Golf ball mold

Abstract

To provide a mold 2 which may provide a golf ball excellent in appearance and flight symmetric properties.SOLUTION: A mold 2 has a pair of half molds 4. Each half mold 4 has a cavity plane including a plurality of pimples 16. The cavity plane includes a low latitude zone 18 and a high latitude zone 20. The low latitude zone 18 includes a low latitude base surface 22 whose inner diameter is larger than an inner diameter of a virtual ball of the cavity. The high latitude zone includes a high latitude base surface 24 whose inner diameter matches the inner diameter of the virtual ball. Each pimple protrudes from the low latitude base surface or the high latitude base surface. The pimple 16 crossing an equatorial plane Eq of the virtual ball or proximate to the equatorial plane Eq is partially or in whole body, protruded from the low latitude base surface 22.SELECTED DRAWING: Figure 5

Description

[[Technical Field]]

[0001] The present specification discloses a mold suitable for molding golf balls. [[Background Art]]

[0002] A conventional mold for golf balls includes an upper mold half and a lower mold half. When the upper mold half is mated with the lower mold half, a spherical cavity is formed. The cavity surface of this mold has a base surface and a large number of pimples. The position of the base surface coincides with the surface of the imaginary sphere of the cavity. Each pimple protrudes from the base surface.

[0003] A material is charged into this mold to mold an intermediate golf ball product. This intermediate product has a seam. The position of this seam corresponds to the parting line between the upper mold half and the lower mold half. The intermediate product further has a plurality of dimples. Each dimple has a shape obtained by inverting the shape of the corresponding pimple. A portion of the material enters the parting surface between the upper mold half and the lower mold half to form a flash. The flash adheres to the intermediate product. The position of this flash coincides with the position of the seam. This flash is removed by cutting. From the viewpoint of ease of removal, no dimples are provided on the seam. In other words, the pimples are arranged avoiding the parting line. An example of such a mold for golf balls is disclosed in Japanese Patent Laid-Open No. 2010-284531. [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Patent Laid-Open No. 2010-284531 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] When burrs are removed, the dimples surrounding the burrs may also be cut. This cutting can deform the dimples. This deformation can lead to a defect in the appearance of the golf ball. This deformation can also disrupt the flight symmetry of the golf ball. In particular, deformation is a concern for golf balls that have dimples that intersect the equator of a virtual sphere.

[0006] The applicant's intention is to provide a mold that can produce golf balls with excellent appearance and flight symmetry. [Means for solving the problem]

[0007] The golf ball mold disclosed herein has a pair of half-molds that, when joined together, form a substantially spherical cavity. Each half-mold has a cavity surface containing a plurality of pimples. This cavity surface has a low-latitude zone and a high-latitude zone. The low-latitude zone includes a low-latitude base surface whose inner diameter is greater than the inner diameter of the virtual sphere of the cavity. The high-latitude zone includes a high-latitude base surface whose inner diameter is equal to the inner diameter of the virtual sphere. Each pimple protrudes from either the low-latitude base surface or the high-latitude base surface. Pimples that intersect with or are close to the equatorial plane of the virtual sphere protrude partially or entirely from the low-latitude base surface. [Effects of the Invention]

