JPH06273069A - Burning jig, molded form thereof, mold and molding method therefor - Google Patents

Abstract

PURPOSE:To prevent crack, cut of a molded form to be used to manufacture a burning jig during a manufacturing step and to improve its yield by providing a holding hole for a material to be burned and a region for suppressing a residual stress due to pressure molding at the form. CONSTITUTION:A wheel shaft 11 is rotated in the direction indicated by arrow P to vertically move a ram 12, and a molding material in a cavity between an upper mold 13 and a lower mold 14 is pressurized and molded. A protrusion 13a for forming a hole forming a material to be burned at an obtained molded form 30 is provided at the mold 13. Dams 14a are provided at the mold 14. The form 30 molded by using this friction press molding machine 1 has six holes 33 for holding materials to be burned and two residual stress suppressing regions 35. Thus, a residual stress is not concentrated at a narrow region 31n at the time of drying the form 30, and crack, cut of the form 30 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a firing jig, a molded body used for manufacturing the firing jig, a molding die and a molding method therefor. The present invention relates to a firing jig, a molded body, and the like, which are less likely to cause breakage, etc.

[0002]

2. Description of the Related Art Conventionally, firing jigs such as saggers, setters and shelves have been obtained by filling a press die with a forming raw material such as ceramic powder and pressurizing it. It is manufactured by drying a molded body and then firing it. This manufacturing method is the same for a jig for firing with holes,
For example, as shown in FIG. 4, the molding raw material 1 is pressed by the upper mold 2 and the lower mold 3 to form a molded body 4 as shown in FIGS. 5A and 5B, and then the molded body. 4 is dried and then fired to manufacture a firing jig with holes.

[0003]

However, in the conventional method for manufacturing such a firing jig, as shown in FIG.
As shown in (b) and (b), at the time of pressure molding, the molding raw material 1 is extruded from the narrow region 4n to the wide region 4w as shown by the arrow F, and forms a directional flow. This allows
The internal stress F corresponding to the magnitude of this flow remains inside the molded body 4. Then, in the step of drying the molded body 4, the stress F and the contracting stress (arrow S) generated at the time of drying are antagonized, and these stresses are concentrated in the narrow region 4n in the molded body 4 where the stress relief is poor. There is a problem that cracks or breaks occur in this region 4n.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to perform perforated firing which does not cause cracks or breaks in the manufacturing process and can improve the yield. A jig, a molded body used for the jig, a molding die, and a molding method are provided.

[0005]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by forming a region for suppressing a residual stress due to pressurization in a molded body. The present invention has been completed. Therefore, the molded body for manufacturing a firing jig of the present invention is a pressure molded body of a ceramic material used for manufacturing a firing jig, and has a hole for holding a material to be fired and a pressure. And a region for suppressing residual stress due to molding.

Further, the molding die of the present invention is a molding die for molding the above-mentioned molded body, and is characterized in that an upper mold and / or a lower mold is provided with a dam forming the residual stress suppressing region. Further, the molding method of the present invention is characterized by using a mold having a weir that forms the residual stress suppressing region when molding the above-mentioned molded body. Furthermore, the firing jig of the present invention is characterized by being obtained by firing the above-mentioned molded body.

[0007]

In the present invention, when the molded body is pressure-molded, a region for suppressing the residual stress inside the molded body (hereinafter, referred to as
It is called a "residual stress suppression region". ) Was provided in the molded body. Therefore, when the molded body is dried, the residual stress is not concentrated in the narrow region, and it is possible to prevent the molded body from cracking or breaking.

Next, the molded article of the present invention will be described.
The molded body of the present invention is a molded body used for manufacturing a firing jig with holes. Therefore, the molded product of the present invention has a hole for holding the object to be fired. The number of the holes is not particularly limited and may be 1 or more, but is preferably 4 or more, more preferably 6 or more in view of the production efficiency of the object to be fired and the like. The planar shape of the hole is not particularly limited, but it is preferable that the hole has at least a curved portion such as a circle or an ellipse. Therefore, the molded product of the present invention preferably has the narrow region and the large region as described above. Furthermore, the ratio of the cross-sectional area between the minimum narrow portion, which is the portion having the minimum or maximum cross-sectional area of the narrow area and the wide area, and the maximum wide area, is: Cross-sectional area of vast area = 1: 2 to 1: 2
It is preferably 0.

