Thread types

Among the works of art in our country, wood carving has long been the most common and beloved among the people. Carvings decorated dwellings and ships, furniture, dishes, tools - spinning wheels, sewing machines, rollers. Folk wooden toys are distinguished by the brightness of images, accurate observation, subtle humor and a genuine sense of beauty.

The centuries-old culture of artistic wood carving has national traditions that are passed down from generation to generation when decorating wooden houses with carvings, creating household and decorative products. The best samples of such products, created by folk carvers, are carefully stored in the museums of our country.

Wood remains a favorite material for artists to this day. Sculpture, carved decorative and utilitarian-decorative objects are created from it. In the field of artistic processing of wood, folk craftsmen and professional artists work, training of personnel is organized in an organized manner.

There are many types of woodcarving, which can be divided into the following main groups: flat or recessed; flat-relief; embossed; slotted, or openwork; sculptural, or voluminous; brownie (ship).

Each of these groups, in turn, is divided according to the pattern and technique of execution into varieties.

Flat serrated thread

A flat thread is characterized by the fact that its background is the flat surface of the product or workpiece being decorated, and the pattern is formed by depressions of various shapes - notches. The lowest points of the relief are located below the level of the decorated surface, and the upper points are at its level. Depending on the shape of the recesses and the nature of the pattern, flat-notched threads can be geometric or contour.

Geometric carving - one of the oldest types of woodcarving. It is made in the form of two-, three- and four-sided recesses, forming on the surface a pattern of geometric shapes - triangles, squares, circles.

In ancient times, each geometric figure and their various combinations had their own symbolic meaning. So, a rosette with rays was a symbol of the sun. Centuries passed, the concept of beauty developed, geometric elements formed into ornaments. From the simplest cuts (cuts) made with one tool (knife-knife), carvers learned to create the richest patterns used to decorate various household items.

Figure 1 shows fragments of old Russian spinning wheels decorated with geometric carvings.

Later, with the development of carving techniques and the emergence of new tools, bracketed notches appeared in geometric carving, made with semicircular chisels. They enriched the compositions of ornaments.

Geometric carving compares favorably with other types of carving by its hollow variety of techniques for decorating a wooden surface. At the same time, this carving is not difficult to perform and, in comparison with relief carving, does not require special knowledge of the theory of drawing, a complex set of tools. Its advantage is also the small depth of the carved pattern, which does not disturb the composition of the product itself.

contour thread characterized by shallow thin dihedral notches running along the entire contour of the pattern. In contrast to geometric carving, contour carving mainly uses pictorial motifs: leaves, flowers, figures of animals, birds. An image made with contour carving looks like an engraved drawing: its cutting lines are rigid, there is almost no play of chiaroscuro. On fig. 2 shows fragments of Russian spinning wheels decorated with contour carvings and bracket cuts.

Contour carving is used most often in combination with other types of carving - geometric, flat-relief, and also with painting. As an independent type, this thread is used to make decorative panels on wood.

When performing contour carving, not only a joint knife is used, but also various chisels. The technique of contour carving requires great attention from the performer, fluency in the instrument and high artistic taste.

relief carving

Flat-relief carving has several varieties: carving with oval contours (oval-shaped, or oblique), carving with a pillow background, carving with a selected (selected) background. A common feature for them is a low conditional relief located in one plane at the level of the decorated surface. Flat-relief carving is, as it were, a transitional view from contour to relief carving.

oval carving, as well as contour, it is made in the form of dihedral recesses along the contour of the pattern, but the recesses are cut deeper, and their edges are rounded (ovalized). As a rule, on the side of the ornamental forms, the recesses are cut and oval steeper, and on the side of the background, they are more sloping (Fig. 3).

In some cases, the background is rolled up so that it does not remain flat anywhere. Such a background is called pillow, and carving -oval with pillow background. According to the technique of execution, appearance and purpose, this thread differs little from the usual oval thread.

relief carving with selected background performed in the same way as the usual zaovalnaya. the forms of the ornament remain flat, while the edges of the forms are steeply oval. The background in this thread is chosen to a shallow depth. The ornament, as it were, lies on a flat plane. The background is sometimes minted (Fig. 4). The play of chiaroscuro here is somewhat richer than in the ovalized carving, but also small. Therefore, flat relief carving is performed mainly on small objects and finished with polishing.

In the development of flat-relief carving, the so-called Abramtsevo-Kudrinskaya carving, which arose at the end of the 19th century, played an important role. in the Abramtsevo estate near Moscow, where a wood carving workshop was organized. Many craftsmen who worked and studied in Abramtsevo lived in the neighboring village of Kudrino, so the carving was called Abramtsevo-Kudrinskaya.

A great influence on the formation of the Abramtsevo-Kudrinskaya carving was exerted by the work of the talented folk carver V.P. Vornoskov, who left the Abramtsevo workshop. Vornoskov's works are characterized by plant motifs with rounded leaves (the so-called "finger" carving), a flat polished ornament that almost completely covers the surface, and a matte tinted background with a embossed pattern of dots.

The traditions of the old masters are still preserved in the works of the carvers of the Khotkovo factory of art products made of wood and bone, created on the basis of the former Abramtsevo workshops. A sample of modern Kudrin thread is shown in fig. 5.

relief carving

Relief carving is performed by trimming a flat ornament left on a deep background and working out the forms on the surface of this ornament. Relief carving has almost no flat surface. The forms of the ornament are revealed by the relief of different heights.

Distinguish bas-relief carving - threads with low relief and high relief carving - with a higher relief, more pronounced and with a richer play of chiaroscuro.

Relief carving is very expressive and decorative. In the past, it was widely used to decorate interiors - wall panels, portals, doors, as well as in furniture. At present, relief carving is also used to decorate the interiors of public buildings in the form of wall panels (Fig. 6). Relief carving is also used in the manufacture of modern art furniture: on the backs of chairs, on cabinet furniture in the form of overhead decorative elements.

slotted thread

A slotted thread is a thread in which the background has been removed. Slotted carving can be performed both in the technique of flat-relief carving (with a flat ornament) and in the technique of relief carving.

Flat slotted carving was often used to decorate antique Russian furniture. On fig. 7 shows an armchair made of pine wood with flat slotted and contour carvings (end of the 17th century).

When using such a thread in lockers and screens, a bright fabric is placed under it as a background.

It is much easier to make a thread of this type than to cut it deaf, that is, on a workpiece. For work, drills of different diameters, a jigsaw or a narrow hacksaw are most often used, and less often - some incisors, most of all flat and semicircular chisels. It is better to use jigsaws with fine teeth, they cut less productively, but they drank cleaner.

To set the jigsaw saw blade in the cut-out places inside the parts, you first have to drill holes of the desired diameter. Since you often have to rearrange the jigsaw blade, one end of the saw blade is made with a hook.

A slotted thread is a normal thread with a fully selected background. With a neat and clean execution, this gives the details delicacy and lightness. Such a thread can be geometric, contour with a blocky background. She is decorated with cornices, platbands, piers, doors, gates, as well as various fences.

