JP2011045914A - Injection apparatus of molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection apparatus of a molding machine in which any tank can be eliminated. <P>SOLUTION: The injection apparatus 1 includes an injection cylinder device 7 capable of driving an injection plunger 5, a conversion cylinder device 9 for feeding working fluid to the injection cylinder device 7, a first communication passage 57 for communicating a rod side chamber 25r of the injection cylinder device 7 with a rear side chamber 27r of the conversion cylinder device 9, and a motor 11 capable of driving a conversion piston 29 of the conversion cylinder device 9. In the injection motion of the injection apparatus, the working fluid in the rod side chamber 25r is discharged to the rear side chamber 27r via the first communication passage 57, and a space SP in which any working fluid is not present is formed in the rear side chamber 27r according to the insufficient amount of the working fluid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an injection device for a molding machine. The molding machine is, for example, a die casting machine or an injection molding machine.

  As an injection device for extruding a molding material into a cavity by an injection plunger, a hybrid type combining an electric motor and a cylinder device is known (Patent Document 1).

  The injection device of Patent Document 1 includes an injection cylinder device connected to an injection plunger, a conversion cylinder device communicated with the injection cylinder device, and an electric motor that drives a conversion piston of the conversion cylinder device. The conversion cylinder device is driven by the electric motor, whereby hydraulic fluid is supplied from the conversion cylinder device to the injection cylinder device, and the injection plunger is driven.

JP 2008-155280 A

  The injection device disclosed in Patent Document 1 discharges hydraulic fluid pushed out of a cylinder chamber by a piston of an injection cylinder device to a tank at the time of injection. That is, since the technique of Patent Document 1 requires a tank, the injection apparatus becomes large and complicated.

  The objective of this invention is providing the injection apparatus of the molding machine which can abbreviate | omit a tank.

  An injection device of a molding machine according to the present invention is an injection device for extruding a molding material into a cavity by an injection plunger, an injection piston rod connected to the injection plunger, an injection piston to which the injection piston rod is fixed, and the An injection cylinder tube that slidably accommodates an injection piston is provided, and the inside of the injection cylinder tube is divided into a rod side chamber on the side where the injection piston rod extends by the injection piston and a head side chamber on the opposite side. It has a partitioned injection cylinder device, a conversion cylinder tube communicating with the head side chamber, and a conversion piston slidably accommodated in the conversion cylinder tube, and the conversion cylinder tube is formed by the conversion piston. A first cylinder chamber communicating with the head side chamber and a second cylinder chamber on the opposite side A defined conversion cylinder device, a first communication passage communicating the rod side chamber and the second cylinder chamber, a driven portion fixed to the conversion piston and extending to the outside of the conversion cylinder tube, An electric motor capable of driving the driven portion in the sliding direction of the conversion piston, and the electric motor drives the conversion piston toward the first cylinder chamber and operates from the first cylinder chamber to the head side chamber. When the liquid is supplied and the injection piston moves forward to the rod side chamber side, the injection plunger moves forward and the molding material is injected into the cavity. Is discharged to the second cylinder chamber via the first communication passage, and a space in which no hydraulic fluid is present is formed in the second cylinder chamber according to the shortage of the hydraulic fluid.

  Preferably, the space is a vacuum.

  Preferably, after the injection, the conversion piston is driven to the second cylinder chamber side by the electric motor, the space disappears, the second cylinder chamber is filled with the working fluid, and the second cylinder chamber The working fluid is supplied to the rod side chamber, and the injection piston moves backward.

  Preferably, the conversion cylinder tube has a small-diameter cylinder portion that communicates with the head side chamber, and a large-diameter cylinder portion that communicates with the small-diameter cylinder portion and has a larger diameter than the small-diameter cylinder portion. And a small-diameter portion that can slide the small-diameter cylinder portion, and a large-diameter portion that can slide the large-diameter cylinder portion.

  Preferably, the second communication passage that communicates the second cylinder chamber with the front chamber on the small diameter cylinder portion side of the large diameter portion of the large diameter cylinder portion, and opens and closes the second communication passage. A control device that controls the directional control valve and the electric motor and the directional control valve, wherein the control device communicates the front chamber and the small-diameter cylinder, and the front chamber and the second cylinder chamber. In the state where the conversion piston is moved to the injection cylinder tube side by the driving force of the electric motor to perform injection, the small diameter portion is inserted into the small diameter cylinder portion, and the front chamber and the small diameter cylinder are inserted. The pressure is increased by moving the conversion piston to the injection cylinder tube side by the driving force of the electric motor in a state where the part is blocked and the front chamber and the second cylinder chamber are in communication with each other. Said Controlling the motive and the directional control valve.

  Preferably, when performing the injection, the control device switches from the low speed to the high speed by switching the rotation speed of the electric motor from a low speed to a high speed while keeping the control of the hydraulic circuit constant. Switch.

  Preferably, the driven portion protrudes from the conversion piston toward the first cylinder chamber, and extends from the end surface of the conversion cylinder tube on the first cylinder chamber side to the outside of the conversion cylinder tube.

  Preferably, a screw shaft provided in the driven part, and a nut screwed to the screw shaft and driven to rotate by the electric motor, the screw shaft being an axis of the conversion piston On the other hand, it is provided coaxially.

  Preferably, a dog rod fixed to the conversion piston and extending from the conversion cylinder tube in a sliding direction of the conversion piston, and a portion of the dog rod extending to the outside of the conversion cylinder tube The dog rod is provided and a switch operated by the dog, and the dog rod extends from the conversion cylinder tube at a position eccentric with respect to the axis of the conversion piston.

  According to the present invention, the tank can be omitted.

The schematic diagram which shows the structure of the injection apparatus of the die-casting machine which concerns on embodiment of this invention. The figure which shows the injection pressure and injection speed of the injection apparatus of FIG. The figure explaining operation | movement of the injection device of FIG. The figure which shows typically the state at the time of the injection | emission of the injection device of FIG. The figure which shows the modification of this invention.

  FIG. 1 is a diagram showing a configuration of a main part of an injection apparatus 1 for a die casting machine according to an embodiment of the present invention.

  The injection apparatus 1 is an apparatus that injects and fills molten metal into a cavity 105 formed by a fixed mold 101 and a moving mold 103. The fixed mold 101 and the movable mold 103 are opened / closed and clamped by a mold clamping device (not shown) of a die casting machine.

