JP2015131423A - Method of manufacturing bar-like component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a bar-like component, which is capable of improving strength of the bar-like component while reducing a manufacturing cost of the bar-like component in the case of constituting the bar-like component by connecting a pipe made of carbon fiber-reinforced resin with a metal component.SOLUTION: A bar-like component 22 includes a pipe 10 and metal components 17, 18. A method of manufacturing the bar-like component 22 includes: a process of winding a carbon fiber 25 and a thermoplastic resin fiber 26 round a core material including a metal ring 16 which has an outer peripheral surface 16A to which surface roughening work is applied; a process of melting the thermoplastic resin fiber 26 by heating the thermoplastic resin fiber 26 wound round the outer peripheral surface of the core material while pressurizing the fiber 26; a process of forming the pipe 10 in which end parts 10A, 10B are externally fitted to the outer peripheral surface 16A, by cooling thermoplastic resin which is melted and impregnated into the carbon fiber 25; and a process of screw-fastening the metal components 17, 18 and the metal ring 16.

Description

  The present invention relates to a method for manufacturing a bar-shaped component that constitutes, for example, a vehicle steering apparatus.

  In the propeller shaft of Patent Document 1 below, a thin metal ring that is substantially equal to the inner diameter of the main body cylinder is attached to the inside of the end of the FRP (fiber reinforced plastic) main body cylinder. It is manufactured by press fitting a metal joint having an outer diameter larger than the inner diameter of the ring. During the press-fitting, the hard particles arranged on the outer peripheral surface of the thin ring bite into the inner surface of the FRP main body cylinder. As an application example of fiber reinforced plastic, as shown in Patent Document 2 below, a prepreg is wound around a metal core and laminated to form a carbon fiber reinforced plastic outer shell. A rack in which a rack tooth portion is formed by cutting the outer diameter surface is exemplified.

  On the other hand, in the rack manufacturing method of Patent Document 3 below, a filament bundle made of organic fibers is wound around a metal core while impregnating the liquid thermosetting resin, and then heated at the curing temperature of the thermosetting resin. And the cylindrical body joined to the outer periphery of a metal core is obtained by hardening thermosetting resin. A rack is manufactured by forming gear teeth on the cylindrical body.

Japanese Patent Laid-Open No. 7-91433 JP 2012-153314 A JP 2010-89524 A

  In the propeller shaft of Patent Document 1, since the outer peripheral surface of the thin ring bites into the inner surface of the fiber reinforced plastic main body cylinder due to the press-fitting of the thin ring and the joint, the fibers in the fiber reinforced plastic in the main body cylinder may be cut. is there. If the fiber is cut, the strength of the connecting portion between the main body tube and the joint may be reduced. Moreover, since the carbon fiber is cut when the outer diameter surface of the carbon fiber reinforced plastic outer shell is cut as in Patent Document 2, the strength of the rack may be reduced.

On the other hand, shortening of manufacturing time is always required in order to reduce manufacturing cost. However, in order to obtain a cylindrical body from a thermosetting resin like patent document 3, since a long time is required for hardening, there exists a possibility that manufacturing cost may increase.
The present invention has been made under such a background, and in the case of forming a bar-shaped part by connecting a pipe made of carbon fiber reinforced resin and a metal part, the manufacturing cost of the bar-shaped part can be reduced. It aims at providing the manufacturing method of the bar-shaped components which can improve intensity | strength, aiming.

  The invention according to claim 1 is a carbon fiber reinforced thermoplastic resin pipe (10), and metal parts (17, 18) fastened to ends (10A, 10B) in the axial direction (X) of the pipe. A metal ring (16) having an outer peripheral surface (16A) subjected to roughening with respect to the metal mandrel (24) extending in the axial direction. ) To prepare a core material (23) including the mandrel and the metal ring, and each of the carbon fiber (25) and the thermoplastic resin fiber (26) is arranged on the outer periphery of the core material. A step of winding around the surface (23A), a step of melting the thermoplastic resin fiber by heating the carbon fiber and the thermoplastic resin fiber wound around the outer peripheral surface of the core material, and Carbon fiber Cooling the impregnated thermoplastic resin to form the pipe with the end portion fitted and fixed to the outer peripheral surface of the metal ring; and only the mandrel of the core material from the pipe A method for manufacturing a bar-shaped part, comprising: a step of pulling out and a step of screwing the metal part and an inner peripheral surface (16B) of the metal ring.

  The invention according to claim 2 includes a pipe (10) made of carbon fiber reinforced thermoplastic resin, and metal parts (17, 18) fastened to ends (10A, 10B) in the axial direction (X) of the pipe. A metal ring (16) having an outer peripheral surface (16A) subjected to roughening with respect to the metal mandrel (24) extending in the axial direction. ) To prepare a core material (23) including the mandrel and the metal ring, and each of the carbon fiber (25) and the thermoplastic resin fiber (26) is arranged on the outer periphery of the core material. A step of winding around the surface (23A), a step of melting the thermoplastic resin fiber by heating and pressurizing the carbon fiber and the thermoplastic resin fiber wound around the outer peripheral surface of the core material, Carbon fiber Cooling the impregnated thermoplastic resin to form the pipe with the end portion fitted and fixed to the outer peripheral surface of the metal ring; and only the mandrel of the core material from the pipe A method for manufacturing a bar-shaped part, comprising: a step of pulling out and a step of screwing the metal part and an inner peripheral surface (16B) of the metal ring.

According to a third aspect of the present invention, in the step of winding the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material, a woven fabric sheet configured by combining the carbon fiber and the thermoplastic resin fiber with each other The method of manufacturing a bar-shaped part according to claim 1, comprising a step of winding (40) around the outer peripheral surface of the core member.
According to a fourth aspect of the present invention, in the step of winding the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material, the braid (37) configured by combining the carbon fiber and the thermoplastic resin fiber is used as the braid (37). It is a manufacturing method of the bar-shaped component in any one of Claims 1-3 including the process wound around the outer peripheral surface of a core material.

