ITMI951896A1 - REGULATORY COMPOSITE BICYCLE FRAME AND PROCEDURE FOR ITS CONSTRUCTION - Google Patents

Abstract

A composite regulatory bicycle frame is disclosed which comprises a portion of a radiant front frame and a portion of a rear frame. The front frame portion comprises a central main tube and a plurality of legs radiating therefrom. The rear frame portion comprises the rear fork connected to the front frame portion, the rear fork having a left rear branch and a right rear branch. The composite regulatory bicycle frame is constituted by a process which includes the steps which consist of: (a) superimposing a plurality of first prepreg layers on a first mandrel to form an unhardened left rear branch and a non right rear branch hardened, each of the first prepreg layer containing a fibrous material impregnated with a curable synthetic resin; (b) removing the unhardened left and right rear branches from the first mandrel and heating the left and right unhardened rear branches in a first mold to form hardened left and right rear branches; (c) overlapping a plurality of second prepreg layers to form an unhardened front frame portion, which contains a hollow central tube and a plurality of hollow legs connected thereto, each of the second prepreg layers containing a fibrous material impregnated with a curable synthetic resin; (d) joining the hardened left and right rear branches to the unhardened front frame portion with a plurality of third prepreg layers, wherein the third prepreg overlaps one or the other or both the left and right rear branches hardened with the uncured front frame portion, each of the third prepreg layers contains a fibrous material impregnated with a curable synthetic resin; and (e) heating and hardening the portion of the unhardened front frame within a second mold to form a bicycle frame. The hardened left and right rear branches can be joined separately to the uncured front frame portion; or they can be glued together at their respective abutment surfaces to form the integral rear fork before they are joined to the uncured front frame portion.

Description

DESCRIPTION

The present invention relates to bicycle frames and their manufacturing process. More particularly, the present invention relates to bicycle frames of a regulatory type made of composite materials, and a process for applying the same. The regulatory type bicycle frames are non-lozenge shaped bicycle frames having a front frame portion, which contains a hollow central tube and a plurality of hollow arms connecting between the hollow central tube and various supporting means, such as the steering support, saddle support means, and pedal means, respectively, and a rear frame portion, which contains a single rear fork connected to the rear wheel support means.

A lozenge-shaped conventional bicycle frame comprises a front triangle and a rear triangle. The front triangle includes (a) a head tube for connecting the bicycle handlebar and the front wheel assembly; (b) a saddle tube having an upper portion connecting the bicycle saddle and a lower portion connected to the pedal support; (c) an upper tube connecting between the head tube and the upper portion of the saddle tube; and (d) a lower tube connecting between the head tube and the lower portion of the saddle tube.

On the other hand, the rear triangle of the conventional lozenge-shaped frame comprises: (a) a right seat stay tube, for connecting between the upper left portion of the seat post and the left portion of the rear wheel assembly, and the upper right of the seat tube and the right portion of the rear wheel assembly, respectively; and (c) a left chain tie tube and (d) a right chain tie tube, for connecting between the lower left portion of the seat tube and the left portion of the rear wheel assembly, and the lower right portion of the rear wheel assembly. saddle and the right portion of the rear wheel assembly, respectively. The left seat stay tube and the right seat stay tube are commonly, and collectively, referred to as the "rear upper fork". And the left chain stay tube and right chain stay tube are commonly, and collectively, called "rear lower fork".

One of the drawbacks that has been recognized with the conventional lozenge shaped frame is the relatively large number of tubes and joints that have to be supplied and welded, brazed or glued together. This is further complicated by the need to connect pipes of different sizes and materials, thus resulting in time consuming and relatively fatigue-intensive manufacturing process, and high manufacturing cost.

In order to improve complexity and reduce the cost associated with manufacturing bicycle frames, so-called regulatory-type bicycle frames have been developed which combine the different tubular components of the front triangular frame portion of traditional lozenge-shaped frames into one shape. radiating, typically a Y-shaped frame body, and the rear triangular frame portion is reduced to include only either a rear lower fork or a rear upper fork, each fork would comprise two branches, one on the left, and the other on the right , of the rear wheel.

Another approach to simplify the process of manufacturing traditional lozenge-shaped bicycle frames is to use so-called unitary bicycle frames, which are taught in U.S. Patent Nos. 4,850,607; 4,889,355; 4,902,458; 4,941,674; 4,982,975 and 4,986,949, their content is expressly incorporated by reference. In the manufacture of unitary bicycle frames, no welding or adhesion is required, and the finished bicycle frame has no abutment joints. Unit bicycle frames that are made from composite fibers are also substantially lighter than metal frames. Unit bicycle frames have the disadvantages that they require relatively complicated molds to manufacture, and the thickness of the finished products often becomes too large resulting in undesirably heavy weight of the finished bicycle frame. Also, because high molding accuracy is required, the molds are expensive to build. The unit molding process typically involves three bulky mold elements, which often could be misaligned, causing errors in the straightness of the finished bicycle frame.