Further, the molded product of the present invention has a residual stress suppressing region. This residual stress suppressing region is formed by a weir provided in the molding die of the present invention, as described later. The position in the formed body of this region is not particularly limited, and it is sufficient if it is a position where the flow of the forming raw material by pressure forming can be suppressed by being cut off. The vicinity of the hole to be held is preferable, and the vicinity of the large area is more preferable.

The shape of the residual stress suppressing region is not particularly limited, and it is sufficient if it is a concave shape, and not only a cylindrical, prismatic, pyramidal, conical or frustoconical concave part is used. The recess may have a hemispherical shape, a stepped columnar shape, a prismatic shape, or the like, and may have a shape penetrating from the surface portion to the bottom portion of the molded body. Further, the size of the residual stress suppressing region is about 2 to 50 of the cross-sectional area of the maximum wide area.
It is preferably sized to have a cross-sectional area of%.

By providing the residual restraint region as described above (by providing the weir in the molding die), the generation of internal stress due to the flow of the molding raw material in the pressure molding is restrained, and the residual stress restrained region is suppressed. In the vicinity, the density of the forming raw material becomes uniform. Therefore, in the drying step of the molded body, the shrinkage stress uniformly acts in the vicinity of the residual stress suppressing region, and as a result, the molded body is promoted to uniformly shrink, and the above-mentioned cracks and breaks occur. Can be suppressed.

Next, the molding die of the present invention will be described.
The mold of the present invention may be of any type as long as it is a split mold, but a preferable example is a friction press mold having an upper mold and a lower mold. The molding die of the present invention has the weir forming the above-mentioned residual stress suppressing region in the upper die or the lower die, or in the upper die and the lower die. The shape of the weir corresponds to the shape of the residual stress suppressing region, and as described above, the top of the weir has an upper mold and / or a lower mold in order to form the residual stress suppressing region penetrating therethrough. The shape may be such that it contacts the cavity forming surface.

The weir blocks the flow of the forming raw material (particularly, the flow from the narrow region to the large region) at the time of pressure molding, and suppresses the internal stress due to this flow from remaining in the compact. Fulfill. Therefore, the molded body molded using the molding die of the present invention does not cause the above-mentioned cracks or breaks in the drying step.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of a molding machine according to the present invention.
In the figure, a friction press molding machine 10 includes a wheel shaft 11, a ram 12, an upper mold 13, and a lower mold 1.
4 and. By rotating the wheel shaft 11 in the direction of the arrow P shown in the drawing, the ram 12 is moved up and down, and the molding raw material filled between the upper mold 13 and the lower mold 14 (cavity) is pressurized to be molded into a desired shape. To do.

The upper die 13 is provided with a convex portion 13a which forms a hole for holding the object to be fired in the obtained molded body. In the present embodiment, the shape of the convex portion 13a is a cylindrical shape, but this shape can be appropriately changed according to the shape of the object to be fired. The lower mold 14 has a weir 1
4a is provided, and in the case of this embodiment, the weir 14a has a substantially columnar shape.

Next, the molded body 30 of the present invention molded by using the friction press molding machine 10 will be described. 2 is a plan view showing an example of the molded body 30 of the present invention, FIG.
(A) is sectional drawing in the XX line of FIG. Figure 2
Also, in FIG. 3A, the molded body 30 is a molded body used for firing a perforated bowl, and includes a plate-shaped portion 31 and a standing edge portion 32.
It has and. In addition, as shown in FIG. 2, this molded body 30 has six holes 33 for holding an object to be fired and two residual stress suppressing regions 35.

In the molded body 30, the ratio of the cross-sectional areas of the minimum narrow portion 31 _min indicated by the line segment AB of the narrow region 31n and the maximum wide portion 31 _max of the wide region 31w indicated by the line segment CD is the cross-sectional area of 31n: 31w cross-sectional area = 1: 2 to 1: 2
It is preferably 0. In addition, the cross-sectional area of the residual stress suppressing region 35 is preferably about 2 to 50% of the cross-sectional area of the maximum wide portion 31 _max . If it is less than 2%, the flow of the raw material for the molded body cannot be suppressed, and if it exceeds 50%, the strength of the resulting casket is lowered, which is not preferable.

