JP2005132221A - Manufacturing method for bicycle frame member and bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a bicycle frame member and a bicycle capable of enhancing rigidity in a manufacturing process without requiring dies or machining, having sufficient anti-scratch performance and anti-abrasiveness, and has enhanced design quality and high accuracy. <P>SOLUTION: The manufacturing method for the bicycle frame member is configured such that the peripheral surface of a hollow member 8 is subjected to masking selectively and the peripheral surface of the hollow member 8 except a masked portion 22 is subjected to ceramic coating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a member for a bicycle frame.

  As a bicycle frame member that requires light weight and high rigidity, increase the thickness at both ends (or one end), which is a joint part of a pipe where relatively large stress acts, and decrease the thickness at the middle. Thus, there is already known a butted processing method that secures sufficient rigidity while minimizing a decrease in rigidity while reducing the weight of the pipe.

  Conventional butted processing methods are roughly classified into two types, that is, a method by cold processing and a method of processing the inner periphery of a pipe by chemical milling (chemical cutting) such as pickling.

  As the cold working, there are a processing method by a roll method shown in FIG. 7 and a processing method by a drawing method shown in FIG.

  In the former processing method, as shown in FIG. 7A, first, a cylindrical mandrel 51 is inserted into a material tube 50 of uniform thickness, and these are rotated around an axis. The intermediate portion of the material tube 50 is formed into a thin shape by pressing the outer peripheral portion from the side by the roll 52, and then the core 51 is removed as shown in FIG. The diameter D1 of the hole 53a is smaller than the diameter D2 of the material pipe 50 (substantially equal to the diameter D3 of the small diameter portion of the material pipe 50 forcedly deformed by the roll 52), and the material pipe 50 is pulled out. Thus, as shown by a two-dot chain line in FIG. 7B, a pipe 55 having a thick end is obtained.

  On the other hand, in the latter processing method, as shown in FIG. 8, a mandrel 61 having a narrow end is inserted into a material tube 60 having a substantially constant wall thickness. The pipe 62 having a thick end is obtained by pulling out the die 62 having a diameter D4 of the hole 62a smaller than the diameter D5 of the material tube 60.

  When such a butted processing method by cold working is used, the shape of the pipes 55 and 65 after processing is formed so that the wall thickness gradually changes, so that the stress concentration hardly occurs, and the cold working There exists an advantage that the intensity | strength by work hardening improves in a process.

  Further, as shown in FIG. 9A, the conventional processing method by chemical milling is a chemical milling treatment liquid (corrosive liquid) 72 at the center inside the both ends of the material pipe 70 having a uniform thickness. The rubber plug 71 for masking in which the flow path 71a for injecting the liquid is inserted is inserted, and then the processing liquid 72 is introduced into the material pipe 70 from the flow path 71a. The inner peripheral surface of 70 is melted (etched) to form a pipe 75 having a thin intermediate portion as shown in FIG. 9B.

  This method of machining the inner circumference of a pipe by chemical milling generally melts the inner circumference of the pipe, so it is generally necessary to use a die such as a die, and the advantage that it is possible to machine even materials that are difficult to machine Therefore, it is suitable for high-mix low-volume production.

  However, in the cold working methods such as the roll method and the drawing method described above, when a material having a large ductility is used as the material of the material pipes 50 and 60, the material can be processed with a relatively small force, so that it is relatively easy to perform the batting. Although processing can be performed, materials such as titanium having low ductility and high tensile strength must be processed with a very large force, and there is a problem that processing is difficult. In addition, since large dies such as the dies 53 and 62 are necessary, there is a problem that the manufacturing cost per product becomes high in the case of multi-product small-volume production. Furthermore, since processing is performed while deforming with a large force, in the case of a bicycle frame member that requires a relatively long pipe, a shape error is likely to occur during processing, and it is difficult to produce with high accuracy. In addition, since the thickness cannot be measured during processing, there is a drawback that it is difficult to manage the thickness.

  Moreover, in the conventional method of processing the inner periphery of the pipe by chemical milling, it is difficult to manage the thickness because the change in thickness during the etching cannot be recognized from the outside. Accordingly, there is a case where a large step is generated between the masking portion and the unmasked portion of the material pipe 70 by chemical milling, and there is a drawback that stress concentration is likely to occur in the step portion 75a on the inner periphery of the pipe 75.

  Furthermore, it has been difficult to perform complicated processing by the conventional method of processing the inner periphery of the pipe by chemical milling.

  Therefore, recently, by masking a part of the outer periphery of the material pipe, chemically milling the outer periphery of the material pipe after masking, and thinning the portion other than the masking portion on the outer periphery of the material pipe, the pipe for the bicycle frame is made. A manufacturing method has also been proposed (see, for example, Patent Document 1).