  The injection device 1 includes an injection sleeve 3 that communicates with the cavity 105, an injection plunger 5 that pushes molten metal (a molten metal material) into the cavity 105 in the injection sleeve 3, an injection cylinder device 7 that drives the injection plunger 5, And a conversion cylinder device 9 for supplying hydraulic fluid (for example, oil) to the injection cylinder device 7. The injection device 1 includes a motor (electric motor) 11 and a transmission mechanism 13 that transmits the driving force of the motor 11 to the conversion cylinder device 9. The injection device 1 further includes a hydraulic circuit 17 that controls the flow of hydraulic fluid in the injection cylinder device 7 and the conversion cylinder device 9, and a control device 19 that controls the motor 11 and the hydraulic circuit 17.

  The injection sleeve 3 is provided so as to be inserted through the fixed mold 101, for example. The injection plunger 5 has a plunger tip 5a that slides on the injection sleeve 3, and a plunger rod 5b that is fixed to the plunger tip 5a. When the molten metal is supplied to the injection sleeve 3 from a hot water supply port (not shown) formed in the injection sleeve 3, the plunger tip 5 a slides in the injection sleeve 3 toward the cavity 105, so that the molten metal enters the cavity 105. Injection and filling.

  The injection cylinder device 7 slidably accommodates an injection piston rod 21 connected to a plunger rod 5b of the injection plunger 5 via a coupling, an injection piston 23 to which the injection piston rod 21 is fixed, and an injection piston 23. An injection cylinder tube 25 is provided. The injection piston rod 21 and the injection piston 23 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other.

  The injection cylinder tube 25 has, for example, a circular cross section. The inside of the injection cylinder tube 25 is partitioned by the injection piston 23 into a rod side chamber 25r on the side where the injection piston rod 21 extends and a head side chamber 25h on the opposite side. By selectively supplying hydraulic fluid to the rod side chamber 25r and the head side chamber 25h, the injection piston 23 slides in the injection cylinder tube 25.

  The conversion cylinder device 9 has a conversion cylinder tube 27 communicating with the head side chamber 25 h and a conversion piston 29 slidably accommodated in the conversion cylinder tube 27. When the conversion piston 29 moves forward (moves to the head side chamber 25h), the working fluid in the conversion cylinder tube 27 is supplied to the head side chamber 25h, and the injection piston 23 moves forward (moves in the direction of pushing out the injection plunger 5).

  The conversion cylinder tube 27 is formed, for example, so as to have a circular cross section and to protrude toward the front side (the head side chamber 25h side). That is, the conversion cylinder tube 27 has a small-diameter cylinder portion 27a that communicates with the head-side chamber 25h, and a large-diameter cylinder portion 27b that communicates with the small-diameter cylinder portion 27a and has a larger diameter than the small-diameter cylinder portion 27a.

  The conversion piston 29 is also formed to be convex forward corresponding to the shape of the conversion cylinder tube 27. That is, the conversion piston 29 has a small diameter portion 29a that can slide the small diameter cylinder portion 27a and a large diameter portion 29b that can slide the large diameter cylinder portion 27b.

  As shown by a two-dot chain line, the conversion piston 29 is movable between a state where the small diameter portion 29a is inserted into the small diameter cylinder portion 27a and a state where the small diameter portion 29a is pulled out from the small diameter cylinder portion 27a. That is, the conversion piston 29 is accommodated in the conversion cylinder tube 27 so that the small diameter portion 29a can be taken in and out of the small diameter cylinder portion 27a from the large diameter cylinder portion 27b side.

  The inside of the large-diameter cylinder portion 27b is partitioned by a large-diameter portion 29b into a front chamber 27f on the small-diameter cylinder portion 27a side and a rear chamber 27r on the opposite side.

  The motor 11 is composed of, for example, a rotary electric motor. The motor 11 may be a direct current motor or an alternating current motor. Moreover, the motor 11 may be comprised by appropriate motors, such as an induction motor and a synchronous motor. The motor 11 is configured as a servo motor, for example, and constitutes a servo mechanism together with an encoder 31 that detects the rotation of the motor 11 and a servo driver (servo amplifier) 33 that supplies electric power to the motor 11.

  The transmission mechanism 13 includes a pulley 35 that is fixed to the output shaft of the motor 11, a belt 37 that is hung on the pulley 35, a nut 39 that is hung on the belt 37, and a nut 39 that is screwed into the conversion piston 29. And a screw shaft 41 fixed to the head.

  The rotation of the motor 11 is transmitted to the nut 39 via the pulley 35 and the belt 37. The rotation transmitted to the nut 39 is converted into an axial translational motion of the screw shaft 41 by the nut 39 and the screw shaft 41 and transmitted to the conversion piston 29. The screw mechanism constituted by the nut 39 and the screw shaft 41 is constituted by, for example, a ball screw mechanism.

  The motor 11 (and the encoder 31 and the transmission mechanism 13) may be provided separately from the injection cylinder device 7 and the conversion cylinder device 9, or as a built-in motor, integrated with the injection cylinder device 7 and the conversion cylinder device 9. May be provided.

  The screw shaft 41 and the conversion piston 29 are fixed as follows, for example. A driven portion 43 protrudes from the end surface on the front side (head side chamber 25 h side) of the small diameter portion 29 a of the conversion piston 29. The driven portion 43 is, for example, a rod-shaped member having a circular cross section provided coaxially with the conversion piston 29. The driven portion 43 extends to the outside of the conversion cylinder tube 27 from the end surface of the conversion cylinder tube 27 on the front side of the small diameter cylinder portion 27a (the side opposite to the large diameter cylinder portion 27b). The screw shaft 41 is formed at a portion of the driven portion 43 that extends to the outside of the conversion cylinder tube 27.

  Note that the screw shaft 41 may be regarded as a part of the driven part 43 or as a member fixed to the driven part 43. In the present embodiment, for convenience of description, the screw shaft 41 is described as a member fixed to the driven portion 43. The screw shaft 41 and the driven part 43 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other. The driven portion 43 and the conversion piston 29 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other.

  Since the rotation of the nut 39 causes relative rotation between the nut 39 and the screw shaft 41, the screw shaft 41 needs to be prevented from rotating. In this embodiment, the screw shaft 41 is prevented from rotating by the dog rod 45. The dog rod 45 has a configuration related to position detection in the conversion cylinder device 9. The injection device 1 has a dog 47 provided on the dog rod 45 and a switch 49 operated by the dog 47 in addition to the dog rod 45 as a configuration related to position detection in the conversion cylinder device 9. .

