JP7585782B2 - Tubular body and method of manufacturing same - Google Patents

Description

This disclosure relates to a tubular body and a method for manufacturing the same.

Golf club shafts made of fiber-reinforced resin are widely known. JP 2010-260344 A discloses that wrapping tape is used in the manufacture of these shafts. Tubular bodies other than golf club shafts can also be manufactured by this manufacturing method. Examples of tubular bodies other than golf club shafts include tennis racket frames, badminton racket frames, fishing rods, trekking poles, walking poles, walking sticks, etc.

JP 2010-260344 A

After extensive research, the inventors discovered that the strength of the tubular body can be increased by changing the way the wrapping tape is wrapped.

One of the objectives of this disclosure is to provide a tubular body with excellent strength.

In one embodiment, the tubular body is made of fiber-reinforced resin. The tubular body is manufactured by winding a wrapping tape fed at a feed angle θ1 in a spiral shape at a helical angle θs and then heat-curing the wrapping tape. The feed angle θ1 is greater than 0°. A rate of change X of the feed angle θ1 with respect to the helical angle θs is -60% or more and 200% or less. The rate of change X (%) is calculated by the following formula:
X=[(θ1/θs)-1]×100

In another aspect, a method for manufacturing a tubular body includes a winding step of winding a fiber-reinforced resin material around a mandrel to obtain an intermediate wound body, a wrapping step of winding a wrapping tape fed at a feed angle θ1 in a spiral shape around the intermediate wound body at a helical angle θs, a curing step of heating the intermediate wound body around which the wrapping tape is wound, and a step of removing the wrapping tape after the curing step. The feed angle θ1 is greater than 0°. A rate of change X of the feed angle θ1 with respect to the helical angle θs is -60% or more and 200% or less. The rate of change X (%) is calculated by the following formula.
X=[(θ1/θs)-1]×100

As one aspect, a tubular body with excellent strength can be provided.

FIG. 1 shows a tubular body according to a first embodiment and its development view. FIG. 2 shows a tubular body according to a second embodiment and its development view. FIG. 3 is a conceptual diagram showing the manufacturing method of the present disclosure. FIG. 4 is a conceptual diagram showing a conventional manufacturing method. FIG. 5 is an enlarged view of a main portion of FIG.

The following describes the embodiments in detail, with reference to the drawings as appropriate.

Figure 1 shows a golf club shaft 2, which is a tubular body of the first embodiment, and an exploded view of this shaft 2.

The shaft 2 has a tip end Tp and a butt end Bt. The outer diameter of the shaft 2 is constant. The outer diameter of the shaft 2 at the tip end Tp is the same as the outer diameter of the shaft 2 at the butt end Bt. The shaft 2 has a center line z1. The inside of the shaft 2 is hollow. The shaft 2 is a tubular body. In a golf club having the shaft 2, a head is attached to the end on the tip end Tp side, and a grip is attached to the end on the butt end Bt.

The material of the shaft 2 is a sheet-like prepreg. A sheet-like prepreg is also called a prepreg sheet. In this application, a prepreg sheet is also simply called a sheet. In a typical prepreg sheet, the fibers are oriented in one direction, and this is also called a UD prepreg. UD stands for unidirectional. The shaft 2 is made by winding and curing multiple prepreg sheets.

The shaft 2 is manufactured by a sheet winding method. The manufacturing method of the shaft 2 is not limited. For example, the shaft 2 may be manufactured by a filament winding method. The shaft 2 may be manufactured by a method that combines sheet winding and filament winding. In addition, the prepreg is not limited to a UD prepreg, and for example, the fibers contained in the prepreg may be woven.

The shaft 2 is formed from multiple prepreg sheets. In this embodiment, sheets s1 to s5 are used. A mandrel 4 is used to manufacture the shaft 2. The mandrel 4 is made of metal. The mandrel 4 forms the inner surface of the shaft 2. The outer diameter of the mandrel 4 is constant.

The shaft 2 includes a bias layer and a straight layer. Sheets s1 and s2 form the bias layer. The bias sheet is formed by combining a first sheet s1, whose fibers are oriented at -θ° relative to the center line z1, with a second sheet s2, whose fibers are oriented at +θ° relative to the center line z1. The bias layers s1 and s2 are formed by winding the bias sheets s1 and s2. The bias layers s1 and s2 are arranged over the entire length of the shaft. θ is typically set to 45°±10°. In this embodiment, θ is 45°.

