JPH05345340A - Locking device for injection molding machine - Google Patents

Abstract

PURPOSE:To simplify the movement of a mold lock ram, to ensure actuation at the time of mold release, and to reduce the size of a device. CONSTITUTION:During mold opening and closing, a nut member 13 is rotated by a motor M, and a male screw fixed on a movable disk 3 is moved in the direction of an arrow C or an arrow D. A sliding abutment surface S slides to permit the rotation of the nut member. During mold lock, a brake 27 is actuated to stop the nut member, and pressure oil is supplied to a hydraulic chamber B for mold lock. A mold lock ram 12, together with the nut member 13 and the male screw 9, is moved in the direction of the arrow C through the sliding abutment surface S. On the other hand, during mold release, pressure oil is supplied to a hydraulic chamber A for mold release, and the mold lock ram 12, together with the nut member and the male screw, is moved in the direction of the arrow D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device in an injection molding machine, and more particularly to a hybrid type mold clamping device using a rotary motor and a hydraulic actuator.

[0002]

2. Description of the Related Art Recently, as a hybrid type mold clamping device using an electric motor and a hydraulic actuator, for example, JP-A-2-45111 and JP-A-2-121807.
Japanese Patent Application Laid-Open No. 2-143812 and Japanese Patent Laid-Open No. 2-143812 have been proposed.

In the hybrid type mold clamping device, a ball screw and a nut driven by a transmission motor, a mold clamping ram for generating a mold clamping force by hydraulic pressure, and a rotation of the ball nut by contacting the mold clamping ram. And a friction clutch section for stopping the.

When the mold is opened and closed, the ball nut is rotated based on the electric motor to move the ball screw forward and backward to move the movable plate connected to the tip of the screw. During mold clamping, the mold clamping ram is moved by hydraulic pressure, and the friction clutch portion of the ram contacts the ball nut to prevent the ball nut from rotating along the lead of the ball screw. The ram moves the ball screw together with the nut to generate a large tightening force on the movable plate.

[0005]

By the way, the above-described mold clamping device has a structure in which the friction clutch portion prevents rotation of the ball nut during mold clamping, so that the mold is opened and closed by rotating the ball nut to move the ball screw. It is necessary to open the friction clutch part. For this reason, the mold clamping ram needs to move by the engagement and disengagement stroke of the friction clutch portion in addition to the mold clamping stroke by hydraulic pressure, and a special pressure oil chamber for the clutch engagement and disengagement stroke (Japanese Patent Laid-Open No. 2-45111). ,)
And a spring (Japanese Patent Laid-Open Nos. 2-121807 and 2-14381).

Therefore, the mold clamping device has a complicated structure and complicated movement control of the clamping ram.

Further, in the above-described mold clamping device, hydraulic pressure is used during mold clamping that requires a large force, and an electric motor is used during mold opening / closing that does not require a large force. At the time of releasing the mold from the molding resin, a relatively large force is required to move the mold against the adhesive force of the resin. However, since the movable platen is moved by the electric motor even when the mold is released, the mold clamping device requires a relatively large electric motor, and combined with the adoption of the ball screw device having a large inertia, the mold clamping device is required. This is a cause of increasing the size and increasing the cost.

In view of the above, the present invention eliminates the above-mentioned clutch portion to simplify the movement of the mold clamping ram, and operates the movable platen by hydraulic pressure at the time of releasing the mold so that the mold clamping in the injection molding machine can be achieved. The purpose is to provide a device.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is linked to a male screw (9) fixed to a movable plate (3) and a rotary motor (M), and A nut member (13) screwed to the male screw, and a mold clamping ram (12) rotatably supporting the nut member and movably supported by a back plate (5) in a predetermined axial direction. A mold clamping device in an injection molding machine, comprising: a mold clamping hydraulic chamber (B) for supplying a hydraulic pressure to move the mold clamping ram (12) in a mold closing direction during mold clamping; At the time, a mold release hydraulic chamber (A) that is supplied with hydraulic pressure to move the mold clamping ram (12) in the mold opening direction, and the nut member (13) has the male screw ( 9) Rotation preventing means (27, 27 ') (M, 9) for preventing rotation between
And a side surface (13a) of the nut member and a flat surface portion (40) of the mold clamping ram, the rotation of the nut member (13) based on the rotation motor (M) during mold opening and closing. Allowed by sliding, and at the time of mold clamping, the mold clamping ram (1
And a sliding contact surface (S) for transmitting the movement of 2) to the nut member (13).

As an example, the rotation preventing means is a brake (27, 27 ') that acts on a transmission path from the rotation motor (M) to the nut member (13) to stop the rotation of the nut member. ..

