RU2350440C2 - Method of production of parts with key slot - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: proposed method comprises fabricating part, producing key slot followed by electric-contact processing and heating. Prior to processing, tool roller is produced with its diameter equal to that of the part. Contact surfaces of the part and tool roller key slots are aligned to bring them into contact. Electric-contact processing is carried out by rolling the tool roller on over the part diametral surface.

EFFECT: higher quality of machine parts in producing key slots of outer and inner surfaces.

1 dwg, 2 ex

Description

The invention relates to mechanical engineering and can be used in the manufacture of keyways on the outer cylindrical surfaces of machine parts.

Known methods for the manufacture of keyways on parts formed by cutting methods, with subsequent methods of thermal or chemical-thermal treatment [Polyak MS Hardening technology. - M.: Engineering, L.V.M. - SKRIPT, 1995].

However, with volumetric methods of thermal or chemical-thermal treatment, the entire surface of the keyway is exposed to heat exposure, including the stress concentration zone at the base, which leads to the appearance or development of microcracks and reduces the quality of parts in operating conditions.

A known method of manufacturing keyways (RU 2243070, IPC 7 V23H 9/04, 12/27/2004).

However, this method is based on electric heating of the surfaces of the keyway with two electrode tools, which during processing must be placed inside the keyway of the part, which is extremely difficult, especially when processing grooves of a small size.

The objective of the invention is to improve the quality of the keyways in their manufacture with the hardening of the side surfaces in an electric contact way.

The drawing shows a diagram of the electrical contact processing of the keyway according to the proposed method.

The task is achieved by a method of manufacturing a part with a keyway, including the manufacture of the part, the formation of the keyway and subsequent electrical contact processing with heating the part, while before processing the tool roller is made with a diameter equal to the diameter of the part, with a keyway whose dimensions are smaller than the nominal dimensions of the keyway parts, combine the contact surfaces of the keyways of the part and the tool roller, creating a force contact between them, and the electrical contact the work is carried out during mutual rolling of the tool roller along the diametrical surface of the part.

The invention is illustrated by the following examples.

On a low-speed shaft with a diameter of 75 mm (steel 45 GOST 1050-94) of the power reducer Ts2-300, a keyway is formed by milling with a width of 20 mm and a depth of 8.15 mm. The shaft operates under alternating loads. The requirements for hardness of parts are set within 42 ... 48 HRC, which provides for hardening and subsequent average tempering.

When a keyway is formed on the parts, due to technological factors, microcracks can form in the base zone, especially in the radius part. Hardening and subsequent tempering lead to the appearance of thermal cracks in dangerous groove sections of the groove, and also contribute to the development of microcracks obtained at the stage of forming keyways. In addition, during bulk heat treatment, oxidation and decarburization of the surface layer constantly occur. In operating conditions, this leads to emergency destruction of the shaft in the area of the keyway. In addition, due to the insufficient strength of the groove, its wear on the lateral surfaces occurs, especially in the upper part at the interface between the keyway and the diameter of the part. The operating conditions of the connection are violated, and the machine must be stopped for repair work.

To improve the quality of the part with a keyway, they were contact-electrically processed to ensure the effect of hardening of the executive surfaces, without affecting the zone of voltage concentrators at the base.

Contact processing is carried out on a 16K20 screw-cutting lathe. From an electric current source 2 of an industrial frequency of 50 Hz, through current-carrying buses 3, the current is supplied to the tool roller 1 and to the shaft 4. Having provided reliable contact in the tool-surface connection, the electric current source is switched on and the tool d is moved and the part is rotated . The contact zone is heated to a temperature of 900-1000 ° C, and due to the rapid removal of heat into the body of the cold part, the surfaces of the keyway are quenched. During processing, the zone of electrical contact extends to the lateral surfaces of the keyway and to the diametrical sections of the shaft d adjacent to it without thermal effects on the base zone. As a result of processing, the hardness of the surfaces of the keyway and surface layer along the shaft diameter increases to 56 ... 60 with a hardening depth of 3 mm. The structure of the surface layer is fine martensite in the presence of residual austenite.

Contact processing according to the proposed method are keyway grooves of parts of cylindrical surfaces. The keyway processing is performed on parts from structural, alloyed, tool steels and cast irons.

A bronze roller is used as an electrode tool. When choosing a tool material, the following conditions were taken into account: electrical conductivity, high red resistance, and low hardness of the material. During processing, the tool roller rotates relative to the fixed axis, rolling around the outer diameter of the shaft.

Obtaining a hardened surface layer on the external surface being treated while maintaining the original structure and properties of the underlying metal layers will improve the quality of manufacturing parts with keyways and extend the life of the machines.

Claims (1)

A method of manufacturing a part with a keyway, including manufacturing the part, forming a keyway and subsequent electrical contact processing with heating the part, characterized in that before processing the tool roller is made with a diameter equal to the diameter of the part, with a keyway smaller than the nominal dimensions of the keyway on the part , combine the contact surfaces of the keyways of the part and the tool roller, creating a force contact between them, and the electrical contact processing is performed at mutual rolling of the tool roller along the diametrical surface of the part.