JP2019051552A - Injection device and die casting machine - Google Patents

Abstract

To provide an injection device capable of improving quality.SOLUTION: Provided is an injection device 9 comprising: a dynamo-electric motor 27 capable of driving a plunger 23 slidable inside a sleeve 21 leading to the inside of a mold 101; and a control apparatus 13 controlling the dynamo-electric motor 27 based on the detection value of injection pressure P over at least a part of a fillings step where, before a metallic material in a liquid state or a solid-liquid coexistent state spreads all over a cavity Ca of a mold 101, the metallic material is filled to the cavity Ca.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to an injection apparatus that injects a metal material in a liquid or solid-liquid coexistence state into a mold, and a die casting machine including the injection apparatus.

  2. Description of the Related Art An injection device that pushes (injects) an unsolidified metal material in a sleeve into a mold by a plunger that can slide in a sleeve that communicates with the mold (for example, Patent Document 1) is known.

  In general, in an injection device for injecting molten metal (liquid metal), the plunger speed (injection speed) until filling of the molten metal into the mold cavity (the part corresponding to the product in the space in the mold) is completed. ) Is controlled, and after filling is completed, pressure control is performed to control the pressure (injection pressure) applied to the molten metal by the plunger. This is because the injection speed has a great influence on the quality before completion of filling, and the injection pressure has a great influence on the quality after filling.

  Patent Document 1 proposes that pressure control is started in an electric die-casting machine when the molten metal has completely spread to the cavity but has not completely spread to the hot water pool (overflow). Japanese Patent Application Laid-Open No. H10-228667 claims that the quality of the product can be ensured by performing speed control until the molten metal reaches the cavity completely.

JP 2008-126294 A

  When the injection speed is high, for example, seizure occurs due to friction between the unsolidified metal material and the mold, and the product quality may be deteriorated. In addition, when the injection speed is low, for example, blisters that are a kind of nest are generated, and there is a possibility that the quality of the product is also deteriorated. However, even if the operator sets various values as the injection speed, it may be difficult to suppress such quality deterioration. Therefore, it is desired to provide an injection apparatus and a die casting machine that can improve quality.

  An injection device according to an aspect of the present disclosure includes an electric motor capable of driving a plunger that can slide in a sleeve that communicates with a mold, and the metal material in the cavity before the metal material reaches the cavity of the mold. And a control device that performs pressure control for controlling the electric motor based on a detected value of the injection pressure over at least a part of the filling process.

  In one example, the pressure control includes control for converging the injection pressure to a target pressure.

  In one example, the control device starts the pressure control when a detection value of the position of the plunger reaches a predetermined value.

  In one example, the control device starts the pressure control when the detected value of the injection pressure rises to a predetermined value.

  In one example, the control device starts the pressure control when the detected value of the injection speed drops to a predetermined value.

  In one example, when the detected value of the injection speed reaches a predetermined upper limit speed during the pressure control, the control device temporarily controls the injection speed to be equal to or lower than the upper limit speed in preference to the pressure control. Take control.

  In one example, the control device changes the target pressure in accordance with a change in the detected value of the injection pressure.

  In one example, the control device controls the electric motor by speed control that converges the injection speed to a target speed over at least a part of the filling step, and the pressure control is configured to control the injection pressure during the speed control. When the detected value reaches a predetermined upper limit pressure, the control includes temporarily controlling the injection pressure below the upper limit pressure in preference to the speed control.

  A die casting machine according to an aspect of the present disclosure includes the above-described injection device and a mold clamping device that clamps the mold.

  A die casting machine according to an aspect of the present disclosure includes a mold clamping device that clamps the mold and the injection device.

  According to said structure, quality can be improved.

The schematic diagram which shows the principal part structure of the die-casting machine which concerns on embodiment of this indication. The schematic diagram which shows the principal part structure of the injection apparatus of the die-casting machine of FIG. 3A to 3C are schematic diagrams for explaining the operation of the injection apparatus of FIG. The figure which shows the example of the injection waveform in the injection device of FIG. Fig.5 (a)-FIG.5 (e) are figures which show the example of the pressure waveform in a filling process. The flowchart which shows the example of the procedure of the injection process which the injection device of FIG. 2 performs. The flowchart which shows the example of the procedure of the injection process which concerns on a 1st modification. The flowchart which shows the example of the procedure of the injection process which concerns on a 2nd modification. The flowchart which shows the example of the procedure of the pressure control process which concerns on a 3rd modification.

(Overall configuration of die casting machine)
FIG. 1 is a side view partially including a cross-sectional view illustrating a configuration of a main part of a die casting machine 1 according to an embodiment of the present disclosure.

  The die casting machine 1 manufactures a die-cast product (product) by injecting an unsolidified metal material into a mold 101 and solidifying the metal material in the mold 101. The metal is, for example, aluminum or magnesium or an alloy thereof. The unsolidified state is a liquid or solid-liquid coexistence state. The solid-liquid coexistence state is a semi-solid state solidified from liquid or a semi-molten state melted from solid.

  The mold 101 includes, for example, a fixed mold 103 and a moving mold 105. In the description of the present embodiment, for convenience, the cross section of the fixed mold 103 or the movable mold 105 is shown by one type of hatching, but these molds may be of a direct engraving type or a nested type. It may be a thing. Further, the fixed mold 103 and the moving mold 105 may be combined with a core or the like. The space in the mold 101 is, for example, a cavity Ca corresponding to a product, a runner (not shown) that leads a metal material to the cavity Ca, and a gate Gt that is a boundary between the cavity Ca and the runner (see FIG. 2). ), And a puddle (not shown) that draws the metal material ahead.

