JP4500622B2 - Soft tennis ball and soft tennis ball manufacturing method - Google Patents

Description

  The present invention relates to a soft tennis ball, and more particularly to a structure of a rubber valve for air injection provided in a soft tennis ball for injecting air.

  The rubber material forming the soft tennis ball has a property of allowing air to pass through, so that slight air leakage occurs. Therefore, it is necessary for the user to appropriately inject air into the ball to keep the ball elasticity suitable for the game. Therefore, conventionally, injecting air into the ball is a solid rubber for air injection in which a hollow insertion needle with a sharp tip connected to an air pump is attached to a predetermined position inside the ball spherical shell. It was performed in a state of being pierced from the outside of the spherical shell toward the stopper (for example, Patent Document 1).

  However, there are some problems such as accidentally piercing the body with the insertion needle and puncturing the insertion needle into a place other than the predetermined inlet provided on the ball. In recent years, therefore, air has been injected using an air pump provided with a hollow insertion rod having a rounded tip.

  Inside the spherical shell of the soft tennis ball into which air is injected using a pump equipped with this insertion rod, a rubber valve having a slit for inserting the insertion rod and introducing it into the ball is attached. An example of a soft tennis ball having such a rubber valve with a slit is shown in FIG. 3 (Patent Document 2).

  In the tennis ball 2 shown in FIG. 3, a rubber valve 23 is bonded and fixed with an adhesive so that the outer end faces a small hole 22 formed in a part of the ball spherical shell 21.

  The rubber valve 23 has a protruding portion 23a that engages with the ball shell 21 of the ball at the center of the outer end portion, and a thin flange portion 23b is formed so as to overlap the base portion of the protruding portion 23a. It is made of a solid rubber member in which a columnar body 23c is formed on the inner end side, and is integrally molded to form a single structure. An adhesive is applied to the outer surface side of the thin flange portion 23b.

  Moreover, the trunk | drum 23c is formed in the taper shape which decreases gradually as an outer diameter goes to an inner end part side from an outer end part side.

  The rubber valve 23 is formed with an introduction hole 23d, which is a bottomed opening for introducing the insertion rod 24 of the above-described unillustrated air pump in the center of the projection 23a, and a slit is formed in accordance with the introduction hole 23d. 23e is formed to penetrate to the inner end face 23f of the body portion 23c.

  The rubber valve 23 has a total weight of about 0.4 g to 0.8 g, and the rubber valve has a hardness of about 30 ° to 35 ° (measured by durometer type A manufactured by Shimadzu Corporation). . The thickness of the flange portion 23b is 0.3 to 0.8 mm, the diameter of the body portion 23c is 5 to 10 mm, the diameter of the small diameter portion is 3 to 8 mm, and the length of the rubber valve 23 is 5 to 11 mm. Is formed.

  When a pneumatic pump insertion rod 24, which is preliminarily coated with a silicone oil 25 as a lubricant and a sealing agent, is inserted into the small hole 22, the insertion rod 24 is guided by the introduction hole 23d and inserted into the slit 23e, and the ball Air can be injected into 2. Further, when the insertion rod 24 is pulled out, the air in the ball 2 does not leak outward due to the tightening force of the rubber valve 23 and the sealing action of the silicon oil 25.

JP 2001-161860 JP 2004-201733

  Unlike a basketball with a hard ball shell, a soft tennis ball has a very soft ball ball shell, so a very large impact force is applied to the rubber valve in actual use. Since it is required to endure such an impact and there is no air leakage, a rubber valve such as a basketball cannot be applied as it is.

  In order to prevent air leakage, for example, if the rubber valve is enlarged to increase the adhesion force applied to the slit, the air in the ball is difficult to leak.

  However, since a soft tennis ball is very lightweight, if the weight of the rubber valve increases, the overall balance of the ball may be lost, and an unexpected hitting trajectory may be drawn. Furthermore, since there are standards defined in the rules for the weight and shape of the ball, the weight of the rubber valve is naturally limited.

