JP2009078075A - Indian club for rhythmic gymnastics and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage to a floor, to reduce injury to the human body and to improve manufacturing efficiency. <P>SOLUTION: An indian club has a neck part 2, a body part 1 and a head part 3. The neck part 2 is formed of a thermoplastic resin (a first material). The body part 1 is formed of a thermoplastic elastomer (a second material) so as to be integral with one end 2b of the neck part 2 by injection molding. The thermoplastic elastomer has a rubber elasticity at normal temperature and is melted by heating for allowing the injection molding. The head part 3 has a head base part 31 which is positioned on the side of the neck part 2 without contacting a virtual plane A that simultaneously circumscribes both the head part 3 and the body part 1, and a head tip part 32 which includes a point of contact 3b with the virtual plane A and which is positioned opposite to the neck part 2. The head tip part 32 is formed integrally with the head base part 31 by injection molding using the thermoplastic elastomer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rhythmic gymnastics club used in rhythmic gymnastics and a method for manufacturing the same.

  As this kind of rhythmic gymnastics club, a body part made of an elastic material is joined to one end part of a neck part formed of a wooden stick by an adhesive or a screw, and the other end part of the neck part is also made of an elastic material. An integrally configured head body, neck, and head by connecting the head with an adhesive is known (for example, Patent Document 1).

  In the rhythmic gymnastics club constructed in this way, the torso and head are made of an elastic material having cushioning properties, so after throwing it up, it may be accidentally dropped on the floor. However, there is an advantage that damage to the human body can be minimized even if the floor is not damaged and, for example, the body part hits the human body.

  As another conventional example, a core material made of a tough material such as glass fiber is formed, and a body portion, a neck portion and a head portion made of rubber material are integrally formed around the core material. (For example, Patent Document 2).

  The rhythmic gymnastics club configured in this manner has a structure that is entirely covered with a rubber having cushioning properties, and thus has the same effects as those described in Patent Document 1 described above.

Japanese Utility Model Publication 2-46931 Japanese Utility Model Publication No. 4-45734

  However, in the rhythmic gymnastics club described in the above-mentioned Patent Document 1, for example, a structure that is bonded using an adhesive requires an operation of applying an adhesive to the neck and the like, and obtains its bonding effect. Sufficient curing time is required. In addition, with a structure that uses screws, the neck and body parts must be machined with male and female screws, and the body part must be rotated for screw connection. In order to obtain a proper fastening force, it is necessary to manage the screw tightening torque. Therefore, there exists a problem that manufacturing efficiency is inferior.

  On the other hand, in the rhythmic gymnastics club described in Patent Document 2, a vulcanizing agent or the like is mixed with natural rubber or synthetic rubber in order to give predetermined rubber properties to the rubber material constituting the trunk, neck and head. Kneading work is required, and using the material kneaded in this way, after forming the body part, neck part and head part around the core material, the body part, neck part and head part are formed for the vulcanization. It is necessary to hold at a high temperature for a predetermined time. Accordingly, in this case as well, there is a problem that the production efficiency is inferior.

  The present invention has been made in view of the above circumstances, and can prevent damage to the floor, minimize damage to the human body, and improve production efficiency. It is an object to provide a club for rhythmic gymnastics and a manufacturing method thereof.

  In order to solve the above problems, the invention described in claim 1 includes a neck portion formed in a rod shape, and a body portion formed at one end portion of the neck portion and having an outer peripheral surface having a diameter larger than that of the outer peripheral surface of the one end portion. A rhythmic gymnastics club having a head formed at the other end of the neck and having an outer peripheral surface larger in diameter than the outer peripheral surface of the other end, wherein the neck has a predetermined strength. The body part is formed integrally with one end part of the neck part by the injection molding by a second material that has rubber elasticity at room temperature and melts by heating and can be injection-molded. When the head is assumed to be a virtual plane that circumscribes the head and the body part at the same time, the head base end located on the neck side without contacting the virtual plane and a contact point between the virtual plane A head tip located on the opposite side of the neck Be provided with a, the head tip is characterized in that it is integrally formed by injection molding on the head base end portion by the second material.

  Here, the normal temperature refers to a temperature under a normal environment where the rhythmic gymnastics club is used for performance or the rhythmic gymnastics club is stored. Injection molding is a mold that is closed by melting a material (thermoplastic resin or the like) that can be melted by heating in a predetermined cylinder and injecting the molten material from the cylinder at a high pressure. After being injected into the cavity (molding space) at a high pressure, it is cooled and solidified to form a product having a shape matching the cavity. This injection molding makes it possible to obtain a large amount of products with small variations in size and weight.

  In addition, as the second material, for example, there is a thermoplastic elastomer. This thermoplastic elastomer is not vulcanized or cross-linked and has rubber elasticity similar to that of vulcanized rubber in the range of use temperature or storage temperature of the club (that is, normal temperature). It is a polymer or a polymer blend that loses its properties when heated to the processing temperature for the purpose, can be easily injection-molded, and exhibits the original properties again when returned to room temperature. For example, there are thermoplastic elastomers such as styrene, olefin, PVC, urethane, ester, and amide. The thermoplastic elastomer may be a foamed thermoplastic elastomer containing a foaming agent, or may contain a reinforcing material such as glass fiber.

  Furthermore, the second material is a material that has rubber elasticity at room temperature and can be melted by heating and can be injection-molded. The physical properties such as hardness and specific gravity may be different. However, in consideration of simultaneous injection molding of the body part and the head tip part, it is preferable to use the second material having the same physical properties in these body part and head tip part. Further, the head base end portion is preferably formed integrally with the neck portion by the first material.

