JP6418984B2 - Jig and mold - Google Patents

Description

  The present invention relates to a jig and a mold, and more particularly to a jig and a mold used in a hot press furnace.

  Conventionally, as a mold used in a hot press furnace, for example, a mold in which a plurality of cylinders are taper-fitted to each other has been proposed. Furthermore, in a mold in which the coefficient of thermal expansion of the inner cylinder is larger than that of the outer cylinder, the inner cylinder may be tightened to the outer cylinder to cause compressive stress in the inner cylinder. (For example, refer to Patent Document 1).

Utility Model Registration No. 2553811

  By the way, in a shaping | molding die, since the internal diameter of a shaping | molding die spreads during baking (during high temperature) by the thermal expansion of the shaping | molding die itself, the diameter of a baking target object may become a little larger than a design value. Thereafter, when the temperature is lowered, the mold returns to the original inner diameter due to thermal contraction. At this time, when the thermal expansion coefficient of the object to be fired is small, the diameter of the fired product after cooling is larger than the diameter of the internal space of the mold, so the mold does not shrink to the original inner diameter. Internal pressure sometimes occurred and the mold was damaged. Further, when the mold is deformed into a drum shape due to the internal pressure, the firing object cannot be taken out, and a large force is required when removing the mold from the mold, and the mold may be damaged. In addition, the fired product was also heavily compressed and sometimes damaged.

  The present invention has been made in view of such problems, and a jig and a mold that can further suppress the occurrence of defects in the outer mold used in a hot press furnace and the defects in the fired product. The main purpose is to provide.

  As a result of diligent research to achieve the above-described main object, the present inventors have, for example, provided an outer mold used in a hot press furnace by providing a space to relieve stress between the firing object and the outer mold. It has been found that the occurrence of this problem can be further suppressed, and the present invention has been completed.

That is, the jig of the present invention is
A jig used in a hot press furnace for firing a firing object,
The outer mold having a thermal expansion coefficient larger than the thermal expansion coefficient of the firing object and the firing object are formed between the outer mold and a relaxation portion that is a space for relaxing stress. is there.

The mold of the present invention is
A mold used in a hot press furnace for firing a firing object,
An outer mold having a thermal expansion coefficient larger than that of the firing object;
The jig described above,
It is equipped with.

  The jig and mold of the present invention can further suppress the occurrence of defects in the outer mold used in the hot press furnace. This is because, for example, a jig is formed with a relaxation portion that is a space for relaxing stress between the firing object and the outer mold. For this reason, even if the outer mold has a larger coefficient of thermal expansion than the firing object, it is considered that this stress can be relaxed by the deformation of the jig.

An explanatory view showing an outline of composition of hot press furnace. The exploded perspective view of the shaping | molding die 20. FIG. Sectional drawing of the shaping | molding die 20 before baking. Sectional drawing of the shaping | molding die 20 after baking cooling.

  Next, modes for carrying out the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of a configuration of a hot press furnace 10 provided with a mold 20 according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the mold 20. FIG. 3 is a cross-sectional view of the mold 20 before firing. FIG. 4 is a cross-sectional view of the mold 20 after firing and cooling.

  The firing object 11 may be a ceramic material, for example. Ceramic materials have a relatively small coefficient of thermal expansion, and are highly meaningful for applying the present invention. Examples of the firing object 11 include silicon-containing materials such as cordierite, silica, mullite, β-eucryptite, β-spodumene, silicon nitride, silicon carbide, sialon, aluminum titanate, zircon, and zirconium phosphate compounds. Among them, cordierite, aluminum titanate, silicon nitride, and sialon are materials having a low coefficient of thermal expansion and are highly suitable. The coefficient of thermal expansion of the firing object 11 may be, for example, in the range of 0.1 ppm / K to 3 ppm / K. Moreover, the thermal expansion coefficient of the baking object 11 is good also as what is the range of 3 ppm / K or more and 10 ppm / K or less according to the thermal expansion coefficient of the shaping | molding die 20, for example.

  Here, the coefficient of thermal expansion uses the value measured in the range of 40 degreeC-1000 degreeC using the push rod type dilatometer as a representative value of each material. The measurement of the coefficient of thermal expansion is performed by detecting a dimensional change of the sample with a displacement detector placed outside through a push rod brought into contact with the end surface of the sample. A differential transformer is used as the displacement detector, and quartz glass or alumina is used as the material of the sample support portion including the push rod.

  As shown in FIG. 1, the hot press furnace 10 accommodates the heater 12 disposed on the outer peripheral side in the furnace, the upper punch 14 and the lower punch 16 that press the firing object 11, and the firing object 11. A mold 20. The hot press furnace 10 is configured to have heat resistance that is fired at 2500 ° C. or lower while pressurizing the firing object 11 in a range of 50 MPa or lower, for example.

