JP2010094721A - Warm compacting method in powder metallurgy and die device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform heating and cooling of a compacting die body without using a heater. <P>SOLUTION: Raw material powder M is packed into a compacting part 6 formed in a die 2, and the raw material powder M is compressed in the compacting part 6 so as to compact a powder compact. Using a heating liquid H and a cooling liquid C for the heating and cooling of the die 2, the heating liquid H is beforehand heated by a heating liquid feed means 18, the cooling liquid C is cooled by a cooling liquid feed means 19 so as to control temperature, thereafter, using the heating liquid H with which the die 2 has been beforehand heated, the die 2 is heated directly before compacting, and is subjected to warm compacting. After the completion of the compacting, the die 2 is cooled using the beforehand cooled cooling liquid C. By performing the heating of the die 2 only by the heating liquid H without using a heater as a heating means, temperature over upon temperature elevation is eliminated, and a phenomenon that a temperature distribution becomes uneven can be prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a warm forming method in powder metallurgy that performs warm forming in powder metallurgy and a mold apparatus thereof.

In powder molding in powder metallurgy, a warming molding device is equipped with a heater on the upper punch, a heater on the die, a cooling pipe on the die plate, and a heater as a heating means. A method of using a cooling medium such as water or air as a cooling means is common (for example, Patent Document 1).
JP-A-9-253896

  If a heater is used as a heating means as in the prior art, the temperature distribution around the heater installation area and the non-installation area will be non-uniform, or it will be overheated when the temperature rises, and the quality of the molded product will be reduced during molding. Problems may arise due to instability or partial thermal expansion of the mold.

  In addition, when a heater is used, the heater capacity is limited due to restrictions on the heater space, and it takes time to heat, or because there is a heater near the molding part, cooling is performed from the outside of the heater. It may take such a case. Furthermore, the heater wiring may become an obstacle when the mold is set, and it may take time to set or damage the wiring. Moreover, since current flows through the wiring of the heater, there is a risk of electric shock. Further, if the cooling water leaks, the danger increases.

  The problem to be solved is the warmth in powder metallurgy that can be heated in a molding die without using a heater and cooled when the molding die is replaced after molding. It is an object of the present invention to provide a molding method and a mold apparatus therefor.

  The invention of claim 1 is a powder molding method for forming a powder compact by filling a raw material powder in a molding part formed in a molding die and compressing the raw material powder in the molding part, A liquid heat medium is used for heating and cooling the mold, the temperature is controlled by heating or cooling the heat medium in advance, and then the mold is formed using the heat medium in which the mold is preheated immediately before molding. A warm molding method in powder metallurgy, characterized in that a mold is heated, warm molding is performed, and after the molding is finished, the molding die is cooled using a heat medium cooled in advance.

  According to a second aspect of the present invention, there is provided a molding die for filling a molding part with raw material powder and compressing and molding the raw material powder in the molding part, and a passage for a heating and cooling liquid heating medium in the molding die. The mold is heated using a heating medium in which the molding die is heated in advance immediately before molding, warm-molding is performed, and after the molding is finished, the heating mold is used in advance to cool the molding mold. A warm-molding die apparatus in powder metallurgy characterized by cooling a die.

  According to a third aspect of the present invention, the heating heat medium passage and the cooling heat medium passage are selectively heated by the heating heat medium using the same passage. 3. The warm molding die apparatus for powder metallurgy according to claim 2, wherein the mold is cooled by a heat medium.

  The invention of claim 4 is characterized in that the heating medium passage for heating and the passage of the cooling heat medium are switched by a switching means such as a valve and connected to the same passage. It is a warm molding die apparatus in powder metallurgy.

  According to the first aspect of the present invention, the molding die is heated by the heating medium heated in advance, and warm molding is performed. On the other hand, at the end of molding, the molding mold is cooled by the cooling heating medium cooled in advance. The heating mold and the heating medium for cooling can be heated and cooled in advance, so that the molding die can be heated and cooled quickly.

  According to the second aspect of the present invention, the molding die is provided with a heated heat medium passage for warm molding and a cooled heat medium passage for cooling the molding die after the molding is completed. Then, the molding die is heated with a heated heat medium to perform warm molding, and after the molding is finished, the molding die body is cooled with a cooled heating medium, so that the electrical wiring is compared with that using a heater. It is possible to eliminate adverse effects such as electric shock.

  According to the invention of claim 3, the dedicated passages for the heating heat medium and the cooling heat medium are not necessary, and the passages can be shared.

  According to invention of Claim 4, each of the heat medium for cooling and the heat medium for heating can be selectively flowed to a shared channel | path by the switching means.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below do not limit the contents of the present invention described in the claims. In addition, all the configurations described below are not necessarily essential requirements of the present invention.

