JP3289949B2 - Closed circulation gas quenching device and gas quenching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas quenching apparatus capable of performing gas quenching of a metal processing member at low cost and with low distortion, and a gas quenching method using the same.

[0002]

2. Description of the Related Art Generally, when quenching a metal workpiece, it is immersed in a liquid quenching agent such as oil, water, a polymer, or a molten salt bath as a cooling medium. These liquid coolants are selected according to the characteristics of the processing member, but since they are liquid, the cooling rate of the processing member during the quenching process is largely governed by the inherent characteristics of the quenching agent. Is difficult, and after quenching, it is necessary to treat a quenching agent attached to the processed member.

On the other hand, gas quenching has recently attracted attention because it does not have the above-described problems and does not require a quenching agent treatment after quenching. When gas quenching,
First, a quenching gas is supplied into the processing chamber to a predetermined pressure, and then circulated through the processing chamber through a heat exchanger by a blower installed in the processing chamber or a quenching gas circulation system connected to the processing chamber. While quenching the metal workpiece. In order to harden a metal work member, it is necessary to cool at a speed higher than the critical cooling rate, and in the case of steel with poor hardenability, a quenching gas is pressurized to, for example, several tens of atmospheres, and pressurized. Gas quenching.
In this case, the equipment must be filled with a high-pressure gas atmosphere and maintain a non-oxidized state in terms of quenching quality.

For example, in the case of steel having good hardenability such as tool steel, it can be hardened at a low pressure (Japanese Patent Laid-Open No. 60-18 / 1985).
4625), in the case of a bearing steel having a lower hardenability, the quenching gas is pressurized to 10 to 40 atm (in the embodiment, 16 atm) and gas cooled (the embodiment, helium gas having good thermal conductivity). By doing so, it became possible to harden a small part having a diameter of 10 mm (JP-A-1-149920). However, carburized case hardened steels and general low alloy steels have inferior hardenability to bearing steels, and parts made of these steels could not be hardened by such general heat treatment equipment.

Recently, however, metal working members to be quenched are arranged and arranged into a working member group, and a quenching cylinder having a shape conforming to the shape of the working member group is used for efficient gas quenching. (Japanese Patent Laid-Open Publication No.
No. 165756). When such a quenching cylinder is used, the quenching gas passes at high speed and uniformly between the inside of the quenching cylinder, the outside of the processing member and the inside of the processing member, and between the arrangement jigs. The cooling of the individual working members is extremely uniform, the quenching effect is large, and the working members made of low alloy can be quenched without using high-pressure quenching gas. However, when quenching is performed by the method described in this publication, quenching distortion occurs in a metal processed member, and as a result, the dimensional accuracy of the processed member is not sufficient, and improvement is demanded.

The present invention has been made in view of the above circumstances, and a gas quenching apparatus and a gas quenching apparatus capable of improving dimensional accuracy of parts by reducing quenching distortion when gas quenching is performed using a closed gas quenching apparatus as much as possible. It is an object of the present invention to provide a gas quenching method using a gas.

[0007]

Means for Solving the Problems The present inventors have conducted various studies to solve the above problems. As a result, the problem with the conventional closed gas quenching apparatus is that the cooling rate during the quenching process is limited. The inventors have found out that this is caused by being constant, and have accomplished the present invention. That is, the apparatus of the present invention has a quenching cylinder having a shape adapted to the shape of the processing member group arranged and arranged, and having a quenching gas supply unit and a discharge unit at both ends thereof,
In the system of the quenching gas circulation device composed of the blower and two heat exchangers arranged on the inlet and the outlet side of the blower, valves are respectively arranged near both ends of the quenching cylinder, and then switched in four directions A valve is arranged, and a circuit for short-circuiting the quenching gas circulation circuit is provided between the four-way valve and the two heat exchangers,
A valve with an actuator is arranged in this short circuit. In the method of the present invention, the quenching gas is sent from one end of a sealed gas quenching cylinder having metal workpieces to be gas-quenched arranged and arranged as a group of processing members and adapted to the shape of the group of processing members. In the method of gas quenching by exhausting or exhausting quenching gas from the other end, the quenching gas main circulation circuit is short-circuited and short-circuited without passing through the quenching cylinder in which the processing member group is arranged A circuit is provided, the valve opening of which is controlled by a valve with an actuator provided in this short circuit, the flow rate of the quenching gas in the quenching cylinder during the quenching process is arbitrarily adjusted, and It is characterized in that the cooling rate is controlled to a cooling rate suitable for the material characteristics and shape. When quenching a metal processing member having an uneven cross-sectional shape, gas quenching can be performed while adjusting the cooling rate of the thin portion using a spacer having a shape for masking the thin portion. .

