JP2004322452A - Turntable forward/backward/moving mechanism of rotary injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a hydraulic power generating cylinder driven by an electric motor be adopted in the turntable forward/backward moving mechanism of a rotary injection molding machine by a means for connecting a piston rod to a ball screw shaft. <P>SOLUTION: In the rotary injection molding machine, the turntable 7 for installing a mold is supported by a middle rotary shaft 9 and set on the side of a movable platen 5 or a machine base, and the rotary shaft 9 is pressurized by hydraulic pressure to forward/backward move the turntable 7. A second hydraulic cylinder 13 for generating hydraulic power having a piston 15 in the shape of both rods is connected to a first hydraulic cylinder 10 having the rotary shaft 9 as a piston rod by hydraulic ways 16 and 17. The driving device 20 of the second hydraulic cylinder 13 is composed of an electric motor 24, a ball nut member 23 of a regular position which is rotated by the motor 24, and a ball screw shaft 21 which is screwed with the ball nut member 23 to connect its shaft end with a piston 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a turntable advance / retreat movement mechanism of a rotary injection molding machine used for multicolor molding or insert molding in which a turntable for installing a mold is supported by a central rotation shaft and is movable forward and backward by hydraulic pressure. Things.
[0002]
[Prior art]
In a conventional rotary injection molding machine that transfers a mold by rotating a turntable, a piston is connected to a rotating shaft at the center of the table and provided on a movable plate, and the rotating shaft can be moved forward and backward by hydraulic pressure, so that the mold is moved. At the time of transfer, the turntable is moved forward to separate it from the movable platen, and at the time of mold clamping, the turntable is moved backward to come into close contact with the movable platen (for example, see Patent Document 1).
In addition, there is a type in which a rotation shaft of a turntable provided on a machine base is used as a piston rod and the rotation shaft is moved forward and backward by hydraulic pressure (for example, see Patent Document 2).
[0003]
It is known that as a driving means of a hydraulic control cylinder for an injection cylinder, a rotary motion transmitted from an electric motor is converted into a linear motion of a plunger by a ball screw shaft, and hydraulic pressure generation control is performed by the plunger (for example, see Patent Document 1). 3).
In addition, as a driving means of the pressure increasing cylinder of the mold clamping cylinder, the rotational motion transmitted from the electric motor to the ball nut member is converted into a linear motion of the pressure increasing piston by the ball screw shaft to increase the pressure of the mold clamping cylinder. Some are also available (for example, see Patent Document 4).
[0004]
[Patent Document 1]
JP-A-2002-79558 (page 2-3, FIG. 1).
[Patent Document 2]
JP-A-2000-84841 (page 3, FIG. 2).
[Patent Document 3]
JP-A-11-268092 (page 4-5, FIG. 1).
[Patent Document 4]
JP-A-2002-2060 (page 1, FIG. 1).
[0005]
[Problems to be solved by the invention]
As described in Patent Literatures 1 and 2, when a rotary shaft is pressurized by hydraulic pressure to move a turntable forward or backward, a hydraulic pump and its accompanying equipment are required as pressure sources. There is no particular problem in a molding machine in which the drive sources of the mold clamping mechanism, the injection mechanism, the nozzle touch device, and the like are hydraulic, since those drive sources can be used.
[0006]
However, in an electric injection molding machine in which all driving is performed by an electric motor, if the turntable is moved forward and backward by hydraulic pressure, a hydraulic pump is required as a drive source in addition to the electric motor. A molding machine having different types of driving sources is not preferable from the viewpoint of maintenance as well as the configuration. Therefore, the rotation is performed by a machine using an electric motor as a drive source, but the structure is more complicated than in a case where the rotating shaft is pressurized by hydraulic pressure, and a forward dimension of separating the turntable from the movable platen or the machine base is 2 to 3 mm. Therefore, the control is difficult as compared with the hydraulic pressure, and there is a problem in responsiveness.
