JP5424626B2 - Injection machine for molding machine - Google Patents

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.

  The injection device of the molding machine is configured to inject the molding material into the cavity by advancing the injection plunger in the sleeve by the injection cylinder device and pushing the molding material (for example, molten metal) in the sleeve into the cavity formed between the molds. Fill. The injection / filling process generally includes a low-speed injection process, a high-speed injection process, and a pressure increasing process. That is, in the initial stage of injection, the injection device advances the injection plunger at a relatively low speed in order to prevent air entrainment of the molding material, and then the injection plunger at a relatively high speed from the viewpoint of shortening the molding cycle. Move forward. Thereafter, the injection device increases the pressure of the molding material in the cavity by a force in the direction in which the injection plunger advances in order to eliminate sink marks of the molded product. In order to realize the operation of such an injection device, various injection cylinder devices and hydraulic circuits for supplying hydraulic fluid to the injection cylinder device have been proposed.

The injection device of Patent Document 1 communicates with the head side chamber of the injection cylinder device, and has another cylinder device having a convex cylinder tube and a convex piston with the head side chamber side convex, thereby enabling high-speed injection. The process and the pressure increasing process are suitably performed. That is, when the entire convex piston is moving forward in the large diameter chamber of the convex cylinder tube, a large amount of hydraulic fluid is supplied to the head side chamber of the injection cylinder device to advance the injection plunger. After the small-diameter portion of the cylinder is fitted into the small-diameter chamber of the convex cylinder tube, high pressure hydraulic fluid is supplied to the head side chamber of the injection cylinder device due to the pressure-increasing effect caused by the difference in pressure receiving area before and after the convex piston. Supply to increase pressure.
Japanese Patent Laid-Open No. 2001-25857

  In the technique of Patent Document 1, switching from the high-speed injection process to the pressure-increasing process is performed using a change in the pressure receiving area of the piston, but switching from the low-speed injection process to the high-speed injection process is performed by an injection cylinder device. This is realized by increasing the amount of hydraulic fluid supplied to another cylinder device communicating with the cylinder. Therefore, in the technique of Patent Document 1, in order to realize a desired high-speed movement, a relatively large amount of hydraulic fluid must be sent out and controlled. As a result, for example, an increase in the size of a hydraulic pressure source such as an accumulator or an increase in the size of a flow rate control valve such as a servo valve that controls the flow rate of hydraulic fluid from the hydraulic pressure source occurs.

  An object of the present invention is to provide an injection apparatus for a molding machine in which a hydraulic pressure source and a flow control valve can be downsized.

  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. A partitioned injection cylinder device, a conversion cylinder tube communicating with the head side chamber, a conversion cylinder device having a conversion piston slidably accommodated in the conversion cylinder tube, and a hydraulic pressure capable of delivering hydraulic fluid A fluid pressure circuit capable of controlling the flow of hydraulic fluid from the fluid pressure source to the conversion cylinder device; The conversion cylinder tube has a large-diameter cylinder portion and a rear-side small-diameter cylinder portion that communicates with a side of the large-diameter cylinder portion opposite to the head-side chamber and has a smaller diameter than the large-diameter cylinder portion. The conversion piston has a large diameter part capable of sliding the large diameter cylinder part, and a rear small diameter part capable of sliding the rear small diameter cylinder part, and the hydraulic circuit includes: The flow rate control valve is capable of controlling the flow rate of the hydraulic fluid from the hydraulic pressure source, and the hydraulic fluid that has passed through the flow rate control valve is less than the large-diameter portion of the large-diameter cylinder portion on the rear small-diameter cylinder portion. The large-diameter rear chamber on the side and the small-diameter rear chamber on the opposite side of the large-diameter cylinder portion from the small-diameter portion of the small-diameter cylinder portion on the rear side, and an operation that has passed through the flow control valve Supply of liquid to the large-diameter rear chamber and the small-diameter rear chamber The supply of both the individual, or separately from the other one, and is configured to be prohibited.

  Preferably, the hydraulic circuit includes a small-diameter rear valve capable of allowing or prohibiting a flow of hydraulic fluid from the flow control valve to the small-diameter rear chamber, and an operation from the flow control valve to the large-diameter rear chamber. And a large-diameter rear valve capable of allowing or prohibiting the flow of liquid.

  Preferably, the hydraulic circuit has a rod side valve capable of allowing or prohibiting a flow of hydraulic fluid from the flow rate control valve to the rod side chamber.

  Preferably, the injection device of the molding machine has a tank capable of storing hydraulic fluid, and the hydraulic circuit can allow or prohibit the flow of hydraulic fluid between the tank and the large-diameter rear chamber. The tank has a large-diameter rear valve, and the tank is disposed above the large-diameter rear chamber.

  Preferably, the conversion cylinder tube is provided between the head side chamber and the large diameter cylinder portion, and has a front small diameter cylinder portion having a smaller diameter than the large diameter cylinder portion, and the conversion piston is formed on the front side. It has a front side small diameter part which can slide a small diameter cylinder part.

  Suitably, the said conversion piston is accommodated in the said conversion cylinder tube so that the said front side small diameter part can be taken in / out from the said large diameter cylinder part side to the said front side small diameter cylinder part.

  Preferably, the injection device of the molding machine includes a detector that detects a position of the injection plunger, and a control device that controls the hydraulic circuit based on a detection result of the detector, and the rear The cross-sectional area of the side small-diameter cylinder is smaller than the cross-sectional area obtained by subtracting the cross-sectional area of the rear-side small-diameter cylinder from the cross-sectional area of the large-diameter cylinder. , Allowing the flow of hydraulic fluid to the large-diameter rear chamber and prohibiting the flow of hydraulic fluid to the small-diameter rear chamber to perform low-speed injection, and then the position detected by the detector is a predetermined high-speed switching position Is reached, the flow of hydraulic fluid to the small-diameter rear chamber is allowed and high-speed injection is performed.

  Preferably, the hydraulic pressure source is an accumulator, and the flow control valve is a servo valve.

  According to the present invention, the hydraulic pressure source and the flow rate control valve can be reduced in size.

  FIG. 1 is a diagram showing a configuration 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 can slide within the injection sleeve 3, an injection cylinder device 7 that drives the injection plunger 5, and a conversion cylinder that communicates with the injection cylinder device 7. Device 9. The injection device 1 also includes an accumulator 11 that can deliver hydraulic fluid (for example, oil), a tank 13 that stores hydraulic fluid, a pump 15 that accumulates the accumulator 11, and a hydraulic circuit 17 that controls the flow of hydraulic fluid. And a control device 19 for controlling the hydraulic circuit 17 and the like.

  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. The conversion cylinder device 9 supplies hydraulic fluid to the head side chamber 25h by advancing the conversion piston 29 (moving downward in the drawing of FIG. 1) to advance the injection piston 23 (moving to the left of the drawing in FIG. 1). It is configured to be possible. In addition, when the injection piston 23 moves backward (moves to the right side in FIG. 1), the conversion cylinder device 9 supplies hydraulic fluid to the conversion cylinder tube 27 from the head side chamber 25h, and the conversion piston 29 moves backward (page of FIG. 1). Moving upward).

