SU1433742A2 - Method of assembling sleeve-and-shaft articles by press-fitting - Google Patents

Abstract

The invention relates to mechanical assembly work, in particular to methods of assembling parts like shaft hub by pressing in. The purpose is to improve the strength of the compounds obtained and | I improve their operating conditions. For this, shaft -1, when pressed into sleeve 3, transmits axial force to the mandrel 2 which performs the elastic-plastic deformation of the sleeve. In the hermetic zone formed by the mandrel, the front end of the shaft 1 and the inner surface of the bush 3, the breather medium is under pressure exceeding the calculated contact contact voltage of the matching parts. The pressing process is finished at the moment when the cylindrical mandrel comes out of the bush H, This leads to the fact that underpressing occurs. shaft to the lower support end of the sleeve. As a result, at this end, a contact-free area of the hardened area is formed.

Description

so & e

YU

ijieft surface. In this area of Aired, an end of the pressed-in shaft forms an annular protrusion, which prevents the shaft from shifting relative to the sleeve during axial operating load. The length of the shaft surface mating to the sleeve and the height of the zone are additionally 433742

The pressure applied to the sleeve located from the shaft end to the cylindrical mandrel ribbon is determined from the above ratios. As a result, the original quality of the mating surfaces is preserved in the assembly process, which contributes to the increase in the adhesiveness of the joints. 4 il.

one

The invention relates to mechanical spraying 1 | yuchny works, in particular to the ways of pressing the connections of parts of the shaft-sleeve.

The aim of the invention is to increase the strength of the compounds obtained and to improve their operating conditions by reducing the pressing force (preserving and maintaining the initial quality of the matching surfaces of the parts to be joined, as well as ensuring the disassembly of the joint using 1 pressurized medium.

FIGURE 1 depicts the scheme for the implementation of the proposed method (intermediate stage); in fig „2 - a joint intended for the perception of axial load, which coincides with the direction of pressing; on FIGURE 3 (;; implementation, which perceives in the process axial loads in different directions; ik; FIG. 4 is a diagram of the process of disassembling the joint.

The method is carried out as follows: a3OM

The pressed shaft 1 transmits the axial force to the mandrel 2, when moving, an elastoplastic approach increases the diametrical dimensions of the sleeve 3 surface. From the moment the pressed shaft 1 is inserted into the sleeve 3 (a sealed zone is formed by the backward cone of the mandrel by the front end the shaft and the inner surface of the sleeve. In this zone, the medium is supplied under pressure, which is 20-30% higher than the calculated contact stress of the Interfaced parts. As a result, the elastic recovery the sleeve-shaped surface of the sleeve is limited and the subsequent insertion of the shaft I into the sleeve 3 occurs without

direct contact between the mating surfaces. This reduces the contact friction and the pressing force, and, in addition, the assembly process is maintained

the original quality of the mating surfaces, which contributes to increasing the strength of the joint.

The pressing process is completed at the moment when the cylindrical tape of the mandrel 2 comes out of the sleeve 3, when the depressurization of the high-pressure cavity occurs, the associated pressure drop in the working medium and the clamping of the mating surfaces. In this case, a sharp increase in the pressing force at the final pressing stage is excluded, since the completion of the pressing process, as well as the whole process, occurs without

direct contact of mating surfaces

As a result of the termination of the pressing process at the moment when the cylindrical ribbon of the mandrel exits the sleeve, the shaft is not pressed to the lower bearing end of the sleeve. At the same time, the length of the sleeve surface mated to the shaft and the nominal area of contact of the parts in the joint are reduced.

To ensure that the strength of the joint obtained does not decrease, the length of the mating with the sleeve of the shaft surface is determined from the ratio

, .lih

1b b, -, where the length of the pressed shaft;

 sleeve length; iih the distance from the shaft end to the cylindrical strip of the mandrel;

K is the coefficient that accounts for the direction of action of the axial operating load: K 1.0, when the direction of the action of the axial operating load coincides with the direction of pressing; To 0.5, when during operation of the joint, the direction of the axial load may change, i.e. It is allowed to reduce the length of the contact surface in the formed joint by no more than 5-10%.

The distance from the end of the shaft to the cylindrical ribbon of the mandrel is determined from the ratio ih (0.05-0.1) K-h.

It has been established that a possible decrease in joint strength from a decrease in the nominal contact area of the mating parts is compensated for by an additional increase due to the increase in the actual contact area in the joint and the friction coefficient of the joint by maintaining the original quality of the mating surfaces throughout pressing process

In addition to the above, the underpressure of the shaft to the lower bearing end of the sleeve leads to the fact that this end of the contact area of the cover surface is free from contact pressure. In this area, due to the elastic return of the metal, the diametrical dimensions are automatically restored and a press-up ledge is formed in front of the end of the pressed-in shaft. This naply-protrusion additionally locks the pressed shaft in the sleeve, preventing it from shifting in

action, axial operating pressure gn pressure1-And there is an elastic increase. The presence in the sleeve of zones free from contact with the shaft expands the technological capabilities of the method due to the possibility of disassembling such compounds using a pressurized medium.

