JPH08205649A - Transmission shaft for bush cutter, its production and operation stick for bush cutter - Google Patents

Abstract

PURPOSE: To provide the subject transmission shaft made of fiber-reinforced resin improved in joint durability, and to provide the subject operation stick consisting of a combination of this transmission shaft with a main pipe. CONSTITUTION: This transmission shaft for bush cutters has such a constitution that the cross-sectional shape of the inner or outer surface at its end to be jointed of a fiber-reinforced resin tubular body 50 constituting this shaft is made polygonal. The transmission shaft is produced by laminating the outer periphery of a mandrel made of soluble linear material with reinforcing fibers and a resin followed by conducting a pultrusion using a mold and then dissolving and removing the mandrel. The cross-sectional shape of the mandrel or the mold to be used is polygonal. The objective operation stick for bush cutters is a combination of this transmission shaft with a main pipe, and the main pipe is made up of a fiber-reinforced resin inner layer formed of carbon fibers crossedly arranged in a helical way, a fiber-reinforced resin intermediate layer formed of carbon fibers arranged axially, and a fiber-reinforced resin outer layer formed of carbon fifers crossedly arranged in a helical way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission shaft for a brush cutter, a method for manufacturing the same, and an operating rod for the brush cutter. More specifically, the present invention relates to a power transmission shaft for a brush cutter and a method for manufacturing the same. The present invention also relates to a bush cutter operating rod combined with a main pipe having required performance such as pipe strength and pipe rigidity while being thin.

[0002]

2. Description of the Related Art A brush cutter is equipped with a cutting blade on the front end side of an operating rod and a prime mover (small engine or small motor) on the rear end side, and the power of the prime mover is passed through the main pipe of the operating rod. It is configured to be transmitted to the cutting blade via. When a worker uses this brush cutter to mow weeds, the upper part of the operating rod on the prime mover side is supported on one side of the waist, and the waist is used as a fulcrum while the cutting blade on the tip side of the operating rod is swung to the left and right. To do.

As described above, since the operation of swinging the brush cutter to the left and right while supporting it on one side of the waist is performed, the work efficiency can be improved as the weight is reduced. Conventionally, as a measure to reduce the weight, it has been proposed that the transmission shaft inside the operating rod be changed from a steel pipe to a fiber-reinforced resin pipe, and the main pipe is changed from a steel pipe to an aluminum pipe, and the aluminum pipe is further made into a fiber-reinforced resin pipe. Proposals have been made to switch to tubes.

When the transmission shaft is formed of a fiber reinforced resin pipe, a metal joint for transmitting torque is joined to the end of the fiber reinforced resin pipe. This joining is generally performed by adhesion, press fitting, pinning, etc., but there is a problem that such means alone causes peeling or slack in the joined portion to destroy the joining. On the other hand, in the case of a main pipe made of fiber reinforced resin, there is a demand to reduce the amount of reinforcing fibers and resin used and to reduce the wall thickness of the pipe wall in order to further reduce the weight. However, simply thinning the fiber-reinforced resin pipe will not satisfy the various performances such as the minimum pipe strength and pipe rigidity required for the main rod for the operating rod of the brush cutter, and it is almost impossible to put it into practical use. It will be possible.

Further, in order to further improve the operability of the brush cutter, it is necessary for the main rod for the operating rod to have excellent vibration damping and shock resistance. However, if the tube wall is made thin, it becomes difficult to improve these performances.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission shaft for a brush cutter, which is made of fiber reinforced resin and has improved durability of a joint portion with a joint. Another object of the present invention is to provide a manufacturing method which enables easy manufacture of a fiber-reinforced resin transmission shaft having excellent durability at a joint with a joint.

Still another object of the present invention is to provide a fiber-reinforced resin transmission shaft having excellent durability at a joint portion with a joint and a main pipe into which the transmission shaft is inserted, which is made into a fiber-reinforced resin pipe to be thin-walled. Even so, it is to provide a mower operating rod that can maintain required performance such as pipe strength and pipe rigidity. It is still another object of the present invention to provide a bush cutter operating rod which is further provided with excellent vibration damping and impact resistance for the main pipe.

