JP3701229B2 - Injection molding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes at least first and second molds that can be opened and closed relatively, and injection molding for supplying a molten material to cavities formed in the first and second molds to obtain a molded product. Relates to the device.
[0002]
[Prior art]
Generally, in an injection molding apparatus, when the mold material is opened after the molten material supplied from the sprue to the cavity is solidified, the sprue is solidified (hardened) to extract the sprue (hereinafter referred to as the sprue portion). A lock pin (sprue lock pin) is used. This sprue lock pin is provided with an undercut portion that can fix the sprue portion at the tip in order to reliably attract the sprue portion when the mold is opened.
[0003]
As this type of injection molding apparatus, for example, “a sprue cutting method for an injection molded product” disclosed in JP-A-4-140122 is known. In this prior art, as shown in FIG. 6, a cavity 3 is formed between an upper mold 1 and a lower mold 2, and a sprue 4 is formed on the upper mold 1. A core pin 5 and a cylindrical cutter 6 are coaxially inserted into the lower mold 2 corresponding to the sprue 4, and the core pin 5 is fixed to the eject plate 7.
[0004]
The cylindrical cutter 6 includes a slide block 9a that is moved in the horizontal direction by an actuator 8, and a guide protrusion 9b that is set to be inclined with respect to the slide block 9a and a lift block 9d that can be moved up and down by a guide groove 9c. And can be moved up and down.
[0005]
In such a configuration, when a molten material, for example, a molten resin, is filled into the cavity 3 through the sprue 4, the upper mold 1 is raised and the mold is opened after the resin is cured. Next, when the slide block 9a moves to the right in FIG. 6 under the driving action of the actuator 8, the lift block 9d rises under the action of the guide protrusion 9b and the guide groove 9c, and the cylindrical cutter 6 is cut. The sprue portion solidified in the sprue 4 by the blade is separated from the molded product.
[0006]
[Problems to be solved by the invention]
However, in the above-described prior art, the core pin 5 penetrates the lower mold 2 and is fixed to the bottom of the eject plate 7 via the fixing portion 7a. For this reason, the core pin 5 is configured to be considerably long in the axial direction, and when the molten resin is filled from the sprue 4 into the cavity 3, the resin pressure is concentrated on the fixing portion 7a of the core pin 5. The fixing force of the fixing portion 7a is likely to be reduced and play or the like may occur.
[0007]
As a result, the tip of the core pin 5 is liable to be displaced, and the molten resin enters the gap generated by the displacement, causing the malfunction of the core pin 5 and the occurrence of burrs. ing. In that case, the device which raises the intensity | strength of the fixing | fixed part 7a can be considered. However, since the axial length of the core pin 5 is considerably long, the concentration of the resin pressure is easily caused, and a subtle decrease in accuracy is likely to occur. As a result, the fixing force of the fixing portion 7a is significantly reduced.
[0008]
Further, the undercut portion is not provided at the tip portion of the core pin 5. Therefore, when the upper mold 1 is separated from the lower mold 2, there is a problem that sprue portions and the like stick to the upper mold 1 and a molded product is defective.
[0009]
On the other hand, regarding the manufacture of the mold, in order to prevent the resin from entering into the long hole 2a of the lower mold 2 and the generation of burrs, it is necessary to make the sealing property between the long hole 2a and the core pin 5 highly accurate. is there. For this reason, as the elongated hole 2a to be processed becomes longer, it becomes more difficult to ensure accuracy, and a high processing technique is required, and man-hours (time) are required. In addition, a mold with reduced accuracy has a large number of parts and is therefore difficult to repair. As a result, a problem arises in that the mold must be replaced.
[0010]
The present invention solves this type of problem, and with a simple configuration, the sprue lock pin is not displaced, and a high-quality molded product can be efficiently obtained, and the man-hours and parts of the mold are processed. An object of the present invention is to provide an injection molding apparatus capable of reducing the number of points and improving the durability.
[0011]
[Means for Solving the Problems]
In the injection molding apparatus according to the present invention, the second mold that can be opened and closed relative to the first mold includes a telescopic member that extrudes a molded product, and the telescopic member is disposed with respect to the second mold. A drive part for advancing and retreating, and a sprue lock pin having an end fixed to the bottom surface side of the recess in which the telescopic member is disposed and a slidable insertion of the telescopic member.
[0012]
Therefore, when the molten material is supplied from the sprue to the cavity with the first and second molds closed, the first and second molds are relatively separated after the molten material is cured. . At this time, an unnecessary portion such as a sprue portion is fixed to the tip portion of the sprue lock pin, and the unnecessary portion is separated from the first mold integrally with the product portion.
[0013]
In this case, the sprue lock pin is fixed to the bottom surface side of the recess in which the telescopic member is disposed with respect to the second mold, and the axial length of the sprue lock pin can be effectively shortened. . Therefore, the sprue lock pin does not cause a decrease in fixing force due to the concentration of the injection pressure of the molten material, and the molten material enters the gap formed by the displacement of the sprue lock pin, and the sprue lock pin Problems such as malfunction of the lock pin and occurrence of burrs can be reliably prevented. This makes it possible to efficiently obtain a high-quality molded product with a simple and inexpensive configuration.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration explanatory view of an injection molding apparatus 10 according to an embodiment of the present invention.
