JP2009228706A - Impact pressure absorbing device of hydraulic control device, injection control circuit of injection device including the impact pressure absorbing device, and clamping control circuit of clamping device including the impact pressure absorbing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact pressure absorbing device releasing pressure so as not to generate surge pressure in a returning pipe returning to an oil tank when a servo valve that high speed controls a driving device of a hydraulic control device including an accumulator is switched, and to provide an injection control circuit or a clamping control circuit including the impact pressure absorbing device. <P>SOLUTION: The impact pressure absorbing having a bladder filled with atmospheric pressure and a coupling member in a hollow space comprises; a linear through-hole generally linearly communicating from an external pipe to the hollow space on the coupling member; a bending member positioned in the middle of the linear through-hole, and changing a direction of a flow of hydraulic fluid flowing into the hollow space to a direction which does not directly hitting the bladder; and a branch through-hole branching off from the linear through-hole to the external pipe in a generally right angle direction. The surge pressure generated in the returning pipe is temporary absorbed in the hollow space. The impact pressure absorbing device is provided in the middle of a depressed pipe provided adjacently to a supplying pipe of the injection control circuit or the clamping control circuit, and make full use of its function. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an impact pressure absorbing device that temporarily absorbs high pressure when hydraulic hydraulic fluid passing through a pipe of a hydraulic control device becomes transiently high in pressure. Further, the present invention is attached to a pressure relief piping line from the servo valve that controls the hydraulic cylinder to the oil tank, and absorbs the surge pressure of the hydraulic fluid generated in the pressure relief piping when the servo valve is switched. The present invention relates to an injection control circuit of an injection device including an impact pressure absorbing device and a mold clamping control circuit of a mold clamping device.

  In a hydraulic control device in which a servo valve is provided in the middle of a piping line from a hydraulic power source such as a hydraulic pump to a hydraulic cylinder, and the operation of the piston rod of the hydraulic cylinder is switched by the servo valve to control the drive, In order to speed up the operation, an accumulator is provided in the middle of the piping line between the hydraulic power source and the servo valve, and a large amount of high-pressure hydraulic fluid (hereinafter simply referred to as hydraulic fluid) accumulated in the accumulator is hydraulic cylinder. There is a hydraulic control device that supplies at once. Such a hydraulic control device is employed, for example, in an injection device of an injection molding machine, and the injection plunger is driven at high speed to fill the cavity in the mold device with plasticized molding resin in the injection cylinder device at high speed. .

  In a hydraulic control device for an injection molding machine including such an accumulator, the supply direction switching of the hydraulic oil supplied to the hydraulic cylinder and the flow rate control are performed with high response and high precision by a servo valve. Therefore, the timing of starting and completing the filling of the molten resin is switched to a high response, and the filling speed is controlled at high speed and high precision, for example, filling the molten resin to the end of a narrow cavity or overfilling in thin molding. It can be avoided. Therefore, such high-speed and high-precision filling control has become a molding technique that is indispensable for molding thin-walled precision molded products such as a recent light guide plate.

  However, since the rapid start-up of the injection start speed and the quick depressurization control of the filling pressure just before the completion of filling are performed near the limit of the switching performance of the servo valve, it occurs in the piping line at the time of the switching. The surge pressure has become more intense. For example, when supplying the hydraulic oil to the injection side oil chamber (usually the head side oil chamber) at once by switching the servo valve rapidly at the start of filling, the piping line leading to the injection side oil chamber and the reverse side oil chamber ( Surge pressure was generated in any piping line that normally leads to the rod side oil chamber. Moreover, when the filling pressure of the injection side oil chamber was rapidly released along with the completion of the filling of the resin, the filling pressure generated a surge pressure in the supply piping line.

  Therefore, Patent Document 1 (Japanese Patent Publication No. 7-4846) has been proposed to solve the above problems. The hydraulic control device for an injection molding machine in that document is a device provided with a small pressure accumulator in both a supply-side pressure oil pipe and a return-side pressure oil pipe in addition to an auxiliary power accumulator for injection driving. The hydraulic control device includes a hydraulic cylinder device (injection cylinder) for advancing and retracting an injection screw, a servo valve provided between the hydraulic cylinder device and the hydraulic pump, and a servo valve between the servo valve and the pump, as in the past. In addition to the supply-side pressure oil piping, the return-side pressure oil piping between the servo valve and the oil tank, and the auxiliary power accumulator in the middle of the supply-side pressure oil piping, the supply-side pressure oil piping and return A small pressure accumulator that absorbs high pressure is provided in the middle of the side pressure oil piping. These small pressure accumulators are attached as close as possible to the injection cylinder.

  In these hydraulic control devices, the oil chambers before and after the hydraulic cylinder device are connected to one servo valve, and a hydraulic oil supply line and a return pressure oil pipe are connected to the primary side of the servo valve. Pair connected. A small pressure accumulator is provided in each of these pressure oil pipes. In particular, in the pressure oil pipe for supply, the auxiliary power pressure accumulator and the small pressure accumulator are arranged in series. With such a configuration, at the start of filling, the impact pressure generated in the supply pressure oil piping and the impact pressure generated in the return pressure oil piping are absorbed by the cooperative action of the respective small pressure accumulators. Further, when filling is completed, pressure hunting due to the impact pressure caused by blocking the high-speed pressure oil flow, which is likely to occur in the supply pressure oil piping, is mainly absorbed by the small pressure accumulator of the supply pressure oil piping. Such a hydraulic control device is also disclosed in Patent Document 2 (Japanese Patent No. 2591885).

  However, these documents do not describe the pressure accumulator itself. Therefore, the accumulator is a conventional standard one.

  The conventional pressure accumulator is a Prada-type accumulator shown in FIGS. In the figure, the upper half of the center line in FIG. 6 shows the state where the high pressure gas and hydraulic oil are not filled in the prada and the hollow space, and the lower half of the drawing shows the high pressure gas and the operation in the prada and the hollow space. The state where oil is filled is shown. FIG. 7A shows a state where the high pressure gas is filled in the prada, but no hydraulic oil is accumulated in the hollow space, and FIG. 7B shows that the high pressure gas is filled in the prada. This shows a state in which hydraulic oil pressure accumulation has just started in the hollow space.

  The Prada accumulator 1 includes a hollow container 2 in which both ends of a cylindrical tube are squeezed into a substantially hemispherical shape, a high-pressure gas sealing member 3 attached to one end thereof, and a prada 4 in which high-pressure gas is sealed via the member. And a connecting member 5 having a through hole 5a that is attached to the other end and communicates the hollow space 2a of the hollow container and an external pipe (not shown). And the poppet valve 6 which opens and closes the through-hole 5a of the connecting member is provided in a state where it is elastically biased toward the hollow space 2a by the compression coil spring 7. More specifically, the poppet valve 6 is attached to the center position of the partition wall 5b that partitions the through-hole 5a of the connecting member 5 in the middle, and the compression coil spring 7 is attached around the axis of the poppet valve. A plurality of sub through holes 5c are formed at equal intervals on the circumference outside the poppet valve 6 mounting hole of the partition wall 5b, and communicate with the through holes 5a in a straight line. In addition, a bush member 8 corresponding to a different diameter bush is attached as necessary to enable connection according to the pipe diameter of the external pipe. The connecting member 5 and the hollow container 2 are fixed in a liquid-sealed state by a screw member 9a outside the container, a locking member 9b inside the container, and a seal member 10 such as an O-ring between them.

  With such a configuration, the accumulator 1 is configured so that the prada 4 expanded by filling with the high-pressure gas contracts like the lower half of FIG. 6 by the working oil, and the working oil enters the hollow space 2 a between the prada 4 and the hollow container 2. Is accumulated. When the accumulator 1 releases the hydraulic oil, the high-pressure hydraulic oil is pushed out from the through hole 5a to the external pipe at a high speed and in a large amount by the high repulsive pressure of the contracted prada 4.