  The tennis ball 2 to which the rubber valve 23 is attached can prevent air leakage to some extent, and the total weight of the rubber valve 23 can be reduced.

  Therefore, an object of the present invention is to provide a soft tennis ball with high confidentiality that is lightweight, and further, air in the ball hardly leaks from the inlet to the outside, and a sufficient sealing effect can be obtained. To do.

According to a first aspect of the present invention, a columnar air injection rubber valve formed of a ball spherical shell and a solid rubber member bonded to a part of the ball spherical shell is provided. When, and a clamping member consists of heat-shrinkable tubing which is to be attached to a periphery of the rubber valve, the rubber valve includes a flange portion which is adhered to the inner peripheral surface of the ball spherical shell, the outer side from the flange portion A projection that engages with a small hole formed in the ball spherical shell, a bottomed opening that opens to the outer surface of the projection, and a columnar body that extends inward from the flange to the ball. And a slit formed in the rubber valve through the inner end surface of the body portion from the bottom surface of the opening, and the body portion is a columnar shape having different longitudinal and transverse lengths substantially parallel to the inner end surface. Formed in the length direction of the slit and the long diameter of the body Direction Metropolitan said slit formed through in a direction substantially orthogonal, said clamping member, after the coating over its length to the barrel periphery, in close contact with the body portion outer periphery by contracts is heated characterized in that tightening the body portion.

A second configuration of the present invention is characterized in that the body portion is formed in a substantially elliptical column shape having an outer diameter gradually increasing from the ball spherical shell side toward the inside of the ball.

A third configuration of the invention of the present application is a manufacturing method for manufacturing the soft tennis ball according to claim 1 or 2 , wherein the tightening member made of the heat-shrinkable tube is fitted in the trunk portion in advance. A rubber valve is bonded to the inside of the ball spherical shell through the flange portion, heated to the ball spherical shell to which the rubber valve is bonded and vulcanized into a ball shape, and the heat shrinkable tube is contracted by the heating. It is made to contact | adhere to the said trunk | drum.

  According to the first aspect of the present invention, the body section is formed in a columnar shape having different vertical and horizontal lengths, and penetrates the slit in a direction in which the length direction of the slit and the major axis direction of the body section are substantially orthogonal to each other. By forming, the force which presses from the slit width direction and sticks a slit works stronger than the force which presses from the slit length direction and tries to open a slit. In addition, the torsion of the body part greatly acts in the major axis direction. At this time, the slit formed in the direction orthogonal to the trunk part major axis direction is difficult to open. Therefore, the slit can be closely adhered to prevent air leakage.

  In particular, if the body portion is formed in an elliptical column shape having different vertical and horizontal lengths, for example, the same effect can be obtained with a rubber valve having a small volume as compared with the case where the body portion is formed in a rectangular column shape. The force for pressing in the direction of the central axis concentrates on the slit 13e. Therefore, in addition to the above effects, there is an effect that the total weight of the rubber valve can be reduced and further confidentiality can be obtained.

A tubular clamping member to the body portion of the elliptical shape in the present invention and exterior, with Rukoto is heat shrunk by heating, the body portion and a force to tighten toward the outside in the center axis direction, a barrel Since it can be tightened strongly from the long diameter direction and the adhesion of the slit is further increased, a soft tennis ball with higher confidentiality can be provided.

  In particular, even if a large impact force is applied when the ball is hit, the body portion is molded by the tightening portion, so that it does not extremely deform in the lateral direction. Even if the body portion swells in the side surface direction, the force for tightening the body portion is further increased, so that the slits can be brought into close contact with each other with stronger elasticity to prevent air leakage.

