JP2010063778A - Shaft for golf club and method for manufacturing the same - Google Patents

Abstract

Provided is a golf club shaft that is lightweight and has sufficient torsional rigidity and bending rigidity, and a method of manufacturing the same.
A golf club shaft of the present invention has a thickness of 0 containing reinforcing fibers oriented at an orientation angle of + α ° and −α ° (where 20 ° ≦ α ° ≦ 70 °) with respect to the axial direction. 3 layers of bias layers 11, 12, 13 made of fiber reinforced resin of 6 mm or less and straight layers 21, 22, 23 made of fiber reinforced resin containing reinforcing fibers oriented substantially parallel to the axial direction. The bias layers 11, 12, 13 and the straight layers 21, 22, 23 are alternately arranged, the innermost layer is the bias layer 11, and any one of the bias layers other than the innermost bias layer 11 is provided. 13 is formed over a length of 20 to 40% of the entire shaft length from the large diameter end.
[Selection] Figure 3

Description

  The present invention relates to a golf club shaft made of fiber reinforced resin and a method of manufacturing the same.

As a golf club shaft formed of a fiber reinforced resin such as a carbon fiber reinforced resin, the orientation directions of the reinforced fibers are + α ° and −α ° (20 ° ≦ α ° ≦ 70 °) with respect to the shaft axis direction. A layer in which a bias layer formed by laminating and winding each of the above layers and a straight layer in which the orientation direction of reinforcing fibers is parallel to the shaft axial direction is known. In such a golf club shaft, it has been proposed to further provide a bias layer on the outside of the straight layer in order to suppress the torsion of the shaft at the time of hitting the ball and make the launch direction accurate. (See Patent Documents 1 to 4).
However, even the golf club shafts described in Patent Documents 1 to 4 sometimes have insufficient torsional rigidity.
In order to further increase the torsional rigidity, for example, it is conceivable to apply a method in which a bias layer is further provided over the entire shaft so that the number of bias layers is three (for example, see FIG. 8 of Patent Document 5).
JP-A-62-33872 JP-A-9-327536 JP-A-11-197277 JP-A-8-308969 Japanese Utility Model Publication No. 4-92270

However, the golf club shaft described in Patent Document 5 has a problem that the torsional rigidity is increased but the shaft becomes heavy.
In order to increase the torsional rigidity while keeping the weight of the shaft constant, it is conceivable to decrease the ratio of the straight layer to the shaft and increase the ratio of the bias layer, but in that case, sufficient bending rigidity can be obtained. become unable.
In order to increase the torsional rigidity, it is conceivable to use an ultrahigh elastic carbon fiber excellent in specific elasticity as the reinforcing fiber for the bias layer, but the ultrahigh elastic carbon fiber has a low elongation at break and a high compressive strength. Therefore, the mechanical strength of the shaft such as impact strength may be insufficient.
SUMMARY OF THE INVENTION An object of the present invention is to provide a golf club shaft that is lightweight, has sufficient torsional rigidity and bending rigidity, and has excellent feel when used as a golf club, and a method for manufacturing the same.

  The present inventors examined a method for increasing the torsional rigidity without causing an increase in weight. As a result, it has been found that even if the bias layer is not formed over the entire shaft, the torsional rigidity of the shaft can be sufficiently improved if it is formed on the large diameter end side. And based on the knowledge, it examined in order to solve the subject of this invention, and invented the following shafts for golf clubs, and its manufacturing method.

The present invention has the following configuration.
[1] Bias made of fiber reinforced resin with a thickness of 0.6 mm or less containing reinforcing fibers oriented at + α ° and −α ° (where 20 ° ≦ α ° ≦ 70 °) with respect to the axial direction Each having three or more layers and straight layers made of fiber reinforced resin containing reinforcing fibers oriented substantially parallel to the axial direction,
Bias layer and straight layer are arranged alternately,
The innermost layer is the bias layer,
Any one of the bias layers other than the innermost bias layer is a golf club shaft formed from the large diameter end to a length of 20 to 40% of the entire shaft length.
[2] A method for producing a golf club shaft according to [1] using a prepreg, comprising:
A thickness of 0.16 mm obtained by bonding two prepregs containing reinforcing fibers oriented at + α ° and −α ° (where 20 ° ≦ α ° ≦ 70 °) with respect to the axial direction of the shaft. A golf club shaft manufacturing method comprising a step of winding three or more of the following bias layer forming bonded prepregs and three or more straight layer forming prepregs containing reinforcing fibers oriented substantially parallel to the axial direction of the shaft .

