JP6764276B2 - Injection device and molding machine - Google Patents

Description

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

As an injection device, a plunger that pushes a molding material into a mold is driven by an injection cylinder (for example, Patent Document 1). The injection cylinder has a piston rod connected to a plunger, an injection piston fixed to the piston rod, and a cylinder portion for accommodating the injection piston. The inside of the cylinder portion is divided into a rod side chamber on the side where the piston rod extends by the injection piston and a head side chamber on the opposite side. Then, when the hydraulic fluid (for example, oil) is supplied to the head side chamber, the injection piston moves toward the piston rod side, whereby the plunger advances toward the mold. The speed of the injection cylinder (in other words, the injection speed) is controlled by, for example, a flow rate control valve (meter-out circuit) that controls the flow rate of the hydraulic fluid discharged from the rod side chamber (for example, Patent Document 1).

Note that Patent Document 1 discloses a double-rod type cylinder used as a booster for accumulating an accumulator.

Japanese Unexamined Patent Publication No. 2009-131868

In the case of using a meter-out circuit, ideally, the injection piston advances at a speed corresponding to the flow rate of the hydraulic fluid discharged from the rod side chamber. However, in reality, for example, when the supply of the hydraulic fluid to the head side chamber is started, the hydraulic fluid in the rod side chamber is compressed by the pressure applied to the hydraulic fluid in the rod side chamber from the injection piston and discharged from the rod side chamber. The injection piston may move forward at a speed exceeding the speed corresponding to the flow rate of the hydraulic fluid. That is, so-called jumping (jumping) may occur. As a result, the quality of the molded product may deteriorate.

Therefore, it is preferable to provide an injection device and a molding machine capable of reducing the risk of jumping.

In the injection device according to one aspect of the present invention, the front rod connected to the plunger sliding in the sleeve, the injection piston fixed to the front rod, and the injection piston fixed to the opposite side of the front rod. An injection cylinder having a rear rod to be slidable, a cylinder portion slidably accommodating the injection piston, a hydraulic pressure device for supplying a working liquid to the injection cylinder, and a control device for controlling the hydraulic pressure device. The cylinder portion has a rod side chamber in which the front side rod is arranged and a head side chamber in which the rear side rod is arranged, and the control device is provided in the rod side chamber before the start of injection. It has a rod-side pressure control unit that controls the hydraulic pressure device so that the pressure is higher than the tank pressure.

Preferably, the cross-sectional area of the rear rod is equal to or larger than the cross-sectional area of the front rod.

Preferably, the hydraulic device has a hydraulic pressure source and a flow path connecting the hydraulic pressure source and the rod side chamber, and the control device has the flow path from the hydraulic pressure source to the flow path. Further provided with a plunger retreat control unit that controls the hydraulic device so as to retreat the plunger by supplying the hydraulic fluid to the rod side chamber via the rod side chamber, the rod side pressure control unit is provided from the hydraulic pressure source. The hydraulic device is controlled so as to apply pressure to the rod side chamber through the flow path.

Preferably, the injection cylinder further includes a pressure-increasing piston slidably housed in the cylinder portion, and the pressure-increasing piston forms the head side chamber and the rear side chamber inside the cylinder portion. It has a large-diameter piston portion whose pressure receiving area in the rear side chamber is larger than the pressure receiving area in the head side chamber, and the rear rod is slidably inserted into the pressure boosting piston and is opposite to the injection piston. The end face on the side is exposed to the rear chamber.

The injection device according to one aspect of the present invention has a front rod connected to a plunger sliding in the sleeve, an injection piston fixed to the front rod, and fixed to the opposite side of the injection piston to the front rod. The cylinder portion includes an injection cylinder having a rear rod to be formed, a pressure boosting piston provided on the rear rod side, and a cylinder portion slidably accommodating the injection piston and the pressure boosting piston. Is divided into a rod side chamber in which the front side rod is arranged by the injection piston and a head side chamber in which the rear side rod is arranged, and further, a rear side chamber is formed in the head side chamber by the pressure boosting piston. The pressure boosting piston has a large-diameter piston portion in which the pressure receiving area in the rear side chamber is larger than the pressure receiving area in the head side chamber, and the rear rod is slidably inserted into the pressure boosting piston. The end face opposite to the injection piston is exposed in the rear chamber.

Preferably, the hydraulic device has a flow rate control valve that controls the flow rate of the hydraulic fluid discharged from the rod side chamber.

The molding machine according to one aspect of the present invention is a molding machine having the above-mentioned injection device, a mold-clamping device for mold-clamping the mold, and an extrusion device for extruding a molded product from the mold.

According to the above configuration, the risk of jumping can be reduced.

The schematic diagram which shows the structure of the die casting machine which has the injection apparatus which concerns on 1st Embodiment of this invention. The schematic diagram which shows the structure of the hydraulic pressure system in the injection apparatus of FIG. A partially enlarged view of FIG. The timing chart for demonstrating the operation of the injection apparatus of FIG. The schematic diagram which shows the structure of the hydraulic system in the injection apparatus which concerns on 2nd Embodiment of this invention. The schematic diagram which shows the structure of the drive mechanism in the injection apparatus which concerns on 3rd Embodiment of this invention. The schematic diagram which shows the structure of the hydraulic pressure system in the injection apparatus of FIG. The timing chart for demonstrating the operation of the injection apparatus of FIG. The schematic diagram which shows the structure of the hydraulic system in the injection apparatus which concerns on 4th Embodiment of this invention. 10 (a) and 10 (b) are schematic views showing a modified example of the injection cylinder.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the second and subsequent embodiments, the same or similar configurations as those of the embodiments already described may be designated by reference numerals to the configurations of the embodiments already described, and the description may be omitted. is there. Even when a configuration similar (corresponding to) the configuration of the embodiment described above is assigned a code different from the code of the embodiment described above, the matters not otherwise specified are the same as the configuration of the embodiment already described. The same is true.

<First Embodiment>
(Overall configuration of die casting machine)
FIG. 1 is a side view showing a configuration of a main part of the die casting machine 1 according to the first embodiment of the present invention, including a cross-sectional view in part.

The die casting machine 1 injects a molten metal material (molten metal) into a mold 101 (a space such as a cavity Ca; the same applies hereinafter) and solidifies the molten metal in the mold 101 to perform die casting. It manufactures products (molded products). The metal is, for example, aluminum or an aluminum alloy.

The mold 101 includes, for example, a fixed mold 103 and a moving mold 105. In the description of the present embodiment, for convenience, the cross section of the fixed mold 103 or the moving mold 105 is shown by one type of hatching, but these molds may be of a direct carving type or a nested type. It may be a thing. Further, the fixed mold 103 and the moving mold 105 may be combined with a core or the like.

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

The machine body 3 includes, for example, a mold clamping device 7 that opens and closes and clamps the mold 101, an injection device 9 that injects molten metal into the mold 101, and a die-cast product fixed mold 103 or a moving mold 105 (. FIG. 1 has an extrusion device 11 that extrudes from a moving die 105). In the machine main body 3, the configurations other than the injection device 9 (for example, the configurations of the mold clamping device 7 and the extrusion device 11) may be the same as various known configurations.

In the molding cycle, the mold clamping device 7 moves the moving mold 105 toward the fixed mold 103 to close the mold. Further, the mold clamping device 7 applies a mold clamping force corresponding to the extension amount of the tie bar (reference numeral omitted) to the mold 101 to perform mold clamping. A cavity Ca having the same shape as the molded product is formed in the mold 101 that has been molded. The injection device 9 injects and fills the molten metal into the cavity Ca. The molten metal filled in the cavity Ca is deprived of heat by the mold 101, cooled, and solidified. As a result, a molded product is formed. After that, the mold clamping device 7 moves the moving mold 105 away from the fixed mold 103 to open the mold. At this time, or after that, the extruder 11 extrudes the molded product from the moving mold 105.

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

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

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

(Injection device configuration)
The injection device 9 has, for example, a sleeve 21 that leads into the mold 101, a plunger 23 that is slidable in the sleeve 21, and an injection drive unit 25 that drives the plunger 23. In the description of the injection device 9, the mold 101 side may be referred to as the front side, and the opposite side may be referred to as the rear side.

The sleeve 21 is, for example, a tubular member connected to the fixed mold 103, and a supply port 21a for receiving the molten metal into the sleeve 21 is opened on the upper surface thereof. The plunger 23 has a plunger tip 23a that can slide in the sleeve 21 in the front-rear direction, and a plunger rod 23b whose tip is fixed to the plunger tip 23a.

When the mold clamping of the mold 101 by the mold clamping device 7 is completed, one shot of molten metal is poured into the sleeve 21 from the supply port 21a by a hot water supply device (not shown). Then, when the plunger 23 slides forward in the sleeve 21 from the position shown in the drawing, the molten metal in the sleeve 21 is pushed out (injected) into the mold 101.

(Basic configuration of injection drive unit)
FIG. 2 is a schematic view showing the configuration of the injection drive unit 25. First, the basic configuration of the injection drive unit 25 will be described, and then the configuration for preventing jumping will be described.

As shown in FIGS. 1 and 2, the injection drive unit 25 is, for example, a hydraulic type, and supplies an injection cylinder 27 connected to the plunger 23 and a hydraulic fluid (for example, oil) to the injection cylinder 27. It has a hydraulic pressure device 28 (FIG. 2) to perform.

As shown in FIG. 2, the injection cylinder 27 is composed of, for example, a so-called direct-coupled booster cylinder. Specifically, for example, the injection cylinder 27 is fixed to the cylinder portion 29, the injection piston 31 and the pressure boosting piston 33 slidable inside the cylinder portion 29, and the injection piston 31, and extends from the cylinder portion 29. It has a front rod 35.

The cylinder portion 29 has, for example, a small-diameter cylinder portion 29a and a large-diameter cylinder portion 29b connected to the rear end of the small-diameter cylinder portion 29a (the side opposite to the extending side of the front rod 35). The small-diameter cylinder portion 29a and the large-diameter cylinder portion 29b are, for example, cylindrical bodies having a circular internal cross-sectional shape. The large-diameter cylinder portion 29b has a larger diameter (cross section) than the small-diameter cylinder portion 29a. In FIG. 2, for convenience, the front end portion and the outer peripheral portion of the cylinder portion 29 are shown by one hatching, and the rear end portion of the cylinder portion 29 is shown by one hatching, but the number of members constituting the cylinder portion 29 is shown. And the division position thereof may be set as appropriate.

The injection piston 31 is slidably arranged in the small diameter cylinder portion 29a. The inside of the small-diameter cylinder portion 29a is divided into a rod side chamber 29r on the side where the front rod 35 extends and a head side chamber 29h on the opposite side by the injection piston 31. By selectively supplying the hydraulic fluid to the head side chamber 29h and the rod side chamber 29r, the injection piston 31 moves in the small diameter cylinder portion 29a in the front-rear direction.

The pressure boosting piston 33 has a small-diameter piston portion 33a that can slide the small-diameter cylinder portion 29a and a large-diameter piston portion 33b that can slide the large-diameter cylinder portion 29b. The inside of the large-diameter cylinder portion 29b is divided into a front chamber 29f on the small-diameter cylinder portion 29a side and a rear chamber 29e on the opposite side by the large-diameter piston portion 33b. From another viewpoint, the inside of the cylinder portion 29 is divided into a head side chamber 29h and a rear side chamber 29e on the opposite side by a pressure boosting piston 33.