[0007]
On the other hand, as described in Patent Document 3, the generation of hydraulic pressure is performed not by a hydraulic pump but by converting the rotational motion transmitted from an electric motor into a linear motion by a ball screw shaft. Since the pressure oil in the cylinder is pressurized by the plunger by rotating the screwed ball screw shaft, two hydraulic control cylinders are required for the front chamber and the rear chamber. Also, since both are driven and controlled by separate electric motors, such a hydraulic control cylinder is applied to the pressurizing movement of the rotating shaft by hydraulic pressure, so that the turntable can be moved forward and backward by hydraulic pressure. It is difficult to do.
[0008]
In Patent Document 2, a ball nut member is attached to a hollow, double rod-type pressure-intensifying piston, and the rotation of a ball screw shaft screwed to the ball nut member is changed to linear motion by the ball-nut member to advance and retreat the pressure-increasing piston. The cylinder that includes the ball nut member moves because the ball nut member is used for both the movement of the ball screw shaft and the movement of the pressure increasing piston. The surrounding structure becomes complicated, and it is difficult to apply the structure to pressurizing movement of the rotating shaft by hydraulic pressure.
[0009]
The present invention has been conceived in order to solve the above-described problems, and has as its object to generate hydraulic pressure by using an electric motor as a drive source and thereby pressurize a rotating shaft to move a turntable forward and backward. Even so, it is an object of the present invention to provide a turntable advance / retreat moving mechanism provided with a hydraulic pressure generating cylinder which can be applied to an electric rotary injection molding machine with a simple structure by employing means for connecting a piston rod and a ball screw shaft.
[0010]
[Means for Solving the Problems]
The present invention according to the above object provides a rotary table for supporting a mold installation turntable, provided on a movable platen or a machine side, supported by a central rotating shaft, and pressurizing the rotating shaft with hydraulic pressure to move the turntable forward and backward. In the injection molding machine, a second hydraulic cylinder for generating hydraulic pressure, which is provided with a double rod-shaped piston, is connected to a first hydraulic cylinder in which the rotating shaft is housed as a piston rod by a hydraulic path, and A hydraulic cylinder drive device comprising an electric motor, a ball nut member at a fixed position rotated by the electric motor, and a ball screw shaft screwed to the ball nut member and having a shaft end connected to a piston. It is.
[0011]
The second hydraulic cylinder of the present invention is provided such that the front chambers and the rear chambers are connected to each other by a hydraulic path in the first hydraulic cylinder, and there is an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder. In this case, the area ratio between the front and rear surfaces of the piston of the second hydraulic cylinder is configured to be the same as the area ratio between the front and rear surfaces of the piston of the first hydraulic cylinder.
[0012]
Further, the second hydraulic cylinder of the present invention is provided in the first hydraulic cylinder by connecting the front chambers and the rear chambers by a hydraulic circuit, and has an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder. In such a case, an auxiliary tank is provided in the hydraulic path, and both ends of the second hydraulic cylinder are set as a forward operation origin and a backward operation origin of the piston.
[0013]
Further, the control means for controlling the movement of the piston of the second hydraulic cylinder is provided between the detection piece provided at the outer end of the cylinder of the piston rod and the stroke range of the piston rod outside the cylinder at the same distance as the movement distance. The driving device may include a pair of proximity switches provided before and after, or may include an encoder built in an electric servomotor included in the driving device.
[0014]
In the above configuration, since the electric motor generates the hydraulic pressure for moving the rotary shaft forward and backward together with the turntable, the rotary shaft is advanced and retracted by hydraulic pressure. . The structures of the rotary shaft and the first hydraulic cylinder may be the same as those in the case where a hydraulic pump is used as a drive source, and the structure can be used as it is for an electric molding machine in which all the drive sources are electric motors.
[0015]
Further, since the piston of the second hydraulic cylinder adopts a double rod type and the piston rod is directly operated with the ball screw shaft, the transmission efficiency is good, and there is a difference in area between the front and rear surfaces of the piston of the first hydraulic cylinder. However, since the area ratio between the front surface and the rear surface of the piston of the second hydraulic cylinder is made the same or the amount of oil in the cylinder is always set to a predetermined amount by controlling the amount of oil by the auxiliary tank of the hydraulic circuit, the turntable that is repeatedly performed The oil amount balance is also maintained during the forward and backward movement of the turntable, and even if the supply and discharge amount of the pressure oil to the front and rear chambers of the first hydraulic cylinder is small, the rotary shaft is reliably pressurized to advance and retract the turntable. Be able to do it quickly.