  According to a second aspect of the present invention, in the first aspect of the present invention, in the first aspect of the invention, the one end of the neck portion is located on the inner side of the body portion by injection molding the body portion. A head end coupling portion that is positioned inward of the head distal end portion by injection molding of the head distal end portion is provided at the head proximal end portion, The body coupling portion and the head end coupling portion are characterized in that a concave portion or a convex portion is formed on each outer peripheral surface.

  According to a third aspect of the present invention, in the second aspect of the present invention, the concave portion or the convex portion is formed continuously and / or partially in the circumferential direction.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the outer peripheral surface of the neck portion is subjected to a rough surface processing for roughening a surface except for a portion near the head portion. It is characterized by being.

  Here, the rough surface processing for roughening the surface refers to processing that causes a relatively rough unevenness on the outer peripheral surface so that the outer peripheral surface of the neck is in a state of rocks, grain, or plain. When the neck is made of, for example, metal, the outer peripheral surface of the neck is subjected to surface treatment such as chemical corrosion (etching) with chemicals or shot blasting (for example, sand blasting). It will be in the state where the unevenness which roughens the surface was formed. Further, when the neck portion is formed of, for example, a thermoplastic resin, the surface of the outer peripheral surface of the neck portion is made by performing the surface treatment by the above-described chemical corrosion or sandblasting on the cavity inner surface of the mold for molding the neck portion. It will be in the state where the unevenness to be roughened was formed. In order to sufficiently increase the frictional force between the outer peripheral surface of the neck and the palm, the rough surface processing is preferably performed so that the outer peripheral surface of the neck has a surface roughness of 10S to 50S. Further, the rough surface processing may be referred to as “texturing”.

  The invention according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the outer peripheral surfaces of the body part and the head tip part are subjected to a matte treatment. .

  Here, as the matting treatment, for example, the body after injection molding is performed by subjecting the inner surface of each cavity in the mold for injection molding of the body portion and the head tip portion to the surface treatment by the above-described chemical corrosion, sandblasting, or the like. There is a process by roughing which makes the outer peripheral surface of the head and the head tip part in a state of rock, grain, or plain.

  The invention according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the body part and the head tip part have a hardness of 60 to 80.

  Here, hardness refers to rubber hardness, and refers to the hardness of rubber measured by a type A durometer as defined in JIS K 6253 (ISO 7619).

  The invention according to claim 7 is a method for manufacturing the club for rhythmic gymnastics according to any one of claims 1 to 6, wherein cavities for injection-molding each of the body part and the head tip part are provided. Open the mold, and insert the neck and head base end integrally formed in a predetermined position in the mold, then close the mold and heat in each cavity Injecting the second material in a melted state by injection molding the body part at one end of the neck and injection-molding the head distal end at the head base end. It is said.

  The invention according to claim 8 is a method for manufacturing the rhythmic gymnastics club according to any one of claims 1 to 6, wherein the cavity for integrally injection-molding the neck portion and the head base end portion is provided. The neck and the head proximal end portion are injected by injecting an injection moldable material as the first material that has been melted by heating into the cavity after closing the first mold having Is integrally molded, and then a second mold having a cavity for injection molding each of the body portion and the head tip portion is opened, and the predetermined position in the second mold is After inserting the neck part and the head base end part injection-molded by the first mold, the second mold is closed and heated in each cavity of the second mold. Injecting the second material in a molten state A result, the injection molding said body portion at one end of the neck, is characterized by injection molding the head tip the head proximal end.

  Here, as the material that can be injection-molded as the first material, it is possible to use a thermoplastic resin (for example, PP), a thermoplastic resin containing a reinforcing material such as glass fiber, a foaming agent, or the like. . The second mold corresponds to the mold in the invention described in claim 7.

  According to the first aspect of the present invention, the body portion is formed of the second material having rubber elasticity at room temperature, and the head tip portion including the contact point with the virtual plane in the head is also formed of the second material. Therefore, even if the torso has fallen on the flat floor first, the head has dropped on the floor first, and the torso and head have fallen on the floor at the same time. The part having rubber elasticity will hit the floor. Therefore, even if the floor is accidentally dropped, the floor is not damaged. In addition, since the impact force when hitting the floor or the like can be absorbed by elastic deformation of the trunk part or the head tip part, it is possible to prevent the trunk part, head part or neck part from being damaged. Furthermore, even when the body part or the head tip part hits a human body, damage to the human body can be minimized.

  In addition, since the second material that can be melted by heating and injection-molded is injection-molded at one end of the neck, the body is integrally formed at the one end. Can be firmly coupled to one end of the neck. That is, even if the surface of the object is finished finely, fine irregularities are continuously present alternately. When the body part is injection-molded at one end of the neck part, the molten second material Will cool and harden after it is in a state that matches the fine irregularities present at one end of the neck. For this reason, a trunk | drum part and the one end part of a neck part are couple | bonded firmly. Similarly, the head distal end portion and the head proximal end portion are firmly coupled.

  In this way, the torso and neck, and the head tip and head base end can be firmly bonded without using any adhesive or screws, so when using adhesive or screws, etc. The troublesome work etc. which arise are unnecessary. In addition, there is no need for kneading work and time for vulcanization as in the case of molding the body and head using a rubber material. Therefore, the manufacturing efficiency can be improved.

  Furthermore, by mixing a colorant into the second material, it is possible to injection mold the body portion and the head tip portion of various colors corresponding to the colorant. In this case, since only the surface of the body part and the head tip part is not colored as in the case of painting, even if the body part or the head tip part is elastically deformed due to a drop or the like, the coating is partially applied. Therefore, the color and appearance of a new article can be maintained for a long time without being peeled off or cracking the coating.

