Method of manufacturing a compression-type equipment clamp friction weld

Abstract

The application discloses a kind of compression type equipment wire clamp friction welding manufacturing method, belong to electric power fitting manufacturing technical field.This method includes: the welding boss end face of T type blank and aluminum pipe end face are pretreated, ensure that two end faces are parallel by machining and surface roughness Ra is 3.2 μm-6.3 μm, after oil removal cleaning, wait for welding;After pretreatment, blank and aluminum pipe are clamped, and are sequentially carried out friction preheating, slag pulse, stable friction and top forging, and are welded into an integrity under solid phase;After welding, remove weld scar, and the finished product is obtained.The application introduces pulse slag removal technology, combined with phased friction welding process, eliminates fusion welding crack and casting shrinkage, and is especially suitable for the manufacture of 1050A pure aluminum material equipment wire clamp.This method does not need annealing treatment after welding, breaks through the size limit of sheet material, and the tensile strength of the welding zone reaches more than 95% of the base material, with high degree of automation, suitable for mass production of high-reliability equipment wire clamp.

Description

Technical Field

[0001] This invention belongs to the field of power fitting manufacturing technology, and specifically discloses a method for manufacturing compression type equipment wire clamps by friction welding. Background Technology

[0002] Compression clamps are core hardware in substations and transmission lines used to reliably connect conductors to equipment terminals. Their typical structure consists of a T-shaped blank with a terminal block and an aluminum tube for crimping the conductors. During operation, these clamps must withstand conductor tension, wind vibration, and heat generation, thus requiring extremely high mechanical strength and conductivity in the plate-tube connection area. Conventional equipment clamp manufacturing processes mainly include integral casting, aluminum rod forging, and argon arc welding using forged aluminum tubes and aluminum plates. While integral casting can produce complex shapes, defects such as shrinkage cavities, porosity, cold shuts, oxide layers, and cracks are unavoidable during aluminum solidification, resulting in poor density, decreased conductivity, and significant strength dispersion. Aluminum rod forging is limited by the size of the rod material, with plate width typically less than 120mm. Integral forging also limits plate width, making it impossible to manufacture larger sizes. After forging aluminum tubes, argon arc welding is performed using aluminum plates. Due to the high heat input, hot cracks and porosity are easily generated in the weld and heat-affected zone, and incomplete welds are prone to occur, resulting in unstable quality and affecting the product appearance. These problems make the safety and lifespan of existing equipment clamps seriously insufficient when developing for large-section conductors and ultra-high voltage lines.

[0003] Friction welding, as a highly efficient solid-state joining technology, eliminates weld cracks and casting shrinkage porosity in principle due to its characteristics of no molten pool and solid-state connection, and has demonstrated excellent performance in the joining of rotating parts such as aluminum wheels. However, when directly applied to equipment clamps with asymmetrical plate structures, it still faces a series of technical obstacles, such as poor clamping rigidity, difficulty in removing oxide film from the welding interface, and control of residual stress after welding. Especially for softer materials such as 1050A pure aluminum, there is still no mature process solution for effectively removing the interface oxide film and ensuring welding quality. Based on this technical need, this invention proposes an optimized friction welding manufacturing method for compression-type equipment clamps, aiming to achieve the manufacturing of large-scale, high-reliability clamps suitable for mass production. Summary of the Invention

[0004] The purpose of this invention is to provide a friction welding manufacturing method for compression-type equipment clamps, thereby solving the technical problems of dimensional limitations, easy cracking in the connection area, and insufficient electrical performance in traditional casting and welding processes. By developing pretreatment control suitable for T-shaped asymmetric structures, a sequential friction preheating-stabilized friction-upsetting friction welding process, pulse slag removal technology, and post-weld treatment, complete metallurgical bonding between the aluminum tube and the T-shaped billet is achieved. This results in a dense, forged structure in the welded area, with strength reaching the level of the base material, and enables the stable manufacture of ultra-large, high-reliability equipment clamps.