As another example, the male screw (9) and the nut member (13) are feed screws such as a square screw or a trapezoidal screw, and the rotation preventing means is the rotation motor itself in a stopped and held state. (M) and / or the lead screw itself (9, 13) in which the lead angle is set small.

[0012]

[Operation] Based on the above configuration, when the mold is closed, the rotary motor (M)
To rotate the nut member (13) in the positive direction. Then, the male screw (9) screwed to the nut member (13) moves in the direction of arrow C to reach the mold closed position. At this time, the sliding contact surface (S) is in contact, but since the pressing force at the time of mold closing is small, the nut member (13) is rotatably supported (2).
0), the sliding contact surface (S) allows the nut member (13) to rotate smoothly by sliding.

At the time of mold clamping, while the rotation of the nut member (13) is blocked by the rotation preventing means such as the brake (27),
The hydraulic pressure is supplied to the mold clamping hydraulic chamber (B). Then, the mold clamping ram (12) moves the nut member (13) in the direction of arrow C by the contact of the sliding contact surface (S), and the male screw (9) and the movable plate ( 3) Move. Then, in the injection molding step, the movable platen (3) is held at the mold clamping position by the large clamping force.

At the time of releasing the mold, the rotation preventing means keeps the nut member (13) from rotating, and the mold clamping hydraulic chamber (B) is kept.
The hydraulic pressure is drained and the hydraulic pressure is supplied to the releasing hydraulic chamber (A). Then, the mold clamping ram (12) moves in the direction of the arrow D together with the nut member (13), thereby moving the movable platen (3) to the releasing position with a relatively large force by hydraulic pressure.

When the mold is opened, the rotation preventing means is released, and
Rotate the rotary motor (M) in the reverse direction to move the nut member (1
3) Rotate. As a result, the male screw (9) moves in the direction of arrow D, and the movable platen (3) is in the mold opening position. At this time, as in the case of closing the mold, the sliding contact surface (S) does not slip and hinders the free rotation of the nut member (13).

The reference numerals in parentheses are for the purpose of contrasting with the drawings, but do not limit the structure of the present invention.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the mold clamping device 1 of the injection molding machine has a fixed platen 2, a movable platen 3 and a back plate 5, and a plurality of fixed plates 2 and 5 are provided between the fixed platen 2 and the back plate 5. A tie bar 6 extends, and the movable plate 3 is reciprocally guided by the tie bar 6. Then, molds 7a and 7b are mounted on the fixed platen 2 and the movable platen 3, respectively, and these molds cooperate to form a cavity for filling the resin injected from the fixed platen 2 direction. A male screw 9 is fixed to the back surface of the movable platen 3. The male screw 9 extends through the back plate 5 and cooperates with a nut member, a hydraulic chamber, etc. mounted on the back plate 5. Thus, an electric / hydraulic hybrid type mold clamping drive device 10 is configured. Furthermore, back board 5
A linear scale 11 is fixed to the movable plate 3, and the scale 11 can detect the bar member 11a fixed to the movable plate 3 to electrically detect the position of the movable plate 3. Further, on the back board 5, one electric motor M such as an AC motor is installed.

As shown in FIG. 2, the hybrid type mold clamping drive device 10 includes a male screw 9 and a mold clamping ram 12.
The mold clamping ram 12 is fitted in a stepped hole 5a formed in the central portion of the backing plate 5 so as to be movable by a predetermined amount in the axial direction. The mold clamping ram 12 is formed with an annular notch 12a on the inner side thereof, and a ring plate 15 fitted into the notch 12a is fixed to the back board 5. Then, a plurality of O-rings are attached so as to surround the notch 12a to form an oil-tight state, thereby forming a mold release hydraulic chamber A.

On the other hand, the outer side portion of the mold clamping ram 12 is formed in a stepped shape, and this stepped portion constitutes a mold clamping hydraulic chamber B together with the stepped hole portion of the back board 5. ing. The mold clamping hydraulic chamber B is oil-tightly constituted by an O-ring, and has a larger pressure receiving area than the mold releasing hydraulic chamber A. Further, a pin 16 protruding outward is planted in the small-diameter annular portion 12b of the mold clamping ram 12, and the pin 16 is
It is fitted into a hole 17a formed in a bracket 17 extending from the back board 5 to prevent the mold clamping ram 12 from rotating.