  According to the second aspect of the present invention, the body coupling portion that is positioned inward of the body portion is provided at one end portion of the neck portion, and the head base end portion is positioned inward of the head distal end portion. Since the head end coupling portion is provided and the concave portion or the convex portion is formed on the outer peripheral surfaces of the trunk coupling portion and the head end coupling portion, the trunk portion and the head tip portion are in close contact with the concave portion or the convex portion. Therefore, the body portion and the neck portion, and the head distal end portion and the head proximal end portion can be more firmly coupled.

  According to invention of Claim 3, since the recessed part or convex part formed in the outer peripheral surface of a trunk | drum coupling | bond part and a head end coupling | bond part is continuously and / or partially formed in the circumferential direction, When the convex portion is continuously formed in the circumferential direction, against the force that pulls the body portion axially away from the neck and the force that pulls the head distal end axially away from the head proximal end A great resistance will be generated. Further, when the concave portion or the convex portion is partially formed in the circumferential direction, the force for rotating the body portion about the axis relative to the neck portion, and the head tip portion about the axis relative to the head base end portion A large resistance force is generated against the rotating force. Further, when the concave portion or the convex portion is formed continuously and partially in the circumferential direction, the force for pulling the body portion away from the neck portion in the axial direction and the force for rotating around the axis, A large resistance force is generated with respect to the force that pulls away from the head base end portion in the axial direction and the force that rotates around the axis. Therefore, the body portion and the neck portion, and the head distal end portion and the head proximal end portion can be firmly coupled.

  According to the invention described in claim 4, since the rough surface processing for roughening the surface is performed on the portion other than the vicinity of the head portion on the outer peripheral surface of the neck portion, The friction coefficient can be increased. Therefore, it is possible to perform the performance while securely grasping the neck portion, and it is possible to reliably catch the neck portion when receiving it after throwing it up. In addition, the vicinity of the head portion in the neck portion is not in the surface roughening range, and the head base end portion in the head portion is not in the surface roughening range, and because of having rubber elasticity, the friction coefficient is reduced. Since the distal end portion of the head is formed of the second material that tends to be larger, for example, by grasping the vicinity of the head portion of the neck portion while using the proximal end portion of the head as a retaining member in the axial direction, It is possible to smoothly perform an action such as sliding the neck and head with respect to the finger or the like of the gripping hand, for example, an action such as swinging or rotating the body side. Further, the rough surface processing makes the outer peripheral surface of the neck frosted and the light hitting the neck is reflected as dispersed light, so that the strong light reflected by the neck enters the eyes of the performer. There is no such thing. Therefore, stable performance is possible.

  According to the invention of claim 5, since the matte processing is made on each outer peripheral surface of the trunk part and the head tip part, the light hitting the trunk part and the head tip part will be dispersed and reflected, The strong light reflected by the torso and head tip does not enter the eyes of the performer. Therefore, stable performance is possible.

  According to invention of Claim 6, since the hardness of a trunk | drum part and a head front-end | tip part is 60-80, even if it may fall to the floor after throwing up high, a trunk | drum part and The head tip can be sufficiently elastically deformed to absorb energy when colliding with the floor. Therefore, it is possible to prevent the floor from being damaged, and it is possible to prevent the trunk, the head, or the neck from being damaged. Further, even when the body part or the head tip part hits a human body, damage to the human body can be minimized.

  According to the seventh aspect of the present invention, a mold having a cavity for injection molding each of the body part and the head tip part is opened, and the neck part and the head base end part are located at predetermined positions in the mold. After inserting the integrally formed one, the mold is closed, and the body is injected into one end of the neck by injecting a second material that has been melted by heating into each cavity. In addition to molding, the head tip is injection-molded at the head base end, so that a predetermined dimension defined by the mold cavity at a predetermined position defined by the mold at one end of the neck And the body part of the weight can be accurately formed, and the head tip part of the predetermined size and weight defined by the cavity of the mold is accurately positioned at the predetermined position defined by the mold at the head base end part. Molded into Door can be. Therefore, it is possible to obtain a stable rhythmic gymnastics club with extremely small variations in size, weight, and position with respect to the body and tip of the head.

  According to the eighth aspect of the present invention, the first mold having a cavity for integrally injection-molding the neck portion and the head base end portion is closed, and then heated in the cavity of the first mold. By injecting an injection moldable material as the first material in a molten state, the neck portion and the head proximal end portion are integrally injection-molded. As for the integrally formed portion, it is possible to obtain an accurate size and weight defined by the cavity of the first mold.

  Then, a second mold having a cavity for injection molding each of the body part and the head tip part is opened, and a neck part injection-molded by the first mold at a predetermined position in the second mold. And after inserting the head base end portion, the second mold is closed, and the second material that has been melted by heating is injected into each cavity of the second mold. The body portion is injection-molded at one end of the neck portion, and the head distal end portion is injection-molded at the head base end portion, so that the predetermined position defined by the second mold at the one end portion of the neck portion The body portion having a predetermined size and weight defined by the cavity of the second mold can be accurately formed, and at a predetermined position defined by the second mold at the head proximal end portion. Specified by the cavity of the second mold Predetermined size and weight of the head tip can be precisely shaped that. Therefore, it is possible to obtain a rhythmic gymnastics club having a stable quality with extremely small variations in size and weight for all of the trunk, neck and head.

