Frame unit for a bicycle and method for producing the same

Abstract

Frame unit for a bicycle, comprising: a left frame body (41) comprising a part of a head tube (3), a part of a seat tube (5), a part of a frame (7) and a left stay (11) which are formed integrally with each other; and a right frame body (43) comprising a part of the head tube (3), a part of the seat tube (5), a part of the frame (7) and a right stay (11a) which are formed integrally with each other; wherein the left frame body (41) and the right frame body (43) are coupled such that they integrally form the head tube (3), the seat tube (5) and the frame (7); and a seat tube (21) formed into a cylindrical shape by stepwise press working, inserted into the seat tube (5) and then coupled to the seat tube (5), the seat tube (21) comprising: a stepped portion (45) projecting on an outer periphery of an upper portion of the seat tube (21) such that a seat clamp (51) can be mounted on the outer periphery of the stepped portion (45); and a support projection (47) projecting from the central portion of the seat tube (21) to form a welding surface portion (53) welded to the seat tube (5).

Description

[0001] The present invention relates to a frame unit for a bicycle and a method of manufacturing the same, and more particularly to a frame unit for a bicycle comprising a head tube, a seat tube, a frame, and left and right stays, and a method of manufacturing the same.

[0002] In general, a bicycle frame unit is an assembly that forms an overall structure of a bicycle and is made by joining components such as a head tube, a seat tube, a frame, and left and right stays together.

[0003] Recently, in order to realize various designs and ensure strength for safety, materials such as aluminum, chromium molybdenum steel, carbon and titanium are used instead of high-strength steel material that is generally used.

[0004] Fig. 1 is a configuration diagram of a frame unit for a bicycle according to the related art.

[0005] With reference to Fig. 1, a frame unit 100 for a bicycle according to the related art includes a head tube 101, a seat tube 103, an upper frame 105, a lower frame 107, and upper and lower stays 109 and 111 arranged on both sides.

[0006] A steering tube (not shown) to which a handlebar is connected is installed on the head tube 101, and a seat tube (not shown) connected to a seat is installed on the seat tube 103.

[0007] The upper and lower frames 105 and 107 connect and support the head tube 101 and the seat tube 103.

[0008] Rear ends of the two upper and lower struts 109 and 111 are connected to each other in such a way that they form a rotary body fork 113 on which a rear wheel is mounted.

[0009] A front end of the lower stay 111 is connected to a pedal assembly 115 configured at a lower end of the seat tube 103.

[0010] Meanwhile, the frame unit 100 for a bicycle mainly includes both the upper frame 105 and the lower frame 107, but in some cases, only a single frame, that is, only the upper frame 105 between the head tube 101 and the seat tube 103 may be used.

[0011] However, according to the related art bicycle frame unit 100 having the above-mentioned configuration, when the head tube 101, the seat tube 103, the upper frame 105, the lower frame 107, and the upper and lower stays 109 and 111 are joined together by welding, residual stress due to welding heat is distributed among the joint portions. In particular, impact loads are directly applied when the bicycle is running, causing serious safety problems such as fractures or damage occurring at the periphery of the joint portions.

[0012] In particular, since the welding process is performed after the head pipe 101 undergoes a separate preheating process according to a difference in thickness between the upper and lower frames 105 and 107 when the head pipe 101 is joined to the upper and lower frames 105 and 107, there is a disadvantage in that a welding failure occurs if the preheating process is not performed properly.

[0013] In addition, since the process of welding the joint sections is carried out manually, a substandard rate is high because there is a difference in welding quality according to the skill of workers and the working environment, and thus there are disadvantages in that excessive working time is required and productivity deteriorates.

[0014] The information disclosed in this Background of the Invention section is provided merely to enhance the understanding of the general background of the invention and should not be considered as an admission or any form of suggestion that this information constitutes prior art already known to a technically skilled person.

[0015] GB 710 162 A describes a frame unit for a bicycle, comprising a left frame body having a part of a head tube, a part of a seat tube, a part of a frame and a left stay which are formed integrally with each other, and a right frame body having a part of the head tube, a part of the seat tube, a part of the frame and a right stay which are formed integrally with each other, wherein the left frame body and the right frame body are coupled so as to form the head tube, the seat tube and the frame integrally, and a seat tube which is inserted into the seat tube and then coupled to the seat tube.

