Motor driven powder forming machine

Abstract

The motor-driven powder molding machine according to the present disclosure molds powder using an upper mold and a lower mold, and includes: in each of the upper mold and the lower mold, a main plunger for operating the upper mold or the lower mold through a main shaft; an auxiliary plunger for operating the upper mold or the lower mold synchronously with the main plunger through an auxiliary shaft; and a pressure detector for detecting the pressure in the axial direction in at least one of the main plunger and the auxiliary plunger. The motor-driven powder molding machine also includes a controller for controlling the operating speed of the upper mold and the lower mold through at least one of the main plunger and the auxiliary plunger based on the detected pressure so that the pressure falls within a predetermined range.

Description

Technical Field

[0001] The present disclosure relates to a motor-driven powder forming machine. Background Art

[0002] In recent years, in terms of reducing CO2 emissions and protecting the environment, there is a demand for electrification of a powder molding machine for manufacturing mechanical parts by filling powder into a mold and then compressing the powder. Under such circumstances, an electric powder molding machine composed of an electric device has been developed instead of the hydraulically driven powder molding machine of the prior art. The electric powder molding machine can greatly shorten the time for equipment adjustment.

[0003] If an electric powder molding machine has a structure of an upper mold with one shaft and a lower mold with one shaft, the electric powder molding machine can only mold sintered parts with a simple structure. Therefore, it is necessary to develop an electric powder molding machine that can form more complex sintered parts by providing an upper section and a lower section. Japanese Unexamined Patent Application Publication No. 2017-205769 discloses a technology of an electric powder molding machine that obtains a moving speed of an upper mold, multiplies the moving speed by a predetermined rate, and sets a target speed of a lower mold to follow the lower mold. Summary of the invention

[0004] Even when following the lower die according to the moving speed of the upper die, if the lower die or the upper die reaches the limit position of the movable range, a load increase occurs due to a control delay for a rapid increase in the pressurizing speed, and parts of the mold or equipment may be damaged.

[0005] An object of the present disclosure is to provide a motor-driven powder molding machine for solving such problems.

[0006] According to the present invention, a motor-driven powder molding machine uses an upper mold and a lower mold to mold powder, and the motor-driven powder molding machine includes: in each of the upper mold and the lower mold, a main plunger, which is configured to operate the upper mold or the lower mold through a main shaft; an auxiliary plunger, which is configured to operate the upper mold or the lower mold synchronously with the main plunger through an auxiliary shaft; a pressure detector, which is used to detect the pressure in the axial direction in at least one of the main plunger and the auxiliary plunger; and a controller, which is used to control the operating speed of the upper mold and the lower mold through at least one of the main plunger and the auxiliary plunger based on the detected pressure, so that the pressure falls within a predetermined range.

[0007] According to the present disclosure, it is possible to provide a motor-driven powder molding machine capable of reducing a control delay for a rapid increase in a pressurization speed.

[0008] The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given below and the accompanying drawings which are given by way of illustration only and thus should not be considered as limiting the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a cross-sectional view showing the configuration of a motor-driven powder molding machine according to a first embodiment of the present disclosure.

[0010] Figure 2 is a cross-sectional view showing the configuration of an auxiliary plunger servo unit according to the first embodiment of the present disclosure.

[0011] Figure 3 is a cross-sectional view showing the configuration of a motor-driven powder molding machine according to a second embodiment of the present disclosure.

[0012] Figure 4 A process of powder molding using a motor-driven powder molding machine according to the prior art is shown. DETAILED DESCRIPTION

[0013] Hereinafter, the embodiments will be described with reference to the accompanying drawings. Since the accompanying drawings are simplified, the technical scope of the embodiments should not be narrowly interpreted based on the description of the accompanying drawings. The same elements are represented by the same figure numerals, and repeated descriptions are omitted. When the number of elements including the number of pieces, numerical values, quantities, ranges, etc., etc. are mentioned in the following embodiments, the number thereof is not limited to a specific number, and may be greater than, less than, or equal to a specific number, unless otherwise specifically stated and clearly defined as a specific number in principle.

[0014] <Research History Until Conception of Motor Driven Powder Molding Machine According to Embodiment>

[0015] First, refer to Figure 4 A motor driven powder compacting machine according to the prior art is described. Figure 4 A process of powder molding in a mold cavity formed using an upper mold and a lower mold using a motor-driven powder molding machine in a conceptual stage before the embodiment is conceived is shown.

[0016] As a premise, in the case of a device having a structure in which two ball screws are arranged diagonally for driving one axis, the number of servo units to be used greatly increases, and simplification of the device becomes a problem. To simplify the device, it is necessary to use a single motor and ball screw drive for single-axis drive. However, there is a concern that the device may be damaged due to the following reasons.

