JPH11170260A - Mold clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop an injection molding machine surely in the case of abnormality and to generate mold clamping force correctly when a mold is clamped in multiple stages. SOLUTION: A fixed platen 11, a fixed mold 15 mounted on the platen 11, a toggle support 12, a movable platen 34 which is installed to move freely between the fixed platen 11 and the toggle support 12, a movable mold 16 mounted on the movable platen 34, and a toggle mechanism 21 which is installed between the toggle support 12 and the movable platen 34 and moves the movable plate 34 forward and backward are provided. Then movable platen 34 is equipped with a toggle side member, a mold side member, and a strain member installed between the toggle side member and the mold side member. When the mold is closed, the reaction force applied to the movable platen 34 can be detached correctly on the basis of the strain of the strain member.

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.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is filled at a high pressure into a cavity space of a mold apparatus, and the resin is cooled in the cavity space. Then, the molded article is molded by solidification.

For this purpose, the mold apparatus comprises a fixed mold and a movable mold, and the movable mold is moved forward and backward by a toggle mechanism, and is brought into and out of contact with the fixed mold to close and close the mold. And the mold can be opened. FIG. 2 is a schematic view of a conventional mold clamping device.
In the figure, 11 is a fixed platen, 12 is a toggle support, and 13 is the fixed platen 11 and the toggle support 12.
A tie bar 14 is provided between the fixed platen 11 and the movable platen 14 so as to be able to move forward and backward (moving in the left-right direction in the figure) along the tie bar 13. A fixed mold 15 and a movable mold 16 are attached to the fixed platen 11 and the movable platen 14 so as to face each other.

The toggle support 12 and the movable platen 1
4, a toggle mechanism 21 is arranged between the toggle support 21 and the movable platen 14 by an actuator (not shown) such as a hydraulic cylinder or an electric motor. By moving the movable platen 14 along the tie bar 13 and moving the movable mold 16 toward and away from the fixed mold 15, the mold can be closed, clamped and opened. ing.

To this end, the toggle mechanism 21 includes a toggle lever 23 swingably supported by the crosshead 22, a toggle lever 24 swingably supported by the toggle support 12, Platen 14
, And the link between the toggle levers 23 and 24 and between the toggle lever 24 and the toggle arm 25 are link-coupled to each other.

A ball screw shaft (not shown) is rotatably supported by the toggle support 12, and the ball screw shaft and a ball nut (not shown) provided on the crosshead 22 are screwed together. Let me do. And
In order to rotate the ball screw shaft, a servo motor (not shown) is attached to a side surface of the toggle support 12.

Accordingly, when the servomotor is driven to rotate the ball screw shaft, the rotational movement of the ball screw shaft is converted into the linear movement of the ball nut, and the crosshead 22 is moved forward and backward. That is, when the crosshead 22 is advanced (moved to the right in the drawing), the toggle mechanism 21 is extended, the movable platen 14 and the movable mold 16 are advanced, and the mold is closed and the mold is clamped. At this time, a cavity space (not shown) is formed between the fixed mold 15 and the movable mold 16, and the resin injected by an injection device (not shown) is filled in the cavity space. Then, when the resin in the cavity space is cooled and solidified, a molded product is formed.

Subsequently, when the cross head 22 is retracted (moves to the left in the drawing), the toggle mechanism 21 is bent, and the movable platen 14 and the movable mold 16 are retracted, and the mold is opened. At this time, an ejector pin (not shown) protrudes from the movable mold 16 and the movable mold 16
Push down the molding adhering to the side. By the way, the molded product pushed down by the ejector pin is taken out by a molded product removal machine (not shown) arranged below the mold clamping device. There is a case that the movable mold 16 is caught between the mold 15 and the movable mold 16.

In this case, in order to prevent the mold from being clamped in a state where a foreign matter such as a molded product is sandwiched between the fixed mold 15 and the movable mold 16, a predetermined mold immediately before the mold closing is completed is performed. The thrust generated by the actuator in a section is limited. FIG. 3 is a view showing the operation of a conventional mold clamping device. In the figure, the horizontal axis represents time, and the vertical axis represents the position of the movable platen 14 (FIG. 2) and the thrust generated by an actuator (not shown).

