JP4212840B2 - Injection mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection mold suitable for molding a thin layer body such as a golf ball cover layer. More specifically, the present invention relates to molding a thin layer body with the same mold regardless of the type of resin. The present invention relates to an injection mold.
[0002]
[Prior art]
For example, in an injection mold for molding a cover layer of a golf ball, a large number of gates are provided in the cavity in order to allow molten resin to flow into the cavity while being evenly distributed. These gates play a role of adjusting the inflow amounts of the resins to obtain a cover layer having a uniform thickness. The thickness of the cover layer of the golf ball is about 0.5 to 3.0 mm. However, if the thickness is uneven, the center of gravity shifts from the center of the ball. Variations in the trajectory and flight distance occur.
[0003]
Conventionally, in order to adjust the flow rate of resin from each gate so that the cover layer has a uniform thickness, the flow channel cross-sectional area of the gate is set to a small size in advance, and a part of the flow channel is shaved for each gate. It was done to spread. However, this cutting work requires a great deal of labor and effort, and there is a problem that a new mold must be prepared because it cannot be repaired if it is cut excessively. Further, since different melt resins have different melt viscosity characteristics, even golf balls having the same shape cannot be molded with the same mold, and there is a problem that a new mold must be processed.
[0004]
On the other hand, Japanese Patent Laid-Open No. 2001-212849 by the present inventor proposes to provide a movable member for adjusting the cross-sectional area of the flow path at the entrance of each gate. Thus, when a movable member is provided in the entrance part of each gate, it becomes possible to adapt to shaping | molding of multiple types of resin with the same metal mold | die. However, in recent years, in addition to an increase in the types of resins used for golf ball cover layers, it has been required to further improve the dimensional accuracy of the center of gravity position. The resin flow rate could not always be adjusted sufficiently by simply providing the movable member.
[0005]
[Problems to be solved by the invention]
An object of the present invention is an injection molding that enables a thin layer body to be accurately formed with the same mold regardless of the type of resin when a thin layer body such as a cover layer of a golf ball is formed. The purpose is to provide molds.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an injection mold of the present invention includes a resin supply runner connected to a main runner , a spherical cavity for molding a thin layer, and the resin supply runner. An injection mold having a plurality of gates that connect the cavity and the gates connected to the runner for resin supply at different positions from the main runner ; and the gate on the inner surface of the cavity Open at equal intervals along the equator line of the spherical cavity, and provide a first movable member for adjusting the cross-sectional area of the flow path at the entrance of each gate, and at all gates of the runner for resin supply A second movable member for adjusting the flow path cross-sectional area is provided at a corresponding position and slightly upstream of each gate .
[0007]
More specifically, the injection mold of the present invention includes a resin supply runner connected to a main runner , a spherical cavity for molding a golf ball cover layer, and the resin supply runner. And a plurality of gates that connect the cavity and a support pin that can be protruded and projected from the inner surface of the cavity and supports a spherical core material in the cavity, and the gate is spaced from the main runner. In an injection mold connected to the resin supply runner at different positions, the gate is opened at equal intervals along the equator line of the spherical cavity on the inner surface of the cavity, and a flow path is formed at the entrance of each gate. provided with a first movable member for adjusting the cross-sectional area, slightly upstream of the respective gate a position corresponding to all the gates of the runner for the resin supply Wherein each providing the second movable member for adjusting the flow path cross-sectional area at the position.
[0008]
In the present invention, since the flow passage cross-sectional area of the inlet portion of each gate can be arbitrarily changed based on the adjustment of the first movable member provided at the inlet portion of each gate, it corresponds to a plurality of types of resins having different melt viscosities. Thus, the resin flow rate from each gate to the cavity can be adjusted appropriately. Moreover, since the flow passage cross-sectional area of the runner can be arbitrarily changed based on the adjustment of the second movable member provided on the runner, the flow rate of resin from the runner to each gate can be adjusted to correspond to a plurality of types of resins having different melt viscosities. It can be adjusted appropriately. Therefore, when a thin layered body having a thickness of about 0.5 to 3.0 mm, such as a cover layer of a golf ball, is formed, a flow rate adjusting function by the first movable member and a flow rate adjusting function by the second movable member This synergistic effect makes it possible to accurately form a thin layer with the same mold regardless of the type of resin .
[0009]
In the case of a mold for molding a golf ball cover layer, recent resin materials tend to have a low melt index (MI) (that is, a high melt viscosity), so The road cross-sectional area is preferably as large as possible. When cutting a die as in the prior art, if the gate dimension is increased, there is no allowance for the cutting allowance, so the gate dimension cannot be increased beyond a certain level, and the use of a resin with a small MI has been restricted. On the other hand, in the present invention, by providing the first movable member and the second movable member, it is possible to avoid the inconvenience and to employ a resin having a small MI.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a longitudinal sectional view of a golf ball injection mold according to an embodiment of the present invention, and FIG. 2 is a view taken along the line XX of FIG.
