JP2005337353A - Hydraulic cylinder device and injection molding unit of injection molding machine with usage of hydraulic cylinder device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic cylinder device capable of being easily controlled and capable of coping with a large capacity facility. <P>SOLUTION: A piston 14 is moved by a hydraulic pressure so as to follow the movement of a movement body side rod 24, and thereby large axial force is generated on a driving rod 15 jointed to the piston 14. When the piston 14 is moved in a speed higher than the movement speed of opening and closing valves 22 and 23, the opening and closing valves 22 and 23 are opened and the hydraulic pressure of an oil chamber of a cylinder 11 escapes through a working fluid passage provided on the piston. Therefore, the piston 14 always follows the opening and closing valves 22 and 23, in other words, the movement of the movement body side rod 24, and moves in the same speed with the movement body side rod 24. The driving rod 15 is driven with particularly large force in proportion to the force moving the movement body side rod, and the driving rod 15 is moved to follow the movement body side rod 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic cylinder device particularly suitable as a large-capacity hydraulic drive unit and an injection unit of an injection molding machine using the hydraulic cylinder device.

An injection molding apparatus using a hydraulic cylinder as an actuator for driving injection of an injection screw has been put into practical use. The hydraulic cylinders are arranged symmetrically in parallel on both sides of the injection cylinder and simultaneously driven in order to balance the driving force. (For example, see Patent Document 1)
In the molten resin injection process, first, the injection screw is moved backward at a low speed while rotating. As a result, the resin material fed into the injection cylinder is stored at the screw tip while being melt-plasticized. When the resin storage amount reaches a certain amount, the rotation of the injection screw is stopped, and then the injection screw is advanced at a high speed to inject the molten resin into the mold cavity from the nozzle at the tip of the injection cylinder.

In the previous injection molding apparatus, the advance and retreat of the injection screw was sufficient by repeating low-speed melt plasticization at a constant speed and high-speed injection at a constant speed. However, at present, step-by-step control of injection speed and in-mold pressure control are required to reduce the thickness of injection-molded products and increase the injection speed.
Since a large force is required for the injection of the resin, in order to drive the injection screw, it is necessary to use a hydraulic cylinder having a large diameter and to rapidly flow a large amount of hydraulic oil into the cylinder. High-speed injection requires a large-capacity hydraulic power source and a large-capacity switching valve, so the response of the hydraulic cylinder to the control command will be delayed due to the influence of inertia due to the weight of hydraulic oil. . Therefore, delicate control of the injection speed and the like in the injection process is difficult, and the cost of peripheral functional parts for control becomes high.

Therefore, in recent years, in order to realize highly accurate injection control, mechanical injection screw driving means using a ball screw or the like driven by an electric motor has been introduced. However, the load of the ball screw is limited, and when a large number of ball screws are installed, certainty of load sharing is required. Further, the injection screw driving means using the ball screw has a complicated structure and a high cost.
Japanese Patent Publication No.55-24986

As described above, the conventional drive device such as injection by a hydraulic cylinder is difficult to delicately control the injection speed for thinning the injection molded product or increasing the injection speed, and also controls the large-capacity hydraulic injection drive mechanism. Means are expensive.
On the other hand, mechanical injection driving means using a ball screw driven by an electric motor or a ball screw nut is easy to control the speed, but has a drawback that the ball screw is limited by the load. In addition, large-capacity ball screws are expensive, and when a large number of ball screws are used, the structure becomes complicated, and control means for synchronous rotation of the ball screw shaft and load averaging of the ball screw nut are provided. Since it becomes necessary, the equipment cost increases.

In view of such a situation, the present invention provides a hydraulic cylinder device that can be easily combined with a large-capacity hydraulic cylinder and a mechanical drive unit driven by an electric motor and can be used for large-capacity equipment. The purpose is that.
The present invention also provides an injection unit of an injection molding machine that uses the above hydraulic cylinder device to reduce the amount of circulating hydraulic oil, reduce the amount of relief oil, and reduce the energy of hydraulic operation. The purpose is that.

The hydraulic cylinder device according to the present invention is provided to be slidable in the hydraulic cylinder and the first and second oil chambers of the cylinder formed on one side and the other side thereof, respectively. A piston formed with a hydraulic fluid passage, a movable body side rod that is slidably penetrated through one side lid of the hydraulic cylinder, and is coupled to the piston so as to be relatively displaceable, and provided on the movable body side rod. A valve body configured to open and close the hydraulic oil passage by relative displacement between the body side rod and the piston is formed between the piston and the other side lid of the hydraulic cylinder so as to be slidable, A fixedly coupled drive rod;
An actuator for moving the rod on the movable body forward and backward, and a hydraulic pressure generating means configured to supply hydraulic oil to the second oil chamber and to recirculate the hydraulic oil through the hydraulic oil passage, The on-off valve is opened by the relative displacement caused by the speed difference when the speed of the piston moving in the same direction is larger than the speed of the valve body moving in the direction of the one side cover. In addition, the valve body is configured to be opened when the valve body moves in the direction of the other side lid in a state where the hydraulic pressure generating means is stopped.

  It is desirable that the diameter of the movable body side rod and the diameter of the drive rod are set to be equal so that the pressure receiving areas on both sides of the piston are equal. The on-off valve may be a poppet valve or a cup valve.

  The actuator for moving the moving body side rod forward and backward includes a ball screw shaft that is rotationally driven and a ball screw nut that is screwed to the ball screw shaft, and transmits linear motion of the ball screw nut to the moving body side rod. It can be constituted as follows.

  The hydraulic pressure generating means can include a hydraulic pump and a closed piping circuit that recirculates hydraulic oil discharged from the hydraulic pump. The hydraulic pump is operated in cooperation with the actuator so as to generate a flow amount of hydraulic oil that can move the piston following the valve body moving in the direction of the one side lid.

