RU2222609C2 - Method of hardening steel parts and device for realization of this method - Google Patents

Abstract

FIELD: heat treatment of parts. SUBSTANCE: proposed method includes heating part to austenization temperature and cooling it in hardening tank containing at least two immiscible hardening media of different density located in way of motion of parts; rate of motion of parts is determined preliminarily by cooling capacity of liquids and part hardening curve. Device proposed for realization of this method includes hardening tank having form of U- shaped pipe; its first half is located at angle and is provided with conveyer and second part is located vertically; first half of tank is located an angle of 10-30 deg. and second half of tank is adjustable in inclination and is provided with conveyer. EFFECT: extended functional capabilities. 3 cl, 3 dwg, 1 ex

Description

 The invention relates to the field of heat treatment of steel in order to increase its mechanical properties (hardness, strength, toughness, etc.) and can be used for liquid separation techniques.

A known method of hardening of products (SU 1425223, MKI C 21 D 1/78, publ. 23.09.88), including heating above AC ₃ , cooling in a liquid with the introduction of ultrasonic vibrations of the same intensity.

 The need to introduce ultrasonic vibrations into the method significantly complicates the method, and the source of such vibrations also complicates the device that implements the method.

A known method of low strain hardening after nitrocarburizing (RF patent 2112811, IPC 6 C 21 D 1/58, publ. 06/10/96), including austenization, cooling the part in cold oil to 100 ^o , transferring the part to boiling water and cooling in air.

 With this quenching method, it is difficult to obtain a martensitic structure, since the rates of part temperature decrease can be less than critical.

 The closest in technical essence and the achieved result is an installation for hardening products in two environments (SU 783352, IPC 7 C 21 D 1/63, 03/03/1980), in which a hardening method is disclosed, which includes heating and cooling of parts moving in a quenching tank with two quenching media (water and oil) with different densities and not miscible with each other and located along the movement of the parts.

 The closest in technical essence and the achieved result for the device is a tank for cooling rails in oil (SU 57106, IPC 7 C 21 D 1/63, 05/31/1940), including a quenching tank in the form of a U-shaped pipe, the first half of which is equipped with a conveyor and is located at an angle to the vertical, and the second is located vertically.

 The disadvantage of this method is the unpredictable results of the hardening process, and the disadvantage of the device is the use of oil in the initial portion of the hardening process.

 The objective of the invention is the expansion of the functionality of the method and device.

 The task is achieved by a method of hardening steel parts, which consists in heating the parts to an austenization temperature, cooling the moving parts in a quenching tank with at least two quenching media with different densities, not miscible with each other and located along the parts. In contrast to the prototype, the location of the quenching media along the movement of the parts in the quenching tank and the speed of the parts are preliminarily determined by the cooling ability of the liquids and the necessary quenching curve of the parts.

The task is also achieved by a device for hardening steel parts, containing a quenching tank in the form of a U-shaped pipe, the first half of which is located at an angle and has a conveyor, and the second half is located vertically, while in contrast to the prototype, the first half of the tank is located at an angle of 10- 30 ^o , and the second half of the tank is made with the possibility of adjusting the angle of inclination and is equipped with a conveyor.

 The invention is illustrated by drawings. 1 shows a hardening curve; in FIG. 2 - the basic design of the device for hardening; figure 3 - modification of the design of the device.

Consider the process of hardening steel parts. The aim of quenching is mainly to obtain a martensitic structure, which means that in the upper temperature range (t> 350 ^o , Fig. 1), the cooling rate should be high, and in the lower interval - much less. A quenching medium providing such requirements practically does not exist. Thus, in the initial cooling period, it is necessary to use fluids that naturally have high cooling ability (SU 783352 - prototype), or fluids that have high cooling ability artificially (SU 1425223 - analog). In the final cooling period (t <350 ^o ), in order to reduce the cooling rate, it is necessary to transfer parts to the quenching tank with another cooling medium (RF Patent 2112811 - analog) or reduce the cooling intensity (SU 783352 - prototype).

An example of a specific implementation of the method
The proposed method is as follows. To obtain the necessary properties from the part, the technologist determines the quenching curve (Fig. 1) of the steel part. Of the many quenching media, several which are not miscible with each other, with different densities and cooling capabilities, are isolated. At least two fluids providing a quenching curve are selected experimentally or by calculation. In the quenching tank, the liquids are arranged in accordance with the direction of movement of the part in the tank. As a rule, first they have a liquid with a greater cooling capacity and then with a lower one.

 Figure 2 shows the basic design of the device for hardening steel parts. The device comprises a quenching tank 1, a conveyor 2, a first half 3 of a U-shaped pipe, a second half 4 of a U-shaped pipe.

The implementation of the device for hardening steel parts of the first half of the quenching tank, located at an angle of 10-30 ^o , and the second half with the ability to adjust the angle of inclination and equipped with a conveyor, allows you to use the device for both small and large parts, while providing a hardening curve .

 A device for hardening steel parts works as follows.

 We have a hardening curve for parts (for example, nuts). Two fluids are selected (e.g. water and mineral oil). First, water having a high density is poured into the device, and then oil is brought to the levels shown in FIG. 2. The level between oil and water should be 3..5 cm above the upper junction of the first and second halves of the U-shaped pipe of the device. Parts heated in the furnace to the temperature of austenization are fed into the second half of the U-shaped pipe of the device, where they are intensively cooled by water. Falling onto the conveyor, parts are carried away by the conveyor, moving first in water and then in oil.

 The proposed method and device for its implementation can expand the functionality of hardening of steel parts.

Claims (2)

1. The method of hardening of steel parts, including heating the parts to an austenitizing temperature, cooling moving parts in a quenching tank with at least two quenching media with different densities, not miscible with each other and located along the parts, characterized in that the location of the quenching media in the direction of movement of the parts in the quenching tank and the speed of movement of the parts is preliminarily determined by the cooling ability of the liquids and the necessary curve of the quenching of the parts. 2. A device for hardening steel parts, containing a hardening tank in the form of a U-shaped pipe, the first half of which is located at an angle and has a conveyor, and the second half is located vertically, characterized in that the first half of the tank is located at an angle of 10-30 °, and the second half of the tank is made with the possibility of adjusting the angle of inclination and is equipped with a conveyor.

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