JP2003072666A - Bicycle crank and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crank and its manufacturing method connecting an insert and a core more easily without needing to foam the insert in a mold. SOLUTION: The bicycle crank is composed of the long core 10 having first and second end parts 12 and 14, the first and second inserts 24 and 26 fitting on both end parts 12 and 14 of the core 10, and a high drag fiber coating mixed in a plastic material matrix forming a case 40 wrapped around the core 10 and the inserts 24 and 26. The core 10 provides only limited or almost no structural drag.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bicycle crank and a method for manufacturing the crank. More specifically, the present invention provides a long core having first and second end portions, first and second inserts arranged at both end portions of the core, and a plastic material base material. A crank for a bicycle composed of a mixed high drag fiber coating.

[0002]

U.S. Pat. No. 6,202,506 discloses a bicycle crank of the type described above in which the insert is a rigid plastic material which is foamed to form the core of the crank. This document discloses a method for manufacturing a crank which comprises the following steps. That is, one layer of woven fabric soaked in synthetic resin is introduced into the mold to prepare a fiber reinforced plastic case with an open part, and a pair of inserts is inserted into the partly open case to form a high resistance foam. Foaming the insert of material, sealing the case of fiber reinforced plastic material with a fabric of fibers soaked in at least one layer of plastic material, and curing the fiber reinforced plastic material and the foam material.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a crank and a method of manufacturing the crank, which does not require foaming of the insert in the mould, making it easier to connect the insert and the core, and It is to provide the manufacturing method.

[0004]

According to the invention, said object can be achieved by a crank and its manufacturing method having the characteristics forming the subject of the claims.
The invention will be more clearly illustrated by the following detailed description with reference to the accompanying drawings, which show non-limiting examples.

[0005]

1 to 3, reference numeral 10
Shows a core of preformed foamed plastic material, such as polyurethane or similar material, obtained by foaming in a mold. The core 10 has an elongated shape and has two end portions 12 and 14, to which the corresponding coupling elements 16 and 18 are coupled. Said coupling element is provided with recesses 20,22 which receive the end portions 12,14 of the core 10 and formally fit therewith.

Reference numerals 24 and 26 designate two inserts made of metal such as aluminum alloy or fiber reinforced plastic material, and the corresponding connecting elements 16 and 1 are provided.
It has terminals 28, 30 that are inserted into the recesses 32, 34 of the eight and form a tight fit. This insert 2
4, 26 preferably consist of hard metal blocks.
The insert has holes into which a pedal spindle and a bottom bracket spindle (not shown) respectively fit.

FIG. 3 shows the core 10, the coupling element 16,
18 shows a state in which the configurations including the metal inserts 24 and 26 are combined. The core 10 has no structural characteristics. That is, the core 10 has inserts 24, 2
No transmission of force or torque between 6 The core 10 holds the inserts 24, 26 coupled in place and forms the support surface during lamination, as shown schematically in FIG. 5, and provides the appropriate reaction force during molding. Here, the term “bonding” refers to a step of stacking the tape 36 and the sheet 38 in layers on the structure formed by the inserts 24 and 26 and the core 10. This process is used to attach the reinforcing fibers in the most appropriate way to give the crank the necessary structural properties.

The arrangement shown in FIG. 3 is wrapped with a tape 36 and a sheet 38 formed of structural high-strength fibers mixed with a plastic material matrix. Preferably, the tapes and sheets 36, 38 are made of carbon fiber fabric mixed with a thermosetting resin. The structural fibers are carbon fibers, glass fibers, aramid fibers, boron fibers,
It may be selected from ceramic fibers or combinations thereof. After laminating, the crank is molded,
At the same time, the thermosetting resin is heated at the polymerization temperature or higher. This mold forming step is performed in a mold and a press (not shown). During molding, the applied pressure is supported by the reaction force of the core and insert. This pressure tightens the fabric of the plastic material matrix.

After molding, the plastic material base material is hardened. The crank removed from the mold is in the state shown in FIG.
And a case 40 made of carbon fiber having a uniform structure.
The case 40 exhibits high drag structural properties and is capable of transmitting the stress applied to the crank during use from one insert to the other.

Although the above method is described for the left crank, it is similarly used for manufacturing the right crank as shown in FIG. In this case, the insert 26 has an integrated metal spoke 42 for joining the bottom bracket.
Have a set of. In the embodiment shown in FIG. 4, the insert 26 has four spokes 42, the ends 44 of which form the fixings for tightening a pair of chain wheels (not shown). The fifth tightening portion is obtained by the third metal insert 46 fitted in the recess 48 formed in the core 10. The crank shown in FIG. 4 is subjected to lamination and polymerization in the same manner as described above.