The hydraulic cylinder device according to the present invention is provided to be slidable in the hydraulic cylinder and the first and second oil chambers of the cylinder formed on one side and the other side thereof, respectively. A piston having a hydraulic oil passage;
A movable body side rod that is slidably penetrated through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable, and provided on the movable body side rod. By the relative displacement of the movable body side rod and the piston, First and second on-off valves that open and close the hydraulic oil passage are slidably passed through the first and second valve bodies that respectively constitute the piston and the other side cover of the hydraulic cylinder. , A drive rod fixedly coupled to the piston, an actuator for moving the rod on the movable body forward and backward, and hydraulic oil is selectively supplied to the first and second oil chambers, and the hydraulic oil is passed through the hydraulic oil passage. Hydraulic pressure generating means configured to recirculate the hydraulic oil, and the first on-off valve has a higher speed than the speed at which the first valve body moves in the direction of the one side lid. But When the moving speed in the direction is large, the second opening / closing valve is configured to be opened by the relative displacement caused by the speed difference, and the second valve body moves in the direction of the other side lid. When the speed at which the piston moves in the same direction is larger than the speed at which the piston is moved, the piston is opened by the relative displacement caused by the speed difference.

  It is desirable that the diameter of the movable body side rod and the diameter of the drive rod are set to be equal so that the pressure receiving areas on both sides of the piston are equal. The first and second on-off valves can be constituted by poppet valves. One of the first and second on-off valves may be a cup valve, and the other may be a cup valve or a poppet valve.

  The actuator for moving the moving body side rod forward and backward includes a ball screw shaft that is rotationally driven and a ball screw nut that is screwed to the ball screw shaft, and transmits linear motion of the ball screw nut to the moving body side rod. It can be constituted as follows.

  In an embodiment, the hydraulic pressure generating means includes a hydraulic pump and a closed piping circuit that recirculates hydraulic oil discharged from the hydraulic pump, and the hydraulic pump follows the piston with respect to the valve body. And is operated in cooperation with the actuator so as to generate a flow amount of hydraulic oil that can be moved.

  An injection unit of an injection molding machine according to the present invention includes a pair of hydraulic cylinder devices provided in parallel symmetry with respect to an injection cylinder, and an injection screw for injecting molten resin is moved forward and backward by these hydraulic cylinder devices. An injection unit of an injection molding machine configured as described above, wherein the pair of hydraulic cylinder devices are provided in a hydraulic cylinder and slidably in the hydraulic cylinder, and are formed on one side and the other side thereof, respectively. A piston formed with a hydraulic oil passage for communicating the first and second oil chambers of the cylinder, and a movable body side that is slidably penetrated through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable. A rod, and an opening / closing valve provided on the movable body side rod for opening and closing the hydraulic fluid passage by relative displacement between the movable body side rod and the piston. A drive body that is slidably passed through the other side lid of the hydraulic cylinder and fixedly coupled to the piston, an actuator that moves the movable body side rod forward and backward, and Hydraulic pressure generating means configured to supply hydraulic oil to the second oil chamber and to recirculate the hydraulic oil through the hydraulic oil passage. The on-off valve is opened by the relative displacement caused by the speed difference when the speed of the piston moving in the same direction is larger than the speed of the valve body moving in the direction of the one side cover. In addition, the valve body is configured to be opened when the valve body moves in the direction of the other side lid in a state where the hydraulic pressure generating means is stopped.

  The injection unit of the injection molding machine according to the present invention includes a pair of hydraulic cylinder devices provided in parallel symmetry with respect to the injection cylinder, and these hydraulic cylinder devices move the injection screw for molten resin injection back and forth. An injection unit of an injection molding machine configured to cause the first hydraulic cylinder device to have a structure of a normal hydraulic cylinder device, the second hydraulic cylinder device including a hydraulic cylinder, and the hydraulic pressure A piston that is slidably provided in the cylinder, and that is formed on one and the other side of the cylinder and that has a hydraulic oil passage that communicates the first and second oil chambers of the cylinder; and one of the hydraulic cylinders A movable body side rod that is slidably penetrated through the side lid and is coupled to the piston so as to be relatively displaceable; and provided on the movable body side rod; 1st and 2nd valve bodies which constitute the 1st and 2nd on-off valve which opens and closes the operation oil passage by relative displacement of the piston between the piston, respectively, and the other side lid of the hydraulic cylinder A driving rod that is slidably penetrated and fixedly coupled to the piston, an actuator that moves the moving body side rod forward and backward, and hydraulic oil is selectively supplied to the first and second oil chambers, and the operation is performed. Oil pressure generating means configured to recirculate the hydraulic oil through an oil passage. The first on-off valve is caused by a difference in speed when the speed at which the piston moves in the same direction is higher than the speed at which the first valve body moves in the direction of the one side lid. The second on-off valve is configured to be opened by relative displacement, and the speed at which the piston moves in the same direction is higher than the speed at which the second valve body moves in the direction of the other side lid. When large, it is configured to be opened by the relative displacement caused by the speed difference.

  According to the hydraulic cylinder device according to the present invention, the piston moves hydraulically following the movement of the movable body side rod, so that the drive rod coupled to the piston can have a large axial force. Further, when the piston moves at a speed greater than the moving speed of the on-off valve, the on-off valve is opened and the hydraulic pressure in the oil chamber of the cylinder is released through the hydraulic oil passage provided in the piston, so that the axial force Therefore, the piston always follows the movement of the on-off valve, that is, the moving body side rod, and moves at the same speed as the moving body side rod. Therefore, the drive rod can be driven with a force that is much greater than the force that moves the moving body side rod, and the driving rod can be moved following the moving body side rod. Thus, the hydraulic cylinder device of the present invention has a function as a boosted linear follow-up moving means capable of speed control.

According to the configuration in which one on-off valve is provided, when the piston is moved in the direction opposite to the above, the movable body side rod may be moved in the direction opposite to the above while the hydraulic pressure generating means is stopped. . In this case, the piston is moved by being pushed by the movable body side rod.
For example, in the injection process of the injection molding apparatus, a strong force is required at the time of injection, and a weak force (about 1/10 of the injection) is sufficient when plasticizing the resin while rotating the injection screw. Therefore, if the hydraulic cylinder device of the present invention is applied to facilities that require such force distribution, power energy can be saved.
According to the configuration in which two on-off valves are provided, the piston can follow in both directions and the bidirectional axial force can be amplified.