[0008]

Means for Solving the Problems A transmission shaft for a brush cutter according to the present invention which achieves the above object has a tubular body containing a fiber reinforced resin layer, and the inner surface of an end portion of the tubular body which is joined to at least a joint. Alternatively, the outer surface is formed into a polygonal cross-sectional shape. In this way, the tubular body made of fiber reinforced resin has a polygonal cross-sectional shape of the inner surface or the outer surface of the end portion to be joined with the joint,
The strength of the joint can be increased with respect to the torque transmission function, and the durability can be improved.

Further, in the method for manufacturing a transmission shaft for a brush cutter according to the present invention, which achieves the above object, a wire rod having a polygonal cross section made of a soluble material is used as a mandrel, and a reinforcing fiber and a resin are laminated in a tubular shape on the outer periphery of the mandrel. In addition, the laminate is moved together with the mandrel into a cylindrical mold for pultrusion, and then the mandrel is dissolved and removed.

Alternatively, according to another method of the present invention, a polygonal wire rod made of a soluble material is used as a mandrel, and reinforcing fibers and resin are laminated in a tubular shape on the outer periphery of the mandrel,
The laminated body is moved together with the mandrel into a metal mold having a polygonal cross-sectional shape, is drawn and molded, and then the mandrel is dissolved and removed. In this way, when forming a polygonal cross-sectional shape by pultrusion, since the linear mandrel is integrally drawn with the laminate of fiber-reinforced resin while pultrusion is performed, deformation of the mandrel or thin mandrel Since the mandrel can be easily removed by melting after molding without causing a breakage accident, an extremely smooth transmission shaft made of a fiber-reinforced resin pipe can be produced.

Further, the operating rod for a bush cutter according to the present invention, which achieves the above-mentioned object, is the operating rod for a bush cutter, wherein the transmission shaft is inserted inside the main pipe.
The transmission shaft has a tubular body including a fiber reinforced resin layer, at least the end portion of the tubular body joined to the joint is formed in a polygonal cross-sectional shape of the inner surface or the outer surface, and the main pipe is at least carbon fiber. An inner layer made of a fiber-reinforced resin layer in which the reinforcing fibers containing the fiber are helically arranged in opposite directions relative to the axial direction, and an intermediate layer made of a fiber-reinforced resin layer in which the reinforcing fibers containing at least carbon fibers are arranged in the axial direction,
It is characterized in that it is composed of a tubular body having a layered structure with an outer layer composed of a fiber-reinforced resin layer in which reinforcing fibers containing at least carbon fibers are helically arranged in opposite directions with respect to the axial direction.

As described above, in the structure of the main pipe, since the helically arranged fiber reinforced resin layers that most efficiently contribute to the compressive strength are arranged on the outer layer and the inner layer of the fiber reinforced resin pipe, it is necessary to use the minimum amount of reinforcing fibers. It is possible to achieve excellent pipe strength and pipe rigidity. That is, when a radial compressive load is applied to the fiber-reinforced resin pipe, maximum compressive stress is generated on the outer wall surface at the load point and maximum tensile stress is generated on the inner wall surface, and a stress distribution with a neutral axis of 0 stress is generated in the intermediate region. However, since the helically-arranged fiber-reinforced resin layer is arranged corresponding to the maximum compressive stress portion and the maximum tensile stress portion of this stress distribution, the required pipe strength and pipe rigidity can be exhibited with the minimum amount of reinforcing fiber used. it can.

Further, since the axially arranged fiber-reinforced resin layer that most efficiently contributes to the bending strength is arranged in the intermediate region including the neutral axis of the stress 0, the minimum reinforcing fiber can be obtained without reducing the compressive strength. It is possible to achieve the required bending strength and bending rigidity depending on the amount used. Furthermore, since the reinforcing fiber of each fiber reinforced resin layer is made of carbon fiber having a large specific strength and a large specific elastic modulus, the amount of fiber used can be further reduced and the weight can be reduced, while the pipe wall thickness can be further reduced. Allows maintenance of required performance such as pipe rigidity.

In the operating rod for a brush cutter according to the present invention, which achieves the above object, the transmission shaft has a tubular body including a fiber reinforced resin layer, and at least an inner surface or an outer surface of an end portion of the tubular body joined to a joint. The cross-sectional shape of is molded into a polygon,
And, the main pipe is an inner layer composed of a fiber reinforced resin layer in which reinforcing fibers containing at least carbon fibers are helically arranged in opposite directions with respect to the axial direction, and a fiber reinforced resin in which reinforcing fibers containing at least carbon fibers are arranged in the axial direction. An intermediate layer consisting of a layer, an outer layer consisting of a fiber reinforced resin layer in which reinforcing fibers containing at least carbon fibers are helically arranged in opposite directions relative to the axial direction, and further inside the inner layer and outside the outer layer respectively. A fiber reinforced resin layer in which reinforcing fibers are arranged in the axial direction is provided as an inner layer and an outermost layer.

