A crank structure based on vacuum electron beam welding and a bicycle

Abstract

A crank structure based on vacuum electron beam welding comprises a crank body, a hollow groove formed on the crank body, and a cover plate lapped on the hollow groove and covering the opening of the hollow groove completely; wherein the cover plate and the hollow groove are welded along the circumference of the opening by vacuum electron beam welding to form a closed loop weld to seal the hollow groove. By adopting the vacuum electron beam welding process, the crank body and the cover plate are welded in a vacuum environment to form a dense weld structure and a smooth appearance, which can effectively avoid the defects such as pores, welding bumps and uneven surface caused by traditional laser welding; meanwhile, the use of filler adhesive is not needed, reducing the processing procedures and cost, and the continuous integrated surface is formed on the outer surface after welding, which not only improves the product appearance, but also improves the welding strength and structural reliability.

Description

Technical Field

[0001] This application relates to the field of bicycle manufacturing technology, and in particular to a crank structure and bicycle based on vacuum electron beam welding. Background Technology

[0002] With the increasing demands for product precision and appearance quality in the manufacturing industry, welding technology is widely used in the manufacture of high-strength, lightweight structural components, such as bicycle cranks. Welding not only affects the strength and durability of the connection but also directly relates to the product's appearance quality and manufacturing cost. However, existing welding processes still have shortcomings, especially in terms of weld smoothness and structural stability, making it difficult to simultaneously achieve both performance and aesthetics.

[0003] Laser welding is widely used for joining thin-walled metal parts due to its advantages such as a small heat-affected zone and high welding speed. However, because of its concentrated heat input and limited energy control precision, problems such as porosity, incomplete fusion, and molten pool spatter can easily occur during the welding process, resulting in a rough and uneven weld surface, affecting the product's appearance and weld strength. For sporting goods with high appearance requirements, such as bicycle cranks, defects such as unsightly welds, weld beads, and dents are even more pronounced, affecting the overall quality.

[0004] To improve the appearance of welds, some manufacturers employ filler bonding technology, which involves filling the weld joint with adhesive or metal powder to smooth the surface and achieve a better aesthetic result. While this method enhances aesthetics to some extent, its bonding and curing process is complex, increasing both process and material costs, and potentially affecting the strength and durability of the welded area. Especially under high load conditions, it is difficult for the bonding material to maintain consistent strength and stability with the metal weld, easily leading to structural fatigue or failure.

[0005] In summary, existing technologies still struggle to balance weld appearance and structural strength. Laser welding suffers from inconsistent weld quality, while filler bonding methods introduce complexity and increased costs. Therefore, a new welding technology is needed that can ensure weld strength and structural reliability while also achieving a smooth appearance and high production efficiency. Utility Model Content

[0006] The purpose of this application is to provide a crank structure based on vacuum electron beam welding to solve the problems of unsightly welds, numerous welding defects, and complex and costly filling and gluing processes in existing laser welding, so as to achieve a crank structure with smooth and dense welds, high strength, and beautiful appearance.

[0007] According to one aspect of this application, a crank structure and bicycle based on vacuum electron beam welding are provided, comprising: Crank body; A hollow groove is formed on the crank body; A cover plate is attached to the hollow tank and completely covers the opening of the hollow tank. The cover plate and the hollow tank are welded together along the periphery of the opening by vacuum electron beam welding to form a closed-loop weld, thereby sealing the hollow tank.

[0008] More preferably, the hollow groove is recessed inward from the outer surface of the crank body, and the opening is located on the periphery formed by the intersection of the hollow groove and the outer surface of the crank body; The inward concavity of the hollow groove is referred to as the first direction, and the projection of the cover plate in the first direction completely coincides with the projection of the opening of the hollow groove in the first direction.

[0009] More preferably, when the cover completely covers the opening, the upper surface of the cover is on the same plane as the outer surface of the crank body; Furthermore, the upper surface of the cover plate and the outer surface of the crank body are both planes or curved surfaces.

[0010] More preferably, the closed-loop weld is located between the upper surface and the outer surface, and any two points on the closed-loop weld are in the same plane in space; Before the cover plate completely covers the opening and before it is welded by the vacuum electron beam welding, there is a gap between the upper surface and the outer surface, and the width of the gap is between 0.1 mm and 0.2 mm.