  The die casting machine 1 includes, for example, a machine main body 3 that performs a mechanical operation for casting, and a control unit 5 that controls the operation of the machine main body 3.

  The machine body 3 includes, for example, a mold clamping device 7 that opens and closes and molds the mold 101, an injection apparatus 9 that injects a metal material into the mold 101, and a die-cast product that is a fixed mold 103 or a movable mold. And an extruding device 11 for extruding from a moving mold 105 in FIG. The configuration of the machine body 3 may be the same as various known configurations except for the configuration of the injection device 9.

  In the casting cycle, the mold clamping device 7 moves the moving mold 105 toward the fixed mold 103 to close the mold. Further, the mold clamping device 7 performs mold clamping by applying a mold clamping force corresponding to the extension amount of the tie bar (reference number omitted) to the mold 101. A cavity Ca is formed in the mold 101 that has been clamped. The injection device 9 injects and fills a metal material into the cavity Ca. The metal material filled in the cavity Ca is deprived of heat by the mold 101 and is cooled and solidified. Thereby, a product is formed. Thereafter, the mold clamping device 7 opens the mold by moving the moving mold 105 away from the fixed mold 103. At this time or thereafter, the extrusion device 11 extrudes the product from the moving mold 105.

  The control unit 5 includes, for example, a control device 13 (see FIG. 2) that performs various calculations and outputs a control command, a display device 15 that displays an image, and an input device 17 that receives an operator's input operation. ing. From another viewpoint, the control unit 5 includes, for example, a control panel (not shown) having a power supply circuit, a control circuit, and the like, and an operation unit 19 as a user interface.

  The control device 13 is provided in a control panel and an operation unit 19 (not shown), for example. The control device 13 may be divided or distributed as appropriate. For example, the control device 13 includes a lower control device for each of the mold clamping device 7, the injection device 9, and the extrusion device 11, and a higher control device that performs control such as synchronization between the lower control devices. May be configured.

  The display device 15 and the input device 17 are provided in the operation unit 19, for example. For example, the operation unit 19 is provided in a fixed portion of the mold clamping device 7. The display device 15 is configured by a touch panel including a liquid crystal display or an organic EL display, for example. The input device 17 is configured by, for example, a mechanical switch and the touch panel.

  When attention is paid to the injection device 9 in the die casting machine 1, the control unit 5 may be regarded as a part of the injection device 9. The same applies to the components of the control unit 5 (the control device 13, the display device 15, or the input device 17). Hereinafter, the control device 13, the display device 15, and / or the input device 17 may be described as a part of the injection device 9.

(Overall configuration of injection device)
FIG. 2 is a schematic diagram showing a configuration of a main part of the injection device 9.

  The injection device 9 includes, for example, a sleeve 21 communicating with the cavity Ca, a plunger 23 that pushes the metal material in the sleeve 21 to the cavity Ca, a drive unit 25 that drives the plunger 23, and a control device 13 that controls the drive unit 25. And have. These configurations are, for example, as follows.

  The sleeve 21 is a cylindrical member inserted through the fixed mold 103, for example. The plunger 23 has a plunger tip 23a that can slide in the front-rear direction within the sleeve 21, and a plunger rod 23b fixed to the plunger tip 23a. The metal material is supplied into the sleeve 21 from the hot water supply port 21a formed on the upper surface of the sleeve 21, and the plunger tip 23a slides (advances) toward the cavity Ca in the sleeve 21, whereby the metal material becomes the cavity Ca. Is injected into.

(Configuration of drive unit)
The drive unit 25 is, for example, an electric type, and includes a rotary electric motor 27, a pulley / belt mechanism 29 that transmits the rotation of the electric motor 27, and a rotation transmitted by the pulley / belt mechanism 29 into a translational motion. And a relay member 33 interposed between the screw mechanism 31 and the plunger 23.

  Although not particularly illustrated, the electric motor 27 includes a stator that constitutes one of a field and an armature, and a rotor that constitutes the other of the field and the armature and rotates with respect to the stator. The electric motor 27 may be of an appropriate type. For example, the electric motor 27 may be a DC motor, an AC motor, a synchronous motor, or an induction motor. However, it may be equipped with a brake.

  Electric power is supplied to the electric motor 27 by a driver 35. For example, the driver 35 can perform feedback control of the number of rotations based on a detection value of a sensor (not shown) (for example, an encoder) that detects the rotation of the electric motor 27. The driver 35 can detect, for example, a current flowing through the electric motor 27 and perform torque feedback control based on the detected value.

  The pulley / belt mechanism 29 includes, for example, a first pulley 37 fixed to the output shaft of the electric motor 27, a belt 39 hung on the first pulley 37, and a second pulley 41 on which the belt 39 is hung. ing. The belt 39 may be, for example, a toothed belt or may have no teeth. The rotation of the electric motor 27 is transmitted from the first pulley 37 to the second pulley 41 via the belt 39.