In both the left and right cranks, these inserts have threaded holes 50 for connecting the pedal spindles and polygons for connecting the bottom bracket spindles, after polymerization in the mould. Holes 52 are machined.

As mentioned above, the core 10 has almost no structural drag, and the only part of the crank having structural properties is the case 40, which provides high drag. Inserts 24 and 26 when using the crank
Forces and torques can be transmitted between them.

Accordingly, the core 10 can be made of any material that provides shape and support for the structural fibers, such as any foam, wax or resin.

According to a preferred embodiment of the present invention, the core 10 is removed after molding and curing of the structural fiber case 40. The core may also be formed from a particulate material such as sand mixed with a binding resin. This particulate material can be removed from the crank through the holes in the structural fiber case (40) after it has hardened, which allows the structural fiber case (40) and the metal inserts 24, 26 to exit. It can be a single structure constructed.

A second embodiment according to the present invention is shown in FIGS. 8 to 12, in which the elements corresponding to the elements described thus far are indicated by the same reference numbers. In this second embodiment, the inserts 24, 26
Are provided with coupling portions 60 and 62, which are inserted into the corresponding terminal portions 12 and 14 of the core 10 to insert them into the core 1.
0 and formally close fit.

Preferably, the core 10 is formed by a tubular element of plastic, metal or fiber reinforced material having only limited structural drag. Insert 2
4, 26 are made of, for example, a metal material such as an aluminum alloy, or a fiber reinforced plastic material. These inserts have holes to accommodate the pedal spindle and the bottom bracket spindle (not shown), respectively.

As shown diagrammatically in FIG. 11, the above construction comprising core 10 and inserts 24, 26 is wrapped by a tape 36 and sheet 38 formed of structural high drag fibers mixed with a plastic material matrix. Be done. The tapes and sheets 36, 38 are preferably made of carbon fiber fabric mixed with a thermosetting resin. The structural fibers may be selected from carbon fibers, glass fibers, aramid fibers, boron fibers, ceramic fibers, or combinations thereof.

The core 10 holds the inserts 24, 26 bonded in place and forms the support surface during lamination. Here, the term “bonding” has the same meaning as that described in the first embodiment of the present invention.

The process described above with reference to the left crank is shown in FIG.
It is used similarly for the production of the right crank as shown in FIG. In this case, the insert 26 joining the bottom bracket is provided with an integrated set of metal spokes 42 similar to that shown in FIG. The insert 26 has a connection 62 for a form-fitting connection with the core 10.

In both the left and right cranks, these inserts have threaded holes 50 for connecting pedal spindles and polygons for connecting bottom bracket spindles, after stacking in the mould. Holes 52 are machined.

As already mentioned, the purpose of this elongated core 10 is to provide shape and support for the structural fibers. Therefore, the core 10 has almost no structural drag, or only limited structural drag.

The term limited structural drag refers to the fact that most of the structural drag is directed to the case 40, which exhibits high drag, and when the crank is in use, the force between inserts 24 and 26 is It means that most of the torque can be transmitted.

Further, in the first embodiment of the present invention,
The crank is formed of a unitary unit consisting of structural fibers and at least a pair of inserts located at the ends of the case. These are in fact the only structural elements of the crank, that is to say they can carry the load during use of the crank.

[0024]

By implementing the present invention, it is not necessary to foam the insert in the mold, and it is possible to obtain a crank that more easily connects the insert and the core, and a manufacturing method thereof.

Naturally, various modifications can be made from the structures and configurations of the embodiments of the invention disclosed herein, all of which specify the invention defined by the embodiments. It is included in the concept category.

[Brief description of drawings]

FIG. 1 is a perspective view showing components of a left crank according to a first embodiment of the present invention.

2 is a perspective view showing a longitudinal cross-section of the component shown in FIG. 1. FIG.

FIG. 3 is a perspective view showing a state in which the constituent elements shown in FIG. 1 are combined.

FIG. 4 is a perspective exploded view showing components of the right crank according to the first embodiment of the present invention.

FIG. 5 is a schematic view showing a bonding step using a carbon fiber layer for manufacturing the crank according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view in the longitudinal direction showing the end of the bonding step and the carbon fiber polymerization step of the crank according to the first embodiment of the present invention.

FIG. 7 is a plan view of a completed crank product.

FIG. 8 is an exploded perspective view showing components of a left crank according to a second embodiment of the invention.

9 is a perspective view similar to FIG. 8, showing a longitudinal cross section of the core.

