JP6764272B2 - 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 an injection piston rod connected to a plunger, an injection piston fixed to the injection piston rod, and an injection cylinder portion for accommodating the injection piston. The inside of the injection cylinder portion is divided into a rod side chamber on the side where the injection piston rod extends by the injection piston and a head side chamber on the opposite side. Then, when the hydraulic fluid (for example, oil) is supplied to the head side chamber, the injection piston moves to the injection 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).

In addition, Patent Document 1 discloses an accumulator connected to a rod side chamber in order to suppress surge pressure.

Japanese Unexamined Patent Publication No. 6-297128

Ideally, when a meter-out circuit is used, 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.

The injection device according to one aspect of the present invention slides the injection piston rod connected to the plunger that is slidable in the sleeve leading to the inside of the mold, the injection piston fixed to the injection piston rod, and the injection piston. The injection cylinder includes an injection cylinder that movably accommodates the injection cylinder and a hydraulic device capable of supplying a hydraulic fluid to the injection cylinder. The injection cylinder has a rod side chamber on the injection side with respect to the injection piston and a head on the opposite side. It has an injection cylinder portion partitioned from a side chamber, the hydraulic device is connected to the head side chamber so as to be able to supply the hydraulic fluid, and a compression cylinder for increasing the pressure of the hydraulic fluid is connected to the rod side chamber. The compression cylinder includes a compression piston and a compression cylinder portion that slidably accommodates the compression piston and constitutes a low-pressure chamber and a high-pressure chamber with the compression piston sandwiched therein, and the low-pressure chamber of the compression piston. The pressure receiving area of the compression piston is larger than the pressure receiving area of the compression piston in the high pressure chamber, the high pressure chamber is connected to the rod side chamber, and the hydraulic fluid can be supplied to the low pressure chamber by the hydraulic pressure device. It is characterized by that.

Preferably, the pressure increasing ratio obtained by dividing the pressure receiving area of the compression piston in the low pressure chamber by the pressure receiving area of the compression piston in the high pressure chamber is such that the pressure receiving area of the injection piston in the head side chamber is divided by the rod side chamber of the injection piston. It is the same or larger than the pressure increase ratio divided by the pressure receiving area in.

Preferably, the hydraulic device comprises a hydraulic source capable of delivering a hydraulic fluid, a flow path connecting the hydraulic source and the head side chamber, and a flow connecting the hydraulic source and the low pressure chamber. Has a road.

Preferably, the injection device further includes an electric drive unit capable of driving the injection piston rod with respect to the injection cylinder portion, and in the hydraulic device, the pressure in the rod side chamber is a predetermined pressure. It has a relief valve that discharges the hydraulic fluid from the rod side chamber when the amount exceeds.

Preferably, the injection device further includes a control device that controls the hydraulic fluid so as to supply the hydraulic fluid to the head side chamber after supplying the hydraulic fluid to the low pressure chamber.

Preferably, the injection device further comprises a control device that controls the hydraulic device and the electric drive unit so as to advance the plunger by the electric drive unit after supplying the hydraulic fluid to the low pressure chamber. Have.

Preferably, the control device controls the electric drive unit and the hydraulic device so as to supply the hydraulic fluid to the head side chamber after the plunger is advanced by the electric drive unit.

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 includes 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. 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. 8 (a) to 8 (c) are schematic views showing a modified example of the compression 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 to (corresponding to) the configuration of the embodiment described above is assigned a code different from the reference numeral assigned to the configuration of the embodiment described above, matters not otherwise specified are already described. It is similar to the configuration of the form.

<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.

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 injection cylinder portion 29, the injection piston 31 and the pressure boosting piston 33 slidable inside the injection cylinder portion 29, and the injection piston 31, and the injection cylinder portion 29 is fixed. It has an injection piston rod 35 extending from.

The injection 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 injection piston 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.

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 by the injection piston 31 into a rod side chamber 29r on the side where the injection piston rod 35 extends and a head side chamber 29h on the opposite side. 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 29g on the opposite side by the large-diameter piston portion 33b.

Therefore, when the pressure is released from the front chamber 29f, the pressure receiving area in the rear chamber 29g of the large diameter piston portion 33b is larger than the pressure receiving area in the head side chamber 29h of the small diameter piston portion 33a. It is possible to apply a pressure higher than the pressure received from the hydraulic fluid in the concubine 29g 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 has a convex portion 34 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 convex portion 34 may protrude rearward from the injection piston 31 and may come into contact with the front end surface of the small diameter piston portion 33a. Such a convex portion 34 is, for example, when a 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 convex portion 34 may be omitted. Further, when the convex portion 34 is separated from the injection piston 31 (or the pressure boosting piston 33), the presence of the convex portion 34 is a pressure receiving area in the head side chamber 29h of the pressure boosting piston 33 (or the head side chamber 29h of the injection piston 31). Does not affect the pressure receiving area). Therefore, in the description of the present embodiment, the convex portion 34 is basically ignored.

As shown in FIG. 1, the injection cylinder 27 is arranged coaxially with the plunger 23. The tip of the injection piston rod 35 is connected to the rear end of the plunger 23 via a coupling (reference numeral omitted). The injection 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 injection cylinder portion 29 causes the plunger 23 to move forward or backward in the sleeve 21.

The hydraulic device 28 uses, 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 an injection cylinder 27. It has a plurality of connecting flow paths (43A to 43H, etc.) and a plurality of valves (45, 47, 49, 51, 53, 55, 67, etc.) that control the flow of the hydraulic fluid in the plurality of flow paths. ing. 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 the pump electric motor 40 to deliver the 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 pump motor 40 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 29g. Thereby, for example, the hydraulic fluid can be supplied from the accumulator 41 to the rear side chamber 29g, and the hydraulic fluid in the head side chamber 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 a switching 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 a switching valve 51 described later.

The plurality of channels (43A to 43H, 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. 2, 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 other flow paths (43A, 43C and 43G)), and the hydraulic fluid from the accumulator 41 to the head side chamber 29h. Allow or prohibit the flow of. 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, 43B and 43G)), and the hydraulic fluid from the accumulator 41 to the rear concubine 29g. Allow or prohibit the flow of. 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 switching valve 51 is composed of, for example, a switching valve having 4 ports and 3 positions. The switching valve 51 cuts off the connection of the four ports at the position in the center of the paper (neutral position and / or normal position).

Further, the switching 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 at the position shown on the left side of the paper surface. 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.

Further, the switching 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, the flow of the hydraulic fluid is not essential, and the switching 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 switching valve 51 may be, for example, a spring type, an electromagnetic type, a pilot type, or a combination of two or more of these. FIG. 2 shows a switching 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.

