JP2009036402A - Arrow - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arrow, quickly damping flexure and vibration during flying to accurately shoot at a target. <P>SOLUTION: This arrow 10 includes a shaft 12 formed by winding fiber reinforced prepregs 24a, 24b, 26a, 26b to form a tubular structure, wherein the shaft 12 includes an inner body layer 24 having a first tilting fiber layer where a reinforced fiber 23 is oriented in the tilting direction with respect to the axial length direction and a second tilting fiber layer oriented in the direction intersecting the first tilting fiber layer; an outer body layer 26 having an axial length direction fiber layer in which a reinforced fiber 25 is oriented in the axial length direction on the inner body layer 24; and a facing layer 30 having a fiber layer where at least a part of a reinforced fiber 31 is oriented in the tilting direction to the axial length direction on the outer body layer 26. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an arrow that shoots using a bow, and more particularly to an arrow formed by winding a fiber-reinforced prepreg in which a shaft impregnates a reinforcing resin with a synthetic resin.

  In general, arrows used in Japanese bows are required to have characteristics such as rigidity, stickiness, and deflection according to the strength of the bow used and the skill of the archer. It is required that each arrow forming four or six sets including a spare has uniform performance and quality.

  In order to form the characteristics of these multiple arrows evenly, the bamboo tension which formed the appearance like a bamboo arrow by processing and sticking natural yatake on the outer surface of geralumin or carbon pipe An arrow has been developed (see, for example, Patent Document 1).

Moreover, in order to form an arrow having not only the appearance but also the strength and rigidity equal properties, a fiber reinforced prepreg impregnated with a synthetic resin is wound around a reinforcing fiber such as carbon fiber, and a woven fabric or a reinforcing fiber is wound. A shaft having an intersecting inner layer and an outer layer in which axial length direction fibers are arranged has been developed (see, for example, Patent Document 2).
JP 2001-108400 A JP-A-2005-273987

  According to the arrow formed by winding a fiber reinforced prepreg, the shaft is formed with high strength and rigidity, and its performance and quality can be made uniform, which is difficult with conventional arrows such as bamboo tension arrows. However, usually when an arrow is released, a large push is suddenly pushed forward from this string via an arrowhead locked to the bowstring. Under pressure, this causes the shaft to bend sideways. The bending of the shaft causes bending in the opposite direction due to the reaction, and finally converges on the vibration due to the bending phenomenon, and finally flies toward the target.

  When such shaft deflection is large, the momentum of the arrow is reduced and the flight posture is made unstable, which is an obstacle to projecting an accurate position with respect to the target.

  In the case of an arrow in which a shaft is formed by winding a fiber-reinforced prepreg, the elasticity of the axial length fiber greatly affects this bending. Therefore, the higher the elasticity of the axial length fiber, the higher the rigidity and the bending. That is, it can withstand bending and therefore reduce bending.

  However, the rigidity and deflection required for the arrow vary depending on the skill of the archer and the strength of the bow used. For this reason, the shaft is usually required to have a certain degree of bending characteristics as well as rigidity. Therefore, it is necessary to provide the mutually opposite characteristics of rigidity and bending.

  The present invention has been made based on such circumstances, and it is an object of the present invention to provide an arrow that can quickly dampen flexure and vibration during flight and can accurately shoot the target.

  In order to achieve the above object, according to the present invention, there is provided a shaft formed by winding a fiber reinforced prepreg into a tubular structure, and the shaft is a first in which reinforcing fibers are oriented in an inclined direction with respect to the axial length direction. An inner body layer having an inclined fiber layer and a second inclined fiber layer oriented in a direction crossing the first inclined fiber layer, and the reinforcing fibers are oriented in the axial length direction on the inner body layer. An arrow provided with an outer body layer having an axial length direction fiber layer and an outer skin layer having a fiber layer in which at least a part of the reinforcing fiber is oriented in an inclined direction with respect to the axial length direction on the outer body layer is provided. Is done.

