JP6762732B2 - Multi-axis current sintering equipment - Google Patents

Description

The present invention relates to an energization sintering device that energizes and sinters a powder material while applying pressure.

Conventionally, there are a uniaxial energizing sintering apparatus and a multiaxial energizing sintering apparatus as an energizing sintering apparatus that energizes and sintered a powder material while applying pressure.

In the uniaxial current-carrying sintering apparatus 200 shown in FIG. 8, spacers 211 and 212 and upper punches 213 are arranged above and spacers 221 and 21 below the powder material placed in the molding die 280 in the vacuum vessel 270. The 222 and the lower punch 223 are arranged and pressurized and energized by the pressurizing and energizing shafts 210 and 220 in the vertical direction to generate the sintered body 290. Since the uniaxial energization sintering device uses the same axis for pressurization and energization, the temperature distribution in the radial direction (horizontal direction) of the sintered portion tends to be non-uniform. In order to improve the drawback, the multi-axis energization sintering device is a device in which the pressurizing shaft and the energizing shaft are separated.

The multi-axis current-carrying sintering apparatus 100 shown in FIG. 9 pressurizes the powder material contained in the molding die 80 in the vacuum vessel 70 by the vertical pressure shafts 10 and 20, and the horizontal current-carrying shaft (A). ) 30, 40 and the energizing shaft (B) 50, 60 are energized. Regarding the method of energizing with an energizing shaft, Patent Document 1 disposes a plurality of sets of electrodes in a pair of two around the side surface of a tubular mold for accommodating a powder material under pressure. Further, an invention relating to a multi-axis current-carrying sintering apparatus in which heat is applied to a powder material while alternately switching energization to a pair of electrodes of each set is described.

Here, the heat insulating structure in the multi-axis current-carrying sintering apparatus will be described. 10 and 11 are diagrams showing a heat insulating structure in a conventional multi-axis electric current sintering apparatus. Regarding the materials of the constituent members shown below, steel is used for the pressure shaft, graphite is used for the molding die and the spacer, and glass fiber and resin are used for the heat insulating material.

In the heat insulating structure 103 shown in FIG. 10, the spacers 12, 13, 14 and the upper punch 15 are arranged above the powder material in the molding die 80, and the spacers 22, 23, 24 and the lower punch 25 are arranged below. It is arranged, pressurized by the pressure shafts 10 and 20 in the vertical direction, and energized by the energizing shaft in the horizontal direction to generate the sintered body 90. Water cooling portions 11 and 21 are provided on the pressure shafts 10 and 20 in the vertical direction, respectively, so as to cool the pressure shaft while supplying water.

On the other hand, the heat insulating structure 104 shown in FIG. 11 has a heat insulating material 16 between the pressure shaft 10 and the spacer 12 and a heat insulating material 26 between the pressure shaft 20 and the spacer 22 with respect to the heat insulating structure 103. Each is added.

The only difference between the heat insulating structure 103 and the heat insulating structure 104 is the presence or absence of the heat insulating materials 16 and 26, but there is a large difference in usage. In the case of the heat insulating structure 103, the heat escapes to the cooling water of the pressure shaft is large, and the disadvantage is that a large amount of electric power is required for operation at high temperature. Since no heat insulating material is inserted, the pressure shaft Displacement ≒ Dimensional change of the sintered material, and the advantage is that the sintering density and dimensional control during sintering are easy. Therefore, it is used for the production of sintered bodies that can be sintered at a relatively low temperature and have strict requirements for dimensional accuracy.

On the other hand, in the case of the heat insulating structure 104, there is an advantage that electric power can be saved even in operation under high temperature by inserting the heat insulating material, and since there is an elastic change and plastic deformation of the heat insulating material, the sintered body density and the sintered size are controlled. The disadvantage is that it is difficult. Therefore, it is used for manufacturing a sintered body that requires sintering at a relatively high temperature and whose dimensional accuracy is not strict.

Patent No. 4226674

FIG. 12 shows how heat is generated by energization and how heat escapes in the case of the conventional heat insulating structure 103. First, it is considered that the heat generation of the graphite type during energization sintering includes Joule heat (reference numeral 6) due to the electrical resistance of the graphite type and heat generation (reference numerals 7 and 8) due to the contact resistance between the energization shaft and the graphite type. Further, it is considered that the heat escapes to the pressurizing shaft side and to the energizing shaft side, and partially becomes radiant heat to escape. Therefore, in the multi-axis current-carrying sintering apparatus for high-temperature operation, a heat insulating material is provided between the pressurizing shaft and the spacer to suppress heat escape to the pressurizing shaft side. Therefore, it is required to further suppress the escape of heat to the pressurizing shaft side.

