JP2003145591A - Ejector device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the life of an ejector device from becoming short by the generation of overload more than rated ejection force. SOLUTION: The ejector device has a drive part for ejection, a motion direction conversion part for converting rotary motion to linear motion, a linear motion transmission part receiving linear motion to transmit the same to an ejector rod 23, an impact absorption device 65 for absorbing the impact accompanying the advance of the ejector rod 23, an impact absorbing state detection part for detecting the impact absorbing state due to the impact absorption device 65 and a drive part stopping processing means for stopping the driving of the drive part on the basis of the detection result. When an impact can not be sufficiently absorbed by the impact absorption device 65 because of the generation of overload more than rated ejection force, the driving of the driving part is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ejector device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is charged (filled) into a cavity space of a mold device at a high pressure, cooled in the cavity space, and solidified. By doing so, a molded product is obtained.

The mold apparatus comprises a fixed mold and a movable mold, and the movable mold is moved forward and backward by a toggle mechanism.
By contacting and separating from the fixed mold, mold closing, mold clamping and mold opening can be performed, and a cavity space is formed between the fixed mold and the movable mold during mold clamping. Has become. Then, when the mold is opened, the movable mold is retracted while leaving the molded product, and subsequently, the molded product is ejected by the ejector device to perform the mold release.

Therefore, in the ejector device, the ejector pin is disposed with its front end facing the cavity space and its rear end fixed to the ejector plate. Further, an ejector pin feeding device is connected to the rear end of the ejector plate via an ejector rod. Then, when the ejector pin feeding device is operated to move the ejector plate forward through the ejector rod, the ejector pin fixed to the ejector plate is moved forward.

By the way, normally, the ejector pin feeding device can be operated by driving a motor.

FIG. 2 is a sectional view showing a main part of a conventional ejector device.

In the figure, 11 is a movable platen,
A movable mold (not shown) is attached to the front end (right end in the figure) of the movable platen 11. The movable platen 1
A fixed platen (not shown) is disposed so as to face 1
A fixed mold (not shown) is attached to the fixed platen so as to face the movable mold, and a mold device is formed by the fixed mold and the movable mold. Further, the movable platen 11 is advanced and retracted along a tie bar (not shown) by a toggle mechanism (not shown) arranged at the rear end (the left end in the drawing) to close the mold, close the mold, and open the mold. Done. Then, when the mold is clamped, a cavity space is formed between the fixed mold and the movable mold, and the melted resin is filled in the cavity space and cooled to form a molded product.

By the way, when the mold is opened, the movable mold is retracted while leaving the molded product, and subsequently, the molded product in the cavity is ejected by the ejector device to release the mold.

Therefore, in the ejector device, an ejector pin (not shown) is disposed with its front end facing the cavity space and its rear end fixed to an ejector plate (not shown). An ejector pin feeding device 16 is connected to the rear end of the ejector plate. Then, when the ejector pin feeding device 16 is operated and the ejector plate is moved forward, the ejector pin fixed to the ejector plate is moved forward.

By the way, the ejector pin feeding device 1
At least a portion of the movable platen 6 is housed in a recess 12 formed in the rear end surface (left end surface in the drawing) of the movable platen 11, and a plurality of guide bars 18 (only two guide bars 18 are shown in the drawing). A drive unit 21 attached to the movable platen 11 via a ball screw 22, a ball screw 22 as a motion direction conversion unit that receives a rotation generated by the drive unit 21, and converts the rotation motion into a rectilinear motion without rotation; The ejector rod 23 is provided as a rectilinear motion transmission unit that transmits the rectilinear motion generated by the screw 22 to the ejector pin and advances the ejector pin.

The drive unit 21 includes a front plate 2
5, a drive unit frame 2 including a rear plate 26, and a tubular body 27 connecting the front plate 25 and the rear plate 26.
8, a servo motor 31 as a drive unit housed in the drive unit frame 28, a hollow output shaft 32 that outputs the rotation generated by driving the servo motor 31, and the output shaft. The encoder 33 is attached to the rear end of the encoder 32 and detects the rotational speed of the output shaft 32 to detect the rotational speed of the servo motor 31. A threaded portion 46 is formed at the front end of each of the guide bars 18, and the threaded portion 46 is screwed into the movable platen 11.

