JPH0596048U - Heat treatment jig - Google Patents

Abstract

(57) [Summary] [Purpose] When quenching a ring-shaped product such as a bearing ring, prevent distortion that occurs during heating. [Structure] The heat treatment jig 1 is composed of a circular ceramic flat plate 2 serving as a main body and a plurality of shims 3 serving as seats. The shim 3 may be made of ceramics or metal. In use, for example, the ceramic flat plate 2 is placed on the fixture basket 4, the heat-treated product W is placed via the shim 3, and heating is performed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat treatment jig used for heat treatment such as quenching of steel, particularly for quenching of bearing rings in thin bearings.

[0002]

[Problems to be solved by conventional techniques and devices]

 Quenching of steel is performed by cooling a heat-treated product that has been heated to a quenching heating temperature (about 750 ° C to 1300 ° C depending on the type of steel) with a liquid such as water or oil, or a gas such as air or nitrogen. To do. Quenching strain generated at this time is a combination of strain generated during heating, transformation and thermal stress strain generated during cooling, and strain due to stress remaining before heating.

Of these, the strain that occurs during heating occurs as follows. That is, when steel is heated to an austenite state, its hot deformation resistance is significantly reduced. Therefore, in the conventional general heating method, deformation and warpage occur due to the weight of the heat-treated product.

For example, FIG. 5 shows a charging condition of a general heat-treated product when a batch-type heating furnace is used. The heat-treated product 51 is placed directly on the fixture basket 52, and the baskets 52 are stacked on the tray 53 in multiple stages and placed in the furnace.

Since the heat-treated product 51 is placed directly on the basket 52 as described above, the heat-treated product 51 is deformed or warped during heating in accordance with the flatness of the bottom surface of the basket 52. In particular, when the heat-treated product 51 is a bearing ring of a thin bearing whose thickness is thinner than the inner diameter or a ring-shaped product having a small width dimension, such deformation and warpage are likely to occur. In a rotary hearth furnace or a roller hearth furnace, the heat-treated product is placed directly on the hearth, but in this case, the heat-treated product is deformed or warped due to the flatness of the hearth.

An object of the present invention is to provide a heat treatment jig capable of preventing distortion generated during heating.

[0007]

[Means for Solving the Problems]

 The heat treatment jig of the present invention has a ceramic main body and a seat portion provided on the main body for locally supporting the heat treated product.

[0008]

[Action]

 The heat-treated product is placed on the seat of this heat-treatment jig and placed on the hearth or basket in the heating furnace for heating. Since the heat treatment jig is formed as a stand on which heat treated products are individually placed, it can be easily formed to have a high degree of flatness, and since the main body is made of ceramics, it has a large deformation resistance at high temperatures. .. Therefore, the heat-treated product is always supported by the surface having high flatness, which prevents the heat-treated product from being deformed or warped during heating. Further, since the seat portion of the heat treatment jig locally supports the heat treated product, it is possible to sufficiently circulate the cooling gas to the lower surface of the heat treated product during quenching and cooling.

[0009]

【Example】

 An embodiment of this invention will be described with reference to FIG. The heat treatment jig 1 is composed of a circular ceramic flat plate 2 that serves as a main body and a plurality of shims 3 that serves as a seat. The shim 3 may be made of ceramics or metal. Explaining an example of dimensions, the ceramic flat plate 2 is formed to have a thickness of 5 to 10 mm, and a ventilation opening 2a is formed in the center. The shim 3 has a ring shape and a width dimension of 5 to 15 mm.

In use, for example, the ceramic flat plate 2 is placed on the fixture basket 4, the heat-treated product W is placed via the shim 3, and heating is performed. The heat-treated product W is a ring-shaped product such as a bearing ring. When used in a rotary hearth furnace, etc., the ceramic flat plate 2 is placed on the hearth.

