JP3345949B2 - Quenching method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quenching method for performing two-stage quenching with a high-temperature and low-temperature quenching oil, and an apparatus therefor.

[0002]

2. Description of the Related Art When quenching steel gears or the like, 850 is required.
When a work heated to 150 ° C. is quenched with a 150 ° C. quenching oil, the temperature difference between the work surface and the inside is large, and martensitic transformation (MS point: 200 ° C.) starts in this state, causing internal strain in the work. As a result, the work is deformed, and the deformation amount and its variation are increased.

As a countermeasure, a work heated to 850 ° C. is first heated to an oil temperature slightly higher than the martensite transformation temperature.
A method is used in which the first-stage quenching is performed with a quenching oil at 0 ° C., and the surface and the inside of the work are substantially uniform, and then the second-stage quenching is performed with a quenching oil at an oil temperature of 150 ° C. FIG. 3 shows an apparatus for performing the two-stage quenching. 85 in atmosphere furnace 1
The work W heated to 0 ° C. is conveyed to the oil tank chamber 2 by opening the intermediate door 3A. The oil tank chamber 2 is provided with a quenching oil tank 11 having an oil temperature of 220 ° C. and a quenching oil tank 12 having an oil temperature of 150 ° C. First, the work W is quenched in the quenching oil tank 11 having an oil temperature of 220 ° C., and then as shown by an arrow. Then, the work W is transferred to the quenching oil tank 12 having an oil temperature of 150 ° C., and the second quenching is performed. The quenched work W is transferred from the oil tank chamber door 3B to the atmosphere and air-cooled.

Japanese Utility Model Application Laid-Open No. 61-18767 discloses an immersion quenching apparatus in which a quench hood is disposed around a work in order to make the flow of the quenching liquid uniform when the quenching liquid is circulated in the quenching tank. Has been described.

[0005]

The quenching equipment for two-stage quenching shown in FIG. 3 requires two tanks, a high-temperature oil tank 11 and a low-temperature oil tank 12, and therefore requires two types of quenching oil. The space of the chamber 2 and the amount of quenching oil are required for two tanks, and the work W needs to be transferred from the high-temperature oil tank 11 to the low-temperature oil tank 12.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and to provide a method capable of sequentially performing two-stage quenching with high and low temperature quenching oil while using a single quenching oil tank, and an apparatus for implementing the method. It is the purpose.

[0007]

According to the present invention, a heated work is immersed in a quench oil in a hood in a quench tank having a hood surrounding the work in an oil tank having a quenching oil circulation system. The temperature of the quenching oil around the work in the hood is raised to near the transformation point temperature by the heat of the work, and the first-stage quenching is performed with the circulation of the quench oil stopped.
Ru hardening method der to perform two-stage quench for quenching the quenching oil is circulated in the following transformation temperature when the surface and internal temperature of the workpiece is near uniform. Equipment used for this method
Is installed in the oil tank where quenching oil is circulated by the pump.
The flow of quenching oil in the oil tank is surrounded by
And quenching inside the hood
A temperature sensor that detects the temperature of oil is provided.
Is the transformation point temperature of the quenching oil around the work in the hood
When the pump is detected to have risen to near
Is configured to stop . Also, start / stop pump
Timer to control the heated work in the hood
Immersion in quenching oil and the temperature of the quenching oil is near the transformation point temperature
When the preset time elapses,
Pump drive or quenching oil circulation stopped
Perform the first quenching in the condition
When the preset time elapses when the degree approaches uniform
Control the pump with a timer to drive the pump
It can be configured as follows.

[0008]

[Function] The quenching oil in the hood has a small capacity, so if the circulation is stopped, the oil temperature rises to near the transformation temperature due to the heat of the work, and when the circulation starts, it is mixed with a large amount of low-temperature quenching oil. The quenching oil temperature in the hood decreases. As a result, quenching can be performed sequentially with quenching oil at two high and low temperatures in one oil tank, and the hood partitions the flow of quenching oil in the oil tank into upstream and downstream, so that the oil temperature in the hood is efficiently adjusted to two high and low temperatures. Switch well. Hardening in the hood
The equipment provided with a temperature sensor for detecting the temperature of the oil, temperature
The temperature sensor measures the temperature of the hardened oil around the workpiece in the hood.
Is detected when the temperature rises to near the transformation point temperature.
Stop the operation of the oil circulation pump. Also quenching
A timer is provided to control the operation and stop of the oil circulation pump
Timer has passed the preset time
At times, the quenching oil circulation pump is controlled.

