SU1611953A1 - Method of hardening cylinders - Google Patents

Abstract

The invention relates to heat treatment can be used in the heat treatment of cylinders. The purpose of the invention is to improve the quality of quenching by ensuring uniformity of mechanical properties along the length of the container. The method includes the rotational movement of the cylinder around the longitudinal axis and immersing it in a liquid when the horizontal position of the specified axis. At the same time, at the locations of the bottom and neck of the cylinder, from under the mirror of the liquid, its jets are delivered, which form a local rise in the level of the liquid. The height of the local lift with respect to the lower generatrix of the cylindrical part of the cylinder is determined by the dependence H _ut = R {1-COS [ARCCOS (1-H _O ) / R] ^. S _ut / S _o }, where R is the radius of the cylindrical part of the cylinder

mm

H _O - immersion depth of the lower generatrix of the cylindrical part of the cylinder, mm

S _O , S _ut - respectively the maximum thickness of the walls of the cylinder and the thickened parts of the bottom and neck of the cylinder, mm. 1 tab. 1 il.

Description

The invention relates to heat treatment and can be used in the heat treatment of cylinders.

The aim of the invention is to improve the quality of processing by increasing the uniformity of the distribution of mechanical properties along the length of the cylinder.

The drawing shows a scheme for implementing the method.

The method is; 1; 4est as follows.

Heated to a given TeNmepaTypbi cylinder 1 u1 is rolled onto mechanism 2 rotates, located above. The water mirror 3 of the tank 4 is filled. When placed on mechanism 2, cylinder 1 acquires a rotational motion) by lowering 1 N: exaHH3Ma 2 of rotation in a vertical plane

The rotating cylinder 1 is immersed in water at a depth h corresponding to the wall thickness SQ of the cylindrical part of the cylinder 1. Before this operation, in order to create a local increase in the water level in the bath tube 5, located in the locations of the thickened parts of the cylinder (under the bottom and neck), are served medium pressure - water or compressed air - so that the depth of the thickened

about

parts of the hyv corresponded to the magnitude, the limit of emry from the specified ratio. Rotating in position, shown in the drawing, the balloon has a different depth of immersion along the entire length depending on the wall thickness of its various parts: a cylindrical part with a wall thickness of S-width to a depth of hg, and a bottom and neck with a wall thickness of a bit to a depth hu. After the cooling time specified by the technology has expired, the cylinder 1 is lifted above the bath with the help of mechanism 2 and transferred for conducting the following technological operations. The next heated cylinder is laid on the released mechanism 2, and the cycle is repeated.

Thus, thanks to the fact that the level of the cylinder loading along its length during quenching, depending on the wall thickness, sets the variable, the same cooling rate of all its parts is ensured, which makes it possible to increase the uniform distribution of mechanical properties along the length of the cylinder and thereby increase the operational reliability of such critical products, which are high pressure vessels (cylinders).

The proposed and known methods are tested on the pilot

installation, including a stove for heating and a mechanized bath. For heating, an electric conductivity furnace is used with an operating temperature limit of up to 1300 ° C. The heating temperature of the cylinders is controlled using a thermocouple TXA, whose hot junction is located in the internal cavity of the cylinder. As a secondary device using a potentiometer type KSP-3, accuracy class 0.5,

The mechanized bath is a water tank and a turning device designed for

,

to

15

20

25

thirty

35

m

45

50 о55

-

40

rotating a horizontal product and moving it in a vertical plane. The temperature of the water in the bath is 18-23 ° C, the rotation frequency of the cylinders is 50-52 rpm.

In order to create a local increase in the level of water in the bath at a depth of 150-160 mm from the bath mirror under the bottom and neck of the bottle, nozzles are installed with a cross section (diameter) of 3.5 mm to supply pressurized water. Regulating taps of each of these pipes are located outside the bath. The limits of pressure regulation of water supplied through these nozzles are 1-5 kgf / cm. By adjusting the water pressure, the height of the level of the bath mirror is changed, ranging from 0 to 230 mm.

The heat treatment includes heating the cylinders up to 870j: 10 C, over the course of 20 minutes, water-air cooling in a mechanized water bath to a temperature of 600 C at a speed of 30 degrees / s and subsequent air cooling. The specified mode of single heat treatment (without tempering) should provide the following combination of mechanical properties: G gei 70 kgf / mm% G -r 42 kgf / mm2, Jb. 18%, KCV g - 8 kgf. M / cm2.

The experiments were carried out on carbon cylinders in the amount of 20 pcs. of steel 45 with a diameter of 219 mm, a wall thickness of 7 mm, a length of 1400 mm, the maximum wall thickness of the bottom and neck 14 mm, and the transition from the wall thickness of the cylindrical part of the cylinder to the maximum wall thickness of the bottoms and a throat smooth. 15 cylinders are processed in accordance with the proposed method (options 1-3), 5 cylinders - in accordance with the known (option 4).

During heat treatment according to the proposed method, the immersion level of the balloon is set variable along its length, namely, the immersion depth of the cylindrical part of the balloon is set to h, 97 97 mm, which provides the required cooling rate (30 degrees / s) of the cylindrical portion of the balloon, with wall thickness So 7 mm The depth of the bottom of the bottom and throat Zina calculated. from the given ratio by their maximum wall thickness, equal to S UY 1.4 mm:

1611953

arccosd - e-LZ, h R 1 - cos

 I., Sc

 Marccosd 1-cos | L. 110

 215 MM.

When zkalka cylinder positioned in such a way that the maximum wall thickness of the bottom and neck coincides with the maximum height of the level of the bath mirror.

