JP2017070975A - Control method for powder molding device - Google Patents

Abstract

Provided is a control method for a powder molding apparatus capable of solving the problem that a floating load suddenly decreases after a floating lower punch reaches a stopper and damages the apparatus. A die 1 having a hollow 1a, an upper punch 3 and a floating lower punch 5, a first actuator 4 for pressing the upper punch 3, and a second actuator 7 for controlling a floating load of the floating lower punch 5. And a stopper 8 that defines the pressure stop position of the floating lower punch 5, and pressurizes the powder F filled in the cavity by pressing the upper punch 3 by operating the first actuator 4. In the control method of the powder molding apparatus 10 that controls the second actuator 7 to pressurize the powder F so that the load acting on the powder F during pressurization becomes a predetermined floating load necessary for molding, When the floating lower punch 5 approaches the stopper 8 to a predetermined distance, the first actuator 4 is controlled to reduce the lowering speed of the upper punch 3. [Selection] Figure 4

Description

  The present invention relates to a method for controlling a powder molding apparatus.

  One of the methods for pressure forming powder is a floating forming method. This floating molding is roughly composed of a die having a hollow, a floating lower punch that slides in the hollow, an upper punch that is also slidable in the hollow, and various actuators that drive the floating lower punch and the upper punch, respectively. It is carried out using a configured powder forming apparatus.

  Fill the cavity formed by the die, floating punch and upper punch with powder, press the upper punch with an actuator consisting of a hydraulic cylinder, air cylinder, etc., and pressurize the powder. Pressurization of powder is performed while the floating punch is slid by an actuator so that a predetermined pressing force (floating load) is applied. There is also a device in which a fixed lower punch that does not slide around the floating lower punch exists, and a cavity is formed by the fixed lower punch, the floating lower punch, the die, and the upper punch.

  Further, in addition to the floating lower punch and the upper punch, there is also a powder molding apparatus in which the die can be slid by an actuator. In this molding apparatus, the upper punch and the floating lower punch are lowered while being lowered at a predetermined rate. When pressurizing (for example, when the upper punch descends at a speed of 10 the floating lower punch descends at a speed of 7), the die is also lowered synchronously (for example, descends at a speed of 8) When the green compact is manufactured by gradually compacting the powder from the vicinity of the upper punch, it is possible to make it difficult to generate a density distribution in which the density of the green compact decreases in order from the vicinity of the upper punch.

  By the way, in the floating molding, it is possible to execute a control for completing the pressurization by the upper punch and the floating lower punch when the lower floating punch reaches the stopper and a predetermined time has elapsed.

  In such control, since the floating punch continues to descend (try to move) during the control time required to stop the floating punch, the time until the floating punch stops is long. Then, there is a problem that the movement to continue the descent of the floating punch whose descent is restricted by the stopper propagates throughout the apparatus, leading to damage to the apparatus.

  This will be described with reference to the displacement-time graph of the upper punch and the floating punch shown in FIG. Since the floating punch under pressure has a lowering speed by the actuator, the floating load starts to decrease from the moment when the floating punch reaches the stopper. Here, if the time required for the control is sufficient, the rotation of the actuator that has operated the floating punch in the descending direction to maintain the reduced floating load at the set value starts to decelerate, and the floating punch After the descent speed reaches zero, it moves upward until it reaches a floating load.

  Since the time required for the above control is limited, if the lowering speed of the floating lower punch immediately before reaching the stopper is high, the control will not be in time, and the floating load of the lower floating punch will rapidly decrease as shown in FIG. Become.

  When the floating load is in the pulling direction, the device components are pulled downward, leading to damage to the device.

  Here, in Patent Document 1, a die is movably disposed on a die holder interlocked with a press lower ram, a fixed lower punch and a floating lower punch are disposed on a fixed position punch plate, and the floating lower punch is placed on the punch plate. One end of a connecting rod that works with the lower ram of the press is positioned in the bore of the cylinder device, and the powder is partially moved by being sandwiched between the lower floating punch and the upper floating punch. After that, a powder molding apparatus is disclosed in which the piston of the cylinder device is brought into contact with the connecting rod, and the ascending force of the lower ram is applied to the powder for preliminary molding, and then the lowering of the floating punch is stopped by the stopper to perform final molding. Has been.

JP-A-6-25706

  According to the powder forming apparatus disclosed in Patent Document 1, the powder transfer mechanism can be reduced in size and simplified using a ram under the press. However, even when the powder molding apparatus disclosed in Patent Document 1 is applied, the above-described problem, that is, the floating punch reaches the stopper at a speed, and the floating load rapidly decreases, leading to damage to the apparatus. Such a problem cannot be solved.