In FIG. 1, the fiber inclination direction appears to be the same for sheets s1 and s2. However, sheet s2 is turned over and attached to sheet s1. As a result, the fiber inclination directions of sheets s1 and s2 are opposite to each other.

Sheets s3 and s5 form a straight layer. In the straight layer, the fibers are oriented at 0° (±10°) with respect to the center line z1. The straight layers s3 and s5 are formed by winding the straight sheets s3 and s5. The straight layers s3 and s5 are arranged over the entire length of the shaft.

The shaft 2 further includes a hoop layer. The sheet s4 constitutes the hoop layer. In the hoop layer, the fibers are oriented at 90° (±10°) with respect to the center line z1. The hoop sheet s4 is wound to form the straight layer s4. The hoop layer s4 is disposed over the entire length of the shaft.

The laminated structure of shaft 2 is an example. In this disclosure, the laminated structure of the shaft is not limited.

Figure 2 shows a golf club shaft 6 of the second embodiment and its development view.

The shaft 6 has a tip end Tp and a butt end Bt. The outer diameter of the shaft 6 is not constant. The outer diameter of the shaft 2 at the tip end Tp is smaller than the outer diameter of the shaft 2 at the butt end Bt. The shaft 6 has a tapered portion whose outer diameter decreases as it approaches the tip end Tp. The shaft 6 has a center line z1. The inside of the shaft 6 is hollow. The shaft 6 is a tubular body. In a golf club having the shaft 6, a head is attached to the end on the tip end Tp side, and a grip is attached to the end on the butt end Bt.

The material of the shaft 6 is a sheet-shaped prepreg. The shaft 6 is made by winding and curing multiple prepreg sheets. The shaft 6 is formed from multiple prepreg sheets. In this embodiment, sheets s1 to s6 are used. A mandrel 8 is also used to manufacture the shaft 6. The mandrel 8 is made of metal. The mandrel 8 shapes the inner surface of the shaft 6. The mandrel 8 has a tapered portion.

The shaft 6 includes a bias layer and a straight layer. Sheets s1 and s2 form the bias layer. The bias sheet is formed by combining a first sheet s1, whose fibers are oriented at -θ° relative to the center line z1, with a second sheet s2, whose fibers are oriented at +θ° relative to the center line z1. The bias sheets s1 and s2 are wound to form the bias layers s1 and s2. The bias layers s1 and s2 are arranged over the entire length of the shaft. In this embodiment, θ is 45°.

Sheets s3 and s5 form a straight layer. In the straight layer, the fibers are oriented at 0° (±10°) with respect to the center line z1. The straight layers s3 and s5 are formed by winding the straight sheets s3 and s5. The straight layers s3 and s5 are arranged over the entire length of the shaft.

The shaft 6 further includes a hoop layer. The sheet s4 constitutes the hoop layer. In the hoop layer, the fibers are oriented at 90° (±10°) with respect to the center line z1. The hoop sheet s4 is wound to form the straight layer s4. The hoop layer s4 is arranged along the entire length of the shaft.

The shaft 6 further includes a partial straight layer. The partial straight layer is a straight layer that is located in a portion of the shaft in the axial direction. The partial straight layer is formed by winding the straight sheet s6. The partial straight layer s6 reinforces the end of the shaft 6 on the tip end Tp side. In the portion where the partial straight layer s6 is located, the outer diameter of the shaft 6 is constant.

The laminated structure of shaft 6 is an example. In this disclosure, the laminated structure of the shaft is not limited.

An example of the manufacturing process for a golf club shaft 6 is described below.

[An example of the manufacturing process for golf club shafts]

(1) Cutting Step In the cutting step, the prepreg sheet is cut into a desired shape.

The cutting may be done by a cutting machine. The cutting may also be done manually, for example using a utility knife.

(2) Lamination Step If necessary, a plurality of sheets are laminated together to produce a combined sheet. The bias sheets are laminated together to produce a combined sheet.

(3) Winding Process In the winding process, a mandrel is prepared. A release agent is applied to the mandrel, and then a tacky resin is applied to the mandrel. This resin is also called a tacking resin. The cut sheet is wound around the mandrel. The tacking resin makes it easy to attach the ends of the sheet to the mandrel.

Each sheet is attached to the object to be wound at a predetermined attachment position. The object to be wound is then rolled. This winding can be done manually or by machine, which is called a rolling machine. The object to be wound is a mandrel or a mandrel around which one or more sheets are wound. Once all the sheets have been wound, an intermediate roll is obtained.

