JP5424618B2 - 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, a relatively high-pressure accumulator is required to realize a desired high-speed movement, and a servo valve for controlling the flow rate is required, which complicates the hydraulic circuit.

  An object of the present invention is to provide an injection device for a high-performance molding machine with a simple configuration.

  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, the injection cylinder device and the conversion cylinder A hydraulic fluid supply section for supplying hydraulic fluid to the apparatus, and the conversion cylinder The tube has a large-diameter cylinder portion and a rear-side small-diameter cylinder portion communicating with the opposite side of the large-diameter cylinder portion to the head-side chamber and having a smaller diameter than the large-diameter cylinder portion, and 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 fluid supply part includes a drive cylinder tube, A drive piston slidably accommodated in the drive cylinder tube; and a drive piston rod fixed to the drive piston and extending to the outside of the drive cylinder tube, wherein the drive cylinder tube has the drive An injection-side chamber communicated with the rod-side chamber by a piston, a large-diameter rear chamber that is closer to the rear-small cylinder portion than the large-diameter portion of the large-diameter cylinder portion, and the small-diameter of the small-diameter cylinder portion A drive cylinder device partitioned into a conversion side chamber communicated with a small diameter rear chamber opposite to the large diameter cylinder portion, and driving the drive piston rod to place the drive piston in the drive cylinder tube And an electric motor to be slid.

  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 includes a hydraulic circuit that controls a flow of the hydraulic fluid between the hydraulic fluid supply unit and the injection cylinder device and the conversion cylinder device, and the drive piston rod is the conversion piston. The hydraulic circuit extends to a side chamber side, and the hydraulic circuit includes an injection side flow path that connects the injection side chamber and the rod side chamber, a conversion side flow path that connects the conversion side chamber and the head side chamber, and the conversion An intermediate flow path connecting the side flow path and the injection side flow path, a tank connected midway of the intermediate flow path, and the intermediate flow path between the conversion side flow path and the tank. A pilot-type check valve, in which the pressure of the injection-side flow path is introduced as a pilot pressure for opening the check valve, and when the pilot pressure is not introduced, the conversion-side flow path Blocking the flow to the tank A conversion-side check valve that allows flow from the tank to the conversion-side flow path, and a pilot-type check valve provided between the injection-side flow path and the tank in the intermediate flow path, When the pressure in the conversion side flow path is introduced as a pilot pressure for opening the check valve and no pilot pressure is introduced, the flow from the injection side flow path to the tank is blocked and the tank And an injection-side check valve that allows a flow from the injection-side flow path to the injection-side flow path.

  Preferably, the drive piston rod extends toward the injection side chamber and has the same diameter as the injection piston rod.

  Preferably, the injection device includes a small-diameter rear valve capable of allowing or prohibiting the flow of hydraulic fluid from the conversion-side chamber to the small-diameter rear chamber.

  Preferably, the injection device includes a detector that detects a position of the injection plunger, and a control device that controls the electric motor and the small-diameter rear valve based on a detection result of the detector, When supplying the molding material to the cavity, the control device drives the driving piston by the electric motor in a state where the small-diameter rear valve prohibits the flow of hydraulic fluid from the conversion-side chamber to the small-diameter rear chamber, The hydraulic fluid is supplied from the conversion side chamber to the large-diameter rear chamber to start the advancement of the injection plunger, and then the small-diameter rear valve when the position detected by the detector reaches a predetermined high-speed switching position. Thus, the flow of hydraulic fluid from the conversion side chamber to the small diameter rear chamber is allowed, and the hydraulic fluid is supplied to the small diameter rear chamber to accelerate the injection plunger.

  Preferably, the injection device includes a gas accumulator, a large-diameter rear valve capable of allowing or prohibiting a flow between the gas accumulator and the large-diameter rear chamber, and between the gas accumulator and the rod-side chamber. And a rod side valve capable of allowing or prohibiting the flow.

  Preferably, the gas held in the gas accumulator is less than 1 MPa.

  According to the present invention, a high-performance injection machine for a molding machine can be provided with a simple configuration.

  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. In addition, the injection device 1 includes a hydraulic fluid supply unit 11 that can send hydraulic fluid (for example, oil) to the injection cylinder device 7 and the conversion cylinder device 9, an accumulator 13 that holds the pressurized hydraulic fluid, and hydraulic fluid. It has a tank 15 for storing, a hydraulic circuit 17 that controls the flow of hydraulic fluid, and a control device 19 that controls the hydraulic fluid supply unit 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. 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). Specifically, it is as follows.

  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 at the rear small diameter portion 29c. 29c is performed in a state where it is inserted into the rear small diameter cylinder portion 27c, and the pressure increasing operation after the high speed injection operation is performed in a state where the front small diameter portion 29a is inserted into the front small diameter cylinder portion 27a. It is preferable that the length 29a is not pulled out from the rear small diameter cylinder portion 27c until it 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. The relative position and orientation of the injection cylinder device 7 and the conversion cylinder device 9 may be set as appropriate.

  The hydraulic fluid supply unit 11 is driven by the driving force of the motor 31, the transmission mechanism 33 that transmits the driving force of the motor 31, and the driving force of the motor 31 that is transmitted via the transmission mechanism 33, and sends the hydraulic fluid. 35.

  The motor 31 is composed of, for example, a rotary electric motor. The motor 31 may be a direct current motor or an alternating current motor. Further, the motor 31 may be configured by an appropriate motor such as an induction motor or a synchronous motor. The motor 31 is configured as a servo motor, for example, and constitutes a servo mechanism together with an encoder 37 that detects the rotation of the motor 31 and a servo driver (servo amplifier) 39 that supplies electric power to the motor 31.

  For example, the encoder 37 outputs a pulse signal in synchronization with the rotation of the motor 31. For example, the servo driver 39 counts the pulse signal from the encoder 37 to detect the rotation speed of the motor 31. Then, the servo driver 39 feeds back the rotation of the motor 31 so as to follow the input control signal based on the deviation between the control signal input from the control device 19 to the servo driver 39 and the detection result of the encoder 37. Take control.

