JPH0669692U - Heat treatment furnace - Google Patents

Abstract

(57) [Summary] [Purpose] To make the degreasing process uniform among processed products. [Structure] The fan 3 is configured to stir the carrier gas X in the container 1 together with the binder vapor Y. At this time, the periphery of the fan 3 is surrounded by the box 4 to limit the stirring area, and the exhaust system passage 5 is connected to the box 4 to keep the inside of the box 4 at a relatively lower pressure than the inside of the container 1. This prevents the binder vapor Y from leaking out of the box 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat treatment furnace preferably used in the field of powder metallurgy and the like.

[0002]

[Prior art]

 Injection molding manufacturing technology is one of the powder metallurgy technologies. This injection molding technology uses a metal powder mixed with an organic binder and molded into the required shape (called a green body), through a binder removal process in the degreasing process and a high-temperature firing process in the sintering process. It is a technology for making metal products. This technology is intended for mass production, and the problem is simultaneous processing of many processed materials. Therefore, special emphasis has been placed on uniform treatment in the degreasing process so that the quality of final products can be made uniform among products.

[0003]

[Problems to be solved by the device]

 However, the conventional degreasing furnace has a problem that the homogenization of the treatment in the degreasing process is insufficient. Specifically, in the conventional degreasing furnace, while introducing the carrier gas into the furnace, the carrier gas is discharged to the outside of the furnace by the exhaust means to generate a steady carrier gas flow in the furnace. The carrier gas is used to discharge the binder vapor generated in the furnace to the outside of the furnace so that the processing atmosphere is always kept in a low binder concentration state. However, when the treatment is carried out in the furnace under reduced pressure near atmospheric pressure, the carrier gas flow in the furnace becomes extremely slow. When heating is performed under such a condition, convection occurs in the furnace, the temperature of the rising space of the furnace becomes relatively higher than that of the lower space, and the binders that evaporate one after another from the processed material are different due to the difference in specific gravity. Settles in the lower space. Therefore, such temperature unevenness and binder concentration unevenness cause different degreasing speeds in the upper space and the lower space of the furnace, which causes non-uniform degreasing among the processed products and eventually non-uniformity among the processed products.

The present invention has been made in view of the above-mentioned points of view, and an object thereof is to provide a heat treatment furnace having a configuration that is actually effective in uniforming degreasing.

[0005]

[Means for Solving the Problems]

 The present invention adopts the following configuration in order to achieve such an object.

That is, the heat treatment furnace according to the present invention is provided with a container for containing a processed material, an introduction system passage for introducing a carrier gas into the container, and a carrier gas introduced through the introduction system passage. The container is equipped with a stirring fan, an air-permeable box disposed at a position surrounding the fan, and an exhaust system passage opening into the box. The carrier gas introduced into the box is caused to flow into the box by the differential pressure flow, and the gas generated in the box is agitated by a fan in the box, and part of the carrier gas is discharged to the outside of the container through the exhaust system passage. It is characterized in that it is configured as follows.

[0007]

[Action]

 With such a structure, the carrier gas introduced into the box is stirred in the box together with the generated gas such as a binder, and a part of the carrier gas is gradually discharged to the outside of the container through the exhaust system passage. Therefore, the temperature and the generated gas concentration in the box can be kept uniform. In addition, since the stirring area is limited by the box and the carrier gas is made to flow differentially from the inside of the container to the inside of the box, even if the inside of the box is agitated by a fan, the harmful gas is not generated outside the box. There is no problem such as leakage and contamination of the container.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

This heat treatment furnace is used, for example, for degreasing treatment, and includes a container 1, an introduction system passage 2 for introducing an inert carrier gas X such as N ₂ or Ar into the container 1, and the container 1 A fan 3 arranged inside the fan 3 for stirring the carrier gas X introduced through the introduction system passage 2 and a green body which is disposed at a position surrounding the fan 3 and which is not shown in the drawing is a green body. The box 4 is made of graphite and is capable of accommodating a large number of pieces at the same time, and an exhaust system passage 5 opening in the box 4. The shaft 3a to which the fan 3 is attached is connected to the external motor 6 via a pipe line 5a on the start end side of the exhaust system passage 5, and a pipe 5b on the end side of the exhaust system passage 5 via a valve 5c. The vacuum pump 5d is connected. In front of the valve 5c, a check valve 5e for atmospheric leak is provided in parallel. In the figure, 7 is a heater for heating the box 4.

