JP2015187458A - Composite component, metho of manufacturing the same, rack bar, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite component which has light weight and high bending strength, a method of manufacturing the composite component, a rack bar, and a method of manufacturing the rack bar.SOLUTION: A rack bar 1 as a composite component is equipped with metallic members 2 and 3 which include cylindrical hollow portions 9 and 13; a tube 4 which includes end portions 41 and 42 adhered to inner peripheries 9a and 13a of the hollow portions 9 and 13; and a hollow bag body 5 which is fitted with an inner periphery 4a of the tube 4, and can be pressurized and expanded from the inside. A recession/projection engaging portion for preventing slipping-off is included, in which the inner peripheries 9a and 13a of the hollow portions 9 and 13 of the metallic members 2 and 3 and outer peripheries 41a and 42a of the end portions 41 and 42 of the tube 4 are engaged with each other. The tube 4 is made from a CFRP including resin adhered to the inner peripheries 9a and 13a of the hollow portions 9 and 13 of the metallic members 2 and 3 due to thermal hardening.

Description

  The present invention relates to a composite part, a manufacturing method thereof, a rack bar, and a manufacturing method thereof.

In Patent Literature 1, a male screw formed on an outer peripheral surface of a boss portion of a joint member is screwed into a female screw formed on an inner circumference of the FRP cylindrical member, thereby joining the FRP cylindrical member and the joint member. Members have been proposed.
In Patent Document 2, a metal core having a rack tooth portion and a small-diameter portion machined in an intermediate portion in the axial direction, and a carbon fiber reinforced plastic outer shell formed around the small-diameter portion of the metal core and around the end portion on the small-diameter portion side, Racks containing are proposed.

JP 2010-107020 A JP 2013-154807 A

In Patent Document 1, the outer diameter of the boss of the joint member becomes a small diameter, and the bending strength of the power transmission member may be lowered.
In Patent Document 2, since the heavy metal core extends the entire length in the axial direction of the rack, the weight of the rack becomes heavy.
Accordingly, an object of the present invention is to provide a composite part having a light weight and high bending strength, a manufacturing method thereof, a rack bar, and a manufacturing method thereof.

  In order to achieve the object, the invention according to claim 1 is fixed to the metal member (2, 3) including the cylindrical hollow portion (9, 13) and the inner periphery (9a, 13a) of the hollow portion. A tube (4) including the end portions (41, 42), and a cylindrical hollow bag body (5) which is fitted to the inner periphery (4a) of the tube and can be pressurized and expanded from the inside, The inner periphery of the hollow portion of the metal member and the outer periphery of the end portion of the tube include concave and convex engaging portions (19a, 19b; 20a and 20b) for engaging with each other, and the tube Provides a composite part (1) made of CFRP containing a resin fixed to the inner periphery of the hollow portion of the metal member by thermosetting.

According to a second aspect of the present invention, the concave-convex engaging portion may be provided on the inner periphery of the hollow portion of the metal member, and may include a knurl extending in a direction intersecting the axial direction.
According to a third aspect of the present invention, the metal member may include an insertion hole (15) that faces the surface of the hollow bag body.
According to a fourth aspect of the present invention, the hollow bag body may include an elastic stopper (18) that can pierce the gas supply needle (17) through the insertion hole.
The invention of claim 5 is the rack bar (1) as the composite part, wherein the metal member has a first hollow portion (9) and a cylindrical first having a rack (6) formed on the outer periphery. Including a metal member (2) and a cylindrical second metal member (3) having a second hollow portion (13), wherein one of the first metal member and the second metal member is the hollow The tube includes an insertion hole (15) facing the surface of the bag, and the end of the tube includes a first end (41) fixed to an inner periphery of the first hollow portion and an inner portion of the second hollow portion. And a rack bar including a second end (42) secured to the periphery.

  In the invention of claim 6, a prepreg layer (21) in which a prepreg formed by impregnating a thermosetting resin into a reinforcing fiber mainly composed of carbon fiber is wound around the outer periphery of a cylindrical hollow bag body is provided with a hollow portion. A sealed hollow space (S) formed by a cylindrical metal member that is provided with a retaining process on the inner periphery of the hollow part and a hollow mold (22) disposed adjacent to the metal member The step of pressurizing the prepreg layer to the inner periphery of the hollow space by inflating with the pressure expansion of the hollow bag body, and heating the resin of the prepreg layer to a predetermined thermosetting temperature. A step of forming a tube integral with the metal member by thermosetting, and a step of obtaining a composite part by removing the hollow mold from the tube in a state where the pressure of the hollow bag body is released. Providing a method of manufacturing composite parts including To.