Invention of Claim 5 includes the process of forming in the internal peripheral surface of the said metal ring the internal thread part (19) screw-fastened by the external thread part (20) provided in the said metal component, It is characterized by the above-mentioned. The method for manufacturing a bar-shaped part according to any one of claims 1 to 4.
The invention according to claim 6 is characterized in that the bar-shaped part constitutes a rack bar (8) included in a rack-and-pinion type steering device (1). It is a manufacturing method of the bar-shaped component described in the above.

The invention according to claim 7 is characterized in that the pipe has a rack (15), and the rack is formed in a step of pressurizing the carbon fiber and the thermoplastic resin fiber. It is a manufacturing method of described bar-shaped components.
The invention according to claim 8 is the method for producing a bar-shaped part according to claim 6, characterized in that the metal part has a rack (15).

  In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

  According to the first aspect of the present invention, the bar-shaped part includes a pipe made of carbon fiber reinforced thermoplastic resin and a metal part fastened to an end portion in the axial direction of the pipe. Moreover, the core material prepared in the production of the bar-shaped part includes a mandrel extending in the axial direction, and a metal ring that is subjected to rough surface processing (unevenness processing) on the outer peripheral surface and is fitted on the mandrel. It is out. The carbon fiber and the thermoplastic resin fiber enter the concave portion of the outer peripheral surface of the metal ring without being cut halfway by being wound around the outer peripheral surface of the core material. Next, more carbon fibers and thermoplastic resin fibers enter the recesses by being heated while being pressurized. The thermoplastic resin in the thermoplastic resin fibers is solidified in a shape along the irregularities on the outer peripheral surface of the metal ring by being cooled after heating. Therefore, the end of the pipe can be in close contact with the outer peripheral surface of the metal ring. In addition, since the carbon fiber that has entered the recesses on the outer peripheral surface of the metal ring functions as a retaining ring, the pipe and the metal ring are firmly connected.

  Thereafter, only the mandrel of the core material is pulled out from the pipe, and a metal ring is fitted into the end of the pipe. Since the metal part and the metal ring are screw-fastened, the end of the pipe and the metal part can be securely and firmly fastened without applying extra force to the metal ring. Therefore, unlike the case where the metal part is press-fitted into the metal ring, since the outer peripheral surface of the metal ring does not bite into the pipe, the carbon fiber in the pipe is not cut, so the strength of the pipe is Not reduced.

Thus, the time required to form the pipe using the thermoplastic resin fibers is shorter than the curing time required when forming the pipe using the thermosetting resin. Therefore, the time required for processing can be shortened, and as a result, the manufacturing cost can be reduced.
As a result, when a bar-shaped part is configured by connecting a pipe made of carbon fiber reinforced resin and a metal part, the strength can be improved while reducing the manufacturing cost of the bar-shaped part.

Even in the case where the thermoplastic fiber is melted by heating and pressurizing the carbon fiber and the thermoplastic resin fiber as in the second aspect of the invention, the production of the bar-shaped part is performed in the same manner as in the first aspect. The strength can be improved while reducing the cost.
According to the invention described in claim 3, as the step of winding the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material, a woven sheet formed by combining the carbon fiber and the thermoplastic resin fiber with each other is used as the outer peripheral surface of the core material. Wrap around. Thereby, since the carbon fiber can be oriented in the axial direction of the pipe, the strength of the pipe against the stress in the axial direction can be improved. And since the pipe | tube can be made thin by reducing the frequency | count of winding a textile sheet around the outer peripheral surface of a core material by the part which can improve the intensity | strength of a pipe in this way, the weight reduction of bar-shaped components can be achieved.

  According to invention of Claim 4, as a process of winding carbon fiber and thermoplastic resin fiber around the outer peripheral surface of a core material, the braid formed by combining carbon fiber and thermoplastic resin fiber is wound around the outer peripheral surface of the core material. . Thereby, since carbon fiber and a thermoplastic resin fiber can be uniformly wound around the outer peripheral surface of a core material, a pipe with each uniform ratio of a carbon fiber and a thermoplastic resin fiber can be obtained.

According to the invention described in claim 5, regarding the screw fastening between the metal part and the inner peripheral surface of the metal ring, the male screw part provided on the metal part is connected to the female screw part formed on the inner peripheral surface of the metal ring. Screwed. The step of forming the female thread portion on the inner peripheral surface of the metal ring may be performed before the metal ring is fitted on the mandrel, or may be performed after the mandrel is pulled out from the pipe.
As in the sixth aspect of the invention, the bar-like component may constitute a rack bar included in a rack and pinion type steering device.

  According to invention of Claim 7, the pipe has a rack. Thereby, since the ratio of the pipe made of a carbon fiber reinforced thermoplastic resin in the rack bar can be increased, the weight of the rack bar can be reduced. In addition, the rack is not formed by cutting the pipe, but is formed when the carbon fiber and the thermoplastic resin fiber are pressed. The strength of can be improved.

  As in the invention described in claim 8, the metal component may have a rack.

