An inflatable welding fixture

Abstract

The utility model discloses a kind of inflatable welding positioning tool, including tool spindle (1), its left end and right end are equipped with left end inflatable positioning assembly and right end inflatable positioning assembly respectively. Left, right end inflatable positioning assembly includes center shaft (3,7), expansion sleeve (4,8) and adjusting mechanism (5,9) respectively. Center shaft is coaxially fixed in the end of tool spindle (1), expansion sleeve is coaxially set on the outside of center shaft, adjusting mechanism is threadedly connected with center shaft and abuts on expansion sleeve inner end face, and between expansion sleeve and adjusting mechanism is equipped with taper surface cooperation. When rotating adjusting mechanism, move along axial direction and drive expansion sleeve to slide along taper surface, drive expansion sleeve radial elastic expansion, to accurately adjust expansion sleeve outer diameter to adapt different inner diameter of the component to be welded, eliminate assembly gap, realize no-gap fit and forced coaxial straightening. The tool both ends can be independently adjusted, coaxial degree is high, versatility is strong, adjusting is continuous accurate, effectively improve welding quality and production efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of welding technology, specifically relating to an expandable welding positioning fixture. Background Technology

[0002] This utility model belongs to the field of machining and welding tooling technology, and is mainly applied to the welding and assembly process of shaft and cylindrical components to ensure the overall dimensional accuracy of the components after welding. Currently, the requirements for coaxiality in component welding are increasingly stringent in the machinery manufacturing field, as this accuracy directly affects the assembly performance, operational stability, and service life of the product.

[0003] Most existing welding fixtures adopt a fixed structure design, with the outer diameters of their two locating ends being fixed and non-adjustable. Specifically, the fixture mainly consists of a fixture body and fixed locating heads located at both ends. In use, the two parts to be welded are respectively fitted onto the locating heads at both ends, so that the inner hole of the workpiece fits against the outer circular surface of the locating head, and then welding is performed. The outer diameter of the locating head in this type of fixture is a preset value, which can only accommodate the inner hole of workpieces with a single outer diameter specification, and assembly gaps are easily generated between the locating head and the inner hole of the workpiece.

[0004] The above-mentioned fixed welding fixture has the following technical problems: Low assembly accuracy: Gaps are easily generated between the fixed positioning heads at both ends and the inner hole of the workpiece, making it impossible to accurately align the workpiece coaxially. This results in a large deviation in the coaxiality of the components after welding, affecting the subsequent performance of the product.

[0005] Poor versatility: The outer diameter of the positioning head is fixed, and one tooling can only be used for one type of workpiece. Multiple tooling options are required when producing products of different specifications, increasing manufacturing costs and reducing production efficiency.

[0006] Poor assembly fit: The fixed structure cannot be finely adjusted according to the actual size of the workpiece's inner hole. After locking, the workpiece is prone to slight skewing, and welding deformation is easily caused by positioning deviation during the welding process.

[0007] Therefore, the industry urgently needs a welding fixture that is flexible, adjustable, and has high positioning accuracy. Utility Model Content

[0008] This invention aims to overcome the shortcomings of existing fixed welding fixtures in terms of assembly accuracy, versatility, and fit, and provides a highly coaxial, independently adjustable, and adaptable expandable welding positioning fixture. Its core lies in setting independently driven expandable positioning components at both ends of the fixture's main shaft. Utilizing the tapered fit between the threaded adjustment mechanism and the expansion sleeve, the axial thrust is converted into a uniform radial expansion force, allowing for continuous and quantitative adjustment of the expansion sleeve's outer diameter. This eliminates the assembly gap with the inner hole of the component to be welded, achieving forced coaxial alignment of the components at both ends, and providing reliable technical equipment support for high-precision welding assembly.