[0015]
The injection molding apparatus 10 includes at least an upper mold (first mold) 12 that is a fixed mold and a lower mold (second mold) 14 that is a movable mold, and the upper mold 12 and the lower mold 14. A cavity 16 is formed between the two. The upper mold 12 is provided with a sprue 18 for guiding a molten material, for example, a molten resin, to the cavity 16.
[0016]
The lower die 14 corresponds to the sprue 18, and an insert member 20 that pushes out a molded product (described later) cured in the cavity 16, and the insert member 20 with respect to the lower die 14 in the arrow A direction (vertical direction). ) And a sprue lock pin 28 that is slidably inserted into the telescopic member 20 while the end is fixed to the bottom surface 26 side of the recess 24 in which the telescopic member 20 is disposed. With.
[0017]
As shown in FIG. 2, the telescopic member 20 is provided with an extrusion surface 32 that is continuous with the cavity forming surface 30 of the lower mold 14, and a seal hole in which the sprue lock pin 28 is slidably fitted along the vertical direction. 34 is formed. An open hole 36 that expands upward is communicated with the upper side of the seal hole 34, while a guide hole 38 that expands downward is communicated with the lower side of the seal hole 34. . For example, two holes 42 are formed through the bottom surface 26 of the recess 24 provided in the lower mold 14 in the direction of arrow A, and a predetermined depth is formed between the holes 42. The screw hole 44 and the hole 45 are formed coaxially (see FIG. 3).
[0018]
As shown in FIG. 1, the drive unit 22 includes an eject plate 46 that can be advanced and retracted in the direction of arrow A via an actuator such as a cylinder (not shown), and the lower end portions of two rods 48 are supported by the eject plate 46. The The rod 48 is inserted into a hole 42 provided in the lower mold 14, and its tip is fixed to the bottom of the telescopic member 20 (see FIG. 3).
[0019]
As shown in FIG. 2, the screw hole 44 and the hole portion 45 are provided coaxially with the seal hole 34 of the telescopic member 20, and the screw hole 44 is provided at the end of the sprue lock pin 28. The screw portion 50 is screwed together, and the rod portion 51 provided coaxially with the screw portion 50 is fitted into the hole portion 45.
[0020]
The sprue lock pin 28 only needs to correspond to the dimension from the guide hole 38 to the seal hole 34 of the telescopic member 20 in the axial direction (direction of arrow A) (axial length), and is configured to be considerably short. Has been. At the tip (upper end) of the sprue lock pin 28, a locking portion 52 having a reverse taper shape such as a conical shape, a triangular pyramid shape or a quadrangular pyramid shape is formed. In a state where the upper mold 12 and the lower mold 14 are closed, a gate 54 and a slag pool 56 are formed between the sprue 18 and the tip of the sprue lock pin 28.
[0021]
The operation of the injection molding apparatus 10 configured as described above will be described below.
[0022]
First, the lower die 14 is raised via an actuator (not shown), and the lower die 14 and the upper die 12 are closed. At this time, as shown in FIG. 2, the sprue lock pin 28 is disposed at a position facing the sprue 18 of the upper mold 12, and between the sprue lock pin 28 and the sprue 18, a gate 54 and A slag pool 56 is formed integrally.
[0023]
Next, when molten resin is supplied to the sprue 18 of the upper mold 12, the molten resin is supplied and filled into the cavity 16 through the gate 54 and the slag reservoir 56. Then, after the molten resin in the cavity 16 is cured, the lower mold 14 is lowered via an actuator (not shown), and the lower mold 14 is separated from the upper mold 12.
[0024]
Here, in the cavity 16, the resin is cured and the product portion 60 is formed, and in the sprue 18, the gate 54 and the slag reservoir 56, unnecessary portions including the sprue portion 62, the gate portion 64 and the slag reservoir portion 66 are present. An integrated molded product is formed (see FIG. 3).
[0025]
At this time, the slag reservoir portion 66 is formed so as to cover the locking portion 52 provided at the tip end portion of the sprue lock pin 28, and the locking portion 52 has a reverse taper shape, whereby the slag reservoir portion is formed. The locking action is generated by the coupling between the portion 66 and the locking portion 52. Therefore, when the lower mold 14 is separated from the upper mold 12, the product part 60, the sprue part 62, the gate part 64 and the slag reservoir 66 are reliably separated from the upper mold 12 and integrated with the lower mold 14. Can descend.
[0026]
After the lower mold 14 is detached from the upper mold 12, the eject plate 46 that constitutes the drive unit 22 moves vertically upward. Therefore, as shown in FIG. 4, the two rods 48 held by the eject plate 46 are raised in the recess 24 of the lower mold 14, and the telescopic member 20 to which the rod 48 is fixed is It disengages from the recess 24 and is displaced upward.