Cutting out any ornaments is many times easier and faster than cutting them out with a selection of the background, over-sharp contours, as in blind carving.

It happens that the sawn ornament does not always turn out to be clean and even, so its edges are slightly rounded on the back side, cutting off a narrow chamfer. In general, house carving looks good at some distance from the house.

Depending on the ornament of the part, you have to drill a lot of various holes of various shapes. Round ones are drilled with a drill of the required diameter, and holes of a different shape are first drilled and then cut out with chisels of different widths and shapes, chisels and knives with narrow blades. This technique is easier, more convenient and more productive.

When carving, wood is often chipped from the back (reverse) side. To prevent this from happening, the workpiece should be strengthened on a planed board.

Wood is often cut in two steps. First, a rough cut is made with an indent from the lines of the ornament by 1 ... 2 mm, and then it is cut cleanly along the line of the ornament. The tool should be sharp, put it with a slight inclination into the hole, cutting the wood at a very slight angle. This method facilitates the work and gives a cleaner cut surface.

In slotted carvings, the chamfer is often cut from the back of the part, smoothing out jagged edges and removing chipped wood. The width of the chamfer depends on the pattern of the ornament and the thickness of the part. Carved details perform differently. First of all, a template or stencil is applied to the workpiece, the pattern of the ornament is transferred to it with a simple pencil and the carving is started. You can first process the part from the outside, and then from the inside, but you can do the opposite.

To insert a saw blade, first drill a hole. The workpiece is placed directly on the workbench and they work with a saw from top to bottom or install a special stand made of a thick board about 1 m long, to which four racks 250 ... 300 mm high are attached with a distance of 50 mm between them.

For racks in the board, four through holes are drilled or hammered with a diameter (section) of 40 ... 50 mm. A workpiece is placed between the posts and, if necessary, secured with wedges that are inserted between the posts and the workpiece. So that the ends of the racks do not diverge, wooden or wire clamps are sometimes put on top of them.

The stand can be attached to the workbench with clamps, nails, screws.

During operation, the teeth of hand-held jigsaws should cut wood in a direction away from themselves, and a foot jigsaw should cut from top to bottom.

The foot jigsaw is arranged as follows. In a workbench or board, a hole is made with a width of not more than 1 mm, along which a jigsaw must walk. On the back (smooth) side of the jigsaw, or butt, a steel plate is attached or a nail is hammered. This is necessary so that the saw, when pressed on it, does not crash into the wood with its reverse side. A twisted spring is hung over the hole or a trunk or bough of a tree made of springy wood is strengthened. A pedal is attached to the floor. One end of the jigsaw is attached through a leash, that is, a piece of wire, to the pedal, and the other end, also through the leash, to the spring. The teeth of the saw should be pointing down, that is, towards the floor.

When you press the pedal, the saw blade moves down and cuts through the wood. When the pedal is released, the saw springs up. At this time, the workpiece is held by hand and directed at risk to the saw blade. To make the saw stable, bosses are attached above the hole in the workbench or board - guides, and the saw blade passes this place without bending.

The made slotted thread is fixed at some distance from the wall so that it can be better seen against its background.

The overhead thread is a part made with a slotted thread. They are fastened with nails close to the structures of the house: to walls, piers, under windows, above windows, to shoulder blades, that is, boards nailed to the corners of walls, door or gate pillars, etc. Nail heads can be flattened and drowned in wood. Such a thread can be seen better than a deaf one.

Cleaner threading is recommended, especially on the back side. It is advisable not to chamfer it, so it is best to drill holes from both sides. As soon as the center of the drill (point) appears on the back side, the workpiece is turned over and drilled from the back side. In the same way, chiselling or cutting wood is performed. Unwanted wood chipping does not happen. The manufactured parts are tightly adjacent to the walls, preferably sheathed with wood, which creates a solidity of products.

To avoid rusty streaks from nail heads, it is recommended to coat the latter with drying oil.

The background in the slotted thread is removed with a chisel or saw. In the latter case, the thread is called propyl. Since this operation can be mechanized, saw thread is used in the mass production of furniture.

Welt carving with relief ornament is called openwork. Such carvings were widely used to decorate baroque and rococo furniture in the late 17th and 18th centuries. (Fig. 8). The execution of such a thread requires high skill.

Sometimes slotted carvings are glued to a wooden base. In this case, it is called a consignment note or a sticker.

sculptural carving

Sculptural or three-dimensional carving is characterized by the fact that in it the relief image is partially or completely separated from the background, turning into a sculpture. In contrast to the one-sided image of an object in a flat-relief and relief carving, in a three-dimensional carving, the object is depicted comprehensively.

Sculptural carving has a thousand-year history. Since ancient times, man has embodied his religious ideas in the figures of gods and spirits. Fantastic ideas about nature also manifested themselves in the forms of household items. So, in the form of boat-shaped ladles with the head of a duck or a horse, the ancient myth of a fiery chariot in which the sun made its way was reflected: during the day, horses were harnessed to it across the sky, and at night - in the underground - underground kingdom - fantastic birds.

With the advent of Christianity, sculptural images of saints appeared, which were often brightly painted and served as decorations for numerous temples.

Love for humor, jokes, and sometimes sharp satire was embodied in a wooden toy, which was very popular in many parts of our country. The toy makers of Zagorsk and the village of Bogorodskoe gained particular fame. A feature of Bogorodsk carving is a patterned study of the surface of the product, imitating the skin of an animal or the plumage of birds. On fig. 9 shows one of the works of Bogorodsk carvers.

Sculptural carving was widely used to decorate interiors and furniture of classical styles. The legs of chairs and armchairs were often made in the form of animal paws, the armrests of the chairs were decorated with figures of fantastic animals and birds.

house carving

House carving is characterized by the fact that it is large-scale, performed mainly on softwood with an ax, saw and chisels, and is used to decorate wooden buildings.

Although house carving was already developed in the 16th century, samples dating back to the 19th century have come down to us. Wooden buildings, decorated with carvings, have survived mainly in the north of our country and in the Volga region.

It is believed that carved decorations for residential buildings came from wooden ships, so house carving is also called ship carving. By the nature and technique of execution, house carving is embossed, slotted (openwork) and volumetric.

Blind relief carvings - carvings with an uncut (deaf) background and a high relief pattern - were used to decorate the pediments of houses and window architraves (Fig. 10). The motifs of the carving were most often floral ornaments, where the leaves curl in steep counter spirals, they are connected and at the same time separated by flower rosettes. Among the leaves and flowers, images of shoreline mermaids, lions, and phoenix birds were often inserted. The slotted, or sawn, brownie appeared in the middle of the 19th century. It was done with a jigsaw. Openwork valances decorated the pediments of houses, window frames, framed entrances, railings.

An example of a three-dimensional house carving is the so-called "okhlupen" - a figured image of the head and upper body of a horse, deer, large bird, which was cut from a whole rhizome with an ax and placed on the crest of the roof above the pediment, and earlier they decorated the bow of the ship.