[0008] From this mold, a golf ball containing dimples with the intended specifications can be obtained. This mold can contribute to the appearance and flight symmetry of the golf ball. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an exploded perspective view showing a golf ball mold according to one embodiment. [Figure 2] Figure 2 is a front view showing the mold from Figure 1. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 2. [Figure 4]Figure 4 is an enlarged view of the portion indicated by the symbol IV in Figure 3. [Figure 5] Figure 5 is an exploded view showing a portion of the cavity surface of the mold in Figure 3. [Figure 6] Figure 6 is a magnified view showing a portion of the cavity surface of the mold in Figure 3. [Figure 7] Figure 7 is an enlarged cross-sectional view along the line VII-VII in Figure 6. [Figure 8] Figure 8 is an enlarged cross-sectional view along the line VIII-VIII in Figure 7. [Figure 9] Figure 9 is an enlarged cross-sectional view along the line IX-IX in Figure 7. [Figure 10] Figure 10 is an enlarged cross-sectional view along line XX in Figure 6. [Figure 11] Figure 11 is an enlarged cross-sectional view along the line XI-XI in Figure 10. [Figure 12] Figure 12 is an enlarged cross-sectional view along the line XII-XII in Figure 10. [Figure 13] Figure 13 is a front view showing an intermediate golf ball obtained from the mold shown in Figure 1. [Figure 14] Figure 14 is an enlarged cross-sectional view showing a portion of the intermediate golf ball product shown in Figure 13. [Figure 15] Figure 15 is a front view showing a golf ball obtained from the intermediate product shown in Figure 13. [Figure 16] Figure 16 is an enlarged cross-sectional view showing a portion of the golf ball in Figure 15. [Figure 17] Figure 17 is a front view showing the dimple pattern of the golf ball in Figure 15. [Figure 18] Figure 18 is a plan view showing the dimple pattern from Figure 17. [Figure 19] Figure 19 is a magnified view showing a portion of the mold in Figure 3. [Figure 20] Figure 20 is a cross-sectional view showing a further enlarged portion of the mold from Figure 4. [Modes for carrying out the invention]

[0010] Hereinafter, preferred embodiments will be described in detail with appropriate reference to the drawings.

[0011] The mold 2 for golf balls shown in Figure 1 includes a pair of mold halves 4. Specifically, this mold 2 consists of an upper mold 6 and a lower mold 8. Each mold half 4 has a parting surface 10 and a cavity surface 12.

[0012] As indicated by arrow A1 in Figure 1, the upper mold 6 descends relative to the lower mold 8. The mold 2 is clamped when the upper mold 6 is mated with the lower mold 8. In this state, the parting surface 10a of the upper mold abuts against the parting surface 10b of the lower mold 8.

[0013] The clamped mold 2 is shown in Figures 2 and 3. In this mold 2, the cavity 14 is formed by mating the upper mold 6 with the lower mold 8. The cavity 14 has a substantially spherical shape. In Figures 2 and 3, the symbol Eq represents the Equator or an Equator Plane. The equator has a circular shape. The equatorial plane is a plane containing the equator. The equator Eq is defined assuming that the topmost point of the cavity surface 12 of the upper mold 6 is the north pole Pn of a globe (see Figure 3) and the bottommost point of the cavity surface 12 of the lower mold 8 is the south pole Ps of the globe. The latitude of the north pole Pn and the south pole Ps is 90 degrees. The latitude of the equator Eq is 0 degrees.

[0014] As shown in Figure 3, each cavity surface 12 has a large number of pimples 16. The total number of pimples 16 in the entire mold 2 is generally from 250 to 550. In the present embodiment, the contour of each pimple 16 is circular. In Figure 3, only some of the pimples 16 are shown. In practice, a large number of pimples 16 are arranged over the entire cavity surface 12. The parting surface 10 of the mold half 4 is uneven.

[0015] Figure 4 is an enlarged view of the portion indicated by the symbol IV in Figure 3. Figure 4 shows the cavity surface 12 assuming that the pimple 16 does not exist. This cavity surface 12 has a low-latitude zone 18 and a high-latitude zone 20. The dashed line indicated by the symbol L1 in Figure 4 is the boundary line between the low-latitude zone 18 and the high-latitude zone 20. The boundary line L1 is parallel to the equator Eq.

[0016] The low-latitude zone 18 extends from the parting surface 10 to the boundary line L1. The low-latitude zone 18 extends along the equator Eq. The low-latitude zone 18 has a ring shape. The low-latitude zone 18 includes the low-latitude base surface 22. The low-latitude base surface 22 is the surface of the low-latitude zone 18 other than the pimple 16. The curve indicated by the sign L2 in Figure 4 is a virtual sphere of the cavity 14. The virtual sphere L2 coincides with the cavity surface 12 when it is assumed that there is no pimple 16 and low-latitude zone 18. The inner diameter D1 of the low-latitude base surface 22 is larger than the inner diameter D2 of the virtual sphere L2.

[0017] The high-latitude zone 20 extends from the boundary line L1 to the pole Po (see Figure 3). The high-latitude zone 20 has a bowl shape. The high-latitude zone 20 includes the high-latitude base plane 24. The high-latitude base plane 24 is the surface of the high-latitude zone 20 other than the pimple 16. The inner diameter of the high-latitude base plane 24 coincides with the inner diameter D2 of the virtual sphere L2.

