JPH05138759A - Production of bent pipe - Google Patents

Abstract

PURPOSE:To provide a method for producing various kinds of bent pipes of which are curved in the axial direction thereof, for example, a handle bar with a return for a bicycle enhanced in bending strength, elasticity and rigidity to a large extent. CONSTITUTION:A circular prepreg laminate 110C is fitted to the inner surface of the semicircular prepreg laminate 110A of a lower mold 200A so that a slit 112 is turned upwardly and, subsequently, an upper mold 200B having a semicircular prepreg laminate 110B formed thereto is superposed on the lower mold 200A to fix both molds. Next, an inner pressure tube is inflated under pressure reducing treatment to press the circular prepreg laminate 110C and the semicircular prepreg laminates 110A, 110B to the molding surfaces of both molds to heat and cure the prepregs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing various curved tubes which are composed of a plurality of fiber reinforced resin layers and which are curved in the axial direction, such as a handlebar with a barb for a bicycle.

[0002]

2. Description of the Related Art In recent years, as a handlebar for a bicycle, it is made of a fiber-reinforced composite resin product using carbon fiber, glass fiber, aramid fiber or the like as a reinforcing fiber because it is lightweight and has high mechanical strength. Many of them are used and good results have been obtained.

If the bicycle handlebar has a straight type, it is formed by winding a predetermined number of fiber-reinforced prepregs cut into a predetermined size on a mandrel and curing the mandrel.

At this time, in order to improve other mechanical properties such as rigidity as well as twisting and bending performance, for example, when carbon fiber is used as the reinforcing fiber, refer to FIG. 6 for the fiber reinforced prepreg. As will be understood, basically, in order from the inner layer to the outer layer, the reinforcing fibers are opposite to each other with respect to the axis of the bicycle handlebar at an angle (θ) (usually θ = 25 ° to 90 °). ) Prepregs 101 (101A ₁ , 101A) arranged so as to be inclined only
₂ ) (angle layer 101A ′), prepreg 102A ₁ (90 ° layer 102A ₁ ′) in which reinforcing fibers are arranged in a direction of 90 ° with respect to the axis of the bicycle handlebar, and reinforcing fibers of the bicycle handlebar. Parallel to the axis (θ =
Prepreg 103 (0 ° layer 10) arranged in 0 °
3 ') and reinforcing fibers arranged in a 90 ° direction with respect to the axis of the bicycle handlebar, the prepreg 102A ₂ (9
The 0 ° layer 102A ₂ ′) is laminated.

[0005]

However, in recent years,
As shown in FIG. 5, a bicycle handlebar that is curved in the axial direction, that is, has a barb, is often required for convenience in use or for design (fashion). became.

Such a handlebar with a barb for a bicycle cannot be manufactured by using the above mandrel, but is manufactured exclusively by a wet method.

That is, according to the wet method, a cloth (fabric) which has not been impregnated with the matrix resin and has a predetermined shape and size is attached to the inner surface of the forming die, and thereafter,
Matrix resin is impregnated from the inside of the mold and cured,
The product is made.

Fiber-reinforced resin pipe products produced by such a wet method use straight fibers as reinforcing fibers,
It is extremely difficult to mold by arranging in the 90 ° direction or 0 ° direction with respect to the axis of the handlebar, and as described above, cloth is used as the reinforcing fiber. For this reason, the conventional handlebar with a barb for bicycle has a problem that the bending strength, elasticity, and rigidity are insufficient.

Further, it is difficult to mold the fiber-reinforced resin pipe product produced by the wet method so that the inner and outer diameters are uniform, and the pipe wall thickness is always uneven, so that a product of constant quality is produced. It was extremely difficult to do so, and it was practically impossible to accurately control the strength and rigidity of the manufactured product.

It is therefore an object of the present invention to very efficiently manufacture various axially curved bends, such as barbed handlebars for bicycles, with significantly improved bending strength, elasticity and stiffness. It is an object of the present invention to provide a method of manufacturing a bent tube that can be manufactured.

Another object of the present invention is to form the inner and outer diameters uniformly so that the wall thickness of the pipe can be always finished as desired.
It is an object of the present invention to provide a method for manufacturing a curved pipe, which is capable of manufacturing a product of constant quality and which can accurately control the strength and rigidity of the manufactured product.