[0011]
The mold 1 is configured such that a half-shaped upper mold 1a and a lower mold 1b are opened and closed by a dividing plane P. A spherical cavity 3 is formed between the upper mold 1a and the lower mold 1b. The upper mold 1 a and the lower mold 1 b are provided with a plurality of support pins 10 that can protrude and retract from the inner surface of the cavity 3, and the spherical core material 9 is supported at the center of the cavity 3 by these support pins 10. Thereby, a space for molding the cover layer of the golf ball is formed between the cavity 3 and the core material 9.
[0012]
A runner 4 is formed on the dividing surface P of the upper mold 1a and the lower mold 1b so as to surround the cavity 3, and the runner 4 is connected to an injection molding machine (not shown) via a main runner 8. The runner 4 has left and right runner portions extending symmetrically in an arc shape, and a main runner 8 is connected to a boundary portion between the left and right runner portions. Between the cavity 3 and the runner 4, there are a plurality of inlet portions 5 branched from the runner 4, and the inner surface of the cavity 3 extending from the inlet portions 5 at equal intervals along the equator line of the spherical cavity 3. A plurality of gates 6 are formed. The plurality of gates 6 are disposed symmetrically on the left and right runner portions. Further, the gate 6 is connected to each of the left and right runner portions at a position where the distance from the main runner 8 is different. Since the inlet portion 5 and the gate 6 are for controlling the distribution function of the molten resin supplied to the runner 4 from the injection molding machine to the cavity 3, the flow passage cross-sectional area is sufficiently smaller than that of the runner 4, It is set to have high flow resistance. In particular, the channel cross-sectional area of the gate 6 is set to be smaller than that of the inlet portion 5.
[0013]
In the lower mold 1b, the inlet 5 of each gate 6 is provided with a first movable member 7 for adjusting the flow path cross-sectional area. In the present embodiment, the movable member 7 is constituted by a screw pin, and the head 7a protrudes into the inlet portion 5 so that the protruding height can be adjusted. Specifically, as shown in FIG. 3, the movable member 7 has an engaging groove 7b such as a plus groove or a minus groove in the head 7a, and rotates by engaging a driver or the like in the engaging groove 7b. By doing so, the protruding height of the head 7a is adjusted. However, the movable member 7 may be provided on at least one of the upper mold 1a and the lower mold 1b.
[0014]
Furthermore, in the lower mold 1b, the runner 4 is provided with a second movable member 17 for adjusting the cross-sectional area of the flow path. These movable members 17 are arranged at positions corresponding to all the gates 6, that is, at positions slightly upstream from the gates 6 in order to accurately adjust the resin flow rate to the gates 6. In the present embodiment, the movable member 17 is composed of a screw pin, and the head 17a protrudes into the runner, and the protruding height is adjustable. Specifically, as shown in FIG. 4, the movable member 17 has an engaging groove 17b such as a plus groove or a minus groove on the head 17a, and is rotated by engaging a driver or the like in the engaging groove 17b. By doing so, the protruding height of the head 17a is adjusted. However, the movable member 17 may be provided on at least one of the upper mold 1a and the lower mold 1b.
[0015]
When the golf ball cover layer is injection-molded between the cavity 3 and the core material 9 while supporting the spherical core material 9 at the center of the cavity 3 using the injection mold 1 described above, each gate The flow passage cross-sectional area determined by the movable member 7 provided at the inlet portion 5 of 6 and the flow passage cross-sectional area determined by the movable member 17 provided at the runner 4 are connected to the discharge port of the main runner 8 (connection to the runner 4). The flow rate of the molten resin from each gate 6 to the cavity 3 is set to be uniform according to the distance from the point).
[0016]
Thereby, the core material 9 supported by the support pins 10 is prevented from being eccentric, and as a result, a golf ball having a cover layer with a uniform thickness and excellent dimensional accuracy at the center of gravity is obtained. I can do it. When changing the type of resin of the cover layer, it is only necessary to change the setting of the diaphragm amount of each of the movable members 7 and 17 according to the melt index of the resin.
[0017]
Further, in the injection molding die, if the flow passage cross-sectional area of the gate 6 is designed to be large, it is possible to easily cope with the molding of the cover layer when using a resin having a low melt index.