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 valve 49. It has a cooler 59 and the like that cools the hydraulic fluid flowing to the tank 37 via the valve.

(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.

Therefore, in the present embodiment, for example, before supplying the hydraulic fluid to the head side chamber 29h, the hydraulic fluid in the rod side chamber 29r is compressed in advance, thereby reducing the possibility of jumping. Specifically, jumping is suppressed by the following configuration.

The injection drive unit 25 has a compression cylinder 61. The compression cylinder 61 has a compression cylinder portion 63 and a compression piston 65 slidably housed in the compression cylinder portion 63.

The compression cylinder 61 is configured to have a pressure increasing function. For example, the compression cylinder portion 63 has a first cylinder portion 63a and a second cylinder portion 63b having a diameter (cross section) larger than that of the first cylinder portion 63a. On the other hand, the compression piston 65 has a first piston portion 65a slidable on the first cylinder portion 63a and a second piston portion 65b slidable on the second cylinder portion 63b. The inside of the first cylinder portion 63a is a first cylinder chamber 63e in which the tip surface (the surface opposite to the second piston portion 65b) of the first piston portion 65a is exposed. The inside of the second cylinder portion 63b is divided into a second cylinder chamber 63f on the first cylinder chamber 63e side and a third cylinder chamber 63g on the opposite side by the second piston portion 65b.

Therefore, for example, when the pressure of the second cylinder chamber 63f is released, the pressure receiving area of the second piston portion 65b in the third cylinder chamber 63g is larger than the pressure receiving area of the first piston portion 65a in the first cylinder chamber 63e. The compression piston 65 can apply a pressure higher than the pressure received from the hydraulic fluid in the third cylinder chamber 63g to the first cylinder chamber 63e.

The hydraulic device 28 can supply the hydraulic fluid to 63 g of the third cylinder chamber. For example, the hydraulic pressure device 28 has a seventh flow path 43G connecting the third cylinder chamber 63g and the accumulator 41 (liquid chamber 41e), and the hydraulic fluid can be supplied from the accumulator 41 to the third cylinder chamber 63g. Is. In the illustrated example, a part of the seventh flow path 43G on the accumulator 41 side is shared with the second flow path 43B.

The first cylinder chamber 63e communicates with the rod side chamber 29r, and the pressure can be applied to the rod side chamber 29r. For example, the hydraulic pressure device 28 has an eighth flow path 43H that connects the first cylinder chamber 63e and the rod side chamber 29r, whereby the first cylinder chamber 63e and the rod side chamber 29r are communicated with each other. The first cylinder chamber 63e and the rod side chamber 29r may be communicated with each other by directly connecting an appropriate portion of the first cylinder portion 63a and an appropriate portion of the small diameter cylinder portion 29a.

Although not particularly shown, the second cylinder chamber 63f is connected to the tank 37 via an appropriate flow path. Therefore, the second cylinder chamber 63f can discharge the hydraulic fluid to the tank 37 as the compression piston 65 advances. Further, the second cylinder chamber 63f can be replenished with the hydraulic fluid from the tank 37 by a negative pressure as the compression piston 65 retracts. The hydraulic fluid may be replenished to the second cylinder chamber 63f by the pump 39. Further, the second cylinder chamber 63f may be opened to the atmosphere instead of being filled with the hydraulic fluid.

Therefore, by supplying the hydraulic fluid from the hydraulic pressure device 28 to the third cylinder chamber 63g, the pressure of the hydraulic fluid can be increased and the pressure can be applied from the first cylinder chamber 63e to the rod side chamber 29r. By applying this pressure before supplying the hydraulic fluid to the head side chamber 29h, for example, the possibility of jumping can be reduced.

Here, the pressure receiving area of the injection piston 31 in the rod side chamber 29r is reduced by the injection piston rod 35. That is, 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. Therefore, the injection piston 31 can 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.

The pressure boosting ratio of the compression piston 65 is preferably equal to or higher than the pressure boosting ratio of the injection piston 31. That is, the ratio (S ₂ / S ₁ , where S ₂ >) of the pressure receiving area (S ₂ ) of the compression piston 65 in the third cylinder chamber 63 g divided by the pressure receiving area (S ₁ ) of the compression piston 65 in the first cylinder chamber 63e. S ₁ ) is the ratio (S ₄ / S ₃ ) obtained by dividing the pressure receiving area (S ₄ ) in the head side chamber 29h of the injection piston 31 by the pressure receiving area (S ₃ ) in the rod side chamber 29r of the injection piston 31, where S ₄ > S. It is preferable that the value is equal to or higher than that of ₃ ) (S ₂ / S ₁ ≧ S ₄ / S ₃ ).

More preferably, the pressure boost ratio (S ₂ / S ₁ ) in the compression piston 65 is larger than the pressure boost ratio (S ₄ / S ₃ ) in the injection piston 31 (S ₂ / S ₁ > S ₄ / S ₃ ). For example, the former is larger than the latter by a difference of 10% or more and 20% or less of the pressure increasing ratio of the latter.

The hydraulic device 28 has a compression valve 67 that controls the supply of the hydraulic fluid to the third cylinder chamber 63 g. The compression valve 67 is provided in, for example, the 7th flow path 43G (a portion not shared with the other flow path (43B)) to allow the flow of the hydraulic fluid from the accumulator 41 to the 3rd cylinder chamber 63g. Ban. The compression valve 67 is composed of, for example, a pilot type check valve, and when the pilot pressure is not introduced, the flow of the hydraulic fluid from the accumulator 41 to the third cylinder chamber 63 g is prohibited, and the flow thereof is prohibited. Allows flow in opposite directions and, when pilot pressure is introduced, allows both flows.

(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. The plurality of functional units are, for example, a compression cylinder control unit 13a and an injection cylinder control unit 13b.

The compression cylinder control unit 13a controls the operation of the compression cylinder 61. Specifically, for example, the compression cylinder control unit 13a outputs a control signal to a hydraulic pressure circuit (not shown) that introduces pilot pressure to the compression valve 67 based on signals from the input device 17 and various sensors. To do.

The injection cylinder control unit 13b controls the operation of the injection cylinder 27. Specifically, for example, the injection cylinder control unit 13b introduces a pilot pressure into the injection valve 45 based on signals from the input device 17 and various sensors, etc., a hydraulic pressure circuit (not shown), a pressure boosting valve 47. A control signal is output to a driver (not shown) that drives the speed valve 49, a driver (not shown) that drives the speed valve 49, and a driver (not shown) that drives the switching valve 51.

