SU1750934A1 - Device for finishing and strengthening screwed surfaces - Google Patents

Abstract

Usage: metal forming, in particular, surface plastic deformation processing of threaded products such as running screws and screws. The essence of the invention: the device contains a deforming tool installed in the housing, a force mechanism for influencing the deforming tool, as well as tool holders. The deforming tool is made in the form of a nut with a rectangular thread and longitudinal grooves on the inner side surface parallel to the axis of the nut. On the outer side of the nut there is a rectangular groove for the retainer. On the end surfaces of the nut, guide lateral grooves for ball bearings are made. One of the supports is mounted on the body, and the other is mounted on the force mechanism. 5 or

Description

The invention relates to mechanical engineering, mainly to machine tool construction, and can be used in the processing by means of surface plastic deformation (PPD) of threaded parts, in particular running screws and screws.

A device for rolling helical surfaces is known, comprising a split housing, deforming tools installed therein, and force mechanisms for each of them. Deforming tools in the form of rollers are placed in pairs, symmetrically to the axis of the workpiece with an offset relative to each other. The known device has a significant performance due to the use of deforming tools in the device, which are located offset from each other, providing the necessary amount of feed running to perform processing in a single pass.

However, due to the fact that each of the tools is equipped with an independent force mechanism, it is difficult to ensure the same running force on each tool. The difference in these efforts leads to uneven hardening of the screw surface, which reduces the performance of such products.

For some friction sliding screw parts, a combined antifriction hardening treatment is necessary, i.e. an antifriction coating applied to the surface to be treated and the subsequent treatment of this surface using the SPD method with the formation of a regular microXJ on it

SP O U

WITH

relief. An increase in the adhesion strength of the antifriction coating with the base metal and the formation of a regular microrelief on them helps to obtain parts with high performance properties.

However, using a known device, it is impossible to handle screw surfaces with coatings previously applied to them, since there is no impact of deforming tools necessary to ensure an increase in the adhesion force of the coating to the base metal.

In addition, the device is inconvenient and unproductive when operating in large-scale production conditions, since when changing the machined part, an additional operation is required - opening the split housing.

The closest in technical essence and the achieved result is a device for finishing and hardening machining of threads, which contains a hollow body, deforming tools installed in it, and a force mechanism. The deforming tools are located symmetrically with the axis of the part being machined and offset along its length. The force mechanism is made in the form of a torsion spring spanning the tool holders. The device is installed in the support of the lathe, and the part is in the chuck. A single force mechanism provides the same machining force on all tools, which is one of the conditions for the formation of an accurate regular microrelief on the surface to be treated. The device is convenient to operate in large-scale production conditions, since the part can be installed in a housing without its connector.

However, the quality of the screw parts processed on this device is insufficient, since there is no rigid kinematic connection between the tool and the part, which violates the stability of the microrelief. In addition, using a known device, it is impossible to treat the screw surfaces with a coating previously applied to them as a result of the absence of the impact of deforming tools on them.

The aim of the invention is to improve the quality of machining of helical surfaces by applying an accurate regular microrelief.

This goal is achieved by the fact that the known device for finishing and hardening processing of helical surfaces, comprising a housing with

deforming tool, deforming tool retainers and power mechanism for deforming tool are equipped with at least

two ball bearings, axially mounted relative to the deforming tool, one of which is rigidly fixed to the body and the other to the force action mechanism, while

0 the deforming tool is made in the form of a nut with a rectangular thread and splined diameters uniformly located along its inner side surface that is freely mounted on the machined screw.

Five grooves parallel to the nut axis, on the end surfaces of the nut, there are guide rings for ball bearings, and on the outer side surface - rectangular grooves, longitudinal on the axis of which are parallel to the axis of the nut; installed in the body of the collet sleeve and placed in the sleeve

A 5 step axis with a figured protrusion on the end facing the rectangular slot. The execution of the deforming device in the form of a nut which is freely mounted on the machined screw with slots on

0 threading, placing it on axially arranged ball bearings, provides automatic axial feeding of the machined screw without its rotation due to the precession of the nut axis. The precession5 movement of the nut axis relative to the axis of the screw being machined is caused by axial loading of the nut and gaps in the axial and radial directions between the threads of the nut and the threads of the screw being machined. This achieves a rigid kinematic connection of the tool with the part, as well as obtaining the impact of the tool on the machined screw surface of the part.