  The conversion cylinder tube 27 has, for example, a circular cross section, and is convex on the front side (lower side in FIG. 1) and the rear side (upper side in FIG. 1). That is, the conversion cylinder tube 27 communicates with the front small diameter cylinder portion 27a that communicates with the head side chamber 25h, the large diameter cylinder portion 27b that communicates with the front small diameter cylinder portion 27a, and has a larger diameter than the front small diameter cylinder portion 27a. It has a rear small-diameter cylinder portion 27c that communicates with the portion 27b and has a smaller diameter than the large-diameter cylinder portion 27b.

The diameter d3 of the front small diameter cylinder portion 27a, the diameter d2 of the large diameter cylinder portion 27b, the diameter d1 of the rear small diameter cylinder portion 27c, and the diameter d4 of the injection cylinder tube 25 are appropriately set within a range where desired effects can be obtained. For example, d1 <d3 = d4 <d2 and d1 ² <d2 ² −d1 ² .

  The conversion piston 29 is also formed so as to protrude forward and rearward corresponding to the shape of the conversion cylinder tube 27. That is, the conversion piston 29 is slidable on the front small diameter portion 29a capable of sliding on the front small diameter cylinder portion 27a, on the large diameter portion 29b capable of sliding on the large diameter cylinder portion 27b, and on the rear small diameter cylinder portion 27c. And a rear small diameter portion 29c.

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

  The rear small diameter portion 29c may or may not be pulled out from the rear small diameter cylinder portion 27c when the conversion piston 29 moves forward. However, as will be described later, the high speed injection operation is performed in a state where the rear small diameter portion 29c is inserted into the rear small diameter cylinder portion 27c, and the pressure increasing operation after the high speed injection operation is performed by using the front small diameter portion 29a as the front small diameter cylinder. Since it is performed in a state of being inserted into the portion 27a, it is preferable that the length is not pulled out from the rear small diameter cylinder portion 27c until the front small diameter portion 29a reaches the front small diameter cylinder portion 27a.

  The rear small diameter cylinder portion 27c has a small diameter rear chamber 27ch and / or a large diameter cylinder portion 27b which is opposite to the large diameter cylinder portion 27b with respect to the rear small diameter portion 29c (the upper side in FIG. 1). When the working fluid is supplied to the large-diameter rear chamber 27bh on the rear small-diameter cylinder portion 27c side with respect to the large-diameter portion 29b, the conversion piston 29 moves forward. Further, the small-diameter front chamber 27ar and / or the large-diameter cylinder portion 27b on the opposite side (the lower side in FIG. 1) of the small-diameter portion 29a with respect to the small-diameter portion 29a of the front-side small-diameter cylinder portion 27a When the working fluid is supplied to the large-diameter front chamber 27br on the front-side small-diameter cylinder portion 27a side with respect to the large-diameter portion 29b, the conversion piston 29 moves backward.

  Here, since the rear side small diameter cylinder portion 27c is formed with a relatively small diameter, when supplying the hydraulic fluid only to the small diameter rear side chamber 27ch to advance the conversion piston 29, the rear side small diameter cylinder portion 27c is operated at a high speed with a relatively small amount of hydraulic fluid. The conversion piston 29 can be moved forward.

  Further, after the front small-diameter portion 29a is inserted into the front small-diameter cylinder portion 27a when the conversion piston 29 moves forward, if the hydraulic fluid in the large-diameter front chamber 27br can be discharged, the large-diameter rear chamber of the large-diameter portion 29b. The pressure receiving area at 27bh (or the pressure receiving area obtained by adding the pressure receiving area in the small diameter rear chamber 27ch of the rear small diameter portion 29c to this pressure receiving area) and the pressure receiving area in the small diameter front chamber 27ar of the front small diameter portion 29a Due to the pressure effect, a high-pressure hydraulic fluid can be supplied to the head side chamber 25h.

  The head side chamber 25h and the small-diameter front side chamber 27ar may be communicated with each other with an appropriate configuration. For example, the injection cylinder tube 25 and the conversion cylinder tube 27 may be directly communicated with each other by being fixed to each other, may be communicated via a flow path formed by a rigid member, or may be flexible. May be communicated via a flow path formed by a member having a property.

  Further, the relative positions of the injection cylinder tube 25 and the conversion cylinder tube 27 and the orientation of these cylinder tubes with respect to the direction of gravity may be set as appropriate. FIG. 1 illustrates the case where the injection cylinder tube 25 is disposed horizontally and the conversion cylinder tube 27 is disposed so as to extend upward from the end of the injection cylinder tube 25 on the head side chamber 25h side. .

  The accumulator 11 is a so-called gas type accumulator, and includes a pressure accumulation cylinder tube 31 and a pressure accumulation piston 33 that can slide in the pressure accumulation cylinder tube 31. The pressure accumulation cylinder tube 31 is partitioned by a pressure accumulation piston 33 into a gas chamber 31g and a liquid chamber 31o. Gas (for example, air or nitrogen) is compressed and held in the gas chamber 31g. In the liquid chamber 31o, hydraulic fluid supplied to the injection cylinder device 7 and the conversion cylinder device 9 is held.

  The liquid chamber 31o communicates with the rod-side chamber 25r, the large-diameter rear chamber 27bh, and the small-diameter rear chamber 27ch. Accordingly, the accumulator 11 can selectively supply the working fluid to the rod side chamber 25r, the large diameter rear chamber 27bh, and the small diameter rear chamber 27ch, and drive the injection cylinder device 7 and the conversion cylinder device 9.

  Although not particularly illustrated, the accumulator 11 includes a flow path that connects the gas chamber 31g and the atmosphere, a cock that opens and closes the flow path, and a gas chamber 31g that keeps the gas chamber 31g at a predetermined pressure. A pressure gauge or the like for detecting pressure is provided.

  The tank 13 stores the hydraulic fluid under atmospheric pressure. The tank 13 communicates with the rod-side chamber 25r, the large-diameter front chamber 27br, and the large-diameter rear chamber 27bh, and can supply the hydraulic fluid to these cylinder chambers and accept the hydraulic fluid discharged from these cylinder chambers. It is. For example, the tank 13 is disposed above the large-diameter front chamber 27br and the large-diameter rear chamber 27bh, and the hydraulic fluid can be supplied to these cylinder chambers using the dead weight of the hydraulic fluid. .

  The pump 15 sucks the hydraulic fluid in the tank 13 and sends it out from the discharge port 15a. The pump 15 may be configured by an appropriate pump such as a piston pump, a gear pump, or a vane pump. The pump 15 is rotationally driven by a motor 35. The motor 35 may be a direct current motor or an alternating current motor. Further, the motor 35 may be configured by an appropriate motor such as an induction motor or a synchronous motor.

  The hydraulic circuit 17 is connected to the accumulator channel 37 connected to the accumulator 11, the small-diameter rear channel 39 connected to the accumulator channel 37 and the small-diameter rear chamber 27ch, the accumulator channel 37 and the large-diameter rear chamber 27bh. It has a connected large-diameter rear flow channel 41 and a rod-side flow channel 43 connected to the accumulator flow channel 37 and the rod-side chamber 25r.

