JP2002067101A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a facility cost by simplifying a mold releasing unit of a mold for injection molding having a sprue inclined with respect to a mold opening direction. SOLUTION: The mold 1 for injection molding comprises a fixed mold 2 having the sprue 5 inclined with respect to the mold opening direction and provided at the mold 2 and a movable mold 3 for forming a runner 6 of an end of an opening of the sprue 5 and having an undercut shape part 16 projected obliquely in a reverse direction to the inclining direction of the sprue 5 so that a molding S is adhered to the mold 3 side at an initial stage of opening the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold having a sprue inclined with respect to the mold opening / closing direction.

[0002]

2. Description of the Related Art Conventionally, in an injection molding die in which a molten resin is injected from a nozzle into a product cavity through a runner such as a sprue or a gate, the position of the nozzle is adjusted for the balance of the die and for various models. For this reason, the gate is often installed at a substantially central portion of the fixed type, but the gate position may be set at a position distant from the central portion due to the shape of the product and the like. In some cases, the sprue portion is disposed obliquely to the mold opening direction.
At this time, when the mold is opened after forming the molded product, if the sprue is inclined, the resistance of the molded product when it comes out from the sprue part increases, it becomes easier to adhere to the fixed mold side, and the molded product is fixed. If it adheres to the mold, it will be difficult to remove it afterwards.Therefore, an undercut is provided on the movable mold side to make it difficult to remove from the movable mold at the mold opening stage, and after the mold opening is completed, an extrusion pin or extrusion plate etc. In general, a technique of extruding with the use of a liquid is used. (For an example in which the sprue is not inclined, for example, Japanese Utility Model Publication No. 56-120220)

[0003]

However, the method of providing an undercut portion on the movable mold side and extruding a molded product by using an extrusion pin or an extrusion plate as described above involves the use of an extrusion plate, an extrusion pin, and a driving device for these. It is necessary to provide inside the mold, and there is a problem that the structure becomes large and the equipment cost increases.

Accordingly, an object of the present invention is to simplify the mold release structure of a molded product in an injection mold in which a sprue is inclined with respect to the mold opening direction and to reduce equipment costs.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a movable mold which is capable of clamping and opening a movable mold with respect to a fixed mold having a sprue portion inclined with respect to the opening and closing direction of the mold. In the injection molding die, the movable mold
An undercut-shaped portion was provided corresponding to the opening position of the sprue portion, and the undercut-shaped portion was formed in a projecting shape inclining in the direction opposite to the direction in which the sprue portion was inclined.

The undercut shape prevents the molded product from coming out of the movable mold at the time of opening the mold, cancels the increase in the pull-out resistance of the inclined sprue, and slightly increases the resistance. Then, the molded product is separated at the boundary between the nozzle and the sprue so as to be separated from the fixed mold. At this time, a force that opposes the pull-out resistance of the inclined sprue portion can be effectively generated by forming the undercut shape to be a projection shape that is inclined and protrudes in a direction opposite to the direction of inclination of the sprue portion.

According to a second aspect of the present invention, the die is provided with an extruding mechanism for releasing the molded product. The extruding mechanism is provided on a fixed die so as to be freely protruded, and is urged by an urging member. A fixed-side extruding member, and a movable-side extruding member that is provided to be movable to the movable die and is urged by an urging member, and a part of the fixed-side extruding member and a part of the movable-side extruding member are mutually connected. It was set so that the abutting and other parts could press the molded product, and the urging force of the urging member on the fixed mold side was stronger than the urging force of the urging member on the movable mold side.

In the mold clamping state, the abutting portions of the fixed-side pushing member and the movable-side pushing member press against each other, and both of them come into the mold against the urging force of the urging member. In the initial stage of mold opening, the fixed-side pushing member having a large urging force presses the movable-side pushing member so that the molded product is pressed against the movable mold side. Then, when the mold is further opened and the contact between the fixed-side extrusion member and the movable-side extrusion member is separated, the molded product is extruded by the movable-side extrusion member and is separated from the movable mold.

