JP2002052572A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by eliminating gate cutting work after molding in a multi-cavity mold for injection molding resin moldings. SOLUTION: The mold is composed of a fixed mold (cavity mold) 20 and a movable mold (core mold) 30, a runner 41 and 42 gate 43 communicating with a sprue 40 bored in the fixed mold 20 is formed in the parting surface between the molds 20 and 30, the runners 41 and 42 are formed from a main runner 41 and a sub-runner 42 branching perpendicularly from the main runner 41, and a round part 44 is formed at the sub-runner side terminal of the gate 43. By setting the sub-runner side terminal of the gate 43 to be a large diameter, stress is concentrated forcibly between a gate solidification part 72 and the resin moldings 60-63. After molding, by attracting a main runner solidification part 41, gate cutting treatment can be attained simply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die capable of taking a large number of moldings, and more particularly to eliminating gate cutting work and reliably preventing molding defects such as sink marks and silver strokes. The present invention relates to a mold for injection molding that can be performed.

[0002]

2. Description of the Related Art To mass-produce synthetic resin molded articles,
In many cases, an injection mold is used. As shown in FIG. 5, the injection mold 1 is a fixed mold (cavity mold).
The mold 2 and the movable mold (core mold) 3 are provided so as to be mold-clamped and mold-openable, and the molten resin supplied from an injection molding machine (not shown) is supplied to a sprue formed in the fixed mold 2. 4a
Through the runners 4b and gates 4c formed on the parting lines of the dies 2 and 3,
After the molten resin is cooled and solidified to form a desired shape, the movable mold 3 is moved to open the mold, and the mold is opened corresponding to the product cavity 5 by the operation of an ejector pin (not shown). The molded resin body to be removed is released.

For example, in order to form a four-piece molded body using the above-mentioned injection mold 1, as shown in a plan view of FIG. 6, runners are formed in four product cavities 5a to 5d. The gate 4c is set at the junction between the four product cavities 5a to 5d and the runner 4b.

FIG. 7 shows a state in which the molded body is taken out of the molding die 1 after the injection molding. In this state, the molded bodies A1 to A4 corresponding to the product cavities 5a to 5d have runners and gate residual portions. B, a gate cutting process indicated by an arrow P in the figure is performed to separate the molded bodies A1 to A4 as shown in FIG.

[0005] As shown in FIG. 8, a submarine gate 4 is formed as a resin passage between the runner 4 b and the product cavity 5.
The injection mold 1 for setting d to the movable mold 3 is also employed. In this case, the gate residual portion corresponding to the submarine gate 4d is automatically cut by the projecting operation of the projecting pin 6. You.

[0006]

As described above, in the conventional injection molding die 1, it is necessary to perform a gate cutting operation with a nipper or the like in the mold shown in FIGS. Has been pointed out.

In addition, in the injection molding die 1 shown in FIG. 8 which can make the gate cutting work unnecessary, sink and silver strokes are liable to occur on the gate surface and the flow resistance of the molten resin is large because of the large flow resistance. Since molding defects such as sink marks due to defects (short shots) are likely to occur, it is difficult to maintain good moldability,
It has also been pointed out that the work of processing the submarine gate 4d on the movable mold 3 is troublesome.

The present invention has been made in view of such circumstances, and is an injection molding die capable of taking a large number of resin molded articles. The present invention can eliminate gate cut processing, as well as sink marks and silver strokes. It is an object of the present invention to provide an injection mold capable of ensuring good moldability without causing molding failure of the mold.

[0009]

In order to achieve the above-mentioned object, the present invention is directed to a fixed-side mold and a movable-side mold, and includes a plurality of product cavities defined between the molds. An injection mold that can be used to take a large number of moldings by injection filling with molten resin.Runners and gates that communicate with sprues drilled in the fixed mold are formed on the parting surfaces of both molds. The runner is composed of a main runner and a sub-runner branched from the main runner. By setting the sub-runner side terminal of the gate to a larger diameter than the cavity side terminal,
The strength of the sub-runner terminal is enhanced.

As is apparent from the above configuration, in the injection molding die according to the present invention, as the configuration of the runner, a sub-runner is branched from the main runner, and the tip of the sub-runner communicates with the product cavity through the gate. Yes,
And since the junction on the sub runner side of the gate has a large diameter and the joining strength is strengthened, if the main runner is pulled in,
External force is applied to both ends of the gate, but since the sub-runner side terminal of the gate is set to a large diameter, the external force concentrates on the tip of the gate (cavity side terminal) and gate cut processing can be easily performed by simply pulling in the main runner And the gate cutting work by a nipper or the like can be eliminated.

Further, since a normal side gate can be used as the gate instead of the submarine gate, molding defects such as sink marks and silver strokes do not occur.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of an injection mold according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing the overall structure of an injection mold according to the present invention, and FIG. 2 is a plan view showing a mold surface of a movable mold showing the structure of a product cavity and a runner in the same mold. FIG. 3 is an explanatory view showing the relationship between a runner, a gate, and a product cavity, and FIG. 4 is an explanatory view showing a step of separating a molded body after injection molding.

1 and 2, the entire construction of the injection mold 10 according to the present invention will be described. The injection mold 10 includes a fixed mold (cavity mold) 20 and a movable mold. (Core mold) 30, and the fixed mold 20 is connected to an injection molding machine 21, and molten resin is supplied from the injection molding machine.

The movable side mold 30 has a press ram 3
1 and a reciprocating operation is performed by a press machine (not shown) in the direction of an arrow in FIG.