[0011] More preferably, the width of the gap is between 0.12 mm and 0.15 mm.

[0012] More preferably, one end of the crank body is provided with a first mounting part for connecting to the bicycle, and the other end is provided with a second mounting part for connecting to the pedal; The closed-loop weld is located between the first mounting part and the second mounting part, and the closed-loop weld is coplanar in space.

[0013] More preferably, the hollow groove body has an inwardly extending stepped surface around the opening, and the stepped surface extends continuously along the circumference of the opening to form a closed structure. When the cover plate overlaps the stepped surface, the cover plate is adjacent to the hollow groove.

[0014] More preferably, both the crank body and the cover plate are made of metal.

[0015] More preferably, the cover plate and the outer surface of the crank body form a continuous outer surface after vacuum electron beam welding.

[0016] More preferably, it includes the aforementioned crank structure based on vacuum electron beam welding.

[0017] This application has the following beneficial effects: By employing vacuum electron beam welding technology, the crank body and cover plate are welded together in a vacuum environment, resulting in a dense weld structure and a smooth appearance. This effectively avoids defects such as porosity, weld beads, and surface unevenness caused by traditional laser welding. At the same time, there is no need to use filler adhesives, reducing processing steps and costs. The welded outer surface forms a continuous, integrated shape, which not only improves the product's aesthetics but also enhances the welding strength and structural reliability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the crank structure described in one embodiment of this application; Figure 2 This is an exploded view of the crank structure described in one embodiment of this application; Figure 3 This is a schematic diagram of the hollow groove structure of the crank structure according to one embodiment of this application; Figure 4 This is a schematic diagram of the crank structure before welding according to one embodiment of this application; Explanation of reference numerals: 100, crank structure; 10, crank body; 110, first mounting part; 120, second mounting part; 130, outer surface of crank body; 140, outer surface; 20, hollow groove; 210, opening of hollow groove; 230, stepped surface; 30, cover plate; 310, upper surface of cover plate; 40, closed-loop weld; 410, gap; F, first direction. Detailed Implementation

[0020] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0021] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Please refer to Figure 1 - Figure 4 One embodiment of this application provides a crank structure 100 based on vacuum electron beam welding, including a crank body 10, a hollow groove 20, and a cover plate 30.

[0024] The crank body 10 is an integral metal structure, with a first mounting portion 110 at one end for connection to the bicycle bottom bracket, and a second mounting portion 120 at the other end for mounting the pedals. A hollow groove 20 is formed on the crank body 10, recessed inward from the outer surface 130 of the crank body, to reduce overall weight while maintaining structural strength. The opening 210 of the hollow groove 20 is located on the outer surface 130 of the crank body and extends continuously along the periphery of the groove to form a closed profile.

[0025] The cover plate 30 is disposed above the hollow groove 20 of the crank body 10, and the shape of the cover plate 30 matches the opening 210 of the hollow groove 20. When the cover plate 30 overlaps the hollow groove 20, its projection in the concave direction (i.e., the first direction F) of the hollow groove completely coincides with the projection of the opening of the hollow groove, and can completely cover the opening 210.

[0026] The cover plate 30 and the outer surface 130 of the crank body 10 are welded together along the periphery of the opening 210 using a vacuum electron beam welding process. During welding, a high-energy electron beam is used to heat the joint between the cover plate 30 and the hollow tank 20 within the hollow cavity, causing the metal materials of both to partially melt and form a weld. This weld is then continuously applied along the circumference of the opening 210, ultimately forming a closed-loop weld 40. This closed-loop weld 40 reliably connects the cover plate 30 and the hollow tank 20, thereby achieving complete closure of the hollow tank 20.

[0027] After welding, the weld between the cover plate 30 and the crank body 10 forms a smooth transition, and the outer surface 130 of the crank body 10 is continuous and consistent. The weld has high strength and good airtightness, and there are no defects such as weld protrusions, porosity, and weld slag commonly found in traditional welding. The vacuum electron beam welding process has low heat input and low welding deformation, which can effectively ensure the dimensional accuracy and overall appearance quality of the crank structure.

