JP2002264177A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold capable of producing precise product with reduced irregularity and good setting-up in molding in a multi-cavity mold. SOLUTION: In an injection mold for molding at least two molded products, a runner push-out member, which is supported so as to be freely movable in a contact and separation direction with respect to a runner to push out the runner, is provided and the cross-sectional area of a flow channel is made variable by this member to control the filling speed to respective cavities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold for multi-cavity molding of two or more pieces, and more particularly to an injection mold suitable for injection molding of a molded article requiring high precision. It is.

[0002]

2. Description of the Related Art Conventionally, in order to make the filling completion time of each cavity of a multi-cavity mold uniform, a runner mold designed by experience is manufactured, and the filling time is actually increased several times. For cavities that are slow, there is a method that increases the cross-sectional area of the runner that connects to the cavity and balances the filling. Also, in order to control the amount of resin flowing from a large number of runners into one cavity, as disclosed in Japanese Patent Application Laid-Open No. 9-141704, a product ejection pin (ejector) on a movable side in which a cavity portion of a mold is incorporated. A method has been reported in which the flow path cross-sectional area is changed by adjusting the length of a member protruding from the pin) or the runner.

[0003]

However, in the method described in Japanese Patent Application Laid-Open No. 9-141704, there are cases where it is not possible to arrange an ejector pin or a member protruding in the cross section of the runner in the runner due to the shape of the cavity. I was In that case, since the ejector pins and the protruding pins cannot be attached, the flow path control becomes impossible and this method cannot be adopted. In addition, the present invention relates only to the control of the amount of resin flowing into one cavity. Also, a mold with a structure generally called a sleep rate type that does not push the runner from the movable side, or a shape that expands as the cavity becomes deeper than the parting line can be used. In some cases, ejector pins or members protruding from the cross section of the runner cannot be arranged. In this case as well, the flow path cannot be controlled, so that the above method cannot be adopted.

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection molding die capable of obtaining a highly accurate product with little variation in molding with a multi-cavity die and having a good setup surface. .

[0005]

In order to achieve the above object, a first aspect of the present invention is a runner extruding member for extruding a runner which is supported movably in a direction of approaching / separating from the runner in molding by a multi-cavity mold. By controlling the filling speed of each member into each cavity, the filling completion time becomes almost the same, and it is possible to obtain the effect of preventing the dimensional and physical properties of the molded product from being varied due to each cavity.

According to a second aspect of the present invention, there is provided a runner extruding member which is movably supported in the direction of approaching / separating from the runner and extrudes the runner, in a molding by a mold for taking two or more pieces. The cross-sectional area of the flow path of the runner flowing into the cavity is controlled. As a result, the cavity into which the molten material enters earlier during molding incorporates an extruded member that has been processed so that the cross-sectional area of the flow path of the runner is smaller than the cross-sectional area of the flow path of the runner near the other cavity. Incorporates an extruded member that has been processed so that the cross-sectional area of the runner is larger than the cross-sectional area of the runner near other cavities. Can be prevented from being generated.

[0007] Further, the runner extruding member is formed in such a manner that the flow path constituted by the flow path cross-sectional area varying means has a shape of the runner extruding member so as to have an equal cross section in the direction of the flow path. The number of man-hours required for processing the parts
Since the processing can be performed with a general-purpose machine tool, the manufacturing is facilitated, and the filling speed can be controlled using the members as described above.

According to a fourth aspect of the present invention, a mechanism for detecting the inflow of molding material into the cavity is added. Therefore, in a cavity with a high filling speed, an extruding member provided immediately before the cavity operates earlier, and a flow path is formed. Since the cross-sectional area is reduced, the filling speed control is automatically performed, and the filling completion time is almost the same, so that it is possible to obtain an effect of preventing variations in dimensions and physical properties of the molded product due to each cavity. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In order to make the contents of the present invention easier to understand, the present invention will be described below with reference to examples.

[0010]

FIG. 1 shows an example in which a cylindrical product having a cross section of a circular runner is formed by taking two pieces. The mold is provided with a runner extruding member movably supported in the direction of approaching and separating from the runner, and since it is a circular runner, the end face of the member is machined into a semicircular shape as shown in FIG.
The runner pushing member automatically discharges the runner toward the movable mold by the action of the elastic body when the mold is opened. Further, the runner extruding member is subjected to processing such as forming a square cross section or providing a notch in the brim portion so as not to rotate during movement. After performing the molding and observing the filling status of the two cavities, replace the runner extruding member on the cavity side with a shorter filling time with a member that has been subjected to processing such as that shown in FIG. Delays the filling time. By repeating this, a cavity with a fast filling time will have a slow filling time,
The filling of the two cavities is completed at the same time, so that a molded product of uniform quality can be obtained. Preparing a runner extruding member so that it can be changed to several flow path cross-sectional areas before starting the molding saves time for balancing the cavity. Further, if the mold structure is such that the runner extruding member can be replaced without disassembling the mold on a large scale, such as by simply removing the locate ring or the like, the work becomes easier.

Further, in the case of such a structure in which the runner is machined on the same mold plate as the cavity, a general injection molding machine is used when the runner remains on the same mold plate as the cavity when the mold is opened. In this case, it is advantageous because the protruding mechanism of the product is only on the cavity side. Since the runner pushing member is provided, there is an advantage that the runner can be more reliably pressed against the cavity.

[0012]

According to the present invention, the following effects are exhibited by the above configuration. In the present invention, in molding with a mold that performs multi-cavity molding of two or more pieces, the filling speed can be changed instead of processing the entire template by processing the extruded member. In addition, since the filling is almost simultaneous, it is possible to provide an injection molding die that can prevent variations in dimensions and physical properties of a molded product due to each cavity.

[Brief description of the drawings]

FIG. 1 is a view around a cavity of an injection mold during mold clamping according to an embodiment of the present invention.

FIG. 2 is a view of a runner pushing member showing a mechanism for controlling a runner cross-sectional area according to the present invention.

FIG. 3 is a diagram showing an example of a tip shape of an extruding member for reducing a cross-sectional area of a runner according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection molding die, 2 ... Movable mold (cavity side mold), 3 ... Fixed mold, 4 ... Parting line, 5 ... Molded body, 6 ... Runner, 7 ... Coil spring (elastic member), 8 ...
Extruded member, 9 Locating ring

Claims (4)

[Claims] At least two runners are provided, the runner being a flow path communicating with a cavity for forming a molded product during injection molding, and a runner pushing member supported to be movable in a direction of approaching and separating from the runner and for pushing out the runner. An injection molding die for molding the above molded product, wherein a filling speed control means for controlling a filling speed to each cavity is provided by a member for extruding the runner. 2. The injection molding die according to claim 1, wherein a flow path cross-sectional area changing means for changing a flow path cross-sectional area by a runner pushing member is used as said filling speed control means. 3. The injection according to claim 2, wherein the flow path constituted by the flow path cross-sectional area varying means is the runner extruding member having a shape having an equal cross section in the flow path direction. Molding mold. 4. A molding material inflow detecting mechanism for detecting that molding material has flowed into the cavity in the flow path cross-sectional area varying means, and filling is started in conjunction with the molding material inflow detecting mechanism. 4. A runner extruding member installed in a runner portion leading to a cavity with a short time is operated.
Injection molding die as described.