JP2937077B2 - Golf ball injection molding method and golf ball injection molding mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art
As a method of manufacturing a two-piece golf ball by injection molding, for example, as shown in FIG. 6, a core 3 of a two-piece golf ball is placed inside a cavity 2 of a cover molding mold 1 composed of an upper mold 1a and a lower mold 1b. The core 3 is supported by a plurality of (in this example, four upper and lower) holding pins 4, and a molding material (cover material) 5 for a cover is injected into the cavity 2. A method of covering the core 3 with a cover having a large number of dimples by pulling out the holding pins 4 from the cover material 5 immediately before or simultaneously with the completion of the injection of the cover material 5 is generally adopted.

In this case, the injected cover material resin 5 flows into the gap between the core 3 and the peripheral wall of the cavity 2, and the flow of the resin usually converges at the deepest point of the cavity 2. Is covered with a cover material resin 5. For this reason, in the conventional injection molding apparatus, substantially cylindrical gas vent holes 6 are formed at the deepest locations of the cavities 2 of the lower mold 1b and the upper mold 1a, respectively, where the flow of the cover material resin 5 converges. At the same time, a substantially cylindrical fixing pin 7 having a diameter slightly shorter than the inner diameter of the hole 6 is inserted and fixed in the gas releasing hole 6, and the air in the cavity 2 is separated from the gas releasing hole 6 by the injection pressure. It escapes to the outside through the gap 8 between them. Further, in this case, the air is also discharged from the gap 10 between the inner peripheral surface of the insertion hole 9 for the holding pin 4 and the holding pin 4.

However, the gaps 8 and 10 are usually 2
When the length is larger than about / 100 to 4/100 mm, the resin 5 is inserted into the gaps 8 and 10, and a problem of generation of burrs occurs. For this reason, since the gaps 8 and 10 must be formed to be narrow as described above, it is difficult to discharge the air, and the welded product and the defective air are easily generated in the molded product. In addition, since the air is difficult to be discharged, it is necessary to increase the injection pressure, whereby burrs are easily generated and a large clamping force is required. Furthermore, when the injection speed is increased, the air cannot be completely removed, and it is difficult to form the cover thinly because welds or poor air entry are likely to occur. For example, it has been difficult to form the cover twice.

[0005] In addition, a method of degassing by exposing a degassing pin into and out of a cavity is also known (JP-A-63-45040).
The gap between the vent pin and the vent hole is also 5 to 30.
μm, and the gap is as narrow as above.

The present invention has been made in view of the above circumstances,
A golf ball injection molding method capable of easily and surely discharging air in a mold cavity, injecting a golf ball by preventing air entry defect and weld defect, and further preventing burrs as much as possible. An object of the present invention is to provide a mold for injection molding.

[0007]

In order to achieve the above object, the present invention provides (1) a method of injection molding a golf ball by introducing a molten golf ball injection molding material into a cavity of a mold. In the above-described method, a gas vent hole communicating with the cavity is formed in the mold, and a movable pin having a shape such that a tip end can close the cavity-side opening of the hole is movably disposed in the hole. With the tip of the pin not closing the opening, the molten molding material is injected and introduced into the cavity, and the air in the cavity is discharged from the hole and introduced into the cavity. A golf ball injection molding method characterized in that the pin is moved immediately before the molten molding material enters the hole to close the opening with the tip of the pin, and (2) In a golf ball injection molding mold having an upper mold and a lower mold and forming a hollow spherical cavity therein by joining these upper and lower molds in a separable manner, one of the upper mold and the lower mold or A gas vent hole communicating with the cavity is formed on both sides, and a movable pin formed in a shape capable of closing the cavity-side opening of the hole at the tip end is movably disposed in the hole. There is provided a golf ball injection molding mold characterized in that the opening can be opened and closed by moving the movable pin. In this case, when the distal end surface of the movable pin is formed in a hemispherical convex shape capable of forming a dimple of a golf ball or a concave shape capable of forming a land portion of a golf ball, and when the distal end portion of the pin closes the opening, It is preferable to form a part of the mold cavity surface at the front end surface to obtain a golf ball having a surface portion corresponding to the front end surface of the pin.