[0018] Since the inner diameter D1 of the low-latitude base plane 22 is larger than the inner diameter D2 of the virtual sphere L2, and the inner diameter of the high-latitude base plane 24 coincides with the inner diameter D2 of the virtual sphere L2, the shape of the cavity 14 is not strictly spherical. In this specification, such a state is referred to as "substantially spherical."

[0019] As mentioned above, the cavity surface 12 has a number of pimples 16. Each pimple 16 may belong to the low latitude zone 18. This pimple 16 may also belong to the high latitude zone 20. This mold 2, (1) Pimple 16, which is entirely located in the low latitude zone 18. (2) Pimple 16, which is entirely located in the high latitude zone 20. and (3) Pimple 16 that is partially in the low latitude zone 18 and partially in the high latitude zone 20 It may have.

[0020] In other words, this mold 2 is, (1) Pimple 16 that protrudes entirely from the low latitude base plane 22 (2) Pimple 16 that protrudes entirely from the high-latitude base plane 24 and (3) Pimples 16 that partially protrude from the low-latitude base plane 22 and partially protrude from the high-latitude base plane 24 It may have.

[0021] Figure 5 shows a magnified view of a portion of the cavity surface 12 with the mold 2 open. Figure 5 shows the low-latitude base surface 22a of the upper mold 6, the high-latitude base surface 24a of the upper mold 6, and the low-latitude base surface 22b and high-latitude base surface 24b of the lower mold 8. Figure 5 also shows the pimple 16.

[0022] As shown in Figure 5, the parting surface 10 of each half-mold 4 consists of a flat surface 26, a ridge 28, and a recess 30. The flat surface 26 is aligned with the equatorial plane Eq. The ridge 28 protrudes from the equatorial plane Eq. The recess 30 is recessed below the equatorial plane Eq. The ridge 28 contains a portion of the pimple 16. The outer edge of the ridge 28 is an arc. This outer edge substantially coincides with the contour of the pimple 16. Since the ridge 28 protrudes from the equatorial plane Eq, the pimple 16 contained within this ridge 28 intersects with the equatorial plane Eq. In this embodiment, the ridge 28 is a curved surface. The ridge 28 may also be a flat surface. In this embodiment, the recess 30 is a curved surface. The recess 30 may also be a flat surface. The parting surface 10 may have the shape of a combination of multiple curved surfaces.

[0023] Figure 6 shows the cavity surface 12 of the mold 2 in a closed state. In Figure 6, the ridge 28a of the upper mold 6 is fitted into the recess 30b of the lower mold 8, and the ridge 28b of the lower mold 8 is fitted into the recess 30a of the upper mold 6. The flat surface 26a of the upper mold 6 is in contact with the flat surface 26b of the lower mold 8.

[0024] As is clear from Figures 5 and 6, the first row of pimples 16 from the equatorial plane Eq belongs partially to the low-latitude zone 18 and partially to the high-latitude zone 20. In other words, the first row of pimples 16 from the equatorial plane Eq protrudes partially from the low-latitude base plane 22 and partially from the high-latitude base plane 24.

[0025] Pimple 16, the second row from the equatorial plane Eq, is entirely located in the high-latitude zone 20. In other words, pimple 16, the second row from the equatorial plane Eq, protrudes entirely from the high-latitude base plane 24.

[0026] In this embodiment, there are no pimples 16 that are entirely located in the low-latitude zone 18. In other words, there are no pimples 16 that are entirely located in the low-latitude base plane 22. The mold 2 may have pimples 16 that are entirely located in the low-latitude zone 18.

[0027] In Figure 5, the symbol 161 represents an intersecting pimple. The intersecting pimple 161 intersects the equatorial plane Eq. In Figure 5, the symbol 162 represents a nearby pimple. The nearby pimple 162 is nearby the equatorial plane Eq. The nearby pimple 162 satisfies the following conditions (1) to (3). (1) The perpendicular line drawn from the center of the outline of this pimple 162 to the equatorial plane Eq does not intersect with any other pimple 16. (2) The latitude of the center of the outline of Pimple 162 is less than 10°. (3) This pimple 162 is not a cross pimple 161.

