JP5514585B2 - Piston device with a mechanism for limiting the pressing force of a valve pin for opening and closing a valve gate in an injection molding machine - Google Patents

Description

  The present invention relates to a piston device with a pressing force limiting mechanism for a valve pin for opening and closing a valve gate in an injection molding machine using synthetic resin or the like as a raw material.

  In the case of synthetic resin molding, in an injection molding apparatus, an injection molding machine provided with a pneumatic or hydraulic piston that reciprocates a valve member with respect to a gate communicating with a cavity is widely known.

  Then, in order to ensure that the molding operation based on the series of gate opening and closing of the engagement and disengagement between the pin of the valve member and the gate is performed, adverse effects such as impact due to thermal expansion due to high temperature raw material resin of the gate and valve member pin It is also known to prevent (see, for example, Patent Document 1 or Patent Document 2).

  In addition, in the valve gate that the tip of the valve pin pushes down with a taper, the gate and cavity may be damaged by the piston thrust, and there is a thing that relaxes by putting a spring pressing force on the plate at the head of the valve pin inside the piston. is there.

JP 2002-283212 A Japanese Patent Laid-Open No. 7-251429

  According to Patent Document 1, in order to prevent an excessive force from being applied to the valve pin and its guide support portion, a gap is provided between the valve pin head and the washer and the receiving plate so that an excessive force is applied to the valve pin. It prevents you from joining. Further, in Patent Document 2 described above, a spring chamber is provided at the base end portion of the valve pin and operated while weakening the impact applied to both the front end portion and the gate of the valve member. It is impossible to finely adjust the valve pin and the gate in, and only the impact mitigation for the valve pin during operation is considered.

  In addition, when the disc spring is eased by inserting a disc spring, it is said that the spring constant of the disc spring is too large, making adjustment difficult and often causing damage to the gate.

  The present invention has been made paying attention to the above points, and by adopting a double structure in which a cushioning material such as a coil spring is incorporated in a piston mechanism that operates a valve pin, the mold size is equivalent to the conventional one. When a coil spring is used, the spring constant can be made smaller than the spring constant of a conventional disc spring, making it easy to adjust the amount of cut and force at the tip of the valve pin. It is an object of the present invention to provide a piston device with a mechanism for limiting the force of opening and closing a valve pin for opening and closing a valve gate in a novel injection molding machine that eliminates the need for adjustment.

  The present invention can solve the above-mentioned problems by having the following configuration.

The piston mechanism and a cylinder provided in the (1) mold, a raw material containing synthetic resin by reciprocating the valve pin, in an injection molding machine for molding in the cavity by opening and closing the gate, the piston mechanism, the valve pin a front piston to be continuously provided through a buffer material to internal to said front piston and a double structure of the rear piston movable, absorb the impact of Oshikiri force when the valve pin closes the gate in the buffer material A piston device with a mechanism for limiting the force of opening and closing a valve pin for opening and closing a valve gate in an injection molding machine, characterized in that it can be relaxed.

(2) has a sliding cylinder, said valve pin is proximal head is inserted into the sliding tube, and can be positioned by inserting a spacer, and wherein the said piston mechanism on the outer periphery of the sliding tube the front piston projecting from the annular, the rear piston movably disposed in said front piston and coaxially, the cushioning material is a coil spring, between the rear piston and the front piston above, wherein the comprising providing a more gaps roots if the coil by applying an elastic tension is arranged (1) Oshikiri force-limiting mechanism with a piston device of the valve gate opening and closing valve pin in an injection molding machine according.

(3) piston mechanism having a double structure consisting of the front piston and the rear piston, the characterized by comprising by arranging the cylinder portion which is recessed in the mold (1) according injection molding machine Piston device with a mechanism for limiting the force of opening and closing the valve pin for opening and closing the valve gate.

  According to the present invention, the piston mechanism for reciprocating the valve pin has a double structure of a front piston and a rear piston, and a cushioning material such as a coil spring is interposed between the pistons, so that the pressing force against the gate of the valve pin It is possible to prevent the gate and cavity from being damaged and damaged by the piston thrust, and to provide a cylinder part in the mold itself so that the whole can be incorporated in a compact and compact manner.

  Furthermore, the assembly adjustment of the valve pin with respect to the gate and the arrangement of the piston mechanism in the cylinder portion need only be performed at the time of incorporation, and there is an effect that adjustment after use can be made unnecessary.

Sectional explanatory drawing which shows the state of the gate opening which shows one Example which concerns on this invention Cross-sectional explanatory drawing when the gate is closed in the configuration of FIG. III-III sectional view of FIG.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

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

  1 is a valve pin, and 2 is a sliding cylinder in which the base portion 1a of the valve pin 1 is inserted and fixed. A spacer 3 of which the length can be freely selected is inserted, and the base portion 1a of the valve pin 1 can be pressed and fixed by a stop rod 3a. The spacer 3 is roughly adjusted according to the length dimension of the mold X and the valve pin 1.

  Reference numeral 4 denotes a front piston of the piston mechanism A projecting from the outer periphery of the sliding cylinder 2, and 5 denotes a rear piston movable with a gap G interposed through a coil spring 6.

  The piston is provided with a peripheral wall 4a on the outer periphery of the front piston 4 of the mechanism A, and the rear piston 5 is provided with a body portion 5a surrounding the peripheral wall 4a of the front piston 4. Furthermore, an inner cylinder portion 5b that moves on the outer periphery 2a of the sliding cylinder 2 is provided. Then, a gap g is formed between the end portion P of the inner cylinder portion 5 b and the step portion 2 b provided on the outer periphery 2 a of the sliding cylinder 2.