Table 1.2.1

№ p/n	thread type	Thread profile (some options)	Symbolic image of the thread	Standard	Designation examples	Threaded Connection Designation Examples
1	2	3	4	5	6	7
1	Metric
2	Metric conical
3	Pipe cylindrical
4	Pipe conical
5	Conical inch
6	Trapezoidal
7	stubborn
8	Round
9	Rectangular

1.2.1. Metric thread
Metric thread (see Table 1.2.1) is the main type of fastener thread. The thread profile is established by GOST 9150-81 and is an equilateral triangle with a profile angle α = 60°. The thread profile on the rod differs from the thread profile in the hole by the amount of blunting of its peaks and troughs. The main parameters of the metric thread are: nominal diameter - d(D) and thread pitch R, installed by GOST 8724-81.
According to GOST 8724-81, each nominal thread size with a large pitch corresponds to several small pitches. Fine-pitch threads are used in thin-walled connections to increase their tightness, to carry out adjustments in precision mechanics and optics devices, in order to increase the resistance of parts to self-unscrewing. In the event that the diameters and pitches of the threads cannot satisfy the functional and design requirements, ST SEV 183-75 "Metric thread for instrumentation" is introduced. If several pitch values ​​correspond to one diameter, then large pitches are applied first. Diameters and thread pitches given in brackets are not used if possible.
In the case of using a conical metric (see Table 1.2.1) thread with a taper of 1:16, the thread profile, diameters, pitches and main dimensions are established by GOST 25229-82. When connecting an external tapered thread to an internal cylindrical thread, according to GOST 9150-81, the external tapered thread must be screwed in to a depth of at least 0.8.

1.2.2. Inch thread
Currently, there is no standard that regulates the main sizes of inch threads. The previously existing OST NKTP 1260 was canceled, and the use of inch threads in new developments is not allowed.
An inch thread is used in the repair of equipment, since parts with an inch thread are in operation. The main parameters of an inch thread are: the outer diameter, expressed in inches, and the number of steps per inch of the length of the cut part of the part.

1.2.3. Pipe straight thread
In accordance with GOST 6367-81, a cylindrical pipe thread has an inch thread profile, i.e. an isosceles triangle with an apex angle of 55 ° (see Table 1.2.1).
Threads are standardized for diameters from 1/16" to 6" in number of pitches z from 28 to 11. The nominal thread size is conditionally related to the inner diameter of the pipe (to the nominal bore). So, a thread with a nominal diameter of 1 mm has a nominal diameter of 25 mm, and an outer diameter of 33.249 mm.
Pipe threads are used to connect pipes, as well as thin-walled cylindrical parts. This kind of profile (55 °) is recommended for increased requirements for the density (impermeability) of pipe joints. Pipe threads are used when connecting the cylindrical thread of the coupling to the conical thread of the pipes, since in this case there is no need for various seals.

1.2.4. Pipe taper thread
The parameters and dimensions of pipe conical threads are determined by GOST 6211-81, according to which the thread profile corresponds to the profile of an inch thread (see Table 1.2.1). The thread is standardized for diameters from 1/16" to 6" (in the main plane, the thread dimensions correspond to the dimensions of the cylindrical pipe thread).
Threads are cut on a cone with a taper angle j / 2 \u003d 1 ° 47 "24" (as for a metric conical thread), which corresponds to a taper of 1:16.
A thread is used for threaded connections of fuel, oil, water and air pipelines of machines and machine tools.

1.2.5. Trapezoidal thread
The trapezoidal thread has the shape of an isosceles trapezoid with an angle between the sides equal to 30° (see Table 1.2.1). The main dimensions of the diameters and pitches of a trapezoidal single-start thread for diameters from 10 to 640 mm are established by GOST 9481-81. Trapezoidal thread is used to convert rotational motion into translational motion under significant loads and can be single- and multi-start (GOST 24738-81 and 24739-81), as well as right and left.

1.2.6. Thrust thread
The thrust thread, standardized by GOST 24737-81, has a profile of an unequal trapezoid, one of the sides of which is inclined to the vertical at an angle of 3 °, i.e. the working side of the profile, and the other at an angle of 30 ° (see Table 1.2. 1). The shape of the profile and the value of the pitch diameters for a thrust single-start thread are established by GOST 10177-82. The thread is standardized for diameters from 10 to 600 mm in increments of 2 to 24 mm and is used for large one-sided forces acting in the axial direction.
1.2.7. round thread
Round threads are standardized. The profile of a round thread is formed by arcs interconnected by sections of a straight line. The angle between the sides of the profile α = 30° (see Table 1.2.1). The thread is used to a limited extent: for water fittings, in some cases for hooks of cranes, as well as in conditions of exposure to an aggressive environment.

1.2.8. Rectangular thread
Rectangular threads (see Table 1.2.1) are not standardized because, along with the advantages of higher efficiency than trapezoidal threads, they are less durable and more difficult to manufacture. It is used in the manufacture of screws, jacks and lead screws.

1.3. Conditional image of the thread. GOST 2.311-68
The construction of a helical surface in a drawing is a lengthy and complex process, therefore, in the drawings of products, the thread is depicted conditionally, in accordance with GOST 2.311-68. The helix is ​​replaced by two lines - a solid main line and a solid thin line.
Threads are divided according to their location on the surface of the part into external and internal.

1.3.1. Symbolic image of a thread on a rod

Fig.1.3.1.1

The external thread on the rod (Fig. 1.3.1.1) is depicted by solid main lines along the outer diameter and solid thin lines along the inner diameter, and on images obtained by projecting onto a plane perpendicular to the axis of the rod, a thin line is drawn on 3/4 of the circle , and this line can be open anywhere (it is not allowed to start a solid thin line and end it on the center line). The distance between a thin line and a solid main line should not be less than 0.8 mm and more than the thread pitch, and the chamfer is not shown in this view. The thread boundary is applied at the end of the complete thread profile (before the start of the run) with a solid main line, if it is visible. The thread run, if necessary, is depicted as a solid thin line.

Fig.1.3.1.2?

For technological reasons, thread undercutting can be carried out on a part of a part (rod). In total, the thread undercut and the runaway are the thread undercut (GOST 10548-80). The size of the thread length is indicated, as a rule, without a run.

1.3.2. Symbolic image of a thread in a hole

Fig.1.3.2.1

Internal thread - it is depicted as a solid main line along the inner diameter and a solid thin line along the outer one. If, when depicting a blind hole, the end of the thread is close to its bottom, then it is allowed to depict the thread to the end of the hole. Threads with a non-standard profile should be depicted.

1.3.3. Symbolic image of the thread assembly

Fig.1.3.3.1

On sections of a threaded connection in the image on a plane parallel to its axis in the hole, only that part of the thread is shown that is not covered by the thread of the rod.
Hatching in cuts and sections is carried out to a solid main line, i.e. to the outer diameter of the outer thread and the inner diameter of the inner thread.