[0028] Figure 7 is an enlarged cross-sectional view along line VII-VII in Figure 6. Figure 8 is an enlarged cross-sectional view along line VIII-VIII in Figure 7. These figures show the intersecting pimple 161. As shown in Figure 8, the intersecting pimple 161 has a convex surface 32 and a side surface 34. The convex surface 32 is convex radially inward of the virtual sphere L2. The side surface 34 is located between the convex surface 32 and the low-latitude base plane 22. The side surface 34 extends in the height direction (up and down direction in Figure 8) of the convex surface 32. The side surface 34 extends from the edge Ed of the convex surface 32 to the low-latitude base plane 22. In Figure 8, the intersecting pimple 161 protrudes from the low-latitude base plane 22.

[0029] Figure 9 is an enlarged cross-sectional view along the line IX-IX in Figure 7. A convex surface 32 is shown in Figure 9. At the position shown in Figure 9, the intersecting pimple 161 does not have a side surface 34. In Figure 9, the intersecting pimple 161 protrudes from the high-latitude base plane 24.

[0030] In this embodiment, the intersecting pimple 161 partially protrudes from the low-latitude base plane 22 and partially protrudes from the high-latitude base plane 24. In other words, at least a portion of the intersecting pimple 161 protrudes from the low-latitude base plane 22. The intersecting pimple 161 may also protrude entirely from the low-latitude base plane 22.

[0031] Figure 10 is an enlarged cross-sectional view along line XX in Figure 6. Figure 11 is an enlarged cross-sectional view along line XI-XI in Figure 10. These figures show the nearby pimple 162. As shown in Figure 11, the nearby pimple 162 has a convex surface 32 and a side surface 34. The convex surface 32 is convex radially inward of the virtual sphere L2. The convex surface 32 is separated from the low latitude base plane 22. The side surface 34 extends in the height direction of the convex surface 32 (up and down direction in Figure 11). The side surface 34 extends from the edge Ed of the convex surface 32 to the low latitude base plane 22. In Figure 11, the nearby pimple 162 protrudes from the low latitude base plane 22.

[0032] Figure 12 is an enlarged cross-sectional view along the line XII-XII in Figure 10. Figure 12 shows the convex surface 32. At the position shown in Figure 12, the nearby pimple 162 does not have a side surface 34. In Figure 12, the nearby pimple 162 protrudes from the high-latitude base surface 24.

[0033] In this embodiment, the nearby pimple 162 partially protrudes from the low-latitude base plane 22 and partially protrudes from the high-latitude base plane 24. In other words, at least a portion of the nearby pimple 162 protrudes from the low-latitude base plane 22. The nearby pimple 162 may also protrude entirely from the low-latitude base plane 22.

[0034] This mold 2 is used for molding golf balls. This mold 2 can be used in compression molding, injection molding, casting, etc. In any of these methods, material is poured into mold 2. This material is pressurized and flows within mold 2, and an intermediate golf ball is obtained.

[0035] Figures 13 and 14 show the intermediate golf ball 36. This intermediate 36 has a shape in which the shape of the cavity surface 12 is inverted. Specifically, the surface of this intermediate 36 has a large diameter zone 38 and a pair of small diameter zones 40. In Figure 13, the dashed line indicated by the symbol L3 is the boundary line between the large diameter zone 38 and the small diameter zones 40. The boundary line L3 is parallel to the equatorial Eq of the intermediate 36. The large diameter zone 38 is formed by the low latitude zone 18 of the mold 2. The small diameter zones 40 are formed by the high latitude zone 20 of the mold 2. In Figure 14, the curve indicated by the symbol L4 is a virtual sphere of the golf ball. The virtual sphere L4 is the surface of the golf ball assuming that there are no dimples, which will be described later.

[0036] As shown in Figure 13, the large-diameter zone 38 extends from the equatorial plane Eq to the boundary line L3. The large-diameter zone 38 extends along the equatorial Eq. The large-diameter zone 38 has a ring shape. As shown in Figure 14, the outer diameter D3 of the large-diameter zone 38 is larger than the outer diameter D4 of the virtual sphere L4.