The shaft for golf clubs of the present invention is lightweight, has sufficient torsional rigidity and bending rigidity, and is excellent in feel when used as a golf club.
According to the golf club shaft manufacturing method of the present invention, it is possible to manufacture a golf club shaft that is lightweight, has sufficient torsional rigidity and bending rigidity, and is excellent in feel when used as a golf club.

<Golf club shaft>
An embodiment of a golf club shaft (hereinafter abbreviated as a shaft) of the present invention will be described.
1 to 4 show a shaft according to this embodiment. In the shaft 10 of the present embodiment, the innermost layer is a bias layer, and the bias layer and the straight layer are alternately arranged in three layers toward the outer side. That is, the first bias layer 11, the first straight layer 21, the second bias layer 12, the second straight layer 22, the third bias layer 13, and the third straight layer 23 are concentrically formed from the inside. Have in order.
When there are three or more bias layers and straight layers, torsional rigidity and bending rigidity are sufficient. Since the innermost layer is a bias layer, the bending rigidity is sufficient.

  Further, in the present embodiment example, the portion of the surface of the third straight layer 23 on the small-diameter end 10a side has a reinforcing layer 24, and the surface of the reinforcing layer 24 has a predetermined outer surface after finish polishing. It has an outer diameter adjusting layer 25 for ensuring the diameter.

Each of the bias layers 11, 12, and 13 is a layer made of fiber reinforced resin, and a reinforcing fiber oriented at an orientation angle of + α ° with respect to the axial direction of the shaft 10 and −α ° with respect to the axial direction of the shaft 10. And reinforcing fibers oriented at an orientation angle of. Here, α ° is 20 ° to 70 °. Usually, the absolute values of the positive orientation angle and the negative orientation angle are the same.
When α ° is 20 ° or more, the torsional rigidity is sufficiently high, and when α ° is 70 ° or less, the bending rigidity is sufficiently high.

Each bias layer 11, 12, 13 has a thickness of 0.6 mm or less, preferably 0.45 mm or less. Since the thickness of each bias layer 11, 12, 13 is 0.60 mm or less, the shaft 10 becomes light.
Also, the thickness of each bias layer 11, 12, 13 should be 0.10 mm or more in order to obtain sufficient torsional rigidity.

The third bias layer 13 in this embodiment is formed from the large diameter end 10b of the shaft 10 to a length of 20 to 40% of the entire length of the shaft 10. Hereinafter, a bias layer formed from the large diameter end 10b of the shaft 10 to 20 to 40% of the entire length of the shaft 10 is referred to as a short bias layer.
By forming the third bias layer 13 from the large diameter end 10b of the shaft 10 to a length of 20% or more of the entire length of the shaft 10, the torsional rigidity can be increased. Further, since the third bias layer 13 is formed from the large diameter end 10b of the shaft 10 to a length of 40% or less of the entire length of the shaft 10, an increase in the weight of the shaft 10 can be suppressed.

For the third bias layer 13, which is a short bias layer, the orientation angles of the reinforcing fibers with respect to the axial direction of the shaft 10 are + α ° and −α ° (however, in the third bias layer 13, 20 ° ≦ α ° ≦ 40 It is preferable that If α ° of the reinforcing fiber of the third bias layer 13 is 20 ° or more, torsional rigidity can be further improved, and if it is 40 ° or less, sufficiently high bending rigidity can be obtained.
The first bias layer 11 and the second bias layer 12 in the present embodiment are disposed over the entire longitudinal direction of the shaft 10.

Each of the straight layers 21, 22, and 23 is a fiber reinforced resin layer and contains reinforcing fibers oriented substantially parallel to the axial direction of the shaft 10. Since the reinforcing fibers are oriented substantially parallel to the axial direction of the shaft 10, the bending rigidity can be increased.
The thickness of each straight layer 21, 22, 23 is preferably 0.06 to 0.25 mm, and more preferably 0.08 to 0.15 mm. If the thickness of each straight layer 21, 22, 23 is 0.06 mm or more, the bending rigidity can be further improved, and if it is 0.25 mm or less, the shaft 10 can be lightened sufficiently.
The first straight layer 21, the second straight layer 22, and the third straight layer 23 are formed over the entire length of the shaft 10.