  The dog rod 45 is fixed to the conversion piston 29 and extends from the conversion cylinder tube 27 in the sliding direction of the conversion piston 29. More specifically, the conversion cylinder protrudes from the end surface on the rear side (opposite to the small diameter portion 29a) of the large diameter portion 29b and from the end surface on the rear side (opposite side to the small diameter cylinder portion 27a) of the large diameter cylinder portion 27b. It extends to the outside of the tube 27.

  The dog rod 45 extends from the conversion cylinder tube 27 at a position eccentric with respect to the axis of the conversion piston 29. Therefore, the rotation of the conversion piston 29 is restricted by the dog rod 45 and the conversion cylinder tube 27. Thereby, the rotation of the screw shaft 41 is prevented.

  The dog 47 is provided at a portion extending from the conversion cylinder tube 27 of the dog rod 45. For example, the dog 47 is provided so as to protrude in a direction orthogonal to the axial direction of the dog rod 45 at the extending side end of the dog rod 45.

  The switch 49 is constituted by, for example, a lever type switch. When the conversion piston 29 reaches a predetermined position, the dog 47 contacts the lever of the switch 49, and the switch 49 is turned on. The predetermined position is the backward limit of the conversion piston 29 in the present embodiment. That is, the switch 49 constitutes a backward limit detector for the conversion piston 29.

  The conversion piston 29 and the dog rod 45 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other. The dog rod 45 and the dog 47 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other.

  The hydraulic circuit 17 includes, for example, a rod-side channel 51 connected to the rod-side chamber 25r, a front-side channel 53 connected to the front-side chamber 27f, and a rear-side channel 55 connected to the rear-side chamber 27r. is doing. These three flow paths are connected to each other.

  Accordingly, the front flow path 53 and the rear flow path 55 constitute a first communication path 57 that communicates the rod side chamber 25r and the rear chamber 27r. Further, the front flow path 53 and the rear flow path 55 constitute a second communication path 58 that connects the front chamber 27f and the rear chamber 27r.

  Further, the hydraulic circuit 17 has a bypass passage 59 that communicates the small diameter cylinder portion 27a (and the head side chamber 25h) and the front side chamber 27f. Accordingly, the small diameter cylinder portion 27a and the front chamber 27f can communicate with each other even when the small diameter portion 29a is inserted into the small diameter cylinder portion 27a.

  The bypass channel 59 and the front channel 53 are provided with a bypass valve VLa and a front valve VLd that can open and close each channel, respectively.

  The bypass valve VLa is configured by, for example, a pilot check valve that also functions as a flow rate adjustment valve. In addition, the function as a flow regulating valve may not be provided. The bypass valve VLa is closed when pilot pressure is introduced. Further, when the pilot pressure is not introduced, the bypass valve VLa blocks the flow from the small diameter cylinder portion 27a (and the head side chamber 25h) to the front chamber 27f and allows the flow in the opposite direction.

  The front valve VLd is configured by, for example, a pilot check valve. A closing pilot pressure and an opening pilot pressure can be selectively introduced into the front valve VLd. Further, the front side valve VLd blocks the flow from the front side chamber 27f and allows the flow in the opposite direction when both the pilot pressure to open and the pilot pressure to close are not introduced.

  The control device 19 includes, for example, a CPU 61, a memory 63 such as a ROM or a RAM, an input circuit 65, and an output circuit 67. The CPU 61 executes a program stored in the memory 63 and outputs a control signal for controlling the motor 11 and various valves via an output circuit 67 based on an input signal input via the input circuit 65. To do.

  Signals are input to the input circuit 65, for example, an input device 69 that accepts user input operations, a head-side pressure sensor 71 that detects the pressure in the head-side chamber 25h, and a rod-side pressure sensor 73 that detects the pressure in the rod-side chamber 25r. A position sensor 75 for detecting the position of the injection plunger 5 and the switch 49 described above.

  The output circuit 67 outputs a signal, for example, a servo driver 33, a display 77 for displaying information to the user, and a hydraulic pressure (not shown) for introducing a pilot pressure to the pilot type check valves (VLa and VLd). Circuit.

  The position sensor 75 is provided in the injection cylinder device 7, for example, and measures the amount of displacement of the injection piston rod 21 with respect to the injection cylinder tube 25, and indirectly detects the position of the injection plunger 5. Note that the injection cylinder device 7 can be regarded as a cylinder device having a length measuring function. The position sensor 75 is, for example, a scale portion 91 provided on the injection piston rod 21 along the direction in which the injection piston rod 21 extends, and a sensor portion 93 that is disposed to face the scale portion 91 and detects the movement of the scale portion 91. It is comprised by the linear encoder which has.

  The head side pressure sensor 71 and the rod side pressure sensor 73 indirectly detect the pressure applied by the injection plunger 5 to the molten metal, such as the pressure (injection pressure) applied by the injection plunger 5 to the molten metal when the molten metal is injected into the cavity 105. Is. That is, the product of the pressure detected by the head side pressure sensor 71 and the pressure receiving area of the injection piston 23 in the head side chamber 25h, and the product of the pressure detected by the rod side pressure sensor 73 and the pressure receiving area of the injection piston 23 in the rod side chamber 25r. Therefore, the force applied by the injection plunger 5 to the molten metal can be calculated, so that the injection pressure and the like can be detected.

  The operation of the injection apparatus 1 having the above configuration will be described.

  FIG. 2 is a graph showing changes in injection pressure P and injection speed V in the injection apparatus 1.

  In general, the injection device 1 performs low-speed injection control, high-speed injection control, and pressure increase control in order. That is, in the initial stage of injection, the injection device 1 advances the injection plunger at a relatively low speed in order to prevent entrainment of air of the molding material, and then at a relatively high speed from the viewpoint of shortening the molding cycle. Advance the injection plunger. Thereafter, the injection device 1 increases the pressure of the molding material in the cavity by the force in the direction in which the injection plunger advances in order to eliminate sink marks of the molded product.

  FIG. 3 is a chart showing the operations of the motor 11, the pilot check valves (VLa and VLd), the conversion piston 29 and the injection piston 23 that realize the operation of FIG.

  In FIG. 3, in each row, the order from the upper side to the lower side is chronological order. The leftmost “injection operation” column in FIG. 3 outlines the operation of each row. The columns of “injection speed” and “injection pressure” indicate the correspondence between FIG. 3 and FIG. 2 by indicating the reference numerals given in FIG. However, the speed and pressure when the injection piston 23 and the conversion piston 29 retreat after the solidification of the molten metal are only described in FIG.