A poppet valve or a cup valve can be used as the on-off valve. The poppet valve is easy to seal with the valve seat. On the other hand, the cup valve needs to have a self-aligning function, but is suitable when the amount of hydraulic oil is large because the seal length is long.
Since the hydraulic pressure generating means has a closed piping circuit for returning the working oil, the diameter of the moving body side rod and the diameter of the drive rod are set to be equal, and the pressure receiving areas on both sides of the piston are made equal, thereby reducing the reserve of a small capacity. This can be done simply by providing a tank. Therefore, the operation cost is reduced.

According to the injection unit of the injection molding machine according to the present invention in which the hydraulic cylinder device described above is provided in parallel symmetry with respect to the injection cylinder, it is possible to control the speed of the injection screw with high accuracy, It is possible to obtain an effect that waste is suppressed and hydraulic drive energy is reduced.
Further, according to the injection unit of the injection molding machine according to the present invention using one hydraulic cylinder device as described above, the effect of reducing the manufacturing cost can be obtained in addition to the effect of the injection unit.

(First embodiment)
FIG. 1 is a side cross-sectional view showing a first embodiment of a hydraulic cylinder device according to the present invention.
The hydraulic cylinder 11 of the hydraulic cylinder device 10 shown in FIG. 1 includes a cylinder body 11a, a cylinder-side lid 12 fixed to one end side (drive rod side) of the cylinder body 11a, and the other end side of the cylinder body 11a. A cylinder chamber is formed by a cylinder side lid 13 fixed on the (operating rod side).

  The piston 14 slides in the hydraulic cylinder 11. A drive rod 15 is slidably passed through the cylinder-side lid 12. One end of the drive rod 15 is coupled to the piston 14, and the other end is coupled to the acting body (driven body) 16. Reference numeral 17 denotes a seal ring applied to the sliding portion of the drive rod 15 in the cylinder side lid 12, and reference numeral 21 denotes a seal ring applied to the sliding portion of the piston 14.

A valve seat plate 22 having a valve seat of a poppet type valve element 23 is fixed to the piston 14, and a hollow chamber portion for accommodating the valve element 23 is formed by the valve seat plate 22 and a concave portion of the piston 14. .
A cylindrical moving body side rod 24 extending in a direction opposite to the drive rod 15 around the piston 14 passes through the cylinder side lid 13 so as to be slidable. The movable body side rod 24 has the same outer diameter as the drive rod 15, and one end thereof is screwed into a male screw 24 a provided on the valve body 23. Therefore, when the moving body side rod 24 moves leftward to the position shown in the figure, the valve body 23 comes into contact with the valve seat of the valve seat plate 22, and as the moving body side rod 24 moves rightward from the position shown in the figure. Thus, the valve body 23 is separated from the valve seat of the valve seat plate 22.
Thus, the valve body 23 constitutes an open / close valve (poppet valve) together with the valve seat of the valve seat plate 22. Reference numeral 18 denotes a seal ring applied to the sliding portion of the movable body side rod 24 in the cylinder side lid 13.

  The valve body 23 includes a small shaft 23a, and the small shaft 23a is aligned with the shaft center of the drive rod 15 by fitting the small shaft 23a into a hole provided on the shaft center of the end 15a of the drive rod 15. . The gap between the side surface 23b of the valve body 23 and the end 15b of the drive rod 15 corresponds to the gap when the on-off valve is opened. An oil drain hole 23 c is formed in the small shaft 23 a of the valve body 23.

  The other end of the movable body side rod 24 positioned outside the cylinder 11 is coupled to a ball screw nut 26 that is screwed onto the ball screw shaft 25. The ball screw shaft 25 is supported on a ball screw abutment 27 attached to the cylinder side lid 13 via a ball bearing 28. Therefore, the ball screw shaft 25 is freely rotatable and is restrained from moving in the axial direction. The ball screw shaft 25 is driven by a servo motor 32 via a large gear 31 and a small gear 33.

  The hydraulic pump 36 is driven by a servo motor 37. The high-pressure hydraulic oil discharged from the hydraulic pump 36 is sent to the cylinder chamber on the drive rod 15 side of the hydraulic cylinder 11 through the hydraulic piping and the pipe joint 35. Since the drive rod 15 and the moving body side rod 24 have the same outer diameter, the pressure receiving areas on both sides of the piston 14 are the same. Accordingly, the amount of hydraulic oil filled in the hydraulic system is theoretically constant, but a reserve tank 39 is provided to compensate for the shortage of oil in the hydraulic piping due to expansion, leakage, etc. due to temperature changes. Reference numeral 40 indicates a hydraulic pressure gauge, and reference numeral 38 indicates a check valve.

  The servo motor 37 that drives the hydraulic pump and the servo motor 32 that drives the ball screw shaft 25 are operated in proportional tuning. That is, when the piston 14 is driven hydraulically, the moving speed of the piston 14 based on the oil discharged from the hydraulic pump 36 matches the moving speed of the ball screw nut 26 driven by the ball screw shaft 25, that is, The servo motors 32 and 37 are proportionally tuned so that the piston 14 moves following the ball screw nut 26.

Next, the operation of the hydraulic cylinder device 10 will be described.
When the hydraulic pump 36 is driven by the servo motor 37, the hydraulic oil discharged from the hydraulic pump 36 is sent in the direction indicated by the solid line arrow. At this time, if a gap is formed between the valve seat of the valve seat plate 22 and the valve body 23, that is, if the on-off valve is opened, the hydraulic oil passes through the piston 14 via the passage 14a. Therefore, hydraulic pressure does not act on the piston 14.