U.S. Patent No. 4,850,607 discloses a bicycle frame comprising (1) steering support means for supporting a front fork assembly; (2) saddle support means for supporting a saddle assembly; (3) pedal support means for supporting a pedal crank assembly; (4) rear wheel support means for supporting a rear wheel assembly; and (5) a hollow unitary frame component extending between at least two of the support means. The hollow unitary frame component comprises at least one hollow joint connected to at least one portion of hollow tube. The hollow portion comprises at least one elongated strip of resin-impregnated fibrous material and the hollow seam comprises at least one corner plate of the same resin-impregnated fibrous material. The tube strip is integrally joined to the corner plate by overlapping edges molded together along a stamped joint to provide a unitary wall integrally joining the tube portion and the hollow joint. The unitary bicycle frames disclosed in the '607 patent have the advantages that no welding or adhesion is required, and the finished bicycle frame has no abutment seam. Also, since unitary bicycle frames are made of composite fibers, they are also substantially lighter than metal frames.

The process described in the '607 patent, however, cannot be applied to the manufacture of the regulatory type bicycle frames described above. Since a regulatory type bicycle frame is built with a small number of components, the component size must be substantially increased. In short, a regulation-type bicycle frame is constructed like an octopus (with reduced number of legs); it typically comprises a front frame portion, which contains a hollow center tube and a plurality of hollow arms connecting between the hollow core tube and various support means, such as steering support means, saddle support means, and pedal, respectively, and a portion of the rear frame, which contains either a rear lower fork or a rear upper fork, only. The lower or upper rear fork is not connecting between two support means; instead, it is connected to the anterior portion. As a consequence, there is no tube portion extending between at least two of the support means as contemplated in the '607 patent. Hence the fundamentally different design of regulatory-type bicycle frames makes the process described in the '607 patent largely inapplicable.

In the US Patent No. 4,902,458, which is a continuation in part of the '607 patent, a more detailed procedure for building the hollow unitary bicycle frame is described. The '458 patent teaches a process which, among other things, comprises the step which consists in forming a section of tube comprising at least one elongated strip of fibrous material impregnated with a synthetic resin and two joining sections each comprising at least one plate of fibrous material. impregnated with a hardenable synthetic resin, the joint plates and the tube strip each being separate pieces of the resin impregnated fibrous material such that the sections are separated from each other. Each end of the tube section is overlapped with a joint section to form a hollow shell extending between two support means. Uncured portions of the shell are compressed against the surfaces! of a mold by means of an inflatable bladder directed outwards through a passage passing through a metal sleeve. Furthermore, the process described in document '458 is mainly applicable to the manufacture of traditional lozenge-shaped frames, which are based on a combination of connecting tube sections, it is not applicable to the manufacture of regulatory type bicycle frames, which are not contain sections of connecting pipe.

In U.S. Patent No. 4,888,355, which is also a continuation in part of the '458 patent, a bicycle frame is disclosed comprising a hollow unitary frame component extending longitudinally between and connecting at least two of steering support means, means of saddle support, pedal support means, and rear wheel support means, and the method of building such unitary frame component. The hollow unitary frame component comprises at least two adjacent wall sections each of which comprises at least one molded layer of fibrous material impregnated with a synthetic resin. The adjacent wall sections are integrally joined by at least one joining seam integrally comprising a pair of overlapping edges of the adjacent wall sections. The seam provides a substantially continuous wall of the resin impregnated fibrous material around an internal cavity of the hollow unitary frame component. The process described in the '355 patent is also mainly applicable to traditional lozenge-shaped bicycle frames, whereby the dimensions of the components in the front triangle and in the rear triangle are comparable. For regulatory type bicycle frames, since the size of the front frame portion is substantially larger than that of the rear frame portion, it is essentially impossible to have an internal cavity that is molded together to cover both the front frame portion and the rear frame portion. posterior portion in the manner taught by the '355 patent. Furthermore, the process described in document '355 serves to construct relatively straight pipe portions, which are not present in regulatory type frames.

In U.S. Patent No. 4,986,949, which is a divisional application of the '355 patent, a method is disclosed for manufacturing a hollow bicycle frame component by forming at least two wall sections each comprising at least one layer of resin impregnated fibrous material. synthetic. A part of one of the wall sections is arranged to be placed in opposite relation to a corresponding part of the other of the wall section, and the resin of at least one of the parts is substantially uncured. The wall sections are placed adjacent to each other with the corresponding parts in opposite relationships. Thereafter, the opposite parts are transversely overlapped to form a longitudinally extending hollow shell between at least two of the support means, including the wheel support means. Again, the process described in the '949 patent is primarily designed to mold relatively thin tubular components by transversely overlapping slightly more than half of two wall sections together, is not suitable for manufacturing regulatory type bicycle frames, which involve a front frame portion. relatively bulky. Furthermore, in the regulatory type bicycle frame, the rear wheel support means are not directly connected to any other support means through the rear frame portion.

