JPH06108116A - Degreasing device for green compact to be sintered - Google Patents

Abstract

PURPOSE:To degrease green compacts without generating shear droop and deformation by degreasing the green compacts while rotating a mounting surface non-disengeeably mounted to the green compacts around a horizontal axial center. CONSTITUTION:The central parts on both side edges of a flat planar support 2 are pivotally fitted to a horizontal shaft 4 via a pair of arms 3 and both ends of this horizontal shaft 4 are rotatably supported to a pair of end plates 6, 6 erected from a common supporting base 5. A setter 7 made of Mo is fixed onto the mounting surface 2a of the front surface of the support 2 and the rear surfaces of the body part 1a of the green compacts 1 are adhered via an adhesive onto this setter by the adhesive force to withstand the tensile strength higher than the weight of the green compacts 1. While the green compacts A are rotated around the axial center m by rotating the horizontal shaft 4 with a motor 8, the device A is heated together with the green compacts 1 and the green compacts 1 are subjected to the degreasing treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degreasing device for a green body for sintering, which can complete degreasing without causing sagging or deformation of the green body.

[0002]

2. Description of the Related Art In a powder injection molding manufacturing process, a binder (a low molecular weight component such as paraffin wax, a high molecular weight component such as a polyamide resin, etc.) is mixed with a powder of metal, ceramics, cermet or the like in an appropriate amount. What is called) is kneaded and injection-molded into a required shape to form a so-called green body. Then, the green body is degreased in the degreasing step to be in a so-called brown body state. Then, finally, the brown body is subjected to sintering in a sintering step to finish into a strong final product.

[0003]

By the way, in the above-mentioned degreasing step, mainly in the first half, when the green body is rapidly heated, the bander becomes viscoplastic and the shape of the green body is drooped or deformed. For this reason, conventionally, the green body has been heated in a region below the softening temperature to gradually volatilize the binder. That is, the binder includes various materials from low melting point to high melting point as described above, and these binders melt all at once when the green body is rapidly heated and heated to prevent anybody from deforming. However, by controlling the rate of temperature rise, the proportion of binders that are simultaneously melted at a certain moment is limited, so that binders with different melting points are bridged and melted one after another, resulting in binder shape retention. Before the power is lost, the shape retention of the brown body can be expressed to some extent to prevent sagging or deformation.

However, even with such a method,
It is difficult to completely overcome the problem of who and the deformation.
That is, such dripping or deformation is caused as a result of the effect of gravity acting on the green body as a shearing force or a compressing force, and the green body is extremely vulnerable to the shearing force. Therefore, the green body having a three-dimensional or complicated shape in which the shearing force acts more greatly has a problem that the degree of sagging or deformation increases and the dimensional accuracy of the final product is significantly deteriorated.

The present invention has been made in view of these problems, and a degreasing apparatus for a green body for sintering, which is capable of completing degreasing while effectively preventing sagging or deformation of the green body. Is intended to provide.

[0006]

The present invention adopts the following constitution in order to achieve the above object.

That is, in the degreasing device for a green body for sintering according to the present invention, a mounting surface for permanently mounting the green body with a tensile strength equal to or more than its weight and a rotating means for rotating the mounting surface around the horizontal axis. And the degreasing progresses while rotating the green body around the horizontal axis through the rotating means.

Preferred embodiments include a mode in which the rotation speed is set to a constant speed that is gentle to some extent, a mode in which the center of gravity of the green body is positioned on the horizontal axis, and the like.

As a method of mounting the green body on the mounting surface, an adhesive may be applied to the boundary surface.

[0010]

With such a structure, the vector of the shearing force or the compressive force acting on the green body due to gravity changes with the rotational movement of the green body around the horizontal axis, and the green body is When it makes one rotation, it is canceled in a circular integral manner. For this reason, it becomes possible to proceed with degreasing in a state substantially equivalent to a state in which shearing force or compressive force hardly acts on the green body. Further, by performing particularly gentle constant speed rotation, the equivalence can be improved and the influence of centrifugal force can be reduced. Further, when the center of gravity of the green body is positioned on the horizontal axis, it becomes possible to minimize the influence of centrifugal force.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The degreasing device A for the green body for sintering is particularly preferably applicable to the green body 1 shown in the drawing.
The green body 1 is made by injection molding after kneading the powder and the binder, and the top plate portion 1c is connected to the upper portion of the main body portion 1a via the neck portion 1b. Then, the neck portion 1b and the top plate portion 1c are apt to be subjected to a shearing force due to their own weight, and the usual degreasing treatment is most likely to cause drooping or deformation during a long degreasing step.