  According to the seventh aspect of the present invention, there is provided a prepreg layer in which a prepreg formed by impregnating a reinforcing fiber mainly composed of carbon fiber with a thermosetting resin is wound around an outer periphery of a cylindrical hollow bag body, and having a first hollow portion. A cylindrical metal member having a cylindrical first metal member and a second hollow portion that are provided with a retaining process on the inner periphery of the first hollow portion, and a retaining shape that is provided on the inner periphery of the second hollow portion. In the sealed hollow space formed by the second metal member and the hollow mold having the third hollow portion (22a) and disposed between the two metal members, with the pressure expansion of the hollow bag body The step of pressurizing the prepreg layer to the inner periphery of the hollow space by inflating, and heating the resin of the prepreg layer to a predetermined thermosetting temperature to thermoset the tube integral with both metal members. And forming the tube in a state in which the pressurization of the hollow bag body is released By removing the al said hollow, to provide a method of manufacturing a rack bar comprising the steps of obtaining a rack bar, a.

According to the composite part of the first aspect of the present invention, the CFRP tube containing the resin fixed to the inner periphery of the hollow portion of the metal member is prevented from coming off with high retaining strength by engaging the metal member with the unevenness. ing. Therefore, a high bending strength can be achieved by using a large-diameter metal member firmly connected to the tube while reducing the weight with a CFRP tube.
That is, when the male threaded portion at the end of the metal member is screwed into a CFRP tube and the metal member and the tube are fastened as in the prior art, the male threaded portion has the smallest diameter, and therefore when subjected to a bending load. There is a risk of destruction at the male thread. On the other hand, in the present invention, since there is no small-diameter male screw portion and a large-diameter metal member firmly connected to the tube is used, it is possible to suppress the metal member from being broken against a bending load. High bending strength can be obtained.

In addition, during the manufacture of the composite part, the prepreg layer is pressed in the inner periphery of the hollow part of the metal member while the prepreg layer wound around the outer periphery of the hollow bag body is pressed by the pressure expansion of the cylindrical hollow bag body. It becomes possible to form a tube integral with the metal member by thermally curing the resin of the layer.
According to the invention of claim 2, by using a knurling that extends in a direction intersecting the axial direction as the concave and convex engaging portion for retaining, the tube has a large diameter and a high bending strength. Connected with high retaining strength (connection strength). Therefore, high bending strength can be achieved as a whole composite part.

According to the invention of claim 3, during the manufacture of the composite part, gas can be supplied to the hollow bag body from the outside of the metal member through the insertion hole of the metal member.
According to the invention of claim 4, at the time of manufacturing the composite part, the gas supply needle that has passed through the insertion hole of the metal member is pierced through the elastic plug of the hollow bag body, so that the hollow bag body is formed from the outside of the metal member. Gas can be supplied easily.

  According to the invention of claim 5, both metal members having a diameter larger than that of the tube and having strength are arranged at the end of the tube, and CFRP containing a resin fixed to the inner periphery of the hollow portion of both metal members The manufactured tube and the two metal members are prevented from coming off by the concave-convex engagement by the mutual concave-convex engaging portions. Therefore, it is possible to obtain a rack bar having high bending strength while reducing the weight. In addition, during the production of the rack bar, by pressing and expanding the cylindrical hollow bag body, the prepreg layer wound around the outer periphery of the hollow bag body is pressurized to the inner periphery of the hollow part of both metal members, It is possible to form a tube integral with both metal members by thermosetting the resin of the prepreg layer.

  According to the invention of claim 6, by inflating a cylindrical hollow bag body having a prepreg layer wound in a cylindrical shape on the outer periphery in a hollow space formed by a metal member and a hollow mold, The prepreg layer is pressurized to the inner periphery of the hollow space. Next, the resin of the prepreg layer is thermally cured to form a tube integral with the metal member. Next, by removing the hollow mold from the tube in a state where the pressurization of the hollow bag body is released, it is possible to manufacture a composite component that is lightweight and has high bending strength.

