RU2303515C1 - Strengthening head provided with elastic tool - Google Patents

Abstract

FIELD: manufacturing processes in machine engineering, namely finishing and strengthening blanks in the form of screw or eccentric shaft.

SUBSTANCE: strengthening head includes body having flanges on its ends and deforming members in the form of turns of coil cylindrical spring mounted in body. Turns of spring are arranged across blank. Spring is coiled along helical line with possibility of embracing blank and its end portions are rigidly secured in flanges. The last are made with possibility of rotation and fixation in circumference position for influencing upon blanks by means of turns of spring.

EFFECT: enlarged manufacturing processes, enhanced efficiency, improved hardness of worked surface, lowered cost price of head.

3 dwg, 1 tbl

Description

The invention relates to mechanical engineering technology, in particular to finishing and hardening processing of workpieces such as screws and eccentric shafts of steels and alloys by surface plastic deformation by a multi-element rolling device with a deforming annular spring.

Known rotating spring tool for dynamic hardening by surface plastic deformation, consisting of a disk holder, on the outer surface of which is fixed a coil spring rolled into a ring [1]. Separate turns of the spring during the working rotation of the holder play the role of deforming elements that interact with the machined surface of the rotating part mounted on a screw-cutting lathe.

The reinforcing tool located on the support of the machine has a protective casing.

The disadvantages of the known elastic tool are: low productivity and low quality of the processed surface due to the small number of deforming elements simultaneously in contact with the workpiece, low feed and a small drop-shaped contact spot of deforming elements with the surface to be treated. In addition, the known resilient tool does not allow the processing of screw surfaces of screws and eccentric shafts.

Known hardening head with an elastic tool, comprising a housing with flanges located at its ends and deforming elements in the form of turns of a coil spring installed in the housing and made of round steel wire [2].

The disadvantages of the known elastic head are: limited technological capabilities, since the diameter of the coils of a coil spring depends on the design parameters of the screw being machined, low productivity and low quality of the machined surface due to the small number of deforming elements in contact with the workpiece at one time, low feed and a small drop-like spot contact deforming elements with the treated surface. In addition, the known resilient tool does not allow the processing of screw surfaces of screws and eccentric shafts.

The objective of the invention is the expansion of technological capabilities, which consists in increasing the roughness parameter of the treated surface, increasing its hardness to a considerable depth due to the smoothing effect of a large number of deforming elements, increasing productivity by increasing the contact spot of deforming elements with the treated surface and the possibility of using large feeds and adjusting working forces and also process screw surfaces of screws and eccentric wa s at a reduced cost and cheap manufacturing process production thanks to the compactness and simplicity of its design.

The problem is solved with the help of the proposed reinforcing head with an elastic tool, which contains a housing with flanges located at its ends and deforming elements in the form of turns of a helical coil spring installed in the housing and made of steel wire of circular cross section, the spring being rolled along a helical line with the possibility of embracing the workpiece and rigidly fixed by the ends in the flanges, made with the possibility of rotation and fixation in a circumferential position to provide impact on the workpiece at the coils of the spring, which are located across the workpiece.

Design features of the head are illustrated by drawings.

Figure 1 shows the proposed reinforcing head with an elastic tool in the form of helical coils of a spring, a partial longitudinal section; figure 2 is a General view from the left of the elastic deforming tool - springs with turns, deployed and located in the transverse plane; figure 3 is a transverse stepped section aa in figure 1.

The proposed reinforcing head with an elastic tool is used to process surface plastic deformation of the outer surfaces of rotation of workpieces such as shafts and screws with a large pitch, for example, screws of screw pumps, as well as eccentric shafts.

Processing is performed on turning, rotary machines with the message of the rotational movement of the workpiece - V _s , and the head - the movement of the longitudinal feed S _pr

The head housing 1 is a shell with windows 2, jumpers 3 on the outer cylindrical surface and the base 4. At the ends of the housing 1 there are threaded holes where the flanges 5 are screwed in the form of nuts with an external threaded surface and keyways 6. Flanges 5 have central openings for locating the workpiece in them. Locking nuts 7 are located on the outer threaded surface of the flanges 5, and fixing screws 8 are installed from the ends.

