Patent Application
20080307652
The present invention relates to bicycle cranks, and particularly to a method for manufacturing a bicycle crank, wherein small area carbon-fiber adhesive sheets are added to the crank so as to have a preferred strength with less cost and less work.
It is a current trend to use carbon-fiber composite material to make parts of a bicycle.
For a crank of a bicycle made of carbon-fiber material, each of two ends of the crank must be connected to a five communication tube. However, the carbon-fiber composite material is very hard and brittle. Thus the connections therebetween are not effective. To strengthen the structure, the pivoted areas are buried with metal tubes. Further small area carbon-fiber adhesive sheets are adhered upon the crank one by one. Then metal tubes are engaged to the crank. Finally, gluing adhesives are planted upon the crank so as to complete the process of making a crank.
However, the prior art has some troubles in manufacturing and generates some defects in the products. In adhering small area carbon-fiber adhesive sheets upon the crank one by one, the plane carbon-fiber adhesive sheets are difficult in manufacturing. Not only time is consumed, but also it must be performed by professional persons. The cost is high. Furthermore the interior of the crank must be formed with supporting blocks for adhering operation, and thus it is not a complete hollow structure. The material needed is grater and thus heavy.
When the crank is complete, the metal tubes are buried. However, the combination of the crank with the two tubes is not concrete. Adhesive is used to enhance the structure. However, adhesive generates the problems of buckling and the difficulty in prepare. Thus, the prior art is not practical and is necessary to be improved.
Accordingly, the primary object of the present invention is to provide a method for manufacturing a bicycle crank, wherein small area carbon-fiber adhesive sheets are added to the crank so as to have preferred strength with less cost and less work.
To achieve above objects, the present invention provides a method for manufacturing a bicycle crank, comprising the steps of: blowing air into a blowing opening at a lower end of a backbone so as to fixing the backbone; wherein the backbone has a first embedding portion; using a cutter to cut the backbone; and then form a second embedding portion in the end of the backbone having the blowing opening; winding an unidirectional carbon-fiber cloth around the backbone; adhering carbon-fiber adhesive sheet upon an outer side of the backbone; and heating the backbone so as to firmly secure the carbon-fiber adhesive sheet to the backbone. Furthermore before the blowing step, the method further comprises a step of forming a first embedding portion at one end of the backbone; and embedding a metal first tube into the first embedding portion.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.
In order that those skilled in the art can further understand the present invention, a description will be provided in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims.
With reference to
Referring to
Blowing air into a blowing opening 13 at a lower end of the hollow backbone 10 so as to fixing the first tube 12 to the backbone 10 (step 2);
Referring to
Referring to
Thermally setting and pressing the backbone 10 so that the carbon-fiber cloth 16, first tube 12 and second tube 15 and the backbone 10 are combined firmly (step 5);
Adhering carbon-fiber adhesive sheet upon an outer side of the backbone 10 (step 6);
Heating the backbone 10 so as to firmly secure the carbon-fiber adhesive sheet to the backbone 10 (step 7); thus the product according to the present invention is complete as illustrated in
Referring to
The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