A control device (not shown) incorporates a program for controlling the position and moving speed of the action body 16. When the servo motor 32 is operated in accordance with this control program, and the ball screw shaft 25 is thereby rotated and the movable body side rod 24 is pulled in the direction of the arrow A, the valve body 23 is moved in the left direction in the figure to open and close the valve. Is closed.
Accordingly, hydraulic pressure is generated in the oil chamber on the right side of the cylinder 1, so that the piston 14 moves to the left. At this time, if the piston 14 goes too far, the on-off valve is opened and the hydraulic pressure in the oil chamber on the right side of the cylinder and the oil chamber on the left side of the cylinder are balanced. In this way, the piston 14 moves following the moving body side rod 24 to which the valve body 23 is attached while overshoot is suppressed.
The piston 14 generates a hydraulic pressure proportional to the load of the action body 16. Therefore, the ball screw shaft 25 and the ball screw nut 26 (moving body) are responsible for controlling the moving speed of the piston 14, and the hydraulic cylinder 11 and the hydraulic piston 14 are responsible for the load by the action body 16.

  When it is desired to move the piston 14 in the reverse direction, the hydraulic pump 36 is stopped to stop the circulation of the hydraulic oil, while the servo motor 32 is rotated in the reverse direction to send the ball screw nut 26 in the direction opposite to the arrow A direction. . As a result, the side surface 23b of the valve body 23 provided at one end of the movable body side rod 24 abuts on the end surface 15b of the drive side rod 15, so that the drive side rod 15 is pushed rightward (in the direction of the arrow indicated by the broken line). As a result, the action body 16 is moved. At this time, the hydraulic oil in the oil chamber on the right side of the hydraulic cylinder 11 passes through the gap between the valve seat of the valve seat plate 22 and the valve body 23, so that the pushing force of the piston 14 by hydraulic pressure is not generated.

  Since the hydraulic cylinder device 10 according to the first embodiment operates in this manner, it is suitable, for example, as hydraulic drive means for driving an injection screw of an injection molding device. This is because the injection process of the injection molding apparatus requires a large force at the time of injection, and a weak force (about 1/10 of the injection) is sufficient when plasticizing the resin while rotating the injection screw. is there. Therefore, the hydraulic cylinder device 10 is optimal as a driving means used for facilities that require such force distribution.

(Second Embodiment)
FIG. 2 is a side sectional view showing a main part of the hydraulic cylinder device 20 according to the second embodiment of the present invention. In FIG. 2, elements that are the same as those shown in FIG. 1 are given the same reference numerals. In the following, description of this common element is omitted.

  In FIG. 2, the moving body side rod 45 has a small diameter portion 45 a at a position close to the piston 41, and a spherical seat 44 is attached to the tip of the small diameter portion 45 a by a bolt 47. A cup-shaped valve body 43 having a depression matching the spherical surface, that is, a depression having the same curvature as that of the spherical surface, is engaged with the spherical seat 44 so as to be tiltable. When the valve body 43 comes into contact with the valve seat 41 a of the piston 41, the hydraulic oil passage leading to the left and right oil chambers of the cylinder 11 is closed. At this time, the entire circumference of the edge of the valve element 43 comes into contact with the valve seat 41a by the self-aligning action by the contact between the spherical surface of the spherical element 44 and the recess of the valve element 43, so that the hydraulic oil passage is securely closed. Can do.

  In FIG. 2, the upper half valve element 43 is in an open operation state, and the lower half valve element 43 is in a close operation state. The piston 41 is divided into a main body of the piston 41 and a mounting portion 42 of the drive rod 46 for the convenience of mounting the valve body 43. The attachment portion 42 is formed with an oil passage 42 a, and a screw portion 46 a of a drive rod 46 is screwed to the attachment portion 42.

  The hydraulic cylinder device 20 according to the second embodiment is the same as that of the first embodiment except for an on-off valve (cup valve) constituted by a valve body 43 and a valve seat 41a and peripheral elements related to the structure. The hydraulic cylinder device 10 is the same as the hydraulic cylinder device 10 according to the first embodiment.

  Since the hydraulic cylinder device 20 according to the second embodiment having an on-off valve as a cup valve constituted by the valve body 43 and the valve seat 41a has a large passage area when the on-off valve is opened, the piston 41 Is particularly effective when it is desired to immediately follow the moving body side rod 45 and the valve body 43, or when it is desired to move the piston 41 in the reverse direction without using hydraulic pressure.

(Third embodiment)
FIG. 3 is a side sectional view showing a hydraulic cylinder device 30 according to a third embodiment of the present invention. The hydraulic cylinder device 30 is different from the hydraulic cylinder device 10 of the first embodiment in that a pair of poppet type valve bodies 52 and 53 that can alternately open and close the through hole in the center of the piston 14 from the outside and the inside move. This is provided at the tip of the body side rod 54. When one of the on-off valve constituted by the valve body 52 and the on-off valve constituted by the valve body 53 is closed, hydraulic pressure acts on the side surface of the closed piston. The piston 14 moves while the hydraulic pressures on both sides thereof are balanced by the opening and closing operations of the valve bodies 52 and 53, and thereby the action body 16 is driven following the moving body. And the movement of the both sides of pushing and pulling is implement | achieved by switching the hydraulic action side of a piston.

  As shown in FIG. 3, the hydraulic cylinder device 30 includes a valve seat plate 51 attached to the piston 14, a valve seat on the outer edge portion of the through hole 51 a of the valve seat plate 51, and a valve seat on the inner edge portion. The poppet type valve bodies 52 and 53 provided at the distal end portion of the movable body side rod 54 so as to contact the alternating body and the switching valve 56 provided in the hydraulic circuit are provided. Since the configuration other than this configuration is the same as the configuration of the hydraulic cylinder device 10 according to the first embodiment, a description thereof will be omitted. In FIG. 3, the same reference numerals are assigned to elements common to the constituent elements of the hydraulic cylinder device 10 of the first embodiment.

  In FIG. 3, the moving body side rod 54 corresponding to the moving body side rod 24 of the first embodiment has a small diameter portion 54a at a position close to the piston 14, and the valve body opposed to the small diameter portion 54a. A valve member having 52 and 53 is fitted and fixed by a nut 55. As described above, the outer and inner edges of the through hole 51a of the valve seat plate 51 attached to the piston 14 constitute the valve seats of the valve body 52 and the valve body 53, respectively.