The sensors that input signals to the control device 13 are, for example, a position sensor 69 that detects the position of the plunger 23 and a pressure sensor 71 that detects the pressure of the accumulator 41.

The position sensor 69 constitutes, for example, a linear encoder. For example, the position sensor 69 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 69 and / or the control device 13 can specify the relative position between the position sensor 69 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 69 is fixedly provided to the injection cylinder portion 29, and the scale portion is provided on the injection piston rod 35 or a member fixed to the injection piston rod 35. Therefore, by detecting the position and / or speed of the injection piston rod 35, the position and / or speed of the plunger 23 is indirectly detected.

The position sensor 69 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 69 is provided fixedly to, for example, the injection cylinder portion 29, and measures the distance to the injection piston rod 35 or a member fixed to the injection piston rod 35. It may be a laser length measuring device.

The pressure sensor 71 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 71, a known appropriate one such as a diaphragm type may be used. Further, as the pressure sensor 71, in addition to or instead of the one that detects the pressure in the liquid chamber 41e, the one that detects the pressure in the gas chamber 41f may be used.

(Operation of injection device)
FIG. 3 is a timing chart for explaining the operation of the injection device 9.

The upper part of FIG. 3 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. 3, 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. 3 shows the operation of the injection valve 45, the pressure boosting valve 47, the speed valve 49, and the compression valve 67 corresponding to the passage of time in the upper part of FIG. In the lower part of FIG. 3, 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 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 (operation of the compression cylinder 61 and the compression valve 67) 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 switching 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 69. The speed feedback control may be such that the deviation of the speed itself is obtained, or the deviation between the momentary (every elapsed time) target position obtained from the speed target value and the detected position is obtained. , The speed feedback control may be substantially performed by performing the position feedback control from moment to moment.

(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 69.

(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 29 g, 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.

After that, the force due to the increased pressure of the head side chamber 29h and the force due to the pressure 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. 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 29g.

After the extrusion follow-up, 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 by, for example, a switching valve 51. Further, the control device 13 closes the injection valve 45, the pressure boosting valve 47, and the speed valve 49. As a result, 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.

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 hydraulic fluid in the rear concubine 29 g is discharged to the tank 37 through, for example, a flow path (not shown). The hydraulic fluid discharged from the rear side chamber 29g may be filled in the accumulator 41 via the pressure boosting valve 47. 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 switching 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 71 reaches a predetermined set pressure, the control device 13 stops driving the pump 39, for example.

(Operation for jumping suppression)
The control device 13 controls a hydraulic circuit (not shown) that introduces pilot pressure into the compression valve 67 so as to open the compression valve 67 at an appropriate time before the start of low-speed injection (before the time point t0). As a result, the hydraulic fluid is supplied from the accumulator 41 to the third cylinder chamber 63 g of the compression cylinder 61, and the pressure increased by the compression cylinder 61 is applied to the rod side chamber 29r. As a result, the hydraulic fluid in the rod side chamber 29r is compressed. As a result, even if the hydraulic fluid is supplied from the accumulator 41 to the head side chamber 29h after that (time point t0), the compression of the hydraulic fluid in the rod side chamber 29r does not occur or is suppressed, and the possibility of jumping is reduced.

Further, the control device 13 is a hydraulic circuit (not shown) so as to stop the introduction of the pilot pressure into the compression valve 67 after opening the compression valve 67 to compress the hydraulic fluid in the rod side chamber 29r as described above. To control. Even if the compression valve 67 is closed, the discharge of the hydraulic fluid from the rod side chamber 29r and the first cylinder chamber 63e is prohibited, so that the compression of the hydraulic fluid in the rod side chamber 29r is basically maintained. After that, when the injection valve 45 and the speed valve 49 are opened, 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.

When pressure is applied from the compression cylinder 61 to the rod side chamber 29r, the injection piston 31 located at the retreat limit is in contact with, for example, a stopper (not shown) provided in the injection cylinder portion 29. Retreat is regulated by, and / or retreat is regulated by contacting the pressure boosting piston 33, which is regulated by contacting a stopper (not shown) provided on the injection cylinder portion 29. There is. Further, the injection piston 31 may be restricted from retreating by prohibiting the discharge of the hydraulic fluid from the head side chamber 29h.

The time for keeping the compression valve 67 open may be appropriately set so that the compression cylinder 61 completes the compression of the hydraulic fluid in the rod side chamber 29r, or the compression proceeds to some extent.

The timing of opening the compression valve 67 may be an appropriate time point before the start of low-speed injection. For example, it may be a time point at which the time for keeping the compression valve 67 open is secured before the hydraulic fluid is supplied to the head side chamber 29h. Further, the timing of opening the compression valve 67 may be before or after the completion of mold clamping, or before or after the molten metal is supplied to the sleeve 21. May be good.

If the mass and sliding resistance of the plunger 23, the injection piston rod 35 and the injection piston 31 are relatively large, or if the injection valve 45 is configured and controlled to be gradually opened, the rod by the compression cylinder 61 is used. Even if the pressure applied to the side chamber 29r is simultaneously applied to the pressure applied to the head side chamber 29h or is slightly delayed, the effect of suppressing jumping can be obtained to some extent. Therefore, the timing of opening the compression valve 67 is basically the time before the timing of opening the injection valve 45, but it may be at the same time or slightly after. Further, the timing at which the control device 13 outputs the control signal to the compression valve 67 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 timing of closing the compression valve 67 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 timing of closing the compression valve 67 is too early for the start of injection, for example, the pressure in the rod side chamber 29r increased by the compression cylinder 61 may decrease due to leakage of the hydraulic fluid or the like, and the effect of suppressing jumping may decrease. There is. If the timing of closing the compression valve 67 is later than the start of injection, the pressure of the rod side chamber 29r after the speed valve 49 is opened, although it depends on the magnitude of the pressure applied to the rod side chamber 29r by the compression cylinder 61. There is a delay before the start of the decrease, which in turn delays the start of advancement of the plunger 23. Therefore, it is preferable that the timing of closing the compression valve 67 is substantially the same as the start of injection.

When the injection valve 45 is opened with the speed valve 49 closed, for example, the pressure of the rod side chamber 29r is made larger than the pressure of the head side chamber 29h by the compression cylinder 61 at a ratio equal to or higher than the pressure increasing ratio by the injection piston 31. Then, basically, the plunger 23 does not move forward (jumping does not occur). Therefore, the speed valve 49 may be opened after the injection valve 45 is opened. In this case, injection is started when the speed valve 49 is opened.