  According to this method, it is possible to obtain a good shape even when the bicycle frame pipe is long without requiring a mold or machining, and it is possible to easily check the change in the outer periphery of the material pipe. There is an advantage that you can.

JP 2003-200904 A

  However, since the method described in Patent Document 1 adjusts the rigidity of the material tube by a chemical method (etching), it is easy to reduce the rigidity, but it is difficult to increase the rigidity.

  Moreover, when surface hardness is ensured using a material with high hardness, a material with high hardness is difficult to process and increases the cost.

  Furthermore, with special bicycles such as recent competition bicycles, there is a demand for further weight reduction and appearance improvement, and it is necessary to reduce the weight while securing the necessary rigidity or strength, so it is thin and high strength There is a tendency to use materials. However, when the wall thickness is small, a slight scratch has a great influence on the fatigue strength, and there is still room for improvement in terms of scratch resistance, wear resistance, and appearance.

  The present invention has been made in view of such problems of the prior art, and does not require a mold or machining, can improve rigidity in the manufacturing process, and has sufficient scratch resistance or An object of the present invention is to provide a bicycle frame member manufacturing method and a bicycle capable of producing a highly accurate bicycle frame member having wear resistance and improved design.

  To achieve the above object, the invention according to claim 1 of the present invention is a method of manufacturing a member for a bicycle frame, wherein the outer peripheral surface of the hollow member is selectively masked, and the masked portion is excluded. The outer peripheral surface of the hollow member is characterized by ceramic coating.

  The invention according to claim 2 is characterized in that the masked portion is at least one end of the hollow member.

  Furthermore, the invention described in claim 3 is characterized in that at least one end of the hollow member is subjected to butted processing before selectively masking the outer peripheral surface of the hollow member.

  The invention according to claim 4 is characterized in that the thickness of the thinnest portion of the hollow member is 0.5 mm or less.

  The invention according to claim 5 is characterized in that a portion of the hollow member to be welded with another member is masked.

  The invention described in claim 6 is characterized in that, of the hollow member, a portion having a thickness equal to or larger than a predetermined value is masked.

  Further, the invention according to claim 7 is used for a bicycle frame by order production.

  The invention according to claim 8 is used for a frame of a competition bicycle.

  The invention according to claim 9 is used to adjust the rigidity of the frame in accordance with the user of the bicycle.

  The invention according to claim 10 is characterized in that the hollow member is made of titanium alloy or titanium.

  An eleventh aspect of the present invention is a bicycle comprising the bicycle frame member manufactured by the method for manufacturing a bicycle frame member according to any one of the first to tenth aspects.

  According to the present invention, the outer periphery of the hollow member is selectively masked, and the hollow member excluding the masked portion is ceramic-coated, so that the rigidity is increased by the formed ceramic thin film, and the hollow member is thin. In addition, sufficient strength or rigidity can be ensured, and the degree of freedom in design is improved. Further, the rigidity can be freely changed according to the preference of the customer, and the rigidity can be increased without increasing the weight. Furthermore, since the surface hardness of the material can be increased without impairing workability, it is difficult to be scratched. Further, since no mold or machining is required, even if the bicycle frame member has a long size, it can be formed in a good shape, and the bicycle frame member can be manufactured with high accuracy. Furthermore, the ceramic thin film thus formed has a unique luster, and various color tones can be obtained while maintaining the metallic luster, thereby improving the design of the bicycle frame.

  Further, since the end portion of the hollow member is masked and the ceramic coating is applied to the portion other than the end portion, welding with the other hollow member can be easily performed.

  Furthermore, since the end of the hollow member is subjected to butting before masking, the strength of the end to which a large stress is applied can be improved.

  Further, since the ceramic coating is applied to the thinnest portion of the hollow member having a thickness of 0.5 mm or less, the scratch resistance of the thin-walled bicycle frame member that is vulnerable to scratches is improved.

  Even when titanium or a titanium alloy having a small ductility and a high tensile strength is used, a well-shaped bicycle frame member can be manufactured in a relatively short time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a frame 2 of a bicycle (including a power-assisted bicycle), which is composed of a plurality of pipes connected to each other. For a bicycle frame according to the present invention, a lower pipe (hereinafter simply referred to as a pipe) 8 having both ends connected to a head pipe 4 and a hanger lug 6 among a plurality of pipes constituting the bicycle frame 2 shown in FIG. A method for manufacturing the member will be described.

  FIG. 2A shows a material pipe 8 of a pipe for a bicycle frame as a hollow rod-shaped member used in the manufacturing method according to the present invention (here, the same reference numerals as those of the pipe 8 as a finished product are given). And the wall thickness is substantially constant with a cylindrical shape. As the material, for example, a titanium alloy (or pure titanium) is used. As the titanium alloy, Ti-3Al-2.5V, Ti-6Al-4V, Ti-15Mo-5Zr-3Al, Ti-6Al-2Sn are used. -4Zr-2Mo, Ti-8Al-1Mo-1V, and the like.