If the operation load coincides with the direction of pressing, the value of the coefficient K

55

the diametral size of the inner surface of the covering part, wedging of the contacting surfaces and penetration of the pressurized medium into the joint of parts. As a result, during the subsequent movement of the mandrel from the moment an axial force is transmitted through it onto the shaft, the latter is pressed out if

is assumed to be equal to 1. In this case, the shaft 1 bT h interface mated with the sleeve and the annular g bushing-protrusion height DH (0.05-0.1) hg is formed only from the front end of the pressed-in shaft (Fig 2),

When in service

0 connection direction of the axial operating load can change the sign to the opposite, the value of the coefficient K p1 1-1 is equal to 0.5. In this case, with that

5, as above, for the shaft surface mating with the sleeve, during assembly, two annular projections of the same height Ash 0.5 (0.05-0.1) hg are formed

0 from o6oiix ends of the pressed-in shaft (FIG. 3).

The presence of a zone (or two zones), free from contact with the shaft formed during the implementation of the proposed

5, expands the technological possibilities of the method due to the emerging possibilities of developing such compounds.

When disassembling in one operation

0 combines the decompression of the joint; A shaft sleeve in which a pressure medium is used and the simultaneous calibration of the sleeve opening with a mandrel. When the press rod moves, force 5 is given to the dorway 2 (Fig. 4). The presence in the sleeve 3 of the marginal zone free from contact with the shaft 1 allows axial movement of the mandrel without transferring axial force to

0 shaft until its occurrence shchind-. ribbons into the sleeve.

At the moment when the cylindrical ribbon of the mandrel enters into the sleeve into the closed cavity 5 formed by the front cone of the tool, the upper end of the pressed-out shaft and the inner surface of the sleeve free of contact with the shaft, the medium is fed under

five

the diametral size of the inner surface of the covering part, wedging of the contacting surfaces and penetration of the pressurized medium into the joint of parts. As a result, during the subsequent movement of the mandrel from the moment an axial force is transmitted through it onto the shaft, the latter is pressed out if

radial clearance between interfaced surfaces. This contributes to reducing the repressive force, preserving the high quality of the contact surfaces of the repressed parts and makes it possible to use them during repeated assembly and disassembly works.

PRI m e RO Assembly was carried out parts by the proposed method. JopH, used for assembly, had an outer diameter of cylindrical ribbon 38,24, - ribbon width 2 mm, intake cone angle 2, inverse cone angle 3 "Material from which the core was made, steel PJ8, Bushes are made with a landing diameter at which conding was done with tension; and "0.4 mm. The outer diameter of the sleeve 60, the height of the sleeve 70 mm.

The shaft diameter of the shafts is selected taking into account the residual deformation in the sleeve metal so that the pressing is carried out in all samples with medium tension, corresponding to the press fit H7 / rbo The roughness of the mating surfaces was for the shafts within R, 0.8 - 1.25, for bushings - R 2,0- | 2,5 mm. The material of the shafts and bushings is steel 45 without heat treatment.

The force effect during pressing in the zone of the inverse cone of the mandrel on the inner surface of the sleeve, coming out of the deformation zone, was carried out with Industrial Oil 20, with a pressure 20-30% higher than the value of the calculated contact stresses; gah, corresponding to the landing H7 / p6.

The end of the contact interaction of the cylindrical ribbon of the mandrel with the sleeve was fixed by a pressure gauge embedded in the hydraulic system of the device, on which at this moment there was a sharp drop in the arrow to zero.

The distance from the end of the shaft to the cylindrical ribbon of the mandrel is determined by the formula

dB (O, 005-0.1) .K.h

Tue

and in the experiments under consideration It was performed with a size of Ah 0.1 170

4337426

 7 mm. The length of the mating with the sleeve shaft surface 1 70-7 63 mm.

In the process of pressing, the maximum pressing force was determined. In addition, the collected samples were disassembled using a pressure medium. Some of the collected samples were pressed out

10 without using a pressure medium to determine the strength of the joints,

As a result of the tests, it was established that the pressing force of the proposed method is 1.5–2 times higher than when assembled in a known manner. The force required to disassemble samples when using a medium under pressure is 2-3 times less than when - 20 borka by direct contact of the mating surfaces. The strength of the joints is increased 1.3 times compared to joints assembled by a known assembly method.

25

Claims (1)

Invention Formula The method of assembling parts such as shaft-bushing by pressing lo., Auth.St., No. 61127.1, jQ with the fact that, in order to increase the strength of the floor of T1enn connections and improve their operating conditions, the pressing process ends at the moment of termination of the interaction of the cylindrical ribbon the mandrel with the sleeve, the height of the zone of additional pressure on the deformable surface of the bush, located from the end of the pressed shaft to the cylindrical mandrel, is determined from the following relationship: L (0.05 - 0, l) K «h, where h is the height of the sleeve; K - coefficient learning direction of axial operating load: K 1, when the direction of axial operating load coincides with the direction of pressing; , 5, when, during the operation of the joint, the direction of action of the axial load may be reversed, and the length of the shaft-mating surface with the sleeve is dimensioned; defined by 35 40  vd) 45 50 55 in the following way: e.-t G / i Dru X lGr / / U f //////////. Ft Editor Y. Sereda Compiled by N.Pozhidaeva Tehred L.Serdyukova Proofreader V.Romanenko FIG. 2 h WITH: and Phi.