JP2013052678A - Barrel, and method for forming barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent sense of use of a barrel with respect to all users having different gripping positions.SOLUTION: This method for forming the barrel includes: a first step of forming a barrel body 10 by primary molding; and a second step of mounting an axially extending grip 20 on the peripheral surface of the barrel body 10 by secondary molding. In the second step, a mold member 41 is arranged to hold the tip end of the barrel body 10, the mold member 41 forms a part of a cavity 44 to cover the axial tip end of the barrel body 10, and the grip 20 is formed by supplying molding material to the cavity 44.

Description

  The present invention relates to a shaft tube formed by two-color molding and a method for forming the shaft tube.

  As a method of forming this type of axial cylinder, after forming a primary molded product using a pair of axially fixed and movable molds (primary mold), a pair of axially fixed and movable molds are formed. A method is known in which a secondary molded product is formed on the outer peripheral surface of a primary molded product using a (secondary mold) (see, for example, Patent Document 1). In the method described in Patent Document 1, after the primary mold is used to form the primary molded product having a conical tip, the conical tip surface of the primary molded product is held by the holding block of the secondary mold, A part of the cavity is formed by the holding block to form a secondary molded product.

Japanese Patent No. 4487391

  By the way, when this type of shaft cylinder is applied to a writing instrument, a soft resin material such as a thermoplastic elastomer is generally used for the grip of the writing instrument as a secondary molded product in order to enhance the usability of the writing instrument. However, in the method described in Patent Document 1, since the tip end portion of the shaft tube is formed of a primary molded product, some users may feel that the position of the grip is too high and cannot obtain a sufficiently satisfactory feeling of use. There is.

The present invention is a shaft cylinder provided with a shaft cylinder body formed by primary molding and a grip attached to the outer peripheral surface of the shaft cylinder body by secondary molding, the grip extending in the axial direction, The tip portion covers the tip portion in the axial direction of the axial tube body.
In addition, the present invention includes a first step of forming the shaft tube main body by primary molding and a second step of mounting a grip extending in the axial direction on the outer peripheral surface of the shaft tube main body by secondary molding. In the second step, the mold member is arranged so as to hold the tip portion of the shaft cylinder body, and the die member covers the axial tip portion of the shaft cylinder body in the second step. A part of the cavity is formed, and a molding material is supplied to the cavity to form a grip.

  According to the present invention, since the grip is provided by secondary molding so as to cover the axial tip of the shaft tube main body, the entire gripping position of the shaft tube is covered with the grip, and the user can Good usability can be obtained.

Sectional drawing along the axis line of the writing instrument to which the axial cylinder which concerns on embodiment of this invention is applied. (A) is a side view which shows the external appearance shape of the front shaft with which the grip which concerns on embodiment of this invention was mounted | worn, (b) is the sectional drawing. (A), (b) is a figure which shows the modification of FIG. 2 (a), (b), respectively. The principal part enlarged view of FIG.2 (b) and FIG.3 (b). The figure which shows the structure of the primary metal mold | die used for primary shaping | molding among the shaping | molding methods of the axial cylinder which concerns on embodiment of this invention. (A) is a figure which shows the structure of the secondary metal mold | die used for secondary shaping | molding among the shaping | molding methods of the axial cylinder which concerns on embodiment of this invention, (b) is the principal part of FIG. 6 (a). Enlarged view. (A), (b) is a figure explaining the method of primary shaping | molding among the shaping | molding methods of the axial cylinder which concerns on embodiment of this invention, respectively. (A), (b) is a figure explaining the method of secondary shaping | molding among the shaping | molding methods of the axial cylinder which concerns on embodiment of this invention, respectively. (A), (b), (c) is a figure which shows the modification of FIG. 4, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view along an axis L0 of a writing instrument 100 to which a shaft tube according to an embodiment of the present invention is applied, and shows a knock-type ballpoint pen as an example. For convenience of explanation, in the following, the front-rear direction is defined along the axis L0 as shown, and the configuration of each part will be described according to this definition.