A stepped hole 19 is also formed in the center of the mold clamping ram 12. A ball bearing 20 is attached to the large diameter portion 19a of the stepped hole 19,
The nut member 13 is rotatably supported by the bearing 20. The nut member 13 is screwed into the male screw 9 fixed to the movable plate 3 described above, and the male screw 9
The nut member 13 is a feed screw such as a square screw or a trapezoidal screw. Further, a timing pulley 21 is fixed to the nut member 13, and a pulley 23 is also spline-engaged with an output shaft 22 of the electric motor M. A timing belt 25 is wound around these pulleys 21 and 23. Has been. A pulse encoder 26 is connected to the output shaft 22 of the electric motor M, and the position of the movable platen 3 can be detected from the rotation speed of the motor M, that is, the rotation speed of the nut member 13. Further, a hydraulic brake 27 is arranged so as to face the pulley 23, and the brake 27 can stop the rotation of the pulley 23 and the nut member 13 by sandwiching the pulley 23. The brake is not limited to the hydraulic caliper brake, but an electromagnetic brake 27 'integrally incorporated in the motor M.
Of course, other hydraulic brakes may be used.

On the other hand, a cylindrical case 29 is fixed to the small diameter portion 19b of the stepped hole 19 so as to cover the male screw 9, and an oil seal 30 is attached to the open portion of the large diameter portion 19a. The case 29 and the oil seal 30 form an oil reservoir 28. Further, a screw seal 31 is attached to the inner end side of the nut member 13, and an annular oil splash plate 32 (or seal) is fixed to the inner end side surface of the nut member 13. Further, the oil receiver 35 is attached from the mold clamping ram 12 through the bracket 33.
Is provided, and the oil receiver 35 is the oil splash plate 3
It is arranged so as to surround 2 and face the male screw 9. An oil passage 36 extends from the bottom of the oil receiver 35 toward the filter 37 and the pump 39, and further extends from the pump 39 to the oil sump 28. This constitutes a lubricating device in which lubricating oil is always present on the joint surface between the male screw 9 and the nut member 13. In the figure, 29a is an air passage of the oil sump 28.

A quenching washer 40 is fixed to the stepped portion 19c of the stepped hole 19, and the nut member 13 is made of a material having a high lubricating performance such as brass and the outer side surface of the nut member. An annular oil groove a is formed in 13a. Further, when the nut member 13 is in a state in which a normal axial force associated with opening and closing of the mold is applied, the ball bearing 20 includes the quenching washer 40 and the nut member side surface 13a.
And the side surface 13a form a sliding contact surface S with the oil in the oil sump 28 as an oil film interposed therebetween.

Next, the operation of the above embodiment will be described with reference to FIG.

At the mold open position, when a start signal is input due to completion of ejection of the molded product (S1),
First, the electric motor M rotates normally (S2). Then, the nut member 13 rotates counterclockwise as viewed from the right side of FIG. 2 via the pulley 23, the timing belt 25, and the pulley 21 to move the male screw 9 and the movable plate 3 in the arrow C direction. At this time, the nut member 1 is moved based on the movement of the male screw 9 in the direction of arrow C.
Although a reaction force in the direction of arrow D acts on the ball 3, the reaction force is small at the time of the mold closing operation, and the reaction force is the ball bearing 2
And the sliding contact surface S with an oil film interposed between the washer 40 and the nut member side surface 13a. As a result, the nut member 13 is guaranteed to rotate freely, and the thrust force due to the reaction force is applied to the tightening ram 1.
It is carried by the back board 5 based on the fact that the tightening ram 12 is at the moving end in the direction of the arrow D.

When the linear scale 11 or the pulse encoder 26 detects that the movable platen 3 has reached the predetermined mold closing position (S3), the motor M is stopped (S4) and the brake 27 (27 ') is activated. Operate (S
5) Hold the rotation of the nut member 13 in a stopped state. In this state, a switching valve (not shown) is operated to supply pressure oil to the mold clamping hydraulic chamber B (S6). Then, the mold clamping ram 13 moves in the direction of arrow C by a large mold clamping force by hydraulic pressure, and a large reaction force acts on the male screw 9 from the molds 7a and 7b. At this time, the ball bearing 20 allows the nut member 13 to slightly move in the axial direction based on the clearance and the elastic deformation within the static load capacity, whereby a large force from the mold clamping ram 12 causes the bearing 20 to move. It is directly transmitted to the nut member 13 via the washer 40 and the sliding contact surface S of the side surface 13a without passing through. Therefore, the movement of the mold clamping ram 12 in the direction of the arrow C is transmitted to the movable platen 3 via the nut member 13 and the male screw 9 in the stopped and held state,
The movable platen is in the mold clamping position (S7).