  Hereinafter, an embodiment as the best mode for carrying out the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the rhythmic gymnastics club shown in this embodiment is integrally formed of a body part 1, a neck part 2, and a head part 3 in a coaxial manner. The rhythmic gymnastics club has a circular cross section, the body 1 has an outer peripheral surface larger in diameter than the one end 2b of the neck 2, and the head 3 from the other end 2d of the neck 2. It has a large-diameter outer peripheral surface. Hereinafter, each structure of the rhythmic gymnastics club will be described in detail.

  The neck 2 is integrally formed by injection molding using a thermoplastic resin (first material) having a predetermined strength capable of injection molding. The neck portion 2 extends in a straight bar shape, and the outer peripheral surface 2a is gradually enlarged from the base end side (head 3 side) toward the one end side (body portion 1 side). An end face 2c having a shape cut out in a plane perpendicular to the center line C passing through the axial centers of the body part 1, the neck part 2 and the head part 3 is formed at one end part 2b of the neck part 2, and this end face is formed. A body coupling portion 21 is formed so as to protrude in the axial direction from the axial center portion of 2c.

  As shown in FIG. 2, the body coupling portion 21 enters the inside of the body portion 1, thereby firmly coupling the body portion 1 to the one end portion 2 b of the neck portion 2. The body coupling portion 21 has a circular cross section and is formed such that its outer peripheral surface 21a gradually increases in diameter toward the tip. In this case, the outer peripheral surface 21 a of the body coupling portion 21 has a shape that is gradually expanded in diameter so as to follow the outer peripheral surface 1 a of the body portion 1 that is injection-molded on the one end portion 2 b of the neck portion 2. In addition, the outer peripheral surface 21a of the body coupling portion 21 is formed with a first annular recess 21b having a shape continuously depressed in the circumferential direction at a position adjacent to the end surface 2c, and in the circumferential direction at a position near the tip. A second annular recess 21c that is continuously depressed is formed. And the part between the 1st annular recess 21b and the 2nd annular recess 21c, or the part by the side of the tip of the 2nd annular recess 21c becomes the annular convex part 21d of the shape which rises continuously in the peripheral direction. . In addition, each bottom portion of the first annular recess 21b and the second annular recess 21c has a shape rounded in an arc shape, and each corner K of each annular projection 21d is also rounded in an arc shape. It has become.

  Further, the outer peripheral surface 21a of the body coupling portion 21 is recessed deeper than the second annular recess 21c at a position corresponding to the second annular recess 21c and at a position 180 degrees apart in the circumferential direction. A hole-shaped concave portion (a concave portion partially formed in the circumferential direction) 21e is formed. Each hole-shaped recess 21e has a circular cross section and a bottom rounded into a hemisphere.

  And the trunk | drum coupling | bond part 21 rounds the bottom part of the 1st annular recessed part 21b or the 2nd annular recessed part 21c in circular arc shape, and rounds the bottom part of the hole-shaped recessed part 21e in a hemispherical shape, The said 1st annular recessed part 21b, the shape of the second annular recess 21c and the bottom of the hole-shaped recess 21e are effective in reducing stress concentration. Further, the body coupling portion 21 is formed on each corner K of the body portion 1 which is injection-molded so as to be in close contact with the body coupling portion 21 by rounding each corner K of each annular convex portion 21d into an arc shape. The shape is designed to alleviate the stress concentration occurring in the corresponding part. Further, the front end surface 21 f of the body coupling portion 21 is formed in a planar shape in a direction orthogonal to the center line C. In addition, the thermoplastic resin which comprises the neck part 2 contains reinforcing materials, such as glass fiber, and the improvement of the intensity | strength is aimed at.

  Further, as shown in FIG. 1, the outer peripheral surface 2a of the neck 2 is subjected to a rough surface processing for roughening the surface of the portion excluding the vicinity of the head 3 (the portion indicated by the halftone dots in FIG. 1B). Has been. This rough surface processing forms relatively rough irregularities by applying chemical corrosion (etching) with chemicals or surface treatment with sand blasting, etc. to a predetermined range on the inner surface of the cavity of the first mold for injection molding the neck 2. In addition, the thermoplastic resin is injected into the cavity at a high pressure so that the relatively rough unevenness is transferred to a predetermined range on the outer peripheral surface 2a of the neck portion 2.

  The surface roughened portion (hereinafter referred to as “rough surface processed portion 2e”) has a surface roughness of 10S to 50S, and the rough surface processed portion 2e and the rough surface processed portion 2e. It is designed to improve the frictional force between the palm and the palm. Here, the reason why the surface roughness is 10S or more is that if the surface roughness is less than 10S, the height difference (maximum height) of the unevenness is as small as less than 10 μm, and the frictional force with the palm cannot be sufficiently increased. The reason is that if it exceeds 50S, the unevenness of the unevenness becomes more than 50 μm, and the rough feeling when gripping the rough surface processed portion 2e becomes strong, which is not preferable. In addition, the surface roughness has shown the example displayed with the maximum height (Rmax) based on a JIS specification. The surface roughness due to the maximum height (Rmax) is calculated by extracting the reference length in the direction of the average line of the roughness curve, and when the extracted part is sandwiched by two straight lines parallel to the average line of the extracted part. A value obtained by measuring the interval between straight lines in the direction of the vertical magnification of the roughness curve is expressed in units of micrometers (μm).

  On the other hand, the outer peripheral surface 2a in the vicinity of the head 3 in the neck 2 is in a state where a portion corresponding to the outer peripheral surface 2a in the vicinity of the head 3 in the inner surface of the cavity is finished in a mirror surface. The finished surface is a smooth surface.

