Patent Publication Number: US-2023136264-A1

Title: Method of manufacturing tubular hollow profile vehicle frame parts

Description:
FIELD OF THE INVENTION 
     Generally, the present invention relates to manufacturing vehicle frame structures thereof. Particularly, however not exclusively, the present invention pertains to a method for manufacturing tubular hollow profile vehicle frames and a frame structure product thereof. 
     BACKGROUND 
     Contemporary bicycle frames made from metal alloy, such as steel or aluminum alloy, are commonly manufactured with the help of CNC-machining. For producing tubular structures for a bicycle frame part, such as the front frame or rear frame may be manufactured from aluminum by pre-forming two parts of the frame part into tubular shape, which are then joined together to form a single tubular hollow profile frame part. Commonly, the parts are joined together at the seams by welding. However, welding requires high accuracy, be it manual or robotic, in addition to which such a welded frame must in many cases be aligned, heat treated and post-machined to be suitable for high quality bicycle frame applications. 
     Alternatively, an aluminum bicycle frame may be manufactured by bonding two pre-formed tubular shape frame parts together at their respective faying surfaces with a bonding adhesive. This technique however has the disadvantage that two parts must be pressed together while curing the bonding adhesive. The pressing of the parts may be achieved by a mechanical jig, screws or such clamping means, which may be difficult to set with accuracy, such that the frame parts are joined together accurately with even pressure along the seam. In many cases, such bonding may be inferior in strength since there may be imperfections at the bonding of the seam. Additionally, the same imperfections as well as glue squeezed from the seam may need to be machined after bonding of the frame parts. Moreover, some of the used manufacturing techniques are limited in view of the frame shapes that may be manufactured. 
     Since high performance vehicle frames aim for optimal structures in terms of strength to weight ratio the wall thickness of the frame profile is kept as thin as possible. This sets a further difficulty for connecting two pre-formed frame parts to each other and then machining the frame part consisting of the two parts. 
     SUMMARY OF THE INVENTION 
     The objective of the embodiments of the present invention is to at least alleviate one or more of the aforementioned drawbacks evident in the prior art techniques particularly in the context of bicycle frame manufacturing methods. The objective is generally achieved with a method in accordance with the present disclosure. 
     A technical advantage of the present invention is that it allows for manufacturing tubular vehicle frame structures with hollow and thin-walled profiles, which can be machined to substantially high engineering tolerances. Further, the method is highly usable for creating vehicle frame structures wherein stiffness to weight ratio is an important design aspect, and sufficient engineering tolerances as well as structural robustness need to be met. The products manufactured with the method may include especially bicycle frames but also other light and medium size human-powered and motor-powered vehicle frames. 
     Even further, the present method may be used to manufacture smooth-surface vehicle frames with continuous curvilinear profiles. This is enabled by the specific rabbet-type joint formed at and between the billet parts whereat the billet parts are bonded. 
     In accordance with one aspect of the present invention a method for manufacturing a hollow vehicle frame part comprising
         removing material from a first side of a first billet to create a first inner shape of a target vehicle frame and wherein material is removed from the first side of said first billet such that at least one substantially flat faying surface is left on said first side of said first billet adjacent to the first inner shape,   removing material from a first side of a second billet to create a second inner shape of a target vehicle frame and wherein material is removed from the first side of said second billet such that at least one substantially flat faying surface is left on said first side of said second billet adjacent to the second inner shape,   bonding the first billet and the second billet together at the faying surfaces on first sides of the first and second billets such that the first and second inner shapes face each other,   characterized in that after bonding, removing material by machining from the second side of the first billet and from the second side of the second billet to create target outer shape of the vehicle frame part, and further in that before bonding forming additional faying surfaces adjacent and at an angle to the faying surfaces on the first side of the first billet and second billet, which faying surfaces together form a rabbet-type joint at which the first billet and second billet are bonded.       

     According to an exemplary embodiment of the present invention material is removed from the first sides of the first billet and second billet such that an amount of material remains in the second sides of the first billet and second billet before bonding and removing material from the second sides of the first billet and second billet. 