  The transmission mechanism 33 includes, for example, a pulley 41 fixed to the output shaft of the motor 31, a belt 43 suspended from the pulley 41, a nut 45 suspended from the belt 43, and a screw into which the nut 45 is screwed. And a shaft 47.

  The rotation of the motor 31 is transmitted to the nut 45 via the pulley 41 and the belt 43. The rotation transmitted to the nut 45 is converted into an axial translational motion of the screw shaft 47 by the nut 45 and the screw shaft 47. The screw mechanism constituted by the nut 45 and the screw shaft 47 is constituted by, for example, a ball screw mechanism.

  The drive cylinder device 35 includes a drive cylinder tube 49, a drive piston 51 slidably accommodated in the drive cylinder tube 49, and a drive piston rod fixed to the drive piston 51 and extending to the outside of the drive cylinder tube 49. 53. The drive piston rod 53 and the drive piston 51 may be formed separately and fixed to each other, or may be formed integrally and fixed to each other.

  The drive cylinder tube 49 has a circular cross section, for example. The interior of the drive cylinder tube 49 is partitioned by the drive piston 51 into a cylinder chamber on the side where the drive piston rod 53 extends and a cylinder chamber on the opposite side. One of the two cylinder chambers is an injection-side chamber 49h that communicates with the rod-side chamber 25r, and the other is a conversion-side chamber 49r that communicates with the large-diameter rear chamber 27bh and the small-diameter rear chamber 27ch.

  Either the cylinder chamber on the side from which the drive piston rod 53 extends and the cylinder chamber on the opposite side may be the injection side chamber or the conversion side chamber. In this embodiment, the side from which the drive piston rod 53 extends. This illustrates the case where the cylinder chamber is a conversion side chamber. That is, in this embodiment, the drive piston rod 53 extends to the conversion side chamber 49r side.

  When the drive piston 51 moves to the conversion side chamber 49r side, the working fluid is supplied from the conversion side chamber 49r to the large-diameter rear side chamber 27bh and / or the small-diameter rear side chamber 27ch, and the working fluid is supplied from the rod side chamber 25r to the emission side chamber 49h. Supplied. Conversely, when the drive piston 51 moves toward the injection side chamber 49h, hydraulic fluid is supplied from the injection side chamber 49h to the rod side chamber 25r, and from the large diameter rear side chamber 27bh and / or the small diameter rear side chamber 27ch to the conversion side chamber 49r. Hydraulic fluid is supplied.

  The screw shaft 47 is formed in a portion of the drive piston rod 53 that extends to the outside of the drive cylinder tube 49. Therefore, when the screw shaft 47 is driven by the motor 31, the drive piston rod 53 is driven.

  The screw shaft 47 may be regarded as a part of the drive piston rod 53, or may be regarded as a member fixed to the drive piston rod 53. In the present embodiment, for convenience of description, the screw shaft 47 will be described as a member fixed to the drive piston rod 53. The screw shaft 47 and the drive piston rod 53 may be integrally formed and fixed to each other, or may be formed separately and fixed to each other. The screw shaft 47 and the drive piston rod 53 are prevented from rotating by an appropriate method. For example, a ball screw spline shaft is used as the screw shaft 47 to prevent rotation.

  The accumulator 13 is a so-called gas type accumulator, and includes a pressure accumulation cylinder tube 55 and a pressure accumulation piston 57 that can slide in the pressure accumulation cylinder tube 55. The pressure accumulation cylinder tube 55 is partitioned into a gas chamber 55g and a liquid chamber 55o by a pressure accumulation piston 57. Gas (for example, air or nitrogen) is compressed and held in the gas chamber 55g. The fluid chamber 55o holds hydraulic fluid supplied to the injection cylinder device 7 and the conversion cylinder device 9.

  The liquid chamber 55o communicates with the rod-side chamber 25r, the large-diameter front chamber 27br, and the large-diameter rear chamber 27bh. Therefore, the accumulator 13 can supply the working fluid to the large-diameter front chamber 27br and the large-diameter rear chamber 27bh, or remove the surge pressure generated in the rod-side chamber 25r.

  The gas in the gas chamber 55g is kept at a relatively low pressure. For example, the gas in the gas chamber 55g is held below 1 MPa. In the high pressure gas safety method, 1 MPa or more is defined as high pressure. The accumulator 13 includes a flow path that connects the gas chamber 55g and the atmosphere, a cock that opens and closes the flow path, a pressure gauge that detects the pressure of the gas chamber 55g, and the like so as to keep the pressure in the gas chamber 55g at a predetermined pressure. Is provided.

  The tank 15 stores the hydraulic fluid under atmospheric pressure. In FIG. 1, for convenience of illustration, the tank 15 is illustrated at a plurality of positions, but one tank may actually be provided.

  The hydraulic circuit 17 has an injection-side flow path 59 that communicates the drive cylinder tube 49 and the injection cylinder tube 25, and a conversion-side flow path 61 that communicates the drive cylinder tube 49 and the conversion cylinder tube 27.

  The injection side flow passage 59 communicates the injection side chamber 49h and the rod side chamber 25r. One end of the conversion side channel 61 is connected to the conversion side chamber 49r. The other end of the conversion-side channel 61 branches into a large-diameter branch channel 61a connected to the large-diameter rear chamber 27bh and a small-diameter branch channel 61b connected to the small-diameter rear chamber 27ch.

  The hydraulic circuit 17 allows or prohibits the supply of hydraulic fluid to the small-diameter rear chamber 27ch in the small-diameter branch flow path 61b and the drive-side valve 63 that can permit or prohibit the supply of hydraulic fluid from the hydraulic fluid supply unit 11. A possible small-diameter rear valve VLd and a self-supply valve circuit 65 that compensates for excess or deficiency of the hydraulic fluid in the hydraulic fluid supply unit 11 are provided.