The presence of clamps and their relationship with the deforming tool through the groove on the lateral outer surface of the tool ensures the accuracy and correctness of the installation of the deforming tool relative to the workpiece, which, in combination with the features of the deforming part of the tool, ensures high quality of the surface

5 by obtaining an accurate regular microrelief and the possibility of processing parts with a pre-coated coating to form a new state of the surface layer and to form a regular microrelief on the surface.

Figure 1 shows the proposed device in section; figure 2 - section aa in Fig, 1; on fig.Z - section BB in figure 1; FIG. 4 is a diagram for determining the maximum angle of rotation of the nut relative to the screw being machined in the plane of the drawing in FIG. one; Figure 5 shows a scheme for determining the axial and radial clearances between the lateral and cylindrical surfaces of the nut thread and the screw to be machined.

The device for finishing and hardening machining of helical surfaces contains a hollow body 1, a deforming tool 2, a power mechanism 3 for generating processing force and clamps 4, the power mechanism 3 consists of a sleeve 5, a package of belleville springs 6, a nut 7, regulating the clamping force Springs b and lock nut 8.

The sleeve 5 in the housing 1 is fastened with pins 9, which are slidly mounted in the sleeve 5.

The deforming tool 2 is made in the form of a nut 10 with an internal rectangular thread 11c in increments equal to the pitch of the screw 12 to be machined and several turns. The nut 10 is freely mounted on the machined screw 12 with the formation of axial and radial gaps between the turns of the nut 10 and the screw 12.

The nut 10 on the outer perimeter is provided with a groove 13 of rectangular cross section.

Thread 11 has through longitudinal grooves 14 (FIG. 2) in the form of slots, evenly spaced circumferentially symmetrically to each other and parallel to axis 15 of nut 10 (FIG. 1).

Three clamps 4 are evenly spaced around the circumference of the housing 1. The latch 4 consists of an axis 16, which is located in the collet bushing 17 and is fixed in a predetermined position by means of a lock nut 18 (FIG. 3). One end of the axis 16 is made in the form of a turnkey hexagon 19, and the other end is provided with a figured protrusion 20, which is placed in the groove 13 of the nut 10 (Fig. 1).

The deforming tool 2 (Fig. 1) is installed using a pair of axially spaced ball bearings 21 and 22 rolling in contact with the treadmills - guides 23 and 24, made on opposite sides 25 and 26 of the nut 10, the ball bearing 21 is rigidly fixed on the power the mechanism 3, and the ball bearing 22 - on the housing 1.

The device works as follows.

The device body 1 is installed and secured in a lathe chuck (not

shown). In the initial state, the package of disc springs 6 is not loaded. The axis 16 of the retainer 4 is rotated through a 90 ° angle and the nut 18 is screwed in, while the figured protrusion interacts with the groove 13 and rotates the nut 10 to align its axis with the axis of the machined screw 12 (the axis of the lathe spindle).

The treated screw 12 is screwed into the nut 10 for several turns and placed in lunettes (not shown). Release the locking nut 18 and return the axis 16 of the retainer 4 to its original position (rotate through an angle of 90 °).

Nut 7 install the necessary processing force by pressing the springs 6, which transmit the force to the sleeve 5, which, moving along the keys 9, through the support 21 in contact with the treadmill 23, transfers the working force to the tool 2, pressing it to the support 22. axial loading tool-nut 10 and it due to the presence of axial and radial clearances between the turns of the processed screw 12 and the nut 10 occupies an inclined position (figure 1).

The machine is turned on, the body 1 with the power mechanism 3 begins to rotate. The force mechanism 3 generates axial forces by means of springs 6, which, through ball bearings 21 and 22, act on nut 10. With axial action of ball bearings 21 and 22 on nut 10, which is matched with the screw 12, on a local thread 11 nuts 10 and the machined screw 12 normal contact occurs. The position of the contact area depends on the location of the axial force along the circumference of the treadmill 23 and 24 of the nut 24. Since the contact occurs along the screw surface of the screw 12, the rotational movement of the nut 10 is connected with its translational motion relative to the screw 12 without slipping. Here, mainly axial force is transmitted through the ball bearings 21 and 22. The axis 15 of the nut 10 makes a precessional movement with simultaneous rotation around its axis.