The present invention solves the above-mentioned conventional problems, suppresses heat escape to the pressure shaft side, enables operation at a higher temperature, makes the temperature inside the molding mold uniform, and saves energy. It provides a possible multi-axis energization sintering apparatus.

In order to solve the above problems, the multi-axis energization type sintering apparatus of the present invention includes a vertical pressurizing shaft and a horizontal energizing shaft, and pressurizes the powder material in the molding die by the pressurizing shaft. However, it is an energization sintering device that energizes and sinters by the energization shaft, and is characterized in that a cavity for heat insulation is provided at the tip of the pressurization shaft.

Further, it is preferable that a heat insulating material is provided between the pressure shaft and the molding die.

Further, it is preferable to supply cooling water into the cavity.

Further, preferably, the supply amount of the cooling water is adjusted according to the temperature of the tip end portion of the pressurizing shaft.

The current-carrying sintering apparatus of the present invention includes a pressure shaft in the vertical direction and a current-carrying shaft in the horizontal direction, so that the powder material in the molding die is pressed by the pressure shaft and energized by the current-carrying shaft for sintering. It has become. Then, a cavity for heat insulation is provided at the tip of the pressurizing shaft. Therefore, it is possible to provide a cavity for heat insulation in a portion close to the molding die and suppress heat escape from the molding die to the pressure shaft side. As a result, it is possible to operate at a higher temperature, and it is also possible to make the temperature inside the molding mold uniform and save energy.

Further, when a heat insulating material is provided between the pressurizing shaft and the molding die, heat escape from the molding die to the pressurizing shaft side can be further suppressed.

Further, when the cooling water is supplied into the cavity, the heat insulating effect can be enhanced by water cooling.

Further, when the supply amount of the cooling water is adjusted according to the temperature of the tip portion of the pressurizing shaft, the heat escape from the molding die to the pressurizing shaft side can be suppressed while being finely controlled.

As described above, according to the multi-axis energization sintering apparatus of the present invention, it is possible to operate at a higher temperature by suppressing heat escape to the pressure shaft side, and to make the temperature inside the molding mold uniform and save energy. Can be converted.

It is a figure which shows the heat insulation structure of the multi-axis electric current sintering apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the heat insulation structure of the multi-axis electric current sintering apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the temperature measurement position in the mold in an Example. It is a graph which shows the temperature rise curve in the mold in an Example. It is a graph which shows the temperature rise curve in the mold in the comparative example. It is a graph which shows the estimated temperature gradient. It is a graph which shows the electric power used in an Example and a comparative example. It is a block diagram of the uniaxial electric current sintering apparatus. It is a block diagram of the multi-axis electric current sintering apparatus. It is a figure which shows the heat insulation structure of the multi-axis electric current sintering apparatus which concerns on the prior art. It is a figure which shows the heat insulation structure of the multi-axis electric current sintering apparatus which concerns on the prior art. It is a figure which showed the heat generation by energization and the way of heat escape. It is a figure which shows the water cooling structure of a pressure shaft.

Next, the multi-axis current-carrying sintering apparatus according to the embodiment of the present invention will be described with reference to FIGS. 1 to 7 and 13. The overall configuration of the multi-axis energization sintering apparatus according to the present embodiment is the same as that of the multi-axis energization sintering apparatus 100 shown in FIG. 9 described as a conventional example, and the powder contained in the molding die 80 in the vacuum vessel 70. The body material is pressurized by the vertical pressurizing shafts 10 and 20, and is energized by the horizontal energizing shafts 30 and 40 and the energizing shafts 50 and 60. Then, the following two embodiments will be described as the heat insulating structure of the multi-axis energization sintering device 100. Regarding the materials of the constituent members shown below, steel is used for the pressure shaft, graphite is used for the molding die and the spacer, and glass fiber and resin are used for the heat insulating material.