[0009]

1 is an explanatory view of a quenching method according to the present invention, and FIG. 2 is a sectional view of a quenching facility. In FIG. 2, the atmosphere furnace 1
Is a heating furnace for the work W, provided with an oil tank chamber 2 through an intermediate door 3A, and a quenching oil tank 4 having an oil temperature of 150 ° C.
A hood 5 surrounding the suspended work W and partitioning the inside of the oil tank 4 is installed in the oil tank 4, and a spout of a quenching oil circulation pump 6 is provided at the bottom of the hood 5. It is arranged. The hood 5 partitions the inside of the oil tank 4 into a predetermined small volume and regulates the flow of quenching oil.
The details will be described later. The oil tank chamber 2 is provided with an oil tank chamber door 3B for transferring the work W after the quenching process to the atmosphere.

In the quenching of steel gears, 85
The work W heated to 0 ° C. is conveyed to the oil tank chamber 2 by opening the intermediate door 3A, suspended in the hood 5 of the oil tank 4 by a not-shown conveyer, and immersed in quenching oil. This time is defined as t1 in FIG. The quenching oil at an oil temperature of 150 ° C. in the hood 5 (shown by a dashed-dotted line OT in FIG. 1) increases in temperature as shown by a broken line Ot in FIG.
At 2:00, the oil temperature becomes high near the martensitic transformation temperature (MS). On the other hand, the temperature of the work W rapidly decreases as shown by the solid line Wt and approaches 200 ° C. The time T1 from the time t1 to the time t2 when the work W is put into the oil tank 4 is determined by the pump 6
Is driven to circulate the quenching oil in the hood 5, it takes a short time. However, when the heat capacity of the work is small, the circulation of the quenching oil may be stopped.

From time t2 when the temperature of the quenching oil in the hood 5 reaches a predetermined temperature, the circulation of the quenching oil is stopped. The work W is first quenched with a high oil temperature quenching oil in the hood 5, and at a time t3 when a predetermined time T2 elapses and the surface and the inside of the work reach a substantially uniform temperature, the high temperature inside the hood 5 becomes high. The quenching oil and the low-temperature quenching oil in the oil tank 4 are circulated. As a result, the work W is rapidly cooled to a temperature lower than the MS point by a low-temperature quenching oil to cause a martensitic transformation, and the transformation is completed after a lapse of a predetermined time T4. The workpiece W that has been subjected to the second-stage quenching process is transferred from the oil chamber door 3B to the atmosphere, and is cooled by air after t4.

Therefore, the first-stage quenching is performed at an oil temperature near the MS point for T3 hours in one oil tank containing quenching oil at 150 ° C., so that the temperature of the surface and the inside of the work W become uniform. After that, by circulating the quenching oil in the oil tank,
Since the work W is rapidly cooled to a temperature equal to or lower than the MS point and is quenched in the second stage for T4, deformation of the work W due to quenching is suppressed.

Next, an embodiment of a specific quenching facility is shown in FIG.
Will be described. FIG. 4A shows a cross section of an oil tank and a circulation system of quenching oil, and FIG. 4B is a plan view showing a circulation system of quenching oil. The inside of the oil tank 4 is divided into small volumes by a hood 5 resembling the outer shape of the work W, and a temperature sensor 7 such as a thermocouple is installed in the hood 5. An outlet 9 of an oil feed pipe 8 from a pump 6 is provided downward in the hood 5. Food 5
The temperature of the quenching oil at an oil temperature of 150 ° C. rises when the work W is charged, due to the amount of heat it has. The temperature sensor 7 detects that the oil temperature is near the martensitic transformation temperature, and if the quenching oil has been circulated up to that time, the pump 6 is stopped or the valve is closed to stop the circulation of the quenching oil. After performing the first-stage quenching for a predetermined time in this state, the quenching oil is recirculated.

The quenching oil in the hood 5 is jetted from the jet port 9 toward the bottom of the oil tank 4 and rebounds at the bottom to rise in the hood 5 as a laminar flow at a constant speed as shown by a broken line in the figure. Then, the work W is rapidly and uniformly cooled to perform second-stage quenching. The quenched oil overflowing from the upper end of the oil tank 4 is mixed with a large amount of quenched oil in the oil tank 4 to lower the temperature, and is recirculated by the pump 6.

In FIG. 1, the time T1 from the time t1 to the time t2 when the work W is charged into the oil tank 4 is determined by repeating the quenching test to determine an optimum time (for example, 10 seconds) and stopping the circulation of the quenching oil by a timer. For the first-stage quenching time T3, if the optimum time (eg, 92 seconds) is determined by repeating the quenching test in the same manner, the second-stage quenching start time t3 is controlled by a timer and the recirculation of the quenching oil is started. Can be done.