When the hydraulic fluid is supplied to the rod side chamber 29r to retract the plunger 23, the hydraulic fluid is also supplied to the first cylinder chamber 63e of the compression cylinder 61. At this time, the hydraulic fluid in the third cylinder chamber 63 g is discharged to the tank 37 through, for example, a flow path (not shown). As a result, the compression piston 65 returns to the initial position (retraction limit). The hydraulic fluid discharged from the third cylinder chamber 63 g may be filled in the accumulator 41.

(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 switching 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 in FIG. 2 and 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 by the compression cylinder 61.

(Second modification)
As shown by the alternate long and short dash line in the diagram relating to the compression valve 67 of FIG. 3, the compression valve 67 may be maintained in an open state until after the injection valve 45 and the speed valve 49 are opened.

Here, when the injection valve 45 and the speed valve 49 are opened, the hydraulic fluid is supplied to the head side chamber 29h, and the injection piston 31 tries to move forward while reducing the volume of the rod side chamber 29r. On the other hand, the discharge of the hydraulic fluid from the rod side chamber 29r is restricted by the speed valve 49. Therefore, for example, even when the compression cylinder 61 is not provided, the pressure of the rod side chamber 29r becomes higher than the tank pressure. The operation of the compression cylinder 61 differs depending on the magnitude of this pressure.

(1 of the second modification)
For example, when the pressure in the first cylinder chamber 63e is higher than the pressure in the rod side chamber 29r after the injection valve 45 and the speed valve 49 are opened, the hydraulic fluid is transferred from the first cylinder chamber 63e to the rod side chamber 29r. Flows. Therefore, the compression piston 65 moves forward. Further, the injection piston 31 generally maintains a stop or advances at a speed lower than a speed corresponding to the flow rate of the hydraulic fluid discharged from the rod side chamber 29r to the tank 37. After that, when the compression piston 65 reaches the forward limit, the application of pressure from the compression cylinder 61 to the rod side chamber 29r is completed, and the injection piston 31 corresponds to the flow rate of the hydraulic fluid discharged from the rod side chamber 29r to the tank 37. Move forward at speed.

Even in such an operation, if the time from the beginning until the compression piston 65 reaches the forward limit is taken into consideration as the control delay of the injection start and the timing of opening each valve is advanced, the injection speed similar to that of the embodiment is achieved. And injection pressure is obtained. Further, as in the embodiment, since the rod side chamber 29r is preloaded, the possibility of jumping is reduced.

After the compression piston 65 reaches the forward limit, basically, the opening and closing of the compression valve 67 does not affect the injection and the pressure increase. Therefore, the compression valve 67 may be closed at an appropriate time.

(2 of the second modification)
Further, for example, contrary to 2 of the second modification described above, the pressure of the first cylinder chamber 63e is about to be applied to the rod side chamber 29r after the injection valve 45 and the speed valve 49 are opened. If it is lower than that, the hydraulic fluid does not flow from the first cylinder chamber 63e to the rod side chamber 29r. Therefore, when the injection valve 45 and the speed valve 49 are opened, the injection piston 31 starts advancing. However, since the hydraulic fluid flows from the rod side chamber 29r to the first cylinder chamber 63e, the speed of the injection piston 31 is discharged from the rod side chamber 29r to the tank 37 until the compression piston 65 retracts to the retreat limit. Higher than the speed corresponding to the flow rate of the hydraulic fluid.

Even in such an operation, since the rod side chamber 29r is preloaded as in the embodiment, the possibility of jumping is reduced. However, when the hydraulic fluid is supplied to the head side chamber 29h, the rod side chamber 29r is applied with a pressure higher than the pressure applied by the compression cylinder 61 by the injection piston 31, so that some hydraulic fluid is applied. Compression can occur.

In order to reduce the pressure in the rod side chamber 29r at the start of pressure increase, the compression valve 67 is preferably closed at the start of pressure increase. However, when the injection piston 31 decelerates and stops due to the force received from the molten metal by the plunger 23, the pressure in the rod side chamber 29r where the hydraulic fluid is allowed to be discharged by the speed valve 49 decreases, and the compression piston 65 moves forward and forwards. When the limit is reached, the compression cylinder 61 no longer applies pressure to the rod side chamber 29r. You may wait for that state.

(3 of the second modification)
Further, for example, when the pressure of the first cylinder chamber 63e is equivalent to the pressure after the injection valve 45 and the speed valve 49 are opened, the operation is substantially the same as that of the second modification 2 described above.

However, even if the hydraulic fluid is supplied to the head side chamber 29h, the pressure applied by the compression cylinder 61 is maintained in the rod side chamber 29r, so that the hydraulic fluid is basically not compressed. Further, the hydraulic fluid in the rod side chamber 29r basically does not flow into the first cylinder chamber 63e. Therefore, the operation is more preferable than 2 in the second modification described above.

As described above, in the present embodiment, the injection device 9 has an injection cylinder 27 and a hydraulic pressure device 28. The injection cylinder 27 slides an injection piston rod 35 connected to a plunger 23 slidable in a sleeve 21 leading to the mold 101, an injection piston 31 fixed to the injection piston rod 35, and an injection piston 31. It has an injection cylinder portion 29 that can be accommodated. The inside of the injection cylinder portion 29 is divided into a rod side chamber 29r on the side where the injection piston rod 35 extends by the injection piston 31 and a head side chamber 29h on the opposite side. The hydraulic fluid device 28 can supply the hydraulic fluid to the head side chamber 29h. Further, the injection device 9 has a compression cylinder 61. The compression cylinder 61 has a compression piston 65 and a compression cylinder portion 63 that slidably accommodates the compression piston 65. The compression cylinder portion 63 has a third cylinder chamber 63 g (low pressure chamber) and a first cylinder chamber 63e (high pressure chamber) with the compression piston 65 interposed therebetween. The pressure receiving area of the compression piston 65 in the third cylinder chamber 63g is larger than the pressure receiving area of the compression piston 65 in the first cylinder chamber 63e. The first cylinder chamber 63e communicates with the rod side chamber 29r. The hydraulic device 28 can supply the hydraulic fluid to 63 g of the third cylinder chamber.