  The present invention has been made in view of the above-described problems, and by reducing the time required for the floating lower punch to completely stop the operation to descend after reaching the stopper, the floating load is reduced as much as possible. An object of the present invention is to provide a method for controlling a powder molding apparatus that can solve the problem of a sudden drop in the amount of damage that damages the apparatus.

  In order to achieve the above object, a method for controlling a powder molding apparatus according to the present invention includes a die having a hollow, an upper punch that slides in the hollow and forms a cavity together with the die, a floating lower punch, and an upper punch. A first actuator, a second actuator for controlling a floating load of the floating lower punch, and a stopper for defining a pressure stop position of the floating lower punch. Press the upper punch by pressing the actuator 1 and pressurize, and pressurize the powder by controlling the second actuator so that the load acting on the powder during pressurization becomes the predetermined floating load necessary for molding In the control method of the powder molding apparatus that executes the above, when the floating lower punch approaches a predetermined distance from the stopper, the upper punch is moved to the first actuator. And it executes a control to decelerate the lower speed.

  The control method of the powder molding apparatus according to the present invention is such that when the floating lower punch approaches the stopper to a predetermined distance, the first actuator is controlled to decelerate the lowering speed of the upper punch. It is possible to shorten the time from when the lower punch reaches the stopper until it completely stops the operation of lowering as much as possible.

  In floating molding, control is performed so that the floating lower punch also descends in synchronization with the lowering of the upper punch, and when the upper punch descending speed is reduced, the lowering punch is also synchronized in synchronism with the lowering speed. With this control, the time until the floating lower punch stops completely after the floating lower punch reaches the stopper can be shortened by controlling the timing of the lowering speed of the upper punch.

  The position of the floating punch with respect to the stopper is specified by the second actuator.

  Further, when the second actuator specifies that the position of the floating lower punch with respect to the stopper is approaching a predetermined distance, based on this information, the lowering control of the lowering speed of the upper punch is executed by the first actuator.

  As described above, the lowering control synchronized with the upper punch and the lower floating punch, and the deceleration control of the lowering speed of the upper punch by the first actuator based on the position information of the lower lower punch by the second actuator are executed accurately. The first and second actuators are preferably servo actuators, and for example, an electric servo motor is preferably applied.

  Here, the "predetermined distance" where the floating lower punch approaches the stopper means the upper punch lowering speed at which the floating load does not rapidly decrease until the floating lower punch reaches the stopper and then pressurization is completed. This is the distance corresponding to the start of deceleration. The “predetermined distance” is set in consideration of the speed of the upper punch after deceleration, the time required for the upper punch to decelerate, the distance that the lower floating punch descends, the amount of elastic deformation of the lower floating punch, and the like.

  According to the present invention, the distance to the stopper of the floating punch is used as a trigger for starting deceleration of the lowering speed of the upper punch, and the timing of deceleration of the lowering speed of the upper punch is controlled based on this trigger, thereby Therefore, it is possible to effectively eliminate the breakage of the apparatus due to the sudden drop of the floating load.

  As can be understood from the above description, according to the control method of the powder molding apparatus of the present invention, the first actuator that presses down the upper punch when the floating lower punch approaches a predetermined distance from the stopper. By executing the control to reduce the lowering speed of the upper punch, the rapid lowering of the floating load after the floating lower punch reaches the stopper is suppressed, and the breakage of the device due to the rapid lowering of the floating load is eliminated. be able to.

It is the schematic diagram explaining the state with which the cavity of the powder shaping | molding apparatus with which the control method of this invention is applied is filled with powder. It is the schematic diagram which demonstrated the state which the control method of this invention is performed and pressurizes powder and shape | molds the green compact. It is the schematic diagram explaining the state where the floating punch has reached the stopper. It is the figure which showed the displacement-time graph of the upper punch and the floating punch, and the floating punch load-time graph explaining the control method of this invention. It is the figure which showed the displacement-time graph of the upper punch and the floating punch, and the floating punch load-time graph explaining the conventional control method.

  Embodiments of a method for controlling a powder molding apparatus of the present invention will be described below with reference to the drawings.

(Embodiment of control method of powder molding apparatus)
FIG. 1 is a schematic diagram illustrating a state in which powder is filled in a cavity of a powder molding apparatus to which the control method of the invention is applied, and FIG. FIG. 3 is a schematic diagram illustrating a state in which powder is formed, and FIG. 3 is a schematic diagram illustrating a state in which the floating punch reaches the stopper. Further, FIG. 4 is a diagram illustrating a displacement-time graph and a floating punch load-time graph of the upper punch and the floating punch, which illustrate the control method of the present invention.

  The illustrated powder molding apparatus 10 includes a die 1 having a hollow 1a, a third actuator 2 that slides the die 1 (X3 direction), an upper punch 3 that slides in the hollow 1a, and an upper punch 3 that slides (X1). Direction) first actuator 4, fixed lower punch 6 partially entering hollow 1 a, floating lower punch 5 sliding in fixed lower punch 6, sliding lower floating punch 5 (X2 direction) second The actuator 7 and the fixed lower punch 6 are placed, and a stopper 8 that defines the lowering limit of the floating lower punch 5 is generally configured.