  The accumulator 1 having this configuration has the following characteristics. One of the features is that the thickness of the valve portion 6a of the poppet valve 6 is thin. As a result, when the prada 4 filled with the high-pressure gas and expanded is pressed against the poppet valve 6 as shown in FIG. 7A, the prada is deformed easily along the poppet valve 6 and the local damage is caused. Is avoided. Since the valve portion 6a of the poppet valve 6 is configured to block like a partition with respect to the flow direction of the hydraulic oil, there is one aspect that causes flow resistance when the hydraulic oil flows into the accumulator 1. Since the role of No. 1 exclusively releases a large amount of hydraulic oil at high speed, its configuration has not been a problem in the past. The other feature is that the compression coil spring 7 is present in the flow path through which the hydraulic oil passes, whereby the poppet can be opened and closed with a simple configuration. Another characteristic is that, as a matter of course, the through holes 5a and 5c through which the hydraulic oil enters and exits are formed in a straight line so that the hydraulic oil can pass through with as little resistance as possible.

Japanese Patent Publication No. 7-4846 Japanese Patent No. 2591885

  However, the inventor of the present application considers that the countermeasure for eliminating the surge pressure of the return pipe in the above-mentioned patent document is insufficient as a solution to the problem of the present inventor. The problem that the inventor of the present application focuses on is to eliminate the surge pressure generated by the high-pressure hydraulic oil that returns to the return pipe especially when the servo valve is switched. This is because it removes the adverse effects on the tank. On the other hand, the countermeasure of the above document is to prevent shock pressure or pressure hunting that makes the first or immediately after the operation unstable when the hydraulic cylinder device operates in accordance with the switching of the servo valve. This is a measure that emphasizes the stabilization of operation. The difference appears in the configuration in which a small pressure accumulator is provided in each of the supply and return pressure oil pipes. In addition, since the above measures are desirable to place the accumulator close to the servo valve and to place them as close to the injection cylinder device as possible, it is also unsatisfactory to make a large area around the injection device. It is. These means that there is a limit even if the conventional pressure accumulator is provided in the pipe as it is.

  Therefore, the inventors of the present invention returned and compared the conventional function required for the Prada accumulator and the function for absorbing the surge pressure. And, the inventor of the present application is naturally inferior in the function that the conventional accumulator allows the hydraulic oil to flow in rapidly, and the surge pressure absorbing accumulator is required to have the function of flowing the hydraulic oil without resistance. However, I thought that it was necessary to reflect in the structure of the accumulator that the function of flowing a large volume in volume was not required. In addition, since the inventor of the present application makes the depressurization of the return pipe particularly problematic, the gas pressure of the accumulator prada is about atmospheric pressure, and in this case, the prada does not expand until it contacts the poppet. We thought that the omission of the conventional movable poppet should be considered.

  For more details, the inventors of the present application considered the above-described characteristics of the poppet valve 6 as a problem to be solved. That is, as for the feature that the valve portion 6a blocks the flow of hydraulic oil like a partition, when the partition shape absorbs the surge pressure, the smooth flow of the hydraulic oil into the hollow container is remarkably prevented. is there. A feature of the presence of the compression coil spring 7 is that the spring acts as a resistance against the high-speed flow of hydraulic oil and increases the surge pressure on the external piping side. The feature that the through holes 5a and 5c through which the hydraulic oil enters and exits is formed in a straight line is that the hydraulic oil that has once flowed into the accumulator is once again released to the external pipe side, thereby inhibiting the inflow.

  Moreover, the inventor of the present application has recognized that the oil tank breakage accidents that frequently occur in this type of hydraulic control device are caused by this surge pressure. For example, in the hydraulic control device of an injection molding machine, the high-pressure hydraulic oil in the injection-side oil chamber rapidly flows into the return pipe and is finally discharged into the oil tank in the hydraulic control device of the injection molding machine. Sometimes the oil tank collides violently and damages the oil tank. This occurred particularly when the surge pressure in the return pipe could not be sufficiently released when the injection pressure was lowered immediately after completion of the injection. Therefore, the present inventor has recognized that in order to solve this problem, a hydraulic control circuit for more thorough decompression is required, which is different from the hydraulic control device of the above-mentioned patent document. In particular, in the control circuit composed of a set of hydraulic oil supply piping and return piping for one servo valve as described above, it was considered that there was a limit to how the pressure accumulator was incorporated. The inventor of the present application investigated other prior arts from the above viewpoint, but could not find anything that seemed relevant.

  Therefore, the present invention proposes an impact pressure absorbing device itself that can quickly accommodate a high surge pressure generated in a return pipe without resistance. Moreover, the present invention proposes an injection control circuit for an injection device of an injection molding machine in which the impact pressure absorbing device is incorporated in a decompression pipe, and a mold clamping control circuit for a mold clamping device.

  In order to solve the above problems, an impact pressure absorbing device according to the present invention supplies hydraulic oil accumulated in an accumulator from a servo valve to a hydraulic drive device to control the hydraulic control device, from the servo valve to the oil tank. Shock pressure absorption provided in the middle of the return pipe line, and having a hollow container for temporarily flowing high-pressure hydraulic oil generated transiently into the return pipe as the servo valve is switched from the return pipe In the device, the hollow container has a connecting member that communicates the return pipe line and the hollow space in the hollow container on the other side thereof with a prada in which atmospheric pressure is sealed on one side. The connecting member communicates with the return pipe connected to the servo valve in a substantially straight line and opens into the hollow space, and is positioned near the hollow space side opening of the straight hole. In the hollow space A deflecting member that changes the direction of the incoming hydraulic oil flow in a direction that does not directly hit the prada, and a branched through hole that branches from the straight through hole in a substantially right angle direction and is connected to a return pipe that leads to the oil tank. Configured as follows.

  The injection control circuit of the injection device including the impact pressure absorbing device includes an injection hydraulic cylinder of the injection device in the hydraulic control device including the impact pressure absorbing device, and an injection-side oil chamber of the injection hydraulic cylinder includes the injection hydraulic cylinder. A servo valve and a retreat side oil chamber are connected to different control valves, and a piping line connected to the primary side of the servo valve includes a supply piping line for supplying hydraulic oil from the accumulator, and the oil tank. A pressure relief piping line for returning hydraulic fluid, and a first pressure relief piping to the servo valve of the pressure relief piping line is connected to the linear through hole of the impact pressure absorbing device, and the pressure relief piping When the injection pressure is rapidly increased during filling of the molding resin by connecting the second pressure release pipe leading to the oil tank of the line to the branch through hole of the impact pressure absorbing device, the servo valve Suddenly When the hydraulic oil is rapidly supplied from the accumulator to the injection-side oil chamber and the injection pressure is rapidly released immediately after the completion of filling, the servo valve is rapidly switched to increase the high pressure of the injection-side oil chamber. The hydraulic oil is rapidly accommodated in the impact pressure absorbing device from the straight through hole, and then the hydraulic oil in the impact pressure absorbing device is discharged from the branch through hole when the pressure of the second pressure release pipe is lowered. It is configured to return to the oil tank.

  The mold clamping control circuit of the mold clamping device including the impact pressure absorbing device includes a mold clamping hydraulic cylinder of the mold clamping device in the hydraulic control device including the impact pressure absorbing device, and the mold of the mold clamping hydraulic cylinder is included. A supply line for supplying hydraulic oil from the accumulator is connected to the servo valve, the mold opening side oil chamber is connected to a different control valve, and a piping line connected to the primary side of the servo valve. And a pressure relief piping line that returns the hydraulic oil to the oil tank, and a first pressure relief piping that reaches the servo valve of the pressure relief piping line is connected to the linear through hole of the impact pressure absorbing device. And when the second pressure release pipe reaching the oil tank of the pressure release pipe line is connected to the branch through hole of the impact pressure absorbing device, when the mold clamping force is rapidly increased during mold clamping, The servo valve is rapidly switched to When the hydraulic oil is rapidly supplied from the accumulator to the mold clamping side oil chamber and the mold clamping force is rapidly released after mold clamping, the servo valve is switched quickly to supply the high pressure hydraulic oil in the mold clamping side oil chamber. When the pressure of the second pressure release pipe is lowered from the straight through hole to the shock pressure absorbing device, the hydraulic oil in the shock pressure absorbing device is discharged from the branch through hole to the oil tank. Configured to return.

  According to the impact pressure absorbing device of the present invention described above, even if surge pressure is generated in the return pipe line connected to the impact pressure absorbing device, the high-pressure hydraulic oil causes the straight through hole of the connecting member of the impact pressure absorbing device to It passes through the hollow container at a stretch with a small resistance, and the surge pressure is rapidly absorbed. At this time, the deflecting member avoids direct hitting of the hydraulic oil to the prada and does not damage the prada. In addition, since the amount of hydraulic oil that generates surge pressure is usually small and the gas pressure in the prada is as small as atmospheric pressure, the increase in repulsive force due to the contraction of the prada is small, so that the hydraulic oil flows into the hollow space. Is not disturbed. Then, when the pressure in the return pipe subsequently decreases, the hydraulic oil in the impact pressure absorbing device returns from the branch through hole to the return pipe line at a low pressure.