[0016]
Further, in the oil amount control by the auxiliary tank, both ends of the second hydraulic cylinder are set to the forward operation origin and the backward operation origin, and the piston is moved forward or backward from there. The piston movement of the set stroke can be repeated without being affected by the area difference between the front surface and the rear surface.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to a horizontal rotary injection molding machine shown in the drawings.
In FIG. 1, reference numeral 1 denotes a pressure receiving plate, and 2 denotes a fixed plate, which is connected to a tie bar 3 and stands on a machine base 4. A movable plate 5 is provided between the pressure receiving platen 1 and the fixed platen 2 by being inserted into the tie bar 3, and a toggle mechanism 6 is connected between the back portion and the pressure receiving platen 1.
[0018]
On the front surface of the movable platen 5 facing the fixed platen 2, a turntable 7 that makes a half turn or one turn by gear transmission with a rotation drive device (not shown) is provided. The turntable 7 is provided with a rotating shaft 9 having a piston 8 (see FIG. 2) around its center at the center of the back surface, and the rotating shaft 9 is rotatably inserted into a hydraulic cylinder 10 in a movable platen as a piston rod. The movable plate is provided on the front surface of the movable plate so as to be freely contacted and separated. The movable platen 5 is provided with a mold 11 on the fixed platen side and a plurality of (one in the figure) molds 12 for closing the mold. In addition, 13 is a second hydraulic cylinder described later, 18 is an auxiliary tank of the second hydraulic cylinder 13, and 20 is a driving device.
[0019]
In FIG. 2, hereinafter, reference numeral 13 denotes a second hydraulic cylinder for generating hydraulic pressure in which the hydraulic cylinder 10 is provided as a first hydraulic cylinder, and a double rod type piston 15 having a piston rod 14 inserted through both end walls. The front chamber 13a and the rear chamber 13b defined by the piston 15 are connected to the front chamber 10a and the rear chamber 10b defined by the piston 8 of the first hydraulic cylinder 10 by hydraulic paths 16 and 17, respectively. It is.
[0020]
Further, the cylinder capacity of the second hydraulic cylinder is determined in relation to the cylinder capacity of the first hydraulic cylinder 10 which is set based on the separation dimension of the turntable 7, but as shown in FIG. When the front face 15a and the rear face 8b of the second hydraulic cylinder 13 have the same area, the front face 15a and the rear face 15b of the piston 15 in the second hydraulic cylinder 13 have the same area. Does not occur, so that the set stroke can be repeated to reciprocate the piston 15 to move the turntable 7 forward and backward.
[0021]
Further, the advance / retreat control of the piston 15 is performed by using a detection piece 14a provided at the outer end of the cylinder of the piston rod 14 and the front and rear of the piston rod 14 provided at the same distance as the movement distance in the stroke range of the piston rod 14 outside the cylinder. This can be performed by a pair of proximity switches 14b and 14c.
[0022]
Reference numeral 20 denotes a driving device for the second hydraulic cylinder 13, a ball screw shaft 21 having a shaft end connected to the piston rod 14 and provided on the same axis, and being screwed with the ball screw shaft 21 to form a drive in a housing (not shown). A ball screw shaft 23 at a fixed position rotatably provided on the bearing member 22, an electric motor 24 such as a servo motor installed in the housing, and pulleys 25 and 26 mounted on the drive shaft of the ball nut member 23 and the electric motor 24. And a timing belt 27 provided to hang.
[0023]
When an electric servomotor including an encoder is used as the electric motor 24 of the drive device 20, the rotational speed of the ball screw shaft 21 detected by the encoder can be arithmetically converted into the amount of movement of the piston 15. The movement of the piston 15 can be controlled by the electric motor 20 instead of the pair of proximity switches 14b and 14c.
[0024]
In such a driving device 20, the rotation of the electric motor 24 is transmitted to the ball nut member 23 via the timing belt 27, and the rotation of the ball nut member 23 is converted into the linear motion of the piston rod 14 by the ball screw shaft 21. . The direction of movement of the piston rod 14 is determined by the direction of rotation of the electric motor 24.
