JPS6176611A - Method and device for high-frequency non-oxidation hardening - Google Patents

Abstract

PURPOSE:To harden safetly and cleanly a material to be treated without forming an oxide film by subjecting said material to high-frequency heating in a hermetic treating vessel in which a non-oxidative gaseous atm. is maintained then cooling the material by self-cooling and force gas cooling with the non-oxidative gas. CONSTITUTION:The member 9 to be treated is mounted to a jig 11 for mounting the member to be treated in the treating vessel 2 and is lowered; then the vessel is hermetically closed by a cap member 1. Gaseous nitrogen is introduced through a cooling medium supply pipe 5 from an ejecting hole 8 provided to a high-frequency hardening coil 7 to maintain the non-oxidative gaseous atmosphere in the vessel 2. While the jig 11 is rotated, the member 9 is high- frequency-heated by the high-density electric power via the coil 7. The member 9 in the high-temp. region is cooled by making combination use of the self- cooling by the heat capacity of the member 9 itself and the force gas cooling of the high-pressure gaseous nitrogen injected from the hole 8. The material is further subjected to the force air cooling by high-pressure air in the low temp. region where oxidation is little.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an induction hardening method and an apparatus thereof,
Specifically, the present invention relates to an induction hardening method and an apparatus therefor, which can perform induction hardening without forming an oxide film on the surface of a member to be treated.

[Conventional technology]

In induction hardening, the workpiece is heated using Joule heat from a high-frequency current induced in the workpiece such as a steel workpiece as a heat source, and after reaching the hardening temperature, the current is turned off and water etc. This is a heat treatment method in which hardening is performed by injecting a cooling medium.

Since high-frequency heating is usually performed in the atmosphere, an oxide film is generally formed on the surface of the workpiece that has been high-frequency hardened.

However, after high-frequency heating in the atmosphere,
In the induction hardening method in which quenching is performed by injecting an oxidizing coolant such as water, depending on the target part to be induction hardened, the oxide film formed on the surface of the workpiece by induction hardening may cause the product to be hardened. This causes a decrease in filli value and product strength.

Therefore, in conventional induction hardening, a method for performing induction hardening without forming an oxide film on the surface of the workpiece is to surround the workpiece together with the induction hardening coil, which can be raised and lowered at the same time, and has an opening at the bottom. A processing container having a section is placed above the induction hardening coil, an oil tank is placed below the induction hardening coil, and after the workpiece is mounted inside the induction hardening coil, the opening at the bottom of the processing container is placed. is lowered to below the oil level in the oil tank, the air in the processing container is replaced with non-oxidizing gas such as nitrogen gas, and then high-frequency heating is performed, after which the workpiece is quenched by immersing it in the oil tank. The method was usually adopted.

[Problem that the invention seeks to solve]

In view of the current state of the prior art as described above, the problem to be solved by the present invention is that although an oxide film is not formed on the surface of the member to be treated in the induction hardening without oxidation by the method as described above, (1) The working environment deteriorates because quenching oil adheres to the surface of the workpiece and oil mist is generated and scattered around.

■It becomes easier to cause a fire.

That's what it means.

Therefore, the technical problem of the present invention is to
Using a sealed processing container having a processing object mounting jig and a high-frequency heating coil connected to a high-frequency oscillator that oscillates high-density power, the processing object is attached to the processing object mounting jig inside the processing container. Then, after high-frequency heating is applied to the inside of the processing vessel in a non-oxidizing gas atmosphere, the processing chamber is heated in a high-temperature range using a combination of self-cooling using the heat capacity of the workpiece itself and forced gas cooling using non-oxidizing gas. After cooling the treated member, the treated member, which has been cooled to a low temperature range where air oxidation is less likely to occur, is hardened by forced air cooling, thereby forming an oxide film on the surface of the induction hardened treated member. It also prevents quenching oil from adhering to the surface of the workpiece (2) deterioration of the working environment as oil mist is generated and scattered around.