  Further, according to the injection control circuit of the injection device of the present invention, the injection side oil chamber of the injection hydraulic cylinder is connected to the servo valve, and the reverse side oil chamber is connected to a different control valve, on the primary side of the servo valve. The connected piping line includes a supply piping line that supplies hydraulic oil from the accumulator, and a pressure relief piping line that returns the hydraulic oil to the oil tank, and the first pressure line leading to the servo valve of the pressure relief piping line A pressure relief pipe is connected to the straight through hole of the shock pressure absorbing device, and a second pressure release pipe leading to the oil tank of the pressure relief pipe line is connected to the branch through hole of the shock pressure absorbing device. Is done. So, first, the depressurization piping line serves as a dedicated depressurization piping line for the high-pressure side injection-side oil chamber, and is servoed to the supply piping line that supplies hydraulic oil to the same high-pressure side injection-side oil chamber. Since the valve is connected so that it can be switched, when the servo valve is switched just before the completion of injection, the high-pressure hydraulic fluid that was filling the injection-side oil chamber just before filling is released from the injection-side oil chamber. Rapid depressurization is carried out by moving to the piping line and the impact pressure absorbing device at once, and dropping the injection pressure at once. Second, since the impact pressure absorbing device communicates with the pressure release piping line through a straight through hole and a branch through hole, when the servo valve is switched just before the injection is completed, Flows into the shock pressure absorber via a straight through hole, the injection pressure drops all at once, and when the pressure in the second pressure release pipe decreases, the hydraulic oil in the shock pressure absorber is It returns to the oil tank from the branched through hole. Therefore, the surge pressure generated in the pressure relief piping line can be minimized, and the oil tank can be prevented from being damaged. Thirdly, since the injection side oil chamber and the reverse side oil chamber of the injection hydraulic cylinder are cooperatively controlled by the servo valve and the different control valve, the servo valve and the different control are controlled. Valves can be optimally selected according to the required functional performance capacity.

  According to the mold clamping control circuit of the mold clamping apparatus of the present invention, the mold clamping side oil chamber of the mold clamping hydraulic cylinder is connected to the servo valve, and the mold opening side oil chamber is connected to a different control valve. A piping line connected to the primary side of the valve includes a supply piping line that supplies hydraulic oil from the accumulator and a pressure relief piping line that returns the hydraulic oil to the oil tank, and the servo valve of the pressure relief piping line A first pressure relief pipe connected to the straight through hole of the impact pressure absorber, and a second pressure relief pipe leading to the oil tank of the pressure relief line is a part of the impact pressure absorber. Connected to the branch through hole. So, firstly, the pressure release piping line is a dedicated pressure release piping line for the high pressure side clamping chamber oil chamber, and the supply piping line that supplies hydraulic oil to the same high pressure side clamping chamber oil chamber. Therefore, when the servo valve is switched at an appropriate timing after the main mold is clamped, the high-pressure hydraulic fluid that has filled the injection side oil chamber by the main mold clamping is Rapid depressurization is performed in which the mold clamping force is reduced at once by flowing into the pressure relief piping line and the impact pressure absorbing device from the side oil chamber. And secondly, since the impact pressure absorbing device communicates with the depressurization piping line through a straight through hole and a branch through hole, when the servo valve is switched at an appropriate timing after the mold clamping, When high-pressure hydraulic fluid flows from the mold clamping side oil chamber into the shock pressure absorbing device through the straight through holes at once, the mold clamping force drops all at once, and then the pressure in the second depressurization pipe decreases. The hydraulic oil in the impact pressure absorbing device is returned to the oil tank from the branch through hole. Therefore, the surge pressure generated in the depressurizing pipe can be minimized, and the oil tank can be prevented from being damaged. Third, since the mold clamping side oil chamber and the mold opening side oil chamber of the mold clamping hydraulic cylinder are controlled in cooperation by the servo valve and the different control valve, the servo valve and the Different control valves can be optimally selected according to the required functional performance capacity.

  Hereinafter, the impact pressure absorbing device 11 of the present invention will be described with reference to FIGS. The configuration of the impact pressure absorbing device 11 includes a portion common to a conventional Prada type accumulator. Therefore, the same members as those in the prior art are denoted by the same reference numerals as those of the conventional members in FIG. FIG. 1 is a partial cross-sectional view of an impact pressure absorbing device, and the upper half of the center line shows a state where the gas is filled in the prada but no hydraulic oil is accumulated in the inner space. The half figure shows a state where the prada is filled with gas and the hydraulic oil is accumulated in the internal space. FIG. 2 is an enlarged cross-section in an assembled state of the connecting member of the impact pressure absorbing device, and FIG. 3 is an enlarged cross-section in an exploded state of the connecting member of the impact pressure absorbing device.

  The impact pressure absorbing device 11 of the present invention includes the gas sealing member 3 and the prada 4 on one side of the hollow container 2 as usual, but on the other side, the hollow space 2a of the hollow container 2 and external piping ( The connecting members 15 and 16 are provided for communication with each other. These connecting members include a first connecting member 15 and a second connecting member 16, a first through hole 15 a is formed in the first connecting member 15, and a second through hole is formed in the second connecting member 16. A hole 16a is formed. The second connecting member 16 is formed with a branched through hole 16b that branches in a substantially perpendicular direction to the second through hole 16a and is connected to another external pipe. Further, a partition wall 15b is formed on the side of the first connecting member 15 facing the hollow space 2a, and a sub through hole 15c and a deflecting member 15d are formed in the partition wall 15b. That is, the deflecting member 15d is integrally formed as a member protruding to the hollow space 2a side at the center position of the partition wall, and a plurality of sub through holes are provided on the circumference arranged at equal intervals outside the center of the partition wall. 15c is formed. Thus, the connecting members 15 and 16 are linear through holes composed of the sub through holes 15c, the first through holes 15a, and the second through holes 16a that linearly communicate the hollow space 2a and the external pipe, A branched through hole 16b branched from the straight through hole in a substantially right angle direction and connected to an external pipe.

  More specifically, the first connecting member 15 and the hollow container 2 are liquid-tightly connected via the conventional screw member 9a, the locking member 9b, and the seal member 10. As shown in FIG. 3, the first connecting member 15 and the second connecting member 16 are screwed together by, for example, a female screw portion 15e and a male screw portion 16c, and are connected in a liquid-sealed state by a packing 17 such as an O-ring. The The second connecting member 16 is screwed to the external pipe via a screw portion 16d formed in the second through hole 16a and a screw portion 16e formed in the branch through hole 16b. The screw portion is formed as a female screw in the illustrated example, but may be a male screw. As shown in FIG. 2, the baffle member 15d is formed so as to protrude toward the hollow space 2a at the center position of the partition wall 15b, and a hook-shaped member 15f is formed at the tip of the hollow space side. The flange-shaped member 15f is provided at a position close to the opening of the sub through hole 15c on the hollow space 2a side, and does not cause the flow of the hydraulic oil flowing into the hollow container 2 from the sub through hole 15c to directly hit the pradder 4. Change direction. However, the conical surface on the side of the sub-through hole 15c of the flange-shaped member 15f, that is, the deflecting surface 15g, has an inclination angle of the deflecting member 15d so that the flange-shaped member 15f is not as resistant as possible to the flow of the hydraulic fluid. It is formed so as to intersect with the central axis at approximately 45 °. Therefore, it is avoided that much of the flowing hydraulic oil flows near the inner wall of the hollow container 2 and directly collides with the prada 4.

  In such an impact pressure absorbing device 11, the gas sealed in the prada 4 is boosted only to about atmospheric pressure. Therefore, as shown in the upper half of FIG. 1, even if the prada 4 is expanded, it does not interfere with the deflecting member 15d. Therefore, even if the deflecting member 15d is a fixing member protruding into the hollow container 2, no matter what. There is no hindrance. Note that adjusting the gas pressure sealed in the prada 4 to about atmospheric pressure means that when the gas is injected from the high-pressure gas cylinder into the gas sealing member 3, the gas pressure is reduced from the sealing plug if necessary for a short time. This is done by unplugging.

