JPH06279838A - Quenching method and equipment therefor - Google Patents

Abstract

PURPOSE:To enable two-step quenchings employing one quenching oil vessel. CONSTITUTION:A hood surrounding a work is arranged in the oil vessel and the heated work is dipped into the quenching oil in the hood and the temp. of the quenching oil in the hood is raised to near the temp. of the transformation point with the heat of the work. In the condition of stopping the circulation of the quenching oil, a first step of quenching is executed, and when the temps. of the surface and the inner part of the work approach to uniformity, the quenching oil is circulated and a second step of quenching for rapidly cooling it to the temp. of the transformation point or lower is performed. As the capacity of quenching oil in the hood is small in the condition of stopping the circulation, the oil temp. is raised to near the transformation temp. by calorific quantity held by the work. At the time of starting the circulation, the quenching oil temp. in the hood is lowered by mixing with a large quantity of low temp. quenching oil. By this method, the quenchings in the quenching oil having high and low temps. are sequentially executed in one oil vessel.

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 quenching oils at high and low temperatures, and equipment therefor.

[0002]

2. Description of the Related Art When quenching steel gears, etc., 850
When a work heated to ℃ is quenched with quenching oil at 150 ℃, the temperature difference between the work surface and the inside is large, and martensite transformation (MS point: 200 ℃) starts in this state, causing internal strain in the work. As a result, the work is deformed, and the amount of deformation and its variation increase.

As a countermeasure, a work heated to 850 ° C. is first heated to an oil temperature 22 which is slightly higher than the martensitic transformation temperature.
A method is used in which first-step quenching is performed with 0 ° C. quenching oil, and after the surface and inside of the work become substantially uniform, second-step quenching is performed with quenching oil with an oil temperature of 150 ° C. An apparatus for carrying out this two-step quenching is shown in FIG. 85 in atmosphere furnace 1
The work W heated to 0 ° C. is transferred 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 with an oil temperature of 220 ° C. and a quenching oil tank 12 with an oil temperature of 150 ° C. First, the work W is quenched in the quenching oil tank 11 with an oil temperature of 220 ° C., and then as shown by the arrow. Then, the work W is transferred to the quenching oil tank 12 having an oil temperature of 150 ° C. and second-stage quenching is performed, and the work W after the quenching treatment is transferred from the oil tank chamber door 3B to the atmosphere and air-cooled.

Japanese Utility Model Laid-Open No. 61-187367 discloses an immersion quenching facility in which a quench hood is arranged around a work in order to make the flow of the quenching solution uniform when circulating the quenching solution in a quenching tank. Have 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.

The present invention solves the above-mentioned problems and provides a method capable of sequentially performing two-stage quenching with quenching oil at high and low temperatures while using one quenching oil tank, and equipment for carrying out the method. It is intended.

[0007]

According to the present invention, a heated work is immersed in the quenching oil in the hood in a quenching tank having a hood surrounding the work in an oil tank having a quenching oil circulation system. The heat of the work raises the temperature of the quenching oil around the work in the hood to near the transformation point temperature, and the first quenching is performed with the circulation of quenching oil stopped.
This is a quenching method that performs second-stage quenching in which quenching oil is circulated to rapidly cool below the transformation point temperature when the temperature of the surface and inside of the workpiece approaches evenly. A hood is installed to separate the flow of quenching oil in the oil tank into upstream and downstream.

[0008]

[Function] Since the quenching oil in the hood has a small capacity, when the circulation is stopped, the oil temperature rises to around the transformation temperature due to the heat quantity of the work, and when circulation begins, it is mixed with a large amount of low-temperature quenching oil. Quenching oil temperature in the hood drops. As a result, quenching can be performed sequentially with quenching oil of two high and low temperatures in one oil tank, and the hood divides the flow of quenching oil in the oil tank into upstream and downstream, so the oil temperature in the hood can be efficiently adjusted to two temperatures, high and low. Switch well.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a quenching method of the present invention, and FIG. 2 is a sectional view of quenching equipment. In FIG. 2, the atmosphere furnace 1
Is a heating furnace for the work W, and an oil tank chamber 2 is provided through an intermediate door 3A. In the oil tank chamber 2, a quenching oil tank 4 having an oil temperature of 150 ° C.
A hood 5 that surrounds the suspended work W and partitions the inside of the oil tub 4 is installed in the oil tub 4, and the jet port of the quenching oil circulation pump 6 is provided at the bottom of the hood 5. It is provided. The hood 5 divides 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 treatment into the atmosphere.

In quenching steel gears, 85 in the atmosphere furnace 1
The work W heated to 0 ° C. is transferred to the oil tank chamber 2 by opening the intermediate door 3A, suspended in the hood 5 of the oil tank 4 by a carrier (not shown), and immersed in quenching oil. This time is designated as t1 in FIG. The temperature of the quenching oil in the hood 5 having an oil temperature of 150 ° C. (shown by the one-dot chain line OT in FIG. 1) rises due to the amount of heat of the work W as shown by the broken line Ot in FIG.
At 2 o'clock, 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 when the work W is put into the oil tank 4 to the time t2 is short when the quenching oil in the hood 5 is circulated by driving the pump 6. However, when the heat capacity of the work is small, the circulation of the quenching oil may be stopped.

