JP2732774B2 - Device for setting the amount of piston retraction of the mold clamping cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for setting the amount of piston retraction of a mold clamping cylinder.

[0002]

2. Description of the Related Art A conventional injection compression molding apparatus is disclosed in Japanese Patent Application Laid-Open No. 61-283520. The injection compression molding apparatus shown in this figure has a movable plate attached to a piston rod of a mold clamping cylinder.

[0003]

However, the conventional injection compression molding apparatus as described above has a problem that it is troublesome to control the position of the movable platen. That is,
In the injection compression molding, for example, when a foaming resin is used, not only the moving plate is advanced to perform the compression step, but also the operation of actively retracting the movable plate to perform the foaming step is required. The amount of retreat is 1.0
mm, tolerance range of ± 0.1 mm in many cases, a mechanism that detects the stroke position of the movable platen and feeds it back to the mold clamping cylinder is required, and the position control of the movable platen is troublesome. become. An object of the present invention is to solve such a problem.

[0004]

The present invention solves the above-mentioned problems by providing a mechanism for retracting a piston of a mold clamping cylinder to a predetermined retracted position. That is, in the method for setting the piston retreat amount of the mold clamping cylinder according to the present invention, the cylinder chamber is
Divided into a forward oil chamber and a reverse oil chamber by a piston
A piston retraction amount setting device for mold clamping cylinder was
So that it can slide into the housing in which the oil chamber is formed.
The auxiliary pin fitted and pressed by the spring
The piston has a stone, and can apply hydraulic pressure to the auxiliary piston.
With this, the auxiliary piston resists the force of the spring.
And push it to a position where the volume of the oil chamber is
Forcibly send the oil amount corresponding to the volume reduction of
As a result, the piston is forcibly retracted from the forward position by a movement amount corresponding to the supply oil amount. An apparatus for performing the above method includes a cylindrical cylinder body (16), a piston (18) fitted to an inner diameter portion of the cylinder body so as to be movable in an axial direction, and integrally attached to the piston (18). Piston rod (20),
And a cylinder chamber for the mold clamping cylinder (10) divided into a forward oil chamber (10a) and a backward oil chamber (10b) by a piston (18), (22a), a housing (22), an auxiliary piston (24) movably fitted in an oil chamber (22a) of the housing (22), and a spring (28) provided in the housing (22). And the housing (2
2) a hydraulic pressure source (27) connected to the oil chamber (22a);
And an oil chamber (22a) of the housing (22).
Is communicated with the retreat-side oil chamber (10b), and the spring (28) connects the auxiliary piston (24) to the oil chamber (22) when no external force acts on the auxiliary piston (24).
A force is applied so as to press the position of the auxiliary piston (2) from the hydraulic pressure source (27).
By applying hydraulic pressure to 4), the auxiliary piston (2
4) the oil chamber (22a) against the force of the spring (28)
Is pushed to a position where the volume of the oil chamber (22a) is minimized, and the oil amount corresponding to the reduced volume of the oil chamber (22a) is forcibly fed into the retreat-side oil chamber (10b). In addition, the code | symbol in a parenthesis shows the corresponding member of an Example.

[0005]

With the piston of the mold clamping cylinder stopped at the predetermined forward position, the auxiliary piston is moved in the direction in which the volume of the oil chamber is reduced, so that the hydraulic oil in the oil chamber is moved to the retreating oil chamber of the mold clamping cylinder. Forcibly send to. As a result, the piston of the mold clamping cylinder is forcibly retracted from the advanced position by a predetermined amount, and the movable plate is retracted by a predetermined amount of movement. Therefore, the movable plate can be reliably retracted by the predetermined amount without using a mechanism for detecting the stroke position of the movable plate and feeding back the stroke position to the mold clamping cylinder.

