JP4168521B2 - 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. 8, an example of a conventional electric heating type pressure sintering apparatus is provided with a mold 3 provided through a molding space 2 for pressure-molding the powder 1 therein. The molding space 2 is provided with heating elements 4 and 5 which are fitted to face each other.
[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 heating elements 4 and 5 are made of, for example, semi-graphite or the like whose electrical resistance is increased by containing impurities in the graphite constituting the mold 3. Generally has a cylindrical shape as shown in FIG.
[0006]
Further, the heating element 5 and the mold 3 on one side (lower side in FIG. 8) are supported by the support means 7 including the pedestal block 7a, and the upper side of the heating element 4 on the other side (upper side in FIG. 8) A pressurizing means 6 comprising a hydraulic cylinder or the like for applying pressure to the body 4 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 AC power source or a DC power source can be used.
[0008]
At least the part of the mold 3 can be held in a non-oxidizing atmosphere by a method such as housing in a vacuum chamber (not shown).
[0009]
In such a configuration, first, in a state where the heating element 5 is inserted into the molding space 2 of the mold 3 from below and the mold 3 and the heating element 5 are supported on the pedestal block 7a of the support means 7, metal, ceramic, etc. The powder 1 is supplied into the molding space 2 from above. Then, the 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 kept in a non-oxidizing atmosphere by making it a vacuum state, or an inert gas atmosphere or a reducing gas atmosphere such as hydrogen gas.
[0011]
Further, by applying a voltage between the pressurizing means 6 and the supporting means 7 using the power source 8, a current is caused to flow to the mold 3 and the powder 1 in the mold 3 through the heating elements 4 and 5, and the current generates heat. The powder 1 is heated to a high temperature by the Joule heat generation of the bodies 4 and 5, and further by the Joule heat generation of the powder 1 itself.
[0012]
In this state, the heating element 4 is lowered by the pressurizing means 6. At this time, since the lower heating element 5 is fixed by the support means 7, the heating elements 4 and 5 are relatively close to each other, whereby the powder 1 therebetween is pressurized and the powder 1 is heated to a high temperature. Since it 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 volume pressure sintered body, and in order to manufacture a large volume pressure sintered body, the entire apparatus is enlarged. In addition to this, the press load between the heating elements 4 and 5 also increases, and 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 heating 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 volume of the pressure-sintered body to be manufactured increases, the supply of heat to the powder 1 decreases, and there is a problem that it takes time to heat the powder 1. is there.
[0015]
The present invention has been made in view of the above-described circumstances, and even when the diameter of the heating element is increased in response to the large volume sintered body, sufficient Joule heat is generated in the heating element. Thus, it is an object of the present invention to provide an electric heating type pressure sintering apparatus capable of efficiently producing even a pressure sintered body having a large volume.
[0016]
[Means for Solving the Problems]
The present invention relates to a mold having a molding space for pressure-molding powder therein, a heating element fitted so as to face the molding space inside the mold, and a support means for supporting the mold and one heating element. Each of the heating elements is made of semi-graphite , and a heating means for applying pressure to the other heating element, and a power source connected to the pressing means and the supporting means. comprising conductive portions and the conductor material portion electrical resistance than is constituted by a large insulator portion, and each heating element, electric heating type, characterized in that it consists of the block body are stacked in a plurality of stages This relates to a pressure sintering apparatus.
[0017]
Here, each block of the heating element may have a multilayer structure according to the insulation body conductive portion disposed concentrically, also a cylindrical conductive portions, the conductive portions The insulator portion may be filled with a depth smaller than the thickness of the conductor portion, leaving a periphery on the circular surface.
[0018]
The present invention relates to a mold having a molding space for pressure-molding powder therein, a heating element fitted so as to face the molding space inside the mold, and a support means for supporting the mold and one heating element. Each of the heating elements is made of semi-graphite , and a heating means for applying pressure to the other heating element, and a power source connected to the pressing means and the supporting means. conductive portions and the conductor material portion made is constituted by a high electric resistance insulator portion than further respective heating element, a cylindrical insulator portion, the inside the insulator portion of the insulator portion The present invention relates to an electric heating type pressure sintering apparatus characterized in that it has one or more conductor parts parallel to an axis.