The moving body side rod 54 has a small shaft 54b at the tip. The small shaft 54 b is fitted into a hole formed at the center of the end of the drive rod 15, so that the axis of the valve bodies 52 and 53 is aligned with the axis of the drive rod 15, that is, the axis of the cylinder 11. . The small shaft 54b is formed with an oil drain hole indicated by a dotted line.
In this embodiment, a pair of opposed poppet type valve bodies 52 and 53 are provided, but the same function can be obtained even if one or both of them are replaced with a cup type valve body. Of course, in that case, a valve seat corresponding to the cup-shaped valve body is provided.

The high-pressure hydraulic oil discharged from the hydraulic pump 36 is sent to one of the left and right oil chambers of the hydraulic cylinder 11 through the electromagnetic switching valve 56, the hydraulic piping and the pipe joint 35.
Since the drive rod 15 and the moving body side rod 54 have the same outer diameter, the left and right pressure receiving areas of the piston 14 are the same. Therefore, theoretically, the amount of hydraulic oil filled in the hydraulic system is constant, but in this embodiment as well, a reserve tank is used to compensate for the shortage of oil in the hydraulic piping due to expansion, leakage, etc. due to temperature changes. 39 is provided. Reference numeral 40 indicates a hydraulic pressure gauge, and reference numeral 38 indicates a check valve.

Hereinafter, the operation of the hydraulic cylinder device 30 will be described.
When the switching valve 56 is operated to the switching position in FIG. 3, hydraulic oil is sent in the direction of the solid line arrow. At this time, if there is a gap between the valve seat of the valve seat plate 51 and the valve body 53, the hydraulic oil does not act on the piston 14 because the hydraulic oil passes through the gap.

The control device incorporates a program for controlling the position and moving speed of the action body 16. When the servo motor 32 is operated in accordance with this control program, and the ball screw shaft 25 is thereby rotated and the movable body side rod 24 is pulled in the direction of arrow A, the valve body 53 moves in the left direction in the figure and the valve seat. Abut. That is, the first opening / closing valve (poppet valve) including the valve body 53 is closed.
As a result, hydraulic pressure is generated in the oil chamber on the right side of the piston 14, and the piston 14 moves to the left. At this time, if the piston 14 goes too far, the first on-off valve is opened and the hydraulic pressure in the right and left oil chambers of the cylinder is balanced, so that the force to move the piston 14 is lost. In this way, the piston 14 moves following the moving body side rod 24 while overshoot is suppressed.
The piston 14 generates a hydraulic pressure proportional to the load of the action body 16. Accordingly, the moving body including the ball screw shaft 25 and the ball screw nut 26 is in charge of controlling the moving speed of the piston 14, and the hydraulic cylinder 11 and the hydraulic piston 14 are responsible for the load by the action body 16.

Next, when the switching valve 56 is switched to a position on the side different from the position of FIG. 3 by the control device, the hydraulic oil is sent in the direction of the broken arrow. At this time, if there is a gap between the valve seat of the valve seat plate 51 and the valve body 52, the hydraulic oil does not act on the piston 14 because the hydraulic oil passes through the gap.
When the servo motor 32 is rotated in the reverse direction, the ball screw shaft 25 is also rotated in the reverse direction, so that the moving body side rod 54 is moved in the direction of the broken line arrow B. Thereby, since the valve body 52 is moved rightward, this valve body 52 contacts the valve seat. That is, the second on-off valve (poppet valve) having the valve body 52 as a valve element is closed.
As a result, hydraulic pressure is generated in the oil chamber on the left side of the piston 14 and the piston 14 moves in the right direction. However, if the piston 14 goes too far, the second on-off valve is opened and the oil chamber on the right side of the cylinder is opened. Since the oil pressure in the left oil chamber is balanced, the force to move the piston 14 is lost. In this way, the piston 14 moves in the right direction following the moving body rod 54 by the opening and closing action of the valve body 52.

  Also in the third embodiment, the servo motor 37 that drives the hydraulic pump 36 and the servo motor 32 that drives the ball screw shaft 25 are operated in proportional tuning. That is, when the piston 14 is driven hydraulically, the moving speed of the piston 14 based on the oil discharged from the hydraulic pump 36 matches the moving speed of the ball screw nut 26 driven by the ball screw shaft 25, that is, The servo motors 32 and 37 are proportionally tuned so that the piston 14 moves following the ball screw nut 26.

  The hydraulic cylinder device 30 according to the third embodiment can convert a slight moving force (both the leftward moving force and the rightward moving force in the figure) of the moving rod 54 into a great oil pressure. It is possible to move the action body 16 at the same speed by the same distance as the moving body rod 54.

(Fourth embodiment)
FIG. 4 is a cross-sectional view and a hydraulic system block diagram of an injection unit of an injection molding machine according to the fourth embodiment of the present invention. FIG. 6 is a characteristic curve diagram showing the injection speed, hydraulic pump discharge flow rate and hydraulic pressure with respect to the stroke of the injection screw in the injection process of the injection unit 1.

The injection unit 1 shown in FIG. 4 uses the hydraulic cylinder device 10 shown in FIG. 1 or the hydraulic cylinder device 20 shown in FIG.
The injection unit 1 includes an injection cylinder 2, an injection screw 3 that is inserted into the cylinder 2 so as to be rotatable and movable back and forth, a fixed base 4 that fixes and supports the injection cylinder 2, and a sliding base 5 that is close to and away from the fixed base 4. And.
The sliding table 5 incorporates a bearing that rotatably supports the injection screw 3 and restricts the axial movement of the injection screw 3, and an injection screw drive motor 6 is attached.

  On both sides of the fixed base 4, that is, symmetrical positions around the injection cylinder 2, the hydraulic cylinder device 10 (20) is fixedly arranged in a form parallel to the injection cylinder 2 (in parentheses are shown in FIG. 2). No. of the hydraulic cylinder device 20). As described above, the hydraulic cylinder device 10 (20) drives the moving body side rod 24 (45) by the ball screw shaft 25 driven by the servo motor 32 and the ball screw nut 26 screwed to the ball screw shaft 25. Is configured to do. The cylinder 11 of the hydraulic cylinder device 10 (20) may be formed integrally with the fixed base 4.