  A writing instrument 100 in FIG. 1 includes a shaft cylinder 1 extending in the front-rear direction, a refill 2 disposed inside the shaft cylinder 1, and a knock portion 3 provided at a rear end portion of the shaft cylinder 1. The refill 2 is configured by attaching a ballpoint pen tip to a front end portion of an ink containing tube containing ink for writing instruments, and is urged backward by a spring 4. The knock portion 3 integrally has a clip (not shown), and when the knock portion 3 is pressed against the urging force of the spring 4, the refill 2 moves in the front-rear direction within the shaft tube 1, and the refill is performed. The tip of 2 can be advanced and retracted from the front end of the barrel 1.

  The shaft cylinder 1 includes a cylindrical front shaft 10 and a rear shaft 11 that constitute a shaft cylinder main body, and a grip 20 that is attached to the outer peripheral surface of the front shaft 10. Screw portions 10a and 11a are respectively provided on the outer peripheral surface of the rear end portion of the front shaft 10 and the inner peripheral surface of the front end portion of the rear shaft 11, and the rear shaft 11 is connected to the rear end portion of the front shaft 10 via the screw portions 10a and 11a. Are screwed together. For this reason, the rear shaft 11 can be attached to and detached from the front shaft 10, and the refill 2 inside the shaft tube can be easily replaced by removing the rear shaft 11 from the front shaft 10.

  2A is a side view showing the external shape of the front shaft 10 to which the grip 20 is attached, and FIG. 2B is a longitudinal sectional view thereof. The grip 20 is attached to the outer peripheral surface of the front shaft 10 by two-color molding. That is, the grip 20 as the secondary molded product is integrally fused to the front shaft 10 so as to cover the outer peripheral surface of the front shaft 10 as the primary molded product. Hereinafter, the front shaft 10 and the grip 20 may be referred to as a primary molded product 10 and a secondary molded product 20, respectively.

  The front shaft 10 is made of a semi-rigid or hard resin material such as polypropylene or polycarbonate. The rear shaft 11 is also made of the same resin material as the front shaft 10. The rear shaft 11 can be made of a material different from that of the front shaft 10. The grip 20 is made of, for example, a material having rubber elasticity such as a thermoplastic elastomer or a soft resin material. For this reason, the elastic modulus of the grip 20 is smaller than the elastic modulus of the front shaft 10 and the rear shaft 11.

  The front shaft 10 has an outer diameter that gradually decreases from the front end portion 12 to a tapered shape as a whole. The grip 20 as well as the front shaft 10 has a tapered shape as a whole. The grip 20 is formed so as to cover the entire outer peripheral surface of the front shaft 10. That is, the front end portion of the grip 20 projects forward from the front end portion of the front shaft 10 as will be described later. Further, a contact surface 20 a is formed at the rear end portion of the grip 20 so that the front end surface of the rear shaft 11 contacts when the rear shaft 11 is screwed into the front shaft 10.

  For this reason, the front shaft 10 is not exposed to the outside in a state where the rear shaft 11 is screwed to the front shaft 10 as shown in FIG. Therefore, when used as a writing instrument, the entire position where the user's finger hits (gripping position) can be covered with the grip 20, and a good feeling of use of the shaft tube 1 can be given to any user with different gripping positions. it can. That is, both the user who holds the reduced diameter portion 1a at the tip of the shaft cylinder and the user who holds the large diameter portion 1b behind the reduced diameter portion 1a hold the grip 20 and can obtain a good feel during use.

  As shown in FIGS. 3A and 3B, a ring-shaped protrusion 13 is provided on the outer peripheral surface of the front shaft 10, and the front end surface of the protrusion 13 and the grip 20 are formed during two-color molding. The rear end surface may be brought into contact, and when the rear shaft 11 is screwed, the front end surface of the rear shaft 11 may be brought into contact with the 13 rear end surface of the protrusion. Also in this case, the entire gripping position can be covered with the grip 20, and a good feeling of use of the shaft tube 1 can be given to all users having different gripping positions.