  According to the invention of claim 7, by inflating a cylindrical hollow bag having a prepreg layer wound in a cylindrical shape on the outer periphery in a hollow space formed by both metal members and a hollow mold. The prepreg layer is pressurized to the inner periphery of the hollow space. Next, both the metal member and the tube are integrated by thermally curing the resin of the prepreg layer. Next, a rack bar having a light weight and a high bending strength can be manufactured by removing the hollow mold in a state where the pressure of the hollow bag body is released.

It is a schematic side view of the rack bar as a composite part of one embodiment of the present invention. It is an expanded sectional view of the principal part of a rack bar. (A) And (b) is a general | schematic expanded sectional view of the principal part of a 1st metal member and a 2nd metal member. (A) is sectional drawing of the retaining structure of a 1st metal member and a CFRP tube, (b) is sectional drawing of the retaining structure of a 2nd metal member and a CFRP tube. (A)-(c) is a schematic sectional drawing which shows the manufacturing process of a rack bar in order. (A)-(c) is a schematic sectional drawing which shows the manufacturing process of a rack bar in order following the process of FIG.5 (b).

  FIG. 1 is a schematic side view of a rack bar as a composite part according to an embodiment of the present invention. As shown in FIG. 1, the rack bar 1 (composite part) includes a first metal member 2, a second metal member 3, and a CFRP tube 4 that connects the first metal member 2 and the second metal member 3. And a hollow bag body 5 accommodated in the tube 4.

  The first metal member 2 includes a shaft portion 7 in which a rack 6 is formed on the outer periphery (corresponding to a part of the outer periphery 2a of the first metal member 2), a diameter-enlarged portion 8 provided at one end of the shaft portion 7, A first hollow portion 9 provided in the enlarged diameter portion 8 and a joint element 10 provided at the other end of the shaft portion 7 are provided.

  The first metal member 2 is preferably subjected to a quenching process such as a carburizing quenching process or an induction quenching process in order to suppress wear of the rack 6. The first hollow portion 9 is a cylindrical hole extending in the axial direction. The joint element 10 is a part of a joint for connecting to one tie rod (not shown).

  The second metal member 3 includes a shaft portion 11, an enlarged diameter portion 12 provided at one end of the shaft portion 11, a second hollow portion 13 provided in the enlarged diameter portion 12, and the other end of the shaft portion 11. And a coupling element 14 provided. The joint element 14 is a part of a joint for connecting to the other tie rod (not shown). The second hollow portion 13 is a cylindrical hole extending in the axial direction.

  The tube 4 includes a first end portion 41 fixed to the inner periphery 9 a of the first hollow portion 9 and a second end portion 42 fixed to the inner periphery 13 a of the second hollow portion 13. The tube 4 includes carbon fibers and a resin (for example, an epoxy resin that is a thermosetting resin as a matrix resin) fixed to the inner circumferences 9a and 13a of the hollow portions 9 and 13 by thermosetting.

  One of the first metal member 2 and the second metal member 3, for example, the first metal member 2 includes an insertion hole 15 that faces the surface of the hollow bag body 5 in the tube 4. The entrance of the insertion hole 15 is closed by a sealing member 16 such as a rubber plug, for example, to prevent entry of moisture or the like from the outside. A known sealing agent may be used as the sealing member 16.

  The hollow bag body 5 has a cylindrical shape, is fitted to the inner periphery 4a of the tube 4, and can be pressurized and expanded from the inside. The hollow bag body 5 is provided with an elastic plug 18 through which the gas supply needle 17 can be inserted through the insertion hole 15. The elastic stopper 18 is, for example, a rubber stopper, and may be formed integrally with the hollow bag body 5 from a single material, or may be provided as a separate member from the hollow bag body 5 and fixed integrally therewith. Good.

  As shown in FIG. 3A and FIG. 4A, the inner periphery 9a of the first hollow portion 9 of the first metal member 2 and the outer periphery 41a of the first end portion 41 of the tube 4 are engaged with each other. The concave-convex engaging portions 19a and 19b for preventing the removal are included.

  As shown in FIGS. 3B and 4B, the inner periphery 13 a of the first hollow portion 13 of the second metal member 3 and the outer periphery 42 a of the second end portion 42 of the tube 4 are engaged with each other. The concave-convex engaging portions 20a, 20b for retaining are included.