[0006]

FIG. 1 shows a mold clamping apparatus for carrying out the present invention. The mold clamping housing 34 is arranged at a position facing the fixed platen 32. The movable platen 30 is disposed between the fixed platen 32 and the mold clamping housing 34. The mold clamping housing 34 and the movable platen 30 are connected by the toggle mechanism 12. That is, the plurality of links connected to each other of the toggle mechanism 12 have one ends connected to the mold clamping housing 34, respectively, and the other ends connected to the movable platen 30, respectively. The fixed platen 32 and the mold clamping housing 34 are connected by four tie bars 36 (however, only two tie bars are visible in the figure). The tie bar 36
Each penetrates the movable board 30. That is, the movable platen 30 is guided by the tie bar 36 for movement in the axial direction. A movable mold 38 is fixed to the movable plate 30, and a fixed mold 40 is fixed to the fixed plate 32. The mold clamping cylinder 10 is attached to the mold clamping housing 34. Piston rod 2 of mold clamping cylinder 10
Reference numeral 0 penetrates the center of the mold clamping housing 34 and is connected to the crosshead 12 a of the toggle mechanism 12.

FIG. 2 is an enlarged view of a part of the mold clamping cylinder 10 embodying the present invention. The mold clamping cylinder 10 includes a cylindrical cylinder body 16, a piston 18 axially movably fitted to an inner diameter of the cylinder body 16, the above-described piston rod 20 integrally attached to the piston 18, and a cylinder body 16. An oiltight housing 22, an auxiliary piston 24 movably fitted in an oil chamber 22 a thereof, and a flow passage 26 a screwed to the housing 22.
Are formed, and a spring 28 provided in the housing 22. The flow path 26 a of the flow path member 26 communicates with the hydraulic pressure source 27. The mounting position of the housing 22 is set so as to limit the stroke of the piston 18 in the mold closing direction (right direction in FIG. 2) by the left side surface in the drawing. Housing 22
The oil chamber 22a is communicated with the mold opening side oil chamber 10b (retreat side oil chamber). When no external force is applied to the auxiliary piston 24, the spring 28 applies a force so as to press the auxiliary piston 24 to a position where the volume of the oil chamber 22a is maximized (a position indicated by a solid line in the drawing). . Hydraulic source 2
7 through the flow path 26a of the flow path member 26 to apply hydraulic pressure to the auxiliary piston 24,
Against the force of the spring 28 to a position where the volume of the oil chamber 22a is minimized (a position indicated by a virtual line in the figure). Thus, the amount of oil corresponding to the reduction in the volume of the oil chamber 22a can be sent to the mold opening side oil chamber 10b to move the piston 18 by a predetermined amount in the mold opening direction. That is, the movable mold 38 can be located at the retracted position in the mold opening direction as shown in FIG.

Next, the operation of this embodiment will be described. The hydraulic pressure is not supplied to the flow path 26a of the flow path member 26 from the hydraulic pressure source 27, and therefore, the auxiliary piston 24
8, and is positioned at the ascending position shown in the drawing.
The capacity of the oil chamber 22a is maximized. In a state where the piston 18 is located at the mold opening position on the left side of the position shown in FIG. 2, the movable mold 38 is integrated with the movable platen 30 via the toggle mechanism 12 through the mold opening position (see FIG. 1). (The position on the left side of the figure from the position shown). The mold is closed by supplying hydraulic pressure to a mold-side oil chamber (advancing-side oil chamber) 10a of the mold-clamping cylinder 10, and foamable molten resin is placed in the mold cavity C from an injection device (not shown). A fixed amount is injected. Subsequently, mold clamping is performed, and the piston 18 is positioned at a position indicated by a solid line in FIG. Next, the pipeline of the mold opening side oil chamber 10 b of the mold clamping cylinder 10 is blocked, and the hydraulic pressure is supplied from the hydraulic pressure source 27 to the flow path 26 a of the flow path member 26. Accordingly, the auxiliary piston 24 is pushed down to a position (a virtual line position) where the volume of the oil chamber 22a is minimized against the force of the spring 28. That is, the hydraulic oil in the oil chamber 22a is forcibly pushed out into the mold opening side oil chamber 10b of the mold clamping cylinder 10. Thereby, the piston 18 is moved to a position indicated by a virtual line in FIG. The amount of movement of the piston 18 can be obtained by calculation from the product of the diameter d of the oil chamber 22a and the stroke s, and the inner diameter and the outer diameter of the mold opening side oil chamber 10b. By changing the thickness dimension of the auxiliary piston 24 or the thickness dimension of the flow path member 26, the stroke s can be changed, that is, the amount of oil pushed out to the mold opening side oil chamber 10b can be changed. In this way, the movable mold 38 is retracted by a predetermined amount to increase the volume of the cavity C, and the foaming process is performed.