  In the “Motor” column, the rotation of the motor 11 in the direction of moving the conversion piston 29 forward (moving toward the head side chamber 25h) is “D”, and the rotation of the motor 11 in the direction of moving the conversion piston 29 backward is “U”. The stop of the motor 11 is indicated by “−”. The motor 11 may be stopped in a torque-free state or in a state where braking torque is generated.

  In the “Pilot check valve” column, VL is omitted from the reference numerals of the bypass valve VLa and the front valve VLd, and “a” and “d” columns corresponding to these valves are provided. In the column of “Pilot check valve”, “N” indicates a state in which no pilot pressure is introduced, “C” indicates that a pilot pressure to be closed is introduced, and “O” indicates a pilot pressure to be opened. Indicates that it is introduced, and “-” indicates that it may be selected as appropriate.

  The column “conversion piston position” indicates that the switch 49 is turned on by “ON” and that the switch 49 is turned off by “−”.

  The column of “injection piston retreat limit” indicates that the injection piston 23 is located at the retreat limit by a circle (◯) and that it is not located at the retreat limit by “−”.

  Hereinafter, the operation of the injection apparatus 1 will be described along the time series of FIG. 3 (from the upper side to the lower side in FIG. 3).

(Low speed injection operation)
Immediately before the start of the low-speed injection operation, the conversion piston 29 and the injection piston 23 are located at the backward limit. Accordingly, the small diameter portion 29a is not inserted into the small diameter cylinder portion 27a, and the front chamber 27f and the small diameter cylinder portion 27a are in direct communication. Note that the low-speed injection operation can be started in a state where the conversion piston 29 and the injection piston 23 are arranged at appropriate positions other than the backward limit.

  When a predetermined low-speed injection start condition is satisfied, for example, when the clamping of the fixed mold 101 and the movable mold 103 is completed and the molten metal is supplied to the injection sleeve 3, the control device 19 moves the conversion piston 29 forward. A control signal is output to the motor 11 via the servo driver 33 so that the motor 11 is rotated at a relatively low speed.

When the conversion piston 29 moves forward at a relatively low speed, the working fluid is supplied relatively slowly from the conversion cylinder tube 27 to the head side chamber 25h of the injection cylinder tube 25, and the injection piston 23 also moves forward at a relatively low speed. As the injection piston 23 advances, the injection plunger 5 advances at a relatively low speed V _L , and the injection pressure becomes P _L.

  Pilot pressure is not introduced into the bypass valve VLa. That is, the flow from the front chamber 27f to the small diameter cylinder portion 27a is allowed. In the low-speed injection, the front chamber 27f and the small-diameter cylinder portion 27a are in direct communication with each other, and thus a pilot pressure for closing the bypass valve VLa may be introduced.

  A pilot pressure is not introduced to the front valve VLd, or a closed pilot pressure is introduced. That is, the discharge of the hydraulic fluid from the front chamber 27f is prohibited. Accordingly, all of the hydraulic fluid pushed out by the conversion piston 29 is used to push out the injection piston 23.

  When the injection piston 23 moves forward, the hydraulic fluid in the rod side chamber 25r is discharged to the rear side chamber 27r through the first communication passage 57.

  Here, in the conversion cylinder device 9, the driven portion 43 extends from the front end surface (surface on the injection cylinder device 7 side) of the conversion cylinder tube 27 to the outside of the conversion cylinder tube 27. The pressure receiving area in the rear chamber 27r is larger than the pressure receiving area in the front chamber 27f. Therefore, when the conversion piston 29 moves forward, the amount of increase in volume in the rear chamber 27r is larger than the amount of hydraulic fluid discharged from the front chamber 27f.

  Further, in the injection cylinder device 7, the injection piston rod 21 extends from the front end surface (the surface on the injection plunger 5 side) of the injection cylinder tube 25 to the outside of the injection cylinder tube 25. The pressure receiving area in 25h is larger than the pressure receiving area in the rod side chamber 25r. Therefore, when the injection piston 23 moves forward, the amount of hydraulic fluid supplied to the head side chamber 25h is larger than the amount of hydraulic fluid discharged from the rod side chamber 25r.

  That is, in the conversion cylinder device 9 and the injection cylinder device 7 as a whole, the increase amount of the volume in the rear chamber 27r is larger than the discharge amount of the hydraulic fluid from the rod chamber 25r. In other words, in the rear chamber 27r, the required amount of hydraulic fluid exceeds the amount of hydraulic fluid supplied from the rod side chamber 25r, and the hydraulic fluid is insufficient.

  On the other hand, the rod side chamber 25r, the first communication passage 57, and the rear side chamber 27r are sealed and are not connected to the tank.

  Therefore, as shown in the schematic diagram of FIG. 4, in the rear chamber 27r, a space SP in which no hydraulic fluid is present is formed according to the shortage of the hydraulic fluid. The space SP is a vacuum.

(High-speed injection operation)
When the position of the injection plunger 5 based on the detection value of the position sensor 75 reaches a predetermined high-speed switching position, the control device 19 passes the servo driver 33 so as to switch the rotation speed of the motor 11 to a relatively high rotation speed. A control signal is output to the motor 11.

Therefore, the speed of the conversion piston 29 is switched to high speed, and consequently the speed of the injection piston 23 is also switched to high speed. The injection plunger 5 is advanced at a relatively fast speed V _H, injection pressure becomes P _H.

  The ratio between the speed of the conversion piston 29 and the speed of the injection piston 23 (injection plunger 5) is determined by the ratio of the pressure receiving area in the front chamber 27f of the conversion piston 29 and the pressure receiving area in the head side chamber 25h of the injection piston 23. , Constant from low speed injection to high speed injection. Therefore, the ratio of the rotational speed at the low speed injection of the motor 11 to the rotational speed at the high speed injection is proportional to the ratio between the speed at the low speed injection of the injection plunger 5 and the speed at the high speed injection.

  The operations of the bypass valve VLa and the front valve VLd are the same as in the low-speed injection. That is, the control device 19 switches from the low speed injection to the high speed injection only by changing the control of the motor 11 while keeping the control of the hydraulic circuit 17 constant.