  As shown in FIGS. 3A and 3B, the concave and convex engaging portions 19a and 20a provided on the inner peripheries 9a and 13a of the hollow portions 9 and 13 of the metal members 2 and 3 intersect the axial direction. It may be a knurl that extends in the direction of movement. The knurling may be a knurling extending in two directions intersecting each other (an iris knurling) or a knurling extending only in one direction. Further, the concave and convex engaging portions 19a and 20a may be concave and convex formed using shot blasting, etching with acid or laser, or the like. In consideration of processing costs and the like, iris concaves are preferable as the concave and convex engaging portions 19a and 20a.

  Next, FIGS. 5A to 5C and FIGS. 6A to 6C sequentially show the manufacturing process of the rack bar 1.

  First, as shown in FIG. 5A, by winding a prepreg obtained by impregnating a reinforcing fiber mainly composed of carbon fiber with a thermosetting resin as a matrix resin around an outer periphery 5a of a cylindrical hollow bag body 5. The cylindrical prepreg layer 21 wound around the outer periphery 5a of the hollow bag 5 is formed. The prepreg is laminated and used as necessary.

  As the carbon fiber, any polyacrylonitrile (PAN) -based or pitch-based carbon fiber typified by “Torayca” (registered trademark) T300 or “Torayca” (registered trademark) T700 can be used. Further, a part of the carbon fiber may be replaced with glass fiber or aramid fiber to constitute the reinforcing fiber.

  As the prepreg, for example, a woven fabric sheet of reinforcing fibers or a unidirectional reinforcing material (so-called UD material) in which reinforcing fibers are aligned in one direction is used. The woven sheet is formed, for example, by weaving a bundle of reinforcing fibers (tow) extending linearly in a predetermined direction and a bundle of reinforcing fibers extending in a direction intersecting the bundle with a plain weave. The weaving method of the woven sheet is not limited to plain weaving, and general weaving methods such as twill weaving, satin weaving, and multiaxial weaving can be applied.

  As the thermosetting resin as the matrix resin, an epoxy resin, a polyimide resin, a bismaleimide resin, a phenol resin, or the like can be used, and an epoxy resin is preferably used.

  Next, as shown in FIG. 5 (b), the pair of end portions of the hollow bag body 5 in which the cylindrical prepreg layer 21 is formed on the outer periphery 5 a are connected to the first hollow portion 9 and the second hollow portion of the first metal member 2. Each is inserted into the second hollow portion 13 of the metal member 3.

  Next, as shown in FIGS. 5B and 5C, a hollow mold 22 that covers the outer periphery 21 a of the cylindrical prepreg layer 21 is disposed between the first metal member 2 and the second metal member 3. As shown in FIG. 5 (c), the first hollow part 9 of the first metal member 2, the second hollow part 13 of the second metal member 3, and the third hollow part 22 a of the hollow mold 22 are sealed. A hollow space S is formed.

  As shown in FIG. 5B, the hollow mold 22 is a divided mold that is divided into a plurality of parts in the circumferential direction. The hollow mold 22 is attached to the outer periphery 21 a of the cylindrical prepreg layer 21 from the radial direction, It is possible to remove from the outer periphery 4b [see FIG. 6B] in the radial direction.

  The inner periphery 9a of the first hollow portion 9 of the first metal member 2 and the inner periphery 13a of the second hollow portion 13 of the second metal member 2 have the unevenness shown in FIGS. 3 (a) and 3 (b). The engaging portions 19a and 20a are processed in advance.

  Next, as shown in FIG. 6 (a), the gas supply needle 17 inserted through the insertion hole 15 of the first metal member 2 is pierced through the elastic plug 18 of the hollow bag 5 and sent from a pump (not shown) or the like. A gas to be supplied (for example, air or nitrogen gas as an inert gas) is injected into the hollow bag 5 through the gas supply needle 17. Thereby, the prepreg layer 21 is pressurized to the inner periphery Sa of the hollow space S by inflating the hollow bag body 5 in the hollow space S.

  Next, as shown in FIG. 6B, the resin (for example, epoxy resin) of the prepreg layer 21 is heated to a predetermined thermosetting temperature and is thermally cured while maintaining the pressurized state of the hollow bag body 5. The resin is fixed to the inner peripheries 9a and 13a of the hollow portions 9 and 13 of the metal members 2 and 3, respectively. Thereby, the tube 4 integral with both the metal members 2 and 3 is formed.

  Next, after cooling the whole, as shown in FIG. 6C, the rack bar 1 is obtained by removing the hollow mold 22 from the tube 4 in a state in which the pressurization of the hollow bag body 5 is released. After that, as shown in FIG. 1, a sealing member 16 that closes the inlet is attached to the insertion hole 15.