In the housing 1, a helical coil spring 9 of round steel cross-section 9, coils 10 of which are deforming elements, is installed and fixed along a helical line.

The coils 9 of the spring 10 are deformed and deployed so that the plane of the coils are located in the transverse plane relative to the workpiece (see figure 2).

The spring 9 itself is folded along a helical line and covers the workpiece 11 with a large number of turns, and the ends of the spring 9 are rigidly fixed in the flanges 5 by fixing screws 8.

When the workpiece 11 is inserted into the head by rotating the flanges 5 and tightening the spring 9 around the workpiece 11, the desired force of action of the deforming elements on the work surface is achieved. After installing the necessary spring preload 9, the flanges 5 are fixed in this circumferential position using lock nuts 7. At the end of the processing, the spring preload is removed.

The head is mounted on a support of a lathe (not shown), the workpiece, for example, a screw 11 is fixed in the chuck 12 of the spindle 13 of the headstock 14 and is pressed by the center 15 of the tailstock 16.

After the workpiece 11 is fixed in the cartridge 12, the head is brought to the free end of the workpiece and using manual longitudinal feed of the caliper, overcoming the resistance of the deforming spring 9, string the head on the workpiece, and then tighten the rear center 15.

Before turning on the machine, it is adjusted to the required breaking-in force by rotating one of the flanges 5 with a special key, twisting the spring 9 around the workpiece 11 and controlling the value of the force on a scale (not shown) applied to the end of the case. Lock nut 7 fix the position of flange 5. For uniform spring tension over the entire helical surface of the workpiece, the spring tension is adjusted by two flanges in series.

Include the main movement - the rotation of the workpiece 11 and at the same time tell the head the progressive longitudinal feed S _PR

The essence of the process lies in the fact that during operation of the head, the deforming spring with the help of a control device is installed with an interference fit relative to the workpiece being machined, covering it.

The rolling is carried out by turns 10 of spring 9, exerting pressure on the surface of the workpiece.

With a certain (working) force in the contact zone between the deforming elements and the workpiece, the stress intensity exceeds the yield strength, resulting in plastic deformation of microroughnesses, the physical and mechanical properties and structure of the surface layer change (for example, microhardness increases or residual stresses arise in the surface layer).

Volumetric deformation of the workpiece is negligible.

The presence of an elastic element, which is a deforming spring 9, provides a constant rolling force at any point on the surface to be treated.

The unfolding of the coils 9 of the deforming spring 10 across the workpiece allows you to increase the contact spot of the tool with the workpiece and give it a new ellipsoidal shape, and also makes it possible to process shaped surfaces described by second-order curves, such as, for example, a helical surface.

In this case, the transverse arrangement of the deforming coil of the spring relative to the workpiece allows you to process shaped surfaces with less curvature, depending only on the diameter of the spring wire and not depending on the outer diameter of the coil.

As a result of plastic deformation of microroughnesses and the surface layer, the surface roughness parameter increases to Ra = 0.1 ... 0.4 μm with the initial value Ra = 0.8 ... 3.2 μm. The surface hardness increases by 30 ... 80% with a riveted layer depth of 0.3 ... 3 mm. Residual compressive stresses reach 400 ... 800 MPa on the surface.

Pretreatment of a part: grinding to a roughness parameter value Ra = 0.4 ... 1.6 μm, as well as finish turning of surfaces with a roughness Ra = 3.2 μm.

The rolling of the proposed head is used in the manufacture of billets of non-ferrous metals and alloys, cast iron and steel with a hardness of up to HRC 58 ... 64.

Deforming elements of the device, i.e. the spring is made of steel: alloyed ШХ15, ХВГ, 9Х, 5ХНМ, carbon tool U10A, U12A, high-speed R6M5, P9. Hardness of the working surface of coils made of HRC 62 ... 65 steels. The roughness parameter of the working profile of the coil of the spring Ra = 0.32 μm.

The performance of the rolling process is determined by the radius of the coil of the deforming spring and the diameter of the wire from which the spring is made.