By thus arranging the axially arranged fiber reinforced resin layers in the outermost layer and the innermost layer of the tubular body, respectively, the fiber reinforced structure in which the helically arranged fiber reinforced resin layers are arranged in the inner layer and the outer layer as described above. When the resin pipe is manufactured by the so-called pull wind method, it is possible to prevent the reinforcing fibers of the helically arranged fiber reinforced resin layer from being disturbed by frictional contact with the inner mandrel or the outer mold. Therefore, it is possible to manufacture a high-performance main bush operating rod main pipe without deteriorating the desired performance based on the above-mentioned helically arranged fiber-reinforced resin layer.

The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is a perspective view showing a main part of a fiber reinforced resin pipe which constitutes a transmission shaft for a brush cutter of the present invention. The fiber reinforced resin pipe 50 of FIG. 1 is configured by laminating two layers of an inner layer 51 and an outer layer 52. In the inner layer 51, the reinforcing fibers inclined helically at about 45 ° with respect to the axial direction of the tube and the reinforcing fibers inclined helically at about −45 ° in the opposite direction cross each other. The fiber-reinforced resin layer (hereinafter, referred to as “helical array fiber-reinforced resin layer”). Since the inner layer 51 is composed of the helically arranged fiber reinforced resin layer as described above, the transmission shaft is given torsional strength and torsional rigidity with respect to torque.

Further, the inner layer 51 is formed such that the cross-sectional shape of the inner surface orthogonal to the axial direction is a regular polygon (regular hexagon in the figure) by pultrusion which will be described later. The inner surface of the regular polygon is a portion where the connecting portion 53a of the metal joint 53 as shown in FIG. 2 fits. On the other hand, the outer layer 52 is composed of a fiber reinforced resin layer in which reinforcing fibers are arranged in the axial direction of the tube (hereinafter, referred to as axially arranged fiber reinforced resin layer).
Since the outer layer 52 is composed of the axially arranged fiber reinforced resin layer as described above, bending strength and bending rigidity are imparted to the transmission shaft.

The fiber-reinforced resin tube 50 thus constructed
On the inner surface of the regular hexagonal inner layer 51 with respect to the transmission shaft of, the regular hexagonal connecting portion 5 of the metal joint 53 as shown in FIG.
3a are joined by fitting through an adhesive, and are further fixed by being tightened from the outer peripheral side of the outer layer 52 by a reinforcing ring 54 or a reinforcing winding layer. The outer end portion 53b of the metal joint 53 serves as an input end from the prime mover or an output end for the cutting blade.

FIG. 4 is a perspective view showing another example of the drive shaft for the brush cutter of the present invention. In this embodiment, the fiber reinforced resin tube 60 constituting the transmission shaft is composed of an inner layer 51 made of a helically arranged fiber reinforced resin layer and an outer layer 52 made of an axially arranged fiber reinforced resin layer, as in the case of FIG. However, the difference is that the regular polygonal cross section is formed on the outer surface of the outer layer 52.

A fiber reinforced resin pipe 60 constructed in this way
A metal joint 63 is fitted and joined to the end of the regular hexagon of the transmission shaft as shown in FIG. That is, the connecting portion 63a of the metal joint 63 whose inner surface is formed in a regular hexagonal cross section is joined by being fitted with an adhesive. In each of the transmission shafts of the above-described embodiments, the cross-sectional shape of the inner surface or the outer surface into which the metal joint 53 fits is formed into a regular polygon by drawing, so that the fiber reinforced resin layer is The reinforcing fibers are not cut. Therefore, the strength required for torque transmission can be maintained as designed and good durability can be obtained.