  Embodiment 1 of the present invention will be described below with reference to FIGS. In this figure, the molding die 1 has an up-down direction as an axial direction (press up-down axis direction), and includes a die 2, a core rod 3, a lower punch 4, and an upper punch 5 as a molding die body. In the embodiment, the die 2 has a substantially cylindrical shape, and a substantially cylindrical core rod 3 is coaxially positioned in the die 2. The lower punch 4 has a substantially cylindrical shape and is fitted between the die 2 and the core rod 3 so as to be vertically movable from below. The upper punch 5 has a substantially cylindrical shape, and is fitted between the die 2 and the core rod 3 so as to be movable up and down from above and detachably. A die plate 10 for fixing the die 2 is provided outside the die 2. The die 2 can be fixed to the die plate 10 by a die press or a die holder.

  As shown in FIG. 4, the powder molded body 101, which is also referred to as a green compact in this example, is a cylindrical rotating body or a bearing. In the case of a bearing, a cylindrical shape in which the rotating shaft slides in the center. A sliding surface 102 as a hole is formed. A molded portion 6 of the powder molded body 101 is formed between the die 2, the core rod 3, and the lower punch 4, and the inner peripheral surface 7 of the die 2 is a portion that forms the inner peripheral portion of the molded portion 6. Thus, the outer peripheral surface of the powder molded body 101 is formed, and the outer peripheral surface 8 of the core rod 3 is a portion forming the central outer peripheral portion of the molded portion 6, which forms the sliding surface 102, and the lower punch 4 The upper surface 9 is a portion that forms the bottom surface portion of the molded portion 6, and forms one end surface in the axial direction of the powder molded body 101. Such a powder compact 101 is sintered in a sintering furnace (not shown).

  As shown in FIG. 1, the die 2 as a molding die body includes a die body 11 having the inner peripheral surface 7, a die intermediate body 12, and a die outer periphery body 13. The body 12 and the die outer periphery 13 are each substantially cylindrical and are made of a metal mold material. The die intermediate body 12 is shrink-fitted in the die outer periphery 13, and the die body 11 is shrink-fitted and fixed to the die intermediate body 12. On the outer peripheral surface 12S of the die intermediate body 12, a groove 15 constituting a passage 14 through which a heating liquid H as a heating medium or a cooling liquid C as a cooling medium selectively passes is formed in a spiral shape. The grooves 15 are formed at substantially equal intervals in the axial direction of the die 2, and the passage 14 is formed by the grooves 15 and the inner peripheral surface 13 U of the die outer peripheral body 13. In addition, by die-fitting the die intermediate body 12 in the die outer peripheral body 13, the passages 14 and 14 adjacent to each other in the die axis direction are kept fluid-tight. In this example, the groove 15 has a substantially semicircular shape, and the interval between the passages 14 and 14 adjacent to each other in the die axis direction is set to be equal to or smaller than the dimension of the passage 14 in the die axis direction.

  Connected to the upper end 14A of the passage 14 is an upper connecting passage 16 comprising a lateral portion 16A and a downward portion 16B connected to the end of the lateral portion 16A. The outlet side switching valve 17 is connected. The outlet-side switching valve 17 is an electrically operated automatic type, and its primary side 17A is connected to the upper end 14A side, that is, a heating liquid H or a cooling liquid C discharge side described later. On the other hand, heating liquid supply means 18 for heating liquid H such as water or silicone oil is connected to one secondary side 17B of the outlet side switching valve 17 via a secondary side passage 18A.

  In addition, the temperature of less than 100 ° C is used as a medium, and if it is higher than that, for example, if it is about 150 ° C, various known heat media such as silicone oil can be used for high temperature warm forming. Is possible.

  A coolant supply means 19 for coolant C such as water or silicone oil is connected to the other secondary side 17C of the outlet side switching valve 17 via a secondary side passage 19A. The outlet side switching valve 17 can selectively connect the primary side 17A to either the secondary side 17B or the secondary side 17C by the control means 23 described later. The outlet side switching means may be an automatic switching valve such as an electromagnetic valve.

  The lower end 14B of the passage 14 is formed with a lower connecting passage 20 including a lateral portion 20A and a downward portion 20B connected to the end of the lateral portion 20A. Is connected to an inlet side switching valve 21 as an inlet side switching means. The inlet side switching valve 21 is an electric type automatic type, and one of the primary sides 21A is connected to the heating liquid supply means 18 via a primary side passage 18B. The other primary side 21B of the inlet side switching valve 21 is connected to the coolant supply means 19 via the primary side passage 19B. On the other hand, a downward portion 20B is connected to the secondary side 21C of the inlet side switching valve 21. The inlet side switching valve 21 can be selectively connected by the control means 23 to either the primary side 21A or the other primary side 21B to the secondary side 21C. The inlet side switching means may be an automatic switching valve such as an electromagnetic valve.