FIG. 1 is a schematic front view of a steering apparatus 1 including a bar-like component 22 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the manufacturing process of the bar-shaped component 22. FIG. 3 is a diagram schematically showing the next step of FIG. FIG. 4 is a cross-sectional view schematically showing the core member 23 and the molded body 36 after the step of FIG. FIG. 5 is an enlarged view of a portion surrounded by an alternate long and short dash line in FIG. FIG. 6 is a schematic cross-sectional view showing the next step of FIG. FIG. 7 is a schematic cross-sectional view showing the next step of FIG. FIG. 8 is a schematic cross-sectional view showing the next step of FIG. FIG. 9 is an enlarged view of a portion surrounded by an alternate long and short dash line in FIG. FIG. 10 is a diagram in which the first modification is applied to FIG. FIG. 11 is a view showing a braid 37 of the second modification. FIG. 12 is a view showing a fabric sheet 40 of a third modification. FIG. 13 is a view showing the rack bar 8 of the fourth modified example and its periphery.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic front view of a steering apparatus 1 including a bar-like component 22 according to an embodiment of the present invention.
Referring to FIG. 1, steering device 1 mainly includes a steering member 2, a steering shaft 3, an intermediate shaft 5, a pinion shaft 7, a rack bar 8, and a housing 9.

For example, a steering wheel can be used as the steering member 2. One end of a steering shaft 3 is connected to the steering member 2. The other end of the steering shaft 3 and one end of the intermediate shaft 5 are connected by a universal joint 4. Further, the other end of the intermediate shaft 5 and one end of the pinion shaft 7 are connected by a universal joint 6.
A pinion 14 is integrally provided on the outer peripheral surface of the other end of the pinion shaft 7. The rack bar 8 has a substantially cylindrical shape extending in the width direction of the vehicle (the left-right direction in FIG. 1). Here, the direction in which the rack bar 8 extends is defined as the axial direction X. The axial direction X is the same as the vehicle width direction (left-right direction in FIG. 1). With reference to the attitude of the steering device 1 in FIG. 1, a sign “X1” is attached to the left side in the axial direction X, and a sign “X2” is attached to the right side in the axial direction X.

A rack 15 that meshes with the pinion 14 is formed at one place on the circumference of the outer peripheral surface of the rack bar 8. The pinion 14 of the pinion shaft 7 and the rack 15 of the rack bar 8 mesh with each other to form a rack-and-pinion type steering mechanism A.
The rack bar 8 is accommodated in the housing 9. The housing 9 is a substantially cylindrical body fixed to the vehicle body. Both end portions of the rack bar 8 protrude to both sides of the housing 9, and tie rods 12 are coupled to the respective end portions via joints 11. Each tie rod 12 is connected to a corresponding steered wheel 13 via a corresponding knuckle arm (not shown).

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion of the rack bar 8 along the axial direction X by the pinion 14 and the rack 15. Thereby, the turning of the steered wheel 13 is achieved.
The rack bar 8 mainly includes a pipe 10, a metal ring 16, and cylindrical first metal parts 17 and second metal parts 18 which are two metal parts. Since the first metal part 17 and the second metal part 18 constitute the rack bar 8, strength and rigidity are required, so carbon steel such as S45C is used as a material. The second metal part 18 has a rack 15. The rack 15 is formed by cutting the second metal component 18.

The pipe 10 is made of a carbon fiber reinforced thermoplastic resin (so-called CFRTP) using a thermoplastic resin as a matrix resin, and has a substantially cylindrical shape extending in the axial direction X. The pipe 10 is provided, for example, on the left X1 of the rack bar 8 relative to the rack 15, and is disposed between the first metal component 17 and the second metal component 18 in the axial direction X.
The metal ring 16 is an annular shape extending in the axial direction X. The metal ring 16 is provided one by one (a total of two) according to the end 10A on the left X1 side and the end 10B on the right X2 side of the pipe 10, and the end of the end 10A and the end 10B. One is inserted through each (internal fitting). In other words, the end 10 </ b> A and the end 10 </ b> B of the pipe 10 are externally fitted to the outer peripheral surface 16 </ b> A of the metal ring 16. In the end portion 10 </ b> A and the end portion 10 </ b> B, the inner peripheral surface 10 </ b> C is expanded in diameter to substantially the same size as the outer peripheral surface 16 </ b> A of the metal ring 16. The diameter of the inner peripheral surface 16B of the metal ring 16 is substantially equal to the diameter of the inner peripheral surface 10C of the pipe 10 in the region between the end portions 10A and 10B.

  The first metal component 17 is adjacent to the joint 11 on the left side X1 as an end of the rack bar 8 on the left side X1 side. The first metal component 17 is adjacent to the end 10A of the pipe 10 from the left side. A small-diameter portion 21 is integrally provided at the end portion on the right X2 side of the first metal component 17. The small diameter portion 21 has a cylindrical shape extending in the axial direction X toward the right side X2. The small diameter portion 21 has a smaller diameter than the first metal component 17 (a portion other than the small diameter portion 21).

  In order to prevent the rack 15 from being worn, the second metal part 18 is subjected to a quenching process such as a carburizing quenching process or an induction quenching process. The second metal part 18 is adjacent to the end 10 </ b> B of the pipe 10 from the right side of the rack bar 8. The small diameter portion 21 described above is also provided integrally with the end portion of the second metal component 18 on the left X1 side. The small diameter portion 21 of the second metal part 18 has a cylindrical shape extending in the axial direction X toward the left X1. However, the small diameter portion 21 of the first metal component 17 and the small diameter portion 21 of the second metal component 18 may have different dimensions (diameter and length in the axial direction X). As will be described in detail later, the first metal component 17 and the second metal component 18 are fastened to the end portion (end portion 10A or 10B) of the pipe 10 at each small diameter portion 21. The connected pipe 10, the first metal part 17, and the second metal part 18 constitute a bar-like part 22 that extends in the axial direction X as a whole. This bar-shaped component 22 constitutes the rack bar 8. Since a part of the rack bar 8 is composed of the CFRTP pipe 10, the rack bar 8 is lighter than a case where the entire rack bar 8 is composed of a metal such as steel. CFRTP is also excellent in strength and rigidity. Therefore, the steering device 1 can be significantly reduced in weight while maintaining necessary strength and rigidity.