In United States Patent No. A,982,975, which is a divisional application of the '607 patent, a bicycle frame is described connecting at least two support means of the assembly consisting of steering support means, saddle support means, pedal support means, and rear wheel support means. The bicycle frame comprises a hollow unitary frame component which extends longitudinally between at least two support means and comprises at least two adjacent wall sections each comprising at least one molded layer of fibrous material impregnated with a synthetic resin. The adjacent wall sections are integrally joined by at least one pressure molded joint to provide the unit wall of the resin impregnated fibrous material around an internal cavity of the unitary frame component. The pressure-molded seam is formed by overlapping layers of the resin-impregnated fibrous material provided by overlapping portions of adjacent wall sections. The unitary frame component described in the '975 patent involves a portion of tube which extends longitudinally and connects between at least two support means; therefore, it is applicable only for conventional diamond-shaped bicycle frames and not for regulatory-type bicycle frames, which do not involve such a tube portion due to the substantially greater force required by the frame component.

The main object of the present invention is to develop a method for building bicycle frames with reduced weight and improved aerodynamics and style. More specifically, the main object of the present invention is to develop a process for building regulatory-type bicycle frames from composite materials, which contain fibrous materials impregnated with a synthetic resin. The regulatory type bicycle frames are non-diamond shaped bicycle frames having a front frame portion and a rear frame portion variously different from traditional lozenge-shaped frames. Instead of a front triangle, the regulatory type bicycle frame contains a hollow center tube and a plurality of hollow arms radiating from the hollow core tube and connecting between the hollow core tube and the different support means, such as the steering support means, saddle support means, and pedal means, respectively. In other words, the different tubular components of the front triangular frame portion of the traditional diamond-shaped frames are combined in a radiant-shaped front frame, such as Y-shaped, T-shaped, V-shaped, Z-shaped. rear frame of the regulatory type bicycle frame contains either a rear lower fork or a rear upper fork, but not both. Each fork comprises two branches, one on the left, and the other on the right, of the rear wheel. In other words, the rear triangular frame portion of conventional diamond-shaped frames is reduced to comprise only one fork. Since a regulatory type bicycle frame is constructed with a reduced number of components, the size of the constituent components must be substantially increased. Furthermore, a regulatory-type bicycle frame, whose appearance resembles that of an octopus (with reduced number of legs), implies a very different design from traditional lozenge-shaped frames; therefore, a new manufacturing concept is required to build this new type of bicycle frame.

In summary, the present invention describes a process for manufacturing regulatory-type bicycle frames, which comprise a radiating front frame portion and a rear frame portion, which includes either an upper fork or a lower fork connected to the front frame portion, each of the upper or front fork having left and right rear branches. The process described in the present invention comprises the following steps:

(a) superimposing a plurality of first layers of prepreg on a first mandrel to form the left and right uncured rear branches, each of the first layers of prepreg contains a fibrous material impregnated with a hardenable synthetic resin;

(b) remove the left and right rear uncured branches from the first mandrel and heat the left and right rear uncured branches in a first mold to form rear left and right hardened branches;

(c) superimposing a plurality of second layers of prepreg on a second mandrel assembly to form the uncured front frame portion, which contains a hollow core tube and a plurality of hollow legs connected thereto, each of the second prepreg layers contains a fibrous material impregnated with a hardenable synthetic resin;

(d) removing the uncured front frame portion from the second mandrel assembly;

(e) joining the cured left and right posterior branches to the uncured front frame portion with a plurality of third layers of prepreg, which overlap the uncured front frame portion with at least one or the other of the cured left branch; or of the rear right branch and, each of the third layers of prepreg contains a fibrous material impregnated with a hardenable synthetic resin;

(f) heating and hardening the uncured front frame portion within a second mold to form a bicycle frame.

The plurality of legs provided for connecting the center tube with steering support means, saddle support means, and pedal support means, respectively; while the rear fork connects the central tube with rear wheel support means. In a preferred embodiment, the steering support means is formed by wrapping a head tube with at least a fourth layer of prepreg, the saddle support means is formed by wrapping a saddle tube with at least a fourth layer of prepreg, and the pedal support means is formed by wrapping a pedal tube (i.e., a five-joint tube) with at least a fourth layer of prepreg. The steering support means, the saddle support means, the pedal support means are joined by overlapping the second layers of prepreg. Alternatively, the uncured front frame portion may be formed by superimposing a plurality of long strips or plates of the second prepregs on a plurality of tubes, these tubes being radiantly disposed from said hollow core tube to be formed to become part of the legs.