[0019]
In addition, a plurality of molds having a molding space for pressure-molding the powder therein are provided so that the molding space is in a straight line, and three or more heating elements are fitted so as to fit in each molding space of each mold. You may have.
[0020]
According to the above means, the following operation can be obtained.
[0021]
When the power is turned on, the opposing heating elements are energized through the pressurizing means and the supporting means, and a current flows through both heating elements. Here, since both the heating elements are composed of a conductor part having a required electric resistance and an insulator part, and are composed of block bodies stacked in a plurality of stages, the diameter of the entire heating element Is large, the horizontal cross-sectional area of the conductor portion that actually generates heat is small, so that the electrical resistance increases accordingly, and sufficient Joule heat is generated in the heat generator.
[0022]
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.
[0023]
In addition, since the heating element is composed of block bodies stacked in a plurality of stages, a contact resistance is generated between the block bodies overlapping in the vertical direction, and the electrical resistance is further increased by this contact resistance. Therefore, it is possible to obtain a larger calorific value than that obtained by integrating the heating elements.
[0024]
Each block of the heating element, or a multi-layer structure by an insulating body concentrically arranged electrical conductors section, also leaving a cylindrical conductor portion, a peripheral circular surface of the conductive portion If the shape has an insulator portion filled with a depth smaller than the thickness of the conductor portion, the powder can be heated at a substantially uniform temperature in the circumferential direction.
[0025]
Furthermore, if each heating element is formed of a cylindrical insulator part and a plurality of conductor parts parallel to the axis of the insulator part inside the insulator part, the diameter of the entire heating element is large. The horizontal cross-sectional area of the conductor portion that actually generates heat can be set small, and further, the dispersed heating can be performed in the horizontal direction, so that the powder can be uniformly heated.
[0026]
In addition, a mold having a molding space for pressure forming the powder therein is provided in a plurality of stages so that the molding space is in a straight line, and a plurality of heating elements are provided so as to fit in the molding space of each mold. At the same time, a plurality of pressure sintered bodies can be manufactured.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
FIG. 1 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to the first embodiment of the present invention. The same components as those in FIG. Only the features of the present invention will be described.
[0029]
As shown in FIG. 1, an upper heating element 9 and a lower heating element 10 which are fitted so as to face the molding space 2 inside the mold 3 and pressurize and heat the powder 1 are provided. ing.
[0030]
Heating elements 9 and 10, conductor portion 9a having a required electrical resistance inside about its axis, provided with 10a, have a double structure having an insulator portion 9b, and 10b concentrically with respect to the outer In addition, each of the heating elements 9 and 10 has a laminated structure of block bodies 12 divided into a plurality of parts in the axial direction.
[0031]
More specifically, each of the block bodies 12 constituting the heating elements 9 and 10 is formed at the center of the inside of the insulator portions 9b and 10b made of, for example, ceramic formed in a cylindrical shape as shown in FIG. 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. Of course, the conductor portions 9a and 10a and the insulator portions 9b and 10b may have a multilayer structure of a double structure or more.
[0032]
In addition, a spacer 11 is provided between the heating elements 9 and 10 including the block body 12 and the powder 1. The spacer 11 is made of a material having a smaller electric resistance than the conductor portions 9a and 10a.
[0033]
The operation of the above embodiment will be described below.
[0034]
As shown in FIG. 1, the heating elements 9 and 10 have a multilayer structure in which insulator parts 9b and 10b are provided on the outside and conductor parts 9a and 10a are provided on the center part. In order to produce a bonded body, even if the heating elements 9 and 10 having a large press load and a large diameter are used, the diameters of the conductor portions 9a and 10a themselves that actually generate heat are kept small. And thus a large electrical 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.
[0035]
Here, the heat generation amount in the heating elements 9 and 10 will be described.
[0036]
If the power source 8 is directly connected to both ends of the heating elements 9 and 10 and a voltage is applied, the general heating elements 4 and 5 shown in FIGS. 8 and 9 are also of the present embodiment shown in FIG. Of course, if the applied voltage is the same for the heating elements 9 and 10, the total heat generation amount does not change.