  The screw mechanism 31 is configured by, for example, a ball screw mechanism or a sliding screw mechanism. The screw mechanism 31 includes, for example, a screw shaft 43 that is coaxially fixed to the second pulley 41 and a nut 45 that is screwed onto the screw shaft 43. The screw shaft 43 is allowed to rotate around the shaft and is restricted from moving in the axial direction, for example, by a bearing (not shown). On the other hand, for example, the nut 45 is restricted from rotating around the axis by a guide (not shown) and is allowed to move in the axial direction. Therefore, when the rotation of the electric motor 27 is transmitted to the screw shaft 43, the nut 45 moves in the axial direction.

  The relay member 33 has, for example, a substantially cylindrical shape, and the rear end is fixed to the nut 45 while accommodating the screw shaft 43 therein. Further, the front end of the relay member 33 is fixed to the rear end of the plunger 23. Therefore, when the nut 45 moves forward, the driving force is transmitted to the plunger 23 via the relay member 33, and the plunger 23 also moves forward.

  The relay member 33 and the plunger 23 are fixed via a coupling 47, for example. The coupling 47 may be the same as that which connects the piston rod of the injection cylinder and the plunger 23 in a general hydraulic injection device, for example. Although a reference numeral is not particularly attached to the distal end of the relay member 33, a connecting portion composed of a shaft portion and a flange is formed in the same manner as the distal end of the piston rod of the injection cylinder.

(Injection device sensor)
The injection device 9 includes, for example, a position sensor 49 that detects the position of the plunger 23 and a force sensor 51 that detects a force applied to the plunger 23.

  The configuration of the position sensor 49 may be appropriate. For example, the position sensor 49 may constitute a magnetic or optical linear encoder together with a scale portion (not shown) provided on the relay member 33, and the distance from the member fixed to the plunger 23 may be set. You may comprise with the laser length measuring device to measure.

  The position sensor 49 or the control device 13 can also acquire (detect) the speed (injection speed) of the plunger 23 that is a differential value of the detected position. In this respect, the position sensor 49 may be regarded as a speed sensor.

  The force sensor 51 includes, for example, a load cell, is interposed between the relay member 33 and the nut 45, and detects forces (compression force and tensile force) transmitted from the nut 45 to the relay member 33. The configuration of the load cell may be appropriate, for example, a strain gauge type. In addition, the load cell may be a spring type, a piezoelectric type, a magnetostrictive type, a capacitance type, or a gyro type.

  The control device 13 can calculate the pressure (injection pressure) applied to the metal material by the plunger 23 based on the force detected by the force sensor 51 and the diameter (cross-sectional area) of the plunger tip 23a. In this viewpoint, the force sensor 51 may be regarded as a pressure sensor. Further, since the diameter of the plunger 23 does not change during the casting cycle, in the present disclosure, the detected value of the injection pressure is synonymous with the detected value of the force.

(Control device)
In the control device 13, for example, a plurality of functional units that perform various operations are constructed by the CPU executing a program stored in the ROM and / or the external storage device. A speed control unit 53 and a pressure control unit 55.

  For example, the speed control unit 53 controls the electric motor 27 so that the injection speed converges to a desired value based on the detection value of the position sensor 49. For example, based on the detection value of the force sensor 51, the pressure control unit 55 controls the electric motor 27 so that the injection pressure converges to a desired value. Note that the feedback control for converging the control amount (injection speed or injection pressure) to a desired value is a result of appearing to control the control amount within a desired range due to a control delay or the like (for example, You may invite a result that seems to regulate the upper limit).

(Operation of injection device)
FIG. 3A to FIG. 3C are schematic views for explaining the operation of the injection device 9. These drawings show how the injection process proceeds from the state of FIG. 2 in the order of FIG. 3A, FIG. 3B, and FIG. 3C.

  When the unsolidified metal material M is supplied to the sleeve 21, the injection device 9 advances the plunger 23 as shown in FIGS. 3 (a), 3 (b) and 3 (c). As a result, the metal material M passes from the state in front of the gate Gt (FIG. 3A) to the cavity Ca through the state in which it flows into the cavity Ca beyond the gate Gt (FIG. 3B). It moves to the state (FIG.3 (c)) with which filling with Ca was completed.

  In a general injection apparatus, speed control is performed to maintain the injection speed at a desired value in the state of FIGS. 3 (a) and 3 (b). Then, when the state shown in FIG. 3C is reached, for example, control for bringing the injection pressure to the final casting pressure (final pressure) is performed.

  In the injection device 9 according to the present embodiment, before the metal material reaches the gate Gt, the command from the speed control unit 53 to the electric motor 27 is indicated by an arrow in FIG. In addition, speed control is performed. However, unlike the conventional case, the injection pressure is set to a desired value before the metal material is filled into the cavity Ca, as indicated by an arrow in FIG. 3B from the pressure control unit 55 to the electric motor 27. To start pressure control. In addition, as shown in FIG.3 (c), after completion | finish of filling, the pressure control for obtaining final pressure (and the desired pressure | voltage rise curve until it reaches final pressure as needed) is performed.

(Example of injection waveform)
FIG. 4 is a diagram showing an example of an injection waveform in the injection device 9.

  In this figure, the horizontal axis is an axis indicating time t (elapsed time from the start of injection). The vertical axis represents the values of the position D of the plunger 23 (distance D from the start of injection), the injection speed V, and the injection pressure P. A line L1 indicates a change with time of the position D. A line L2 indicates a change with time in the injection speed V. A line L3 indicates a change with time in the injection pressure P.