  According to the composite part (rack bar 1) of the present embodiment, the metal members 2 and 3 having larger diameter and strength than the tube 4 are disposed at the end portions 41 and 42 of the tube 4. In addition, the CFRP tube 4 containing a resin fixed to the inner periphery of the hollow portions 9 and 13 of the metal members 2 and 3 and the metal members 2 and 3 are connected to the concave and convex engaging portions 19a and 19b; It is prevented from coming off by the concave-convex engagement by 20b, and is connected with high retaining strength (connection strength). Therefore, a high bending strength can be achieved by using the large-diameter metal members 2 and 3 firmly connected to the tube 4 while reducing the weight with the CFRP tube 4.

  That is, when the male threaded portion at the end of the metal member is screwed into a CFRP tube and the metal member and the tube are fastened as in the prior art, the male threaded portion has the smallest diameter, and therefore when subjected to a bending load. There is a risk of destruction at the male thread. On the other hand, in the present invention, since the large-diameter metal members 2 and 3 that are firmly connected to the tube 4 without the small-diameter male thread portion are used, the metal members 2 and 3 are broken against the bending load. It is possible to obtain a high bending strength.

  Further, when the composite part (rack bar 1) is manufactured, the prepreg layer 21 wound around the outer periphery 5a of the hollow bag body 5 is made hollow by the metal members 2 and 3 by the pressure expansion of the cylindrical hollow bag body 5. With the pressure applied to the inner peripheries 9a and 13a of the portions 9 and 13, the resin of the prepreg layer 21 can be thermoset to form the tube 4 integrated with the metal members 2 and 3.

  Further, by using knurling extending in the direction intersecting the axial direction as the retaining portions 19a and 20a on the metal members 2 and 3 side, the tube 4 has a large diameter and high bending strength. And are connected with high retaining strength (connection strength). Therefore, high bending strength can be achieved as a whole composite part (rack bar 1).

  Since the insertion hole 15 is provided in the first metal member 2, gas is supplied from the outside of the first metal member 2 into the hollow bag body 5 through the insertion hole 15 of the first metal member 2 when manufacturing the composite part. can do.

  Specifically, at the time of manufacturing the composite part (rack bar 1), the gas supply needle 17 that has passed through the insertion hole 15 of the first metal member 2 is pierced through the elastic plug 18 of the hollow bag body 5, thereby 1 Gas can be easily supplied into the hollow bag body 5 from the outside of the metal member 2. The insertion hole 15 may be provided in the second metal member 3.

  In addition, the first metal member 2 and the second metal member 3 that are larger in diameter and stronger than the tube 4 are disposed at both ends 41 and 42 of the tube 4. Also, a CFRP tube 4 containing a resin fixed to the inner periphery 9a of the first hollow portion 9 of the first metal member 2 and the inner periphery 13a of the second hollow portion 13 of the second metal member 13, and both metal members 2 and 3 are prevented from coming off with high retaining strength by the concave-convex engagement. Therefore, the rack bar 1 having high bending strength can be obtained by using the large-diameter metal members 2 and 3 firmly connected to the tube 4 while reducing the weight with the CFRP tube 4. Further, at the time of manufacturing the rack bar 1, the prepreg layer 21 wound around the outer periphery 5 a of the hollow bag body 5 by the pressure expansion of the cylindrical hollow bag body 5 is changed into the hollow portions 9, 2 of both metal members 2, 3. In a state in which the inner circumferences 9a and 13a of 13 are pressurized, the resin of the prepreg layer 21 can be thermoset to form the tube 4 integral with both the metal members 2 and 3.

  Moreover, even if the gas in the hollow bag 5 leaks out in the long-term use, if it is air or nitrogen gas, there is no risk of adverse effects such as rusting of metal parts. In particular, nitrogen gas is preferable because it is an inert gas.

  According to the manufacturing method of the composite part (rack bar 1) of the present embodiment, the prepreg layer 21 wound around the outer periphery 5a of the cylindrical hollow bag 5 is formed by both the metal members 2 and 3 and the hollow mold 22. In the hollow space S to be formed, the prepreg layer 21 is pressurized to the inner circumference Sa of the hollow space S by being expanded as the hollow bag body 5 is pressurized and expanded. Subsequently, both the metal members 2 and 3 and the tube 4 are integrated by thermosetting the resin of the prepreg layer 21. Next, by removing the hollow mold 22 in a state where the pressurization of the hollow bag body 5 is released, the rack bar 1 as a composite part that is lightweight and has high bending strength can be manufactured.

