JP3810900B2 - Manufacturing method of hollow pipe - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a method of manufacturing a hollow pipes, further process for the preparation of hollow pipes having a section on the inner wall of the pipe in particular.
[0002]
[Prior art and problems]
Hollow plastic pipes are generally used as golf club shafts, fishing rods, etc., but the degree of bending (softness in the case of golf club shafts) such as golf club shafts, fishing rods, etc. The position of the point (called a kick point in the case of a golf club shaft), and the natural frequency of the pipe are important in determining the performance.
[0003]
In order to control the softness and kick point of such a hollow pipe, a reinforcing layer is provided on a part of the outside of the pipe. It is also known to provide a protrusion on a part of the pipe to control the softness and the position of the kick point.
[0004]
However, according to the method for controlling the kick point by wrapping the reinforcing layer around the pipe, for example, as described above, or the method of providing the protrusion, the pipe surface is uneven, which is disadvantageous in terms of design. is there.
[0005]
The present invention has been made in view of the above problems, without the formation of irregularities on the outer surface of the hollow plastic pipe, softness of the pipe, kick point position, a hollow capable of controlling the natural frequency pipes It aims at providing the manufacturing method of.
[0006]
[Means for solving problems]
The method for manufacturing a hollow pipe according to the present invention includes a step of covering an elastic pressure bag on a hollow mandrel having an air discharge hole, a ring is fitted at a predetermined position on the pressure bag, and the pressure bag does not expand at the predetermined position. And a step of winding a prepreg thereon, a step of setting the mandrel in a mold, and a step of heat-molding by injecting air from the hollow portion of the mandrel.
[000 7 ]
ADVANTAGE OF THE INVENTION According to this invention, at least 1 node is formed in the predetermined position of a hollow plastic pipe main body inner wall, and the hollow pipe excellent in the design which does not have an unevenness | corrugation in an external appearance can be manufactured . The provision of the knots at predetermined positions has the advantage that the softness of the hollow pipe, the position of the kick point, the natural frequency, etc. can be controlled. Furthermore , there is an advantage that a hollow pipe having a node at a predetermined position of the hollow pipe as described above can be easily manufactured.
[000 8 ]
DETAILED DESCRIPTION OF THE INVENTION
Hollow pipe that are more manufacturable to the present invention, a side cross-sectional view in FIG. 1, as shown in the A-A sectional view in FIG. 2, a section 11 is formed at a predetermined position of the inner wall of the hollow pipe body 1, this section 11 has a hole 12 formed in the center, and the entire pipe is hollow.
[00 09 ]
The position where such a node 11 is provided is not basically limited in the present invention, and can be determined by the softness of the hollow pipe, the position of the kick point, the natural frequency, and the like.
[001 0 ]
According to the method for manufacturing a hollow pipe according to the present invention, as shown in a partially cutaway cross-sectional view in FIG. 3, the mandrel 2 having the air discharge holes 21 is covered with the pressure bag 3 for applying pressure from the inside. In the present invention, after covering the pressure bag 3 in this way, at least one ring 4 is inserted into a predetermined position. By inserting the ring 4 in this way, the swelling of the pressure bag 3 is suppressed. On this pressure bag 3, the prepreg 5 which forms a plastic layer by further bridge | crosslinking is provided. Such a ring 4 may basically be anything as long as it basically suppresses the swelling of the pressure bag 3. However, since it should not be softened and deformed at the temperature at which the prepreg 5 is crosslinked, it is preferable to use a heat-resistant one. For example, a metal ring or the like can be used.
[001 1 ]
As such a pressure bag 2, basically any pressure bag 2 may be used as long as it has good releasability from the mandrel 1 and has elasticity that can be expanded by the pressure of air. What was conventionally used as this kind of pressure bag can be used effectively. For example, a nylon bag or a rubber bag can be used.
[001 2 ]