  In FIG. 4, the injection waveform when laminating the molten metal or the injection waveform when filling the solid-liquid coexisting metal is taken as an example. The following description is also the same. This figure basically shows waveforms of detected values of position D, velocity V and pressure P. However, regarding the speed V during the speed control and the pressure P during the pressure control, it may be considered that the waveform of the target value is shown. The same applies to FIGS. 5A to 5E described later.

  Time t0 is an injection start time. In the initial stage of injection (time t0 to time t1), the speed V is controlled to a substantially constant value, for example. The value of the position D increases by an amount corresponding to the speed V. The value of the pressure P is maintained at a value close to zero.

  The time point t1 corresponds approximately when the metal material reaches the gate Gt. When the metal material reaches the gate Gt, the speed V starts to decrease and the pressure P starts to increase because the cross-sectional area of the gate Gt is narrower than the cross-sectional area of the runner. As the speed V decreases, the increase rate of the position D decreases.

  The time point t2 corresponds to when the filling of the metal material into the cavity Ca is almost completed. Since the metallic material basically loses its destination except for an overflow or the like, the velocity V becomes substantially zero and the pressure P rises relatively rapidly. The position D becomes a constant value as the velocity V becomes zero.

(Control during filling process)
The process from when the metal material reaches the gate Gt until the metal material is completely filled into the cavity Ca (time t1 to t2) is referred to as a filling process. In the lower part of the figure, an arrow indicates whether the type of control is speed control or pressure control. As already described with reference to FIG. 3B, in general, speed control is performed in the filling process. In the present embodiment, pressure control is performed in the filling process.

  For example, the operator sets the target speed in the speed control and the target pressure in the pressure control with respect to the elapsed time or the position of the plunger 23 via the input device 17. In addition, about the target pressure in a filling process, the control apparatus 13 may set automatically. For example, the control device 13 may set a value obtained by multiplying a final casting pressure (final pressure) set by the operator by a predetermined ratio (<1) as a target pressure in the filling process.

(Pressure control start time)
The pressure control may be performed in at least a part of the filling process. Therefore, the start point of the pressure control may be before the time point t1, may be the time point t1 (example shown in the figure), or after the time point t1 (but before the time point t2). There may be.

  In the present disclosure, the operation in which the pressure control is performed in at least a part of the filling process is a concept of starting the pressure control when the filling is completed, but for compensation of a control error or a control delay. It shall not include those whose pressure control is started before filling is completed. The determination can be made based on the pressure control start condition or the like, but it may be determined by simply comparing the pressure control start time and the filling completion time. For example, if the pressure control is started from 10% or more or 50% or more of the length of the filling process before the completion of filling, the pressure control is performed in at least a part of the filling process as in this embodiment. It may be determined that

  The injection device 9 (control device 13) may appropriately determine whether or not the pressure control start time has come.

  For example, when the plunger 23 moves forward to a predetermined position, the metal material reaches the gate Gt and filling is started. Therefore, the control device 13 may start the pressure control when the detection value of the position sensor 49 reaches the predetermined value Dt.

  In addition, for example, when the metal material reaches the gate Gt, the injection speed decreases. Therefore, the control device 13 may start the pressure control when the detection value of the injection speed based on the detection value of the position sensor 49 has decreased to the predetermined value Vt.

  For example, when the metal material reaches the gate Gt, the injection pressure increases. Therefore, the control device 13 may start the pressure control when the detected value of the injection pressure based on the detected value of the force sensor 51 rises to the predetermined value Pt.

  Further, for example, in the case where speed control is substantially performed by position control in which the plunger 23 is positioned at a target position that changes from moment to moment, the metal material reaches the gate Gt after a predetermined time has elapsed from the start of injection. . Therefore, the control device 13 may start the pressure control when the time t reaches a predetermined value (for example, time t1).

  In FIG. 4, values near the start of filling are illustrated as the predetermined values Dt, Vt, Pt, and the like. However, these values do not have to be values near the start of filling, and may be values when filling has progressed to some extent, for example. In addition to or instead of the predetermined values Dt, Vt, and Pt, the rate of change of these values may be considered.

  The predetermined values Dt, Vt, Pt and the like are input and held in the control device 13 by the operator via the input device 17, for example. Further, for example, the control device 13 may automatically set based on casting conditions.

  For example, the control device 13 inputs the filling mass of the metal material ahead of the gate Gt, the diameter of the plunger tip 23a, the type (density) of the metal material, and the biscuit thickness (position at the completion of filling), which are input via the input device 17. Based on D), the position where the metal material reaches the gate Gt may be calculated, and the calculated position may be set as the predetermined value Dt.

  Further, for example, the control device 13 may calculate the predetermined value Vt based on the target value of the injection speed immediately before the filling process set via the input device 17. More specifically, for example, a value obtained by multiplying the target value by a predetermined ratio (<1) may be set as the predetermined value Vt.

  For example, the control device 13 may calculate the predetermined value Pt based on the target value of the injection pressure set during or after the filling process, which is set via the input device 17. More specifically, for example, a value obtained by multiplying the target value by a predetermined ratio (<1) may be set as the predetermined value Pt.

(Example of pressure waveform)
Fig.5 (a)-FIG.5 (e) are figures which show the various examples of the pressure waveform in a filling process. In these figures, the change with time of pressure P is shown centering on the period from time t1 to time t2 in FIG.

