Threaded pin extraction three-point closing tool based on threaded adjustment and spherical three-claw structure

Abstract

The application relates to a threaded pin extraction three-point closing tool based on threaded adjustment and a spherical three-claw structure, which comprises a positioning sleeve, a connecting rod movably arranged in the positioning sleeve in the axial direction, a screw rod arranged at the bottom of the connecting rod, the bottom end of the screw rod being fixed on an external workbench, a spring arranged on the screw rod, a gasket arranged on the end of the spring close to the positioning sleeve, the top surface of the gasket being attached to the bottom end surface of the positioning sleeve, the bottom surface of the gasket being in abutment with the top end of the spring, a positioning hole arranged at the top end of the connecting rod, a positioning column arranged on the connecting rod, a plurality of spherical three-claws being uniformly distributed on the outer circumferential side of the positioning column in the circumferential direction, one end of each of the spherical three-claws being fixedly connected with a driving mechanism of an external closing machine, the other end being a spherical working end, the spherical working end being directed to a threaded pin extraction closing part of the top end of the positioning column, three-point synchronous extrusion closing being realized, and the application aims at solving the problems of poor positioning precision, low efficiency, insufficient applicability and difficulty in adapting to different specifications of traditional tools.

Description

Technical Field

[0001] This invention belongs to the field of machining tooling technology, and relates to a three-point closing tooling for threaded pins based on thread adjustment and a spherical three-jaw structure. Background Technology

[0002] Threaded rivets, as fasteners combining high locking reliability with convenient single-sided installation, are widely used in aerospace, rail transportation, and high-end equipment manufacturing industries where stringent connection performance requirements exist. Their core function is to use a "three-point closing" process at the ends to deform the edge of the cap inwards, ensuring a tight fit between the threaded thin-walled part and the screw. This achieves anti-loosening, vibration-resistant, and stable clamping effects, while simultaneously improving the tensile strength and fatigue life of the overall structure. In the aerospace field, titanium alloy threaded rivets are particularly crucial. They not only possess shear strength comparable to traditional bolts but also allow for single-sided installation like ordinary blind rivets, making them suitable for scenarios with poor process access and limited installation space. They are core components ensuring connection stability in high shear load areas and improving assembly efficiency. The quality of the "three-point closing" process directly determines whether the locking torque of the threaded rivet meets standards, thus affecting the safety of the entire connection structure.

[0003] In the large-scale production and practical application of threaded rivets, the existing three-point closing process and supporting tooling have revealed many problems that restrict production efficiency and product quality stability. Firstly, there is a lack of versatility. Most tooling is designed only for threaded rivets of specific diameters or interlayer lengths. When processing specifications change, the entire tooling component must be replaced, which not only extends production preparation time but also requires storing multiple sets of tooling of different specifications, resulting in wasted equipment costs and storage space. Secondly, positioning accuracy and parameter controllability are poor. Traditional tooling lacks precise adjustment mechanisms, and key parameters such as closing position and extrusion depth rely heavily on manual experience, making quantitative control difficult. This leads to problems such as closing offset and uneven depth in batch production, and some products have locking torques exceeding the standard range, requiring rework or even scrapping. Furthermore, there is an imbalance between operational complexity and durability. Some high-precision tooling uses complex structures, which are difficult and costly to process. Moreover, after long-term use, parts are prone to wear and tear, resulting in high maintenance costs. On the other hand, low-cost tooling generally suffers from insufficient strength and is easily damaged, making it difficult to adapt to the needs of long-term continuous production. At the same time, the operation process is cumbersome and requires professional personnel to debug for a long time, which cannot meet the high-efficiency processing requirements of modern production lines.

[0004] After searching relevant materials, patent number CN213575028U, patent name is a closing device for "three-point denting" of threaded core-pulling rivets. The device consists of a spring collet assembly, a chuck and a limiting bar. The spring collet assembly includes a spring collet, a perforated bushing and a denting pin. The perforated bushing has circumferentially spaced through holes to embed the denting pin. The clamping force when the collet is closed is adjusted by the threaded engagement between the spring collet and the chuck. The relative position of the part to be closed is controlled by the threaded engagement between the limiting bar and the spring collet. At the same time, different specifications of perforated bushings and denting pins can be replaced to adapt to products of different diameters. Its advantages lie in the use of common components such as 5C standard spring collets and vertical or lathe-type chucks, which simplifies the structural design and significantly reduces processing and procurement costs. It also achieves basic control of clamping force and closing position through thread adjustment, making operation relatively convenient. However, its disadvantages are also quite obvious. Its versatility is limited by the specifications of the spring collets, and its adaptability to products with different sandwich lengths is narrow. Furthermore, it lacks parameter quantitative control methods, and the closing quality depends on manual experience. After long-term use, the fit clearance between the perforated bushing and the dented pin can easily lead to a decrease in accuracy, making it difficult to meet the diverse and high-precision production needs. Summary of the Invention