FIG. 10 is an exploded perspective view showing components of a right crank according to a second embodiment of the invention.

FIG. 11 is a schematic view showing a bonding step using a carbon fiber layer for manufacturing a crank according to a second embodiment of the present invention.

FIG. 12 is a longitudinal cross-sectional view showing the end of the bonding step and the carbon fiber polymerization step of the crank of the second embodiment.

[Explanation of Codes] 10. Core, 12, 14. Terminal part, 16, 18. Coupling element, 20, 22. Recessed portion, 24. First insert, 26. Second insert, 28, 30. Terminal part, 32, 34. Recessed portion, 36. Tape, 38.
Sheet, 40. Case, 42. Metal spokes, 4
4. Terminal part, 46. Third insert, 48. Recessed portion, 50. Screw holes, 52. Polygonal hole 60, 62.
Joining part.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Maurizio Valle             Italy 36100 Visunza, Viale et             Sse Agostino No. 366 F term (reference) 4F211 AD08 AG07 AG23 AH17 TA03                       TC08 TC11 TC14 TC21 TN01                       TN44 TN56 TN63

Claims (22)

[Claims] 1. A case (40) of structural fibers mixed with a plastic material matrix and arranged at both ends of the case (40) for connecting a bicycle crank to a pedal and a bottom bracket spindle. Bicycle crank characterized in that it is configured as a single structural unit by means of the first and second inserts (24, 26). 2. Bicycle crank according to claim 1, characterized in that it comprises a third insert (46) arranged in the middle region of the crank. 3. The structural fibers are carbon fibers, glass fibers, aramid fibers, boron fibers, ceramic fibers,
Alternatively, the bicycle crank according to claim 1, wherein the crank is selected from a combination thereof. 4. Bicycle crank according to claim 1, characterized in that the inserts (24, 26) are made of metal. 5. Bicycle crank according to claim 4, characterized in that the inserts (24, 26) are made of aluminum alloy. 6. Bicycle crank according to claim 4, characterized in that the inserts (24, 26) are made from a fiber-reinforced plastic material. 7. The bicycle crank has an elongated core (1).
0) and includes the first and second inserts (24, 2).
Bicycle crank according to claim 1, characterized in that 6) is structurally connected only to the case (40) or substantially only to the case (40). 8. A bicycle crank according to claim 7, characterized in that the elongated core (10) provides substantially no structural drag. 9. Bicycle crank according to claim 8, characterized in that the elongated core (10) is made of a material selected from foam, wax and resin. 10. Bicycle crank according to claim 9, characterized in that the elongated core (10) is a preformed body of foamed plastic material. 11. Bicycle crank according to claim 1, characterized in that it comprises a coupling element (16, 18) for obtaining a form-fitting coupling with the insert (24, 26). 12. The elongated core (10) has two ends (12, 14) and the coupling element (16, 18).
Has recesses (20, 32, 22, 34) that provide a form-fitting connection between the inserts (24, 26) and the ends (12, 14) of the elongated core (10).
The bicycle crank according to claim 8 or 11, further comprising: 13. Bicycle crank according to claim 7, characterized in that the elongated core (10) is rigid. 14. Bicycle crank according to claim 7, characterized in that the elongated core (10) provides a limited structural drag. 15. Bicycle crank according to claim 13, characterized in that the elongated core (10) is made of plastic. 16. Bicycle crank according to claim 13, characterized in that the elongated core (10) is made of metal. 17. The elongated core (10) is made of a fiber reinforced plastic material,
The bicycle crank according to claim 13. 18. A method of manufacturing a bicycle crank, comprising: a) forming an elongated core (10); and (b) both ends (12, 1) of the elongated core (10).
4) Fitting a pair of inserts (24, 26) into c), c) the long core (10) and the inserts (24,
26) onto which is coated a coating of structural fibers mixed with a plastic material matrix, d) said elongated core (10) and said insert (2)
The method comprises the steps of curing the plastics material matrix to form a high resistance hard case (40) enclosing the plastic material matrix. 19. A method according to claim 18, characterized in that it comprises the step of removing the elongated core (10) after curing the plastics material matrix. 20. The method according to claim 19, characterized in that the elongated core (10) is made of a granular material and is taken out of a hole of the hardened hard case (40). 21. The method according to claim 18, characterized in that it comprises the step of fitting a third insert (46) in the middle part of the elongated core (10). 22. Fitting a coupling element (16, 18) on both ends (12, 14) of the elongated core (10) and inserting the insert (24, 26) into the coupling element (16, 1).
Method according to claim 18, characterized in that it comprises the step of fitting in 8).