[0017] Specifically, multi-stage molding in which the mold is divided by the number of segments of the product and the compression rate of each part is maintained within an appropriate range under pressure is assumed. In the case of multi-stage molding, if floating axes for performing proportional integral differential (PID) speed control are arranged to face each other while monitoring the control pressure during pressurization, a control delay for a rapid increase in the pressurization speed may occur when the lower mold or the upper mold reaches the limit position of the movable range. The increased pressure associated with the control delay may damage the mold or parts of the equipment.

[0018] Figure 4 The graph of FIG. 1 schematically shows the pressure applied to the shaft during molding using the upper die and the lower die. Figure 4 As shown in , due to the pressure applied from the product during molding, the upper axis moves upward and the lower axis moves downward. Even when a load cell is used to monitor the pressure, a rapid increase in pressure may occur when the lower or upper die reaches the limit of the movable range. In addition, if the pressure applied to the load cell increases rapidly, the control may not be able to keep up. In such a case, the motor driving the powder molding machine and peripheral equipment may be damaged.

[0019] Therefore, a motor-driven powder molding machine according to the following embodiments that can solve such problems has been found.

[0020] [First embodiment]

[0021] Will refer to Figure 1 and Figure 2 The motor-driven powder molding machine 1 according to the present embodiment is described. Figure 1 : is a sectional view showing the configuration of the motor-driven powder molding machine 1 according to the present embodiment. Figure 2 : is a cross-sectional view showing the configuration of an auxiliary plunger servo unit of the motor-driven powder molding machine 1 according to the present embodiment. Figure 2 It is an upper die auxiliary plunger servo unit 80 to be described later, and has the same configuration as the lower die auxiliary plunger servo unit 70. Therefore, the description of the configuration of the lower die auxiliary plunger servo unit 70 will be omitted.

[0022] like Figure 1 As shown in FIG. 1 , the motor-driven powder molding machine 1 is, for example, disposed on a base 60. The motor-driven powder molding machine 1 has a rectangular parallelepiped shape extending in a direction perpendicular to the base 60. The motor-driven powder molding machine 1 includes a lower die main plunger servo unit 10, a lower die 20, an upper die 30, an upper die main plunger servo unit 40, and a control unit 50.

[0023] In the motor driven powder molding machine 1, powder material is filled in a cavity formed using an upper mold 30 and a lower mold 20. Pressure is applied to the filled powder material by the upper mold main plunger servo unit 40 and the lower mold main plunger servo unit 10, so that the powder is subjected to compression molding. The upper mold main plunger servo unit 40 operates the upper mold 30 through the spindle. The lower mold main plunger servo unit 10 operates the lower mold 20 through the spindle. In this case, the upper mold 30 and the lower mold 20 move in one direction, for example, in the vertical direction.

[0024] A rotating mechanism may be provided below the lower mold 20. In this case, the rotating mechanism may rotate the lower mold 20 on a horizontal plane. Note that the horizontal plane is not limited to an accurately horizontal plane, but instead includes a plane inclined to a certain degree according to technical purposes.

[0025] like Figure 1 As shown in , the lower die main plunger servo unit 10 can be arranged at the lower part of the motor-driven powder molding machine 1. The lower die main plunger servo unit 10 may include a servo motor. In this case, the servo motor moves the lower die 20. The servo motor is used to move the lower die 20 and compress and mold the powder material.

[0026] like Figure 1 As shown in FIG. 1 , the upper mold 30 is disposed above the lower mold 20. The upper mold 30 and the lower mold 20 are molds for compression molding the powder material filled in the cavity.

[0027] The upper die main plunger servo unit 40 is disposed above the upper die 30. The upper die main plunger servo unit 40 may include a servo motor. A plurality of servo motors may be provided. The upper die main plunger servo unit 40 moves the upper die 30.

[0028] The control unit 50 controls the moving speed of the upper mold 30 and the lower mold 20 of the motor-driven powder molding machine 1. The control unit 50 moves the lower mold 20 and the upper mold 30 by controlling the servo motor.

[0029] The lower die auxiliary plunger servo unit 70 is disposed below the lower die 20. The lower die auxiliary plunger servo unit 70 may include an auxiliary plunger drive slider. In such a case, a linear motion ball screw may be provided on the auxiliary plunger drive slider. The lower die auxiliary plunger servo unit 70 controls the operating speed of the lower die 20 by operating synchronously with the lower die main plunger servo unit 10. The lower die auxiliary plunger servo unit 70 applies pressure to the filled powder material by operating the lower die 20 through an auxiliary shaft to perform compression molding.