  FIG. 4 is an enlarged view of a main part of FIGS. 2B and 3B and shows the shapes of the front shaft 10 and the tip of the grip 20. A plurality of step portions 14 are formed on the inner peripheral surface of the front shaft 10 so as to be separated from each other in the front-rear direction, and the inner diameter of the front shaft 10 gradually increases toward the rear with the step portion 14 as a boundary. The inner peripheral surface of the front end portion 12 of the front shaft 10 extends in parallel with the axis L0 (FIG. 1), and a cylindrical surface 15 is formed. The inner diameter of the front shaft 10 is a minimum d1 on the cylindrical surface 15. The front end face 16 of the front shaft 10 is formed perpendicular to the axis L0.

  The front end portion of the grip 20 is provided with a protruding portion 21 that protrudes radially inward over the entire circumference. The front end surface 22 of the protrusion 21 is formed perpendicular to the axis L0, and the rear end surface 23 is in contact with the front end surface 16 of the front shaft 10. The inner peripheral surface of the protrusion 21 extends in parallel with the axis L0, and a cylindrical surface 25 having a diameter d2 is formed. The diameter d2 of the cylindrical surface 25 is larger than the diameter d1 of the cylindrical surface 15, and only a part of the front end surface 16 of the front shaft 10 is covered with the protruding portion 21 of the grip 20.

  The structure of the metal mold | die for shape | molding the front axis | shaft 10 and the grip 20 comprised as mentioned above is demonstrated. FIG. 5 is a diagram showing a configuration of a primary mold 30 used for primary molding, and FIG. 6A is a diagram showing a configuration of a secondary mold 40 used for secondary molding. FIGS. 5 and 6A particularly show the molds of the front side portions of the front shaft 10 and the grip 20.

  The primary molding is performed in the first molding region centered on the axis L1, and the secondary molding is performed in the second molding region centered on the axis L2. In the primary molding, the front shaft 10 is formed as a primary molded product, and in the secondary molding, the grip 20 is formed as a secondary molded product. The axis line L1 and the axis line L2 are parallel and spaced apart from each other, and a second molding region exists on the side of the first molding region.

  As shown in FIG. 5, the primary mold 30 includes a fixed core pin 31 and a movable core pin 32 arranged along the axis L <b> 1, and a block 33 arranged around the fixed core pin 31 and the movable core pin 32. A cavity 34 corresponding to the shape of the front shaft 10 is formed in a space surrounded by the fixed core pin 31, the movable core pin 32 and the block 33.

  The fixed core pin 31 is a fixed mold having a cylindrical large-diameter portion 31a and a small-diameter portion 31b, and the whole exhibits a stepped shape in the axial direction. The diameter of the small diameter part 31b is d1 (FIG. 4). The movable core pin 32 is a movable mold that approaches and separates from the fixed core pin 31 and has an outer peripheral surface shape corresponding to the inner peripheral surface shape of the front shaft 10. A concave portion 32a into which a part of the small diameter portion 31b of the fixed mold 31 is fitted is formed at the distal end portion of the movable core pin 32, and a concave portion 32b having a smaller diameter than the concave portion 32a is formed on the bottom surface of the concave portion 32a.

  In FIG. 5, the small-diameter portion 31b is fitted in the recess 32a, and in this state, the outer peripheral surface of the small-diameter portion 31b forms the cylindrical surface 15 (FIG. 4) of the front shaft 10, and the end surface 31c of the large-diameter portion 31a A front end face 16 (FIG. 4) of the front shaft 10 is formed. The block 33 is movable in the radial direction, for example, in a half crack shape divided into two in the circumferential direction, and exhibits an inner circumferential surface shape corresponding to the outer circumferential surface shape of the front shaft 10.