Therefore, the hydraulic fluid can be supplied to the third cylinder chamber 63 g, and pressure can be applied to the rod side chamber 29r by the compression cylinder 61. Then, for example, the hydraulic fluid in the rod side chamber 29r can be compressed before the start of injection to reduce the possibility of jumping. As described above, when the pressure is applied to the head side chamber 29h, a pressure higher than the pressure applied to the head side chamber 29h is likely to be applied to the rod side chamber 29r due to the pressure increasing action of the injection piston 31. Further, a relatively high pressure is applied to the head side chamber 29h, such as the hydraulic fluid being supplied from the accumulator 41 as in the embodiment. However, since the compression cylinder 61 has a pressure increasing action, the pressure in the rod side chamber 29r can be sufficiently increased to more reliably suppress the possibility of jumping. Further, since the pressure of the hydraulic fluid in the rod side chamber 29r is relatively increased by utilizing the pressure increasing action of the compression cylinder 61, for example, a new hydraulic pressure source capable of applying a pressure higher than that of the accumulator 41 is provided. Cost reduction is expected as compared with the case where the pressure of the rod side chamber 29r is relatively high.

Further, in the present embodiment, the third intensification ratio, divided by the pressure receiving area _{(S 1)} in the first cylinder chamber 63e of the compression piston 65 a pressure receiving area _{(S 2)} in the cylinder chamber 63g of the compression piston 65, the injection piston 31 It is equal to or greater than the pressure increasing ratio obtained by dividing the pressure receiving area (S ₄ ) in the head side chamber 29h by the pressure receiving area (S ₃ ) in the rod side chamber 29r of the injection piston 31 (S ₂ / S ₁ ≧ S ₄ / S ₃ ).

Therefore, it is easy to apply a pressure equal to or higher than the pressure of the rod side chamber 29r generated by the pressure increasing action of the injection piston 31 to the rod side chamber 29r by the compression cylinder 61. Further, the pressure cylinder 61 applies a pressure higher than the pressure applied to the rod side chamber 29r by the injection piston 31 to the rod side chamber 29r from the same hydraulic pressure source (accumulator 41) to the head side chamber 29h and the third cylinder. It is also possible to supply the hydraulic fluid to the chamber 63 g.

As already described, the pressure boosting ratio (S ₂ / S ₁ ) in the compression piston 65 is preferably larger than the pressure boosting ratio (S ₄ / S ₃ ) in the injection piston 31. The pressure of the rod side chamber 29r raised in advance by the compression piston 65 is static pressure, whereas the pressure of the head side chamber 29h to which the hydraulic fluid is supplied is dynamic pressure. Therefore, from the viewpoint of surely reducing the possibility of jumping, the pressure applied to the rod side chamber 29r by the compression piston 65 is higher than the pressure applied to the rod side chamber 29r by the injection piston 31 based on the pressure of the head side chamber 29h. This is because it is preferable that the pressure is exceeded.

Further, in the present embodiment, the hydraulic pressure device 28 includes an accumulator 41 (hydraulic pressure source) capable of delivering the hydraulic fluid, a second flow path 43B connecting the accumulator 41 and the head side chamber 29h, and the accumulator 41 and the third. It has a seventh flow path 43G that connects to the cylinder chamber 63g.

That is, as a hydraulic pressure source for applying pressure to the rod side chamber 29r in advance by the compression cylinder 61, a hydraulic pressure source that supplies the hydraulic fluid to the head side chamber 29h at the time of injection is used. Therefore, it is not necessary to newly provide a hydraulic pressure source, and the cost can be reduced.

Further, in the present embodiment, the injection device 9 further includes a control device 13 that controls the hydraulic pressure device 28 so as to supply the hydraulic fluid to the head side chamber 29h after supplying the hydraulic fluid to the third cylinder chamber 63 g. ing. That is, the control device 13 operates to the compression cylinder control unit 13a that controls the hydraulic pressure device 28 (compression valve 67) so as to supply the hydraulic fluid to the third cylinder chamber 63g, and to the head side chamber 29h after the control thereof. It has an injection cylinder control unit 13b that controls the hydraulic pressure device 28 (injection valve 45) so as to supply the liquid.

Therefore, it is possible to apply pressure to the rod side chamber 29r in advance before supplying the hydraulic fluid to the head side chamber 29h to more reliably reduce the possibility of jumping. Before and after the supply of the hydraulic fluid referred to here, it may be determined at the timing when the compression valve 67 and the injection valve 45 are actually opened (for example, when they start to be opened), and the difference in control delay between the two valves is almost the same. If it can be ignored, the determination may be made at the timing of the control signal output from the control device 13.

In the first embodiment, the die casting machine 1 is an example of a molding machine, the first cylinder chamber 63e is an example of a high pressure chamber, the third cylinder chamber 63 g is an example of a low pressure chamber, and the accumulator 41 is a hydraulic pressure. The second flow path 43B and the seventh flow path 43G are examples of the flow paths connected to the hydraulic pressure source.

<Second Embodiment>
FIG. 4 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, the hydraulic fluid was supplied from the accumulator 41 to the third cylinder chamber 63 g of the compression cylinder 61. On the other hand, in the injection drive unit 225 of the present embodiment, the hydraulic fluid is supplied from the pump 39 to the third cylinder chamber 63 g. 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 that connects the pump 39 and the third cylinder chamber 63g instead of the seventh flow path 43G of the first embodiment. ing. A part of the seventh flow path 243G on the pump 39 side is shared with, for example, a part of another flow path connected to the pump 39.

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 the compression cylinder 61, the hydraulic fluid is supplied from the pump 39 instead of the hydraulic fluid from the accumulator 41. Is performed, the operation is the same as that of the injection drive unit 25 of the first embodiment. In the second embodiment, the pump 39 may be driven all the time or only when necessary.

Also in this embodiment, the compression cylinder 61 having a pressure increasing function is provided, the first cylinder chamber 63e is connected to the rod side chamber 29r, and the hydraulic pressure device 228 can supply the hydraulic fluid to the third cylinder chamber 63g. Therefore, the same effect as that of the first embodiment is obtained. For example, the possibility of jumping occurring by preloading the rod side chamber 29r can be suitably reduced.

<Third Embodiment>
(Composition of injection drive unit)
FIG. 5 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 (configuration of the control device 313) 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 injection piston 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 injection piston rod 35, and the case member is placed between the plunger 23 and the injection piston rod 35. On the other hand, it constitutes a part that expands in 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 motor 383 is arranged so that the output shaft 383a is parallel to the injection piston 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 injection piston 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 injection piston 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 injection piston rod 35 by the driving force of the driving electric motor 383.

The driven portion 391 is restricted from being relatively advanced with respect to the injection piston rod 35 by engaging and / or being detached, and is allowed to be relatively retracted with respect to the injection piston rod 35. Since the injection piston rod 35 and the plunger 23 are connected to each other, the regulation of relative advancement and the allowance of retreat with respect to the injection piston rod 35 referred to here are the regulation of relative advancement and the allowance of retreat with respect to the plunger 23. Is synonymous with.