[0008]

In the present invention, a circuit for short-circuiting the quenching gas circulation circuit is provided between the four-way valve and the two heat exchangers as described above, and a valve with an actuator is arranged in this short-circuit circuit. Therefore, the opening / closing degree of the valve with an actuator can be adjusted to an arbitrary opening degree. Therefore, the flow rate of the quenching gas in the quenching cylinder during the quenching process can be arbitrarily adjusted, and the metal to be quenched can be adjusted. By controlling the cooling rate of the processed member to a cooling rate suitable for the material properties and shape, it is possible to perform appropriate quenching such as quenching the transformation nose region or higher and gradually cooling the following region. It can be reduced as much as possible.

Hereinafter, an example of the apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 diagrammatically shows the device according to the invention. In FIG. 1, reference numeral 1 denotes a quenching cylinder.
Has a shape conforming to the shape of the processing member group 2 arranged in a line, and has quenching gas supply portions or discharge portions 3 and 4 at both ends thereof.
A valve with an actuator 12, 13 near the supply or discharge section 3, 4; a blower 6; and two heat exchangers 7, arranged on the inlet and outlet sides of the blower 6.
8 together form a quenching gas main circuit. In such a device, the four-way switching valve 5 is disposed after the valves 12 and 13 with the actuator, and the four-way valve 5 is provided.
A short circuit for short-circuiting the main circulation circuit is provided between the two heat exchangers 7 and 8, and a valve 9 with an actuator is provided in the middle of the short circuit.

In the apparatus shown in FIG. 1, the valves 12 and 13 with the actuator are closed, the valve 9 with the actuator is opened, the quenching circulation blower 6 is operated, and the quenching gas is blown by the blower 6 and the heat exchanger. 7, circulate like a valve with an actuator 9, a heat exchanger 8, and a blower 6. The processing member group 2 is suspended and loaded in the quenching cylinder 1 and the lid 1
Immediately after sealing by 1, the valves 12 and 13 with the actuator are fully opened, and at the same time, the valve 9 with the actuator is controlled and operated so that the air volume becomes the initially set air volume. At the same time, in order to obtain better uniformity of the cooling rate, the quenching gas flow direction in the quenching cylinder 10 is operated for several seconds by operating the 4-way valve 5 with an actuator provided in the quenching gas main circuit. Is switched up and down at a frequency of several tens of seconds to perform quenching. Subsequently, the quenching is completed while controlling the opening of the valve with an actuator 9 so that the cooling rate is adapted to the material characteristics and shape of the processed member group 2. The control of the opening degree of the valve with actuator 9 can be arbitrarily performed continuously and intermittently.

In the case of quenching according to the present invention, in the case of hardening the surface of a metal work member 15, a spacer 10 is arranged between the work members 15 and an element is added to the surface before quenching in a separately prepared surface hardening cylinder. Can be diffused. In this case, the surface hardening treatment becomes more uniform and hardens as compared with the case where the spacer 10 is not disposed.
Compared to the case where 5 are stacked without the spacer 10,
The uniformity of the quenching effect is improved. The shape of the spacer 10 is adapted to the shape of the processing member 15, and in order to reduce the quenching distortion of the processing member 15 having a non-uniform cross-sectional shape, the thin portion of the processing member 15 is formed by removing a part of the spacer 10. By masking with the masking material to be formed, and by cooling the individual processing members 15 more uniformly, distortion can be reduced.

FIG. 2 shows an example in which the metal working member 15 is carburized and quenched. The cross section of the metal processing member 15 shown in FIG. 2 is non-uniform, and there is a thin portion 16 every 120 °. When the processing members 15 are aligned, the processing members 1
As shown in FIG. 1, the spacers 10 and the processing members 15 are alternately arranged between the five members 5, stacked so that the processing members 15 do not directly contact each other, passed through the core rod 14, and prepared separately. After carburizing in a surface hardening treatment cylinder having a controlled carburizing atmosphere, the steel is successively moved into the quenching cylinder 1 to perform gas quenching. In this case, heating and moving can be performed in an atmosphere having any characteristics.

FIG. 3 shows the spacer 10 used in the stack of FIG. In the spacer 10, a masking material 17 is arranged at a portion opposed to the thin portion 16 of the processing member 15 with a small gap from the surface of the processing member 15, and the cooling rate of the thin portion 16 is reduced during the quenching process. Has a shape adapted to approximate For this shape, the cooling rate is measured by a temperature measuring element actually attached to the processing member 15, and its size, shape, and gap with the processing member are determined.

The quenching gas used in the present invention includes simple gases of general industrial gases such as nitrogen, helium, hydrogen, argon, carbon monoxide, carbon dioxide, and hydrocarbons; Gases and, in some cases, a mixture thereof with a liquid mist may be mentioned. These are gaseous quenching agents and have lower pollution than liquid quenching agents.