  As shown in FIG. 6A, the secondary mold 40 includes a fixed core pin 41 and a movable core pin 42 arranged along the axis L2, and a block 43 arranged around the fixed core pin 41 and the movable core pin 42. Have The movable core pin 42 is obtained by moving the movable core pin 32 to the second molding region while the primary molded product 10 (front shaft) is attached to the movable core pin 32 in the first molding region. That is, the movable core pin 42 is the same as the movable core pin 32, and the concave portion 32 a and the concave portion 32 b at the distal end portion of the movable core pin 32 become the concave portion 42 a and the concave portion 42 b at the distal end portion of the movable core pin 42 as they are. A cavity 44 corresponding to the shape of the grip 20 is formed in a space surrounded by the primary molded product 10 attached to the movable core pin 42, the fixed core pin 41, and the block 43.

  The fixed core pin 41 is a fixed mold having a cylindrical large-diameter portion 41a and a small-diameter portion 41b, and the whole exhibits a stepped shape in the axial direction. The movable core pin 42 is a movable mold that approaches and separates from the fixed core pin 41 integrally with the primary molded product 10. The diameter of the small diameter portion 41b of the fixed core pin 41 is equal to the diameter of the concave portion 42b of the movable core pin 42, and the tip of the small diameter portion 41b is fitted in the concave portion 42b in the drawing. The block 43 has, for example, a half crack shape divided into two in the circumferential direction, and exhibits an inner peripheral surface shape corresponding to the outer peripheral surface shape of the front shaft 10.

  FIG. 6B is an enlarged view of the main part of FIG. As shown in FIG. 6B, the diameter d3 of the small diameter portion 41b of the fixed core pin 41 is smaller than the diameter d1 of the cylindrical surface 15 of the primary molded article 10, and the entire circumference is between the small diameter portion 41b and the cylindrical surface 15. A gap 45 is open. The diameter d2 of the large diameter portion 41a is smaller than the outermost diameter d4 of the tip surface (front end surface 16 of the front shaft) of the primary molded product 10, and the axial length of the small diameter portion 41a is the tip surface of the primary molded product 10. 16 is shorter than the length from the bottom surface of the recess 42b.

  For this reason, in a state where the small diameter portion 41 b is fitted in the concave portion 42 b, the end surface 42 c of the large diameter portion 41 a comes into contact with the distal end surface 16 of the primary molded product 10, and a part of the distal end surface 16 is covered with the fixed core pin 41. Yes. At this time, the outer peripheral surface of the large diameter portion 41 a forms the cylindrical surface 22 of the grip 20.

Next, a method for forming the front shaft 10 and the grip 20 will be described.
(1) Primary molding First, as shown in FIG. 5, in the first molding region, the fixed core pin 31 of the primary mold 30 is fitted into the recess 32a of the movable core pin 32, and the fixed core pin 31, the movable core pin 32, and the block Cavity 34 is formed between them. Next, the resin for primary molding is supplied to the cavity 34 to form the primary molded product 10 (front shaft). Next, as shown in FIG. 7A, after the block 33 is separated from the outer peripheral surface of the fixed core pin 31, the movable core pin 32 is indicated by an arrow A along the axis L1 as shown in FIG. 7B. In this way, the primary molded product 10 is moved backward together.

(2) Secondary molding Thereafter, when secondary molding is performed, the movable core pin 32 integrated with the primary molded product 10 is moved from the first molding region to the second molding region. The moved movable core pin 32 constitutes the secondary mold 40 and is represented as a movable core pin 42. Next, the movable core pin 42 is advanced toward the fixed core pin 41 along the axis L2, and the fixed core pin 41 is fitted into the recess 42b of the movable core pin 42 as shown in FIG. The front end face 16 of the primary molded product 10 is brought into contact with 41c. At this time, the outer peripheral surface of the fixed core pin 41 and the inner peripheral surface of the distal end portion 12 of the primary molded product 10 are not in contact with each other, and a gap 45 is opened in the circumferential direction between them. Thus, the cavity 44 is formed between the fixed core pin 41, the primary molded product 10, and the block 43.