Next, a method for manufacturing such a bar-shaped part 22 will be described.
FIG. 2 is a schematic cross-sectional view showing the manufacturing process of the bar-shaped component 22. The posture of each member in FIG. 2 is the same as that in FIG. 1 (the same applies to FIGS. 3 to 10 and 13 described later).
With reference to FIG. 2, a core material 23 is prepared as an initial stage of manufacturing the bar-shaped part 22. The core material 23 is a member necessary for forming the cylindrical pipe 10. The core material 23 includes a mandrel 24 and the metal ring 16 described above. The mandrel 24 is made of metal and has a cylindrical shape extending in the axial direction X. The outer peripheral surface 24A of the mandrel 24 is subjected to a release process in advance. The outer peripheral surface 16A of the metal ring 16 is roughened in advance. Therefore, the outer peripheral surface 16 </ b> A has a large number of uneven portions 27. Examples of the rough surface processing here include iris knurl processing, key groove processing, spline processing, shot blast processing, acid etching, laser etching, and the like.

In the preparation step shown in FIG. 2, the core member 23 is prepared by fitting the metal ring 16 to the end portions on both sides in the axial direction X of the mandrel 24. The outer peripheral surface 23 </ b> A of the core member 23 includes an outer peripheral surface 16 </ b> A of each metal ring 16 and a portion of the outer surface 24 </ b> A of the mandrel 24 that protrudes from the metal ring 16.
FIG. 3 is a schematic cross-sectional view showing the next step of FIG.

Referring to FIG. 3, the material of pipe 10 described above uses carbon fiber 25 that is not impregnated with resin (so-called dry) and thermoplastic resin fiber 26.
As the carbon fiber 25, any carbon fiber typified by “Torayca” (registered trademark) T300 and “Torayca” (registered trademark) T700 can be used. It is also possible to replace part of the carbon fibers 25 with glass fibers or aramid fibers.

  As the thermoplastic resin fiber 26, any thermoplastic resin such as nylon 6, nylon 66, aromatic polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, polycarbonate resin, polypropylene resin, polyacetal resin, or the like can be used. it can. Since the rack bar 8 is used in the engine room of the vehicle and sometimes reaches a temperature close to 150 ° C., the thermoplastic resin fiber 26 has heat resistance that can be used even under such circumstances. It is desirable to use nylon 66 or polyetheretherketone resin that is easy to fiberize.

  Each of the carbon fiber 25 and the thermoplastic resin fiber 26 is prepared in a state of being wound around a cylindrical material supply member 31 such as a bobbin and a material supply member 32. The carbon fiber 25 is wound around the material supply member 31, and the thermoplastic resin fiber 26 is wound around the material supply member 32. The material supply members 31 and 32 are rotatably installed in the respective circumferential directions. By pulling the carbon fiber 25 and the thermoplastic resin fiber 26 from the material supply members 31 and 32, the material supply members 31 and 32 rotate in the respective circumferential directions, and the filamentous carbon fiber 25 and the thermoplastic resin fiber 26 are drawn out. .

  In the process shown in FIG. 3, each of the carbon fiber 25 and the thermoplastic resin fiber 26 is wound around the entire outer peripheral surface 23A of the core member 23 by, for example, a filament winding method. Specifically, the carbon fibers 25 and the thermoplastic resin fibers 26 drawn from the material supply members 31 and 32 are simultaneously supplied to approximately the same position in the axial direction X on the outer peripheral surface 23A. The carbon fiber 25 and the thermoplastic resin fiber 26 are wound around the outer peripheral surface 23A by a winding method (so-called hoop winding) along the circumferential direction of the core member 23 or a direction inclined in the axial direction X with respect to the circumferential direction.

When the step of winding the carbon fiber 25 and the thermoplastic resin fiber 26 around the outer peripheral surface 23 </ b> A shown in FIG. 3 is finished, the outer peripheral surface 23 </ b> A of the core material 23 is substantially carbon fiber in the axial direction X and the entire circumferential direction of the core material 23. 25 and the thermoplastic resin fiber 26 are wound up to a predetermined thickness.
Here, the entire carbon fiber 25 and thermoplastic resin fiber 26 wound around the outer peripheral surface 23 </ b> A of the core material 23 until a predetermined thickness is referred to as a molded body 36.

FIG. 4 is a cross-sectional view schematically showing the core member 23 and the molded body 36 after the step of FIG.
Referring to FIG. 4, molded object 36 is substantially cylindrical because it surrounds core member 23 in close contact with outer peripheral surface 24 </ b> A of mandrel 24 and outer peripheral surface 16 </ b> A of metal ring 16. Both ends in the axial direction X of the molded body 36 have a larger diameter than the portions other than both ends in the axial direction X of the molded body 36 by the thickness of the metal ring 16. On the other hand, the inner diameter of the molded body 36 in the portion is substantially equal to the inner diameter of each metal ring 16.

FIG. 5 is an enlarged view of a portion surrounded by an alternate long and short dash line in FIG.
Referring to FIG. 5, carbon fiber 25 or thermoplastic resin fiber 26 overlaps the same position in the axial direction X of outer peripheral surface 23 </ b> A of core material 23. The carbon fibers 25 and the thermoplastic resin fibers 26 are preferably arranged alternately in each of the axial direction X and the radial direction of the core material 23.