[0005] To achieve the above objectives, the present invention provides a friction welding manufacturing method for compression-type equipment clamps, specifically comprising the following steps: Step 1: Pretreatment of T-shaped billet and aluminum tube The T-shaped blank is an aluminum part made by cutting extruded aluminum profiles. It includes an integrally formed plate and a cylindrical or frustum-shaped welding boss perpendicular to one side of the plate. The end face of the welding boss is flat, and the surface is machined by a lathe or milling machine to ensure flatness and parallelism with the end face of the aluminum tube. The aluminum tube is a seamless extruded aluminum tube, with one end being the end to be welded and the other end being a wire crimping section. During pretreatment, the end face of the welding boss and the end face of the aluminum tube to be welded are machined to control the surface roughness Ra to 3.2μm-6.3μm and ensure that the parallelism of the two end faces is no greater than 0.05mm; then, the oil is thoroughly removed with acetone or alkaline cleaning agent, and the tube is dried before welding.

[0006] The method for measuring parallelism is as follows: using a dial indicator or laser rangefinder, with the overall plane of the welded boss end face as the reference plane, measure the difference between the maximum and minimum distances between the aluminum tube end face and the reference plane. This difference is the parallelism deviation of the two end faces.

[0007] The selection of the roughness Ra range of 3.2-6.3 μm is based on the following: when Ra is less than 3.2 μm, the contact surface is too smooth in the initial stage of friction, making it difficult to form a stable frictional heat and plastic shear flow layer, which easily leads to slippage and insufficient preheating; when Ra is greater than 6.3 μm, the surface micro-grooves are too deep, carrying too much oxide film and contaminants, which are difficult to completely remove during subsequent friction. A roughness of 3.2-6.3 μm is beneficial for quickly establishing a stable frictional state in the preheating stage, and can effectively extrude the oxide film with the plastic metal in the pulse slag discharge and stable friction stages, which is the optimal range verified by experiments.

[0008] Preferably, the thickness of the T-shaped blank can be 10-40mm and the width can be 80-300mm; the aluminum tube is a seamless extruded aluminum tube with an outer diameter of 30-100mm.

[0009] Step 2: Staged friction welding The pre-treated T-shaped blank is fixed to the moving end of the friction welding machine using a special fixture, with the plate as the reference surface. The aluminum tube is clamped to the rotating spindle end. The welding process includes, in sequence, the friction preheating stage, the friction stabilization stage, and the upsetting stage. (1) Friction preheating stage: The spindle drives the aluminum tube to rotate at 800-2000 rpm, applies a first-level friction pressure of 10-30 MPa for 2-8 seconds, so that the contact surface initially adheres and generates frictional heat, causing the residual micro oxide film to break.

[0010] (2) Stable friction stage: Maintain the rotation speed and increase the pressure to the secondary friction pressure of 25-60MPa for 3-12s. Through the stable shear flow of the plastic metal layer, the interface temperature is maintained at 0.6-0.9 times the solidus temperature of the aluminum alloy material to be welded (for 1050A pure aluminum, the solidus temperature is about 646℃, and the temperature range is about 388-581℃). At this time, the interface metal is in a superplastic state and the oxide film is continuously extruded.

[0011] (3) Upsetting stage: After reaching the set friction time or shortening amount, first brake the spindle. After the spindle completely stops rotating (or braking and pressure application are carried out simultaneously, but it must be ensured that braking and upsetting pressure are completed within 0.5s), quickly raise the upsetting pressure to 85-150MPa and hold it for 3-10s. The upsetting force causes the high-temperature ductile metal to undergo severe plastic deformation, completely pushing the residual oxide film and contamination layer into the flash (weld scar), forming a dense solid-phase metallurgical bond inside. No shielding gas is required throughout the welding process.

[0012] In this invention, "slag discharge pulse" is defined as: a dynamic slag discharge method in which a sudden high-pressure pulse causes the softened plastic metal at the interface to undergo severe shear deformation between frictional preheating and stable friction, thereby carrying oxide film fragments and extruding them radially at high speed.

[0013] In this invention, "weld scar" is defined as: excess ductile metal squeezed out from the welding interface during the welding process, forming a ring-shaped or continuous accumulation on the outer periphery of the workpiece.

[0014] Preferably, a slag removal pulse stage can be inserted between the friction preheating stage and the stabilization friction stage: the pressure is instantaneously increased to 50-70 MPa within 0.3-1.5 seconds and then restored to the secondary friction pressure within 0.2-0.8 seconds, repeated 1-3 times, causing the softened interface metal carrying oxide film fragments to be extruded radially at high speed, further improving the weld purity. This pulse slag removal technology is particularly suitable for softer materials such as 1050A pure aluminum, effectively breaking down and removing the interface oxide film, compensating for the inability to remove slag through mechanical channels due to the softness of the material.