In the present invention, carbon fibers, aromatic polyamide fibers, aromatic polyester fibers, polyvinyl alcohol fibers and the like can be used as the reinforcing fibers for the inner layer and outer layer of the fiber reinforced resin tube. Particularly, carbon fiber having excellent specific strength and specific elastic modulus is preferable. Further, the polygon formed on the inner surface of the fiber-reinforced resin pipe is not limited to a hexagon, and a triangle or more and an octagon can be applied. Further, as this polygon, a regular polygon is preferable, and since the regularity is lost by making the regular polygon, the fitting operation can be facilitated. Further, this polygonal cross-sectional shape does not necessarily have to be formed over the entire length of the fiber reinforced resin pipe as in the illustrated example, and may be formed only at the end portion where the joint is fitted.

FIG. 6 shows a manufacturing process of the fiber reinforced resin pipe constituting the transmission shaft according to the present invention. In FIG. 6, 71 is a mandrel 8 made of a soluble wire rod.
0 is wound around the creel, and 72 and 73 are packages 72a and 73a around which the reinforcing fiber for the inner layer of the fiber reinforced resin tube is wound.
Spiral winder, 74 is a package in which reinforcing fibers for the outer layer of a fiber-reinforced resin tube are wound, 75, 76
Is a resin impregnation bath, 77 is a guide, 78 is a heated cylindrical mold, and 79 is a puller. Among these members, at least one of the cross-sectional shape of the mandrel 80 and the cross-sectional shape of the molding hole of the mold 79 is formed in a polygonal shape.

In the above structure, the linear mandrel 80 wound around the creel 71 is continuously drawn out linearly by the puller 79, and the reinforcing fiber of the package 72a is first pulled by the spiral winder 72.
It is spirally wound on the upper side in the axial direction, and then the reinforcing fiber of the package 73a is wound on the spiral in the opposite direction by the next spiral winder 73 and laminated. Next, this laminated body is immersed in the resin impregnation bath 75 to be impregnated with the resin to form an inner layer.

On the other hand, the reinforcing fiber pulled out from the package 74 is impregnated with resin in the resin impregnation bath 76,
On the inner layer laminate formed on the mandrel 80,
While being aligned in parallel with the axial direction of the mandrel 80 by the guide 77, the mandrel 80 is laminated so as to cover the periphery thereof to form an outer layer. Next, the laminated body formed on the mandrel 80 is pultruded integrally with the mandrel 80 while passing through the mold 78, and the impregnated resin is thermoset to form the fiber reinforced resin pipe 50 (60).

In this molding, when the mandrel 80 having a polygonal cross section is used, the fiber reinforced resin pipe 50 (6
When the inner surface of 0) is formed in a polygonal shape and a die 78 having a polygonal cross section is used, the fiber-reinforced resin pipe 50 (60)
The outer surface of is shaped into a polygon. Next, the fiber reinforced resin pipe 50 (60) is drawn out by the puller 79 together with the mandrel 80, cut into a predetermined length, and then the mandrel 80 is dissolved and removed to be processed into a transmission shaft.

The transmission shaft for a brush cutter generally has a small effective diameter of 10 mm or less. Therefore, when pultrusion is performed with a fixed mandrel like a conventional pultrusion machine,
It is difficult to perform stable molding because the mandrel may be deformed so as to be thinly stretched or broken due to the frictional force in the mold.
However, this can be stabilized by the molding method according to the present invention described above.

As the material of the mandrel made of the soluble wire used in the present invention, lost wax, low melting point metal, etc. can be used. Further, in order to dissolve and remove the soluble wire rod, heating or elution with hot water or the like may be performed. Further, the linear mandrel can be easily obtained by extrusion molding. This mandrel may be pre-formed on a creel and then supplied to the molding step as in the illustrated example, but it may be directly supplied while being continuously extruded by an extruder. Good.

Further, as described above, the polygon is formed by a forming means such as a metal mold or a mandrel, so that the reinforcing fibers in the fiber-reinforced resin are partially cut as in the case of machining the polygon. Therefore, the joint strength with the joint is improved and the durability can be further improved. FIG. 7 (A) is a partially cutaway view of the main part of the fiber-reinforced resin pipe forming the main pipe of the operating rod of the brush cutter of the present invention, and FIG. 7 (B) shows this fiber-reinforced resin pipe. It is a development view of a tube wall lamination part.

