SU1144743A1 - Method of straightening spline parts - Google Patents

Abstract

1. METHOD OF EDGING SPLENDED DETAILS on a mandrel with slots, including heating to austenization temperature, quenching with simultaneous application of US.PII straightening to side and centering surfaces of slots, characterized in that, in order to improve the quality, straightening on lateral and centering .the surfaces of the splines of the part are applied..in the process of relative axial movement of the part and mandrel locally in sections, they are arranged in a checkerboard order along the cross section and with a spacing along the length of the slot at least 2a, while the velocity V Tel'nykh moving parts and the mandrel is determined from the ratio. where a is the width of the slot section of the mandrel, mm; t is the time of maximum stability of austenite, s; VK is the critical quenching rate for the material of the part, deg / s; Osh - cooling rate of the closed part of the slot, deg / s; Vx.- cooling rate of the metal in the coolant, degrees / s. @ 2. A method according to claim 1, characterized in that during the leveling process, the surfaces of the splines are subjected to surface plastic deformation by relative rotation of the part and mandrel.

Description

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g 1 The invention relates to the machining of metals by pressure and can be used when straightening splined parts. The closest to the present invention is a method of straightening gear caths with a splined hole on a splined mandrel, which includes turning Kaieca gear to temperature, setting a heated wheel on a rigid spline mandrel and straightening on it in the process of hardening the side profiles and centering surfaces of the splines, pressing the mandrel out of the spline hole, dispensing the wheel and loading the spline hole 1. The disadvantage of this method is the uneven hardness (40-56) splined openings due to inability provide uniform critical cooling rate splined openings in contact with the mandrel. The purpose of the invention is to improve the quality of the spline parts. The goal is achieved by the fact that according to the method of straightening schlintsev details on a mandrel with slots, including heating to austenization temperature, quenching with simultaneous application of force to the side and centering surfaces of the slots moving the workpiece and mandrel locally over the plots, positioning them in a staggered order across the cross section and with a spacing along the length of the splines are at least 2a, while the velocity V is relative parts n th movement of the mandrel defined by r from the relationship: Vv CC-T where a - the width of the recess portion of the mandrel, mm; t is the time of minimal stability of austenite, s; critical order rate for the part material, deg / s; cooling rate of the closed portion of the slot, degrees / s; cooling rate of the metal in the coolant, degrees / s. In order to increase the strength of the trimming, the part is subjected to surface plastic deformation relative to the rotation of the part and mandrel. The displacement speed V of the mandrel is determined from the condition that the heat dissipation from the slot surface of the part free to coolant and from the surface covered by the mandrel must be greater than or equal to the intensity of the heat sink necessary for the martensitic transformation of the material of the splined part. FIG. 1 shows a device for carrying out the method of dressing splined parts 11 3 hoists (longitudinal section); in fig. 2 is a view of FIG. one; in fig. 3 -5 - sections A-A, BB, B-B in FIG. 2 respectively. The device for dressing the spline parts includes a die 1 and a punch 2, between which the spline part 3 is installed, a mandrel 4 connected to a slide mechanism 5 of the rocker mechanism (not shown). The matrix 1 and the punch 2 have the ability to rotate relative to the mandrel 4 (twist) into one and the other side along the arrow SK on the bearing 6 mounted on the bottom of the tub 7. Bath. 7 is connected via pipe 8 to a pump of coolant supply and through pipe 9 to a storage tank of cooling liquid (the pump and the container are not shown). The mandrel 4 left separate areas of the splines 10 and 11, arranged in a checkerboard pattern and fixed separately, respectively, the side profiles of the splines and the centering surface of the diameter of the spline part 3, between which the coolant channels 12 are made. The spline portions 10 and 11 have the dimensions of the finished spline hole and are located on the mandrel 4 in staggered order with a step S a -} - j-Qi, where a is the width of the portion of the slot fixing the profile of the slot; a- - the width of the section of the slot, fixing the centering surface. You can accept that aa, then S-2a. Rotation of the matrix 1 around its axis in one and the other direction along the arrow SK performs a rocker mechanism (not shown) with the help of a slider 13. The process is carried out as follows. The part 3 is heated in an oven to austenizacin temperature and fixed in the matrix I by the punch 2. A hole 4 is inserted into the slot opening of the part 3, which is freely moved in the part with the speed of reciprocating movement. 