[0028] Furthermore, the hollow groove 20 is formed by recessing inward from the outer surface 130 of the crank body 10. The hollow groove 20 extends along the recess direction F of the crank body 10, and the groove depth direction is denoted as the first direction F. The outer edge of the hollow groove 20 intersects with the outer surface 130 of the crank body 10 to form an opening 210, and the opening 210 extends continuously along the periphery of the hollow groove 20 to form a closed ring structure. Through this recessed structure design, a partially hollow area is formed inside the crank body, thereby achieving weight reduction while ensuring structural strength.

[0029] A cover plate 30 is positioned above the hollow groove 20 of the crank body 10, and its shape matches the shape of the opening 210. When the cover plate 30 overlaps the hollow groove 20, its projection in the first direction F completely coincides with the projection of the hollow groove opening 210 in the first direction F, ensuring that the cover plate 30 can completely cover the entire opening 210. This structure allows the welding area to be evenly distributed around the periphery of the groove, which is beneficial for the concentration of electron beam welding energy and the continuous formation of the weld.

[0030] Through the above structural design, the recess depth of the hollow groove 20 and the fitting position of the cover plate 30 can be precisely controlled, which not only ensures the assembly positioning accuracy, but also provides a stable weld path for subsequent vacuum electron beam welding, thereby improving welding consistency and appearance flatness.

[0031] Furthermore, when the cover plate 30 overlaps and completely covers the opening 210 of the hollow groove 20, the upper surface 310 of the cover plate 30 and the outer surface 130 of the crank body 10 are on the same plane. By precisely matching the thickness of the cover plate 30 and the recess depth of the hollow groove 20, the two are assembled to form a continuous and flat outer surface 140 in the direction perpendicular to the first direction F.

[0032] In this embodiment, the upper surface 310 of the cover plate 30 and the outer surface 130 of the crank body 10 can be a planar structure or a smooth curved surface extending along the outline of the crank body 10. This coplanar design makes the transition between the cover plate 30 and the crank body 10 natural and the appearance integrated. After welding, a smooth appearance can be obtained without extensive machining or grinding.

[0033] This structure not only improves the aesthetics of the crank's outer surface, but also avoids stress concentration caused by weld protrusions or depressions, thereby improving the fatigue strength and service life of the welded parts and further ensuring the stability of the crank under riding loads.

[0034] Furthermore, the cover plate 30 and the hollow groove body 20 are welded together along the periphery of the opening 210 using vacuum electron beam welding to form a closed-loop weld 40. This closed-loop weld 40 is located between the upper surface 310 of the cover plate 30 and the outer surface 130 of the crank body 10, and its weld path is continuously distributed in a ring shape in space. In order to ensure the flatness of the structure after welding, any two points on the closed-loop weld 40 are on the same plane in space, making the weld as a whole coplanar, avoiding local height differences or weld undulations, thereby improving the welding quality and appearance consistency.

[0035] Before welding, the cover plate 30 completely covers the opening 210 of the hollow tank 20, with a pre-set gap 410 between them. The width of the gap 410 ranges from 0.1 mm to 0.2 mm. By controlling this gap size, the electron beam can obtain an appropriate energy transfer space during the welding process, ensuring stable weld penetration, full fusion of weld metal, and preventing burn-through or incomplete welding. As the vacuum electron beam moves along the periphery, the electron beam energy is concentrated within the gap, forming a dense and continuous weld structure.

[0036] This structural design achieves effective distribution of welding energy and consistency of weld morphology through gap control, which ensures welding strength and reduces welding deformation, so that the cover plate 30 and the outer surface 130 of the crank body 10 form a smooth transition after welding, improving the overall assembly accuracy and aesthetics.

[0037] Furthermore, the width of the gap 410 between the cover plate 30 and the hollow groove 20 is preferably set to be between 0.12 mm and 0.15 mm. By controlling the gap within this range, the vacuum electron beam can achieve a more stable energy focusing effect during the welding process, ensuring the uniformity of weld penetration and weld width.

[0038] When the gap is less than 0.12 mm, the electron beam energy cannot fully penetrate the joint interface, which can easily lead to poor weld fusion or localized incomplete welds. When the gap is greater than 0.15 mm, problems such as an excessively large molten pool, uneven weld formation, or burn-through may occur. Maintaining the gap between 0.12 mm and 0.15 mm ensures that the electron beam energy can fully act on the welding area while effectively controlling the amount of welding deformation, resulting in a dense, continuous weld structure and a smooth appearance.