In FIGS. 7A and 7B, the fiber reinforced resin pipe 1 is constructed by laminating three layers of an inner layer 2, an intermediate layer 3 and an outer layer 4. Of these three layers, the intermediate layer 3 is
It is composed of a fiber reinforced resin layer in which carbon fibers 3a are arranged in the axial direction AX of the tube. Further, the inner layer 2 is a fiber reinforced structure in which carbon fibers 2a helically arranged with respect to the axial direction AX of the pipe and carbon fibers 2b arranged obliquely in the opposite direction cross each other. It is composed of a resin layer. Similarly, the outer layer 4 is also reinforced so that the carbon fibers 4a that are helically inclined with respect to the axial direction AX of the tube and the carbon fibers 4b that are inclined in the opposite direction and the carbon fibers 4b are intersecting with each other. It is composed of a resin layer.

Now, assuming that a compressive load F, F in the radial direction is applied to the fiber reinforced resin pipe 1 in which such three layers of fiber reinforced resin are laminated, as shown in FIG. The stress distribution in the thickness direction of is as shown in FIG. 11 (B). That is, the maximum compressive stress σ _c is generated on the outer wall surface of the fiber-reinforced resin pipe 1, while the maximum tensile stress σ _t is generated on the inner wall surface, and a neutral axis with zero stress is formed in the intermediate region.

In the fiber-reinforced resin pipe 1 having the above-mentioned structure, the helical arrangement that most efficiently contributes to the compressive strength is provided in the outer layer 4 where the maximum compressive stress σ _c is generated and the inner layer 2 where the maximum tensile stress σ _t is generated. Since the fiber-reinforced resin layer is arranged, the required pipe strength and pipe rigidity are exhibited with the minimum amount of reinforcing fibers used. In addition, since the axially arranged fiber reinforced resin layer that most efficiently contributes to the bending strength is arranged in the intermediate region including the neutral axis of the stress 0, the compression strength in the radial direction is not decreased and The required bending strength and bending rigidity can be exhibited depending on the amount of reinforcing fibers used. Further, since the reinforcing fiber is a carbon fiber having a high specific strength and a high specific elastic modulus, it becomes possible to exhibit the required pipe strength, pipe rigidity and the like even if the fiber usage amount is small and the wall thickness of the pipe is thin.

The wall thickness t of the main wall of the operating rod main pipe of the present invention having the above characteristics is 0.8 to 2.5 mm, preferably 1.
It is recommended that the wall thickness be 0 to 2.0 mm. Regarding the thickness of the inner layer, the intermediate layer, and the outer layer, the thickness of the inner layer and the outer layer is set to 20 to 80% of the thickness of the intermediate layer with reference to the intermediate layer. In the present invention, the inner layer, the intermediate layer, the reinforcing fiber constituting each of the fiber-reinforced resin layer of the outer layer, at least as compared with the general fiber, a carbon fiber having a significantly large specific strength and specific elastic modulus is used. The amount used should occupy at least 50% by volume of the total amount of reinforcing fibers.

The helical angles of the reinforcing fibers of the helically arranged fiber reinforced resin layers of the inner layer and the outer layer inclined with respect to the axial direction of the tube are preferably 60 ° to 90 °.
The helical arrangement fiber-reinforced resin layer is a layer that bears the compressive strength, so the theoretical helical angle is optimally 90 ° to improve the compressive strength, but in the case of continuous production such as the pullwind method, the helical angle is optimal. The productivity decreases as the angle approaches 90 °. Therefore, from the viewpoint of improving productivity, the smaller the helical angle is, the more preferable, but if it is smaller than 60 °, it becomes difficult to maintain the required compressive strength.

Since the axially arranged fiber reinforced resin layer of the intermediate layer is for imparting bending rigidity to the fiber reinforced resin pipe, in the case of a thick wall, this axially arranged fiber reinforced resin layer is the outer layer. It is effective to place them. However, in the case of the operating rod main pipe of the present invention, since it is made thin for the purpose of thinning, it does not hinder the maintenance of the required bending rigidity even if this axially arranged fiber reinforced resin layer is arranged in the intermediate layer. .

In the present invention, when other fibers besides carbon fibers are used as the reinforcing fibers, it is preferable to use organic fibers together. By using this organic fiber in combination, the impact resistance of the operating rod main pipe can be improved as compared with the case of reinforcing with 100% carbon fiber. That is, when the operating rod main pipe receives a very large impact, it is possible to prevent the main pipe from being broken so as to be completely bisected, so that the safety of the brush cutter operating rod can be improved.

