JP2007023365A - Method for producing electrode for discharge surface treatment, and production device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an electrode for discharge surface treatment capable of producing an electrode for discharge surface treatment having desired density and electric conductivity with high precision. <P>SOLUTION: The upper part of the device is provided with a hydraulic press mechanism part 1. Powder 11 having electric conductivity is packed into a press fixture, a load is applied to the press fixture to a prescribed thrusting distance, so as to cause pressurization, simultaneously, the powder is heated and sintered, thereafter, voltage is applied to the powder, and, based on a value of current flowing through the powder, the pressurization and sintering are stopped, so as to produce an electrode for discharge surface treatment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the manufacture of an electrode used in a discharge surface treatment technique in which a pulsed discharge is generated between a conductive electrode and a substrate, and the electrode material is coated on the surface of the substrate by the pulsed discharge energy. It is about the method.

  There is known a discharge surface treatment method in which a pulsed discharge is generated between an electrode made of metal or conductive ceramic and a substrate, and the electrode material is coated on the surface of the substrate by the discharge energy. In this discharge surface treatment method, submerged discharge is generally used as in the electric discharge machining treatment. However, it is necessary to concentrate the discharge energy on the tip portion of the electrode so that the tip portion has a high temperature. Therefore, it is necessary to lower the thermal conductivity of the electrode, and a green compact obtained by pressing and hardening a metal or conductive ceramic powder has been used as the electrode (for example, see Patent Document 1).

  However, although an electrode made of such a green compact is easy to manufacture, there is a problem that it is difficult to maintain the shape, and part of the electrode collapses during the discharge surface treatment. For this improvement, a green compact obtained by pressing a metal or conductive ceramic powder as an electrode to be sintered at a temperature below the sintering temperature is used as a sintered body, and this sintered body is used as an electrode. There has been disclosed a technique that eliminates the tendency of the shape to collapse by use (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 5-148615 (page 3) JP-A-8-300287 (page 3)

  However, the conventional method of compacting a green compact by pressing a metal or conductive ceramic powder into a porous sintered body by pre-sintering at a temperature lower than the sintering temperature is stronger than the green compact. However, it is difficult to accurately control the density and electrical conductivity of the electrodes that affect the stability of film formation in the discharge surface treatment. That is, there is a problem that variations in the density and electrical conductivity of the produced electrodes occur only by controlling the heat treatment temperature and heat treatment time for pre-sintering.

  The present invention has been made to solve the above-described problems, and manufacture of an electrode for discharge surface treatment that can accurately manufacture an electrode for discharge surface treatment having a desired density and electrical conductivity. It aims to provide a method.

  In the method for manufacturing the electrode for discharge surface treatment according to the present invention, the press jig is filled with conductive powder, and the press jig is heated by applying a load to a predetermined indentation distance and simultaneously heating the powder. After sintering, a voltage is applied to the powder, and pressurization and sintering are stopped based on the current value flowing through the powder to produce an electrode for discharge surface treatment.

  This invention controls the density of the electrodes by applying a load to the pressing jig up to a predetermined indentation distance and pressurizing it, and when the powder is heated and sintered, a voltage is applied to the powder to reduce the resistance value of the powder. Since the electrical conductivity of the electrode is controlled by stopping the sintering when a predetermined value is reached, the density and electrical conductivity of the electrode can be controlled independently, and the desired density and electrical conductivity can be controlled. Can be manufactured with high accuracy.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an apparatus for manufacturing an electrode for discharge surface treatment according to Embodiment 1 for carrying out the present invention. In FIG. 1, a hydraulic press mechanism 1 is provided at the upper part of the apparatus, and a compression force can be applied to a metal upper press bar 4 and lower press bar 5 via a frame 2 and a support 3. Has been. The pushing distance of the upper press bar 4 can be monitored with a displacement meter 6. The chamber 7 can be hermetically maintained. When a metal material that is easily oxidized is sintered, the chamber 7 can be evacuated or filled with an inert gas or hydrogen gas. It has become. As the heater 8, for example, a resistance heater made of carbon can be used. The heater 8 is heated by energizing the heater 8 from the heater power source 9, and the temperature of the press die 10 can be raised by the radiant heat. The press mold 10 is filled with powder 11 of an electrode material, and the press mold 10 is provided with a thermocouple so that the temperature of the powder 11 can be measured. A resistance monitor 12 is electrically connected between the upper press bar 4 and the lower press bar 5 that are in contact with the upper and lower sides of the press die 10. The control unit 13 is electrically connected to the hydraulic press mechanism 1, the displacement meter 6, the heater power supply 9, the resistance monitor 12, etc., and receives information from each device and controls the operation of each device. It is configured to be able to.

