JPH0910361A - Golf ball injection molding method, and mold for injection molding of golf ball - Google Patents

Abstract

PURPOSE: To dispense with a complicated after-process and to eliminate the wastefulness of material, by connecting a runner with a built-in heater to a cavity through a gate part, and injecting and leading molding material to the cavity directly through the gate part. CONSTITUTION: In case of injection-molding a golf ball, upper and lower molds 1 and 2 are joined with each other, and injection molding material for a golf ball is supplied in fused condition from an injection molding machine to the inlet 8a of a hot runner with a built-in heater. At this time, a valve pin 9 is retreated from the end of an outlet 8b to open the end of the outlet 8b. Hereby, the fused molding material flows within the hot runner 8, and is introduced into the cavity 3 directly form the end of the outlet 8b. When a specified quantity of molding material is introduced, the valve pin 9 is advanced to block the end of the outlet 8b. Accordingly, at the time of finish of a molding cycle, the head of the valve pin 9 abuts on the surface of a molded golf ball, so the golf ball is molded in such a condition that the gate pressure is inconspicuous without burrs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball injection molding method and an injection molding die used therefor, and is particularly suitable for injection molding a golf ball cover.

[0002]

2. Description of the Related Art
When injection molding the cover of a golf ball, as shown in FIGS.
As shown in Fig. 2, the molten cover molding material from the injection molding machine is passed through the main runner a and the ring-shaped cold runner b.
In this case, a method has been adopted in which a plurality of nozzles c equally distributed along the inner peripheral portion of the ring-shaped runner b are supplied to the cavity f of the mold e through the gate portion d. In the figure, g indicates a golf ball core.

However, in this method, when the golf ball is taken out after injection molding, the molding material remaining on the ring-shaped runner b and its nozzle portion c is solidified together with the cover, and as shown in FIG. The ring-shaped runner b and the ring-shaped solidified substance i and the radial solidified substance j respectively corresponding to the ring-shaped runner b and the nozzle portion c are integrally connected to the ball h and then demolded.

Therefore, as shown in FIG. 12, the golf ball h thus demolded is gate-cut to separate the ring-shaped and radial solidified materials i and j from each other, and then the solidified portion corresponding to the gate is solidified. The thing (burr) k was removed by trimming.

However, the above-mentioned gate cutting and trimming are time-consuming post-processes, and if the gate cutting and trimming are not performed well, the molded product often fails. Furthermore, the ring shape,
The formation of the radial solidified materials i, j causes waste of the molding material, and therefore, the solidified materials i, j are crushed, mixed with the molding material, and used again for injection molding. However, if such a pulverized product is mixed with the molding material, the quality of the golf ball may be deteriorated and the injection molding condition may be changed.

Further, since the injection molding is carried out via the ring-shaped runner, the molten molding material is prevented from solidifying in the ring-shaped runner during the injection molding cycle, and moreover, it is evenly distributed from the nozzle parts to the cavities via the gate parts. In addition, injection molding is performed at high pressure and low speed because it is necessary to introduce them almost at the same time, and it is generally difficult to adopt high-speed and low-pressure injection molding conditions. Furthermore, the gate diameter is limited to about 1 mm, and if the diameter is smaller than this, the fluidity of the molten material into the cavity will deteriorate, and not only will the filling be insufficient, but also the sink marks, weld lines, burrs, and other There is a problem that appearance defects are likely to occur.

[0007] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a golf ball injection molding method and an injection molding die, which can omit complicated post-processes such as gate cutting and trimming and can obtain a high quality golf ball without wasting materials. .

[0008]

In order to achieve the above object, the present invention provides a method for injection molding a golf ball by introducing a molten injection molding material for a golf ball into a mold cavity. And at least three runners provided in proximity to the heating means for maintaining the molten state of the molding material are communicated with the cavities through the gate portions, respectively, and the molding material is discharged from the outlet end of the runner. Provided is a golf ball injection molding method characterized by directly injecting and introducing into the cavity through a gate portion.

Further, according to the present invention, a mold for injection molding a golf ball, which has an upper die and a lower die, and in which the upper and lower dies are separably joined to each other to form a hollow spherical cavity, is melted. At least three hot runners, through which the injection molding material for golf balls circulates, are formed inside, and the tip of the hot runner member having a built-in heating means for holding the molten state of the molten molding material in this hot runner. Also provided is a mold for golf ball injection molding, characterized in that the nozzle part is connected to the gate part of the cavity.