A head with a large radius of the coil of the deforming spring and the diameter of the wire allows processing with a large feed (up to 3 mm / rev), however, in this case, to obtain high surface quality, it is necessary to create large working forces. The parameters of the deforming spring depend on the value of the allowable working force.

The proposed multi-element rolling head provides a constant contact force of the deforming elements and the machined surface and almost does not reduce the errors of the previous processing, being a copying tool.

The change in surface size during rolling is associated with crushing microroughnesses and plastic bulk deformation of the workpiece. Thus, the accuracy of the processed workpiece will depend on its design and the design of the rolling head, processing conditions, as well as on the accuracy of the dimensions, shape and surface quality of the workpiece obtained during processing at the previous transition. The size change depends on the state of the initial surface (see table 1).

Moreover, the dimensional accuracy does not change significantly. Adverse conditions for processing the workpiece near the ends lead to increased plastic deformation of the workpiece in areas of length 3 ... 15 mm.

Table 1

Changing the size of the surface of the workpiece when rolling the proposed head depending on the roughness of the original surface Pretreatment Method Roughness parameter Ra, mm The size by which the size changes after processing, mm Turning 6.3
3.2
1,6 0.02 ... 0.06
0.01 ... 0.04
0.01 ... 0.02 Shaving with a (wide) cutter 3.2
1,6 0.01 ... 0.02
up to 0.01 Grinding 3.2
1,6 0.01 ... 0.03
0.01 ... 0.02

It is most expedient to treat the initial surfaces of the 7 ... 11th qualifications by rolling.

With surface plastic deformation by the proposed head, roughness parameters Ra = 0.2 ... 0.8 μm are practically achieved with the initial values of these parameters 0.8 ... 6.3 μm. The degree of reduction in surface roughness depends on the material, working force or interference, feed, initial roughness, head design, etc.

The rolling of the proposed head should be carried out so that the desired results are achieved in one pass. Do not use the reverse stroke as a working stroke, as repeated passes in opposite directions can lead to excessive deformation and peeling of the surface layer.

The speed does not significantly affect the processing results and is selected taking into account the requirements of productivity, design features of the workpiece and equipment. Usually the speed is 30 ... 150 m / min. The value of the rolling force is selected depending on the purpose of the treatment. The optimal force P (H) corresponding to the maximum endurance limit is determined by the formula: P = 500 + 1.66 D ² , where D is the diameter of the workpiece being rolled in. The feed during the run-in is 0.2 ... 3 mm / rev. The optimal supply of S _e for one deforming element should not exceed 0.1 ... 0.5 mm / rev. The feed per revolution of the workpiece is determined by the formula: S = kS _e , where k is the number of deforming elements.

Lubricating and cooling fluid during the run-in are engine oil, a mixture of engine oil with kerosene (50% each), sulfofresol (5% emulsion). Cast iron processing is recommended without cooling.

The proposed head extends technological capabilities, increases the roughness parameter of the processed surface, increases its hardness to a considerable depth due to the smoothing effect of a large number of deforming elements, increases productivity by increasing the contact spot of deforming elements with the treated surface, the use of large feeds and regulation of working forces, and also allows process screw surfaces of screws and eccentric shafts at reduced cost process and low-cost manufacturing of the head due to the compactness and simplicity of its design.

Information sources

1. Nikiforov A.V., Sakharov V.V. Technological capabilities and prospects of finishing and hardening with an elastic tool. - M., 1991 (Mashinostroit. Pr-in. Ser. Progressive technology. Processes in engineering: Obzor. Inform. / VNIITEMR. Issue 5) - S.31-36, Fig. 16-17. - prototype.

2. A.S. SU 1666290 A1, MKP V24V 39/02, 07/30/1991.

Claims (1)

A reinforcing head with an elastic tool, comprising a housing with flanges located at its ends and deforming elements in the form of turns of a coil spring installed in the housing and made of round steel wire, characterized in that the spring is rolled along a helix with the possibility of setting the workpiece and rigidly fixed by the ends in the flanges, made with the possibility of rotation and fixation in the circumferential position to provide impact on the workpiece of the coil of spring, which are located across to the workpiece.

Images