  In the present embodiment, the description has been given based on an example in which the composite part is a rack bar. However, the present invention is not limited thereto, and the present invention is applied to a composite part in which a metal member is fixed to only one end of a tube made of CFRP. You may apply. In addition, the present invention can be variously modified within the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 ... Rack bar (composite part), 2 ... 1st metal member, 3 ... 2nd metal member, 4 ... Tube, 4a ... Inner periphery, 4b ... Outer periphery, 5 ... Hollow bag body, 5a ... Outer periphery, 6 ... Rack, DESCRIPTION OF SYMBOLS 7 ... Shaft part, 8 ... Diameter expansion part, 9 ... 1st hollow part, 9a ... Inner circumference, 10 ... Joint element, 11 ... Shaft part, 12 ... Diameter expansion part, 13 ... 2nd hollow part, 13a ... Inner circumference , 14 ... Joint element, 15 ... Insertion hole, 17 ... Gas supply needle, 18 ... Elastic stopper, 19a, 19b ... Concave / engagement part, 20a, 20b ... Concave / engagement engagement part, 21 ... Pre-preg layer, 22 ... Hollow type, 22a ... third hollow part, S ... hollow space, Sa ... inner circumference

Claims (7)

A metal member including a cylindrical hollow portion;
A tube including an end fixed to the inner periphery of the hollow portion;
A cylindrical hollow bag body fitted to the inner periphery of the tube and capable of being pressurized and expanded from the inside;
The inner periphery of the hollow portion of the metal member and the outer periphery of the end portion of the tube include a concave / convex engaging portion for retaining the concave / convex engagement with each other,
The tube is a composite part made of CFRP containing a resin fixed to the inner periphery of the hollow portion of the metal member by thermosetting.   2. The composite part according to claim 1, wherein the concave-convex engaging portion is provided on an inner periphery of the hollow portion of the metal member and includes a knurl extending in a direction intersecting the axial direction.   3. The composite part according to claim 1, wherein the metal member includes an insertion hole facing the surface of the hollow bag body.   4. The composite part according to claim 3, wherein the hollow bag body includes an elastic stopper capable of inserting a gas supply needle through the insertion hole. A rack bar as a composite part according to any one of claims 1 to 4,
The metal member includes a cylindrical first metal member having a first hollow portion and a rack formed on the outer periphery, and a cylindrical second metal member having a second hollow portion,
Either one of the first metal member and the second metal member includes an insertion hole facing the surface of the hollow bag body,
The end portion of the tube is a rack bar including a first end portion fixed to an inner periphery of the first hollow portion and a second end portion fixed to an inner periphery of the second hollow portion. A prepreg layer in which a prepreg formed by impregnating a reinforcing fiber mainly composed of carbon fiber with a thermosetting resin is wound around the outer periphery of a cylindrical hollow bag body has a hollow portion and is pulled out to the inner periphery of the hollow portion. In the sealed hollow space formed by the cylindrical metal member subjected to the stop processing and the hollow mold disposed adjacent to the metal member, the hollow bag body is inflated with the pressure expansion. By pressurizing the prepreg layer to the inner periphery of the hollow space,
Forming a tube integral with the metal member by heating and curing the resin of the prepreg layer to a predetermined thermosetting temperature;
Obtaining a composite part by removing the hollow mold from the tube in a state where the pressurization of the hollow bag body is released. A prepreg layer in which a prepreg formed by impregnating a reinforcing fiber mainly composed of carbon fiber with a thermosetting resin is wound around the outer periphery of a cylindrical hollow bag body has a first hollow portion, A cylindrical second metal member, which has a cylindrical first metal member and a second hollow portion, the inner periphery of which is provided with a retaining process, and a cylindrical second metal member, which is provided with a retaining process on the inner periphery of the second hollow portion. The prepreg layer is expanded by the pressure expansion of the hollow bag body in a sealed hollow space formed by a hollow mold having three hollow portions and disposed between both metal members. Pressurizing the inner periphery of the hollow space;
Forming a tube integral with both metal members by heating and curing the resin of the prepreg layer to a predetermined thermosetting temperature;
And a step of obtaining a rack bar by removing the hollow mold from the tube in a state where the pressurization of the hollow bag body is released.

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