JP3870571B2 - Electric heating type pressure sintering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric heating type pressure sintering apparatus. More specifically, the present invention relates to an electric heating type pressure sintering in which the amount of heat generated by a heating element is increased and the temperature of a powder is quickly raised to a target temperature. It relates to the device.
[0002]
[Prior art]
As an apparatus for pressure-sintering metal powder, ceramic powder, etc., there is an electric heating type pressure sintering apparatus.
[0003]
As shown in FIG. 3, a conventional electric heating type pressure sintering apparatus is provided with a cylindrical mold 3 having a molding space 2 for pressure-molding the powder 1 therein. The upper heating element 4 and the lower heating element 5 are fitted in the molding space 2.
[0004]
As the material of the mold 3, graphite or the like, which has high strength at high temperatures and is difficult to adhere the powder 1 or the like, is generally used.
[0005]
On the other hand, the upper heating element 4 and the lower heating element 5 are made of, for example, semi-graphite whose electric resistance is increased by containing impurities in the graphite constituting the mold 3, The heating elements 4 and 5 generally have a cylindrical shape as shown in FIG.
[0006]
Further, a pressurizing means 6 made of a hydraulic cylinder or the like is installed on the upper part of the upper heating element 4, and a supporting means 7 made of a pedestal block for supporting the mold 3 and the lower heating element 5 is provided.
[0007]
The pressurizing means 6 and the support means 7 are both good conductors, and a power source 8 is connected between the pressurizing means 6 and the support means 7. As the power source 8, a commercial power source or a DC power source can be used.
[0008]
Note that at least a portion of the mold 3 is accommodated in a vacuum chamber (not shown).
[0009]
In such a configuration, first, in a state where the lower heating element 5 is inserted into the molding space 2 of the mold 3 from the lower side and the mold 3 and the lower heating element 5 are supported by the support means 7 by the pedestal block, Powder 1 such as ceramic is supplied into the molding space 2 from above. Then, the upper heating element 4 is inserted into the molding space 2 from above.
[0010]
In this state, the inside of the vacuum chamber that surrounds at least the mold 3 portion is set to a vacuum state, an inert gas atmosphere, or a reducing gas atmosphere such as hydrogen gas.
[0011]
Further, by applying a voltage between the upper heating element 4 and the lower heating element 5 using the power source 8, a current is supplied to the mold 3 and the powder 1 in the mold 3 through the upper heating element 4 and the lower heating element 5. The powder 1 is heated to a high temperature by the Joule heating of the upper heating element 4 and the lower heating element 5 and the Joule heating of the powder 1 itself.
[0012]
In this state, the upper heating element 4 is lowered by the pressurizing means 6. At this time, since the lower heating element 5 is fixed to the support means 7, the upper heating element 4 and the lower heating element 5 approach each other, whereby the powder 1 between them is pressurized, but the powder 1 Since it is heated to a high temperature and is in a state of being easily bonded, it is sintered into a pressure sintered body.
[0013]
[Problems to be solved by the invention]
In the above-mentioned current heating type pressure sintering apparatus, there is a demand for manufacturing a large-sized sintered body. To manufacture a large-sized sintered body, the entire apparatus is enlarged and the upper heating element 4 is used. Further, the press load between the lower heating element 5 and the heating element 5 is increased. For this reason, the diameter of the heating elements 4 and 5 must be increased from the viewpoint of strength.
[0014]
Here, when the diameters of the heating elements 4 and 5 are increased, the electrical resistance due to the heating elements 4 and 5 is reduced. For this reason, even if a high voltage is applied by the power supply 8, heat generation by the heat generating elements 4 and 5 cannot be sufficiently obtained, and thus there is a problem that the temperature of the powder 1 cannot be increased efficiently. Moreover, since the quantity of the powder 1 increases as the sintered body becomes larger, the supply of heat to the powder 1 decreases, and there is a problem that it takes time to heat the powder 1.
[0015]
In view of the above circumstances, the present invention is an electric heating type pressure firing in which sufficient heating of Joule heat is generated by a heating element even when the diameter of the heating element is increased corresponding to a large sintered body. The object is to provide a binding device.