FIG. 6 is a schematic cross-sectional view showing the next step of FIG.
In the step shown in FIG. 6, the pipe 10 is formed by a press forming step.
Next, referring to FIG. 6, the object 36 is placed in the press mold 33 together with the core material 23. The press die 33 includes a lower first die 34 in FIG. 6 and an upper second die 35 in FIG. On the upper surface of the first mold 34 in FIG. 6, a concave portion 34 </ b> A having a substantially semicircular arc shape when viewed from the axial direction X is formed. On the lower surface of the second mold 35 in FIG. 6, a concave portion 35 </ b> A having a substantially semicircular arc shape when viewed from the axial direction X is formed. Both ends of the recesses 34A and 35A in the axial direction X have a larger diameter than the portions other than both ends of the recesses 34A and 35A in the axial direction X by the thickness of the metal ring 16. Therefore, the molded body 36 can be disposed in the press die 33 so as to fit into the recesses 34A and 35A.

After the molding 36 is placed in the press mold 33, the molding 36 is heated to near the melting point of the thermoplastic resin fiber 26 while being pressurized. The thermoplastic resin fiber 26 is melted by the pressurization and heating. The melted thermoplastic resin fiber 26 is impregnated in the adjacent carbon fibers 25 and between the adjacent carbon fibers 25.
Next, by cooling the press mold 33, the molded body 36 and the core material 23 arranged in the press mold 33 are cooled. The thermoplastic resin fiber 26 melted and impregnated in the carbon fiber 25 (the thermoplastic resin constituting the thermoplastic resin fiber 26) is solidified by being cooled in the press mold 33. Thereby, the to-be-molded body 36 is shape | molded along the outer peripheral surface 23A of the recessed part 34A and recessed part 35A of the press metal mold | die 33, and the core material 23, and the substantially cylindrical pipe 10 is formed. In this state, the thermoplastic resin fiber 26 previously dissolved is not in the form of a fiber, but forms a substantially cylindrical thermoplastic resin 28 as a whole. In this state, the pipe 10 is externally fitted to the outer peripheral surface 16A of the metal ring 16 at the ends 10A and 10B (specifically, externally fixed as described later).

Next, the first mold 34 and the second mold 35 of the press mold 33 are opened up and down in FIG. 6, and the pipe 10 and the core material 23 are taken out from the press mold 33.
Next, only the mandrel 24 of the core material 23 is pulled out from the pipe 10. As described above, since the outer peripheral surface 24A of the mandrel 24 has been subjected to a release treatment, the thermoplastic resin 28 is not bonded to the outer peripheral surface 24A of the mandrel 24 after the press molding process. Therefore, the mandrel 24 can be easily pulled out. At this time, in order to pull out the mandrel 24 more smoothly, it may be contracted by cooling. In that case, the force required to pull out the mandrel 24 from the pipe 10 is further reduced.

FIG. 7 is a schematic cross-sectional view showing the next step of FIG.
Referring to FIG. 7, in a state where mandrel 24 is pulled out from pipe 10, each metal ring 16 is in a state of being internally fitted to the corresponding one at end 10 </ b> A and end 10 </ b> B of pipe 10. ing. Moreover, it is preferable that a part of each metal ring 16 (for example, about 2 mm at the end in the axial direction X) protrudes outward from the end 10A and the end 10B of the pipe 10 in the axial direction X. . For this purpose, in the step of winding the carbon fiber 25 and the thermoplastic resin fiber 26 around the outer peripheral surface 23A of the core member 23, the carbon fiber 25 and the thermoplastic resin fiber 26 are not wound around the part of each metal ring 16. What should I do?

Next, the female thread portion 19 is formed on the inner peripheral surface 16 </ b> B of the metal ring 16. The female screw portion 19 is formed over the entire inner peripheral surface 16B.
FIG. 8 is a schematic cross-sectional view showing the next step of FIG.
Referring to FIG. 8, a male screw portion 20 is provided on the outer peripheral surface of the small diameter portion 21 of the first metal component 17. The female screw part 19 of the left metal ring 16 is screwed to the male screw part 20 of the first metal part 17. Thus, the first metal component 17 is screwed to the inner peripheral surface 16B of the metal ring 16 and is fastened to the end portion 10A of the pipe 10 via the metal ring 16.

On the other hand, a male screw portion 20 is also provided on the outer peripheral surface of the small diameter portion 21 of the second metal component 18. The female screw part 19 of the right metal ring 16 is screwed to the male screw part 20 of the second metal part 18. Thereby, the second metal component 18 is screwed to the inner peripheral surface 16B of the metal ring 16 and is fastened to the end portion 10B of the pipe 10 via the metal ring 16.
Thus, the pipe 10 is in a state of being fastened to the first metal part 17 and the second metal part 18 at both end portions 10A and 10B in the axial direction X, and the manufacture of the bar-shaped part 22 is completed.

  In the completed bar-shaped part 22, a part of the metal ring 16 protrudes outward from the pipe 10 in the axial direction X as described above. Therefore, when the pipe 10 is about to bend with respect to the first metal part 17 and the second metal part 18, the first metal part 17 and the second metal part 18 come into contact with the metal ring 16 instead of the pipe 10. Therefore, it is possible to prevent the end portions 10A and 10B of the pipe 10 from contacting the corresponding ones in the first metal part 17 and the second metal part 18, respectively. Thereby, damage to the pipe 10 due to contact with the first metal component 17 and the second metal component 18 can be prevented.