[0005] This invention provides a three-point closing tooling for threaded pins based on thread adjustment and a spherical three-jaw structure, which solves the problems of poor positioning accuracy, low efficiency, insufficient applicability, and difficulty in adapting to different specifications of threaded pins in the traditional three-point closing process.

[0006] To solve the above problems, the technical solution adopted by the invention is as follows: A three-point closing fixture for threaded pins based on thread adjustment and a spherical three-jaw structure includes a positioning post, a spherical three-jaw jack, a connecting rod, a washer, a positioning sleeve, a screw, and a spring. The screw is the bottom load-bearing component of the fixture, vertically fixed to an external worktable, and supports the spring, washer, and connecting rod. The external thread at the top of the screw engages with the internal thread of the connecting rod. The spring is coaxially sleeved on the outside of the screw. The washer is horizontally fitted to the top of the spring, and the inner hole of the washer is clearance-fitted with the outer wall of the screw. The bottom of the connecting rod has an internal threaded hole, which connects to the top thread of the screw through the internal thread. The bottom end face of the connecting rod is aligned with the upper surface of the washer. The positioning sleeve is coaxially sleeved on the outside of the connecting rod, with the inner wall of the positioning sleeve and the outer wall of the connecting rod having a clearance fit, and the bottom of the positioning sleeve is in contact with the external worktable surface; the bottom of the positioning post is provided with an external thread section, which is connected to the threaded hole at the top of the connecting rod through the external thread, and the upper end of the positioning post is adapted to the diameter of the through hole provided on the rod part of the threaded pin to be closed, for positioning and placing the threaded pin to be closed; multiple spherical three-jaw jacks are provided, evenly distributed in a circle around the axis of the positioning post, one end of the spherical three-jaw jack is connected to the external closing machine drive mechanism, and the other end is the spherical working end, which faces the threaded pin at the top of the positioning post.

[0007] A method for three-point closing of threaded pins using a three-point closing fixture based on thread adjustment and a spherical three-jaw structure includes the following steps: S1: Tooling assembly: Vertically fix the screw to the external worktable, coaxially insert the spring into the screw, and place a washer on the top of the spring; screw the internal threaded hole at the bottom of the connecting rod into the top of the screw until the bottom end face of the connecting rod is in contact with the upper surface of the washer; insert the positioning sleeve from the top of the connecting rod so that the bottom of the positioning sleeve is in contact with the worktable surface; select a spherical three-jaw jack with a suitable spherical radius according to the diameter of the threaded pin to be closed, and install it on the external closing machine drive mechanism, ensuring that the three spherical three-jaw jacks are evenly distributed around the circumference and that the spherical working ends face the axis of the positioning column; S2: Part positioning. Based on the length of the threaded pin interlayer to be closed, rotate the positioning post to adjust its thread engagement depth with the connecting rod. Read the adjustment depth through the scale line of the connecting rod so that the distance between the top of the positioning hole of the positioning post and the working end of the spherical three-jaw jack matches the interlayer length. Place the threaded pin rod to be closed into the positioning hole of the positioning post, ensuring that the top cap of the threaded pin is above the top of the positioning post. S3: Closing operation. Input the preset closing value on the closing machine control panel. The closing value is determined according to the standard locking torque of the threaded pin. Start the closing machine. The motor drives the three spherical three-jaw jacks to move synchronously in the center. The spherical working end applies uniform extrusion force to the edge of the threaded pin top cap to complete the three-point synchronous closing. S4: Reset and part removal. After the end capping is completed, the motor drives the spherical three-jaw centrifugal movement to reset and remove the threaded pin after end capping. If processing parts of the same specification, repeat S2-S3. If changing the specification, repeat S1-S3.