[0025]
When the piston 15 moves forward due to the forward rotation of the electric motor 24, the pressure oil in the rear chamber 13b is pressed by the piston 15 until the detection piece 14a reaches the proximity switch 14b and the rotation of the electric motor 24 stops. , Into the rear chamber 10b of the first hydraulic cylinder 10. Accordingly, the pressure oil in the front chamber 10a flows into the front chamber 13a of the second hydraulic cylinder 13, and the rotary shaft 9, which also serves as a piston, moves forward. Thereby, the turntable 7 of the same body also moves and separates from the front surface of the movable platen 5 to be easily rotated.
[0026]
Conversely, when the electric motor 24 rotates in the reverse direction and the piston 15 moves backward, the pressure oil in the front chamber 13a is released until the detection piece 14a reaches the proximity switch 14c and the rotation of the electric motor 24 stops. And press-fitted into the front chamber 10 a of the first hydraulic cylinder 10. Accordingly, the pressure oil in the rear chamber 10b is returned to the rear chamber 13b of the second hydraulic cylinder 13, and the rotating shaft 9 returns to the original position together with the turntable 7, and the front surface of the movable platen 5 And comes to withstand the mold clamping force.
[0027]
FIG. 3 shows the second hydraulic cylinder 13 in a case where the area of the front surface 8a of the piston of the first hydraulic cylinder 10 is larger than the area of the rear surface 8b and there is an area difference there between. In this case, if the area ratio between the front surface 15a and the rear surface 15b of the piston is made the same as the area ratio between the front surface 8a and the rear surface 8b of the first hydraulic cylinder 10, the difference in the pressure oil flow between the two cylinders is determined based on the area ratio. Therefore, even if the piston 15 reciprocates repeatedly, the piston 15 does not shift, and the turntable 7 can be moved forward and backward.
[0028]
FIG. 4 shows that, even if there is an area difference between the front surface 8a and the rear surface 8b of the piston of the first hydraulic cylinder 10, the area of the front surface 15a and the rear surface 15b of the piston 15 is the same, resulting from the difference in the area ratio between the two cylinders. This shows a case where the difference in the amount of pressure oil between the front and rear chambers is eliminated by using the auxiliary tank 18.
[0029]
The auxiliary tank 18 is connected to both the hydraulic paths 16 and 17 via an electromagnetic valve 19, and switches the electromagnetic valve 19 to the symbol b side when the piston 15 moves forward, so that the auxiliary tank 18 and the hydraulic path 16 are connected to each other. Make the connection. Thereby, the pressure oil from the auxiliary tank 18 supplements the pressure oil flowing from the front chamber 10a of the first hydraulic cylinder 10 to the front chamber 13a of the second hydraulic cylinder, and the excess pressure oil is provided in the hydraulic path 16. Is discharged from the valve 19a.
[0030]
At the time of backward movement, the electromagnetic valve 19 is switched to the symbol a side to connect the auxiliary tank 18 and the hydraulic path 17. Thereby, the pressure oil from the auxiliary tank 18 supplements the pressure oil flowing from the rear chamber 10b of the first hydraulic cylinder 10 into the rear chamber 13b of the second hydraulic cylinder. By such a valve switching operation, a difference in pressure oil inflow / outflow caused by a difference in the area of the front and rear surfaces of the piston in the first hydraulic cylinder 10 is avoided. Does not occur, and the turntable 7 can be moved forward and backward.
[0031]
It is preferable to control the movement of the piston 15 by setting both ends of the cylinder to the forward operation origin A and the backward operation origin B of the piston 15 and starting the movement of the piston 1 from the origin. The movement of the piston 15 is controlled by a pair of detection pieces 14a provided at the outer end of the cylinder of the piston rod 14 and a front and rear pair disposed at the same distance as the distance between the origins in the stroke range of the piston rod 14 outside the cylinder. Can be performed by the proximity switches 14b and 14c.
