RU2311279C1 - Strengthening tool with spring - Google Patents

Abstract

FIELD: manufacturing processes in machine engineering, namely apparatuses for finishing and strengthening stepped shafts, eccentric shafts or screws with small height of thread profile.

SUBSTANCE: apparatus includes holder with bearing assemblies and elastic rings. Deforming member is in the form of steel spring arranged on elastic rings and having turns of round cross section. On inner surface of turns lengthwise path whose profile is similar to that of outer surface of elastic rings is formed. Elastic rings are fixed to mandrel in direction of turns of spring; ends of spring are rigidly secured to mandrel with possibility of regulating spring turns tightness on elastic rings.

EFFECT: enlarged manufacturing possibilities of method.

5 dwg, 1 tbl

Description

The invention relates to mechanical engineering technology, in particular to finishing and hardening processing of workpieces such as smooth, stepped and eccentric shafts and screws with a small profile height of steels and alloys by surface plastic deformation (PPD) with a multi-element rolling tool with a deforming ring spring.

A known tool for finishing and hardening processing of cylindrical surfaces, containing a spring-loaded holder and mounted in it with the possibility of free rotation of the deforming element, made in the form of a spring with an outer diameter that is not a multiple of the diameter of the rolled surface [1].

The disadvantages of the known tool are narrow technological capabilities and the range of application: only for smooth cylindrical surfaces.

The objective of the invention is to expand the technological capabilities that the proposed tool will allow finishing and hardening processing of workpieces such as smooth, stepped and eccentric shafts and screws with a small profile height of steels and alloys by surface plastic deformation (PPD) with a multi-element rolling tool with a spring-loaded ring deforming spring.

The problem is solved using the proposed spring hardening tool for processing or stepped shafts, or eccentric shafts, or screws with a small profile height, containing a holder with bearings, in which a mandrel with a deforming element is installed, and it is equipped with elastic rings, the deforming element is made in the form mounted on elastic rings of a steel spring with round turns, on the inner surface of which a longitudinal track is made with a profile similar to the profile of hydrochloric surfaces of the elastic rings for possible contact surface track coil with the outer surface of the elastic ring, the latter being fixedly mounted in the direction of the turns of the spring on the mandrel, and spring ends rigidly embedded in the mandrel is adjustable preload turns of the spring by elastic rings.

Features of the design of the tool are illustrated by drawings.

Figure 1 shows a diagram of rolling a screw with a small profile height of the proposed spring reinforcing tool with deforming elements in the form of coils of an annular spring, general view; figure 2 - construction of the tool, a partial longitudinal section; figure 3 is a transverse section a - a in figure 2; figure 4 is a left view along B in figure 2; figure 5 - section b - In figure 2.

The proposed tool is designed to handle surface plastic deformation of the outer surfaces of rotation of workpieces such as smooth, stepped and eccentric shafts and screws with a large pitch and a small profile height, for example screw pump screws.

The processing is performed on turning, carousel, milling machines and machining centers with the message of the rotational movement of the workpiece - V ₃ , and the tool - the longitudinal feed movement S _CR when processing bodies of revolution and with the message reciprocating longitudinal and transverse movements when processing flat surfaces.

The tool contains a holder 1 in the form of a fork, in the bearings 2 of which a mandrel 3 is installed with a deforming element made in the form of a spring 4 with an outer diameter that is not a multiple of the diameter of the rolling surface of the workpiece 5.

The turns of the deforming spring 4 are wound close to each other and are made of round steel with a longitudinal track 6 on the inner surface.

The spring 4 is mounted on the mandrel 3 not directly, but on the elastic rings 7 fixedly mounted in the direction of the turns on the mandrel 3. The rings 7 are fixed on the mandrel 3 by known methods, for example by welding (not shown in FIGS. 2-3), by soldering, coinage, with screws and slats, etc. The elastic rings 7 are made of steel wire in the cross section of round, semicircular, rectangular, ellipse, etc. profile. Since the coils of the spring 4 cover the mandrel 3 with the rings 7 and are in contact with the tracks 6 with the outer surface of the elastic rings 7, therefore, the cross-sectional profile of the said track 6 of the coils of the spring 4 is similar to the cross-sectional profile of the outer surface of the elastic rings 7.

The ends of the deforming spring 4 are rigidly sealed on the mandrel 3 with the possibility of adjusting the interference of the coils of the spring 4 on the elastic rings 7. For example, in the design of the tool shown in Fig.1-2, the left end of the spring is rolled into a ring 8 and clamped by a nut 9, and the right end 10 - bent and pinched by a screw 11 through the bar 12.