(4) Wrapping Step In the wrapping step, a wrapping tape is wound around the outer circumferential surface of the intermediate roll. The wrapping tape is a tape-shaped wrapping film. The wrapping tape is wound while tension is applied.

(5) Curing process In the curing process, the intermediate wound body after wrapping is heated. This heating hardens the matrix resin while forming the shaft into a tubular shape. During this curing process, the matrix resin temporarily becomes fluid. This fluidization of the matrix resin can eliminate voids between and within the sheets. The tightening pressure of the wrapped wrapping tape promotes the elimination of voids.

(6) Mandrel Removal Step and Wrapping Tape Removal Step After the curing step, the mandrel is removed and the wrapping tape is removed. As a result, a hardened tubular body is obtained. From the viewpoint of improving the efficiency of the wrapping tape removal step, it is preferable that the wrapping tape removal step is performed after the mandrel removal step.

(7) Both End Cutting Step In this step, both end portions of the cured laminate are cut to flatten the end surfaces of the tip end Tp and the butt end Bt.

(8) Polishing step In this step, the surface of the cured laminate is polished. On the surface of the cured laminate, irregularities may be formed as a result of the wrapping tape. By polishing, these irregularities can be removed, and the surface of the shaft can be made smooth.

(9) Painting Step The cured laminate after the polishing step is painted.

Tubular bodies other than golf club shafts can also be manufactured using the above manufacturing process.

In this manufacturing method, prepreg is used as the fiber-reinforced resin material. In this manufacturing method, a sheet-shaped prepreg (prepreg sheet) is wound around a mandrel. In addition to prepreg sheets, examples of the fiber-reinforced resin material include tow prepregs and slit prepregs. This fiber-reinforced resin material may be a fiber bundle impregnated with liquid resin.

The prepreg sheet contains fibers and a matrix resin. In this embodiment, the fibers are carbon fibers. In this embodiment, the carbon fibers are oriented in one direction. The fibers may be other than carbon fibers. From the viewpoint of obtaining a high-strength, lightweight shaft, carbon fibers are preferred.

Figure 3 is a schematic diagram showing the wrapping process in this disclosure. In the wrapping process, a wrapping machine 10 is used. In the wrapping process of tubular bodies such as golf club shafts, a commercially available wrapping machine manufactured by Yokote Iron Works is used. The wrapping machine 10 in Figure 3 is a modified version of this commercially available product manufactured by Yokote Iron Works.

The wrapping machine 10 has a tape delivery section 12, a rail 14, and a rotating holding section 16. The intermediate winding body 18 wound around the mandrel 4 is set in the rotating holding section 16. When set in the rotating holding section 16, the center line of the intermediate winding body 18 is parallel to the rail 14. Although only one end side of the intermediate winding body 18 is shown in FIG. 3, the rotating holding section 16 holds both ends of the intermediate winding body 18. The intermediate winding body 18 is held in a state parallel to the rail 14. The tape delivery section 12 moves along the rail 14. The rotating holding section 16 rotates the intermediate winding body 18. This rotation winds up the wrapping tape 30. The wrapping tape 30 is wound at a helical angle θs. The helical angle θs is the angle of the wound tape 30 with respect to the circumferential direction D2 of the intermediate winding body 18. The circumferential direction D2 is perpendicular to the center line of the intermediate winding body 18. The axis of rotation is the center line of the intermediate winding body 18. The moving speed of the tape delivery section 12 and the number of rotations of the intermediate winding body 18 are controlled. The wrapping tape 30 can be wound at a constant pitch Pt.

The helical angle θs can be measured, or it can be calculated from the pitch Pt and the outer diameter of the intermediate winding body 18.

Figure 4 is a schematic diagram showing a conventional wrapping process. In the wrapping process, a wrapping machine 20 is used. This wrapping machine 20 is the wrapping machine manufactured by Yokote Iron Works, as mentioned above.

The wrapping machine 20 has a tape delivery section 22, a rail 24, and a rotating holding section 26. The intermediate winding body 18 wound around the mandrel 4 is set in the rotating holding section 26. When set in the rotating holding section 26, the center line of the intermediate winding body 18 is parallel to the rail 24. The intermediate winding body 18 is held in a state parallel to the rail 24. The tape delivery section 22 moves along the rail 24. The rotating holding section 26 rotates the intermediate winding body 18. This rotation winds up the wrapping tape 30. The moving speed of the tape delivery section 22 and the rotation speed of the intermediate winding body 18 are controlled.