Furthermore, the Tightening member for forming a thermal shrinkable tube, and the ball spherical shell, while adhering the rubber valve that is fitted into the heat-shrinkable tube body portion, heat is applied to the ball-like In the vulcanization molding step, the heat-shrinkable tube shrinks due to the heat during vulcanization molding due to its properties. Therefore, the fastening member can be easily attached to the rubber valve simply by fitting the fastening member before shrinkage having a diameter larger than that of the rubber valve to the rubber valve before the ball molding process. Is tightened by contraction of the heat-shrinkable tube, so that the valve can be easily tightened.

According to the invention of claim 2 , the body portion is formed into a substantially elliptical column shape having an outer diameter gradually increasing from the ball spherical shell side toward the inside of the ball, thereby fastening the body portion on the body portion. It is possible to prevent the member from falling into the ball spherical shell.

  In particular, if a flange portion for receiving a fastening member is formed on the inner end face of the body portion, the fastening member can be further prevented from falling off.

  FIG. 1 and FIG. 2 are a perspective view and a cross-sectional view of a main part of a soft tennis ball showing a first embodiment of the present invention.

  1 and 2, in the soft tennis ball 1 according to the present embodiment, a rubber valve 13 is bonded and fixed with an adhesive so that an outer end portion faces a small hole 12 formed in a part of a ball spherical shell 11. . In FIG. 1 and FIG. 2, the rubber valve 13 is drawn large for easy understanding, and is actually small as shown in the dimensions described later.

  The rubber valve 13 has a protruding portion 13a that engages with the small hole 12 of the ball spherical shell 11 at the center of the outer end portion, and a thin bonding flange portion 13b is formed so as to continue to the base portion of the protruding portion 13a. It is made of a solid rubber member in which a columnar body portion 13c is formed on the inner end side from the bonding flange portion 13b, and is integrally formed into a single structure. An adhesive is applied to the outer surface side of the bonding flange portion 13b.

  The trunk portion 13c is formed in a columnar shape having different vertical and horizontal lengths in a cross section parallel to the inner end surface 13f of the trunk portion 13c. In the present embodiment, the trunk portion 13c is formed in an elliptical columnar shape.

  The rubber valve 13 is formed with an introduction hole 13d, which is a bottomed opening for introducing the insertion rod of the air pump in the center of the protrusion 13a, and a cutter (not shown) is fitted to the introduction hole 13d. The slit 13e is formed to penetrate to the inner end surface 13f of the body portion 13c. The slit 13e is formed inside the rubber valve 13 and is not formed up to the outer periphery.

  Since the slit 13e is formed so as to penetrate the length direction A of the slit 13e and the major axis direction B of the trunk part 13c, the pressure from the major axis direction B of the trunk part 13c is higher than the pressure from the minor axis direction. Join strongly. Therefore, since the force which presses the slit 13e from the width direction works more strongly than the force which opens the slit 13e, and the contact | adhesion power increases, air does not leak from the slit 13e.

  In addition, since the body portion 13c is formed in an elliptical columnar shape, the weight of the rubber valve 13 can be reduced, and the force for pressing the body portion 13c in the central axis direction can be concentrated on the slit 13e, thereby achieving further airtightness.

  Further, in the present embodiment, the body portion 13c is formed in an elliptical column shape having a hem that gradually increases in outer diameter from the outer end side toward the inner end side, and is attached to the outer periphery of the body portion 13c described later. It is possible to prevent the tightening member 14 to be dropped from falling into the ball shell 11. In the present embodiment, as shown in FIG. 2, a flange member receiving flange portion 13g is formed on the inner end surface 13f of the body portion to prevent the tightening member 14 from falling into the ball spherical shell 11.

  In addition, in this Embodiment, although the trunk | drum 13c is formed in the elliptical column shape, the shape of the trunk | drum 13c is not limited to this, For example, you may form in a square column shape.

  On the other hand, on the outer periphery of the rubber valve 13, a fastening member 14 for fastening in the central axis direction of the trunk portion 13c is externally provided.