[0008] The principle and advantages of this solution are as follows: Through the synergistic effect of modular structural design and threaded adjustment mechanism, efficient and precise control of the three-point closing of the threaded pin is achieved. The screw, serving as the bottom load-bearing foundation, is vertically fixed to the worktable. A coaxially sleeved spring and a fitted washer provide stable support for the connecting rod above, while the spring's elasticity cushions and offsets localized impact forces generated during the closing process, preventing damage caused by rigid collisions. The connecting rod, through the engagement of its bottom internal thread and the screw's top thread, forms an adjustable vertical support structure. A positioning sleeve, coaxially sleeved on the outside of the connecting rod, not only limits its vertical movement trajectory, preventing deviation under stress, but also further enhances the overall stability of the fixture through its contact with the worktable surface. As the core component for part positioning, the positioning pin's bottom external thread engages with the threaded hole at the top of the connecting rod. The engagement depth can be adjusted by rotation, precisely controlling the distance between the top of the positioning pin and the working end of the spherical three-jaw chuck, thus adapting to threaded pins of different interlayer lengths. Simultaneously, the through hole at the top of the positioning pin matches the diameter of the threaded pin's shank, ensuring the part remains centered during the finishing process and preventing uneven finishing due to positioning misalignment. The spherical three-jaw chucks are evenly distributed circumferentially around the positioning pin's axis. One end connects to the external finishing machine drive mechanism, while the other end, the spherical working end, faces the pin's cap. When the finishing machine starts, the motor drives the three spherical three-jaw chucks to move synchronously towards the center. The spherical working end applies a uniform and symmetrical compressive force to the edge of the cap, causing the cap's edge to deform evenly inward along the circumference, ultimately achieving a three-point finishing effect that meets the locking torque standard. Throughout the process, preset finishing values ​​can be input through the finishing machine control panel, combined with the thread adjustment scale of the positioning pin, to achieve quantitative control of finishing parameters and ensure consistent finishing quality for each part.

[0009] Compared to existing technologies, which rely heavily on manual experience to adjust the closing position and force, leading to issues such as closing offset and uneven depth, this solution utilizes a threaded connection between the positioning pin and the connecting rod with graduated lines. This allows for intuitive reading of the adjustment depth and precise adaptation to different interlayer lengths. For example, when processing rivets of the same diameter with interlayer lengths of 5mm and 8mm, no tooling changes are required. Positioning can be achieved simply by rotating the positioning pin to adjust the thread engagement depth, with positioning errors controlled within ±0.1mm, far lower than the ±0.5mm error range of traditional tooling. By inputting a preset closing value into the closing machine, the spherical three-jaw chuck synchronously compresses the material, avoiding uneven force caused by manual operation. This significantly improves the locking torque qualification rate compared to existing technologies, completely solving the problem of locking torque failing to meet standards in traditional processes. In terms of versatility, existing technologies often design tooling for single-specification pull pins. Changing specifications requires replacing the entire tooling assembly, which is time-consuming and costly. This solution, however, achieves multi-specification adaptability through modular design. It can replace the spherical three-jaw jacks with different radii based on the pull pin diameter. The replacement process only requires disassembling the connection with the closing machine drive mechanism, which improves efficiency compared to traditional tooling replacement. Different interlayer lengths can be adapted through thread adjustment, eliminating the need to stock multiple sets of positioning components and reducing tooling inventory costs. This is especially suitable for multi-variety, small-batch production scenarios. When processing parts of the same specification, only the positioning and closing operations need to be repeated, without the need for re-adjustment. Even when changing specifications, only the steps of replacing the spherical three-jaw jacks and adjusting the thread depth need to be added, significantly reducing production preparation time. In terms of stability and durability, existing technologies either suffer from insufficient strength due to simple structure, making them prone to component deformation after long-term use, or have high maintenance costs due to complex structure. This solution uses high-strength metal components such as screws and positioning sleeves, combined with a spring buffer design, which can withstand the extrusion force during the closing process and reduce component wear.

[0010] Furthermore, the positioning hole at the top of the connecting rod has a stepped structure, comprising a first guide hole and a second guide hole arranged sequentially from top to bottom. The diameter of the first guide hole is larger than that of the second guide hole. The inner wall of the second guide hole is provided with an internal thread for engaging with the external thread of the positioning post. Before the positioning post is threadedly connected to the second guide hole, the first guide hole can quickly radially limit the positioning post, preventing the threads from being difficult to align due to installation deviations, significantly reducing assembly difficulty and improving operational efficiency. At the same time, it prevents tooth profile damage caused by misalignment during thread engagement, extending the service life of the positioning post and the connecting rod. By rotating the positioning post to adjust the thread engagement depth with the second guide hole, the height of the top of the positioning post can be precisely controlled, thereby adapting to threaded pins of different interlayer lengths. Moreover, the thread engagement has self-locking properties, which can stably maintain the position of the positioning post during the closing process, preventing the positioning post from shifting due to the axial force generated by the spherical three-jaw extrusion, and ensuring the consistency of closing during three-point synchronous extrusion.