  The body portion 1 is a material that is softer than the neck portion 2 and has rubber elasticity at room temperature (the temperature at which the rhythmic gymnastics club is used or stored), and is a thermoplastic elastomer that can be injection-molded by being melted by heating. 2), it is integrally formed at one end 2b of the neck 2 by injection molding. The body portion 1 is in an intimate contact state with the end surface 2c of the one end portion 2b of the neck portion 2, the outer peripheral surface 21a and the front end surface 21f of the body coupling portion 21, and the first portion of the body coupling portion 21 is formed by injection molding. The annular recess 21b, the second annular recess 21c, and the hole-like recesses 21e are in close contact with these surfaces.

  Further, the outer peripheral surface 1a of the body portion 1 is gradually expanded in diameter so as to be continuous with the outer peripheral surface 2a of the one end portion 2b of the neck portion 2, and has a maximum diameter at a substantially central position in the axial direction. It is formed so as to gradually reduce the diameter toward the end, and has a barrel-shaped outer peripheral surface shape as a whole. The front end surface 1b of the body portion 1 is formed in a planar shape in a direction orthogonal to the center line C.

  Further, the body portion 1 is formed with a cavity 1c having a circular cross section extending from the center portion of the front end surface 1b along the center line C to the vicinity of the front end surface 21f of the body coupling portion 21. The cavity 1c is formed by injection molding in a state where the core of the cavity 1c is inserted into a cavity as a molding space of the body part 1 in the second mold for injection molding the body part 1. It is possible to form. For this reason, the cavity 1c is formed in a taper shape gradually reduced in diameter from the front end surface 1b, and after the thermoplastic elastomer is solidified in the cavity, the body portion formed by the thermoplastic elastomer. It is easy to pull out the core from the inside.

  Further, the body portion 1 is formed with an annular recess 1d having a shape continuously depressed in the circumferential direction at a position of the maximum diameter on the outer peripheral surface 1a. The bottom of the annular recess 1d is also formed in an arc shape, so that the concentration of stress generated at the bottom of the annular recess 1d in the body 1 is reduced.

  Further, the outer peripheral surface 1a, the front end surface 1b, and the surface of the annular recess 1d of the body portion 1 are subjected to a matting process by roughening. In this case, the rough surface processing is performed by forming relatively rough irregularities on a predetermined portion of the inner surface of the cavity of the second mold to be molded by injection molding by chemical corrosion, sandblasting, or the like. By injecting the thermoplastic elastomer into the inside at high pressure, the irregularities are transferred to the outer peripheral surface 1a, the front end surface 1b and the surface of the annular recess 1d of the body portion 1.

  Moreover, the trunk | drum 1 has the rubber hardness of 60-80 at normal temperature. This hardness is the hardness of rubber by a type A durometer specified in JIS K 6253 (ISO 7619). Here, the rubber hardness is set to 60 or more. When the rubber hardness is less than 60, there is a possibility that the bonding force with the one end 2b of the neck 2 including the body coupling portion 21 may be reduced due to the decrease in rigidity accompanying the hardness reduction. This is because, when it exceeds 80, the cushioning property due to rubber elasticity is lowered, and particularly the damage given to the human body when hitting the human body is increased. In order to increase the binding force with the one end 2b of the neck 2 and reduce the damage to the human body, it is more preferable that the hardness of the body 1 is about 70.

  As shown in FIGS. 1 and 3, the head 3 is positioned on the neck 2 side without contacting the virtual plane A when assuming the virtual plane A that circumscribes the head 3 and the body 1 at the same time. The head base end portion 31 and the head tip end portion 32 including the portion in contact with the virtual plane A and positioned on the opposite side of the neck portion 2 are integrally formed in a spherical shape. In this case, the contact 3b with the virtual plane A on the outer peripheral surface 3a of the head 3 exists on the head tip 32 side.

  The head base end portion 31 is integrally injection-molded simultaneously with the neck portion 2 by the same thermoplastic resin as the neck portion 2. The head base end portion 31 gradually bulges out in a spherical shape from the other end 2d of the neck portion 2 toward the distal end side of the head portion 3, and the end surface 31a on the distal end side is in a planar shape in a direction perpendicular to the center line C. Is formed. The end face 31a is positioned on the neck 2 side by a predetermined dimension with respect to the plane B in the direction orthogonal to the center line C through the contact 3b. A head end coupling portion 31b is integrally formed on the end surface 31a so as to protrude in the axial direction from the axial center portion.

  The head end coupling portion 31 b enters the inside of the head distal end portion 32, thereby firmly coupling the head distal end portion 32 to the head proximal end portion 31. The outer peripheral surface 31 c of the head end coupling portion 31 b is formed in a spherical shape along the outer peripheral surface 3 a of the head distal end portion 32 that is injection-molded on the distal end side of the head proximal end portion 31. In addition, an annular recess 31d having a shape continuously depressed in the circumferential direction is formed at a position adjacent to the end surface 31a on the outer peripheral surface 31c of the head end coupling portion 31b. The annular concave portion 31d forms an annular convex portion 31e having a shape in which the tip-side portion of the annular concave portion 31d is continuously raised in the circumferential direction. The bottom of the annular recess 31d has a shape rounded in an arc shape, and the corner K of the annular projection 31e has also a shape rounded in an arc shape.

  In addition, the outer peripheral surface 31c of the head end coupling portion 31b has a hole shape that is recessed with respect to the outer peripheral surface 31c at positions corresponding to the annular convex portion 31e and spaced 180 degrees in the circumferential direction. A concave portion (a concave portion partially formed in the circumferential direction) 31f is formed. Each hole-shaped recess 31f is formed in a circular shape in cross section, and has a bottom rounded into a hemisphere.