In the present embodiment, the fastening member 14 is formed of a heat shrinkable tube (for example, a tube made of ethylene propylene or a thermoplastic elastomer ) having a property of shrinking when heated. When the fastening member 14 made of this heat-shrinkable tube is fitted over the length direction of the body portion 13c and heated, the fastening member 14 contracts due to its property and comes into close contact with the body portion 13c. Can be tightened from the outside to prevent air leakage from the slit 13e, and the confidentiality of the ball 1 can be further enhanced. In particular, in the present embodiment, a tube having a substantially circular cross section is used, so that it can be strongly tightened from the major axis direction B of the elliptical cylindrical body portion 13c, and the slit 13e can be further adhered.

Further, the body portion 13c with the tightening member 14 sheathed is molded by the tightening portion 14 even if it receives a large impact force at the time of hitting the ball. Even when it swells in the lateral direction, the force for tightening the body portion 13c is further increased, and the slit 13e is brought into close contact with a strong elastic force.

  By the way, the soft tennis ball 1 is usually formed into a spherical shape by vulcanization molding with a rubber bulb 13 adhered inside the ball bulb shell 11 and the ball bulb shell 11 and the rubber bulb 13 set together.

  Therefore, in the soft tennis ball 1 according to the present embodiment, the fastening member 14 made of a heat shrinkable tube having an inner diameter larger than the outer diameter of the body portion 13c is fitted in the body portion 13c of the rubber valve 13 in advance. The rubber valve 13 is bonded to the inner side of the ball spherical shell 11 via the bonding flange portion 13b and set integrally. Further, when the ball 1 with the rubber valve 13 set is heated at about 150 ° C. to 160 ° C. for about 10 minutes to 20 minutes and vulcanized and formed into a ball shape, the heat-shrinkable tube, due to its nature, And is tightly adhered to the body portion 13c to tighten the body portion 13c in the direction of the central axis. Therefore, the operation of expanding the fastening member 14 and fitting it into the rubber valve main body 13 is unnecessary, so that the fastening member 14 can be easily attached in the ball forming process.

  In addition, although the heat-shrinkable tube is used for the fastening member 14 of this Embodiment from the ease of attachment, the fastening member 14 is not restricted to this, Even if a tape is wound around the trunk | drum 13c. Alternatively, other fastening members may be externally mounted.

  The total weight of the rubber valve 13 in the present embodiment is 0.5 ± 0.1 g, and the upper limit value is 0.6 g. As a material, 2 parts by weight or less of an adhesive and 1 to 5 parts by weight of a softener are added to the compounding chemical resulting from vulcanization. And 2 parts by weight or less of pigment, and powder filling is not used. The polymer is NR, IR, BR alone or a blend.

  The rubber hardness of the valve body 13 is 20 ° to 30 °, in particular, the upper limit is 30 ° or less, and the rubber hardness of the rubber valve 23 of the tennis ball 2 shown in FIG. (Measurement is based on durometer type A manufactured by Shimadzu Corporation.) Accordingly, the tightening member 14 can be tightened so hard that it is difficult to fit into the body portion 13c, so the slit 13e is closely attached and air leaks from the slit 13e. Can be prevented.

  Further, even if the rubber valve 13 is formed in the same size as the conventional rubber valve 23, the total weight can be reduced, so that even if the fastening member 14 is fitted here, the rubber valve 13 is lighter than the conventional product. Can be formed. The thickness of the bonding flange portion 13b is 0.3 to 0.8 mm, which greatly contributes to weight reduction.

  Furthermore, the outer diameter of the trunk portion 13c is 9.0 mm for the major axis and 7.0 mm for the minor axis, the minor axis is 8.0 mm and the minor axis is 6.0 mm, and the slit 13e is 1.0 mm to 3 mm. It is formed with a length of 0.0 mm. By forming the body portion 13c and the slit 13e at the above ratio, the rubber valve 13 is formed so as to be light enough not to affect the entire ball 1. Further, by forming at the above ratio, the pressure from the width direction of the slit 13e can be maximized, and the adhesion force of the slit 13e is increased. In addition, although the said range can obtain the largest fastening force, the dimension of a diameter is not necessarily limited to this.