  Further, it comprises a shaft in which a fiber reinforced prepreg is wound to form a main body layer, and this shaft has, in at least a part of the main body layer, an axial length direction fiber layer in which reinforcing fibers are oriented in the axial length direction, On this main body layer, there is a skin layer formed by winding a fiber reinforced prepreg in which reinforcing fibers are oriented in at least two directions that are inclined with respect to the axial length direction and intersect each other, and this skin layer is formed. The reinforcing fiber of the fiber-reinforced prepreg is provided with an arrow formed of an organic fiber having a specific gravity smaller than that of the reinforcing fiber forming the axial length direction fiber layer of the main body layer and having a high vibration damping property.

  The skin layer is preferably formed of a fiber-reinforced prepreg in which a reinforcing fiber forms a woven fabric made of a triaxial or tetraaxial fabric.

  In addition, a shaft having a main body layer formed by winding a fiber reinforced prepreg is provided, and this shaft has a specific gravity on the outer side in the radial direction from the inner side in the radial direction with a central cylindrical surface passing through the center position in the thickness direction of the main body layer as a boundary. A small arrow is provided.

  And a shaft having a body layer formed by winding a fiber reinforced prepreg and a skin layer formed by winding the fiber reinforced prepreg on the outside of the body layer, and the body layer has an axial length of the reinforcing fiber. The fiber-reinforced prepreg having an axial length direction fiber layer oriented in the direction and forming the skin layer is oriented in an inclination direction of 30 degrees opposite to each other with respect to the axial length direction and intersects with each other. And an arrow that forms a triaxial woven fabric having circumferential fibers intersecting with these inclined fibers at positions separated from the intersections of these inclined fibers in the axial length direction.

  According to the arrow of the present invention, the bending stress formed when the shaft is bent laterally by the action of the pressing force from the bow chord is inclined so that the reinforcing fibers arranged in the inner body layer and the outer body layer intersect each other. Is distributed along the direction and the axial length direction, and further distributed in the inclined direction by the reinforcing fibers in the skin layer, which can improve the torsional rigidity and bending rigidity, and the sticky shaft bends when the arrow is released And the vibration caused by the bending is quickly attenuated during the flight, the posture is stabilized, and the target can be accurately shot.

  Also, the reinforcing fiber of the fiber reinforced prepreg that forms the skin layer of the shaft is formed of organic fibers having a specific gravity smaller than that of the reinforcing fiber that forms the axial length direction fiber layer of the main body layer and high vibration damping properties. The reinforcing fiber in the skin layer distributes bending stress along the direction of the reinforcing fiber, and the small specific gravity and vibration damping of the reinforcing fiber make shaft flexing or vibration efficient during flight. It attenuates well and stabilizes the posture, so that the target can be shot accurately.

  When the reinforcing fiber of the skin layer forms a woven fabric composed of a triaxial or tetraaxial woven fabric, the reinforcing fiber extending in the triaxial or tetraaxial direction within the same layer or at the same level in the skin layer is used as the shaft. The bending stress due to the bending of the reinforcing fiber can be evenly distributed along the inclination directions of the reinforcing fibers intersecting each other, and further, the stress can be distributed in the circumferential direction, so that the axial stress component is reduced. As a result, the bending when the arrow is released and the vibration caused by the bending are quickly attenuated during the flight, the posture is stabilized, and the target can be accurately shot.

  In addition, when the shaft main body layer formed by winding the fiber reinforced prepreg is an arrow in which the specific gravity on the outer side in the radial direction is smaller than the inner side in the radial direction with the central cylindrical surface passing through the center position in the thickness direction as a boundary Can concentrate the specific gravity of the main body layer of the shaft closer to the shaft core, and the shaft bends due to the combined force of not only the axial pressing force but also the deflected pressing force and rotation. Even if it behaves in a complex manner, such as vibration or rotation, it is possible to effectively attenuate these flexures and vibrations to stabilize the posture and to shoot accurately with respect to the target.