  Further, when the primary side 17A is connected only to the secondary side 17B by the outlet side switching valve 17 by the control means 23, the primary side 21A can be connected only to the secondary side 21C by the inlet side switching valve 21. ing. On the other hand, when the primary side 17A is connected to only the secondary side 17C by the outlet side switching valve 17 by the control means 23, the primary side 21B can be connected only to the secondary side 21C by the inlet side switching valve 21. ing.

  In the heating liquid supply means 18, the low-temperature heating liquid H collected in the tank section 18C through the secondary passage 18A is heated by a heater (not shown) or a heat exchanger (none shown). It can be heated and discharged again to the primary passage 18B. In the coolant supply means 19, the warmed coolant C collected in the tank portion 19C via the secondary side passage 19A is cooled by a heat exchanger (not shown), and again the primary side passage 19B. Can be discharged.

  The temperature of the heating liquid H or the temperature of the cooling liquid C is provided in the upper connection passage 16 and the temperature is controlled to a set temperature by the temperature sensor 22. Further, the die 2 is provided with a temperature sensor 24, which is provided in the die body 11 and is connected to the control means 23. As shown in FIG. 3, the control means 23 includes a heating liquid supply means 18, a cooling liquid supply means 19, an outlet side switching valve 17, an inlet side switching valve 21, a temperature sensor 22, a temperature sensor 24 of the die 2, etc. Is connected.

  For this reason, the temperature sensor 24 of the die 2 outputs the measured temperature data to the control means 23, and the control means 23 controls the heating state or the feeding state in the heating liquid supply means 18 based on the temperature data. In this case, the temperature of the die 2 can be controlled by changing the flow rate and temperature of the feed pump (not shown) provided in the tank portion 18C and the heated liquid H to be fed.

  As the raw material powder M, those for general metal powder metallurgy such as iron powder and iron alloy powder are used. Reference numeral 31 in the figure denotes a feeder as a raw material supply body. The feeder 31 is slidably provided on the upper surface 2A of the die 2, and the raw material powder M is dropped into the molding unit 6 by the feeder 31. It can be filled with.

  Next, the operation of the above configuration will be described. In the molding step, the control means 23 controls the outlet side switching valve 17, the inlet side switching valve 21, and the heating liquid supply means 19, and the heating liquid H previously heated in the tank portion 18C by the heating liquid supply means 18 is passed through the passage. The temperature is controlled via a temperature sensor 24 so that the inner peripheral surface 7 of the die 2 is kept at a predetermined temperature or higher. At this time, the control unit 23 connects the primary side 17A only to the secondary side 17B via the outlet side switching valve 17, and connects the primary side 21A only to the secondary side 21C via the inlet side switching valve 21. is doing.

  Next, in a state where the lower punch 4 is fitted to the die 2 to form the molded part 6, the feeder 31 moves forward to drop the raw material powder M into the molded part 6 and fill it. Then, the feeder 31 moves backward, and the upper punch 5 is inserted into the opening 6A of the molding unit 6 from above, and the raw material powder M is compressed by warm molding so as to be sandwiched between the upper punch 5 and the lower punch 4. At this time, the lower punch 4 is fixed at the lower end so as not to move. Note that the die 2 may be moved downward before the upper punch 5 is inserted into the molding portion 6.

  In this manner, the powder compact 101 that has been warm-pressed while the die 2 is at a predetermined temperature is taken out in the take-out step. In this extraction step, the die 2 and the core rod 3 are lowered downward, or the lower punch 4 is raised and the upper surface of the lower punch 4 becomes substantially the same height as the upper surface 2A of the die 2, and the raw powder The process of filling the molding part 6 with M, warm pressure molding, and taking out is repeated.

  After all the warm forming using the die 2 is completed, when the die 2 is removed from the die plate 10 and replaced, it is necessary to cool the die 2 because it is hot. At this time, the control means 23 connects the primary side 17A only to the secondary side 17C via the outlet side switching valve 17, and connects the primary side 21B only to the secondary side 21C via the inlet side switching valve 21. Control is performed via the die temperature sensor 24 so that the coolant C cooled in the tank portion 19C in advance by the coolant supply means 19 flows into the passage 14 and keeps the inner peripheral surface 7 of the die 2 below a predetermined temperature.

  Then, the die 2 whose temperature has become low is removed from the die plate 10 and replaced with another die (not shown). At this time, the primary side 17A of the outlet side switching valve 17 is removed from the downward portion 16B, and the secondary side 21C of the inlet side switching valve 21 is removed from the downward portion 20B side.