  FIG. 2 is a schematic diagram showing a central section of the press die 10 in the present embodiment. The space surrounded by the die 14, the upper punch bar 4a and the lower punch bar 5a, which is a part of the press die 10, is filled with the powder 11, and the upper punch bar 4a and the lower punch bar 5a are respectively connected to the upper press bar 4 and Pressure is applied by the hydraulic press mechanism 1 through the lower press bar 5. As a result, the powder 11 is pressed by the upper punch bar 4a and the lower punch bar 5a. The upper press bar 4 and the lower press bar 5 are made of conductive metal, the upper punch bar 4a and the lower punch bar 5a are made of conductive carbon, and the die 14 is made of electrically insulating alumina. Yes. For this reason, when a voltage is applied between the upper punch bar 4a and the lower punch bar 5a from the resistance monitor 12 via the upper press bar 4 and the lower press bar 5, the powder 11 becomes an energization route. The current value flowing through the powder 11 can be monitored as a resistance value. That is, the direction in which the voltage is applied to the powder and the direction in which the load is applied to the press jig are the same.

Next, the manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. A 55Co-30Cr-12W-3Ni alloy powder adjusted to an average particle diameter of about 1.1 mm by jet mill grinding is filled into a press die 10 composed of a die 14 having an inner diameter of 10 mm. Note that 55Co-30Cr-12W-3Ni represents an alloy having a composition ratio of 55 wt% Co, 30 wt% Cr, 12 wt% W, and 3 wt% Ni. This alloy is also called stellite and is often used as an abrasion resistant material. The press die 10 filled with the powder 11 is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and the displacement distance is monitored by the displacement meter 6 until the density of the powder 11 in the press die 10 becomes 3.0 g / cm ^3. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a heating rate of 10 ° C./min. When the powder 11 reaches 650 ° C., the heating is stopped to 650 ° C. To maintain. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 6.0 × 10 ⁻² Ω. In addition, when the resistance value of the resistance monitor 12 indicates 6.0 × 10 ⁻² Ω, it is when the resistance value of the powder 11 becomes the design value of 4.5 × 10 ⁻² Ω using a standard sample in advance. The cause of this difference is due to the contact resistance between the upper and lower punch bars 4a and 5a and the powder 11.

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of 10 mm and a height of 20 mm, a density of 2.9 g / cm ³ , and a resistance value of 4.6 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment. When the resistance value is high, the charge time becomes long when used as an electrode for discharge surface treatment, and it becomes impossible to follow the cycle of pulse discharge. On the other hand, when the resistance value is low, sintering of the powder particles is advanced, so that the thermal conductivity of the electrode becomes high and the tip portion of the electrode may not be sufficiently heated. Therefore, the resistance value of the electrode needs to be in a limited range, and is preferably in the range of 10 ⁻² Ω in this embodiment.

Furthermore, when 10 discharge surface treatment electrodes were produced under the same production conditions as described above, the 10 characteristic variations were ± 0.1 g / cm ^{3 in} density and ± 0.3 × 10 ⁻² Ω in resistance. And excellent uniformity was obtained.

As a comparison, in order to produce a discharge surface treatment electrode by a conventional manufacturing method, the discharge surface treatment electrode was not monitored for the resistance value of the powder and the heating time of the heater was kept constant with the same apparatus as this embodiment. Ten pieces were produced. In this case, the ten characteristic variations were ± 0.3 g / cm ^{3 in} density and ± 0.8 × 10 ⁻² Ω in resistance value, and the resistance value variation was particularly large. It was.