  The head end coupling portion 31b rounds the bottom of the annular recess 31d into an arc shape and also rounds the bottom of the hole-like recess 31f into a hemispherical shape, thereby concentrating stress generated at the bottom of the annular recess 31d and the hole-like recess 31f. It is an effective shape for mitigating this. Further, the head end coupling portion 31b is injection-molded so as to be in close contact with the head end coupling portion 31b outside the head end coupling portion 31b by rounding the corner portion K of the annular convex portion 31e into an arc shape. The head tip 32 also has a shape that relieves stress concentration that occurs in the portion corresponding to the corner K.

  Further, the outer peripheral surface 3a at the head base end portion 31 is transferred with a mirror-like finish surface on the inner surface of the cavity of the first mold, similarly to the outer peripheral surface 2a in the vicinity of the head 3 in the neck portion 2 described above. It has a smooth surface.

  The head distal end portion 32 is integrally formed on the distal end side of the head base end portion 31 by injection molding, using the same thermoplastic elastomer as the thermoplastic elastomer for injection molding the body portion 1. Therefore, the head tip portion 32 has the same hardness as that of the body portion 1. The head distal end portion 32 is brought into close contact with the end surface 31a of the head proximal end portion 31 and the outer peripheral surface 31c of the head end coupling portion 31b by injection molding, and the annular recess 31d in the head end coupling portion 31b and Each hole-like recess 31f enters and comes into close contact with these surfaces. Further, the outer peripheral surface 3 a of the head distal end portion 32 is subjected to a matting process by rough surface processing, like the outer peripheral surface 1 a of the body portion 1.

  Next, the manufacturing method of the rhythmic gymnastics club comprised as mentioned above is demonstrated. In this manufacturing method, a first mold (not shown) for integrally injection-molding the neck 2 and the head tip 32, and the neck 2 and the head injection-molded with the first mold. The body portion 1 is injection-molded at one end 2b of the neck portion 2 after being inserted into a predetermined position and integrally formed of the tip portion 32 (hereinafter referred to as “first molded body”). Use a second mold (not shown) for injection-molding the head tip 32 at the end 31 and an injection molding machine (not shown) for injection molding using these molds. become.

  First, a first mold is set in a predetermined injection molding machine, and a first molded body is molded using the first mold. In this molding, after the first mold is closed, the molten thermoplastic resin is injected into the first mold at a high pressure from the injection cylinder in the injection molding machine, and the thermoplastic resin is injected into the first mold. It inject | pours in the cavity for shape | molding the 1st molded object in a type | mold. Then, after the thermoplastic resin is cooled and solidified in the cavity, the first molded body molded according to the shape of the cavity is taken out by opening the first mold. By repeating such steps, a large amount of the first molded body can be obtained.

  On the other hand, the second mold is set in a predetermined injection molding machine, and the body part 1 and the head are formed with respect to the first molded body after molding with the first mold using the second mold. 3 is further formed. In this molding, first, after opening the second mold, the first molded body is inserted into a predetermined position in the second mold, and then the second mold is closed. Then, the molten thermoplastic elastomer is injected from the injection cylinder into the second mold at a high pressure, and the body part 1 and the head tip part 32 in the second mold are injection-molded with the thermoplastic elastomer. Inject into each cavity for. After that, after the thermoplastic elastomer is cooled and solidified in each cavity, the second mold is opened to form the mold according to the shape of each cavity, and the first molding is formed at a predetermined position of the first molded body. The rhythmic gymnastics club having the body part 1 and the head tip part 32 formed integrally with the body is taken out from the second mold. By repeating such steps, a large number of rhythmic gymnastics clubs can be produced.

  According to the rhythmic gymnastics club configured as described above, the body part 1 and the head tip part 32 are made of a thermoplastic elastomer that is softer than the neck part 2 and has rubber elasticity. Even if the head 3 falls to the floor first, or the body part 1 and the head 3 fall on the floor at the same time, the thermoplastic elastomer having rubber elasticity is always used. The part will hit the floor. Therefore, even if the floor accidentally falls, the floor is not damaged. In addition, since the portion of the thermoplastic elastomer can be elastically deformed and absorbed when it hits the floor or the like, it is possible to prevent the body portion 1, the head portion 3 or the neck portion 2 from being damaged. Furthermore, even if the body part 1 or the head tip part 32 hits the human body, damage to the human body can be minimized. And since the rubber hardness of the trunk | drum 1 and the head front-end | tip part 32 is set to 60-80, the effect mentioned above can be exhibited reliably.

  Further, the body portion 1 and the head distal end portion 32 are integrally formed on one end portion of the neck portion 2 and the distal end side of the head proximal end portion 31 by injection molding using a thermoplastic elastomer material. Therefore, the body portion 1 and the head distal end portion 32 can be firmly coupled to the neck portion 2 and the head proximal end portion 31, respectively. That is, even if the surface of the object is finished finely, fine irregularities exist alternately and continuously, and the molten thermoplastic elastomer cools after becoming a shape that matches the fine irregularities. Since it hardens, the trunk | drum 1 and the head front-end | tip part 32 can be firmly couple | bonded with the neck 2 and the head base end part 31. FIG.

  In this way, the body part 1 and the neck part 2 and the head tip part 32 and the head base end part 31 can be firmly bonded without using any adhesive or screws, so that the adhesive or screws are used. The troublesome work etc. which arise in the case of having become unnecessary are unnecessary. In addition, the kneading work and the time for vulcanization, which are necessary when molding the body and head with a rubber material, are not required. Therefore, the manufacturing efficiency can be improved.