Next, the hydraulic system of the injection unit 1 will be described. The control device 147 contains a program for controlling the injection unit 1. The inverter 48 supplies electric power according to an instruction based on the control program of the control device 147 to the AC motor 37a, and controls the rotation of the AC motor 37a. The hydraulic pump 36 is driven by this AC motor 37a. A servo motor may be used instead of the combination of the inverter 48 and the AC motor 37a.
Reference numeral 58 denotes a relief valve for preventing overload of the hydraulic pump 36, reference numeral 57 denotes a two-way electromagnetic on-off valve, and reference numeral 40 denotes a hydraulic gauge for detecting hydraulic pressure.
Hydraulic pipes 71 and 72 are coupled to the right and left oil chambers of the cylinder 11 in the pair of hydraulic cylinder devices 10 (20), respectively. A reserve tank 39 is branchedly connected to the pipe 72 via a check valve 38.

Next, a resin injection process using this injection unit 1 will be described.
When the injection screw 3 advances, the injection screw 3 is controlled at a substantially constant speed. Then, pressure control in the cavity (internal pressure control) is performed after the molten resin is filled in the cavity of the mold (not shown) until the fluidity of the resin is lost. Thereafter, the pressure is maintained until the resin is solidified, and the control of the forward direction of injection is completed.

FIG. 6 is a characteristic curve diagram illustrating the changes in the injection speed V, the discharge flow rate F of the hydraulic pump, and the hydraulic pressure P with respect to the injection stroke S of the injection screw 3 in the filling step and the subsequent pressure holding step.
In the filling step, the servo motor 32 is rotated at a predetermined rotational speed, and the valve body 23 (43) is moved at a designated speed. At this time, in order to make the piston 14 (41) follow the valve body 23 (43), supply of hydraulic oil so that the moving speed of the piston 14 (41) is slightly faster than the moving speed of the valve body (23 or 43). The amount, that is, the rotational speed of the hydraulic pump 36 is controlled. In addition, the excess of the hydraulic fluid which acts on piston 14 (41) will pass the valve body 23 (43).
On the other hand, during the pressure holding control, the pressure control is performed by rotating the hydraulic pump 36 so that the in-mold pressure is maintained in a state in which the rotational torque of the servo motor 32 is applied to the valve body 23 (43).

The hydraulic pump 36 is stopped at the time of resin plasticization storage in which the injection screw 3 moves backward. Then, the end of the moving body side rod 24 (45) is brought into contact with the end of the driving rod 15 (46), and the driving rod 15 (46) is moved backward directly by the moving body side rod 24 (45). At this time, since the valve body 23 (valve body 43) provided in the movable body side rod 24 (45) is in an open state, the hydraulic oil in the left and right oil chambers of the cylinder 11 freely circulates. No oil pressure acts on the piston 14 (41).
The servo motors 32 of the hydraulic cylinder devices 10 (20) are operated synchronously electrically or mechanically by a chain or a toothed belt (not shown) wound between them.

(Fifth embodiment)
FIG. 5 is a cross-sectional view and a hydraulic system block diagram of an injection unit for an injection molding machine according to a fifth embodiment of the present invention.
The injection unit 50 shown in FIG. 5 uses the hydraulic cylinder device 30 shown in FIG.
The injection unit 50 includes an injection cylinder 2, an injection screw 3 that is inserted into the cylinder 2 so as to be rotatable and movable back and forth, a fixed base 4 that fixes and supports the injection cylinder 2, and a sliding base 5 that is close to and away from the fixed base 4. And.
The sliding table 5 incorporates a bearing that rotatably supports the injection screw 3 and restricts the axial movement of the injection screw 3, and an injection screw drive motor 6 is attached.

The hydraulic cylinder device 30 and the hydraulic cylinder device 64 are fixedly disposed in both sides of the fixed base 4, that is, symmetrical positions around the injection cylinder 2 so as to be parallel to the injection cylinder 2.
As described above, the hydraulic cylinder device 30 is configured to drive the moving body side rod by the ball screw shaft 25 driven by the servo motor 32 and the ball screw nut 26 screwed to the ball screw shaft 25. .
On the other hand, the hydraulic cylinder device 64 has a general structure including a cylinder body 11 a ′, a hydraulic cylinder 11 ′ having a cylinder side lid 66 and a cylinder side lid 12, and a piston 65.

Next, the hydraulic system of the injection unit 1 will be described. The control device 60 contains a program for controlling the injection unit 50. The inverter 48 supplies electric power according to an instruction based on the control program of the control device 147 to the AC motor 37a, and controls the rotation of the AC motor 37a. The hydraulic pump 36 is driven by this AC motor 37a.
Hydraulic pipes 71 and 72 are coupled to the right and left oil chambers of the cylinders 11 and 11 ′ in the hydraulic cylinder devices 30 and 64, respectively.
Reference numeral 58 denotes a relief valve for preventing overload of the hydraulic pump 36, reference numeral 61 denotes a four-way electromagnetic opening / closing valve interposed between the hydraulic pump 36 and the pipes 71 and 72, and reference numeral 40 denotes a hydraulic meter for detecting the hydraulic pressure. Reference numeral 63 denotes an electromagnetic relief valve connected to the pipe 71.

Since the hydraulic cylinder devices 30 and 64 are coupled by the hydraulic pipes 71 and 72 as described above, the hydraulic pressures in the left and right oil chambers in the cylinder 11 of the hydraulic cylinder device 30 are in the cylinder 11 ′ of the hydraulic cylinder device 64. It becomes equal to the oil pressure in the left and right oil chambers.
Therefore, when the piston 14 of the hydraulic cylinder device 30 moves following the moving body side rod 54 (see FIG. 3), the piston 65 of the hydraulic cylinder device 64 operates in the same direction with the same force as the piston 14, and as a result, The slide 5, that is, the screw 3 is smoothly advanced and retracted.