For all cylinders (15 pcs.), Processed by the proposed method, the immersion depth of their cylindrical part is h 97 mm, and the depth of the bottom and hu neck is set according to option 1 (5 cylinders) 215 mm, i.e. immersion depth corresponds to the value calculated from the above formula, for option 2 (5 cylinders) 210 mm, i.e. immersion depth is less than calculated by the formula, for option 3 (5 cylinders) 219 mm, i.e. The immersion depth is greater than that calculated by the formula.

Heat treatment of cylinders in the amount of 5 pcs. using the known method (option 4), they are carried out with the same immersion depth of their cylindrical and thickened parts equal to 97 mm.

The averaged results of experimental testing of the proposed and known methods of quenching for each variant are given in the table ..

As can be seen from the table, when testing the proposed method of quenching with provision of a variable immersion level of the cylinder along its length, calculated using the described ratio, along the entire length of the thick-walled product (in the cylindrical part of 7 mm, in the thickened parts of the bottom and neck. 14 mm) get the same microstructure of thin lamellar pearlite and 15-20% ferrite (option 1), which indicates unambiguous cooling rates in all parts of the product. The same type of microstructure along the length of the product provides a fairly high uniformity of the distribution of mechanical properties, the values of which satisfy the requirements.

g LQ7 l1

arccosd - YJoU-IM

20

25

 Oh changing the level

end parts score ant 2) or higher (varying the calculated personal speeds to cool the product 15, as a result of austenite, temperature shafts occur with personal types; loading into water by cooling speed leads to an increase in the structure of the metal of the colony component that neither the strength characteristics unevenly lazy along the length of the balloon

Cooling rate in version 3, in the end portions of the ball of 30 quenching structures, meaning the impact strength

When sampling from the ba in the case of immersion 35 water to a depth of 97 mm in the metal of a cylindrical metal, a cooling requirement of 30 degrees / s is achieved, the decomposition of austenite with about 40 structures is identical to that obtained by quenching by the method - thin plastic + 15-20% ferrite. The mechanisms are similar to the obtained 45 research institutes of the proposed model, however, in thickened h, the cooling rate required that the austenite drive 50 is formed with ferrite-pearlite with strict plastic and hard properties. MI And the properties of the metal by 55 have significant

Thus, the comparison with the uniform distribution properties after

arccosd - e-Lcos

- i., Sc

arccosd L. r LQ7 L1

arccosd - YJoU-IM

20

25

 When changing the immersion level

the end parts of the cylinder are lower (option 2) or higher (option 3) compared to the calculated one, different cooling rates are achieved along the length 15 of the product, as a result of which the austenite disintegrates in separate temperature ranges with the formation of various types of structures; When immersed in water according to option 2, a lower cooling rate of the collar and neck leads to an increase in the ferrite component amount in the microstructure of the metal, which reduces the values of the strength characteristics and increases the irregularity of their distribution along the length of the cylinder.

The cooling rate is achieved in option 3, which leads to the completion of intermediate quenching structures in the end portions of the balloon, which reduces the value of toughness and necessitates subsequent tempering.

When testing a known method in the case of a balloon dipping into water at a depth of 97 mm (option 4), the required cooling rate of 30 degrees / s is achieved in the metal of the cylindrical part of the cylinder, ensuring the decomposition of austenite with the formation of a microstructure that is identical to hardening by the proposed method - thin plate pearlite + 15-20% ferrite. The mechanical properties are close to those obtained during testing of the proposed method and meet the requirements. However, in the thickened parts of the balloon, the cooling rate is much lower than the required one, which leads to the decomposition of 0 austenite with the formation of an equilibrium ferritic-perlitic structure with high plastic and low strength properties. Microstructure and properties of the metal along the length of the balloon. 5 have a significant difference.

Thus, the proposed method in comparison with the known increases the uniformity of the distribution of mechanical properties after quenching over

the length of the cylinder, including its bottom and neck, and, consequently, increases the operational reliability of the cylinders. This is due to the fact that when the immersion level of the cylinder varies along its length in accordance with the described ratio, conditions are created that ensure the same cooling rate of all parts of the cylinder.

Claims (1)

Iso-bro formula A method of quenching cylinders, which includes immersing a horizontally arranged cylinder in liquid, characterized in that, in order to improve the quality of quenching by ensuring uniform mechanical properties along the length of the cylinder, an additional operation of local leveling is performed liquids at the locations of the bottom and neck of the cylinder by supplying jets of liquid from under its mirror, and the height of the local level of the liquid in relation to the lower generatrix of the cylindrical part of the cylinder is determined by the dependence - where R - cos EarccosQ - hp / R) - S  0 the radius of the cylindrical part of the cylinder, MMJ immersion depth of the lower forming cylindrical part of the cylinder, mm accordingly, the maximum wall thickness is the cylinder and the thickened parts of the bottom and neck of the cylinder, mm. same 97 97 219 97 P tokkoplvstinsky F 15-2pg Pr + F 20-30 L then kop astinchaty F 1U20g P 50% + F 50% Perspective requirements of Ufa Etc and “e, and in and with. P - pearl t, F - Ferrite. Pr - industrial structure. 81/8262/6015/15 7.9 / 6.5 76/6452/3819/21 8.5 / P  8.0