(Embodiment 1)
In the heat insulating structure 101 shown in FIG. 1, the spacers 12, 13, 14 and the upper punch 15 are arranged above the powder material in the molding die 80, and the spacers 22, 23, 24 and the lower punch 25 are arranged below. It is arranged, pressurized by the pressure-carrying shafts 10 and 20 in the vertical direction, and energized by the power-carrying shaft in the horizontal direction to generate the sintered body 90. Water cooling portions 11 and 21 are provided on the main bodies of the pressure shafts 10 and 20 in the vertical direction, respectively, so as to cool the pressure shaft while supplying water. Further, a heat insulating material 16 is inserted between the pressure shaft 10 and the spacer 12, and a heat insulating material 26 is inserted between the pressure shaft 20 and the spacer 22.

Next, in the first embodiment, the cavity 19 is formed in the tip portion 18 (the portion on the molding mold 80 side) of the pressure shaft 10. Similarly, a cavity 29 is formed in the tip 28 (the portion on the molding mold 80 side) of the pressure shaft 20. Cooling water is supplied to the cavities 19 and 29 from the outside. The supplied cooling water is heated as the temperature of the pressurizing shafts 10 and 20 rises, and is discharged to the outside as high-temperature water or steam. The cooling water to the cavities 19 and 29 may be supplied in a circulating manner.

In this way, by providing the cavities 19 and 29 for heat insulation in the portion close to the molding die 80 and supplying the cooling water, it is possible to suppress the escape of heat from the molding die to the pressure shaft side.

Further, the supply amount of the cooling water may be adjusted according to the temperature of the tips 18 and 28 of the pressurizing shafts 10 and 20. Thereby, the heat escape from the molding die 80 to the pressure shafts 10 and 20 can be finely controlled.

Here, with reference to FIG. 13, an example of a method of adjusting the supply amount when the cooling water is supplied to the cavity at the tip of the pressurizing shaft will be described. FIG. 13 describes the pressurizing shaft 10, but the same applies to the pressurizing shaft 20.

A water cooling portion 11 is provided at the base end portion (main body portion) of the pressurizing shaft 10. A main body water supply pipe 111 and a main body drainage pipe 112 are connected to the water cooling unit 11 so as to cool the main body while circulating cooling water.

A cavity 19 is provided in the tip 18 of the pressurizing shaft 10. A tip water supply pipe 114 and a tip drain pipe 115 are connected to the cavity 19. Further, a check valve 113 and a solenoid valve 119 are provided on the upstream side of the tip water supply pipe 114, and a check valve 116 is provided on the downstream side of the tip drain pipe 115. The check valve 113 enables passage from the upstream side to the cavity 19 side and prevents backflow from the cavity 19 side. The check valve 116 allows passage from the cavity 19 side to the downstream side, and also prevents backflow from the downstream side. The solenoid valve 119 is opened and closed as necessary in order to adjust the amount of cooling water supplied to the cavity 19.

A thermocouple 117 is attached to the tip 18 of the pressurizing shaft 10. The temperature of the tip 18 of the pressurizing shaft is measured. Further, the water cooling portion 11 and the cavity 19 are separated by a partition wall 118.

When energization sintering is started, the temperature of the tip 18 of the pressurizing shaft 10 rises as the temperature of the molding die rises. Therefore, based on the temperature measurement by the thermocouple 117, when the temperature of the tip portion 18 becomes higher than the predetermined temperature, the solenoid valve 119 is opened to supply the cooling water to the cavity 19. Further, when the tip portion 18 is cooled and becomes lower than a predetermined temperature, the solenoid valve 119 is closed to stop the supply of cooling water to the cavity 19. The cooling water supplied to the cavity 19 is discharged from the tip drain pipe 115 in the state of high temperature water or steam depending on the temperature of the tip 18. By the action of the check valves 113 and 116, the high-temperature water or steam in the cavity 19 is discharged to the downstream side without flowing back to the upstream side.

By adjusting the supply amount of the cooling water in this way, the temperature of the tip portion 18 of the pressurizing shaft 10 can be kept within a certain range. If the tip of the pressurizing shaft 10 becomes too hot, damage such as cracking will occur, which is not preferable. On the other hand, if it is cooled too much, heat escapes to the pressurizing shaft 10 side more often. Therefore, by controlling the temperature of the tip portion 18 to be kept within a certain range, it is possible to suppress damage to the tip portion 18 and prevent heat from escaping to the pressure shaft 10 side.