[0016]
[Means for Solving the Problems]
The present invention supports a mold having a molding space for pressure-forming powder inside, an upper heating element and a lower heating element fitted from above and below into the molding space of the mold, and the mold and the lower heating element. In the energization heating type pressure sintering apparatus, comprising: a supporting means for applying pressure; a pressing means for applying pressure to the upper heating element; and a power source connected to the pressing means and the supporting means. The side heating element comprises a conductor portion and an insulator portion, and a current flows through the powder through the conductor portion having an electric resistance equal to or higher than that of the pressing means and the supporting means. The present invention relates to an electric heating type pressure sintering apparatus.
[0017]
The upper heating element and the lower heating element may have a double structure consisting of a conductor part and an insulator part arranged concentrically, and between the lower heating element and the lower heating element. A spacer may be provided between the heating element and the powder.
[0018]
According to the above means, the following operation can be obtained.
[0019]
When the power is turned on, the upper heating element and the lower heating element are energized, and a current flows through both heating elements. Here, since both of the heating elements are composed of a conductor part having a required electric resistance and an insulator part, even if the diameter of the entire heating element is large, the conductor part that actually generates heat is cut off in the horizontal direction. Since the area is small and the electrical resistance is correspondingly increased, sufficient Joule heat is generated in the heating element.
[0020]
As a result, a large calorific value can be obtained while increasing the diameter of the heating element to keep the surface pressure against the press load low.
[0021]
If a spacer is provided on the surface of the upper heating element and the lower heating element facing the powder, the heat from the conductor portion of the heating element can be dispersed by the spacer, and the powder can be heated uniformly.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to an embodiment of the present invention. The same components as those in FIG. Only the features of the invention will be described.
[0024]
As shown in FIG. 1, an upper heating element 9 and a lower heating element 10 which are fitted in the molding space 2 of the mold 3 and pressurize and heat the powder 1 are provided.
[0025]
The upper heating element 9 and the lower heating element 10 are provided with conductor portions 9a and 10a having required electric resistance on the inner side with the axis as the center, and with insulator portions 9b and 10b concentrically with respect to the outer side. Has a double structure.
[0026]
More specifically, as shown in FIGS. 1 and 2, the upper heating element 9 and the lower heating element 10 are provided inside the insulating portions 9b and 10b made of, for example, ceramic, which are formed in a cylindrical shape. It has a configuration in which conductor portions 9a and 10a made of cylindrical semi-graphite having a required electric resistance are filled and solidified integrally. In contrast to FIGS. 1 and 2, the insulator portions 9b and 10b may be provided inside and the conductor portions 9a and 10a provided outside.
[0027]
In FIG. 1, spacers 11 and 12 are provided on the surfaces of the upper heating element 9 and the lower heating element 10 facing the powder 1.
[0028]
The operation of the above embodiment will be described below.
[0029]
As shown in FIGS. 1 and 2, the upper heating element 9 and the lower heating element 10 have a two-layer structure including insulator portions 9 b and 10 b on the outside and conductor portions 9 a and 10 a at the center. Therefore, in order to manufacture a large-sized sintered body, the conductor portions 9a and 10a themselves that actually generate heat even when the heating elements 4 and 5 having a large diameter and a large pressing load by the pressing means 6 are used. The diameter can be kept small, so that a large electric resistance is obtained. As a result, sufficient Joule heat sufficient to quickly raise the temperature of the powder 1 can be obtained by the conductor portions 9a and 10a.
[0030]
Here, the heat generation amount in the heating elements 9 and 10 will be described.
[0031]
If the power supply 8 is directly connected to both ends of the upper heating element 9 and the lower heating element 10 and a voltage is applied, the general heating elements 4 and 5 shown in FIGS. The heating elements 9 and 10 of the present embodiment shown in FIG. 2 also have the same total heat generation as long as the applied voltage is the same.
[0032]
However, in actuality, a pressurizing means 6 by a hydraulic cylinder connected to a power source 8 and a support means 7 by a pedestal block are connected in series with both heating elements 9 and 10. Therefore, as the resistance of the heating elements 9 and 10 increases, the current i flowing through the whole decreases, and as a result, i1R1 (R1 is the resistance value of the pressurizing means 6) and i2R2 (R2 is the support means 7). The heating value of the pressurizing means 6 portion and the heating value of the support means 7 portion expressed by
[0033]
If the applied voltage of the power source 8 is equal, the total heat generation amount of the entire series circuit is the same. Therefore, if the heat generation amounts of the pressurizing means 6 and the support means 7 are reduced, the heat generation amounts of the heating elements 9 and 10 are correspondingly reduced. Becomes larger. That is, it is possible to increase the amount of heat generated by the heating elements 9 and 10 by using the heating elements 9 and 10 of this embodiment, rather than using the general heating elements 4 and 5 shown in FIGS. It can be done.