  The molding die 20 is disposed between the die 21 disposed on the outermost periphery, the sleeve 22 disposed on the inner periphery of the die 21, and the firing object 11 and the sleeve 22. And a member 24. The die 21 is a cylindrical type made of a heat-resistant member, and the inner peripheral surface of the internal space into which the sleeve 22 is fitted is formed as a tapered surface. The heat-resistant member is preferably a thermally and chemically stable material, and examples thereof include carbon, zirconia, and alumina, and among these, carbon is preferable. For example, the thermal expansion coefficient when the die 21 is carbon may be in the range of 3 ppm / K or more and 10 ppm / K or less. The sleeve 22 has a cylindrical shape made of a heat resistant member, and is formed in a tapered surface so that the outer peripheral surface thereof matches the inner peripheral surface of the die 21. In the sleeve 22, a space in which the cylindrical relaxation member 24 is fitted is formed on the inner side. The sleeve 22 and the relaxation member 24 may have a structure that is divided into a semicircular shape (180 °), such as two divisions, three divisions (120 °), or four divisions (90 °). The die 21 and the sleeve 22 may be made of the same material or different materials. When the sleeve 22 is made of carbon, the thermal expansion coefficient may be in the range of 3 ppm / K or more and 10 ppm / K or less. The die 21 and the sleeve 22 constitute an outer mold 29 of the mold 20. The outer mold 29 has a thermal expansion coefficient larger than that of the firing object 11.

  The relaxation member 24 is disposed between the outer mold 29 and the firing object 11, and a relaxation portion 26 that is a space for relaxing stress is formed on the outer peripheral surface 25. The relaxation member 24 is a cylindrical type (including the aforementioned divided structure) made of a heat-resistant member. The firing object 11 is accommodated in the columnar inner space 27, and the upper punch 14 and the lower punch 16. Is inserted into the internal space 27. The relaxation member 24 may be formed of the same material as the outer mold 29 or may be formed of a different material. The thermal expansion coefficient when the relaxing member 24 is carbon may be in the range of 3 ppm / K to 10 ppm / K.

  As shown in FIG. 2, the relaxing portion 26 is formed in a concave shape over the outer periphery of the relaxing member 24. When the relaxation member 24 is fitted into the sleeve 22, a space (relaxation portion 26) is formed between the inner peripheral surface of the sleeve 22 and the outer peripheral surface of the relaxation member 24. The relaxing portion 26 is preferably formed on the entire outer periphery of the relaxing member 24, but there may be a portion that is not partially formed on the outer periphery of the relaxing member 24. The thickness of the relaxing member 24, particularly the thickness T (see FIG. 3) of the wall portion 28 in the region where the relaxing portion 26 is formed is not significantly deformed by the press pressure at the time of temperature rise, and the outer mold at the time of temperature decrease. It is preferable to have a thickness that can absorb the stress caused by the difference in thermal expansion between the material 29 and the firing object 11.

  As shown in FIG. 4, the relaxing portion 26 is preferably formed to have a length X that is longer than the length L of the firing object 11 after firing and cooling. In the relaxation part 26, it is easy to absorb the stress generated by the difference in thermal expansion between the outer mold 29 and the firing object 11. The relaxation part 26 is provided for the relaxation member 24 with respect to the inner diameter D before firing of the relaxation member 24 and the outer diameter F after firing cooling of the firing object 11 determined by the difference in thermal expansion between the firing object 11 and the outer mold 29. And the thickness Y of the relaxing portion 26 in the contact portion between the firing object 11 after firing and cooling satisfies at least 1/2 times the difference value G (G = FD) between the outer diameter F and the inner diameter D ( Y ≧ G / 2) is preferred. When the thickness Y satisfies 1/2 times G or more, the stress generated by the difference in thermal expansion between the outer mold 29 and the firing object 11 is easily absorbed by the relaxation portion 26.

  Next, the operation of the hot press furnace 10 configured as described above, particularly the operation related to thermal expansion and contraction in the mold 20 will be described. First, the die 21, the sleeve 22, and the relaxation member 24 are assembled into the mold 20. The molding die 20 may be all made of carbon. Next, the mold 20 is disposed inside the hot press furnace 10, and the lower punch 16 is inserted into the internal space 27 of the relaxation member 24. Next, a molded product of the raw material powder (for example, cordierite) of the firing object 11 is put into the internal space 27 of the relaxation member 24, and the upper punch 14 is inserted into the internal space 27 of the relaxation member 24 (see FIG. 3). Next, the temperature is raised by the heater 12 to a firing temperature (for example, 1425 ° C.) while applying a predetermined pressure (for example, 5 MPa) by the upper punch 14 and the lower punch 16. At this time, the thermal expansion of the mold 20 shows the maximum, and the firing object 11 is pressed and fired with the size of the internal space 27 that is thermally expanded. Subsequently, after a predetermined time has elapsed, the temperature is lowered to room temperature. At this time, since the thermal expansion of the firing object 11 is small, the shrinkage due to cooling is smaller than that of the mold 20 and an internal pressure is generated in the mold 20, but the internal pressure can be absorbed by the relaxation portion 26. (See FIG. 4).