[0015] During friction welding, the axial shortening and welding zone temperature are monitored in real time using a displacement sensor and an infrared thermometer. When the measured shortening falls within the preset range and the temperature curve deviates from the standard curve by less than ±10℃, the system determines that the welding is qualified; otherwise, it automatically alarms and rejects the weld. The preset target range for axial shortening is determined based on the outer diameter of the aluminum tube and is 3-15mm. The specific correspondences are as follows: for aluminum tubes with an outer diameter of 30-50mm, the shortening range is 3-6mm; for outer diameters of 50-80mm, the shortening range is 6-10mm; and for outer diameters of 80-100mm, the shortening range is 10-15mm. For outer diameters not listed, linear interpolation can be used to determine the shortening.

[0016] The interface temperature standard curve is a temperature-time reference curve obtained through multiple experiments on the same material and specifications under the same process parameters. The method for obtaining it is as follows: using aluminum tubes of the same material, outer diameter, and wall thickness as the workpiece to be welded, and T-shaped blanks of the same size, at least five welding experiments are conducted under identical friction welding process parameters (speed, pressure at each stage, and time). An infrared thermometer is used to continuously record the interface temperature change over time throughout the entire welding process. The temperature-time data points from each experiment are smoothed, and then the average value of all experimental temperatures at each time point is taken to plot an average temperature-time curve, which is the standard curve for that product specification. A temperature deviation of ≤±10℃ between the measured curve and the standard curve at the same time point is considered acceptable.

[0017] Step 3: Post-weld treatment After welding, once the workpiece has cooled to room temperature, the weld spatter extruded from the outer periphery of the welded area is removed by turning or milling to smooth the surface, resulting in a compression-type equipment wire clamp. The process parameters for weld spatter removal are: turning speed 50-150 m / min, feed rate 0.1-0.5 mm / r, and depth of cut 0.5-2 mm, to ensure that the weld spatter is removed without damaging the base material surface. The welded area is subjected to X-ray or phased array ultrasonic non-destructive testing to confirm the absence of internal defects. The resulting compression-type equipment wire clamp exhibits no cracks or porosity in the welded area; tensile tests show fractures occurring on the base material or conductor side; and the room temperature tensile strength of the welded area is not less than 95% of the tensile strength of the aluminum tube base material and the T-shaped billet base material.

[0018] A compression-type equipment clamp, manufactured using the above-mentioned method, is formed by welding a T-shaped blank and an aluminum tube. The welding area between the T-shaped blank and the aluminum tube is free of cracks and pores, and the room temperature tensile strength of the welding area is not less than 95% of that of the base material.

[0019] Preferably, the base material mentioned in this invention refers to aluminum tube base material and T-shaped billet base material.

[0020] Beneficial technical effects of the present invention: Friction welding for solid-state bonding, combined with pulse slag removal technology, eliminates hot cracking from fusion welding and shrinkage porosity from casting, resulting in a dense weld zone and completely resolving cracking issues in the plate-to-pipe connection area. Machining ensures flat and parallel end faces and simplifies pretreatment; combined with pulse slag removal, it maximizes oxide film removal efficiency. The T-shaped blank is cut from extruded profiles, not limited by plate width, allowing for the production of large-specification clamps with plate widths exceeding 300mm and pipe diameters up to 100mm. The conductivity is consistent with the base material, meeting the requirements of ultra-high voltage, high-capacity power transmission. No complex heat treatment is required after welding, simplifying the process and making it suitable for mass production. This invention provides a high-quality, highly flexible, and highly reliable solution for manufacturing compression-type equipment clamps. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the T-shaped blank of the present invention.

[0022] Figure 2 This is a schematic diagram of the welded boss end face.

[0023] Figure 3 A schematic diagram of the clamping process for welding the T-shaped blank to the aluminum tube.

[0024] Figure 4 This is a schematic diagram of the structure after welding (with weld spatter).

[0025] Figure 5 A schematic diagram of the compression-type equipment clamp structure after removing weld spatter.

[0026] In the figure: 1-T-shaped blank, 2-welding boss end face, 3-aluminum tube, 4-weld scar. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the term "comprising" in the specification and claims of this application is intended to cover a non-exclusive inclusion. For example, a method comprising a series of steps is not necessarily limited to those explicitly listed, but may include other steps not explicitly listed or inherent to these methods. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. The present application will now be described in detail with reference to embodiments.