  Reference numeral 7 denotes a cylinder portion in which the piston mechanism A provided in the mold X can reciprocate, and has openings 8 and 9 for working fluid such as air pressure.

  Reference numeral 10 denotes an insertion hole provided in the mold X that communicates with the cylinder portion 7, which enables the sliding operation of the sliding cylinder 2, and 11 holds the sealing effect of a plurality of movable parts of the mold X. The packing 12 is a retaining ring provided on the outer periphery of the sliding cylinder 2 and has a function of restricting the movement of the rear piston 5.

  Reference numeral 13 denotes a gate that communicates with the cavity, and has a tapered shape α, and the tip shape of the valve pin 1 is also provided with a tapered shape α in order to effectively perform the injection cutting of the injection molten resin.

  Based on the above configuration, the assembly operation of the valve pin 1 will be briefly described first.

  The sliding pin 2 is inserted into the insertion hole 10 provided in the mold X with respect to the gate 13 leading to the cavity disposed in the mold X, and the length of the valve pin 1 is previously stopped by the spacer 3. Adjust by 3a and place it slidably fixed.

  Next, a piston mechanism A in which a front piston 4 provided on the sliding cylinder 2 and a rear piston 5 capable of moving on the sliding cylinder 2 are interposed in a state in which a tension is applied to the coil spring 6 is inserted into the mold X. In the cylinder portion 7, the opening portion is closed although not shown.

  An injection molding operation is performed under the above-described configuration.

  The injected molten material is injected into the cavity through the gate 13, but the valve pin 1 can move back and forth in the cylinder part 7 of the piston mechanism A every time an injection molding operation is performed to open and close the gate 13. .

  When the state shown in FIG. 1, that is, when the gate 13 is opened and the injection raw material is injected into the cavity, the piston mechanism A moves in the cylinder portion 7 and the valve pin 1 closes the gate 13 in the state shown in FIG. However, the thrust acting on the front piston 4 of the piston mechanism A with respect to the valve pin 1 due to expansion or deformation based on the temperature change of the mold X or the valve pin 1 is not a problem. Further, it is possible to buffer the tension of the built-in coil spring 6 and to avoid excessive abutment due to abnormal abutment on the gate 13, and to prevent the gate 13 and the cavity from being damaged.

  As shown in FIG. 2, even if the front end Q of the body portion 5 a of the rear piston 5 of the piston mechanism A is in contact with the inner end of the cylinder portion 7, the front piston 4 is opposed to the tension of the coil spring 6. Unnecessary movement is limited and buffered, so that unnecessary thrust of the piston mechanism A is not received, and the damage to the valve pin 1 and the cavity as well as the gate 13 can be completely prevented.

  In this case, the gap g of the rear piston 5 is formed as the maximum eccentric position, so that the valve pin 1 can be opened and closed safely at the gate 13 under a normal pressing force. is there.

  Although one embodiment of the present invention has been described above, the dimensions of the spacer 3 for adjusting the digging dimension of the cylinder portion and the position of the valve pin operated by the piston mechanism A are the length of the valve pin 1 and the thermal expansion amount of the valve pin. On the other hand, it can be easily calculated with a dimension obtained by adding a cut-off amount of about 0.2 mm, and adjustment after being once incorporated is unnecessary.

  Furthermore, although two sets of coil springs 6 provided in the piston mechanism A are opposed to each other in the drawing, one set or three or more sets may be used, and the rear piston 5 can operate with good balance with respect to the front piston 4. If configured, the number is not specified.

  In this embodiment, the reference numeral 6 is specified as a coil spring. However, the elastic material having a function equivalent to that of the coil spring can be changed to a buffer material or a cushion material.

DESCRIPTION OF SYMBOLS 1 Valve pin 1a Base part 2 Sliding cylinder 2a Outer periphery 2b Step part 3 Spacer 3a Stopper 4 Front piston 4a Circumferential wall 5 Rear piston 5a Body part 5b Inner cylinder part 6 Coil spring 7 Cylinder part 8,9 Entrance / exit hole 10 Insertion hole 11 Packing 12 Retaining Ring 13 Gate X Die A Piston Mechanism G Spacing P End g Gap α Taper Q Tip

Claims (3)

The piston mechanism and a cylinder provided in the mold, a raw material containing synthetic resin by reciprocating the valve pin, thereby opening and closing the gate in an injection molding machine for molding in the cavity, said piston mechanism is provided continuously to the valve pin a front piston that, through a buffer material to internal to said front piston and a double structure of a rear piston that moves, so that the impact of Oshikiri force when closing the valve pin gate can absorb alleviated by the cushioning member A piston device with a pressing force limiting mechanism for a valve pin for opening and closing a valve gate in an injection molding machine. Has a sliding cylinder, said valve pin is proximal head is inserted into the sliding tube, and can be positioned by inserting a spacer, and, said front piston of said piston mechanism on the outer periphery of the sliding tube the projecting from the annular, the rear piston movably disposed in said front piston and coaxially, the cushioning material is a coil spring, an elastic tension between the rear piston and the front piston Oshikiri force-limiting mechanism with a piston device of the valve gate opening and closing valve pin in an injection molding machine according to claim 1, characterized in that it comprises providing a more gaps roots if the coils disposed be imparted. 2. The valve gate opening and closing in the injection molding machine according to claim 1, wherein the double-structure piston mechanism comprising the front piston and the rear piston is disposed in a cylinder portion recessed in a mold. Piston device with a mechanism to limit the force of pressing the valve pin.

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