  The hydraulic circuit 17 includes a servo valve 45 provided in the accumulator channel 37, a small-diameter rear valve VLa provided in the small-diameter rear channel 39, and a large-diameter provided in the large-diameter rear channel 41. It has a diameter rear side valve VLb and a rod side valve VLc provided in the rod side flow path 43.

  Accordingly, the small-diameter rear chamber 27ch, the large-diameter rear chamber 27bh, and the rod-side chamber 25r are individually allowed to supply the hydraulic fluid from the accumulator 11 by the small-diameter rear valve VLa, the large-diameter rear valve VLb, and the rod-side valve VLc. Or prohibited. On the other hand, in the small-diameter rear chamber 27ch, the large-diameter rear chamber 27bh, and the rod-side chamber 25r, the flow rate of the hydraulic fluid supplied from the accumulator 11 is commonly controlled by the servo valve 45.

  The servo valve 45 is a control valve that is used in the servo mechanism and can modulate the flow rate in a stepless manner in accordance with electric or other input signals. The servo valve 45 is constituted by, for example, a double-coil electromagnetic flow control valve. The servo valve 45 is opened with an opening corresponding to the control signal input by the control device 19. The servo valve 45 outputs a detection signal indicating the opening degree to the control device 19. The detection signal is a signal indicating the position of the spool, for example. The servo valve 45 is feedback controlled by the control device 19 so as to be opened at a desired opening degree.

  The small-diameter rear valve VLa is constituted by, for example, a pilot type check valve (check valve) that can introduce a pilot pressure to be closed and a pilot pressure to be opened. When the pilot pressure is not introduced, the small-diameter rear valve VLa prevents the flow from the accumulator 11 to the small-diameter rear chamber 27ch and allows the flow in the opposite direction.

  The large-diameter rear side valve VLb is constituted by, for example, a pilot type check valve capable of introducing a pilot pressure to be closed and a pilot pressure to be opened. When the pilot pressure is not introduced, the large-diameter rear valve VLb prevents the flow from the accumulator 11 to the large-diameter rear chamber 27bh and allows the flow in the opposite direction.

  The rod side valve VLc is constituted by, for example, a pilot type check valve capable of introducing a pilot pressure to be closed and a pilot pressure to be opened. When the pilot pressure is not introduced, the rod side valve VLc blocks the flow from the accumulator 11 to the rod side chamber 25r and allows the flow in the opposite direction.

  The hydraulic circuit 17 has a bypass passage 47 that communicates the large-diameter front chamber 27br of the conversion cylinder device 9 with the small-diameter front chamber 27ar. The bypass channel 47 is provided with a bypass valve VLd that can open and close the bypass channel 47.

  The bypass channel 47 is provided so that the large-diameter front chamber 27br and the small-diameter front chamber 27ar communicate with each other even when the front small-diameter portion 29a is inserted into the front small-diameter cylinder portion 27a. The portion of the bypass passage 47 that communicates with the small-diameter front chamber 27ar is indirectly opened by opening the head-side chamber 25h of the injection cylinder device 7 or a communication passage that communicates the head-side chamber 25h and the small-diameter front chamber 27ar. In addition, the small-diameter front chamber 27ar may be communicated with.

  The bypass valve VLd is configured by, for example, a pilot check valve. The bypass valve VLd is closed when pilot pressure is introduced. Further, when the pilot pressure is not introduced, the bypass valve VLd blocks the flow from the small-diameter front chamber 27ar to the large-diameter front chamber 27br and allows the flow in the opposite direction.

  Therefore, when the conversion piston 29 moves forward with the front small diameter portion 29a inserted into the small diameter front chamber 27ar, when the pilot pressure is not introduced, the hydraulic fluid in the large diameter front chamber 27br is bypassed. When the pilot pressure is introduced into the small-diameter front chamber 27ar through 47, the small-diameter front chamber 27ar is sealed. When the conversion piston 29 is retracted in a state where the front small diameter portion 29a is inserted into the small diameter front chamber 27ar, the small diameter front chamber 27ar is sealed.

  The hydraulic circuit 17 has the following configuration in order to allow the hydraulic fluid to be discharged from the injection cylinder device 7 and the conversion cylinder device 9 to the tank 13 and to be supplied from the tank 13 to the conversion cylinder device 9. have.

  The hydraulic circuit 17 includes a tank rod side channel 49 that communicates the rod side chamber 25r and the tank 13, a tank large diameter front side channel 51 that communicates the large diameter front chamber 27br and the tank 13, and a large diameter rear chamber 27bh. And a tank large-diameter rear passage 53 that communicates with the tank 13.

  The hydraulic circuit 17 includes a tank rod side valve VLe provided in the tank rod side flow path 49, a tank large diameter front valve VLf provided in the tank large diameter front flow path 51, and a tank large diameter rear side flow. And a tank large-diameter rear valve VLg provided in the passage 53.

  The tank rod side valve VLe is constituted by, for example, a pilot type check valve. The tank rod side valve VLe is closed when pilot pressure is introduced. Further, the tank rod side valve VLe prevents the flow from the tank 13 to the rod side chamber 25r and permits the flow in the opposite direction when the pilot pressure is not introduced.

  The tank large-diameter front valve VLf is constituted by, for example, a pilot type check valve capable of introducing a pilot pressure to be closed and a pilot pressure to be opened. The tank large-diameter front valve VLf prevents the flow from the large-diameter front chamber 27br to the tank 13 and permits the flow in the opposite direction when the pilot pressure is not introduced.

  The tank large-diameter rear valve VLg is constituted by, for example, a pilot type check valve capable of introducing a pilot pressure to be closed and a pilot pressure to be opened. When the pilot pressure is not introduced, the tank large-diameter rear valve VLg blocks the flow from the large-diameter rear chamber 27bh to the tank 13 and allows the flow in the opposite direction.

  The tank large-diameter front channel 51 and the tank large-diameter rear channel 53 are shared on the tank 13 side. However, these may not be shared.

  The hydraulic pressure circuit 17 includes a pressure accumulation channel 59 that communicates the discharge port 15 a of the pump 15 and the liquid chamber 31 o of the accumulator 11, and a pressure accumulation valve 61 provided in the pressure accumulation channel 59. For the sake of illustration, the pressure accumulating channel 59 is shown by omitting the portion between (1) shown in two places in FIG. The pressure accumulating valve 61 is constituted by, for example, a check valve that allows a flow from the pump 15 to the accumulator 11 and prevents a flow in the opposite direction.

  The hydraulic circuit 17 includes a tank 63, a tank small-diameter rear channel 65 that communicates the tank 63 and the small-diameter rear chamber 27ch, and a tank small-diameter rear valve 67 provided in the tank small-diameter rear channel 65. doing. These are for enabling discharge of hydraulic fluid from the small-diameter rear chamber 27ch and replenishment of hydraulic fluid to the small-diameter rear chamber 27ch. The tank 63 may be shared with the tank 13.

  The tank small-diameter rear valve 67 is constituted by, for example, a pilot type check valve that is opened when pilot pressure is introduced. When the pilot pressure is not introduced, the tank small-diameter rear valve 67 prevents the flow from the small-diameter rear chamber 27ch to the tank 63 and allows the flow in the opposite direction. Although the tank small-diameter rear valve 67 is not shown, the pressure in the rod-side chamber 25r is introduced as a pilot pressure. The pressure in the rod side chamber 25r may be introduced through the rod side channel 43.