  According to the impact pressure absorbing device 11 described above, even if a surge pressure is generated on the connected external pipe side, the hydraulic oil is straight in the second through hole 16a, the first through hole 15a, and the sub through hole 15c. The shock pressure absorbing device 11 absorbs the surge pressure by passing through the through-holes and flowing into the hollow container 2. At this time, the straight through holes are straight, there is no coil spring for increasing the flow resistance attached to the conventional poppet, and the deflecting surface 15g of the deflecting member 15d is like the valve portion of the conventional poppet valve. Therefore, the impact pressure absorbing device 11 allows high-pressure hydraulic oil to flow in rapidly and without resistance. In addition, the contraction of the prada 4 is limited and its repulsive force increases due to the gas pressure in the prada 4 being as small as atmospheric pressure and the volume of hydraulic oil usually being small when a surge occurs. There is hardly anything. As a result, the pressure increase in the hollow space 2a does not occur so much, and therefore the inflow of hydraulic oil is hardly inhibited. When the pressure of the external piping is reduced, the relatively small repulsive pressure of the prada 4 releases the hydraulic oil from the branch through hole 16b at a low pressure. In addition, the pressure of the external pipe on the branch through hole 16b side communicating with the oil tank side is lower than the pressure on the straight through hole side external pipe.

  The above impact pressure absorbing device 11 may be incorporated in an injection control circuit of an injection device of an injection molding machine. The injection apparatus may be at least an apparatus in which the injection apparatus is hydraulically controlled, but is preferably a pre-plastic injection apparatus as shown in FIG.

  Reference numeral 20 denotes a pre-plastic injection device, which includes a pre-plastic device 21 that plasticizes a molding resin, and an injection cylinder device 22 that injects the plasticized resin into a mold cavity (not shown) by a plunger 23. The plunger is driven by the piston 25 of the injection hydraulic cylinder 24. Therefore, the head side oil chamber of the injection hydraulic cylinder 24 is connected to the injection control circuit 30 so that it becomes the injection side oil chamber 24a for moving the piston 25 forward, and the rod side oil chamber becomes the reverse side oil chamber 24b for moving the piston 25 backward. Is done. In such a pre-plastic injection device 20, since the plunger 23 is shorter than the screw of the in-line screw injection device, high-speed filling control of molten resin and prevention of sudden rise in filling pressure at the completion of filling are controlled with high response and precision. it can.

  With such a pre-plastic injection device 20 (hereinafter simply referred to as an injection device), particularly when thin precision molding such as light guide plate molding is injection-molded, the filling performance of the molten resin into the mold cavity and the shape accuracy of the molded product are improved. In order to improve dimensional accuracy and to eliminate residual distortion of molded parts, injection control is required to rapidly increase the initial filling start speed or to quickly release the filling pressure at the moment of filling completion. It is done. Therefore, an injection control circuit 30 as shown in FIG. 4 including an accumulator and the impact pressure absorbing device of the present invention is employed as the injection control circuit of the injection device. Note that the hydraulic control circuit for the driving device other than the injection cylinder device 22, for example, a drive device such as a screw rotation motor of the pre-pla device 21 is the same as the conventional one, and the description thereof is omitted.

  First, the control circuit for moving the plunger 23 forward at high speed with the hydraulic oil of the accumulator 33 includes a supply piping line from the hydraulic pump 31 through the servo valve 32 to the injection side oil chamber 24a of the injection hydraulic cylinder 24. The piping lines branch from the supply lines P1, P2 from the hydraulic pump 31 to the servo valve 32, the supply line P3 from the servo valve 32 to the injection side oil chamber 24a, and between the supply line P1 and the supply line P2. The charge line C communicates with the accumulator 33. The supply line P2 is provided with a pilot operation check valve 34, which opens when the pilot pressure is applied by a switching valve (not shown) from the direction of the circle A shown in the figure, and is accumulated in the accumulator 33. The supplied hydraulic oil is supplied to the servo valve 32 from the supply line P2. A check valve 37 is provided in the supply line P1, and the backflow of the hydraulic oil in the accumulator 33 to the oil tank 35 is prevented. On the other hand, as the piston 25 moves forward, the piping line that returns the working oil from the reverse side oil chamber 24b to the oil tank 35 includes the line B between the reverse side oil chamber 24b and the direction switching valve 36, and the oil from the direction switching valve 36 to the oil. The tank line T extends to the tank 35.

  In contrast to the control circuit for moving the plunger 23 forward, the control circuit of the present invention returns the high-pressure hydraulic oil in the injection-side oil chamber 24a from the supply line P3 to the oil tank 35 so that it can be switched by the servo valve 32. With line. That is, it is a pressure relief piping line provided for supply lines P1, P2 connected to the same injection side oil chamber 24a by a servo valve 32 so as to be switchable. The depressurization line includes the impact pressure absorbing device 11 of the present invention in the middle, the first depressurization pipe R1 from the impact pressure absorbing device 11 to the servo valve 32, and the shock pressure absorbing device 11 to the oil tank. Up to 35 second pressure release pipes R2. The first pressure release pipe R1 communicates with a second through hole 16a (see FIG. 2) as a straight through hole of the impact pressure absorbing device 11, and the second pressure release pipe R2 is connected to the impact pressure absorbing device 11. It communicates with the branch through hole 16b (see FIG. 2). As described above, the impact pressure absorbing device 11 has an enclosed gas pressure of about atmospheric pressure, and is superior to the conventional product in the capability of flowing hydraulic oil. Further, the amount of hydraulic oil that flows into the impact pressure absorbing device 11 for depressurization is such that when the filling operation is almost completed and the forward movement of the plunger 23 is about to stop, the hydraulic oil stops from the high-speed flow state. Since it is a thing when the flow direction of hydraulic oil reverses trying to be in a state, it is few in quantity. Therefore, the impact pressure absorbing device 11 absorbs the injection pressure of the injection side oil chamber 24a, which rapidly rises upon completion of filling, from the first depressurization pipe R1 to the internal space 2a quickly and without resistance. Regarding the volume of the impact pressure absorbing device 11, for example, in an injection device whose outer shape of the injection plunger 23 is φ28 mm, the amount of hydraulic oil flowing into the impact pressure absorbing device 11 is about 200 cc. Therefore, the container capacity of about 5L can be used.

  On the other hand, the piping line of the control circuit for retreating the plunger 23 includes a supply line P1, a supply line P4 branched from the supply line P1 and connected to the direction switching valve 36, and the direction switching valve 36 and the backward oil chamber 24b. It consists of a line B in between. The pipeline for releasing hydraulic oil from the injection-side oil chamber 24a as the plunger moves backward is a line A branched from the supply line P3, and a tank line T that communicates the direction switching valve 36 and the oil tank 35. .

  By the way, a piping line that supplies hydraulic oil to the injection-side oil chamber 24a and a piping line that releases hydraulic oil from the reverse-side oil chamber 24b are controlled by different control valves of the servo valve 32 and the direction switching valve 36. This is because the supply lines P1 and P2 and the pressure relief pipes R1 and R2 are provided on the primary side of the servo valve 32 as described above. That is, the depressurization piping line is provided as one piping line for extracting hydraulic oil from the high-pressure side injection-side oil chamber 24a with respect to the other supply piping line that supplies the operating oil to the injection-side oil chamber 24a. Because. Thus, in the injection hydraulic cylinder 24, another direction switching valve 36 is connected to the other reverse side oil chamber 24b, and injection filling control is performed by the cooperative control of the servo valve 32 and the direction switching valve 36. Such a configuration makes it possible to optimally select the servo valve 32 and the direction switching valve 36 in accordance with the required functional performance capacity. Actually, each control valve may be configured as described below, for example. This is advantageous when optimizing each control valve, particularly when performing high speed injection and rapid depressurization in a large mold clamping device.

  First, the servo valve 32 employs a linear servo valve driven by a linear motor that switches the piping line with high speed and high response and precisely controls the flow rate. The servo valve 32 has three positions for switching the connection direction of the four piping ports depending on the position of a valve spool (not shown), and each position is described next. The direction switching valve 36 employs the following simple single solenoid switching valve.