In the drawing, L1 is the movable platen 14
L2 is the thrust generated by the actuator. First, at timing t0, the advance of the movable mold 16 is started, and the mold is closed. Then, a predetermined section τ immediately before the end of the mold closing, that is, the timing t1
From time t2 to timing t2, the thrust L2 is limited, and the value is reduced (F1). At the timing t2, the movable mold 16 reaches the mold touch position. Then, a reaction force generated with respect to the thrust L2 and applied to the movable platen 14 is detected by a strain gauge (not shown) provided on the crosshead 22, and based on a detection result by the strain gauge. If it is determined that a foreign object is sandwiched between the fixed mold 15 and the movable mold 16, the injection molding machine is stopped.

Further, in the case of a mold clamping device that generates a mold clamping force in multiple stages, after the mold closing is completed, in the initial stage of mold clamping, the mold is evacuated to release gas in the cavity space with resin filling. The clamping force is reduced, and thereafter, as the filling of the cavity space with the resin proceeds, the mold clamping force is increased. For this purpose, the position of the crosshead 22 is detected by a position sensor (not shown), and the mold clamping force is changed in multiple stages at a timing corresponding to the position of the crosshead 22.

[0012]

However, in the above-described conventional mold clamping device, the reaction force applied to the movable platen 14 is transmitted to the crosshead 22 via the toggle mechanism 21, so that the detection result by the strain gauge is toggled. The deflection (deflection) generated in the mechanism 21 and the frictional resistance affect the reaction force, and the reaction force cannot be accurately detected.

Therefore, when an abnormality occurs, for example, the fixed mold 1
When it is determined that foreign matter is caught between the mold 5 and the movable mold 16, the injection molding machine cannot be stopped reliably. In addition, since the reaction force applied to the movable platen 14 is transmitted to the crosshead 22 via the toggle mechanism 21, the deflection, frictional resistance, and the like generated in the toggle mechanism 21 affect the detection result of the position sensor. The position of the crosshead 22 cannot be accurately detected.

Therefore, the filling state of the resin in the cavity space and the position of the crosshead 22 cannot be accurately matched, and the mold clamping force cannot be generated accurately. The present invention solves the problems of the conventional mold clamping device, and can reliably stop the injection molding machine when an abnormality occurs, and can accurately generate a mold clamping force when performing multi-stage mold clamping. It is an object of the present invention to provide a mold clamping device that can perform the above.

[0015]

For this purpose, in the mold clamping apparatus according to the present invention, a fixed platen, a fixed die attached to the fixed platen, a toggle support, and a support between the fixed platen and the toggle support are provided. , A movable platen arranged to be able to move forward and backward, a movable mold attached to the movable platen, and a toggle mechanism arranged between the toggle support and the movable platen for moving the movable platen forward and backward.

[0016] The movable platen includes a toggle-side member, a mold-side member, and a strain member disposed between the toggle-side member and the mold-side member. In another mold clamping device of the present invention, a rigid member is further provided adjacent to the distortion member, and the rigid member has an axial dimension smaller than that of the distortion member. Still another mold clamping device of the present invention further includes a strain gauge for detecting a strain amount of the strain member.

Still another mold clamping device of the present invention further includes a pressure sensor for detecting a pressure applied to the distortion member.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of a mold clamping device according to a first embodiment of the present invention, FIG. 4 is a diagram showing a main part of the mold clamping device according to the first embodiment of the present invention, and FIG. FIG. 3 is an explanatory diagram of a mold protection range of the mold clamping device according to the first embodiment.

In the figure, 11 is a fixed platen, 12 is a toggle support, 13 is a tie bar provided between the fixed platen 11 and the toggle support 12, 34 is disposed facing the fixed platen 11, The movable platen is provided so as to be able to advance and retreat (move in the left-right direction in FIG. 1) along the tie bar 13.
The fixed mold 15 and the movable mold 16 are attached to the movable platen 1 and the movable platen 34 so as to face each other.

The toggle support 12 and the movable platen 3
4, a toggle mechanism 21 is provided. The toggle mechanism 21 controls the crosshead 22 by a toggle support 1 by an actuator (not shown) such as a hydraulic cylinder or an electric motor.
By moving the movable platen 34 forward and backward along the tie bar 13 by moving the movable platen 34 back and forth between the second side and the movable platen 34 side, the movable mold 16 is moved toward and away from the fixed mold 15 to close the mold. The mold can be closed and opened.

