JP4169336B2 - Turntable advance / retreat mechanism of rotary injection molding machine - Google Patents

Description

[0001]
BACKGROUND 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 mold setting turntable is supported by a central rotating shaft and can be moved forward and backward by hydraulic pressure. Is.
[0002]
[Prior art]
In a conventional rotary injection molding machine that transfers the mold by rotating the turntable, a piston is connected to the rotary shaft at the center of the table and is provided on the movable plate so that the rotary shaft can be moved forward and backward by hydraulic pressure. At the time of transfer, the turntable is moved forward and away from the movable platen, and at the time of mold clamping, it is brought into close contact with the movable platen by moving backward (see, for example, Patent Document 1).
There is also a type in which a rotary shaft of a turntable provided on a machine base is used as a piston rod, and the rotary shaft is moved back and forth by hydraulic pressure (see, for example, Patent Document 2).
[0003]
As a driving means of a hydraulic control cylinder with respect to an injection cylinder, it is known to convert a rotary motion transmitted from an electric motor into a linear motion of a plunger by a ball screw shaft, and to perform hydraulic pressure generation control by the plunger (for example, Patent Document) 3).
Also, as the driving means for the pressure increasing cylinder of the clamping cylinder, the rotational movement transmitted from the electric motor to the ball nut member is converted into the linear motion of the pressure increasing piston by the ball screw shaft to increase the pressure of the clamping cylinder. There are some (see, for example, Patent Document 4).
[0004]
[Patent Document 1]
JP 2002-79558 A (page 2-3, FIG. 1).
[Patent Document 2]
JP 2000-84941 A (page 3, FIG. 2).
[Patent Document 3]
JP-A-11-268092 (page 4-5, FIG. 1).
[Patent Document 4]
Japanese Patent Laid-Open No. 2002-2060 (first page, FIG. 1).
[0005]
[Problems to be solved by the invention]
As described in Patent Documents 1 and 2, when the turntable is moved forward and backward by pressurizing the rotating shaft with hydraulic pressure, a hydraulic pump and its associated equipment are required as the pressure generation source. In a molding machine that uses hydraulic pressure as a driving source such as a mold clamping mechanism, an injection mechanism, and a nozzle touch device, there is no particular problem because these driving 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 back and forth by hydraulic pressure, a hydraulic pump is required as a drive source in addition to the electric motor. A molding machine provided with different types of drive sources is not preferable from the viewpoint of maintenance and management as well as configuration. Therefore, it is performed by a machine using an electric motor as a drive source, but the structure is more complicated than when the rotary shaft is pressurized by hydraulic pressure, and the forward dimension for separating the turntable from the movable platen or the machine base is 2 to 3 mm. Therefore, the control is more difficult than the hydraulic pressure, and there is a problem in responsiveness.
[0007]
On the other hand, as described in Cited Document 3, the generation of hydraulic pressure is performed by converting the rotary motion transmitted from the electric motor into a linear motion by the ball screw shaft, not by the hydraulic pump. By rotating the screwed ball screw shaft and pressurizing the pressure oil in the cylinder by the plunger, two hydraulic control cylinders for the front chamber and the rear chamber are required. In addition, since both are driven and controlled by separate electric motors, such a hydraulic control cylinder can be applied to the pressurizing movement of the rotary shaft by hydraulic pressure so that the turntable can be advanced and retracted hydraulically. It is difficult to make.
[0008]
Further, in Patent Document 2, a ball nut member is attached to a hollow, double rod type pressure increasing piston, and the rotation of the ball screw shaft screwed to the ball nut member is changed to a linear motion by the ball nut member, and the pressure increasing piston is advanced and retracted. It is possible to increase the pressure in the rear chamber of the clamping cylinder, but since the ball nut member is used for both the movement of the ball screw shaft and the movement of the pressure increasing piston, the cylinder including the ball nut member The surrounding structure is complicated, and it is difficult to apply to the pressurizing movement of the rotating shaft by hydraulic pressure.
[0009]
The present invention has been conceived in order to solve the above-mentioned problems, and its purpose is to generate oil pressure using an electric motor as a drive source, thereby pressurizing the rotating shaft and moving the turntable forward and backward. Even so, an object of the present invention is to provide a turntable advance / retreat mechanism equipped with an oil pressure generating cylinder that can be applied to an electric rotary injection molding machine with a simple structure by employing a means of connecting a piston rod and a ball screw shaft.