[0016] Further frame units for a bicycle are known from US 2 089 889 A, US 589 868 A and US 6 109 638 A.

[0017] The object of the present invention is to provide a frame unit for a bicycle and a method for producing the same with the advantages of improving rigidity and design quality.

[0018] The object is achieved according to the invention by a frame unit for a bicycle according to the features of claim 1 and a method for producing a frame unit for a bicycle according to the features of claim 4. Advantageous further developments are described in the subclaims.

[0019] Various aspects of the present invention provide a frame unit for a bicycle, comprising a left frame body in which a part of a head tube, a part of a seat tube, a part of a frame, and a left stay are integrally formed, and a right frame body in which a part of the head tube, a part of the seat tube, a part of the frame, and a right stay are integrally formed, wherein the left frame body and the right frame body are coupled to integrally form the head tube, the seat tube, and the frame, and a seat tube formed into a cylindrical shape by stepwise press working is inserted into the seat tube and then coupled to the seat tube.

[0020] The seat tube has a stepped portion protruding from an outer periphery of an upper portion of the seat tube such that a seat clamp can be mounted on the outer periphery of the stepped portion, and a support projection protruding from the middle portion of the seat tube such that it forms a welding surface portion welded to the seat tube.

[0021] The seat tube may have a thickness that is substantially the same as a thickness of the seat tube.

[0022] The left frame body and the right frame body can be coupled by a welding process.

[0023] Various aspects of the present invention provide a method of manufacturing a frame unit for a bicycle, comprising: compression molding a left frame body, wherein a part of a head tube where a steering tube is mounted thereon, a part of a seat tube where a seat tube is mounted thereon, a part of a frame configured to integrally connect the head tube and the seat tube and form a body of the bicycle, and a left stay are integrally molded; compression molding a right frame body, wherein a part of the head tube, a part of the seat tube, and a right stay are integrally molded; coupling the left frame body and the right frame body to each other along edges of the left and right frame bodies; and inserting a seat tube, which is formed into a cylindrical shape by stepwise press working, into the seat tube; and coupling the seat tube to the seat tube.

[0024] The seat tube has a stepped portion protruding from an outer periphery of an upper portion of the seat tube such that a seat clamp can be mounted on the outer periphery of the stepped portion, and a support projection protruding from the middle portion of the seat tube such that it forms a welding surface portion welded to the seat tube.

[0025] The seat tube can have a thickness that is equal to or similar to the thickness of the seat tube.

[0026] The seat tube may be formed by press-molding a flat sheet so as to obtain the stepped portion and the seating projection, press-molding the flat sheet into a cylindrical shape, press-molding a projection and a recessed portion at ends of the sheet, and welding the projection and the recessed portion.

[0027] According to the frame unit for a bicycle according to various aspects of the present invention, a head tube, a seat tube, a frame, a pedal assembly, and left and right stays are integrally molded without a connecting portion with the main frame, so that residual stress due to welding heat at a connecting portion according to the related art can be prevented, and a factor causing deterioration of the connecting rigidity due to the residual stress can be eliminated.

[0028] Accordingly, the rigidity and durability between the head tube and the frame are stably maintained with respect to a shock load transmitted from a road surface and a fatigue load of the frame unit itself, thereby preventing damage such as breakage and ensuring safety.

[0029] In addition, a welding process is performed along the edges of the left and right frame bodies when the left and right frame bodies are joined, so that the welding processes can be easily automated, the working hours can be reduced as a result of automation, and the quality and productivity of welding can be improved.

[0030] Since the seat tube is designed to have a thickness equal to or similar to that of the seat tube, the seat tube can be immediately joined to the seat tube without a separate preheating process, thereby improving the welding quality and reducing the time required during the working process.

[0031] Since the seat tube is formed by compression molding to have a thickness equal to or similar to a thickness of the seat tube, the seat tube can be compatible with other saddles, and productivity can be improved.

