RU2344906C2 - Method of thread making - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: method includes formation of geometry and electrocontact processing of thread full profile by tool, which is displaced along screw line relative to component installed with the possibility of rotation. Prior to electrocontact processing, thread of identical dimension type is shaped on electroconductive insert and component, at that electrocontact processing is done initially by thread of electroconductive insert, and then - by component thread with supply of electric current to the tool via electroconductive insert.

EFFECT: higher quality of screw surfaces.

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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 full profile of the thread with tools moving along a helical line, by applying an electric current GB 798609, B23G1 / 00, 1958, 4 C.

However, this method is based on the supply of electric current through the part and tool, which does not allow to increase the wear resistance and strength of the thread at the beginning of its input part.

The objective of the invention is to improve the quality of screw surfaces due to electrical contact processing of the surface layer of thread and the formation of metal fibers

This object is achieved by the fact that in the method of manufacturing threads before electrical contact machining from one installation, a thread of the same size is formed on the electrical conductive insert and the part, and electrical contact processing is carried out initially by threading the electrical conductive insert, and then by threading the part with the supply of electric current to the tool through conductive threaded insert.

The drawing shows a processing circuit with electric heating of the thread of the part.

The invention is illustrated by the following examples.

It is known that a threaded connection is made by screwing a thread of one part (nut) relative to a similar thread of another part (bolt). For screwing threaded parts, it is necessary that the lead-in of the turns of the threads of the parts does not have nicks and crushing of the turns. During electrical contact machining of the thread, it is not possible to install the tool at the beginning of the turns of the lead-in. Therefore, part of the thread turns to be of low hardness and during operation or repair of machines, its deformation from mechanical action by metal parts of other parts or metalwork is noted. To restore such a thread, repair actions are necessary by threading with special tools.

Technologically, the manufacture was as follows.

On the machine 16K20 thread processing was performed according to the proposed method. The bolt blank (steel 45 GOST 1050-88) was processed on a machine with a diameter of 18.2 mm. An insert was made (steel 45 GOST 1050-88) with a diameter of 18.2 mm and a height of 10 mm. A centering hole of 3.15 mm was made on one side of the end face of the insert. The insert was pressed to the end surface of the bolt and centered using a rotating center from the side of the headstock of the lathe. When assembled, the bolt blank and insert were machined to a size of 17.82 mm. Then, a M18 thread was cut with a pitch P = 2 mm on the bolt and insert with a threaded cutter.

Then made an electrical contact thread processing. Electric current was supplied to the tool and to the threaded insert. Having adjusted the machine to the step S = P, the tool was set along the profile of the threaded insert, and creating a reliable contact Q in the connection of the tool with the thread, the rotation of the part and the source of electric current were 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 processing speed and temperature in the contact zone, combined with the rapid cooling of 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. During electrical contact processing, the thread of the insert and the bolt is made as a whole, therefore, the processing of the thread of the part was performed from the beginning of the lead-in.

The application of the above method of manufacturing threads allows you to improve the quality of the thread of the cavity and side sections, as well as the durability of the threaded parts.

Claims (1)

A method of manufacturing a thread, including the shaping of the geometry and the electrical contact processing of the complete profile of the thread with a tool that is moved along a helix relative to the part mounted for rotation, characterized in that before the electrical contact processing the forming of a thread of the same size is performed on the electrical conductive insert and the component, and the electrical contact processing is carried out initially by threading an electrically conductive insert, and then by threading a part with an electrical supply current to the instrument through the conductive insert.