It is preferred that each of the first or second layers of prepreg contain 5 to 30 layers, more preferably 8 to 16 layers, of the fibrous material impregnated with a hardenable resin. An inflatable bladder may be placed within the cavity of the uncured front frame portion before it is placed in the second state to apply pressure on the prepreg layers during curing. Alternatively, a thermally expandable material can be placed in the cavity of the uncured front frame portion. The volume expansion of the thermally expandable material after heating also similarly exerts pressure on the prepreg layers against the inner wall of the mold during the curing process.

The process described in the present invention provides great flexibility for an essentially unlimited number of bicycle frames to be designed. Typical regulatory type frames that can be readily fabricated using the process disclosed in the present invention include Y-shaped, T-shaped, V-shaped, 2-shaped, etc. front frames. And the overall frame (i.e., after the front frame portion is integrated with the rear frame portion) can be designed to have an X, cross, Z, or 6 shape. The process described in the present invention is also extremely flexible which allows for a very wide variety and sizes and dimensions of frame components that must be designed and manufactured to meet any special needs. Furthermore, since regulatory type frames involve a substantially reduced number of components and joints, the present invention allows inexpensive bicycles to be manufactured which are very comfortable to use (due to the improved shock absorption and vertical impact capacity of bicycles regulatory type), simple to manufacture, extremely elegant, robust, aerodynamic, and can be shaped to satisfy a personal desire.

The present invention will be described in detail with reference to the drawings showing the preferred embodiment of the present invention, in which:

Figure 1 is a schematic drawing of a preferred embodiment of the present invention with a V-shaped front frame portion; the rear frame portion is connected to the intermediate part between the five-joint tube and the seat tube of the rear frame portion.

Figure 2 is a schematic drawing of another preferred embodiment of the present invention with a 7-shaped front frame portion; the rear frame portion is connected to the intermediate part between the five-joint tube and the seat tube of the front frame portion.

Figure 3 is a schematic drawing of yet another preferred embodiment of the present invention with a Y-shaped front frame portion; the rear frame portion comprises a rear lower fork.

Figure 4 is a schematic drawing of another preferred embodiment of the present invention with a T-shaped front frame portion; the rear frame portion is connected to the intermediate part between the joint tube and the seat tube of the front frame portion and the overall frame is shaped as an "X".

Figure 5 is a schematic drawing of yet another preferred embodiment of the present invention with a V-shaped front frame portion; the rear frame portion comprises a rear upper fork.

Figure 6 is a schematic drawing of yet another preferred embodiment of the present invention with another T-shaped front frame portion, the rear frame portion comprises a rear upper fork.

Figure 7 is a schematic drawing of yet another preferred embodiment of the present invention with yet another T-shaped front frame portion; the rear frame portion comprises a rear lower fork.

Fig. 8 is a schematic drawing of yet another preferred embodiment of the present invention with yet another T-shaped front frame portion; the rear frame portion comprises a rear lower fork.

Figure 9 is a schematic drawing of yet another preferred embodiment of the present invention with another 7-shaped front frame portion; the rear frame portion includes a rear upper fork and the overall frame is shaped like a "Z"

Figure 10 is a schematic drawing of yet another preferred embodiment of the present invention with yet another 7-shaped front frame portion; the rear frame portion comprises a rear upper fork.

Fig. 11 is a schematic drawing of yet another preferred embodiment of the present invention with yet another T-shaped front frame portion; the rear frame portion comprises a rear lower fork.

Figure 12 is a schematic drawing of yet another preferred embodiment of the present invention with yet another T-shaped front frame portion; the rear frame portion comprises a rear upper fork.

Figure 13 is a schematic drawing of yet another preferred embodiment of the present invention with a V-shaped front frame portion; the rear frame portion comprises a rear lower fork and the overall frame is shaped as an "e".

Figure 14 is a schematic drawing of a regulatory type bicycle frame with the so-called Y-shaped front frame portion; the rear frame portion comprises a rear lower fork.

Figure 15 is a top view of the mold used in constructing the rear lower fork (including the left rear branch and the right rear branch) shown in Figure 14.

Figure 15A is a cross-sectional view of the mold as shown in Figure 15 along the line 15A-15A.

Figure 15B is a cross-sectional view of the mold as shown in Figure 15 along the line 15B-15B.

Figure 16A is a top view of a cross-shaped mating protrusion formed on the upper side face of one of the two rear branches of the rear frame portion as shown in Figure 14.

Figure 16B is a side view of the cross-shaped mating protrusion as shown in Figure 16A.

Figure 17 is a top view of the left rear branch and the right rear branch of the Y-shaped frame as shown in Figure 14 after they are joined with the five-joint tube (i.e., the pedal tube) and portion of front frame.