In wrapping machine 10 and wrapping machine 20, wrapping tape 30 is pulled out in a predetermined direction. The tension of wrapping tape 30 during winding is controlled.

The difference between the presently disclosed wrapping machine 10 (FIG. 3) and the commercially available wrapping machine 20 (FIG. 4) is whether the orientation of the tape feed section can be changed. In other words, this difference is whether the feed angle θ1 of the wrapping tape 30 relative to the intermediate winding body 18 can be changed. The wrapping machine 10 is a modified version of the commercially available wrapping machine 20. In the wrapping machine 10, the tape feed section 12 is configured to be rotatable relative to the rail 14 and fixed at any rotation angle. In the wrapping machine 10, the feed angle θ1 of the wrapping tape 30 relative to the intermediate winding body 18 can be adjusted. Furthermore, the wrapping machine 10 can also change the feed angle θ1 during wrapping. On the other hand, in the wrapping machine 20 (a wrapping machine manufactured by Yokote Iron Works), the feed angle θ1 is fixed at 0° and cannot be adjusted. The feed angle θ1 is the angle between the direction D1 of the wrapping tape 30 fed from the tape feed section and the circumferential direction D2 of the intermediate winding body 18. The direction D1 is also called the feed direction. The feed direction D1 is the direction of the center line of the wrapping tape 30 fed from the tape feed section 12. For wrapping tape 30 with a constant width, this center line direction is also the direction of the edges (both edges) of the tape 30.

As mentioned above, the feed angle θ1 was 0° in the conventional method. Therefore, as shown in FIG. 4, the spiral angle θs of the wrapping tape 30 wound in a spiral shape was different from the feed angle θ1. Therefore, as shown in FIG. 4, in the wrapping tape 30 being wound, there is an angle between the wound tape 30 and the tape 30 before being wound. In this regard, in FIG. 2 of the above-mentioned JP-A-2010-260344, it appears that there is no angle between the wound tape and the tape before being wound. In other words, in FIG. 2, the feed angle θ1 appears to be equal to the spiral angle θs. However, this differs from the reality of the conventional technology. In the conventional technology, the difference between the angle θs and the angle θ1 is small, for example, about 2 to 3°. Therefore, to the naked eye, it appears that there is no difference between the angle θs and the angle θ1. As a result, the drawings in the patent publications of the conventional technology are drawn as if there is no angle difference.

Even if the feed angle θ1 is 0°, the helical angle θs itself is usually small, at around 2 to 3°, so it was not thought that the difference between the helical angle θs and the feed angle θ1 would affect the quality of the tubular body. However, the inventors discovered that this small angle difference does affect the strength of the tubular body.

Figure 5 is an enlarged view showing the main part of Figure 3. The wrapping tape 30 is wound at a predetermined pitch Pt. The pitch Pt is measured along the axial direction of the intermediate winding body 18. The wrapping tape 30 is wound spirally with no gaps, with some of it overlapping. The two-dot chain line in Figure 5 indicates the winding start line. The winding start line is the position where the wrapping tape 30 starts to come into contact with the intermediate winding body 18 during the winding process.

In FIG. 5, the solid line indicates the state where the feed angle θ1 is equal to the spiral angle θs. In this case, the tension acting on the wrapping tape 30 is equalized in the width direction of the wrapping tape 30. The width direction is the direction along the winding start line R1.

In FIG. 5, the dashed line indicates a state in which the feed angle θ1 is smaller than the spiral angle θs. In this case, the tension acting on the wrapping tape 30 is not uniform across the width of the wrapping tape 30. In this case, the tension acting on the front side S1 of the winding direction D3 is greater than the tension acting on the rear side S2 of the winding direction D3.

In FIG. 5, the dashed line indicates a state in which the feed angle θ1 is greater than the spiral angle θs. In this case, the tension acting on the wrapping tape 30 is not uniform across the width of the wrapping tape 30. In this case, the tension acting on the front side S1 of the winding direction D3 is smaller than the tension acting on the rear side S2 of the winding direction D3.

The tension acting on the wrapping tape 30 tightens the intermediate winding 18. As described above, the tightening pressure of the tape 30 removes voids from the intermediate winding 18. Reducing the voids improves strength.