  Further, the fiber-reinforced prepreg forming the skin layer is oriented in the inclined direction of 30 degrees in the opposite direction to the axial length direction and intersects with each other, and the intersection of these inclined direction fibers in the axial length direction. In the case of an arrow that forms a triaxial woven fabric having circumferential fibers intersecting with these inclined fibers at positions separated from each other, the reinforcing fibers that form the triaxial woven fabrics cause the bending stress of the shaft along the reinforcing fibers 3. It can be efficiently distributed in one direction to improve torsional rigidity and bending rigidity, and the sticky shaft allows the bending of the arrow and the vibration caused by the bending to be quickly damped during flight. In addition, the triaxial fabric formed by the reinforcing fibers of the skin layer intersects the reinforcing fibers in the two axial directions at different positions to form a triangular shape, so that the reinforcing fibers in the three directions intersect at one place. This prevents stress concentration in the same layer and efficiently distributes axial stress in three directions including the circumferential direction. As a result, the flying posture can be stabilized and the target can be accurately shot.

  1 to 3 schematically show an arrow 10 according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the arrow 10 of the present embodiment is formed as a target arrow used for a Japanese bow, and an arrowhead 14 that covers the tip is fixed to the tip of a shaft 12 that is a stalk by bonding or the like. At the end, an arrowhead 16 that is locked to the bowstring is fixed by adhesion or the like. In front of the arrowhead 16, three blades 18, whose blade shafts are fixed with a string 20, an adhesive, paint, etc., are arranged at three positions equally divided into three in the circumferential direction. 10 is rotated to stabilize the flight posture and flight direction. Reference numeral 22 denotes a weight member disposed at the tip of the shaft 12, and stabilizes the posture during flight together with the blades 18.

  The weight member 22 may be formed as a member separate from the shaft 12 and may be fixed to the shaft 12 as necessary. However, as will be described later, the fiber reinforced prepreg forming the shaft 12 has a specific gravity such as tungsten. A large material may be mixed in advance. Moreover, it is preferable that the fixing part of the arrowhead 14 is securely fixed between about 10 mm or more so that it does not come off during use. Usually, the shaft extends over a length of 10 mm to 30 mm. 12 to be fixed. The arrowhead 14 and the arrowhead 16 can be detachably attached to the shaft 12 by screwing or the like.

  As shown in FIGS. 2 and 3, the shaft 12 has a tubular structure formed by winding a fiber reinforced prepreg on, for example, a metal mandrel 8, and orients the reinforcing fibers in an inclined direction with respect to the axial length direction. The shaft 12 includes a body layer 28 having a tubular structure including an inner body layer 24 and an outer body layer 26 having an axial fiber layer in which reinforcing fibers are axially oriented on the inner body layer 24. The skin layer 30 is disposed on the main body layer 28.

  The fiber reinforced prepreg forming such a shaft 12 may be an appropriate fiber as long as the tensile elasticity, strength, elongation at break, vibration absorption, etc. are suitable for the shaft 12 as the reinforcing fiber. In addition to metal / inorganic fibers such as carbon fiber, boron fiber, alumina fiber, and glass fiber, organic fibers such as aramid fiber, polyester fiber, nylon fiber, and cotton fiber can be used. In particular, the main body layer 28 of the shaft 12, that is, the inner main body layer 24 and the outer main body layer 26, are preferably made of carbon fibers having excellent elastic modulus and strength as the reinforcing fibers 23 and 25.

  In addition to using a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polyamide or polyetherimide can be used as the matrix resin impregnated into the reinforcing fibers.

  As the fiber reinforced prepreg, as described above, in addition to the inclined direction prepregs 24a and 24b in which the reinforcing fibers 23 and 25 aligned in one direction are impregnated with the matrix resin and the axial length direction prepregs 26a and 26b, a woven fabric It is also possible to use a prepreg obtained by impregnating a matrix resin into (or non-woven fabric) reinforcing fibers, and further impregnating the matrix resin after winding the fiber bundle on the mandrel 8 alone.

  In any case, the resin impregnation amount for the reinforcing fiber, which is also referred to as RC below, is preferably used in the range of, for example, 20 wt% to 50 wt%. It is possible to select an arbitrary range such as 15 to 19 wt% for low RC and 51 to 60 wt% for high RC.