  2 (b) and 2 (c) show a pipe 8 manufactured by the manufacturing method according to the present invention, in which both end portions are formed thick, and the intermediate portion 10 between both end portions is thinner than both end portions. It is formed to become. The pipe 8 has no step on the inner peripheral surface, and has steps (stepped portions) 12 at both ends of the outer peripheral surface. This butted processing can be performed only by the process of FIG. 7A in the cold processing by the roll method already described with reference to FIG. 7, and can also be performed by chemical milling of the outer periphery.

  As shown in FIGS. 1 and 2 (b) and 2 (c), one end of the pipe 8 is formed with a head pipe side end 14 connected to the bicycle head pipe 4, and the other end is formed with a bicycle. A hanger lug side end portion 16 connected to the hanger lug 6 is formed, and an intermediate portion 10 between these end portions 14 and 16 is formed in a thin shape. Thus, various parts including the pipe 8 are assembled as a bicycle frame by forming the end portions 14 and 16 in a thick shape while reducing the weight by forming the intermediate portion 10 in a thin shape. When using a bicycle as a finished product, it is possible to reinforce a portion where a large stress is easily applied and to disperse the stress even when the stress is applied, thereby preventing stress concentration.

  As shown in FIG. 3, the water bottle support fitting screw 18, the shift lever attachment fitting 20, and the like may be formed in the intermediate portion 10 as necessary.

  Next, the manufacturing method of the pipe 8 concerning this invention is demonstrated, referring FIG.

  First, a material pipe having a cylindrical shape and a substantially constant thickness is cut to a predetermined length, and the known butted process described above is applied to both ends of the material pipe 8 so that the head pipe side end portion 14 and the hanger lug side end portion 16 are formed. Form. Next, if necessary, small items (screws 18 or metal fittings 20) are attached to the intermediate portion of the material pipe 8, and then the outer surfaces of the head pipe side end portion 14 and the hanger lug side end portion 16 are covered with masking tape for masking. Then, the masking portion 22 is formed. Here, masking is performed using a tape, but it may be performed by applying a paint, a silk screen, a photoresist, or the like.

  FIG. 5 shows the masking portion 22 in an expanded manner.

  Furthermore, a ceramic coating is applied to the material tube 8 to form a ceramic thin film of, for example, 5 to 50 μm on the surface of the material tube 8, and then the masking tape is removed to complete the pipe 8.

  Through the above-described steps, the pipe 8 is manufactured so that both end portions 14 and 16 are thick and the intermediate portion 10 is thinner than both end portions 14 and 16.

  Thereafter, the pipe 8 is welded and connected to the head pipe 4 and the hanger lug 6 at both ends.

  The ceramic coating process is a method for forming a thin film of TiN, TiC, CrN or the like with good adhesion by ionizing metal atoms evaporated in a vacuum and applying a negative potential to the object to be processed. Since it is a known technique, its description is omitted. This coating is performed in order to adjust the frame rigidity by applying a predetermined film thickness only to a portion where rigidity is required or according to customer preference.

  Further, if a ceramic coating is to be applied to the entire frame, a large processing device is required. However, in the case of a ceramic coating of a single pipe, processing can be performed with a relatively small device.

  According to the manufacturing method according to the present invention, a mold or machining is not required, and the production unit price is relatively low while performing a variety and small quantity production. Further, by accommodating a plurality of material pipes in the coating apparatus at a time, a plurality of bicycle frame pipes can be obtained at a time, and the work efficiency is improved. Further, since machining is not performed, the bicycle frame pipe can be formed in a good shape even if the bicycle frame pipe has a long dimension, and the bicycle frame pipe can be manufactured with high accuracy.

  In the above embodiment, the lower pipe 8 whose both ends are connected to the head pipe 4 and the hanger lug 6 has been described as an example. However, other pipes constituting the bicycle frame 2 such as an upper pipe, a standing pipe, and a chain stay are used. Of course, the present invention can also be applied to the production of back hawks, hawk feet, hawk stems, and the like.

  In the above embodiment, the material pipe of the bicycle frame pipe has been described as an example of a cylindrical shape with a substantially constant wall thickness. However, the material pipe is not limited to a cylindrical shape, but is a quadrangular prism, a triangular prism, a triangular pyramid. A cone, a quadrangular pyramid, or the like may be bent.

  Furthermore, in the above-described embodiment, the case where a double butted pipe is manufactured in which both end portions have a thick wall shape and the middle portion thereof has a thin wall shape is not limited to this. When manufacturing single butted pipes with a thick wall shape only at the center and a thin wall at the other and the other end, or a thick wall shape with different thicknesses at both ends, and a thin wall at the middle It can also be applied to the case of manufacturing a triple butted pipe.