The servo motor 31 includes a stator 35 attached to the tubular body 27 and the stator 3.
5 is provided with a rotor 36 rotatably arranged,
The stator 35 includes a core 38 and a coil 39.
The output shaft 32 is rotatably mounted on the drive unit frame 28, and has a front end rotatably attached to the front plate 25 by a bearing b1 and a rear end rotatably attached to a rear plate 26 by a bearing b2.

The ball screw 22 has an output shaft 32.
A ball nut 43 attached to the front end of the ball nut, and a ball screw shaft 44 that is screwed with the ball nut 43 and is arranged so as to move forward and backward (moving in the left-right direction in the drawing). The front end of 44 is the crosshead 4
5, the rear end of the ejector rod 23 is attached to the crosshead 45. The crosshead 45 is slidably arranged along the guide bar 18, functions as a rotation stopper for the ball screw shaft 44, and is moved forward and backward as the ball screw shaft 44 moves forward and backward. The ejector rod 23 is moved back and forth. A hole 47 is formed at the center of the movable platen 11, and the ejector rod 23 extends through the hole 47.

Therefore, when the servo motor 31 is driven and the ball nut 43 is rotated via the output shaft 32, the ball screw shaft 44 can be moved forward and backward, and the ejector rod 23 can be moved forward and backward.

By the way, when the ejector rod 23 is moved forward (moved to the right in the figure) and the ejector pin is moved forward through the ejector plate to eject the molded product, in the case of a hydraulic ejector device, the forward movement limit is set. The ejector plate can be rapidly stopped at the position, but in the case of the electric ejector device using the servo motor 31, the ball nut 43 has inertia, so the ejector plate is rapidly stopped at the forward limit position. I can't. Therefore, in the case of the electric ejector device, the rotation speed of the servo motor 31 is controlled so that the servo motor 31 is decelerated before the ejector plate reaches the forward limit position, and the ejector plate reaches the forward limit position. I'm trying to stop it.

[0016]

However, in the above-mentioned conventional electric ejector device, if the rotational speed of the servo motor 31 is set incorrectly, the servo motor 31 is stopped when the ejector plate reaches the forward limit position. However, the overload due to the inertia of the ball nut 43 is applied to the mechanism of the ejector pin feeding device 16 as a shock.

Therefore, in order to absorb the impact, a spring (not shown) as a buffer member is provided between the crosshead 45 and the ejector rod 23, and when the ejector plate reaches the forward limit position. When an overload exceeding the rated rush output occurs, the spring may be contracted to absorb the shock.

However, since it is possible to continue operating the ejector device while generating an overload exceeding the rated rush output, the spring cannot sufficiently absorb the shock, and the life of the ejector device is short. turn into.

The present invention provides an ejector device which solves the problems of the conventional electric ejector device and prevents the life of the ejector device from being shortened due to an overload of a rated rush output or more. The purpose is to do.

[0020]

To this end, in the ejector device of the present invention, a drive unit for protrusion attached to a predetermined portion of the support platen and a rotation generated by driving the drive unit. In response to this, a motion direction conversion unit that converts rotational motion into a rectilinear motion, a rectilinear motion transmission unit that receives the rectilinear motion and transmits it to the ejector rod, and a shock absorbing device that absorbs the shock accompanying the forward movement of the ejector rod. A shock absorbing state detecting section for detecting a state of shock absorption by the shock absorbing apparatus, and drive section stop processing means for stopping driving of the drive section based on a detection result by the shock absorbing state detecting section.

In another ejector device of the present invention,
Further, the impact absorbing device absorbs the impact by the urging member. Then, the shock absorption state detection unit detects the operation amount of the biasing member.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a main part of an ejector device according to an embodiment of the present invention.

In the figure, 11 is a movable platen as a support platen, and a movable mold (not shown) is attached to the front end (right end in the figure) of the movable platen 11. A fixed platen (not shown) is arranged so as to face the movable platen 11, and a fixed mold (not shown) is attached so as to face the movable mold on the fixed platen, and the mold is formed by the fixed mold and the movable mold. The device is formed. Further, the movable platen 11 is the movable platen 11
A toggle mechanism (not shown) arranged at the rear end (left end in the figure) advances and retreats along a tie bar (not shown) to perform mold closing, mold clamping and mold opening of the mold device. Then, when the mold is clamped, a cavity space is formed between the fixed mold and the movable mold, and the melted resin is filled in the cavity space and cooled to form a molded product.