Examples of the resin component constituting the bias layers 11, 12, 13 and the straight layers 21, 22, 23 include an epoxy resin, an unsaturated polyester resin, an acrylic resin, a vinyl ester resin, a phenol resin, and a benzoxazine resin. . Among these, an epoxy resin is preferable because the strength after curing can be increased.
Examples of the reinforcing fibers constituting the bias layers 11, 12, 13 and the straight layers 21, 22, 23 include carbon fiber, glass fiber, aramid fiber, high-strength polyester fiber, boron fiber, alumina fiber, silicon nitride fiber, and nylon. Examples include fibers. Among these, carbon fiber is preferable because it is excellent in specific strength and specific elasticity.
Moreover, when using a carbon fiber as a reinforced fiber which comprises the bias layers 11, 12, and 13, it is preferable to use the carbon fiber whose tensile elastic modulus is 280-500 GPa. Here, the tensile modulus is a value measured according to JIS R 7608.
If the tensile modulus of the carbon fiber is 280 GPa or more, the torsional rigidity can be further improved, and if it is 500 GPa or less, the impact strength when the shaft is made can be kept high.
In addition, the fiber volume content in the bias layers 11, 12, and 13 is preferably 65% or more because the torsional rigidity can be further increased. In addition, the fiber volume content in the bias layers 11, 12, and 13 is preferably 73% or less because a certain amount of resin is required to ensure sufficient adhesion between the matrix resin and the reinforcing fibers. .

  The reinforcing layer 24 and the outer diameter adjusting layer 25 are configured in the same manner as the straight layers 21, 22, and 23 except that they are dimensioned to perform the intended function.

In the shaft 10 described above, the torsional rigidity can be improved by the third bias layer 13 formed from the large-diameter end 10b to a length of 20 to 40% of the entire length of the shaft. Moreover, since the third bias layer 13 is 20 to 40% of the entire length of the shaft, the weight of the shaft 10 can be reduced.
In addition, since the bias layer and the straight layer are each provided in three layers, the torsional rigidity and the bending rigidity can be sufficiently increased. In particular, since the innermost layer is the bias layer 11 and each bias layer 11, 12, 13 contains reinforcing fibers having an α ° of 70 ° or less, the bending rigidity is particularly high.
Furthermore, since the bias layers 11, 12, 13 and the straight layers 21, 22, 23 are alternately arranged, the balance between torsional rigidity and bending rigidity can be improved.

<Manufacturing method of shaft>
Next, an embodiment of a method for manufacturing the shaft 10 will be described.
The manufacturing method of the shaft 10 of the present embodiment is a method of obtaining the shaft 10 by winding a prepreg around a mandrel 30 having a portion 31 whose diameter gradually increases as shown in FIG.
Specifically, first, a first bias layer forming bonded prepreg 11a, a first straight layer forming prepreg 21a, and a second bias layer forming bonded prepreg as shown in FIG. 12a, the second straight layer forming prepreg 22a, the third bias layer forming prepreg 13a, and the third straight layer forming prepreg 23a are wound one by one in order from the inside. Here, when the bias layer forming bonded prepregs 11a, 12a, and 13a and the straight layer forming prepregs 21a, 22a, and 23a are not alternately disposed, the balance between the torsional rigidity and the bending rigidity of the obtained shaft 10 is impaired. Sometimes.
Next, the reinforcing layer forming prepreg 24a is wound around the portion of the surface of the third straight layer forming prepreg 23a on the narrow diameter end side, and the outer diameter adjusting layer forming prepreg 25a is further wound around the surface of the reinforcing layer forming prepreg 24a. Is wound to obtain an uncured molded product.
Next, the uncured molded product is heated using a heating furnace or the like to cure the resin component, thereby obtaining the shaft 10.