     According to an exemplary embodiment of the present invention material is removed from the first sides of the first billet and second billet such that an amount of material remains outside of the faying surfaces on the first sides of the first billet and second billet before bonding and removing material from the second sides of the first billet and second billet. 
     According to an exemplary embodiment of the present invention material is removed from the first and second sides of the first and second billets such that the target shape of the vehicle frame part has a wall thickness of 0.1-8 mm. 
     According to an exemplary embodiment of the present invention material is removed from the first and second sides of the first and second billets such that the target shape of the vehicle frame part has a wall thickness of approximately 1 millimeter. 
     According to an exemplary embodiment of the present invention at or after bonding the combined block of the first billet and the second billet is attached to a jig for machining any of the second sides of the first and second billets. 
     According to an exemplary embodiment of the present invention the first and/or second billet are pre-formed by cold-forging, casting or printing to form a first and/or second inner shape, after which the first and/or second inner shape is machined. 
     According to an exemplary embodiment of the present invention the first side of the first and/or second billet are shot-peened. 
     According to an exemplary embodiment of the present invention the first and/or second inner shape surface is treated by coating, anodizing, coloring or passivating. 
     According to an exemplary embodiment of the present invention mechanical fastening means through the first billet and second billet at non-machined parts of the first billet and second billet are used for setting and holding the first billet and second billet in relation to each other for bonding. 
     According to an exemplary embodiment of the present invention mechanical fastening means are used to fasten the billets to a jig for machining 
     According to an exemplary embodiment of the present invention xyz-coordinate zero points and their relation to one or more sides of a billet and inner shape geometry are determined for each inner shape at or after forming each inner shape. 
     According to an exemplary embodiment of the present invention in the method the billets are aluminum alloy billets. 
     According to further exemplary embodiments of the present invention in the method may comprise more billets than the first and second billets, which may be regarded as third, fourth etc. billets. The method then comprises removing material from a first side of the third, fourth, or such billet, which first side is substantially flat, to create a third, fourth etc. inner shape of a target vehicle frame and wherein material is removed from the first side of said third, fourth etc. billet such that at least one faying surface is left on said first side of said third, fourth etc. billet adjacent to the third, fourth etc. inner shape. 
     In accordance with one aspect of the present invention the use of method for manufacturing a bicycle frame part. 
     In accordance with one aspect of the present invention a bicycle frame part manufactured by the method. 
     The method may be used to manufacture various tubular hollow profile vehicle parts, such as bicycle front frames and rear frames. However, a person skilled in the art will be able to appreciate that the method may be used to manufacture various other vehicle frame parts, which are not explicitly disclosed but arise in various different applications. 
     As briefly reviewed hereinbefore, the utility of the different aspects of the present invention arises from a plurality of issues depending on each particular embodiment. 
     The expression “a number of” may herein refer to any positive integer starting from one (1). The expression “a plurality of” may refer to any positive integer starting from two (2), respectively. 
     The term “exemplary” refers herein to an example or example-like feature, not the sole or only preferable option. 