[0037] As shown in Figure 13, each small-diameter zone 40 extends from the boundary line L3 to the pole point Po. The small-diameter zones 40 have a bowl shape. As shown in Figure 14, the outer diameter of the small-diameter zones 40 coincides with the outer diameter D4 of the virtual sphere L4.

[0038] The intermediate golf ball 36 has a number of dimples 42 on its surface. The number of dimples 42 is the same as the number of pimples 16 in mold 2. Each dimple 42 has a shape that is an inverse of the shape of pimple 16. Figure 14 shows a dimple 421 formed by intersecting pimples 161. This dimple 421 is partially recessed from the large diameter zone 38 and partially recessed from the small diameter zone 40. This dimple 421 has a step 44. This step 44 originates from the side surface 34 of the pimple 16.

[0039] The golf ball intermediate product 36 also has burrs 46. The burrs 46 are formed when material enters the gap between the parting surface 10 of the upper mold 6 and the parting surface 10 of the lower mold 8. The formation of burrs 46 is unavoidable. As shown in Figure 13, the burrs 46 are ring-shaped. As shown in Figure 14, the burrs 46 protrude from the large diameter zone 38.

[0040] The outermost layer of this intermediate product 36 is made of a rubber composition or a resin composition. For the intermediate product 36 for a one-piece ball, the typical material is a rubber composition. For the intermediate product 36 for a golf ball having two or more layers, the typical material is a resin composition. A resin composition in which the base material is an ionomer resin or polyurethane is preferred.

[0041] The area near the equatorial Eq of the golf ball intermediate 36 is machined. Machining can be done with sandpaper, a grinding wheel, a cutter, etc. Machining is performed while the intermediate 36 is rotated around a line passing through both poles Po. Machining may also be performed while the intermediate 36 is rotated randomly using a centerless cutting device, barrel, etc. Machining removes burrs 46. Machining further eliminates the large diameter zone 38. The outer diameter of the machined area after elimination roughly matches the outer diameter of the virtual sphere L4. Machining eliminates the step 44. This machining yields a golf ball. This golf ball 48 is shown in Figures 15 and 16. In Figures 15 and 16, the large diameter zone 38 before machining is shown by a dashed line. The dimple pattern of this golf ball 48 is shown in Figures 17 and 18. The diameter of this golf ball 48 is preferably 42.67 mm or larger. The diameter is preferably 43.00 mm or less, more preferably 42.90 mm or less, and particularly preferably 42.80 mm or less. The golf ball 48 may have a coating layer on its surface.

[0042] As mentioned above, when removing the burr 46, the large-diameter zone 38 is also cut along with the burr 46. When removing the burr 46, the large-diameter zone 38 suppresses excessive cutting of the dimple 421. Therefore, the dimple 421 after cutting has the intended specifications (diameter, depth, volume, area, cross-sectional shape, etc.). This golf ball 48 has excellent appearance. In this golf ball 48, the dimple 421 near the equatorial equilibrium contributes significantly to the aerodynamic characteristics. This golf ball 48 has excellent flight symmetry.

[0043] From the viewpoint of suppressing excessive cutting of the dimples 421, the latitude of boundary line L3 is preferably 2° or more, more preferably 3° or more, and particularly preferably 4° or more. From the viewpoint of ease of cutting, this latitude is preferably 10° or less, more preferably 8° or less, and particularly preferably 7° or less. The latitude of boundary line L3 coincides with the latitude of boundary line L1 in mold 2.

[0044] Figure 19 is an enlarged view showing a portion of mold 2 in Figure 3. This figure shows pimple 16, the equatorial equilibrium, and boundary line L1. Pimple 16 is partially located in the low-latitude zone 18 and partially in the high-latitude zone 20. In Figure 19, the symbol P1 represents the intersection of the outline of pimple 16 and boundary line L1, the symbol P2 represents a point on the outline of pimple 16 that is in the low-latitude zone 18, the symbol P3 represents the intersection of the outline of pimple 16 and boundary line L1, and the symbol P4 represents a point on the outline of pimple 16 that is in the high-latitude zone 20.

