SU1257105A1 - Method of heat treatment of large bearing races - Google Patents

Description

The invention relates i-cH to heat treatment of steel and can be used in the heat treatment of rings of large rolling bearings made of steel

prokapyvaemosti.

. The aim of the invention is to reduce ring deformation during quenching.

Self-tempering in the die prevents the ring from being resized due to the occurrence of processes during tempering. When the rings are cooled in the stamp without self-tempering, during the subsequent tempering, the diameter of the rings decreases and their ovality increases. The absence of a punch, even when using self-tempering, leads to a large deformation, - tion of the ring already in the process of quenching cooling.

TchmepaTypy self-tempering is selected from the condition of providing the required solid. Experimentally, it was found that the HRC 60-63 hardness is optimal for bearing rings at a self-tempering temperature in the range of 200-250 ° C. In order to ensure the greatest possible reduction of the strain, the rings are removed from the die after completion of the self-tempering.

The heating temperature of the ring after cooling is terminated must be in the range of 200-250 ° C for the following reasons: at the heating temperature below 200 ° C, the formation of a trephine occurs at the base of a thin ring shoulder that limits the axial movement of the rollers; at temperatures above the hardness of the rings decreases below the required (below HRC 60).

The method is explained as follows.

The ring of the large-sized bearing is heated through in the furnace or in the inductor and placed in a cooling device containing a stamp, then intensive all-round cooling of the fast-moving bottom ring is carried out. The time of intensive cooling is chosen so that after stopping the supply of water in the core of the cross section of the ring, there is enough heat left enough to heat the surface to 200-250 ° C. This time is established experimentally by means of test hardening according to the indications of thermocouples attached to the ring surface. After heating the ring to the required self-tempering temperature and the beginning of its natural cooling, the air

0

20

25

thirty

35

40

45

50

55

the ring is removed from the die, cooled in air and subjected to low tempering.

The method is carried out as follows.

 The inner ring of the bearing (777/48 with an outer diameter of 310 mm, an inner diameter of 2 AO mm and a height of 129 mm from steel of a regulated calcability grade SHH4 is heated in a furnace for 30 minutes, and then transferred to a cooling device with a quenching die. Working part The stamp consists of sector crackers, which are pulled apart by the inner cone. The outer diameter of the cylindrical surface formed by the crackers corresponds to the inner diameter of the heat-treated ring in a cold state. n includes a pneumatic guide for the quenching water supply valve, water is supplied from a 6NDV type pump under a pressure of 0.2 MPa (2 atm) to all ring surfaces for 16. It is due to shrinkage during cooling that the hardenable ring covers the outer surface of the crackers and gets the required size. After cessation of the water supply, the ring surface is heated to 230 ° C and 60 seconds after the start of cooling the ring is removed from the die, cooled in air and subjected to low tempering.

During the heat treatment of the proposed method, the reduction of the inner diameter of the ring compared to the original dimensions before the heat treatment was 0.3 mm, the ovality decreased from 0.5 mm (before the heat treatment) to 0.05 mm (after the heat treatment), i.e. the invention allows to reduce the initial ovality from turning the ring. During quenching with intensive cooling in the die for 30 s, when the entire ring section was cooled to room temperature during intensive cooling and there was no self-tempering, followed by tempering in an oven at 160 ° C for 4 hours, the change in internal diameter averaged 0.85 mm , ovality of 0.2 mm. In addition, due to the absence of self-tempering, quenching cracks were found on the protrusions of the rings.

The use of the proposed method allows to reduce the deformation of the rings during heat treatment and makes it possible to produce rings

312571054

large-sized bearings made of steel, of steel of regulated-regulated hardenability with hardenable steel, including the steps by means of squelification of the bulk-surface heating to austenitic temperature, providing economy of alloying and comprehensive cooling in km elements, increasing reliability 5 stamping and tempering, which distinguish between - and durability of bearings, reduction with the fact that, in order to reduce the labor-intensiveness of heat treatment of the formation of rings, cooling in the stamp. rows. produced over a period of time

.The self-dispensing coloration formula of the invention at 200–250 ° C, and after completion of the self-discharging of the ring, a heat treatment method for the rings is drawn from the punch and cooled with large-sized bearings, preferably with air.

Claims (1)

Claims A method of heat treatment of large-sized bearings rings, mainly of steel of regulated hardenability, including squared heating to an austenitizing temperature and comprehensive cooling in a stamp and tempering, which, in order to reduce ring deformation, cool in the stamp time for self-release of the ring at 200-250 C, and after the completion of self-release of the ring is removed from the stamp and cooled in air.