[0010]
[Means for Solving the Problems]
This invention according to the above object is a rotary type in which a turntable for mold installation is supported by a central rotary shaft and provided on the movable platen or the machine base, and the rotary shaft is moved forward and backward by pressurizing the rotary shaft with hydraulic pressure. in the injection molding machine, made of the rotation shaft from the first hydraulic cylinder which is furnished as a piston rod, a second hydraulic cylinder for the hydraulic power generation provided with the double-rod type piston, the second hydraulic cylinder The drive device comprises an electric motor, a ball nut member at a fixed position rotated by the electric motor, and a ball screw shaft screwed into the ball nut member and having a shaft end connected to a piston, and the second hydraulic pressure The front chamber and the rear chamber of the cylinder and the first hydraulic cylinder are connected by a hydraulic path .
[0011]
Further, according to the present invention, in the above configuration, when there is an area difference between the piston front surface and the rear surface of the first hydraulic cylinder, the area ratio between the piston front surface and the rear surface of the second hydraulic cylinder is set to the piston ratio of the first hydraulic cylinder. The area ratio between the front surface and the rear surface is the same.
[0012]
According to the present invention, in the above structure, when there is a difference in area between the front surface and the rear surface of the piston of the first hydraulic cylinder, an auxiliary tank is provided in the hydraulic path, and the second hydraulic cylinder is provided. Are set as the forward operation origin and the backward operation origin of piston movement.
[0013]
Further, the piston movement control means of the second hydraulic cylinder is arranged in the stroke of the piston rod outside the cylinder and the stroke range of the piston rod outside the cylinder with the same distance as the movement distance. It consists of a set of proximity switches provided before and after, or it consists of an encoder built in an electric servo motor included in the drive device.
[0014]
In the above configuration, since the hydraulic pressure is generated by the electric motor to move the rotary shaft together with the turntable, the hydraulic pump and its associated equipment are not required and noise is reduced while the rotary shaft is advanced and retracted hydraulically. . The structure of the rotary shaft and the first hydraulic cylinder may be the same as that of the case where the hydraulic pump is used as a drive source, and can be diverted to an electric molding machine using all the drive sources as electric motors.
[0015]
In addition, a double rod type is adopted for the piston of the second hydraulic cylinder, and the piston rod is directly operated together with the ball screw shaft, so that transmission efficiency is good, and there is an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder. However, since the area ratio between the front and rear surfaces of the piston of the second hydraulic cylinder is the same, or the oil amount in the cylinder is always set to a predetermined amount by the oil amount control by the auxiliary tank of the hydraulic circuit, the turntable is repeatedly performed. Even in the forward and backward movement, the oil amount balance is maintained, and even if the amount of pressurized oil supplied to and discharged from the front and rear chambers of the first hydraulic cylinder is small, the rotary shaft is reliably pressurized to move the turntable forward and backward. You can 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, so the piston of the first hydraulic cylinder The piston movement of the set stroke can be repeated without being affected by the difference in area between the front surface and the rear surface.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to a horizontal rotary injection molding machine shown in the drawings.
In FIG. 1, reference numeral 1 is a pressure receiving plate, 2 is a fixed plate, and is erected on a machine base 4 connected by a tie bar 3. Reference numeral 5 denotes a movable plate which is inserted through the tie bar 3 and provided between the pressure receiving plate 1 and the fixed plate 2, and a toggle mechanism 6 is connected between the back portion and the pressure receiving plate 1.
[0018]
On the front surface of the movable platen 5 facing the fixed platen 2, there is provided a turntable 7 that makes a half rotation or a single rotation by gear transmission with a rotation driving device (not shown). The turntable 7 has a rotating shaft 9 having a piston 8 (see FIG. 2) around the shaft at the center of the back surface, and the rotating shaft 9 is inserted into the hydraulic cylinder 10 in the movable plate as a piston rod so as to be able to rotate and advance and retract. In addition, it 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 (one in the figure) of molds 12 for closing the mold. Reference numeral 13 denotes a second hydraulic cylinder, which will be described later, reference numeral 18 denotes an auxiliary tank of the second hydraulic cylinder 13, and reference numeral 20 denotes a driving device.