Here, the movement of the movable pin in the direction of the opening is started when the injection amount of the molding material by the injection molding machine reaches a predetermined value, or the movement of the movable pin in the direction of the opening is performed. Can be started when the pressure of the air discharged from the cavity to the vent hole reaches a predetermined value. Further, when the movable pin is retracted from the cavity, the opening is opened, and when the movable pin is advanced in the cavity direction, the distal end thereof is disposed so as to close the opening, or the movable pin is provided. The opening can be arranged so that the opening is opened when the tip is projected into the cavity, and the opening is closed with the tip when retracted from the cavity.

[0009]

The golf ball injection molding die of the present invention is constructed as described above, so that the opening area of the gas vent hole can be made large, and when the molding material is injected into the cavity, the air inside the cavity is removed. Is reliably and smoothly discharged from the gas vent hole, so that it is possible to reliably prevent the occurrence of poor air entry and poor weld in the golf ball,
Immediately before the molding material introduced into the cavity enters the gas vent hole, the opening is closed by the pin tip, so that it is possible to prevent the occurrence of burrs in this gas vent hole, and to have a good appearance,
A golf ball that can omit or simplify post-processing can be formed.

In addition, the distal end surface of the movable pin is formed in a hemispherical convex shape capable of forming a dimple of a golf ball or a concave shape capable of forming a land portion of a golf ball, and the distal end portion of the pin closes the opening. In this case, by forming a part of the mold cavity surface at the tip end surface, the opening area of the gas vent hole can be made larger, and post-processing of the pin mark can be omitted or simplified. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5, the same components as those in FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows an embodiment of a golf ball injection molding die according to the present invention. In this embodiment, the golf ball injection molding die is provided between holding pins 4 and 4 of an upper die 1a and a lower die 1b. Gas vent holes 11, 11 are formed so as to face each other (note that the holes 11, 11 are preferably provided on or near the weld line). In this case, the vent holes 11,
Reference numerals 11 denote openings 12, 1 communicating with the cavity 2, respectively.
Two sides are formed into small-diameter cylindrical columns 13 and 13, and the side opening to the outside is formed into large-diameter cylindrical columns 14 and 14, and movable pins 15 and 15 are movably disposed in the holes 11 and 11. These pins 15, 15 are connected to the small-diameter cylindrical portion 13,
And small-diameter cylindrical portions 16 that can be fitted into the holes 13 and large-diameter cylindrical portions 13
3, and a pin movable device 18, 18 is connected to the pin 15, 15, and the pin 1 is activated by the operation of the pin movable device 18, 18.
5 and 15 retreat from the cavity 2 side in the holes 11 and 11, and the tips of the small-diameter cylindrical portions 16 and 16 of the pins 15 and 15 recede from the rear ends of the large-diameter cylindrical portions 14 and 14 of the holes 11 and 11. By doing so, the openings 12, 12 are opened (FIG. 1).
(Retracted state shown in (B)) or from this position in the direction of the cavity, and the small-diameter cylindrical portions 16, 1 of the pins 15, 15
6 fits into the small-diameter cylindrical portions 13, 13 of the holes 11, 11, and the leading ends reach the ends of the openings to close the openings 12, 12 (shown in FIG. 1A). Advanced state). Here, the movable devices 18, 18 are connected to a control device (computer) 19 of an injection molding machine (not shown), and the injection amount of the molding material from the injection molding machine into the cavity 2 of the mold 1. Reaches a predetermined value (when the molding material is filled in the cavity 2), a signal is issued to the movable devices 18 to move the movable pins 15 in the direction of the cavity 2 as described above. Before the injection of the molding material into the mold cavity 2 from the injection molding machine, a signal is issued to move the movable pins 15 and 15 out of the cavity 2 as described above.

The openings 12, 1 of the holes 11, 11 are provided.
The diameter of No. 2 is not particularly limited, but when it is the same as the dimple diameter, it is preferably 1.5 to 4 mm.

The method of injection molding using the mold 1 is as follows.
It is basically the same as the conventional method using the mold shown in FIG.
In the present embodiment, the pins 15, 15 are connected to each other in FIG.
The molding material is introduced into the cavity 2 with the openings 12, 12 open as shown in FIG. As a result, the molding material is filled into the cavity 2 while the air in the cavity 2 is quickly and surely discharged from the openings 12, 12. Then, a predetermined amount of molding material is injected from the injection molding machine, the cavity 2 is filled with the molding material, and the movable devices 18, 18 are controlled by a signal from the control device 19 immediately before entering the holes 11, 11. Are pins 15,15
To the cavity 2, and the pins 15, 15
The small-diameter cylindrical portions 16, 16 advance to the ends of the openings to close the openings 12, 12.