[0009] To address the aforementioned problems, the first aspect of this utility model provides an expandable welding positioning fixture, characterized in that it comprises: a fixture spindle 1; a left-end expandable positioning component and a right-end expandable positioning component, respectively located at the left and right ends of the fixture spindle 1; the left-end expandable positioning component and the right-end expandable positioning component each comprise: central shafts 3 and 7, expansion sleeves 4 and 8, and adjusting mechanisms 5 and 9; wherein the central shafts 3 and 7 are coaxially fixedly connected to the ends of the fixture spindle 1, the expansion sleeves 4 and 8 are coaxially sleeved on the outer sides of the central shafts 3 and 7, the adjusting mechanisms 5 and 9 are threadedly connected to the central shafts 3 and 7 and abut against the inner end faces of the expansion sleeves 4 and 8, and the expansion sleeves 4 and 8 are provided with a tapered surface fit with the adjusting mechanisms 5 and 9; the adjusting mechanisms 5 and 9 are used to drive the expansion sleeves 4 and 8 to undergo radial elastic expansion to adjust the outer diameter of the corresponding expandable positioning component, so that the fixture can adapt to welding parts with different inner diameter specifications.

[0010] This application provides an expandable welding positioning fixture, the core of which lies in the provision of a left-end expandable positioning component and a right-end expandable positioning component at the left and right ends of the fixture spindle 1, respectively. Each component independently includes a central shaft 3, 7, an expansion sleeve 4, 8, and an adjusting mechanism 5, 9. The central shaft 3, 7 are coaxially fixedly connected to the end of the fixture spindle 1. The expansion sleeves 4, 8 are coaxially sleeved on the outside of the central shaft 3, 7. The adjusting mechanisms 5, 9 are threadedly connected to the central shaft 3, 7 and abut against the inner end faces of the expansion sleeves 4, 8, with a tapered surface fit between the expansion sleeves and the adjusting mechanisms. When the adjusting mechanism is rotated, it moves axially and drives the expansion sleeves to slide along the tapered surface, thereby converting the axial thrust into a uniform radial expansion force, causing the expansion sleeves to undergo radial elastic expansion and increase their outer diameter. Reverse rotation causes the expansion sleeves to elastically contract. Through the connection and coordination of the above components, the tooling can independently adjust the outer diameter of the expansion sleeves at both ends, eliminate the assembly gap with the inner hole of the part to be welded, realize the forced coaxial alignment of the two end components, and adapt to the parts to be welded with different inner diameter specifications, providing reliable positioning for high-precision welding assembly.

[0011] Furthermore, the left and right ends of the tooling spindle 1 are integrally formed with positioning disks 2 and 6, respectively. The positioning disks 2 and 6 have axially protruding cylindrical bosses. The ends of the central shafts 3 and 7 are provided with grooves that cooperate with the cylindrical bosses. The central shafts 3 and 7 are fixedly connected to the corresponding positioning disks 2 and 6 by bolts, and the cylindrical bosses cooperate with the grooves to achieve radial positioning.

[0012] Furthermore, the left-end expandable positioning component and the right-end expandable positioning component have the same conical surface and cone angle and the same axial travel of the adjustment mechanism; the base outer diameter of the central shaft 3 of the left-end expandable positioning component is smaller than the base outer diameter of the central shaft 7 of the right-end expandable positioning component, so that the outer diameter adjustment range of the left-end expandable positioning component is 218.6mm to 238.6mm, and the outer diameter adjustment range of the right-end expandable positioning component is 241.6mm to 261.6mm.

[0013] Furthermore, the outer diameter adjustment range of both the left-end expandable positioning component and the right-end expandable positioning component is 0mm to 20mm.

[0014] Furthermore, the expansion sleeves 4 and 8 are provided with a number of elastic grooves, which are straight grooves and evenly distributed along the circumferential direction to achieve radial elastic expansion.

[0015] Furthermore, the expansion sleeves 4 and 8 are made of wear-resistant alloy material.

[0016] Furthermore, the tooling spindle 1 is also provided with scale markings, which are used to cooperate with the adjustment mechanisms 5 and 9 to achieve quantitative adjustment of the outer diameter.