In this state, the resin is injected into the cavities of the molds 7a and 7b by an injection device (not shown) for molding (S8), and the mold clamping hydraulic chamber B is kept until the injection molding process is completed. The pressure oil is held (S9), and the movable platen 3 and the mold are held in the mold clamped state. When the injection process is completed, the switching valve is switched, the hydraulic pressure in the mold clamping hydraulic chamber B is drained (S11), and the pressure oil is supplied to the mold releasing hydraulic chamber A (S12). As a result, the mold clamping ram 12 moves in the direction of arrow D, and the ball bearing 2
The nut member 13 also moves in the same direction via 0, and the movable platen 3 moves in the direction of arrow D via the male screw 9 in the stopped state by the brake 27 (27 '). At this time, depending on the shape of the mold, a relatively large force is required at the time of mold release (about 20% of the time of mold clamping), but at the time of mold release operation, the nut member 1
Since the rotation of No. 3 is blocked and hydraulic pressure is used, an axial force corresponding to the above large force can be obtained.

At the time of mold clamping and mold releasing, the nut member 13 moves in the axial direction based on the movement of the mold clamping ram 12, whereby the pulley 21 provided on the nut member 13 is moved.
Also moves, and the alignment state with the motor-side pulley 23 is broken, but the mold clamping (demolding) stroke is short, and at this time the rotation is not transmitted to the nut member 13. Moreover, it is generally absorbed by the timing belt 25. When the mold clamping stroke is large, the spline of the input shaft 22 or the pulley 21 on the nut member side can be absorbed by spline engagement.

Then, when the mold clamping ram 12 moves to the moving end in the direction of the arrow D and reaches the mold release position (see FIG. 2) (S1
3) Then, the releasing hydraulic chamber A enters a holding state in which the hydraulic pressure is held (S14), and the brake 27 (27 ') is released (S15). The mold releasing position is the same as the mold closing position, and is the position where the mold clamping ram 12 moves in the direction of arrow D and comes into contact with the backing board 5. In this state, the electric motor M rotates in the opposite direction, and the nut member 13 is rotated clockwise through the timing belt 25 when viewed from the right in FIG. 2 (S16), and the male screw 9 is moved in the direction of arrow D. To do. At this time, a reaction force in the direction of arrow C is generated in the nut member 13, and the reaction force is transmitted to the mold clamping ram 12 via the bearing 20,
Since the ram is held at the position shown in FIG. 2 by the holding pressure of the mold release hydraulic chamber A, the reaction force of the nut member 13 is further carried by the mold clamping ram 12 by the backing board 5.

When the mold opening position is reached (S17), the holding pressure of the releasing hydraulic chamber A is drained, the electric motor M is stopped (S19), and one stroke is completed (S2).
0). Then, in this state, the molded product is ejected from the mold, and when the mold closing signal is input again, the mold closing operation is started (S1).

Further, when the male screw 9 is moved by the rotation of the nut member 13, the oil in the oil sump 28 is present at the sliding contact surface between the nut member 13 and the male screw 9, and screwed in a sufficiently lubricated state. To do. When the male screw 9 moves in the direction of arrow C, most of the oil attached to the male screw is wiped off by the screw seal 31, but a part of the oil sticks to the male screw 9 and projects from the nut member 13. .. Then, when the male screw 9 moves in the direction of the arrow D, the oil attached to the portion projecting from the nut member is scraped off by the seal when entering the screw seal 31 and rotates integrally with the nut member 13. By the rotation of the plate 32, the adhered oil scraped off is collected in the oil receiver 35, and further returned to the oil sump 28 by the oil passage 36, the filter 37 and the pump 39.

In the above-mentioned embodiment, the feed screw such as the square screw or the trapezoidal screw is used for the male screw 9 and the nut member 13, but this may be a ball screw or the oil sump 28.
Not only the lubrication by the above, but also a static pressure bearing system for forcibly supplying the lubricating oil to the screw sliding surface may be adopted. Further, the electric motor may be another electric motor such as a pulse motor or a servo motor, and is not limited to electric power, and may be another rotary motor such as a hydraulic motor.

Next, a partially modified embodiment will be described.

In the above embodiment, the lead angles of the male screw 9 made of the feed screw and the nut member 13 are set so that the nut member 13 is rotated by the axial force of the male screw 9. In the embodiment, the lead angle is set to a small value, for example, at a predetermined friction coefficient or less than or near the self-locking angle at which the nut member does not rotate depending on the axial force of the male screw 9. Then, the brake 27 (27 ') in the above embodiment is omitted.