  FIG. 5A illustrates an aspect in which the injection pressure is maintained constant throughout the entire filling process. FIG. 5B illustrates a mode in which the injection pressure is increased linearly throughout the entire filling process. FIG. 5C illustrates a mode in which the change over time in the injection pressure becomes a curved shape that swells upward substantially throughout the entire filling process. FIG.5 (d) has illustrated the aspect which becomes a curvilinear shape with which the time-dependent change of injection pressure dents substantially throughout the filling process. FIG. 5E illustrates an aspect in which the injection pressure changes in multiple stages during the filling process. Thus, various pressure waveforms during the filling process may be set.

(Processing procedure)
FIG. 6 is a flowchart showing an example of the procedure of an injection process executed for the injection device 9 (control device 13) to inject a metal material into the mold 101. This process is executed every time a casting cycle is performed in the die casting machine 1.

  In step ST1, the control device 13 determines whether or not the injection start condition is satisfied. The injection start condition is, for example, that a metal material for one shot is supplied to the sleeve 21 by a hot water supply device (not shown). If the determination is affirmative, the control device 13 proceeds to step ST2. If the determination is negative, the control device 13 waits and repeats step ST1.

  In step ST2, the control device 13 (speed control unit 53) performs speed control (time points t0 to t1 in FIG. 4). Specifically, for example, the control device 13 controls the rotation speed of the electric motor 27 based on the detection speed of the position sensor 49 so that the injection speed converges to the target speed. That is, the control device 13 performs speed feedback control. As already described, based on the detection position of the position sensor 49, position control may be performed to a target position that changes from time to time, and speed feedback control may be performed substantially.

  In step ST3, the control device 13 determines whether or not a switching condition for switching from speed control to pressure control is satisfied. As described with reference to FIG. 4, the switching conditions are, for example, that the position D has reached the predetermined value Dt, that the speed V has decreased to the predetermined value Vt, that the pressure P has increased to the predetermined value P, etc. It is. If the determination is affirmative, the control device 13 proceeds to step ST4. If the determination is negative, the control device 13 returns to step ST2 and continues the speed control.

  In step ST4, the control device 13 (pressure control unit 55) performs pressure control (time t1 to time t1 in FIG. 4). Specifically, for example, the control device 13 controls the torque of the electric motor 27 based on the force detected by the force sensor 51 so that the injection pressure converges to the target pressure. That is, the control device 13 performs pressure feedback control. In this pressure control, for example, subsequent to the pressure control during the filling process (time t1 to t2), control for pressure increase and holding pressure (time t2) after the filling process is also performed. The pressure holding may be performed not by pressure control of the electric motor 27 but by a brake.

  In step ST5, the control device 13 determines whether or not the injection end condition is satisfied. The injection end condition is, for example, that a predetermined time has elapsed from a predetermined time (for example, an injection start time or a time when the final pressure is obtained). And the control apparatus 13 complete | finishes pressure control (specifically holding | maintenance pressure) in the case of affirmation determination, and returns to step ST4 and continues pressure control in the case of negative determination.

  As described above, in this embodiment, the injection device 9 is in the liquid or solid-liquid coexistence in the electric motor 27 that can drive the plunger 23 that can slide in the sleeve 21 that communicates with the mold 101 and the cavity Ca of the mold 101. The control device 13 that performs pressure control for controlling the electric motor 27 based on the detected value of the injection pressure P over at least a part of the filling process in which the cavity Ca is filled with the metal material before the metal material in the state is spread. And have.

  Therefore, for example, the injection speed is suitably adjusted by pressure control, and the quality can be improved. Specifically, it is as follows.

  For example, when the cavity Ca has a thin part (for example, a part having a cross-sectional area smaller than the cross-sectional area of the gate Gt), when the metal material reaches the thin part, the speed V (injection speed) of the plunger 23 is constant. However, the speed of the metal material in the thin portion increases. As a result, for example, burn-in occurs. On the other hand, if the injection speed is slowed down, blisters, which are a kind of nest, are generated.

  In general, the injection speed during the filling process is constant. Here, it is conceivable to solve the above problem by changing the target speed during the filling process to various values according to the position of the plunger 23. However, setting such a target speed is very difficult for the operator and places a heavy burden on the operator. Furthermore, every time the mold is replaced, such a difficult or burdensome setting must be made.

  On the other hand, since the pressure control is performed in the injection device of the present embodiment, for example, when the target pressure is a constant value, if the metal material reaches a thin part and the injection pressure increases, the injection pressure is reduced. The torque of the electric motor 27 is reduced so as to suppress the increase. As a result, an increase in the speed of the metal material flowing into the narrow portion is also suppressed. That is, the speed adjustment according to the shape of the cavity Ca and the arrival state of the metal material in the cavity Ca is automatically performed. As a result, for example, image sticking and blistering are suppressed.

  Note that the above-described effects are similarly achieved not only when the target pressure is a constant value, but also when the target pressure changes over time (position of the plunger 23). For example, even if the target pressure increases with respect to the elapsed time, if the increase amount is smaller than the pressure increase amount when the speed control is performed to make the injection speed constant, the burn-in is suppressed. .

  The control device 13 may start pressure control when the detected value of the position D of the plunger 23 reaches a predetermined value Dt. In this case, for example, the pressure control can be started without delaying the arrival of the metal material to the gate Gt. Since it is not necessary to change the injection speed or the injection pressure due to the metal material reaching the gate Gt for the determination of the start of the pressure control, it is easy to start the pressure control before the metal material reaches the gate Gt. It is.