  The drive side valve 63 is constituted by, for example, a 4-port 2-position switching valve, and can be switched between a cutoff position 63a and a connection position 63b. The drive side valve 63 cuts off the connection between the injection cylinder device 7 and the injection side chamber 49h and cuts off the connection between the conversion cylinder device 9 and the conversion side chamber 49r at the cut-off position 63a. The drive side valve 63 connects the injection cylinder device 7 and the injection side chamber 49h at the connection position 63b, and connects the conversion cylinder device 9 and the conversion side chamber 49r. Switching of the position of the drive side valve 63 is performed, for example, by controlling the introduction of pilot pressure by electromagnetic force.

  The small-diameter rear valve VLd is configured by, for example, a pilot type check valve (check valve). The small-diameter rear valve VLd is opened when pilot pressure is introduced. Further, the small diameter rear valve VLd prevents the flow to the small diameter rear chamber 27ch and allows the flow from the small diameter rear chamber 27ch when the pilot pressure is not introduced.

  Accordingly, when the working fluid is supplied from the conversion side chamber 49r to the conversion side flow passage 61, when the pilot pressure is not introduced, the working fluid is supplied only to the large diameter rear side chamber 27bh via the large diameter side branch flow passage 61a. And the conversion piston 29 moves forward at a relatively low speed. When pilot pressure is introduced, the working fluid is also supplied to the small-diameter rear chamber 27ch, and the conversion piston 29 moves forward at a relatively high speed. To do. Note that the small diameter side branch flow path 61b can flow the hydraulic fluid at a flow rate equal to or higher than that of the large diameter side branch flow path 61a so as to achieve such an effect. And a sufficiently large cross-sectional area.

  The self-supply valve circuit 65 compensates for excess or deficiency of the hydraulic fluid in the hydraulic fluid supply unit 11. For example, the excess or deficiency of the hydraulic fluid supply unit 11 is caused by the following factors. In the drive cylinder device 35, since the drive piston rod 53 extends to the outside of the drive cylinder tube 49, when the drive piston 51 is driven, the occupied volume of the drive piston rod 53 in the drive cylinder tube 49 changes. To do. Accordingly, in the drive cylinder device 35, one of the inflow amount and the outflow amount of the hydraulic fluid is larger than the other. The same applies to the injection cylinder device 7. As will be described later, the conversion cylinder device 9 supplies and discharges the hydraulic fluid not only with the hydraulic fluid supply unit 11 but also with the accumulator 13 and the tank 15. For the above reasons, when the drive piston 51 is moved to one of the conversion side chamber 49r and the injection side chamber 49h and the working fluid is supplied from the one cylinder chamber to the conversion cylinder device 9 and the injection cylinder device 7, In the other cylinder chamber, the hydraulic fluid supplied from the conversion cylinder device 9 and the injection cylinder device 7 is insufficient or excessive.

  The self-supply valve circuit 65 includes an intermediate flow path 67 that connects the injection flow path 59 and the conversion flow path 61, a tank 15 that is connected to the intermediate flow path 67, and the intermediate flow path 67. And an injection side valve 69 provided between the tank 15 and a conversion side valve 71 provided between the conversion side flow path 61 and the tank 15 in the intermediate flow path.

  The injection side valve 69 is constituted by, for example, a pilot type check valve. The injection side valve 69 is opened when pilot pressure is introduced. Further, the injection side valve 69 prevents the flow from the injection side flow path 59 to the tank 15 and allows the flow from the tank 15 to the injection side flow path 59 when the pilot pressure is not introduced. In the injection side valve 69, the pressure of the conversion side flow path 61 is introduced as a pilot pressure.

  The conversion side valve 71 is constituted by, for example, a pilot type check valve. The conversion side valve 71 is opened when pilot pressure is introduced. When the pilot pressure is not introduced, the conversion side valve 71 blocks the flow from the conversion side flow path 61 to the tank 15 and allows the flow from the tank 15 to the conversion side flow path 61. Further, the conversion side valve 71 is introduced with the pressure of the injection side passage 59 as a pilot pressure.

  1 illustrates the case where the flow path for introducing pilot pressure of the injection side valve 69 is connected to the conversion side flow path 61, the introduction of pressure in the conversion side flow path 61 is It is also possible to connect the flow path for introducing pilot pressure to a portion of the intermediate flow path 67 closer to the conversion side flow path 61 than the conversion side valve 71. Similarly, the pressure of the injection side flow path 59 to the conversion side valve 71 may be introduced from an appropriate position.

  The self-supply valve circuit 65 operates as follows.

  When the drive piston 51 moves to the conversion side chamber 49r side and the working fluid is supplied from the conversion side chamber 49r to the conversion side channel 61, the conversion side valve 71 prevents the flow from the conversion side channel 61 to the tank 15. To do. On the other hand, the injection side valve 69 is opened by the pilot pressure introduced from the conversion side flow path 61.

  At this time, when the hydraulic fluid flowing into the injection side chamber 49h is insufficient, the hydraulic fluid in the tank 15 is supplied to the injection side chamber 49h via the injection side valve 59 via the injection side valve 69 due to negative pressure. Is compensated. On the other hand, when the hydraulic fluid flowing into the injection side chamber 49 h becomes excessive, the excessive hydraulic fluid in the injection side passage 59 is discharged to the tank 15 via the injection side valve 69.

  Contrary to the above, when the drive piston 51 moves to the injection side chamber 49h side and the working fluid is supplied from the injection side chamber 49h to the injection side flow path 59, the conversion side valve 71 and the injection side in the above-described operation. The role of the valve 69 is reversed, and the excess or deficiency of the hydraulic fluid in the conversion side chamber 49r is compensated.

  The hydraulic circuit 17 has a bypass passage 73 that communicates the large-diameter front chamber 27br of the conversion cylinder device 9 with the small-diameter front chamber 27ar. The bypass passage 73 is provided with a bypass valve VLa that can open and close the bypass passage 73.

  The bypass flow path 73 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 flow passage 73 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 VLa is constituted by, for example, a pilot type check valve. The bypass valve VLa is closed when pilot pressure is introduced. The bypass valve VLa prevents the flow from the small-diameter front chamber 27ar to the large-diameter front chamber 27br and allows the flow from the large-diameter front chamber 27br to the small-diameter front chamber 27ar when the pilot pressure is not introduced. .