     Different embodiments of the present invention are also disclosed in the attached dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some exemplary embodiments of the present invention are reviewed more closely with reference to the attached drawings, wherein 
         FIG.  1    illustrates the machined first billet in accordance with an embodiment of the present invention, 
         FIG.  2    illustrates the machined second billet in accordance with an embodiment of the present invention, 
         FIGS.  3   a  and  3   b    illustrate axonometric and partial cutaway views respectively of the first and second billets combined together in accordance with an embodiment of the present invention, 
         FIG.  4    illustrates the bonded first and second billet wherein the second side of the first billet has been machined in accordance with an embodiment of the present invention, 
         FIG.  5    illustrates the bonded first and second billet connected to a jig after the second side of the first billet has been machined in accordance with an embodiment of the present invention, 
         FIG.  6    illustrates a vehicle frame part product connected to a jig after the second side of the second billet has been machined in accordance with an embodiment of the present invention, 
         FIG.  7    illustrates a cutaway drawing of a bicycle frame manufactured by the method in accordance with the present invention, 
         FIG.  8    illustrates a cutaway drawing of a bicycle frame part product manufactured by the method in accordance with the present invention, and 
         FIG.  9    depicts a flow diagram illustrating an embodiment of the method in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG.  1    illustrates the first billet ( 102   a ) after machining of the first inner shape ( 106   a ). For the present method, the plate-like first billet ( 102   a ) is first pre-formed by machining a first side ( 104   a ) to create the hollow inner shape of a first elongated hollow frame half constituting a first inner shape ( 106   a ). The shape may be determined in view of the target vehicle frame part profile and dimensions. The inner shape is machined to the first billet ( 102   a ) such that one or more surfaces are left as faying surfaces whereat the first billet ( 102   a ) may be bonded with a second billet ( 102   b ). In this embodiment, a rabbet-type joint rim ( 110   a ), comprising two faying surfaces at an angle to each other, is formed to the outer rim of the first inner shape ( 106   a ) which may be mated with a matching shoulder shape. The first side ( 104   a ) surface may be pre-formed or machined substantially flat or to such other shape that it may be set surface to surface with the first side ( 104   b ) of the second billet ( 102   b ) at least at the faying surfaces whereat the first billet ( 102   a ) and second billet ( 102   b ) are bonded. Boring holes ( 112 ) (only one numbered as an example) of such mechanical fastening means may be formed through the first billet ( 102   a ) at the peripheries of the billet, i.e. at the areas that don&#39;t coincide or situate too close to the first inner shape ( 106   a ) at which boring holes ( 112 ) the first billet ( 102   a ) may be attached to a jig ( 114 ) for machining. 
       FIG.  2    illustrates a machined second billet ( 102   b ). For the present method, the plate-like second billet ( 102   b ) is first pre-formed by machining a first side ( 104   b ) to create the hollow inner shape of a second elongated hollow frame half constituting a second inner shape ( 106   a ). The shape may be determined in view of the target vehicle frame part profile and dimensions, and in view of the dimensions of the inner shape and/or faying surfaces of the first billet ( 102   a ). The inner shape is machined to the second billet ( 102   b ) such that one or more surfaces are left as faying surfaces whereat the second billet ( 102   b ) may be bonded with the first billet ( 102   a ). In this embodiment, a rabbet-type joint shoulder ( 110   b ), comprising two faying surfaces at an angle to each other, is formed to the edges of the second inner shape ( 106   b ) which may be mated with a matching rabbet-type joint rim ( 110   a ) of the first inner shape ( 106   a ). The first side ( 104   b ) surface may be pre-formed or machined substantially flat or to such other shape that it may be set surface to surface with the first side ( 104   a ) of the first billet ( 102   a ) at least at the faying surfaces whereat the first billet ( 102   a ) and second billet ( 102   b ) are bonded. Boring holes ( 112 ) may be formed through the second billet ( 102   b ) at the peripheries of the billet, i.e. at the areas that don&#39;t coincide or situate too close to the second inner shape ( 106   b ) at which boring holes ( 112 ) the second billet ( 102   b ) may be attached to a jig ( 114 ) for machining The boring holes ( 112 ) of both the first billet ( 102   a ) and second billet ( 102   b ) may be formed such that holes ( 112 ) coincide when the inner shapes ( 106   a ,  106   b ) of the billets ( 102   a ,  102   b ) are set to face each other. 
     The first billet ( 102   a ) and second billet ( 102   b ) comprise a material that may be machined comprising for example metal or metal alloy. Some feasible examples include aluminum alloys 6061-T6, 7005-T6 and 7075-T6. The billets ( 102   a ,  102   b ) may be plate-like, cuboid, cylindrical shape, or some other shaped block of solid material of any sufficient shape, thickness, dimensions and surface shapes. The billets ( 102   a ,  102   b ) may also be parts that are printed with optimal pre-formation. The faying surfaces are preferably machined or they may be otherwise pre-formed as a rabbet-type joint ( 110   ab ) defined by the first inner shape ( 106   a ) and the second inner shape ( 106   b ) set against each other and optionally additionally a number of surfaces on first side ( 104   a ,  104   b ) on either billet ( 102   a ,  102   b ). 