If the tension is uneven across the width of the tape 30, the clamping pressure will be uneven, resulting in areas where the clamping pressure is weak. In areas where the clamping pressure is weak, the percentage of remaining voids may be high. Areas with many voids reduce the strength of the shaft. By equalizing the tension, the number of areas with a high percentage of remaining voids decreases. As a result, the strength of the shaft increases.

The above-mentioned effect occurs regardless of whether the intermediate winding body 18 has a tapered portion. If the intermediate winding body 18 has a tapered portion, the feed angle θ1 may be further modified according to the taper angle of the tapered portion.

In the state shown by the dashed line in Figure 5, the feed angle θ1 is greater than 0°. Therefore, the unevenness of the tension in the width direction of the wrapping tape 30 is mitigated compared to when the feed angle θ1 is 0°. It was found that the strength can be improved by making the feed angle θ1 only slightly greater than 0°. It was also found that when the feed angle θ1 is greater than the helical angle θs, the effect of improving the strength can be obtained even if the difference (θ1 - θs) is relatively large. These effects are shown in the examples described below.

In the present application, the rate of change of the feed angle θ1 with respect to the helix angle θs is defined as X (%). This rate of change X is calculated by the following formula.
X=[(θ1/θs)-1]×100

It was found that when the rate of change X is within a predetermined range, the strength of the tubular body is sufficiently increased compared to when the feed angle θ1 is 0°. From the viewpoint of the strength of the tubular body, the rate of change X is preferably -60% or more, more preferably -40% or more, and more preferably -20% or more. From the viewpoint of the strength of the tubular body, the rate of change X is preferably 200% or less, more preferably 180% or less, and more preferably 160% or less.

By having a certain width for the preferred range of the rate of change X, errors in the feed angle θ1 and the spiral angle θs during mass production can be absorbed. This makes it possible to reduce the defect rate.

The preferred range of the rate of change X has a certain width, which improves compatibility with the shape of the intermediate winding body 18. When the intermediate winding body 18 has a taper, the feed angle θ1 gradually changes because the outer diameter of the intermediate winding body 18 changes depending on the axial position of the intermediate winding body 18. The rate of change X has a certain width, which allows it to accommodate changes in the feed angle θ1. In other words, by setting the wrapping machine 10 so that the rate of change X falls within the preferred range, it is possible to increase strength without changing the feed angle θ1 according to the axial position. It can also be adapted to cases where the taper angle of the intermediate winding body 18 changes depending on its axial position, or where the intermediate winding body 18 has tapered and non-tapered parts.

It has been found that when the feed angle θ1 is greater than 0°, the strength of the tubular body can be improved compared to when the feed angle θ1 is 0°. It has also been found that when the feed angle θ1 is greater than the helix angle θs, the strength of the tubular body can be improved compared to when the feed angle θ1 is smaller than the helix angle θs. Assuming that the absolute value of the difference (θ1-θs) is the same, the strength of the tubular body can be improved when the difference (θ1-θs) is positive compared to when the difference (θ1-θs) is negative. This tendency is enhanced when the absolute value of the difference (θ1-θs) is positive. When the difference (θ1-θs) is positive, the strength of the tubular body is less likely to decrease even if the absolute value of the difference (θ1-θs) increases. These effects are shown in the examples described below.

In this way, when the feed angle θ1 is greater than the helix angle θs, the strength is less likely to decrease even if the difference (θ1 - θs) changes. This makes it possible to absorb errors in the feed angle θ1 and the helix angle θs during mass production. In other words, by setting the median value of the feed angle θ1 to an appropriate value greater than the helix angle θs, the difference (θ1 - θs) can be kept within an appropriate range even if the feed angle θ1 and the helix angle θs vary. This makes it possible to reduce the defect rate.

Furthermore, the versatility when θ1>θs enhances compatibility with the shape of the intermediate winding body 18. When the intermediate winding body 18 has a taper, as described above, the feed angle θ1 changes depending on the axial position of the intermediate winding body 18. In this case, by setting the median value of the feed angle θ1 to an appropriate value greater than the helical angle θs, the difference (θ1-θs) can be kept within an appropriate range even if the feed angle θ1 varies. Even if the taper angle of the intermediate winding body 18 changes depending on its axial position or if the intermediate winding body 18 has tapered and non-tapered portions, the difference (θ1-θs) can be kept within an appropriate range.