[0010]

The method of injection molding a golf ball of the present invention and the mold used for the same have at least three hot runners in which a molten injection molding material for golf balls circulates. The tip nozzle part of the hot runner member containing the heating means for holding the molten state of the molten molding material is connected to the gate part of the cavity, and the molding material is directly passed through the gate part from the outlet end of the hot runner. Injection into the cavity,
Since the molding material is directly injected into the cavity from three or more gates without a ring-shaped runner, complicated post-processing such as gate cutting and trimming can be eliminated. It is possible to eliminate the occurrence of defective products. Furthermore, since it is not necessary to take out the runner part for each molding cycle, the loss (waste) of the molding material used can be reduced, the time for filling the runner part with material can be shortened, and the time for taking out the runner can be reduced. Therefore, the molding cycle time can be considerably shortened by adding them together. In this case, after the molding cycle is completed, the molten molding material in the hot runner is heated by the heating means and thus does not solidify and maintains the molten state, so that it is injected into the cavity without waste during the next molding cycle. It will be introduced. In addition, since the runner does not need to be taken out, the gate can be separated automatically, enabling fully automatic molding (unmanned operation). Further, high-speed low-pressure molding is possible without post-processing such as gate cutting and trimming, and molding defects such as burrs and welds are less likely to occur.

When the resin is injected from the two gate portions, for example, the core material is eccentric in the manufacturing process in which the core material is previously placed in the cavity and the cover material is formed thereon. May occur, which is not preferable. Therefore, in the method and apparatus of the present invention, the resin is injected from at least three directions. In this case, the gate portions are arranged so as to be spaced apart from each other at substantially equal distances (at positions farthest from each other). For example, when the number of gate portions is three, it is preferable that an equilateral triangle is drawn by connecting these gate portions. Further, when the number is four, it is preferable that the line connecting these draws a regular tetrahedron inscribed in the spherical cavity.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2 show a golf ball injection molding die according to an embodiment of the present invention, in which 1 is an upper die having a hemispherical concave portion on the lower surface and 2 is a lower die having a hemispherical concave portion on the upper surface. The upper mold 1 and the lower mold 2 can be separably joined to each other, and in the joined state,
A hollow spherical cavity 3 is formed.
In addition, in the figure, A in the drawing is a split surface.

Further, 4 is a first hot runner member (sprue bush), 5 is a second hot runner member, 6 is a third hot runner member, and the tip of the third hot runner member 6 is inside the upper mold 1. Placed in the state where
The tip nozzle portion 6a of the member 6 is connected to the gate portion 7 of the cavity 3. A hot runner 8 serving as a passage for the molten molding material is continuously formed in each of the members 4, 5, and 6, and the molten molding material from the injection molding machine (not shown) is supplied to the first hot runner member 4 by the injection molding machine. The hot runner inlet end 8a flows into the hot runner 8, and is injected and introduced into the cavity 3 from the hot runner outlet end 8b of the tip nozzle portion 6a of the third hot runner member 6. Reference numeral 9 is a valve pin that can move into the hot runner 8c of the third hot runner member 6 (see FIG. 1).
It is arranged so that it can be moved up and down. The base end portion (upper end portion) of the valve pin 9 penetrates the second hot runner member 5 and projects upward, and is connected to a movable device 10 that moves the valve pin 9 up and down. When it advances in the direction of the cavity 3, the tip of the valve pin 9 closes the hot runner outlet end 8b to block the inflow of the molten molding material in the hot runner 8 into the cavity 3, and the valve pin 9 from the cavity 3 side. When exiting, the hot runner outlet end 8b is opened so that the molten molding material in the hot runner 8 can flow into the cavity 3. In this case, in this embodiment, the tip end surface of the valve pin 9 is advanced to a position where it can come into contact with the surface of the molded golf ball through the inside of the gate portion 7 when the valve pin 9 is in the maximum extension state.

Furthermore, each of the above hot runner members 4, 5,
Each 6 has a heating means (heater) 11 built therein, and this heating means 11 heats the molten molding material flowing through the hot runner 8. As a result, even after the hot runner outlet end 8b is blocked by the advance of the valve pin 9, the molding material remaining on the hot runner 8, particularly the hot runner 8c of the third hot runner member 6, does not solidify, and the molten state is maintained. The molten molding material is injected and introduced into the cavity 3 in the next molding cycle.