In the general assembly of the tool, first, the screw 11 is fixed to the right end 10 of the spring 4 through the bar 12, and then the left ring end 8 is screwed with the nut 9, while the spring 4 is pre-screwed, eliminating the gaps in the contact area of the track 6 of the spring 4 with the rings 7 and creating a spring tension .

The tool is mounted on a support in a tool holder of a lathe (not shown), the workpiece, for example screw 5, is fixed in the chuck 13 of the spindle 14 of the headstock 15 and is pressed by the center 16 of the tailstock 17.

Before turning on the machine, it is adjusted to the necessary breaking-in force. Turn on the main movement - the rotation of the workpiece 5 and at the same time tell the tool a progressive longitudinal feed S _av

The essence of the process lies in the fact that during the operation of the tool, the deforming spring is installed with some interference with respect to the workpiece.

The rolling is carried out by the coil of spring 4, which exert pressure on the surface of the workpiece to be machined; in this case, when the protrusions of the machined screw run on the coil, the latter bends and bends the elastic ring located under the coil, and when the screw cavity runs on, the coil of spring and the elastic ring restore their sizes.

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 elastic elements, which are a deforming spring 4 and elastic rings 7, provides a rolling force at any point near or far from the axis of the tool on the surface to be machined.

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.

Pre-treatment of the workpiece: grinding to a roughness parameter value Ra = 0.4 ... 1.6 μm, as well as finishing turning of surfaces with a roughness Ra = 3.2 μm.

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

The deforming elements of the device, i.e., the spring and elastic rings, are made of steel: alloyed ШХ15, ХВГ, 9Х, 5ХНМ, carbon tool U10A, U12A, high-speed R6M5, P9. The hardness of the working surface of the coils of HRC 62 ... 65 steel. 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 tool 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 tool provides the necessary contact force of the deforming elements and the machined surface and almost does not reduce the errors of the previous processing, being a copy.

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 tool, 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 of the change in size depends on the state of the initial surface (see table).

Table
Changing the size of the surface of the workpiece when rolling the proposed tool, 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 0.025 ... 0.065 3.2 0.015 ... 0.045 1,6 0.010 ... 0.025 Shaving with a (wide) cutter 3.2 0.010 ... 0.025 1,6 up to 0.015 Grinding 3.2 0.015 ... 0.035 1,6 0.010 ... 0.020

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.

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

When surface-plastic deformation by the proposed tool, 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, tool design, etc.

The testing of the proposed tool 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.

, где D - диаметр обкатываемой поверхности заготовки. Подачу при обкатывании принимают 0,2...3 мм/об. Оптимальная продольная подача S_{пр э} на один деформирующий элемент не должна превышать 0,1...0,5 мм/об. Подачу на один оборот заготовки определяют по формуле: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 (N) corresponding to the maximum endurance limit is determined by the formula:

where D is the diameter of the rolled surface of the workpiece. The feed during the run-in is 0.2 ... 3 mm / rev. The optimal longitudinal feed S _{pr e} for one deforming element should not exceed 0.1 ... 0.5 mm / rev. The feed for one revolution of the workpiece is determined by the formula:

,

,

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 tool extends the technological capabilities of the surface plastic deformation process, increases the roughness parameter of the treated surface, increases its hardness to a considerable depth, increases productivity by increasing the contact spot of a large number of deforming elements with the surface being treated, and also reduces production costs and reduces manufacturing costs.

Information sources

1. A.S. USSR No. 218 681, IPC V24V 39/00. Tool for finishing and hardening of cylindrical surfaces. Braslavsky V.M. Application No. 1,052,441 / 26-8; 02/01/1966. Bull. Number 17.

Claims (1)

Spring hardening tool for machining either stepped shafts, or eccentric shafts, or screws with a small profile height, containing a holder with bearings in which a mandrel with a deforming element is installed, characterized in that it is equipped with elastic rings, the deforming element is made in the form of mounted on elastic rings of a steel spring with round turns, on the inner surface of which a longitudinal track is made with a profile similar to the profile of the outer surface of the elastic rings, for the possibility of contacting the surface of the path of the coil with the outer surface of the elastic rings, the latter being fixedly fixed in the direction of the coil of the spring on the mandrel, and the ends of the spring are rigidly sealed on the mandrel with the ability to adjust the tightness of the coil of spring on the elastic rings.

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