Filter field capacitor small sleeve guide pin lead crimping die and crimping process thereof

Abstract

The application provides a filter field capacitor small sleeve guide rod lead wire crimping die, and belongs to the technical field of dies. The filter field capacitor small sleeve guide rod lead wire crimping die comprises a lower die, a supporting inclined block, a frame die and an upper die. A pair of limiting holes are formed in the vertical plane of the lower die. A connecting hole corresponding to the limiting hole horizontally is formed in the other inclined surface opposite to the limiting hole. The vertical plane top of the lower die is an arc surface with a 120-degree concave. Another lower die is arranged in mirror image symmetry along the vertical plane of the lower die. The application can control the elastic diameter change contraction of the crimping die cavity along with the guide rod diameter, ensure that the guide rod is in close contact with the copper lead wire after crimping within a certain diameter specification error range, the internal guide rod does not have local gaps, eliminates the overheating hidden danger caused by poor contact, and makes every crimping reach the best effect.

Description

Filter field capacitor small bushing guide rod lead wire crimping die and crimping process Technical Field

[0001] This invention belongs to the field of sleeve lead crimping technology, specifically relating to a small sleeve guide rod crimping mold for filter field capacitors and its crimping process. Background Technology

[0002] Currently, abnormal heating has been found in the filter field capacitors used in the UHV AC / DC transmission project. After gradual investigation, it was discovered that the heating was caused by increased contact resistance at the top of the small bushing conductor. Further inspection of the outer diameter of the copper tube in the heating bushing conductor (the part of the copper tube not cold-pressed) revealed that the drawing specifies a diameter of φ10-φ10.1mm. On-site testing showed that the outer diameter of the copper tube in the heating bushing conductor was smaller than expected, measuring φ9.78mm and φ9.82mm respectively. In contrast, another normal bushing in the same capacitor system has copper tube outer diameters of φ10.02mm and φ10.04mm respectively. The outer diameter of the copper tube in the heating bushing conductor was found to be too small.

[0003] To simulate the insufficient compression caused by the smaller outer diameter of the copper tube in the bushing guide rod, the outer diameter of the copper tube of the qualified size bushing guide rod was ground down to 9.8mm. Both the qualified size bushing guide rod copper tube and the copper tube of the qualified size bushing guide rod were pressed with copper stranded wire in the same upper and lower fixed mold cavity. The contact resistance was then tested and compared. It was found that the contact resistance of the copper tube of the qualified size bushing guide rod was 56.2μΩ, while the contact resistance of the product after the copper tube was ground down was 263μΩ.

[0004] Based on the investigation and testing, as shown in Figures 1 and 2, the contact resistance between the abnormal bushing terminal and the copper stranded wire is too high. The main problem is that the outer diameter of the copper tube in the cold-pressed heating bushing guide rod is 0.18-0.22mm smaller. After the rounding shrinkage cold pressing, the outer diameter of the copper tube in the guide rod cannot be effectively compressed in the mold. After cold pressing, the copper tube in some positions cannot make sufficient contact with the soft copper stranded wire, resulting in increased contact resistance.

[0005] Therefore, if the inner diameter of the copper tube at the tail of the bushing guide rod is too large or the outer diameter is too small, exceeding the tolerance requirements, it will lead to insufficient pressing of the copper wire and guide rod by the cold pressing mold, resulting in increased contact resistance and causing localized overheating failure during current flow.

[0006] When standard-sized guide rods are crimped with copper tubes and stranded wires, reliable cold-pressing stability can be maintained. However, for non-standard-sized guide rods, the mold uses upper and lower fixed cavities and lacks the function of error correction and self-correction. As a result, some products have poor crimping quality, which is the biggest drawback and deficiency of the existing crimping technology. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the issue of poor crimping process for the small bushing guide rod leads inside capacitors in existing technologies, and to provide a crimping mold for the small bushing guide rod leads of filter field capacitors. To solve the above technical problem, the technical solution adopted by this invention is:

[0008] A filter field capacitor small bushing guide rod crimping die includes a lower die, a supporting inclined block, a frame die, and an upper die. A pair of limiting holes are formed on the vertical plane of the lower die. A connecting hole, horizontally corresponding to the limiting holes, is formed on another inclined surface opposite to the limiting holes. The top of the vertical plane of the lower die is a concave arc surface of 120 degrees. Another lower die is mirror-symmetrically arranged along the vertical plane. A strong spring is engaged between the corresponding limiting holes of the two lower dies. A limiting bolt is coaxially arranged inside the strong spring, with both ends of the limiting bolt engaged at the corresponding connecting holes of the two lower dies, thus forming a movable contraction gap between the two lower dies.

