RU2478452C2 - Method of making rollers of heavy-duty drive chains - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in producing drive chain rollers used in whatever industry. Blank cut of bar, heat treated and lubed, is deformed by two make dies in female die to make hollow cylinder with web. One male die has flat working end to create flat surface of said web. Second male die has flat-cone working end to create a recess shaped to truncated cone on web opposite surface. Said web is remove by cutting out. Conical ledge is arranged on cylinder inner wall to be squeezed into the wall in further roller calibration. Ledge volume exceeds that of formed defects after web cutting out on outer surface of semi-finished product.

EFFECT: higher quality of articles and efficiency of their production.

5 cl, 3 dwg

Description

The present invention relates to the field of engineering technology, in particular to the field of metal forming, and can be used to improve the reliability of the drive chains used in metallurgy, conveyor devices and other high-energy motion transmission.

The rollers for heavily loaded drive chains are long-axis bushes made of 20G steel, which are difficult to obtain by stamping and often they are made by machining by cutting, which is why almost 50% of the metal has to be shipped. At the same time, productivity becomes low, and labor costs are large (an example of such production is the Tula Chain Plant, website http://www.tzc.ru).

There is a method when the workpiece is cut from a bar, heat treated, lubricated and squeezed out in the reverse way in the form of a glass with a bottom, which is then cut down (Filimonov Yu.F., Poznyak L.A. Stamping by pressing. M .: Mechanical Engineering, 1964, 157, Fig. 113). However, the rollers in this way get small, not more than 1.5-1.8 internal diameter in height, which is used in chains for small vehicles (bicycle, moped, motorcycle). Extrusion of long-axis rollers in this way leads to rapid tool breakage.

There is also known a method that we took as a prototype using combined extrusion from a solid billet (Filimonov Yu.F., Poznyak L.A. Stamping by pressing. M .: Mechanical Engineering, 1964, 161, Fig. 118) of a hollow cylinder with a jumper inside with tapered surfaces, which increases tool life. This jumper is removed by drilling, leaving an internal protrusion, which is then removed mechanically (turning, grinding, calibration) of the internal cavity. The disadvantage of this method is the increased complexity of the manufacture of the roller at the final stage of its manufacture.

When cutting down the jumper (as in the first analogue), the quality of the roller decreases due to tearing of metal on its inner surface. With a decrease in the thickness of the bridge, in order to reduce the volume of metal tearing, annular weights appear on the outer surface of the sleeve, which, when the sleeve is different, lead to uneven beating in the chain and its destruction. Therefore, the technology of combined extrusion with cutting down jumpers in production is practically not used.

The objective of the invention is to improve the quality of the rollers by compensating for defects in combined extrusion and subsequent cutting of the jumper without reducing the utilization of metal and labor productivity.

The task is achieved as follows.

A method of manufacturing rollers of heavily loaded drive chains, namely, that the workpiece is cut off from the bar, heat treated, lubricated and deformed by combined extrusion of 2 punches in the matrix, forming a hollow cylinder with a jumper inside, the jumper is removed, the workpiece is deformed by combined extrusion of punches having working punches having the ends of one are flat, creating a flat surface of the jumper of the cylinder, and the other of a flat-cone, creating a recess in the form of a truncated cone on the other surface of the jumper and, cutting the jumper is removed, leaving a conical protrusion on the inner wall of the cylinder, followed by its indentation into the wall during the further calibration roller, wherein the volume of the protrusion should be greater than the amount of defects formed in a tear-out after cutting the jumper, or in the form of sink marks on the outer surface of the semi-finished product; the volume of the part of the jumper remaining after cutting in the semi-finished product should be 3-7% more than the volume of defects formed; combined extrusion is carried out with a restriction on the height of the wall of the semi-finished product in the direction of the flat surface of the lintel while aligning it with the height of the edge; the thickness of the jumper in the zone of its future slice is taken so that when cutting the wall of the roller does not crease; the bevel angle of the conical protrusion of the bridge is taken in the range of the real angle of friction of the deformable material.