Therefore, in the degreasing apparatus A of this embodiment, the central portions of both side edges of the flat plate-like support body 2 are axially attached to the horizontal shaft 4 via the pair of arms 3, and both end portions of the horizontal shaft 4 are It is rotatably supported by a pair of end plates 6, 6 standing from a common support 5. The upper surface 2a of the support 2 constitutes the mounting surface of the present invention. Then, one end of the horizontal shaft 4 is connected to a motor 8 serving as a rotating means placed apart from the other, and the horizontal shaft 4 is driven to rotate at a constant speed by the motor 8 at a required speed (for example, 6 rpm). .

In such a structure, the mounting surface 2a
A setter 7 made of Mo (molybdenum) is fixed on the upper surface, and the lower surface of the main body 1a of the green body 1 is attached to the setter 7 with an adhesive. As the adhesive, one having an adhesive strength capable of withstanding the tensile strength of the green body 1 or more is used. The setter 7 has a thickness dimension that allows the center of gravity G of the green body 1 to be positioned on the axis m of the horizontal axis 4.

Then, this apparatus A is heated together with the green body 1, and a degreasing treatment is applied along a predetermined temperature pattern. As an example of the temperature treatment pattern, first, the green body 1 is heated relatively quickly to 80 ° C. immediately after the start of degreasing,
A pattern is adopted in which the temperature is raised to 200 ° C. over 12 hours from then, and further raised to 400 to 500 ° C. in the subsequent degreasing step. After the degreasing is completed, the process proceeds to the sintering process and is heated to 1,000 degrees or more.

According to the apparatus A as described above, the green body 1 is fixed on the mounting surface 2a, and the green body 1 is moved around the axis m.
It rotates at a rate of 1 rotation in 0 seconds, and degreasing proceeds in that state. Therefore, a vector of shearing force or compressive force (not shown) that acts on the green body 1 due to gravity.
Changes as the green body 1 rotates, and the green body 1 is canceled in a round integral manner when the green body 1 makes one rotation. Therefore, degreasing can be progressed in a state almost equivalent to a state in which the shearing force and the compressing force hardly act on the green body 1, and as a result, even if the green body 1 has a three-dimensional shape as shown in the drawing, it is a final product. It is possible to reliably improve the dimensional accuracy of. Further, in this embodiment, since the processing is performed at a gentle constant speed of 6 rpm, the equivalence can be improved and the influence of centrifugal force can be reduced. In particular, since the center of gravity G of the green body 1 is located on the horizontal axis m, the influence of centrifugal force can be minimized. Furthermore, since the sagging and the deformation are effectively prevented, it becomes easier to increase the temperature rising speed and the degreasing speed as compared with the conventional case.

The present invention is not limited to the above-mentioned embodiments. For example, in the above-described embodiment, the green body is attached to the mounting surface with an adhesive, but the green body may be sucked to the mounting surface side by vacuum exhaust means. Alternatively, a part of the green body may be mechanically fixed. Further, the rotation speed of the horizontal axis is not limited to the above-mentioned value, and an appropriate value can be set at any time from the viewpoint of prevention of drooping and deformation and centrifugal force.

[0018]

As described above, the degreasing device for a green body for sintering according to the present invention is designed to perform degreasing while rotating the entire green body around a horizontal axis. Can be canceled in a circular integral manner, and degreasing can be progressed in a state almost equivalent to a state in which gravity does not work. For this reason, it is possible to prevent sagging or deformation of a green body having a three-dimensional shape or a relatively complicated shape, and reliably improve the dimensional accuracy of the final product. Further, by effectively preventing sagging or deformation, it becomes easier to increase the temperature rising rate and the degreasing rate faster than in the past.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 ... Green body 2a ... Mounting surface 8 ... Rotating means (motor) A ... Degreasing device m ... Horizontal axis

Claims (1)

[Claims] 1. A green body is provided with a mounting surface for permanently mounting the green body with a tensile strength equal to or greater than its weight, and a rotating means for rotating the mounting surface around a horizontal axis. A degreasing device for a green body for sintering, which is characterized by advancing degreasing while rotating around an axis.