Laminated prepregs 11a, 12a, 13a for forming a bias layer used in the above production method contain reinforcing fibers oriented at + α ° with respect to the axial direction of the shaft 10 and reinforcing fibers oriented at −α °. It is a prepreg. Here, α ° is 20 ° to 70 °.
When α ° is 20 ° or more, the torsional rigidity of the obtained shaft 10 is sufficiently high, and when α ° is 70 ° or less, the bending rigidity of the obtained shaft 10 can be sufficiently increased.
In order to set the orientation angle of the reinforcing fiber to the axial direction of the shaft 10 to + α ° and −α ° (20 ° ≦ α ° ≦ 70 °), the orientation angle of the reinforcing fiber to the axial direction of the mandrel 30 is set to + α °. And −α ° (where 20 ° ≦ α ° ≦ 70 °).

The third laminated prepreg 13a for forming a bias layer in this embodiment is a prepreg for forming a short bias layer, that is, from the large diameter end 10b of the shaft 10 to a length of 20 to 40% of the total length of the shaft. A prepreg for forming a bias layer. The third bias layer forming prepreg 13a forms a bias layer from the large-diameter end 10b of the shaft 10 to 20% of the total length of the shaft, whereby the torsional rigidity of the obtained shaft 10 can be increased. In addition, the third bias layer-forming bonded prepreg 13a forms a bias layer from the large-diameter end 10b of the shaft 10 to a length of 40% or less of the entire shaft length, so that the bending rigidity can be sufficiently increased. .
Α ° of the reinforcing fiber in the third prepreg 13a for forming the bias layer is preferably 20 ° to 40 °.

Each of the bias layer forming bonded prepregs 11a, 12a, and 13a has a thickness of 0.16 mm or less, preferably 0.12 mm or less. When the thickness of each bias layer forming bonded prepreg 11a, 12a, 13a exceeds 0.16 mm, the obtained shaft 10 tends to be heavy. In addition, when the number of turns is not an integer, the shape of the cross section perpendicular to the longitudinal direction of the shaft 10 is likely to be elliptical, and the hardness is distributed in the circumferential direction, which may impair the hit feeling.
Further, the thickness of each bias layer forming bonded prepreg 11a, 12a, 13a is preferably 0.03 mm or more, and 0.05 mm or more in order to sufficiently improve the torsional rigidity of the obtained shaft 10. It is more preferable that

  The straight layer forming prepregs 21 a, 22 a, and 23 a contain reinforcing fibers oriented substantially parallel to the axial direction of the obtained shaft 10. Since the reinforcing fibers are oriented substantially parallel to the axial direction of the shaft 10, the bending rigidity of the obtained shaft 10 can be increased.

The bias layer forming bonded prepregs 11a, 12a, and 13a and the straight layer forming prepregs 21a, 22a, and 23a are unidirectional prepregs in which reinforcing fibers are aligned in one direction, and the shape of the shaft 10 is formed. It is obtained by cutting so that the reinforcing fibers are oriented in a predetermined direction, and combining a plurality as necessary. For example, for the bias layer forming bonded prepregs 11a, 12a, and 13a, a prepreg containing reinforcing fibers oriented at an orientation angle within a range of + α ° with respect to the axial direction of the shaft 10 and within a range of −α ° It is obtained by combining with a prepreg containing reinforcing fibers oriented at an orientation angle of. Here, α ° is 20 ° to 70 °.
Usually, the bias layer forming bonded prepregs 11a and 12a and the straight layer forming prepregs 21a, 22a, and 23a have a small diameter so that the shaft 10 has a circular cross section even if it has a portion that expands in diameter. The width on the side that becomes the end 10a is narrow.

  In the above manufacturing method, if necessary, finish polishing may be performed after the resin component is cured. In the manufacturing method according to the present embodiment, the third straight layer 23 is formed on the surface of the third bias layer 13, and therefore the third bias layer 13 is not removed even if polishing is performed. .

In the manufacturing method described above, the second straight layer forming prepreg 22a and the third straight layer forming prepreg 23a are formed over a length of 20 to 40% of the entire shaft length from the large diameter end 10b. Since the third bias layer forming bonded prepreg 13a is arranged, the torsional rigidity of the shaft 10 obtained is sufficiently high. Moreover, since the third prepreg 13a for forming the bias layer is 20 to 40% of the entire length of the shaft, the obtained shaft 10 can be reduced in weight.
Further, since three each of the bias layer forming bonded prepreg and the straight layer forming prepreg are used, the torsional rigidity and bending rigidity of the obtained shaft 10 can be sufficiently increased. In particular, since the bias layer forming prepreg 11a is used in the innermost layer, the bias layer forming bonded prepregs 11a, 12a, and 13a contain reinforcing fibers having an orientation angle of 70 ° or less and reinforcing fibers having an orientation angle of −70 ° or more. The bending rigidity of the obtained shaft 10 can be particularly increased.
Furthermore, since the bias layer forming bonded prepregs 11a, 12a, and 13a and the straight layer forming prepregs 21a, 22a, and 23a are alternately arranged, the balance between torsional rigidity and bending rigidity can be improved.