[0037]
However, in actuality, the pressurizing means 6 by the hydraulic cylinder connected to the power source 8 and the support means 7 by the pedestal block 7 a are connected in series with the two heating elements 9 and 10. Accordingly, as the resistance of the heating elements 9 and 10 increases, the current i flowing through the whole decreases, and as a result, i ₁ R ₁ (R ₁ is the resistance value of the pressurizing means 6) and i ₂ R ₂ (R ₂ is the resistance value of the support means 7) The amount of heat generated in the pressurizing means 6 portion and the amount of heat generated in the support means 7 portion are reduced.
[0038]
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, the amount of heat generated by the heating elements 9 and 10 can be increased by using the heating elements 9 and 10 of the present embodiment rather than using the general heating elements 4 and 5 shown in FIGS. It can be done.
[0039]
Further, since each of the heating elements 9 and 10 has a structure in which the block bodies 12 as shown in FIG. 2 are stacked in multiple stages, a contact resistance is generated between the overlapping block bodies 12, and the contact resistance is further increased by this contact resistance. The electrical resistance increases and the amount of heat generation can be further increased.
[0040]
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.
[0041]
The heat from the conductor portions 9a and 10a of the heating elements 9 and 10 is dispersed in the radial direction by the spacers 11, so that the powder 1 is uniformly heated.
[0042]
3 and 4 are schematic configuration diagrams of an electric heating type pressure sintering apparatus according to a second embodiment of the present invention.
[0043]
Also in this embodiment, the heating elements 9 and 10 both have conductor portions 9a and 10a and insulator portions 9b and 10b, and have a laminated structure in which multistage block bodies 13 are laminated in the axial direction. ing. However, in the present embodiment, the insulator portions 9b and 10b have a depth smaller than the thickness of the conductor portions 9a and 10a, leaving the periphery on the upper surface (or the lower surface or both upper and lower surfaces) of the cylindrical conductor portions 9a and 10a. The structure is filled.
[0044]
3 and 4 also, the conduction in the conductor portions 9a and 10a is limited mainly to the peripheral portion by the insulator portions 9b and 10b, and the contact resistance between the block bodies 13 is increased. Thus, the same effect as that of the first embodiment can be obtained.
[0045]
5 and 6 show an example of a heating element according to the third embodiment of the present invention. In FIGS. 5 and 6, the heating elements 9 and 10 include a cylindrical insulator portion 14 and one or more rod-like conductor portions parallel to the axis of the insulator portion 14 inside the insulator portion 14. 15.
[0046]
In the configuration shown in FIGS. 5 and 6, even if the overall diameters of the heating elements 9 and 10 are large, heat is actually generated by adjusting the diameter of the conductor 15 or adjusting the number of conductors 15 installed. The horizontal cross-sectional area of the conductor portion 15 can be reduced to increase the amount of heat generation, and the plurality of conductor portions 15 can perform heating dispersed in the horizontal direction, so that the powder 1 can be uniformly heated.
[0047]
FIG. 7 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to a fourth embodiment of the present invention. In FIG. 7, a plurality of molds 3 each having a molding space 2 for pressure-molding the powder 1 are provided so that the molding spaces 2 are in a straight line, and are fitted in the molding spaces 2 of the respective molds 3. 1 to 6 show a case where a plurality of (three or more) heating elements 9 and 10 as shown in FIGS. 1 to 6 are provided.
[0048]
In the configuration shown in FIG. 7, a plurality of pressure-sintered bodies can be manufactured simultaneously by pressing one pressing means 6 using a plurality of molds 3.
[0049]
The present invention is not limited to the above-described embodiment. In the illustrated example, the case where the pressure is applied in the vertical direction is shown. However, the pressure may be applied in the horizontal direction, and other aspects of the present invention. Of course, various changes can be made without departing from the scope of the invention.