[0032] The methods and apparatus of the present invention have other features and advantages which will be apparent from, or set forth in more detail in, the accompanying drawings incorporated herein and the following detailed description, which together serve to explain certain principles of the present invention. Fig. 1 is a configuration diagram of a frame unit for a bicycle according to the related art. Fig. 2 is a side view of a bicycle to which an exemplary frame unit for a bicycle according to the present invention is applied. Fig. 3 is a perspective view of an exemplary frame unit for a bicycle according to the present invention. Fig. 4 is an exploded perspective view of an exemplary frame unit for a bicycle according to the present invention. Fig. 5 is a side sectional view illustrating an exemplary configuration of a seat tube according to the present invention. Fig. 6 is a perspective view of an exemplary seat tube according to the present invention.

[0033] Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) have been described in connection with exemplary embodiments, it is to be understood that the present description is not intended to limit the invention(s) to these exemplary embodiments. On the contrary, the invention(s) are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments which may be included within the spirit and scope of the invention as defined by the appended claims.

[0034] A part irrelevant to the description is omitted in order to clearly describe the present invention, and the same or similar elements are denoted by the same reference numerals throughout the description.

[0035] The size and thickness of each component shown in the drawings are shown arbitrarily for clarity and ease of description, but the present invention is not limited thereto. The thicknesses of the various sections and regions are exaggerated for clarity.

[0036] Furthermore, in the following detailed description, names of components which are in the same relationship are classified into “the first”, “the second” and the like, but the present invention is not limited to the order in the following description.

[0037] Throughout the specification and claims, unless expressly stated to the contrary, the word "comprise" and variations such as "comprises" or "having" are intended to include stated elements but not to exclude any other elements.

[0038] In addition, “unit,” “means,” “part,” “element,” or the like described in the specification means a unit of a comprehensive configuration that performs at least one function or activity.

[0039] Fig. 2 is a side view of a bicycle to which a frame unit for a bicycle according to various embodiments of the present invention is applied, Fig. 3 is a perspective view of the frame unit for a bicycle according to various embodiments of the present invention, and Fig. 4 is an exploded perspective view of the frame unit for a bicycle according to various embodiments of the present invention.

[0040] With reference to the Fig. 2 to 4, a frame unit 1 for a bicycle according to various embodiments of the present invention comprises a head tube 3, a seat tube 5, a frame 7, a pedal assembly 9, and left and right stays 11 and 11a.

[0041] A steering tube 15, on which a handlebar 13 is mounted, is installed on the head tube 3, and a front wheel 19 is installed on a fork 17 configured on a lower side of the steering tube 15.

[0042] A saddle 23 is installed on the seat tube 5 by means of a seat tube 21.

[0043] The frame 7 may include an upper extension frame 25 configured to integrally connect the head tube 3 and the seat tube 5, and a lower extension frame 27 integrally connected to the pedal assembly 9, and forms a body of a bicycle 29. It is appreciated that such integral components may be monolithically formed.

[0044] The left and right stays 11 and 11a each have an upper stay 31 and a lower stay 33, and rear ends of the two upper stays 31 and rear ends of the two lower stays 33 are connected to each other to form a rotary fork 37 on which a rear wheel 35 is mounted.

[0045] Further, front ends of the two upper stays 31 are connected to the seat tube 5, and front ends of the two lower stays 33 are connected to the pedal assembly 9 configured on a lower side of the seat tube 5.

[0046] The pedal assembly 9 may be formed to project downward at a lower side between the frame 7 and the two lower stays 33, and a pedal 9a connected to the rear wheel 35 via a chain 39 is installed on the pedal assembly 9.

[0047] Here, the head tube 3, the seat tube 5, the frame 7, the pedal assembly 9, and the left and right stays 11 and 11a are formed on a left frame body 41 and a right frame body 43, which are integrally molded. It is appreciated that such integral components may be monolithically molded.

[0048] Further, the left and right frame bodies 41 and 43 are connected along the edges thereof so as to form an overall configuration of the frame unit 1 for a bicycle.