  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 73, 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 pressure circuit 17 is provided in the rod side flow path 75 and the rod side flow path 75 that allow the accumulator 13 and the rod side chamber 25r to communicate with each other in order to allow the accumulator 13 to supply hydraulic fluid and remove back pressure surge. The rod-side valve VLb, the large-diameter front channel 77 communicating with the accumulator 13 and the large-diameter front chamber 27br, the large-diameter front valve VLe provided in the large-diameter front channel 77, the accumulator 13, and the large-diameter A large-diameter rear channel 79 communicating with the rear chamber 27bh and a large-diameter rear valve VLc provided in the large-diameter rear channel 79 are provided.

  The rod side valve VLb is constituted by, for example, a pilot type check valve. The rod side valve VLb is closed when pilot pressure is introduced. Further, the rod side valve VLb prevents the flow from the accumulator 13 to the rod side chamber 25r and allows the flow from the rod side chamber 25r to the accumulator 13 when the pilot pressure is not introduced.

  Therefore, when the injection piston 23 moves forward and the pilot pressure is not introduced, the flow from the rod side chamber 25r to the accumulator 13 is allowed to suppress the generation of surge pressure, and the pilot pressure is introduced. When it is, the flow from the rod side chamber 25r to the accumulator 13 is blocked, and all the hydraulic fluid in the rod side chamber 25r flows into the injection side flow path 59.

  The large-diameter front valve VLe is configured by a pilot type check valve capable of introducing a pilot pressure to be closed and a pilot pressure to be opened. The large-diameter front valve VLe prevents the flow from the accumulator 13 to the large-diameter front chamber 27br and allows the flow from the large-diameter front chamber 27br to the accumulator 13 when the pilot pressure is not introduced.

  Therefore, when the conversion piston 29 moves backward, the working fluid can be supplied from the accumulator 13 to the large-diameter front chamber 27br by introducing the pilot pressure to be opened. In addition, when the conversion piston 29 moves forward or backward, by introducing a pilot pressure to be closed, the flow between the accumulator 13 and the large-diameter front chamber 27br is prevented, and the large-diameter front chamber 27br and the small-diameter The working fluid can flow between the front chamber 27ar without waste. The large-diameter front valve VLe includes a fixed throttle.

  The large-diameter rear valve VLc is configured by a pilot check valve that can introduce a pilot pressure to be closed and a pilot pressure to be opened. The large-diameter rear valve VLc blocks the flow from the accumulator 13 to the large-diameter rear chamber 27bh and allows the flow from the large-diameter rear chamber 27bh to the accumulator 13 when pilot pressure is not introduced.

  Therefore, when the conversion piston 29 moves forward, the working fluid can be replenished from the accumulator 13 to the large-diameter rear chamber 27bh by introducing the pilot pressure to be opened. In addition, when the conversion piston 29 moves forward or backward, by introducing a pilot pressure to be closed, the flow between the large-diameter rear chamber 27bh and the accumulator 13 is prevented, and the large-diameter rear chamber 27bh operates. The hydraulic fluid can be flowed between the liquid supply unit 11 without waste. The large-diameter rear valve VLc includes a fixed throttle.

  The control device 19 includes, for example, a CPU 81, a memory 83 such as a ROM or a RAM, an input circuit 85, and an output circuit 87. The CPU 81 executes a program stored in the memory 83 and outputs a control signal for controlling the motor 31 and various valves via the output circuit 87 based on an input signal input via the input circuit 85. To do.

  The input of the signal to the input circuit 85 is, for example, the input device 89 that accepts a user's input operation, the conversion side pressure sensor 91 that detects the pressure in the conversion side channel 61, and the pressure in the head side chamber 25 h of the injection cylinder device 7. A head side pressure sensor 93 to detect, a rod side pressure sensor 95 to detect the pressure of the injection side flow path 59 (rod side chamber 25r), a pressure accumulation side pressure sensor 97 to detect the pressure of the liquid chamber 55o of the accumulator 13, and a conversion piston 29 They are a backward limit detector 99 that detects whether or not the backward limit has been reached, and a length measurement sensor 111 that detects the position of the injection plunger 5.

  The output circuit 87 outputs a signal, for example, a servo driver 39, a display 113 for displaying information to the user, various valves (bypass valve VLa, rod side valve VLb, large diameter rear valve VLc, small diameter rear side). A valve VLd, a large-diameter front valve VLe, etc.) are hydraulic circuits (not shown) for introducing pilot pressure.

  The backward limit detector 99 is constituted by, for example, a lever type switch. An operation member 115 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 115 comes into contact with the lever of the backward limit detector 99, and the backward limit detector 99 is turned on. When the conversion piston 29 moves forward from the backward limit, the operation member 115 is separated from the lever, and the backward limit detector 99 is turned off.

  The length measurement sensor 111 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 measurement sensor 111 is, for example, a scale portion 117 provided on the injection piston rod 21 along the direction in which the injection piston rod 21 extends, and a sensor portion 119 that is disposed opposite to the scale portion 117 and detects the movement of the scale portion 117. It is comprised by the linear encoder which has.

  Specifically, for example, when the length measuring sensor 111 is configured by a magnetic linear encoder, the scale unit 117 has N poles and S poles alternately arranged along the longitudinal direction of the injection piston rod 21. It is constituted by being done. The sensor unit 119 includes, for example, an MR element and a Hall IC. Further, for example, when the length measurement sensor 111 is configured by an optical linear encoder, the scale portion 117 is configured by arranging a transmission portion, a reflection portion, and the like along the longitudinal direction of the injection piston rod 21. Composed. The sensor unit 119 includes a light receiving element.