Further, by using this organic fiber together, the vibration damping property of the fiber reinforced resin pipe is also improved, and the amount of the vibration of the prime mover transmitted to the worker can be reduced, thereby improving the workability. it can. As the organic fibers used in combination in this way, for example, aromatic polyamide fibers, aromatic polyester fibers, polyvinyl alcohol fibers, and other high-strength, high-modulus fibers are preferable, but general organic fibers such as nylon and polyester are used. May be. Of course, when the effect of such organic fibers is not particularly required, inorganic fibers such as glass fibers may be used as an auxiliary fiber to be used in combination with the carbon fibers.

The matrix resin used for the fiber reinforced resin layer includes epoxy resin, unsaturated polyester resin,
Thermosetting resins such as vinyl ester resins are preferred. In particular, in the case where the operating rod main pipe is continuously manufactured by the pull wind method, it is preferable to use a thermosetting resin. Of course,
Thermoplastic resins such as polyamide resins and polyester resins can also be used.

An elastomer may be mixed with the matrix resin. By mixing this elastomer, it is possible to improve the shock resistance and the vibration damping property of the operating rod main pipe, as in the case of using the organic fiber together. Examples of the elastomer mixed with the matrix resin include polybutadiene and acrylonitrile-butadiene copolymer. In particular, the acrylonitrile-butadiene copolymer is excellent in compatibility with an epoxy resin that is a typical matrix resin, and therefore can exhibit a higher vibration damping property. Particularly, when acrylonitrile-butadiene copolymer having a polymerization ratio of acrylonitrile of 20 to 50% is mixed with an epoxy resin in an amount of 10 to 40% by weight, excellent vibration damping property can be exhibited.

FIGS. 8A and 8B show another example of the fiber-reinforced resin pipe constituting the main pipe for the operating rod of the brush cutter of the present invention. The fiber-reinforced resin pipe 10 of this embodiment is shown in FIG.
The innermost layer 5 and the outermost layer 6 are laminated on the inner surface and the outer surface of the fiber-reinforced resin pipe 1 shown in (A) and (B), respectively. In the innermost layer 5, the reinforcing fibers 5a are arranged in the axial direction AX of the pipe. It is composed of a fiber reinforced resin layer, and similarly, the outermost layer 6 is also composed of a fiber reinforced resin layer in which reinforcing fibers 6a are arranged in the axial direction AX of the tube.

By stacking the innermost layer 5 and the outermost layer 6 of such axially arranged fiber-reinforced resin layers, the inner layer 2 and the outer layer 4 form a helical shape especially in the step of manufacturing a fiber-reinforced resin pipe by the pullwind method. Carbon fiber 2
It is possible to prevent a, 2b, 4a, 4b from being disturbed by strong frictional contact with the inner mandrel or the outer mold. Therefore, the desired performance can be surely exhibited without compromising the above-mentioned various performances based on the basic configuration of FIGS. 7A and 7B, and a highly reliable operating rod main pipe can be obtained.

The innermost layer 5 used for the above purpose,
The thickness of the outermost layer 6 does not need to be large, and is preferably about 1 to 50% of the thickness of the intermediate layer 3. The reinforcing fibers used in the innermost layer 5 and the outermost layer 6 may be carbon fibers, but need not necessarily be carbon fibers having high strength and high elastic modulus, and aromatic polyamide fibers, In addition to high-strength and high-modulus fibers such as aromatic polyester fibers and polyvinyl alcohol fibers, general organic fibers such as nylon and polyester may be used. Further, instead of the reinforcing fiber, a thin fabric such as nylon or polyester taffeta may be used instead.

9A and 9B show still another embodiment of the present invention, and FIGS. 10A and 10B show still another embodiment. The fiber-reinforced resin tube 20 of the embodiment shown in FIGS. 9A and 9B is obtained by coating the heat-shrinkable resin tube 7 on the outer circumference of the fiber-reinforced resin tube 1 shown in FIGS. 7A and 7B. 10A and 10B, the fiber-reinforced resin tube 30 shown in FIGS. 10A and 10B is coated with the heat-shrinkable resin tube 8 on the outer periphery of the fiber-reinforced resin tube 10 shown in FIGS. It was done.

The fiber-reinforced resin tubes 20 and 30 are provided with the bending shock resistance by coating the heat-shrinkable resin tubes 7 and 8, and when a very large shock is applied to the operation rod main tube from the outside. Moreover, it is possible to prevent a damage accident such that the main pipe is completely divided into two parts. Examples of the resin that can be used for the heat-shrinkable resin tube include polyethylene, polyvinyl chloride, and fluororesin.