Here, the mold shown in FIG. 1 is provided with three hot runner devices H having the above-mentioned structure, and these hot runner devices H are joined to the upper die 1 and the lower die 2 by joining them. In this state, the three hot runners 8,
8, 8 communicate with the cavity 3 via the gate portions 7, 7, 7. At this time, the gate portions 7, 7, 7 are spaced from each other at equal intervals, and are provided so as to be substantially 120 ° apart (each farthest).

When a golf ball is injection-molded using the above mold, the injection molding machine (not shown) melts the golf ball injection molding material in a state where the upper mold 1 and the lower mold 2 are joined. Is supplied to the hot runner inlet end 8a. At this time, the valve pin 9 is the hot runner outlet end 8b.
The outlet end 8b is opened by further retreating. This allows
The molten molding material flows in the hot runner 8 and is directly introduced into the cavity 3 from the hot runner outlet end 8b.
When a predetermined amount of molding material is introduced into the cavity 3, the movable device is operated to advance the valve pin 9 toward the cavity 3 and close the hot runner outlet end 8b.
Next, after the molding material in the cavity 3 is solidified, the upper mold 1 and the lower mold 2 are separated at the split surface A, and the molded golf ball is taken out. When the golf ball is further molded subsequently, the above operation is repeated. However, as described above, the molding material remaining in the hot runner 8 in the previous molding cycle does not solidify due to the heat of the heating means 11 and is in a molten state. Since it is held, this molten molding material is injected and introduced into the cavity 3 as an injection molding material without waste in a new molding cycle. The timing of advancing and retracting the valve pin can be set by interlocking with the injection molding machine.

Therefore, according to this method, the molded golf ball is not molded in the state in which the ring-shaped solidified product is integrally bonded as shown in FIG. At this time, since the tip end surface of the valve pin 9 contacts the surface of the molded golf ball, the valve pin 9 is molded with substantially no burr and the gate pressure is inconspicuous. It is a thin and short ring-shaped burr that occurs when the molding material penetrates into the slight gap between the mold and the mold and can be easily removed. The post-process can be reduced, the post-process can be omitted in some cases, and the occurrence of defective products during post-processing is also reduced.

FIG. 3 is a modified example of the above-mentioned embodiment, and this example is a top type in which the tip nozzle portion 6a of the third hot runner member 6 simultaneously serves as the gate portion 7. , 2 has the same configuration and operation effect as the above-mentioned embodiment except that it is different from the topless type.

The shape of the tip end surface of the valve pin 9 can be changed in various ways. As shown in FIGS. 2 and 3, the valve pin 9 is formed into a hemispherical shape (shape corresponding to the dimple shape), and the tip end surface is formed on the molding material at the end of the molding cycle. The dimples may be formed by pressing so as to bite.If the dimples are not formed as described above and are brought into contact with the land, a circular shape, a triangular shape, a square shape, a rectangular shape, a hexagonal shape, an octagonal shape, and an octagonal shape may be used. It may be formed in various shapes such as polygonal shape such as prismatic shape, humanoid shape, elliptical shape, gourd shape and cross shape.

Further, FIG. 4 shows a valve gate system. In this method, the gate is opened and closed by a member in which a piston 64 and a spring 66 are arranged in a capsule body 62 which is divided into two parts, front and rear. That is, when the resin pressure is not applied, the gate 7 is closed because the piston 64 is pressed toward the gate by the force of the spring 66. When the resin pressure is applied, the portion 62b of the capsule body 62 near the gate is pushed by the resin pressure, whereby the piston 64 retracts and the gate 7 opens. When the filling of the cavity is completed and the resin pressure is reduced, the piston 64 is automatically pushed by the force of the spring 66 to completely seal the gate 7.

Further, FIGS. 5 and 6 are of an open nozzle type which does not use the valve pin as described above, FIG. 5 is of an external heating type having a heating means 11 outside the hot runner 8c, and FIG. 6 is of a hot type. The internal heating system has a heating means 11 in the runner 8c. In these open systems, burrs corresponding to the gate portion 7 occur, but the object of the present invention can be sufficiently achieved.

In the embodiments of FIGS. 2 to 6, only one hot runner communicating with the cavity is shown and the other ones are omitted, and these three hot runners also communicate with the cavity as in FIG. Is what you are doing.

FIG. 7 shows another embodiment of the present invention. In this example, the tip end nozzle portions 6a of the hot runner members 6, 6, 6, 6 are provided at a plurality of locations (4 locations in the figure) of the cavity 3. , 6a, 6a, 6a are connected.