[0009] The inclined surfaces of the two lower molds are slidably connected to the supporting inclined blocks; the supporting inclined blocks are fixedly connected to the frame mold; the upper mold is set above the two lower molds, and the mold closing point of the upper mold is also provided with an inwardly concave arc surface of 120 degrees; the upper mold and the two lower molds are enclosed by their respective inwardly concave arc surfaces to form a mold cavity smaller than the outer diameter of the guide rod to be pressed.

[0010] Furthermore, a springback support is provided at the bottom of the lower mold; the springback support includes a springback spring, a pull rod, a bottom plate, and a top plate; the pull rod is fitted with a springback spring, one end of which is fixedly connected to the top plate, and the other end passes through the bottom of the frame mold and the bottom plate in sequence and is threadedly fixed to the bottom of the frame mold.

[0011] Furthermore, a stress-bearing plate is provided on the top plate, and one end of a connecting column is integrally fixedly connected to the four corners of the stress-bearing plate. The other end of the connecting column is movably riveted to the top plate. A pressure sensor is provided between the stress-bearing plate and the top plate.

[0012] Preferably, the supporting inclined block is detachably and fixed to the frame mold with a mortise and tenon joint.

[0013] Furthermore, several hemispherical pressure molds are vertically fixed downwards on the concave 120-degree arc surface of the upper mold.

[0014] Preferably, the outer sides of both ends of the mold cavity formed by the upper mold and the two lower molds are coaxially provided with expansion grooves.

[0015] Furthermore, the movable shrinkage gap formed between the two lower molds is less than the axial movement distance of both ends of the limiting bolt within the connecting hole.

[0016] A process for crimping the lead wires of a filter field capacitor's small bushing guide rod is implemented using a crimping mold for the lead wires of the filter field capacitor's small bushing guide rod, and includes the following steps:

[0017] S1. Cut copper stranded wire to the required length according to product specifications, and weld the loose strands at the ends of the copper stranded wire.

[0018] S2. Cut the fused copper stranded wire into segments according to the specified dimensions;

[0019] S3. The welded copper stranded wire and the copper tube of the guide rod are straightened.

[0020] S4. Insert the regularized copper stranded wire into the copper tube of the guide rod, and perform cold pressing operation in the filter field capacitor small bushing guide rod lead wire pressing mold.

[0021] Furthermore, the normalization process in step S3 includes:

[0022] S31. Place the cut copper stranded wire ends into the end mold for constraint processing, molding...

[0023] It is made into a round copper rod that matches the inner hole of the guide rod connecting tube;

[0024] S32. Boring and scraping the inner hole of the guide rod copper tube to remove the surface oxide layer and other impurities.

[0025] Furthermore, a pressure range is set for the lead wire of the guide rod to be crimped based on the actual cold-pressing pressure data set of qualified cold-pressed guide rods;

[0026] When performing cold pressing operations inside the filter field capacitor small bushing guide rod lead wire pressing die.

[0027] Referring to the pressure information transmitted by the pressure sensor inside the mold, the pressing operation stops when the pressure information transmitted by the pressure sensor reaches the set pressure range.

[0028] Compared with existing technologies, this invention can control the crimping mold cavity to elastically shrink with the guide rod diameter, ensuring that after crimping within a certain diameter tolerance range, the inner contact surface of the guide rod is in tight contact with the copper lead wire, eliminating local gaps and the risk of overheating caused by poor contact, thus achieving optimal results with each crimping. It solves the dimensional compatibility problem, effectively eliminating the impact of dimensional deviations on crimping quality and improving the reliability and consistency of crimping quality. The springback support enables flexible and rapid springback demolding, reducing the tension and reset pressure of the strong spring.

[0029] Meanwhile, the crimping process employs multiple operations, including welding, shearing, rounding, boring, and cold pressing, to further eliminate problems such as uneven pressure during crimping caused by loose strands in the copper stranded wire leads, oxidation of the guide rod, and large outer diameter tolerances, which can lead to overheating failures. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] Figure 1: Cross-sectional view of the heating guide rod crimp joint.

[0032] Figure 2: Cross-sectional view of the normal guide rod crimp joint.

[0033] Figure 3: A three-dimensional structural schematic diagram of Embodiment 1 of the present invention.

[0034] Figure 4: A cross-sectional structural schematic diagram of Embodiment 1 of the present invention.

[0035] Figure 5: A cross-sectional structural schematic diagram of Embodiment 1 of the present invention (second example).

[0036] Figure 6: Schematic diagram of the three-dimensional structure of the spring support in Embodiment 1 of the present invention.