[0049] The left and right frame bodies 41 and 43 are joined to each other by a welding method, and in this case, the welding method may be an arc welding method or the like.

[0050] Fig. 5 is a side sectional view illustrating a configuration of a seat tube according to various embodiments of the present invention, and Fig. 6 is a perspective view of a seat tube according to various embodiments of the present invention.

[0051] With reference to the Fig. 5 and Fig. 6, the seat tube 21 mounted on the seat tube 5 is formed into a cylindrical shape by stepwise press working, and a stepped portion 45 and a seating projection 47 are formed at an upper portion and a middle portion thereof.

[0052] The stepped portion 45 projects on an outer periphery of the seat tube 21, and a seat clamp 51 is mounted on the outer periphery of the stepped portion 45 for clamping a seat post 49 where the saddle 23 is attached.

[0053] The support projection 47 protrudes at the central portion thereof to form a welding surface portion 53 contacting the seat tube 5.

[0054] The seat tube 21 may have a thickness equal to or similar to that of the seat tube 5.

[0055] An inner diameter of the seat tube 21 is determined according to an outer circumference of the seat post 49.

[0056] In this case, a gap may be formed between the inner diameter of the seat tube 21 and the outer circumference of the seat post 49. However, the seat clamp 51 may prevent movement of the seat post 49 by clamping the seat post 49.

[0057] Therefore, the seat tube 21 can adapt to different seat posts 49 of different sizes.

[0058] According to the frame unit 1 for a bicycle according to various embodiments of the present invention having the above-mentioned configuration, the head tube 3, the seat tube 5, the frame 7, the pedal assembly 9, and the left and right stays 11 and 11a are integrally molded without a connecting portion, so that residual stress due to welding heat at a connecting portion according to the related art can be prevented, and a factor causing deterioration of the connecting rigidity due to the residual stress can be eliminated.

[0059] In addition, an occurrence of a safety accident due to fractures and damages occurring in the connecting portion is reduced, and the rigidity and durability between the head tube 3 and the frame 7 with respect to an impact load transmitted from a road surface and a fatigue load of the frame unit itself are stably maintained.

[0060] Further, the left and right frame bodies 41 and 43 constituting the bicycle frame unit 1 are integrally formed, thereby making the overall external appearance of the bicycle frame unit 1 aesthetically attractive.

[0061] In addition, welding beads, which are formed when the left and right frame bodies 41 and 43 are joined, are not directly exposed on a surface, so that an influence on the design of the entire external appearance of the frame unit 1 for a bicycle is minimized.

[0062] In addition, welding is performed along the edges of the left and right frame bodies 41 and 43 when the left and right frame bodies 41 and 43 are joined, so that the welding processes can be automated, the working hours can be reduced as a result of the automation, and the quality and productivity of welding can be improved.

[0063] In addition, since the seat tube 21 is formed to have a thickness equal to or similar to a thickness of the seat tube 5, the seat tube 21 can be immediately joined to the seat tube 5 without a separate preheating process, thereby improving the welding quality and reducing the time required during the working process.

[0064] Hereinafter, a method of manufacturing the frame unit 1 for a bicycle according to various embodiments of the present invention described above will be described with reference to Fig. 3 to 6.

[0065] First, the seat tube 5, the frame 7, the pedal assembly 9 and the left and right stays 11 and 11a are integrally molded, and the left and right frame bodies 41 and 43, which are symmetrical to each other, are respectively compression-molded as shown in Fig. 4 is shown.

[0066] Thereafter, the left and right frame bodies 41 and 43 formed by a press are joined together by welding along the edges of the left and right frame bodies 41 and 43 and manufactured as the frame unit 1 for a bicycle as shown in Fig. 3 is shown.

[0067] The seat tube 21, which is formed into a cylindrical shape by step-by-step press processing, is inserted into the seat tube 5 and then coupled to the seat tube 5.

[0068] The stepped portion 45 protrudes on the outer periphery of the seat tube 21, the seat clamp 51 is mounted on the outer periphery of the stepped portion 45 for clamping the seat post 49, and the support projection 47 protrudes at the middle portion thereof to form a welding surface portion 53 for welding with the seat tube 5.