Therefore, when the pressure of the front side chamber 29f is released, the pressure receiving area of the pressure increasing piston 33 (small diameter piston portion 33a) in the rear side chamber 29e of the pressure increasing piston 33 (large diameter piston portion 33b) is compared with the pressure receiving area of the head side chamber 29h. Therefore, the pressure boosting piston 33 can apply a pressure higher than the pressure received from the hydraulic fluid in the rear concubine 29e to the hydraulic fluid in the head concubine 29h. As a result, the injection cylinder 27 exerts a pressure increasing function.

The pressure receiving area of the piston referred to in the description of the present embodiment is an area obtained by projecting the area in which the pressure of the hydraulic fluid acts on the piston in the moving direction (axial direction) of the piston. Therefore, the pressure receiving area is basically unaffected by the unevenness of the surface of the piston exposed to the cylinder chamber. Further, unless the shape of the piston is peculiar, the pressure receiving area is substantially the same as the cross section of the piston. If the piston is cylindrical with a diameter d, the pressure receiving area is π × (d / 2) ² .

The pressure boosting piston 33 may have, for example, a protruding portion 33c (reference numeral: FIG. 3) that protrudes forward from the small-diameter piston portion 33a and can come into contact with the rear end surface of the injection piston 31. The protruding portion 33c has a smaller diameter than the small diameter piston portion 33a. Such a protruding portion 33c is, for example, when the hydraulic fluid is supplied to the rod side chamber 29r to retract the injection piston 31 and the pressure boosting piston 33 is pushed rearward by the injection piston 31 to move the pressure boosting piston 33 rearward. , It is useful to make the positions of both pistons suitable and to secure a gap between both pistons for the hydraulic fluid to enter.

However, the protruding portion 33c may be omitted. Further, when the protruding portion 33c is separated from the injection piston 31, the presence of the protruding portion 33c does not affect the pressure receiving area of the pressure boosting piston 33 in the head side chamber 29h. Therefore, in the description of this embodiment, the protruding portion 33c is basically ignored. For example, the pressure-receiving area of the small-diameter piston portion 33a in the head-side chamber 29h basically refers to the pressure-receiving area of the entire pressure-increasing piston 33 in the head-side chamber 29h.

The pressure boosting piston 33 has, for example, an intermediate portion 33e (reference numeral is FIG. 3) having a diameter smaller than that of the small diameter piston portion 33a between the small diameter piston portion 33a and the large diameter piston portion 33b. By providing such an intermediate portion 33e, for example, the sliding area between the pressure boosting piston 33 (small diameter piston portion 33a) and the small diameter cylinder portion 29a can be reduced. However, the small diameter piston portion 33a may be directly fixed to the large diameter piston portion 33b without providing such an intermediate portion 33e.

As shown in FIG. 1, the injection cylinder 27 is arranged coaxially with the plunger 23. The tip of the front rod 35 is connected to the rear end of the plunger 23 via a coupling (reference numeral omitted). The cylinder portion 29 is fixedly provided with respect to a mold clamping device (not shown) or the like. Therefore, the movement of the injection piston 31 with respect to the cylinder portion 29 causes the plunger 23 to move forward or backward in the sleeve 21.

The hydraulic device 28 (FIG. 2) includes, for example, a tank 37 for storing the hydraulic fluid, a pump 39 capable of delivering the hydraulic fluid of the tank 37, an accumulator 41 capable of discharging the accumulated hydraulic fluid, these, and injection. A plurality of flow paths (43A to 43F, etc.) that connect the cylinders 27 to each other and a plurality of valves (45, 47, 49, 51, 53, 55, etc.) that control the flow of the hydraulic fluid in the plurality of flow paths are provided. Have. In FIG. 2 and the like, tanks 37 may be shown at a plurality of locations for convenience of illustration, but in reality, the tanks 37 shown at the plurality of locations may be integrated into one tank 37.

The tank 37 is, for example, an open tank and holds the hydraulic fluid under atmospheric pressure. The tank 37 supplies the hydraulic fluid to the injection cylinder 27 via, for example, the pump 39 and the accumulator 41, and also houses the hydraulic fluid discharged from the injection cylinder 27.

The pump 39 is driven by a pump electric motor 40 to deliver a hydraulic fluid. The pump 39 may be of an appropriate type such as a rotary pump, a plunger pump, a constant capacity pump, a variable capacity pump, a one-way pump, and a bidirectional (two-way) pump. The electric motor 40 for a pump may be of an appropriate type such as a DC motor, an AC motor, an induction motor, a synchronous motor, or a servo motor. The pump 39 (pump electric motor 40) may be constantly driven while the die casting machine 1 is in operation, or may be driven only when necessary. The pump 39 contributes, for example, to the supply of the hydraulic fluid to the accumulator 41 (accumulation of the accumulator 41) and the supply of the hydraulic fluid to the injection cylinder 27.

The accumulator 41 is, for example, a weight type, a spring type, a gas pressure type (including a pneumatic type), a cylinder type or a Prada type. In the illustrated example, the accumulator 41 is of a cylinder type, and has a cylinder portion 41a and a piston 41b that divides the cylinder portion 41a into a liquid chamber 41e and a gas chamber 41f. The liquid chamber 41e contains a working fluid, and the gas chamber 41f is filled with a gas (for example, air or nitrogen). The hydraulic fluid is supplied to the liquid chamber 41e, and the piston 41b moves to the gas chamber 41f side, so that the gas in the gas chamber 41f is compressed and the accumulator 41 is accumulating pressure. Further, the hydraulic fluid is discharged from the liquid chamber 41e by utilizing the pressure of the gas. The accumulator 41 contributes, for example, to the supply of the hydraulic fluid to the injection cylinder 27.

The first flow path 43A connects the pump 39 and the accumulator 41 (liquid chamber 41e). Thereby, for example, the hydraulic fluid can be supplied from the pump 39 to the accumulator 41 to accumulate the pressure of the accumulator 41.

The second flow path 43B connects the accumulator 41 (liquid chamber 41e) and the head side chamber 29h. Thereby, for example, the hydraulic fluid can be supplied from the accumulator 41 to the head side chamber 29h to advance the injection piston 31.

The third flow path 43C connects the accumulator 41 (liquid chamber 41e) and the rear chamber 29e. Thereby, for example, the hydraulic fluid can be supplied from the accumulator 41 to the rear concubine 29e, and the hydraulic fluid in the head concubine 29h can be pressurized by the pressure boosting piston 33.

The fourth flow path 43D connects the rod side chamber 29r and the tank 37. Thereby, for example, the hydraulic fluid in the rod side chamber 29r whose volume decreases as the injection piston 31 advances can be discharged to the tank 37.

One end of the fifth flow path 43E is connected to the rod side chamber 29r, and the other end is connected to the pump 39 or the tank 37 by an operation valve 51 described later.

One end of the sixth flow path 43F is connected to the head side chamber 29h, and the other end is connected to the pump 39 or the tank 37 by an operation valve 51 described later.

The plurality of channels (43A to 43F, etc.) are composed of, for example, steel pipes, flexible hoses, or metal blocks. A part of the plurality of flow paths may be shared as appropriate. For example, in the example of FIG. 1, the first flow path 43A to the third flow path 43C are partly shared on the accumulator 41 side, and the fourth flow path 43D and the fifth flow path 43E are on the rod side chamber 29r side. Some are shared.

The injection valve 45 is provided, for example, in the second flow path 43B (a portion of which is not shared with the other flow paths (43A and 43C)), and the flow of the hydraulic fluid from the accumulator 41 to the head side chamber 29h. Allow or prohibit. The injection valve 45 is composed of, for example, a pilot type check valve, and when the pilot pressure is not introduced, the hydraulic fluid is allowed to flow from the accumulator 41 to the head concubine 29h and in the opposite direction. When pilot pressure is introduced, both flows are prohibited. The injection valve 45 also contributes to the prevention of backflow of the hydraulic fluid from the head side chamber 29h.

The pressure boosting valve 47 is provided, for example, in the third flow path 43C (a portion of which is not shared with the other flow paths (43A and 43B)), and the flow of the hydraulic fluid from the accumulator 41 to the rear concubine 29e. Allow or prohibit. The pressure boosting valve 47 is composed of, for example, a flow rate control valve. The pressure boosting valve 47 may be one that performs pressure compensation (flow rate adjusting valve) or one that does not perform pressure compensation. Further, the control method of the pressure boosting valve 47 may be, for example, any of a spring type, an electromagnetic type, a pilot type, and a combination of two or more thereof. The pressure boosting valve 47 may be a servo valve in which feedback control is performed, or a proportional valve in which open control is performed. FIG. 2 shows a flow rate adjusting valve as a pressure boosting valve 47, which is closed at a normal position by a spring and is opened by sequentially operating an electromagnetic force and a pilot pressure.

The speed valve 49 is provided, for example, in the fourth flow path 43D (a portion of which is not shared with the other flow paths (43E)), and for example, the hydraulic fluid discharged from the rod side chamber 29r to the tank 37. Contributes to the control of the flow rate of. By controlling this flow rate, the forward speed of the injection piston 31 is controlled. That is, the speed valve 49 constitutes a so-called meter-out circuit. The speed valve 49 may be one that performs pressure compensation (flow rate adjusting valve) or one that does not perform pressure compensation. Further, the control method of the speed valve 49 may be, for example, any of a spring type, an electromagnetic type, a pilot type, and a combination of two or more of these. The speed valve 49 may be a servo valve in which feedback control is performed, or a proportional valve in which open control is performed. FIG. 2 shows a flow rate adjusting valve as a speed valve 49, which is closed at a normal position by a spring and is opened by sequentially operating an electromagnetic force and a pilot pressure.

The operation valve 51 is composed of, for example, a switching valve having 4 ports and 3 positions. The operation valve 51 cuts off the connection of the four ports at the position (neutral position and / or normal position) shown in the center of the paper.

Further, at the position shown on the left side of the paper surface, the operation valve 51 connects the fifth flow path 43E (rod side chamber 29r) and the pump 39, and connects the sixth flow path 43F (head side chamber 29h) and the tank 37. .. As a result, the hydraulic fluid can be supplied from the pump 39 to the rod side chamber 29r, and the injection piston 31 can be retracted.

The operation valve 51 connects the fifth flow path 43E (rod side chamber 29r) and the tank 37, and connects the sixth flow path 43F (head side chamber 29h) and the pump 39 at the position shown on the right side of the paper surface. .. As a result, the hydraulic fluid can be supplied from the pump 39 to the head side chamber 29h to advance the injection piston 31. However, in the present embodiment, this flow of the hydraulic fluid is not essential for the operation during the molding cycle, and the operation valve 51 may be a two-position valve having a position at the center of the paper surface and a position on the left side of the paper surface.

The control method of the operation valve 51 may be, for example, any of a spring type, an electromagnetic type, a pilot type, and a combination of two or more of these. FIG. 2 shows an operating valve 51 that is set to a closed position (position at the center of the paper surface) at a normal position by a spring and is controlled by sequentially operating an electromagnetic force and a pilot pressure.