     Pre-forming may be used to treat the billets ( 102   a ,  102   b ) before machining For example, cold-forging and casting may be used to shape and treat the billets ( 102   a ,  102   b ), which may be used to reduce the amount of machining needed or to treat the material. Also, techniques may be used to treat the first side ( 104   a ,  104   b ) surfaces and the inner shape surfaces after removal of material. Such techniques include shot-peening, coloring, anodization, passivation and coating, such as Aluminum Oxide Coating, and the like corrosion resistance treatment techniques. Such treatment techniques may be very harsh since the outer surface of the target frame part hasn&#39;t yet been formed. This additionally means that inner shape surfaces may be treated independently and from the frame part outer surfaces. 
     A CNC (computer numerical control) machining device is preferably used for the machining operations but also other such machining techniques may be used as feasible in view of e.g. engineering tolerance requirements. However, also other machining means, such as manual machining means may be possible in limitations of the required accuracy and tolerances of the target design requirements. Machining is preferably used to remove substance material from the billets ( 102   a ,  102   b ) as well as any residue from the bonding seams, such as removing any bonding material extruding from the profile or outer wall of the target part that is being manufactured. 
       FIGS.  3   a  and  3   b    illustrate axonometric and partial cutaway aspects respectively of the first billet ( 102   a ) and second billet ( 102   b ) combined together. The first billet ( 102   a ) and second billet ( 102   b ) are joined together by bonding the first billet ( 102   a ) and the second billet ( 102   b ) together at the faying surfaces on first sides ( 104   a ,  104   b ) of the first billet ( 102   a ) and second billet ( 102   b ) such that the first inner shape ( 106   a ) and second inner shape ( 106   b ) face each other. Preferably an amount of material remains in the second sides ( 108   a ,  108   b ) of the first billet ( 102   a ) and second billet ( 102   b ) before bonding and removing material from the second sides ( 108   a ,  108   b ) of the first billet ( 102   a ) and second billet ( 102   b ) as illustrated. Preferably also an amount of material remains outside of the faying surfaces on the first sides ( 104   a ,  104   b ) of the first billet ( 102   a ) and second billet ( 102   b ) before bonding and removing material from the second sides ( 108   a ,  108   b ) of the first billet ( 102   a ) and second billet ( 102   b ) as illustrated. Because the billets ( 102   a ,  102   b ) have more material than the final target vehicle frame part shape the billets ( 102   a ,  102   b ) may be compressed together from various preferred points and the amount of material helps to stiffen the structure while bonding. This also helps to reduce movement and vibration of the structure while machined from the seams and the second sides ( 108   a ,  108   b ) of the first billet ( 102   a ) and second billet ( 102   b ). 
     As illustrated and meant herein throughout, the second sides ( 108   a ,  108   b ) of the billets comprise the all one or more outer sides of the billets, which sides are not the first sides ( 104   a ,  104   b ) at which the billets are bonded together. Because billets may have different geometries the second sides ( 108   a ,  108   b ) are to be understood as to cover all the outer surfaces of the billets, which are machined to create target outer shape of the vehicle frame part. 
     The billets ( 102   a ,  102   b ) may be compressed against each other by boring holes ( 112 ) through the billets ( 102   a ,  102   b ) at the peripheries of the billets ( 102   a ,  102   b ), i.e. at the areas that don&#39;t coincide or situate too close to the inner shapes of the billets ( 102   a ,  102   b ). Via the holes ( 112 ) the billets ( 102   a ,  102   b ) may be both compressed against each other and fastened to a jig ( 114 ) for machining Alternatively or additionally, clamping means may be used. The mechanical fastening means and/or clamping means may be used to compress and hold the billets ( 102   a ,  102   b ) against each other while the bonding adhesive sets and cures. 