[0069] The seat tube 21 is formed by step-by-step press processing.

[0070] That is, a flat sheet is press-formed to form the stepped portion 45 and the support projection 47, and then formed into a cylindrical shape into the seat tube 21 through a series of press-forming processes.

[0071] A projection 55 and a recessed portion 57 are formed by compression molding at ends of the sheet (the seat tube 21), and then the projection 55 and the recessed portion 57 are coupled.

[0072] The seat tube 21 may have a thickness equal to or similar to that of the seat tube 5.

[0073] In addition, since the seat tube 21 is formed to have a thickness equal to or similar to a thickness of the seat tube 5, the seat tube 21 can be immediately joined to the seat tube 5 without a separate preheating process, thereby improving the welding quality and reducing the time required during the working process.

[0074] Since the seat tube 21 is formed to have a thickness equal to or similar to a thickness of the seat tube 5, the seat tube 21 can be compatible with other saddles.

[0075] Since the seat tube 21 is formed by a compression molding process, the quality of the seat tube 21 is stable, and the thickness of the seat tube 5 can be reduced, so that the overall weight of the frame unit 1 can be reduced.

[0076] For ease of explanation and precise definition in the appended claims, the terms top or bottom, front or back, etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as shown in the figures.

Claims

[1] Frame unit for a bicycle, comprising: a left frame body (41) comprising a part of a head tube (3), a part of a seat tube (5), a part of a frame (7) and a left stay (11) which are formed integrally with each other; and a right frame body (43) comprising a part of the head tube (3), a part of the seat tube (5), a part of the frame (7) and a right stay (11a) which are formed integrally with each other; wherein the left frame body (41) and the right frame body (43) are coupled such that they integrally form the head tube (3), the seat tube (5) and the frame (7); and a seat tube (21) formed into a cylindrical shape by stepwise press working, inserted into the seat tube (5) and then coupled to the seat tube (5), the seat tube (21) comprising: a stepped portion (45) projecting from an outer periphery of an upper portion of the seat tube (21) such that a seat clamp (51) can be mounted on the outer periphery of the stepped portion (45); and a support projection (47) projecting from the central portion of the seat tube (21) to form a welding surface portion (53) welded to the seat tube (5). [2] The frame unit according to claim 1, wherein the seat tube (21) has a thickness substantially the same as a thickness of the seat tube (5). [3] The frame unit according to claim 1, wherein the left frame body (41) and the right frame body (43) are coupled by a welding process. [4] Method for producing a frame unit (1) for a bicycle, comprising: compression molding a left frame body (41), wherein a part of a head tube (3) where a steering tube (15) is mounted thereon, a part of a seat tube (5) where a seat tube (21) is mounted thereon, a part of a frame (7) configured to integrally connect the head tube (3) and the seat tube (5) and form a body of the bicycle, and a left stay (11) are integrally molded; compression molding a right frame body (43), wherein a part of the head tube (3), a part of the seat tube (5) and a right stay (11a) are integrally molded; coupling the left frame body (41) and the right frame body (43) to each other along edges of the left and right frame bodies (41, 43); and Inserting a seat tube (21) which is formed into a cylindrical shape by stepwise press working into the seat tube (5), and coupling the seat tube (21) to the seat tube (5), wherein the seat tube (21) comprises: a stepped portion (45) projecting from an outer periphery of an upper portion of the seat tube (21) such that a seat clamp (51) can be mounted on the outer periphery of the stepped portion (45); and a support projection (47) projecting from the central portion of the seat tube (21) to form a welding surface portion (53) welded to the seat tube (5). [5] The method of claim 4, wherein the seat tube (21) has a thickness substantially the same as a thickness of the seat tube (5). [6] Method according to claim 4, wherein the seat tube (21) is formed by: compression molding a flat sheet to obtain the stepped portion (45) and the support projection (47); Forming the flat sheet into a cylindrical shape; compression-molding a projection (55) and a recessed portion (57) at ends of the sheet; and Welding the projection (55) and the recessed section (57).

Images