[0030] The upper die auxiliary plunger servo unit 80 is disposed above the upper die 30. The upper die auxiliary plunger servo unit 80 may include an auxiliary drive slider. In this case, a linear motion ball screw may be provided on the auxiliary plunger drive slider. The upper die auxiliary plunger servo unit 80 controls the operating speed of the upper die 30 by operating synchronously with the upper die main plunger servo unit 40. The upper die auxiliary plunger servo unit 80 applies pressure to the filled powder material by operating the upper die 30 through the auxiliary shaft to perform compression molding.

[0031] The main shaft load cell 14a is provided on the main shaft, and the auxiliary shaft load cells 14b and 14c are provided on the auxiliary shafts. The load cells 14a, 14b, and 14c are used as pressure detectors for detecting the pressure applied in the axial direction. Therefore, a pressure detector such as a pressure gauge may be used instead of the load cells 14a, 14b, and 14c. The load cells may be provided on the main shaft or the auxiliary shaft.

[0032] In this case, the control unit 50 monitors the pressure applied in the respective axial directions using the load cells 14a, 14b, and 14c. Based on the pressure detected by the load cells 14a, 14b, and 14c, the control unit 50 may control the operating speed of at least one of the lower die main plunger servo unit 10 and the lower die auxiliary plunger servo unit 70, or may control the operating speeds of both the lower die main plunger servo unit 10 and the lower die auxiliary plunger servo unit 70, so that these pressures fall within a predetermined range. Based on the pressure detected by the load cells 14a, 14b, and 14c, the control unit 50 may control the operating speed of at least one of the upper die main plunger servo unit 40 and the upper die auxiliary plunger servo unit 80, or may control the operating speeds of both the upper die main plunger servo unit 40 and the upper die auxiliary plunger servo unit 80, so that these pressures fall within a predetermined range.

[0033] In addition, in order to prevent damage to the equipment when a rapid increase in the pressurization speed occurs in the load cells 14a, 14b, and 14c, a main shaft pressure absorbing member 15a, an auxiliary shaft pressure absorbing member 15b, and 15c are respectively provided between the ball screws of the main shaft and the auxiliary shaft of each of the upper and lower molds and the load cells 14a, 14b, and 14c. The main shaft pressure absorbing member 15a and the auxiliary shaft pressure absorbing members 15b and 15c are mechanical shock absorbing members, and may be constituted by, for example, a simple hydraulic cylinder. The main shaft pressure absorbing member 15a and the auxiliary shaft pressure absorbing members 15b and 15c may be operated when the pressure applied to at least one of the main shaft 11 and the auxiliary shafts 12 and 13 in the axial direction becomes a predetermined value or higher. In such a case, a sensor for detecting the operation of each pressure absorbing member may be provided, and the control unit 50 may detect the operation of the main shaft pressure absorbing member 15a and the auxiliary shaft pressure absorbing members 15b and 15c.

[0034] Here, the predetermined value is a value higher than the upper limit value of the predetermined range of the pressure applied in the axial direction when the control unit 50 controls the operation speed of the mold. The predetermined value is lower than the pressure applied in the axial direction when one of the upper mold 30 and the lower mold 20 moving in the direction in which the elastic retracting pressure is applied reaches the limit position of the movable range due to the movement of the other of the upper mold 30 and the lower mold 20.

[0035] In addition, a configuration may be adopted in which the positions of the upper die 30 and the lower die 20 are monitored using a linear sensor. In such a case, the control unit 50 may use the linear sensor to obtain the actual speed of the upper die 30 and the lower die 20. Here, the actual speed indicates a real speed, for example, a real speed of the upper die calculated based on the movement of the position of the upper die. By operating the auxiliary shafts 12 and 13 synchronously with the main shaft 11, thorough molding is enabled, and a complex sintered part can be molded with high precision.

[0036] As the operation of the motor-driven powder molding machine 1, a method for molding a powder material and a method for controlling the motor-driven powder molding machine 1 in powder molding will be described. As a method for molding the powder material filled in the cavity, for example, proportional molding is used. Proportional molding is a molding method in which compression is performed by delaying the lower mold 20 relative to the upper mold 30 at a constant rate.

[0037] According to the motor driven powder molding machine 1 of this embodiment, the rapid increase of the pressurization speed which may damage the equipment can be reduced. In addition, by providing the main shaft pressure absorbing member 15a and the auxiliary shaft pressure absorbing members 15b and 15c, damage to the equipment can be prevented as a failsafe function.