6kiV4s, v VK-T where a is Width section of mandrel spindle, mm; t is the time of minimal stability of austenite, s; VK is the critical speed for the material of the spline part, deg / s; Vyg, is the cooling rate of the metal in the coolant. gra.1 / s; Via is the cooling rate of the slot portion, deg / s. Simultaneously with the inserts of the mandrel 4, the part 3 switches on the supply of coolant through the channels 12, halfway to the internal surface of the splined bore, and turns on the pump, which quickly pushes the coolant bath 7 to the coolant. When the liquid is cooled by the spline part 3, prior to the beginning of structural transformations, thermal deformations occur in the spline part, which tend to transform the ring shape of the part 3 into the toric one, and the straight splines into cylinders. The spline sections 10 and 11 of the mandrel 4, which are arranged in a staggered order over cross sections of a piece with a pitch of at least 2a and contacting in series with the spline opening with the side profiles of the splines and centering, prevent the shape of the centering surface and side profiles of the splines from changing. with its surface (f. For reciprocating movements of the mandrel 4 at a speed V, the areas of the splines 10 and 11 successively follow the splines of the part and are right in different sections in side-by-side chessboard and centering points in different sections. surface of the slotted hole. In addition, each of the sections of the slots 10 and 11, successively moving to indent the slots, ensuring uniform cooling of the slotted surface of the orifice detail and 3. During further cooling, structural transformations occur (martensite is formed), the diameter of the slotted orifice decreases and The sections of the splines 11 and 10, moving with the velocity V, are right in the shape and dimensions of the slit hole at the moment of the kinetic plasticity of martensite. A further increase in the quality of machining the spline part is achieved by increasing the service life of the spline. Increasing the service life of the splines is obtained after carrying out the surface plastic deformation of the splines. The deformation is created by twisting with an additional alternating load of the matrix I with the part. 3 in the bearing 6 relative to the spline mandrel 4 with the help of the slide 13 of the rocker mechanism, making reciprocating movement S. The magnitude of the load is increased from the minimum proportionally to the increase in hardness of the surface layer of the splines. Example. The parameters of the slotted hole of the part d 8x 36HSX 40N12x 7D9, the length of the part 50 mm. Centering is carried out on the inner diameter of f-36 + 0.039 mm. The largest diameter, the width of the slot b 7 o; o7b, the number of slots 8, the material-cement steel steel 20HNZA. The parameters of the splined mandrel d are 8X X36ft7X4 (J / i8X7 / 7; the length of the mandrel is 80 mm, the third diameter, the largest diameter is mm, the slot width, o28, the number of slots 8 material - high-speed steel P 18, the width of the slot section is about: 4 mm, pitch spline S 16 mm. Spline part after carburizing is heated to austenization temperature of 820-830 ° C and fixed in the matrix using a punch. Turn on the coolant (oil) through the mandrel, freely idle the mandrel in the slotted hole and - reciprocating displacement of the mandrel with a speed equal to V - ir f - 5 f 5nm / c 0, where - width of the slot of the mandrel. mm, mm; KK - critical cooling rate in CC oil 150 deg / s; t - minimum austenite stability time, s ;, W. is the cooling rate of the closed portion of the slot (determined indirectly by the structure formed during quenching without displacement of the mandrel) Eighth 80 degrees, s; U.- cooling rate in the form of metal of the slotted part, Kk 550 degrees, s. When the slotted part reaches 20 ° C, the mandrel is taken out of the hole and the hardened part is removed and subjected to low tempering. As a result of the straightening, the hardness of the spline bore HRC 52-56 and the following parameters of the spline bore are obtained: centering diameter rf 36 °; the largest diameter D 40 is the width of the slot fc 7 - ° “The additional alternating load with which the slots are loaded increases from 2 to 40 kgM for 4 s (the transition time of austenite to martensite). The frequency of changing the direction of the load is ten drips per second. Conducting straightening and deformation of the splines during the quenching process allows to obtain a spline hole without additional processing and to increase the allowable stresses per cm 1.5–2 times, i.e., improve the quality of the straightening.

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Claims (2)

. . 1. METHOD FOR EDITING SPLINE PARTS on a mandrel with slots, including heating to an austenitizing temperature, hardening with simultaneous application of a dressing force to the side and centering surfaces of the slots, characterized in that, in order to improve the quality, a dressing force is applied to the side and centering surfaces of the splines of the part , in the process of relative axial movement of the part and the mandrel locally around 1 1 \ _______________________________________________ i at • stonewall, placing them in a checkerboard pattern along the cross section and with a pitch along the length of the slot of at least 2a, while the speed V of the relative movement of the part and the mandrel is determined from the ratio UK-t - the width of the slot slot mandrel, mm; - time of maximum stability of austenite, s; - critical hardening rate for the material of the part, deg / s; - cooling rate of the closed slot section, deg / s; - metal cooling rate in the coolant, deg / s. where a τ UK Wush Oh 2. The method according to π. 1, characterized in that in the process of dressing the surface of the slots is subjected to surface plastic deformation by relative rotation of the part and the mandrel.