  The control device 19 includes, for example, a CPU 71, a memory 73 such as a ROM or a RAM, an input circuit 75, and an output circuit 77. The CPU 71 executes a program stored in the memory 73, and outputs a control signal for controlling various valves and the motor 35 through the output circuit 77 based on an input signal input through the input circuit 75. To do.

  The signal is input to the input circuit 75, for example, whether the servo valve 45, the input device 79 that receives the user's input operation, the length measuring sensor 81 that detects the position of the injection plunger 5, and the conversion piston 29 have reached the retreat limit. This is a backward limit detector 83 that detects whether or not.

  The output circuit 77 outputs a signal, for example, a servo valve 45, a display 85 for displaying information to the user, and a hydraulic circuit (not shown) for introducing pilot pressure to the pilot type valves (VLa to VLg). It is.

  The length measuring sensor 81 is provided in the injection cylinder device 7, for example, and measures the amount of displacement of the injection piston rod 21 relative 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 length measuring sensor 81 is, for example, a scale portion 87 provided on the injection piston rod 21 along the direction in which the injection piston rod 21 extends, and a sensor portion 89 that is disposed to face the scale portion 87 and detects the movement of the scale portion 87. It is comprised by the linear encoder which has. As the linear encoder, an appropriate type such as a magnetic type or an optical type may be selected.

  The backward limit detector 83 is constituted by, for example, a lever type switch. An operation member 91 extending from the rear small diameter cylinder portion 27 c of the conversion cylinder tube 27 is fixed to the conversion piston 29. When the conversion piston 29 reaches the backward limit, the operating member 91 comes into contact with the lever of the backward limit detector 83, and the backward limit detector 83 is turned on. When the conversion piston 29 moves forward from the backward limit, the operating member 91 is separated from the lever, and the backward limit detector 83 is turned off.

  In addition to the configuration described above, the injection device 1 may have a pressure sensor or the like that detects the pressure in the head side chamber 25h. The pressure in the head side chamber 25h is generally proportional to 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.

  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 is a low-speed injection control that advances the injection plunger 5 at a relatively low speed, a high-speed injection control that advances the injection plunger 5 at a relatively high speed, and a pressure increase that increases the molten metal in the cavity 105 by the injection plunger 5. Control in order.

  FIG. 3 is a chart showing operations of various valves (VLa to VLg), the servo valve 45, the accumulator 11, the conversion piston 29, the injection piston 23, and the motor 35 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 “Pilot Check Valve” column, VL is omitted from the symbols VLa to VLg of various valves, and “a” to “g” columns corresponding to the various valves (VLa to VLg) 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 has been introduced.

  The column “servo valve” indicates a flow rate (may be regarded as an opening degree) in the servo valve 45.

  In the “release” column of “accumulator”, the fact that hydraulic fluid is released from the accumulator 11 is indicated by a circle (◯), and the fact that hydraulic fluid is not released from the accumulator 11 is indicated by a cross (×). In the “fill” column of “accumulator”, a circle (◯) indicates that the accumulator 11 is filled with a working fluid, and a cross (×) indicates that the accumulator 11 is not filled with a working fluid.

  The column of “conversion piston position” indicates that the backward limit detector 83 is turned on by “ON” and indicates that it 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 “−”.

  The column “motor” indicates that the motor 35 is driven by a circle (◯) and that the motor 35 is not driven by a cross (×).

  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)
Before the start of the low-speed injection operation, the conversion piston 29 and the injection piston 23 are located at the backward limit. Therefore, the front small diameter portion 29a is not inserted into the front small diameter cylinder portion 27a, and the large diameter front chamber 27br and the small diameter front chamber 27ar are in direct communication with each other. 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 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 supplies the hydraulic fluid accumulated in the accumulator 11 only to the large-diameter rear chamber 27bh. Thus, the hydraulic circuit 17 is controlled.

That is, the control device 19 opens the servo valve 45 at an opening corresponding to the flow rate V _LP . The control device 19 introduces a pilot pressure that closes the small-diameter rear valve VLa, or introduces a pilot pressure that opens to the large-diameter rear valve VLb without introducing the pilot pressure, and closes the rod-side valve VLc. Introduce pressure or do not introduce pilot pressure.

  When the working fluid is supplied to the large-diameter rear chamber 27bh, the pressure receiving area of the large-diameter portion 29b in the large-diameter rear chamber 27bh is set to be relatively large, so that the conversion piston 29 moves forward 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.

However, since the diameter d2 of the large diameter cylinder portion 27b is set larger than the diameter d4 of the head side chamber 25h, the injection piston 23 moves forward at a higher speed (d2 ² / d4 ² times) than the conversion piston 29. 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.

  The working fluid in the tank 63 is supplied to the small-diameter rear chamber 27ch via the tank small-diameter rear valve 67 due to the negative pressure generated in the small-diameter rear chamber 27ch as the conversion piston 29 moves forward.

  The control device 19 may control the opening degree of the servo valve 45 based on the feedback signal from the servo valve 45 so that the opening degree is set in advance, or based on the detection result of the length measurement sensor 81. The opening degree of the servo valve 45 may be controlled so that the speed of the injection plunger 5 becomes a preset speed. Further, the control device 19 may control the opening degree of the servo valve 45 so as to become a preset speed after controlling the opening degree of the servo valve 45 so as to become a preset opening degree. The feedback loop of the opening degree may be incorporated as a minor loop in the speed feedback loop of the injection plunger 5. The same applies to high-speed injection and deceleration injection, which will be described later. Below, control device 19 explains as what controls servo valve 45 so that it may become a preset opening.

  The bypass valve VLd may or may not have pilot pressure introduced therein. This is because in the low-speed injection and the high-speed injection described later, the front small diameter portion 29a is not inserted into the front small diameter cylinder portion 27a, and the large diameter front chamber 27br and the small diameter front chamber 27ar are in direct communication.

  Pilot pressure is not introduced into the tank rod side valve VLe. Accordingly, the hydraulic fluid in the rod side chamber 25 r pushed out by the injection piston 23 is discharged to the tank 13.

  The tank large-diameter front valve VLf is supplied with a closed pilot pressure or no pilot pressure. Accordingly, the hydraulic fluid in the large-diameter front chamber 27br pushed out by the conversion piston 29 does not flow into the tank 13 but is used to apply pressure to the injection piston 23.

  A closed pilot pressure is introduced to the tank large-diameter rear valve VLg, or no pilot pressure is introduced. Accordingly, the hydraulic fluid supplied from the accumulator 11 to the large-diameter rear chamber 27bh does not flow into the tank 13 but is used to apply pressure to the conversion piston 29.

  The motor 35 is not driven until the retreat of the injection piston described later is completed. Accordingly, in the accumulator 11, only the hydraulic fluid is discharged and the hydraulic fluid is not charged until the injection piston described later is retracted.