■, Occurrence of fire.

The aim is to prevent

c. Means for Solving the Problems] In view of the problems in the conventional techniques, the present invention provides means for solving the problems in the conventional techniques. a step of mounting the member to be processed on a mounting jig; a step of creating a non-oxidizing gas atmosphere inside the processing container after sealing the processing container; a step of high-frequency heating of the member to be processed using high-density electric power; A process of cooling the above-mentioned workpiece in a high temperature range by using a combination of self-cooling using the heat capacity of the workpiece itself and forced gas cooling using non-oxidizing gas, and cooling the workpiece in a low-temperature range where oxidation by air is less An induction hardening method characterized by comprising a step of forced air cooling;
The workpiece attached to the workpiece installation jig is heated by high frequency in a sealed processing container that includes a workpiece installation jig and a high-frequency heating coil connected to a high-frequency oscillator that oscillates high-density power. A high-frequency non-oxidizing hardening device for hardening, which uses a combination of self-cooling using the heat capacity of the workpiece itself and forced gas cooling using a non-oxidizing gas to heat the workpiece that has been high-frequency heated by an induction hardening coil. After the workpiece is cooled to a high temperature range, the workpiece is cooled to a low temperature range where air oxidation is less likely to occur. a non-oxidizing gas supply section; a high-pressure non-oxidizing gas supply section for forcibly cooling the processed member in the high temperature range after high frequency heating; Induction-free oxidation quenching characterized by having a high-pressure air supply section for air cooling, a gas discharge section for discharging non-oxidizing gas and air after use, and a charging/unloading structure for the workpiece. It consists of a device.

[Effect]

Hereinafter, the effects of the present invention will be explained.

In the present invention, the process object is mounted on the process object mounting jig disposed inside the process container, and after the process container is sealed, the inside thereof is made into a non-oxidizing gas atmosphere during high-frequency heating. This is to prevent oxidation of the member to be treated.

Furthermore, in the present invention, the object to be processed is subjected to high-frequency heating using high-density electric power in order to effectively self-cool the object to be processed using its own heat capacity in a high temperature range.

Note that self-cooling here refers to self-cooling to such an extent that a cooling rate close to that for quenching can be obtained without using any other coolant.

Furthermore, in the present invention, the cooling of the processed member in the high temperature range after high-frequency heating is performed by using both self-cooling using the heat capacity of the processed member itself and forced gas cooling using non-oxidizing gas. By increasing the power density supplied to the input coil (10 to 40 kW/cm''), the heating rate of the workpiece can be increased to <(700 to 3000°/cm).
5ec), and although self-cooling due to the heat capacity of the workpiece can be used for hardening, self-cooling alone is not sufficient for cooling speed in sharp parts such as the tips of gear teeth. Therefore, it is necessary to use forced gas cooling using a non-oxidizing gas such as nitrogen gas.

By the way, Figure 2 shows the cooling curve on the surface of the test piece after high-frequency heating using a small test piece. However, the cooling rate is faster in specimens 3 and 3 with forced gas cooling. Atmospheric pressure) Test piece C has a clearly faster cooling rate on the surface of the test piece than test piece C where the gas pressure is low (1.0 atm) during forced gas cooling.

Further, in the present invention, for carbon steel, low alloy steel, etc., which have poor hardenability, forced gas cooling using non-oxidizing gas is essential.

In addition, low-temperature ranges (for example, 500
The reason why we use forced gas cooling for the parts to be processed (below 'C') is that if we forcedly cooled the parts to room temperature with non-oxidizing gas, the amount of non-oxidizing gas used would be large and it would be uneconomical. In the low temperature range where oxidation is less likely to occur, forced air cooling is used to cool the member to be processed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

First, FIG. 1 shows the high-frequency non-oxidation hardening apparatus of this embodiment.