At this time, as shown schematically in FIG. 8, the four tip nozzles are arranged so that the gates come to the respective vertices of the regular tetrahedron ABCD inscribed in the spherical cavity. With such a structure, an eccentric multilayer ball can be injection-molded.

Further, as shown by reference numeral 12 in FIGS. 2 and 3, if a cooling means is provided in the vicinity of the gate portion 7, the heat from the tip nozzle portion 6a of the third hot runner member 6 causes the molded golf ball to move. It is possible to avoid the influence of the portion in the vicinity of the gate portion 7 and obtain a golf ball having a better appearance.
As this cooling means, a means for circulating cold water or a heat pipe can be used.

In the present invention, a small-sized injection molding machine in which at least one of three or more hot runners can be built in the molding die may be used.

The type of golf ball molded according to the present invention is not particularly limited, and it may be a solid golf ball such as a one-piece, two-piece, three-piece golf ball or a thread-wound golf ball. It is suitable for injection molding. In this case, as shown in FIG. 10, the cover can be formed by inserting the core into the cavity and injecting the molding material for the cover into the gap between the core and the wall surface of the cavity. The cover material may be injection-moldable and is not particularly limited.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the present invention.

[0029]

The golf ball injection molding method and injection molding die of the present invention have the following effects. (1) Post processing after injection molding of a golf ball can be reduced or eliminated. (2) By eliminating the post-processing, defects in the process are eliminated. (3) Factors such as variations in the flight of golf balls due to post-processing can be reduced or eliminated, and quality is improved. (4) Waste of molding material is eliminated. (5) Since the gate diameter can be increased, high-speed and low-pressure injection can be performed, and molding defects such as burrs and welds are reduced. (6) Equipment for post-processing can be simplified or omitted. (7) The cycle is shortened (lead time is shortened). (8) It becomes easy to mold a seamless golf ball having dimples on the split surface of the mold. (9) High-speed, low-pressure injection becomes easy, and thin cover molding becomes easy (note that the conventional cold runner system
(Because the resin solidifies before entering, or the core is eccentric because it is forcibly filled with high pressure). (10) Since low-pressure injection and low-pressure mold clamping are possible, the life of the mold and molding machine is extended. (11) Since the residual stress of the resin can be reduced as compared with the molded product formed by the conventional mold, the durability of the ball is improved. (12) A multi-layer golf ball without eccentricity can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of a mold of the present invention.

FIG. 2 is a schematic sectional view showing a second embodiment of the mold of the present invention.

FIG. 3 is a schematic sectional view showing a third embodiment of the mold of the present invention.

FIG. 4 is a schematic sectional view showing a fourth embodiment of the mold of the present invention.

FIG. 5 is a schematic sectional view showing a fifth embodiment of the mold of the present invention.

FIG. 6 is a schematic sectional view showing a sixth embodiment of the mold of the present invention.

FIG. 7 is a schematic sectional view showing a seventh embodiment of the mold of the present invention.

FIG. 8 is an illustration of an arrangement mode of a tip nozzle portion of a hot runner member in a seventh embodiment.

FIG. 9 is a schematic side sectional view showing a conventional golf ball injection molding die.

FIG. 10 is a schematic plan sectional view showing a conventional golf ball injection molding die.

FIG. 11 is a perspective view of a golf ball molded by the same mold.

FIG. 12 is a schematic sectional view illustrating a gate cut state of the golf ball.

[Explanation of symbols]

 1 Upper Mold 2 Lower Mold 3 Cavity 4 First Hot Runner Member 5 Second Hot Runner Member 6 Third Hot Runner Member 7 Gate 8 Hot Runner 9 Valve Pin 10 Actuator 11 Heating Means

Claims (2)

[Claims] 1. A method for introducing a molten injection molding material for a golf ball into a mold cavity for injection molding a golf ball, wherein the molten molding material flows and a heating means for maintaining a molten state of the molding material. At least three runners provided in close proximity to each other communicate with the cavity through the gate portion, and the molding material is directly injected from the outlet end of the runner into the cavity through the gate portion. A characteristic golf ball injection molding method. 2. A golf ball injection molding die having an upper mold and a lower mold, wherein the upper mold and the lower mold are separably joined to each other to form a hollow spherical cavity therein. At least three hot runners through which the molding material flows are formed inside, and the tip nozzle portion of the hot runner member having a built-in heating means for holding the molten state of the molten molding material in the hot runner is described above. A mold for golf ball injection molding, characterized in that it is connected to the gate of the cavity.