Fig. 18 is a revealed view of the uncured front frame portion with the cured rear frame portion attached thereto, in accordance with the Y-shaped frame as shown in Fig. 14 which has been placed inside a mold.

Figure 18A is the cross-sectional view along the line 18A-18A of Figure 18.

Figure 18B is the cross-sectional view along line 18B-18B of Figure 18.

Figure 18C is the cross-sectional view along line 18C-18C of Figure 18.

Figure 18D is the cross-sectional view along line 18D18D of Figure 18.

Figure 18E is the cross-sectional view along line 18E-18E of Figure 18.

Figure 18F is the cross-sectional view along line 18F-18F of Figure 18.

Figure 18G is the cross-sectional view along line 18G-18G of Figure 18.

Figure 18H is the cross-sectional view along the line 18H-18H of Figure 18.

Figure 19 is a revealed view of an embodiment of the curing / pressurizing operation using the mold of Figure 18, showing that an inflatable bladder is placed within the cavity of the uncured front frame portion; the inflatable bladder is connected to a flexible tube for supplying air entering through the head tube.

Figure 20 is a revealed view of another embodiment of the curing / pressurizing operation using the mold of Figure 18, showing that an inflatable bladder is placed within the cavity of the uncured front frame portion ; the inflatable bladder is connected to a flexible tube for supplying air entering through the seat tube.

Figure 21 is a revealed view of yet another embodiment of the curing / pressurizing operation using the mold of Figure 18, showing that two inflatable bladders are placed within the cavity of the front frame portion not hardened; the inflatable bladders are connected to two hoses supplying air entering through the head tube and the saddle tube, respectively.

The present invention describes a process for constructing composite regulatory-type bicycle frames, which comprise a radiating front frame portion and a rear frame portion. The front frame portion comprises either an upper fork or a lower fork connected to the front frame portion, but not both; each of the upper or front fork having left and right rear branches. The regulatory-type bicycle frames differ from the traditional lozenge-shaped frames mainly due to the fact that the regulatory-type frames do not contain tubular components, which are the main components of the lozenge-shaped frames for connection between the different support means, such as the steering support means for supporting the front fork assembly; the saddle support means for supporting the saddle assembly; the pedal support means for supporting the pedal crank assembly; and the rear wheel support means for supporting the rear wheel assembly. On the other hand, regulatory-type bicycle frames contain a relatively bulky central tube, which connects with the various support means in a radiant manner via a plurality of legs, respectively. Since regulatory looms (which resemble an octopus) involve a fundamentally different design from traditional lozenge-shaped looms (which are structured like a lattice) the traditional process for manufacturing composite lozenge-shaped looms is not satisfactory, and it is required that a new technique is developed to produce safe and inexpensive regulatory type bicycles from composite materials.

The process described in the present invention comprises the following steps: (a) superposing a plurality of first layers of prepreg on a first mandrel to form the left and right uncured rear branches, each of the first layers of prepreg contains a fibrous material impregnated with a hardenable synthetic resin; (b) remove the left and right uncured posterior branches from the first mandrel and heat the uncured left and right posterior branches in a first mold to form hardened left and right posterior branches; (c) superimposing a plurality of second layers of prepreg on a second mandrel assembly to form the uncured front frame portion, which contains a hollow core tube and a plurality of hollow legs connected thereto, each of the second prepreg layers contains a fibrous material impregnated with a hardenable synthetic resin; (d) removing the uncured front frame portion from the second mandrel assembly; (e) joining the cured left and right posterior branches to the uncured front frame portion with a plurality of third layers of prepreg, overlapping both the cured left and right posterior branches and the uncured front frame portion, each of the third layers of prepreg contains a fibrous material impregnated with a hardenable synthetic resin; (f) heating and hardening the uncured front frame portion within a second mold to form a bicycle frame.

It is preferred that each of the first or second layers of prepreg contain 5 to 30 layers, more preferably 8 to 16 layers, of the fibrous material impregnated with a hardenable resin. An inflatable bladder may be placed within the cavity of the uncured front frame portion before it is placed in the second state to apply pressure on the prepreg layers during curing. Alternatively, a thermally expandable material can be placed in the cavity of the uncured front frame portion. The volume expansion of the thermally expandable material after heating also creates pressure on the prepreg layers during the curing process to improve the strength of the cured product.

One of the advantages of the process developed in the present invention is flexibility; it can be used to produce a variety of bicycle frames such as Y-shaped, T-shaped, V-shaped, Z-shaped front frames, etc. Figures 1 to 14 show only some examples of bicycle frames that can be produced using the process described in the present invention. In all these examples, the bicycle frame 10 comprises a front frame portion 1, and a rear frame portion 2. The numbers 11 and 12 indicate head tube and seat tube, respectively, and the number 13 indicates a tube to five joints (i.e., the pedal support tube), which also provides support means for the pedal. The process described in the present invention is also extremely flexible which allows a wide variety of frame component cuts and sizes to be designed and manufactured to meet any special needs and preferences.