Although not particularly shown, the front concubine 29f is connected to the tank 37 via an appropriate flow path. Therefore, the front chamber 29f can discharge the hydraulic fluid to the tank 37 as the pressure boosting piston 33 advances. Further, the front chamber 29f can be replenished with the hydraulic fluid from the tank 37 by a negative pressure as the pressure boosting piston 33 retracts. The hydraulic fluid may be replenished to the front chamber 29f by the pump 39. Further, the front chamber 29f may be opened to the atmosphere instead of being filled with the hydraulic fluid.

In addition, the hydraulic pressure device 28 includes, for example, valves 53 and 55 including check valves provided to prevent backflow to the pump 39, a filter 57 for filtering the hydraulic fluid from the tank 37 to the pump 39, and a speed. It has a cooler 59 and the like that cools the hydraulic fluid flowing to the tank 37 via the valve 49.

(Configuration for jumping suppression)
In the above configuration, for example, the injection valve 45 is opened, and the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h to perform injection. The discharge of the hydraulic fluid from the rod side chamber 29r is permitted only by the speed valve 49, for example, and the speed of the injection piston 31 is controlled by the flow rate control of the speed valve 49.

In such a case, as described above, when the supply of the hydraulic fluid from the accumulator 41 to the head side chamber 29h is started, the operation of the hydraulic fluid being discharged from the rod side chamber 29r due to the compression of the hydraulic fluid in the rod side chamber 29r. The injection piston 31 may be driven (jumping occurs) at a speed exceeding the speed corresponding to the flow rate of the liquid.

Here, the pressure receiving area of the injection piston 31 in the rod side chamber 29r is reduced by the front rod 35. Therefore, in the known configuration, the injection piston 31 has a larger pressure receiving area in the head side chamber 29h than the pressure receiving area in the rod side chamber 29r. As a result, the injection piston 31 may generate a pressure increasing action of increasing the pressure in the head side chamber 29h and applying it to the rod side chamber 29r. This pressure-increasing action is also one of the causes of jumping.

Therefore, in the present embodiment, for example, the pressure receiving area in the head side chamber 29h of the injection piston 31 is reduced to reduce the possibility of jumping. Specifically, it is as follows.

FIG. 3 is an enlarged view showing a part of FIG. 2 (a rear portion of the injection cylinder 27).

The injection cylinder 27 has a rear rod 61 extending rearward (opposite to the front rod 35) from the injection piston 31. Therefore, the pressure receiving area of the injection piston 31 in the head side chamber 29h is reduced by the cross-sectional area of the rear rod 61. Further, the rear rod 61 extends from the head side chamber 29h, and the end surface (the surface opposite to the front rod 35) is isolated from the hydraulic fluid in the head side chamber 29h. That is, the rear rod 61 does not have a pressure receiving area in the meaning defined above in the head side chamber 29h. Therefore, with respect to the entire injection piston 31 and the rear rod 61, the pressure receiving area in the head side chamber 29h is reduced by the cross-sectional area (end face area) of the rear rod 61.

Therefore, for example, when no pressure is applied to the end surface of the rear rod 61, the pressure increasing action of the injection piston 31 is reduced by the amount that the pressure receiving area in the head side chamber 29h of the injection piston 31 is reduced. As a result, the risk of jumping is reduced.

The cross-sectional area (diameter) of the rear rod 61 is, for example, the same as the cross-sectional area (diameter) of the front rod 35. In other words, the injection piston 31 has the same pressure receiving area in the rod side chamber 29r and the pressure receiving area in the head side chamber 29h. From the viewpoint of reliably suppressing jumping, it is preferable that the cross section of the injection piston 31 in the rod side chamber 29r is larger than the cross section of the injection piston 31 in the head side chamber 29h. That is, the cross-sectional area of the rear rod 61 is preferably larger than the cross-sectional area of the front rod 35. However, conversely, the cross-sectional area of the rear rod 61 may be smaller than the cross-sectional area of the front rod 35.

The end face of the rear rod 61 is isolated from the head side chamber 29h by being slidably inserted into the pressure boosting piston 33, for example. That is, the pressure boosting piston 33 has a hole 33h, and also has a sliding portion 33s that slides on the outer peripheral surface of the rear rod 61 on the inner peripheral surface of the hole 33h. The flow of the hydraulic fluid between the 33s and the outer peripheral surface of the rear rod 61 is basically regulated.

Although not particularly shown, an O-ring or the like may be appropriately arranged on the sliding portion 33s. Further, the position and range of the sliding portion 33s in the front-rear direction on the pressure boosting piston 33 may be appropriately set. In the example of FIG. 3, the sliding portion 33s is provided on a part of the front side (for example, the protruding portion 33c) of the pressure boosting piston 33. That is, the hole portion 33h has a larger diameter than the rear rod 61 behind the sliding portion 33s. A gap is formed between the inner peripheral surface of the rear portion of the hole 33h and the outer peripheral surface of the rear rod 61 so that the hydraulic fluid can flow into the hole.

The hole 33h penetrates the pressure boosting piston 33 in the front-rear direction, for example. The gap between the rear rod 61 and the hole 33h in the hole 33h behind the sliding portion 33s leads to the rear chamber 29e. From another point of view, the gap is part of the rear chamber 29e. Therefore, regardless of the presence or absence of the gap, the pressure receiving area in the rear chamber 29e of the boosting piston 33 is obtained by subtracting the cross section of the rear rod 61 (opening area of the sliding portion 33s) from the cross section of the large diameter piston portion 33b. The area is large.

Since the hole 33h communicates with the rear chamber 29e, the end surface of the rear rod 61 is exposed to the rear chamber 29e and receives pressure from the hydraulic fluid in the rear chamber 29e. That is, the rear rod 61 has a pressure receiving area in the rear chamber 29e in the sense defined above.

Therefore, for example, by setting the rear side chamber 29e to a relatively low pressure (for example, tank pressure), it is possible to obtain the effect of suppressing jumping by reducing the pressure increasing action of the injection piston 31 described above. On the other hand, when applying pressure to the rear chamber 29e, the pressure of the rear chamber 29e can be applied not only to the pressure boosting piston 33 but also to the end surface of the rear rod 61. As a result, a part of the decrease in the pressure receiving area in the head side chamber 29h of the injection piston 31 can be compensated.

The rear rod 61 has a length that is not completely pulled out from the pressure boosting piston 33 even if the injection piston 31 reaches the forward limit or its vicinity in a state where the pressure boosting piston 33 is located at the backward limit. Have. As a result, the effect of the rear rod 61 as described above is exerted over the entire stroke of the injection piston 31. The rear rod 61 having such a length has substantially the same length as the front rod 35.

Further, the rear rod 61 is longer than, for example, the pressure boosting piston 33. Therefore, as shown in the drawing, when the injection piston 31 is in a position of contacting the pressure boosting piston 33 (protruding portion 33c), the rear rod 61 extends rearward from the pressure boosting piston 33. However, the booster piston may be formed to be relatively long so that it does not extend as such.

Since the rear rod 61 extends rearward from the pressure boosting piston 33, it protrudes rearward from the stopper 29c that defines the retreat limit of the pressure boosting piston 33. The posterior chamber 29e has, for example, the minimum size necessary to accommodate the posterior rod 61 behind the stopper 29c. For example, the cross-sectional area of the rear side chamber 29e behind the stopper 29c is at least smaller than that of the pressure boosting piston 33, and preferably has the same cross-sectional area as the rear portion of the hole 33h. As a result, the amount of hydraulic fluid required for the rear concubine 29e is reduced.

(Functional parts and sensors of control device)
The control device 13 is composed of, for example, a computer including a CPU, RAM, ROM, and an external storage device, although not particularly shown. When the CPU executes a program stored in the ROM and an external storage device, a plurality of functional units responsible for various controls or calculations are configured. As shown in FIG. 2, the plurality of functional units are, for example, a rod-side pressure control unit 13a, an injection control unit 13b, and a plunger retreat control unit 13c.

The rod-side pressure control unit 13a controls the pressure in the rod-side chamber 29r immediately before the start of injection or the like. Specifically, for example, the rod-side pressure control unit 13a drives a driver (not shown) and an operation valve 51 that drive the pump electric motor 40 based on signals from the input device 17 and / or various sensors and the like. A control signal is output to a driver (not shown).

The injection control unit 13b controls the injection drive unit 25 from the start of injection to the completion of holding pressure. Specifically, for example, the injection control unit 13b applies pilot pressure to an injection valve 45, a driver (not shown) that drives the pump motor 40, based on signals from the input device 17 and / or various sensors. A control signal is output to a hydraulic circuit (not shown) to be introduced, a driver (not shown) that drives the pressure boosting valve 47, a driver (not shown) that drives the speed valve 49, and a driver (not shown) that drives the operation valve 51. ..

The plunger retreat control unit 13c controls the injection drive unit 25 so as to retreat the plunger 23 after the holding pressure is completed. Specifically, for example, the plunger retreat control unit 13c applies a pilot pressure to an injection valve 45, a driver (not shown) that drives the pump electric motor 40, based on signals from the input device 17 and / or various sensors. A control signal is output to a driver (not shown) that drives a hydraulic circuit (not shown) and an operation valve 51.

The sensors that input signals to the control device 13 are, for example, a position sensor 63 (FIG. 2) that detects the position of the plunger 23 and a pressure sensor 65 (FIG. 2) that detects the pressure of the accumulator 41.

The position sensor 63 constitutes, for example, a linear encoder. For example, the position sensor 63 faces a scale portion (not shown) in a direction orthogonal to the axial direction of the scale portion, and generates a pulse according to the relative movement in the axial direction with the scale portion. Then, the position sensor 63 and / or the control device 13 can specify the relative position between the position sensor 63 and the scale unit by integrating the number of generated pulses, and also specify the number of pulses per hour. The speed can be specified by doing so.

The position sensor 63 is fixedly provided to the cylinder portion 29, and the scale portion is provided on the front rod 35 or a member fixed to the front rod 35. Therefore, the position and / or speed of the plunger 23 is indirectly detected by detecting the position and / or speed of the front rod 35.

The position sensor 63 may only output a pulse, or may specify a position and / or speed and output a signal corresponding to the specified position and / or speed. Even in the former case, it can be said that the signal corresponding to the position is output because the total number of pulses differs depending on the position, and the number of pulses per unit time differs depending on the speed, so the signal according to the speed is output. It can be said that it is outputting. The signal in the latter case is, for example, a signal whose signal level changes in response to changes in position and / or velocity.

In addition to the linear encoder as described above, the position sensor 63 is, for example, a laser measurement that is fixedly provided to the cylinder portion 29 and measures the distance to the front rod 35 or a member fixed to the front rod 35. It may be a long instrument.

The pressure sensor 65 outputs, for example, a signal corresponding to the pressure of the liquid chamber 41e. The pressure-responsive signal is, for example, a signal whose signal level changes in response to a change in pressure. As the pressure sensor 65, a known appropriate one such as a diaphragm type may be used. Further, as the pressure sensor 65, a pressure sensor 65 that detects the pressure of the gas chamber 41f may be used in addition to or instead of the one that detects the pressure of the liquid chamber 41e.