  Next, a resin for secondary molding is supplied to the cavity 44, the secondary molded product 20 (grip) is welded to the outer peripheral surface of the primary molded product 10, and two-color molding is performed. At this time, the resin in the cavity 44 is sealed by the contact surfaces 41 c and 16 between the fixed core pin 41 and the primary molded product 10. Next, as shown in FIG. 8A, after the block 34 is separated from the outer peripheral surface of the fixed core pin 31, the movable core pin 42 is indicated by an arrow B along the axis L2 as shown in FIG. 8B. Thus, the molded products 10 and 20 are moved backward together. Finally, the molded products 10 and 20 are removed from the movable core pin 42, and the molding of the front shaft 10 and the grip 20 is completed.

According to the present embodiment, the following operational effects can be achieved.
(1) The grip 20 is attached to the outer peripheral surface of the front shaft 10 by two-color molding from the front end portion 12 of the front shaft 10 to the axial direction (FIGS. 2 and 3). Thereby, since the whole holding position of the axial cylinder 1 is covered with the grip 20, when using as a writing instrument, the favorable feeling of use of the axial cylinder 1 can be given to all users having different holding positions.

(2) Since the front end portion (front end surface 22) of the grip 20 protrudes forward from the front end portion (front end surface 16) of the front shaft 10 (FIG. 4), the shaft cylinder 1 is accidentally dropped. In this case, damage to the front shaft tip can be prevented.
(3) Cylindrical surfaces 15 and 25 are respectively formed at the front end portion 12 of the front shaft 10 and the front end portion (projecting portion 21) of the grip 20, and the inner diameter d2 of the cylindrical surface 25 is made larger than the inner diameter d1 of the cylindrical surface 15 ( FIG. 4). Accordingly, when the shaft 20 is used, even when the grip 20 is swollen by user's hand oil or the like, the inner diameter d2 of the grip 20 is not smaller than d1, and the refill 2 is advanced or retracted from the tip of the shaft 1. Interference between the grip 20 and the refill 2 can be prevented.

(4) At the time of secondary molding, the front end surface 16 of the front shaft 10 and the end surface 41c of the fixed core pin 41 are brought into contact with each other, and a grip molding cavity 44 is formed using this contact surface as a sealing surface ( In FIG. 6B, the flash generated by the molding extends in the radial direction (so-called side flash). For this reason, the inner diameter of the grip tip (projection 21) can be set to d2 without being affected by the flash, and interference with the refill 2 can be reliably prevented. On the other hand, for example, when sealing with the cylindrical surface of the fixed core pin 41 at the time of secondary molding, the flash may extend in the axial direction by molding (so-called vertical flash), and the inner diameter of the molded product may be reduced by the amount of flash. In this case, there is a possibility of interference with the refill 2.
(5) The fixed core pin 41 has a stepped shape having a small-diameter portion 41b and a large-diameter portion 41a, and the end surface 41c of the large-diameter portion 41a is brought into contact with the front end surface 16 of the primary molded product 10, thereby Since part of the cavity 44 is formed on the surface, the grip 20 can be more easily projected in the axial direction than the front shaft 10.

(6) The diameter d3 of the small diameter part 41b of the fixed core pin 41 at the time of secondary molding was made smaller than the diameter d1 of the cylindrical surface 15 of the tip part 12 of the primary molded product 10 (FIG. 6B). Accordingly, the fixed core pin 41 can be fitted into the concave portion 42b of the movable core pin 42 without being brought into contact with the cylindrical surface 15 of the primary molded product 10, and damage to the primary molded product 10 can be prevented.
(7) Since the tip of the small-diameter portion 41b of the fixed core pin 41 is fitted into the concave portion 42b of the movable core pin 42 (FIG. 6B), the axis of the fixed core pin 41 and the movable core pin 42 can be matched. The shaft tube 1 can be formed with high accuracy.

  In the above embodiment, the front end portion of the grip 20 is provided with the protruding portion 21 that protrudes toward the inner diameter side, and a part of the front end surface 16 of the front shaft 10 is covered with the grip 20. The shape of the part is not limited to this. As a modification of the shape of the tip portion of the shaft tube 1, as shown in FIG. 9A, the front end surface 22 of the grip 20 and the front end surface 16 of the front shaft 10 may be matched. Alternatively, as shown in FIG. 9B, the cylindrical surface 25 of the grip 20 and the cylindrical surface 15 of the front shaft 10 may be matched.