  In the present embodiment, the inner body layer 24 formed radially inward close to the mandrel 8 includes an inclined direction prepreg 24a in which the reinforcing fibers 23 are oriented in an inclined direction with respect to the axial length direction, and an inclined direction prepreg 24a. And an inclined direction prepreg 24b oriented on the opposite side that is line-symmetric with respect to the reinforcing fiber 23 in the axial direction, and is wound on the mandrel 8 to form the inclined direction prepreg 24a. The first inclined fiber layer and the second inclined direction fiber layer formed by the inclined direction prepreg 24b are oriented in a direction crossing each other. The inclination angle of these reinforcing fibers with respect to the axial direction is in the range of 10 to 60 degrees, and preferably in the range of 15 to 45 degrees. If necessary, the reinforcing fibers 23 can be arranged at an angle larger than 60 degrees.

  These inclined direction prepregs 24a and 24b have a thickness of, for example, 0.10 to 0.15 mm, and are wound on the mandrel 8 in a state of being overlapped with each other, so that the reinforcing fiber 23 is made to extend in the axial direction. For example, the first inclined fiber layer formed by the inclined direction prepreg 24a oriented in the inclination direction of about +30 degrees and the reinforcing fiber 23 are oriented in the inclination direction of, for example, about −30 degrees with respect to the axial length direction. It is possible to form the inner main body layer 24 by the inclined direction fiber layers in which the second inclined fiber layers formed by the inclined direction prepregs 24b intersecting with the reinforcing fibers 23a are alternately arranged one by one. As a result, the stress in the axial length direction due to the bending of the shaft 12 can be evenly distributed between the first and second inclined fiber layers located adjacent to each other, and the shaft 12 has a sticky and strong torsional strength. Can be.

The inner body layer 24 has a thickness of, for example, about 0.2 to 0.7 mm by stacking 2 to 6 of these inclined fiber layers, and the thickness t (see FIG. 3) of the shaft 12 is, for example, It is preferably formed to occupy the largest proportion of about 40 to 75%. In order to improve the specific strength and specific rigidity, it is preferable to form RC to 20 to 35 wt% and the elastic modulus of the reinforcing fiber 23 to about 20000 to 40000 kg / mm ² .

  The outer main body layer 26 is formed by winding the axial length direction fiber layer formed by the axial length direction prepregs 26 a and 26 b in which the reinforcing fibers 25 are oriented in the axial length direction on the inner main body layer 24.

  The axial length direction prepregs 26a and 26b forming the outer body layer 26 have a thickness of, for example, about 0.08 to 0.18 mm, and are wound, for example, 2 to 6 times, and the thickness is set to, for example, 0.0. The axial length direction fiber layer is formed on the inner body layer 24 with a thickness of about 1 to 0.5 mm. The outer body layer 26 has a bending rigidity and a sticky shaft, so that the thickness t of the shaft 12 is less than the inner body layer 24 and more than the skin layer 30, about 10 to 40. % Is preferred. These axial direction prepregs 26a and 26b may be wound in a state of being overlapped with each other, or may be wound one by one or one layer at a time.

If necessary, it is possible to form the outer body layer 26 by forming only one axially long prepreg that is wide, or by winding three or more prepregs in advance. Further, in order to improve the specific strength and specific rigidity, it is preferable to use 15 to 35 wt% of RC and about 20000 to 40000 kg / mm ² as the elastic modulus of the reinforcing fiber 23. The outer main body layer 26 formed of such an axial length direction fiber layer efficiently imparts rigidity against bending or bending of the shaft 12.

  Further, the skin layer 30 is formed on the main body layer 28 formed by winding the respective fiber reinforced prepregs in this way.

  The skin layer 30 of the present embodiment has a fiber layer in which at least a part of the reinforcing fibers 31a, 31b, and 31c is oriented in the inclined direction so as to intersect the axial length direction. In the present embodiment, As an example, the reinforcing fibers 31a and 31b formed of glass fibers or aramid fibers are disposed in the inclined directions intersecting each other at +30 degrees and −30 degrees with respect to the axial length direction, and the reinforcing fibers 31a that are these inclined direction fibers. , 31b is formed on the main body layer 28 by a multi-directional prepreg 32 which is formed in a triaxial woven shape in which reinforcing fibers 31c as circumferential fibers are extended at positions separated in the axial direction from the intersection of 31b, and impregnated with a matrix resin. A multidirectional fiber layer is formed. Further, the multi-directional fiber layer is covered with the scrim 34 to form the skin layer 30. Since the reinforcing fibers 31a and 31b are arranged at ± 30 degrees with respect to the axial length direction, the reinforcing fibers 31a to 31c form a large number of continuous triangular meshes and act on the shaft 12. The stress can be uniformly and efficiently distributed in the three directions of the inclination direction and the circumferential direction.