For this purpose, the toggle mechanism 21 includes a toggle lever 23 swingably supported by the crosshead 22, a toggle lever 24 swingably supported by the toggle support 12, Platen 34
, And the link between the toggle levers 23 and 24 and between the toggle lever 24 and the toggle arm 25 are link-coupled to each other.

A ball screw shaft (not shown) is rotatably supported on the toggle support 12, and the ball screw shaft and a ball nut (not shown) provided on the crosshead 22 are screwed together. Then, in order to rotate the ball screw shaft, the toggle support 1
A servo motor (not shown) is attached to the side surface of the motor 2.

Accordingly, when the servomotor is driven to rotate the ball screw shaft, the rotational motion of the ball screw shaft is converted into the linear motion of the ball nut, and the crosshead 22 is moved forward and backward. That is, when the crosshead 22 is advanced (moved rightward in FIG. 1), the toggle mechanism 21 is extended, the movable platen 34 and the movable mold 16 are advanced, and the mold is closed and the mold is clamped. At this time, a cavity space (not shown) is formed between the fixed mold 15 and the movable mold 16, and the resin injected by an injection device (not shown) is filled in the cavity space. Then, when the resin in the cavity space is cooled and solidified, a molded product is formed.

Subsequently, when the cross head 22 is retracted (moves to the left in FIG. 1), the toggle mechanism 21 is bent, and the movable platen 34 and the movable mold 16 are retracted, and the mold is opened. At this time, an ejector pin (not shown) protrudes from the movable mold 16 and the movable mold 16
Push down the molding adhering to the side. By the way, the molded product pushed down by the ejector pin is taken out by a molded product removal machine (not shown) arranged below the mold clamping device. There is a case that the movable mold 16 is caught between the mold 15 and the movable mold 16.

In this case, in order to prevent the mold from being clamped in a state where a foreign matter such as a molded product is sandwiched between the fixed mold 15 and the movable mold 16, a predetermined mold immediately before the mold closing is completed. The thrust generated by the actuator in a section is limited. Therefore, the movable platen 34
Is a toggle-side member 45 for swingably supporting the toggle arm 25, and a mold-side member 4 for mounting the movable mold 16.
6. A distortion member 51 disposed between the toggle-side member 45 and the mold-side member 46 and configured to generate sufficient distortion with a small mold force; and a distortion member disposed around the distortion member 51. A rigid member 52 having an axial dimension smaller than 51 by a distance δ and not generating distortion even with a large clamping force is provided. In order to detect the amount of distortion of the distortion member 51, a distortion meter (not shown) is provided on the crosshead 22, and a detection result by the distortion meter is sent to a control device (not shown).
Note that a pressure sensor that detects a pressure applied to the strain member 51 can be used instead of the strain gauge.

In this case, at the time of closing the mold, the movable platen 34 is advanced to enter the mold protection range, and the distance L between the fixed mold 15 and the movable mold 16 corresponds to the mold protection range. When the value becomes smaller than the value m, the monitoring of the amount of distortion of the distortion member 51 is started, and the amount of distortion of the distortion member 51 becomes equal to or more than a set value, that is, the distance δ between the toggle member 45 and the rigid member 52 is set. When the value is equal to or less than the value, the control device determines that a foreign object is caught between the fixed mold 15 and the movable mold 16, and stops the injection molding machine.

Then, the amount of distortion of the distortion member 51 does not exceed the set value, that is, the distance δ between the toggle member 45 and the rigid member 52 does not become less than the set value.
When the mold side member 46 reaches the mold touch position, the fixed mold 1
When the movable mold 16 and the movable mold 16 come into contact with each other, the control device ends the monitoring of the distortion amount of the distortion member 51 and starts the mold clamping.

As described above, since the deflection and frictional resistance generated in the toggle mechanism 21 do not affect the detection result of the strain gauge, the reaction force applied to the movable platen 34 when the mold is closed can be accurately detected. Can be.
Therefore, at the time of an abnormality, for example, when it is determined that a foreign substance is sandwiched between the fixed mold 15 and the movable mold 16, the injection molding machine can be reliably stopped.

Next, a second embodiment of the present invention will be described. In this case, the mold clamping device is configured to generate mold clamping force in multiple stages, and after the mold closing is completed, in the initial stage of mold clamping, to release gas in the cavity space with resin filling. Then, as the filling of the cavity space with the resin proceeds, the mold clamping force is increased.