The present invention will now be described more specifically with reference to the following examples. It should be noted that the following descriptions of examples, including the preferred embodiment of this invention, are presented here for purposes of illustration and description, and are not intended to be exhaustive or limit the invention to the precise form described.

As described above, the rear frame portion of the regulatory type frames contains only a lower rear fork or an upper rear fork, but not both. As shown in Figure 14, each rear fork, whether it is an upper fork or a lower fork, contains a left branch 21 and a right branch 22 in a symmetrical relationship to each other. The left and right branches of the rear frame portion are connected to the wheel assembly (not shown) via a pair of hook terminations 26, respectively. The left and right branches are formed by superimposing a plurality of prepreg layers on a mandrel. The mandrel can be made of inexpensive, relatively light and easily separable material such as wood, plastic, rubber, etc. After the mandrel is removed, the uncured branches are placed inside a mold. Figure 15 is a top view of the mold used to construct the rear lower yoke shown in Figure 14. Figures 15A and 15B are cross-sectional views of the mold as shown in Figure 15 along the line 15A-15A, and along the line 15B-15B, respectively. The mold consists of an upper mold member 31 and a lower mold member 32. An inflatable bladder (preferably made of nylon) has been placed within the uncured branches to apply pressure, after the mold has been closed, during the thermal hardening process.

The abutment surfaces and the left and right branches may be provided with a pair of mating (i.e., corresponding) projections and recesses, respectively. In a preferred embodiment of the present invention, the projection (and corresponding recess) had a cross shape (i.e., "+") as shown in Figures 16A and 16B. The thickness (or depth) of the conjugation cross was about 5 to 10 mm, and its width was about 5 to 25 mm. The size of the cross should preferably be as large as the area of the abutting surfaces allows. After the left and right branches hardened, they were glued together using an appropriate adhesive. The protrusion and the mating cavity collectively improved the bond between the abutting surfaces of the two branches. Figure 17 is a top view of the rear upper left branch and rear right branch of the Y-shaped frame as shown in Figure 14 after they are joined with the five-joint tube of the front frame portion. As shown in Figure 17, a 2 mm deep triangular groove was provided at the bottom of the portion of curvature embracing the left and right branches. The triangular groove provided a means to collect excess glue and helped ensure an even distribution of stress.

Figure 18 is a revealed view of the uncured front frame portion, with the cured rear frame portion attached thereto, in accordance with the Y-shaped frame as shown in Figure 14 which has been placed inside a mold 5 Figures 18A-18H show various cross-sectional views. Before being placed inside the mold, the front frame portion 1 was prepared by arranging a head tube 11, a saddle tube 12, and a five-joint tube 13, relative to a mandrel assembly (not shown). A plurality of layers of prepreg (preferably 5 to 30 layers, even better 8 to 16 layers) were arranged above and covered the mandrel assembly and several tubes, 11, 12 and 13, such that those tubes were buried inside them. Thereafter, the mandrel assembly was removed and the uncured front frame portion was placed within the mold 5. The rear frame portion 2 was connected by sleeve to the front frame portion at an appropriate location between the tube. of saddle 12 and the five-joint tube 13. A plurality of layers of prepreg were wrapped around the connection, and an overlapping length or length of at least 4-8 cm was provided in this sleeve connection. It is preferred that the prepreg layers be tapered (and their lengths were about 5 to 10 cm) so as to avoid localized stress concentration. In another preferred embodiment, an appropriate film type adhesive was applied to the sleeve connection to improve the integrity of those of the adhesion. In yet another preferred embodiment, 1-2 layers of specially prepared thermally expandable film of epoxy material were applied by covering the outermost prepreg layers surrounding the five-joint tube and rear fork portion. The thermally expandable films caused external pressure to be applied to the uncured resin opposite to the pressure exerted by the inflatable bladder during the curing step to further enhance the structural integrity of the final product.

Figure 19, which is a revealed view of the curing / pressurizing operation using the mold 5 of Figure 18, shows that an inflatable bladder was placed inside the cavity of the uncured front frame portion 1; the inflatable bladder 41 was connected to an air supply hose 44 entering through the head tube 11. The cured rear frame portion 2 had been received in sleeve mode from the adjacent uncured front frame portion 1 to tube five at junction 13. Air was supplied from the air supply hose 44 during the curing step to apply pressure causing the uncured prepregs to be pushed against the inner wall of the mold 5 to form a frame for composite bicycle. In an alternate embodiment, a thermally expandable material was used to fill the cavity within the uncured front frame portion. As the volume of the thermally expandable material expanded during the thermal curing step, a similar pressure was exerted against the prepregs being cured. Figures 20 and 21 are revealed views of two alternative embodiments, respectively, of the curing / pressurizing operation using the mold of Figure 18. In Figure 20, the inflatable bladder 41 was connected to a flexible tube 44 of supply of air entering through the saddle tube 12. In Figure 21, two inflatable bladders 42 and 43 were used which were connected to two hoses 44 supplying air entering through the head tube 11 and the saddle tube 12, respectively.