[0011] Furthermore, a U-shaped groove is provided at the bottom of the positioning sleeve. This U-shaped groove is located on the axis of the positioning sleeve and the connecting rod, and it runs perpendicular to the axis of the positioning sleeve through the bottom of the positioning sleeve. The through-type structure facilitates direct observation of the fit between the boss and the groove, allowing for timely detection of wear or misalignment issues and reducing maintenance difficulty. The U-shaped groove, being located along the axis, ensures its coaxiality with the connecting rod and screw, preventing radial wobbling of the connecting rod during movement due to groove misalignment. This, in turn, ensures the center positioning accuracy of the threaded pin at the top of the positioning post, providing a stable reference for the three-point synchronous extrusion of the spherical three-jaw jack. At the same time, the through-type U-shaped groove forms a natural chip removal and heat dissipation channel. During the finishing process of the threaded pin, it can promptly remove iron filings or impurities, preventing them from accumulating at the bottom of the positioning sleeve and affecting the normal operation of the spring and washer. It can also help dissipate the heat generated by component friction, extending the service life of vulnerable parts such as springs and washer, and avoiding the defects of traditional closed grooves that are prone to chip accumulation and poor heat dissipation.

[0012] Furthermore, a boss is provided at the bottom of the connecting rod. The diameter of the boss is larger than that of the connecting rod. The boss fits with the side wall of the U-shaped groove with a clearance. The design of the boss diameter being larger than that of the connecting rod and fitting with the side wall of the U-shaped groove can form a bidirectional radial limit. The outer circumferential surface of the boss fits against the side wall of the U-shaped groove, which can strictly limit the radial displacement of the connecting rod during axial movement. This avoids the lateral force generated when the spherical three-claw squeezes the pin, which would cause the connecting rod to tilt. This ensures that the center reference of the pin at the top of the positioning post does not shift, providing a key guarantee for the accuracy of the three-point synchronous closing. At the same time, compared with a design without a boss, this structure can disperse the contact stress between the connecting rod and the positioning sleeve, preventing the connecting rod from increasing the fit clearance due to local wear after long-term stress, and extending the service life of the overall structure.

[0013] Furthermore, the gasket has a circular structure, is made of 45# steel, has a thickness of 2-3mm, and its inner diameter is 0.1-0.2mm larger than the outer diameter of the screw. The symmetrical characteristics of the circular structure ensure that the contact area between the gasket and the bottom of the positioning sleeve and the top of the spring is uniform, avoiding the positioning sleeve from being concave or the spring from being deformed due to localized force concentration. As a medium carbon steel, 45# steel has high hardness and resistance to deformation, and can withstand the axial force generated by the long-term compression of the spring, preventing the gasket from undergoing plastic deformation due to excessively soft material or from breaking due to excessively brittle material, thus extending the service life of the gasket. The thickness is designed to avoid both insufficient structural rigidity due to excessive thinness and increased overall tooling volume and compromised fit between components due to excessive thickness; the inner diameter is larger than the outer diameter of the screw. The clearance not only prevents the gasket and screw from getting stuck due to dimensional interference or machining errors, but also ensures that the gasket moves flexibly along the screw axis with the connecting rod to meet the adjustment requirements of different closing depths. It can also compensate for the slight radial offset during tooling operation through the clearance, prevent the gasket from getting stuck due to component assembly deviations, and at the same time avoid radial wobbling of the gasket caused by excessive clearance, ensuring the stability of spring force transmission.

[0014] Furthermore, the second positioning hole is threadedly connected to the connecting part on the positioning post. The detachable and adjustable nature of the threaded connection allows the tooling to easily adapt to threaded pins of different interlayer lengths. By rotating the positioning post, the thread engagement depth between the positioning post and the second positioning hole can be precisely adjusted, thereby changing the height of the top of the positioning post. This eliminates the need to replace the entire positioning component to meet the closing requirements of parts of different sizes, avoiding the cost waste and efficiency loss of frequent part replacements associated with traditional tooling. At the same time, the detachability of the threaded connection also facilitates the individual maintenance or replacement of the positioning post, reducing the overall maintenance cost of the tooling. In addition, the self-locking characteristic of the threaded connection provides a stable positioning reference for the closing process. When the spherical three-jaw chuck applies circumferential compression to the threaded pin, the friction of the threaded engagement surface can effectively prevent the positioning post from shifting axially or radially, ensuring that the pin at the top of the positioning post is always in the preset closing position, avoiding problems such as asymmetrical closing and insufficient locking torque caused by loose positioning.