[0017] The above-mentioned technical solution of this utility model has the following beneficial technical effects: 1. Significantly improves welding coaxiality accuracy: Because the expandable positioning components on the left and right ends are independently set, and the axial thrust is converted into radial expansion force through a conical fit between the expansion sleeve and the adjustment mechanism, the assembly gap with the workpiece's inner hole is eliminated, achieving forced coaxial alignment of the parts to be welded. Actual measurements show that the coaxiality deviation after welding with traditional tooling is ≥1mm, while this new tooling can control the deviation to ≤0.3mm, improving accuracy by over 70%.

[0018] 2. Significantly improves tooling versatility and production efficiency: Because the adjustment mechanisms at both ends can be operated independently to control the expansion amount of the corresponding expansion sleeves, one tooling can adapt to multiple workpieces of different specifications with an outer diameter deviation within 20mm, eliminating the need for tooling changes. Production time is reduced by approximately 30%, significantly lowering tooling investment costs and changeover time.

[0019] 3. Effectively improves the yield rate of welded products: Because the expansion sleeve and the inner hole of the workpiece achieve a tight, gapless fit through radial expansion, and both ends can be independently and precisely adjusted, welding deformation and misalignment are avoided. Traditional tooling achieves a yield rate of approximately 80% for welded products; this new tooling can increase the yield rate to over 99%, significantly reducing rework costs and ensuring product quality stability.

[0020] 4. Achieve continuous and quantitative adjustment of outer diameter: By cooperating with the conical surface through the threaded adjustment mechanism, the outer diameter of the expansion sleeve can be continuously changed by rotating the adjustment mechanism, and the axial movement distance is linearly related to the radial expansion amount. Operators can accurately control the expansion amount as needed, avoiding errors caused by operation based on experience.

[0021] 5. Reliable structure and wide applicability: Based on the mature elastic expansion sleeve and thread adjustment principle, it integrates innovation, resulting in a compact structure and simple operation. It is not only suitable for welding and positioning of shaft and cylindrical components, but its design concept can also be extended to other mechanical assembly scenarios that require radial clamping or positioning.

[0022] In summary, the technical solution of this utility model, through the coordinated design of an independently expandable positioning structure at both ends, a conical thrust conversion mechanism, and an independent adjustment mechanism, eliminates assembly gaps, forcibly corrects coaxiality at both ends, and expands the outer diameter adjustment range. It comprehensively solves the key problems of large coaxiality deviation, poor versatility, and insufficient fit of existing fixed welding fixtures, and provides a high-precision, high-efficiency, and highly adaptable welding positioning fixture solution. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of an expandable welding positioning fixture according to an embodiment of this utility model.

[0024] Figure label: 1: Tooling spindle; 2: Left end positioning plate; 3: Left end central shaft; 4: Left end expansion sleeve; 5: Left end adjustment mechanism; 6: Right end positioning plate; 7: Right end central shaft; 8: Right end expansion sleeve; 9: Right end adjustment mechanism. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model.

[0026] To address the technical problems of low coaxiality accuracy, poor versatility, and insufficient fit in existing fixed welding fixtures, this invention proposes an expandable welding positioning fixture. Independently driven expandable positioning components are installed at both ends of the fixture's main shaft. Each component includes a central shaft, an expansion sleeve, and an adjustment mechanism, with a tapered surface fit between the expansion sleeve and the adjustment mechanism. During fixture operation, rotating the adjustment mechanism moves it axially along the central shaft thread. The tapered surface converts the axial thrust into a radial expansion force, driving the expansion sleeve to undergo uniform elastic deformation. This continuously adjusts the outer diameter of the expansion sleeve, eliminating the assembly gap with the inner hole of the part to be welded, and achieving forced coaxial alignment of the two ends. This solution, through independent adjustment at both ends, tapered thrust conversion, and elastic expansion technology, allows a single fixture to adapt to workpieces with different inner diameters, improving welding coaxiality accuracy by over 70%, increasing the finished product qualification rate from 80% to 99%, and significantly reducing fixture investment and production time, providing efficient and reliable technical equipment for high-precision welding assembly.