1.4. Conditional image of threads
Table 1.4.1

thread type	Symbol for thread type	Dimensions indicated on the drawing	Thread designation in drawings
			on images in a plane parallel to the thread axis		on images in a plane perpendicular to the thread axis
			on the rod	in the hole	on the rod	in the hole
Metric coarse pitch GOST 9150-81	M	Outer diameter (mm)
Metric fine pitch GOST 9150-81	M
Trapezoidal single-thread GOST 9484-81 (ST SEV 146-78)	Tr	Outer diameter and thread pitch (mm)
Pipe cylindrical GOST 6357-81 (ST SEV 1157-78)	G
Conical inch GOST 6111-52	K	Symbol in inches
Pipe conical GOST 6211-81 (ST SEV 1159-78): external and internal	R Rc	Symbol in inches

To designate threads, standards for individual types of threads are used. For all threads, except for conical and cylindrical pipe threads, the designations refer to the outer diameter and are affixed above the dimension line, on its continuation, or on the shelf of the leader line. The designations of conical threads and cylindrical pipe threads are applied only on the shelf of the leader line.
The thread in the drawing is conventionally designated in accordance with the standards for the image, diameters, steps, etc.
Metric thread is designated in accordance with GOST 9150-81.
Metric thread subdivided into threads with a large pitch, denoted by the letter M indicating the nominal diameter of the cylindrical surface on which the thread is made, for example M12, and a thread with a fine pitch, indicated by indicating the nominal diameter, thread pitch and tolerance field, for example M24 × 2-6g or M12 × 1-6H.
When designating a left-hand thread, LH is placed after the conditional designation.
Multi-start threads are designated, for example, three-start, М24×З(P1)LH, where M- thread type, 24 - nominal diameter, 3 - thread stroke, P 1 - thread pitch. The given designations of left-hand and multi-start threads can be applied to all metric threads.
Metric taper thread designated in accordance with GOST 25229-82. The thread designation includes the letters MK. Connections of an internal cylindrical thread with an external conical thread are used. The dimensions of the profile elements of conical and cylindrical threads are taken in accordance with GOST 9150-81. This type of connection must ensure that the taper thread is screwed in to a depth of at least 0.8 l(Where l- thread length without run-out). The designation of an internal cylindrical thread consists of a nominal diameter, pitch and standard number (for example: M20 × 1.5 GOST 25229-82).

Fig.1.4.1

The connection of an internal cylindrical thread with an external conical thread (Fig. 1.4.1) is indicated by the M / MK shot, nominal diameter, pitch and standard number: M / MK 20 × 1.5LH GOST 25229-82. In the absence of special requirements for the density of connections of this kind or when seals are used to achieve the tightness of such connections, the standard number in the designation of the connections is omitted, for example: M / MK 20 × 1.5 LH.
The tolerance field for the average diameter of the internal cylindrical thread must correspond to 6N according to GOST 16093-81, and the maximum deviation of the internal diameter and cut of the hollows of the internal cylindrical thread is taken within: the upper limit deviation (+0.12) -g - (+0.15), and the lower limit deviation is 0.
Pipe cylindrical thread. Thread symbol consists of a letter G, designation of the thread size, accuracy class of the average diameter ( A or IN). For left-hand threads, the symbol LH is used. For example, G1½LH-B-40 make-up length, if required.
The connection of an internal pipe cylindrical thread of accuracy class A with an external pipe conical thread according to GOST 6211-81 is indicated as follows: for example, G / Rp-1½-A.
When designating landings, the numerator indicates the accuracy class of the internal thread, and the denominator indicates the external thread. For example: G 1½-A/B.
Pipe taper thread. The thread designation includes the letters: R- for conical external thread, R c - for tapered internal thread, R p - for cylindrical internal threads and thread size designation. For left-hand threads, the letters LH are added. The conditional size of the thread, as well as its diameters, measured in the main plane, correspond to the parameters of a cylindrical pipe thread having the same conditional size. Therefore, parts with pipe conical threads are quite often used in connections with parts with cylindrical pipe threads, which ensures a sufficiently high tightness of the joints. Threaded connections are designated as a fraction, in the numerator of which the letter designation of the internal thread is indicated, and in the denominator - the external one. Example of notation:

G/R * 1½ - A

- internal pipe cylindrical thread of accuracy class A according to GOST 6357-81.
Trapezoidal carving. Trapezoidal thread symbol consists of letters Tr, nominal diameter, stroke R n and step R. For example: Tr20 × 4LH-8H, where LH is the designation of the left thread, 8H is the main thread deviation.
If necessary, after the main deviation of the thread, the length of the make-up is indicated L(in mm). For example: Tg40×6-8g-85; 85 - make-up length.
The carving is persistent. The thread designation consists of the letter S, nominal diameter, pitch and basic deviation S80×10-8N.
For a left-hand thread, the letters LH are indicated after the thread symbol.
For a multi-start thread, an additional stroke value is entered together with the letter R and step value. So, a two-start thread with a pitch of 10 mm is designated S80 × 2 (P10).
Rectangular thread not standardized. When depicting a rectangular thread, it is recommended to draw a local section on which the necessary dimensions are put down.
Special threads. If the thread has a standard profile, but differs from the corresponding standard thread in diameter or pitch, then the thread is called special. In this case, the inscription is added to the thread designation sp, and the thread designation indicates the dimensions of the outer diameter and thread pitch, for example: Sp.M19 × 1D thread making.

Thread classification

Table 1

	thread type	Thread profile (some options)	Symbolic image of the thread	Standard	Designation examples	Threaded Connection Designation Examples
	Metric
	Metric conical
	Pipe cylindrical
	Pipe conical
	Conical inch
	Trapezoidal
	Rectangular

1.1 Metric thread

Metric thread (see Table 1.2.1) is the main type of fastening thread. The thread profile is established by GOST 9150–81 and is an equilateral triangle with a profile angle b = 60°. The profile of the thread on the rod differs from the profile of the thread in the hole by the amount of blunting of its tops and troughs. The main parameters of a metric thread are: nominal diameter - d (D) and thread pitch - P, established by GOST 8724–81.

According to GOST 8724–81, each nominal thread size with a large pitch corresponds to several small pitches. Fine-pitch threads are used in thin-walled connections to increase their tightness, to carry out adjustments in precision mechanics and optics devices, in order to increase the resistance of parts to self-unscrewing. In the event that the diameters and pitches of the threads cannot meet the functional and design requirements, ST SEV 183-75 "Metric thread for instrumentation" is introduced. If several pitch values ​​correspond to the same diameter, then large pitches are applied first. Diameters and thread pitches given in brackets are not used if possible.

In the case of using a conical metric (see Table 1.2.1) thread with a taper of 1:16, the thread profile, diameters, pitches and main dimensions are established by GOST 25229–82. When connecting an external tapered thread to an internal cylindrical thread, according to GOST 9150–81, the external tapered thread must be screwed in to a depth of at least 0.8.