FIG. 9 is an enlarged view of a portion surrounded by an alternate long and short dash line in FIG.
Referring to FIG. 9, the diameter d1 of the carbon fiber 25 and the diameter (not shown) of the thermoplastic resin fiber 26 are the width W in the axial direction X of the concave portion 29 of the concave and convex portion 27 of the outer peripheral surface 16A of the metal ring 16 and The height H of the convex portion 38 of the concave and convex portion 27 (depth of the concave portion 29) is smaller. Therefore, the carbon fiber 25 and the thermoplastic resin fiber 26 are wound around the outer peripheral surface 23 </ b> A of the core member 23, thereby entering the concave portion 29 of the outer peripheral surface 16 </ b> A of the metal ring 16 without being cut halfway. Next, more carbon fibers 25 and thermoplastic resin fibers 26 enter the recesses 29 by being heated while being pressurized in the press molding step. The thermoplastic resin in the thermoplastic resin fiber 26 is solidified in a shape along the uneven portion 27 of the outer peripheral surface 16A of the metal ring 16 by being cooled after heating. Therefore, the end portions 10 </ b> A and 10 </ b> B of the pipe 10 can be in close contact with the outer peripheral surface 16 </ b> A of the metal ring 16. In addition, since the carbon fiber 25 that has entered the recess 29 on the outer peripheral surface 16A of the metal ring 16 functions as a retainer, the pipe 10 and the metal ring 16 are firmly connected.

Thus, the pipe 10 is externally fitted and fixed (prevented from falling out) to the outer peripheral surface 16A of the corresponding metal ring 16. In addition, the metal ring 16 in this state is positioned so as not to be displaced in the axial direction X with respect to the end portions 10A and 10B of the pipe 10 or in the circumferential direction.
Since the first metal part 17 and the second metal part 18 and the metal ring 16 are screw-fastened, the end parts 10A and 10B of the pipe 10 can be connected to the metal ring 16 without applying extra force. The first metal part 17 and the second metal part 18 can be securely and firmly fastened. Therefore, unlike the case where the first metal part 17 and the second metal part 18 are press-fitted into the metal ring 16, the outer peripheral surface 16 </ b> A of the metal ring 16 does not bite into the pipe 10. Since the fibers 25 are not cut, the strength of the pipe 10 is not reduced.

Incidentally, the time required to form the pipe 10 using the thermoplastic resin fibers 26 in this way is shorter than the curing time required to form the pipe 10 using the thermosetting resin.
Specifically, the time required for curing the thermosetting resin in the process of forming a pipe made of a general carbon fiber reinforced resin (so-called CFRP) is the time required for fluidizing the thermosetting resin and the thermosetting. It takes 5 hours or more including the time required to raise the temperature of the functional resin, and the cycle time for manufacturing automobile parts is very long, which causes an increase in manufacturing cost. On the other hand, as in this embodiment, the time required for forming the CFRTP pipe 10 by the press molding process, that is, the time until the thermoplastic resin fiber 26 is sufficiently fluidized and uniformly impregnated in the carbon fiber 25 is as follows. 1 to 15 minutes. Therefore, the CFRTP pipe 10 can be manufactured in a shorter time (low cycle time) than the CFRP pipe.

Thus, by using the thermoplastic resin fiber 26 for forming the pipe 10, the time required for processing can be shortened, and as a result, the manufacturing cost can be reduced.
As a result, in the case where the bar-shaped part 22 is configured by connecting the CFRTP pipe 10 and the first metal part 17 and the second metal part 18, while reducing the manufacturing cost of the bar-shaped part 22, Strength can be improved.

In addition, as for the filling amount (ratio of the volume of the carbon fiber 25 with respect to the volume of the pipe 10) of the carbon fiber 25 contained in the pipe 10, 35%-70% is desirable. If the filling amount is less than 35%, the strength and rigidity necessary for the rack bar 8 cannot be secured. On the other hand, when the filling amount exceeds 70%, the carbon fiber 25 is not sufficiently and uniformly impregnated with the thermoplastic resin in the press molding process.
Here, as a method of winding the resin around the core member 23 or the like, there is a sheet winding method using a sheet-like resin or the like in addition to the filament winding method using the fibrous resin used in the present embodiment.

  Thermoplastic resins are generally difficult to impregnate carbon fibers due to their high viscosity. However, when the carbon fibers 25 and the thermoplastic resin fibers 26 are wound around the outer peripheral surface 23A of the core member 23 by the filament winding method as in the present embodiment, the carbon fibers 25 and the thermoplastic resin fibers 26 are close to each other. ing. Therefore, the melted thermoplastic resin fibers 26 (the thermoplastic resin constituting the thermoplastic resin fibers 26) are easily impregnated in the carbon fibers 25 and between the carbon fibers 25.

In the filament winding method, the filling amount of the carbon fibers 25 can be adjusted by adjusting the speed at which the carbon fibers 25 and the thermoplastic resin fibers 26 are wound around the outer peripheral surface 23 </ b> A of the core member 23.
On the other hand, when the sheet-like carbon fiber and the sheet-like thermoplastic resin are alternately wound around the outer peripheral surface 23A of the core member 23 by the sheet winding method, in the surface portions of the respective sheet-like carbon fibers and the sheet-like thermoplastic resin. However, the carbon fiber and the thermoplastic resin are not close to each other. Therefore, the molten thermoplastic resin impregnates only the surface portion of the sheet-like carbon fiber.

As described above, when the filament winding method is used, the thermoplastic resin 28 can enter the carbon fibers 25 and between the carbon fibers 25 without gaps, compared with the case where the sheet winding method is used. Higher loadings can be achieved than when used.
Furthermore, since a sheet-like thermoplastic resin is hard and not bent at room temperature, it is difficult to use the sheet winding method in the first place. For this reason, it can be considered that the two sheet-like thermoplastic resins are pressed into an arc shape and the ends are welded to each other, but this is very laborious.

  Further, as a conventional method, after sheet-like carbon fibers are wound around the outer peripheral surface 23A of the core member 23 by a sheet winding method, a thermoplastic resin is poured into the sheet-like carbon fibers wound around the outer peripheral surface 23A by injection molding. There is also a method of bonding between layers of sheet-like carbon fibers. When the pipe 10 is formed only by press molding as in the present embodiment, injection molding is not necessary, so that the time required for molding can be shortened compared to the conventional method using injection molding.