  The head side pressure sensor 93 and the rod side pressure sensor 95 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 93 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 95 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 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 the drive piston 51, various valves (VLa to VLe), the accumulator 13, 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 column of “drive piston moving direction”, the movement of the drive piston 51 to the conversion side chamber 49r side is “L”, the movement of the drive piston 51 to the injection side chamber 49h is “R”, and the stop of the drive piston 51 is “ -".

  In the “Pilot check valve” column, VL is omitted from the symbols VLa to VLe of various valves, and “a” to “e” columns corresponding to the various valves (VLa to VLe) 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.

  In the “Release” column of “Accumulator”, the hydraulic fluid is discharged from the accumulator 13 by a circle (◯), and the hydraulic fluid is not released from the accumulator 13 by a cross (×). Appropriate release is indicated by triangles (Δ). In the “Fill” column of “Accumulator”, the accumulator 13 is filled with the working fluid by a circle (◯), and the accumulator 13 is not filled with the working fluid by a cross (×). The proper filling is indicated by a triangle (Δ).

  The column of “conversion piston position” indicates that the backward limit detector 99 is turned on by “ON” and 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 “−”.

  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.

  The drive side valve 63 may be opened during a plurality of molding cycles, or only during a predetermined operation of each molding cycle (for example, from the start of the low speed injection operation to the retraction of the injection plunger 5). Open until completion).

  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 drives the motor 31, The drive piston 51 is moved to the conversion side chamber 49r side. As a result, the working fluid is supplied from the conversion side chamber 49r to the conversion side flow path 61.

  At this time, pilot pressure is not introduced to the small diameter rear valve VLd, and the flow from the conversion side flow path 61 to the small diameter rear chamber 27ch is blocked. Therefore, the hydraulic fluid supplied to the conversion side flow path 61 is supplied only to the large-diameter rear side chamber 27bh. Since the pressure receiving area of the large diameter portion 29b in the large diameter rear chamber 27bh is set to be relatively large, the conversion piston 29 advances 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.

  Note that the hydraulic fluid in the tank 15 is supplied to the small-diameter rear chamber 27ch via the negative-pressure control valve 121 due to, for example, negative pressure generated in the small-diameter rear chamber 27ch when the conversion piston 29 moves forward. The negative pressure control valve 121 includes, for example, a check valve that allows a flow from the tank 15 to the small-diameter rear chamber 27ch and prohibits a flow from the small-diameter rear chamber 27ch to the tank 15.

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

  The rod side valve VLb is closed by introducing pilot pressure. Accordingly, all the hydraulic fluid in the rod side chamber 25r pushed out by the injection piston 23 is discharged to the injection side flow path 59.

  A closing pilot pressure is introduced into the large-diameter rear valve VLc. Therefore, the hydraulic fluid supplied from the conversion side flow passage 61 to the large diameter rear chamber 27bh does not flow to the accumulator 13, but is used to apply pressure to the large diameter portion 29b.

  A closing pilot pressure is introduced into the large-diameter front valve VLe. Accordingly, the hydraulic fluid in the large-diameter front chamber 27br and the small-diameter front chamber 27ar pushed out by the conversion piston 29 does not flow into the accumulator 13, but is used to apply pressure to the injection piston 23.

(High-speed injection operation)
When the position of the injection plunger 5 based on the detection value of the length measuring sensor 111 reaches a predetermined high speed switching position, the control device 19 introduces pilot pressure to the small diameter rear valve VLd and opens the small diameter rear valve VLd. Thereby, the working fluid from the conversion side chamber 49r is supplied to the small-diameter rear side chamber 27ch via the conversion side flow path 61. Since 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, the conversion piston 29 moves forward at a relatively high speed, and consequently the injection piston 23 is also relatively Move forward at high speed. Accordingly, the injection plunger 5 is advanced at a relatively fast speed V _H, the P _H injection pressure rises.

  At this time, the pilot pressure for closing the rod side valve VLb is not introduced. Therefore, when the injection piston 23 moves at high speed, a surge pressure is generated in the rod side chamber 25r, and when the pressure in the rod side chamber 25r exceeds the pressure in the accumulator 13, the hydraulic fluid in the rod side chamber 25r pushes the rod side valve VLb. It opens and flows into the accumulator 13, and the surge pressure is removed. Note that the accumulator 13 is accumulating as much as the surge pressure is removed.

  An open pilot pressure is introduced into the large-diameter rear valve VLc. Therefore, the hydraulic fluid is supplied from the accumulator 13 to the large-diameter rear chamber 27bh. Since the pressure accumulated in the accumulator 13 is applied to the replenished hydraulic fluid, it is compared with the case where the hydraulic fluid is replenished from the tank 15 only by the negative pressure generated in the large-diameter rear chamber 27bh as the conversion piston 29 advances. Thus, the hydraulic fluid is efficiently replenished.

  Note that the bypass valve VLa and the large-diameter front valve VLe 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, in the deceleration injection operation, when a predetermined deceleration start condition is satisfied such that the injection plunger 5 reaches a predetermined deceleration position, the flow of hydraulic fluid to the small-diameter rear chamber 27ch is prohibited as will be described later. It starts when the conversion piston 29 is decelerated. 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 front small diameter portion 29 a into the front small diameter cylinder portion 27 a, the large diameter front side chamber 27 br and the front small diameter cylinder portion 27 a are blocked directly and indirectly via the bypass flow path 73. It will only be connected. 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 various valves VLa to VLe are in the same state as during low-speed injection. Therefore, pilot pressure is not introduced into the small diameter rear valve VLd, and the flow of hydraulic fluid to the small diameter rear chamber 27ch is prohibited. Thereby, the conversion piston 29 and by extension, the injection plunger 5 are decelerated.

(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 large-diameter front chamber 27br to the small-diameter front chamber 27ar is blocked. The large-diameter front valve VLe does not receive pilot pressure or introduces pilot pressure for opening. Thereby, the flow of the hydraulic fluid from the large-diameter front chamber 27br to the accumulator 13 is allowed. The rod-side valve VLb, the large-diameter rear valve VLc, and the small-diameter rear valve VLd are in the same state as the deceleration injection operation.