(High-speed injection operation)
When the position of the injection plunger 5 based on the detection value of the length measuring sensor 81 reaches a predetermined high-speed switching position, the control device 19 changes the supply destination of the hydraulic fluid from the accumulator 11 from the large-diameter rear chamber 27bh to the small-diameter rear chamber 27ch. Switch to. That is, the control device 19 introduces a pilot pressure that opens to the small-diameter rear valve VLa, introduces a pilot pressure that closes to the large-diameter rear valve VLb, or does not introduce the pilot pressure.

When the hydraulic fluid supply destination is switched, the cross-sectional area of the small-diameter rear chamber 27ch is smaller than the cross-sectional area of the large-diameter rear chamber 27bh excluding the rear small-diameter portion 29c, so that the conversion piston 29 moves forward at a relatively high speed. As a result, the injection piston 23 also moves forward at a relatively high speed. Accordingly, the injection plunger 5 is advanced at a relatively fast speed V _H, the P _H injection pressure rises.

The opening degree of the servo valve 45 is an opening degree corresponding to the flow rate V _HP . The flow rate V _HP may be the same as or larger than the flow rate V _LP . In other words, the opening degree of the servo valve 45 may or may not be changed from low-speed injection to high-speed injection. Even if the opening degree of the servo valve 45 is constant, switching from the low speed to the high speed is performed by changing the pressure receiving area in the conversion cylinder device 9 as described above. Further, when the opening degree of the servo valve 45 is increased from low speed injection to high speed injection, the injection plunger 5 is further increased in speed.

  An open pilot pressure is introduced into the tank large-diameter rear valve VLg. Accordingly, the hydraulic fluid is supplied from the tank 13 to the large-diameter rear side chamber 27bh. As described above, the tank 13 is disposed above the large-diameter rear chamber 27bh, and the hydraulic fluid in the tank 13 can flow into the large-diameter rear chamber 27bh by its own weight. Therefore, the hydraulic fluid is efficiently replenished as compared with the case where the hydraulic fluid is replenished from the tank 13 only by the negative pressure generated in the large-diameter rear chamber 27bh as the conversion piston 29 advances.

  Note that the rod side valve VLc, the bypass valve VLd, the tank rod side valve VLe, and the tank large-diameter front side valve VLf remain in the state during the low speed injection operation.

(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 is decelerated by receiving a reaction force from the molten metal filled in the cavity 105.

  Alternatively, the deceleration injection operation is started when the front small diameter portion 29a is inserted into the front small diameter cylinder portion 27a and the injection piston 23 is decelerated, as will be described later.

  Alternatively, the deceleration injection operation is started when the supply destination of the hydraulic fluid in the accumulator 11 is switched from the small-diameter rear chamber 27ch to the large-diameter rear chamber 27bh when a predetermined deceleration start condition is satisfied, as will be described later. Is done. The deceleration start condition is, for example, that the injection plunger 5 has reached a predetermined deceleration position.

  Alternatively, the deceleration injection operation is started by reducing the opening of the servo valve 45 when a predetermined deceleration start condition is satisfied, as will be described later.

  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.

  By inserting the front small diameter portion 29a into the front small diameter cylinder portion 27a, the large diameter front chamber 27br and the front small diameter cylinder portion 27a are directly blocked. On the other hand, the pilot pressure is not introduced into the bypass valve VLd, and the flow of the hydraulic fluid from the large-diameter front chamber 27br to the front small-diameter cylinder portion 27a is allowed in the bypass flow path 47. However, since the cross-sectional area of the bypass flow path 47 is smaller than the cross-sectional area of the front small diameter cylinder portion 27a, the flow rate in the bypass flow path 47 is such that the working fluid is directly transferred from the large diameter front chamber 27br to the front small diameter cylinder portion 27a. Less than the flow rate when flowing. Accordingly, 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 switches the supply destination of the working fluid of the accumulator 11 from the small-diameter rear chamber 27ch to the large-diameter rear chamber 27bh. That is, the control device 19 introduces a pilot pressure that closes to the small-diameter rear valve VLa, or introduces a pilot pressure that opens to the large-diameter rear valve VLb without introducing the pilot pressure. Thereby, similarly to the low-speed injection, the speed of the conversion piston 29 becomes low, and the injection plunger 5 is decelerated.

The opening degree of the servo valve 45 is an opening degree corresponding to the flow rate V _dP . The flow rate V _dP may be the same as or smaller than the flow rate V _LP . In other words, the opening degree of the servo valve 45 may or may not be changed from the high speed injection to the deceleration injection. Even if the opening degree of the servo valve 45 is constant, the switching from the high speed to the low speed is performed by changing the pressure receiving area in the conversion cylinder device 9 as described above. Further, when the opening degree of the servo valve 45 is reduced from the high speed injection to the deceleration injection, the injection plunger 5 is further decelerated.

  Note that the rod side valve VLc, the tank rod side valve VLe, and the tank large-diameter front side valve VLf remain in the state during the high-speed injection operation. Further, a closed pilot pressure is introduced into the tank large-diameter rear valve VLg, or no pilot pressure is introduced. That is, the tank large-diameter rear valve VLg prohibits the hydraulic fluid that has flowed from the accumulator 11 into the large-diameter rear chamber 27bh from flowing out into the tank 13, as in the low-speed injection operation.

(Pressure increase operation)
When a predetermined pressure increase start condition is satisfied, the control device 19 introduces a pilot pressure to the bypass valve VLd and closes the bypass valve VLd. Thereby, the flow of the hydraulic fluid from the large-diameter front chamber 27br to the small-diameter front chamber 27ar is blocked. Further, an open pilot pressure is introduced into the tank large-diameter front valve VLf. Thereby, the flow of the hydraulic fluid from the large-diameter front chamber 27br to the tank 13 is allowed. The small-diameter rear valve VLa, the large-diameter rear valve VLb, the rod-side valve VLc, the tank rod-side valve VLe, and the tank large-diameter rear valve VLg remain in the state in the deceleration injection operation.

The conversion piston 29 moves forward while discharging the hydraulic fluid in the large-diameter front chamber 27br to the tank 13. Further, the conversion piston 29 has a pressure increase ratio ((d2 ² −d1 ² ) / in accordance with a ratio between a pressure receiving area in the large diameter rear chamber 27bh of the large diameter portion 29b and a pressure receiving area in the small diameter front chamber 27ar of the front small diameter portion 29a. In d3 ² ), the pressure of the hydraulic fluid in the large-diameter rear chamber 27bh is amplified, and the increased pressure is applied to the hydraulic fluid in the small-diameter front chamber 27ar. Thereby, the injection pressure reaches Pmax via the pressure Pt. Further, the injection speed becomes 0 after the speed Vt.

  The pressure increase start condition is, for example, that the pressure (injection pressure) in the head side chamber 25h detected by a pressure sensor (not shown) has reached a predetermined value, or that the injection plunger 5 has reached a predetermined position. It is.

The opening degree of the servo valve 45 is an opening degree corresponding to the flow rate V _tP . The flow rate V _tP may be set as appropriate, and may be the same, larger, or smaller than the flow rate in the injection operation. Further, when the servo valve 45 can control not only the flow rate but also the pressure, the pressure may be the same as that during the injection operation or may be higher than that during the injection operation. Even if the pressure of the hydraulic fluid in the servo valve 45 is constant from the injection operation to the pressure increasing operation, the pressure can be increased by changing the pressure receiving area in the conversion cylinder device 9 as described above. Further, when the pressure in the servo valve 45 is increased from the injection operation to the pressure increasing operation, the pressure is further increased.