[0038] [Second embodiment]

[0039] Will refer to Figure 3 The motor-driven powder molding machine 1 according to the present embodiment is described. Figure 3 1 is a cross-sectional view showing the configuration of the motor-driven powder molding machine 1 according to the present embodiment. Unlike the first embodiment, the motor-driven powder molding machine 1 according to the present embodiment includes two lower die main plunger servo units 10 .

[0040] like Figure 3 As shown in , the lower die main plunger servo unit 10 may be provided at the lower part of the motor driven powder molding machine 1. Each of the lower die main plunger servo units 10 may include a servo motor. Two lower die main plunger servo units 10 are arranged below the lower die 20 and are arranged with a gap therebetween in the horizontal direction. Note that the number of the lower die main plunger servo units 10 is not limited to two, and may be three or more instead.

[0041] like Figure 3As shown in , two lower die main plunger servo units 10 are connected and linked to both ends of the lower die main plunger servo unit connecting rod 16 extending in the horizontal direction. In this way, the connecting rod 16 serves as a linking mechanism of the two lower die main plunger servo units 10. Therefore, the two lower die main plunger servo units 10 operate synchronously. The linking mechanism can move vertically between the two servo motors.

[0042] As in the motor-driven powder molding machine according to the present embodiment, by arranging two lower die main plunger servo units 10 and inserting a connecting rod 16 therebetween, the force required to move the lower die 20 and compress the powder material can be shared between the two lower die main plunger servo units 10, and the lower die main plunger servo unit 10 can be miniaturized.

[0043] In addition, when a rapid increase in pressure occurs due to one of the lower mold 20 and the upper mold 30 reaching the limit position of the movable range, the connecting rod 16 elastically deforms to serve as a cushion for the molded product. By including a link mechanism using the connecting rod 16, the possibility of equipment being damaged can be reduced.

[0044] From the disclosure thus described, it will be apparent that the embodiments of the present disclosure may be modified in a variety of ways. Such variations should not be regarded as departing from the spirit and scope of the present disclosure, and all such modifications that would be apparent to those skilled in the art are intended to be included within the scope of the appended claims.

Claims

1. A motor-driven powder molding machine for molding powder using an upper mold and a lower mold, the motor-driven powder molding machine comprising: In each of the upper die and the lower die, a main plunger configured to operate the upper die or the lower die through a main shaft, an auxiliary plunger configured to operate the upper die or the lower die synchronously with the main plunger through an auxiliary shaft, a pressure detector for detecting a pressure in an axial direction in at least one of the main plunger and the auxiliary plunger; a controller for controlling the operation speeds of the upper die and the lower die through at least one of the main plunger and the auxiliary plunger based on the detected pressure so that the pressure falls within a predetermined range; a pressure absorbing member provided between the main shaft and the pressure detector and between the auxiliary shaft and the pressure detector, configured to absorb the pressure in at least one of the main shaft and the auxiliary shaft, the pressure absorbing member being operated when the pressure applied in the axial direction becomes a predetermined value or more, the predetermined value being lower than the pressure applied in the axial direction when one of the upper die and the lower die moving in the direction in which the elastic retracting pressure is applied reaches a limit position of a movable range due to movement of the other of the upper die and the lower die; a pressure absorbing member sensor for detecting operation of the pressure absorbing member; A linear sensor for monitoring the positions of the upper die and the lower die to obtain the actual speeds of the upper die and the lower die; as well as Two lower die main plunger servo units are arranged below the lower die, are arranged horizontally with a gap between the two, and are configured to operate the lower die through the spindle. Wherein, the two lower die main plunger servo units are connected and linked to two ends of a lower die main plunger servo unit connecting rod extending along the horizontal direction; and When a rapid increase in pressure occurs due to one of the lower die and the upper die reaching a limit position of a movable range, the lower die main plunger servo unit coupling rod is elastically deformed to serve as a cushion for molding a product.

2. The motor-driven powder forming machine according to claim 1, wherein: The predetermined value is a value higher than an upper limit value of the predetermined range.

3. The motor-driven powder molding machine according to claim 1, wherein: The pressure absorbing member is constituted by a hydraulic cylinder.

4. The motor-driven powder molding machine according to any one of claims 1 to 3, wherein: The pressure detector is provided for each of the main plunger and the auxiliary plunger.

5. The motor-driven powder forming machine according to claim 4, wherein: The pressure detector is provided for all of the main plungers and the auxiliary plungers provided for each of the upper die and the lower die.

6. The motor-driven powder molding machine according to claim 5, wherein: The controller is configured to control the operation speed so that the pressures detected by all the pressure detectors fall within the predetermined range.

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