1.2 Inch thread

Currently, there is no standard that regulates the main dimensions of an inch thread. The previously existing OST NKTP 1260 was canceled, and the use of inch threads in new developments is not allowed.

An inch thread is used in the repair of equipment, since parts with an inch thread are in operation. The main parameters of an inch thread are the outer diameter, expressed in inches, and the number of steps per inch of the length of the cut part of the part.

1.3 Parallel pipe thread

In accordance with GOST 6367–81, a cylindrical pipe thread has an inch thread profile, i.e. an isosceles triangle with an apex angle of 55 ° (see Table 1.2.1).

The thread is standardized for diameters from "to 6" with the number of steps z from 28 to 11. The nominal thread size is conditionally related to the inner diameter of the pipe (to the nominal bore). So, a thread with a nominal diameter of 1 mm has a nominal diameter of 25 mm, and an outer diameter of 33.249 mm.

Pipe threads are used to connect pipes, as well as thin-walled cylindrical parts. This kind of profile (55°) is recommended for increased requirements for tightness (impermeability) of pipe joints. Pipe threads are used when connecting the cylindrical thread of the coupling with the conical thread of the pipes, since in this case there is no need for various seals.

1.5 Tapered pipe thread

The parameters and dimensions of pipe taper threads are determined by GOST 6211–81, according to which the thread profile corresponds to the profile of an inch thread (see Table 1.2.1). The thread is standardized for diameters from 1/16" to 6" (in the main plane, the thread dimensions correspond to the dimensions of the cylindrical pipe thread).

Threads are cut on a cone with a taper angle φ / 2 = 1 ° 47 "24" (as for a metric taper thread), which corresponds to a taper of 1:16.

The thread is used for threaded connections of fuel, oil, water and air pipelines of machines and machine tools.

1.6 Trapezoidal thread

The trapezoidal thread has the shape of an isosceles trapezoid with an angle between the sides equal to 30° (see Table 1.2.1). The main dimensions of the diameters and pitches of a trapezoidal single-start thread for diameters from 10 to 640 mm are established by GOST 9481-81. The trapezoidal thread is used to convert to translational under significant loads and can be single and multiple (GOST 24738–81 and 24739–81), as well as right and left.

1.7 Thrust thread

The thrust thread, standardized by GOST 24737–81, has a profile of an unequal trapezoid, one of the sides of which is inclined to the vertical at an angle of 3 °, i.e. the working side of the profile, and the other at an angle of 30 ° (see Table 1.2.1) . The shape of the profile and the value of the pitch diameters for a thrust single-start thread are established by GOST 10177–82. The thread is standardized for diameters from 10 to 600 mm in increments of 2 to 24 mm and is used for large one-sided forces acting in the axial direction.

1.8 Round thread

Round threads are standardized. The profile of a round thread is formed by arcs interconnected by sections of a straight line. The angle between the sides of the profile b = 30° (see Table 1.2.1). The thread is used to a limited extent: for fittings, in some cases for hooks of cranes, as well as in conditions of exposure to an aggressive environment.

1.9Rectangular thread

Rectangular threads (see Table 1.2.1) are not standardized because, along with the advantages of higher efficiency than trapezoidal threads, they are less durable and more difficult to manufacture. It is used in the manufacture of screws, jacks and lead screws.

Threaded cutters and combs

Threaded cutters are used for cutting all types of threads and have the following advantages: simple design, manufacturability and versatility. The last advantage is that the same cutter can cut external and internal threads of various diameters and pitches on cylindrical and conical surfaces.

Threaded cutters work according to the copying method, so the profile of their cutting edges must match the profile of the root of the thread being cut. In order to increase productivity, a generator cutting circuit is also sometimes used.

Removal of the allowance in the process of thread cutting is carried out under conditions of non-free cutting with a high degree of deformation of the material being removed. In this case, the formation of the thread is carried out, as a rule, in several passes at small sections of the cut chips. In this regard, the productivity of the threading process is low, so threading tools are mainly used in single-piece and small-scale production.

Being a shaped tool, threading cutters can be of three types: core, prismatic and round.

On fig. 1 shows typical designs of rod-type threaded cutters:

solid high speed steel; with brazed hard-alloy plate; with mechanical fastening of a specially shaped carbide insert used for cutting external and internal threads.

Rice. 1. Types of rod threading tools:

a - from high-speed steel; b - with brazed hard-alloy plate; in - with mechanical fastening of a hard-alloy plate.

With multi-pass cutting of acute-angled threads with cutters, the formation of a thread profile can be carried out according to three schemes (Fig. 2): a) profile - with a radial feed of the cutter; b) generator - with the supply of the cutter at an angle to the axis of the workpiece; c) combined, consisting of feed at an angle during roughing and radial feed - during finishing (final) machining.

The advantage of the generator circuit is the increase in the thickness of the cut layer in one pass by 2 times, which provides a corresponding reduction in passes. The right edge in this case works as an auxiliary edge, leaving steps on the machined surface. This shortcoming makes it possible to correct the use of the combined scheme.

Rice. 2. Cutting patterns used in threading:

a - profile; b - generator;
c - combined; g - for cutting trapezoidal threads

When cutting threads with a deep profile, for example, trapezoidal threads, the formation of threads in preliminary operations is carried out with cutters with different cutting edge profiles, as shown in Fig. 2, Mr.

Rod cutters usually have a small margin for regrinding and their installation relative to the workpiece is associated with certain difficulties that do not arise when using shaped prismatic and round thread cutters.

Combs (Fig. 3) are multi-thread shaped cutters that can be rod, prismatic, round. They are mainly used for cutting fastening threads with a fine pitch, i.e. threads with a small profile height.

As shown in fig. 3 g, the cutting part of the combs consists of a chamfer with a length l1 sharpened at an angle ц to the axis and a calibrating part l2

where P is the thread pitch.

Rice. 3. Thread cutting dies:

a - rod with mechanical fastening of a hard-alloy plate;
b - prismatic; in - round; g - working part of the comb

At the beginning of the working stroke, the comb has a radial infeed and then moves along the axis of the rotating workpiece with a feed per revolution equal to the pitch.

Thread cutters

In the practice of mechanical engineering, the following main types of thread-cutting cutters are used:

comb, disc, threading heads.

The use of milling instead of turning for external and internal threading provides a significant increase in productivity due to:

1) the use of a multi-toothed tool with a large total active length of the cutting edges that simultaneously remove chips (comb cutters);

2) increasing the thickness of the cut by one tooth (disc cutters);

3) increasing the cutting speed by equipping the cutters with a hard alloy (threading heads).

Comb cutters (Fig. 4) are used for cutting acute-angled external and internal threads with a fine pitch on cylindrical and conical surfaces of workpieces. In fact, they are a set of disk cutters made in one piece on one body with a tooth profile corresponding to the thread profile. To form teeth along the axis of the cutter, either straight or helical flutes are cut.

	A)
	b)
V)

Rice. 4. Comb thread cutters:

a - cylindrical mounted; b - cylindrical end; c - for cutting conical threads.

