Jig for vacuum heat treatment and method of vacuum heat treatment
A negative pressure and fixture technology, which is applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of adhesion of processed materials, reduce defective products of dimensional accuracy, etc., and achieve the effect of preventing adhesion and preventing both adhesion
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Embodiment 1
[0037] A jig for negative pressure heat treatment and a negative pressure heat treatment method according to an embodiment of the present invention will be described with reference to the accompanying drawings.
[0038] In this example, a method of heat-treating a ring gear made of carbon steel as the material to be processed 8 in a negative-pressure atmosphere lower than atmospheric pressure is taken as an example, and a jig for negative-pressure heat treatment used in this process is also used. 1 (hereinafter appropriately referred to as "jig 1").
[0039] Such as figure 2 As shown, the processed material 8 of this example is a ring gear having a cylindrical ring portion 80 and spline teeth 81 formed on the inner peripheral surface of the ring portion 80 . The ring gear is a component incorporated into an automatic transmission (A / T) for automobiles, and requires very high dimensional accuracy such as roundness.
[0040] Such as figure 1 As shown, the jig 1 supporting th...
Embodiment 2
[0054] In this example, instead of clamp 1 in embodiment 1, such as Figure 4 As shown, a negative pressure heat treatment jig 3 (hereinafter appropriately referred to as "jig 3") is used. The processed material 8 and the negative pressure carburizing treatment are the same as those in Example 1.
[0055] As shown in the figure, the jig 3 of this example is configured to be supported in a state in which the axis of the material 8 to be processed is placed in the horizontal direction and suspended by a hanger that is a part of the jig 3 . As shown in the figure, the bottom plate portion 31 of the jig 3 has a skeleton structure provided with a plurality of cavities 320, and allows the flow of ambient air. A plurality of pillar portions 32 are erected on the bottom plate portion 31 , and the horizontal frame 34 and the hanger 35 are supported by the pillar portions 32 .
[0056] Note that in this example, the same coating 2 as in Example 1 is formed on the surface of the above-...
Embodiment 3
[0059] In this example, in order to clarify the effect of the negative pressure carburizing treatment using the jig 1 described in Example 1, a test was performed to measure and evaluate the dimensional accuracy of the treated material 8 after treatment.
[0060] Specifically, an existing fixture of the same shape that does not form a film 2 is prepared outside the above-mentioned fixture 1, and the same negative pressure carburizing treatment as in Example 1 is carried out by charging twice, and a total of 336 processed materials 8 Carry out heat treatment.
[0061] Evaluation of dimensional accuracy is carried out by measurement of so-called "BBD ellipse". Specifically, as figure 2 As shown, steel balls 88 of a predetermined diameter are placed in contact with the valleys of the spline teeth 81, and "BBD" which is a dimension obtained by measuring the inner diameters of opposing hard balls 88 is obtained. The above-mentioned measurement is performed on the entire circumfe...
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