Therefore, according to this method, the cavity 2
Since the air in the inside is smoothly and reliably discharged to the outside, it is difficult for the formed golf ball to have poor air entry or poor weldability, and the pins 15, 15, before the molding material enters the holes 11, 11. 15 small-diameter cylindrical sections 16, 16
Are fitted into the small-diameter cylindrical portions 13, 13 of the holes 11, 11, and extend to the ends of the openings to close the openings 12, 12, so that burrs are less likely to occur.

In this case, the front end surface of the pin 15 is
As shown in FIG. 3, the pin 15 may be formed in a hemispherical convex shape capable of forming a dimple of a golf ball, or may be formed in a concave shape capable of forming a land portion of a golf ball as shown in FIG.
It is preferable that the tip end surface of the pin 15 can form a mold cavity surface when it is advanced to the opening end of the opening, so that the opening area of the opening portion 12 can be increased, and the pin mark is eliminated, and the pin mark is eliminated. Post-processing is omitted or simplified. In the figure, reference numeral 2a denotes a mold cavity surface, and 2b denotes a dimple-forming projection. When the land portion is formed by the tip of the pin, the flat shape of the tip of the pin may be a circle, a polygon such as a triangle, a square, a rectangle, a hexagon, an octagon, a human shape, an ellipse, a gourd, or a ten. It can be formed into various shapes such as a letter shape, and the shape of the opening 12 can be changed accordingly.

Further, as shown in FIG. 4, the shape of the movable pin 15 is such that the tip 20 has a small diameter column shape, the intermediate portion 21 has a frustum shape, and the like.
The rear portion 22 has a large-diameter columnar shape, and the axial length of the large-diameter columnar rear portion 22 is formed to be longer than the total axial length of the small-diameter columnar tip portion 20 and the frustum-shaped intermediate portion 21. When the pin 15 is advanced, the rear portion 22 is first fitted into the large-diameter peripheral wall surface 11a of the hole 11 into which the pin 15 can be fitted. The gap (clearance) formed by 12 is made as narrow as possible. Further, the tip portion 20 of the pin 15 can be accurately and concentrically arranged within the opening portion 12 (without bias). Thereby, generation of burrs can be further reduced. Further, the tip 20 and the inner surface of the opening 12 can be prevented from being rubbed with each other, so that pin contamination does not occur.

In the above embodiment, when the pin 15 is withdrawn from the cavity 2, the opening 12 is opened,
Although the opening 12 is configured to close when it advances in the direction, as shown in FIG. 5, when filling the molding material into the cavity 2, the tip of the pin 15 is projected into the cavity 2, and the opening 12 is closed. When the portion 12 is opened and the molding material is filled in the cavity 2, the pin 15 may be withdrawn from the cavity 2 side and the opening 12 may be closed at the tip.

Further, when the pin advances or retracts, the air pressure when air is discharged from the cavity to the hole 11 is detected, and when the air pressure reaches a predetermined value (for example, when the pressure becomes atmospheric pressure), the pin closes the opening. The movable device can be operated so as to perform the operation.

The type of golf ball formed by the present invention is not particularly limited, and may be a solid golf ball such as a one-piece, two-piece or three-piece golf ball or a thread-wound golf ball. Is suitably used for injection molding. In this case, as shown in FIGS. 1 and 2, a cover can be formed by putting a core into the cavity and injecting a cover molding material into a gap between the core and the cavity wall surface. The cover material is not particularly limited as long as it can be injection molded.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and may be variously modified without departing from the gist of the present invention.

[0022]

According to the present invention, the area of the opening of the gas vent hole can be made large, so that the air in the cavity can be reliably and smoothly discharged, and weld defects and air entry defects are reduced. In addition, burrs are less likely to occur in the gas vent hole. In addition, since air can be satisfactorily vented from the cavity, low-pressure injection and low-pressure mold clamping can be performed, so that the occurrence of burrs is reduced from this point.
Therefore, hole marks and burrs are reduced, so that post-processing is omitted or simplified.Therefore, defects in the post-processing step are eliminated, and factors such as variation in golf ball flight due to post-processing can be reduced or eliminated. Is improved. Furthermore, since low-pressure injection and low-pressure mold clamping can be performed as described above, a thin cover can be easily molded, and the life of the mold and the molding machine can be extended. In addition, by adopting a configuration in which the pin tip surface is adapted to the shape of the golf ball cavity so that dimples and land portions of the golf ball can be formed, the opening area of the gas vent hole can be increased, and furthermore, after the pin mark No processing is required.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a mold according to one embodiment of the present invention;
(A) shows a state where the opening is closed with a pin, and (B) shows a state where the opening is opened.