  In this embodiment, as a judgment when stopping heating, the resistance value of the powder is measured using a resistance monitor, but the current value flowing through the powder is measured using a current monitor instead of the resistance monitor. You may measure directly. In this case as well, it is necessary to examine in advance the current value flowing through the powder and the current value measured by the current monitor using a standard sample. The cause of this difference is due to the contact resistance between the upper and lower punch bars 4a and 5a and the powder 11 as in the case of monitoring the resistance value.

  In this embodiment, the upper and lower punch rods made of carbon and the die made of alumina are used. However, depending on the heating temperature for sintering, metal may be used as the upper and lower punch rods. Also, silica-based or nitride-based ceramics may be used. In the present embodiment, an alumina die having excellent electrical insulation is used, but the die does not necessarily have high electrical insulation, and a voltage is applied between the electrically conductive upper punch bar and lower punch bar. It is only necessary that the current flowing through the powder when a voltage is applied has a resistance that can be measured by a resistance monitor.

  In addition, as a powder filling method, the powder is directly filled in the press mold. However, when using a powder that becomes bulky, the powder may be inserted into the press mold after press molding to reduce the volume in advance. In this embodiment, a powder having an average particle diameter of about φ1.1 μm is used. However, if the powder has an average particle diameter of φ0.5 to 3 μm, the density and A combination with the resistance value is a preferable value.

  Furthermore, in the present embodiment, 55Co-30Cr-12W-3Ni alloy powder is used, but other cobalt-based alloys, cobalt-nickel-based alloys, etc. may be used, and the temperature of the sintering process in this case The temperature may be in the range of 0.4 to 0.8, where the melting point of the material used is 1. In order for sintering to occur at the contact portion between the metal powder particles, the mass transfer between the powder particles is necessary, and the temperature at which the mass transfer starts is about 0.4 when the melting point of the material is 1. It is. Therefore, this temperature becomes the lower limit of the temperature of the sintering process. On the other hand, when the temperature of the sintering process reaches the melting point of the material, the powder particles are melted, so the upper limit of the sintering process temperature is about 0.8 when the melting point of the material is 1.

Embodiment 2. FIG.
In the second embodiment, a discharge surface treatment electrode is produced using 72Fe-19Cr-9Ni alloy powder using the same manufacturing apparatus as in the first embodiment. This alloy is known as SUS304 and is often used as a material having excellent corrosion resistance.

The manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. The manufacturing apparatus is the same as that of the first embodiment, and will be described with reference to FIG. The 72Fe-19Cr-9Ni alloy powder is classified by the high pressure water atomization method, and the powder having an average particle diameter of φ1.4 μm is selected. The powder having the average particle diameter of φ1.4 μm is formed into a press die 10 composed of a die having an inner diameter of φ10 mm. Fill. Next, the press die 10 filled with the powder 11 is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and is pressed to the indentation distance at which the density of the powder 11 in the press die 10 becomes 4.0 g / cm ³ while monitoring the indentation distance with the displacement meter 6. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a heating rate of 10 ° C./min. When the powder 11 reaches 700 ° C., the heating is stopped to 700 ° C. To maintain. Furthermore, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 2.7 × 10 ⁻² Ω. The resistance value of the resistance monitor 12 indicates 2.7 × 10 ⁻² Ω when the resistance value of the powder 11 becomes the design value of 1.5 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of φ10 mm and a height of 20 mm, a density of 3.9 g / cm ³ , and a resistance value of 1.5 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment. Furthermore, when 10 discharge surface treatment electrodes were produced under the same production conditions as described above, the 10 characteristic variations were ± 0.1 g / cm ^{3 in} density and ± 0.2 × 10 ⁻² Ω in resistance value. And excellent uniformity was obtained. In this embodiment, since the powder classified by the high pressure atomizing method is used, there is an effect that the characteristic variation is further reduced as compared with the first embodiment.