  Alternatively, as shown in FIG. 9C, instead of the cylindrical surface 25 shown in FIG. 9B, the grip 20 has an inversely tapered surface, for example, a cut surface, whose inner diameter increases toward the front in the axial direction. It is good also as a structure containing the head cone surface 25 '. In the configuration of FIG. 9C, the inner diameter d1 ′ at the position adjacent to the front end face 16, which is the smallest inner diameter of the truncated conical surface 25 ′, is the same as the inner diameter d1 of the cylindrical surface 15 (d1 ′ = d1). ), The inner diameter d2 ′ at the position of the tip of the grip 20 having the largest inner diameter of the truncated conical surface 25 ′ is larger than the inner diameter d1 (d2 ′> d1). The smallest inner diameter d1 'of the truncated conical surface 25' may be larger than d1 (d1 '> d1). According to this configuration, even when the grip 20 is swollen by user's hand oil or the like when the shaft cylinder 1 is used, the inner diameter d1 ′ of the portion adjacent to the front end surface 16 of the grip 20 It does not deform because it is fused. On the other hand, the inner diameter of the frustoconical surface 25 ′ does not become smaller than d <b> 1 because the inner diameter gradually increases toward the front as described above at a location away from the front end surface 16. Therefore, the shaft cylinder 1 according to the modified example of FIG. 9C is configured to prevent interference between the grip 20 and the refill 2 when the refill 2 is advanced and retracted from the distal end portion of the shaft cylinder 1.

  As described above, the modification of the shape of the distal end portion of the barrel 1 has been shown with reference to FIGS. 9A to 9C, but the distal end portion of the grip 20 covers the distal end portion of the front shaft 10. If the grip 20 is provided in the entire gripping position for the user to grip the shaft tube 1 in use, the shape of the shaft tube 1 may be any.

  In the above-described embodiment, the front shaft 10 is formed by primary molding. However, the front shaft 10 may be molded as an integral shaft cylinder main body without being divided into the front shaft 10 and the rear shaft 11, and the configuration of the shaft cylinder main body is described above. It is not limited to what you did. In the above embodiment, the distal end portion (small diameter portion 41 b) of the fixed core pin 41 is fitted into the concave portion 42 b of the movable core pin 42 so as to hold the primary molded product 10. As long as the cavity 44 is formed so as to cover the tip of the shaft 10 in the axial direction, other holding forms may be adopted. For example, the tip of the fixed core pin 41 may be fitted into the concave portion 41 a of the movable core pin 42. Alternatively, the primary molded product 10 may be held by simply pressing the front end surface 16 of the primary molded product 10 against the end surface of the fixed core pin 41 without fitting the fixed core pin 41 to the movable core pin 42.

  In the above-described embodiment, the small diameter portion 41b (first cylindrical surface) and the large diameter portion 41a (second cylindrical surface) that are coaxial with each other, and the end surface 41c (connection surface) that connects the small diameter portion 41b and the large diameter portion 41a. Secondary molding was performed using a fixed core pin 41 having Specifically, the small-diameter portion 41b is inserted into the cylindrical surface 15 of the front shaft 10, and the end surface 41c of the fixed core pin 41 is brought into contact with the front end surface 16 of the front shaft 10, and the cavity 44 is formed by the large-diameter portion 41a. However, the shape of the fixed core pin 41 is appropriately changed according to the shape of the tip of the grip 20 and the front shaft 10 as shown in FIG. The configuration of the mold member for use is not limited to that described above. For example, the front end surface 22 of the grip 20 may be formed by the fixed core pin 41, and the outer peripheral surface of the grip 20 may be further formed.