(Operation of injection device)
FIG. 4 is a timing chart for explaining the operation of the injection device 9.

The upper part of FIG. 4 shows the time course of the injection speed V (advance speed of the plunger 23) and the injection pressure P (pressure applied to the molten metal by the plunger 23). In the upper part of FIG. 4, the horizontal axis represents the time t, and the vertical axis represents the injection speed V and the injection pressure P. Line L _V and L _P are respectively shows changes in the injection speed V and an injection pressure P with respect to lapse of time t.

The lower part of FIG. 4 shows the operation of the injection valve 45, the pressure boosting valve 47, the speed valve 49, and the operation valve 51 corresponding to the passage of time in the upper part of FIG. In the lower part of FIG. 4, the solid line shows the operation in this embodiment, and the alternate long and short dash line shows a modification described later. “Open” of the pressure boosting valve 47 and the speed valve 49 indicates that these valves are open and the opening degree is appropriately controlled. The "open" of the operation valve 51 is the position where the operation valve 51 is on the left side of the paper in FIG. 2 (the position where the pump 39 and the rod side chamber 29r are connected and the head side chamber 29h and the tank 37 are connected). The "closed" of the operation valve 51 indicates that the operation valve 51 is at the position (closed position) at the center of the paper in FIG. The timing at which the control device 13 outputs the control signal may be earlier than the timing shown in the figure in consideration of the valve control delay and the like.

First, the basic operation of the injection device 9 will be described, and then the operation for preventing jumping will be described.

As a basic operation, the injection device 9 performs, for example, low-speed injection (generally at time points t0 to t1), high-speed injection (generally at time points t1 to t2), and boosting (boost, generally at time points t3 to) in order. The operation of these steps is, for example, as follows.

(Slow injection)
Before the start of injection, the injection device 9 is in a state as shown in FIG. 2, for example. That is, the injection piston 31 and the pressure boosting piston 33 are located, for example, in the retreat limit. The accumulator 41 has been filled to a predetermined pressure, for example. As already described, the pump 39 may be driven all the time or only when necessary, and in the latter case, for example, it is stopped. The injection valve 45 is closed by introducing pilot pressure. The pressure boosting valve 47, the speed valve 49, and the operation valve 51 are in the closed position.

When the injection start condition is satisfied (time point t0), the control device 13 starts advancing the plunger 23, and advances the plunger 23 at a relatively low low-speed injection speed _VL . As a result, the molten metal in the sleeve 21 is pushed out toward the cavity Ca while suppressing the entrainment of air by the molten metal.

The injection start condition is, for example, that the mold clamping device 7 completes the mold clamping of the fixed mold 103 and the moving mold 105, and the supply of the molten metal to the sleeve 21 by the hot water supply device (not shown) is completed. Further, the completion of the operation for suppressing jumping, which will be described later, may be added as an injection start condition.

The low-speed injection speed _VL may be appropriately set, but is, for example, less than 1 m / s. The low-speed injection speed _VL is, for example, a constant value. However, appropriate shift control may be performed. In low-speed injection, the injection pressure is relatively low because the injection speed is relatively low.

For the above operation, the control device 13 specifically supplies the hydraulic fluid from the accumulator 41 to the head concubine 29h by stopping the introduction of the closing pilot pressure into the injection valve 45, for example. .. Further, the control device 13 opens, for example, the speed valve 49 at an appropriate opening degree to allow the hydraulic fluid to be discharged from the rod side chamber 29r to the tank 37. As a result, the injection piston 31 advances, and eventually the plunger 23 advances.

At this time, the speed of the plunger 23 is controlled, for example, by controlling the opening degree of the speed valve 49. This speed control may be open control or feedback control based on the speed detected by the position sensor 63. The speed feedback control may be based on the deviation of the speed itself, or sometimes based on the deviation between the momentarily (every elapsed time) target position obtained from the speed target value and the detected position. The speed feedback control may be substantially performed by performing the position feedback control every moment.

In the present embodiment, since the end face of the rear rod 61 is exposed to the rear chamber 29e, the volume of the rear chamber 29e (including the hole 33h) increases as the injection piston 31 advances, unlike the known configuration. To do. The hydraulic fluid may be appropriately replenished to the rear concubine 29e. For example, the hydraulic fluid may be replenished from the tank 37 through a flow path (not shown) due to the negative pressure generated with the expansion of the volume, or the hydraulic fluid may be replenished from the pump 39 through the flow path (not shown). Alternatively, the hydraulic fluid may be replenished from a comparatively low pressure accumulator (not shown) via a flow path (not shown). When replenishing the hydraulic fluid from the pump 39 or the accumulator, for example, the hydraulic fluid is discharged at a flow rate at which the pressure of the rear side chamber 29e is increased by the pressure increasing ratio of the pressure increasing piston 33 to be equal to or less than the pressure of the head side chamber 29h. Be replenished.

(High-speed injection)
When the plunger 23 reaches a predetermined high speed switching position (time point t1), the control unit 13 advances the plunger 23 at a relatively high speed of high-speed injection speed V _H. As a result, for example, the molten metal is quickly filled in the cavity Ca without delaying the solidification of the molten metal. The high-speed injection speed _VH may be appropriately set, but is, for example, 1 m / s or more. The high-speed injection speed V _H is, for example, a constant value. However, appropriate shift control may be performed. In high-speed injection, the injection pressure is higher than the pressure in low-speed injection because the injection speed is relatively high.

For the above operation, specifically, for example, the control device 13 continues to supply the hydraulic fluid from the accumulator 41 to the head side chamber 29h from the low speed injection, while opening the speed valve 49. To increase. When only increasing the opening degree of the speed valve 49 in this way, the control device 13 performs, for example, open control or feedback control continuously from the low speed injection, and simply sets the target value of the speed from the low speed injection to the high speed injection. All you have to do is change it to something.

For example, the control device 13 converts the target speed set for each section in which the movement range of the plunger 23 is divided into a plurality of sections into a target value of the position of the plunger 23 for each elapsed time, and performs position feedback control (substantial speed feedback). Control) is performed, and it is not detected whether or not the plunger 23 has reached the high-speed switching position. However, the control device 13 may switch the target value of the speed by detecting that the plunger 23 has reached a predetermined high-speed switching position based on the signal from the position sensor 63.

It should be noted that the hydraulic fluid may be appropriately replenished to the rear concubine 29e as in the case of low-speed injection.

(Deceleration, boosting and holding pressure)
As a result of the high-speed injection, when the cavity Ca is substantially filled with the molten metal (time point t2), the pressure of the molten metal increases, which causes the plunger 23 to decelerate. The deceleration control may be performed by reducing the opening degree of the speed valve 49 at an appropriate time. As a result of the deceleration, the plunger 23 is almost stopped (time point t4). As shown in the illustrated example, the molten metal may be boosted even after the plunger 23 is substantially stopped. After that, the pressure of the molten metal reaches the casting pressure (final pressure). In this way, deceleration and pressure increase are performed. After that, the casting pressure is maintained (pressure holding step).

For the above operation, specifically, the control device 13 opens the pressure boosting valve 47 at an appropriate time (t3), for example. As a result, the hydraulic fluid is supplied from the accumulator 41 to the rear concubine 29e, the increased pressure is applied to the head concubine 29h, and the pressure is increased. The injection valve 45 self-closes when the pressure in the head side chamber 29h becomes higher than the pressure in the accumulator 41. However, the injection valve 45 may be closed by introducing a pilot pressure that closes at an appropriate time. Further, the control device 13 sets the opening degree of the speed valve 49 to an appropriate opening degree for boosting so that an appropriate boosting curve can be obtained.

In the present embodiment, since the rear rod 61 is exposed to the rear chamber 29e, unlike the known configuration, the injection piston 31 not only has the pressure in the head side chamber 29h, but also the rear rod 61 via the rear rod 61. It also receives the pressure of the concubine 29e. Therefore, as already described, a part of the decrease in the pressure receiving area in the head side chamber 29h of the injection piston 31 is compensated.

After that, the force received by the injection piston 31 from the hydraulic fluid such as the head side chamber 29h and the force received by the plunger 23 from the molten metal are balanced, so that the injection pressure becomes constant (the casting pressure becomes). At this time, the pressure of the rod side chamber 29r is, for example, a tank pressure (generally 0). It should be noted that the discharge of the hydraulic fluid from the rod side chamber 29r is prohibited by closing the speed valve 49 at an appropriate time, and the pressure of the rod side chamber 29r is set to an appropriate pressure higher than the tank pressure, whereby arbitrary casting is performed. You may get pressure. In the pressure holding step, the control device 13 maintains the state when the casting pressure is obtained. For example, the boost valve 47 and the speed valve 49 remain open.

(Extrusion tracking, plunger retreat and accumulator filling)
When the molten metal filled in the cavity Ca solidifies, the control device 13 advances the plunger 23 following the mold opening by the mold clamping device 7, although not particularly shown. As a result, the biscuit is pushed and the molded product is separated from the fixed mold 103. Specifically, for example, the control device 13 controls the hydraulic device 28 so as to supply the hydraulic fluid from the accumulator 41 or the pump 39 to the head side chamber 29h or the rear side chamber 29e.

After the extrusion follow-up (time point t5), the control device 13 controls the injection drive unit 25 so as to retract the plunger 23. Specifically, the control device 13 controls the operation valve 51 so as to be at the position on the left side of the paper surface. That is, the control device 13 connects the pump 39 and the rod side chamber 29r, and connects the head side chamber 29h and the tank 37. Further, the control device 13 closes the injection valve 45, the pressure boosting valve 47, and the speed valve 49. Further, the control device 13 drives the electric motor 40 for the pump. Therefore, the hydraulic fluid is supplied from the pump 39 to the rod side chamber 29r, the injection piston 31 retracts, and the plunger 23 retracts.

In the present embodiment, since the rear rod 61 is exposed to the rear chamber 29e, the volume of the rear chamber 29e is reduced as the injection piston 31 retracts. At this time, the hydraulic fluid in the rear concubine 29e is discharged to the tank 37 through, for example, a flow path (not shown). The hydraulic fluid discharged from the rear side chamber 29e may be filled in the accumulator 41 via the pressure boosting valve 47.

Further, when the injection piston 31 retracts to a certain position, the pressure boosting piston 33 is pushed by the injection piston 31 and retracts together with the injection piston 31. The discharge of the hydraulic fluid in the rear concubine 29e is, for example, the same as described above. The pressure boosting piston 33 is not pushed by the injection piston 31, but is retracted by prohibiting the discharge of the hydraulic fluid from the head side chamber 29h and retracting the injection piston 31, or the head side chamber 29h or the front side chamber 29f. It may be retracted by supplying a working fluid to the.

After the retreat of the plunger 23 is completed, the control device 13 drives the pump 39 with the injection valve 45, the pressure boosting valve 47, the operation valve 51, and the like closed. As a result, the hydraulic fluid is supplied from the pump 39 to the accumulator 41, and the accumulator 41 is filled. Then, when the pressure detected by the pressure sensor 65 reaches a predetermined set pressure, the control device 13 stops driving the pump 39, for example.