(Decelerated injection operation)
The deceleration injection operation is started when an appropriate event occurs. For example, the deceleration injection operation is started when the molten metal is filled in the cavity 105 to some extent, and the injection plunger 5 receives a reaction force from the filled molten metal and decelerates. Alternatively, the deceleration injection operation is started when the small diameter portion 29a is inserted into the small diameter cylinder portion 27a and the injection piston 23 is decelerated, as will be described later. Alternatively, the deceleration injection operation is started by the deceleration control of the motor 11 when a predetermined deceleration start condition is satisfied, such as when the injection plunger 5 reaches a predetermined deceleration position. Alternatively, it is started when two or more events exemplified above occur simultaneously. Any of the events exemplified above may occur first, but it is preferable that the amount of molten metal in one injection is adjusted so as to occur almost simultaneously.

In the deceleration injection operation, the injection speed is reduced from the high injection speed _VH to the speed Vd. However, the cavity 105, because it is filled to some extent the molten metal, the injection pressure is a pressure Pd rises from the high-speed injection pressure P _H in the high-speed injection.

  Further, by inserting the small-diameter portion 29a into the small-diameter cylinder portion 27a, the front chamber 27f and the small-diameter cylinder portion 27a are cut off directly and are only indirectly connected via the bypass channel 59. Become. As a result, the hydraulic fluid supplied from the conversion cylinder tube 27 to the head side chamber 25h decreases, and the injection piston 23 is decelerated.

  The control device 19 outputs a control signal to the motor 11 via the servo driver 33 so as to reduce the rotation speed of the motor 11. However, as described above, since the injection plunger 5 receives a reaction force from the molten metal or the small diameter portion 29a is inserted into the small diameter cylinder portion 27a, the injection plunger 5 is decelerated. It is also possible to decrease the target rotational speed without decreasing the target rotational speed 11 or with a deceleration acceleration smaller than the deceleration acceleration of the injection plunger 5.

  The operations of the bypass valve VLa and the front valve VLd are the same as in the low-speed injection. However, pilot pressure is not introduced into the bypass valve VLa. Therefore, after the small-diameter portion 29a is inserted into the small-diameter cylinder portion 27a, the hydraulic fluid in the front chamber 27f flows to the small-diameter cylinder portion 27a via the bypass channel 59. Since the speed of the injection piston 23 and thus the speed of the injection plunger 5 can be adjusted by adjusting the flow rate in the bypass valve VLa, the bypass valve VLa is configured to have the function of a variable flow rate adjusting valve, and the flow rate is adjusted. May be.

(Pressure increase operation)
When a predetermined pressure increase start condition is satisfied, the control device 19 introduces a pilot pressure to the bypass valve VLa and closes the bypass valve VLa. Thereby, the flow of the hydraulic fluid from the front chamber 27f to the small diameter cylinder portion 27a is blocked. In addition, the control device 19 opens the front valve VLd by introducing a pilot pressure for opening the front valve VLd. Thereby, the flow of the hydraulic fluid from the front chamber 27f to the rear chamber 27r is allowed.

  Accordingly, the conversion piston 29 pressurizes the hydraulic fluid in the head side chamber 25h by the sum of the pressure receiving area in the front chamber 27f of the large diameter portion 29b and the pressure receiving area in the small diameter cylinder portion 27a of the small diameter portion 29a in the injection operation. Thus, the pressure is changed to a state where the hydraulic fluid in the head side chamber 25h is pressurized only by the pressure receiving area in the small diameter cylinder portion 27a of the small diameter portion 29a in the pressure increasing operation. As a result, even if the torque of the motor 11 is constant, the pressure in the head side chamber 25h rises and the force that the injection piston 23 receives from the head side chamber 25h increases due to the Pascal principle.

  That is, the force with which the injection plunger 5 pressurizes the molten metal increases. The injection pressure reaches Pmax via the pressure Pt. In addition, the injection speed becomes 0 after the speed Vt when the cavity 105 is completely filled with the molten metal.

  The pressure increase start condition is, for example, that the injection pressure detected by the head side pressure 71 and the rod side pressure sensor 73 has reached a predetermined value, or that the injection plunger 5 has reached a predetermined position. .

  For example, the motor 11 is switched from speed control for obtaining a desired rotation speed to torque control for obtaining a desired torque at the start of the pressure increasing operation. However, since the pressure applied to the molten metal by the injection plunger 5 can be increased by the action of the conversion piston 29 as described above, the control of the motor 11 can be made constant from the deceleration injection operation to the pressure increase operation. is there.

  In the conversion cylinder device 9, the working fluid in the front chamber 27f is returned to the rear chamber 27r. However, for the same reason as during injection, the amount of increase in volume (required amount of hydraulic fluid) in the rear chamber 27r is greater than the amount of hydraulic fluid discharged from the front chamber 27f and the rod side chamber 25r. Then, the space SP continues to expand at the time of injection.

(Pressure holding operation)
When the injection pressure reaches a predetermined casting pressure (final pressure) Pmax, a pressure holding operation is performed so that the casting pressure Pmax is maintained. For example, the control device 19 performs torque control of the motor 11 so that the injection pressure detected by the head side pressure sensor 71 and the rod side pressure sensor 73 is kept constant.

  The operations of the bypass valve VLa and the front valve VLd are the same as when the pressure is increased. Therefore, the pressure increasing action by the conversion cylinder device 9 is maintained.

(Reverse injection piston)
When the molten metal solidifies, the control device 19 outputs a control signal to the motor 11 via the servo driver 33 so as to drive the motor 11 in a direction in which the conversion piston 29 is moved backward. The control device 19 determines whether or not the molten metal has solidified, for example, based on whether or not a predetermined time has elapsed since a predetermined reference time such as a time when the casting pressure Pmax is reached.

  When the conversion piston 29 is retracted by the motor 11 and the rear chamber 27r is filled with the hydraulic fluid (when the space SP is exhausted), the hydraulic fluid in the rear chamber 27r is discharged to the rod side chamber 25r. Thereby, the injection piston 23 also moves backward.

  The bypass valve VLa and the front valve VLd are appropriately controlled so that the conversion piston 29 and the injection piston 23 are smoothly retracted.

  For example, when the conversion piston 29 starts to move backward, a pilot pressure for closing the bypass valve VLa is introduced. That is, the flow from the front chamber 27f to the small diameter cylinder portion 27a via the bypass flow path 59 is prohibited. Thereby, a negative pressure is generated in the head side chamber 25h, and the injection piston 23 is easily retracted.