Further, as shown in FIGS. 1 to 3, the injection molding die 10 is supplied with a molten resin from an injection molding machine 21 to a sprue 40 formed in the stationary die 20 by punching. 2 from the sprue 40 through a main runner 41, a sub-runner 42, and a gate 43 formed on the parting line surfaces of the fixed mold 20 and the movable mold 30.
Product cavities 5 set at four locations as shown in
The molten resin is supplied to 0 to 53.

Then, the injection molding die 10 according to the present invention.
In FIG. 2, as shown in FIGS. 2 and 3, runners 41 and 42 that supply molten resin to product cavities 50 to 53 are
The main runner 41 communicates with the sprue 40 and supplies the molten resin in two directions (the direction a and the direction b), and a sub-runner 42 that branches in a direction orthogonal to the main runner 41 in both directions. 43 are set.

Therefore, the molten resin supplied from an injection molding machine (not shown) is introduced from the sprue 40 to the main runner 41, and the main runners 41 in the a and b directions are branched by the sub runners 42, respectively, and correspond to the corresponding gates. 43
The molten resin is injected and filled into the four product cavities 50 to 53 through the above.

In the present invention, as described above, the sub-runner 42 is formed so as to be branched in a direction substantially perpendicular to the main runner 41 in order to eliminate the man-hour for gate cutting of the product after injection molding. As shown in FIG. 3, an R portion 44 is formed at the terminal of the gate 43 on the side of the sub-runner 42.

That is, if the R section 44 is set, the R section 4
4, the diameter of the gate 43 is restricted to a large diameter only in the area indicated by oblique lines in FIG.

By setting the R portion 44, the strength of the boundary portion between the sub-runner 42 and the gate 43 is strengthened. 50
The mechanical strength is higher than the side terminal.

Therefore, using the injection mold 10,
In a state where molten resin is injected and filled into the product cavities 50 to 53 and the corresponding resin molded bodies 60 to 63 are removed from the mold as shown in FIG. 4, the resin molded bodies 60 to 63 are separated from the main runner 41 and the sub-runner. The runner solidified portions 70 and 71 corresponding to the gate 42 and the gate 43 and the gate solidified portion 72 are integrated.

As described above, in the injection molding die according to the present invention, by setting this joint portion to a large diameter, for example, by providing the R portion 44 between the sub-runner 42 and the gate 43, the sub-runner solidification portion is formed. Since the joining portion between the solidified portion 71 and the gate solidified portion 72 is strengthened, for example, if the main runner solidified portion 70 is pulled in the directions of arrows A and B in FIG. External force will be concentrated on the boundary with the body 60-63,
Since the portion is easily broken at this portion, the gate cutting operation can be easily completed simply by pulling the main runner solidified portion 70 to the left and right without the need for the conventional gate cutting operation using a nipper or the like.

As described above, by using the injection molding die 10 according to the present invention, a multi-piece resin molded body 60 to 63 can be obtained.
In addition to eliminating the need for special gates such as submarine gates, the die cutting process can be simplified, and sink and silver can be eliminated. Molding defects such as strokes can be prevented beforehand, and good moldability can be maintained.

[0025]

As described above, in the injection molding die according to the present invention, the sub-runner is branched and formed from the main runner communicating with the sprue, and the sub-runner side terminal of the gate is set to have a large diameter. By increasing the strength of the boundary with the gate, the stress is forcibly concentrated on the cavity side end of the gate, so after unmolding the one in which many resin moldings are integrated with the runner solidified part ,
By pulling the main runner, the gate terminal can be broken, eliminating the need for gate cutting work.
This has the effect of increasing work efficiency.

Further, in the present invention, since the product cavity is filled with the molten resin through the gates formed on the parting surfaces of both molds, molding defects such as sink marks, silver strokes, short shots and the like when using a submarine gate are used. And the effect of ensuring good moldability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an injection mold according to the present invention.

FIG. 2 is a plan view showing a mold surface of a movable mold in the injection mold shown in FIG.

FIG. 3 is an explanatory view showing a relationship between a runner and a gate in the injection mold according to the present invention.

FIG. 4 is an explanatory view showing a separation step of a molded article molded using the injection mold according to the present invention.

FIG. 5 is a schematic view showing a conventional multi-cavity injection mold.

FIG. 6 is an explanatory diagram showing a mold surface of a movable mold of a conventional injection mold.

FIG. 7 is an explanatory view showing a gate cutting operation of a multi-cavity molded body molded using a conventional injection molding die.

FIG. 8 is an explanatory view showing a type using a submarine gate in a conventional injection mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Injection molding metal mold 20 Fixed mold (cavity mold) 21 Injection molding machine 30 Movable mold (core mold) 31 Press ram 40 Sprue 41 Main runner 42 Subrunner 43 Gate 44 R part 50-53 Product cavity 60-63 Resin molding 70 Main runner solidified part 71 Subrunner solidified part 72 Gate solidified part

Claims (1)

[Claims] 1. A fixed mold (20) and a movable mold (3).
0) and a plurality of product cavities (50, 51, 52, 53) defined between both molds (20, 30).
The molten resin is injected and filled into the inside of the molded product (60, 61, 6).
Injection mold (10) that can take a large number of 2, 63)
A sprue (4) drilled in the fixed mold (20).
Runners (41, 42) and gate (43) communicating with 0)
Are formed on the parting surfaces of both molds (20, 30),
The runner (41, 42) is a main runner (41).
And a sub-runner (42) branching therefrom,
An injection molding die, wherein the strength of the sub-runner (42) side terminal is enhanced by setting the sub-runner (42) side terminal of the gate (43) larger than the cavity side terminal.