Note that the present invention is not limited to the above embodiment. For example, the bias layer and the straight layer need not be three layers each, and may be four layers or more. Even when there are four or more layers, the innermost layer is used as a bias layer.
The short bias layer may be the second bias layer instead of the third bias layer, or both the second bias layer and the third bias layer. When there are four or more bias layers, at least one of the bias layers other than the first bias layer may be a short bias layer.
Further, the shaft of the present invention may not have one or both of the reinforcing layer 24 and the outer diameter adjusting layer 25.

Hereinafter, the present invention will be described in more detail with reference to examples.
Table 1 shows the prepregs used in the following examples.

Example 1
The outer diameter of the narrow end is 4.40 mm, the outer diameter from the narrow end to the position of 1100 mm gradually increases with a taper degree of 7.91 / 1000, and the outer diameter at the position of 1100 mm from the narrow end is The mandrel 30 having a constant outer diameter of 13.10 mm was used at a position 1100 mm from the narrow end portion to a position 1500 mm from the narrow end portion.
As shown in FIG. 5, first, for forming a trapezoidal first bias layer composed of two prepregs A in a range of 110 mm from the narrow end of the mandrel 30 to 1300 mm from the narrow end. Laminated prepreg 11a (one prepreg obtained by laminating a prepreg containing reinforcing fibers with an orientation angle of + 45 ° and a prepreg containing reinforcing fibers with an orientation angle of -45 °), a trapezoidal first prepreg B 1 straight layer forming prepreg 21a (a prepreg containing reinforcing fibers with an orientation angle of 0 °), a trapezoidal second bias layer forming prepreg 12a composed of two prepregs A (reinforced with an orientation angle of + 45 °) One prepreg obtained by laminating a prepreg containing fibers and a prepreg containing reinforcing fibers having an orientation angle of −45 °), prepreg Trapezoidal second straight layer forming prepreg 22a (prepreg containing reinforcing fibers with an orientation angle of 0 °), and third bias layer forming prepreg 13a (orientation) comprising two prepregs A. For forming a trapezoidal third straight layer comprising a prepreg containing a prepreg containing reinforcing fibers having an angle of + 30 ° and a prepreg containing reinforcing fibers having an orientation angle of -30 °) and prepreg D A prepreg 23a (a prepreg containing reinforcing fibers having an orientation angle of 0 °) was wound in order. Here, in the third laminated prepreg 13a for forming the bias layer, the bias layer is formed in the range from the large diameter end to 30% of the total length of the shaft.
Next, a reinforcing layer forming prepreg 24a (prepreg containing reinforcing fibers with an orientation angle of 0 °) made of prepreg E was wound around a portion on the small diameter end side of the surface of the third straight layer forming prepreg 23a. Further, an outer diameter adjusting layer forming prepreg 25a made of prepreg E (prepreg containing reinforcing fibers with an orientation angle of 0 °) was wound around the surface of the reinforcing layer forming prepreg 24a to obtain an uncured molded product.
Next, a polypropylene tape having a width of 20 mm and a thickness of 0.03 mm is wound at a pitch of 1.5 mm to fix an uncured molded product, and then heated at 145 ° C. for 2 hours using a heating furnace to cure the resin component. I let you. Thereafter, the polypropylene tape was removed, both ends were cut by 11 mm to a total length of 1168 mm, and the surface was polished to obtain the shaft 10.