  In the present embodiment, a powder having an average particle diameter of about φ1.4 μm is used. However, if the powder has an average particle diameter of φ0.5 to 3 μm, the density and A combination with the resistance value is a preferable value. Furthermore, in the present embodiment, 72Fe-19Cr-9Ni alloy powder is used, but other iron-based alloys or iron may be used. In this case, the temperature of the sintering process is set so that the melting point of the material used is 1. Then, the temperature may be in the range of 0.4 to 0.8.

Embodiment 3 FIG.
In the third embodiment, a discharge surface treatment electrode is produced using WC (tungsten carbide) powder, which is a conductive ceramic, using the same manufacturing apparatus as in the first embodiment.

The manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. The manufacturing apparatus is the same as that of the first embodiment, and will be described with reference to FIG. The WC powder pulverized to an average particle diameter of φ1.0 μm by jet mill pulverization is filled into a press die 10 composed of a die having an inner diameter of Φ10 mm. Next, the press mold 10 filled with the powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and is pressed to a pressing distance at which the density of the powder 11 in the press die 10 becomes 8.0 g / cm ³ while monitoring the pressing distance with the displacement meter 6. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a rate of temperature rise of 10 ° C./min. When the powder 11 reaches 1700 ° C., the temperature rise is stopped to 1700 ° C. To maintain. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 2.5 × 10 ⁻² Ω. In addition, when the resistance value of the resistance monitor 12 indicates 2.5 × 10 ⁻² Ω, it is when the resistance value of the powder 11 becomes the design value of 1.5 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of 10 mm and a height of 20 mm, a density of 7.9 g / cm ³ , and a resistance value of 1.3 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment.

  In this embodiment, WC powder is used. However, a ceramic carbide such as TiC may be used. In this case, the temperature of the sintering process is 0.7 to 0 when the melting point of the material to be used is 1. The temperature may be in the range of .95. When the material is a metal, the temperature range of the sintering process was 0.4 to 0.8 when the melting point of the material was 1, but in the case of the ceramic material used in the present embodiment, Since a higher temperature is required for sintering than metal, the temperature range is closer to the melting point.

Embodiment 4 FIG.
In the fourth embodiment, the shape of the upper punch bar 4a is changed in the same manufacturing apparatus as in the first embodiment. FIG. 3 is a schematic diagram showing a central cross section of the press die 10 in the present embodiment. In the present embodiment, an upper punch rod 15 with a collar is used instead of the upper punch rod used in the first embodiment. In this upper punch rod 15 with a collar, the cross-sectional area of the portion of the collar 16 is larger than the area of the surface in contact with the powder 11, and when the powder 11 is pressed from above with the upper punch rod 15 with a collar. The collar 16 is configured to abut against the die 14 so that the collared upper punch bar 15 does not fall any further. That is, the volume when the powder 11 is pressurized by the position of the collar 16 can be made constant. Therefore, the displacement meter used in Embodiment 1 becomes unnecessary. The upper punch bar 15 with the collar and the lower punch bar 5a are made of conductive carbon, and the die 14 which is a part of the press die 10 is made of electrically insulating alumina. For this reason, when a voltage is applied between the upper punch bar 15 with the collar and the lower punch bar 5a, the powder 11 becomes an energization route, and the resistance value of the powder 11 is measured by measuring the current of the energization route with the resistance monitor 12. Can be monitored.