A wide variety of prepregs can be used in the present invention to suit specific needs and applications. Design considerations include flexural strength, stiffness, compressive strength, tensile strength, shock absorbency, weight, etc. Typical fibrous materials include fiberglass, carbon fiber, Kevlar fiber, Spectra fiber, etc. Within each type of fibrous materials, there are also grades of low, medium, or high modulus, etc. which can be selected. Some applications may advantageously use a combination of fibers, such as 75/25, 50/50 or 25/75 carbon / glass fibers.

In the method described above, the left and right rear branches 21 and 22 were connected together before they were joined with the uncured front frame portion. In yet another embodiment, the left and right rear branches can be joined separately in sleeve mode with the uncured front frame portion, before the uncured front frame portion is placed in the mold 5.

The process described in the present invention requires only a rear fork, which contained a left branch and a right branch, and both were pre-molded and hardened prior to fabrication of the entire frame. As a consequence, the three molds required in the present invention, that is, the molds 31 and 32 for molding left and right branches, 21 and 22, respectively, and the main mold 5, can be greatly simplified and with greatly reduced bulk. Furthermore, since only a rear fork 2 was involved in the present invention, it can be joined to the front frame portion 1 at essentially any location between the saddle tube 12 and the five-joint tube 13. This provides great flexibility in bicycle frame designs, especially in designing the bicycle frame that strictly follow the best aerodynamic consideration to minimize drag. Additionally, the single rear fork can be placed at an optimal arrangement with minimal interference from the drive chain.

In the process described in the present invention, since the front frame portion was prepared by first arranging the prepreg above a mandrel assembly, then placing the uncured hollow body, together with the saddle tube, head tube and tube of pedal, within a mold in which the prepregs are hardened by heat and pressure, great flexibility can also be achieved in the design of the front frame. Considerations in the front frame design include avoiding or minimizing interference with the drive chain (in conjunction with an optimal rear fork design), and reducing vertical shock to provide ride comfort.

The foregoing description of the preferred embodiments of this invention has been presented for purposes of illustration and description. Obvious modifications or variations are possible in light of the previous teaching. The embodiments have been selected and described to provide the best illustration of the principles of this invention and its practical application to then allow those skilled in the art to use the invention in different embodiments and with different modifications which are suitable for the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the extent to which they are entitled lawfully, legally, and fairly.

Claims (19)