(Operation for jumping suppression)
The control device 13 positions the operation valve 51 on the left side of the paper in FIG. 2 at an appropriate time before the start of low-speed injection (before the time point t0). That is, the control device 13 connects the pump 39 and the rod side chamber 29r, and connects the head side chamber 29h and the tank 37. Further, the control device 13 closes the injection valve 45, the pressure boosting valve 47, and the speed valve 49. Further, the control device 13 drives the electric motor 40 for the pump. Therefore, pressure is applied from the pump 39 to the rod side chamber 29r. As a result, the hydraulic fluid in the rod side chamber 29r is compressed. The control of this operation is basically the same as the control when the plunger 23 is retracted.

After that, the control device 13 sets the operation valve 51 at the position (closed position) at the center of the paper in FIG. Even if the application of pressure from the pump 39 to the rod side chamber 29r is stopped, the compression of the hydraulic fluid in the rod side chamber 29r is basically maintained as long as the discharge of the hydraulic fluid from the rod side chamber 29r is prohibited. Then, when the injection valve 45 and the speed valve 49 are opened (time point t0), the pressure in the head side chamber 29h rises and the pressure in the rod side chamber 29r decreases, so that the injection piston 31 starts advancing.

At this time, since the hydraulic fluid in the rod side chamber 29r is compressed in advance, even if the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h, the compression of the hydraulic fluid in the rod side chamber 29r does not occur or is suppressed, and jumping is performed. Is reduced.

The time for applying pressure to the rod side chamber 29r (the time for supplying the hydraulic fluid from the pump 39 to the rod side chamber 29r) is such that the compression of the hydraulic fluid in the rod side chamber 29r is completed or the compression proceeds to some extent. It may be set as appropriate.

The start timing for applying pressure to the rod side chamber 29r may be an appropriate time point before the start of low-speed injection. For example, it may be a time point at which the above preload time is secured before the hydraulic fluid is supplied to the head side chamber 29h. Further, the start timing may be before or after the completion of mold clamping, before or after the supply of the molten metal to the sleeve 21.

If the mass and sliding resistance of the plunger 23, the front rod 35, the injection piston 31 and the rear rod 61 are relatively large, or if the injection valve 45 is configured and controlled to be gradually opened, the rod Even if the pressure applied to the rod side chamber 29r by supplying the hydraulic fluid to the side chamber 29r is simultaneous with or slightly delayed from the application of the pressure to the head side chamber 29h, the effect of suppressing jumping can be obtained to some extent. Be done. Therefore, the start timing of applying pressure by trying to supply the hydraulic fluid to the rod side chamber 29r is basically before the timing of opening the injection valve 45, but at the same time or slightly after. It may be a point in time. Further, the timing at which the control device 13 outputs the control signal to the operation valve 51 and the injection valve 45 may be set in consideration of the difference in control delay between the two valves, and both valves are not necessarily opened in the order in which both valves are opened. The control signal to is not required to be output.

The end timing of applying pressure to the rod side chamber 29r may be before the start of injection, at the same time as the start of injection, or after the start of injection. However, if the end timing is too early with respect to the start of injection, for example, the pressure in the rod side chamber 29r may decrease due to leakage of the hydraulic fluid or the like, and the effect of suppressing jumping may decrease. If the end timing is late with respect to the start of injection, there will be a delay between the opening of the speed valve 49 and the start of the pressure in the rod side chamber 29r, depending on the magnitude of the pressure applied to the rod side chamber 29r. , The start of advance of the plunger 23 is delayed. Further, in the present embodiment, the operation valve 51 connects the pump 39 and the rod side chamber 29r, while connecting the head side chamber 29h and the tank 37, so that the hydraulic fluid from the accumulator 41 is wasted in the tank 37. The pressure in the head side chamber 29h does not rise. Therefore, it is preferable that the end timing is substantially the same as the injection start. Further, the end timing may be set when the detection value of a sensor (not shown) for detecting the pressure of the rod side chamber 29r reaches a predetermined pressure.

The rod side chamber 29r may be boosted to an appropriate pressure. For example, the rod side chamber 29r may be boosted to the same level as the pressure immediately before the start of injection of the accumulator 41 (accumulation completion pressure). Further, for example, the rod side chamber 29r is boosted to a pressure equal to or more than half the pressure of the hydraulic fluid (discharge pressure of the hydraulic pressure source) sent to the head side chamber 29h during injection (for example, low speed injection or high speed injection). Good. However, if the pressure of the rod side chamber 29r is slightly larger than the tank pressure (generally atmospheric pressure), the effect of reducing the possibility of jumping will be exhibited to some extent.

(First modification)
Although not particularly shown, the hydraulic pressure device 28 may be modified so that the hydraulic fluid can be discharged from the rod side chamber 29r to the tank 37 via the speed valve 49 while supplying the hydraulic fluid from the pump 39 to the head side chamber 29h. .. For example, the operation valve 51 is configured to connect the pump 39 and the sixth flow path 43F at the position on the right side of the paper surface in FIG. 2 and to shut off the fifth flow path 43E and the tank 37.

Then, in low-speed injection, the hydraulic fluid is supplied from the pump 39 to the head side chamber 29h to advance the injection piston 31, and the speed of the plunger 23 in the rod side chamber 29r is controlled by the speed valve 49. Further, as shown by a two-dot chain line in the diagram relating to the injection valve 45 in FIG. 3, the injection valve 45 is opened at the start of high-speed injection.

Even when the hydraulic fluid is supplied from the pump 39 to the head side chamber 29h in this way, jumping is suppressed by compressing the hydraulic fluid in the rod side chamber 29r in advance.

(Second modification)
Although not particularly shown, in the retreat of the plunger 23, even after the injection piston 31 reaches the retreat limit, the control for supplying the hydraulic fluid from the pump 39 to the rod side chamber 29r is continued, thereby reducing the pressure in the rod side chamber 29r. It may be raised and then the operating valve 51 may be closed. Then, the operation of setting the operation valve 51 at the position on the left side of the paper in FIG. 2 may be omitted immediately before the start of injection.

Even in this case, if the pressure drop in the rod side chamber 29r after closing the operation valve 51 is not large, the possibility of jumping is reduced. That is, the injection drive unit 25 only needs to have a predetermined pressure in which the pressure in the rod side chamber 29r is larger than the tank pressure immediately before the start of injection, and the operation itself for increasing the pressure in the rod side chamber 29r is injection. It does not have to be just before the start.

As described above, in the present embodiment, the injection device 9 has an injection cylinder 27, a hydraulic pressure device 28 capable of supplying a hydraulic fluid to the injection cylinder 27, and a control device 13 for controlling the hydraulic pressure device 28. .. The injection cylinder 27 makes the front rod 35 connected to the plunger 23 slidable in the sleeve 21 leading to the mold 101, the injection piston 31 fixed to the front rod 35, and the injection piston 31 slidable. It has a cylinder portion 29 that accommodates it. The inside of the cylinder portion 29 is divided into a rod side chamber 29r on the side where the front rod 35 extends by the injection piston 31 and a head side chamber 29h on the opposite side. The injection cylinder 27 further has a rear rod 61 extending from the injection piston 31 to the side opposite to the front rod 35 and having an end face isolated from the head concubine 29h. The control device 13 has a rod-side pressure control unit 13a that controls the hydraulic pressure device 28 so that the pressure in the rod-side chamber 29r immediately before the start of injection is higher than the tank pressure.

Therefore, for example, as described above, the possibility of jumping is reduced by compressing the hydraulic fluid in the rod side chamber 29r in advance. Further, when the hydraulic fluid is supplied to the head concubine 29h by reducing (including eliminating) the pressure increasing action of the injection piston 31 by the rear rod 61 or causing the pressure increasing action in the opposite direction. The possibility that a relatively large pressure is applied to the rod side chamber 29r can be reduced, and the possibility that jumping will occur more reliably can be reduced. In another aspect, the need to apply a relatively high pressure to the rod concubine 29r to suppress jumping is reduced, which in turn makes the pump 39 high pressure or pumps to apply pressure to the rod concubine 29r. The need to provide a high-pressure hydraulic pressure source separately from 39 is reduced.

When the pressure of the rod side chamber 29r immediately before the start of injection is higher than the tank pressure, the pressure immediately before the start of injection may be just before the injection piston 31 actually starts advancing. As described above, depending on the mass and sliding resistance of the injection piston 31 and the like, the control delay of the hydraulic system, etc., a control signal is output from the control device 13 so as to supply the hydraulic fluid to the head side chamber 29h immediately. The injection piston 31 does not move forward. Therefore, for example, a control signal for supplying the hydraulic fluid to the head side chamber 29h may be output slightly before or at the same time when the pressure of the rod side chamber 29r becomes higher than the tank pressure.

Further, in the present embodiment, the cross-sectional area of the rear rod 61 is equal to or larger than the cross-sectional area of the front rod 35. Therefore, for example, the pressure-increasing action of the injection piston 31 can be eliminated, or the pressure-increasing action can be generated in the opposite direction, and the possibility of jumping occurring more reliably can be reduced.

Further, in the present embodiment, the hydraulic pressure device 28 has a pump 39 (hydraulic pressure source) and a fifth flow path 43E connecting the pump 39 and the rod side chamber 29r. The control device 13 has a plunger retreat control unit 13c that controls the hydraulic device 28 so as to supply the hydraulic fluid from the pump 39 to the rod side chamber 29r via the fifth flow path 43E and retreat the plunger 23. .. The rod-side pressure control unit 13a controls the hydraulic pressure device 28 so as to apply pressure from the pump 39 to the rod-side chamber 29r via the fifth flow path 43E, similarly to the plunger retreat control unit 13c.

Therefore, for example, the configuration for retracting the plunger 23 can be used as it is for boosting the rod side chamber 29r before the start of injection. That is, the configuration is simplified. Further, as described in the second modification, the rod side chamber 29r may be boosted following the retreat of the plunger 23, and the operation can be simplified.

Further, in the present embodiment, the injection cylinder 27 is slidably housed in the cylinder portion 29 on the side opposite to the front rod 35 with respect to the injection piston 31, and the inside of the cylinder portion 29 is the head side chamber 29h. It is divided into a rear chamber 29e on the opposite side, and has a pressure boosting piston 33 in which the pressure receiving area in the rear chamber 29e is larger than the pressure receiving area in the head side chamber 29h. The rear rod 61 is slidably inserted into the pressure boosting piston 33, and its end face is exposed in the rear chamber 29e.

Therefore, for example, the provision of the rear rod 61 reduces the possibility of jumping at the start of injection, while the provision of the rear rod 61 reduces the pressure receiving area of the injection piston 31. Can be compensated. That is, a suitable operation is possible as a whole from injection to pressure increase, and by extension, the quality of the molded product is improved.

In the first embodiment, the die casting machine 1 is an example of a molding machine, the pump 39 is an example of a hydraulic pressure source, and the fifth flow path 43E is an example of a flow path connected to the hydraulic pressure source.

<Second Embodiment>
FIG. 5 is a diagram corresponding to FIG. 2, which schematically shows the configuration of the injection device 209 according to the second embodiment.