[0032]
When the electric motor 24 rotates forward in such a setting, the piston 15 moves forward from the forward operation origin A to the backward operation origin B. As a result, the position where the detection piece 14a reaches the proximity switch 14b becomes the retreat operation origin B, and the rotation of the electric motor 24 stops. When the electric motor 24 rotates in the reverse direction, the piston 15 moves backward from the backward operation origin B to the forward operation origin A, and when the detection piece 14a reaches the proximity switch 14c, it becomes the backward operation origin B. The rotation of 24 stops. Therefore, since the piston 15 always starts moving forward and backward from the operation origin, even if the area of the front and rear surfaces of the piston is the same, the deviation of the piston 15 caused by the area difference between the front surface and the rear surface of the first hydraulic cylinder 10 is not affected. This does not occur, and the set stroke between both ends of the cylinder reciprocates.
[0033]
In the case where the rotary injection molding machine is a vertical type, the turntable provided in the horizontal direction in the above embodiment is only provided vertically on the machine base together with the first hydraulic cylinder, and other changes are required. However, the present invention can be applied to a vertical rotary injection molding machine as it is.
[Brief description of the drawings]
FIG. 1 is a side view of a rotary injection molding machine employing a turntable advance / retreat moving mechanism according to the present invention.
FIG. 2 is an explanatory diagram of a first embodiment of a turntable advance / retreat moving mechanism according to the present invention.
FIG. 3 is an explanatory diagram of a second embodiment.
FIG. 4 is an explanatory diagram of a third embodiment.
[Explanation of symbols]
5 Movable platen 7 Turntable 8 Piston 8a Front surface 8b Rear surface 9 Rotary shaft 10 First hydraulic cylinder 10a Front room 10b Rear room 13 Second hydraulic cylinder 13a Front room 13b Rear room 14 Piston rod 14a Detection piece 14b, 14c Proximity switch 15 Piston 15a Front surface 15b Rear surface 16, 17 Hydraulic path 18 Auxiliary tank 19 Electromagnetic valve 21 Ball screw shaft 23 Ball nut member 24 Electric motor

Claims (6)

In a rotary injection molding machine in which a turntable for installing a mold is supported on a central rotating shaft and provided on a movable platen or a machine side, and the rotating shaft is pressed by hydraulic pressure to move the turntable forward and backward.
A second hydraulic cylinder for generating hydraulic pressure, which is provided with a double rod-shaped piston, is connected to a first hydraulic cylinder in which the above-mentioned rotary shaft is housed as a piston rod by a hydraulic path and provided. The driving device comprises an electric motor, a ball nut member at a fixed position rotated by the electric motor, and a ball screw shaft screwed to the ball nut member and having a shaft end connected to the piston. Turntable reciprocating mechanism for rotary injection molding machines. The second hydraulic cylinder is provided by connecting the front chambers and the rear chambers to the first hydraulic cylinder by hydraulic paths. When there is an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder, 2. The rotary injection molding according to claim 1, wherein the area ratio between the front and rear surfaces of the piston of the second hydraulic cylinder is made the same as the area ratio between the front and rear surfaces of the piston of the first hydraulic cylinder. Machine turntable forward and backward movement mechanism. The second hydraulic cylinder is provided by connecting the front chambers and the rear chambers to the first hydraulic cylinder by hydraulic paths, and is provided when there is an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder. The turntable advance / retreat movement mechanism for a rotary injection molding machine according to claim 1, wherein an auxiliary tank is provided in the hydraulic path. 4. The turntable advance / retreat movement mechanism for a rotary injection molding machine according to claim 3, wherein both ends of the second hydraulic cylinder are set as a forward movement origin and a backward movement origin of piston movement. The control means for controlling the movement of the piston of the second hydraulic cylinder is provided at the same distance as the movement distance between the detection piece provided at the outer end of the piston rod and the stroke range of the piston rod outside the cylinder. The turntable advance / retreat movement mechanism for a rotary injection molding machine according to any one of claims 1 to 4, comprising a pair of proximity switches arranged before and after. The rotary injection molding machine according to any one of claims 1 to 4, wherein the control means for controlling the movement of the piston of the second hydraulic cylinder comprises an encoder built in an electric servomotor provided in the drive device. Turntable reciprocating mechanism.

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