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 injection piston rod 35, and allows the base portion 391a to retreat with respect to the injection piston 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 injection piston 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, the driven portion 391 is attached to and detached from the injection piston rod 35 by, for example, an electromagnet, or by holding the injection piston rod 35 in the radial direction (and by extension, frictional resistance) in addition to or instead of engaging the base portion 391a. It may be done.

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

The hydraulic system of the injection drive unit 325 is different from the hydraulic system of the injection drive unit 25 of the first embodiment only in that, for example, the ninth flow path 343I and the relief valve 393 are provided.

The ninth flow path 343I connects the rod side chamber 29r and the tank 37. A part of the ninth flow path 343I on the rod side chamber 29r side is shared with a part of other flow paths (43D and 43E). A part of the ninth flow path 343I on the tank 37 side is shared with a part of the other flow path (43D).

The relief valve 393 is provided in the ninth flow path 343I. The relief valve 393 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 393, 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 393 may have a set pressure adjusted manually, or may be adjusted by a solenoid or the like.

The set pressure of the relief valve 393 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 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 in. Further, the pressure may be higher than this, or may be lower.

(Functional part of control device)
Similar to the first embodiment, in the control device 313, various functional units are configured by the CPU executing the program. Specifically, as in the first embodiment, the compression cylinder control unit 313a for controlling the compression cylinder 61 and the injection cylinder control unit 313b for controlling the injection cylinder 27 are configured, and the electric drive unit is configured. An electric control unit 313c for controlling 381 is configured.

Although the valve control timing of the compression cylinder control unit 313a and the injection cylinder control unit 313b is different from that of the first embodiment, the control target and the like may be the same as those of the first embodiment. The electric control unit 313c outputs a control signal to a driver for driving the drive electric motor 383 and a driver for an actuator (not shown) for driving the hook 391b, based on, for example, a signal from the position sensor 69 and / or the encoder 383b. ..

(Operation of injection device)
FIG. 7 is a timing chart for explaining the operation of the injection device 309, and is a diagram corresponding to FIG. 3 of the first embodiment.

The horizontal axis and the vertical axis of FIG. 7 are the same as those of FIG. However, in FIG. 7, a drive electric motor 383 is added in addition to the control target shown in FIG.

First, the basic operation of the injection device 309 will be described, and then the operation for preventing jumping (operation of the compression cylinder 61 and the compression valve 67) 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 and 51) 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 injection piston rod 35 located at the retreat limit from the rear, and the hook 391b is in the engaging position.

Then, the control device 313 starts low-speed injection when the injection start condition is satisfied (time point t0), as in the first embodiment. 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 313 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 injection piston rod 35 move forward.

At this time, the hydraulic fluid in the rod side chamber 29r whose volume decreases as the injection piston 31 advances is discharged to the tank 37 via the relief valve 393. By the action of the relief valve 393, the pressure of the rod side chamber 29r is basically maintained at the set pressure. Unlike the first embodiment, the injection valve 45 and the speed valve 49 are maintained in a closed state in the low speed injection.

The hydraulic fluid may be appropriately replenished to the head side chamber 29h whose volume increases as the injection piston 31 advances. For example, the head side chamber 29h and the tank 37 may be connected by a flow path (not shown) to replenish the hydraulic fluid by negative pressure. Further, for example, the hydraulic fluid may be supplied from the pump 39 to the head side chamber 29h by the configuration as described in the first modification. At this time, the pressure of the hydraulic fluid in the head side chamber 29h may be set to such an extent that no negative pressure is generated, or may be set to a pressure equal to or higher than the tank pressure, and the pump 39 may assist the electric drive unit 381.

The speed of the plunger 23 is controlled by adjusting the rotation speed of the drive electric motor 383. Specifically, the control device 313 (electric control unit 313c) feedback-controls the rotation speed of the drive electric motor 383 based on the signal from the position sensor 69. 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 69.

The discharge of the hydraulic fluid from the relief valve 393 is prohibited by increasing the set pressure or by closing the valve (not shown) provided in the ninth flow path 343I.

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.

Note that FIG. 7 illustrates a case where the drive of the electric drive unit 381 is stopped in high-speed injection. However, for example, the electric drive unit 381 may advance the driven unit 391 following the low speed injection in order to contribute to extrusion follow-up and / or retreat of the plunger 23. Further, for example, the electric drive unit 381 may retract the driven unit 391 at an appropriate time after the low-speed injection to prepare for the next injection.

(Deceleration, pressure increase, pressure retention, extrusion follow-up and plunger retreat)
Deceleration, pressure increase, pressure retention, extrusion follow-up, and plunger retreat may be performed in the same manner as in the first embodiment. Further, following the low-speed injection, the driven unit 391 is advanced, the driven unit 391 is made to catch up with the plunger 23 decelerated by the force from the molten metal, and the electric drive unit 381 is increased in pressure, held in pressure, and followed by extrusion. You may contribute to either. Further, the hook 391b may be engaged with the coupling 24, and the plunger 23 may be retracted by the driving force of the electric drive unit 381.

(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, in the third embodiment, the following operations are performed.

Similar to the first embodiment, the control device 313 opens the compression valve 67 at an appropriate time before the start of low-speed injection (before the time point t0). As a result, as in the first embodiment, pressure is applied to the rod side chamber 29r, and the hydraulic fluid in the rod side chamber 29r is compressed. However, since the relief valve 393 is provided, the pressure of the rod side chamber 29r does not exceed the set pressure of the relief valve 393.

After that, when the injection piston 31 is advanced by the driving force of the electric drive unit 381 in the low speed injection, the hydraulic fluid in the rod side chamber 29r is maintained below the set pressure of the relief valve 393. If the pressure applied to the rod side chamber 29r by the compression cylinder 61 is equal to or higher than the set pressure of the relief valve 393, the pressure of the rod side chamber 29r is basically constant (set pressure) after the start of low-speed injection. Further, even if the pressure applied to the rod side chamber 29r by the compression cylinder 61 is smaller than the set pressure, it is compared with the case where the pressure of the rod side chamber 29r is the tank pressure at the start of low-speed injection, after the injection is started. The pressure rise in the rod side chamber 29r and the compression of the working fluid are reduced.

Then, when the high-speed injection is started, the hydraulic fluid is supplied to the head side chamber 29h, and the pressure increased by the injection piston 31 is applied to the rod side chamber 29r. However, since the pressure of the rod side chamber 29r was maintained at the set pressure of the relief valve 393 in the low speed injection, jumping may occur as compared with the case where the pressure of the rod side chamber 29r is the tank pressure in the low speed injection. Is reduced.