[0027] The following is combined Figure 1 The expandable welding positioning fixture provided by this utility model will be described.

[0028] Figure 1 This is a cross-sectional view of an expandable welding positioning fixture according to an embodiment of this utility model.

[0029] like Figure 1 As shown, the expandable welding positioning fixture of this utility model includes a fixture spindle 1. A left-end expandable positioning assembly and a right-end expandable positioning assembly are located at the left and right ends of the fixture spindle 1, respectively. The left-end expandable positioning assembly includes: a left-end central shaft 3, a left-end expansion sleeve 4, and a left-end adjustment mechanism 5; the right-end expandable positioning assembly includes: a right-end central shaft 7, a right-end expansion sleeve 8, and a right-end adjustment mechanism 9. The left-end central shaft 3 is coaxially fixedly connected to the left end of the tooling spindle 1, and the right-end central shaft 7 is coaxially fixedly connected to the right end of the tooling spindle 1. The left-end expansion sleeve 4 is coaxially sleeved on the outside of the left-end central shaft 3, and the right-end expansion sleeve 8 is coaxially sleeved on the outside of the right-end central shaft 7. The left-end adjusting mechanism 5 is threadedly connected to the left-end central shaft 3 and abuts against the inner end face of the left-end expansion sleeve 4, and the right-end adjusting mechanism 9 is threadedly connected to the right-end central shaft 7 and abuts against the inner end face of the right-end expansion sleeve 8. A tapered surface fit is provided between the left-end expansion sleeve 4 and the left-end adjusting mechanism 5, and between the right-end expansion sleeve 8 and the right-end adjusting mechanism 9. The left-end adjusting mechanism 5 drives the left-end expansion sleeve 4 to undergo radial elastic expansion to adjust the outer diameter of the left-end expandable positioning component; the right-end adjusting mechanism 9 drives the right-end expansion sleeve 8 to undergo radial elastic expansion to adjust the outer diameter of the right-end expandable positioning component; thus enabling the tooling to adapt to welding parts with different inner diameter specifications.

[0030] In some preferred embodiments, a left-end positioning plate 2 is integrally formed at the left end of the tooling spindle 1, and a right-end positioning plate 6 is integrally formed at the right end of the tooling spindle 1. The left-end positioning plate 2 has an axially protruding cylindrical boss, and the right-end positioning plate 6 also has an axially protruding cylindrical boss. The end of the left-end central shaft 3 is provided with a groove that mates with the cylindrical boss of the left-end positioning plate 2, and the end of the right-end central shaft 7 is provided with a groove that mates with the cylindrical boss of the right-end positioning plate 6. The left-end central shaft 3 is fixedly connected to the left-end positioning plate 2 by bolts, and the right-end central shaft 7 is fixedly connected to the right-end positioning plate 6 by bolts, and the cylindrical boss and the groove mate to achieve radial positioning. Specifically, the left-end positioning plate 2 is a cylindrical shoulder that protrudes axially from the left end of the tooling spindle 1, is coaxial with the tooling spindle 1, and its outer diameter is larger than the outer diameter of the tooling spindle 1 and smaller than the outer diameter of the fixed section of the left-end central shaft 3. The outer end face of the left positioning plate 2 is a precision-machined flat surface used to mate with the fixed section end face of the left central shaft 3. The central area of ​​the outer end face of the left positioning plate 2 is a cylindrical outer circumferential surface, which mates with the groove (positioning countersunk hole) at the end of the left central shaft 3, using a small clearance fit or transition fit. When the left central shaft 3 is installed, the outer cylindrical surface of the left positioning plate 2 is embedded in the groove of the left central shaft 3, achieving radial positioning and ensuring the coaxiality of the left central shaft 3 and the tooling spindle 1. The outer end face of the left positioning plate 2 also has multiple threaded holes or bolt through holes evenly distributed along the circumference, used to insert bolts to fix the left central shaft 3 to the left positioning plate 2. The cylindrical surface of the left positioning plate 2 and the outer circular surface of the tooling spindle 1 are transitioned by a fillet to eliminate stress concentration. The right-end positioning disk 6 has the same structure as the left end, symmetrically positioned at the right end of the tooling spindle 1. Its outer cylindrical surface is embedded in the groove of the right-end central shaft 7, achieving coaxiality between the right-end central shaft 7 and the tooling spindle 1. This concave-convex fit structure is simple and reliable, laying the foundation for subsequent high coaxiality welding. In other embodiments, the left-end central shaft 3 and the right-end central shaft 7 can also be directly fixed to the corresponding ends of the tooling spindle 1 by welding or integral molding, as long as coaxiality and no relative movement are ensured.