To explain the described object, Fig. 1 shows a section of an extruded semifinished product with a curved jumper surface from below, Fig. 2 shows a contour of the inner surface of a semifinished product after cutting before calibration, and Fig. 3 shows a diagram of a jumper felling and calibration of a protrusion.

A method of manufacturing rollers of heavily loaded drive chains is as follows.

The main part determining the high wear resistance of heavily loaded drive chains is a roller, the quality of which is high. It is most often made of alloy steel (20 XM). Due to the wide range of such chains, the diameters of the rollers D vary from 20 to 44 mm (from 8 to 44 mm in total), and their heights H from 30 to 80 mm (from 3 to 80 mm in total) in heavily loaded drive chains with a height to outer diameter ratio H / D from 1 to 4 (Figure 1). The applied method is primarily suitable for relative roller heights greater than 1.5. If the rollers are made of stronger steel or titanium alloys, then the maximum relative height for the proposed method is reduced. When using carbide tools, the maximum relative height of the roller increases.

Example

For the manufacture of a roller (cylinder 1 in Fig. 1) with an outer diameter of D = 36 mm, a wall thickness of t = 3 mm, a height of H = 80 mm from steel 20X, a solid billet with a diameter of D ₀ = 35 mm and a height is cut from the rod according to the proposed method H ₀ = 38.2 mm, the volume of which V ₀ includes the volume of the cut-off lintel 2 V _{lane with a} diameter of d = 30 mm and a thickness t _p = 2 mm. Then they work on the workpiece in the following order: heat treat (anneal at T = 800ºС for τ = 30 min), lubricate (pickle, phosphate, wash, dip in soap emulsion and dry), deform with punches 3 and 4 in matrix 5 according to the combined scheme extrusion, turning it into a hollow cylinder 1 with a jumper 2 inside (the thickness t _{p of the} future cut is not greater than the wall thickness t, in our case t _p = 2 mm), on a cold press with a force of P = 2.5 MN, then jumper 2 cut down, and the cylinder 1 is calibrated on the inner surface, removing the protrusion 6, the remaining ysya after cutting member 2, and simultaneously filling the possible tearing of the metal inner and sink marks on the outer surfaces of the cylinder 1.

МПа, т.е. Р=1,3 МН, поэтому и выбран пресс для холодного выдавливания с коэффициентом запаса по силе в К_з≈1,5 раза.To implement such a technology, it is necessary to choose the deformation modes and sizes of semi-finished products. For given dimensions of the part, the degree of deformation in any direction will be ε = 0.69. The specific force of the combined extrusion, depending on the friction conditions of the workpiece at the contact boundaries is

MPa, i.e. P = 1.3 MN, therefore, a press was selected for cold extrusion with a safety factor of K _s ≈1.5 times.

The felling strength of the jumper, taking into account the hardening, is defined as P _out = πdt _n τ _cf = π30 * 2 * 508 = 96 kN.

So that when cutting the bridge 2 the wall of the cylinder 1 does not lose its shape, it must be checked for creasing near the unstressed edge according to the formula

P _cm = π (D ² -d ² ) * τ _s / 4 = π (36 ² -30 ² ) * 340/4 = 106 kN.

Since P _cm ≥P _vyr , the selected thickness of the jumper 2 in 2 mm is quite acceptable.