In this embodiment, step S6 in FIG.
In S15 and S15, when the movable platen 5 is moved by moving the mold clamping ram 12 by supplying the pressure oil to the mold clamping hydraulic chamber B and the mold releasing hydraulic chamber A, the electric motor M is automatically stopped. To prevent the nut member 13 from rotating,
Moves the male screw 9 integrally with the mold clamping ram 12. On this occasion,
Even if the lead angle of the lead screw is set to be slightly larger than the self-locking angle, the nut member 13 is prevented from rotating on the basis of the stop holding force by stopping the electric motor M.

Therefore, in this embodiment, as the rotation preventing means for preventing the rotation of the nut member 13, the stop holding force of the electric motor M and the frictional force due to the small lead angle of the feed screw, or any one of them. One will be used. Further, the control is further simplified without requiring a special brake operation such as steps S5 and S15 shown in FIG.

[0037]

As described above, according to the present invention,
The clamping ram and the nut member have an integral relationship in the axial direction while allowing relative rotation due to the sliding contact surface, etc., so that the mold clamping ram can be moved only by the mold clamping stroke. It is sufficient that the movement operation and control of the mold clamping ram are simple, and the power transmission from the rotary motor to the nut member is simple.

Further, the sliding contact surface constituted by the side surface of the tightening ram and the flat surface of the nut member does not hinder the rotation of the nut member at the time of mold opening and mold closing, and is operated by hydraulic pressure. At the time of mold clamping in which a large mold clamping force is applied, the large force directly acts on the nut member, so that it is possible to prevent an excessive load from being applied to the rotation supporting member of the nut member such as the ball bearing, and to perform the mold clamping. The life and reliability of the device can be improved.

Further, at the time of mold clamping, pressure oil is supplied to the mold clamping hydraulic chamber to exert a large mold clamping force, and at the time of mold release, pressure oil is supplied to the mold releasing hydraulic chamber to release the mold by hydraulic pressure. Therefore, it is possible to reliably perform the mold clamping operation and the holding thereof with a large mold clamping force, and it is possible to reliably perform the mold releasing operation that requires a relatively large force.

Further, since it is not necessary to drive the rotary motor at the time of releasing the mold, the rotary motor can be a small one that does not require a large force and can be used only when the mold is closed and when the mold is opened. With the direct bearing of the mold clamping force by the sliding contact surface, the capacity of the rotation supporting member of the nut member is reduced, and it is possible to use a small one,
The mold clamping device can be downsized.

As means for preventing rotation of the nut member,
When the brake is used, the nut member can be prevented from rotating in a timely and reliable manner, and the reliability can be improved.

If the rotation motor and / or the feed screw itself with a small lead angle is used as the rotation preventing means, the structure is simplified without a special rotation preventing means such as a brake, and when necessary. Since the rotation of the nut member is automatically prevented, no special control for preventing the rotation is required, and the control of the mold clamping device can be further simplified.

[Brief description of drawings]

FIG. 1 is an overall front view showing a mold clamping device in an injection molding machine according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the main part thereof.

FIG. 3 is a flowchart showing the operation of the mold clamping device.

[Explanation of symbols]

 1 mold clamping device 2 fixed plate 3 movable plate 5 back plate 7a, 7b mold 9 male screw 10 mold clamping drive device 12 mold clamping ram 13 nut member 13a (outside) side surface 20 rotation support member (ball bearing) 40 flat surface part (Quenching washer) A Mold release hydraulic chamber B Mold clamping hydraulic chamber M Rotating (electric) motor S Sliding contact surface

Claims (3)

[Claims] 1. A male screw fixed to a movable plate, and a nut member interlocked with a rotary motor and screwed to the male screw.
A mold clamping device in an injection molding machine, comprising a mold clamping ram rotatably supporting the nut member and movably supported by a back plate in a predetermined axial direction. A mold clamping hydraulic chamber that is supplied to move the mold clamping ram in the mold closing direction; a mold releasing hydraulic chamber that is supplied with hydraulic pressure to move the mold clamping ram in the mold opening direction during mold release; At the time of mold release and at the time of mold release, the nut member is composed of rotation preventing means for preventing rotation between the nut screw and the male screw, and a side surface of the nut member and a flat surface portion of the mold clamping ram. A sliding contact surface that allows the rotation of the nut member based on the rotation motor by sliding when closed, and that transmits the movement of the mold clamping ram to the nut member during mold clamping. A mold clamping device for an injection molding machine. 2. The mold clamping device in an injection molding machine according to claim 1, wherein the rotation preventing means is a brake that acts on a transmission path from the rotation motor to the nut member to stop rotation of the nut member. .. 3. The male screw and the nut member are feed screws such as a square screw or a trapezoidal screw, and the rotation preventing means sets the rotation motor itself and / or the lead angle in a stopped and held state to be small. The mold clamping device in an injection molding machine according to claim 1, which is the feed screw itself.