[0015] Furthermore, the positioning post has an integrally formed annular placement platform in its middle section. The diameter of this platform matches the diameter of the first guide hole of the connecting rod, and the bottom surface of the platform fits against the stepped surface of the first guide hole. This precise fit between the platform diameter and the first guide hole diameter creates a radial rigid constraint. The outer circumferential surface of the annular placement platform fits against the inner wall of the first guide hole, which strictly limits the radial wobble of the positioning post during assembly and closing, ensuring that the axes of the positioning post, connecting rod, and positioning sleeve are completely aligned. This provides a concentric reference for the spherical three-jaw three-point synchronous extrusion, avoiding problems such as asymmetrical pin closing and dimensional deviations caused by positioning post misalignment. Compared to designs without a placement platform, this radial constraint... It can disperse the lateral force on the positioning column, prevent the positioning column from bending and deforming due to long-term stress, and extend its service life; the fit between the bottom surface of the placement platform and the stepped surface of the first guide hole can achieve reliable axial limiting. When the height of the positioning column is adjusted through the threaded connection of the second guide hole, the fit between the bottom surface of the placement platform and the stepped surface can accurately control the maximum insertion depth of the positioning column, avoiding the top of the positioning column from exceeding the preset position due to excessive thread adjustment. At the same time, during the closing process, the fitting surface can withstand the axial reaction force transmitted by the spherical three-jaw chuck, preventing the positioning column from sinking due to force and affecting the closing accuracy; and the one-piece molded structure design eliminates assembly gaps, avoiding the loosening or displacement that may occur with the split placement platform.

[0016] Furthermore, the connection end between the spherical three-jaw jack and the external closing machine drive mechanism is provided with an oblong hole. The oblong hole is set along the length direction of the spherical three-jaw jack. By adjusting the position of the bolt in the oblong hole, the distance between the spherical three-jaw jack and the positioning post can be finely adjusted. The length direction adjustment characteristic of the oblong hole allows the tooling to adapt to threaded pins of different diameters without replacing the spherical three-jaw jack. When dealing with pins with small diameter differences, there is no need to disassemble the drive mechanism to replace the corresponding specification three-jaw jack. Simply by loosening the bolt and moving the spherical three-jaw jack along the oblong hole, the distance between the spherical working end of the three-jaw jack and the positioning post can be adjusted, so that the three-jaw jack can always form a uniform three-point compression on the pin. This avoids efficiency loss and cost waste caused by frequent part replacement and greatly improves the tooling's compatibility with multi-specification parts. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention; Detailed Implementation The reference numerals in the accompanying drawings include: 1. Positioning sleeve; 2. Connecting hole; 3. U-groove; 4. Connecting rod; 5. Washer; 6. Screw; 7. Spring; 8. Boss; 9. Spherical three-jaw jack; 10. Spherical working end; 11. Threaded pull pin with constriction; 12. First guide hole; 13. Second guide hole; 14. Positioning pin; 15. Connecting part; 16. Positioning section. Example 1, such as Figure 1-3 As shown, a three-point closing tooling for threaded pins based on threaded adjustment and a spherical three-jaw 9 structure includes a screw 6, with the screw 6 as the bottom core bearing component. Its axis is perpendicular to the surface of the external worktable. The bottom of the screw 6 is fixedly connected to the external worktable 19 by welding or by bolts for easy maintenance and replacement. The external thread specification at the top of the screw 6 is M20×2, which is used to mate with the internal thread hole at the bottom of the connecting rod 4.

[0018] Spring 7 is coaxially sleeved on the outside of screw 6. Spring 7 is made of 65Mn steel with a wire diameter of 5mm and a free length of 80mm. The bottom end of spring 7 is tightly fitted to the surface of the external workbench, and the top end abuts against the lower surface of washer 5. Washer 5 has a circular structure, is made of 45 steel with a thickness of 2.5mm, and its inner diameter is 0.15mm larger than the outer diameter of screw 6. The upper surface of washer 5 is completely fitted to the bottom end face of positioning sleeve 1, and the outer diameter of washer 5 is matched with the inner diameter of screw 6, ensuring that washer 5 can only move vertically along the axis of screw 6 without radial offset.