About the obtained shaft, the twist angle (the smaller the twist angle, the greater the torsional rigidity), the bending rigidity, and the hit feeling were evaluated as follows. The evaluation results are shown in Table 2.
[Twist angle]
As shown in FIG. 7, the first chuck (width 32 mm) 51 is fixed from the position of 1035 mm from the shaft small diameter end to the position of 1067 mm from the shaft small diameter end, and the shaft small diameter end to the small diameter end. The second chuck (width 50 mm) 52 was fixed up to a position of 50 mm from the part. A weight was attached to the second chuck 52, and the twist angle when a torque of 13.8 kgf · cm was applied was measured. When the twist angle is in the range of 2 ° to 3 °, the torsional rigidity is sufficiently high.
[Bending rigidity]
The bending stiffness EI is a fulcrum (radius of the supporting jig installed at the fulcrum at the position of 150 mm on the large diameter end side and 150 mm on the small diameter end side centering on the measurement point (position 525 mm from the small diameter end): 10 mm), and the load applied to the measurement point (radius of the load indenter jig installed at the measurement point: 75 mm) is increased at a test speed of 5 mm / min, and the shaft when a load of 10 kgf and 20 kgf is applied. The deflection amounts δ ₁₀ (mm) and δ ₂₀ (mm) of the film were measured and determined by the following equations.
EI = (ΔP / L ³ ) / (48 · Δδ)
EI: Flexural rigidity (kgf · mm ² )
ΔP: 20 kgf-10 kgf = 10 kgf
L: Distance between fulcrums (mm)
Δδ: δ ₂₀ −δ ₁₀ (mm)
[Hit feeling]
A commercially available titanium driver club head having a weight of 200 g, a volume of 383 cc, and a loft angle of 9.5 ° and a commercially available grip having a weight of 52 g were attached to the shaft so that the club length was 45 inches. The hit feeling when hitting the ball with the head attached was evaluated.

  As shown in FIG. 6, a shaft was obtained in the same manner as in Example except that the third bias layer was formed over the entire length of the shaft using the third laminated prepreg for forming the bias layer. The obtained shaft was evaluated in the same manner as in the example. The evaluation results are shown in Table 2.

In the examples, the torsional rigidity and bending rigidity of the shaft could be sufficiently increased without causing an increase in weight, and the hit feeling of the golf club using the obtained shaft was good.
On the other hand, in the comparative example, although the torsional rigidity and the bending rigidity could be increased, the weight was increased.

It is a side view which shows one embodiment of the shaft of this invention. It is an enlarged view of the A-A 'cross section of FIG. It is an enlarged view of the B-B 'cross section of FIG. It is an enlarged view of the C-C 'cross section of FIG. 1 is a view showing a mandrel and a prepreg used in Example 1. FIG. It is a figure which shows the mandrel and prepreg which are used in the comparative example 1. It is a figure which shows the measuring method of a twist angle.

Explanation of symbols

10 Shaft (Golf Club Shaft)
DESCRIPTION OF SYMBOLS 11 1st bias layer 11a 1st bias layer formation bonding prepreg 12 2nd bias layer 12a 2nd bias layer formation bonding prepreg 13 3rd bias layer 13a 3rd bias layer formation bonding Prepreg 21 First straight layer 21a First straight layer forming prepreg 22 Second straight layer 22a Second straight layer forming prepreg 23 Third straight layer 23a Third straight layer forming prepreg 24 Reinforcing layer 24a Reinforcing layer forming prepreg 25 Outer diameter adjusting layer 25a Outer diameter adjusting layer forming prepreg 30 Mandrel

Claims (2)

A bias layer made of a fiber reinforced resin having a thickness of 0.6 mm or less containing reinforcing fibers oriented at an orientation angle of + α ° and −α ° (where 20 ° ≦ α ° ≦ 70 °) with respect to the axial direction; Three or more straight layers made of fiber-reinforced resin containing reinforcing fibers oriented substantially parallel to the axial direction,
Bias layer and straight layer are arranged alternately,
The innermost layer is the bias layer,
Any one of the bias layers other than the innermost bias layer is a golf club shaft formed from the large diameter end to a length of 20 to 40% of the entire shaft length. A golf club shaft manufacturing method for obtaining a golf club shaft according to claim 1 using a prepreg,
A thickness of 0.16 mm obtained by bonding two prepregs containing reinforcing fibers oriented at + α ° and −α ° (where 20 ° ≦ α ° ≦ 70 °) with respect to the axial direction of the shaft. A golf club shaft manufacturing method comprising a step of winding three or more of the following bias layer forming bonded prepregs and three or more straight layer forming prepregs containing reinforcing fibers oriented substantially parallel to the axial direction of the shaft .

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