Since the ceramic flat plate 2 is provided individually for each heat-treated product W, it can be easily formed to have a high flatness and has a large deformation resistance at high temperatures. Therefore, the heat-treated product W is always supported by the surface having a high degree of flatness, which prevents the heat-treated product W from being deformed or warped during heating. Further, since the heat-treated product W is locally supported by the interposition of the shims 3, the cooling gas is sufficiently circulated to the lower surface of the heat-treated product W during quenching cooling, and uniform cooling can be performed.

Therefore, this heat treatment jig 1 can be effectively used for quenching the bearing ring of the bearing, particularly for a thin bearing having a thinner wall thickness than the inner diameter or a bearing bearing ring having a small width dimension. In terms of the dimensional relationship, regarding the ring-shaped heat-treated product W in FIG. 2, the relationship between the outer diameter A and the inner diameter B and the relationship between the outer diameter A and the width dimension C are: B / A ≧ 0.9 C It is particularly effective when /A≦0.15, and improves the warpage and deformation of the heat-treated product W after quenching.

According to experiments, the heat-treated product W shown in FIG. 2 was heat-treated under the following conditions, and the results shown in the following table were obtained. Table unit mm

The heat-treated product W has an outer diameter A of 200 mm, an inner diameter B of 180 mm, a width C of 25 mm, and is a ring-shaped product of high speed steel M50 (American Iron and Steel Institute AISI standard). The heat-treated product W was heated to 1090 ° C. by heating in a vacuum furnace and then cooled and quenched with nitrogen (N ₂ ) gas. From the above table, it can be seen that when the heat treatment jig 1 of the example is used, the amount of widthwise warp is significantly improved and the amount of elliptic deformation is also approximately halved as compared with the conventional method.

As described above, since the strain is less generated during the heat treatment, in the case of the bearing ring, the grinding allowance in the post process can be significantly reduced. Further, when the heat-treated product W is a flanged bearing ring, the precision of the finished product can be satisfied without processing after the heat treatment.

FIG. 3 shows another embodiment. In the heat treatment jig 1'of this example, a plate-shaped shim 3'was used and was arranged at three locations in the circumferential direction. Other configurations are the same as those in the above embodiment. FIG. 4 shows still another embodiment. In this example, the entire heat treatment jig 4 is integrally molded of ceramics, and includes a main body 5 made of a flat disk and a rib-shaped seat 6 formed radially on the main body 5. Consists of. A ventilation opening 5a is formed in the center of the main body 5. Even when the heat treatment jigs 1 ', 4 of the embodiment shown in FIGS. 3 and 4 are used, distortion can be prevented during the heat treatment and the cooling gas can be satisfactorily ventilated as in the case of the above embodiment. Further, in the case of the example in FIG. 4, since the seat portion 6 is radial, the same heat treatment jig 4 can be used for heat treated products W having various outer diameters.

[0017]

[Effect of the device]

 Since the heat treatment jig of the present invention comprises the main body made of ceramics and the seat for supporting the heat-treated product, it can be easily formed into a highly flat one and has a large deformation resistance at high temperature. Therefore, the heat-treated product is always supported by the surface having high flatness, and the strain generated during heating is prevented. Further, since the seat portion locally supports the heat-treated product, it is possible to sufficiently circulate the cooling gas even on the lower surface of the heat-treated product during quenching cooling or the like, and perform uniform cooling.

[Brief description of drawings]

FIG. 1 is a side view and a plan view showing the relationship between a heat treatment jig and a heat treatment product according to an embodiment of the present invention.

FIG. 2 is a side view of an example of a heat-treated product using the heat treatment jig.

FIG. 3 is a plan view of another embodiment of the present invention.

FIG. 4 is a perspective view of another embodiment of the present invention.

FIG. 5 is a side view of a conventional example.

[Explanation of symbols]

1, 1 '... heat treatment jig, 2 ... ceramic flat plate (main body portion), 3, 3' ... shim (seat portion), 4 ... heat treatment jig, 5 ...
Body part, 6 ... Seat part, W ... Heat treated product

Claims (1)

[Scope of utility model registration request] 1. A heat treatment jig having a main body made of ceramics, and a seat provided on the main body to locally support a heat-treated product.