(Embodiment 2)
In the heat insulating structure 102 shown in FIG. 2, the spacers 12, 13, 14 and the upper punch 15 are arranged above the powder material in the molding die 80, and the spacers 22, 23, 24 and the lower punch 25 are arranged below. It is arranged, pressurized by the pressure-carrying shafts 10 and 20 in the vertical direction, and energized by the power-carrying shaft in the horizontal direction to generate the sintered body 90. Water cooling portions 11 and 21 are provided on the main bodies of the pressure shafts 10 and 20 in the vertical direction, respectively, so as to cool the pressure shaft while supplying water. Further, unlike the first embodiment, two heat insulating materials 16 and 17 are provided between the pressure shaft 10 and the spacer 12, and two heat insulating materials 26 and 27 are provided between the pressure shaft 20 and the spacer 22. Each is inserted.

Next, in the second embodiment, the cavity 19 is formed in the tip portion 18 (the portion on the molding mold 80 side) of the pressure shaft 10. Similarly, a cavity 29 is formed in the tip 28 (the portion on the molding mold 80 side) of the pressure shaft 20. However, unlike the first embodiment, the cavities 19 and 29 are not supplied with cooling water from the outside and are used as a heat insulating space.

In this way, by providing the heat insulating cavities 19 and 29 in the portion close to the molding die 80 to form a heat insulating space, it is possible to suppress heat escape from the molding die to the pressure shaft side.

With respect to the heat insulating structure 101 and the heat insulating structure 102, the presence / absence / number of heat insulating materials and the presence / absence of cooling water supply to the cavity can be appropriately combined. For example, the heat insulating structure 101 may be "without heat insulating material" or "without supplying cooling water to the cavity". Further, the heat insulating structure 102 may be "without heat insulating material" or "with cooling water supplied to the cavity".

The current-carrying sintering apparatus according to the present embodiment includes the pressure shafts 10 and 20 in the vertical direction and the current-carrying shafts in the horizontal direction, and energizes the powder material in the molding die 80 while pressurizing the pressure shafts 10 and 20. It is designed to be energized by a shaft and sintered. Then, cavities 19 and 29 for heat insulation are provided in the tips 18 and 28 of the pressure shafts 10 and 20. Therefore, the heat insulating cavities 19 and 29 can be provided in the portion close to the molding die 80 to suppress heat escape from the molding die 80 to the pressure shafts 10 and 20. As a result, it is possible to operate at a higher temperature, and it is also possible to make the temperature inside the molding mold uniform and save energy.

Further, when the heat insulating materials 16 and 17 are provided between the pressurizing shafts 10 and 20 and the forming mold 80, it is possible to further suppress heat escape from the forming die 80 to the pressurizing shafts 10 and 20 side. it can.

Further, when the cooling water is supplied into the cavities 19 and 29, the heat insulating effect can be enhanced by water cooling.

Further, when the amount of cooling water supplied is adjusted according to the temperature of the tips 18 and 28 of the pressurizing shafts 10 and 20, the heat escape from the molding die 80 to the pressurizing shafts 10 and 20 is finely divided. It can be suppressed while controlling.

As described above, according to the multi-axis energizing sintering apparatus according to the present embodiment, it is possible to operate at a higher temperature by suppressing heat escape to the pressure shafts 10 and 20 side, and the temperature inside the molding die. It is possible to make the temperature uniform and save energy.

The effect of the heat insulating structure in the multi-axis current-carrying sintering apparatus according to the present embodiment was verified as follows. FIG. 3 is a diagram showing a temperature measurement position in the mold in the embodiment. 1 to 5 were set as the temperature measurement positions. The temperature rise was controlled by a control logic in which the central part of the mold reached 800 ° C., and the power supply voltage was constant at 4 V.

The heat insulating structure 102 shown in FIG. 2 was selected as an example, and the heat insulating structure 104 shown in FIG. 11 was selected as a comparative example. The pressing force of the energizing shaft was set to 0.95 MPa in Example and 0.55 MPa in Comparative Example. This is to reduce the heat generated by the contact resistance between the energizing shaft and the graphite mold (reference numerals 7 and 8 in FIG. 12) by increasing the pressing force of the energizing shaft, and to reduce the Joule heat of the mold (reference numeral 6 in FIG. 12). This is because I thought that the outbreak could be increased. Therefore, in this embodiment, the temperature inside the mold is increased by the combined effect of improving the heat insulating effect by increasing the number of heat insulating materials and the cavity at the tip of the pressure shaft (without cooling water) and reducing the contact resistance by increasing the pressing force of the current-carrying shaft. It measures the homogenization, energy saving effect, and cycle time shortening effect.