[0029] Example 1

[0030] T-shaped blank 1 is made of 1050A pure aluminum, produced by extrusion and cutting. The plate body is machined to a final size of 150mm (length) × 100mm (width) × 12mm (thickness). A cylindrical welding boss extends vertically from the center of one side of the plate body, with a diameter of 52mm and a height of 12mm. The welding boss end face 2 is flat and machined by CNC milling to a surface roughness Ra of 5.5μm, ensuring parallelism with the aluminum tube end face of 0.03mm. Aluminum tube 3 is made of 1050A pure aluminum extrusion tube, with an outer diameter of 52mm, an inner diameter of 32.5mm, and a length of 130mm. The end face to be welded is a machined flat surface with a Ra of 5.0μm.

[0031] Pre-treatment process: Clean the boss end face 2 and the pipe end face with acetone to remove oil, and dry them before welding. No additional grinding or oxide film removal treatment is required.

[0032] Friction welding clamping and parameters: The T-shaped blank 1 is fixed in a non-rotating fixture, using the back and side surfaces of the plate as references, ensuring the perpendicularity of the boss end face; the aluminum tube 3 is clamped in the spindle hydraulic chuck. The friction welding machine is a 500kN continuous drive friction welding machine. The process timing is set as follows: Friction preheating stage: spindle speed 1500 rpm, first-stage friction pressure 20 MPa, duration 5.0 s. During this stage, the torque rapidly increases from zero to a stable value of 54 Nm, the cumulative axial shortening is 0.8 mm, and the interface temperature, as monitored by a thermal imager, rapidly rises from room temperature to approximately 370 °C.

[0033] Slag discharge pulse stage: After preheating, two pressure pulses are immediately executed, each time instantly raising the pressure to 60MPa within 0.3s and restoring it to 45MPa within 0.2s. The torque spikes at the moment of the pulse, reaching a maximum of 82Nm, indicating that the interfacial oxide film is violently broken and extruded with the flash.

[0034] Stable friction stage: After the pulse, the pressure stabilizes at 45 MPa, and friction continues for 7.0 s. During this stage, the torque stabilizes at 58 Nm, the highest interface temperature reaches 450℃, and the axial shortening increases at a constant rate of 0.7 mm / s, with a total shortening of 5.8 mm.

[0035] Upsetting stage: After reaching the set shrinkage amount, the spindle is braked within 0.15s, and then the pressure is increased to 100MPa within 0.4s and held for 5.0s (i.e., braking first, then applying pressure). During the upsetting process, a large amount of plastic flash can be seen being extruded from the welding interface, forming a complete annular weld scar 4. After holding the pressure, it is allowed to cool naturally.

[0036] Post-weld treatment: Weld scar 4 was removed using a CNC lathe, flush with the pipe surface. Turning parameters were: cutting speed 80 m / min, feed rate 0.2 mm / r, depth of cut 1.0 mm. After turning, the weld was visually inspected and subjected to X-ray flaw detection. The X-ray results showed no cracks, no incomplete fusion, and no porosity, resulting in a Grade I rating. Subsequently, the product underwent dimensional inspection, yielding a compression-type equipment wire clamp.

[0037] Example 2

[0038] T-shaped billet 1 is made of 1050A aluminum alloy, with dimensions of 250mm width, 180mm length, and 25mm thickness. The welding boss has a diameter of 80mm and a height of 18mm. The end face is flat, and the machining Ra is 4.2μm. Aluminum tube 3 is also made of 1050A aluminum alloy, with an outer diameter of 80mm, an inner diameter of 54mm, a length of 260mm, and an end face Ra of 4.8μm.

[0039] Pretreatment: Clean with acetone to remove oil, then dry.

[0040] Friction welding process: Preheating speed 1000 rpm, initial pressure 25 MPa, duration 6 s; slag removal pulses twice (pressure 65 MPa); stable friction stage pressure 55 MPa, duration 11 s. Actual peak interface temperature reached 480℃, axial shortening reached 9.5 mm. Upsetting pressure 130 MPa, holding pressure 8 s. An online quality monitoring system was used during welding, with the acceptable axial shortening threshold set at 9.5 mm and the maximum temperature limit at 500℃. Five pieces were actually welded. One piece experienced a sudden temperature jump to 506℃ in the later stage of stable friction, prompting the system to immediately issue an audible and visual alarm and automatically push the piece into the scrap area. The parameters of the remaining four pieces remained within tolerance throughout the process, and the system deemed them qualified.