From the viewpoint of the strength of the tubular body, the feed angle θ1 is preferably 1° or more, more preferably 1.5° or more, and more preferably 2° or more. From the viewpoint of the strength of the tubular body, the feed angle θ1 is preferably 20° or less, more preferably 17° or less, and more preferably 15° or less. As described above, in a tapered tubular body, the feed angle θ1 may change even if the settings of the wrapping machine 10 are constant. The feed angle θ1 may be a value measured at the center position in the axial direction of the tubular body.

From the viewpoint of the strength of the tubular body, the pitch Pt is preferably 1 mm or more, more preferably 1.5 mm or more, and more preferably 2 mm or more. From the viewpoint of the strength of the tubular body, the pitch Pt is preferably 10 mm or less, more preferably 8 mm or less, more preferably 6 mm or less, and more preferably 4 mm or less.

From the viewpoint of the strength of the tubular body, the helical angle θs is preferably 1° or more, more preferably 1.5° or more, and more preferably 2° or more. From the viewpoint of the strength of the tubular body, the helical angle θs is preferably 12° or less, more preferably 10° or less, more preferably 8° or less, and more preferably 5° or less.

[Sample 6]
A tubular body having the laminated structure shown in Fig. 1 was obtained by the above manufacturing process including the wrapping process. However, in order to accurately evaluate the strength, the polishing process and the painting process were not performed. The sheets constituting the tubular body were as shown in Table 1 below.

In the wrapping process, the above-mentioned wrapping machine 10 (Figure 3), which is capable of adjusting the feed angle θ1, was used. The wrapping tape used was Fujimori Kogyo Co., Ltd.'s product name "W16-15". This W16-15 is a hybrid tape in which a PET layer is sandwiched between PP layers. The tension was 4000 N, the pitch was 2.0 mm, and the feed angle θ1 was 2.0°. The specifications and evaluation results of sample 6 are shown in Table 2 below.

[Other samples]
Other samples were obtained in the same manner as Sample 6, except for the specifications shown in Tables 2 to 7. In the samples shown in Tables 2, 3 and 7, the pitch was set to 2.0 mm. In the samples shown in Tables 4 and 5, the pitch was set to 4.0 mm. In the sample shown in Table 6, the pitch was set to 10.0 mm. The specifications and evaluation results of these samples are shown in Tables 2 to 7 below. In the samples in Table 7, lapping was performed while changing the feed angle θ1 in the lapping process.

[Strength evaluation]
The three-point bending strength was measured according to the SG-type three-point bending strength test. This is a test for golf club shafts established by the Japan Product Safety Association. The strength was measured at the center point in the axial direction of the obtained tubular body. The measurement method (span 300 mm) at points A, B, and C in the SG-type three-point bending strength test was adopted. Tables 2, 3, and 7 show indexes with the strength of sample 2 set to 100. Tables 4 and 5 show indexes with the strength of sample 16 set to 100. Table 6 shows indexes with the strength of sample 30 set to 100.

As these evaluation results show, when the rate of change X is within a specified range, the strength is high. Also, when the feed angle θ1 is greater than 0°, the strength is high. Even if the feed angle θ1 does not match the helix angle θs, the strength is high as long as the difference (θ1-θs) is within a specified range.

When the absolute value of the difference (θ1 - θs) becomes larger, the strength can decrease. However, when the difference (θ1 - θs) is positive, the strength is high even if the absolute value of the difference (θ1 - θs) becomes relatively large. When the absolute value of the difference (θ1 - θs) is the same, the strength is higher when the difference (θ1 - θs) is positive than when the difference (θ1 - θs) is negative. This can be understood, for example, by comparing Sample 2 and Sample 9. On the other hand, when the feed angle θ1 is negative, the strength is reduced.

As mentioned above, the difference in strength is thought to be caused by uneven tension in the width direction of the wrapping tape. Even if the absolute value of the difference (θ1-θs) is the same, if the feed angle θ1 is greater than the helical angle θs, the tension imbalance is thought to be relatively small. Also, if the feed angle θ1 is negative, i.e., if the inclination direction of the feed angle θ1 is opposite to the inclination direction of the helical angle θs, the tension imbalance is thought to be large even if the absolute value of the difference (θ1-θs) is relatively small.

When the difference (θ1 - θs) is positive, high strength is obtained over a relatively wide range of feed angles θ1. From this perspective, it may be more advantageous to make the difference (θ1 - θs) positive than to make the feed angle θ1 equal to the helix angle θs. In mass production, tolerances may occur in the feed angle θ1 or the helix angle θs. By making the feed angle θ1 larger than the helix angle θs, it is possible to reduce the variation in strength between individual pieces, even if this tolerance occurs. This makes it possible to mass-produce tubular bodies of consistent quality.