[0034]
Note that the conductor portions 9a and 10a of the heating elements 9 and 10 need to have an electrical resistance higher than that of the pressurizing means 6 and the support means 7, and therefore the conductor portions 9a and 10a have semi-graphite or the like. These materials are used.
[0035]
Further, since the spacers 11 and 12 are provided on the surfaces of the upper heating element 9 and the lower heating element 10 facing the powder 1, the heat generated by the conductor portions 9 a and 10 a 12 is dispersed in the radial direction by the heat transfer of 12 and transmitted to the powder 1, so that the powder 1 can be heated uniformly.
[0036]
Furthermore, the spacers 11 and 12 have a shape that closely fits in the molding space 2 of the mold 3, and the powder 1 is between the upper heating element 9 and the lower heating element 10 and the mold 3. Therefore, the spacers 11 and 12 are preferably made of semi-graphite having a thermal expansion coefficient substantially equal to that of a mold made of graphite.
[0037]
In the configuration as described above, when a voltage is applied between the pressurizing means 6 and the support means 7 by the power source 8 as described above, the pressurizing means 6, the conductor portion 9a of the upper heating element 9, the spacer 11, the powder 1, current flows through a path of the mold 3, the spacer 12, the conductor portion 10 a of the lower heating element 10, and the support means 7.
[0038]
At this time, as described above, since Joule heat larger than that obtained when the general heating elements 4 and 5 shown in FIGS. 3 and 4 are used is obtained by the heating elements 9 and 10, even if the volume of the powder 1 is large. The powder 1 can be heated sufficiently. Further, the heat from the conductor portions 9a, 10a of the heating elements 9, 10 is dispersed in the radial direction by the spacers 11, 12, so that the powder 1 can be heated uniformly.
[0039]
In the present embodiment, the case where the conductor portions 9a and 10a are formed inside the heat generating members 9 and 10 and the insulator portions 9b and 10b are formed outside is illustrated. In addition to the heavy structure, a triple or quadruple structure may be used, and further, the conductor portions 9a and 10a may be formed at positions shifted from the axial centers of the heating elements 9 and 10, and the present invention. Of course, various changes can be made without departing from the scope of the present invention.
[0040]
【The invention's effect】
As described above, according to the present invention, the upper heating element and the lower heating element are constituted by the conductor part and the insulator part. While suppressing the pressure, the resistance of the heating element can be increased and the amount of heat generation can be increased. Therefore, it is possible to provide an electric heating type pressure sintering apparatus that can reliably and efficiently produce even a large pressure sintered body.
[0041]
Further, when a spacer is provided on the surface of the upper heating element and the lower heating element facing the powder, the heat from the conductor portion of the heating element can be dispersed by the spacer, and the powder can be heated uniformly. .
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of a heating element according to the embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a conventional electric heating type pressure sintering apparatus.
FIG. 4 is a perspective view of a conventional heating element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Powder 2 Molding space 3 Mold 6 Pressurization means 7 Support means 8 Power supply 9 Upper heating element 9a, 10a Conductor part 9b, 10b Insulator part 10 Lower heating element 11, 12 Spacer

Claims (3)

A mold having a molding space for pressure-molding powder therein, an upper heating element and a lower heating element fitted from above and below in the molding space of the mold, and a support means for supporting the mold and the lower heating element In the energization heating type pressure sintering apparatus comprising a pressurizing means for applying pressure to the upper heating element, and a power source connected to the pressing means and the supporting means, the upper heating element and the lower heating element are An electric heating type heating device characterized in that an electric current flows in the powder through the electric conductor part which has an electric resistance equal to or higher than the electric resistance of the pressurizing means and the supporting means. Pressure sintering equipment. 2. The energization heating type pressure firing according to claim 1, wherein the upper heating element and the lower heating element have a double structure comprising a conductor portion and an insulator portion arranged concentrically. Bonding device. The electric heating type pressure sintering apparatus according to claim 1 or 2, further comprising a spacer between the upper heating element and the powder and between the lower heating element and the powder.

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