[0041] After welding, the weld scars were removed, and the machining parameters were the same as in Example 1. All four pieces were tested and found to be free of defects.

[0042] Example 3

[0043] T-shaped blank 1 is made of 1050A pure aluminum, produced by extrusion and cutting. The plate body is machined to a final size of 120mm (length) × 80mm (width) × 10mm (thickness). A cylindrical welding boss extends vertically from the center of one side of the plate body, with a diameter of 40mm and a height of 10mm. The welding boss end face 2 is flat and machined by CNC milling to a surface roughness Ra of 5.8μm, ensuring parallelism with the aluminum tube end face of 0.04mm. Aluminum tube 3 is made of 1050A pure aluminum extrusion tube, with an outer diameter of 40mm, an inner diameter of 26mm, and a length of 100mm. The end face to be welded is a machined flat surface with a Ra of 6.0μm.

[0044] Pre-treatment process: Clean the boss end face 2 and the pipe end face with acetone to remove oil, and dry them before welding. No additional grinding or oxide film removal treatment is required.

[0045] Friction welding clamping and parameters: The T-shaped blank 1 is fixed in a non-rotating fixture, using the back and side surfaces of the plate as references, ensuring the perpendicularity of the boss end face; the aluminum tube 3 is clamped in the spindle hydraulic chuck. The friction welding machine is a 500kN continuous drive friction welding machine. The process timing is set as follows: Friction preheating stage: spindle speed 1800 rpm, first-stage friction pressure 15 MPa, duration 4.0 s. During this stage, the torque rapidly increases from zero to a stable value, the cumulative axial shortening is 0.5 mm, and the interface temperature, as monitored by a thermal imager, rapidly rises from room temperature to approximately 350 °C.

[0046] Slag discharge pulse stage: After preheating, two pressure pulses are immediately executed, each time instantly raising the pressure to 55MPa within 0.4s and then restoring it to 30MPa within 0.3s. The torque spikes at the moment of the pulse, indicating that the interfacial oxide film is violently broken and extruded with the flash.

[0047] Stable friction stage: After the pulse, the pressure stabilizes at 30 MPa, and friction continues for 8.0 s. During this stage, the torque is stable, the highest interface temperature reaches 430℃, and the axial shortening increases at a constant rate, with a total shortening of 3.5 mm.

[0048] Upsetting stage: After reaching the set shrinkage amount, the spindle is braked within 0.15s, and then the pressure is increased to 85MPa within 0.4s and held for 6.0s. During the upsetting process, a large amount of plastic flash can be seen being extruded from the weld interface, forming a complete annular weld scar 4. After holding the pressure, it is allowed to cool naturally.

[0049] Post-weld treatment: Weld scar 4 was removed using a CNC lathe, flush with the pipe surface. Turning parameters were: cutting speed 60 m / min, feed rate 0.15 mm / r, depth of cut 0.8 mm. After turning, the weld was visually inspected and subjected to X-ray flaw detection. The X-ray results showed no cracks, no incomplete welds, and no porosity, resulting in a Grade I rating. Subsequently, the product underwent dimensional inspection, yielding a compression-type equipment wire clamp.

[0050] Comparative Example 1 The blank and aluminum tube are made of the same 1050A material as in Example 1. The tube-boob butt joint circumferential weld was performed using manual AC tungsten inert gas (TIG) welding with 6mm ER1100 pure aluminum welding wire, a welding current of 300A, an argon flow rate of 25L / min, and a welding speed of approximately 120mm / min. After welding, the tube was allowed to cool naturally, and the weld reinforcement was ground down.

[0051] Comparative Example 2 The product's external dimensions and aluminum tube dimensions are the same as in Example 1. It is made of 1050A pure aluminum and is a gravity-cast integrally formed wire clamp.

[0052] Comparative Example 3 The workpiece and welding parameters were exactly the same as in Example 1. The only change was the pretreatment: the surface was simply wiped with a cotton cloth soaked in gasoline, without degreasing or cleaning, and no machining was performed. The measured Ra of the end face was 12.5 μm, and the parallelism deviation was 0.15 mm. During the welding process, the torque fluctuated violently, and high-frequency vibrations occurred. The infrared thermal imager showed uneven interface temperature. Post-weld flaw detection revealed multiple instances of incomplete welds.