  According to the mold 20 of the present embodiment described above, it is possible to further suppress the occurrence of defects in the outer mold 29 used in the hot press furnace 10. This is because, for example, the relaxation member 24 (jig) is formed with a relaxation portion 26 that is a space for relaxing stress between the firing object 11 and the outer mold 29, so that the outer mold 29 is the firing target. This is because even when the thermal expansion coefficient is larger than that of the object 11, the stress can be relaxed by the deformation of the relaxation member 24.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the mold 20 including the relaxation member 24 has been described. However, the present invention is not particularly limited thereto, and may be the relaxation member 24 as a jig of the present invention. If the relaxation member 24 is used in combination with the outer mold 29, the same effect as the above-described embodiment can be obtained.

  Below, the example which specifically manufactured the shaping | molding die 20 which has the jig | tool (relaxation member 24) of this invention is demonstrated as an Example.

[Making mold]
A die having a height of 250 mm and an outer diameter of 250 mm was produced using carbon (thermal expansion coefficient 5.6 ppm / K). A sleeve having a height of 250 mm and an outer diameter of 13.5 to 14.5 mm to be inserted into the die was produced using carbon. Further, a relaxation member having a height of 250 mm and an outer diameter of 125 mm to be inserted into the sleeve was produced using carbon. The length X of the relaxation part was 7 times the length of the firing object after firing and cooling. Further, the thickness Y of the relaxation portion at the contact portion between the relaxation member and the firing object after firing cooling is a difference value G between the outer diameter F after firing cooling of the firing object and the inner diameter D before firing of the relaxation member. More than 1/2 times. Thus, the shaping | molding die shown in FIGS. 1-4 was created.

  The object to be fired is cordierite (thermal expansion coefficient of 1.5 ppm / K), 500 g of raw material powder is molded into a columnar shape having a diameter of about 105 mm and a height of about 50 mm, and placed in the internal space of the relaxation member of the above mold. Firing was carried out under the conditions of a temperature rate of 50 K / hr, a firing temperature of 1425 ° C., a holding time of 5 hours, and a press pressure of 5.0 MPa. After firing, it was cooled in a press-free condition at a temperature drop rate of 200 K / hr. As a result of firing, the die and the sleeve (outer mold) could be easily removed, and no defects occurred in the outer mold. The fired body had a cylindrical shape with a diameter of about 105.5 mm and a height of about 23 mm, and no defects such as damage occurred. The reason for this was presumed to be that the stress caused by the difference in thermal expansion between the mold and the firing object could be sufficiently relaxed by the relaxation portion of the relaxation member (the jig of the present invention).

  In addition, this invention is not limited to the Example mentioned above at all, and as long as it belongs to the technical scope of this invention, it cannot be overemphasized that it can implement with a various aspect.

  The present invention can be used in a technical field related to firing that performs hot press firing.

  DESCRIPTION OF SYMBOLS 10 Hot press furnace, 11 Firing object, 12 Heater, 14 Upper punch, 16 Lower punch, 20 Mold, 21 Dies, 22 Sleeve, 24 Relaxing member, 25 Outer peripheral surface, 26 Relaxing part, 27 Internal space, 28 Wall part , 29 outer mold, D inner diameter, F outer diameter, G difference value, L, X length, T, Y thickness.

Claims (4)

A jig used in a hot press furnace for firing a firing object,
Said outer mold having a large thermal expansion coefficient than the thermal expansion coefficient of the fired matter and is disposed between the firing object, alleviating portion is a space to relax a stress is formed on the outer peripheral surface,
The relaxed portion has a thickness Y of the relaxed portion at a contact portion between the jig and the fired object after firing and cooling, an inner diameter D before firing of the jig, and after firing and cooling of the fired object. A jig that satisfies an outer diameter F satisfying ½ times or more the difference value G (G = FD) between the outer diameter F and the inner diameter D (Y ≧ G / 2) .   The jig according to claim 1, wherein the relaxation portion is formed to have a length longer than that of the firing object after firing. The relaxation portion is formed over the entire circumference of the jig, the jig according to claim 1 or 2. A mold used in a hot press furnace for firing a firing object,
An outer mold having a thermal expansion coefficient larger than that of the firing object;
The jig according to any one of claims 1 to 3 ,
A mold equipped with.

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