Thus, the mandrel 2 provided with the pressure bag 3, the ring 4, and the prepreg 5 is set in the molding die 6, air is supplied from the hollow portion of the mandrel 2, and this air is injected from the air discharge hole 21, Heat molding is performed while applying an internal pressure to the prepreg 5 through the pressure bag 3. At this time, an internal pressure is applied to the prepreg 5 due to the expansion of the pressure bag 3 and is pressed against the inner wall of the mold 6, thereby forming a hollow pipe.
[001 3 ]
However, a ring 4 is provided at a predetermined position of the pressure bag 3. For this reason, the swelling of the pressure bag 3 is suppressed in the portion where the ring 4 is provided. For this reason, when the prepreg 5 is cross-linked, the resin protrudes in the direction of the inner wall only in a portion that does not swell, and as a result, a node 11 having a hole in the center is formed. On the other hand, since the resin flows into the upper part of the node 11 from the left-right direction, a hollow pipe having a smooth appearance and having the node 11 on the inner wall can be manufactured. The prepreg used at this time may be a semi-cured state obtained by impregnating a resin into a reinforcing fiber and heating, or a non-heated one simply impregnating a resin into a reinforcing fiber.
[001 4 ]
After the prepreg 5 is cross-linked and cured in this manner, the prepreg 5 is taken out from the mold 6 and the mandrel 2 and the pressure bag 3 to which the ring 4 is attached are removed to produce a hollow pipe having a node on the inner wall.
[001 5 ]
【Example】
A mandrel having an air discharge hole was covered with a rubber pressure bag, and then the prepreg was wound, and a metal ring was attached every 5 cm (see FIG. 3). This was set in a mold as shown in FIG. 4 and heated by injecting air from the hollow portion of the mandrel to produce a hollow pipe. At this time, the pressure bag 3 did not swell in the portion where the ring 4 was provided, and a hollow pipe having a node 11 formed on the inner wall as shown in FIG. 5 could be manufactured.
[001 6 ]
For comparison, a ring was not used, and the others were produced under the same conditions. In this case, no node is formed on the inner wall at this time. Natural frequency of the hollow pipe of Comparative Example a hollow pipe that is more produced in the present invention, the position of the kick point was measured softness showed respectively different values compared to not in section hollow pipe. From this, it became clear that the natural frequency, the position of the kick point, and the softness can be controlled by forming a node on the inner wall of the hollow pipe.
[001 7 ]
【The invention's effect】
As described above, according to the hollow pipe that are more manufacturable to the present invention, a hollow plastic pipe for forming at least one node in a predetermined position of the inner body wall, no appearance irregularities design to better hollow pipe It can be. The provision of the knots at predetermined positions has the advantage that the softness of the hollow pipe, the position of the kick point, the natural frequency, etc. can be controlled. Moreover, according to the manufacturing method of the hollow pipe by this invention, there exists an advantage that the hollow pipe which has a node in the predetermined position of the above hollow pipes can be manufactured easily.
[Brief description of the drawings]
Side cross-sectional view of a hollow pipe that are more manufacturable to the present invention; FIG.
FIG. 2 is a cross-sectional view of the hollow pipe of FIG. 1 taken along the line AA.
FIG. 3 is a partially cutaway cross-sectional view for explaining a method for manufacturing a hollow pipe according to the present invention.
FIG. 4 is a cross-sectional view for explaining a method for manufacturing a hollow pipe according to the present invention.
FIG. 5 is a cross-sectional view for explaining a method for manufacturing a hollow pipe according to the present invention.
[Explanation of symbols]
2 Mandrel 21 Air exhaust hole 3 Pressure bag 4 Ring 5 Prepreg 6 Mold

Claims (1)

  A step of covering a hollow mandrel having an air discharge hole with an elastic pressure bag, a step of fitting a ring at a predetermined position on the pressure bag to prevent the pressure bag from expanding at the predetermined position, and a prepreg thereon A method of manufacturing a hollow pipe, comprising: a step of winding a wire, a step of setting the mandrel in a mold, and a step of heat-injecting air from a hollow portion of the mandrel.

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