  Furthermore, the body part 1 and the head tip part 32 of various colors corresponding to the colorant can be formed by injection molding using a thermoplastic elastomer mixed with the colorant. In this case, since only the surface of the body part 1 and the head tip part 32 is not colored as in the case of painting, even when the body part 1 and the head tip part 32 are elastically deformed due to dropping or the like. The paint is not partially peeled off or cracked in the paint, and the color and appearance of the new article can be maintained for a long time.

  The neck portion 2 and the head base end portion 31 can also be obtained in various colors corresponding to the colorant by injection molding with a thermoplastic resin mixed with the colorant. Also in this case, the material itself of the neck portion 2 and the head base end portion 31 is in a colored state, so that a problem such as peeling off a part of the coating does not occur.

  Also, a body coupling portion 21 is formed at one end 2b of the neck portion 2, and a first annular recess 21b, a second annular recess 21c, each annular projection 21d, and each hole shape are formed on the outer peripheral surface 21a of the body coupling portion 21. Since the concave portion 21e is formed, the body portion 1 can be brought into close contact with the above-described fine irregularities that are inevitably present, in addition to the first annular concave portion 21b, the second annular concave portion 21c, and each annular portion The protrusions 21d and the hole-like recesses 21e can be brought into close contact with each other. Therefore, the body part 1 can be very strongly coupled to the neck part 2.

  In this case, the first annular recess 21b, the second annular recess 21c, and each annular projection 21d are large against the force that separates the body portion 1 from the neck portion 2 in the axial direction (the direction along the center line C). A resistance force can be generated, and each hole-shaped recess 21e can generate a large resistance force to a force that rotates the body portion 1 around the axis (around the center line C) with respect to the neck portion 2.

  As for the head distal end portion 32, a head end coupling portion 31b is formed at the head proximal end portion 31, and an annular recess 31d, an annular projection 31e, and each hole-like recess 31f are formed on the outer peripheral surface 31c of the head end coupling portion 31b. As a result, the head base end portion 31 can be very firmly coupled.

  Moreover, since the rough surface process which roughens the surface is given to the part except the vicinity part of the head 3 in the outer peripheral surface 2a of the neck part 2, the friction coefficient with a palm is increased in the processed part. Can be planned. Therefore, it is possible to perform the performance while securely grasping the neck portion 2, and it is possible to reliably catch the neck portion 2 when receiving it after throwing it up. In addition, the vicinity of the head 3 in the neck portion 2 is out of the rough surface processing range and is formed on a smooth surface, and the head base end portion 31 in the head 3 is also out of the rough surface processing range and is smooth. Since a portion made of a thermoplastic elastomer (second material) having rubber elasticity and a large friction coefficient is disposed on the head tip 32, for example, the vicinity of the head 3 in the neck 2 The performance of sliding the neck 2 and the head 3 with respect to the fingers or the like of the gripping hand by gripping the portion while using the head proximal end portion 31 as a retaining member in the axial direction, for example, the body portion It is possible to perform smoothly such as swinging or rotating one side. Further, since the surface of the neck is matted by roughening, the light hitting the neck 2 is dispersed and reflected, and the strong light reflected by the neck 2 is the eyes of the performer. There is no such thing as entering. Therefore, there is an advantage that stable performance can be performed even under illumination in various performance venues.

  Further, since the outer peripheral surfaces 1a and 3a of the body part 1 and the head tip part 32 are matted, the light hitting the body part 1 and the head tip part 32 is dispersed and reflected, so that the body part 1 The strong light reflected by the head tip 32 does not enter the eyes of the performer. Therefore, a more stable performance can be performed.

  And since the cavity 1c extended in the axial direction (direction along the centerline C) from the front end surface 1b is provided in the axial center part of the trunk | drum 1, about the part corresponding to the cavity 1c in the said trunk | drum 1, especially The rigidity in the direction orthogonal to the axial direction can be reduced. For this reason, since the elastic deformation of the body part 1 becomes easy with respect to the force in the direction orthogonal to the axial direction, the outer peripheral surface 1a of the body part 1 corresponding to the cavity 1c may hit the human body. However, the damage to the human body can be mitigated more effectively.

  Furthermore, since the annular recess 1d is formed on the outer peripheral surface 1a of the body portion 1, the rigidity in the bending direction with the center line C as the neutral axis can be reduced. For this reason, the impact when the outer peripheral surface 1a of the trunk | drum 1 of the front end side from the cyclic | annular recessed part 1d hits a human body can be relieve | moderated further.

  In particular, the body portion 1 is formed with a rubber hardness of 60 to 80, a cavity 1c is formed in the axial center portion of the body portion 1, and an annular recess 1d is formed in the outer peripheral surface 1a of the body portion 1. Due to this synergistic effect, there is a remarkable effect that an extremely large impact force can be absorbed while the body 1 is firmly coupled to the one end 2b of the neck 2. Note that the weight of the body portion 1 can be adjusted by changing the size of the cavity 1c.

  On the other hand, according to the method for manufacturing a rhythmic gymnastics club, the first molded body composed of the neck portion 2 and the head base end portion 31 is obtained with an accurate size and weight defined by the cavity of the first mold. Can do.

  In addition, the body portion 1 having a predetermined size and weight defined by the cavity of the second mold is accurately formed at a predetermined position defined by the second mold in the one end portion 2b of the neck portion 2. The head distal end 32 having a predetermined size and weight defined by the cavity of the second mold is accurately formed at a predetermined position defined by the second mold at the head proximal end portion 31. can do.

  Therefore, it is possible to obtain a rhythmic gymnastics club having a stable quality with extremely small variations in size and weight for all of the body part 1, the neck part 2 and the head part 3.