In FIG. 1, reference numeral 2 denotes a processing container, inside of which there is a processing object mounting jig 11, and a high-frequency thermal oscillator connected via a lead 6 to a high-frequency oscillator (not shown) placed outside the processing container 2. An input coil 7 is provided.

Further, 5 is a coolant supply pipe, which supplies non-oxidizing gas (nitrogen gas is used in this embodiment) from a non-oxidizing gas supply source N such as a nitrogen gas cylinder to gas pressure regulators 12 and 15.
, electromagnetic pulp 13 and 15, and check valves 14 and 17, low pressure nitrogen gas and high pressure nitrogen gas are supplied, and gas is also supplied from high pressure air supply source A such as factory compressed air in the same way as nitrogen gas. Pressure regulator 18. Solenoid valve 19. High pressure air is supplied via a check valve 20.

Note that the nitrogen gas used in the induction hardening apparatus of this embodiment is discharged from the processing container 2 through the gas exhaust pipe 21 by the operation of the relief valve 22 after the induction hardening is completed. There is.

Next, the operation of the high frequency non-oxidation hardening apparatus of this embodiment will be explained based on FIG. 1.

First, the processed member (a gear is used in this embodiment) 9 is mounted on the processed member mounting jig 11, and the processed member mounting jig 11 is lowered, and then, as shown in FIG. After the member 9 is installed in the induction hardening coil 7, the lid member 1 of the processing container 2 is fixed to the processing container 2 to seal the inside of the processing container 2.

Next, the electromagnetic valve 13 is set to the "open" state, and nitrogen gas whose pressure is adjusted to 0.2 to 0.5 atmospheres by the gas pressure regulator 12 is supplied to the check valve 14. The coolant is injected from the injection hole 8 provided in the induction hardening coil 7 via the coolant supply pipe 5,
The air in the processing container 2 is replaced with nitrogen gas.

Then, the processed member mounting jig 11 is rotated.

After that, the frequency is applied to the lead 6 of the induction hardening coil 7;
0-400KHz, voltage: 200-800V.

High frequency current of 11000~4000A is 0.3~1
．． Turn on electricity for 5 seconds.

Next, immediately after the high-frequency current has been energized, the electromagnetic valve 16
is in the "open" state, and the gas pressure regulator 15 is set to 1.0 to 4.
．． The nitrogen gas whose pressure has been adjusted to 0 atmospheres is passed through the check valve 14. 5 to 1 from the above-mentioned injection holes 8 via the coolant supply pipe 5.
It is sprayed for 0 seconds, and cooling is performed using a combination of self-cooling and forced gas cooling until the surface of the member to be processed 9 becomes 250° C. or less.

During this time, the above-mentioned electromagnetic valve 13 is kept in a "closed" state.

Then, after finishing cooling the member to be processed in the high temperature range, the relief valve 22 connected to the processing container 2 is operated,
The nitrogen gas used for cooling the member to be processed 9 is transferred to the processing container 2.
discharge outside.

Next, the electromagnetic valve 19 is opened, and the compressed air whose pressure has been adjusted to 2.0 to 4.0 atmospheres by the gas pressure regulator 18 is supplied to the check valve 20. The coolant is injected from the above-mentioned injection hole 8 for 15 to 30 seconds via the coolant supply pipe 5 to cool the member 9 to be treated to 50° C. and form the induction hardened layer 10 .

During this time, the above-mentioned electromagnetic valve 16 is in the "closed state".

Next, the aforementioned relief valve 22 is operated to discharge the air used for cooling the member 9 to be processed to the outside of the processing container 2 .

Finally, the rotation of the processing object mounting jig 11 is stopped, the lid member 1 is removed from the processing container 2, and the processing object 9 is taken out.