[0019] A connecting rod 4 is provided on the positioning sleeve 1. The connecting rod 4 is cylindrical in shape, with a diameter of 40 mm and a length of 120 mm. An internal threaded hole is opened in the center of its bottom, which engages with the external thread at the top of the screw 6 through the internal thread, so as to realize the detachable fixation of the connecting rod 4 and the screw 6. A boss 8 is integrally formed on the outer side of the bottom of the connecting rod 4. The boss 8 has a diameter of 48 mm and a thickness of 10 mm. The outer circumferential surface of the boss 8 is clearance-fitted with the side wall of the U-shaped groove 3 on the inner wall of the positioning sleeve 1 to limit the radial sway of the connecting rod 4. A stepped positioning hole is opened in the center of the top of the connecting rod 4. The positioning hole includes a first guide hole 12 and a second guide hole 13 arranged sequentially from top to bottom. The first guide hole 12 has a diameter of 30 mm and a depth of 20 mm. The second guide hole 13 has a diameter of 25 mm and a depth of 30 mm. The inner wall of the second guide hole 13 has an internal thread with a specification of M24×1.5, which is used to cooperate with the connecting part 15 at the bottom of the positioning post 14.

[0020] The positioning sleeve 1 is a cylindrical hollow structure made of 40Cr steel, with an outer diameter of 60mm, an inner diameter of 50mm, and a length of 150mm. The positioning sleeve 1 is coaxially sleeved on the outside of the connecting rod 4, and its bottom is tightly fitted with the surface of the external workbench. It can be fixed to the workbench by bolts passing through the connecting hole 2 on the side wall of the positioning sleeve 1. A U-shaped groove 3 is opened at the bottom of the positioning sleeve 1 along the axial direction. The width of the U-shaped groove 3 is 48.2mm and the depth is 50mm. It runs through the bottom of the positioning sleeve 1 perpendicular to the axis.

[0021] The positioning post 14 is cylindrical in shape, made of hard alloy, with a diameter of 25mm and a total length of 80mm. The bottom of the positioning post 14 has a connecting part 15 with an external thread specification of M24×1.5. This external thread engages with the internal thread of the second guide hole 13 at the top of the connecting rod 4, enabling detachable fixing of the positioning post 14 and the connecting rod 4. The middle of the positioning post 14 has an integrally formed annular placement platform with a diameter of 30mm and a thickness of 10mm. The diameter of the placement platform perfectly matches the diameter of the first guide hole 12, and the bottom surface of the annular placement platform tightly fits the stepped surface of the first guide hole 12, forming an axial limit. The upper end of the positioning post 14 is a positioning section 16 with a diameter of 12mm, which matches the diameter of the through hole in the rod of the threaded pull pin to be closed. This section is used to insert the threaded pull pin into the through hole of the rod to achieve positioning and placement of the pull pin.

[0022] Three spherical three-jaw jacks 9 are provided, made of Cr12MoV steel. Each spherical three-jaw jack 9 is 150mm long. One end is connected to the external closing machine drive mechanism through an adjusting bolt. The connecting end has a waist-shaped hole, which is set along the length of the spherical three-jaw jack 9, with a length of 20mm and a width of 10mm. The other end is machined into a spherical working end 10. The three spherical three-jaw jacks 9 are evenly distributed in a circle around the axis of the positioning post 14. The included angle between the spherical three-jaw jacks 9 is 120°. The spherical working end 10 faces the threaded pin to be closed at the top of the positioning post 14, and the distance between the spherical working end 10 and the top cap of the pin can be adjusted through the waist-shaped hole.

[0023] Tooling assembly process Weld screw 6 vertically to the preset position on the external worktable, ensuring the perpendicularity error between the axis of screw 6 and the worktable surface. After welding, the weld seam is ground with an angle grinder to prevent protrusions from affecting the assembly of subsequent components.

[0024] Insert the spring 7 coaxially into the screw 6, ensuring that the bottom of the spring 7 fits tightly against the worktable surface; insert the washer 5 from the top of the screw 6, so that the lower surface of the washer 5 fits against the top of the spring 7, and check whether the washer 5 can slide freely along the screw 6.

[0025] Hold the connecting rod 4 and align its bottom internal threaded hole with the top external thread of the screw 6. Slowly rotate it until the bottom end face of the connecting rod 4 is in contact with the upper surface of the washer 5. During the rotation, observe whether the connecting rod 4 is vertical and ensure that it is not tilted.