Incidentally, such an extruding mechanism has a simple configuration which does not require the use of a large-scale device such as a conventional extruding pin or an extruding plate. No. 340032.

According to a third aspect of the present invention, the fixed mold and the movable mold having a sprue portion inclined with respect to the opening and closing direction of the mold are clamped.
In an injection mold that allows the mold to be opened freely, an extrusion mechanism that presses the molded body against the movable mold at the initial stage of mold opening at the opening position of the sprue part and extrudes the molded body from the movable mold at the final stage of mold opening. The push-out mechanism is provided on the fixed die so as to be protrudable and urged by the urging member, and the pushing mechanism is provided on the movable die so as to be freely protrudable and urged by the urging member. In addition to the movable-side extruding member, a part of the fixed-side extruding member and the movable-side extruding member abut against each other, and the other part can press the molded product. The urging force was set to be stronger than the urging force of the urging member on the movable mold side.

As described above, the extrusion mechanism is provided at the opening position of the sprue portion so that the molded body is pressed against the movable mold at the initial stage of opening the mold. The degree of adhesion to the mold can be increased, and it is possible to effectively cope with an increase in pull-out resistance of the fixed mold sprue portion.

[0012]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is an explanatory view of a mold mating surface of an injection mold according to the present invention, FIG. 2 is a longitudinal sectional view showing a mold extruding mechanism, and FIG. 3 is a longitudinal sectional view showing a sprue part of the mold. 4 is an explanatory view of an extruding mechanism, FIG. 5 is an explanatory view illustrating an extruded state of a molded product accompanying opening of a mold, FIG. 6 is an explanatory view showing an operation of an undercut-shaped portion, and FIG. FIG. 8 is an explanatory diagram of a mold-matching surface of a configuration example, FIG. 8 is an explanatory diagram of a push-out mechanism of a runner portion, and FIG.

In the injection mold 1 according to the present invention, in a mold having an inclined sprue, the extrusion mechanism for taking out a molded product can be simplified to reduce equipment costs and the like. As shown in FIG. 3, a movable mold 3 which can be opened and closed with respect to the fixed mold 2 is provided. As shown in FIG. 3, the fixed mold 2 is provided with a sprue portion 5 communicating with a nozzle 4. Is inclined obliquely to the opening and closing direction of the mold.

The downstream opening of the sprue 5 communicates with the product cavity 8 via the runner 6 and the gate 7.

Further, the fixed die 2 and the movable die 3 are provided with an extruding mechanism 9 for taking out a molded product from the product cavity 8, and the extruding mechanism 9 is provided as shown in FIGS. A plurality of push-out mechanisms 9 are provided along the peripheral edge of the product cavity portion 8, and each of the push-out mechanisms 9 includes a fixed-side push-out pin 11 as a fixed-side push-out member provided in the fixed mold 2, and a movable A movable push-out pin 12 is provided as a side push-out member. The fixed push-out pin 11 and the movable push-out pin 12 are urged forward by springs 13 and 14, respectively. The biasing force of the spring 13 on the fixed-side pushing pin 11 is greater than the biasing force of the spring 14 of the movable-side pushing pin 12.

As shown in FIGS. 5 and 6, the fixed-side push pin 11 and the movable-side push pin 12 have cut surfaces 11c and 12c and stepped portions 11d and 12d, respectively.
The amount of forward projection is regulated by each stopper 15, and a contact surface 11 t with which a part such as a tip portion directly contacts,
12t, and other portions are cavity surfaces 11p and 12p forming the product cavity portion 8.

The operation of the above-described pushing mechanism 9 will be described with reference to FIG. 5. In the initial stage when the mold opening is started, as shown in FIG. Only the fixed-side pushing pin 11 moves forward according to the mold opening stroke, and presses the molded product S against the movable mold 3, of which the step 11 d of the fixed-side pushing pin 11 comes into contact with the stopper 15.