  More specifically, the servo valve 32 and the direction switching valve 36 are preferably connected to the above-described piping line as follows. First, the two ports A and B of the servo valve 32 are collectively connected to the supply line P3. In this case, when the piping port connection position of the servo valve 32 is offset to the a side and the two ports A and B communicate with each other, the supply line P2 and the supply line P3 use the two ports A and B. And communicate. Therefore, the hydraulic oil from the accumulator 33 can pass through the servo valve 32 in a large amount and stably. In addition, at least one of the two ports A and B at the neutral switching position of the servo valve 32 is configured to communicate with the T port, and the communication from the transient state where the a side offset position is switched to the b side offset position is established. Is started so that the switching can be speeded up. Next, the directional switching valve 36 has two positions: a piping port connection position when the solenoid b is excited and a piping port connection position when the spring is returned, and the spring return position of the valve is the P port. It is preferable to be configured at a single-flow piping port connection position that does not communicate with the A port.

  For example, in the case of an injection device having an outer shape of the injection plunger 23 of φ28 mm and an injection stroke of about 130 mm, the accumulator 33 is selected to have a capacity of about 20 L so that the maximum pressure of the accumulated hydraulic oil is about 17 MPa. The enclosed gas pressure is adjusted to about 11 MPa. Then, the pressure of the hydraulic oil in the accumulator 33 is detected by the pressure sensor 38 and sent to the control device of the injection molding machine. Thus, when the pressure drops, the direction switching valve 36 is de-energized to block the supply line P4 and the pilot pressure of the pilot operation check valve 34 is stopped to block the supply line P2, and then the pump 31 is driven. Then, the hydraulic oil is accumulated in the accumulator 33. The hydraulic oil in the accumulator 33 is opened and depressurized by the open / close valve 39 in the line D at rest or the like.

  Although not shown in the figure, the injection control circuit 30 is appropriately provided with a relief valve and a relief pipe, a drain pipe, etc. extending from the relief valve to the oil tank 35 as in the prior art. The pump 31 is a variable flow type pump such as an electromagnetic proportional flow rate control pump.

  The injection control of the injection cylinder device 22 is performed as follows by the injection control circuit 30 described above. The injection control is mainly explained by high-speed injection control that is performed when compression molding thin precision molded products and the like, and rapid depressurization control that rapidly lowers the filling pressure immediately after the completion of filling.

  First, filling control is performed after a conventionally known metering is performed. At the start of filling, the pilot check valve 34 is opened, and the piping port connection position of the servo valve 32 is controlled to be offset to the a side. Therefore, the P port of the servo valve 32 and the two ports A and B communicate with each other, and the hydraulic oil in the accumulator 33 flows from the line C to the supply line P2, the servo valve 32, and the supply line P3. 24a. At this time, the solenoid b of the direction switching valve 36 is controlled to be non-excited, the line A is blocked, the line B and the tank line T communicate with each other, and the hydraulic oil in the backward oil chamber 24b is transferred to the oil tank 35. Return. In this way, by controlling the flow rate of the hydraulic oil supplied from the servo valve 32 to the supply line P3 in a large amount and at once, the forward movement of the plunger 23 is controlled at a high speed, and high-speed injection control for rapidly increasing the injection speed is realized. The At this time, the filling pressure generated in the molten resin in the injection cylinder device becomes an appropriate resistance to stabilize the forward movement of the plunger 23.

  Next, depressurization control is performed to release the high pressure in the injection-side oil chamber 24a to the oil tank 35 at the moment of completion of high-speed filling or immediately before filling. For this reason, the piping port connection position of the servo valve 32 is offset to the b side, the two ports A and B communicate with the T port, and the supply line P3 communicates with the first pressure relief piping R1 and the injection side oil. The chamber 24a communicates with a second through hole 16a as a straight through hole of the impact pressure absorbing device 11. Then, the high-pressure hydraulic oil in the injection-side oil chamber 24a flows from the first pressure release pipe R1 into the impact pressure absorbing device 11 with high response and rapidly, and the injection pressure in the injection-side oil chamber 24a is depressurized all at once. Is done. At this time, the solenoid b is controlled to be non-excited by the direction switching valve 36, the connection between the line B and the tank line T is ensured, and the communication between the backward oil chamber 24b and the oil tank 35 is ensured. In addition, the second through hole 16a of the impact pressure absorbing device 11 and the first pressure releasing pipe R1 communicate with each other in a straight line, and the branch through hole 16b of the impact pressure absorbing device 11 and the second pressure releasing pipe R2 are connected. Since it communicates in a branched state from the straight line, the high-pressure hydraulic oil is accommodated exclusively from the first pressure relief pipe R1 and does not flow out to the second pressure relief pipe R2 side. Then, when the pressure in the second pressure release pipe R2 subsequently decreases, the shock pressure absorber 11 returns the hydraulic oil to the oil tank 35 at a low pressure. Thus, the impact pressure absorbing device 11 not only releases the high pressure in the injection side oil chamber 24a just before the filling is completed, but also generates surge pressure in the first pressure release pipe R1 and the second pressure release pipe R2. This prevents the oil tank 35 from being damaged as much as possible to realize a quick depressurization control of the injection pressure. Of course, this effect is not achieved under the condition that the servo valve 32 and the impact pressure absorbing device 11 are arranged near the injection device.

  Thereafter, holding pressure control is performed as necessary, and the following plasticizing measurement is performed. However, since these are conventional processes, the description thereof is omitted. Then, a known suck-back operation is performed to prevent the resin leakage from the tip of the injection nozzle by slightly retracting the plunger 23 after completion of the measurement. At this time, the solenoid b of the direction switching valve 36 is excited to connect the supply line P4 to the line B, and the line A is connected to the tank line T to supply hydraulic oil to the backward oil chamber 24b and injection side oil. The hydraulic oil in the chamber 24 a is returned to the oil tank 35.

  On the other hand, the impact pressure absorbing device 11 of the present invention may be incorporated in a mold clamping control circuit of a mold clamping device of an injection molding machine. The mold clamping device is preferably a hybrid mold clamping device 40 as shown in FIG. 5 that performs mold opening and closing electrically and mold clamping is hydraulic.

  The hybrid mold clamping device 40 (hereinafter simply referred to as a mold clamping device) includes a fixed platen 41 and a movable platen 42, and a mold 43 is fixed between them to open and close. Therefore, the mold clamping device 40 is movable by a mold opening / closing drive device including an electric drive device (not shown), a ball screw 44 (only a part is shown) and a ball screw nut (not shown) that are driven by rotation. The mold is opened and closed by moving the mold clamping shaft 45 integral with the platen 42. The mold clamping device 40 includes a mold clamping hydraulic cylinder 47, a mold clamping ram 48, and a half nut 46 disposed on the front surface of the mold clamping ram 48, and the half nut 46 is connected to the annular protrusion 45 a of the mold clamping shaft 45. Then, the mold clamping ram 48 is advanced to perform mold clamping. Therefore, the mold clamping hydraulic cylinder 47 moves forward when the hydraulic oil is supplied to the mold clamping side oil chamber 47a, and the mold clamping ram 48 moves when the hydraulic oil is supplied to the mold opening side oil chamber 47b. The mold clamping control circuit 50 is connected so that 48 moves backward. When the half nut 46 is closed, the normally held position of the half nut 46 is adjusted in advance by a known mold thickness adjustment so as to mesh with the annular convex portion 45a of the mold clamping shaft 45 that has been closed. It is positioned at the mold thickness adjustment position. A tie bar 49 is stretched between a support platen that integrally incorporates the mold clamping hydraulic cylinder 47 and the fixed platen 41.

  In such a mold clamping device 40, a strong thrust is required for the mold clamping operation, but a large pulling force is not required for the operation of retracting the half nut to the mold thickness adjustment position after releasing the mold clamping force. The sectional area of the clamping side oil chamber 47a is considerably larger than the sectional area of the mold opening side oil chamber 47b. Further, the moving distance necessary for the operation of the mold clamping ram 48 is small as will be described below. Therefore, the volume of the mold clamping side oil chamber 47a is sufficiently smaller than that of the direct pressure type. Therefore, when the mold clamping force is increased, the volume of the hydraulic oil in the mold clamping side oil chamber 47a which is compressed and contracted is small. As a result, the amount of hydraulic oil supplied to the mold clamping side oil chamber 47a for the pressure increase is Less is enough. For the same reason, the amount of hydraulic oil returned from the mold clamping side oil chamber 47a to the pressure relief piping line when the mold clamping force is lowered at a stroke is small.