[0012]

The above object can be achieved by the method for manufacturing a curved pipe according to the present invention. In summary, the present invention provides (a) a half-divided mold comprising a lower mold and an upper mold, and a mold release treatment is performed on the molding surfaces of the separated lower mold and upper mold. A step of applying, (b) a step of laminating a predetermined number of fiber reinforced prepregs on the respective molding surfaces of both the molds to form a prepreg laminate having a semicircular cross section, (c) On the other hand, a mold release treatment was applied. A step of winding a predetermined number of fiber reinforced prepregs around a mandrel and laminating the prepregs to form a prepreg laminate having a circular cross section, (d)
A step of extracting the circular prepreg laminated body from the mandrel and making a cut in the longitudinal direction of the prepreg laminated body, (e) the circular prepreg laminated body of the lower molding die with the cut being on the upper side. A step of installing the semi-circular prepreg laminate in conformity with the inner surface thereof, (f) at the central position of the circular prepreg laminate, an inner pressure tube subjected to mold release treatment along the longitudinal direction of the prepreg laminate A step of inserting and arranging, (g) a step of overlapping a cut portion of the circular prepreg laminate with a cut portion along a longitudinal direction, and (h) a step of forming the upper mold with a semicircular prepreg laminate of the upper mold. A step of superimposing on the lower molding die so that the inner surface fits to the outer surface of the circular prepreg laminate and fixing both molding dies, (i) molding surfaces of both molding dies and semicircular shape A step of performing a decompression treatment so as to prevent the occurrence of voids between the outer surface of the prepreg laminate and between each prepreg, (j) at the same time, pressurizing the inside of the internal pressure tube to expand the internal pressure tube to form a circular shape A method for manufacturing a curved pipe, comprising a step of heating and curing each prepreg while pressing the prepreg laminate and the semicircular prepreg laminate against the molding surfaces of both molds.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of manufacturing a curved pipe according to the present invention will be described in more detail with reference to the drawings. In the present embodiment, the curved pipe to be manufactured is described as the handlebar bar 1 for a bicycle as shown in FIG. 5, but the present invention is not limited to this.

The bicycle handlebar 1 manufactured in this embodiment basically comprises a plurality of fiber reinforced resin layers described with reference to FIG. It is assumed that several fiber reinforced resin layers are laminated to satisfy the characteristics.

To carry out the manufacturing method of the present invention, as shown in FIG. 3, the lower molding die 200A having the same shape is used.
A half-type molding die 200 composed of the upper molding die 200B is used. A cavity 202 is formed in both molds 200A and 200B so as to match the outer shape of the bicycle handlebar 1 when they are overlapped.

According to the present embodiment, as shown in FIG. 5, the bicycle handlebar 1 has an inner diameter (d) and an outer diameter D which are constant in the axial direction, but only at the center. The diameter (D ₀ ) is made slightly larger.

Next, the manufacturing method of the present invention will be described. First, the upper and lower molds 200A and 200B separated from each other are separated.
Molding surfaces 200A ₀ and 200B ₀ are subjected to a mold release treatment, and as shown in FIGS. 1 (B) and 1 (C), carbon fiber cloth is applied to the molding surfaces 200A ₀ and 200B ₀ of both molds. The carbon fiber cloth prepreg 104, which is a reinforcing fiber, is laminated. Of course, carbon fiber cloth prepreg 104
Is used by cutting (molding) so as to fill the molding surfaces 200A ₀ and 200B ₀ of the respective molding dies 200A and 200B over half the circumference. An example of a blank of the carbon fiber cloth prepreg 104 used is shown in FIG. 4 (A).

Then, similarly, both molding dies 200A,
In 200B, carbon fiber reinforced prepreg 102A _{2 in} which reinforcing fibers are arranged in a 90 ° direction with respect to the axis of the bicycle handlebar, and reinforcing fibers are parallel to the axis of the bicycle handlebar (θ = 0 °). The carbon fiber reinforced prepregs 103 arranged in the above are sequentially laminated. 90 ° carbon fiber reinforced prepreg 102A ₂ and 0 ° carbon fiber reinforced prepreg 103 may be further laminated depending on mechanical properties such as strength and rigidity required for the product. An example of the carbon fiber reinforced prepreg 102A _{2 used} and a blank obtained by molding the carbon fiber reinforced prepreg 103 is shown in FIG.
Shown in (B) and (C).