The height of the conical section h _b and the bevel angle α (FIG. 2) of the notch of the jumper 2 are of great importance for the technology and are selected from the condition that the volume V _{B of the} protrusion 6 (FIG. 1) will compensate for defects in the weight 8 of width h _y and tear 9 in FIG. 3). The bevel angle of the conical protrusion 6 of the jumper 2 is taken equal to α = 5º in the range of the real angle of friction of the deformable material, α = 4-17º. The height of the conical section adopted h _b = 2 mm

After cutting down the jumper 2 on the inner surface of the cylinder 1 there remains an annular protrusion 6 (Fig. 3) of a triangular section with a height t _bp = 0.18 mm, then the volume of the annular protrusion will be equal to

V _in = π (d / 2-t _in / 3) h _kb t _in = π (15-0.18 / 3) 4 * 0.18 = 33.79 mm ³ ,

V _y = π (D / 2-t _y / 3) h _y t _y = π (18-0.09 / 3) 5 * 0.09 = 25.4 mm ³ ,

V _bp = π (d / 2-t _bp / 3) h _bp t _bp = (15-0.06 / 3) 3 * 0.06 = 8.3 mm ³ .

The volume of the annular protrusion is slightly higher than the sum of the arisen volumes of the annular tearing and weights.

The figure 3 shows a diagram of the felling of the jumper 2 in the cylinder 1 (the semi-finished product is turned 180 °) and the subsequent calibration of the inner surface of the cylinder 1 with an annular protrusion 6 with one punch 10 with a punch part 11 and a calibrating girdle 12 in the punch matrix 13. In this case, the pressed metal of the ring the protrusion 6 of the cylinder 1 will fill the volume of the weight 8 and the breakout 9.

Since when the jumper 2 is cut out, the reaction force R of the protrusion 14 from the matrix 13 presses on the edge of the cylinder 1, then it must be made even with the help of end calibration, and this is easy to do if, when combining extrusion in one of the directions, a height restriction 7 (FIG. 1). Since the felling passes towards the flat surface of the jumper 2, then we set the restriction 7 from the same side h (Fig. 1). And then all possible distortions will then go towards its curly surface h ₁ , which will not affect the quality of the future chain roller.

When extruding billets from strong structural steels or from titanium alloys, the billet is stamped in a half-hot state, i.e. at a temperature, for example, for steel 40X or 45, 730-750ºС, which is 30-70ºС less than the temperature of recrystallization of these steels. Then the entire proposed technology is configured to be standard for half-hot extrusion.

An economic calculation showed that the utilization of metal in the combined extrusion of rollers of heavily loaded drive chains can reach 94%, which, compared with metal cutting, gives more than 40% of metal savings. For a million manufactured rollers of these sizes, savings can be 42 tons of metal. Given that 1 ton of steel 20X or 40X is on the market about 40 thousand rubles per ton, it is easy to calculate: 1680 thousand rubles can be saved per million of metal only, and the Russian chain industry produces several million of such rollers.

Claims (5)

1. A method of manufacturing rollers of heavily loaded drive chains, including cutting a workpiece from a bar, heat treating, lubricating and deforming it by combined extrusion of two punches in a matrix to form a hollow cylinder with a jumper inside, removing the jumper, characterized in that the workpiece is deformed by combined extrusion of punches, one of which has a flat working end to create a flat surface of the cylinder bridge and the other a flat-conical working end to create on another surface These bridges of the recess in the form of a truncated cone, the jumper is removed by cutting, while leaving a conical protrusion on the inner wall of the cylinder, followed by pressing it into the wall during further calibration of the roller, and the volume of the conical protrusion exceeds the volume of the defects formed in the form of a breakout after cutting the jumper and in the form of a weight on the outer surface of the semi-finished product. 2. The method according to claim 1, characterized in that the volume remaining after cutting the conical protrusion exceeds the volume of the resulting defects by 3-7%. 3. The method according to claim 1, characterized in that the combined extrusion is limited to the height of the wall of the semi-finished product in the direction of the flat surface of the jumper while aligning it with the height of the edge. 4. The method according to claim 1, characterized in that the thickness of the jumper in the area of its slice is selected from the condition of exclusion of crushing of the wall of the roller when cutting. 5. The method according to claim 1, characterized in that the bevel angle of the conical protrusion of the jumper is selected from the range of the real friction angle of the deformable material, which is 4-17 °.

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