In the above description of the embodiment, the present invention is applied to a toggle-type mold clamping device. However, any device using a mold clamping cylinder may be used, and a movable plate is connected to the mold clamping cylinder. The present invention can also be applied to a direct-acting type mold clamping device. In the above embodiment, the piston 18 is retracted by a predetermined amount from a state in which the piston 18 is advanced to a position where it contacts the housing 22.
May be retracted by a predetermined amount from a state where it is stopped at a position away from the housing 22. Further, in the description of the above embodiment, the housing 22 is connected to the cylinder body 1.
6, but may be provided at the outer peripheral portion of the cylinder main body 16 or at a position away from the cylinder main body 16.

[0010]

As described above, according to the present invention,
The movable mold can be reliably retracted from the mold clamping position to a desired retracted position without precisely measuring the position of the movable mold. Therefore, foam molding using the foamable resin can be easily performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mold clamping device to which the present invention is applied.

FIG. 2 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 mold closing cylinder 10a mold closing side oil chamber (advance side oil chamber) 10b mold opening side oil chamber (retreat side oil chamber) 16 cylinder body 18 piston 20 piston rod 22 housing 22a oil chamber 24 auxiliary piston 26 flow path member 26a flow Road 27 Hydraulic source 28 Spring

Claims (2)

(57) [Claims] The cylinder chamber is moved forward by a piston.
A piston retreat amount setting device for a mold clamping cylinder partitioned into a chamber and a retreat-side oil chamber, wherein the piston retreat amount setting device is mounted on the housing in which the oil chamber is formed.
Auxiliary fixie fitted and pressed by spring
Has a down, by the action of hydraulic pressure in the auxiliary piston, the
Auxiliary piston against the oil chamber against the force of the spring
Push to the position where the volume is minimized to reduce the volume of the oil chamber.
A piston retraction amount setting device for a mold clamping cylinder which forcibly feeds a corresponding amount of oil into a retraction oil chamber to forcibly retreat a piston from a forward position by a movement amount corresponding to a supply oil amount. 2. A cylindrical cylinder body (16), a piston (18) fitted to the inner diameter of the cylinder body so as to be movable in the axial direction, and a piston rod (1) integrally attached to the piston (18). 20), and the cylinder chamber is moved forward by the piston (18).
a) and a housing (22) in which an oil chamber (22a) is formed, comprising: a housing (22) having an oil chamber (22a); 22) an auxiliary piston (24) movably fitted in the oil chamber (22a), and a spring (28) provided in the housing (22).
And a hydraulic pressure source (27) connected to the oil chamber (22a) of the housing (22). The oil chamber (22a) of the housing (22) communicates with the retreat-side oil chamber (10b). And the spring (28)
When no external force is applied to the auxiliary piston (24), a force is applied so as to press the auxiliary piston (24) to a position where the volume of the oil chamber (22a) is maximized,
By applying hydraulic pressure from the hydraulic pressure source (27) to the auxiliary piston (24), the auxiliary piston (24) is pressed against the force of the spring (28) to a position where the volume of the oil chamber (22a) is minimized, and A retraction amount setting device for a piston of a mold clamping cylinder for forcibly sending an oil amount corresponding to a volume reduction of the chamber (22a) to the retraction oil chamber (10b).