RU2492018C1 - Method of barrel production - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in producing 5.45-30 mm-caliber gun barrels. Initial billet is subjected to heat treatment and pre-machining to make a tube billet. Said tube billet has die part and drive part composed of a large and a small cylinder, said parts being made at rube ends. Said small cylinder features length smaller than the height between transition between said large and small cylinders. Tube billet is subjected to radial squeezing at radial squeezer to produce barrel forged piece. Note here that tube drive part is fixed at squeezer driver toothed chuck.

EFFECT: increase in drive center service life by one and a half to two times.

2 cl, 4 dwg

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of trunks with threaded or smooth guide parts.

A known method of manufacturing a barrel, (see the book. Troitsky ND Deep drilling. - L.: Engineering, 1971, S. 140-141). The blank-forgings are pre-treated on the outer surface, their ends are cut, centering necks and control belts are made and deep drilling is carried out. Next, heat treatment is carried out, a deep hole is bored, grooves are made in it, in the breech part it is a chamber and finally processed on the outer surface, getting a finished barrel.

The disadvantages of the analogue are: the length of the initial workpiece is greater than the length of the barrel, taking into account the trimming of the ends and the separation of the template from the muzzle for samples — witnesses; therefore, the difference between the volumes of preliminary and final machining is significant, and the metal utilization coefficient (KIM - the ratio of the mass of the barrel to the mass of the initial billet - η) is not more than 30%.

A known method of manufacturing a barrel, adopted as a prototype (see patent RU No. 2156670 C1, publ. 09/27/2000): first get the original billet (rolled or forged), then it is processed thermally and pre-mechanically to obtain the billet pipe having at the ends a lead-in and a lead-in in the form of a large and small cylinders. Further, a forging of the barrel is obtained from it by radial compression, which is finally machined and its entry part is removed. During preliminary machining at the lead part, the small cylinder is made into a diametric size equal to or greater than the final external diametrical size of the breech of the barrel, and at the large cylinder, the diametrical size of the initial workpiece is maintained.

The advantage of the prototype over the analogue is that the lead part after radial crimping is not removed, but used as a breech part of the finished barrel, thereby achieving a reduction in metal consumption during its machining.

The disadvantage of the prototype is the low durability of the standard lead center (about 1000 forgings of the trunks) on its internal radius teeth experiencing high stresses: contact, compression and bending, and their premature failure due to their contact with only one step formed by the intersection of the side and end surfaces of the large cylinder billet pipes fed into the area of the strikers by this center and simultaneously rotated by it with radial compression by the corresponding mechanism of the radial crimping machine.

The objective of the proposed invention is to increase the service life of the lead center at least 1.5 ... 2 times, achieved by increasing the total contact area of its internal radius teeth, interacting additionally with the zone of intersection of the side and end surfaces of the small cylinder of the workpiece pipe, thereby reducing it teeth contact stress, compression stress and bending.

The technical result from this invention is an increase in the service life of the lead center at least 1.5 ... 2 times is achieved due to the formation of two steps in the breech of the billet-pipe under its internal radius teeth, with which they come into contact during rotation during radial compression.

The specified technical result is achieved by the fact that in the method of manufacturing forgings of trunks with threaded or smooth guide parts, including heat treatment of the original billet, its preliminary machining to obtain a billet-pipe having at its ends a lead-in and a lead-in part in the form of large and small cylinders, and the manufacture of the forgings of the barrel by radially crimping the billet-pipe on a radial crimping machine when fixing the lug portion of the billet-pipe in the center, made with teeth, ovym is that the small cylinder-tube preform operate length smaller than the height of the step between the large and small cylinders.

At the end of the small cylinder, a smaller cylinder is made, the length of which exceeds the step height between the small and smaller cylinders

By performing two steps at the workpiece-pipe under the teeth of the center of the lead, their contact area with these steps increases, and the stresses arising in these teeth decrease: contact, compressive and bending, which increases the resistance of these teeth, which ensure the rotation of the workpiece-pipe during radial compression, necessary for crimping it around the perimeter and forming a threaded guide part of the bore.

These distinctive features allow you to increase the service life of the center of the lead at least 1.5 ... 2 times and improve other production and economic indicators associated with the manufacture of forgings of the barrel.

Based on the foregoing, we can conclude that the proposed technical solution has a novelty and inventive step and can be used in industry in the manufacture of forgings of trunks, for example, heavy machine guns.

The proposed methods are illustrated in the drawing, where Figs. 1 and 2 show variants of methods for manufacturing the towing part of the billet-pipe, and Figs. 3 and 4 show their implementation together with the corresponding version of the towing center.

The proposed methods are implemented as follows.

At a metallurgical enterprise, the initial billet is manufactured and heat treated (round rolled or forged); then, at the factory of the trunks, it is mechanically processed: the ends are cut, one of them is centered, a through hole is drilled, and a billet-pipe is obtained. Then grind with the formation of the lead-in and the lead part (see figure 1) in the form of a large cylinder 1 with a diameter of do. When turning at this cylinder 1, the section 4 is kept untreated, equal to the diameter of the initial billet d _zag and a length l ₀ = 5 ... 6 mm, and from its end it is made a small cylinder 2 having a diameter d ¹ , and the length l of the small cylinder should be less than the height h are the steps between these cylinders. In the axial hole of the billet-pipe from the breech part, the technological chamfer 3 is performed, which is necessary for fixing this part in the lead center during radial compression of the billet-pipe and which is part of the 1st cone of the future barrel chamber.