FIG. 5 is a sectional view showing another embodiment of the oil tank. A hood 5 having a receiving tank 10 mounted thereon is installed in the oil tank 4, and quenching oil that has cooled the work W is temporarily transferred to the receiving tank 10 in the oil tank 4.
When the pump 6 is driven to circulate the quenching oil, the inside of the oil tank 4 is partitioned upstream and downstream of the hood 5 and the receiving tank 9 is circulated. There is no ripple of the quenching oil on the surface, and the quenching oil flows in the hood 5 as a whole in a laminar flow.

FIGS. 6 and 7 show still another embodiment of the oil tank. FIG. 6 is a plan view of the oil tank and the circulation system, and FIG. 7 is a sectional view. In the oil tank 4, a cylindrical hood 15 having a partition plate 14 attached to the outer periphery is installed, and quenching oil from the pump 6 is installed at four locations around the oil tank 4 from a pipe 20 at a lower portion of the partition plate 14. 15, the quenching oil that has cooled the work W is temporarily put into the oil tank 4 above the partition plate 14, and circulated to the pump 6 by the pipe 21 from here, and the work W such as a gear is quenched. It is preferable that the quenching oil sometimes flows in the hood 15 as a laminar flow as a whole.

Five steel helical gears of material F16 are stacked to form a work, and quenching oil at an oil temperature of 150 ° C. is circulated in accordance with the method of the present invention. Then, the oil temperature in the hood rose to 197 ° C. in about 20 seconds. After that, while the circulation of the quenching oil is stopped, the temperature is maintained for 1 minute, the first quenching is performed, and then the quenching oil is recirculated. I returned.

The amount of deformation of the torsion angle of the helical gear after quenching was determined by experiments (15 tests) according to the method of the present invention.
Right tooth flank 15μm or less (average 7μm), left tooth flank 20μ
m (average: 6 μm) and 1
In the case hardened product (20 tests), the right tooth surface was 2
Both the variation and the average deformation were reduced as compared to 5 μm or less (average 11 μm) and the left tooth surface was 20 μm or less (average 10 μm).

[0020]

According to the present invention, it is possible to sequentially perform two-stage quenching with high and low temperature quenching oils while using one quenching oil tank, so that quenching can be performed efficiently with little capital investment, and the quality of the processed products can be reduced. The amount of deformation and its variation can be reduced.

[Brief description of the drawings]

FIG. 1 is a heat treatment diagram of the present invention.

FIG. 2 is an explanatory view of a quenching facility of the present invention.

FIG. 3 is an explanatory view of a conventional quenching facility.

FIG. 4 is an explanatory view of an embodiment of a quenching oil tank.

FIG. 5 is a sectional view of another embodiment of the quenching oil tank.

FIG. 6 is a plan view of a circulation system of a quenching oil tank.

FIG. 7 is a sectional view of another embodiment of the quenching oil tank.

[Description of Signs] 1 Atmosphere furnace 2 Oil tank chamber 3A, 3B Door
4 Oil tank 5 Hood 6 Pump 7 Temperature sensor
W Work Wt Work Temperature OT Low Oil Temperature Ot High Oil Temperature MS Martensite Transformation Temperature

Continuation of the front page (56) References JP-A-4-350115 (JP, A) JP-A-6-240347 (JP, A) JP-A-6-220529 (JP, A) JP-A-5-222445 (JP) , A) JP 4913692 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 1/18 C21D 1/63

Claims (3)

(57) [Claims] 1. A heated work is immersed in a quenching oil in a hood in a quenching tank in which a hood surrounding the work is installed in an oil tank having a circulating system of quenching oil, and the heat of the work is used to immerse the heated work in the hood. The temperature of the quenching oil around the workpiece is raised to near the transformation point temperature, and the first stage quenching is performed with the circulation of the quenching oil stopped. Quenching is performed in a second step of quenching to a temperature below the transformation point by circulating the quenching. To 2. A oil tank in performing the circulation of quenching oil by a pump, as well as installing a hood defining around the workpiece the flow of quenching oil surrounds oil vessel to the upstream and downstream, the Fu
Temperature sensor to detect the temperature of the quenching oil in the
The temperature sensor hardens around the work in the hood
Detected that the oil temperature has risen to near the transformation point temperature
Quenching equipment, characterized in that the drive of the pump is sometimes stopped . 3. An oil tank in which quenching oil is circulated by a pump.
Around the work and the flow of quenching oil in the oil tank.
In addition to installing hoods that separate upstream and downstream,
A timer is provided to control the drive
The workpiece is immersed in quenching oil in the hood and the temperature of the quenching oil is
Predetermined predetermined time when the temperature rises to near the transformation point temperature
Stop the drive of the pump when lapsed, or harden
With the circulation of oil stopped, the first stage quenching
A preset point where the surface and internal temperatures of the
Before driving the pump when the fixed time elapses
The pump is controlled by the timer.
Quenching equipment.