In this embodiment as well, as described in the second modification, the compression valve 67 may be left in the open state. The operation of the compression cylinder 61 in this case is as described in the second modification.

As described above, also in the present embodiment, the compression cylinder 61 having a pressure increasing function is provided, the first cylinder chamber 63e is connected to the rod side chamber 29r, and the hydraulic pressure device 328 supplies the hydraulic fluid to the third cylinder chamber 63g. Since it is possible, an advantageous effect is produced. For example, it is possible to suppress the pressure rise (pressure fluctuation) at the start of low-speed injection and stabilize the speed control by the electric drive unit 381.

Further, in the present embodiment, the injection device 309 includes an electric drive unit 381 that can drive the injection piston rod 35 with respect to the injection cylinder unit 29, and a rod side chamber when the pressure of the rod side chamber 29r exceeds a predetermined pressure. It has a relief valve 393 for discharging the hydraulic fluid from 29r.

Therefore, for example, the pressure fluctuation when the plunger 23 is advanced by the electric drive unit 381 can be reduced to stabilize the speed control.

Further, in the present embodiment, the injection device 309 supplies the hydraulic fluid 328 and the electric drive so as to advance the plunger 23 by the electric drive unit 381 after supplying the hydraulic fluid to the third cylinder chamber 63 g (low pressure chamber). Further, it has a control device 313 that controls the unit 381. That is, the control device 313 advances the compression cylinder control unit 313a that controls the hydraulic pressure device 28 (compression valve 67) so as to supply the hydraulic fluid to the third cylinder chamber 63g, and the plunger 23 after the control thereof. As described above, it has an electric control unit 313c for controlling the electric drive unit 381 (drive electric motor 383).

Therefore, for example, it is possible to apply pressure to the rod side chamber 29r in advance before driving the injection piston 31 by the electric drive unit 381 to more reliably stabilize the speed control by the electric control unit 313c from the start of injection. ..

Further, in the present embodiment, the control device 313 controls the electric drive unit 381 and the hydraulic pressure device 328 so as to supply the hydraulic fluid to the head side chamber 29h after the plunger 23 is advanced by the electric drive unit 381. .. That is, the control device 313 supplies the hydraulic fluid to the electric control unit 313c that controls the electric drive unit 381 (drive electric motor 383) so as to advance the plunger 23, and to the head side chamber 29h after the control thereof. It has an injection cylinder control unit 313b that controls the hydraulic pressure device 328 (injection valve 45).

Therefore, for example, the pressure of the rod side chamber 29r is maintained at the set pressure by the relief valve 393 while the low speed injection is performed by the electric drive unit 381, and the pressure of the rod side chamber 29r is set to the tank pressure. It is possible to reduce the risk of jumping when switching to injection.

<Modification example of compression cylinder>
8 (a) to 8 (c) show a modified example of the compression cylinder. The following compression cylinder may be applied to any of the first to third embodiments, but in the following description, the reference numerals of the flow paths of the first embodiment and the like are used.

The compression cylinder 61 shown in FIG. 8A is the same as the compression cylinder 61 of the first embodiment, as can be understood from the fact that the compression cylinder 61 shown in FIG. 8A has the same reference numerals as the compression cylinder 61 of the first embodiment for convenience. It has the shape of. However, unlike the first embodiment, the first cylinder chamber 63e is connected to the tank 37, and the second cylinder chamber 63f is connected to the eighth flow path 43H (rod side chamber 29r). The first cylinder chamber 63e may be open to the atmosphere without being filled with the hydraulic fluid.

Even in such a configuration, the pressure receiving area (S ₁₂ ) of the compression piston 65 (second piston portion 65b) in the third cylinder chamber 63g is the pressure receiving area of the compression piston 65 (second piston portion 65b) in the second cylinder chamber 63f. Since it is larger than the area (S ₁₁ ), the compression cylinder 61 has a pressure increasing action. That is, in this modification, the third cylinder chamber 63g is an example of the low pressure chamber, and the second cylinder chamber 63f is an example of the high pressure chamber. It is preferable that the pressure increasing ratio (S ₁₂ / S ₁₁ ) by the compression piston 65 is equal to or larger than the pressure increasing ratio (S ₄ / S ₃ ) by the injection piston 31 as in the embodiment.

As can be understood from the fact that the compression cylinder 501 shown in FIG. 8B has the same reference numerals as the compression piston 65 of the first embodiment and the first modification, the compression piston 65 is the first modification. In the above, the first cylinder chamber 63e is eliminated. That is, the first piston portion 65a extends outward from the compression cylinder portion 503. The pressure boosting ratio is the same as that of the first modification.

As can be understood from the fact that the compression cylinder 511 shown in FIG. 8C has the same reference numerals as the compression piston 65 of the first embodiment and the first modification, the compression piston 65 of the first embodiment In the above, the compression cylinder portion is separated into two parts. That is, the compression cylinder portion 513 according to the present modification has a first cylinder portion 513a into which the first piston portion 65a is inserted and a second cylinder portion 513b accommodating the second piston portion 65b.

A first cylinder chamber 513e is formed inside the first cylinder portion 513a, and an eighth flow path 43H (rod side chamber 29r) is connected to the first cylinder chamber 513e. The inside of the second cylinder portion 513b is divided into a second cylinder chamber 513f and a third cylinder chamber 513g by the second piston portion 65b. The second cylinder chamber 513f is connected to the tank 37, and the third cylinder chamber 513g is connected to the seventh flow path 43G (accumulator 41). The second cylinder chamber 513f may be open to the atmosphere.

Also in this modification, similarly to the first embodiment, the third pressure receiving area in the cylinder chamber 513g of the compression piston 65 (the second piston portion 65b) _{(S 2),} the compression piston 65 (first piston portion 65a) Since it is larger than the pressure receiving area (S ₁ ) in the first cylinder chamber 513e, the compression cylinder 511 has a pressure increasing action. The pressure increase ratio (S ₄ / S ₃ ) is the same as that of the first embodiment. The diameter (cross section) of the first cylinder chamber 513e is larger than, for example, the diameter (cross section, pressure receiving area) of the first piston portion 65a.

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. In the direct-coupled or separate type booster injection cylinder, the piston and the cylinder portion may be configured so that the diameter of the small diameter portion of the booster piston is smaller than the diameter of the injection piston.

The compression valve 67 may not be provided. For example, in the first embodiment, if the discharge of the hydraulic fluid from the rod side chamber 29r is prohibited before the start of injection, the compression piston 65 exerts pressure on the first cylinder chamber 63e even without the compression valve 67. Maintain the stopped state while granting. Then, after the speed valve 49 is opened, the compression cylinder 61 performs the same operation as that described in the second modification. The retreat of the compression piston 65 may be performed in the same manner as in the first embodiment, and then the speed valve 49 may be closed to prepare for the next cycle. Further, the compression valve is not limited to the check valve, and may be, for example, a switching valve or a pressure control valve.