Next, a first modification of the present invention will be described.
FIG. 10 is a diagram in which the first modification is applied to FIG. In FIG. 10, the same members as those described above are denoted by the same reference numerals, and the description thereof is omitted (the same applies to FIGS. 11 to 13 described below).
Referring to FIG. 10, a thermal adhesive film 30 is provided along the concavo-convex portion 27 on the outer peripheral surface 16 </ b> A of the metal ring 16 in the first modification. The heat bonding film 30 may be attached to the outer peripheral surface 16 </ b> A that has been roughened before the metal ring 16 is fitted onto the mandrel 24, or the metal ring 16 is attached to the mandrel 24. You may attach to 16 A of outer peripheral surfaces by which the roughening process was given after being externally fitted. Thereby, the pipe 10 and the metal ring 16 are more firmly connected.

Next, a second modification of the present invention will be described.
FIG. 11 is a view showing a braid 37 of the second modification.
Referring to FIG. 11, the step of winding carbon fiber 25 and thermoplastic resin fiber 26 of the second modification around outer peripheral surface 23 </ b> A of core material 23 includes the step of winding braid 37 around outer peripheral surface 23 </ b> A of core material 23. Yes. The braid 37 is configured by combining dry carbon fibers 25 and thermoplastic resin fibers 26 so as to twist them together.

  Rather than separately winding the carbon fiber 25 and the thermoplastic resin fiber 26 around the outer peripheral surface 23A, the carbon fiber 25 and the thermoplastic resin fiber 26 are uniformly distributed in the axial direction X by using only the braid 37. It can be wound around the outer peripheral surface 23A. Thereby, the pipe 10 with which the ratio of each of the carbon fiber 25 and the thermoplastic resin fiber 26 is uniform can be obtained.

  Further, in FIG. 11, two thermoplastic resin fibers 26 and one carbon fiber 25 form a braid 37, but the braid 37 may be composed of three or more fibers, The composition ratio of the carbon fiber 25 and the thermoplastic resin fiber 26 can be arbitrarily changed. By adjusting the ratio of the carbon fibers 25 and the thermoplastic resin fibers 26 in the braid 37, the filling amount of the carbon fibers 25 can be adjusted.

Next, a third modification of the present invention will be described.
FIG. 12 is a view showing a fabric sheet 40 of a third modification.
Referring to FIG. 12, the step of winding the carbon fiber 25 and the thermoplastic resin fiber 26 of the third modified example around the outer peripheral surface 23 </ b> A of the core member 23 includes the step of winding the woven sheet 40 around the outer peripheral surface 23 </ b> A of the core member 23. It is out. The woven sheet 40 is a woven sheet in which the carbon fibers 25 and the thermoplastic resin fibers 26 are combined with each other.

  Specifically, the fabric sheet 40 of the third modified example has a carbon fiber tow 41 that is a bundle of dry carbon fibers 25 and a thermoplastic resin fiber tow 42 that is a bundle of thermoplastic resin fibers 26 in a fabric shape. It is shaped. In the woven fabric sheet 40, carbon fiber tows 41 extending linearly in a predetermined direction and thermoplastic resin fiber tows 42 extending in a direction intersecting the carbon fiber tows 41 are woven together by plain weaving.

Here, in order to increase the strength against the tensile / compressive stress (stress in the axial direction X) generated in the pipe 10, the carbon fiber 25 extends in the axial direction X (orientated in the axial direction X). Is desirable).
As described above, in this embodiment, the filament winding method is used, and the carbon fiber 25 is wound around the outer peripheral surface 23A by hoop winding. Therefore, in the present embodiment, the carbon fibers 25 cannot be oriented along the axial direction X. As a result, in order to improve the strength of the pipe 10, it is necessary to increase the thickness of the pipe 10, and as a result, the weight reduction effect of the rack bar 8 may be reduced.

  On the other hand, in the third modification, the fabric sheet 40 is wound around the outer peripheral surface 23A of the core member 23 by a sheet winding method. Since the direction in which the fabric sheet 40 is wound can be controlled, the fabric sheet 40 can be wound around the outer peripheral surface 23 </ b> A with the carbon fibers 25 oriented in the axial direction X of the pipe 10. Thereby, the strength of the pipe 10 against the stress in the axial direction X can be improved.

In addition, since the strength of the pipe 10 is improved in this way, the number of times the woven fabric sheet 40 is wound around the outer peripheral surface 23A of the core member 23 can be reduced and the pipe 10 can be made thinner. In this way, the rack bar 8 can be reduced in weight by controlling the number of laminated fabric sheets 40.
Also in the third modified example, injection molding is unnecessary as in the present embodiment, so that the molding time can be shortened compared to the case of using injection molding.

Moreover, the woven sheet 40 can adjust the filling amount of the carbon fiber 25 by adjusting the width of the carbon fiber tow 41 and the thermoplastic resin fiber tow 42.
Further, the weaving method of the fabric sheet 40 is not limited to plain weaving, and general weaving methods such as twill weaving, satin weaving, and multiaxial weaving can be applied.
Next, a fourth modification of the present invention will be described.

FIG. 13 is a view showing the rack bar 8 of the fourth modified example and its periphery.
Referring to FIG. 13, in the rack bar 8 of the fourth modified example, the pipe 10 has a rack 15. In the case of the fourth modification, the rack 15 is formed in a step of pressing the carbon fibers 25 and the thermoplastic resin fibers 26 (press forming step). Specifically, a rack forming portion (not shown) capable of forming the rack 15 is provided in the first mold 34 or the second mold 35 (see also FIG. 3). In the press molding process, the thermoplastic resin fiber 26 is melted and solidified in the press mold 33 by using the press mold 33 provided with the rack molding portion in either the first mold 34 or the second mold 35. Then, the rack 15 is formed on the outer peripheral surface 10D of the pipe 10 (see also FIG. 3). On the other hand, the rack 15 is not formed in the second metal part 18 of the fourth modification example, and the second metal part 18 is disposed only in a portion adjacent to the joint 11 on the right side X2. Thus, the thermoplastic resin fiber 26 can be molded into the rack 15 simultaneously with the molding of the pipe 10 by hot pressing at a high temperature in the press molding process.