The height of the step h is determined by the expression:

h = (d _zag - d ¹ ) / 2,

and the length of the step 1 is prescribed from the condition:

l <(d _zag -d ¹ ) / 2

Figure 2 presents the lead part of the billet pipe also in the form of a large cylinder 1 with a diameter do and an untreated section 4 with a diameter of the initial billet d _zag length l ₀ = 5 ... 6 mm, from its end a small cylinder 2 having a diameter d ^{1 of} length l, which is smaller than a step of height h between these cylinders. From the end of the small cylinder 2 of the billet pipe, a smaller cylinder 5 with a diameter of d _m.s ≥ diameter of the breech of the finished barrel and a length l ^{1 of} not more than 10 mm, which is greater than the height h ^{1 of the} step between it and the small cylinder 2, is made.

After the radial crimping of the billet-pipe, completed at a distance of 20 ... 50 mm from its breech end, the forged barrel obtained from it (according to paragraph 1 of the formula) is processed finally with removal of its lead-in, and the end of the small cylinder 2 is cut at the lead part, with a diameter d ¹ = d _k.ch - the diameter of the breech of the trunk, on a length of not more than 2 mm, to remove in the zone of diameter d ¹ fingerprints up to 2 mm long and up to 1.5 mm deep of the inner radius teeth of the center, according to paragraph 1 of the formula. When running on a small cylinder, a diameter larger than the maximum breech bore diameter d ¹ > d _c.ch cut the _{bore forge of the} bore for removal of tooth imprints of the lead center at a shorter length, and then grind the untreated initial billet diameter d _zag to the final bore diameter parts of the barrel (for the KPVT machine gun it is 51 mm).

When the billet-pipe is performed according to paragraph 2 of the formula, the forging of the barrel is finally processed similarly to the previous version without removing a smaller cylinder 5 with a diameter of d _m with a length of l ¹ into waste, provided that it is made into the breech of the barrel or more and use this cylinder as part of the finished the trunk.

An example of the implementation of this method (according to paragraph 1 of the formula).

For a 1350 mm barrel with a 14.5 mm KPVT machine gun, the initial billet-hire with a diameter d _zag = 56 mm is cut into billets with a length of 950 mm + l + allowance for trimming the ends, where l = 3.8 mm, then the billet is subjected to preliminary mechanical processing namely, they cut one of the ends of the workpiece, center it and drill a through hole with a diameter of 15.6 mm in it, in which a technological chamfer, which serves as the base surface for the lead center, is made from the breech end to a diametric size not larger than the maximum diameter of the 1st cone chamber stem-tube preform is then treated in the centers of the lathe to give the flanged portion consisting of the diameter d _o = 53.2 mm large cylinder diameter d of the untreated portion _zag. = 56 mm with a length l ₀ = 5 ... 6 mm and a small cylinder d ¹ = 51 ... 52 mm with dimensions 1 = 1.8 ... 2.3 mm and h = 2 ... 2.5 mm (subject to the use of a lead center, teeth which were obtained when milling them with a mill with a diameter of 80 mm). After that, on the CNC machine tool, the input part of the workpiece with a total length of 25 mm is obtained, having a conical-cylindrical surface with diameters of 32 mm and 45 mm.

Thus, after machining, a billet-pipe with a total length of 953.8 mm + an allowance for trimming the ends, having an axial hole with a technological chamfer serving as the base surface for the lead center, is received from the side of the lead part in which a small cylinder d ¹ = 51 ... 52 mm long l = 1.9 ... 2.1 mm, a smaller height h = 2 ... 2.5 mm steps between it and the large cylinder (see figure 1).

Next, the billet pipe is subjected to radial crimping operations on a radial crimping machine, obtaining a forged barrel with a finished guide part. The lead-in portion is removed from the obtained forgings and only the end of the lead part is cut, provided that a small cylinder with a diameter ≥ diameter of the breech shaft is made, to remove fingerprints of the lead center teeth on this cylinder and the remaining from it is used to form this part of the trunk. After that, the final machining of all surfaces, including the inner one, is carried out with the formation of a chamber in it, part of which is already made in the form of a technological chamfer 3 of its first cone.

The implementation of this method according to paragraph 2 of the formula is carried out similarly to the previous method. The length of the workpiece will remain unchanged if d ¹ ≥ the diameter of the breech of the finished barrel and does not increase by a length l ¹ ≤10 mm of a smaller cylinder 5, which is greater than the height of the step between it and the small cylinder and is determined from the expression h ¹ = (d ¹ -d _{m .c} ) / 2 (see _figure 2). In this case, the lateral surface of the smaller cylinder d _m.c serves for the billet-pipe with radial compression by the base surface located in the cavity 11 of the lead center (see figure 4).