[0045] Of the contour, the portion passing from point P1 through point P2 to point P3 is in the low-latitude zone 18. Of the contour, the portion passing from point P1 through point P4 to point P3 is in the high-latitude zone 20. In each pimple 16, the ratio Pe of the length of the contour in the low-latitude zone 18 to the total length of the contour is preferably 25% or more. From a mold 2 with this ratio Pe of 25% or more, a golf ball 48 with excellent appearance and flight symmetry can be obtained. From this viewpoint, this ratio Pe is more preferably 35% or more, and particularly preferably 45% or more. The ratio Pe may also be 100%. In the case of a mold 2 in which the contour of the pimple 16 is non-circular, the ratio Pe is similarly calculated based on the contour. Examples of non-circular pimples include elliptical pimples and polygonal pimples. Figure 19 shows an intersecting pimple 161, but the ratio Pe in the adjacent pimple 162 is also preferably within the above range.

[0046] In Figures 8 and 11, the arrow Hi represents the height of the side surface 34. As is clear from Figures 7 and 10, the height Hi varies depending on the latitude. The maximum value Hm of the height Hi in the pimple 16 is preferably 20 μm or more. In the golf ball intermediate product 36 obtained from mold 2 with a maximum value Hm of 20 μm or more, the large diameter zone 38 sufficiently suppresses excessive cutting of the dimple 421 when removing the burrs 46. From this intermediate product 36, a golf ball 48 with excellent appearance and flight symmetry can be obtained. From this viewpoint, this maximum value Hm is more preferably 30 μm or more, and particularly preferably 40 μm or more. From the viewpoint of ease of cutting, the maximum value Hm is preferably 150 μm or less, more preferably 100 μm or less, and particularly preferably 80 μm or less.

[0047] From the viewpoint of the appearance and flight symmetry of the golf ball 48, it is preferable that the height Hi of the side surface 34 on the equatorial plane Eq is the maximum value Hm at the crossing pimple 161. The height Hi may be the maximum value Hm at multiple locations, both on the equatorial plane Eq and elsewhere.

[0048] Figure 20 shows a further enlarged view of a portion of mold 2 in Figure 4. In Figure 20, the four points indicated by the symbols P5-P8 are located on the low-latitude base plane 22. Point P5 is on the equatorial plane Eq. Point P8 is on the boundary line L1. In the cross-sectional shape of the low-latitude base plane 22, the portion from point P5 to point P6 is a straight line, the portion from point P6 to point P7 is a straight line, and the portion from point P7 to point P8 is also a straight line. In other words, this cross-sectional shape contains multiple straight lines. The golf ball intermediate product 36 obtained from mold 2 having this low-latitude base plane 22 can be easily machined.

[0049] In this embodiment, points P5, P6, and P7 lie on a single arc. The center of this arc coincides with the center of the virtual sphere L2. The distance of the low-latitude base plane 22 from the virtual sphere L2 varies with latitude. In this embodiment, this distance is maximum at points P5, P6, and P7. The golf ball intermediate 36 obtained from the mold 2 having this low-latitude base plane 22 can be easily machined.

[0050] In this low-latitude base plane 22, the portion from point P7 to point P8 is a straight line, so the difference between the direction of this low-latitude base plane 22 at point P8 and the direction of the high-latitude base plane 24 is small. In the intermediate golf ball product 36 obtained from this mold 2, it is less likely that unmachined material will remain in the large-diameter zone 38 (see Figure 14).

[0051] The cross section from point P5 to point P8 may be a combination of multiple curves. The cross section from point P5 to point P8 may be a combination of straight lines and curves. Preferably, the cross section from point P5 to point P8 has a corner between two lines. This corner can be used as a marker in fine-tuning the cutting device for the appropriate cutting depth of the burr 46 and the large diameter zone 38. [Examples]

[0052] The effects of the golf ball mold according to the following examples will be revealed, but the scope disclosed herein should not be interpreted as limiting based on the description of these examples.