Figure 4 shows the scheme for determining the maximum vrna a. rotation of the nut 10 relative to the screw 12 in the plane of the drawing (figure 1). The angle "can be determined from the ratio

sin a Ј, o

where l is the height of the screw thread profile; B is the width of the nut.

With the largest DHG and the smallest DHM screw diameters, the thread height h can be determined by the formula

h

Onb - DHM

The width of the nut can be determined by the formula

B n -t, (3)

where t is the thread pitch of the screw;

p - the number of threads in the nut.

Taking into account expressions (1), (2) and (3), the desired angle a can be determined from the expression

sin and ° nb Rnm

2 -t n

Fig. 5 shows the scheme for determining the axial clearance between the side surfaces of the thread 11 of the nut 10 and the screw 12 (Fig. 1). Here, the radial clearance a is taken equal to the axial g, i.e.

a d. (5)

The angle of rotation of the axis of the nut relative to the axis of the screw / 3 can be determined from the ratio

d

D

nm

+ a

Assuming equal angles and ft, i.e. a / you can determine the axial clearance d by the formula

D

 nm

Onb he

2 P t - (Onb 0 "m)

Each turn of the thread 11 of the nut 10 (Fig. 1), being a deforming element, performs a complex rolling motion under the pressure of the springs 6, which leads to the deformation of the metal of the helical surface of the anti-friction coating, if any. The thread 11 of the nut 10 due to the splines 14 (FIG. 2) has a discontinuous surface, therefore when turning the nut 10, in addition, an impact of the splines 14 on the surface to be treated occurs. Due to the rolling and impact on the surface to be treated, a regular microrelief is formed on the latter. The device continues to work automatically until the screw surface is processed along its entire length.

Regulation of parameters of the state of the surface layer and microrelief on

The surfaces of the product are made by installing a deforming tool with the help of clamps, changing the machining force through the Zi mechanism by changing the frequency of rotation of the housing 1.

The execution of the deforming tool in the form of a nut with a rectangular thread freely mounted on the machined screw allows only the casing of the device to be rotated without rotating the part, which firstly provides a rigid kinematic connection of the tool with the part, secondly, there is no accumulation of error when there is step errors

15 screws. Placing the nut on the axially spaced roller bearings allows you to create a precession movement of the nut axis, and the nut itself will create a complex wavelike movement and turn it around its axis for

20 ensure that the thread turns over the entire surface by rolling and for axial movement of the machined screw. The threading of the nut of the longitudinal slots parallel to the axis of the nut ensures that the shock effects of the deforming elements on the treated screw surface are obtained, which contributes to additional surface hardening. In addition, when processing

30 screw surfaces with a pre-applied anti-friction coating impact, activating the anti-friction coating layer and a thin layer of the base metal, intensify physical chemical processes, cause the appearance of accelerated mass transfer between the anti-friction coating particles and the base metal, which ensures the alloying of the upper metal layer, the formation of

40 (anti-friction) surface layer of the part and increases the adhesion of the coating and the base metal.

Impact rolling provides a more complete filling of the irregularities of the surface of the metal base with an anti-friction coating, which improves the quality of the treated surface and the operational properties of the processed screw parts such as wear resistance, counter tolerance, uniformity and smoothness of workability. For example, the wear resistance when using the proposed device can be increased by 1.5 times. In addition, the structures

55 devices are easy to manufacture and assemble, which makes it possible to replace worn parts.

Claims (1)

Claims An apparatus for finishing and hardening the machining of screw surfaces, comprising a housing with a deforming tool installed therein, deforming tool holders and a power mechanism for the deforming tool, characterized in that in order to improve the quality of machining of helical surfaces by applying precise control microrelief, it is equipped with at least two axially mounted rolling bearings with respect to the deforming tool, one of which of a tight fixed to korupse, a- other - to effect the power mechanism, wherein the deforming tool is designed as a nut with 0 five rectangular threads and evenly spaced along its inner side surface slotted grooves parallel to the nut axis; on the end surfaces of the nut, guide rings for ball bearings are made; and on the outer side surface — rectangular grooves, the lengthwise length of which is parallel to the axis of the nut, retainers mounted with the ability to interact with the grooves, each made in the form of a collet bushing installed in the housing and a stepped axis placed in the bushing with a figured protrusion on the end facing the rectangular groove.   (Bd 78 ЯРц $. qcb AXIS Ј {/ # Г77 1