  In the above embodiment, both end portions 14 and 16 of the material tube 8 are masked. Particularly, a portion having a wall thickness of a predetermined value or more, a portion to be welded to other members, etc. are coated with ceramics. This is a part that does not need to be applied or a part that should not be applied. Basically, a ceramic coating is applied to the material pipe 8 excluding such a part.

  Furthermore, in the above embodiment, the case where the material is titanium has been described as an example. However, the present invention is not limited to this, and materials such as magnesium, aluminum, carbon steel, stainless steel, and beryllium are also used as the material. Can do.

  FIG. 6 shows changes in rigidity when a ceramic coating is applied to a material tube made of a titanium alloy having a thickness of 0.3 mm, 0.5 mm, 1 mm, or 3 mm while changing the film thickness. The vertical axis indicates the rigidity after ceramic coating when the base material (material tube) is 100.

  As can be seen from the graph of FIG. 6, the lower the wall thickness, the greater the rate of increase in rigidity due to the ceramic coating. In particular, when the ceramic coating is applied to a material pipe having a wall thickness of 0.5 mm or less, the increase in rigidity is significant. Therefore, it can be seen that when the thinnest portion of the material tube is 0.5 mm or less, it is particularly advantageous to apply a ceramic coating to that portion.

  The method for manufacturing a bicycle frame member according to the present invention can ensure a sufficient strength or rigidity even with a thin hollow member, is not easily scratched, and has various color tones while maintaining a metallic luster. Therefore, it is particularly useful for special bicycles such as racing bicycles that are manufactured by order production and require weight reduction or design.

It is a right view which shows the flame | frame of the bicycle concerning this invention. The material pipe used for the manufacturing method of the member for bicycle frames concerning the present invention is shown, (a) is the partially notched front view, (b) is the front view after butted processing, (c) is after butted processing It is sectional drawing. It is a front view which shows the other example of the raw material pipe | tube after butted processing shown by FIG.2 (b). It is a front view which shows each process of the manufacturing method of the member for bicycle frames concerning this invention. It is an expanded view of the masking part in the manufacturing method shown by FIG. It is a graph which shows the change of the rigidity at the time of changing a film thickness with respect to the raw material pipe | tube of various thickness, and giving a ceramic coating. (A) And (b) is sectional drawing which shows each process of the manufacturing method of the conventional pipe for bicycle frames by the cold processing of a roll method, respectively. It is sectional drawing which shows the manufacturing method of the conventional pipe for bicycle frames by the cold working of a drawing method. (A) And (b) is sectional drawing which shows each process of the manufacturing method of the pipe for bicycle frames by the conventional chemical milling, respectively.

Explanation of symbols

2 Bicycle frame,
4 Head pipe,
6 Hangarag,
8 Lower pipe,
10 Middle part of the lower pipe,
12 steps,
14 Head pipe side end,
16 Hanger lug side end,
18 Screws for water bottle support fittings,
20 Shift lever mounting bracket,
22 Masking part.

Claims (11)

A method for manufacturing a member for a bicycle frame, wherein the outer peripheral surface of the hollow member is selectively masked, and the outer peripheral surface of the hollow member excluding the masked portion is ceramic-coated. The method for manufacturing a member for a bicycle frame according to claim 1, wherein the masked portion is at least one end portion of the hollow member. 3. The method for manufacturing a member for a bicycle frame according to claim 1, wherein at least one end portion of the hollow member is subjected to butted processing before selectively masking the outer peripheral surface of the hollow member. The method for manufacturing a member for a bicycle frame according to any one of claims 1 to 3, wherein a thickness of the thinnest portion of the hollow member is 0.5 mm or less. The method for manufacturing a member for a bicycle frame according to any one of claims 1 to 4, wherein a portion of the hollow member that is welded to another member is masked. The method for manufacturing a member for a bicycle frame according to any one of claims 1 to 4, wherein a portion of the hollow member having a thickness equal to or greater than a predetermined value is masked. The method of manufacturing a member for a bicycle frame according to any one of claims 1 to 6, wherein the method is used for a bicycle frame by order production. It is used for the frame of a competition bicycle, The manufacturing method of the member for bicycle frames of any one of Claim 1 thru | or 7 characterized by the above-mentioned. The method for manufacturing a member for a bicycle frame according to any one of claims 1 to 8, wherein the method is used for adjusting the rigidity of the frame according to a user of the bicycle. The method for manufacturing a member for a bicycle frame according to any one of claims 1 to 9, wherein the hollow member is made of titanium alloy or titanium. A bicycle comprising the bicycle frame member manufactured by the method for manufacturing a bicycle frame member according to any one of claims 1 to 10.

Images