  As mentioned above, in the said Example, when the raw material powder M is filled into the shaping | molding part 6 formed in the die | dye 2, and the raw material powder M is compressed by the shaping | molding part 6, the die | dye 2 is heated. The heating liquid H and the cooling liquid C are used for cooling, and the heating liquid H is heated by the heating liquid supply means 18 in advance, or the cooling liquid C is cooled by the cooling liquid supply means 19 to control the temperature, and immediately before molding. Heating is performed by heating the die 2 using the heating liquid H obtained by heating the die 2 in advance, performing warm forming, and cooling the die 2 using the cooling liquid C cooled in advance after the forming is completed. By heating the die 2 only with the heating liquid H, which is a liquid heat medium, as a means, it is possible to prevent the temperature from being over at the time of temperature rise and to prevent the temperature distribution from becoming uneven. The temperature distribution became almost uniform. In addition, by using the heating liquid H that is a heating medium whose temperature is controlled by heating in advance, excessive heating at the time of temperature rise is prevented.

  Furthermore, the die 2 provided with the molding part 6 is provided with a passage 14 for the heating liquid H and the cooling liquid C, and the die 2 is heated using the heating liquid H obtained by heating the die 2 in advance immediately before molding. After the molding is completed, the die 2 is cooled by using the cooling liquid C that has been cooled in advance, so that the heating liquid H and the cooling liquid C, which are heating media that are heated or cooled in advance, are temperature controlled. In use, the heating time or cooling time can be greatly reduced. In particular, since the temperature can be easily controlled by the separately provided tank section 18C for storing the heating liquid H and the tank section 19C for storing the cooling liquid C, there are no restrictions on the heating capacity and the cooling capacity. In addition, by using the heating liquid H and the cooling liquid C whose temperatures are controlled in advance, the heating and cooling time is greatly shortened. Moreover, since there is no wiring, it does not take time to set the mold. Furthermore, there is no risk of electric shock because there is no current flowing around the mold.

  Further, the passage 41 for the heating liquid H and the passage 14 for the cooling liquid C are selectively connected to a single passage 41 provided in a planar annular shape so as to surround the periphery of the molding portion 6 provided in the die 2. By using the same passage 14, the die 2 is heated by the heating liquid H and warm-molded. On the other hand, after the molding is completed, the die 2 is cooled by the cooling liquid C. The passages for the liquid H and the coolant C are not necessary, and the passage 14 can be shared. In addition, since the cooling liquid C can be directly flowed through the passage 14 during heating, it is not necessary to cool it at a position away from the heating portion, and the cooling time can be shortened.

  Further, the passage 14 for the heating liquid H and the passage 14 for the cooling liquid C are switched by an outlet side switching valve 17 as an outlet side switching means such as a switching valve or a solenoid valve and an inlet side switching valve 21 as an inlet side switching means. By connecting to the same passage 14, heating and cooling can be easily switched by switching between the heated heating liquid H and the cooled cooling liquid C.

  As described above, the warm forming method and its mold apparatus in powder metallurgy according to the present invention can be applied to various applications.

It is sectional drawing of the metal mold | die apparatus which shows Example 1 of this invention. It is a front view of the principal part of die | dye same as the above. It is a block diagram same as the above. It is a perspective view of a powder molded object same as the above.

Explanation of symbols

1 Mold 6 Molding part
14 Passage
17 Outlet side switching valve (outlet side switching means)
21 Inlet side switching valve (Inlet side switching means)
C Coolant (cooling medium)
H Heating liquid (heating medium)
M Raw material powder

Claims (4)

A molding method of powder molding in which a raw material powder is filled in a molding part formed in a molding die, and the raw material powder is compressed in the molding part to form a powder compact,
A liquid heat medium is used for heating and cooling the molding die, the temperature is controlled by heating or cooling the heating medium in advance, and a heating medium in which the molding die is heated immediately before molding is used. A warm molding method in powder metallurgy, characterized in that a molding die is heated to perform warm molding, and after the molding is completed, the molding die is cooled using a heat medium cooled in advance.   The molding part is filled with raw material powder, the molding powder is compressed by the molding part and molded, and a heating and cooling liquid heat medium passage is provided in the molding mold, and the molding powder is immediately before molding. Heating the mold using a heating medium that has been heated in advance, and performing warm molding, and after the molding is completed, the heating mold is cooled using the cooling medium that has been cooled in advance. Warm forming mold equipment in powder metallurgy.   The heating heat medium passage and the cooling heat medium passage are selectively heated by the heating heat medium and cooled by the cooling heat medium using the same passage. The warm molding die apparatus for powder metallurgy according to claim 2.   4. The warm forming in powder metallurgy according to claim 3, wherein the passage of the heating heat medium and the passage of the cooling heat medium are switched by a switching means such as a valve and connected to the same passage. Mold equipment.

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