By the way, when the mold is opened, the movable mold is retracted while leaving the molded product, and subsequently, the molded product in the cavity space is ejected by the ejector device to release the mold.

Therefore, in the ejector device, an ejector pin (not shown) is disposed with its front end facing the cavity space and its rear end fixed to an ejector plate (not shown). An ejector pin feed device 56 is connected to the rear end of the ejector plate. Then, when the ejector pin feeding device 56 is operated to move the ejector plate forward, the ejector pin fixed to the ejector plate is moved forward. The ejector pin is
When the mold release is completed, the ejector plate is moved backward by the urging force of a return spring (not shown) arranged in front of the ejector plate.

By the way, the ejector pin feeding device 5
At least a portion 6 of the movable platen 11 is housed in a recess 12 formed in the rear end surface (left end surface in the figure) of the movable platen 11. The concave portion 12 is a cone-shaped first accommodating portion 57 formed on the rear side (left side in the figure), and a medium diameter formed on the front side (right side in the figure) of the first accommodating section 57. The second accommodating portion 58 and the third accommodating portion 59 having a small diameter formed in front of the second accommodating portion 58.

The ejector pin feeding device 56 has a movable platen via an annular mounting plate 61 having a through hole h1 formed in the center and a plurality of guide bars 81 (only one guide bar 81 is shown in the drawing). 11, a drive unit 62 attached at a predetermined position of 11, and the drive unit 62
Generated by the ball screw 63 as a first motion direction conversion unit that converts the rotational motion into a linear motion with rotation, that is, a rotational linear motion, in response to the rotation generated by the ball screw 63. A bearing box 64 as a second motion direction conversion unit and a rectilinear motion transmission unit for converting the rotational rectilinear motion into a rectilinear motion without rotation, and an ejector pin (not shown) in response to the rectilinear motion generated in the bearing box 64 An ejector rod 23 as a transmission member for advancing the ejector pin, and an impact absorbing device 65 for absorbing an impact generated by the advancing of the ejector rod 23 and applied to the mechanism of the ejector pin feeding device 56. Prepare A rear end of the guide bar 81 is attached to a plurality of positions of the mounting plate 61, and a front end thereof is a bottom surface S1 of the second accommodating portion 58.
Is attached to the movable platen 11. The guide bar 81 also functions as a detent bar that prevents the bearing box 64 from rotating. In the present embodiment, the drive unit 62 is attached to the movable platen 11 via the attachment plate 61 and the guide bar 81. However, the drive unit 62 is not provided via the attachment plate 61, but only the guide bar 81. It can also be attached to the movable platen 11 via. Further, the drive unit 62 can be directly attached to the movable platen 11.

The drive unit 62 includes the mounting plate 61.
Fixed to the front plate 25, the rear plate 26, and a tubular body 27 connecting the front plate 25 and the rear plate 26.
A servo serving as a drive unit for protrusion, which is housed in the drive unit frame 28 and is attached to a predetermined position of the movable platen 11 via the drive unit frame 28 and the guide bar 81. A motor 31, a hollow output shaft 32 that outputs the rotation generated by driving the servo motor 31, and a rear end of the output shaft 32 and the ball screw 63 are provided. Unit 67 as a rotation transmission unit that transmits the rotation of the ball screw 63 to the ball screw 63, and as a detection unit that is attached to the spline unit 67 and detects the rotation speed of the output shaft 32 to detect the rotation speed of the servo motor 31. The encoder 33 of FIG. Although the encoder 33 is attached to the spline unit 67 in the present embodiment, the encoder 33 can be attached to the output shaft 32.