In this way, both molding dies 200A, 20
0B, molding surfaces 200A ₀ , 20 over each half circumference
At 0B ₀ , prepreg laminated bodies 110A and 110B having a semicircular cross section are formed.

On the other hand, as shown in FIG. 1 (A), a mandrel 300 which has been subjected to a mold release treatment is used. In this embodiment, a glass fiber cloth prepreg 105 using glass fiber cloth as a reinforcing fiber and a reinforcing fiber are used for the mandrel. Angles (θ) in opposite directions with respect to the axis of 300, ie, the axis of the bicycle handlebar (typically θ = 25 ° to 90 °).
), In this embodiment, carbon fiber reinforced prepregs 101 (101A ₁ , 10A ₁ , 10 arranged so as to be inclined by ± 35 °).
1A ₂ ), an aramid fiber cloth prepreg 106 using aramid fiber cloth as a reinforcing fiber, and further, reinforcing fibers for connecting the upper and lower molds to the axis of the mandrel 300, that is, to the axis of the bicycle handlebar. Carbon fiber reinforced prepreg 1 arranged in 90 ° direction
02A ₁ is wound in order. Further, in this embodiment, the glass fiber cloth prepreg 107 using the glass fiber cloth as the reinforcing fiber is wound around the center portion of the handlebar 1 in the longitudinal direction over a predetermined length.

In this manner, the prepreg laminate 110C having a circular cross section is provided on the outer periphery of the mandrel 300.
Is formed.

As the matrix resin of each of the prepregs 101 to 107 described above, a thermosetting matrix resin such as an epoxy resin, an unsaturated polyester resin, a polyurethane resin, a diallyl phthalate resin or a phenol resin can be used. In addition, the curing temperature of the prepreg is 50
A curing agent and other imparting agents, for example, a flexibility imparting agent and the like are appropriately added so that the temperature is from about 200 ° C.

Next, the prepreg laminate 110C wound around the mandrel 300 is extracted from the mandrel 300, and cuts 112 are made in the longitudinal direction as shown in FIG. 1 (A). Next, the cut 112 is placed on the upper side of the lower mold as shown in FIG. 1 (B) so that it fits on the inner surface of the prepreg laminate 110A.

A prepreg laminate 1 is attached to the lower molding die 200A.
When 10C is installed, prepreg laminate 110C
The inner pressure tube 310 (FIG.
) Is inserted along the longitudinal direction of the prepreg laminate 110C.

Next, after the cuts 112 of the prepreg laminate 110C are largely wrapped in the longitudinal direction, that is, the inside diameter of the prepreg laminate 110C is reduced so as to be smaller than the mandrel outside diameter, and the cut portions are overlapped. After combining, as shown in FIG. 2, the upper molding die 200B in which the prepreg laminated body 110B is laminated and arranged over a half circumference is overlapped with the lower molding die 200A, and both molding dies are fixed with a tightening bolt or the like. At this time, the inner surface of the prepreg laminate 110B of the upper molding die 200B is the prepreg laminate 11
0C, and both prepreg laminates 110A, 110 of the upper molding die 200A and the lower molding die 200B.
The mating end face portions of B facing each other should be pressed sufficiently to prevent a gap from being formed between both end faces.

Next, the molding surfaces 200A ₀ , 2 of both molds are formed.
00B ₀ and the outer surfaces of the prepreg laminates 110A and 110B are decompressed by a normal method, and at the same time, the inner pressure tube 310 is pressurized to inflate the inner pressure tube 310,
Prepreg laminate 110C and prepreg laminate 110
A and 110B are molded surfaces 200A ₀ and 200B of both molds.
_Press to ₀ . At the same time, each prepreg is heated and cured.

At this time, the molding surfaces 200A ₀ of both molding dies,
The temperature rise and pressurization control are performed so as to completely eliminate air between 200B ₀ and the outer surfaces of the prepreg laminates 110A and 110B and from the laminate boundary portion of each prepreg to prevent the occurrence of voids. Curing and molding is performed at a temperature of 130 ° C.