The conversion piston 29 moves forward while discharging the hydraulic fluid in the large-diameter front chamber 27br to the accumulator 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 difference between the pressure detected by the head side pressure 93 and the rod side pressure sensor 95 has reached a predetermined value, or that the injection plunger 5 has reached a predetermined position.

  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)
When the molten metal solidifies, the control device 19 rotates the motor 31 so as to move the drive piston 51 toward the injection side chamber 49h. Thereby, the working fluid is supplied from the injection side chamber 49h to the injection side flow path 59. 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.

  The hydraulic fluid supplied to the injection side flow path 59 is supplied to the rod side chamber 25r, and 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 rod side valve VLb is closed by introducing pilot pressure. Therefore, all of the hydraulic fluid supplied from the injection side flow path 59 to the rod side chamber 25r is used for retreating the injection piston 23.

  The large-diameter rear valve VLc is closed by introducing pilot pressure. Accordingly, all of the hydraulic fluid discharged from the large-diameter rear chamber 27bh as the conversion piston 29 moves backward is supplied to the conversion-side flow path 61.

  The small-diameter rear valve VLd is opened by introducing pilot pressure. Further, even if the pilot pressure is not introduced, the small-diameter rear valve VLd allows the flow from the large-diameter rear chamber 27bh to the conversion-side flow path 61. Accordingly, the hydraulic fluid discharged from the small-diameter rear chamber 27ch as the conversion piston 29 moves backward is supplied to the conversion-side flow path 61.

  The large-diameter front valve VLe is introduced with a pilot pressure that opens 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 accumulator 13 to the large-diameter front chamber 27br. In addition, since the pressure accumulated in the accumulator 13 is applied to the replenished hydraulic fluid, the hydraulic fluid is replenished from the tank 15 only by the negative pressure generated in the large-diameter front chamber 27br as the conversion piston 29 moves backward. Compared to the above, the hydraulic fluid is efficiently replenished.

  The large-diameter front valve VLe is introduced with a pilot pressure that closes after the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a. As a result, the head side chamber 25h, the small-diameter front chamber 27ar, and the large-diameter front chamber 27br are sealed, and the conversion piston 29 is efficiently retracted by the retraction of the injection piston 23.

  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 115. Further, replenishment to the large-diameter front chamber 27br before the front small-diameter portion 29a is pulled out from the front small-diameter cylinder portion 27a is constituted by a check valve capable of introducing a pilot pressure to open the bypass valve VLa, and the small-diameter front chamber 27ar. It is also possible to supply the working fluid to the large-diameter front side chamber 27br via the bypass channel 73. The bypass valve VLa may or may not be introduced with pilot pressure.

(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 length measurement sensor 111. 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 99.

  Note that the reverse movement of the injection piston 23 and the conversion piston 29 is generally the reverse operation of the injection operation and the pressure increasing operation, so ideally the injection piston 23 and the conversion piston 29 are in the initial stage of the injection operation. At the same time, the backward limit is reached. However, in actuality, one of them may reach the backward limit first due to leakage of hydraulic fluid or the like. In this case, the method of moving the piston that has reached the backward limit to the backward limit may be selected as appropriate, but is performed as follows, for example.

  When the injection piston 23 reaches the backward limit first, as shown in the column “Injection piston backward limit”, the control device 19 performs the rod side valve VLb with respect to the operation of the above-mentioned “injection piston backward”. The pilot pressure for opening to the large-diameter front side valve VLe is introduced while the introduction of the pilot pressure to is stopped. Thereby, the working fluid is supplied from the injection side chamber 49h to the accumulator 13 via the rod side chamber 25r and the rod side valve VLb, and the working fluid is supplied from the accumulator 13 to the large diameter front side chamber 27br via the large diameter front valve VLe. The conversion piston 29 moves backward. However, at this time, since the injection piston 23 moves forward due to the difference in pressure receiving area between the rod side chamber 25r and the head side chamber 25h, the control device 19 closes the rod side valve VLb and the large-diameter front valve VLe at an appropriate timing, and again The injection piston 23 is retracted together with the conversion piston 29, and both are made to reach the retreat limit.

  When the conversion piston 29 reaches the reverse limit first, as shown in the column of “conversion piston reverse limit”, the control device 19 performs the large-diameter front valve with respect to the operation of the “injection piston reverse” described above. The introduction of the pilot pressure to VLe is stopped, or the pilot pressure that opens to the large-diameter front valve VLe is introduced. As a result, the hydraulic fluid in the head-side chamber 25h, the small-diameter front chamber 27ar, and the large-diameter front chamber 27br is allowed to be discharged to the accumulator 13, and as a result, the injection piston 23 is allowed to retract without the conversion piston 29 retracting. . At this time, the accumulator 13 is pressurized.

(Accumulator filling)
When the injection piston 23 and the conversion piston 29 reach the backward limit, the control device 19 introduces pilot pressure to the rod side valve VLb, opens the rod side valve VLb, and allows the flow from the rod side chamber 25r to the accumulator 13. Further, the control device 19 does not introduce pilot pressure into the large-diameter front valve VLe and the large-diameter rear valve VLc, or introduces a pilot pressure that closes, so that the flow of hydraulic fluid from the accumulator 13 to the conversion cylinder device 9 is made. Ban. Thereby, the hydraulic fluid discharged | emitted from 49 h of injection | emission side chambers is stored in the accumulator 13 via the rod side chamber 25r.

(Preparation for the next cycle)
When both the injection piston 23 and the conversion piston 29 reach the backward limit, the control device 19 stops the motor 31 and prepares for the next cycle. In preparation for the next cycle, for example, each valve (VLa to VLe) is in a state of low-speed injection operation.

  Note that the target rotational speed of the motor 31 (drive piston 51) is basically constant over the above-described operations. However, the target rotational speed corresponding to each operation may be set such that the target rotational speed of the motor 31 in the high-speed injection operation is set faster than the target rotational speed of the motor 31 in the low-speed injection operation or the deceleration injection operation. Further, the control of the motor 31 may be switched from speed control for obtaining a desired number of revolutions to torque control for obtaining a desired torque in accordance with switching from the injection operation to the pressure increasing operation.