  Incidentally, the movement distance of the mold clamping ram 48 is small because the stroke of the mold clamping ram 48 that moves forward after the mold closing until the mold clamping is completed hits the annular protrusion 45a from the mold thickness adjustment position of the half nut 46. The adjustment distance of the mold clamping ram 48 necessary for mold thickness adjustment is slightly larger than the sum of the distance to advance until contact and the amount of extension of the tie bar 49 extended by mold clamping. This is because the distance slightly exceeds the distance of one pitch.

  Even in an injection molding machine having such a mold clamping device 40, when performing compression molding with thin precision molding such as recent light guide plate molding, in order to improve the shape accuracy and dimensional accuracy of the molded product and to remove residual distortion, There is a need for mold clamping control in which the mold clamping force is rapidly increased and then the pressure is rapidly released. Therefore, a mold clamping control circuit 50 as shown in FIG. 5 similar to the above-described injection control circuit of the injection apparatus including the accumulator and the impact pressure absorbing device is also used for such mold clamping control. Note that the hydraulic control circuit for the other driving devices such as the half nut 46 is a conventional technique, and therefore the description thereof is omitted.

  First, the control circuit for performing the mold clamping operation by moving the mold clamping ram 48 forward includes a supply piping line from the hydraulic pump 51 via the servo valve 52 to the mold clamping side oil chamber 47a of the mold clamping hydraulic cylinder 47. The piping lines include supply lines P11 and P12 from the hydraulic pump 51 to the servo valve 52, a supply line P13 from the servo valve 52 to the mold clamping side oil chamber 47a, and from between the supply line P11 and the supply line P12. The charge line CC1 branches and communicates with the accumulator 53. The pilot operation check valve 54 provided in the supply line P12 is opened when a pilot pressure is applied from a circle B direction shown in the figure by a switching valve (not shown), and the hydraulic oil accumulated in the accumulator 53 is supplied to the servo valve 52. To supply. A check valve 57 provided in the supply line P <b> 11 prevents hydraulic fluid from flowing back from the accumulator 53.

  On the other hand, as the mold clamping ram 48 advances, a piping line that releases hydraulic oil from the mold opening side oil chamber 47b is a branch line CC2 connected to the accumulator 60, and a line that joins the line CC2 from the mold opening side oil chamber 47b. It consists of BB. Therefore, the hydraulic oil in the mold opening side oil chamber 47 b whose volume is contracted by the advance of the mold clamping ram 48 accompanying mold clamping is accommodated in the accumulator 60. At this time, the volume flowing into the accumulator 60 is small because the stroke of the mold clamping ram 48 that is advanced during the molding operation is small and the sectional area of the mold opening side oil chamber 47b is small as described above. . Therefore, a standard capacity of about 20 L is sufficient for the capacity of the accumulator 60 even if the mold clamping device has a mold clamping force of about 4000 N, for example. The gas pressure sealed in the accumulator 60 is adjusted to be as weak as about 1 MPa, for example, and the pressure of the hydraulic oil in the accumulator 60 is set to 2 MPa by the pressure reducing valve 61 described next. The pressure of the hydraulic oil in the accumulator 60 is constantly applied as a back pressure to the mold opening side oil chamber 47b as will be described later.

  Note that the pressure of the hydraulic oil in the accumulator 60 is detected by a pressure sensor 65 disposed in the branch line CC2, and fed back to the control device of the injection molding machine. The pressure in the accumulator 60 is controlled as will be described later. For this purpose, a piping line for supplying hydraulic oil to the accumulator 60 includes a supply line P15 from the junction of the branch line CC2 and the line BB to the direction switching valve 56, and a supply line P14 between the direction switching valve 56 and the supply line P11. It is. A pressure reducing valve 61 for reducing the pressure on the secondary side to about 2 MPa is provided in the supply line P14. A tank line TT is provided between the direction switching valve 56 and the oil tank 55. The hydraulic oil in the accumulator 60 is manually depressurized by the open / close valve 66 in the line DD2 when it is idle.

  In addition, two accumulators 53 having a capacity of 20 L in which the sealed gas pressure is adjusted to about 11 MPa, for example, when a mold clamping device having a mold clamping force of about 4000 N, for example, is prepared. And it controls so that the pressure of the hydraulic fluid in the accumulator 53 will be about 20 MPa. Therefore, the pressure is detected by the pressure sensor 58 and sent to the control device of the injection molding machine, and the hydraulic oil is replenished to the accumulator 53 as necessary, as described later. In addition, the hydraulic oil in the accumulator 53 is opened and depressurized by the open / close valve 59 in the line DD1 at the time of rest or the like.

  In contrast to the control circuit for advancing the mold clamping ram 48, the control circuit of the present invention returns the high pressure hydraulic oil in the mold clamping side oil chamber 47a from the supply line P13 to the oil tank 55 so that it can be switched by the servo valve 52. Equipped with a pressure release line. In other words, the pressure release piping line is provided adjacent to the supply lines P11 and P12 connected to be switched by the same servo valve 52. The depressurization line includes the impact pressure absorbing device 11 of the present invention in the middle thereof, the first depressurization pipe R11 from the impact pressure absorbing device 11 to the servo valve 52, and the shock pressure absorbing device 11 to the oil tank. And second pressure release pipe R12 up to 55. The first pressure release pipe R11 communicates with the second through hole 16a as a straight through hole of the impact pressure absorbing device 11, and the second pressure release pipe R12 communicates with the branch through hole 16b of the impact pressure absorbing device 11. Communicate. As described above, the impact pressure absorbing device 11 is excellent in the sealed gas pressure is atmospheric pressure and the ability to flow in hydraulic fluid. In addition, the amount of hydraulic oil that flows into the impact pressure absorbing device 11 for pressure release is only the amount that is generated when the mold clamping ram 48 is retracted by the amount of extension of the tie bar 49 by the mold clamping operation. Few. Therefore, the impact pressure absorbing device 11 absorbs the high pressure existing in the mold clamping side oil chamber 47a and the supply line P13 rapidly and without resistance when the mold clamping force is instantaneously released during mold clamping. Regarding the volume of the impact pressure absorbing device 11, for example, in a mold clamping device having a clamping force of about 4000 N, a standard hollow container of about 20 L can be used as the hollow container of the impact pressure absorbing device 11.

  On the other hand, the piping line for retreating the mold clamping ram 48 is the aforementioned line BB between the mold opening side oil chamber 47b and the direction switching valve 56 and the branch line CC2 between the accumulator 60 and the line BB. A pipe line through which hydraulic oil in the mold clamping side oil chamber 47a is released to the oil tank 55 as the mold clamping ram 48 is retracted communicates the supply line P13, the servo valve 52, and the oil tank 55 described above. One pressure release pipe R11, impact pressure absorbing device 11, and second pressure release pipe R12. In such a piping line, as described later, a weak pressure in the accumulator 60 is constantly applied to the mold opening side oil chamber 47b, and the servo valve 52 controls the backward movement of the mold clamping ram 48 in a meter-out manner. .

  In particular, a pilot operated check valve 62 is provided in the line BB. The valve 62 is normally opened by applying pilot pressure from a switching valve (not shown) in the direction of the circle C shown in the figure. Thus, the pressure in the accumulator 60 is constantly applied to the mold opening side oil chamber 47b, and the mold clamping ram 48 is constantly subjected to back pressure. The supply line P15 is provided with a pilot operated check valve 63 and a check valve 64 with a throttle valve in order from the accumulator 60 side to the direction switching valve 56. On the other hand, the valve 62 is controlled so that the pilot operation check valve 63 is normally closed as will be described later, thereby preventing the backflow of hydraulic oil in the accumulator 60.

  By the way, a piping line that supplies hydraulic oil to the mold clamping side oil chamber 47 a and a piping line that returns hydraulic oil from the mold opening side oil chamber 47 b are controlled by different control valves of the servo valve 52 and the direction switching valve 56. This is because the supply lines P11 and P12 and the pressure release pipes R11 and R12 are provided on the primary side of the servo valve 52 as described above. That is, the depressurization line is provided as one piping line for draining the hydraulic oil from the high-pressure side mold clamping side oil chamber 47a to the other supply piping line for supplying the hydraulic oil to the mold clamping side oil chamber 47a. It is to be done. Therefore, in the mold clamping hydraulic cylinder 47, another direction switching valve 56 is connected to the other mold opening side oil chamber 47b, and mold clamping control is performed by cooperative control of the servo valve 52 and the direction switching valve 56. Such a configuration makes it possible to optimally select the servo valve 52 and the direction switching valve 56 in accordance with the required functional performance capacity. Actually, each control valve may be configured as described below, for example. This is advantageous when optimizing each control valve especially when performing the above-mentioned rapid mold clamping and rapid depressurization in a large-sized apparatus.