  When the air in the soft tennis ball 1 according to the present embodiment is reduced, air is injected by an air pump provided with a hollow insertion rod 15 having a rounded tip.

  In the present embodiment, the tip of the insertion rod 15 is inserted while inserting the insertion rod 15 having a tip of about 1.0 ± 0.1Φ into the introduction hole 13d of the rubber valve body 13 through the small hole 12 and further expanding the slit 13e. Is injected until it protrudes from the inner end face 13f of the valve. An appropriate amount of silicon oil 16 is preliminarily applied to the distal end portion of the insertion rod 15 as a lubricant and a sealant for reducing friction with the rubber valve 13.

  When the insertion rod is pulled out from the slit 13e after the air is injected, the tightening force of the rubber forming the body portion 13c, the tightening force of the tightening member 14, and the sealing action of the silicon oil 16 remaining in the slit 13e work. 13e closely adheres and air in the ball 1 does not leak outward from the slit 13e.

  Furthermore, the air in the ball 1 does not leak outward from the slit 13e due to the above-described action even after the air is injected, particularly at the time of hitting.

The principal part perspective view of the soft tennis ball which shows the Example of this invention. FIG. 2 is a cross-sectional view of a main part of the soft tennis ball shown in FIG. 1. Sectional drawing of the principal part of the conventional soft tennis ball.

Explanation of symbols

1 soft tennis ball 11 ball shell 12 small hole 13 rubber valve 13a protrusion
13b Bonding flange portion 13c Body portion 13d Introduction hole 13e Slit 13f Valve inner end surface 13g Tightening member receiving flange portion 14 Tightening member 15 Insertion rod
16 Silicon oil 2 Soft tennis ball 21 Ball spherical shell 22 Small hole 23 Rubber valve 23a Protruding part 23b Flange part 23c Body part 23d Introduction hole 23e Slit 23f Valve inner end face 24 Insertion rod 25 Silicon oil

Claims (3)

A ball spherical shell, solid and columnar air injection rubber valve that is formed of a rubber member, the clamping member consists of heat-shrinkable tubing which is to be attached to a periphery of the rubber valve that is bonded to a portion of the ball sphere shell And
The rubber valve includes a flange portion bonded to an inner peripheral surface of the ball spherical shell, a protrusion protruding outward from the flange portion and engaging with a small hole formed in the ball spherical shell, and the protrusion Formed in the rubber valve through the inner end surface of the body portion from the bottom surface of the opening portion, a columnar body portion extending from the flange portion to the inner side of the ball, Having a slit,
The body portion is formed in a columnar shape having different vertical and horizontal lengths in a cross section substantially parallel to the inner end surface, and the slit is formed in a direction in which the length direction of the slit and the major axis direction of the body portion are substantially orthogonal to each other. and,
A soft tennis ball , wherein the fastening member is attached to the outer periphery of the body part by being heated and contracted after the exterior of the body part is wound around the outer periphery of the body part in the length direction, thereby tightening the body part . 2. The soft tennis ball according to claim 1 , wherein the trunk portion is formed in a substantially elliptical column shape having an outer diameter gradually increasing from the ball spherical shell side toward the inside of the ball. A manufacturing method for manufacturing the soft tennis ball according to claim 1 or 2,
The rubber bulb in which the tightening member made of the heat shrinkable tube is fitted in advance to the body portion is bonded to the inside of the ball spherical shell through the flange portion, and the ball spherical shell to which the rubber valve is bonded A method for producing a soft tennis ball, wherein the heat shrinkable tube is shrunk by the heating and is brought into close contact with the trunk.

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