As a means for improving the impact resistance in this way, in addition to the method of coating the heat-shrinkable resin tube as described above, a method of using the above-mentioned organic fibers in combination or a method of mixing an elastomer with the matrix resin is used. is there. Any one of these three methods may be used, or any two of them may be used in combination, or all three may be used at the same time.

[0045]

As described above, according to the transmission shaft for a brush cutter of the present invention, the tubular body made of the fiber reinforced resin layer has a polygonal cross-sectional shape of the inner surface or the outer surface of the end portion joined to the joint. The strength of the joint portion can be sufficiently obtained for the torque transmission function, and the durability can be improved.

According to the method of manufacturing the transmission shaft of the present invention, a linear mandrel made of a soluble material is used,
Since this mandrel is integrally molded with the fiber reinforced resin laminate while being drawn and molded, it does not cause deformation or breakage of the mandrel even if the mandrel is thin, and the mandrel can be easily removed by melting after molding, so it is extremely smooth. Enables the production of various drive shafts.

The main pipe to be combined with the drive shaft of the present invention is
Since the axially arranged fiber-reinforced resin layer of reinforcing fibers containing at least carbon fibers is arranged in the intermediate layer, and the helical arrangement fiber-reinforced resin layer of reinforcing fibers containing carbon fibers is arranged in the inner layer and the outer layer to form a laminate. Even if the fiber-reinforced resin pipe is made thin, necessary performances such as pipe strength and pipe rigidity can be maintained. Further, when the axially arranged fiber reinforced resin layers are arranged on the outer circumference and the inner circumference of the laminate, the reliability of performance can be further improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a fiber reinforced resin pipe which serves as a transmission shaft for a brush cutter of the present invention.

FIG. 2 is a perspective view of a metal joint joined to the fiber reinforced resin pipe of FIG.

3 is a cross-sectional view of a connecting portion when the fiber-reinforced resin pipe of FIG. 1 and the metal joint of FIG. 2 are connected.

FIG. 4 is a perspective view showing another embodiment of the fiber-reinforced resin pipe that serves as the transmission shaft for the brush cutter of the present invention.

5 is a cross-sectional view of a connecting portion when a metal joint is connected to the fiber reinforced resin pipe of FIG.

FIG. 6 is a schematic view showing a manufacturing process of a fiber-reinforced resin pipe for a drive shaft according to the present invention.

FIG. 7 (A) is a side view showing a main portion of a fiber-reinforced resin pipe, which is a main pipe for a bush cutter operating rod of the present invention, with a part thereof broken away;
[Fig. 4] is a development view showing a laminated portion of the tube wall in an exploded manner.

FIG. 8 (A) is a side view showing a fiber reinforced resin pipe, which is a main pipe for an operating rod of a bush cutter, according to another embodiment of the present invention, with a part of the main part cut away; It is a development view which decomposes | disassembles and shows a laminated part.

FIG. 9 (A) is a side view showing a fiber reinforced resin pipe, which is a main pipe for an operating rod of a brush cutter, according to still another embodiment of the present invention, with a part of the main part cut away; It is a development view which decomposes | disassembles and shows the laminated part of.

FIG. 10 (A) is a side view showing a fiber reinforced resin pipe as a main pipe for a control rod of a brush cutter according to still another embodiment of the present invention, with a part of the main part cut away; It is a development view which decomposes | disassembles and shows the laminated part of.

FIG. 11A is an explanatory view showing a case where a compressive load is applied to the fiber reinforced resin pipe, and FIG. 11B is an explanatory view showing a stress distribution within the wall thickness of the pipe when the compressive load is applied. .