[0019]
In FIG. 2, 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 includes a double rod-shaped piston 15 having piston rods 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. .
[0020]
In addition, the cylinder capacity of the second hydraulic cylinder is determined in relation to the cylinder capacity of the first hydraulic cylinder 10 set from the separation dimension of the turntable 7, but as shown in FIG. When the piston front surface 8a and the rear surface 8b of 10 have the same area, if the areas of the front surface 15a and the rear surface 15b of the piston 15 in the second hydraulic cylinder 13 are also set to be the same, there is a difference in the amount of pressure oil flowing in and out between the cylinders. Therefore, the turntable 7 can be moved forward and backward by repeating the set stroke and reciprocating the piston 15.
[0021]
Further, the forward / backward control of the piston 15 is performed in the same manner as before and after the detection piece 14a provided at the outer end of the cylinder of the piston rod 14 and the stroke range of the piston rod 14 outside the cylinder with the same distance as the moving distance. This can be done by a pair of proximity switches 14b, 14c.
[0022]
Reference numeral 20 denotes a driving device for the second hydraulic cylinder 13, which is connected to the piston rod 14 with a shaft end and a ball screw shaft 21 provided on the same axis line, and screwed with the ball screw shaft 21, so A ball nut member 23 in 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 attached to the drive shafts of the ball nut member 23 and the electric motor 24. And a timing belt 27 hung on.
[0023]
Further, when an electric servo motor incorporating an encoder is adopted as the electric motor 24 of the drive device 20, the rotation speed of the ball screw shaft 21 detected by the encoder can be calculated and converted into the movement amount of the piston 15, so 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 through the timing belt 27, and the rotation of the ball nut member 23 is converted into a linear motion of the piston rod 14 by the ball screw shaft 21. . The moving direction of the piston rod 14 is determined by the rotating direction of the electric motor 24.
[0025]
When the piston 15 moves forward by the forward rotation of the electric motor 24, the pressure oil in the rear chamber 13b is compressed by the piston 15 until the detection piece 14a reaches the proximity switch 14b and the rotation of the electric motor 24 stops. The first hydraulic cylinder 10 is press-fitted into the rear chamber 10b. 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 that also serves as a piston moves forward. As a result, the turntable 7 of the same body also moves and is easily rotated away from the front surface of the movable platen 5.
[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 moved to the piston 15 until the detection piece 14a reaches the proximity switch 14c and the electric motor 24 stops rotating. Is pressed into the front chamber 10 a of the first hydraulic cylinder 10. Accordingly, the pressure oil in the rear chamber 10 b is returned to the rear chamber 13 b of the second hydraulic cylinder 13, and the rotary shaft 9 returns to the original position together with the turntable 7. Withstands mold clamping force.
[0027]
FIG. 3 shows the second hydraulic cylinder 13 when the area of the piston front surface 8a of the first hydraulic cylinder 10 is larger than the area of the rear surface 8b and there is an area difference there. In this case, if the area ratio between the piston front surface 15a and the rear surface 15b is the same as the area ratio between the piston front surface 8a and the rear surface 8b of the first hydraulic cylinder 10, the difference in the amount of pressure oil flowing in and out between the two cylinders is determined from the area ratio. Therefore, even if the piston 15 is reciprocated repeatedly, the piston 15 is not displaced and the turntable 7 can be moved back and forth.
[0028]
FIG. 4 shows that even if there is an area difference between the piston front surface 8a and the rear surface 8b of the first hydraulic cylinder 10, the areas of the front surface 15a and the rear surface 15b of the piston 15 are the same, resulting from the difference in the area ratio of both cylinders. This shows a case where the difference in the amount of pressure oil flowing in and out of the front and rear chambers is eliminated by employing 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 when the piston 15 moves forward, the electromagnetic valve 19 is switched to the symbol b side, and the auxiliary tank 18, the hydraulic path 16, Connect. As a result, the pressure oil from the auxiliary tank 18 supplements the pressure oil flowing from the front chamber 10 a of the first hydraulic cylinder 10 into the front chamber 13 a of the second hydraulic cylinder 10, and excess pressure oil is provided in the hydraulic path 16. Discharged from the valve 19a.