Next, the manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. In the following description, the drawing number of the manufacturing apparatus will be described with reference to FIG. 1 and FIG. A 55Co-30Cr-12W-3Ni alloy powder adjusted to an average particle diameter of about 1.1 mm by jet mill grinding is filled into a press die 10 composed of a die 14 having an inner diameter of 10 mm. The press die 10 filled with this powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press rod 4 is pressurized until the flange 16 of the upper punch rod 15 with a flange contacts the die 14 via the hydraulic press mechanism 1. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a heating rate of 10 ° C./min. When the powder 11 reaches 600 ° C., the heating is stopped and 600 ° C. To maintain. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 3.5 × 10 ⁻² Ω. In addition, when the resistance value of the resistance monitor 12 indicates 3.5 × 10 ⁻² Ω, it is when the resistance value of the powder 11 becomes the design value of 2.0 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of φ10 mm and a height of 20 mm, a density of 3.0 g / cm ³ , and a resistance value of 1.9 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment. Furthermore, when 10 discharge surface treatment electrodes were produced under the same manufacturing conditions as described above, the 10 characteristic variations were ± 0.08 g / cm ^{3 in} density and ± 0.15 × 10 ⁻² Ω in resistance. And excellent uniformity was obtained. In the present embodiment, by using the upper punch rod with a collar, the height of the discharge surface treatment electrode is always constant, so that a displacement meter is unnecessary and the variation in the volume of the discharge surface treatment electrode is reduced. In particular, there is an effect of reducing variation in density.

Embodiment 5. FIG.
In the fifth embodiment, an electrode for discharge surface treatment is produced using Cu powder using the same manufacturing apparatus as in the fourth embodiment.

The manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. As in the case of the fourth embodiment, the drawing numbers of the manufacturing apparatus will be described with reference to those shown in FIGS. Cu powder classified to an average particle diameter of φ1.5 μm by a high-pressure water atomization method is filled into a press die 10 constituted by a die having an inner diameter of φ10 mm. The press die 10 filled with this powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized through the hydraulic press mechanism 1 until the flange 16 comes into contact with the die 14. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a heating rate of 20 ° C./min. When the powder 11 reaches 550 ° C., the heating is stopped and 550 ° C. To maintain. Furthermore, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 2.6 × 10 ⁻² Ω. In addition, when the resistance value of the resistance monitor 12 indicates 2.6 × 10 ⁻² Ω, it is when the resistance value of the powder 11 becomes the design value of 1.2 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of φ10 mm and a height of 20 mm, a density of 3.8 g / cm ³ , and a resistance value of 1.1 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment. Furthermore, when 10 discharge surface treatment electrodes were produced under the same production conditions as described above, the 10 characteristic variations were ± 0.09 g / cm ^{3 in} density and ± 0.3 × 10 ⁻² Ω in resistance value. And excellent uniformity was obtained.

  In the present embodiment, Cu powder is used. However, a Cu alloy containing Cu as a main component may be used. In this case, the temperature of the sintering process is 0. The temperature may be in the range of 4 to 0.8.

Embodiment 6 FIG.
FIG. 4 is a schematic diagram showing an apparatus for manufacturing a discharge surface treatment electrode according to Embodiment 6. In FIG. In FIG. 4, the hydraulic press mechanism 1, the frame 2, the support 3, the displacement meter 6, the chamber 7, and the like are the same as those in the first embodiment, but a pair of electrode rods 17 are provided on both sides of the press die 10. The resistance monitor 12 electrically connected to the pair of electrode rods 17 can measure the resistance value of the powder 11.

  FIG. 5 is a perspective view schematically showing the structure at the center of the press die 10 in the present embodiment, and FIG. 6 is a schematic diagram showing a central cross section of the press die 10. The upper punch bar 4a and the lower mold 18 are insulators made of alumina. A pair of press side plates 19 are provided on both sides of the lower mold 18 so as to sandwich the powder, and the press side plates 19 are made of carbon. A voltage is applied from the resistance monitor 12 to the pair of press side plates 19 through the pair of electrode rods 17, and the powder 11 filled between the upper punch rod 4a and the lower die 18 is energized to apply the press pressure. The resistance value of the powder 11 in a direction perpendicular to the direction to be measured can be measured. That is, the direction in which a voltage is applied to the powder and the direction in which a load is applied intersect.