  Even when these reinforcing fibers 31a to 31c extend in the direction of forming an equilateral triangle, the reinforcing fibers 31a to 31c form a wide fiber bundle, so that the gap has a hexagonal shape. In addition, these reinforcing fibers 31a to 31c do not necessarily need to be extended in the direction of an equilateral triangle, but the inclined direction fibers have a triangular shape with the same angle with respect to the axial direction, and stress is applied in the circumferential direction. It is preferable to disperse evenly.

The multidirectional prepreg 32 forming this multidirectional fiber layer has a thickness of about 0.03 to 0.08 mm, preferably 0.03 to 0.06 mm, RC of 28 to 55 wt%, and reinforcing fibers 31a to 31c. The aramid fiber is formed to have an elastic modulus of about 2000 to 15000 kg / mm ² and is wound on the main body layer 28, for example, 1 to 4 times to form about 5 to 15% of the wall thickness t of the shaft 12. It is preferable to do.

  In addition, it is good to wind by making the overlap of a winding end part into 1.5 mm or less, Preferably it is 1.0 mm or less, or shifting the overlap position of each layer (circumferential direction equal dispersion | distribution).

  The multi-directional prepreg 32 that forms the skin layer 30 can use reinforcing fibers similar to the above-described fiber-reinforced prepreg, such as glass fibers, in addition to the aramid fibers as the reinforcing fibers 31a to 31c. In this case, the elastic modulus of the reinforcing fibers 31a to 31c is higher than the elastic modulus of the matrix resin, and is, for example, 80% or less of the elastic modulus of the reinforcing fibers 25 of the axial length direction prepregs 26a and 26b forming the outer body layer 26. And it is preferable to set it as the range of 70%-10%.

  Further, the multi-directional fiber layer is not only formed of a triaxial woven fabric composed of the reinforcing fibers 31a to 31c, but can disperse the axial stress acting on the shaft 12 in a direction other than the axial direction as will be described later. If it is, what is necessary is just to form the fiber layer in which at least a part is oriented in the inclination direction, for example, a four-axis woven fabric in which reinforcing fibers 3d (see FIG. 4C) are extended in the axial length direction. You may form in. In this case, the axial length direction fibers or the circumferential direction fibers are arranged so as to pass through the intersections of the inclined direction fibers 31a and 31b, but are shifted from the intersection points of these reinforcing fibers 31a and 31c in the circumferential direction or the axial length direction. It can also be arranged.

  The scrim 34 for forming the auxiliary layer on the multidirectional fiber layer has a thickness of about 0.02 to 0.05 mm, for example, a glass scrim or woven fabric 34 in which glass fibers are oriented in a cross shape. It is formed by winding it once, and prevents the reinforcing fibers of the multi-directional prepreg 32 from fuzzing.

  When each fiber reinforced prepreg is wound around the cored bar 8, it may be wound individually one by one, or each prepreg may be attached in advance and wound. For example, the inclined prepregs 24a and 24b forming the inner body layer 24 are wound on the mandrel 8 in a state of being overlapped with each other as described above, whereby the first inclined fiber layers and the second reinforcing fiber layers are alternately arranged. The reinforcing fibers 23 can be crossed by being arranged adjacent to each other. Moreover, when winding the inclination direction prepreg 24a, 24b one by one in order, it can form in the state which accumulated the 1st inclination fiber layer and the 2nd inclination fiber layer in the radial direction.

  In any case, except for the necessary parts such as attaching the arrowhead 14 at the front end of the front part and the arrowhead 16 at the rear end of the base part, the fibers are uniformly reinforced at the front part, the intermediate part and the base part along the axial direction of the shaft 12. It is preferable to laminate prepregs and make the wall thickness t substantially constant. In addition, items that affect the shooter's sensation and flight posture, such as the position of the center of gravity and outer diameter, can be set individually. It is possible to prevent the user from feeling uncomfortable.