[0031] Both the left-end central shaft 3 and the right-end central shaft 7 are stepped shaft structures, divided into a fixed section (base), a mating section, and a threaded section along the axial direction from the inside out. Taking the left end as an example, the fixed section of the left-end central shaft 3 is located at the innermost side and is a shaft directly fixedly connected to the left-end positioning plate 2; its outer diameter is the same as the outer diameter of the base. The mating section of the left-end central shaft 3 is located in the middle and is a precision-machined outer cylindrical surface; its outer diameter is smaller than that of the fixed section, providing a radial support reference for the left-end expansion sleeve 4. The mating method between the mating section and the left-end expansion sleeve 4 can be selected according to design requirements, such as leaving a clearance, a transition fit, or a small interference fit. Due to the high cylindricity accuracy of the mating section, the uniformity of the left-end expansion sleeve 4 during radial expansion is ensured, thus helping to achieve a high-precision indicator of coaxiality deviation of the welded component ≤0.3mm. The threaded section of the left-end central shaft 3 is located at the outermost end and is threaded (internal or external) for threaded connection with the left-end adjusting mechanism 5. The length and pitch of the threaded section determine the axial travel range of the left-end adjusting mechanism 5, enabling the rotational motion of the left-end adjusting mechanism 5 to be converted into precise axial movement, thus providing a basis for continuous and quantitative adjustment of the outer diameter of the left-end expansion sleeve 4. The structure of the right-end central shaft 7 is exactly the same as that of the left end, but its fixed section outer diameter (base outer diameter) is different from that of the left end. The specific values ​​are described below.

[0032] To achieve different outer diameter adjustment ranges at the left and right ends, this fixture adopts the following structure: the left-end expandable positioning component and the right-end expandable positioning component have the same conical surface and cone angle and the same axial travel of the adjustment mechanism; the base outer diameter of the left-end central shaft 3 of the left-end expandable positioning component is smaller than the base outer diameter of the right-end central shaft 7 of the right-end expandable positioning component, so that the outer diameter adjustment range of the left-end expandable positioning component is 218.6mm to 238.6mm, and the outer diameter adjustment range of the right-end expandable positioning component is 241.6mm to 261.6mm. The principle is as follows: the outer diameter of the fixed section (base) of the left-end central shaft 3 is 218.6 mm, and the outer diameter of the fixed section (base) of the right-end central shaft 7 is 241.6 mm; the cone angle between the left-end expansion sleeve 4 and the left-end adjusting mechanism 5 is the same as the cone angle between the right-end expansion sleeve 8 and the right-end adjusting mechanism 9 (e.g., 15°); the axial travel of the left-end adjusting mechanism 5 (i.e., the length of the threaded section of the left-end central shaft 3) is the same as the axial travel of the right-end adjusting mechanism 9. Therefore, when the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9 rotate the same number of turns, their axial movement distances are the same, and the radial expansion amount obtained through the cone surface conversion is the same, both being 0–20 mm. Thus, the minimum outer diameter of the left-end expansion sleeve 4 is 218.6 mm, and the maximum outer diameter is 218.6 + 20 = 238.6 mm; the minimum outer diameter of the right-end expansion sleeve 8 is 241.6 mm, and the maximum outer diameter is 241.6 + 20 = 261.6 mm. In this way, the outer diameter adjustment range of both the left and right expandable positioning components is 0mm to 20mm. One tooling can simultaneously adapt to two different inner diameter specifications of the parts to be welded without the need to change tooling, which significantly improves versatility and can shorten production time by about 20%.