(Temperature distribution in graphite mold)
FIG. 4 is a graph showing a temperature rise curve in the mold in the example. Further, FIG. 5 is a graph showing a temperature rise curve in the mold in the comparative example. According to FIGS. 4 and 5, the temperature difference between the temperature measurement positions 1 to 4 is less than 2 ° C. (about 1.5 ° C.) in the example and less than 4 ° C. (about 3 ° C.) in the comparative example when reaching 800 ° C. It is 0.7 ° C). In the comparative example, the temperature distribution in the mold is considerably uniform, but in the example, it is more uniform. Therefore, taking advantage of the structure in which the pressurizing shaft and the energizing shaft are separated, which is a feature of the multi-axis energizing sintering device, the pressurizing shaft is insulated and the energizing shaft is increased in pressure to increase the pressure inside the mold. It was verified that the temperature distribution can be further improved.

Here, the phenomenon that the temperature distribution in the mold becomes uniform will be considered. FIG. 6 is a graph showing the estimated temperature gradients of the graphite type and the graphite spacer. The graph corresponds to the heat insulating structure 103 shown in FIG. 10, the heat insulating structure 104 (comparative example) shown in FIG. 11, and the heat insulating structure 102 (example) shown in FIG. 2, in order from the top. The black circles at both ends of the graph are measured values, and the curves are estimated values.

As shown in FIG. 6, it is presumed that the temperature gradient between the graphite mold (molding mold) and the graphite spacer is gentle by weaving a heat insulating structure at the tip of the pressure shaft. Therefore, it is considered that the heat escape from the sintered body is small, the temperature gradient inside the sintered body becomes gentle, and the temperature tends to be uniform in the end.

(Energy saving effect and shortened heating time)
FIG. 7 is a graph showing the power consumption in Examples and Comparative Examples. FIG. 7 (a) shows an embodiment, and FIG. 7 (b) shows a comparative example. As shown in FIG. 7, the total power consumption was 14.7 KWh in the example and 17.2 KWh in the comparative example, and there was an energy saving effect of about 14.5%. The heating time was 29 minutes in the example and 36 minutes in the comparative example, and the heating time was shortened by about 19%.

In this way, the heat insulating structure of the example was able to verify the effects of making the temperature distribution in the mold of the multi-axis current-carrying sintering device uniform, saving energy, and shortening the cycle time.

Although the multi-axis current-carrying sintering apparatus according to the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various other modifications can be made.

10 Pressurized shaft 11 Water cooling part 12 Spacer 13 Spacer 14 Spacer 15 Upper punch 16 Insulation material 17 Insulation material 18 Pressurization shaft tip 19 Cavity 20 Pressurization shaft 21 Water cooling part 22 Spacer 23 Spacer 24 Spacer 25 Lower punch 26 Insulation material 27 Insulation 28 Pressurized shaft tip 29 Cavity 30 Energizing shaft 40 Energizing shaft 50 Energizing shaft 60 Energizing shaft 70 Vacuum container 80 Mold 90 Sintered body 100 Multi-axis energizing sintering device 101 Insulation structure 102 Insulation structure 103 Insulation structure 104 Insulation Structure 111 Main body water supply pipe 112 Main body drain pipe 113 Check valve 114 Tip water supply pipe 115 Tip drain pipe 116 Check valve 117 Thermocouple 118 Partition 119 Electromagnetic valve 200 Uniaxial current sintering device 210 Pressurized current shaft 211 Spacer 212 Spacer 213 Upper punch 220 Pressurized current shaft 221 Spacer 222 Spacer 223 Lower punch 270 Vacuum container 280 Mold 290 Sintered body

Claims (4)

An energization sintering device having a vertical pressurizing shaft and a horizontal energizing shaft, which is capable of sintering by energizing the powder material in the molding die by the energizing shaft while pressurizing the powder material by the pressurizing shaft.
The pressurizing shaft is composed of a main body portion having a water cooling portion that cools the pressurizing shaft while supplying water, and a tip portion having a cavity separated from the water cooling portion.
A multi-axis current-carrying sintering device, characterized in that the cavity is a cavity for heat insulation that suppresses heat escape from the molding die to the pressure shaft side . The multi-axis energization type sintering apparatus according to claim 1, wherein a heat insulating material is provided between the pressure shaft and the molding die. The multi-axis energization type sintering apparatus according to claim 1 or 2, wherein cooling water is supplied into the cavity. The multi-axis energization type sintering apparatus according to claim 3, wherein the supply amount of the cooling water is adjusted according to the temperature of the tip end portion of the pressurizing shaft.