  In this way, the fiber reinforced prepreg is wound around the mandrel 8, and the scrim 34 of the surface layer 30 is wound, and then tightened with a tightening tape, a heating step, a cooling step, a decentering, removal of the tightening tape, polishing, and the like. 1 is formed by attaching necessary parts such as arrowheads 14, arrowheads 16, and arrow blades 18 to the shaft 12 formed through the above process.

  FIG. 4 schematically shows the bent state of the arrow 10 at the moment when it is released from the bowstring.

  As shown in FIG. 4A, when the arrow 10 is released from the bowstring, the shaft 12 is subjected to a large pressing force from the string toward the front via the arrowhead 16, so that the shaft 12 bends greatly. Produce. As shown in FIG. 4B, the bending of the shaft 12 causes bending in the opposite direction due to the repulsion, and the rotation by the arrow blade 18 acts. The arrow 10 is finally linearly directed while rapidly converging the vibration due to the bending phenomenon as follows by the elasticity of the shaft 12.

  FIG. 4C shows a stress state when the shaft 12 is bent and curved. As described above, the stress acting on the shaft 12 in the same manner as when bending is applied is in the inclined direction and the axial length direction intersecting each other by the reinforcing fibers 23 and 25 arranged in the inner body layer 24 and the outer body layer 26. And further dispersed in the respective reinforcing fibers 31a to 31c forming the multidirectional fiber layer of the skin layer 30 (FIGS. 2 and 3).

  As a result, the internal stress of the shaft 12 can be distributed by the fibers in the inclined direction, and the sticky shaft 12 quickly attenuates the bending when the arrow 10 is released from the bow and the vibration caused by the bending during the flight. The posture is stable and it can shoot accurately to the target.

  When the reinforcing fibers of the multi-directional prepreg 32 forming the skin layer 30 form a triaxial woven fabric, the stress due to the bending of the shaft 12 is more radially outward than the main body layer 28, and the reinforcing fibers 31a in the inclined direction, 31b and the reinforcing fibers 31c in the circumferential direction, and when forming a 4-axis woven fabric, as shown in FIG. 4C, the fibers are further dispersed in the reinforcing fibers 31d in the axial direction. The

  In the skin layer 30, the reinforcing fibers 31a to 31c extending in the triaxial direction within the same multi-directional fiber layer or the cylindrical surface at the same level are used to reinforce the bending stress due to the bending of the shaft 12 with the reinforcing fibers 31a and 31b. Since the stress can be dispersed in the circumferential direction along the reinforcing fiber 31c, the stress component in the axial direction acting on the main body layer 28 can be distributed evenly along the inclined directions intersecting each other. Thus, the bending when the arrow is released and the vibration caused by the bending are quickly attenuated during the flight, the posture is stabilized, and the target can be accurately shot.

  In particular, since the elastic modulus of the reinforcing fibers 31a to 31d forming the multidirectional fiber layer is smaller than the elastic modulus of the reinforcing fiber 25 of the main body layer 28, the repulsive force is small and the vibration is attenuated. As a result, the stress acting in the axial length direction is gradually reduced, and hence the amount of bending or bending is also reduced.

  As described above, the reinforcing fibers 31a to 31c (including the reinforcing fibers 31d in the axial length direction when formed in a four-axis woven shape) form the multi-directional fiber layer of the skin layer 30 as the axis of the main body layer 28. Since the elastic modulus is smaller than the elastic modulus of the reinforcing fiber 25 forming the long direction fiber layer, the stress is absorbed in the skin layer 30. As a result, the repulsive force to bend to the opposite side is reduced, the bending or bending of the opposite side is reduced, the vibration is quickly attenuated, and the linear shape can be quickly restored.

  Further, the circumferential fibers 30c forming the multidirectional fiber layer of the skin layer 30 are separated in the axial direction from the intersection where the inclined fibers 31a and 31b intersect at an angle of 60 degrees. , 31b, the reinforcing fibers 31a to 31c efficiently disperse the bending stress of the shaft 12 in three directions along the reinforcing fibers, thereby providing torsional rigidity and bending rigidity. In addition to being able to improve, the sticky shaft quickly dampens the deflection when the arrow is released and the vibration caused by the deflection during flight. Further, the triaxial fabric formed by the reinforcing fibers 31a to 31c of the skin layer 30 intersects with each other at a position different from the intersecting position of the reinforcing fibers 31a and 31b in the two inclined directions, thereby forming a triangular shape. Stress concentration in the same layer due to crossing of the reinforcing fibers in three directions at one place is prevented, and axial stress is efficiently dispersed in three directions including the circumferential direction. As a result, the flying posture can be stabilized and the target can be accurately shot.