[0027]
For this reason, the gate part 64 (or product part 60) is pressed vertically upward via the extrusion surface 32 of the insert member 20, and the product part 60 is separated from the cavity forming surface 30 of the lower mold 14.
[0028]
At this time, since the nesting member 20 rises with a pressing force stronger than the coupling force between the locking portion 52 and the slag reservoir portion 66, the slag reservoir portion 66 is partially peeled off by the locking portion 52. In this state, it is separated from the locking portion 52 (see FIG. 4). Next, as shown in FIG. 5, after the insert member 20 is lowered and the molded product is taken out, the sprue part 62, the gate part 64, and the slag reservoir part 66 are separated from the product part 60. A product is obtained.
[0029]
In this case, in this embodiment, as shown in FIG. 2, a recess 24 for arranging the nested member 20 is formed in the lower mold 14, and a screw hole 44 is formed in the bottom surface 26 of the recess 24. The screw portion 50 of the sprue lock pin 28 is screwed into the screw hole 44. Therefore, the axial length of the sprue lock pin 28 only needs to correspond to the dimension from the guide hole 38 to the seal hole 34 of the telescopic member 20 and is considerably shortened.
[0030]
For this reason, the sprue lock pin 28 is not affected by the resin pressure when the molten resin is injected from the sprue 18 into the cavity 16, and even if the injection molding process (shot) is repeated, the sprue lock pin 28 It can prevent reliably that fixing force falls. As a result, a gap is formed between the sprue lock pin 28 and the seal hole 34, and the malfunction of the sprue lock pin 28 and the occurrence of burrs or the like due to the molten resin entering the gap are prevented as much as possible. The effect that it becomes possible is acquired.
[0031]
Further, when the sprue lock pin 28 is fixed to the lower mold 14, for example, it is not necessary to form a through hole in the lower mold 14. In addition, there is no need for a long sprue lock pin fixing long hole processing or an expensive fixing mechanism, and the manufacturing cost of the entire injection molding apparatus 10 can be reduced, which is economical.
[0032]
Furthermore, a reverse-tapered locking portion 52 is provided at the tip of the sprue lock pin 28. For this reason, when the upper mold 12 and the lower mold 14 are opened after the resin is cured in the cavity 16, the sprue portion 62, the gate portion 64, and the slag reservoir portion 66, in addition to the product portion 60, It is possible to reliably prevent sticking to the mold 12 side, and the work of taking out the product portion 60 is performed efficiently and reliably.
[0033]
In this embodiment, the sprue lock pin 28 is disposed at a position facing the sprue 18, but may be set at a position away from the axial position of the sprue 18. The lower mold 14 provided with the sprue lock pin 28 is configured as a movable mold. However, the lower mold 14 may be configured as a fixed mold and the upper mold 12 may be configured as a movable mold. Furthermore, although the molten resin has been described as the molten material, the present invention is not limited to this, and can be applied to various materials employed in normal injection molding.
[0034]
【The invention's effect】
In the injection molding apparatus according to the present invention, the axial length of the sprue lock pin can be effectively shortened, and the sprue lock pin is not affected by the pressure at the time of pouring the molten material. It is possible to reliably prevent the occurrence of malfunctions and burrs. Thereby, the injection molding process can be repeatedly performed with a simple and inexpensive configuration, and a high-quality molded product can be efficiently obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory diagram of an injection molding apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged explanatory view of a telescopic member and a sprue lock pin constituting the injection molding apparatus.
FIG. 3 is an operation explanatory diagram when the lower mold is separated from the upper mold.
FIG. 4 is an operation explanatory diagram when the telescopic member is pushed up from the lower mold.
FIG. 5 is an operation explanatory diagram when a molded product is taken out from the lower mold.
FIG. 6 is a schematic explanatory view of an injection molding apparatus according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Injection molding apparatus 12 ... Upper die 14 ... Lower die 16 ... Cavity 18 ... Sprue 20 ... Nesting member 22 ... Drive part 24 ... Recess 26 ... Bottom 28 ... Sprue lock pin 34 ... Seal hole 44 ... Screw hole 46 ... Eject Plate 48 ... Rod 52 ... Locking portion 54 ... Gate 56 ... Slag reservoir 60 ... Product portion 62 ... Sprue portion 64 ... Gate portion 66 ... Slag reservoir portion

Claims (1)

An injection molding apparatus comprising at least first and second molds that can be opened and closed relatively, and supplying a molten material to cavities formed in the first and second molds to obtain a molded product. ,
The first mold is provided with a sprue for guiding the molten material to the cavity,
The second mold includes a nesting member for extruding the molded product,
A drive unit for moving the telescopic member forward and backward with respect to the second mold;
A sprue lock pin in which an end is fixed to the bottom surface side of the recess in which the nesting member is disposed, and the nesting member is slidably inserted,
An injection molding apparatus comprising:

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