  Further, for example, in the front valve VLd, the pilot pressure to be closed is introduced at an appropriate timing at an appropriate time so that the supply of the hydraulic fluid to the rod side chamber 25r has priority over the supply of the hydraulic fluid to the front chamber 27f. . Thereby, even after the front side chamber 27f and the small diameter cylinder portion 27a (head side chamber 25h) communicate with each other, the negative pressure in the head side chamber 25h is maintained, and the injection piston 23 is easily retracted.

(Injection piston retract limit and conversion piston retract limit)
The control device 19 detects that the injection piston 23 has reached the backward limit based on the detection result of the position sensor 75. Further, the control device 19 detects that the conversion piston 29 has reached the backward limit based on the ON signal from the switch 49.

  As described above, when the replenishment of the hydraulic fluid to the rod side chamber 25r is prioritized over the replenishment of the hydraulic fluid to the front side chamber 27f, the injection piston 23 is set to the retreat limit before the conversion piston 29. To reach.

  Thereafter, when the conversion piston 29 reaches the backward limit, an open pilot pressure is introduced into the front valve VLd. Thereby, the pressure of hydraulic fluid is equalized over the whole apparatus.

(Preparation for the next cycle)
When the control device 19 determines that both the injection piston 23 and the conversion piston 29 have reached the retreat limit, the control device 19 prepares for the next cycle. For example, the pilot pressure which closes to various valves is introduced, the flow of the hydraulic fluid between the plurality of cylinder chambers is suppressed, and the position of the injection plunger 5 is held at a fixed position. However, since the front chamber 27f and the small-diameter cylinder portion 27a are in direct communication, the bypass valve VLa may or may not be introduced with the pilot pressure.

  According to the above embodiment, the injection device 1 includes the injection cylinder device 7 that can drive the injection plunger 5, the conversion cylinder device 9 that supplies hydraulic fluid to the injection cylinder device 7, and the rod side chamber 25 r of the injection cylinder device 7. And the rear chamber 27r of the conversion cylinder device 9 and a motor 11 capable of driving the conversion piston 29 of the conversion cylinder device 9. In the injection operation of the injection device 1, the working fluid in the rod side chamber 25r is discharged to the rear chamber 27r via the first communication passage 57, and there is no working fluid in the rear chamber 27r according to the shortage of working fluid. SP is formed.

  Accordingly, the rear chamber 27r functions as a tank that stores the hydraulic fluid discharged from the rod side chamber 25r. In addition, the shortage of hydraulic fluid in the rear chamber 27r is compensated by the formation of the space SP in the rear chamber 27r. As a result, the injection apparatus 1 does not require a tank and the configuration is simplified.

  In the normal cylinder device, the piston (29) does not advance toward the front chamber (27f) unless hydraulic fluid is supplied to the rear chamber (27r). In other words, the normal cylinder device is premised on the hydraulic fluid filling the rear chamber (27r). The present invention focuses on the fact that it is not essential that the hydraulic fluid is filled in the rear chamber 27r in the hybrid drive device in which the conversion piston 29 is driven by the motor 11, and the space SP is formed. Yes, it has a novel configuration that is not confined to the concept of a normal cylinder device.

  Since the space SP is a vacuum, the configuration is simplified compared to a mode in which gas (for example, air) is introduced into the rear chamber 27r to form the space SP (this mode is also included in the present invention). The For example, it is not necessary to provide an air vent valve that allows the flow of air between the rear chamber 27r and the outside of the conversion cylinder device 9 and prohibits the flow of hydraulic fluid.

  After the injection, the conversion piston 29 is driven by the motor 11 to the rear chamber 27r side, the space SP is lost, the rear chamber 27r is filled with the hydraulic fluid, and the hydraulic fluid is supplied from the rear chamber 27r to the rod side chamber 25r. 23 moves backward. That is, the injection piston 23 that is not directly connected to the motor 11 is retracted by the motor 11. Accordingly, the configuration of the injection device 1 can be simplified.

  The conversion cylinder tube 27 has a small-diameter cylinder portion 27a that communicates with the head-side chamber 25h, and a large-diameter cylinder portion 27b that communicates with the small-diameter cylinder portion 27a and has a larger diameter than the small-diameter cylinder portion 27a. The conversion piston 29 has a small diameter portion 29a that can slide the small diameter cylinder portion 27a and a large diameter portion 29b that can slide the large diameter cylinder portion 27b.

  Accordingly, when shifting from the injection operation to the pressure increasing operation, the pressure receiving area in front of the conversion piston 29 is increased (the sum of the pressure receiving area of the small diameter portion 29a and the pressure receiving area of the large diameter portion 29b) to the smaller (small diameter portion). 29a pressure receiving area). As a result, in the injection operation, the amount of hydraulic fluid flowing into the head side chamber 25h with respect to the number of rotations of the motor 11 is increased compared to the pressure increase operation, and in the pressure increase operation, the motor is compared with the injection operation. The pressure in the head side chamber 25h with respect to 11 torque can be increased. That is, high-speed injection and pressure increase are possible while reducing the burden on the motor 11. Furthermore, since it is not necessary to provide an accumulator, maintenance management is facilitated, and it is not necessary to perform synchronous control of driving forces from different driving limits, thereby facilitating control.

  In the configuration in which the hydraulic fluid is supplied from the accumulator to the rear chamber 27r without the motor 11, the pressure receiving operation in the rear chamber 27r of the large diameter portion 29b is performed in the pressure increasing operation in which the small diameter portion 29a is inserted into the small diameter cylinder portion 27a. Depending on the ratio of the area and the pressure receiving area in the small diameter cylinder portion 27a of the small diameter portion 29a, the pressure in the rear chamber 27r is increased and a pressure increasing action is transmitted to the front chamber 27f. Therefore, a change in the pressure receiving area (in other words, diameter d1) of the large diameter portion 29b with respect to the pressure receiving area (in other words, diameter d2) of the small diameter portion 29a affects the pressure increasing operation. Therefore, in setting the diameter d1, both the influence of the diameter d1 on the high speed injection operation and the influence on the pressure increasing operation must be considered.

  On the other hand, in the present embodiment, the change of the diameter d1 of the large diameter portion 29b with respect to the diameter d2 of the small diameter portion 29a does not affect the pressure increasing operation. That is, the pressure generated in the front chamber 27f is obtained by dividing the driving force of the motor 11 by the pressure receiving area on the front side of the small-diameter portion 29a, and is influenced only by the diameter d2 of the small-diameter portion 29a. Not affected. Therefore, the diameter d1 of the large-diameter portion 29b can be set in consideration of only the high-speed injection operation without considering the pressure increasing operation, and the degree of freedom in design is high.