  First, as the servo valve 52, for example, a linear servo valve driven by a linear motor that switches the piping line at high speed and high response and precisely controls the flow rate is adopted. The servo valve 52 has three positions for switching the connection direction of the piping port according to the position of the valve spool (not shown), and each position is described next. Is configured as an all-port block. Further, the directional switching valve 56 employs a double solenoid switching valve having a capacity smaller than that of the servo valve as shown in the figure, and in its neutral position, the A port and the B port communicate with the T port via a restriction. is doing.

  More specifically, the servo valve 52 and the direction switching valve 56 are connected to the above-described piping line and controlled as follows. First, for the servo valve 52, the P port is connected to the supply line P12, the A port is connected to the supply line P13, and the B port is closed with a plug. Thus, when the connection position of the piping port of the servo valve 52 is moved to the offset position on the b side, the P port and the A port are communicated, and the pilot check valve 54 is opened, the accumulator 53 is disconnected from the supply line P12. It communicates with the supply line P13 and the mold clamping side oil chamber 47a. Next, for the directional switching valve 56, for example, a directional switching valve having three positions of a double solenoid is adopted. In particular, in the neutral position, the P port is blocked while the T port is restricted to both the A and B ports. It is comprised so that it may communicate via. The A port is connected to the pilot line PP of the pilot operated check valve 63, and the B port is connected to the check valve 64 with a throttle valve. The P port is connected to the supply line P14, and the T port is connected to the tank line TT.

  In addition, the control which replenishes the quantity of the hydraulic oil accumulate | stored in the accumulator 60 from the pump 51 side as needed excites the solenoid b of the direction control valve 56, and connects the supply line P14 to the supply line P15. Do. At this time, the pilot operation check valve 63 allows the hydraulic oil to flow in the forward direction, while preventing the hydraulic oil accumulated in the accumulator 60 from flowing backward to the oil tank 55 side. Further, the pressure reducing valve 61 depressurizes the hydraulic oil, and the check valve 64 with a throttle valve suppresses the flow rate of the hydraulic oil by the throttle. The pressure sensor 65 disposed on the branch line CC2 detects the pressure of the accumulator 60 and transmits the pressure value to the control device of the injection molding machine. The control device responds to the pressure value with the solenoid b of the direction control valve 56. Control the excitation of. However, the accumulator 60 accumulates the hydraulic oil that has returned from the mold opening side oil chamber 47b by clamping, so replenishment is not usually required. On the other hand, the control to return the hydraulic oil of the accumulator 60 to the oil tank 55 is performed by exciting the solenoid a of the direction control valve 56 to connect the supply line P14 to the pilot line PP and to connect the supply line P15 to the tank line TT. . Thus, pilot pressure is applied to the pilot operation check valve 63 to open the pilot operation check valve 63, and the hydraulic oil in the accumulator 60 is returned to the oil tank 55.

  In addition, in the control for accumulating hydraulic oil in the accumulator 53 for the first time, the supply line P14 is blocked by setting the direction switching valve 56 to the neutral position, and the supply line P12 is blocked without applying the pilot pressure to the pilot check valve 54. In this state, it is performed by the pump 51. Although not shown, a relief valve and a relief pipe, a drain pipe, and the like from the relief valve to the oil tank 55 are appropriately provided as in the prior art. The pump 51 is a variable displacement pump such as an electromagnetic proportional flow control pump.

  With the mold clamping control circuit 50 described above, mold clamping control of the mold clamping device 40 is performed as follows. The mold clamping control is performed especially when compression molding thin precision molded products, etc., with rapid mold clamping control performed at an appropriate timing after preliminary mold clamping and appropriate timing after starting injection filling after mold clamping. Will be mainly explained.

  First, as described above, the movement of the mold clamping shaft 45 is controlled by the ball screw 44 that is rotationally driven, and the mold is closed. Then, the half nut 46 held at the mold thickness adjustment position is closed and meshed with the mold clamping shaft 45.

  Next, the mold clamping ram 48 advances until the half nut 46 abuts on the annular convex portion 45a. Therefore, the pilot operation check valve 54 is opened by the pilot pressure, and the valve spool of the servo valve 52 is offset to the b side so that the P port and the A port communicate with each other, and the high pressure hydraulic oil in the accumulator 53 is charged to the charge line. It is supplied from CC1 to the mold clamping side oil chamber 47a via the supply line P12, the servo valve 52, and the supply line P13. At the same time, the piping port connection position of the direction switching valve 56 is controlled to the neutral position, the pilot pressure is released, the pilot operation check valve 63 is kept in the check state, and the mold opening side oil chamber 47b is operated. The oil flows forward through the pilot operated check valve 62 and is contained in the accumulator 60. The hydraulic oil stored in the accumulator 60 acts as a back pressure on the mold opening side oil chamber to prevent the mold clamping ram 48 from popping out, thereby stabilizing the mold clamping control. Thus, the hydraulic oil in the accumulator 53 is supplied to the mold clamping side oil chamber 47a while being controlled by the servo valve 52, whereby the advance of the mold clamping ram 48 is controlled. The back pressure not only holds the half nut 46 in the open state at the mold thickness adjustment position, but also helps prevent the mold clamping ram 48 from popping out during advancement.

  Next, the mold clamping ram 48 advances the mold clamping shaft through the half nut 46 to perform mold clamping. This mold clamping control is often performed in two stages, that is, preliminary mold clamping and main mold clamping, particularly when compression molding a thin precision molded product or the like. That is, at the initial stage of filling, preliminary mold clamping performed by a weak clamping force that can open the mold against the filling pressure of injection filling, and main mold performed by a strong clamping force at an appropriate timing during filling. It is tightening.

  In this compression molding, the transition from pre-clamping to permanent clamping must be done as quickly as possible. Therefore, high-speed mold clamping is performed between the preliminary mold clamping and the main mold clamping to rapidly increase the mold clamping force to the final mold clamping state. These mold clamping controls are common in that the mold clamping ram 48 is advanced. Therefore, basically the same control as that when the half nut 46 described above is brought into contact with the annular convex portion 45a is performed. The difference is in the control of the speed pressure when the servo valve advances the mold clamping ram 48. Therefore, when high-speed mold clamping is performed, the control with the preliminary mold clamping, in which the valve spool of the servo valve 52 is appropriately offset to the b side, is instantaneously switched to the completely offset control. By doing so, the high pressure hydraulic oil in the accumulator 53 is rapidly supplied to the mold clamping side oil chamber 47a at once. Thereafter, the main mold clamping is continued as it is. However, when the mold clamping force is changed to an arbitrary mold clamping force in a stepped manner, for example, the servo valve 52 is flow-controlled.

  Next, filling of the molten resin is performed on the injection device side, and high-speed depressurization control for depressurizing the mold clamping force is performed immediately after completion of the filling control or at an appropriate timing such as just before. This control also needs to be performed at the highest speed in compression molding of a thin precision molded product. Therefore, when performing the quick depressurization control, the piping port connection position of the servo valve 52 is rapidly offset to the a side, the T port and the A port are communicated, and the supply line P13 and the first depressurizing piping R11 are connected. And the mold clamping side oil chamber 47a is instantaneously communicated from the first pressure release pipe R11 to the second through hole 16a of the impact pressure absorbing device 11. Thus, the high pressure hydraulic oil in the mold clamping side oil chamber 47a and the supply line P13 flows into the impact pressure absorbing device 11 at the same time as the servo valve 52 is switched.