     For bonding, two-component adhesives, heat-activated adhesives and the like may be used. The adhesive may be applied to and along the corner of the shoulder ( 110   b ) of the rabbet-type joint ( 110   ab ) such that when the other billet is pressed against the shoulder ( 110   b ) of the other billet the adhesive is squeezed and spread along the different-facing surfaces of the shoulder ( 110   b ) and hence adhesive spreads into the two different surfaces of the shoulder ( 110   b ) and its opposing surfaces of the rim ( 110   a ) of the rabbet-type joint ( 110   ab ). Alternatively or additionally, the adhesive may be applied directly on all faying surfaces. 
       FIG.  4    illustrates the bonded first and second billet ( 102   b ) wherein the second side ( 108   a ) of the first billet ( 102   a ) has been machined. The structure formed by the bonded billets ( 102   a ,  102   b ) may be attached to a jig ( 114 ) and the second side ( 108   a ) of the first billet ( 102   a ) is machined to create one target outer shape of the vehicle frame part. As illustrated, the boring holes ( 112 ) surrounded by a wall remaining billet material housing the mechanical fastening means may be left protruding. 
       FIGS.  5    illustrates the bonded first and second billet ( 102   b ) connected to a jig ( 114 ) after the second side ( 108   a ) of the first billet ( 102   a ) has been machined. Herein the second side ( 108   b ) of the second billet ( 102   b ) is machined to create a second target outer shape and essentially finalize the target shape of the vehicle frame part. Logos and other details such as connection points for links, bearings, load-bearing structures, derailleurs, seat posts, forks, brakes, hubs, bottle holders, and the like, as well as attachment means, such as screws and the like. 
       FIG.  6    illustrates a vehicle frame part ( 100 ) product connected to a jig ( 114 ) after the second side ( 108   b ) of the second billet ( 102   b ) has been machined. The final product may be machined and finished to remove any protruding adhesives or billet material. As depicted, the vehicle frame part ( 100 ) attained with the method includes a hollow profile, which may be also tubular and have a substantially thin wall thickness, which wall thickness may be also variable along the frame part ( 100 ). The various shapes may include linear and curvilinear shapes via the longitudinal and vertical directions of the frame part ( 100 ) to attain various different kinds of shapes and surface textures and structures, such as protrusions, recesses, through holes, means for attaching components, and other such mechanical details. 
       FIG.  7    illustrates a cutaway drawing of a bicycle frame manufactured by the method. The bicycle frame shown here is the front frame of a bicycle. The wall-thickness may vary, even along the profile, and some examples of suitable wall-thickness comprise thicknesses from the range of 0.1-8 mm. One preferable wall-thickness is approximately 1 mm. However, the wall-thickness may be chosen in view of billet material, frame part geometry and frame part purpose. 
       FIG.  8    illustrates a cutaway drawing of a bicycle frame part product manufactured by the method. The rabbet-type joint ( 110   ab ) whereat the billets ( 102   a ,  102   b ) are joined comprises a shoulder ( 110   b ) at the second billet ( 102   b ) to which the rim ( 110   a ) of the first billet ( 102   a ) is set for bonding. The frame part may also comprise a portion with a higher wall-thickness at the location of the rabbet-type joint ( 110   ab ), which portion may protrude from the overall frame part profile as illustrated. However, due to the bonding connection being a rabbet-type joint ( 110   ab ) the outer profile may be machined to a smooth and continuous curvilinear profile allowing for a plurality of different frame part shapes. The rabbet-type joint ( 110   ab ) provides a wide surface for the bonding adhesives and due to the shape also strength into various directions of the bonding connection. 
       FIG.  9    depicts a flow diagram illustrating an embodiment of the method ( 200 ) in accordance with the present invention. 