  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, and the hydraulic fluid that supplies the hydraulic fluid to the injection cylinder device 7 and the conversion cylinder device 9. And a supply unit 11. 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 fluid supply unit 11 includes a drive cylinder device 35 communicating with the injection cylinder device 7 and the conversion cylinder device 9, and a motor 31 that slides the drive piston 51 in the drive cylinder tube 49 by driving the drive piston rod 53. Have

  Accordingly, by supplying the working fluid to the large-diameter rear chamber 27bh of the large-diameter cylinder portion 27b, the injection plunger 5 is advanced at a low speed, and by supplying the working fluid to the rear-side small-diameter cylinder portion 27c, the injection plunger at a high speed. 5 can be advanced. That is, the speed change operation can be performed only by switching the supply destination of the hydraulic fluid, and the injection device 1 can be simplified and enhanced in function. For example, it is possible to switch from the low-speed injection operation to the high-speed injection operation only by providing a pilot check valve (VLd) in the small diameter side branch flow path 61b. Further, since the rotation speed of the motor 31 is changed according to the ratio of the pressure receiving areas of the drive cylinder device 35, the conversion cylinder device 9 and the injection cylinder device 7, the correlation between the rotation speed of the motor 31 and the speed of the injection plunger 5 is grasped. As compared with the case where hydraulic fluid is supplied to the conversion cylinder device 9 by a high-pressure accumulator, the diameter of each cylinder device, the setting of control variables, and the like are facilitated.

  The injection device 1 includes a hydraulic pressure circuit 17 that controls the flow of hydraulic fluid between the hydraulic fluid supply unit 11 and the injection cylinder device 7 and the conversion cylinder device 9. The drive piston rod 53 extends to the conversion side chamber 49r side. Further, the hydraulic circuit 17 has a self-supply valve circuit 65. Therefore, the pressure increasing operation can be suitably performed. That is, in the present embodiment, the pressure receiving area in the conversion side chamber 49r of the drive piston 51 is small compared to the case where the drive piston rod 53 extends to the injection side chamber 49h contrary to the present embodiment. In principle, even if the driving force of the motor 31 is reduced, a large pressure can be applied to the conversion piston 29 to increase the pressure. Since the drive piston rod 53 extends to the conversion side chamber 49r, in the drive cylinder device 35, the amount of hydraulic fluid flowing out from the conversion side chamber 49r during pressure increase is greater than the amount of hydraulic fluid flowing into the injection side chamber 49h. There are few. On the other hand, in the conversion cylinder device 9 and the injection cylinder device 7, due to the injection piston rod 21 extending and the like, the amount of hydraulic fluid flowing from the conversion side chamber 49r to the injection side chamber 49h is increased at the time of pressure increase. There is little outflow of hydraulic fluid. Therefore, when the pressure is increased, the hydraulic fluid is always insufficient in the injection side chamber 49h. In this case, there is a possibility that a negative pressure is generated in the injection side chamber 49h and the efficiency of the pressure increase is lowered. However, by appropriately supplying hydraulic fluid from the self-supply valve circuit 65, such inconvenience is alleviated.

  The injection device 1 includes a gas-type accumulator 13, a large-diameter rear valve VLc capable of allowing or prohibiting a flow between the accumulator 13 and the large-diameter rear chamber 27bh, and a flow between the accumulator 13 and the rod-side chamber 25r. And a rod side valve VLb that can permit or prohibit the above. Therefore, it is possible to reliably remove the back pressure surge of the injection cylinder device 7 while rapidly supplying the working fluid to the conversion cylinder device 9. Moreover, as described above, the high-speed injection operation and the pressure increasing operation can be performed without the accumulator 13, and therefore the accumulator 13 is used for replenishing hydraulic fluid and removing surges for the purpose of suppressing the generation of negative pressure. It may be of a sufficiently low pressure, and can be reduced in size, cost and safety.

  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 liquid, and may be water, for example.

  In the drive cylinder device (35), the drive piston rod (53) may extend to the injection side chamber (49h). When the drive piston rod extends to the injection side chamber, the amount of outflow from the conversion side chamber becomes larger than the amount of inflow to the injection side chamber when pressure is increased. On the other hand, as described above, in the conversion cylinder device (9) and the injection cylinder device (7), the injection piston rod (21) extends to the rod side chamber (25r), so that the working fluid from the conversion side chamber is removed. The outflow amount of the working fluid to the injection side chamber is smaller than the inflow amount. Therefore, at the time of pressure increase or the like, the excess or deficiency of the hydraulic fluid in the drive cylinder device is alleviated by the excess or deficiency of the hydraulic fluid in the conversion cylinder device and the injection cylinder device. As a result, it is possible to reduce the tank and the like. In particular, when the diameter (d5) of the injection piston rod 21 and the diameter (d6) of the drive piston rod are the same, the hydraulic fluid in the injection cylinder device is excessive or insufficient, and the hydraulic fluid in the drive cylinder device is excessive or insufficient. Therefore, it is easy to calculate the amount of replenishment of hydraulic fluid in various processes, and the design and control are facilitated.

  The electric motor is not limited to a rotary type. Further, the transmission mechanism (33) 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 drive piston, but may be provided in parallel with the drive piston.

  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 on the rear small diameter cylinder portion (27c) side of the large diameter cylinder portion (27b) of the large diameter portion (29b) is larger than the pressure receiving area of the front small diameter cylinder portion (27a) of the front small diameter portion (29a). There must be. 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 , the hydraulic fluid is supplied to the small-diameter rear chamber (27ch) to move at low speed, and the large-diameter rear chamber (27bh) is moved. The hydraulic fluid may be supplied to perform high speed movement. 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 small-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, when the front small diameter portion (29a) is not inserted into the front small diameter cylinder portion (27a), the hydraulic fluid should be pushed out from the small diameter front chamber (27br) to the head side chamber (25h). The resistance applied to the hydraulic fluid can be reduced, and the high-speed injection operation can be reliably performed.