  Similarly, when this multidirectional fiber layer is formed as a four-axis woven fabric by the reinforcing fibers 31a to 31d, the stress can be efficiently dispersed in the same layer.

  In the above-described embodiment, the elastic modulus of the reinforcing fibers 31a to 31d forming the multidirectional fiber layer of the skin layer 30 is made smaller than that of the reinforcing fibers 23 and 25 of the main body layer 28, whereby stress is dispersed in the multidirectional fiber layer. However, the density of the reinforcing fibers 31a and 31b of the skin layer 30 is reduced by forming the specific gravity of these reinforcing fibers 31a to 31d smaller than the specific gravity of the reinforcing fibers 25 of the main body layer 28. The vibration damping property may be improved by reducing the value of. In addition to aramid fibers, organic fibers such as polyester resins can be used as reinforcing fibers having such a small specific gravity (small density) and excellent vibration damping properties.

  In this case, the bending stress acting on the shaft 12 by the reinforcing fibers 31a to 31d in the skin layer 30 is dispersed along the direction of the reinforcing fibers 31a to 31d, and the small specific gravity of the reinforcing fibers 31a to 31d and Due to the vibration damping property, it is possible to stabilize the posture by efficiently attenuating the bending or vibration of the shaft 12 during the flight.

  FIG. 5 shows a cross-sectional view along the axis 12a of the shaft 12 according to a modification.

  In this modification, the vibration is attenuated by adjusting the distribution of the weight and specific gravity of the main body layer 28 of the shaft 12.

  The shaft 12 has a specific gravity of an outer portion 28b arranged radially outside, with a central cylindrical surface (specifically, an intermediate position in the thickness) h passing through the center position in the thickness direction of the main body layer 28 as a boundary. It is formed smaller than the inner part 28a on the inner side in the direction. The outer part 28b and the inner part 28a of the main body layer 28 are defined by a central cylindrical surface h having the same thickness, and the fiber layer is the same as the inner main body layer 24 described above as the inner part 28a. The outer portion 28b can be formed in a layered structure similar to that of the outer body layer 26. Further, the surface layer 30 may be provided on the main body 28.

  In the shaft 12 according to this modification, the inner portion 28a located on the axial core 12a side is formed of a material having a relatively large specific gravity with respect to the outer portion 28b, whereby the main body layer 28 forming the main body portion of the shaft 12 is formed. The specific gravity can be concentrated on the shaft core 12a, and the shaft 12 bends, vibrates or rotates due to the action of not only the axial pressing force but also the deflected pressing force and rotation. Even when flying in a complex behavior, it is possible to effectively attenuate these flexures and vibrations to stabilize the posture and to shoot accurately with respect to the target.

  When the skin layer 30 is formed on the main body layer 28, the multi-directional fiber layer formed by the multi-directional prepreg 32 acts to stick the shaft 12 and absorb vibration, as in the above-described embodiment. . By this vibration absorbing action, when the shaft 12 is bent to the side, the vibration due to the bending is quickly absorbed and quickly returned to the linear shape to ensure a linear flight posture.

  In the above-described embodiment and modification, the vibration is attenuated by adjusting the elastic modulus, specific gravity, and the like in the radial direction of the shaft 12. In addition, in order to stabilize the flying posture of the arrow 10, the shaft 12 It is also possible to adjust the distribution of specific gravity along the axial direction.

  For example, when the weight of the intermediate portion and the base portion of the shaft 12 is reduced with respect to the tip portion, a relatively large amount of fibers having a large elastic modulus are distributed in the intermediate portion, or a relatively small amount of material having a low specific gravity is relatively distributed. By distributing the weight, the intermediate portion can be reduced in weight, and the bending of the intermediate portion during flight and the vibration of the bending can be absorbed.