During degreasing, the heater 7 and the fan 3 are turned on, and the introduction system passage 2 and the exhaust system passage 5 are operated. At this time, if the valve 5c of the exhaust system is throttled, the inside of the container 1 is in a depressurized state near atmospheric pressure.

Under such a configuration, the carrier gas X introduced into the container 1 from the introduction system passage 2 flows under a differential pressure into the box 4 through the thickness of the box 4 or through a gap, and the box Along with the binder vapor Y, which is the generated gas in the box 4, is agitated by the fan 3 in the box 4, and a part of the gas is discharged to the outside of the container 1 through the exhaust system passage 5. Therefore, there is no problem that temperature unevenness occurs in the box 4 due to convection, or only the binder vapor Y precipitates in the lower space of the box 4 due to the difference in specific gravity, which causes uneven density. And the binder concentration condition can be kept uniform everywhere. In addition, since the stirring area is limited to the inside of the box 4 and the steady differential pressure flow state of the carrier gas X is created, the binder vapor Y is prevented from leaking out of the box 4, so that the inside of the container 1 is prevented. Can be effectively protected from binder pollution.

Therefore, when the heat treatment furnace of the present embodiment is adopted, it is possible to uniformly degrease a plurality of processed products arranged in the box 4, and as a result, the homogeneity between final products can be improved. It has an excellent effect of surely improving as compared with. Further, at that time, the heater 7 and the like can be effectively protected from contamination and the like.

The specific configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the valve 5c may be closed and the gases X and Y may be leaked to the atmosphere via the check valve 5e. Further, as shown in the figure, the carrier gas X may be introduced into the box 4 in parallel through the auxiliary introduction system passage 8 into the box 4. In this case as well, it goes without saying that the relationship between the introduction amounts in the introduction paths 2 and 8 is adjusted so as to satisfy the condition that the inside of the box 4 is kept at a relatively lower pressure than the inside of the container 1. Further, the fan may be arranged in a state of being hung from above in the box, and the type of the fan (stirring direction) is not limited to the illustrated example.

[0014]

[Effect of device]

 As described above, the heat treatment furnace of the present invention is configured so that the carrier gas is stirred by the fan together with the vaporized gas. In addition, in order to prevent the configuration from causing a new problem such as contamination, the area around the fan is surrounded by a box to limit the stirring area, and the exhaust system passage is connected to the box to connect the box to the inside of the box. This is to prevent the generated gas from leaking out of the box by keeping the gas pressure relatively lower than that in the container. Therefore, for example, when it is applied to degreasing treatment, it is possible to uniformly maintain the temperature and binder concentration in the box serving as the treatment atmosphere, and to perform uniform degreasing treatment on a plurality of processed products.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1 ... Container 2 ... Introducing system path 3 ... Fan 4 ... Box 5 ... Exhaust system path X ... Carrier gas Y ... Generated gas (binder vapor)

Claims (1)

[Scope of utility model registration request] 1. A container, an introduction system passage for introducing a carrier gas into the container, a fan for stirring the carrier gas introduced through the introduction system passage, and a position surrounding the fan. Is provided with a breathable box and an exhaust system passage opening into the box, and the carrier gas introduced into the container through the introduction system passage is introduced into the box by a differential pressure flow. A heat treatment furnace characterized in that the heat treatment furnace is made to flow in, stirred with a gas generated in the box by a fan in the box, and partially discharged out of the container through the exhaust system passage.