Next, the manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. A 55Co-30Cr-12W-3Ni alloy powder adjusted to an average particle size of about 1.1 μm by jet milling is filled into a press die 10 having a forming area of 10 mm length × 40 mm width. The press die 10 filled with the powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and the displacement distance is monitored by the displacement meter 6 until the density of the powder 11 in the press die 10 becomes 3.0 g / cm ^3. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, the heater power source 9 is controlled to heat the heater 8 so that the powder 11 is heated at a heating rate of 10 ° C./min. When the powder 11 reaches 650 ° C., the heating is stopped to 650 ° C. To maintain. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the heating of the heater 8 is stopped when the resistance value indicated by the resistance monitor 12 becomes 2.0 × 10 ⁻² Ω. The resistance value of the resistance monitor 12 is 2.0 × 10 ⁻² Ω when the resistance value of the powder 11 is the designed value of 1.2 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a thin plate shape having a height of 5 mm, a length of 10 mm, and a width of 40 mm, a density of 2.9 g / cm ³ , and a resistance value of 1.1 × 10 ^−2. It has a characteristic value preferable as an electrode for discharge surface treatment. Furthermore, when 10 discharge surface treatment electrodes were produced under the same production conditions as described above, the 10 characteristic variations were ± 0.1 g / cm ^{3 in} density and ± 0.2 × 10 ⁻² Ω in resistance value. And excellent uniformity was obtained.

  By constructing in this way, when producing a thin plate-shaped discharge surface treatment electrode, it is possible to directly measure the resistance value in the same longitudinal direction as the energization direction when used in the discharge surface treatment apparatus, and thus further characteristics An electrode for discharge surface treatment with little variation can be produced. Further, in the case where a thin plate-like electrode for electric discharge treatment is produced by the manufacturing method described in the first embodiment, it is necessary to fill the powder in a direction in which the press pressure is applied, and the area to which the press pressure is applied is reduced. There is a risk that the pressure does not spread evenly throughout the powder. In the present embodiment, since the area to which the press pressure is applied is larger than that in the first embodiment, the uniformity is further improved.

  In this embodiment, the upper punch rod 4a made of alumina and the lower die 18 having excellent electrical insulation are used. However, these need not necessarily have high electrical insulation, and a pair of electrical conductivity is not necessary. It is sufficient that the current flowing through the powder when a voltage is applied to the press side plate 19 has a resistance that can be measured by a resistance monitor.

Embodiment 7 FIG.
FIG. 7 is a schematic diagram showing an apparatus for manufacturing a discharge surface treatment electrode according to Embodiment 7. In FIG. In FIG. 7, the hydraulic press mechanism 1, the frame 2, the support 3, the upper press bar 4, the lower press bar 5, the displacement meter 6, the chamber 7, and the like are the same as those in the first embodiment. Is different from the first embodiment. In the present embodiment, a pulse power source 20 is electrically connected between the upper press bar 4 and the lower press bar 5, and the powder 11 is supplied from the pulse power source 20 via the upper punch bar 4a and the lower punch bar 5a. It is configured such that a pulsed current is applied and the powder 11 is heated by the Joule heat. Either the upper punch bar 4a or the lower punch bar 5a is provided with a thermocouple so that the temperature of the powder 11 can be measured. The pulse power source 20 is connected to the control unit 13 and is controlled by the control unit 13 in the same manner as the hydraulic press mechanism 1, the displacement meter 6 and the resistance monitor 12. In addition, the resistance monitor 12 controls the measurement of the resistance value of the powder 11 during a blanking period of pulse energization (period in which no pulsed current is energized) in order to avoid the influence of pulse energization. .

Next, the manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. A 55Co-30Cr-12W-3Ni alloy powder adjusted to an average particle size of about φ1.1 μm by jet mill grinding is filled into a press die 10 composed of a die having an inner diameter of φ10 mm. The press die 10 filled with the powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and the displacement distance is monitored by the displacement meter 6 until the density of the powder 11 in the press die 10 becomes 3.0 g / cm ^3. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, a pulsed current is applied to the upper and lower punch rods 4a and 5a from the pulse power source 20 so that the powder 11 is heated at a temperature rising rate of 20 ° C./min. The pulsed current is controlled so that the temperature stops, and 600 ° C. is maintained. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the energization from the pulse power source 19 is stopped when the resistance value indicated by the resistance monitor 12 becomes 0.24Ω. In addition, when the resistance value of the resistance monitor 12 shows 0.24Ω, it is when the resistance value of the powder 11 becomes 0.20Ω as a design value using a standard sample in advance.