The disadvantage of comb cutters is the distortion of the profile angle of the thread being cut due to the mismatch between the trajectory of the points of the cutting edges of the cutter and the thread curve obtained in a section perpendicular to the axis of the workpiece.

Disc cutters have found application in threading large depths, diameters and lengths. For example, they are often used when threading worms, lead screws, etc.

Fig.5 Scheme of installation of a disk cutter relative to the workpiece

When threading, the axis of the mandrel of the disk cutter is set at an angle φ to the axis of the workpiece, equal to the angle of the thread on its average diameter (Fig. 5). The cutter performs, and the workpiece - rotational and translational movements along its axis with a feed per revolution equal to the thread pitch.

Taps are widely used in mechanical engineering for cutting threads in workpiece holes and are very diverse in design and geometric parameters.

A tap is a screw turned into a tool by cutting flutes and creating front, back and other angles on the cutting teeth. For fastening on the machine or in the collar, it is equipped with a shank. The cutting part of the tap is most often made of high-speed steel, less often of hard alloy.

Cutting conditions for chip removal with a tap are very difficult due to tight cutting, high cutting and friction forces, and difficult chip removal conditions.

The advantages of taps are: simplicity and manufacturability of the design, the possibility of thread cutting due to self-feeding, high thread accuracy, determined by the accuracy of tap manufacturing.

By design and application, taps are divided into the following types:

1) manual (locksmith) - with a manual drive, made in sets of two or three numbers;

2) machine-manual single or in a set of two numbers - with a manual or machine drive;

3) machine single - with a machine drive;

4) nut - for cutting threads in nuts on special machines;

5) dies - for cutting and, accordingly, calibrating threads in thread-cutting dies;

6) special - for cutting threads of various profiles: trapezoidal, round, thrust, etc., as well as prefabricated adjustable, broach taps, conical taps, etc.

The main parts of the tap (Fig. 6) are: cutting (intake) and calibrating parts, chip grooves, number of feathers and teeth, shank with fasteners.

b)

Rice. 6. Taps: a - the main elements of the tap; b - photograph of the tap.

The cutting part of the tap performs the main work of cutting the allowance, forming the profile of the thread being cut and removing chips from the cutting zone. It determines the accuracy of the thread and the durability of the taps.

A thread-cutting die is a nut turned into a cutting tool by drilling chip holes and forming front and rear corners on the teeth of the cutting feathers.

Dies are used for cutting external threads on bolts, screws, studs and other fasteners. According to the shape of the outer surface of the die, there are: round, square, hexagonal, pipe. For plumbing work, they are cut and clamped in the knobs.

The most widely used are round dies, as the most technologically advanced and easy to operate. They are made from calibrated high-speed steel bars on automatic bar lathes.

On fig. 7 shows the design of a round die and its main design and geometric parameters. Structural parameters: die outer diameter D thickness B, diameters of chip holes dc and circumferences of their centers dc, clearance width c, pen width b, minimum wall thickness e. Geometrical parameters of the die: front angle r, rear angle b and angle of the intake cone c. On the outer surface of the die there are 3 or 4 conical recesses with an angle at the top of 90° for fastening in a collar or ring. On the same surface of the dies, a trapezoidal groove with an angle of 60° is made, forming a bridge with a thickness of m = 0.4 ... 1.5 mm, which is cut after two or three regrinding of the dies.

A)

b)

Rice. 7. Dies: a - structural elements of a round die, b - photo of a die

Abstract questions.

Name the types of threads. Characteristics of a metric thread. Characteristics of inch thread. Characteristics of cylindrical pipe threads. Characteristics of pipe conical thread. Characteristics of trapezoidal thread. Characteristics of a persistent thread. Characteristics of a round thread. Characteristics of a rectangular thread. The use of threaded cutters. Definition of combs and their application. Name the types of thread cutters. Definition of a tap. Types of taps. Plate definition.

List of used literature.

, “Technology of precision” - M., Higher school, 1973. , “Technology of mechanical engineering (special part) - M., Mechanical engineering, 1973 “Technology of mechanical engineering” - M., Higher school, Moscow, 1967 Mechanical engineering technology. - M., Engineering 1990

Metric thread(Fig. 120). The main type of fastening thread in Russia is a metric thread with a triangular profile angle a equal to 60°. The dimensions of its elements are given in millimeters.

Rice. 120

According to GOST 8724-81, metric threads for diameters from 1 to 600 mm are divided into two types: with a large pitch (for diameters from 1 to 68 mm) and with a fine pitch (for diameters from 1 to 600 mm).

Coarse pitch threads are used in connections subjected to impact loads. Thread with a fine pitch - in the connections of parts with thin walls and to obtain a tight connection. In addition, fine threads are widely used in adjusting and set screws and nuts, as they make it easier to make fine adjustments.

When designing new machines, only metric threads are used.

Inch thread(Fig. 121). This is a thread of a triangular profile with an angle at the top of 55 ° (a equal to 55 °). The nominal diameter of an inch thread (the outer diameter of the thread on the shank) is indicated in inches. In Russia, inch threads are allowed only in the manufacture of spare parts for old or imported equipment and are not used in the design of new parts.

Rice. 121

Pipe cylindrical threads and GOST 6357-81, is an inch thread with a fine pitch, rounded troughs and a triangular profile with an angle of 55 °. Cylindrical pipe threads are cut on pipes up to 6 ". Pipes over 6" are welded. The profile of a cylindrical pipe thread is shown in fig. 122.

Rice. 122

Rice. 123

Tapered pipe threads are used in two standard sizes. Tapered pipe thread GOST 6211-81, corresponds to a rounded profile of a cylindrical pipe thread with an angle of 55 ° (Fig. 123.1).

Conical inch thread GOST 6111-52 has a profile angle of 60 ° (Fig. 7 123, II). Tapered threads are used almost exclusively in pipe connections to obtain tightness without special sealing materials (linen threads, red lead yarn, etc.).

The theoretical profile of the tapered thread is shown in fig. 124. The taper of the surfaces on which the tapered thread is made is usually 1: 16. The bisector of the profile angle is perpendicular to the axis of the thread.

Rice. 124

Diametral threads of tapered threads are installed in the main plane (2 - end of the coupling), which is perpendicular to the axis and spaced from the end of pipe 1 at a distance I, regulated by the standards for tapered threads (3 - coupling; 4 - pipe end; 5 - pipe axis).

In the main plane, the thread diameters are equal to the nominal diameters of the cylindrical pipe thread. This allows conical threads to be made up with cylindrical threads, since the pitch and profiles of these threads for certain diameters are the same.

Tapered threads have definitions and concepts similar to cylindrical threads, such as outer, middle and inner thread diameters. The thread pitch P h is measured along the axis.

When making up a pipe and a coupling with nominal thread sizes without applying force, the make-up length is equal to l.