CLAIMS 1. Process for building regulatory-type bicycle frames, wherein said regulatory-type bicycle frame comprises a radiating front frame portion and a rear frame portion, said front frame portion comprises a center tube and a plurality of radiating legs from it, said rear frame portion comprises a rear fork connected to said front frame portion, said rear fork comprises a left rear branch and a right rear branch, said process comprising the following steps: (a) arranging a plurality of first layers of prepreg on a first mandrel to form an uncured left rear branch and an uncured right rear branch, each of said first layers of prepreg containing a fibrous material impregnated with a hardenable synthetic resin; (b) removing said left and right rear uncured branches from said first mandrel and heating said rear left and right uncured branches in a first mold to form rear left and right hardened branches; (c) overlapping a plurality of second prepreg layers to form an uncured front frame portion, which contains a hollow core tube and a plurality of hollow legs connected thereto, each of said second prepreg layers containing a fibrous material impregnated with a hardenable synthetic resin; (d) joining said cured left and right rear branches to said uncured front frame portion with a plurality of third prepreg layers, where said third prepregs overlap either or both of said left and right rear branches cured with said uncured front frame portion, each of said third prepreg layers contains a fibrous material impregnated with a hardenable synthetic resin and (e) heating and hardening said front frame portion within a second mold to form a bicycle frame. 2. A process for constructing regulatory type bicycle frames according to claim 1, wherein said cured left and right rear branches are joined separately to said uncured front frame portion by means of said overlapping third prepregs. A process for building regulatory type bicycle frames according to claim 1, which further comprises the steps which consist of gluing together said hardened left and right rear branches at their respective abutment surfaces to form an integral rear fork, then joining said integral rear fork to said uncured front frame portion with said third overlapping prepregs. 4. Process for constructing regulatory type bicycle frames according to claim 3, which further comprises the step which consists in forming a pair of projections and mating cavities on said abutting surfaces of said left and right rear branches, respectively, in a manner to increase the integrity of said integral rear fork. 5. Process for building regulatory type bicycle frames according to claim 1, wherein said uncured hollow front frame portion is formed by the following steps: (a) superimposing a plurality of second layers of prepreg on a second mandrel assembly to form an uncured front frame portion, which contains a hollow core tube and a plurality of hollow legs connected thereto, each of said second layers of prepreg containing a fibrous material impregnated with a hardenable synthetic resin; (b) removing said uncured front frame portion from said second mandrel assembly to form said uncured hollow front frame portion. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said uncured hollow front frame portion is formed by arranging a plurality of long strips or plates of said second prepreg layers on a plurality of tubes, said tubes being arranged in a radiant manner from said hollow core tube to be formed. 7. A process for manufacturing regulatory type bicycle frames according to claim 6, wherein said tubes are arranged in a "Y", "V", "T", or "7" shape and joined by said overlapping layers of said prepreg. 8. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said uncured left rear branch and said uncured right rear branch are cured by the steps which consist of: (a) inserting an inflatable bladder within each of said uncured branch; (b) blowing air into said inflatable bladder so as to press said uncured branch against an inner wall of said first mold; And (c) applying heat to harden said hardenable synthetic resin. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said uncured left rear branch and said uncured right rear branch are cured through the steps which consist of: (a) inserting a thermally expandable material into each of said uncured branch; And (b) applying heat to harden said hardenable synthetic resin. 10. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said hardened rear fork has a depressed front portion about 2 to 4 cm deep which is sleeve received by said uncured front frame portion so as to forming an outer surface joined at level. 11. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said plurality of legs connect said center tube with steering support means, saddle support means, and pedal support means, respectively, and said rear fork connects said central tube with rear wheel support means. Process for manufacturing regulatory type bicycle frames according to claim 11, wherein: (a) said steering support means is formed by wrapping a head tube with at least a fourth layer of prepreg, said saddle support means is formed by wrapping a saddle tube with at least a fourth layer of prepreg, and said support means pedals are formed by wrapping a pedal tube with at least a fourth layer of prepreg; And (b) said steering support means, said saddle support means, and said pedal support means are joined by said second layers of prepreg. 13. Process for manufacturing regulatory type bicycle frames according to claim 12, wherein said uncured front frame portion is hardened through the steps which consist of: (a) inserting at least one inflatable bladder within said uncured front frame portion; (b) blowing air into said inflatable bladder via a flexible air tube which is connected to an external air supply through said head tube or saddle tube so as to press said uncured branch against an interior wall of said first mold; And (c) applying heat to harden said hardenable synthetic resin. 14. A process for manufacturing regulatory type bicycle frames according to claim 13, wherein two of said inflatable bladders are inserted within said uncured front frame portion, and air is blown into said bladders. inflatable via air hoses which are connected to an external air supply via said head tube and seat tube, respectively. 15. Process for manufacturing regulatory type bicycle frames according to claim 1, wherein said uncured front frame portion is hardened through the steps which consist of: (a) inserting a thermally expandable material into each of said uncured branches; And (b) applying heat to harden said hardenable synthetic resin. 16. A process for manufacturing regulatory type bicycle frames according to claim 1, wherein said left rear branch and said right rear branch are joined by an adhesive layer approximately 0.1-1.0mm thick. 17. Composite regulatory type bicycle frame comprising a radiating front frame portion and a rear frame portion, said front frame portion comprises a central tube and a plurality of legs radiating therefrom, said rear frame portion comprises the rear fork connected to the front frame portion, said rear fork having a left rear branch and a right rear branch; wherein said composite regulatory-type bicycle frame is constituted through a process comprising the following steps: (a) arranging a plurality of first layers of prepreg on a first mandrel to form an uncured left rear branch and an uncured right rear branch, each of said first layers of prepreg containing a fibrous material impregnated with a hardenable synthetic resin; (b) removing said left and right rear uncured branches from said first mandrel and heating said rear left and right uncured branches in a first mold to form rear left and right hardened branches; (c) overlapping a plurality of second prepreg layers to form an uncured front frame portion, which contains a hollow core tube and a plurality of hollow legs connected thereto, each of said second prepreg layers containing a fibrous material impregnated with a hardenable synthetic resin; (d) joining said cured left and right rear branches to said uncured front frame portion with a plurality of third prepreg layers, where said third prepregs overlap either or both of said left and right rear branches cured with said uncured front frame portion, each of said third prepreg layers contains a fibrous material impregnated with a hardenable synthetic resin; And (e) heating and hardening said uncured front frame portion within a second mold to form a bicycle frame. 18. Composite regulatory type bicycle frame according to claim 17, wherein said cured left and right rear branches are joined separately to said uncured front frame portion by means of said overlapping third prepregs. 19. Composite regulatory type bicycle frame according to claim 17, wherein said hardened left and right rear branches are glued together at their respective abutment surfaces to form said integral rear fork before they are joined to said frame portion anterior not hardened.