The servo motor 31 includes a stator 35 attached to the tubular body 27, and the stator 3.
5 is provided with a rotor 36 rotatably arranged,
The stator 35 includes a core 38 and a coil 39.
The output shaft 32 is rotatably arranged with respect to the drive unit frame 28, and has a front end rotatably attached to the front plate 25 by a bearing b1 and a rear end rotatably attached to a rear plate 26 by a bearing b2. To be

The spline unit 67 is attached to the rear end of the output shaft 32, extends forward in the output shaft 32 to almost the center in the axial direction, and has a spline formed on the inner peripheral surface thereof. Spline nut 68,
The spline nut 68 is spline-engaged with a rod-shaped spline shaft portion 69 having an outer peripheral surface on which a spline is formed, and the spline nut 68 and the spline shaft portion 69 are movable in the axial direction with respect to each other. It is arranged immovably in the circumferential direction. The ball screw 63 is formed integrally with the spline shaft portion 69,
A ball screw shaft portion 72 as a first conversion element that is arranged to move forward and backward (moves in the left-right direction in the figure), and is movable with respect to the spline unit 67 by being screwed into the ball screw shaft portion 72. And a ball nut 71 as a second conversion element attached to the bearing box 64 and the shock absorber 65. A shaft portion 73 is integrally formed at the front end of the ball screw shaft portion 72, and the spline shaft portion 69, the ball screw shaft portion 72 and the shaft portion 73 constitute a shaft unit 90. In the shaft unit 90, The spline shaft portion 69 constitutes a rear end portion (left end portion in the figure), the ball screw shaft portion 72 constitutes an intermediate portion, and the shaft portion 73 constitutes a front end portion (right end portion in the figure).

Therefore, a current is supplied to the coil 39 based on a command from the control unit 92, and the servo motor 31
When driven, the rotation generated in the rotor 36 is output to the output shaft 32 and transmitted from the output shaft 32 to the shaft unit 90 via the spline nut 68. At this time,
The rotation speed of the output shaft 32 and the rotation speed of the servo motor 31 are detected by the encoder 33, and a detection signal is sent to the control unit 92. When the rotation is transmitted to the shaft unit 90, the ball nut 71 and the ball screw shaft portion 72
The shaft unit 90 is moved forward (moved to the right in the figure) while being rotated by screwing with.

The bearing box 64 has its rear end fixed to the front end surface (right end surface in the figure) of the flange portion 70 of the ball nut 71, and has a cylindrical portion 74 and a diameter from the front end of the cylindrical portion 74. A housing 76 having a projecting portion 75 formed outward in the direction, and two bearings b for supporting the shaft portion 73 in the housing 76.
3, b4, a holding nut 77 for pressing the bearings b3, b4 to the stepped portion between the ball screw shaft portion 72 and the shaft portion 73, and a holding plate 78 for covering the front end portion of the shaft portion 73. Then, the rear end of the ejector rod 23 is attached to the holding plate 78, and the ejector rod 23
Extend forward along the same axis as the shaft unit 90, and the front end thereof is disposed in a hole 47 formed in the center of the movable platen 11.

The impact absorbing device 65 is attached to the rear end surface of the flange portion 70 and has a ball nut 71.
And a retainer 80 slidably arranged with respect to the stud 85, a rear end of the retainer 80 abutting on the mounting plate 61, a front end thereof abutting on the retainer 80, and a stud. A spring 82 as an impact absorbing member and an urging member in which 85 is inserted is provided, and the spring 82 urges the ball nut 71 and the bearing box 64 forward through the retainer 80 with a predetermined urging force. Energize. In addition, by the head portion of the stud 85,
Advancement of the retainer 80 beyond a predetermined limit is restricted.

Therefore, when the shaft unit 90 is rotated and moved forward, the housing 76 and the pressing plate 7 are moved.
8 is advanced and the ejector rod 23 is advanced.

As described above, when the servo motor 31 is driven in the positive direction and the shaft unit 90 is rotated in the positive direction via the output shaft 32, the shaft unit 90 is advanced and the ejector rod 23 is advanced. The ejector pin can be advanced through the ejector plate to eject the molded product. Further, when the servo motor 31 is driven in the reverse direction and the shaft unit 90 is rotated in the reverse direction via the output shaft 32, the shaft unit 90 is retracted (moved to the left in the figure), and the ejector rod 23 is moved. Retreat.
At this time, the ejector pin is retracted via the ejector plate by the urging force of the return spring.