[0037] Figure 7: A second three-dimensional structural schematic diagram of Embodiment 1 of the present invention.

[0038] Figure 8: Schematic diagram of the three-dimensional exploded structure of Embodiment 1 of the present invention.

[0039] Among them, 1-lower mold, 11-limiting hole, 12-connecting hole, 13-arc surface, 14-strong spring, 15-limiting bolt, 2-supporting inclined block, 3-frame mold, 4-upper mold, 41-pressing mold, 42-outer expansion groove, 5-guide rod, 51-copper tube, 6-springback support, 61-springback spring, 62-pull rod, 63-bottom plate, 64-top plate, 65-force plate, 66-connecting column, 7-pressure sensor. Detailed Implementation

[0040] To better understand the present invention, the following embodiments further illustrate the content of the invention, but the scope of protection of the present invention is not limited to the following embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0041] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0042] Example 1, see Figures 3-8.

[0043] A filter field capacitor small bushing guide rod crimping mold includes a lower mold 1, a supporting inclined block 2, a frame mold 3, and an upper mold 4. A pair of limiting holes 11 are formed on the vertical plane of the lower mold 1. A connecting hole 12, horizontally corresponding to the limiting holes 11, is formed on another inclined surface opposite to the limiting holes 11. The top of the vertical plane of the lower mold 1 is an arc surface 13 with a 120-degree concave inward angle. Another lower mold 1 is mirror-symmetrically arranged along the vertical plane. A strong spring 14 is engaged between the corresponding limiting holes 11 of the two lower molds 1. A limiting bolt 15 is coaxially arranged inside the strong spring 14, with both ends of the limiting bolt 15 engaged at the corresponding connecting holes 12 of the two lower molds 1, creating a movable contraction gap between the two lower molds 1. A dynamic balance is achieved between the preload of the limiting bolt 15 and the elastic force of the strong spring 14. When the pressing force provided by the upper mold 4 is transmitted to the lower mold 1, the strong spring 14 is further compressed, and the limiting bolt 15 moves axially within the connecting hole 12; the movable shrinkage gap formed between the two lower molds 1 is less than the axial movement distance of the two ends of the limiting bolt 15 within the connecting hole 12, so as to avoid mold overload damage.

[0044] The inclined surfaces of the two lower molds 1 are each slidably connected to the supporting inclined blocks 2; the supporting inclined blocks 2 are made of hard aluminum alloy, and their inclined surface angle matches that of the lower mold 1; the supporting inclined blocks 2 are fixedly connected to the frame mold 3 by mortise and tenon joints. The frame mold 3 is an integral cast iron structure, providing rigid support. The sliding contact surfaces of the supporting inclined blocks 2 and the lower molds 1 are coated with grease to reduce friction loss. The mortise and tenon structure is designed with trapezoidal tenons and dovetail joints, allowing for easy separation by tapping and pulling during disassembly, and self-locking by gravity during assembly.

[0045] The upper mold 4 is positioned above the two lower molds 1, and a concave arc surface 13 of 120 degrees is also provided at the mold closing point with the lower molds 1. The upper mold 4 and the two lower molds 1 form a mold cavity smaller than the outer diameter of the guide rod to be pressed by their respective concave arc surfaces 13, ensuring that the copper tube 51 part of the guide rod 5 undergoes appropriate shrinkage deformation during pressing.

[0046] Furthermore, a springback support 6 is provided at the bottom of the lower mold 1; the springback support 6 includes a springback spring 61, a pull rod 62, a bottom plate 63, and a top plate 64; the pull rod 62 is fitted with a springback spring 61, one end of which is fixedly connected to the top plate 64, and the other end passes through the bottom of the frame mold 3 and the bottom plate 63 in sequence and is threadedly fixed to the bottom of the frame mold 3. One end of the springback spring 61 abuts against the bottom of the top plate 64, and the other end abuts against the bottom of the frame mold 3.

[0047] Furthermore, a force-bearing plate 65 is provided on the top plate 64, and one end of a connecting column 66 is integrally fixedly connected to the four corners of the force-bearing plate 65. The other end of the connecting column 66 is movably riveted to the top plate 64. A pressure sensor 7 is provided between the force-bearing plate 65 and the top plate 64 to transmit pressure changes during the cold pressing process to the outside.

[0048] Furthermore, several hemispherical pressing molds 41 are vertically fixed downwards on the concave 120-degree arc surface 13 of the upper mold 4. The hemispherical pressing molds 41 are evenly distributed on the arc surface of the upper mold, and during pressing, they form indentations on the surface of the copper tube 51 embedded in the guide rod 5, increasing the contact area and pull-out resistance.