[0018]
FIG. 5 shows an injection mold according to another embodiment of the present invention. This injection mold has a plurality of cavities assigned to an upper mold and a lower mold, but only the lower mold will be described here. As shown in FIG. 5, the lower mold 1 b includes a plurality of cavities 3, a plurality of runners 4 surrounding each cavity 3, and a plurality of inlet portions 5 and a plurality of gates 6 connected from each runner 4 to the cavities 3. The main runner 8 for distributing resin to all the runners 4 is formed while being formed.
[0019]
The inlet 5 of each gate 6 is provided with a first movable member 7 for adjusting the cross-sectional area of the flow path, and the runner 4 has a second movable member 17 for adjusting the cross-sectional area of the flow path. Is provided. Further, the main runner 8 is provided with a second movable member 17 like the runner 4. In general, the flow of the resin may be uneven due to the shape and arrangement of the main runner 8, but the movable member 17 is also provided in the main runner 8 to more effectively adjust the flow of the resin. Can do.
[0020]
In the example described above, the first movable member and the second movable member are constituted by screw pins. However, the movable member may be constituted by a plurality of cylindrical pins having different lengths, and these cylindrical pins may be exchangeable. For example, as shown in FIGS. 6 and 7, while preparing a plurality of cylindrical pins 7A, 7B, 7C, and 7D having different lengths L as the first movable member, a cylindrical is provided at the entrance 5 of each gate. You may adjust the flow-path cross-sectional area of the inlet part 5 by providing the opening part which receives pin 7A-7D, and embedding either cylindrical pin 7A-7D in this opening part. Of course, such a configuration can also be applied to the second movable member.
[0021]
【The invention's effect】
As described above, according to the present invention, in an injection mold having a runner for resin supply, a cavity for molding a thin layer body, and a plurality of gates connecting the runner and the cavity, Since the first movable member for adjusting the cross-sectional area of the flow path is provided at the entrance of each gate and the second movable member for adjusting the cross-sectional area of the flow path is provided in the runner, It is possible to appropriately adjust the resin flow rate from the runner to each gate based on the adjustment, and further to appropriately adjust the resin flow rate from each gate to the cavity based on the adjustment of the first movable member. Therefore, when a thin layer body such as a cover layer of a golf ball is molded, it is possible to accurately mold the thin layer body with the same mold regardless of the type of resin.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an injection mold according to an embodiment of the present invention.
FIG. 2 is a view taken along arrow XX in FIG.
3 is a cross-sectional view taken along the line III-III in FIG. 2;
4 is a cross-sectional view taken along arrow IV-IV in FIG. 2;
FIG. 5 is a plan view of a lower mold of an injection mold according to another embodiment of the present invention.
FIG. 6 is a side view showing a modification of the movable member in the present invention.
7 is a cross-sectional view showing a state where the movable member shown in FIG. 6 is installed in a mold. FIG.
[Explanation of symbols]
1 Mold 1a Upper mold 1b Lower mold 3 Cavity 4 Runner 5 Entrance 6 Gate 7 First movable member 9 Core material 10 Support pin 17 Second movable member

Claims (5)

A runner for resin supply connected to the main runner , a spherical cavity for molding a thin layer body, and a plurality of gates connecting the runner for resin supply and the cavity, In the injection mold connected to the resin runner at different positions from the main runner , the gates are opened at equal intervals along the equator line of the spherical cavity on the inner surface of the cavity. A first movable member for adjusting the cross-sectional area of the flow path is provided at the inlet of each of the plurality of gates of the resin supply runners and at positions slightly upstream of the gates. An injection mold provided with a second movable member for adjusting the cross-sectional area of each flow path. A resin supply runner connected to the main runner , a spherical cavity for forming a golf ball cover layer, a plurality of gates connecting the resin supply runner and the cavity, and an inner surface of the cavity An injection molding gold provided with support pins that can be protruded from and retracted into the cavity to support the spherical core material, and the gate is connected to the resin supply runner at a position different from the main runner In the mold, the gate is opened on the inner surface of the cavity at equal intervals along the equator line of the spherical cavity, and a first movable member for adjusting the cross-sectional area of the flow path is provided at the entrance of each gate, for adjusting the slightly each flow path sectional area at a position upstream of the gates a position corresponding to all the gates of the runner for the resin supply Injection mold in which a second movable member.   The injection mold according to claim 1 or 2, wherein each of the first movable member and the second movable member is formed of a screw pin, and the protruding length of the screw pin can be adjusted.   The injection mold according to claim 1 or 2, wherein each of the first movable member and the second movable member includes a plurality of cylindrical pins having different lengths, and the cylindrical pins can be exchanged. The resin supply runner has left and right runner portions extending symmetrically in an arc shape, the main runner is connected to a boundary portion of the left and right runner portions, and the gate is symmetrical to the left and right runner portions. The injection mold according to any one of claims 1 to 4, which is arranged in a mechanical manner.

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