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of 10 mm and a height of 20 mm, a density of 2.9 g / cm ³ , a resistance value of 0.21Ω, and a discharge surface treatment. It has a characteristic value preferable as a working electrode. Furthermore, when 10 discharge surface treatment electrodes were produced under the same manufacturing conditions as described above, the 10 characteristic variations were ± 0.1 g / cm ^{3 in} density and ± 0.02Ω in resistance value, which was excellent. Uniformity was obtained.

  In the heating of the powder 11 by pulse energization, a pulsed current flows through the contact portion between the powder particles of the powder 11 filled in the press die 10, and this contact portion is preferentially heated by the contact resistance of the contact portion, In addition, since the oxide film at this contact portion is destroyed by pulsed electric impact, sintering of the contact portion between the powder particles is promoted even at a relatively low temperature. In the electrode for discharge surface treatment which is the object of the present invention, it is preferable that only the contact portion between the powder particles is slightly sintered, and the oxide film at the contact portion between the powder particles is removed to promote the sintering. It is a desirable condition. Further, when the powder is heated by heating the press die with the carbon heater as shown in the first embodiment, it is necessary to first increase the temperature of the press die, and it takes time to heat the powder. However, since the heating of the powder by pulse energization does not require heating of the press die, the heating time is shortened and a predetermined resistance value can be obtained in a shorter time.

  In the present embodiment, the case where the direction in which the pressing pressure is applied, the direction in which the resistance value of the powder is measured, and the direction in which the pulse energization is the same direction has been described, but as shown in the sixth embodiment, When the direction in which the pressing pressure is applied is perpendicular to the direction in which the resistance value of the powder is measured, the direction in which the pulse current is applied can be the same as the direction in which the resistance value of the powder is measured. In that case, a pulse power source may be electrically connected between the pair of electrode rods used in Embodiment 6.

  In addition, the heating temperature in the case of performing heating by pulse energization may be a temperature in the range of 0.4 to 0.8 when the melting point of the material to be used is 1, as in the first embodiment.

  Further, in the present embodiment, the indentation distance of the upper press bar is measured with a displacement meter, and the displacement of the upper press bar is stopped at the indentation distance having a predetermined density, but the collar shown in the fourth embodiment is used. The pressing distance of the upper press bar may be made constant by using the attached punch bar.

Embodiment 8 FIG.
In the eighth embodiment, a discharge surface treatment electrode is produced using 72Fe-19Cr-9Ni alloy powder using the same manufacturing apparatus as in the seventh embodiment.

The manufacturing method of the electrode for discharge surface treatment in this Embodiment is demonstrated. The 72Fe-19Cr-9Ni alloy powder is classified by the high-pressure water atomization method, and the alloy powder having an average particle diameter of about φ1.4 μm is filled into a press die 10 composed of a die having an inner diameter of φ10 mm. The press die 10 filled with the powder is set inside the chamber 7 and the inside of the chamber 7 is evacuated. The upper press bar 4 is pressurized via the hydraulic press mechanism 1 and is pressed to the indentation distance at which the density of the powder 11 in the press die 10 becomes 4.0 g / cm ³ while monitoring the indentation distance with the displacement meter 6. Then, the displacement of the upper press bar 4 is stopped when the predetermined pressing distance is reached. Next, a pulsed current is applied to the upper and lower punch rods 4a and 5a from the pulse power source 20 so that the powder 11 is heated at a temperature rising rate of 20 ° C./min. When the powder 11 reaches 650 ° C., the temperature rises. The pulsating current is controlled so that the temperature stops to maintain 650 ° C. Further, the resistance value of the powder 11 is monitored by the resistance monitor 12, and the energization from the pulse power source 20 is stopped when the resistance value indicated by the resistance monitor 12 becomes 3.0 × 10 ⁻² Ω. The resistance value of the resistance monitor 12 indicates 3.0 × 10 ⁻² Ω when the resistance value of the powder 11 becomes the design value of 2.0 × 10 ⁻² Ω using a standard sample in advance. .