[0039] Furthermore, one end of the crank body 10 is provided with a first mounting portion 110 for connecting with the bicycle bottom bracket, and the other end is provided with a second mounting portion 120 for mounting the pedals. The crank body 10 forms a main body section between the first mounting portion 110 and the second mounting portion 120, and the main body section is provided with a welded structure of a hollow groove 20 and a cover plate 30.

[0040] The closed-loop weld 40 is distributed along the periphery of the opening of the hollow groove 20, and is located in the middle area between the first mounting part 110 and the second mounting part 120. By arranging the closed-loop weld 40 in the middle of the crank body, the weld can be kept away from the stress concentration area after welding, avoiding additional stress concentration at the bottom bracket or pedal connection, thereby improving the mechanical strength and fatigue life of the entire crank.

[0041] Furthermore, the closed-loop weld 40 is spatially coplanar, meaning that any two points along the weld path lie on the same plane. This coplanar design ensures the consistency of the welding path, resulting in uniform circumferential distribution of welding deformation and stable weld penetration and width, thus achieving a smooth weld morphology and continuous appearance. After welding, the cover plate 30 transitions naturally with the outer surface of the crank body 10, and the overall outer surface 140 is smooth and continuous, satisfying both aesthetic requirements and improving structural rigidity and welding reliability.

[0042] Furthermore, the periphery of the opening 210 of the hollow groove 20 is provided with an inwardly extending stepped surface 230. This stepped surface 230 extends continuously along the circumference of the opening 210, forming a closed ring structure to define the assembly position of the cover plate 30. The stepped surface 230 smoothly transitions with the inner wall of the hollow groove 20, and its width and depth are designed to match the thickness of the cover plate 30 to ensure accurate positioning and stable support during assembly.

[0043] When the cover plate 30 overlaps the stepped surface 230, the lower surface of the cover plate 30 is adjacent to the stepped surface 230, achieving a tight fit between them. This structure allows the cover plate 30 to be reliably positioned before welding, preventing misalignment or warping during assembly and facilitating alignment and energy concentration during vacuum electron beam welding. Simultaneously, the continuous closed structure of the stepped surface 230 ensures the integrity of the weld path, enabling electron beam welding to continuously form a closed-loop weld 40 along the periphery of the opening 210, thereby improving welding consistency and structural strength.

[0044] This stepped surface structure not only improves the fitting accuracy between the cover plate and the hollow groove, but also effectively controls the weld position, ensuring a flat and continuous outer surface 140 after welding, and improving the weld appearance and the manufacturing consistency of the whole part.

[0045] Furthermore, both the crank body 10 and the cover plate 30 are made of metal. Preferably, both are made of aluminum alloy, formed by forging or precision milling and then vacuum electron beam welding. Aluminum alloy has low density, high specific strength and good weldability, which can achieve structural lightweighting while ensuring overall strength.

[0046] Of course, this application is not limited to using aluminum alloy materials. In other embodiments, the crank body 10 and the cover plate 30 can also be made of titanium alloy, stainless steel, or high-strength steel, depending on the application requirements. These metals all have excellent mechanical properties and weldability, and can achieve dense weld connections through vacuum electron beam welding, thereby ensuring the reliability and service life of the crank structure.

[0047] The crank body and cover plate, made of metal materials, form an integral continuous metal structure after welding. This not only results in high weld strength and good airtightness, but also a smooth and uniform outer surface after welding, which is beneficial for subsequent surface treatment and coating.

[0048] Furthermore, after the cover plate 30 and the crank body 10 are welded together by vacuum electron beam welding along the periphery of the opening 210 of the hollow groove 20, the outer surfaces 130 of the cover plate 30 and the crank body 10 form a continuous outer surface 140 in the welding area. After welding, the surface of the closed-loop weld 40 smoothly transitions with the surrounding base material, and the overall appearance has no obvious protrusions or depressions. The weld and the outer surface 130 of the crank body are consistent in both visual appearance and structure.

[0049] Because vacuum electron beam welding has low heat input and concentrated energy, the deformation of the weld area is minimal, and a smooth surface can be obtained without extensive machining or polishing after welding. This continuous surface not only improves the product's appearance and aesthetics but also achieves continuous stress transfer between the crank body and the cover plate, avoiding stress concentration in the weld area and significantly improving the crank's fatigue strength and service life.