The hydraulic pressure source capable of supplying the hydraulic fluid to the low pressure chamber of the compression cylinder is not limited to the accumulator or the pump. For example, the hydraulic pressure source may be one in which the piston and the cylinder portion accommodating the piston are relatively moved by an electric motor, and the hydraulic fluid is discharged from the cylinder chamber whose volume is reduced. The same applies to the hydraulic pressure source that is used for both supplying the hydraulic fluid to the head side chamber of the injection cylinder and supplying the hydraulic fluid to the low pressure chamber of the compression cylinder.

The hydraulic fluid in the rod side chamber may be returned to the head side chamber via a flow control valve (speed valve) instead of the tank. That is, a run-around circuit may be provided. The hydraulic device may have a meter-in circuit in addition to the meter-out circuit.

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 (for example, a compression cylinder) 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 seen from the low speed injection operation of the third embodiment, the compression cylinder preloads the rod concubine in a state where the meter out circuit is not functioning and a relief valve is provided. Contributes to suppressing the pressure rise at the start of low-speed injection.

From the embodiment, the following injection device that does not require a compression cylinder can be extracted.
An injection piston rod connected to a plunger that is slidable in a sleeve leading to the inside of the mold, an injection piston fixed to the injection piston rod, and an injection cylinder portion that slidably accommodates the injection piston. An injection cylinder having an injection cylinder portion, the inside of which is divided into a rod side chamber on the side where the injection piston rod extends by the injection piston and a head side chamber on the opposite side.
A hydraulic device capable of supplying hydraulic fluid to the head side chamber, and
An electric drive unit capable of driving the injection piston rod with respect to the injection cylinder unit,
Have and
The hydraulic device is an injection device having a relief valve that discharges a hydraulic fluid from the rod side chamber when the pressure in the rod side chamber exceeds a predetermined pressure.

1 ... Die casting machine, 9 ... Injection device, 21 ... Sleeve, 23 ... Plunger, 27 ... Injection cylinder, 28 ... Hydraulic device, 29 ... Injection cylinder part, 31 ... Injection piston, 29r ... Rod side chamber, 29h ... Head side chamber, 61 ... compression cylinder, 63 ... compression cylinder section, 63e ... first cylinder section (high pressure chamber), 63 g ... third cylinder chamber (low pressure chamber), 65 ... compression piston.

Claims (9)

An injection piston rod that is connected to a plunger that can slide inside the sleeve that leads to the inside of the mold,
An injection piston fixed to the injection piston rod and
An injection cylinder that slidably accommodates the injection piston,
A hydraulic device capable of supplying hydraulic fluid to the injection cylinder,
With
The injection cylinder has an injection cylinder portion that is partitioned into a rod side chamber on the injection side and a head side chamber on the opposite side of the injection piston.
The hydraulic device is connected to the head side chamber so as to be able to supply the hydraulic fluid.
A compression cylinder that increases the pressure of the hydraulic fluid is connected to the rod side chamber.
The compression cylinder
With a compression piston
A compression cylinder portion that slidably accommodates the compression piston and constitutes a low-pressure chamber and a high-pressure chamber with the compression piston interposed therebetween.
Have,
The pressure receiving area of the compression piston in the low pressure chamber is configured to be larger than the pressure receiving area of the compression piston in the high pressure chamber.
The high pressure chamber is connected to the rod side chamber, and the hydraulic fluid can be supplied to the low pressure chamber by the hydraulic device .
The pressure increasing ratio obtained by dividing the pressure receiving area of the compression piston in the low pressure chamber by the pressure receiving area of the compression piston in the high pressure chamber is the pressure receiving area of the injection piston in the head side chamber divided by the pressure receiving area of the injection piston in the rod side chamber. An injection device that is equal to or larger than the divided pressure boost ratio . The hydraulic pressure device is
A hydraulic pressure source capable of delivering hydraulic fluid and
A flow path connecting the hydraulic pressure source and the head side chamber,
Injection device according to claim 1 having a, a flow passage connecting the low-pressure chamber and the pressure source. It further has an electric drive unit capable of driving the injection piston rod with respect to the injection cylinder unit.
The injection device according to claim 1 or 2 , wherein the hydraulic device has a relief valve for discharging a hydraulic fluid from the rod side chamber when the pressure in the rod side chamber exceeds a predetermined pressure. The invention according to any one of claims 1 to 3 , further comprising a control device that controls the hydraulic fluid so as to supply the hydraulic fluid to the head side chamber after supplying the hydraulic fluid to the low pressure chamber. Injection device. The third aspect of claim 3 , further comprising a hydraulic device and a control device for controlling the electric drive unit so that the plunger is advanced by the electric drive unit after supplying the hydraulic fluid to the low pressure chamber. Injection device. The control device according to claim 3 or 5 , wherein the control device controls the electric drive unit and the hydraulic device so as to supply a hydraulic fluid to the head side chamber after the plunger is advanced by the electric drive unit. Injection device. An injection piston rod that is connected to a plunger that can slide inside the sleeve that leads to the inside of the mold,
An injection piston fixed to the injection piston rod and
An injection cylinder that slidably accommodates the injection piston,
A hydraulic device capable of supplying hydraulic fluid to the injection cylinder,
With
The injection cylinder has an injection cylinder portion that is partitioned into a rod side chamber on the injection side and a head side chamber on the opposite side of the injection piston.
The hydraulic device is connected to the head side chamber so as to be able to supply the hydraulic fluid.
A compression cylinder that increases the pressure of the hydraulic fluid is connected to the rod side chamber.
The compression cylinder
With a compression piston
A compression cylinder portion that slidably accommodates the compression piston and constitutes a low-pressure chamber and a high-pressure chamber with the compression piston interposed therebetween.
Have,
The pressure receiving area of the compression piston in the low pressure chamber is configured to be larger than the pressure receiving area of the compression piston in the high pressure chamber.
The high pressure chamber is connected to the rod side chamber, and the hydraulic fluid can be supplied to the low pressure chamber by the hydraulic device.
It further has a control device for controlling the hydraulic fluid so as to supply the hydraulic fluid to the head side chamber after supplying the hydraulic fluid to the low pressure chamber.
Injection device. The injection device according to any one of claims 1 to 7, 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 8.
A mold clamping device that clamps the mold and
An extruder that extrudes a molded product from the mold,
Molding machine that has.

Images