In the injection drive unit 25 of the first embodiment, pressure was applied from the pump 39 to the rod side chamber 29r before the start of injection. On the other hand, in the injection drive unit 225 of the present embodiment, pressure is applied from the accumulator 41 to the rod side chamber 29r before the start of injection. Other configurations of this embodiment are the same as those of the first embodiment.

Specifically, the hydraulic device 228 of the injection drive unit 225 has a seventh flow path 243G and a seventh flow path 243G connecting the accumulator 41 and the rod side chamber 29r, in addition to the configuration of the hydraulic device 28 of the first embodiment. It has a compression valve 267 provided in the flow path 243G.

A part of the 7th flow path 243G on the accumulator 41 side is shared with a part of other flow paths (43A, 43B and 43C) connected to the accumulator 41, and the rod of the 7th flow path 243G is used. A part of the side chamber 29r side is shared with a part of other flow paths (43D and 43E) connected to the rod side chamber 29r, for example.

The compression valve 267 may be appropriately configured as long as the flow of the hydraulic fluid from the accumulator 41 to the rod side chamber 29r can be allowed and prohibited. In the illustrated example, the compression valve 267 is composed of a pilot type check valve, which prohibits the flow of hydraulic fluid from the accumulator 41 to the rod side chamber 29r when no pilot pressure is introduced. Allow reverse flow and, when pilot pressure is introduced, allow both flows.

The operation of the injection drive unit 225 (control of the control device 13) is that when pressure is applied to the rod side chamber 29r by sending the hydraulic fluid to the rod side chamber 29r, the accumulator 41 replaces the supply of the hydraulic fluid from the pump 39. The operation is the same as that of the injection drive unit 25 of the first embodiment, except that the hydraulic fluid is supplied from the above. That is, immediately before the time point t0 in FIG. 4, the pilot pressure is introduced into the compression valve 267 instead of the operation valve 51 being positioned on the left side of the paper in FIG.

Also in the present embodiment, the injection cylinder 27 is a double-rod type, and the pressure of the rod side chamber 29r immediately before the start of injection is made larger than the tank pressure, so that the same effect as that of the first embodiment is obtained. .. For example, the risk of jumping is reduced.

<Third Embodiment>
(Composition of injection drive unit)
FIG. 6 is a schematic view showing the configuration of the injection device 309 according to the third embodiment of the present invention.

The injection drive unit 25 of the first embodiment was a hydraulic type. On the other hand, the injection drive unit 325 of the present embodiment is a so-called hybrid type in which a hydraulic type and an electric type are combined. Further, in response to this difference, the control of the injection drive unit 325 of the present embodiment is also different from that of the first embodiment. The other configurations of this embodiment are the same as those of the first embodiment.

Specifically, the injection drive unit 325 has an electric drive unit 381 in addition to the injection cylinder 27 similar to that of the first embodiment.

Although omitted in the description of the first embodiment, the rear end of the plunger 23 and the tip of the front rod 35 are connected by, for example, a coupling 24. The coupling 24 has, for example, a case member (reference numeral omitted) for accommodating the rear end of the plunger 23 and the tip of the front rod 35, and the case member is provided between the plunger 23 and the front rod 35 with respect to these. It constitutes a part to expand the diameter.

The electric drive unit 381 includes, for example, a rotary drive electric motor 383, a transmission mechanism 385 that transmits the rotation of the drive electric motor 383, and a conversion mechanism 387 that converts the rotation transmitted from the transmission mechanism 385 into translational motion. It has a driven portion 391 driven in the moving direction of the plunger 23 by a driving force from the conversion mechanism 387. Then, the plunger 23 is driven by transmitting the driving force from the driven unit 391 to the plunger 23.

The drive motor 383 has, for example, a stator that constitutes one of the armature or the field, and a rotor that constitutes the other of the armature or the field, as is not particularly shown. The arrangement position and orientation of the drive electric motor 383 may be appropriately set. In the illustrated example, the drive electric motor 383 is arranged so that the output shaft 383a is parallel to the front rod 35.

The drive motor 383 may be a DC motor, an AC motor, an induction motor, or a synchronous motor. The drive electric motor 383 may be an electric motor with a brake. The drive motor 383 is configured as, for example, a servomotor, and constitutes a servo mechanism together with an encoder 383b that detects the rotation of the drive motor 383 and a servo driver (not shown) that supplies power to the drive motor 383. There is.

The transmission mechanism 385 is composed of, for example, a pulley / belt mechanism, and has a first pulley 385a fixed to the output shaft 383a of the drive electric motor 383, a second pulley 385b fixed to the conversion mechanism 387, and a first pulley. It has a pulley 385a and a belt 385c bridged over a second pulley 385b. Therefore, when the drive electric motor 383 is rotated, the rotation is transmitted to the conversion mechanism 387 via the transmission mechanism 385.

The conversion mechanism 387 is composed of, for example, a ball screw mechanism, and has a screw shaft 387a and a nut 387b screwed to the screw shaft 387a via a ball (not shown).

The screw shaft 387a is arranged parallel to the front rod 35. Further, the screw shaft 387a is restricted from moving in the axial direction and is allowed to rotate around the shaft. On the other hand, the nut 387b is allowed to move in the axial direction and its rotation around the axis is restricted. Therefore, when the screw shaft 387a is rotated, the nut 387b moves in a direction parallel to the front rod 35.

The above-mentioned second pulley 385b is fixed concentrically or coaxially with the screw shaft 387a. Therefore, the rotation transmitted from the drive motor 383 via the transmission mechanism 385 is transmitted to the screw shaft 387a. As a result, the nut 387b moves in the direction parallel to the front rod 35 by the driving force of the driving electric motor 383.

The driven portion 391 is regulated to move forward relative to the front rod 35 by engaging and / or detaching, and is allowed to move backward relative to the front rod 35. Since the front rod 35 and the plunger 23 are connected to each other, the regulation of relative advance and the allowance of retreat with respect to the front rod 35 here are synonymous with the regulation of relative advance and the allowance of retreat with respect to the plunger 23. Is.

Specifically, for example, the driven portion 391 has a base portion 391a, a hook 391b oscillatingly supported by the base portion 391a, and an actuator (not shown) for driving the hook 391b.

The base 391a is fixed to, for example, a nut 387b. Further, the base portion 391a can be brought into contact with the coupling 24 (contacted portion) from behind, for example. Therefore, the contact of the base portion 391a with respect to the coupling 24 restricts the relative advancement of the base portion 391a with respect to the front rod 35, and allows the base portion 391a to retreat with respect to the front rod 35 rearward from the contact position.

Therefore, the plunger 23 can be advanced by advancing the base portion 391a in a state where the base portion 391a is in contact with the coupling 24. That is, the plunger 23 can be advanced by the driving force of the driving electric motor 383. Further, the plunger 23 can be advanced relative to the base portion 391a by supplying the hydraulic fluid to the head side chamber 29h and moving the front rod 35 at a relatively high speed.

The hook 391b is formed, for example, in a substantially L shape, and one end thereof is rotatably supported by the base portion 391a. The hook 391b is at a position (shown) where the plunger 23 can be engaged with the coupling 24 (contacted portion, engaged portion) in the retracting direction and a position at which the engagement is released (the position shown in the drawing). It is possible to move between the position shown in the figure and the position moved downward on the paper. The hook 391b can hold the coupling 24 with the base portion 391a at the engaging position.

By engaging the hook 391b, the relative advance of the plunger 23 with respect to the driven portion 391 is restricted. Therefore, for example, deceleration control can be performed while the plunger 23 is being advanced by the electric drive unit 381, or the plunger 23 can be retracted after injection by the electric drive unit 381.

The actuator (not shown) for driving the hook 391b may be realized by an appropriate actuator such as an air cylinder or a linear motor. The hook 391b and the actuator may not be provided. Further, in addition to or instead of engaging the base portion 391a, the driven portion 391 may be attached / detached to / from the front rod 35 with an electromagnet, or may be attached / detached / detached by holding (and thus frictional resistance) the front rod 35 in the radial direction. You may.

Although not particularly shown, the injection drive unit 325 may have a pair of electric drive units 381 symmetrically or vertically symmetrically. Further, the pair of electric drive units 381 may share one drive electric motor 383. The transmission mechanism 385 may be omitted and the rotation of the drive motor 383 may be directly transmitted to the screw shaft 387a. Further, contrary to the illustrated example, the nut 387b is made non-movable in the axial direction and rotatable around the shaft, and the screw shaft 387a is movable in the axial direction and is not rotatable around the shaft. The 391 may be fixed to the screw shaft 387a, and the rotation of the driving electric motor 383 may be transmitted to the nut 387b.

(Construction of hydraulic system)
FIG. 7 is a diagram corresponding to FIG. 2, which schematically shows the configuration of the hydraulic system of the injection drive unit 325.

The hydraulic device 328 of the injection drive unit 325 differs from the hydraulic device 28 of the injection drive unit 25 of the first embodiment only in that, for example, a so-called run-around circuit 369 is provided.

The run-around circuit 369 has an eighth flow path 343H that connects the rod side chamber 29r and the head side chamber 29h, and a run-around valve 371 that opens and closes the eighth flow path 343H.

A part of the eighth flow path 343H on the rod side chamber 29r side is shared with a part of other flow paths (43D and 43E) connected to the rod side chamber 29r, and a part of the head side chamber 29h side is shared. , Is shared with a part of another flow path (43F) connected to the head side chamber 29h.

The run-around valve 371 may have an appropriate configuration as long as the eighth flow path 343H can be opened and closed. In the illustrated example, the run-around valve 371 is composed of a pilot-type check valve, which allows the flow of hydraulic fluid from the rod side chamber 29r to the head side chamber 29h when no pilot pressure is introduced. , The reverse flow is prohibited, both flows are allowed when an open pilot pressure is introduced, and both flows are prohibited when a closing pilot pressure is introduced.

The control device 13 (injection control unit 13b and plunger retreat control unit 13c) uses the same reference numerals as those in the first embodiment for convenience, but in addition to the hydraulic pressure device 228, the electric drive unit 381 is controlled. I do.

(Operation of injection device)
FIG. 8 is a timing chart for explaining the operation of the injection device 309, and is a diagram corresponding to FIG. 4 of the first embodiment.

The horizontal axis and the vertical axis of FIG. 8 are the same as those of FIG. However, in FIG. 8, in addition to the control target shown in FIG. 4, a drive electric motor 383 and a run-around valve 371 are added.

First, the basic operation of the injection device 309 will be described, and then the operation for preventing jumping will be described. The injection device 309 has, as basic operations, for example, low-speed injection (generally at time point t0 to t1), high-speed injection (generally at time point t1 to t2), and boosting (boost, generally at time point t3) as in the first embodiment. ~) Are performed in order.

(Slow injection)
Before the start of injection, the state of the hydraulic system of the injection device 309 is the same as the state before the start of injection of the first embodiment. That is, the various pistons (31, 33) are located in the retreat limit, the various valves (45, 47, 49, 51 and 371) are basically closed, and the accumulator 41 is completely filled. Further, the base portion 391a of the electric drive unit 381 is engaged with the front rod 35 located at the retracting limit from the rear, and the hook 391b is in the engaging position.