  In the above embodiment, the example in which the neck portion 2 and the head base end portion 31 are integrally injection-molded with a thermoplastic resin has been shown. , Metal, or other materials.

  The material constituting the body part 1 and the head tip part 32 is limited to the above-described thermoplastic elastomer as long as it is a material having rubber elasticity at room temperature and can be melted by injection and injection-molded. It goes without saying that it is not done.

  Furthermore, although the trunk | drum 1 and the head tip part 32 showed the example which is injection-molded with the same thermoplastic elastomer, these trunk | drum 1 and the head tip part 32 are thermoplastic elastomers and other materials from which a physical property differs. You may make it injection-mold. However, if the body part 1 and the head tip part 32 are made of the same material, the body part 1 and the head tip part 32 are obtained by one injection molding using one type of second mold. be able to.

  Moreover, although the hole-shaped recessed parts 21e and 31f were shown as an example of the recessed part partially formed in the circumferential direction, it is only a part in the circumferential direction on the outer peripheral surface 21a of the trunk | drum coupling | bond part 21 and the outer peripheral surface 31c of the head end coupling | bond part 31b. Protrusions as an example of the convex portions that are formed may be provided at positions 180 degrees apart in the circumferential direction. The protrusion preferably has a shape that protrudes in a cylindrical shape from the outer peripheral surface 21a or the outer peripheral surface 31c and the tip is rounded into a hemisphere.

It is a figure of the club for rhythmic gymnastics shown as one embodiment of this invention, (a) is a front view, (b) is principal part sectional drawing. It is principal part sectional drawing which expands and shows the part by the side of the trunk | drum in the rhythmic gymnastics club. It is principal part sectional drawing which expands and shows the part by the side of the head in the same rhythmic gymnastics club.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body part 1a, 2a, 3a, 21a, 31c Outer peripheral surface 2 Neck part 2b One end part 2d Other end part 2e Rough surface processing part 3 Head 3b Contact (contact part with a virtual plane)
21 body coupling | bond part 21b 1st cyclic | annular recessed part (recessed continuously formed in the circumferential direction) (recessed part)
21c 2nd annular recessed part (recessed continuously formed in the circumferential direction) (recessed part)
21d annular convex part (convex part continuously formed in the circumferential direction) (convex part)
21e Hole-shaped recessed part (recessed partly formed in the circumferential direction) (recessed part)
31 head base end portion 31b head end coupling portion 31d annular recess (recess formed continuously in the circumferential direction) (recess)
31e annular convex part (convex part formed continuously in the circumferential direction) (convex part)
31f Hole-shaped recessed part (recessed partly formed in the circumferential direction) (recessed part)
32 Head tip A Virtual plane

Claims (8)

A neck portion formed in a rod shape, a body portion formed at one end portion of the neck portion and having an outer peripheral surface larger in diameter than the outer peripheral surface of the one end portion, and an outer peripheral surface formed at the other end portion of the neck portion A rhythmic gymnastics club with a head having a larger outer peripheral surface,
The neck is formed of a first material having a predetermined strength,
The body portion has rubber elasticity at normal temperature, and is formed integrally with the one end portion of the neck portion by the injection molding by a second material that can be melted by heating and injection-molded.
When the head is assumed to be a virtual plane that circumscribes the head and the body part at the same time, the head base end located on the neck side without contacting the virtual plane and a contact point between the virtual plane And a head tip portion located on the opposite side of the neck portion, and the head tip portion is integrally formed by injection molding on the base end portion of the head with the second material. Rhythmic gymnastics club. One end portion of the neck portion is provided with a body coupling portion that is positioned inward of the body portion by injection molding the body portion,
The head proximal end portion is provided with a head end coupling portion that is positioned inward of the head distal end portion by injection molding of the head distal end portion,
2. The rhythmic gymnastics club according to claim 1, wherein a concave portion or a convex portion is formed on an outer peripheral surface of each of the body coupling portion and the head end coupling portion.   The rhythmic gymnastics club according to claim 2, wherein the concave portion or the convex portion is formed continuously and / or partially in the circumferential direction.   The rhythmic gymnastics club according to any one of claims 1 to 3, wherein the outer peripheral surface of the neck portion is subjected to a roughening process to roughen the surface in a portion other than the vicinity of the head portion. .   The rhythmic gymnastics club according to any one of claims 1 to 4, wherein the outer peripheral surfaces of the body part and the head tip part are subjected to a matte treatment.   6. The rhythmic gymnastics club according to claim 1, wherein the body part and the head tip part have a hardness of 60 to 80. A method for producing a club for rhythmic gymnastics according to claim 1,
A mold having a cavity for injection molding each of the body part and the head tip part is opened, and the neck part and the head base end part are integrally formed at a predetermined position in the mold. Then, the mold is closed, and the body part is injection-molded at one end of the neck by injecting the second material that has been melted by heating into the cavities. A method of manufacturing a club for rhythmic gymnastics characterized by injection-molding the tip of the head at the base of the head. A method for producing a club for rhythmic gymnastics according to claim 1,
Injection as the first material that has been melted by heating in the cavity after closing the first mold having a cavity for integrally injection molding the neck and the head base end After injecting the neck and the head proximal end integrally by injecting a moldable material,
A second mold having a cavity for injection molding each of the body part and the head tip part is opened, and injection molding is performed by the first mold at a predetermined position in the second mold. After the insertion of the neck and the head base end, the second mold is closed, and the second mold is melted by heating in the cavities of the second mold. The body part is injection molded at one end of the neck by injecting the above material, and the head tip is injection molded at the head base end.

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