〔Effect of the invention〕

As is clear from the above, according to the high-frequency non-oxidation hardening method and the apparatus thereof according to the present invention, there is provided a workpiece mounting jig and a high-frequency heating device connected to a high-frequency oscillator that oscillates high-density power. Using a sealed processing container having a coil, the processing object is mounted on a processing object mounting jig in the processing container, and then, after high-frequency heating is performed in a non-oxidizing gas atmosphere inside the processing container, the processing object is placed in a non-oxidizing gas atmosphere. After cooling the target member in a high temperature range using a combination of self-cooling using the heat capacity of the target member itself and forced gas cooling using non-oxidizing gas, the target member that has been cooled to a low temperature range where oxidation by air is less likely to occur is forcibly cooled. Quenching by air cooling prevents the formation of an oxide film on the surface of the induction hardened workpiece, and also prevents quenching oil from adhering to the surface of the workpiece and prevents oil mist. ■ Deterioration of the working environment due to the occurrence and scattering of the product to the surrounding area.

■, Occurrence of fire.

This has the advantage of being able to prevent this.

In addition, according to the method of the present invention, the workpiece to be treated in a low temperature range where oxidation by air is less likely to be oxidized is forcedly air-cooled, so it is necessary to perform forced gas cooling with a non-oxidizing gas such as nitrogen gas to room temperature. There is also the advantage that the amount of non-oxidizing gas used can be reduced.

Furthermore, according to the method of the present invention, cooling of the workpiece after high-frequency heating is performed by a combination of self-cooling of the workpiece and forced gas cooling using non-oxidizing gas, which is superior to conventional induction hardening. Not only can the quenching distortion be significantly reduced, but also the cooling rate at around 200°C is 7~b, so it is self-tempered during induction hardening, and the tempering process after induction hardening is omitted. There are also advantages to being able to do so.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main parts of the high-frequency non-oxidation hardening device. FIG. 2 is a diagram showing a cooling curve of surface temperature after high-frequency heating using a small test piece. 1---One lid member. 2-----One processing container. 3--- Cooling pipe hole. 4--11--Lead hole. 5-----Cooling medium supply pipe. 6-・-・-Lead. 7--...Induction hardened coil. 8-1--・-Injection hole. 9-...-Processed member. 10...-Induction hardened layer. 11-1--Processed member mounting jig. 12.15.18-1-...-Gas pressure regulator. 13.16.19--Solenoid valve. 14.17.20--m-.-Check valve. 21------Gas exhaust section. 22...-111 relief valve. a---... Standing cooling test piece. b-・-Forced gas cooling combined test piece (1,0 atm) c-1-・・Forced gas cooling combined test piece (3,5 atm) 8-・
−・High pressure air supply source. 11--.-Nitrogen gas supply source.

Claims (1)

[Claims] 1. A step of mounting a processed member on a processing member mounting jig disposed in a processing container, and after sealing the processing container, creating a non-oxidizing gas atmosphere inside the processing container. A step of high-frequency heating the target member using high-density electric power; A combination of self-cooling using the heat capacity of the target member itself and forced gas cooling using a non-oxidizing gas to heat the target member in a high temperature range. and forced air cooling of the target member in a low temperature range where oxidation by air is low. 2. The processed material is mounted on the processed material mounting jig in a sealed processing container that includes a processed material mounting jig and a high-frequency heating coil connected to a high-frequency oscillator that oscillates high-density power. This is an induction non-oxidation hardening device for induction hardening a workpiece, which heats the workpiece at high frequency by an induction hardening coil, and cools the workpiece by self-cooling by the heat capacity of the workpiece itself and by force with non-oxidizing gas. After cooling the workpiece in the high temperature range by using gas cooling, a non-oxidizing gas atmosphere is created in the processing container so that the workpiece that has been cooled down to a low temperature range where oxidation by air is less likely to be cooled is forcibly air-cooled. a low-pressure non-oxidizing gas supply unit for forced gas cooling of the processed member in the high-temperature range after high-frequency heating; The method is characterized by having a high-pressure air supply section for forced air cooling of the member to be processed, a gas discharge section for discharging non-oxidizing gas and air after use, and a structure for loading and unloading the member to be processed. High frequency non-oxidation hardening equipment.