When the mold opening further proceeds, as shown in FIG. 5B, the movable side pushing pin 12 starts to advance, and the molded product S is pushed out from the movable mold 3. That is, the pushing mechanism 9
Requires the molded product S to be pressed against the movable mold 3 in the initial stage of mold opening, and the molded product S to be released from the movable mold 3 in the final stage of mold opening. And not.

As shown in FIG. 3, an undercut-shaped portion 16 is formed on the movable die 3 corresponding to the runner portion 6.
Is formed in a projection shape that is projected in a direction opposite to the direction in which the sprue portion 5 is inclined. This is because when the mold is opened, the inclined sprue portion 5 increases the pull-out resistance, and cancels the tendency that the molded product S easily adheres to the fixed mold 2 side. This is for surely dividing the boundary between the nozzle 4 and the nozzle 4.

The operation and the like of the injection mold 1 described above will be described with reference to FIG. As shown in FIG. 6A, the molten resin injected from the nozzle 4 is filled into the product cavity 8 through the sprue 5, the runner 6, and the gate 7. When the mold opening is started after the molten resin is solidified and the molded product S is formed, at the initial stage of the mold opening, as shown in FIG. The molded product S is pressed against the movable mold 3 by the mechanism 9, and the undercut-shaped portion 16 cancels out the pull-out resistance of the sprue portion 5 in the runner portion 6, so that the molded product S can be reliably moved to the movable mold 3.
Adheres to

When the mold opening further proceeds, FIG.
As shown in (c), the molded product S is extruded from the movable mold 3 by the action of the extruding mechanism 9, and thereafter, as shown in FIG.
The molded product S is extracted from the sprue portion 5 as shown in FIG.

In the above-described injection molding die 1, due to the action of the undercut portion 16 of the nozzle portion 4, the cutting is reliably performed at the boundary between the nozzle 4 and the sprue portion 5 regardless of the pull-out resistance of the inclined sprue. , Molded product S is movable mold 3
The mold can be opened while it is adhered to the mold.

Next, another configuration example in which the pushing mechanism 17 is provided in the runner section 6 will be described with reference to FIGS.
In this configuration example, instead of providing the undercut-shaped portion in the runner portion 6, an extrusion mechanism 17 constituted by a pair of extrusion pins is provided. The basic configuration of the extrusion mechanism 17 is as described above. It is the same as the pushing mechanism 9 of the peripheral part of the product S.

That is, as shown in FIG. 8, the push-out mechanism 17 includes a fixed push-out pin 1 provided on the fixed die 2.
8 and a movable-side push-out pin 19 provided on the movable mold 3. These fixed-side push-out pins 18 and movable-side push-out pins 1
9 is urged forward by respective springs 20 and 21. The biasing force of the spring 20 on the fixed-side pushing pin 18 is larger than the biasing force of the spring 21 on the movable-side pushing pin 19.

Further, the fixed-side push pin 18 and the movable-side push pin 19 are provided with cut surfaces 18c, 19c and a stepped portion 18d,
19d is formed, the amount of protrusion is regulated by the stopper 22 (FIG. 9), and a part of the tip part is formed as the contact surfaces 18t and 19t that directly contact, and the other part is the runner part 6. The arc-shaped portions 18p and 19p are formed.
The extrusion mechanism 9 at the periphery of the molded product S is the same as in the above-described example.

In the injection mold 1 as described above, as shown in FIG. 9 (a), when a molded product S is molded by injecting a molten resin, the mold opening is started. As shown in FIG. 9B, the fixed-side pushing pin 18 with a strong urging force projects and presses the runner portion 6 against the movable mold 3, and the step 18d of the fixed-side pushing pin 18 is
9A, the movable side push-out pin 19 starts to protrude as shown in FIG. 9C, and finally, the molded product S is pushed out from the movable mold 3 as shown in FIG. 9D.