  Further, the control device 13 may start pressure control when the detected value of the injection pressure P rises to a predetermined value Pt. In this case, for example, the pressure control can be started not only when the metal material reaches the gate Gt but also when the metal material reaches a narrow portion of the cavity Ca. For example, since the injection pressure is used as a reference, it is easy to smooth the pressure waveform before and after switching to pressure control.

  Further, the control device 13 may start the pressure control when the detected value of the injection speed V drops to the predetermined value Vt. In this case, for example, the pressure control can be started not only when the metal material reaches the gate Gt but also when the metal material reaches a narrow portion of the cavity Ca. For example, since the injection speed is used as a reference, it is possible to perform deceleration control before the start of pressure control and smooth the speed waveform before the start of pressure control.

(First modification of injection processing)
FIG. 7 is a flowchart showing an example of the procedure of the injection process according to the first modification, and corresponds to FIG.

  In the injection process of FIG. 6, speed control is performed in the initial stage of injection, and then pressure control is performed when a predetermined switching condition is satisfied. On the other hand, in the injection process of FIG. 7, pressure control is basically performed from the start of injection. In this case, the injection speed may increase more than necessary before the metal material reaches the gate Gt and the injection pressure increases. Therefore, when the injection speed reaches a predetermined upper limit speed, control is performed to temporarily control the injection speed to be equal to or lower than the upper limit speed in preference to the pressure control. Specifically, it is as follows.

  Step ST11 is the same as step ST1 of FIG. 6, and in this step, it is determined whether or not the injection start condition is satisfied. However, when an affirmative determination is made, pressure control (step ST12) is performed unlike FIG. That is, pressure control is performed from the start of injection. Step ST12 itself is the same as step ST4 of FIG. 6, for example.

  In step ST13, the control device 13 determines whether or not the detection speed of the position sensor 49 exceeds a predetermined upper limit speed Vmax. If the determination is affirmative, the control device 13 proceeds to step ST14. If the determination is negative, the control device 13 returns to step ST12 and continues the pressure control.

  The upper limit speed Vmax may be set by the operator, may be set in advance by the manufacturer of the injection device 9, or may be set by the control device 13 based on various conditions. The affirmative determination is made in step ST13 basically before the metal material reaches the gate Gt and the filling resistance increases (before the filling step).

  In step ST14, the control device 13 performs control for restricting the injection speed to the upper limit speed or less. In this control, for example, an upper limit speed or a speed lower by a predetermined amount than the upper limit speed may be set as a target speed, and speed feedback control similar to step ST2 of FIG. 6 may be performed for a predetermined time. Further, for example, instead of speed control, the target pressure may be temporarily reduced to a predetermined amount or to a predetermined pressure, and the pressure control may be continued. Further, for example, the operation amount (voltage, current and / or frequency) may be lowered by a predetermined amount.

  In addition, no matter what control is performed in step ST14, since the upper limit of the injection speed is regulated in the whole of steps ST13 and ST14, the whole of steps ST13 and ST14 may be regarded as speed control. . Further, even if the pressure control is performed in step ST14, in the present disclosure, it is expressed as different from the pressure control in step ST12.

  Step ST15 is the same as step ST5 of FIG. 6, and in this step, it is determined whether or not the injection end condition is satisfied. If a negative determination is made, the control device 13 returns to step ST12.

  As long as the injection speed V does not exceed the upper limit speed Vmax until the injection end condition is satisfied in steps ST12 to ST15, the pressure control is continued as in step ST4 of FIG. Then, pressure control, pressure increase, and pressure holding during the filling process are sequentially performed, and while the pressure holding is being performed, an affirmative determination is made in step ST15, and the process ends.

  As described above, the pressure control may be performed from the start of injection instead of starting after the speed control. According to the first modification, for example, it is not necessary to set the start point of pressure control, and the burden on the operator is reduced. In the second modification, the injection speed is restricted to the upper limit speed or less by the control of the control device 13, but the restriction may be made mechanically.

(Second modification of injection processing)
FIG. 8 is a flowchart showing an example of the procedure of injection processing according to the second modification, and corresponds to FIG.

  In the embodiment, the pressure control is control for converging the injection pressure to the target pressure. On the other hand, in the second modification, the pressure control is a control for restricting the injection pressure to be equal to or lower than a predetermined upper limit pressure (within a predetermined range). Specifically, it is as follows.

  Steps ST21 and ST22 are the same as steps ST1 and ST2 in FIG. That is, speed control is performed in the initial stage of injection.

  In step ST23, the control device 13 determines whether or not the detected pressure P of the force sensor 51 exceeds a predetermined upper limit pressure Pmax. Then, the control device 13 proceeds to step ST24 when the determination is affirmative, and skips step ST24 when the determination is negative.

  The upper limit pressure Pmax may be set by the operator, may be set in advance by the manufacturer of the injection device 9, or may be set by the control device 13 based on various conditions. The affirmative determination is made in step ST23 basically after the metal material reaches the gate Gt and the injection resistance increases (after the filling process starts).

  In step ST24, the control device 13 performs control for restricting the injection pressure to be equal to or lower than the upper limit pressure. In this control, for example, an upper limit pressure or a pressure lower than the upper limit pressure by a predetermined amount may be set as a target pressure, and pressure feedback control similar to step ST4 in FIG. 6 may be performed for a predetermined time. Further, for example, instead of the pressure control, the target speed may be temporarily reduced to a predetermined amount or to a predetermined speed, and the speed control may be continued. Further, for example, the operation amount (voltage, current and / or frequency) may be lowered by a predetermined amount.