The following notes are part of the invention contained in this disclosure.
[Appendix 1]
A tubular body formed of fiber reinforced resin,
The wrapping tape is wound spirally at a spiral angle of θs and then heated and hardened.
The feed angle θ1 is greater than 0°,
A tubular body in which a rate of change X of the feed angle θ1 with respect to the helix angle θs is −60% or more and 200% or less.
Here, the rate of change X (%) is calculated by the following formula.
X=[(θ1/θs)-1]×100
[Appendix 2]
2. The tubular body according to claim 1, wherein the feed angle θ1 is greater than the helix angle θs.
[Appendix 3]
A tubular body formed of fiber reinforced resin,
The wrapping tape is wound in a spiral shape at a predetermined spiral angle θs and then heated and cured.
A tubular body, wherein the feed angle θ1 is greater than the helix angle θs.
[Appendix 4]
4. The tubular body according to any one of claims 1 to 3, which is a golf club shaft.
[Appendix 5]
a winding step of winding a fiber reinforced resin material around a mandrel to obtain an intermediate wound body;
a wrapping step of spirally winding the wrapping tape fed at a feed angle θ1 around the intermediate winding body at a spiral angle θs;
a curing step of heating the intermediate roll around which the wrapping tape is wound;
removing the wrapping tape after the curing step;
Including,
The feed angle θ1 is greater than 0°,
A method for manufacturing a tubular body, wherein a rate of change X of the feed angle θ1 with respect to the helix angle θs is −60% or more and 200% or less.
Here, the rate of change X (%) is calculated by the following formula.
X=[(θ1/θs)-1]×100

2...Golf club shaft (tubular body)
4: Mandrel 6: Golf club shaft (tubular body)
8: Mandrel 10: Wrapping machine 12: Tape feed section 14: Rail 16: Rotation holding section 18: Intermediate winding body 20: Conventional wrapping machine 30: Wrapping tape θ1: Feed angle θs: Helix angle Pt: Pitch

Claims (8)

A tubular body formed of fiber reinforced resin,
The wrapping tape is wound around a mandrel to produce a fiber-reinforced resin material, and the intermediate winding body is rotated. The wrapping tape is wound around the intermediate winding body at a spiral angle of θs and heated to harden the intermediate winding body .
The feed angle θ1 is greater than 0°,
A rate of change X of the feed angle θ1 with respect to the helical angle θs is −60% or more and 200% or less,
A tubular body , wherein the feed angle θ1 is greater than the helix angle θs .
Here, the rate of change X (%) is calculated by the following formula.
X=[(θ1/θs)-1]×100 A tubular body formed of fiber reinforced resin,
The wrapping tape is wound around a mandrel at a predetermined feed angle θ1, and the intermediate winding body is rotated. The wrapping tape is wound around the intermediate winding body at a predetermined helical angle θs, and the intermediate winding body is heated and cured.
A tubular body, wherein the feed angle θ1 is greater than the helix angle θs. 3. The tubular body according to claim 1, which is a golf club shaft. 2. The tubular body according to claim 1, wherein the rate of change X is 6% or more and 198% or less. 5. The tubular body according to claim 1, wherein the difference (θ1-θs) is 0.3° or more and 12.7° or less. 6. The tubular body according to claim 1, wherein the pitch of the spirally wound wrapping tape is 1 mm or more and 10 mm or less. The tubular body according to claim 1 , wherein the helix angle θs is equal to or greater than 1° and equal to or less than 12°. a winding step of winding a fiber reinforced resin material around a mandrel to obtain an intermediate wound body;
a wrapping step of spirally winding the wrapping tape fed at a feed angle θ1 around the intermediate winding body at a spiral angle θs while rotating the intermediate winding body ;
a curing step of heating the intermediate roll around which the wrapping tape is wound;
removing the wrapping tape after the curing step;
Including,
The feed angle θ1 is greater than 0°,
A rate of change X of the feed angle θ1 with respect to the helical angle θs is −60% or more and 200% or less,
A method for manufacturing a tubular body , wherein the feed angle θ1 is greater than the helix angle θs .
Here, the rate of change X (%) is calculated by the following formula.
X=[(θ1/θs)-1]×100

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