Incidentally, the injection piston 23 (the injection plunger 5) are driven at a speed of ^{(d1 2 -d3 2) / d4} 2 times the speed of the conversion piston 29. As an example, when d1 = 180 mm, d3 = 30 mm, and d4 = 90 mm, the injection piston 23 is driven at a speed approximately four times the speed of the conversion piston 29.

  The driven portion 43 protrudes from the small diameter portion 29a and extends to the outside of the conversion cylinder tube 27 from the end surface (front end surface) of the small diameter cylinder portion 27a opposite to the large diameter cylinder portion 27b. Accordingly, unlike the present embodiment, various diameters d1 to d5 can be easily set as compared with the mode in which the driven portion 43 is exposed from the rear end surface of the conversion cylinder tube 27 (this mode is also included in the present invention). It is. For example, when the driven portion 43 is exposed from the rear end surface of the conversion cylinder tube 27, depending on the setting of various diameters d1 to d5, the working fluid may become excessive in the rear chamber 27r. There is no need to assume a case.

  The injection device 1 includes a screw shaft 41 provided in the driven part 43 and a nut 39 that is screwed to the screw shaft 41 and is rotationally driven by the motor 11. The screw shaft 41 is connected to the conversion piston 29. Are provided coaxially. Therefore, the driving force from the motor 11 is restrained from generating a force that tilts the conversion piston 29 with respect to the conversion cylinder tube 27. As a result, it is possible to prevent the sliding resistance from increasing or decreasing, the hydraulic fluid from leaking, or the conversion cylinder device 9 from being damaged.

  The injection device 1 is fixed to the conversion piston 29 and extends to the outside of the conversion cylinder tube 27 of the dog rod 45 extending in the sliding direction of the conversion piston 29 from the conversion cylinder tube 27 and the dog rod 45. A dog 47 provided in the portion and a switch 49 operated by the dog 47 are provided. The dog rod 45 extends from the conversion cylinder tube 27 at a position eccentric with respect to the axis of the conversion piston 29. Therefore, the dog rod 45 is also used as a rotation stopper for the conversion piston 29, and the configuration is simplified.

  In the above embodiment, the die casting machine is an example of the molding machine of the present invention, the molten metal is an example of the molding material of the present invention, and the inside of the small diameter cylinder portion 27a and the front side chamber 27f are the first cylinder of the present invention. The rear chamber 27r is an example of a second cylinder chamber of the present invention, and the front valve VLd is an example of a direction control valve of the present invention.

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

  The molding machine is not limited to a die casting machine. For example, the molding machine may be another metal molding machine, a plastic injection molding machine, or a molding machine that molds a material obtained by mixing wood powder with a thermoplastic resin or the like. Good. Further, the injection device is not limited to horizontal mold clamping horizontal injection, and may be vertical mold clamping vertical injection or horizontal mold clamping vertical injection, for example. The hydraulic fluid is not limited to oil and may be water, for example.

  Moreover, in embodiment, the case where the injection cylinder apparatus 7 and the conversion cylinder apparatus 9 were arrange | positioned so that it might orthogonally crossed was illustrated. More specifically, the case where the injection cylinder device 7 is arranged horizontally and the conversion cylinder device 9 is arranged vertically is illustrated. However, the injection cylinder device and the conversion cylinder device may be arranged in an appropriate positional relationship such as parallel.

  FIG. 5A shows a modification of the arrangement of the injection cylinder device 7 and the conversion cylinder device 9. In this modification, both the injection cylinder device 7 and the conversion cylinder device 9 are disposed horizontally. The arrangement of the embodiment has an advantage that the weight of the conversion piston 29 and the weight of the hydraulic fluid in the rear chamber 27r can be used. In the modified example, the weight of the conversion piston 29 or the like cannot be used, but in exchange, it is not necessary to consider the weight of the conversion piston 29 or the like in calculating the injection pressure or the like, and the design and control are facilitated.

  The relative sizes of the various diameters (d1 to d5) in the injection cylinder device and the conversion cylinder device may be set as appropriate.

For example, the pressure receiving area (π × (d1 ² −d3 ² )) in the front chamber (27f) of the conversion piston (29) is larger than the pressure receiving area (π × d4 ² ) in the head side chamber (25h) of the injection piston (23). May be larger, smaller, or the same. In other words, in the injection operation, the injection piston (23) may be accelerated, decelerated, or set to the same speed as the conversion piston (29).

For example, in the embodiment, the pressure receiving area (π × (d2 ² −d3 ² )) in the small diameter cylinder chamber (27a) of the small diameter portion (29a) is the pressure receiving area in the head side chamber (25h) of the injection piston (23). It may be smaller than (π × d4 ² ), larger or the same. In other words, in the pressure increasing operation and the pressure holding operation, the torque from the motor 11 may be amplified, may be attenuated, or both may not be performed.

  Further, for example, in the conversion cylinder device, when the driven portion (43) is extended forward as in the embodiment, it is essential that the diameter d3 is smaller than the diameter d2. Conversely, when extending the driven portion (43) rearward, it is not essential that the diameter d3 is smaller than the diameter d2. That is, the diameter d3 may be the same as the diameter d2, or may be larger than the diameter d2.

  The conversion cylinder device may not have a pressure-increasing action using the Pascal principle.

  FIG. 5B shows a conversion cylinder device 109 according to such a modification. The conversion cylinder tube 127 and the conversion piston 129 of the conversion cylinder device 109 have a uniform cross-sectional area in the axial direction.

  In the injection operation, as in the embodiment, the hydraulic fluid in the rod side chamber 25r is discharged to the second cylinder chamber 109r. In the second cylinder chamber 109r, a space SP is formed according to the shortage of hydraulic fluid.

  In the case where the conversion cylinder device exhibits a pressure increasing action using the Pascal principle, the small diameter portion (29a) may not be able to be taken in and out of the small diameter cylinder portion (27a). That is, it may be inserted into the small diameter cylinder part. Even in this case, if the front chamber (27f) and the small-diameter cylinder part (27a) are communicated with each other by the bypass flow path (59), the pressure reception in front of the conversion piston is performed by opening and closing the bypass flow path (59). The area can be switched.

  Further, when the small diameter portion (29a) can be taken in and out of the small diameter cylinder portion (27a), the bypass passage (59) and the bypass valve (VLa) communicating the front chamber (27f) and the small diameter cylinder portion (27a). Can be omitted.