[0030]
Further, at the time of backward movement, the electromagnetic valve 19 is switched to the symbol a side, and the auxiliary tank 18 and the hydraulic path 17 are connected. As a result, 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. Such a valve switching operation avoids the difference in the amount of pressure oil flowing in and out due to the difference in the area of the front and rear surfaces of the first hydraulic cylinder 10, so that even if the piston 15 is reciprocated repeatedly, the position of the piston 15 is displaced. The turntable 7 can be moved forward and backward.
[0031]
The movement of the piston 15 is preferably controlled 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. Further, the movement control of the piston 15 is performed by a pair of front and rear disposed at the same distance as the distance between the origins in the stroke range of the detection piece 14a provided at the cylinder outer end of the piston rod 14 and the piston rod 14 outside the cylinder. The proximity switches 14b and 14c can be used.
[0032]
When the electric motor 24 operates in the forward rotation with such 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 reverse operation origin B, and the rotation of the electric motor 24 stops. When the electric motor 24 is operated in reverse rotation, the piston 15 moves backward from the reverse operation origin B to the forward operation origin A, and the position where the detection piece 14a reaches the proximity switch 14c becomes the reverse 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 front and rear surface areas of the piston are the same, the displacement 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. The set stroke between both ends of the cylinder does not occur and reciprocates.
[0033]
When the rotary injection molding machine is a vertical type, the turntable provided sideways 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 directly applied to a vertical rotary injection molding machine.
[Brief description of the drawings]
FIG. 1 is a side view of a rotary injection molding machine employing a turntable advance / retreat mechanism according to the present invention.
FIG. 2 is an explanatory diagram of a first embodiment of a turntable advance / retreat mechanism according to the present invention.
FIG. 3 is also an explanatory diagram of a second embodiment.
FIG. 4 is also an explanatory diagram of a third embodiment.
[Explanation of symbols]
5 Movable platen 7 Turntable 8 Piston 8a Front surface 8b Rear surface 9 Rotating shaft 10 First hydraulic cylinder 10a Front chamber 10b Rear chamber 13 Second hydraulic cylinder 13a Front chamber 13b Rear chamber 14 Piston rod 14a Detection pieces 14b, 14c Proximity switch 15 Piston 15a Front 15b Rear 16 and 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 that supports a mold setting turntable by a central rotating shaft and is provided on the movable platen or the machine base side, pressurizes the rotating shaft by hydraulic pressure, and moves the turntable back and forth.
A first hydraulic cylinder having the rotary shaft as a piston rod, and a second hydraulic cylinder for generating hydraulic pressure having a double-rod piston ;
The drive device for the second hydraulic cylinder comprises an electric motor, a ball nut member at a fixed position rotated by the electric motor, and a ball screw shaft screwed into the ball nut member and having a shaft end connected to a piston. And
A turntable advance / retreat mechanism for a rotary injection molding machine, wherein the second hydraulic cylinder and the front chambers and rear chambers of the first hydraulic cylinder are connected by a hydraulic path . In the above configuration according to claim 1, when there is an area difference between the piston front surface and the rear surface of the first hydraulic cylinder, the area ratio between the piston front surface and the rear surface of the second hydraulic cylinder is set to A turntable advance / retreat mechanism for a rotary injection molding machine, characterized in that the area ratio between the front surface and the rear surface of the piston is the same. 2. The turntable for a rotary injection molding machine according to claim 1 , wherein an auxiliary tank is provided in the hydraulic path when there is an area difference between the front surface and the rear surface of the piston of the first hydraulic cylinder. Advance and retreat mechanism.   4. The turntable advance / retreat mechanism of the rotary injection molding machine according to claim 3, wherein both ends of the second hydraulic cylinder are set as a forward operation origin and a reverse operation origin of piston movement.   The piston hydraulic control means of the second hydraulic cylinder is arranged at the same distance as the moving distance in the stroke of the piston rod outside the cylinder and the detection piece provided on the piston rod outside the cylinder. The turntable advance / retreat mechanism for a rotary injection molding machine according to any one of claims 1 to 4, wherein the turntable advance / retreat mechanism comprises a set of proximity switches arranged in front and rear.   The rotary injection molding machine according to any one of claims 1 to 4, wherein the piston movement control means of the second hydraulic cylinder comprises an encoder built in an electric servo motor provided in the driving device. Turntable advance / retreat mechanism.

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