By providing the residual stress suppressing region 35 as described above, the flow of the forming raw material as shown by the arrow F in the figure is interrupted, so that the residual stress accumulated inside the molded body 30 is suppressed. . On the other hand, in the vicinity of the residual suppression region 35, the distribution of the molding raw material becomes uniform (that is, the density of the molded body becomes uniform). Therefore, in the drying step which is the next step, the residual stress of the molded body 30 is small and the density is uniform, so that the shrinkage stress is also small, and cracks or breaks (particularly cracks or breaks in the narrow region 31n) occur. It can be prevented.

Further, as the residual stress suppressing region 35, it is sufficient if the flow of the forming raw material can be suppressed. Therefore, as shown in FIGS. 3 (b) and 3 (c), from the surface portion 31t to the bottom surface of the plate-like portion 31. Through-hole up to the portion 31b, and the surface portion 31
It may be a concave portion provided at t. Correspondingly, the weir 14a of the friction press molding machine 10 may be provided in the upper mold 13, or the weir 14a may be provided in each of the upper mold 13 and the lower mold 14.

Example 1 A mixture of alumina powder and clay was used as a molding raw material and was molded at a molding pressure of 300 kg / cm ² using a friction press molding machine 10 to obtain a molded body. The obtained molded body was dried in a drying chamber at 80 ° C. for 24 hours. No cracks or breaks were observed during this drying. Next, this molded body was fired in an air atmosphere at 1400 ° C. for 5 hours to obtain a perforated bowl.

Example 2 The same operation as in Example 1 was repeated except that the residual stress suppressing region of the molded body had a shape as shown in FIG. 3 (b). No cracks or breaks occurred during drying. It baked similarly and the perforated box was obtained. (Example 3) The residual stress suppressing region of the molded body is shown in FIG.
The same operation as in Example 1 was repeated except that the shape shown in FIG. No cracks or breaks occurred during drying.
It baked similarly and the perforated box was obtained.

Example 4 The same operation as in Example 1 was repeated except that the residual stress suppressing region of the molded body was changed from a cylindrical shape to a hemispherical shape. No cracks or breaks occurred during drying. It baked similarly and the perforated box was obtained. (Comparative Example 1) The same operation as in Example 1 was repeated except that the residual stress suppressing region was not provided in the molded body. Cuts occurred during 30 minutes during drying. When baked as it is,
There were many cracks and breaks, and it could not be used as a product.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to this, and various modifications can be made within the scope of the present invention. For example, the present invention can be applied not only to a perforated bowl, but also to a setter, a shelf board, or the like for a perforated firing jig. Further, the number and dimensions of the holding hole portion and the residual stress suppressing region of the object to be fired are
It can be appropriately changed according to the size of the forming raw material and the firing jig.

[0024]

As described above, according to the present invention,
Since a region for suppressing the residual stress due to pressure is formed in the molded body, a jig for perforated firing that does not cause cracks or breaks in the manufacturing process and can improve the yield, a molded body used for this, a molding die and A molding method can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a molding machine according to the present invention.

FIG. 2 is a plan view showing an embodiment of the molded body of the present invention.

FIG. 3 is a cross-sectional view taken along the line XX of the molded body shown in FIG. 2 and similar sectional views of other molded bodies.

FIG. 4 is a cross-sectional view showing an example of a conventional molding die.

FIG. 5 is a plan view and a cross-sectional view of a molded body used in a conventional perforated firing jig.

[Explanation of symbols]

10 Friction Press Molding Machine 13 Upper Mold 14 Lower Mold 14a Weir 20 Molding Material 30 Molded Body 31n Narrow Area 31w Wide Area 31 _min Minimum Narrow Area 31 _max Maximum Wide Area 33 Residual Stress Suppression Area 35

Claims (6)

[Claims] 1. A pressure-molded body of a ceramic material, which is used for manufacturing a firing jig, and has a hole for holding an object to be fired and a region for suppressing a residual stress due to the pressure molding. A molded body for manufacturing a firing jig, characterized in that 2. A narrow area and a wide area are provided in the vicinity of the holding hole, and the ratio of the cross-sectional area in the maximum wide area to the cross-sectional area of the minimum narrow area is 1: 2 to 1:20. The molded article according to claim 1, characterized in that 3. A mold for molding the molded body according to claim 1, wherein the upper mold and / or the lower mold is provided with a dam forming the residual stress suppressing region. 4. The top of the weir is in contact with the cavity forming surface of the upper die and / or the lower die.
Mold described. 5. A molding method, wherein the molding die according to claim 3 is used for molding the molding according to claim 1. 6. A firing jig, which is obtained by firing the molded body according to claim 1.