  The electric motor is not limited to a rotary type. Further, the transmission mechanism (13) may be omitted. For example, a linear motor may be used as the electric motor, and the conversion piston may be driven directly by the electric motor.

  When a rotary electric motor is used, the conversion mechanism that converts the rotational motion into the translational motion is not limited to the screw mechanism. For example, the conversion mechanism may be a rack and pinion mechanism. Further, the rotation transmission mechanism that transmits the rotational motion is not limited to the pulley and the belt. For example, the rotation transmission mechanism may be a gear mechanism. The screw shaft is preferably provided coaxially with the conversion piston, but may be provided in parallel with the conversion piston.

  The position detection of the conversion piston is not limited to that performed by the dog, the dog rod and the switch. For example, the position of the conversion piston may be detected indirectly by an encoder of the electric motor, or may be detected by providing a linear scale that detects the position of the driven part (43).

  The detent required when the screw shaft is provided coaxially with the axis of the conversion piston is not limited to that provided by the dog rod. For example, the rotation of the conversion piston may be prevented by using a spline screw as the screw shaft of the screw mechanism.

  The switch operated by the dog is not limited to one that detects the backward limit of the conversion piston. For example, the switch may detect a position where the small diameter portion is inserted into the small diameter cylinder portion, or may be provided corresponding to a plurality of positions. The switch may be turned off when the dog reaches a predetermined position.

  The hydraulic circuit for obtaining the effects of the present invention can be appropriately configured, and channels and valves may be provided in addition to the channels and valves shown in the embodiments. Moreover, although this invention makes it possible to omit a tank, an accumulator, or a pump, these components may be provided.

  DESCRIPTION OF SYMBOLS 1 ... Injection device, 5 ... Injection plunger, 7 ... Injection cylinder device, 9 ... Conversion cylinder device, 11 ... Motor (electric motor), 21 ... Injection piston rod, 23 ... Injection piston, 25 ... Injection cylinder tube, 25r ... Rod side chamber 25h ... head side chamber, 27 ... conversion cylinder tube, 27a ... small diameter cylinder part, 27b ... large diameter cylinder part, 29 ... conversion piston, 29a ... small diameter part, 29b ... large diameter part, 43 ... driven part, 57 ... first 1 communication path, 105 ... cavity, SP ... space.

Claims (9)

An injection device for extruding a molding material into a cavity by an injection plunger,
An injection piston rod connected to the injection plunger, an injection piston to which the injection piston rod is fixed, and an injection cylinder tube that slidably accommodates the injection piston, and the inside of the injection cylinder tube is the injection An injection cylinder device partitioned by a piston into a rod side chamber on the side where the injection piston rod extends and a head side chamber on the opposite side thereof;
A conversion cylinder tube that communicates with the head side chamber, and a conversion piston that is slidably accommodated in the conversion cylinder tube, and the inside of the conversion cylinder tube communicates with the head side chamber by the conversion piston. A conversion cylinder device partitioned into a chamber and a second cylinder chamber on the opposite side;
A first communication passage communicating the rod side chamber and the second cylinder chamber;
A driven part fixed to the conversion piston and extending to the outside of the conversion cylinder tube;
An electric motor capable of driving the driven part in the sliding direction of the conversion piston;
Have
The conversion piston is driven to the first cylinder chamber side by the electric motor, hydraulic fluid is supplied from the first cylinder chamber to the head side chamber, and the injection piston moves forward to the rod side chamber side, whereby the injection plunger Is advanced to inject the molding material into the cavity,
In the injection, the working fluid in the rod side chamber is discharged to the second cylinder chamber through the first communication passage, and there is no working fluid in the second cylinder chamber according to the shortage of working fluid. Is formed molding machine injection device. The injection device for a molding machine according to claim 1, wherein the space is a vacuum. After the injection, the conversion piston is driven to the second cylinder chamber side by the electric motor, the space disappears, the second cylinder chamber is filled with the working fluid, and the second cylinder chamber is operated to the rod side chamber. The injection device according to claim 1, wherein liquid is supplied and the injection piston moves backward. The conversion cylinder tube is
A small diameter cylinder portion communicating with the head side chamber;
A large-diameter cylinder portion having a diameter larger than that of the small-diameter cylinder portion,
Have
The conversion piston is
A small diameter part capable of sliding the small diameter cylinder part;
A large diameter portion capable of sliding the large diameter cylinder portion;
The injection device for a molding machine according to any one of claims 1 to 3. A second communication passage that communicates the second cylinder chamber with the front chamber on the small diameter cylinder portion side of the large diameter portion of the large diameter cylinder portion;
A direction control valve for opening and closing the second communication path;
A control device for controlling the electric motor and the direction control valve;
Have
The controller is
In a state where the front chamber and the small diameter cylinder portion are in communication with each other and the front chamber and the second cylinder chamber are shut off, the conversion piston is moved toward the injection cylinder tube by the driving force of the electric motor. And
In the state where the small diameter portion is inserted into the small diameter cylinder portion, the front chamber and the small diameter cylinder portion are blocked, and the front chamber and the second cylinder chamber are communicated, the conversion is performed by the driving force of the electric motor. Increase the pressure by moving the piston to the injection cylinder tube side,
The injection device for a molding machine according to claim 4, wherein the electric motor and the direction control valve are controlled. The control device switches from low-speed injection to high-speed injection by switching the rotational speed of the electric motor from low speed to high speed while performing control of the hydraulic circuit when performing the injection. The injection device of the molding machine described in 1. The said driven part protrudes from the said conversion piston to the said 1st cylinder chamber side, and extends to the exterior of the said conversion cylinder tube from the end surface by the side of the said 1st cylinder chamber of the said conversion cylinder tube. An injection device for a molding machine according to claim 1. A screw shaft provided in the driven part;
A nut screwed into the screw shaft and rotated by the electric motor;
Have
The injection device for a molding machine according to any one of claims 1 to 7, wherein the screw shaft is provided coaxially with respect to an axis of the conversion piston. A dog rod fixed to the conversion piston and extending in a sliding direction of the conversion piston from the conversion cylinder tube;
A dog provided on a portion of the dog rod that extends to the outside of the conversion cylinder tube;
A switch operated by the dog;
Have
The injection device for a molding machine according to claim 8, wherein the dog rod extends from the conversion cylinder tube at a position eccentric with respect to an axis of the conversion piston.

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