[0033] Several elastic grooves are respectively provided on the left end expansion sleeve 4 and the right end expansion sleeve 8. These elastic grooves are straight grooves and are evenly distributed along the circumference to achieve radial elastic expansion.

[0034] In some embodiments, the left end expansion sleeve 4 is a cylindrical elastic part with a conical surface on its inner side for engaging with the conical surface of the left end adjustment mechanism 5. The elastic grooves on the left end expansion sleeve 4 are straight grooves, evenly distributed along the circumference of the left end expansion sleeve 4 (e.g., the angle between the centerlines of two adjacent elastic grooves is 30° or 45°), giving the left end expansion sleeve 4 a uniform radial elastic deformation capability. The elastic grooves can be formed along the entire axial length of the left end expansion sleeve 4, or only in a certain axial section. When the left end expansion sleeve 4 is subjected to radial expansion force, elastic deformation occurs at the elastic grooves, and the overall outer diameter of the left end expansion sleeve 4 increases uniformly, thereby achieving a gapless fit with the inner hole of the part to be welded. The structure of the right end expansion sleeve 8 is exactly the same as that of the left end expansion sleeve 4, only differing in size to accommodate the right end outer diameter range. This structure effectively eliminates the coaxiality deviation caused by gaps in traditional fixed fixtures, resulting in a coaxiality accuracy improvement of over 70% for the welded parts (traditional fixture deviation ≥1mm, this invention ≤0.3mm). The left-end expansion sleeve 4 is coaxially fitted onto the outside of the mating section and threaded section of the left-end central shaft 3, meaning the left-end expansion sleeve 4 covers both the mating section and threaded section of the left-end central shaft 3. The inner conical surface of the left-end expansion sleeve 4 mates with the conical surface provided on the left-end adjusting mechanism 5. Various mating forms can be used between the inner hole (cylindrical portion) of the left-end expansion sleeve 4 and the outer cylindrical surface of the mating section of the left-end central shaft 3, such as leaving a gap to facilitate installation and expansion. Similarly, the right-end expansion sleeve 8 is coaxially fitted onto the outside of the mating section and threaded section of the right-end central shaft 7. Preferably, the left-end expansion sleeve 4 and the right-end expansion sleeve 8 are made of wear-resistant alloy materials, such as high-manganese steel, cemented carbide, or tool steel, to improve the service life of the tooling, making it suitable for mass production scenarios and reducing tooling maintenance costs.

[0035] In some embodiments, both the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9 are threaded adjusting screws. The left-end adjusting mechanism 5 has a conical surface (the conical surface can be located at the end, middle, or other position of the left-end adjusting mechanism 5 that can mate with the inner conical surface of the left-end expansion sleeve 4). The left-end adjusting mechanism 5 is screwed into the threaded section of the left-end central shaft 3, and its conical surface mates with the inner conical surface of the left-end expansion sleeve 4 to form a conical driving structure. The front end face or stepped surface of the left-end adjusting mechanism 5 abuts against the inner end face of the left-end expansion sleeve 4. This conical mating structure can efficiently convert axial thrust into radial expansion force, and the conversion ratio is determined by the cone angle of the conical surface. The axial movement distance L and the radial expansion amount ΔR satisfy the relationship ΔR = L·tanα, thereby realizing continuous and precise adjustment of the outer diameter of the left-end expansion sleeve 4. The structure of the right-end adjusting mechanism 9 is exactly the same as that of the left end. It is screwed into the threaded section of the right-end central shaft 7 and mates with the inner conical surface of the right-end expansion sleeve 8. Operators can control the rotation number of the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9 separately as needed to independently obtain the required expansion amount at both ends, avoiding errors caused by operation based on experience. When rotating the left-end adjusting mechanism 5, the left-end adjusting mechanism 5 moves axially and drives the left-end expansion sleeve 4 to slide along the conical surface, thereby driving the left-end expansion sleeve 4 to expand radially; the same applies when rotating the right-end adjusting mechanism 9.