[0053] [Example 1] A mold shown in Figure 1-12 was prepared. In this mold, the ratio Pe of the length of the contour in the low-latitude zone to the total length of the contour was 75%. The latitude of boundary line L1 was 6°. The maximum height Hm of the side of the intersecting pimple was 75 μm. The location of this maximum value Hm was on the equatorial plane (latitude 0°). A core was prepared having a center made of a rubber composition and an intermediate layer made of an ionomer resin composition. The core was covered with two half-shells made of a polyurethane composition. This core and half-shell were placed in the mold, and the half-shell was pressurized and heated to obtain a golf ball intermediate. This intermediate had a large diameter zone and burrs. These large diameter zones and burrs were removed by cutting with sandpaper. This intermediate was coated with a clear paint based on two-component curing polyurethane to obtain a golf ball with a diameter of approximately 42.7 mm and a mass of approximately 45.4 g.

[0054] [Examples 2-5] A golf ball was obtained in the same manner as in Example 1, except that molds with different maximum values ​​Hm were used.

[0055] [Examples 6-8] A golf ball was obtained in the same manner as in Example 1, except that molds with different ratios Pe and latitudes for the boundary line L1 were used.

[0056] [Example 9] A golf ball was obtained in the same manner as in Example 1, except that a mold was used in which the latitude of the position of the maximum value Hm was 3°.

[0057] [Example 10] A golf ball was obtained in the same manner as in Example 1, except that a mold with a boundary line L1 at a latitude of 15° was used.

[0058] [Comparative Example 1] A golf ball was obtained in the same manner as in Example 1, except that a mold without an equatorial zone was used.

[0059] [Comparative Example 2] A golf ball was obtained in the same manner as in Example 1, except that a mold was used that did not have an equatorial zone and had a flat parting surface.

[0060] [Workability] In the burr removal process, work efficiency was rated AD based on the time required to optimize the cutting machine conditions. The results are shown in Table 1-3 below.

[0061] [Flight Symmetry] The lift and drag coefficients were measured during PH rotation and POP rotation, and the flight symmetry was graded AD. The results are shown in Table 1-3 below.

[0062] [exterior] Golf balls were visually inspected and their appearance was graded AD. The results are shown in Table 1-3 below.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] As shown in Table 1-3, golf balls with excellent performance can be obtained from the molds of each embodiment. The superiority of this mold is clear from these evaluation results.

[0067] [Disclosure items] Each of the following items is a disclosure of a preferred embodiment.

[0068] [Item 1] It comprises a pair of half-molds that, when joined together, form a cavity that is substantially spherical in shape. Each half-mold has a cavity surface containing multiple pimples, The above cavity surface has a low-latitude zone and a high-latitude zone, The low-latitude zone includes a low-latitude base plane whose inner diameter is larger than the inner diameter of the virtual sphere of the cavity. The above high-latitude zone includes a high-latitude base plane whose inner diameter coincides with the inner diameter of the above virtual sphere. Each pimple protrudes from the low-latitude base plane or the high-latitude base plane. A golf ball mold in which pimples intersecting or adjacent to the equatorial plane of the virtual sphere described above partially or entirely protrude from the low-latitude base plane.

[0069] [Item 2] The mold described in item 1, wherein the contour of the pimple that intersects with or is close to the equatorial plane belongs to the low latitude zone for a length of 25% or more of the total length of the contour.

[0070] [Item 3] A mold as described in item 1 or 2, wherein the latitude of the boundary between the low-latitude zone and the high-latitude zone is 10° or less.

[0071] [Item 4] A pimple that intersects or is close to the equatorial plane has a convex surface and a lateral surface. A mold according to any one of items 1 to 3, wherein the convex surface is separated from the low-latitude base surface, the side surface extends in the height direction of the convex surface, and the edge of this convex surface extends to the low-latitude base surface.

[0072] [Item 5] The mold described in item 4, wherein the maximum height of the above-mentioned side surface is 20 μm or more.

[0073] [Item 6] The mold according to item 4 or 5, wherein the above-mentioned side surface has the maximum height in the above-mentioned equatorial plane.

[0074] [Item 7] A mold according to any of items 4 to 6, wherein the cross-sectional shape of the low-latitude base surface described above includes multiple straight lines.