[0049] Preferably, the mold cavity formed by the upper mold 4 and the two lower molds 1 is provided with coaxially extended grooves 42 on both outer sides. The extended grooves 42 at both ends of the mold cavity are used to accommodate the material overflowing from the end lead wire of the copper tube 51 of the guide rod 5 after extrusion, avoiding burrs and sharp edges; at the same time, it avoids the shear stress concentration at the beginning of the copper tube 51, which may cause shear cracks in the copper tube 51, thus reducing the production of defective products.

[0050] In use, the lower mold 1 connected to the frame mold 3 is placed horizontally in a flat position, and the upper mold 4 is fixedly connected to the pressure output end of the press. The mating position of the upper mold 4 and the lower mold 1 is calibrated to ensure accurate mold closing between the upper mold 4 and the two lower molds 1. The copper stranded wire is inserted into the copper tube 51 of the guide rod 5, and the copper tube 51 is placed on the arc-shaped mold cavity of the two lower molds 1. The press drives the upper mold 4 downward, and the pressure mold 41 first contacts the copper tube 51. As the pressure increases, the two lower molds 1 slide down synchronously along the inclined surface of the support inclined block 2, and the strong spring 14 is compressed, closing the mold. The diameter of the mold cavity continuously decreases; at this time, the bottom of the lower mold 1 forms horizontal sliding friction with the force plate 65, and at the same time, pressure is applied downward. The pressure transmitted by the upper mold 4 is transmitted to the spring spring 61 through the lower mold 1, the force plate 65, the pressure sensor 7 and the top plate 64. During the pressing process, the spring spring 61 is further compressed; when the cold pressing work is completed, the pressure is removed, the spring spring 61 is slowly released, pushing the lower mold 1 to gradually move upward along the inclined plane. The diameter of the mold cavity slowly returns to its initial state under the tension of the strong spring 14, realizing flexible spring demolding.

[0051] Compared to existing technologies, this invention allows for the control of the crimping mold cavity to elastically shrink and adjust to the diameter of the guide rod 5. This ensures that after crimping within a certain diameter tolerance range, the inner contact surface of the guide rod 5 maintains tight contact with the copper leads, preventing localized gaps and eliminating the risk of overheating due to poor contact. This ensures optimal results for every crimping operation. It also solves the dimensional compatibility problem, effectively eliminating the impact of dimensional deviations on crimping quality and improving its reliability and consistency. The springback support 6 enables flexible and rapid springback demolding, reducing the tension and reset pressure of the powerful spring.

[0052] Example 2: A filter field capacitor small bushing guide rod lead crimping process, implemented using the filter field capacitor small bushing guide rod lead crimping mold of Example 1, includes the following steps:

[0053] S1. Cut copper stranded wire to the required length according to product specifications. Use micro-beam plasma welding to instantly melt several strands of copper wire within the specified length at the end of the copper stranded wire to form a dense cylinder. The melting depth is controlled at 1.0~1.2 mm, which maintains the conductivity of copper material and completely eliminates loose strands.

[0054] S2. Cut the fused copper stranded wire into segments according to the specified dimensions;

[0055] S3. The welded copper stranded wire and the guide rod copper tube are standardized; that is, the cylindrical end of the cut copper stranded wire is placed in the constrained round mold for constrained processing to form a round copper rod that matches the inner hole of the guide rod copper tube; then the inner hole of the guide rod copper tube is bored and scraped to remove the surface oxide layer and other impurities.

[0056] S4. Insert the regularized copper stranded wire into the copper tube of the guide rod, and perform cold pressing operation in the filter field capacitor small bushing guide rod lead wire pressing mold.

[0057] Furthermore, a pressure range is set for the lead wire of the guide rod to be crimped based on the actual cold-pressing pressure data set of qualified cold-pressed guide rods;

[0058] When performing cold pressing operations inside the filter field capacitor small bushing guide rod lead wire pressing die.

[0059] The crimping pressure information is collected in real time and transmitted to the press. When the pressure information transmitted by the pressure sensor reaches the set pressure range, the press immediately stops the crimping operation, further preventing problems such as underpressure causing loose connections and overheating between the lead wire and the guide rod, and overpressure causing cracking and producing defective products.

[0060] The detailed execution methods of some steps in this embodiment have been described in Embodiment 1 and will not be repeated here.

[0061] To further verify the reliability of this process, resistance and tensile strength tests were conducted on 100 samples treated with the improved process. The resistance test results are shown in Table 1. The random sampling tensile strength tests are shown in Table 2, and the results were good, all meeting the requirements.

