SU1759511A1 - Tool for rolling-on thread - Google Patents

Abstract

Usage: in the processing of metals by pressure, hardware production. The tool contains movable and stationary threaded dies with thread-forming grooves. The depth and width of the grooves vary by zones. The maximum depth of the grooves in the adjacent zones differs by 1.1 ... 1.8 times, and the average width - by 1.05 ... 1.35 times. Conjugations of the adjacent zones in the plane of the longitudinal section of the plates are made in the form of curves whose derivatives coincide at the point of intersection. 1 tab., 5 Il.

Description

The invention relates to hardware manufacturing, in particular to the manufacture of threads on high-strength products, such as rail bolts, and can be used when rolling threads on products of normal strength.

A known die for threading by the method of plastic deformation (see ed. St. № 742017, class B 21 NS) / 06) is made in cross section with an opening and working surface in the form of an ellipse with a constant height of coils corresponding to the height of the full profile formed thread.

However, this tool does not allow improving the quality of the thread on the product and increasing tool life, since it does not provide a rational plastic change in the material of increased strength when forming turns of thread on the product.

A known thread rolling tool (ed. St. 1166339, class B 21 H 3/06) contains a movable and stationary dies with an intake, calibrating and resetting section, and at least one smooth section is performed on the intake section.

However, this tool does not allow improving the quality of the thread with increased strength and increasing tool life, since a change in the height of the thread grooves in the intake area does not provide a rational plastic change in material when forming the thread profile.

The closest in design features to the claimed object are flat knurling dies, having a group of several cutting teeth of successively increasing height and a group of several finishing teeth, a series of finishing teeth having a joint (C) at the site

with

4 SP O SL

modifying with the workpiece a variable width less than the width of the rolled teeth (Japanese Application No. 63-31294, H 21 H 5/00).

However, this tool does not allow to improve the quality of the thread on the product with increased strength and at the same time to increase the tool life, since it does not allow to reduce the stress of plastic shaping.

The aim of the invention is to improve the quality of rolled threads and increase tool life by reducing the strain stress.

This goal is achieved by the fact that in a knurling tool containing movable and stationary dies with a zone varying along the length of the dies with a width of the thread-forming grooves, the grooves are made with a zone varying depth, with the maximum depth of the grooves in the adjacent zones differing by 1.1. , 8 times, and average width - 1.05 ... 1.35 times.

Moreover, the adjacencies of neighboring zones in the plane of the longitudinal section of the plates are made in the form of curves whose derivatives coincide at the intersection point.

The proposed tool is shown in figure 1-5, where figure 1 shows a general view of the tool; 2-4 shows the profile of the threaded grooves on the thread-rolling zones I, II, III in FIG. 1 and the thread obtained therewith; FIG. 5 is a view A of FIG. 1 cross-section of threading plate in the plane of symmetry of the thread groove.

The tool consists of a movable die 1 (Fig. 1) and a fixed die 2, containing thread-forming grooves 3 (Figures 1-4), the depth and width of which vary in zones. There are zones on the instrument: input 4 (figure 1) of lo length, first calibrating 5 long, And second calibrating 6 long 2, third calibrating 7 long and 3 and output 8. Conjugations of neighboring zones are made in the form of curves, the derivatives of which coincide at the point 9 (FIG. 5), which is achieved by the coincidence of the tangents 10, 11, drawn to the curves of the adjacent sections, the tool 12 rolled by the tool 12 (FIG. 1) acquires the thread 13 (FIGS. 2-4) with the formed ridges 14 of the thread, the cavity section 15 thread and intermediate point 16.

The tool works as follows. The article 12 (FIG. 1) is captured by the inlet part 4, after which it is moved to the first calibrating zone 5. When the product passes the first calibrating zone, the thread surface of the product is partially formed (FIG. 2, view

1 in FIG. 1) due to incomplete insertion of the tool into the surface of the product. The thread thus receives non-rolled rounded crests 14, the metal of the product deformed by the threaded grooves flows in the direction of the crests of the thread (the direction of the metal flow is shown in Fig. 2 by arrows).