[0036] When using this fixture for welding positioning, first reset the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9, so that the left-end expansion sleeve 4 and the right-end expansion sleeve 8 are in the contracted state. Then, fit the left part to be welded onto the left end of the fixture spindle 1, aligning the inner hole of the left part with the left-end expansion sleeve 4; fit the right part to be welded onto the right end of the fixture spindle 1, aligning the inner hole of the right part with the right-end expansion sleeve 8. Rotate the left-end adjusting mechanism 5 (clockwise rotation can be achieved using an Allen wrench, or other tools and directions), and the left-end adjusting mechanism 5 moves axially inward (towards the fixture spindle 1) along the thread direction. Its conical surface abuts against the conical surface of the left-end expansion sleeve 4, forcing the left-end expansion sleeve 4 to slide along the conical surface. The inclined surface of the conical surface converts the axial thrust into a radially outward expansion force, causing elastic deformation at the elastic groove of the left-end expansion sleeve 4. The overall outer diameter of the left-end expansion sleeve 4 increases uniformly, thereby tightly fitting the inner hole of the left part and eliminating assembly gaps. Similarly, rotating the right-end adjusting mechanism 9 causes the right-end expansion sleeve 8 to expand and tightly fit against the inner hole of the right component. Since the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9 can be operated independently, controlling the expansion amount of the left-end expansion sleeve 4 and the right-end expansion sleeve 8 respectively, even if the inner diameters of the workpieces at the left and right ends are different, they can be adjusted to achieve the optimal fit. This ensures uniform force on the components during welding, avoiding welding deformation and misalignment. Actual measurements show that using this fixture increases the welded product qualification rate from approximately 80% with traditional fixtures to over 99%, significantly reducing rework costs. After welding, rotating the left-end adjusting mechanism 5 and the right-end adjusting mechanism 9 in the opposite direction moves the adjusting mechanisms outwards, releasing the thrust on the expansion sleeve. The expansion sleeve then returns to its original shape due to its own elasticity, its outer diameter shrinks, and it disengages from the inner hole of the workpiece, allowing the finished workpiece to be removed.

[0037] To verify the actual effectiveness of this fixture, a comparative experiment was conducted. Using components of the same specifications, welding and positioning were performed using both the original manual process and this fixture. Five components were tested for each method. The evaluation criterion was: coaxiality at both ends after welding ≤ 0.3mm (target value for this fixture). See Table 1 for a comparison of welding positioning experimental data.

[0038] Experimental results show that after using this tooling, the welding time for a single part was reduced from 8.4 hours to 6.2 hours, and the total working time was reduced by 26%. After welding, the product qualification rate of the welded parts with coaxiality ≤0.3mm at both ends increased from 0% to 100%. This experiment fully demonstrates the significant effect of this utility model in improving welding coaxiality, increasing production efficiency, and ensuring product qualification rate.

[0039] In some embodiments, the tooling spindle 1 is also provided with scale markings to cooperate with the left-end adjustment mechanism 5 and the right-end adjustment mechanism 9 to achieve quantitative adjustment of the outer diameter. Specifically, the outer surface of the tooling spindle 1 is engraved with millimeter scale lines (e.g., 0mm to 50mm) along the axial direction, and pointers are fixedly installed on the left-end adjustment mechanism 5 and the right-end adjustment mechanism 9, respectively. When the left-end adjustment mechanism 5 is rotated, its pointer moves relative to the scale line, and the operator can read the axial movement distance of the left end according to the pointer position. Given that the cone angle of the conical surface is α, the axial movement distance L and the radial expansion amount ΔR of the left-end expansion sleeve 4 satisfy the relationship ΔR = L·tanα. The operator calculates the required axial movement distance according to the required left-end expansion amount, rotates the left-end adjustment mechanism 5 to the corresponding scale mark of the pointer, and thus achieves precise and quantitative adjustment of the outer diameter of the left-end expansion sleeve 4. The same applies to the right end. This scale marking further improves the controllability of positioning accuracy.