By the way, if the rotation speed of the servo motor 31 is set incorrectly and the ejector plate cannot be stopped when it reaches the forward limit position, an overload due to the forward movement of the shaft unit 90 causes an ejector pin feed device 56.
Will be added as a shock to the mechanism.

Therefore, the shaft unit 90 and the movable platen 1
1, or between the drive unit 62 and the shock absorber 65.
Since the spring 82 can absorb the impact applied to the mechanism of the ejector pin feeding device 56, even if an overload of the rated rush output or more occurs at the time when the ejector plate reaches the forward limit position, Spring 8
2 contracts to absorb the impact. At this time, the retainer 80 is retracted as the spring 82 is contracted.

However, if the ejector device is continuously operated while an overload exceeding the rated rush output is generated, the impact cannot be sufficiently absorbed by the spring 82, and the life of the ejector device is shortened.

Therefore, in the vicinity of the boundary between the first accommodating portion 57 and the second accommodating portion 58 of the movable platen 11,
Proximity sensor 94 as a position detecting unit that faces the retainer 80 and detects the position of the retainer 80, and a shock absorbing state detecting unit that detects the state of shock absorption represented by the amount of contraction as the operating amount of the spring 82. Is arranged,
The detection result of the proximity sensor 94 is sent to the control unit 92 as a detection signal. The proximity sensor 94 is turned on when the retainer 80 is within a predetermined range, generates a predetermined sensor output, and is turned off when the retainer 80 is outside the predetermined range.

A drive unit stop processing means (not shown) of the control unit 92 performs drive unit stop processing, and the proximity sensor 9
Based on the detection signal from 4, the position of the retainer 80 is determined and the impact absorption state of the spring 82 is determined. Then, an overload exceeding the rated rush output occurs, the retainer 80 is out of the predetermined range, and the spring 8
When the shrinkage amount of 2 is larger than a threshold value, the driving of other drive units such as the measuring motor and the injection motor of the injection device, the mold clamping motor of the mold clamping device, and the servo motor are stopped. The driving of 31 is stopped and the molding by the injection molding machine is stopped.

As described above, when the shock cannot be sufficiently absorbed by the spring 82, the driving of the servo motor 31 is stopped and the ejector device cannot be continuously operated. Therefore, the life of the ejector device is reduced. It is possible to prevent shortening.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention, and they are not excluded from the scope of the present invention.

[0044]

As described above in detail, according to the present invention, in the ejector device, a drive unit for protrusion attached to a predetermined position of the support platen and a drive unit for driving the drive unit are generated. In response to the rotation that was made,
A motion direction conversion unit that converts a rotational motion into a linear motion, a linear motion transmission unit that receives the linear motion and transmits the linear motion to an ejector rod, a shock absorbing device that absorbs a shock accompanying the forward movement of the ejector rod, and the shock absorbing unit. The apparatus includes a shock absorption state detection unit that detects a state of shock absorption by the device, and a drive unit stop processing unit that stops driving of the drive unit based on a detection result of the shock absorption state detection unit.

In this case, when the impact absorbing device cannot sufficiently absorb the impact due to the occurrence of overload exceeding the rated rush output, the drive of the drive unit is stopped and the ejector device is operated. Since it becomes impossible to continue, it is possible to prevent the life of the ejector device from being shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an ejector device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a conventional ejector device.

[Explanation of symbols]

11 Movable platen 23 Ejector rod 31 Servo motor 63 ball screw 64 bearing box 65 Shock absorber 82 spring 92 Control unit 94 Proximity sensor

Claims (2)

[Claims] 1. A linear motion of a rotary drive is received by (a) a drive unit for protrusion attached to a predetermined position of a support platen, and (b) a rotation generated by driving the drive unit. (C) a linear motion transmitting unit that receives the linear motion and transmits the linear motion to the ejector rod; and (d) a shock absorbing device that absorbs the shock accompanying the forward movement of the ejector rod, ) A shock absorbing state detecting section for detecting a state of shock absorption by the shock absorbing apparatus, and (f) a drive section stop processing means for stopping driving of the drive section based on a detection result by the shock absorbing state detecting section. An ejector device comprising: 2. The ejector device according to claim 1, wherein (a) the shock absorbing device absorbs a shock by a biasing member, and (b) the shock absorbing state detecting unit detects a movement amount of the biasing member.