FIG. 2 is a partially omitted cross-sectional view showing another embodiment of the present invention;
An example is shown in which the pin tip is formed in a hemispherical convex portion capable of forming a dimple.

FIG. 3 is a partially omitted cross-sectional view showing another embodiment of the present invention;
The example which the tip of the pin was formed in the shape which can form a land part is shown.

FIG. 4 is a partially omitted sectional view showing still another embodiment of the present invention.

5A and 5B show still another embodiment of the present invention, wherein FIG. 5A shows a state where an opening is opened, and FIG. 5B shows a state where the opening is closed.

FIG. 6 is a schematic sectional view of a conventional mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 1a Upper mold 1b Lower mold 2 Cavity 3 Core 4 Holding pin 5 Molding material 11 Gas vent hole 12 Opening 15 Movable pin 18 Pin movable device 19 Control device 20 Optical part 21 Intermediate part 22 Rear part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-178199 (JP, A) JP-A-5-208053 (JP, A) JP-A-5-3933 (JP, A) JP-A-4- 67920 (JP, A) JP-A-3-178415 (JP, A) JP-A-61-246018 (JP, A) JP-A-61-213068 (JP, A) JP-A-52-30863 (JP, A) 63-80110 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/00-45/84 A63B 45/00

Claims (9)

(57) [Claims] 1. A method for injection molding a golf ball by introducing a molten golf ball injection molding material into a cavity of a mold, wherein a gas vent hole communicating with the cavity is formed in the mold, and In the hole, a movable pin formed in a shape such that the tip can close the cavity-side opening of the hole is movably disposed, and the tip of the pin does not close the opening. The molten molding material is injected and introduced into the cavity, the air in the cavity is exhausted from the hole, and the pin is moved immediately before the molten molding material introduced into the cavity enters the hole. A golf ball injection molding method, wherein an opening is closed by a tip of the pin. 2. A tip end surface of the movable pin is formed in a hemispherical convex shape capable of forming a dimple of a golf ball or a concave shape capable of forming a land portion of a golf ball, and the tip end portion of the pin closes the opening. 2. The method according to claim 1, wherein the tip surface forms a part of the mold cavity surface to obtain a golf ball having a surface portion corresponding to the tip surface of the pin. 3. A golf ball injection molding mold having an upper mold and a lower mold, in which a hollow spherical cavity is formed by joining these upper and lower molds separably, said upper mold and said lower mold. A gas vent hole communicating with the cavity is formed in one or both of the two, and in this hole,
A movable pin whose tip is formed in a shape capable of closing the cavity-side opening of the hole is movably disposed, and the opening is opened and closed by moving the movable pin. Golf ball injection mold. 4. A tip end surface of the movable pin is formed in a hemispherical convex shape capable of forming a dimple of a golf ball or a concave shape capable of forming a land portion of a golf ball, and the tip end portion of the pin closes the opening. 4. The mold according to claim 3, wherein the tip surface forms a part of the mold cavity surface. 5. The mold according to claim 3, wherein movement of the movable pin in the direction of the opening is started when an injection amount of a molding material by an injection molding machine reaches a predetermined value. 6. The movable pin according to claim 3, wherein the movement of the movable pin in the direction of the opening is started when the pressure of the air discharged from the cavity to the gas vent hole reaches a predetermined value. Mold. 7. The movable pin is provided such that the opening is opened when the movable pin is retracted from the cavity, and the opening is closed at a tip end when the movable pin is advanced toward the cavity. 7. The mold according to claim 6. 8. The movable pin has a small-diameter pillar-shaped front end, a frustum-shaped intermediate part, a large-diameter pillar-shaped rear part, and a large-diameter pillar-shaped rear part having a small-diameter columnar tip and a frustum-shaped intermediate part. 8. The mold according to claim 7, wherein the mold is formed in a shape longer than the total axial length of the movable pin, and the hole is formed in a shape that can be fitted to the movable pin. 9. The movable pin is arranged such that the opening is opened when the tip of the movable pin is projected into the cavity, and the opening is closed by the tip when retracted from the cavity. 7. The mold according to any one of 3 to 6.