  In addition, no matter what control is performed in step ST24, since the upper limit of the injection pressure is regulated in the whole of steps ST23 and ST24, the whole of steps ST23 and ST24 may be regarded as pressure control. This pressure control is also an example of the pressure control performed over at least a part of the filling step in the present disclosure.

  In step ST25, the control device 13 determines whether or not a predetermined pressure increase start condition is satisfied. When the determination is affirmative, the control device 13 proceeds to step ST25. When the determination is negative, the control device 13 returns to step ST22 and continues the speed control.

  The pressure increase start condition may be set by the operator via the input device 17, may be set in advance by the manufacturer, or may be set by the control device 13 based on various conditions. For example, the pressure increase start condition is set so as to substantially match when the metal material is filled into the cavity Ca (when the filling process is completed). More specifically, the pressure increase start condition is, for example, that the position D of the plunger 23 has reached a predetermined position, that the injection pressure has increased to a predetermined value, or that the injection speed has decreased to a predetermined value.

  In step ST26, the control device 13 performs pressure control for increasing pressure and holding pressure. This step corresponds to a portion after completion of the filling process in the pressure control in step ST4 of FIG.

  Step ST27 is the same as step ST5 of FIG. 6, and in this step, it is determined whether or not the injection end condition is satisfied. However, if a negative determination is made, the control device 13 returns to step ST26 and performs pressure control for increasing pressure or holding pressure.

  As described above, the pressure control during the filling process may regulate the upper limit of the injection pressure in the speed control. According to the second modification, for example, the operator can set the speed until the filling process is completed and the pressure after the pressure increase is started, as in a general injection device.

(Modification of pressure control process)
In the embodiment, it has been described with reference to FIG. 5 (e) that the target pressure may be set in multiple stages. Further, in the embodiment, it has been described that the target pressure may be set with respect to the elapsed time or the position of the plunger 23 by an input to the input device 17 by the operator (or by the control device 13). In other words, it has been described that the control device 13 may change the target pressure according to the elapsed time or the position of the plunger 23 during the pressure control. In this modification, the control device 13 changes the target pressure according to the detected pressure.

  FIG. 9 is a flowchart illustrating an example of a procedure of pressure control processing according to the third modification. This process is executed in, for example, step ST4 in FIG. 6 or step ST12 in FIG. Here, a case where the detected pressure is controlled to follow a two-stage target pressure (a first target pressure P1 and a second target pressure P2 higher than the first target pressure P1) is taken as an example.

  In step ST31, the control device 13 controls the torque of the electric motor 27 so that the detected pressure P of the force sensor 51 follows the preset first target pressure P1. That is, the control device 13 performs pressure feedback control.

  Since feedback control is performed, ideally, the detected pressure P is constant (follows the first target pressure) and does not vary. However, actually, for example, as already described, when the metal material reaches the narrow portion of the cavity Ca, the detected pressure P tends to increase rapidly. And the detected pressure P can be fluctuate | varied by the time delay of control.

  In step ST32, the control device 13 determines whether or not the change amount ΔP of the detected pressure P within a predetermined time exceeds a predetermined threshold value ΔPh. If the determination is negative, the control device 13 returns to step 31 to continue the control for causing the detected pressure P to follow the first target pressure P1, and if the determination is affirmative, the control device 13 proceeds to step ST33.

  In step ST33, the control device 13 controls the torque of the electric motor 27 so that the detected pressure P of the force sensor 51 follows the preset second target pressure P2. That is, the control device 13 performs pressure feedback control.

  As described above, in the present modification, the target pressure is switched from the first target pressure P1 to the second target pressure P2 when the change amount ΔP of the detected pressure P within the predetermined time exceeds the threshold Ph. In other words, the control device 13 switches the target pressure when the metal material reaches a predetermined position (a narrow portion in the cavity Ca).

  In the above modification, for example, since pressure control is first performed in the filling process, as in the embodiment, the progress of the metal material in the cavity Ca as compared with the case where speed control is performed in the filling process. Accordingly, the speed of the metal material is automatically adjusted, and seizure and blistering are suppressed.

  Further, for example, by changing (for example, increasing) the injection pressure in multiple stages in the filling process, for example, compared with a case where a relatively low constant injection pressure is continued, the metal material is distributed to each part of the cavity Ca. It is easy to reliably compress into the shape of the product. Further, for example, as compared with a case where a relatively high constant injection pressure is continued, injection is performed at an unnecessarily high speed, and the possibility of air entrainment and / or seizure is reduced.

  Furthermore, by switching the target pressure according to the change amount ΔP, the injection pressure can be increased according to the progress of the metal material in the cavity Ca. That is, multistage control of injection pressure can be performed at an appropriate timing without requiring a difficult and complicated operation such as predicting the progress of the metal material in the cavity Ca with respect to the position of the plunger 23.

  A mode is conceivable in which speed control is performed in the filling step, and the target speed is automatically switched according to the pressure of the metal material. In this case, for example, when a pressure rise occurs in the metal material, the control device 13 appears at the detection position of the electric motor 27, and when the torque calculated from the detection position of the electric motor 27 changes, A rise in pressure will be detected. On the other hand, in the present modification, the control device 13 uses the detected pressure for pressure control, and therefore can immediately detect a pressure increase based on the detected pressure. As a result, more accurate control is possible.