[0050] Furthermore, a bicycle is provided, which includes the crank structure 100 based on vacuum electron beam welding as described in any of the foregoing embodiments. The crank structure 100 is fixedly connected to the bicycle's bottom bracket assembly via a first mounting portion 110 and rotatably connected to the pedal assembly via a second mounting portion 120, thus forming the power input end of the bicycle's transmission system.

[0051] During riding, the rider applies driving force to the crank structure 100 through the pedals. The crank body 10, through the closed-loop weld 40, forms an integral structure that stably transmits the pedaling force to the bottom bracket, thereby driving the sprocket and rear wheel to rotate, thus propelling the entire vehicle. Because the crank structure 100 is manufactured using vacuum electron beam welding technology, its welds are dense, high-strength, and of stable quality, maintaining good structural stability and fatigue performance under long-term high-frequency pedaling conditions.

[0052] In addition, the crank structure 100 has a continuous and flat outer surface 140, which is consistent with the overall appearance of the vehicle. This not only improves the visual quality of the vehicle but also reduces air resistance and improves the streamlined performance during riding.

[0053] Through the above structural design, the crank structure described in this embodiment achieves lightweighting while ensuring excellent welding strength and smooth appearance, making it suitable for the transmission system of high-performance bicycles.

[0054] By employing vacuum electron beam welding, the crank body 10 and the cover plate 30 are welded together in a vacuum environment, resulting in a dense and smooth weld seam 40. This effectively avoids defects such as porosity, weld beads, and uneven surface caused by traditional laser welding. At the same time, there is no need to use filler adhesives, reducing processing steps and costs. After welding, the outer surface 130 forms a continuous integrated outer surface 140, which not only improves the product's aesthetics but also enhances the welding strength and structural reliability.

[0055] The embodiments described above are merely illustrative of several implementations of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A crank structure based on vacuum electron beam welding, characterized in that, include: Crank body; A hollow groove is formed on the crank body; A cover plate is attached to the hollow tank and completely covers the opening of the hollow tank. The cover plate and the hollow tank are welded together along the periphery of the opening by vacuum electron beam welding to form a closed-loop weld, thereby sealing the hollow tank.

2. The crank structure based on vacuum electron beam welding according to claim 1, characterized in that, The hollow groove is recessed inward from the outer surface of the crank body, and the opening is located on the periphery formed by the intersection of the hollow groove and the outer surface of the crank body; The inward concavity of the hollow groove is referred to as the first direction, and the projection of the cover plate in the first direction completely coincides with the projection of the opening of the hollow groove in the first direction.

3. The crank structure based on vacuum electron beam welding according to claim 2, characterized in that, When the cover completely covers the opening, the upper surface of the cover is on the same plane as the outer surface of the crank body; Furthermore, the upper surface of the cover plate and the outer surface of the crank body are both planes or curved surfaces.

4. The crank structure based on vacuum electron beam welding according to claim 3, characterized in that, The closed-loop weld is located between the upper surface and the outer surface, and any two points on the closed-loop weld are in the same plane in space; Before the cover completely covers the opening and before it is welded by the vacuum electron beam welding, there is a gap between the upper surface and the outer surface, and the width of the gap is between 0.1 mm and 0.2 mm.

5. A crank structure based on vacuum electron beam welding according to claim 4, characterized in that, The width of the gap is between 0.12 mm and 0.15 mm.

6. A crank structure based on vacuum electron beam welding according to claim 5, characterized in that, One end of the crank body is provided with a first mounting part for connecting to the bicycle, and the other end is provided with a second mounting part for connecting to the pedal; The closed-loop weld is located between the first mounting part and the second mounting part, and the closed-loop weld is coplanar in space.

7. A crank structure based on vacuum electron beam welding according to claim 6, characterized in that, The hollow trough has an inwardly extending stepped surface around the opening, which extends continuously along the circumference of the opening to form a closed structure. When the cover plate overlaps the stepped surface, the cover plate is adjacent to the hollow groove.

8. A crank structure based on vacuum electron beam welding according to claim 7, characterized in that, Both the crank body and the cover plate are made of metal.

9. A crank structure based on vacuum electron beam welding according to claim 8, characterized in that, The cover plate and the outer surface of the crank body form a continuous outer surface after vacuum electron beam welding.

10. A bicycle, characterized in that, Includes a crank structure based on vacuum electron beam welding as described in any one of claims 1 to 9.

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