For this purpose, a control device (not shown) monitors the amount of distortion of the distortion member 51 (FIG. 5), and the thrust generated by the actuator (not shown) is changed in multiple stages in accordance with the amount of distortion of the distortion member 51. You. Therefore,
Since the deflection and frictional resistance generated in the toggle mechanism 21 do not affect the detection result by the strain gauge, the amount of distortion of the distortion member 51 can be accurately detected. As a result, the filling state of the resin in the cavity space and the amount of distortion of the distortion member 51 can be accurately corresponded, so that the mold clamping force can be accurately generated in multiple stages.

Further, it is possible to prevent the resin from burning due to poor gas escape, and to prevent the molded product from becoming uneven in thickness and uneven in gravity. Next, a third embodiment of the present invention will be described. FIG. 6 is a diagram showing a main part of a mold clamping device according to a third embodiment of the present invention. FIG. 7 is a side view of a movable platen according to the third embodiment of the present invention.
FIG. 8 is an explanatory diagram of a mold opening force according to the third embodiment of the present invention. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

In this case, a distortion member 61 is disposed between the toggle side member 45 and the mold side member 46.
Can be detected by a strain gauge (not shown) provided on the crosshead 22 (FIG. 1). Further, a pressure sensor for detecting the pressure applied to the strain member 61 can be used instead of the strain gauge. When the cavity space 63 is filled with a resin (not shown) at the time of mold clamping, the pressure of the resin in the cavity space 63 increases, and a mold opening force H is applied to the fixed mold 15 and the movable mold 16.
In this case, the mold opening force H can be accurately detected by detecting the amount of distortion of the distortion member 61.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0034]

As described above in detail, according to the present invention, in a mold clamping device, a fixed platen, a fixed die attached to the fixed platen, a toggle support, and the fixed platen and the toggle. A movable platen provided to be movable back and forth between the support, a movable mold attached to the movable platen, and a toggle mechanism provided between the toggle support and the movable platen to advance and retract the movable platen And

The movable platen includes a toggle-side member, a mold-side member, and a distortion member disposed between the toggle-side member and the mold-side member. In this case, at the time of closing the mold, the reaction force applied to the movable platen can be accurately detected based on the amount of distortion of the distortion member. Therefore, at the time of abnormality, for example, when it is determined that a foreign object is interposed between the fixed mold and the movable mold, the injection molding machine can be reliably stopped.

Further, since the filling state of the resin in the cavity space and the amount of distortion of the distortion member can be made to correspond accurately, the mold clamping force can be accurately generated in multiple stages. In addition, it is possible to prevent the resin from burning due to poor gas escape, and the occurrence of uneven thickness, variation in gravity, and the like in the molded product.

[Brief description of the drawings]

FIG. 1 is a schematic view of a mold clamping device according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a conventional mold clamping device.

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

FIG. 4 is a diagram illustrating a main part of the mold clamping device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a mold protection range of the mold clamping device according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a main part of a mold clamping device according to a third embodiment of the present invention.

FIG. 7 is a side view of a movable platen according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of a mold opening force according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 fixed platen 12 toggle support 15 fixed mold 16 movable mold 21 toggle mechanism 34 movable platen 45 toggle side member 46 mold side member 51, 61 strain member 52 rigid member

Claims (4)

[Claims] 1. A fixed platen, (b) a fixed mold attached to the fixed platen, (c) a toggle support, and (d) a movable back and forth between the fixed platen and the toggle support. With the movable platen arranged,
(E) a movable mold attached to the movable platen;
(F) a toggle mechanism disposed between the toggle support and the movable platen for moving the movable platen forward and backward; and (g) the movable platen includes a toggle-side member, a mold-side member, and the toggle. A mold clamping device comprising a strain member disposed between a side member and a mold side member. 2. The mold clamping device according to claim 1, wherein (a) a rigid member is provided adjacent to the distortion member, and (b) the axial dimension of the rigid member is smaller than that of the distortion member. 3. The mold clamping device according to claim 1, further comprising a strain gauge for detecting a strain amount of the strain member. 4. The mold clamping device according to claim 1, further comprising a pressure sensor for detecting a pressure applied to said strain member.