[Explanation of symbols]

 1,10,20,30 Fiber reinforced resin tube 2 Inner layer 3 Middle layer 4 Outer layer 5 Innermost layer 6 Outermost layer 7,8 Heat shrinkable resin tube 2a, 2b, 3a, 3b, 4a, 4b Carbon fiber 5a, 6a Reinforced fiber 50,60 Fiber reinforced resin pipe 51 Inner layer 52 Outer layer 53,63 Metal joint 53a, 63a Connecting part 71 Creel 72,73 Spiral winder 72a, 73a, 74 Package 75,76 Resin impregnated bath 78 Mold 80 Mandrel

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Claims (13)

[Claims] 1. A transmission shaft for a bush cutter, comprising a tubular body including a fiber reinforced resin layer, and at least an end portion of the tubular body joined to a joint has a polygonal cross-sectional shape of an inner surface or an outer surface. . 2. The fiber reinforced resin layer comprises an outer layer made of a fiber reinforced resin layer in which reinforced fibers are axially arranged, and a fiber reinforced resin layer in which reinforced fibers are helically arranged in opposite directions to the axial direction. The transmission shaft for a brush cutter according to claim 1, further comprising an inner layer. 3. A wire rod having a polygonal cross section made of a soluble material is used as a mandrel, reinforcing fibers and a resin are laminated in a tubular shape on the outer periphery of the mandrel, and the laminate is moved together with the mandrel into a cylindrical mold. A method of manufacturing a transmission shaft for a brush cutter, which comprises: pultrusion and then melting and removing the mandrel. 4. A polygonal wire rod made of a soluble material is used as a mandrel, reinforcing fibers and a resin are laminated in a tubular shape on the outer periphery of the mandrel, and the laminate is placed together with the mandrel in a mold having a polygonal cross section. A method for manufacturing a transmission shaft for a bush cutter, which comprises moving and pultrusion, and then melting and removing the mandrel. 5. An operating rod for a bush cutter, wherein a transmission shaft is inserted and arranged inside a main pipe, wherein the transmission shaft has a tubular body including a fiber reinforced resin layer, and an end portion of the tubular body joined to at least a joint. An inner layer formed of a fiber-reinforced resin layer in which the cross-sectional shape of the inner surface or the outer surface is formed into a polygonal shape, and the main pipe is a fiber-reinforced resin layer in which reinforcing fibers including at least carbon fibers are helically arranged in opposite directions with respect to the axial direction, An outer layer consisting of an intermediate layer composed of a fiber-reinforced resin layer in which reinforcing fibers containing carbon fibers are axially arranged, and a fiber-reinforced resin layer in which reinforcing fibers containing at least carbon fibers are helically arranged in opposite directions with respect to the axial direction. An operating rod for a brush cutter, which is composed of a tubular body having a layered structure with. 6. An operating rod for a bush cutter, wherein a transmission shaft is inserted and arranged inside a main pipe, wherein the transmission shaft has a tubular body containing a fiber reinforced resin layer, and an end portion of the tubular body joined to at least a joint. An inner layer formed of a fiber-reinforced resin layer in which the cross-sectional shape of the inner surface or the outer surface is formed into a polygonal shape, and the main pipe is a fiber-reinforced resin layer in which reinforcing fibers including at least carbon fibers are helically arranged in opposite directions with respect to the axial direction, An outer layer consisting of an intermediate layer composed of a fiber-reinforced resin layer in which reinforcing fibers containing carbon fibers are axially arranged, and a fiber-reinforced resin layer in which reinforcing fibers containing at least carbon fibers are helically arranged in opposite directions with respect to the axial direction. An operating rod for a brush cutter, further comprising a fiber reinforced resin layer in which reinforcing fibers are axially arranged as an innermost layer and an outermost layer, respectively, inside the inner layer and outside the outer layer. 7. The operating rod for a bush cutter according to claim 5, wherein the tubular body has a wall thickness of 0.8 to 2.5 mm. 8. The operating rod for a bush cutter according to claim 5, wherein the inner layer and the outer layer each have a wall thickness of 20 to 80% of the wall thickness of the intermediate layer. 9. The operating rod for a bush cutter according to claim 6, wherein the innermost layer and the outermost layer each have a wall thickness of 1 to 50% of a wall thickness of the intermediate layer. 10. The operating rod for a bush cutter according to claim 5, wherein the helical angles of the reinforcing fibers of the inner layer and the outer layer with respect to the axial direction are 60 ° to 90 °, respectively. 11. The operating rod for a bush cutter according to claim 5, wherein the matrix resin of the fiber reinforced resin layer is mixed with an elastomer. 12. The operating rod for a bush cutter according to claim 5, wherein an organic fiber is used together with a carbon fiber as the reinforcing fiber of the fiber reinforced resin layer. 13. The operating rod for a bush cutter according to claim 5, wherein a heat-shrinkable resin tube is coated on the outer circumference of the tubular body.