  In the hydraulic cylinder device 30, the rotational speed of the hydraulic pump 36 is controlled so that the piston 14 follows the movement of the moving body side rod 54 over the entire injection process. A hydraulic pump having a capacity capable of operating both the hydraulic cylinder devices 10 and 64 is used.

Next, a resin injection process using this injection unit 50 will be described.
When the injection screw 3 advances, the injection screw 3 is controlled at a substantially constant speed. Then, pressure control in the cavity (internal pressure control) is performed after the molten resin is filled in the cavity of the mold (not shown) until the fluidity of the resin is lost. Thereafter, the pressure is maintained until the resin is solidified, and the control of the forward direction of injection is completed.

Since the speed control and pressure holding control of the injection screw 3 are the same as in the case of the fourth embodiment, the characteristic curve diagram of FIG. 6 can be applied to the control.
In the filling step, the servo motor 32 is rotated at a predetermined rotational speed, and the valve bodies 52 and 53 are moved at a designated speed. At this time, in order to cause the pistons 14 to follow the valve bodies 52 and 53, the amount of hydraulic oil supplied, that is, the rotation of the hydraulic pump 36, so that the moving speed of the piston 14 is slightly faster than the moving speed of the valve bodies 52 and 53. Speed is controlled. The surplus hydraulic fluid acting on the piston 14 passes through the on-off valve provided with the valve body 52 or the on-off valve provided with the valve body 53.
On the other hand, at the time of controlling the mold internal pressure and maintaining the pressure, the hydraulic pump 36 is rotationally controlled so as to maintain the mold internal pressure with the rotational torque of the servo motor 32 applied to the valve bodies 52 and 53.

  At the time of resin plasticization storage in which the injection screw 3 moves backward, the four-way electromagnetic switching valve 61 is switched so as to generate hydraulic pressure for moving the injection screw 3 backward in the hydraulic cylinder devices 30, 64, and an electromagnetic relief valve 63 for adjusting hydraulic pressure is used. Back pressure is applied to the hydraulic piping 71 side. The servo motor 32 is rotated in the reverse direction at a low speed, and the hydraulic pump 36 is rotated at a low speed corresponding to the moving speed of the valve bodies 52 and 53 to move the piston 14 to move the valve bodies 52 and 53, that is, the moving body side rod 54. Follow the movement.

  The hydraulic cylinder devices 30 and 64 are always subjected to equal and equal hydraulic pressures. Therefore, hydraulic pressures having the same direction and size act on the piston 14 of the hydraulic cylinder device 30 and the piston 65 of the hydraulic cylinder device 64. As a result, the injection screw 3 moves forward and backward in a well-balanced manner via the slide base 5. Is done.

  According to the injection unit 50 according to the fifth embodiment, it is only necessary to provide one hydraulic cylinder device 30 as a hydraulic cylinder device having a ball screw mechanism for controlling the speed of the injection screw 3. Can be reduced. Further, if the backward force of the injection screw 3 increases with the rotation of the injection screw 3 at the time of resin plasticization storage, a pulling force acts on the pistons 14 and 65. Since the back pressure is applied, the hydraulic cylinder device 30 can be normally controlled in a state where an appropriate positive pressure is applied.

It is side surface sectional drawing of the hydraulic cylinder apparatus which concerns on the 1st Embodiment of this invention. It is side surface sectional drawing of the hydraulic cylinder apparatus which concerns on the 2nd Embodiment of this invention. It is side surface sectional drawing of the hydraulic cylinder apparatus which concerns on the 3rd Embodiment of this invention. It is sectional drawing and hydraulic system block diagram which show embodiment of the injection unit which concerns on this invention provided with the hydraulic cylinder apparatus of FIG. 1 or FIG. It is sectional drawing and hydraulic system block diagram which show other embodiment of the injection unit concerning the present invention provided with the hydraulic cylinder device of FIG. FIG. 6 is a characteristic curve diagram illustrating the change in injection speed, hydraulic pump discharge flow rate, and hydraulic pressure with respect to the stroke of the injection screw in the injection process of the injection unit in FIGS. 4 and 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection unit 2 Injection cylinder 3 Injection screw 4 Fixed base 5 Slide base 10 Hydraulic cylinder apparatus 11, 11 'Hydraulic cylinder 12 Cylinder side cover 13 Cylinder side cover 14 Piston 15 Driving rod 16 Acting body (driven body)
22 Valve seat plate 23 Valve body 24 Moving body side rod 25 Ball screw shaft 26 Ball screw nut 32 Servo motor 36 Hydraulic pump 41 Piston 42 Piston joint 43 Valve body 45 Moving body side rod 46 Drive rod 147 Controller 48 Inverter 50 Injection unit 51 Valve Seat plate 52 Valve body (outside)
53 Valve body (inside)
54 Moving body side rod 56 Switching valve 57 Two-way switching valve 58 Relief valve 60 Control device 61 Four-way switching valve 63 Hydraulic pressure adjusting relief valve

Claims (14)