  Each of the first actuator 4, the second actuator 7, and the third actuator 2 is composed of an electric servo motor.

  In the powder forming apparatus 10, the floating lower punch 5 is also moved down (X2 direction) in synchronization with the lowering of the upper punch 3 (X1 direction) during floating forming, and the floating load is reduced by the lowering of the floating lower punch 5. Is given to F. Further, when the lowering speed of the upper punch 3 is decelerated, the lowering punch 5 is also controlled to be decelerated in synchronization.

  Such control is realized by the fact that both the first actuator 4 and the second actuator 7 are composed of servo actuators (electric servo motors).

  In addition, the die 1 is also lowered by the electric servo motor 2 (X3 direction) in synchronization with the lowering of the floating lower punch 5 and the upper punch 3, whereby the powder F is gradually compacted from the vicinity of the upper punch 3 and pressed. When the powder C is manufactured (see FIG. 3), it is possible to suppress the occurrence of density distribution such that the density of the green compact C decreases in order from the vicinity of the upper punch 3.

  As shown in FIG. 1, a cavity is formed in the hollow 1a of the die 1, the upper surface of the floating lower punch 5, and the upper surface of the fixed lower punch 6, and the powder F to be molded is filled in the cavity.

  Next, as shown in FIG. 2, the powder F is pressed down while the upper punch 3 is lowered to apply a pressing force P, and the floating lower punch 5 is also floated with respect to the powder F while being lowered in synchronization with the upper punch 3. While the load P ′ is applied and the floating load P ′ is applied to the powder F, the lowering control of the upper punch 3, the floating lower punch 5 and the die 1 is executed.

  When the pressurization of the powder F proceeds and the floating lower punch 5 approaches a predetermined distance from the stopper 8 ((1) in FIG. 4), the lowering speed of the upper punch 3 from the second actuator 7 is controlled. A command signal for decelerating the descending speed is transmitted to the first actuator 4 ((2) in FIG. 4).

  Here, the above-mentioned “predetermined distance” refers to the speed of the upper punch 3 after deceleration, the time required for the upper punch 3 to decelerate, the distance that the floating lower punch 5 descends, the amount of elastic deformation of the floating lower punch 5, etc. Set in consideration.

  The upper punch 3 starts to decelerate the lowering speed by the control of the first actuator 4 receiving the command signal ((3) in FIG. 4), and a constant floating load is applied according to the lowering of the lowering speed of the upper punch 3. Control is performed by the second actuator 7 to reduce the descending speed of the floating lower punch 5 so as to be maintained.

  The lowering speed of the upper punch 3 and the lower floating punch 5 is gradually reduced, and the lower floating punch 5 in the low speed state reaches the stopper 8 ((4) in FIG. 4).

  The floating load gradually decreases ((6) in FIG. 4) after the floating lower punch 5 reaches the stopper 8 until the pressurization is completed ((5) in FIG. 4).

  When the pressurization is completed, a green compact C having a predetermined shape is formed as shown in FIG.

  As in the illustrated control method, when the floating lower punch 5 approaches the stopper 8 to a predetermined distance, the first actuator 4 is controlled to decelerate the lowering speed of the upper punch 3, The rapid drop of the floating load as in the conventional control method shown in FIG. 5 is eliminated.

  By eliminating the sudden drop in the floating load in this way, it is possible to eliminate the breakage of the device due to the sudden drop in the floating load.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Die, 1a ... Hollow, 2 ... 3rd actuator (electric servomotor), 3 ... Upper punch, 4 ... 1st actuator (electric servomotor), 5 ... Floating lower punch, 6 ... Fixed lower punch, 7 ... Second actuator (electric servo motor), 8 ... Stopper, 10 ... Powder molding device, F ... Powder, C ... Green compact

Claims (2)

A die having a hollow;
An upper punch and a floating lower punch that slide in a hollow and form a cavity with a die;
A first actuator for pressing the upper punch;
A second actuator for controlling the floating load of the floating lower punch;
A stopper for defining a pressure stop position of the floating lower punch, and at least
The first actuator is operated to press the upper punch and pressurize the powder filled in the cavity, and the load acting on the powder during pressurization becomes the predetermined floating load necessary for molding. In a method of controlling a powder molding apparatus that controls the actuator of No.
A control method for a powder molding apparatus, wherein control is performed to reduce the lowering speed of the upper punch with respect to the first actuator when the floating lower punch approaches a predetermined distance from the stopper.   The method of controlling a powder molding apparatus according to claim 1, wherein both the first actuator and the second actuator are electric servo motors.

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