[0026] Insert the positioning sleeve 1 from the top of the connecting rod 4, so that the inner wall of the sleeve fits against the outer wall of the connecting rod 4, until the bottom of the positioning sleeve 1 fits against the workbench surface; adjust the position of the positioning sleeve 1 so that the U-shaped groove 3 is aligned with the boss 8 of the connecting rod 4, and the gap between the outer circumference of the boss 8 and the side wall of the U-shaped groove 3 is uniform.

[0027] Based on the interlayer length of the M6 ​​threaded pull pin to be processed, such as initially processing a 5mm interlayer pull pin, rotate the positioning post 14 and screw its bottom external thread into the internal thread of the second guide hole 13 of the connecting rod 4. Read the adjustment depth through the scale line of the connecting rod 4 so that the distance between the positioning hole at the top of the positioning post 14 and the working end of the spherical three-jaw 9 is 5mm, until the bottom surface of the annular placement platform of the positioning post 14 is in contact with the step surface of the first guide hole 12.

[0028] Select a spherical three-jaw jack 9 with a spherical radius of 6mm and install it on the output end of the closing machine drive mechanism using M8 bolts. Adjust the position of the three spherical three-jaw jacks 9 to ensure they are evenly distributed in a 120° circle around the axis of the positioning post 14, with the distance between the spherical working end 10 and the axis of the positioning post 14 being 6mm. Fine-tune the position of the bolts through the slotted holes to ensure the coaxiality error between the spherical working end 10 and the positioning hole at the top of the positioning post 14 is correct. .

[0029] Check the specifications of the M6 ​​threaded pull pin to be closed: the rod diameter is 6mm, the interlayer length is 5mm, and the top cap diameter is 12mm. Confirm that the diameter of the positioning hole at the top of the positioning post 14 and the adjustment depth are both suitable.

[0030] Hold the threaded pin and slowly insert its rod into the positioning part of the positioning post 14 until it reaches the position of the boss 8, ensuring that the pin rod fits snugly against the positioning part without any looseness, and that the pin cap is positioned above the boss 8 on the positioning post 14.

[0031] Enter the preset closing value on the closing machine control panel. Based on the M6 ​​threaded pin tightening torque standard, the required tightening torque is... The output force of the closing machine is set accordingly. The closing stroke is 2mm. Through preliminary testing and calibration, this parameter can ensure that the edge of the cap deforms evenly to meet the torque requirements.

[0032] Press the start button of the sealing machine, and the motor drives the three spherical three-jaw grouts to move synchronously towards the center at a speed of [missing information]. The spherical working end 10 gradually contacts the edge of the rivet cap and applies uniform extrusion pressure; during the process, the pressure value is monitored in real time by the pressure sensor built into the closing machine to ensure that the pressure is stable. If the pressure fluctuation exceeds the range, the equipment will automatically stop and alarm, and will be restarted after troubleshooting.

[0033] When the spherical three-jaw jack 9 moves to the preset stroke, the closing machine automatically stops driving, maintains pressure for 3 seconds, and then releases pressure to complete the three-point synchronous closing.

[0034] Press the reset button on the closing machine, and the motor will drive the spherical three-jaw 9 to move centrifugally to the initial position. During the reset process, observe whether the three jaws are synchronized.

[0035] Remove the threaded pin from the positioning post 14 after it has been closed, and check the closed state of the threaded pin, whether the edges are deformed inward evenly, and whether there are any cracks or deviations.

[0036] If you continue to process the same specification of pull pins, there is no need to readjust the tooling; if you change the specification, such as processing 8mm sandwich M6 pull pins, rotate the positioning post 14 to adjust the depth, and use the scale line to make the distance between the positioning post 14 and the working end of the three-jaw jack 8mm, without replacing other parts; if you change to M8 pull pins, you need to replace the spherical three-jaw jack 9 with one with a spherical radius of 8mm, and fine-tune the position of the three-jaw jack through the oblong hole to ensure a fit.

[0037] The above are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the description of specific embodiments in the specification can be used to interpret the content of the claims.