A hydraulic cylinder;
A piston that is slidably provided in the hydraulic cylinder, and that forms a hydraulic oil passage that communicates the first and second oil chambers of the cylinder formed on one and the other of the cylinder;
A movable body side rod that is slidably passed through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable;
A valve body provided on the movable body side rod, and configured to open and close the hydraulic oil passage by relative displacement between the movable body side rod and the piston, and the piston,
A drive rod slidably pierced through the other side lid of the hydraulic cylinder and fixedly coupled to the piston;
An actuator for moving the rod on the movable body forward and backward, and
Hydraulic pressure generating means configured to supply hydraulic oil to the second oil chamber and recirculate the hydraulic oil through the hydraulic oil passage;
The on-off valve is opened by the relative displacement caused by the speed difference when the speed of the piston moving in the same direction is larger than the speed of the valve body moving in the direction of the one side cover. In addition, the hydraulic cylinder device is configured to be opened when the valve body moves toward the other side lid in a state where the hydraulic pressure generating means is stopped.   2. The hydraulic cylinder device according to claim 1, wherein the diameter of the movable body side rod and the diameter of the drive rod are set to be equal to each other so that pressure receiving areas on both sides of the piston are made equal.   The hydraulic cylinder device according to claim 1 or 2, wherein the on-off valve is a poppet valve.   The hydraulic cylinder device according to claim 1 or 2, wherein the on-off valve is a cup valve.   The actuator for moving the moving body side rod forward and backward includes a ball screw shaft that is rotationally driven and a ball screw nut that is screwed to the ball screw shaft, and transmits linear motion of the ball screw nut to the moving body side rod. The hydraulic cylinder device according to claim 1, wherein the hydraulic cylinder device is configured as described above. The hydraulic pressure generating means includes a hydraulic pump, and a closed piping circuit for recirculating the hydraulic oil discharged from the hydraulic pump,
The hydraulic pump is operated in cooperation with the actuator so as to generate a flow amount of hydraulic oil that can move the piston following the valve body moving in the direction of the one side lid. The hydraulic cylinder device according to any one of 1 to 5, wherein A hydraulic cylinder;
A piston that is slidably provided in the hydraulic cylinder, and that forms a hydraulic oil passage that communicates the first and second oil chambers of the cylinder formed on one and the other of the cylinder;
A movable body side rod that is slidably passed through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable;
First and second opening and closing valves provided on the moving body side rod and configured to open and close the hydraulic fluid passage by relative displacement between the moving body side rod and the piston are respectively configured between the piston and the piston. The disc,
A drive rod slidably pierced through the other side lid of the hydraulic cylinder and fixedly coupled to the piston;
An actuator for moving the rod on the movable body forward and backward, and
Hydraulic pressure generating means configured to selectively supply hydraulic oil to the first and second oil chambers and to recirculate the hydraulic oil through the hydraulic oil passage;
The first on-off valve is caused by a difference in speed when the speed at which the piston moves in the same direction is higher than the speed at which the first valve body moves in the direction of the one side lid. Configured to be opened by relative displacement,
The second on-off valve is caused by a difference in speed when the speed at which the piston moves in the same direction is higher than the speed at which the second valve body moves in the direction of the other side lid. Configured to be opened by relative displacement,
A hydraulic cylinder device characterized by that.   8. The hydraulic cylinder device according to claim 7, wherein the diameter of the movable body side rod and the diameter of the drive rod are set to be equal so that the pressure receiving areas on both sides of the piston are equal.   The hydraulic cylinder device according to claim 7 or 8, wherein the first and second on-off valves are poppet valves.   9. The hydraulic cylinder device according to claim 7, wherein one of the first and second on-off valves is a cup valve, and the other is a cup valve or a poppet valve.   The actuator for moving the moving body side rod forward and backward includes a ball screw shaft that is rotationally driven and a ball screw nut that is screwed to the ball screw shaft, and transmits linear motion of the ball screw nut to the moving body side rod. The hydraulic cylinder device according to any one of claims 7 to 10, wherein the hydraulic cylinder device is configured as described above. The hydraulic pressure generating means includes a hydraulic pump, and a closed piping circuit for recirculating the hydraulic oil discharged from the hydraulic pump,
The hydraulic pump is operated in cooperation with the actuator so as to generate hydraulic oil at a flow rate that can move the piston to follow the piston with respect to the valve body. The hydraulic cylinder device described. An injection unit of an injection molding machine comprising a pair of hydraulic cylinder devices provided in parallel to the injection cylinder and configured to move the injection screw for molten resin injection back and forth by these hydraulic cylinder devices. The pair of hydraulic cylinder devices are
A hydraulic cylinder;
A piston that is slidably provided in the hydraulic cylinder, and that forms a hydraulic oil passage that communicates the first and second oil chambers of the cylinder formed on one and the other of the cylinder;
A movable body side rod that is slidably passed through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable;
A valve body provided on the movable body side rod, and configured to open and close the hydraulic oil passage by relative displacement between the movable body side rod and the piston, and the piston,
A drive rod slidably pierced through the other side lid of the hydraulic cylinder and fixedly coupled to the piston;
An actuator for moving the rod on the movable body forward and backward, and
Hydraulic pressure generating means configured to supply hydraulic oil to the second oil chamber and recirculate the hydraulic oil through the hydraulic oil passage;
The on-off valve is opened by the relative displacement caused by the speed difference when the speed of the piston moving in the same direction is larger than the speed of the valve body moving in the direction of the one side cover. In addition, the injection unit of the injection molding machine is configured to be opened when the valve body moves in the direction of the other side lid in a state where the hydraulic pressure generating means is stopped. An injection unit of an injection molding machine comprising a pair of hydraulic cylinder devices provided in parallel to the injection cylinder and configured to move the injection screw for molten resin injection back and forth by these hydraulic cylinder devices. And
The first hydraulic cylinder device has a structure of a normal hydraulic cylinder device, and the second hydraulic cylinder device includes:
A hydraulic cylinder;
A piston that is slidably provided in the hydraulic cylinder, and that forms a hydraulic oil passage that communicates the first and second oil chambers of the cylinder formed on one and the other of the cylinder;
A movable body side rod that is slidably passed through one side lid of the hydraulic cylinder and is coupled to the piston so as to be relatively displaceable;
First and second opening and closing valves provided on the moving body side rod and configured to open and close the hydraulic fluid passage by relative displacement between the moving body side rod and the piston are respectively configured between the piston and the piston. The disc,
A drive rod slidably pierced through the other side lid of the hydraulic cylinder and fixedly coupled to the piston;
An actuator for moving the rod on the movable body forward and backward, and
Hydraulic pressure generating means configured to selectively supply hydraulic oil to the first and second oil chambers and to recirculate the hydraulic oil through the hydraulic oil passage;
The first on-off valve is caused by a difference in speed when the speed at which the piston moves in the same direction is higher than the speed at which the first valve body moves in the direction of the one side lid. Configured to be opened by relative displacement,
The second on-off valve is caused by a difference in speed when the speed at which the piston moves in the same direction is higher than the speed at which the second valve body moves in the direction of the other side lid. Configured to be opened by relative displacement,
An injection unit for an injection molding machine.

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