  At this time, in particular, the first pressure release pipe R11 and the second through hole 16a of the impact pressure absorbing device 11 communicate with each other in a straight line, and the second pressure release pipe R12 branches from the second through hole 16a. Since it communicates with the branch through hole 16b, the high pressure hydraulic oil in the first pressure release pipe R11 is accommodated from the second through hole 16a as a straight through hole and flows out to the second pressure release pipe R12 side. do not do. Then, when the pressure in the second pressure release pipe R12 subsequently decreases, the shock pressure absorber 11 returns the hydraulic oil to the oil tank 55 at a low pressure. As a result, no surge pressure is generated not only in the first pressure release pipe R11 but also in the second pressure release pipe R12, and the oil tank 55 is prevented from being damaged. At this time, since the pilot check valve 62 is open, the hydraulic fluid is freely replenished from the accumulator 60 to the mold opening side oil chamber 47b, but the molded product and the mold cavity are in close contact with each other. Therefore, the mold clamping ram 48 does not retract at a stretch.

  After that, until the mold is opened, the above depressurization state is maintained in principle, but the mold clamping may be restarted with a mold clamping force as appropriate. In this case, needless to say, the mold clamping control described above is appropriately performed. If the depressurization is not rapid depressurization, the offset amount is controlled so as to adjust the flow rate when the piping port connection position of the servo valve 52 is offset to the a side, as described above. Controlled by meter-out.

  Thereafter, in order to perform mold opening, the mold clamping ram 48 is retracted until the half nut 46 returns to the mold thickness adjustment position. Therefore, the servo valve 52 is controlled so as to offset the piping port connection position to the a side rather than the pilot operation check valve 62 in the same manner as described above, and the oil is released from the mold clamping side oil chamber 47a. A servo valve 52 controls the flow rate of hydraulic oil flowing to the tank 55 side to meter-out. At this time, the amount of hydraulic oil supplied to the mold opening side oil chamber 47b is almost equal to the amount returned to the accumulator 60 by mold clamping, as described above, and is small in quantity and low in pressure. Then, the hydraulic oil in the mold closing side oil chamber 47a returns from the first pressure release pipe R11 to the oil tank via the impact pressure absorbing device 11. At this time, since the pressure generated in the pressure release piping line is small, the hydraulic oil mainly flows from the second through hole 16a serving as the straight through hole of the impact pressure absorbing device 11 to the branched through hole 16b and flows through the impact pressure absorbing device 11. Go through. Thereafter, after the half nut 46 is moved back to the mold thickness adjustment position, the half nut 46 is opened and the mold is opened as usual.

FIG. 2 is a partial cross-sectional view schematically showing the impact pressure absorbing device of the present invention, and a diagram in the upper half of the center line is a state where the gas is filled in the prada but no hydraulic hydraulic oil is accumulated in the hollow space. The lower half of the figure shows a state where the prada is filled with gas and the hydraulic fluid is accumulated in the hollow space. It is an expanded section of the connection member in the assembly state of the impact pressure absorber of FIG. It is an expanded section of the connection member in the decomposition | disassembly state of the impact pressure absorption apparatus of FIG. It is an injection control circuit diagram of an injection device including an impact pressure absorbing device and an accumulator of the present invention. It is a mold clamping control circuit diagram of a mold clamping device including an impact pressure absorbing device and an accumulator of the present invention. It is a side view showing a conventional accumulator with a partial cross section, the upper half view from the center line is a state where the high pressure gas and hydraulic fluid are not filled in the prada and the hollow space, and the lower half view is The prada and the hollow space are filled with high-pressure gas and hydraulic fluid. It is an expanded section of the connecting member of the conventional accumulator, (a) is a state where high pressure gas has been filled in the prada, but hydraulic hydraulic oil has not yet been accumulated in the hollow space, and (b) is high pressure in the prada. In this state, the gas is filled and the hydraulic fluid is being accumulated in the hollow space.

Explanation of symbols

2 Hollow container 2a Hollow space 4 Prada 11 Impact pressure absorbing device 15 First connecting member (connecting member)
15a First through hole (straight through hole)
15c Sub through hole (straight through hole)
15d Bending member 16 Second connecting member (connecting member)
16a Second through hole (straight through hole)
16b Branch through hole 20 Injection device 24 Injection hydraulic cylinder (hydraulic drive device)
24a Injection side oil chamber 24b Reverse side oil chamber 30 Injection control circuit (hydraulic control device)
32 Servo valve 33 Accumulator 35 Oil tank P1 Supply line (Supply piping line)
P2 supply line (supply piping line)
C charge line (supply piping line)
R1 First pressure release pipe (return pipe line / pressure release line)
R2 Second pressure release pipe (return pipe line / pressure release line)
40 Clamping device 47 Clamping hydraulic cylinder (hydraulic drive device)
47a Mold clamping side oil chamber 47b Mold opening side oil chamber 50 Mold clamping control circuit (hydraulic control device)
52 Servo Valve 53 Accumulator 55 Oil Tank P11 Supply Line (Supply Piping Line)
P12 supply line (supply piping line)
CC1 charge line (supply piping line)
R11 1st pressure release pipe (return pipe line / pressure release line)
R12 Second pressure relief piping (return piping line / pressure relief piping line)

Claims (3)

  The hydraulic control device that supplies and controls the hydraulic fluid accumulated in the accumulator from the servo valve to the hydraulic drive device is provided in the middle of the return piping line from the servo valve to the oil tank. In addition, in the impact pressure absorption device having a hollow container for temporarily flowing high-pressure hydraulic fluid generated transiently in the return pipe from the return pipe, the hollow container has an atmospheric pressure on one side thereof. A connecting member for connecting the return pipe line and the hollow space in the hollow container to the other side of the return pipe connected to the servo valve; A straight through hole that communicates in a substantially straight line and opens into the hollow space, and a flow of hydraulic hydraulic fluid that flows into the hollow space and is positioned in the vicinity of the hollow space side opening of the straight through hole directly hits the prada. do not do And a branch through hole that branches from the straight through hole in a substantially right angle direction and connects to a return pipe that leads to the oil tank. apparatus.   The hydraulic control device including the impact pressure absorbing device according to claim 1 includes an injection hydraulic cylinder of an injection device, wherein an injection side oil chamber of the injection hydraulic cylinder is different from the servo valve, and a reverse side oil chamber is different. A piping line connected to the control valve and connected to the primary side of the servo valve includes a supply piping line that supplies hydraulic fluid from the accumulator, and a pressure relief piping line that returns the hydraulic fluid to the oil tank. A first pressure release pipe reaching the servo valve of the pressure release pipe line is connected to the linear through hole of the impact pressure absorbing device, and a second pressure reaching the oil tank of the pressure release pipe line When the injection pipe is connected to the branch through-hole of the impact pressure absorbing device and the injection speed is rapidly increased when filling with the molding resin, the servo valve is rapidly switched to remove the accumulator from the accumulator. When the hydraulic fluid is rapidly supplied to the injection-side oil chamber and the injection pressure is rapidly released immediately after the completion of filling, the servo valve is rapidly switched to supply the high-pressure hydraulic fluid in the injection-side oil chamber to the The hydraulic pressure oil in the impact pressure absorbing device is transferred from the branch through hole to the oil tank when the pressure in the second pressure release pipe is lowered after the straight pressure through hole is quickly accommodated in the impact pressure absorbing device. An injection control circuit for an injection device, wherein   The hydraulic control device including the impact pressure absorbing device according to claim 1 includes a mold clamping hydraulic cylinder of a mold clamping device, wherein a mold clamping side oil chamber of the mold clamping hydraulic cylinder is provided in the servo valve, and a mold opening side oil is provided. The chamber is connected to a different control valve, the piping line connected to the primary side of the servo valve is a supply piping line that supplies hydraulic fluid from the accumulator, and the pressure relief that returns the hydraulic fluid to the oil tank A first pressure relief pipe including the pipe line and reaching the servo valve of the pressure relief pipe line is connected to the straight through hole of the impact pressure absorber, and is connected to the oil tank of the pressure relief pipe line. By connecting the second pressure relief pipe to the branch through hole of the impact pressure absorbing device, when the mold clamping force is rapidly increased during mold clamping, the servo valve is rapidly switched to hydraulically operate from the accumulator. Oil the mold When supplying the side oil chamber rapidly and releasing the mold clamping force rapidly after mold clamping, the servo valve is switched quickly so that the hydraulic fluid of the high pressure in the mold clamping side oil chamber is impacted from the straight through hole. The hydraulic fluid in the impact pressure absorber is returned from the branch through hole to the oil tank when the pressure in the second pressure relief pipe is lowered and then quickly stored in the pressure absorber. A mold clamping control circuit for the mold clamping device.

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