Also in the case of this configuration example, a large-scale push-out mechanism, a driving device and the like are not required as in the prior art, the configuration can be simplified, and the equipment cost can be reduced.

The present invention is not limited to the above embodiment. Those having substantially the same configuration as those described in the claims of the present invention and exhibiting the same operation and effect belong to the technical scope of the present invention. For example, the shape of the molded product, the specific configuration of the extrusion pins 11, 12, 18, and 19 are arbitrary, and the type of the mold 1 may be a vertical type or a horizontal type.

[0029]

As described above, the injection mold according to the present invention has an undercut shape corresponding to the opening position of the sprue portion on the mold mating surface of the movable mold of the injection mold having the inclined sprue portion. The undercut-shaped part is formed as a protruding shape that is inclined and protrudes in the direction opposite to the direction of inclination of the sprue part. Then, it can be attached to the movable mold, and thereafter, the mechanism for extruding the molded product can be configured simply and inexpensively. It is preferable to provide an extrusion mechanism as described in claim 2. Further, the same effect can be obtained by providing an extrusion mechanism in the runner portion.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a mold mating surface of an injection mold according to the present invention.

FIG. 2 is a longitudinal sectional view showing a die pushing mechanism.

FIG. 3 is a longitudinal sectional view showing a sprue portion of a mold.

FIG. 4 is an explanatory view of an extrusion mechanism.

FIG. 5 is an explanatory view for explaining a state in which a molded product is extruded with opening of a mold.

FIG. 6 is an explanatory view showing the operation of an undercut shape portion.

FIG. 7 is an explanatory view of a mold mating surface of a configuration example in which an extrusion mechanism is provided in a runner portion.

FIG. 8 is an explanatory diagram of a push-out mechanism of a runner portion.

FIG. 9 is a diagram showing the operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection molding die, 2 ... Fixed mold, 3 ... Movable mold, 5 ... Sprue part, 6 ... Runner part, 8 ... Product cavity, 9 ... Extrusion mechanism, 11 ... Fixed-side extrusion pin, 12 ... Movable-side extrusion pin , 13 ... Spring, 14 ... Spring, 16 ... Undercut shape part, 17 ... Extruding mechanism, 18 ... Fixed side pushing pin, 19 ... Movable side pushing pin, 20 ... Spring, 21 ... Spring, S ... Molded product.

Claims (3)

[Claims] 1. An injection molding die in which a movable die is clamped and a mold is freely opened with respect to a fixed die having a sprue portion inclined with respect to the opening and closing direction of the die. The surface is provided with an undercut-shaped portion corresponding to the opening position of the sprue portion, and the undercut-shaped portion is formed into a protruding shape that projects in a direction opposite to the direction in which the sprue portion is inclined. An injection mold characterized by the following. 2. An injection mold according to claim 1, wherein said mold is provided with an extruding mechanism for releasing a molded product from said mold, and said extruding mechanism is freely projectable to a fixed mold. A movable side extruding member provided to the movable die so as to be protrudable and biased by the biasing member, wherein the stationary side pushing member and the movable side are provided. A part of the extruding member abuts against each other, and the other part can press the molded product. Further, the urging force of the urging member on the fixed mold side is equal to the urging force of the urging member on the movable mold side. An injection mold characterized by being set stronger. 3. An injection molding die in which a movable die is clamped and a mold is freely opened with respect to a fixed die having a sprue portion inclined with respect to the opening / closing direction of the die, and an opening position of the sprue portion is provided. Has an extrusion mechanism that presses the molded body against the movable mold at the initial stage of mold opening, and extrudes the molded body from the movable mold at the final stage of mold opening, and this extrusion mechanism can freely project to the fixed mold. A fixed-side extruding member provided and urged by an urging member; a movable-side extruding member provided to be movable in a movable mold and urged by an urging member; Part of the members abut each other, and the other part can press the molded product. Further, the biasing force of the biasing member on the fixed mold side is greater than the biasing force of the biasing member on the movable mold side. An injection mold characterized by being strongly set.