[0040] In summary, this fixture, through the coordinated design of independent expandable positioning structures at both ends, conical thrust conversion, and independent adjustment mechanisms, eliminates assembly gaps, forces coaxiality correction at both ends, expands the outer diameter adjustment range, and ensures controllable adjustment accuracy. It comprehensively solves the key problems of existing fixed welding fixtures, such as large coaxiality deviation, poor versatility, and insufficient fit, and provides a high-precision, high-efficiency, and highly adaptable welding positioning fixture solution.

[0041] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within its protection scope. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An expandable welding positioning fixture, characterized in that, include: Tooling spindle (1); The left-end expandable positioning component and the right-end expandable positioning component are located at the left end and the right end of the tooling spindle (1), respectively. The left-end expandable positioning component and the right-end expandable positioning component respectively include: a central shaft (3, 7), an expansion sleeve (4, 8) and an adjustment mechanism (5, 9). The central shaft (3, 7) is coaxially fixedly connected to the end of the tooling spindle (1), the expansion sleeve (4, 8) is coaxially sleeved on the outside of the central shaft (3, 7), the adjustment mechanism (5, 9) is threadedly connected to the central shaft (3, 7) and abuts against the inner end face of the expansion sleeve (4, 8), and there is a tapered surface fit between the expansion sleeve (4, 8) and the adjustment mechanism (5, 9); The adjustment mechanism (5, 9) is used to drive the expansion sleeve (4, 8) to undergo radial elastic expansion to adjust the outer diameter of the corresponding expandable positioning component, so that the tooling can be adapted to the welding parts with different inner diameter specifications.

2. The expandable welding positioning fixture according to claim 1, characterized in that, The tooling spindle (1) has a positioning plate (2, 6) integrally formed on its left and right ends respectively. The positioning plate (2, 6) has an axially protruding cylindrical boss. The end of the central shaft (3, 7) is provided with a groove that cooperates with the cylindrical boss. The central shaft (3, 7) is fixedly connected to the corresponding positioning plate (2, 6) by bolts, and the cylindrical boss cooperates with the groove to achieve radial positioning.

3. The expandable welding positioning fixture according to claim 1, characterized in that, The left-end expandable positioning component and the right-end expandable positioning component have the same conical surface and cone angle and the same axial travel of the adjustment mechanism; the base outer diameter of the central shaft (3) of the left-end expandable positioning component is smaller than the base outer diameter of the central shaft (7) of the right-end expandable positioning component, so that the outer diameter adjustment range of the left-end expandable positioning component is 218.6mm to 238.6mm, and the outer diameter adjustment range of the right-end expandable positioning component is 241.6mm to 261.6mm.

4. The expandable welding positioning fixture according to claim 3, characterized in that, The outer diameter adjustment range of both the left-end expandable positioning component and the right-end expandable positioning component is 0mm to 20mm.

5. The expandable welding positioning fixture according to claim 1, characterized in that, The expansion sleeves (4, 8) are provided with a number of elastic grooves. The elastic grooves are straight grooves and are evenly distributed along the circumference to achieve radial elastic expansion.

6. The expandable welding positioning fixture according to claim 1, characterized in that, The expansion sleeves (4, 8) are made of wear-resistant alloy material.

7. The expandable welding positioning fixture according to claim 1, characterized in that, The tooling spindle (1) is also provided with scale markings, which are used to cooperate with the adjustment mechanism (5, 9) to achieve quantitative adjustment of the outer diameter.

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