  Note that the predetermined time of the change amount ΔP within the predetermined time and / or the threshold value ΔPh may be appropriately set by the operator via the input device 17, for example, or the control device 13 may automatically set based on the target pressure. May be set. Further, the predetermined time may be appropriately set in consideration of, for example, a control delay or the like, and may be shorter, equal, or longer than the time step of feedback control.

  Although not particularly illustrated, it is determined in step ST32 whether or not the elapsed time and / or the position of the plunger 23 has exceeded a predetermined value so that a positive determination is not made in step ST32 due to a relatively large deviation at the start of pressure control. May be combined.

  In the above, the two-stage control is exemplified, but the control may be three or more stages. Further, for example, in the aspect in which the target pressure is gradually changed as shown in FIGS. 5B to 5D, the change rate (slope) may be switched according to the detected pressure. The operation for changing the rate of change is also an operation for changing the target pressure in a broad sense.

  The present invention is not limited to the above embodiments and modifications, and may be implemented in various aspects.

  The die casting machine is not limited to horizontal mold clamping horizontal injection, and may be vertical mold clamping vertical injection, horizontal mold clamping vertical injection, vertical mold clamping horizontal injection, for example. The configuration other than the injection device (mold clamping device, extrusion device, etc.) is arbitrary. For example, the drive unit in the die casting machine may be a hydraulic type or an electric type except for the drive unit of the injection device. Further, for example, the mold clamping device may be a toggle type, or a compound type in which mold opening / closing and mold clamping are performed by separate drive units.

  The injection device includes an electric motor that can drive the plunger, and may be any configuration that can detect the injection pressure, and the configuration of the embodiment is merely an example.

  For example, the drive unit of the injection device may be sequentially driven as the injection progresses (some periods may overlap), and may include a plurality of electric motors having different performance from each other. You may have the same kind of several electric motor by which the same control is made.

  The electric motor is not limited to a rotary type, and may be a linear motor. The conversion mechanism that converts the rotation of the rotary electric motor into a linear motion is not limited to a screw mechanism, and may be a rack and pinion mechanism or a link mechanism, for example. In the screw mechanism, the role of the screw shaft and the nut (which rotates or linearly moves) may be opposite to that of the embodiment. A transmission mechanism that transmits the rotation of the electric motor to a conversion mechanism (for example, a screw shaft) may not be provided. The transmission mechanism is not limited to a pulley / belt mechanism, and may be, for example, a gear mechanism or a winding transmission mechanism (for example, a sprocket / chain mechanism) other than the pulley / belt mechanism.

  The injection waveform is not limited to laminar flow filling or solid-liquid coexisting metal. For example, general low-speed injection, high-speed injection, deceleration injection (one that performs deceleration control, or one that does not perform deceleration control but is decelerated by the pressure of the metal material), one that sequentially increases pressure and holds pressure It may be. Even in this case, for example, pressure control may be started in the same manner as in the embodiment in deceleration injection, or pressure control may be performed in the same manner as in the second modification before the start of pressure increase.

  As described in the embodiment, the effect of automatically adjusting the speed by pressure control and thereby reducing image sticking and blistering may not necessarily be achieved. For example, in the third modified example, the second target pressure P2 is a pressure difference that is larger than the pressure increase amount when the speed when the affirmative determination is made in step ST32 and is larger than the first target pressure P1. It may be. Even in this case, for example, there is an effect that the target pressure can be changed (at an appropriate timing) according to the progress of the metal material in the cavity.

DESCRIPTION OF SYMBOLS 1 ... Die casting machine, 9 ... Injection apparatus, 13 ... Control apparatus, 21 ... Sleeve, 23 ... Plunger, 27 ... Electric motor, 101 ... Mold.

Claims (9)

An electric motor capable of driving a plunger slidable in a sleeve communicating with the mold;
Pressure control is performed to control the electric motor based on the detected value of the injection pressure over at least a part of the filling process in which the metal material is filled in the cavity before the metal material reaches the cavity of the mold. A control device;
Having an injection device. The injection apparatus according to claim 1, wherein the pressure control includes control for converging the injection pressure to a target pressure. The injection device according to claim 2, wherein the control device starts the pressure control when a detected value of the position of the plunger reaches a predetermined value. The injection device according to claim 2, wherein the control device starts the pressure control when the detected value of the injection pressure rises to a predetermined value. The injection device according to claim 2, wherein the control device starts the pressure control when a detection value of the injection speed falls to a predetermined value. When the detected value of the injection speed reaches a predetermined upper limit speed during the pressure control, the control device temporarily controls the injection speed to be equal to or lower than the upper limit speed in preference to the pressure control. The injection device according to any one of claims 2 to 5. The injection device according to any one of claims 2 to 6, wherein the control device changes the target pressure in accordance with a change in a detected value of the injection pressure. The control device controls the electric motor by speed control for converging an injection speed to a target speed over at least a part of the filling step,
In the pressure control, when the detected value of the injection pressure reaches a predetermined upper limit pressure during the speed control, the control for temporarily controlling the injection pressure below the upper limit pressure in preference to the speed control. The injection device according to claim 1. The injection device according to any one of claims 1 to 8,
A mold clamping device for clamping the mold;
Have a die casting machine.

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