[0075] [Item 8] (1) A step of filling a mold having a pair of half-molds that, when joined together, form a substantially spherical cavity, each half-mold having a cavity surface containing a plurality of pimples, the cavity surface having a low-latitude zone and a high-latitude zone, the low-latitude zone including a low-latitude base surface whose inner diameter is larger than the inner diameter of the virtual sphere of the cavity, the high-latitude zone including a high-latitude base surface whose inner diameter matches the inner diameter of the virtual sphere, each pimple protruding from the low-latitude base surface or the high-latitude base surface, and pimples that intersect with or are close to the equatorial plane of the virtual sphere protrude partially or entirely from the low-latitude base surface, (2) A step of pressurizing the above material in the above mold to obtain a golf ball intermediate product having a shape in which the shape of the cavity surface is inverted. and (3) The process of cutting the area near the equator of the golf ball intermediate product. A method for manufacturing golf balls, comprising the following features. [Industrial applicability]

[0076] The aforementioned mold can produce golf balls of various structures. This mold can also produce golf balls of various materials. [Explanation of Symbols]

[0077] 2. Golf ball mold 4...Half mold 6...Upper mold 8...Lower mold 10. Parting surface 12···Cavity surface 14... Cavity 16... Pimple 18. Low latitude zone 20...High latitude zone 22. Low-latitude base plane 24. High-latitude base plane 26. Flat surface 28..Ridge 30 recess 32...convex surface 34...side view 36... Golf ball intermediate product 38...Large diameter zone 40... Small diameter zone 42 dimples 44 steps 46...Bali 48 golf balls 161... Crossed pimples 162... Proximity pimple 421... Dimple

Claims

1. It comprises a pair of half-molds that, when joined together, form a cavity that is substantially spherical in shape. Each half-mold has a cavity surface containing multiple pimples, The above cavity surface has a low-latitude zone and a high-latitude zone, The low-latitude zone includes a low-latitude base plane whose inner diameter is larger than the inner diameter of the virtual sphere of the cavity. The above high-latitude zone includes a high-latitude base plane whose inner diameter coincides with the inner diameter of the above virtual sphere. Each pimple protrudes from the low-latitude base plane or the high-latitude base plane. The pimples intersecting the equatorial plane of the virtual sphere protrude, partially or entirely, from the low-latitude base plane. The pimples intersecting the equatorial plane have a convex surface and a lateral surface. The above-mentioned convex surface is separated from the above-mentioned low-latitude base surface, the above-mentioned side surface extends in the height direction of the above-mentioned convex surface and extends from the edge of this convex surface to the above-mentioned low-latitude base surface, A golf ball mold in which the above-mentioned side surface has the greatest height in the above-mentioned equatorial plane.

2. The mold according to claim 1, wherein the contour of the pimple intersecting the equatorial plane belongs to the low-latitude zone for a length of 25% or more of the total length of the contour.

3. The mold according to claim 1 or 2, wherein the latitude of the boundary between the low-latitude zone and the high-latitude zone is 10° or less.

4. The mold according to claim 1, wherein the maximum value of the height of the above-mentioned side surface is 20 μm or more.

5. The mold according to claim 1, wherein the cross-sectional shape of the low-latitude base surface includes a plurality of straight lines.

6. (1) A mold having a pair of half-molds that, when joined together, form a substantially spherical cavity, each half-mold having a cavity surface containing a plurality of pimples, the cavity surface having a low-latitude zone and a high-latitude zone, the low-latitude zone including a low-latitude base surface whose inner diameter is larger than the inner diameter of the virtual sphere of the cavity, the high-latitude zone including a high-latitude base surface whose inner diameter matches the inner diameter of the virtual sphere, each pimple protruding from the low-latitude base surface or the high-latitude base surface, the pimple intersecting the equatorial plane of the virtual sphere protruding partially or entirely from the low-latitude base surface, the pimple intersecting the equatorial plane having a convex surface and a side surface, the convex surface being separated from the low-latitude base surface, the side surface extending in the height direction of the convex surface and reaching the low-latitude base surface from the edge of the convex surface, and the side surface having the maximum height at the equatorial plane, a process of filling a mold with material. (2) A step of pressurizing the material in the mold to obtain an intermediate golf ball having a shape in which the cavity surface is inverted. and (3) The process of cutting the area near the equator of the above-mentioned intermediate golf ball product. A method for manufacturing golf balls, comprising the following features.

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