[0050]
【The invention's effect】
As described above, according to the present invention, the heating element fitted so as to face the molding space inside the mold is constituted by the conductor part and the insulator part, and the block bodies are laminated in a plurality of stages. Since the structure is adopted, it is possible to increase the resistance of the heating element and increase the heat generation amount while suppressing the surface pressure against the press load by increasing the diameter of the entire heating element. Therefore, even if it is a big pressure sintered body, there exists an effect which can provide the electric heating type pressure sintering apparatus which can be produced reliably and efficiently.
[0051]
Each block of the heating element, or a multi-layer structure by an insulating body concentrically arranged electrical conductors section, also leaving a cylindrical conductor portion, a peripheral circular surface of the conductive portion The shape having the insulator portion filled with a depth smaller than the thickness of the conductor portion has an effect that the powder can be heated at a substantially uniform temperature in the circumferential direction.
[0052]
Furthermore, if each heating element is formed of a cylindrical insulator part and a plurality of conductor parts parallel to the axis of the insulator part inside the insulator part, the diameter of the entire heating element is large. The horizontal cross-sectional area of the conductor portion that actually generates heat can be set small, and furthermore, since the heating can be distributed in the horizontal direction, there is an effect that the powder can be uniformly heated.
[0053]
Also, a mold having a molding space for pressure-forming the powder inside is provided in a plurality of stages so that the molding space is in a straight line, and a plurality of heating elements are fitted to the molding space inside each mold. When provided, there is an effect that a plurality of pressure sintered bodies can be manufactured at the same time.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to a first embodiment of the present invention.
2 is a perspective view showing a shape of a block body in FIG. 1. FIG.
FIG. 3 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to a second embodiment of the present invention.
4 is a perspective view showing a shape of a block body in FIG. 3. FIG.
FIG. 5 is a plan view showing an example of a heating element according to a third embodiment of the present invention.
6 is a view taken along arrow VI-VI in FIG. 5;
FIG. 7 is a schematic configuration diagram of an electric heating type pressure sintering apparatus according to a fourth embodiment of the present invention.
FIG. 8 is a schematic configuration diagram of a general electric heating type pressure sintering apparatus.
9 is a perspective view of a heating element of the electric heating type pressure sintering apparatus shown in FIG. 8. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Powder 2 Molding space 3 Mold 6 Pressurization means 7 Support means 8 Power supply 9, 10 Heating body 9a, 10a Conductor part 9b, 10b Insulator part 12 Block body 13 Block body

Claims (5)

A mold having a molding space for pressure-molding the powder therein, a heating element fitted so as to face the molding space inside the mold, a support means for supporting the mold and one heating element, and the other In an energization heating type pressure sintering apparatus provided with a pressurizing means for applying pressure to the heat generating element, and a power source connected to the pressurizing means and the supporting means, each heat generating element is a conductor part made of semi-graphite And an insulating part having a larger electric resistance than the conductor part, and each heating element is composed of a block body laminated in a plurality of stages, and is heated by electric heating type pressure sintering apparatus. Each block of the heating element, electric heating type pressure sintering apparatus according to claim 1, characterized in that it has a multilayer structure by the insulation body conductive portion arranged concentrically.   Each block body of the heating element has a cylindrical conductor portion and an insulator portion filled with a depth smaller than the thickness of the conductor portion, leaving a periphery on the circular surface of the conductor portion. The energization heating type pressure sintering apparatus according to claim 1. A mold having a molding space for pressure-molding the powder therein, a heating element fitted so as to face the molding space inside the mold, a support means for supporting the mold and one heating element, and the other In an energization heating type pressure sintering apparatus provided with a pressurizing means for applying pressure to the heat generating element, and a power source connected to the pressurizing means and the supporting means, each heat generating element is a conductor part made of semi-graphite And an insulator portion having an electric resistance larger than that of the conductor portion, and each heating element includes a columnar insulator portion and an inner portion of the insulator portion that is parallel to the axis of the insulator portion. An electric heating type pressure sintering apparatus characterized by having one or more electric conductor parts.   A plurality of molds having a molding space for pressure-forming powder inside are provided so that the molding space is in a straight line, and three or more heating elements are provided so as to fit in each molding space of each mold. The electric heating type pressure sintering apparatus according to claim 1, 2, 3, or 4.

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