The circulation of the quenching oil is stopped from t2 when the quenching oil temperature in the hood 5 reaches a predetermined temperature. The work W is first-quenched with high-oil-temperature quenching oil in the hood 5, and at a time t3 when the surface of the work and the inside of the hood 5 become substantially uniform after a predetermined time T2, the high temperature inside the hood 5 is reached. 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 below the MS point by quenching oil at a low temperature, martensitic transformation occurs, and the transformation is completed after a lapse of a predetermined time T4. The work W that has undergone the second-stage quenching process is moved from the oil tank chamber door 3B to the atmosphere, and is air-cooled after t4 at this time.

Therefore, in the oil tank containing the quenching oil of 150 ° C., the first quenching is performed at the oil temperature near the MS point for T3 hours, so that the surface of the work W and the internal temperature become uniform. After that, by circulating the quenching oil in the oil tank,
Since the work W is rapidly cooled to a temperature below the MS point and is second-stage quenched for T4 time, the deformation of the work W accompanying quenching is suppressed.

Next, a concrete example of quenching equipment is shown in FIG.
Will be described. FIG. 4A shows the cross section of the oil tank and the quench oil circulation system, and FIG. 4B is a plan view showing the quench oil circulation system. The inside of the oil tank 4 is divided into a small volume 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. The jet port 9 of the oil feed pipe 8 from the pump 6 is provided downward in the hood 5. Hood 5
The temperature of the quenching oil having an oil temperature of 150 ° C. rises due to the amount of heat of the work W when the work W is charged. When the temperature sensor 7 detects that the oil temperature is near the martensitic transformation temperature and the quenching oil has been circulated until then, the pump 6 is stopped or the valve is closed to stop the quenching oil circulation. In this state, after quenching the first stage for a predetermined time, quenching oil is recirculated.

The quenching oil in the hood 5 is ejected from the ejection port 9 toward the bottom of the oil tank 4, is bounced off at the bottom and becomes a laminar flow at a constant speed as shown by the broken line in the figure, and rises in the hood 5. Then, the work W is uniformly rapidly cooled and the second stage quenching is performed. The quenching oil overflowing from the upper end of the oil tank 4 is mixed with a large amount of quenching oil in the oil tank 4 to lower the temperature, and is recirculated by the pump 6.

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

FIG. 5 shows another embodiment of the oil tank in cross section. The hood 5 having the receiving tank 10 attached thereto is installed in the oil tank 4, and the quenching oil that has cooled the work W is once stored in the receiving tank 10
The pipe 6 is circulated to the pump 6 from here, and when the pump 6 is driven to circulate the quenching oil, the oil tank 4 is divided into an upstream side and a downstream side of the hood 5 and a receiving tank 9 There is no waviness of the quenching oil on the surface, and the quenching oil flows as a whole in a laminar flow in the hood 5.

6 and 7 show 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. A cylindrical hood 15 having a partition plate 14 attached to the outer circumference is installed in the oil tank 4, and quenching oil from the pump 6 is installed from four pipes 20 installed around the oil tank 4 to a hood at a lower portion of the partition plate 14. The quenching oil, which is made to flow into 15 and cools the work W, is once put in the oil tank 4 above the partition plate 14 and is circulated to the pump 6 by the pipe 21 from here, and the work W like a gear is quenched. At this time, the quenching oil becomes a laminar flow as a whole and flows in the hood 15, which is preferable.

Five pieces of steel helical gears of material F16 are stacked to form a work, and quenching oil having an oil temperature of 150 ° C. is circulated according to the method of the present invention. When the circulation of No. 1 was stopped, the oil temperature in the hood increased to 197 ° C in about 20 seconds. After that, the temperature of the quenching oil in the hood rapidly increases to around 150 ° C when the quenching oil is recirculated after the quenching oil is circulated for 1 minute while maintaining the temperature for 1 minute while the circulation of the quenching oil is stopped. I'm back.

The amount of deformation of the torsion angle of the helical gear after quenching was determined by an experiment (15 tests) by the method of the present invention.
Right flank is less than 15μm (7μm on average), left flank is 20μ
m or less (average 6 μm), 1 at the conventional 150 ° C oil temperature
In the case-hardened product (20 tests), the right flank is 2
Both the variation and the average amount of deformation were reduced as compared with 5 μm or less (average 11 μm) and 20 μm or less on the left tooth surface (average 10 μm).

[0020]

EFFECTS OF THE INVENTION The present invention makes it possible to perform two-step quenching sequentially with high-low temperature quenching oil while using one quenching oil tank, so that quenching can be performed efficiently with a small equipment investment, The amount of deformation and its variation can be reduced.

[Brief description of drawings]

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

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

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

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 the circulation system of the quenching oil tank.

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

[Explanation of symbols] 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

Claims (2)

[Claims] 1. A heated work is immersed in the quenching oil in the hood in a quenching tank in which a hood surrounding the work is installed in an oil tank having a quenching oil circulation system, and the heat of the work causes the inside of the hood to move. The temperature of the quenching oil around the work is raised to near the transformation point temperature, the first quenching is performed with the quenching oil circulation stopped, and the quenching oil is applied when the temperature on the surface of the work and the internal temperature approach A quenching method characterized by performing second-stage quenching in which the steel is circulated to quench the temperature below the transformation point temperature. 2. A quenching facility characterized in that a hood is provided inside the oil tank having a quenching oil circulation system, which surrounds the work and divides the quenching oil flow in the oil tank into an upstream and a downstream.