RU2254967C1 - Thread making method - Google Patents

Abstract

FIELD: machine engineering, namely manufacture of threaded parts operating at sign-variable loads and in condition of abrasive wear.

SUBSTANCE: method comprises steps of finish strengthening working of part by means of tools at electrically heating part mounted with possibility of rotation. In order to enhance efficiency and quality of threaded surfaces, working is realized by means of combination tool whose mean portion is made of wear resistant electrically non-conducting material. Electric contact working of lateral surfaces of thread is realized at sliding pressure contact, at supplying electric current to tools and simultaneously applying effort to them. Mean portion of tool is used for working recess and forming micro-geometry and texture of metal fibers. Boundary portions of tool are used for quenching surface layer.

EFFECT: improved efficiency and quality of threaded surface.

1 dwg, 1 ex

Description

The invention relates to mechanical engineering and can be used in the manufacture of threads on parts operating under alternating loads and under abrasive wear.

Known methods of manufacturing threads that improve wear resistance and fatigue strength / Yakushev A.I., Mustaev R.Kh., Mavlyutov P.P. Improving the strength and reliability of threaded joints. - M.: Mechanical Engineering, 1979 - 215 p. /.

These methods of manufacturing threads do not allow complex to carry out hardening and finishing-hardening treatment with quenching of the thread profile along the entire perimeter with a simultaneous favorable arrangement of metal fibers.

A known method of manufacturing a thread on a part, including finishing and hardening processing of the complete profile of the thread with tools moving along a helical line, by applying an electric current GB 798609, B 23 G 1/00, 1958, 4 pages.

However, this method is based on the supply of electric current through the part and tool, which does not allow to increase the productivity of the process.

The objective of the invention is to increase the productivity and quality of screw surfaces by reducing time, finishing and hardening processing of the surface layer of thread and the formation of metal fibers elongated along the profile of the base.

Using the proposed method of manufacturing threads allows to reduce processing time, to increase the wear resistance and fatigue strength of screw surfaces after the formation of the geometry.

The problem is achieved in that in the method of manufacturing a thread, the processing is carried out with a combined tool consisting of a wear-resistant, but not electrically conductive material in the middle part, and the electrical contact processing of the side surfaces of the threads is performed by sliding power contact with the supply of electric current to the tools and simultaneous application of force, the middle part of the tool processes the cavity, forming microgeometry and the texture of the metal fibers, and the extreme sections of the tool produce tracing of the surface layer.

The drawing shows a processing circuit with electric heating.

The invention is illustrated by the following examples.

On the machine 1K62 thread processing was performed according to the proposed method. The M60 × 2.5 thread was cut with a cutter. Part material steel 45 GOST 1050-88, thread length 50 mm.

Technologically, the manufacture was as follows.

A tool consisting in the middle part of a wear-resistant, but not electrically conductive material, and the side parts of T15K6 carbide are sharpened at an angle of 60 degrees with a radius at the apex (0.108 ... 0.144) P, where P is the thread pitch.

Having adjusted the machine by a pitch of 2.5 mm, the tool was set along the profile of the start of the thread and, having created reliable contact in the connection of the tool with the thread, the rotation of the part and the source of electric current are successively turned on. A current of high strength and low voltage, concentrated in the “tool-thread” contact zone, leads to instantaneous heating of the surface layer of the side sections of the thread turns to a temperature of 900 ... 1000 ° C. The high speed and temperature of the treatment, combined with the rapid cooling of the surface-heated areas, leads to structural changes in the surface layer with quenching to a depth of 0.2 mm while maintaining the structure and properties inside the coil in the initial state.

The middle part of the tool exerts a force on the thread base. High wear resistance and hardness of the material of the middle part allows for finishing and hardening treatment with the formation of a favorably located texture of metal fibers. When the tool tip is subjected to force, a surface hardening to a depth of up to 0.08 mm with a hardness of up to 2600 HV, MPa is noted. In addition, the force effect of the tool allows the formation of residual compressive stresses in the cavity, which increase the fatigue strength of machine parts.

The use of the above method of manufacturing threads allows to reduce the cost, improve the quality of the helical surface of the cavity and side sections, as well as the durability of the threaded parts.

Claims (1)

A method of manufacturing a thread on a part, including finishing hardening processing with tools with electric heating of a part mounted rotatably, characterized in that the processing is performed with a combined tool consisting in the middle part of a wear-resistant but non-conductive material, and the electrical contact processing of the side surfaces of the thread is carried out with sliding power contact with the supply of electric current to the tools and the simultaneous application of force, and the middle part of the tool is processed it sinks into the cavity, forming microgeometry and the texture of metal fibers, and the extreme sections of the tool harden the surface layer.