  The hydraulic fluid may be supplied to each cylinder chamber (25r, 25h, 27ar, 27br, 27bh, 27ch) at an appropriate timing by an appropriately configured hydraulic circuit. For example, in the embodiment, a pilot type check valve may be provided in the large diameter side branch flow path 61a instead of the small diameter rear valve VLd or in addition to the small diameter rear valve VLd. In the high-speed injection operation, the flow of hydraulic fluid from the drive cylinder device 35 to the large-diameter rear chamber 27bh is blocked, and the hydraulic fluid is supplied from the drive cylinder device 35 only to the small-diameter rear chamber 27ch, and the large-diameter rear chamber 27bh. The hydraulic fluid may be supplied from the tank by negative pressure, or the hydraulic fluid may be supplied from a low-pressure accumulator. In this case, it is possible to further increase the speed by supplying the hydraulic fluid from the drive cylinder device 35 only to the small-diameter rear chamber 27ch.

  Further, for example, each check valve may be another direction control valve such as a switching valve. As the check valve, a valve that can introduce a closed pilot pressure, a valve that can introduce an open pilot pressure, a valve that can introduce both a closed pilot pressure and an open pilot pressure, and a valve that is not pilot-type may be used as appropriate.

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 ... Working fluid supply part, 21 ... Injection piston rod, 23 ... Injection piston, 25 ... Injection cylinder tube, 25r ... Rod side chamber 25h ... head side chamber, 27 ... conversion cylinder tube, 27a ... front small diameter cylinder portion, 27b ... large diameter cylinder portion, 27c ... rear side small cylinder portion, 27bh ... large diameter rear side chamber, 27ch ... small diameter rear side chamber, 29 ... conversion Piston, 29a ... Front side small diameter part, 29b ... Large diameter part, 29c ... Rear side small diameter part, 31 ... Motor (electric motor), 35 ... Drive cylinder device, 49 ... Drive cylinder tube, 51 ... Drive piston, 53 ... Drive piston rod , 49h: injection side chamber, 49r: conversion side chamber, 105 ... cavity.

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, 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 fluid supply section for supplying hydraulic fluid to the injection cylinder device and 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 fluid supply unit is
A drive cylinder tube, a drive piston slidably accommodated in the drive cylinder tube, and a drive piston rod fixed to the drive piston and extending to the outside of the drive cylinder tube; The inside of the injection side chamber communicated with the rod side chamber by the drive piston, the large diameter rear side chamber that is closer to the rear small diameter cylinder portion than the large diameter portion of the large diameter cylinder portion, and the small diameter cylinder portion A drive cylinder device partitioned into a conversion side chamber communicated with a small diameter rear chamber opposite to the large diameter cylinder portion from the small diameter portion;
An electric motor that slides the drive piston in the drive cylinder tube by driving the drive piston rod;
An injection device for a molding machine. 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 claim 1, wherein the conversion piston has a front small-diameter portion that can slide on the front small-diameter cylinder portion. The injection device for a molding machine according to claim 2, wherein the conversion piston is accommodated in the conversion cylinder tube so that the front small diameter portion can be inserted into and extracted from the large diameter cylinder portion side to the front small diameter cylinder portion. A hydraulic circuit that controls the flow of hydraulic fluid between the hydraulic fluid supply unit, the injection cylinder device, and the conversion cylinder device;
The drive piston rod extends to the conversion side chamber side,
The hydraulic circuit is
An injection-side flow path communicating the injection-side chamber and the rod-side chamber;
A conversion-side flow path communicating the conversion-side chamber and the head-side chamber;
An intermediate flow path connecting the conversion side flow path and the emission side flow path;
A tank connected in the middle of the intermediate flow path;
A pilot-type check valve provided between the conversion-side flow path and the tank in the intermediate flow path, wherein the pressure of the injection-side flow path is introduced as a pilot pressure for opening the check valve When the pilot pressure is not introduced, a conversion-side check valve that prevents the flow from the conversion-side flow path to the tank and allows the flow from the tank to the conversion-side flow path,
A pilot type check valve provided between the injection side flow path and the tank in the intermediate flow path, wherein the pressure of the conversion side flow path is introduced as a pilot pressure for opening the check valve And when the pilot pressure is not introduced, an injection-side check valve that prevents the flow from the injection-side flow path to the tank and allows the flow from the tank to the injection-side flow path,
The injection device for a molding machine according to any one of claims 1 to 3. The injection device for a molding machine according to any one of claims 1 to 3, wherein the drive piston rod extends toward the injection side chamber and has the same diameter as the injection piston rod. The injection device for a molding machine according to any one of claims 1 to 5, further comprising a small-diameter rear side valve capable of allowing or prohibiting a flow of hydraulic fluid from the conversion-side chamber to the small-diameter rear side chamber. A detector for detecting the position of the injection plunger;
Based on the detection result of the detector, a control device for controlling the electric motor and the small-diameter rear valve;
Have
When supplying the molding material to the cavity, the control device drives the drive piston by the electric motor in a state where the small-diameter rear valve prohibits the flow of hydraulic fluid from the conversion-side chamber to the small-diameter rear chamber. The hydraulic fluid is supplied from the conversion side chamber to the large-diameter rear chamber to start the advancement of the injection plunger, and then the small-diameter rear side when the position detected by the detector reaches a predetermined high-speed switching position. The injection device for a molding machine according to claim 6, wherein a valve allows a flow of hydraulic fluid from the conversion-side chamber to the small-diameter rear chamber and supplies the hydraulic fluid to the small-diameter rear chamber to accelerate the injection plunger. A gas accumulator,
A large-diameter rear valve capable of allowing or prohibiting a flow between the gas accumulator and the large-diameter rear chamber;
A rod side valve capable of allowing or prohibiting a flow between the gas accumulator and the rod side chamber;
The injection apparatus for a molding machine according to any one of claims 1 to 7. The injection device for a molding machine according to claim 8, wherein the gas held in the gas accumulator is less than 1 MPa.

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