In the present invention, the quenching gas main circulation circuit is short-circuited, a short-circuit circuit in which an actuator-equipped valve 9 is arranged is provided, and the degree of opening and closing of the actuator-equipped valve 9 is controlled arbitrarily. The purpose is to adjust the amount of quenching gas sent through the main gas inlet circuit. by the way,
As the air supply amount adjusting means, besides this method, a method of controlling the output of the quenching gas circulation blower motor by an inverter or the like, or a method of arranging an adjustment valve in the main quenching gas circulation circuit and controlling the same can be considered. In the former case, the equipment cost is high, and in the latter case, when the regulating valve is closed, the pressure on the air supply side of the quenching gas circulation circuit increases and an excessive load is applied to the blower motor, which is not desirable.

[0016]

Embodiment 1 Outer diameter 80 mm, inner diameter 60 mm, height 20 m
m SCM420 steel grooved ring parts were carburized and then quenched using the apparatus of the present invention. The cooling rate at this time was measured by embedding a thermocouple having an outer diameter of 1 mm in the component, and measuring the increase in the roundness of the groove at this time. Table 1 shows the results.
The controlled cooling in Test 1 reduced the amount of strain to １ ／ compared to Test 2 in which controlled cooling was not performed. In addition, the quenching results at this time indicate that the surface hardness Hv (10) 826 to 8 was used for both tests 1 and 2.
45, the core hardness was equivalent in Hv (10) 312 to 334.

[0017]

[Table 1]

[0018]

Embodiment 2 This embodiment shows the effect of the presence or absence of masking when quenching according to the present invention. When a sliding gear made of material SCr420H and having a sparger on the outside and a spline on the inside is treated in a vacuum atmosphere at a temperature of 1193 ° K, carburizing + diffusion time of 4.2 × 10 ³ seconds and then N ₂ gas quenched The resulting roundness change at the bottom of the fork groove having an outer diameter of 85φ was compared between a jig with masking and a jig without masking. The effective hardened layer depth obtained by the above heat cycle is 0.45 mm (atH
v513). Table 2 shows the results.

[0019]

[Table 2]

As shown in Table 2, when the masking was performed according to the present invention, the average change amount was improved by about 20% and the variation was improved by 50% by the masking.

[0021]

As described above, according to the present invention, gas quenching of carburized case hardened steel and general low alloy steel, which had been conventionally difficult to perform under special conditions and could not be performed under special conditions, can be easily performed. Can,
Moreover, simple equipment is provided without the need for high-pressure equipment,
It has excellent effects such as the quenching distortion of the processed part can be suppressed to a very small value.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view schematically showing one example of the apparatus of the present invention.

FIG. 2 is an explanatory view showing the shape of a processed member used in the embodiment of the present invention.

FIG. 3 is an explanatory view showing a spacer of the processing member of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quenching cylinder 2 Metal working member group 3 Quenching gas supply part or discharge part 4 Quenching gas discharge part or supply part 5 Four-way valve with an actuator 6 Blower 7 Heat exchanger 8 Heat exchanger 9 With an actuator Valve 10 Spacer 11 Sealing lid 12 Valve with actuator 13 Valve with actuator 14 Core rod 15 Metal work 16 Thin part 17 Masking material 18 Thick part

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C21D 1/18 C21D 1/62 C21D 1/767

Claims (3)

(57) [Claims] 1. A quenching cylinder having a shape conforming to the shape of a group of processing members arranged in a line and having a supply portion and a discharge portion for quenching gas at both ends thereof, a blower, an inlet and an outlet of the blower. In the system of the quenching gas circulation device composed of two heat exchangers arranged on the side, valves are arranged near both ends of the quenching cylinder, and thereafter, a four-way switching valve is arranged, and a four-way valve is arranged. A circuit for short-circuiting the quench gas circulation circuit between the heat exchanger and the two heat exchangers, and a valve with an actuator is arranged in the short-circuit circuit. 2. A metal working member to be gas quenched is arranged and arranged as a working member group, and quenching gas is supplied or exhausted from one end of a sealed gas quenching cylinder having a shape adapted to the shape of the working member group. In the method of quenching gas by exhausting or sending quenching gas from the other end, a quenching gas main circulation circuit is short-circuited, and a short-circuit circuit that does not pass through the quenching cylinder in which the processing member group is arranged is provided. The opening degree of the valve is controlled by a valve with an actuator provided in the short circuit, the flow rate of the quenching gas in the quenching cylinder during the quenching process is adjusted arbitrarily, and the cooling rate of the metal workpiece to be quenched is reduced. A gas quenching method characterized by controlling a cooling rate suitable for material characteristics and shape. 3. When quenching a metal processing member having an uneven cross-sectional shape, gas quenching is performed while adjusting a cooling rate of the thin portion using a spacer having a shape for masking the thin portion. 2. The method according to 2.