  Thereby, since the ratio of the pipe 10 to the rack bar 8 can be increased, the weight of the rack bar 8 can be reduced. Further, the rack 15 is not formed by cutting the pipe 10, but is formed when the carbon fiber 25 and the thermoplastic resin fiber 26 are pressed, so that the carbon fiber 25 is not cut. Therefore, the strength of the bar-shaped part 22 can be improved.

However, the dimensional accuracy of the rack 15 formed on the pipe 10 is inferior to that of the rack 15 formed on the second metal part 18 by cutting.
The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.
For example, in the present embodiment, in the press molding process, the thermoplastic resin fiber 26 is heated while being pressurized. However, even if the carbon fiber 25 and the thermoplastic resin fiber 26 are heated and then pressurized, the same as in the present embodiment. The strength can be improved while reducing the manufacturing cost of the bar-shaped component 22.

Further, in the present embodiment, the step of providing the female screw portion 19 screwed to the male screw portion 20 provided in the first metal component 17 and the second metal component 18 on the inner peripheral surface 16B of the metal ring 16 is performed by the mandrel 24. However, this step may be performed before the metal ring 16 is fitted onto the mandrel 24.
Further, the bar-shaped component 22 of the above-described embodiment is configured to fasten metal components (the first metal component 17 and the second metal component 18) to both end portions (both the end portion 10A and the end portion 10B) of the pipe 10. However, a configuration in which the metal part is fastened to only one of the both end portions may be employed.

Further, the bar-shaped component 22 of the above-described embodiment is the rack bar 8, but may be configured as a bar-shaped component other than the rack bar 8 (for example, various shafts, rods, pipe-shaped components).
In this embodiment, instead of the carbon fibers 25 and the thermoplastic resin fibers 26, the carbon fiber tows 41 and the thermoplastic resin fiber tows 42 may be wound around the outer peripheral surface 23 </ b> A of the core member 23.

  Further, the fabric sheet 40 may have a fabric shape configured by combining braids 37.

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 8 ... Rack bar, 10 ... Pipe, 10A ... End part, 10B ... End part, 15 ... Rack, 16 ... Metal ring, 16A ... Outer peripheral surface, 16B ... Inner peripheral surface, 17 ... First metal Part 18: Second metal part 19 ... Female thread part 20 ... Male thread part 22 22 Bar-shaped part 23 23 Core material 23A Peripheral surface 24 Mandrel 25 Carbon fiber 26 Thermoplastic resin fiber 37 ... Braid, 40 ... Woven sheet, X ... Axial direction

Claims (8)

A method of manufacturing a bar-shaped part including a pipe made of carbon fiber reinforced thermoplastic resin and a metal part fastened to an end portion in the axial direction of the pipe,
A step of preparing a core material including the mandrel and the metal ring by externally fitting a metal ring having an outer peripheral surface subjected to a rough surface to the metal mandrel extending in the axial direction. When,
Winding each of the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core;
Melting the thermoplastic resin fiber by heating while pressing the carbon fiber and the thermoplastic resin fiber wound around the outer peripheral surface of the core material;
Cooling the thermoplastic resin impregnated in the carbon fiber and forming the pipe with the end portion fitted and fixed to the outer peripheral surface of the metal ring; and
Extracting only the mandrel from the pipe from the core;
Screwing the metal part and the inner peripheral surface of the metal ring;
The manufacturing method of bar-shaped components characterized by including these. A method of manufacturing a bar-shaped part including a pipe made of carbon fiber reinforced thermoplastic resin and a metal part fastened to an end portion in the axial direction of the pipe,
A step of preparing a core material including the mandrel and the metal ring by externally fitting a metal ring having an outer peripheral surface subjected to a rough surface to the metal mandrel extending in the axial direction. When,
Winding each of the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core;
A step of melting the thermoplastic resin fibers by heating and then pressurizing the carbon fibers and the thermoplastic resin fibers wound around the outer peripheral surface of the core material;
Cooling the thermoplastic resin impregnated in the carbon fiber and forming the pipe with the end portion fitted and fixed to the outer peripheral surface of the metal ring; and
Extracting only the mandrel from the pipe from the core;
Screwing the metal part and the inner peripheral surface of the metal ring;
The manufacturing method of bar-shaped components characterized by including these.   The step of winding the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material includes the step of winding a woven sheet formed by combining the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material. The method for manufacturing a bar-shaped part according to claim 1, comprising: a bar-shaped part.   The step of winding the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material includes the step of winding a braid formed by combining the carbon fiber and the thermoplastic resin fiber around the outer peripheral surface of the core material. The manufacturing method of the bar-shaped component in any one of Claims 1-3 characterized by these.   The bar according to any one of claims 1 to 4, further comprising a step of forming a female screw portion screwed to a male screw portion provided in the metal part on an inner peripheral surface of the metal ring. Method for manufacturing a shaped part.   The method of manufacturing a bar-shaped part according to claim 1, wherein the bar-shaped part constitutes a rack bar included in a rack-and-pinion type steering device. The pipe has a rack;
The method of manufacturing a bar-shaped part according to claim 6, wherein the rack is formed in a step of pressurizing the carbon fiber and the thermoplastic resin fiber.   The method of manufacturing a bar-shaped part according to claim 6, wherein the metal part has a rack.

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