     At  202 , referred to as the start-up billets may be fastened to a jig for machining 
     At  204 , the material is removed from a first side of a first billet to create a first inner shape of a target vehicle frame and wherein material is removed from the first side of said first billet such that at least one faying surface is left on said first side of said first billet adjacent to the first inner shape. Also, a first geometry for a rabbet-type joint is formed to or adjacent to the first inner shape. The first side may be machined or otherwise pre-formed to be substantially flat for being able to set another substantially flat surface against it. As step  205 , pre-forming or post-forming of the first inner shape and/or other parts of the first side may be carried out before, at or after creating the first inner shape. Also, the billet may be determined and assigned xyz-coordinate zero points and their relation to one or more sides of the billet in view of the formed inner shape geometry of the billet. 
     At  206 , the material is removed from a first side of a second billet to create a second inner shape of a target vehicle frame and wherein material is removed from the first side of said second billet such that at least one faying surface is left on said first side of said second billet adjacent to the second inner shape. Also, a second geometry for a rabbet-type joint is formed to or adjacent to the first inner shape that fits with the first geometry. The first side may be machined or otherwise pre-formed to be substantially flat for being able to set another substantially flat surface against it. As step  207 , pre-forming or post-forming of the second inner shape and/or other parts of the first side may be carried out before, at or after creating the second inner shape. Also, the billet may be determined and assigned xyz-coordinate zero points and their relation to one or more sides of the billet in view of the formed inner shape geometry of the billet. 
     At  208 , a first geometry for a rabbet-type joint is formed to or adjacent to the first inner shape and a second geometry for a rabbet-type joint is formed to or adjacent to the second inner shape that fits with the first geometry. The rabbet-type geometry of the joint and its faying surfaces is preferably done while forming the first inner shape and the second inner shape. The first geometry may be for example a rim with a 90 degree angle corner, which may be mated with a shoulder with a rim or recess of 90 degree angle corner. The two main faying surfaces of the rabbet-type joint are defined by a faying surface at the first side of a billet substantially flat and adjacent to an inner shape and an additional faying surface at, in or protruding from the second inner shape. These faying surfaces are adjacent and at an angle to each other. The shape and geometry, e.g. the area, of the faying surfaces as well as the angle thereof may vary and be chosen in view of design requirements. 
     At  210 , the first billet and the second billet are placed together at the faying surfaces on first sides of the first and second billets such that the first and second inner shapes face each other. The first and second billets are bonded together such as that their first and second geometries together form a rabbet-type joint wherein at least one surface is used as a faying surface for bonding. Alternatively, both surfaces of the shoulder of the rabbet-type joint may be used as faying surfaces with the corresponding opposing faying surfaces of the rim of the other billet. Because the second sides of the billets haven&#39;t yet been machined the billets still have a substantially high amount of mass and thickness when compared to the final target shape of the frame part, which means that high amount of pressure may be used to compress the billets against each other for bonding. This means that more pressure may be used to compress the billets to each other than would be possible for a two ready-machined frame halves. Also, setting and keeping the frame parts in place and in preferred relation to each other is possible because of the sufficiently high pressure that may be used and because of the rabbet-type joint geometry at the seams of the billets. 
     At  212 , material is removed by machining from the second side of the first billet and from the second side of the second billet to create target outer shape of the vehicle frame part. 
     A person skilled in the art will be able to appreciate that some steps may be carried out coincidentally or at different orders. Further, although only two billets are depicted the method allows for use of a further number of billets. One or more of third, fourth, fifth, etc., billets removing material from a first side of the third, fourth, fifth or such billet, which first side is substantially flat, to create third, fourth, fifth or such, inner shape of a target vehicle frame and wherein material is removed from the first side of said third, fourth, fifth or such, billet such that at least one faying surface is left on said first side of said third, fourth, fifth or such, billet adjacent to the third, fourth, fifth or such, inner shape. 
     The scope of the invention is determined by the attached claims together with the equivalents thereof The skilled persons will again appreciate the fact that the disclosed embodiments were constructed for illustrative purposes only, and the innovative fulcrum reviewed herein will cover further embodiments, embodiment combinations, variations and equivalents that better suit each particular use case of the invention.