  After the pressure increasing operation, the injection device 1 performs a pressure holding operation. That is, the injection device 1 maintains the injection pressure at Pmax.

(Reverse injection piston)
The control device 19 determines whether or not the molten metal has solidified by an appropriate method. For example, the control device 19 determines whether or not the molten metal has solidified by determining whether or not the elapsed time from an appropriate time such as the time when the injection pressure reaches Pmax has exceeded a predetermined set value. .

  When determining that the molten metal has solidified, the control device 19 switches the supply destination of the hydraulic fluid from the accumulator 11 from the large-diameter rear chamber 27bh to the rod-side chamber 25r. That is, the control device 19 introduces a pilot pressure that closes to the large-diameter rear valve VLb, or introduces a pilot pressure that opens to the rod-side valve VLc without introducing the pilot pressure.

  When the hydraulic fluid is supplied to the rod side chamber 25r, the injection piston 23 starts to retreat. By the retraction of the injection piston 23, the hydraulic fluid in the head side chamber 25h is pushed out to the small diameter front side chamber 27ar, and the conversion piston 29 is also retracted.

The opening degree of the servo valve 45 is an opening degree corresponding to the flow rate _VbP . The flow rate V _bP may be set as appropriate, and may be the same, larger, or smaller than the flow rate in the injection operation or the pressure increasing operation.

  The small-diameter rear valve VLa is introduced with a closed pilot pressure or no pilot pressure. Accordingly, the supply of hydraulic fluid from the accumulator 11 to the small-diameter rear chamber 27ch is prohibited.

  The bypass valve VLd may or may not have pilot pressure introduced therein. In any case, when the front small diameter portion 29a is inserted into the front small diameter cylinder portion 27a, the hydraulic fluid in the head side chamber 25h (small diameter front chamber 27ar) pushed out by the injection piston 23 flows into the large diameter front chamber 27br. It is prohibited. In any case, since the small-diameter front chamber 27ar and the large-diameter front chamber 27br are in direct communication with each other when the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a, it is pushed out by the injection piston 23. The hydraulic fluid in the head side chamber 25h (small diameter front chamber 27ar) flows into the large diameter front chamber 27br.

  The tank rod side valve VLe is closed by introducing pilot pressure. Accordingly, the hydraulic fluid supplied from the accumulator 11 to the rod side chamber 25r does not flow into the tank 13, but is used to apply pressure to the injection piston 23.

  In the tank large-diameter front valve VLf, the pilot pressure to be opened is not introduced or the pilot pressure is not introduced until the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a. Therefore, the hydraulic fluid is supplied from the tank 13 to the large-diameter front chamber 27br. As described above, the tank 13 is disposed above the large-diameter front chamber 27br, and the hydraulic fluid in the tank 13 can flow into the large-diameter front chamber 27br by its own weight. Therefore, the hydraulic fluid is efficiently replenished as compared with the case where the hydraulic fluid is replenished from the tank 13 only by the negative pressure generated in the large-diameter front chamber 27br as the conversion piston 29 moves backward.

  Further, the tank large-diameter front valve VLf is introduced with a closed pilot pressure or no pilot pressure after the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a. Therefore, the hydraulic fluid pushed out by the injection piston 23 from the small diameter front chamber 27ar to the large diameter front chamber 27br does not flow to the tank 13.

  Whether or not the front small diameter portion 29a is pulled out from the front small diameter cylinder portion 27a is detected by, for example, a switch (not shown) operated by the operation member 91.

  An open pilot pressure is introduced into the tank large-diameter rear valve VLg. Accordingly, the hydraulic fluid in the large-diameter rear chamber 27bh is discharged to the tank 13 as the conversion piston 29 moves backward.

  The tank small-diameter rear valve 67 is opened when hydraulic fluid is supplied from the accumulator 11 to the rod-side chamber 25r and the pressure in the rod-side chamber 25r introduced as pilot pressure increases. Accordingly, the hydraulic fluid in the small-diameter rear chamber 27ch is discharged to the tank 63 as the conversion piston 29 moves backward.

(Injection piston retract limit and conversion piston retract limit)
The control device 19 detects that the injection piston 23 has reached the retreat limit based on the detection result of the length measuring sensor 81. Further, the control device 19 detects that the conversion piston 29 has reached the backward limit based on the ON signal from the backward limit detector 83.

  As described above, in the injection operation, the large-diameter front chamber 27br, the small-diameter front chamber 27ar, and the head-side chamber 25h are sealed. Further, in the pressure increasing operation, the hydraulic fluid in the large-diameter front chamber 27br is discharged to the tank 13. The pressure increasing operation is generally started when the front small diameter portion 29a is inserted into the front small diameter cylinder portion 27a.

  On the other hand, in the backward movement of the injection piston 23, the hydraulic fluid is replenished from the tank 13 to the large-diameter front chamber 27br until the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a. After the front small diameter portion 29a is pulled out from the front small diameter cylinder portion 27a, the large diameter front chamber 27br, the small diameter front chamber 27ar, and the head side chamber 25h are sealed.

  That is, in the reverse operation of the injection piston 23, the inflow and outflow of the hydraulic fluid between the injection piston 23 and the conversion piston 29 are generally opposite to the injection operation and the pressure increasing operation. In other words, the amount of hydraulic fluid between the injection piston 23 and the conversion piston 29 is such that the front small diameter portion 29a is inserted into the front small diameter cylinder portion 27a when the conversion piston 29 moves forward and the conversion piston 29 moves backward. At the time, the front small diameter portion 29a is substantially the same after being pulled out from the front small diameter cylinder portion 27a. Accordingly, the injection piston 23 and the conversion piston 29 reach their initial positions (retreat limits) almost simultaneously.

  Strictly speaking, the hydraulic fluid between the injection piston 23 and the conversion piston 29 leaks in a pressure increasing operation or the like. Accordingly, it may occur that the injection piston 23 reaches the backward limit first.

  However, in the deceleration injection operation, the hydraulic fluid is not discharged from the large-diameter front chamber 27br to the tank 13 until the bypass passage 47 is closed even after the front small-diameter portion 29a is inserted into the front small-diameter cylinder portion 27a. Not done. In contrast, when the injection piston 23 and the conversion piston 29 are retracted, the hydraulic fluid is replenished from the tank 13 to the large-diameter front chamber 27br until the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a. Accordingly, the amount of discharge to the tank 13 at the time of forward movement can be made smaller than the amount of replenishment from the tank 13 at the time of backward movement as the timing for closing the bypass valve VLd during the forward movement of the conversion piston 29 is delayed. That is, the leakage of hydraulic fluid between the injection piston 23 and the conversion piston 29 is compensated, and the arrival of the injection piston 23 to the reverse limit is made relatively late with respect to the conversion piston 29 reaching the reverse limit, The timing of reaching the retreat limit of both can be matched.

  When the conversion piston 29 reaches the backward limit first, the pilot pressure that opens to the tank large-diameter front valve VLf is introduced. That is, the hydraulic fluid between the injection piston 23 and the conversion piston 29 can be discharged to the tank 13. Then, the hydraulic fluid may be supplied from the accumulator 11 to the rod side chamber 25r and the injection piston 23 may be moved backward.