This billet pipe is also subjected to radial crimping operations on a radial crimping machine, obtaining a forged barrel, which removes the entry part and the technological chamfer on a smaller cylinder, made in diameter d _mt ≥ bore diameter of the barrel (for example, with a machine gun CORD it is 38 mm), this cylinder is not cut, but is used to form this part of the trunk. In this case, the first step is performed in diameter d _zag = 60 mm, and the second step in diameter 52 mm. After this, the final machining of all surfaces is carried out.

Variants of the implementation of the proposed methods using variants of the lead center are shown in FIGS. 3 and 4, where, according to paragraph 1 of the formula in FIG. 3, 1 is shown: 1 — the tube blank subjected to radial compression is installed in the lead center 6 with a hollow thrust center 8, which when exposed to an elastic element 7 (for example, a spring) with its front end, it is based on a chamfer made from the breech side in the axial hole of the workpiece-pipe. To ensure only rectilinear movement of the hollow thrust center without rotation around its longitudinal axis, a longitudinal groove 9 is made in it under the fixing element 10 — a screw with a cylindrical front part located in this groove 9, while the screw itself is installed in the transverse window of the front of the center 6 .

An embodiment of the proposed method according to paragraph 2 of the formula is shown in figure 4, where 1 is the billet-tube subjected to radial compression, is installed by a smaller cylinder 5 into the cavity 11 of the center 6, which is structurally simpler than the previous version of figure 3, but provides greater misalignment between due to the large diametrical gap (up to 0.2 mm) between the smaller cylinder 5 and the side surface of the cavity 11 under it at the center of the center, than the center of the center ig.3. In the latter, this gap between the surfaces of the hollow thrust center 4 and the nest of the lead center under it is several times smaller (up to 0.07 mm).

When implementing this method in the KORD machine gun, the breech diameter of its barrel with a length of 1100 mm is d ¹ = 38 mm, and the initial billet of the barrel with a diameter of 60 _{+ 0.4 / -1} mm and a length of 750 mm. The breech of the billet pipe under radial compression is performed in the following dimensions (see figure 2): d0 = 57 mm; d _zag = 60 mm; l0 = 5 ... 6 mm; l = 3.9 mm; h = 4 mm; h ¹ = 7 mm; l ¹ ≤10 mm; with d0 = d _zag = 57 mm: h = 4 mm; d = 3.5 mm; h ¹ = 5.5 mm; l ¹ ≤ mm. When performing the breech of the billet-pipe into a smaller diameter d _mc = 40 mm, which is larger than this diameter of the finished barrel in the examples h ¹ will be equal to 6 mm and 4.5 mm, respectively. With a smaller diameter d _m = 40 mm, the breech end face of the forgings of the barrel does not require trimming, since its technological chamfer 1 × 45 ° is removed by machining while lowering this diameter d ¹ = 40 mm to a breech diameter of the finished barrel equal to 38 mm.

The examples of the implementation of these methods are suitable for trunks of 12.7 and 14.5 mm caliber. With large barrel gauges, for example, 23 mm, 30 mm, and so on, a larger number of steps can be formed in the lead part of the billet-pipe, which may not have an unprocessed billet diameter d _{zag of} length l0, but only diameter d0 in the breech (This also applies to a 12.7 mm caliber barrel).

For a billet-pipe for calibers 12.7 and 14.5 mm, it is more expedient to have an untreated surface with a diameter of d _{zag with a} tolerance of up to 1.4 mm (for a barrel of caliber 14.5 mm, the diameter of the billet d d _zag = 56 mm has a tolerance of + 0.4 / - 1.0 mm), which is greater than the tolerance + 0 / -0.2 by d0 = 53.2 mm of a large cylinder. With such a large tolerance of 1.4 mm, the teeth of the center of the lead come into contact with the metal of the peripheral step not locally on the length of the teeth in the range> 0.1 mm, of the last example do. = 53.2 mm, but on the length> 0.7 mm and this also increases their resistance to the stresses acting in them arising from the rotation of the billet-pipe in the process of radial compression of it. This also increases the service life of the leash center.

The production option of the lead part of the billet-pipe in diameter d0 without a rough surface made in diameter d _zag , with the corresponding parameters for a given size d0, is not ruled out.

Thus, the proposed method of manufacturing a barrel in the form of a pipe blank having two steps in the ledge part for the inner radius teeth of the lead center, the stresses in these teeth are reduced, and the service life of this center is increased by 1.5 ... 2 times compared to the standard one, in contact with only one step available at the pipe blank.

Claims (2)

1. A method of manufacturing forgings of trunks with threaded or smooth guiding parts, including heat treatment of the original billet, its preliminary machining to obtain a billet-pipe having at its ends a lead-in and a lead-in part in the form of large and small cylinders, and the manufacture of forgings of the barrel by radial compression billet pipes on a radial crimping machine when fixing the lead part of the billet pipe in the lead center made with teeth, characterized in that the small cylinder of the billet pipe They are filled with a length shorter than the step height between the large and small cylinders. 2. The method according to claim 1, characterized in that at the end of the small cylinder perform a smaller cylinder, the length of which exceeds the height of the steps between the small and smaller cylinders.

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