The designation of a pipe thread has the peculiarity that the thread size is set not by the diameter on which the thread is cut, but by the inner diameter of the pipe. This inner diameter is called the "clear" diameter of the pipe and is defined as the nominal diameter of the pipe,

Trapezoidal thread GOST 9484-81 (Fig. 125). The thread profile is an isosceles trapezoid with an angle a equal to 30°. Trapezoidal threads are used to transmit axial forces and movement in lead screws. The symmetrical thread profile allows it to be used for reversible screw mechanisms.

Rice. 125

Thrust thread GOST 10177-82 (Fig. 126). The thread profile is an unequal trapezoid with an angle of the working side of 3 ° and a non-working side of 30 °. Thrust thread has high strength and high efficiency. It is used in cargo propellers to transfer large forces acting in one direction (in powerful jacks, presses, etc.).

Rice. 126

In press building, thrust threads are also used. The profile of this thread is somewhat different from the aforementioned thrust thread. The profile of such a thrust thread according to GOST 13535-87 is an unequal trapezoid with a working side angle of 0 ° and a non-working side of 45 °.

Rectangular and square threads (Fig. 127) have a high efficiency and give a large gain in strength, so they are used to transfer axial forces in load screws and movement in lead screws. Rectangular and square threads are not standardized, as they have the following disadvantages: in a bolt-nut connection, it is difficult to eliminate axial runout; they have less strength than a trapezoidal thread, since the base of the coil of a trapezoidal thread with the same pitch is wider than that of a rectangular or square thread; they are more difficult to make than trapezoidal.

Rice. 127

Note. In critical connections, these threads are replaced by trapezoidal ones.

• diameter unit (metric, inch, modular, pitch thread)
• surface location (external and internal thread)
• direction of movement of the helical surface (right, left);
• number of runs (single and multi-start), for example, two-start, three-start, etc.;
• profile (triangular, trapezoidal, rectangular, round, etc.);
• the forming surface on which the thread is located (cylindrical thread and conical thread);
• purpose (fixing, fixing and sealing, chassis, etc.).

Basic thread parameters and units of measurement

Scheme of a cylindrical thread.

Diagram of a conical thread.

Metric thread- with pitch and basic thread parameters in millimeters.

Inch thread- all thread parameters are expressed in inches (most often indicated by a double stroke, placed immediately after the numerical value, for example, 3 "= 3 inches), thread pitch in fractions inches(inch=2.54cm). For pipe inch threads, the size in inches characterizes the clearance in the pipe, and the outer diameter, in fact, is much larger.

Metric and inch threads are used in threaded connections and screw gears.

Modular thread- thread pitch is measured module(m). To get the size in millimeters, it is enough to multiply the module by the number pi ().

Pitch carving- thread pitch is measured in pitches(p"). To obtain a numerical value (in inches), it is enough to divide the number pi () by the pitch.

Modular and pitch threads are used when cutting the worm of a worm gear. The coil profile of a modular worm may look like Archimedean spiral, circle involutes, long or short involute And trapeze.

• step (P)- the distance between the lateral sides of the profile of the same name, measured in fractions meters, in shares inches or threads per inch is the denominator of a common fraction whose numerator is an inch. Expressed as a natural number (for example; 28, 19, 14, 11);
• outer diameter (D, d), the diameter of the cylinder described around the tops of the external (d) or troughs of the internal thread (D);
• average diameter (D 2 , d 2), the diameter of the cylinder, the generatrix of which intersects the thread profile in such a way that its segments formed at the intersection with the groove are equal to half the nominal thread pitch;
• inner diameter (D 1 , d 1), the diameter of the cylinder inscribed in the troughs of the external (d 1) or tops of the internal thread (D 1);
• stroke (Ph) the amount of relative displacement of the initial midpoint along the helix of the thread through an angle of 360°

where is the number of visits;

Thread types

Metric, M

It has a wide range of applications with nominal diameters from 1 to 600 mm and pitches from 0.25 to 6 mm. The profile is an equilateral triangle (the angle at the apex is 60°) with the theoretical height of the profile Н=0.866025404Р. All profile parameters are measured in millimeters.

Standards:

• GOST 24705-2004 (ISO 724:1993)- Metric thread. Main dimensions.
• GOST 9150-2002- Basic norms of interchangeability. The thread is metric. Profile.
• GOST 8724-2002- Basic norms of interchangeability. The thread is metric. Diameters and steps.
• ISO 965-1:1998- Threads metric ISO general purpose. Tolerances. Part 1. Principles and main characteristics.
• ISO 965-2:1998- Threads metric ISO general purpose. Tolerances. Part 2: Thread limits for general purpose bolts and nuts. Average class of accuracy.
• ISO 965-3:1998- Threads metric ISO general purpose. Tolerances. Part 3: Deviations for structural threads.
• ISO 965-4:1998- Threads metric ISO general purpose. Tolerances. Part 4: Dimensional limits for hot dip galvanized external screw threads for assembly with tapped internal screw threads to tolerance position H or G after galvanization.
• ISO 965-5:1998- Threads metric ISO general purpose. Tolerances. Part 5: Dimensional limits for internal screw threads of screws for assembly with hot dip galvanized external screw threads with a maximum tolerance position dimension h before galvanization.
• ISO 68-1- General purpose ISO screw threads. main profile. Metric thread.
• ISO 261:1998- ISO metric threads for general use. General form.
• ISO 262:1998- General purpose ISO metric threads. Selected sizes for screws, bolts and nuts.
• BS 3643- ISO metric screw threads.
• DIN 13-12-1988- Threads metric ISO basic and precision with a diameter of 1 to 300 mm. Choice of diameters and pitches.
• ANSI B1.13M, ANSI B1.18M- Metric thread M with profile based on ISO 68 standard.

Symbol: the letter M (metric), the numerical value of the nominal thread diameter (d, D in the diagram, it is also the external diameter of the thread on the bolt) in millimeters, the numerical value of the pitch (for threads with fine pitch) (P in the diagram) and the letters LH for the left-hand thread . For example, a coarse pitch thread with a nominal diameter of 16 mm is referred to as M16; thread with a nominal diameter of 36 with a fine pitch of 1.5 mm - M36x1.5; the same in diameter and pitch but left-hand thread M36x1.5LH.

Standard Pitch Table for Metric Threads

M0.25	0.075	M1.1	0.25	M5	0.8	M17	2
M0.3	0.08	M1.2	0.25	M5.5	0.8	M18	2.5
M0.35	0.09	M1.4	0.3	M6	1	M20	2.5
M0.4	0.1	M1.6	0.35	M7	1	M22	2.5
M0.45	0.1	M1.8	0.35	M8	1.25	M24	3
M0.5	0.125	M2	0.4	M9	1.25	M25	3
M0.55	0.125	M2.2	0.45	M10	1.5	M26	3
M0.6	0.15	M2.5	0.45	M11	1.5	M27	3
M0.7	0.175	M3	0.5	M12	1.75	M28	3
M0.8	0.2	M3.5	0.6	M14	2	M30	3.5
M0.9	0.225	M4	0.7	M15	2	M32	3.5
M1	0.25	M4.5	0.75	M16	2

Metric taper, MK

Standard: GOST 6042-83 Edison thread is round. Profiles, dimensions and limit dimensions.