  When the injection piston 23 and the conversion piston 29 reach the retreat limit, the control device 19 drives the motor 35 to send the working fluid from the pump 15 to the accumulator 11 and fill the accumulator 11.

  The accumulator 11 may be filled at an appropriate time earlier than this. For example, the accumulator 11 may be filled in parallel with the retraction of the injection piston 23 and the conversion piston 29, and the filling of the accumulator 11 may be completed immediately after the injection piston 23 and the conversion piston 29 reach the retreat limit.

(Preparation for the next cycle)
When the injection piston 23 and the conversion piston 29 reach the backward limit, the control device 19 prepares for the next cycle. For example, the servo valve 45 is closed, and the pilot pressure for the various valves (VLa to VLg) is introduced or no pilot pressure is introduced. That is, the injection device 1 is basically maintained in a state where the flow of hydraulic fluid is stopped. Further, the motor 35 is stopped.

  According to the above embodiment, the injection device 1 includes the injection cylinder device 7, the conversion cylinder device 9 communicated with the injection cylinder device 7, the accumulator 11, and the flow of hydraulic fluid from the accumulator 11 to the conversion cylinder device 9. A hydraulic circuit 17 capable of controlling The conversion cylinder tube 27 includes a large-diameter cylinder portion 27b and a rear-side small-diameter cylinder portion 27c that communicates with the large-diameter cylinder portion 27b on the opposite side of the head-side chamber 25h and has a smaller diameter than the large-diameter cylinder portion 27b. The conversion piston 29 has a large-diameter portion 29b that can slide the large-diameter cylinder portion 27b and a rear-side small-diameter portion 29c that can slide the rear-side small-diameter cylinder portion 27c. The hydraulic circuit 17 has a servo valve 45 that can control the flow rate of the hydraulic fluid from the accumulator 11. The hydraulic circuit 17 can supply the hydraulic fluid that has passed through the servo valve 45 to the large-diameter rear chamber 27bh and the small-diameter rear chamber 27ch, and the large-diameter rear chamber of the hydraulic fluid that has passed through the servo valve 45. Both the supply to 27bh and the supply to the small-diameter rear chamber 27ch can be individually prohibited.

  Therefore, by supplying hydraulic fluid to the large-diameter rear chamber 27bh having a large cross-sectional area, low-speed injection and pressure increase can be performed, while by supplying hydraulic fluid to the small-diameter rear chamber 27ch having a small cross-sectional area, Injection can be performed at high speed. Since the speed is increased by reducing the cross-sectional area of the cylinder chamber to which hydraulic fluid is supplied from the accumulator 11, the amount of hydraulic fluid supplied to the accumulator 11 can be reduced. The valve 45 can be downsized. Furthermore, the speed change operation by switching the supply destination of the hydraulic fluid and the speed change operation by the flow rate adjustment by the servo valve 45 can be combined, so that the difference between the low speed and the high speed is increased, and the injection speed is changed by a multi-stage shift. You can make it.

  The hydraulic circuit 17 has a rod side valve that can allow or prohibit the flow of hydraulic fluid from the servo valve 45 to the rod side chamber 25r. Therefore, the reverse speed of the injection plunger 5 can also be controlled by the servo valve 45 for controlling the forward speed of the injection plunger 5. Further, the conversion piston 29 can be retracted by the retraction of the injection piston 23.

  The injection device 1 has a tank 13 capable of storing hydraulic fluid, and the hydraulic circuit 17 is a tank large-diameter rear side that allows or prohibits the flow of hydraulic fluid between the tank 13 and the large-diameter rear chamber 27bh. It has a valve VLg, and the tank 13 is disposed above the large-diameter rear chamber 27bh. Therefore, as described above, in high-speed injection, the hydraulic fluid can be efficiently used by utilizing the weight of the hydraulic fluid rather than replenishing the hydraulic fluid to the large-diameter rear chamber 27bh only by the negative pressure generated in the large-diameter rear chamber 27bh. Can be replenished.

  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. The hydraulic fluid is not limited to oil and may be water, for example.

  The front side small diameter cylinder part may not be provided. Even in this case, the pressure-receiving area can be switched by providing the rear small-diameter cylinder portion and the large-diameter cylinder portion, and accordingly, a suitable shift of the injection plunger is possible.

  The diameter (d3) of the front small diameter cylinder part, the diameter (d2) of the large diameter cylinder part, and the diameter (d1) of the rear small diameter cylinder part may be set as appropriate.

  For example, if the diameter (d1) of the rear small-diameter cylinder part is smaller than the diameter (d2) of the large-diameter cylinder part, it is compared with a configuration without the conventional rear small-diameter cylinder part (27c), or Compared to the configuration without the conversion cylinder device (9), the conversion piston (29) can be advanced with a small amount of hydraulic fluid, so the diameter (d4) of the injection cylinder tube and the front side The diameter may not be smaller than the diameter (d3) of the small diameter cylinder portion. Further, for example, the diameter (d2) of the large diameter cylinder portion may not be larger than the diameter (d4) of the injection cylinder tube, and the diameter (d3) of the front small diameter cylinder portion is the diameter (d4) of the injection cylinder tube. ) May be larger or smaller.

As in the embodiment, when the hydraulic fluid is supplied only to the large-diameter rear chamber (27bh) and the hydraulic fluid is not supplied to the rear small-diameter chamber (27ch) during pressure increase, the pressure increase ratio ρ = Since (d2 ² −d1 ² ) / d3 ² , d1 to d3 must be determined so as to satisfy d2 ² −d1 ² > d3 ² . That is, the pressure receiving area in the large diameter rear chamber (27bh) of the large diameter portion (29b) must be larger than the pressure receiving area in the small diameter front chamber (27ar) of the front small diameter portion (29a). However, if pressure is increased by supplying hydraulic fluid to both the large-diameter rear chamber (27bh) and the rear small-diameter chamber (27ch), the pressure increase ratio ρ = d2 ² / d3 ² and d2> d3 Just fill it.

In the embodiment, since d1 ² <d2 ² −d1 ² , when hydraulic fluid is supplied to the small-diameter rear chamber (27ch), the hydraulic fluid is faster than when hydraulic fluid is supplied to the large-diameter rear chamber (27bh). It became. However, the conversion cylinder tube (27) is configured so that d1 ² > d2 ² -d1 ^2, and the working fluid is supplied to the small-diameter rear chamber (27ch) to perform low-speed injection, deceleration injection, and pressure increase. High-speed injection may be performed by supplying hydraulic fluid to the rear chamber (27bh). However, when d1 ² <d2 ² −d1 ² , the diameter d1 of the rear small diameter cylinder portion (27c) is reduced, and the conversion cylinder device 9 can be reduced in size, and the rear small diameter portion (29c) is reduced. The sliding resistance can be reduced by reducing the sliding area.

  The front small diameter part (29a) may remain inserted in the front small diameter cylinder part (27a). Even in this case, the working fluid can be supplied from the large-diameter front side chamber (27br) to the head side chamber (25h) via the bypass channel (73) as in the embodiment. However, as in the embodiment, the hydraulic fluid is pushed out from the large-diameter front chamber (27br) to the head-side chamber (25h) without the front small-diameter portion (29a) being inserted into the front small-diameter cylinder portion (27a). Can reduce the resistance applied to the hydraulic fluid and reliably perform the high-speed injection operation.