  That is, the second step includes a first step of forming the front shaft 10 by primary molding and a second step of mounting the grip 20 extending in the axial direction on the outer peripheral surface of the front shaft 10 by secondary molding. In this step, the mold member 41 is disposed so as to hold the front end portion of the front shaft 10, and the mold member 41 forms a part of the cavity 44 that covers the front end portion of the front shaft 10 in the axial direction. If the molding material is supplied to the cavity 44 and the grip 20 is formed, the molding method of the shaft cylinder 1 is not limited to that described above. Here, covering the front end portion of the front shaft 10 in the axial direction means covering the outer peripheral surface of the front shaft 10 at least to the front end.

  In the above, the case where the shaft cylinder is applied to the knock type ballpoint pen has been described. The present invention can be similarly applied to other shaft cylinders. That is, the present invention is not limited to the shaft cylinder of the embodiment as long as the features and functions of the present invention can be realized.

  If the refill 2 in the shaft cylinder is made of a ballpoint pen containing thermochromic ink or the like, it is possible to change the handwriting color at the front shaft tip when not writing. Further, since the grip is covered up to the tip of the front shaft, the color can be easily changed without changing the shaft and without adjusting the inclination angle between the front shaft and the handwriting surface.

1 Shaft cylinder 10 Front shaft (Primary molded product)
16 Front end surface 12 Tip portion 20 Grip (secondary molded product)
DESCRIPTION OF SYMBOLS 21 Protrusion part 22 Front end surface 25 Cylindrical surface 30 Primary mold 31 Fixed core pin 32 Movable core pin 40 Secondary mold 41 Fixed core pin 41a Large diameter part 41b Small diameter part 41c End surface 42 Movable core pin 44 Cavity

Claims (7)

A shaft cylinder body formed by primary molding;
A grip attached to the outer peripheral surface of the shaft cylinder main body by secondary molding,
The shaft extends in the axial direction, and a tip portion of the grip covers the tip portion in the axial direction of the shaft tube main body. The shaft cylinder according to claim 1,
The shaft cylinder, wherein a tip end portion of the grip protrudes in an axial direction from a tip end portion of the shaft cylinder main body. In the shaft cylinder according to claim 2,
The grip has a protrusion that protrudes toward the inner diameter side along the axial front end surface of the shaft cylinder body, and the inner diameter of the protrusion is the same as the inner diameter of the tip portion of the shaft cylinder body or the shaft cylinder body A shaft cylinder characterized in that it is larger than the inner diameter of the tip of the shaft. In the shaft cylinder according to claim 2,
The grip has a protruding portion that protrudes toward the inner diameter side along the axial front end surface of the axial tube body, and the inner surface of the protruding portion has a reverse tapered shape in which the inner diameter increases toward the axial tube distal end direction. Have
A shaft cylinder characterized in that an inner diameter of a portion of the projecting portion having the smallest inner diameter on the inner surface is the same as or larger than an inner diameter of a tip portion of the shaft cylinder body. A first step of forming a barrel body by primary molding;
A second step of mounting an axially extending grip on the outer peripheral surface of the shaft tube main body by secondary molding, and a method of forming a shaft tube,
In the second step, a mold member is disposed so as to hold the tip end portion of the shaft tube main body, and the mold member has a cavity that covers the tip end portion in the axial direction of the shaft tube body. Forming a gripper by forming a portion and supplying a molding material to the cavity. It is a shaping | molding method of the axial cylinder of Claim 5, Comprising:
In the second step, the shaft cylinder is formed by bringing the end surface of the mold member into contact with the tip surface of the shaft cylinder main body to form the cavity. It is a shaping | molding method of the axial cylinder of Claim 6, Comprising:
The mold member includes a first cylindrical surface, a second cylindrical surface that is coaxial with the first cylindrical surface and has a larger diameter than the first cylindrical surface, and the first cylindrical surface. A connection end surface connecting the second cylindrical surface,
In the second step, the first cylindrical surface of the mold member is inserted into the shaft tube main body, and the connection end surface is brought into contact with the tip surface of the shaft tube main body, so that the second cylinder A method of forming a shaft cylinder, wherein a part of the cavity is formed on a surface.

Images