[0062] Table 1. Statistical Table of Resistance Test Data

[0063] Resistance value (μΩ) Quantity / Percentage 30~35 33 33% 35~40 46 46% 40~45 15 15% 45~50 66% surface

[0064] Table 2 Statistical Table of Tensile Test Data

[0065] Number Tensile Test 1200N Tensile Test Contact Resistance (μΩ) Before Tensile Test Contact Resistance (μΩ) After Tensile Test 1 Pass 39.7 37.5 2 Pass 43.4 44.1 3 Pass 42.9 45.0 4 Pass 42.4 41.2 5 Pass 41.9 43.8 surface

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A crimping die for the lead wire of a filter field capacitor small bushing, characterized in that: The system includes a lower mold, a supporting inclined block, a frame mold, and an upper mold. A pair of limiting holes are formed on the vertical plane of the lower mold. A connecting hole, horizontally corresponding to the limiting holes, is formed on another inclined plane opposite to the limiting holes. The top of the vertical plane of the lower mold is a concave arc surface of 120 degrees. Another lower mold is mirror-symmetrically arranged along the vertical plane. A strong spring is engaged between the corresponding limiting holes of the two lower molds. A limiting bolt is coaxially arranged inside the strong spring, and both ends of the limiting bolt are engaged with the two lower molds respectively. At the corresponding connecting holes, a movable shrinkage gap is formed between the two lower molds; the inclined surfaces of the two lower molds are each slidably connected to the supporting inclined blocks; the supporting inclined blocks are fixedly connected to the frame mold; the upper mold is set above the two lower molds, and the mold closing point of the upper mold is also provided with an inwardly concave arc surface of 120 degrees; the upper mold and the two lower molds are enclosed by their respective inwardly concave arc surfaces to form a mold cavity smaller than the outer diameter of the guide rod to be pressed; a hemispherical pressing mold is fixedly provided on the inwardly concave arc surface of the upper mold.

2. The filter field capacitor small bushing guide rod lead crimping mold according to claim 1, characterized in that: The bottom of the lower mold is provided with a spring-loaded support; the spring-loaded support includes a spring-loaded spring, a pull rod, a bottom plate and a top plate; the pull rod is fitted with a spring-loaded spring, one end of which is fixedly connected to the top plate, and the other end passes through the bottom of the mold frame and the bottom plate in sequence and is threadedly fixed to the bottom of the mold frame.

3. The filter field capacitor small bushing guide rod lead crimping mold according to claim 2, characterized in that: A load-bearing plate is provided on the top plate, and one end of a connecting column is integrally fixedly connected to the four corners of the load-bearing plate. The other end of the connecting column is movably riveted to the top plate. A pressure sensor is provided between the load-bearing plate and the top plate.

4. The filter field capacitor small bushing guide rod lead crimping mold according to claim 1, characterized in that: The supporting inclined block is fixed to the frame mold by a detachable mortise and tenon joint.

5. The filter field capacitor small bushing guide rod lead crimping mold according to claim 1, characterized in that: The mold cavity formed by the upper mold and the two lower molds is coaxially provided with outer expansion grooves on both sides.

6. The filter field capacitor small bushing guide rod lead crimping mold according to claim 1, characterized in that: The movable shrinkage gap formed between the two lower molds is less than the axial movement distance of both ends of the limiting bolt within the connecting hole.

7. A process for crimping the lead wires of a filter field capacitor small bushing, implemented using the crimping mold for the lead wires of a filter field capacitor small bushing as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Cut copper stranded wire to the required length according to product specifications, and weld the loose strands at the ends of the copper stranded wire; S2. Cut the welded copper stranded wire into segments according to the specified dimensions; S3. Regularize the welded copper stranded wire and the guide rod copper tube; S4. Insert the regularized copper stranded wire into the guide rod copper tube, and perform cold pressing operation in the filter field capacitor small bushing guide rod lead wire crimping mold.

8. The filter field capacitor small bushing guide rod lead crimping process according to claim 7, characterized in that, The regularization process in step S3 includes: S31, placing the cut copper stranded wire end into the end mold for constraint processing to shape it into a round copper rod that matches the inner hole of the guide rod connecting tube; S32, boring and scraping the inner hole of the guide rod copper tube to remove the surface oxide layer and other impurities.

9. The filter field capacitor small bushing guide rod lead crimping process according to claim 8, characterized in that: Based on the actual cold pressing pressure data of the qualified cold pressing guide rod, a pressure range is set for the guide rod lead wire to be pressed; when performing cold pressing operation in the filter field capacitor small sleeve guide rod lead wire pressing mold, the pressing work is stopped after the pressure information reaches the set pressure range.

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