Then, as in the first embodiment, the control device 13 starts low-speed injection when the injection start condition is satisfied (time point t0). However, unlike the first embodiment, the low-speed injection is performed by the driving force of the electric drive unit 381.

Specifically, the control device 13 outputs a control signal to the driver of the drive electric motor 383 to drive the drive electric motor 383. The driving force of the driving electric motor 383 is transmitted to the coupling 24 via the transmission mechanism 385, the conversion mechanism 387, and the driven portion 391. As a result, the plunger 23 and the front rod 35 move forward.

At this time, a pilot pressure is introduced into the run-around valve 371 to open the valve. Then, the hydraulic fluid in the rod side chamber 29r whose volume decreases as the injection piston 31 advances is returned to the head side chamber 29h whose volume increases as the injection piston 31 advances. When the cross section of the front rod 35 and the cross section of the rear rod 61 are the same, there is basically no excess or deficiency of the hydraulic fluid. When the cross section of the front rod 35 is smaller than the cross section of the rear rod 61, the hydraulic fluid becomes excess. The surplus may be discharged to the tank 37, for example, through a relief valve (not shown) provided in the eighth flow path 343H. When the cross section of the front rod 35 is larger than the cross section of the rear rod 61, the hydraulic fluid is insufficient. The deficiency may be replenished from the tank 37 by negative pressure, for example, from the pump 39 or a low pressure accumulator (not shown).

The injection valve 45 and the speed valve 49 are maintained in a closed state in low-speed injection, unlike the first embodiment. The replenishment of the hydraulic fluid to the rear concubine 29e is the same as in the first embodiment.

The speed of the plunger 23 is controlled by adjusting the rotation speed of the drive electric motor 383. Specifically, the control device 13 (injection control unit 13b) feedback-controls the rotation speed of the drive electric motor 383 based on the signal from the position sensor 63. It should be noted that the speed feedback control may be the speed itself as a deviation, or may be the position feedback control every moment, as in the first embodiment.

In low speed injection, the hook 391b may or may not be engaged with the coupling 24. In the case of engagement, for example, when multi-stage control including deceleration is performed, the possibility that the plunger 23 moves away from the base portion 391a due to inertial force can be reduced.

(High-speed injection)
The high-speed injection is performed in the same manner as in the first embodiment. That is, the injection valve 45 is opened to supply the hydraulic fluid from the accumulator 41 to the head side chamber 29h, and the speed valve 49 is opened to allow the hydraulic fluid to be discharged from the rod side chamber 29r to the tank 37. The speed of the plunger 23 is controlled by the flow rate in the speed valve 49, and is feedback-controlled based on the signal from the position sensor 63. The run-around valve 371 is closed.

In high-speed injection, the hook 391b is set to the position where the engagement is released. Therefore, the plunger 23 driven by the injection cylinder 27 moves forward leaving the driven portion 391 behind. As a result, the electric drive unit 381 does not become a load that hinders the advance of the plunger 23.

In high-speed injection, for example, the electric drive unit 381 continues to rotate in the direction of advancing the driven unit 391 following the low-speed injection. This is to contribute to the retreat of the plunger, which will be described later. The speed at this time may be the same as that at the time of low-speed injection, or may be lower than this.

(Deceleration, pressure increase, pressure retention, extrusion follow-up and plunger retreat)
Deceleration, pressure increase, pressure retention and extrusion follow-up may be performed in the same manner as in the first embodiment. The driven portion 391 that has moved forward following the low-speed injection catches up with the plunger 23 that has decelerated and stopped, and can engage with the plunger 23 again. Therefore, the electric drive unit 381 may contribute to any of boosting, holding pressure, and extrusion tracking.

Further, the plunger retracts is performed by, for example, the driving force of the electric drive unit 381. Specifically, the hook 391b is engaged with the coupling 24 to rotate the drive electric motor 383 in the direction in which the driven portion 391 is retracted.

At this time, for example, the run-around valve 371 is opened, and the hydraulic fluid in the head side chamber 29h whose volume is reduced is returned to the rod side chamber 29r. As in the case of low-speed injection, when the cross section of the front rod 35 and the cross section of the rear rod 61 are the same, the excess or deficiency of the hydraulic fluid basically does not occur. When excess or deficiency occurs, the surplus may be discharged or the deficiency may be replenished as appropriate, as in the case of low-speed injection. The discharge of the hydraulic fluid from the rear concubine 29e is the same as in the first embodiment.

The retracting of the plunger 23 may be performed by supplying the hydraulic fluid from the pump 39 to the rod side chamber 29r via the operation valve 51, as in the first embodiment. In this case, the run-around valve 371 is closed. Further, the electric drive unit 381 may stop or retract at the time of low-speed injection to prepare for the next cycle.

(Operation for jumping suppression)
As described above, in high-speed injection, the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h, and the injection speed is controlled by controlling the flow rate of the hydraulic fluid discharged from the rod side chamber 29r. Therefore, jumping may occur at the start of high-speed injection.

Therefore, for example, when the cross section of the front rod 35 is equal to or less than the cross section of the rear rod 61, the injection device 309 performs the following operations.

First, the injection device 309 applies pressure from the pump 39 to the rod side chamber 29r via the operation valve 51 before the start of injection, and compresses the hydraulic fluid in the rod side chamber 29r, as in the first embodiment. At this time, as shown by the alternate long and short dash line in FIG. 8, it is preferable to open the run-around valve 371 to compress the hydraulic fluids in both the rod side chamber 29r and the head side chamber 29h.

When the cross section of the front rod 35 is equivalent to the cross section of the rear rod 61, the compressed state before the start of injection of the hydraulic fluid is basically while the low speed injection is performed by the driving force of the electric drive unit 381. Be maintained. Further, when the cross-sectional area of the front rod 35 is smaller than the cross-sectional area of the rear rod 61 and low-speed injection is performed by the driving force of the electric drive unit 381, for example, not shown in the eighth flow path 343H. The pressure of the working fluid rises to the set pressure of the relief valve, and the compressed state is maintained at that pressure.

Then, at the start of high-speed injection, even if the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h, the hydraulic fluid in the rod side chamber 29r is compressed, so that the possibility of jumping is reduced.

Further, for example, regardless of the relative size of the cross-sectional area of the front rod 35 and the cross-sectional area of the rear rod 61, the hydraulic pressure of the pump 39 or the like is kept open during low-speed injection with the run-around valve 371 open. Pressure may be continuously applied from the source to the rod side chamber 29r and the head side chamber 29h.

In this case, for example, when the cross section of the front rod 35 and the cross section of the rear rod 61 are substantially the same, the force received from the hydraulic fluid in the rod side chamber 29r and the force received from the head side chamber 29h in the injection piston 31. After all, the plunger 23 can be driven by the driving force of the electric drive unit 381. Since the compressed state of the hydraulic fluid in the rod side chamber 29r is maintained during the low-speed injection, jumping at the start of the high-speed injection is suppressed.

Further, even when the cross section of the front rod 35 and the cross section of the rear rod 61 are different, when the difference is relatively small, the compressed state of the hydraulic fluid in the rod side chamber 29r is maintained as described above. While doing so, the plunger can be driven mainly by the driving force of the electric drive unit 381. Even if the difference in cross section is relatively large, the plunger 23 is mainly controlled by the speed of the electric drive unit 381 while maintaining the compressed state of the hydraulic fluid in the rod side chamber 29r by suppressing the pressure applied to the rod side chamber 29r. Speed control is possible.

As described above, also in the present embodiment, the injection cylinder 27 is a double-rod type, and the pressure of the rod side chamber 29r immediately before the start of injection or during low-speed injection is made larger than the tank pressure, so that a preferable effect can be obtained. Played. For example, the risk of jumping at the start of high-speed injection is reduced.

The pressure applied to the rod side chamber 29r may be applied by the accumulator 41 instead of the pump 39, as in the second embodiment. In the present embodiment, the relief valve is appropriately referred to, but the description of the configuration and the set pressure of the relief valve 473 in the fourth embodiment described later may be applied to the relief valve of the present embodiment as it is.

<Fourth Embodiment>
(Composition of injection drive unit)
FIG. 9 is a diagram corresponding to FIG. 2, which schematically shows the configuration of the hydraulic system of the injection device 409 according to the fourth embodiment.

The injection drive unit 425 of the injection device 409 is a hybrid type as in the third embodiment. Therefore, the injection drive unit 425 has an injection cylinder 27 and an electric drive unit 381 described with reference to FIG. However, the illustration of the electric drive unit 381 is omitted here.

The hydraulic device 428 of the injection drive unit 425 is different from the hydraulic device 28 of the first embodiment only in that, for example, the ninth flow path 443I and the relief valve 473 are provided. The hydraulic pressure device 428 does not have the run-around circuit 369 that the hydraulic pressure device 328 of the third embodiment has.

The ninth flow path 443I connects the rod side chamber 29r and the tank 37. A part of the ninth flow path 443I on the rod side chamber 29r side is shared with a part of other flow paths (43D and 43E) connected to the rod side chamber 29r. A part of the ninth flow path 443I on the tank 37 side is shared with a part of another flow path (43D) connected to the tank 37.

The relief valve 473 is provided in the ninth flow path 443I. The relief valve 473 allows the flow of the hydraulic fluid from the rod side chamber 29r to the tank 37 when the pressure in the rod side chamber 29r exceeds a predetermined set pressure. As a result, the pressure of the rod side chamber 29r is maintained below a predetermined set pressure. In the relief valve 473, the pressure of the rod side chamber 29r may act directly on the valve body, or the pressure of the rod side chamber 29r may be used as the pilot pressure. Further, the relief valve 473 may have a set pressure manually adjusted, or may be adjusted by a solenoid or the like.

The set pressure of the relief valve 473 may be appropriately set. For example, assuming that the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h and the flow rate of the hydraulic fluid discharged from the rod side chamber 29r via the speed valve 49 is the flow rate for high-speed injection, the rod side chamber 29r It may be about the same as the pressure generated. Further, the pressure may be higher than this, or may be lower.

(Operation of injection drive unit)
The control performed by the control device 13 in the present embodiment is basically the same as the control performed by the control device 13 in the third embodiment, except that the control of the run-around circuit 369 is not performed. Hereinafter, an operation different from the operation of the third embodiment due to the provision of the relief valve 473 will be described. Unless otherwise specified, the matters are the same as those of the other embodiments (basically, the third embodiment).

As in the other embodiment, when the pump 39 and the rod side chamber 29r are connected by the operation valve 51 before the start of injection, the pressure in the rod side chamber 29r increases. However, since the relief valve 473 is provided, the pressure of the rod side chamber 29r does not exceed the set pressure of the relief valve 473.

In low-speed injection, the plunger 23 is driven forward by the electric drive unit 381 as in the third embodiment. At this time, the speed valve 49 is closed as in the third embodiment. Therefore, as the injection piston 31 advances, the pressure in the rod side chamber 29r tends to increase. However, since the relief valve 473 is provided, the pressure of the rod side chamber 29r is maintained at the set pressure (constant pressure) of the relief valve 473. The head side chamber 29h and the rear side chamber 29e may be appropriately replenished with the hydraulic fluid as in the other embodiments.