The discharge surface treatment electrode thus produced has a cylindrical shape with a diameter of φ10 mm and a height of 20 mm, a density of 4.0 g / cm ³ , and a resistance value of 1.9 × 10 ⁻² Ω. Yes, and has preferable characteristic values as an electrode for discharge surface treatment. Furthermore, when 10 discharge surface treatment electrodes were produced under the same production conditions as described above, the 10 characteristic variations were ± 0.08 g / cm ^{3 in} density and ± 0.2 × 10 ⁻² Ω in resistance value. And excellent uniformity was obtained.

FIG. 3 is a schematic diagram showing an apparatus for manufacturing a discharge surface treatment electrode according to Embodiment 1; FIG. 3 is a schematic diagram showing a central section of a press die in the first embodiment. FIG. 6 is a schematic diagram showing a central cross section of a press die in a fourth embodiment. FIG. 10 is a schematic diagram showing an apparatus for manufacturing a discharge surface treatment electrode according to a sixth embodiment. It is the perspective view which showed typically the press die structure in Embodiment 6. FIG. FIG. 10 is a schematic diagram showing a central cross section of a press die in a sixth embodiment. FIG. 10 is a schematic diagram showing an apparatus for manufacturing a discharge surface treatment electrode according to a seventh embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic press mechanism part 2 Frame 3 Support stand 4 Upper press bar 4a Upper punch bar 5 Lower press bar 5a Lower punch bar 6 Displacement meter 7 Chamber 8 Heater 9 Heater power supply 10 Press type 11 Powder 12 Resistance monitor 13 Control unit 14 Die 15 Upper punch rod with collar 16 Brim 17 Electrode rod 18 Lower die 19 Press side plate 20 Pulse power supply

Claims (9)

A filling step of filling the pressing jig with conductive powder;
A pressurizing step of applying a load to the press jig to a predetermined pushing distance after the filling step;
A sintering step of heating the powder;
A discharge surface having a stop control step of applying a voltage to the powder after the pressing step and the sintering step and stopping the pressing step and the sintering step based on a current value flowing through the powder. A method for manufacturing a processing electrode. 2. The method for producing an electrode for discharge surface treatment according to claim 1, wherein a direction in which a voltage is applied to the powder and a direction in which a load is applied to the pressing jig are the same. The pressing jig includes an insulating die and a pair of conductive punch bars,
3. The method for producing an electrode for discharge surface treatment according to claim 2, wherein a voltage is applied to the powder by applying a voltage to the pair of punch bars. 2. The method for producing an electrode for discharge surface treatment according to claim 1, wherein a direction in which a voltage is applied to the powder and a direction in which a load is applied intersect. The pressing jig includes a die having a pair of electrically insulated side plates and a pair of insulating punch bars,
The method for producing an electrode for discharge surface treatment according to claim 4, wherein a voltage is applied to the powder by applying a voltage to the pair of conductive side plates. The method for manufacturing an electrode for discharge surface treatment according to claim 1, wherein the sintering step heats a pressing jig. The pressing jig includes an insulating die and a pair of conductive punch bars,
2. The method of manufacturing an electrode for discharge surface treatment according to claim 1, wherein the sintering step includes applying a pulsed voltage to the pair of press rods to energize and heat the powder. The pressing jig includes a die having a pair of electrically insulated side plates and a pair of insulating punch bars,
2. The method of manufacturing an electrode for discharge surface treatment according to claim 1, wherein the sintering step includes applying a pulse voltage to the pair of conductive side plates to heat the powder. A pressurizing means for applying a load to a predetermined pressing distance into a press jig filled with conductive powder;
Sintering means for heating the powder;
An apparatus for manufacturing an electrode for discharge surface treatment, comprising: a stop control unit that applies a voltage to the powder and stops the pressurizing unit and the sintering unit based on a current value flowing through the powder.

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