Thread symbol: Letter E, thread number, if the thread for non-metallic elements is the letter N through a slash (/) and GOST number, for example E 27 GOST 6042-83 or E 27 / N GOST 6042-83.

Metric EG-M

Inch cylindrical UTS

UTS (Unified Thread Standard) - inch cylindrical thread, widely used in the USA and Canada. Point angle 60°, theoretical profile height H=0.866025P. Depending on the pitch, it is divided into: UNC (Unified Coarse); UNF (Unified Fine); UNEF (Unified Extra Fine); 8 UN; UNS (Unified Special). Extremely common UNC 1/4 (1/4 "x1.25mm). It is present in the mount of almost all modern digital and film cameras and video cameras (as well as tripods) of small format. Its parameters, D = 6.35mm, D 1 = 4.975mm, pitch 20 threads per inch (1.25mm). Before it, a 3/8" thread with a pitch of 16 threads per inch (1.5875mm) D = 9.525mm, D 1 = 7.806mm was just as popular for mounting photographic equipment. Russian standards: GOST 3362-75 "Photo and film cameras. Tripod connection. Connecting dimensions".

Inch BSW

BSW (British Standard Whitworth) - inch thread. It is a British standard, proposed by Joseph Whitworth in 1841, apex angle 55°, theoretical profile height H=0.960491P. A thread with a fine pitch is called: BSF (British Standard Fine).

Inch tubing NPT

OCTG threads

OCTG threads are designed to connect pipes in oil wells. They are conical for high tightness. According to the shape of the profile, there are triangular, with a profile angle of 60 °, and trapezoidal unequal, with angles from 5 ° to 60 ° (the so-called Buttress thread). OCTG threads are generally made to American Petroleum Institute (API) standards. Russian standards: GOST R 53366-2009 - Steel pipes used as casing or tubing for wells in the oil and gas industry. General specifications. GOST 631-65- Drill pipes with upset ends and couplings for them. GOST 632-70- Casing pipes and couplings to them. GOST 633-80- Pump-compressor pipes and couplings to them.

Manufacturing methods

The following threading methods are used:

• blade cutting;
• abrasive processing;
• extrusion by pressing;
• electrophysical and electrochemical processing.

The most common and universal way to obtain threads is blade cutting. It includes:

• cutting external threads with dies;
• tapping of internal threads;
• turning of external and internal threads with threaded cutters and combs;
• thread milling of external and internal threads with disk and worm cutters;
• cutting of external and internal threads with thread-cutting heads;
• vortex processing of external and internal threads.

Rolling is the most productive thread processing method, which ensures high quality of the resulting thread. Thread rolling includes:

• external thread rolling with two or three rollers with radial, axial or tangential feed;
• rolling of external and internal threads with thread rolling heads;
• rolling of external threads with flat dies;
• rolling of external threads with a roller-segment tool;
• rolling (extrusion) of internal threads with chipless taps.

Thread grinding includes grinding with single-thread and multi-thread wheels. It is used to obtain accurate, mostly running threads.

Extrusion by pressing is used to obtain threads from plastics and non-ferrous alloys. Not widely used in industry.

Casting (usually under pressure) is used to obtain low-precision threads from plastics and non-ferrous alloys.

Electrophysical and electrochemical machining (for example, electroerosive, electrohydraulic) is used to obtain threads on parts made of materials with high hardness and brittle materials, such as hard alloys, ceramics, etc.

Historical reference

Scheme of the "threaded" joint in the Trigonopterus beetle

For a long time it was believed that the threaded connection, along with the wheel and gear, is a great invention of mankind, which has no analogue in nature. However, in 2011, a group of scientists published an article in the journal Science on the structure of the joints in weevils of the species Trigonopterus oblongus (English) Trigonopterus ) living in New Guinea. It turned out that the paws of these beetles are connected to the body with the help of a trochanter, which is screwed into a coxa (basin) - an analogue of the hip joint in insects. On the surface of the swivel are protrusions resembling a conical screw. In turn, the surface of the coke is also provided with a threaded recess. Such a connection provides a more reliable fastening of the limbs than a hinged one, and guarantees greater stability for the arboreal insect.

The use of helical surfaces in technology began in ancient times. It is believed that the first screw was invented by Archytas of Tarentum, a philosopher, mathematician and mechanic who lived in the 4th-5th centuries BC. e. The screw invented by Archimedes, which was used to move liquids and loose bodies, is widely known. The first fasteners with threads began to be used in ancient Rome at the beginning of BC. e. However, due to their high cost, they were only used in jewelry, medical instruments, and other expensive items.

Running and fastening threads were widely used only in the Middle Ages. The manufacture of the external thread took place as follows: a rope smeared with chalk or paint was wound onto a cylindrical workpiece, then a helical groove was cut along the resulting spiral marking. Bushings with two or three pins were used instead of female threaded nuts.

In the XV-XVI centuries, the manufacture of three- and four-sided taps for cutting internal threads began. Both mating parts with external and internal threads for make-up were adjusted to each other by hand. Any interchangeability of parts was completely absent.

The prerequisites for thread interchangeability and standardization were created by Henry Maudslay around 1800, when the screw-cutting lathe he invented made it possible to cut precise threads. He made the lead screw and nut for his first machine by hand. Then he turned a screw and a nut of higher precision on the machine. By replacing the first screw and nut with new, more accurate ones, he machined even more precise parts. This continued until the accuracy of the thread ceased to increase.

For the next 40 years, interchangeability and standardization of threads took place only within individual companies. In 1841, Joseph Whitworth developed a system of fastening threads which, thanks to its adoption by many English railway companies, became the national standard for Great Britain, called the British Whitworth Standard ( BSW). The Whitworth standard served as the basis for the creation of various national standards, such as the Sellers standard ( Sellers) in the USA, Loewenhertz threads ( Lowenherz) in Germany, etc. The number of national standards was very large. So, in Germany at the end of the 19th century there were 11 carving systems with 274 varieties.

In 1898, the International Thread Standardization Congress in Zurich defined new international standards for metric threads based on Sellers' threads but with metric dimensions.

In the Russian Empire, there was no standardization of threads at the state level. Each enterprise producing threaded parts used its own standards based on foreign analogues.

The first measures to standardize threads were taken in 1921 by the People's Commissariat of Railways of the RSFSR. Based on the German standards for metric threads, he issued tables of norms NKPS-1 for threads used in railway transport. The tables included metric threads with a diameter of 6 to 68 mm.

In 1927, on the basis of these tables, the Committee for Standardization under the Council of Labor and Defense developed one of the first state standards of the USSR - OST 32.

In the same year, OST 33A was developed for threads according to the Whitworth standard.

By the beginning of 1932, OST for trapezoidal threads was developed based on the modernized American standards Acme ( Acme).

Founded in 1947