Claims

1. A three-point closing tooling for threaded pins based on thread adjustment and a spherical three-jaw structure, characterized in that, The device includes a positioning sleeve, in which a connecting rod is axially movably inserted. The connecting rod passes through the positioning sleeve and is clearance-fitted with it. The bottom of the connecting rod has an internal threaded hole, in which a screw is fitted. The bottom end of the screw is fixed to an external worktable. A spring is fitted on the screw, and a washer is fitted at the end of the spring near the positioning sleeve. The top surface of the washer fits against the bottom end face of the positioning sleeve, and the bottom surface abuts against the top of the spring. The washer and the screw are in clearance fit. A positioning hole is opened at the top of the connecting rod, and a positioning post is provided on the connecting rod. The positioning post is connected to the positioning hole. The outer periphery of the positioning post is evenly distributed with multiple spherical three-jaws along the circumferential direction. One end of each spherical three-jaw is fixedly connected to the drive mechanism of the external closing machine, and the other end is the spherical working end. The spherical working end faces the threaded pin closing part at the top of the positioning post to achieve three-point synchronous extrusion closing. The positioning hole at the top of the connecting rod has a stepped structure, comprising a first guide hole and a second guide hole arranged sequentially from top to bottom. The diameter of the first guide hole is larger than that of the second guide hole. The inner wall of the second guide hole is provided with an internal thread for engaging with the external thread of the positioning post. A U-shaped groove is provided at the bottom of the positioning sleeve, which is located on the axis of the positioning sleeve and the connecting rod and extends perpendicularly through the bottom of the positioning sleeve. A boss is provided at the bottom of the connecting rod, the diameter of which is larger than that of the connecting rod, and the boss is clearance-fitted with the side wall of the U-shaped groove. A waist-shaped hole is provided at the connection end between the spherical three-jaw jack and the external closing machine drive mechanism. The waist-shaped hole is arranged along the length of the spherical three-jaw jack, and the distance between the spherical three-jaw jack and the positioning post can be finely adjusted by adjusting the position of the bolt in the waist-shaped hole.

2. The threaded pin three-point closing tooling based on thread adjustment and a spherical three-jaw structure according to claim 1, characterized in that, The gasket has a circular structure, is made of No. 45 steel, has a thickness of 2-3 mm, and its inner diameter is 0.1-0.2 mm larger than the outer diameter of the screw.

3. The threaded pin three-point closing tooling based on thread adjustment and a spherical three-jaw structure according to claim 1, characterized in that, The second guide hole is threadedly connected to the connecting part provided at the lower end of the positioning post.

4. The threaded pin three-point closing tooling based on thread adjustment and spherical three-jaw structure according to claim 1, characterized in that, The positioning column has an integrally formed annular placement platform in the middle. The diameter of the placement platform is adapted to the diameter of the first guide hole of the connecting rod, and the bottom surface of the placement platform is in contact with the stepped surface of the first guide hole.

5. The threaded pin three-point closing tooling based on thread adjustment and a spherical three-jaw structure according to claim 1, characterized in that, The connection end between the spherical three-jaw jack and the external closing machine drive mechanism is provided with an oblong hole. The oblong hole is set along the length direction of the spherical three-jaw jack. By adjusting the position of the bolt in the oblong hole, the distance between the spherical three-jaw jack and the positioning post can be finely adjusted.

6. A method for three-point closing of a threaded pin based on the threaded adjustment and spherical three-jaw structure three-point closing fixture as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Tooling assembly: Vertically fix the screw to the external worktable, coaxially insert the spring into the screw, and place a washer on the top of the spring; screw the internal threaded hole at the bottom of the connecting rod into the top of the screw until the bottom end face of the connecting rod is in contact with the upper surface of the washer; insert the positioning sleeve from the top of the connecting rod so that the bottom of the positioning sleeve is in contact with the worktable surface; select a spherical three-jaw jack with a suitable spherical radius according to the diameter of the threaded pin to be closed, and install it on the external closing machine drive mechanism, ensuring that the three spherical three-jaw jacks are evenly distributed around the circumference and that the spherical working ends face the axis of the positioning column; S2: Part positioning. Based on the length of the threaded pin interlayer to be closed, rotate the positioning post to adjust its thread engagement depth with the connecting rod. Read the adjustment depth through the scale line of the connecting rod so that the distance between the top of the positioning hole of the positioning post and the working end of the spherical three-jaw jack matches the interlayer length. Place the threaded pin rod to be closed into the positioning hole of the positioning post, ensuring that the top cap of the threaded pin is above the top of the positioning post. S3: Closing operation. Input the preset closing value on the closing machine control panel. The closing value is determined according to the standard locking torque of the threaded pin. Start the closing machine. The motor drives the three spherical three-jaw jacks to move synchronously in the center. The spherical working end applies uniform extrusion force to the edge of the threaded pin top cap to complete the three-point synchronous closing. S4: Reset and part removal. After the closing is completed, the motor drives the spherical three-jaw centrifugal movement to reset and remove the closed threaded pin. If processing parts of the same specification, repeat S2-S3. If the specifications are changed, repeat S1-S3.

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