  Also in this case, the skin layer 30 as described above may be formed, and the multi-directional fiber layer formed by the multi-directional prepreg 32 gives viscosity to the shaft 12 and absorbs vibration, as in the above-described embodiment. When the shaft 12 is bent to the side by this vibration absorbing action, the vibration caused by this bending is quickly absorbed and quickly returned to the linear shape to ensure a straight flight posture. Can do.

  Further, when the reinforcing fibers 31 of the multidirectional prepreg 32 are formed of elastomer resin fibers, the skin layer 30 can be formed as a vibration absorbing layer.

  The scrim 34 covering the multidirectional fiber layer of the skin layer 30 prevents fluffing of the reinforcing fibers of the multidirectional prepreg 32. In addition to the cloth-like member such as the glass scrim described above, the scrim 34 is aligned in one direction. A sheet or a resin film may be used, and may be omitted depending on the manufacturing conditions, in addition to the case where reinforcing fibers that do not cause fluff are used, or the amount of matrix resin impregnated in the multidirectional prepreg 32 is adjusted.

1 is an overall view of an arrow according to a preferred embodiment of the present invention. The layout of the fiber reinforced prepreg used for manufacture of the arrow of FIG. Sectional drawing of the shaft of the arrow of FIG. FIG. 1 shows a flying posture at the moment when the bow of the arrow in FIG. 1 is released, (A) is an explanatory diagram of a state where bending occurs, (B) is an explanatory diagram of a state where bending occurs in the reverse direction due to repulsion, (C) These are explanatory drawings which show the dispersion state of the stress by a skin layer. Sectional drawing of the shaft by a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Arrow, 12 ... Shaft, 23, 25, 31 ... Reinforcing fiber, 24 ... Inner body layer, 24a, 24b ... Inclined direction prepreg, 26 ... Outer body layer, 26a, 26b ... Axial length direction prepreg, 30 ... Skin layer .

Claims (5)

  A shaft formed by winding a fiber reinforced prepreg into a tubular structure is provided, and the shaft has a first inclined fiber layer in which reinforcing fibers are oriented in an inclination direction with respect to the axial length direction, and the first inclined fiber layer. An inner body layer having a second inclined fiber layer oriented in a crossing direction, and an outer body layer having an axial length fiber layer in which reinforcing fibers are oriented in the axial length direction on the inner body layer, An arrow comprising: a skin layer having a fiber layer in which at least a part of the reinforcing fibers is oriented in an inclined direction with respect to the axial length direction on the outer body layer.   A shaft having a main body layer formed by winding a fiber reinforced prepreg is provided, and this shaft has an axial length direction fiber layer in which reinforcing fibers are oriented in the axial length direction at least in part of the main body layer. On the layer, there is a skin layer formed by winding a fiber reinforced prepreg in which reinforcing fibers are oriented in at least two directions that are inclined with respect to the axial length direction and intersect each other, and the fibers forming this skin layer The arrow is characterized in that the reinforcing fiber of the reinforcing prepreg is formed of an organic fiber having a specific gravity smaller than that of the reinforcing fiber forming the axial length direction fiber layer of the main body layer and having a high vibration damping property.   The arrow according to claim 1 or 2, wherein the skin layer is formed of a fiber reinforced prepreg in which a reinforcing fiber forms a woven fabric made of a triaxial or tetraaxial woven fabric.   A shaft having a main body layer formed by winding a fiber reinforced prepreg is provided, and this shaft has a specific gravity on the outer side in the radial direction smaller than that on the inner side in the radial direction with a central cylindrical surface passing through the center position in the thickness direction of the main body layer as a boundary. An arrow characterized by being formed.   A shaft having a main body layer formed by winding a fiber reinforced prepreg and a skin layer formed by winding a fiber reinforced prepreg on the outer side of the main body layer, the main body layer having reinforcing fibers in the axial length direction. The fiber reinforced prepreg having an axial length direction fiber layer that is oriented and forming the skin layer is oriented in an inclination direction of 30 degrees in directions opposite to each other with respect to the axial length direction, and inclined direction fibers intersecting each other; An arrow characterized by forming a triaxial fabric having circumferential fibers intersecting with these inclined fibers at positions separated from the intersections of these inclined fibers in the axial length direction.

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