High-speed injection is performed as in other embodiments. Since the pressure of the rod side chamber 29r is maintained at the set pressure of the relief valve 473 during low-speed injection, the possibility of jumping when the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h is reduced. ..

As described above, also in the present embodiment, the injection cylinder 27 is a double-rod type, and the pressure of the rod side chamber 29r immediately before the start of injection or during low-speed injection is made larger than the tank pressure, so that a preferable effect can be obtained. Played. For example, the risk of jumping at the start of high-speed injection is reduced.

Further, in the present embodiment, since the relief valve 473 suppresses the pressure fluctuation of the rod side chamber 29r during low-speed injection, the speed control of the plunger 23 by the electric drive unit 381 is preferably performed. The operation of keeping the pressure of the rod side chamber 29r higher than the tank pressure immediately before the start of injection contributes to the suppression of the pressure rise (pressure fluctuation) at the start of low-speed injection.

The pressure applied to the rod side chamber 29r may be applied by the accumulator 41 instead of the pump 39, as in the second embodiment.

<Modification example related to extension of the rear rod>
The rear rod 61 only needs to be able to reduce the pressure receiving area of the injection piston 31 in the head side chamber 29h. Therefore, for example, the end face of the rear rod 61 may be open to the atmosphere instead of being exposed to the rear chamber 29e. For example, it may have the following configuration.

(Third modification example)
FIG. 10A is a schematic view corresponding to FIG. 3 showing an example in which the end surface of the rear rod 61 is opened to the atmosphere.

In this modification, the pressure boosting piston 501 has the same structure as the pressure boosting piston 33 of the embodiment, and has an extension portion 501e extending rearward from the rear end surface of the large diameter piston portion 501b (corresponding to 33b). ing. The extending portion 501e extends to the outside of the cylinder portion 503 (corresponding to 29) (outside of the rear concubine 29e). At the rear end of the cylinder portion 503, the flow of the hydraulic fluid is basically regulated (sealed) between the inner peripheral surface of the opening through which the extension portion 501e is inserted and the outer peripheral surface of the extension portion 501e. ing).

Further, the hole portion 501h (corresponding to 33h) accommodating the rear rod 61 penetrates the entire pressure boosting piston 501 including the extension portion 501e. Therefore, the hole 501h is open to the atmosphere. As a result, the end face of the rear rod 61 is open to the atmosphere.

(Fourth modification)
FIG. 10B is a schematic view showing another example in which the end face of the rear rod 61 is opened to the atmosphere.

The injection cylinder 509 according to this modification has an injection piston 31 and a pressure boosting piston 513 (corresponding to 33), and a cylinder portion 511 (corresponding to 29) accommodating them.

The cylinder portion 511 includes an injection cylinder portion 511a that slidably accommodates the injection piston 31 and a pressure boosting cylinder portion 511b that slidably accommodates the pressure boosting piston 513.

The inside of the injection cylinder portion 511a is divided into a rod side chamber 511r on the front rod 35 side and a head side chamber 511h on the opposite side by the injection piston 31.

The pressure boosting cylinder portion 511b has a small diameter cylinder portion 511ba that communicates with the head side chamber 511h and a large diameter cylinder portion 511bb that communicates with the small diameter cylinder portion 511ba and has a larger diameter than the small diameter cylinder portion 511ba. The pressure boosting piston 513 has a small-diameter piston portion 513a capable of sliding the small-diameter cylinder portion 511ba and a large-diameter piston portion 513b capable of sliding the large-diameter cylinder portion 511bb.

From the viewpoint of the pressure of the hydraulic fluid, the head side chamber 511h and the inside of the small diameter cylinder portion 511ba may be equated with each other. Therefore, the head side chamber 511h may be defined to include the inside of the small diameter cylinder portion 511ba. In the following explanation, expressions according to such a definition may be used.

The inside of the large-diameter cylinder portion 511bb is divided into a front chamber 511f on the small-diameter cylinder portion 511ba side and a rear chamber 511e on the opposite side by the large-diameter piston portion 513b. From another viewpoint, the inside of the cylinder portion 511 is divided into a head side chamber 29h and a rear side chamber 511e on the opposite side by a pressure boosting piston 513.

Therefore, when the pressure is released from the front side chamber 511f, the pressure receiving area in the rear side chamber 511e of the pressure increasing piston 513 (large diameter piston portion 513b) is relative to the pressure receiving area in the head side chamber 511h of the pressure increasing piston 513 (small diameter piston portion 513a). Therefore, the pressure boosting piston 513 can apply a pressure higher than the pressure received from the hydraulic fluid in the rear concubine 511e to the hydraulic fluid in the head concubine 511h. As a result, the injection cylinder 509 exerts a pressure increasing function.

The cross-sectional area (diameter) of the small-diameter cylinder portion 511ba and the large-diameter cylinder portion 511bb may be smaller, equal to, or larger than the cross-sectional area (diameter) of the injection cylinder portion 511a. Preferably, as shown in the illustrated example, the diameter of the small diameter cylinder portion 511ba is smaller than the diameter of the injection cylinder portion 511a, and the diameter of the large diameter cylinder portion 511bb is larger than the diameter of the injection cylinder portion 511a.

The pressure boosting cylinder portion 511b is arranged so as to intersect (for example, orthogonally) with the injection cylinder portion 511a. The rear rod 61 extends from the injection cylinder portion 511a (head side chamber 511h) to the outside without passing through the pressure boosting cylinder portion 511b (pressure boosting piston 513). As a result, the end face of the rear rod 61 is open to the atmosphere.

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

The molding machine is not limited to the die casting machine. For example, the molding machine may be another metal molding machine, an injection molding machine for molding a resin, or a molding machine for molding a material obtained by mixing wood powder with a thermoplastic resin or the like. There may be. The molding material is not limited to a liquid material, and may have a certain viscosity. For example, the metal material may be a solid-liquid coexisting metal (semi-solidified metal or semi-molten metal).

Further, the molding machine is not limited to the horizontal clamping horizontal injection, and may be, for example, vertical clamping vertical injection, horizontal clamping vertical injection, vertical clamping horizontal injection. When the molding machine is a die casting machine, the die casting machine is not limited to the cold chamber machine and may be a hot chamber machine.

The configurations other than the injection apparatus such as the mold clamping device may be various known configurations. For example, in the embodiment, a toggle type is shown as the mold clamping device, but the mold clamping device may be a composite type that uses separate drive sources for the mold opening / closing and the mold clamping. Further, for example, the mold clamping device may be a fully electric type or a fully hydraulic type.

The injection cylinder is not limited to the pressure boosting type, and may be a so-called single body type (single acting type) having no pressure boosting function. Further, the pressure-increasing injection cylinder is not limited to the direct connection type, and may be a separate type in which the cylinder portion accommodating the injection piston and the cylinder portion accommodating the pressure-increasing piston are separated.

As shown in the modified example of FIG. 10B, the pressure increasing piston only needs to have a large diameter piston portion larger than the diameter of the small diameter piston portion, and the diameter of the small diameter piston portion is necessarily the diameter of the injection piston. It does not have to be equivalent. For example, even when the injection piston and the pressure boosting piston are arranged coaxially as shown in FIG. 2, a small-diameter piston portion is provided behind the injection piston as in the modified example shown in FIG. 10 (b). A cylinder chamber having a diameter smaller than that of the sliding injection piston may be formed.

The hydraulic pressure source for applying pressure to the rod concubine is not limited to the pump or accumulator. For example, as the hydraulic pressure source, a hydraulic cylinder may be used in which the piston and the cylinder portion are relatively driven by the electric motor to deliver the hydraulic fluid. Further, a hydraulic pressure source may be provided separately from the pump (39) or the accumulator (41) for performing the normal injection operation itself. However, as already mentioned, double-rod injection cylinders reduce the need for such separate hydraulic sources.

The configuration shown in the embodiment is conceived from the problem of suppressing jumping that occurs when the flow rate of the hydraulic fluid discharged from the rod side chamber is limited by the meter-out circuit. However, the configuration obtained to solve the problem does not presuppose a meter-out circuit and may not be used for the purpose of suppressing jumping. For example, as can be understood from the low-speed injection operation of the fourth embodiment, in a state where the relief valve is connected to the rod side chamber, the preload of the rod side chamber before the injection start is the rod side chamber after the injection start. It suppresses the pressure rise (pressure fluctuation) and contributes to the improvement of the accuracy of speed control by the electric drive unit.

Further, from the embodiment, it is possible to extract an invention characterized in that the end face of the rear rod is exposed to the posterior chamber. In the present invention, the operation of raising the pressure of the rod side chamber to be higher than the tank pressure immediately before the start of injection is not an essential requirement.

1 ... Die casting machine, 9 ... Injection device, 13 ... Control device, 21 ... Sleeve, 23 ... Plunger, 27 ... Injection cylinder, 28 ... Hydraulic device, 29 ... Cylinder part, 29r ... Rod side chamber, 29h ... Head side chamber, 31 ... injection piston, 35 ... front rod, 61 ... rear rod.

Claims (5)

The front rod connected to the plunger that slides in the sleeve,
The injection piston fixed to the front rod and
A rear rod fixed to the side opposite to the front rod of the injection piston,
A cylinder portion that slidably accommodates the injection piston and
With an injection cylinder,
A hydraulic device that supplies hydraulic fluid to the injection cylinder,
A control device that controls the hydraulic pressure device and
With
The cylinder part
The rod side chamber in which the front rod is arranged and
The head side chamber in which the rear rod is arranged and
Have,
The control device has a rod-side pressure control unit that controls the hydraulic pressure device so that the pressure in the rod-side chamber becomes higher than the tank pressure before the start of injection .
The injection cylinder includes a pressure boosting piston slidably housed in the cylinder portion.
Further prepare
The pressure boosting piston forms the head side chamber and the rear side chamber inside the cylinder portion.
A large-diameter piston portion having a pressure-receiving area in the rear concubine larger than the pressure-receiving area in the head-side chamber.
Have and
The rear rod is slidably inserted into the pressure boosting piston, and the end surface opposite to the injection piston is exposed in the rear chamber.
The hydraulic device is an injection device capable of supplying a hydraulic fluid to the rear chamber to apply pressure . The injection device according to claim 1, wherein the cross section of the rear rod is equal to or larger than the cross section of the front rod. The hydraulic pressure device is
Hydraulic source and
A flow path connecting the hydraulic pressure source and the rod side chamber,
Have and
The control device includes a plunger retreat control unit that controls the hydraulic device so as to retract the plunger by supplying a hydraulic fluid from the hydraulic pressure source to the rod side chamber via the flow path.
Further prepare
The injection device according to claim 1 or 2, wherein the rod-side pressure control unit controls the hydraulic pressure device so as to apply pressure from the hydraulic pressure source to the rod-side chamber via the flow path. The injection device according to any one of claims 1 to 3 , wherein the hydraulic device has a flow rate control valve for controlling the flow rate of the hydraulic fluid discharged from the rod side chamber. The injection device according to any one of claims 1 to 4 ,
A mold clamping device that clamps the mold and
An extruder that extrudes a molded product from the mold,
Molding machine that has.

Images