With the passage of the second gauge

0, zone 6 (FIG. 1), the shape of the thread-forming grooves of the die ensures the reduction of the stresses of plastic formation of the thread. This is achieved by the fact that already on the rolled section 15 (FIG. 3) of the thread is released from contact with the tool, as well as the plastic deformation center is displaced to the point 16 between the ridge 14 and the root of the thread. (The offset is achieved by reducing the height of the tops of the thread-forming grooves, for example, by grinding this area of a thread-on die. The width and depth of the thread-forming grooves in the area vary monotonically along the length of the plate due to

5 smoothly changing the feed of the grinding wheel when grinding the tops of the thread-forming grooves along the length of the zone). As a result, the tops of the threaded grooves of the die are not placed in the already rolled

0 a threaded hollow, and the deformable metal of the product gets the opportunity to flow from point 16 both in the direction of the ridges 14 of the product's thread and in the direction opposite to the direction of flow on the first

5 calibrating area (the direction of metal flow is shown in Fig. 3 by arrows). Thus, the Bauschinger effect is used (see, for example, M.L. Bernstein, V.A. Zaimovsky. Mechanical properties of metals. 0 M, Metallurgists, 1979, p.77), which consists in reducing the resistance of materials to plastic deformations after preliminary plastic deformation of the opposite sign.

5 The next, third calibrating zone 7 (Fig. 1) has the finished thread profile and forms the thread profile completely (see Fig. 4, view III in Fig. 1), and the Baushin effect is again used: since earlier (in the second gage zone) around point 16 a depression formed on the thread profile, the metal tends to flow into it, changing the direction of its flow to the counter5 compared to the flow on the previous gage zone. Changing the direction of metal flow reduces the plastic strain stress, which has a positive effect on the resistance

tool. In addition, a change in the direction of metal flow disperses dislocations accumulating in the places of the greatest plastic deformations of a thread, which improves the quality of a thread, reducing the possibility of thread destruction during operation.

Conjugations between adjacent tool zones are made in the form of curves whose derivatives coincide at the intersection point, which minimizes the dynamic processes that affect the shaping of the thread.

Example. The tool for rolling threads on bolts M27 from high-strength boron-containing steel for railway fasteners (surface hardness up to 39 HRC) was made of steel X12M. The overall dimensions of the die 400 x 80 x55 mm corresponded to the dimensions of the standard die used in the manufacture of thread M16-M27. The length of the lead-in zone 4 (Fig. 1) on the movable die was 90 mm, the exit zone - 20 mm. The calibration zones had the dimensions: the first - 85 mm, the second - 85 mm, the third - 85 mm. The thread-forming grooves of the first and third zones had a finished thread profile with the following dimensions: depth 1.388 mm, average width (corresponding to the width of the average thread diameter) —1.28 mm. The maximum depth of the grooves of the second zone in accordance with the claims was 1.838 mm: (1.1-1.8) 1.671-1.021 mm. The average width of the grooves of the second zone was 1.28 mm: (1.05-1.35) 1.219-0.948 mm. The change in the width and depth of the grooves of the adjacent zones was achieved by grinding the tops of the grooves of the second zone by 0.17-0.62 mm. At the same time, the depth and width of the grooves of the second zone monotonously decreased in the direction to the third calibrating zone, which was achieved by gradual deepening of the grinding wheel when grinding along the length of the zone. The adjacencies of the adjacent tool zones were made in the form of curves, the derivatives of which coincide at the intersection point, which was controlled by

checking the absence of an obstacle to the free rolling of a flat caliber across the depth of the groove at the junction of two zones.

Examples of threading the proposed tool are given in the table,

As follows from the table, the execution of the maximum depth of the grooves in the adjacent areas, which is less than 1.1 times,

and the width of the grooves reduces the quality of the thread by less than 1.05 times the quality of the thread due to insufficiently worked out ™ elements of the thread, which is associated with the low fluidity of the material of the increased fastener. The durability of the tool is not increased.

The maximum depth of the grooves in the adjacent zones, which is more than 1.8 times, and the width of the grooves more

than 1.35 times, reduces the quality of the thread and tool durability due to a sharp increase in the stress of deformation of the metal of the thread on the product with increased strength.

Claims (2)

1. Thread rolling tool containing movable and fixed plates with zone varying along the length of the plates, with a width of thread-forming grooves characterized in that. what with the purpose improving the quality of rolled threads and increasing tool life by reducing the force of deformation, the grooves are made with a zone of varying depth, with the maximum depth of the grooves in the neighboring zones it differs 1.1 ... 1.8 times, and the average width - 1.05 ... 1.35 times. 2. The tool according to claim 1, wherein the mating of adjacent zones in the plane of the longitudinal section of the dies is made in the form of curves whose derivatives coincide at the intersection point. tf Hyde- I on. / at Dud on the phage. / I bud f on y & g. / #