Among the handlebars for bicycles thus manufactured, the outer diameter is uniformly formed, and the wall thickness of the pipe can be finished as desired, thereby producing a product of constant quality. We were able to.

According to the results of the research conducted by the present inventor, the carbon fiber cloth prepreg 104, which is the outermost layer of the prepreg laminates 110A and 110B, has a matrix resin content of 50 to 65% by weight in this embodiment. It has been found that it is preferable to use a resin-rich prepreg, which makes it possible to effectively prevent the occurrence of voids in this portion.

Further, if necessary, the molding surfaces 2 of both molding dies.
00A ₀ , 200B ₀ and prepreg laminates 110A, 1
By placing a logo film, a brand name printed surface film or a colored film (not shown) between the resin rich prepreg 104 and the 10B resin prepreg 104, the product can be fashionable. Can be given. At this time, heat-resistant printed paper, cloth, resin-penetrable plastic film, or the like is suitable as the covering film.

In the embodiments described above, the case where the handlebar with a barbet for a bicycle is manufactured has been described, but the present invention is not limited to this, and for example, a front fork of a bicycle, a competition (sliding, etc.), etc. Ski pole,
For corrosion prevention (underground, undersea, etc.) such as corner pipes,
Various curved pipes curved in the axial direction can be suitably manufactured.

[0032]

As described above, according to the method of manufacturing a curved pipe of the present invention, the bending strength, elasticity and rigidity of the manufactured curved pipe are significantly improved. Such various curved pipes curved in the axial direction can be manufactured extremely efficiently. Furthermore, according to the manufacturing method of the present invention, the inner diameter of the curved pipe is uniformly formed, and the wall thickness of the pipe can be always finished to a predetermined value.
It is possible to manufacture products of constant quality, and
It is possible to accurately control the strength and rigidity of the manufactured product.

[Brief description of drawings]

FIG. 1 is a process explanatory view illustrating a method for manufacturing a curved pipe according to the present invention.

FIG. 2 is a cross-sectional view of a molding die used in the present invention.

FIG. 3 is a plan view of a mold used in the present invention in a separated state and a side view of a combined state.

FIG. 4 is a diagram showing an example of a blank of a prepreg used.

FIG. 5 is a plan view of an example of a handlebar with a return handle for a bicycle.

FIG. 6 is a transverse cross-sectional view showing a laminated structure of a handlebar with a return member for a bicycle.

[Explanation of symbols]

 1 Handlebar with return for bicycle 101-107 Fiber reinforced prepreg 200 Mold 300 Mandrel 310 Internal pressure tube

Claims (1)

[Claims] 1. A step of (a) preparing a half-divided molding die comprising a lower molding die and an upper molding die, and subjecting the molding surfaces of the separated lower molding die and upper molding die to a mold release treatment, (B) A step of laminating a predetermined number of fiber reinforced prepregs on the respective molding surfaces of both the molding dies to form a prepreg laminate having a semicircular cross section, (c) On the other hand, the mandrel subjected to the mold release treatment Wrap a specified number of reinforced prepregs and stack them,
A step of forming a prepreg laminate having a circular cross section,
(D) Next, a step of extracting the circular prepreg laminate from the mandrel and making a cut in the longitudinal direction of the prepreg laminate, (e) the circular prepreg laminate being cut so that the cut is on the top. A step of installing in conformity with the inner surface of the semicircular prepreg laminate of the lower mold, (f) at the center position of the circular prepreg laminate,
A step of inserting and arranging a release-treated inner pressure tube along the longitudinal direction of the prepreg laminate, (g) a step of overlapping cuts of the circular prepreg laminate with a cut part along the longitudinal direction, h) The upper mold is superposed on the lower mold so that the inner surface of the semi-circular prepreg laminate of the upper mold fits the outer surface of the circular prepreg laminate, and both molds are fixed. Process,
(I) a step of decompressing between the molding surfaces of both molds and the outer surface of the semi-circular prepreg laminate and between the prepregs to prevent generation of voids, (j) at the same time, in the internal pressure tube And inflating the inner pressure tube, and pressing the circular prepreg laminate and the semi-circular prepreg laminate against the molding surfaces of both molds to heat and cure each prepreg. And a method for manufacturing a curved pipe.