  In the embodiment, the hydraulic circuit can individually prohibit both the supply of the hydraulic fluid that has passed through the flow control valve (45) to the large-diameter rear chamber (27bh) and the small-diameter rear chamber (27ch). Configured. However, the hydraulic circuit may be configured such that one of the supply to the large-diameter rear chamber and the supply to the small-diameter rear chamber can be prohibited separately from the other.

  For example, in the embodiment, the large-diameter rear valve VLb is omitted. That is, the hydraulic circuit is configured such that the supply of the hydraulic fluid that has passed through the servo valve 45 to the small-diameter rear chamber 27ch can be separately prohibited from being supplied to the large-diameter rear chamber 27bh. Further, the rod-side channel 43 is provided separately from the small-diameter rear channel 39, the large-diameter rear channel 41, and the accumulator-side channel 37. That is, the rod side flow path 43 is directly connected to the accumulator 11 instead of the accumulator side flow path 37. In such a hydraulic circuit, when the servo valve 45 is opened, the hydraulic fluid is supplied to the large-diameter rear chamber 27bh, and low-speed injection is performed. Further, as in the embodiment, when the small-diameter rear valve VLa and the tank large-diameter rear valve VLg are opened, the working fluid is supplied to the small-diameter rear chamber 27ch and high-speed injection is started. However, the cut-off of the small-diameter rear chamber 27ch is such that the advance speed of the conversion piston 29 by supplying the hydraulic fluid to the small-diameter rear chamber 27ch is faster than the speed at which the hydraulic fluid from the accumulator 11 fills the large-diameter rear chamber 27bh. It is necessary to make the area sufficiently small.

  The hydraulic pressure source is not limited to an accumulator. For example, a pump may be used. However, since the pump itself has a function of adjusting the flow rate, when the hydraulic pressure source is a pump, the significance of providing the flow rate control valve is low. The flow control valve is not limited to a servo valve. For example, a proportional electromagnetic control valve may be used. However, the use of a servo valve enables a highly responsive shift.

  Various direction control valves (VLa to VLg, 67) are not limited to check valves. For example, the direction control valve may be a switching valve. Various directional control valves may be shared, such as a small-diameter rear valve (VLa) and a large-diameter rear valve (VLb) configured by a 2-port 2-position switching valve. When various directional control valves are constituted by check valves, those capable of introducing a closing pilot pressure, those capable of introducing an opening pilot pressure, those capable of introducing both a closing pilot pressure and an opening pilot pressure, What is not a pilot type may be used suitably.

The figure 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.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Injection device, 5 ... Injection plunger, 7 ... Injection cylinder device, 9 ... Conversion cylinder device, 11 ... Accumulator (hydraulic pressure source), 17 ... Hydraulic circuit, 21 ... Injection piston rod, 23 ... Injection piston, 25 ... Injection cylinder tube, 25r ... Rod side chamber, 25h ... Head side chamber, 27 ... Conversion cylinder tube, 27b ... Large diameter cylinder portion, 27c ... Rear small diameter cylinder portion, 27bh ... Large diameter rear chamber, 27ch ... Small diameter rear chamber, 29 ... Conversion piston, 29b ... large diameter part, 29c ... rear side small diameter part, 45 ... servo valve (flow control valve), 105 ... cavity.

Claims (8)

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, the inside of the injection cylinder tube being 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 device communicating with the head side chamber, and a conversion cylinder device having a conversion piston slidably accommodated in the conversion cylinder tube;
A hydraulic pressure source capable of delivering hydraulic fluid;
A hydraulic circuit capable of controlling the flow of hydraulic fluid from the hydraulic pressure source to the conversion cylinder device;
Have
The conversion cylinder tube is
A large diameter cylinder,
The large diameter cylinder portion communicates with the side opposite to the head side chamber, and the rear small diameter cylinder portion has a smaller diameter than the large diameter cylinder portion,
Have
The conversion piston is
A large diameter portion capable of sliding the large diameter cylinder portion;
A rear small diameter portion that can slide the rear small diameter cylinder portion; and
Have
The hydraulic circuit has a flow control valve capable of controlling the flow rate of the hydraulic fluid from the hydraulic pressure source, and allows the hydraulic fluid that has passed through the flow control valve to flow more than the large diameter portion of the large diameter cylinder portion. The large-diameter rear chamber on the rear small-diameter cylinder portion side and the small-diameter rear chamber on the opposite side to the large-diameter cylinder portion from the small-diameter portion of the rear small-diameter cylinder portion can be supplied, and the flow rate The hydraulic fluid that has passed through the control valve can be prohibited both separately from the supply to the large-diameter rear chamber and to the small-diameter rear chamber, or separately from the other. Machine injection equipment. The hydraulic circuit is
A small-diameter rear valve capable of allowing or prohibiting the flow of hydraulic fluid from the flow control valve to the small-diameter rear chamber;
A large-diameter rear valve capable of allowing or prohibiting the flow of hydraulic fluid from the flow control valve to the large-diameter rear chamber;
The injection device for a molding machine according to claim 1, comprising: The injection device for a molding machine according to claim 1 or 2, wherein the hydraulic circuit has a rod side valve capable of allowing or prohibiting a flow of hydraulic fluid from the flow control valve to the rod side chamber. It has a tank that can store hydraulic fluid,
The hydraulic circuit has a tank large-diameter rear valve capable of allowing or prohibiting the flow of hydraulic fluid between the tank and the large-diameter rear chamber,
The injection device for a molding machine according to any one of claims 1 to 3, wherein the tank is disposed above the large-diameter rear chamber. The conversion cylinder tube is provided between the head side chamber and the large diameter cylinder part, and has a front small diameter cylinder part having a smaller diameter than the large diameter cylinder part,
The injection device for a molding machine according to any one of claims 1 to 4, wherein the conversion piston has a front small-diameter portion that is slidable on the front small-diameter cylinder portion. The injection device for a molding machine according to claim 5, wherein the conversion piston is accommodated in the conversion cylinder tube so that the front small diameter portion can be taken in and out of the front small diameter cylinder portion from the large diameter cylinder portion side. A detector for detecting the position of the injection plunger;
A control device for controlling the hydraulic circuit based on a detection result of the detector;
Have
The cross sectional area of the rear small diameter cylinder part is smaller than the cross sectional area obtained by subtracting the cross sectional area of the rear small diameter cylinder part from the cross sectional area of the large diameter cylinder part,
When supplying the molding material to the cavity, the control device allows the flow of hydraulic fluid to the large-diameter rear chamber and prohibits the flow of hydraulic fluid to the small-diameter rear chamber, and then performs low-speed injection. The high-speed injection is performed by allowing the flow of hydraulic fluid to the small-diameter rear chamber when the position detected by the detector reaches a predetermined high-speed switching position. Molding machine injection equipment. The hydraulic pressure source is an accumulator;
The injection device for a molding machine according to any one of claims 1 to 7, wherein the flow control valve is a servo valve.

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