[0053] Comparative Example 4 Based on Example 1, but with the slag removal pulse stage completely eliminated and the upsetting pressure reduced from 100 MPa to 60 MPa. Stable friction parameters remained unchanged. Post-weld flaw detection revealed localized linear incomplete welds in 3 out of 5 samples.

[0054] Comparative Example 5 Using the same workpiece material and dimensions as in Example 1, and with end face machining meeting requirements, the friction welding parameters were: preheating speed 1500 rpm, first-stage pressure 20 MPa, 5 s; direct entry into stable friction (no pulse slag removal), second-stage pressure 45 MPa, 7 s; upsetting pressure 60 MPa, holding pressure 5 s. Only weld spatter was removed post-weld by machining. A total of 5 pieces were prepared. Post-weld flaw detection revealed fine dot-like pores in 2 pieces and a slight oxide film inclusion in 1 piece.

[0055] Performance testing All examples and comparative examples followed the same testing and evaluation standards. Crimping tests were conducted according to GB / T2317.4-2023, using a test tensile bar. The dimensions of the crimping die and the post-crimping edge distance were strictly controlled according to the process specifications. Tensile tests were conducted according to GB / T2317.1-2008, using an Instron 5985 universal testing machine (maximum load 250kN) at a loading rate of 10mm / min. Fatigue tests were conducted according to GB / T3075-2021.

[0056] Evaluation criteria: Based on the tensile strength of 60MPa for 1050A pure aluminum, the acceptable tensile strength standard for the welded area is set at 95% of the theoretical tensile strength of the aluminum tube body (i.e., 60MPa × aluminum tube cross-sectional area × 0.95). If the measured failure load exceeds this standard value, the welded area is judged to meet the strength standard.

[0057] Thermal fatigue performance testing was conducted according to the self-restrained thermal fatigue test standard: the welded joint specimens were subjected to alternating cycles between room temperature and 350°C. Each cycle consisted of heating to 350°C and holding for 30 seconds, followed by forced cooling with compressed air to room temperature and holding for 30 seconds, with a complete cycle lasting 60 seconds. After 5000 thermal cycles, the surface fatigue crack morphology of the welded area and heat-affected zone was observed using a metallographic microscope. The maximum crack length was measured, and the number of cycles at which cracks ≥0.5 mm in length appeared was recorded as the thermal fatigue life. Five specimens were tested in each group, and the average value was taken.

[0058] The test results for each embodiment and comparative example are as follows: Example 1: After pressing the tension bar according to the standard, a total of 5 tensile tests were conducted. Fractures all occurred at the aluminum tube directly between the tension bar and the weld. The breaking loads of the 5 pieces were 78.6 kN, 79.5 kN, 79.3 kN, 80.1 kN, and 80.6 kN, with an average of 79.62 kN, exceeding the standard by 5.86 kN. The metallographic structure of the weld area showed a fine-grained recrystallized structure in a forged state, without oxide film inclusions. Thermal fatigue resistance: average thermal cycle life 4850 cycles, maximum crack length 0.20 mm.

[0059] Example 2: Tensile failure occurred on the conductor side in all cases. The failure loads of the four pieces were 157.3 kN, 159.5 kN, 156.6 kN, and 158.2 kN, with an average of 157.9 kN, exceeding the standard by 1.93 kN. Metallography of the rejected pieces revealed localized overheating. Thermal fatigue performance: average thermal cycle life 4620 cycles, maximum crack length 0.22 mm.

[0060] Example 3: Five specimens were prepared in this example, and all were subjected to tensile tests according to the standard. The breaking loads were 41.8 kN, 42.3 kN, 41.5 kN, 42.1 kN, and 42.6 kN, with an average of 42.06 kN, which is 0.7 kN higher than the standard. The fracture occurred in the base material in all cases. Thermal fatigue performance: The average thermal cycle life was 4920 cycles, and the maximum crack length was 0.16 mm.

[0061] X-ray flaw detection of 5 specimens in Comparative Example 1 showed that 3 specimens had cracks and porosity. In the tensile test, all specimens fractured at the weld or heat-affected zone. The failure loads of the five specimens were 68.6 kN, 69.3 kN, 67.2 kN, 68.5 kN, and 70.9 kN, with an average of 68.9 kN, which is 4.86 kN lower than the standard. Thermal fatigue performance: average thermal cycle life 2150 cycles, maximum crack length 0.68 mm.

[0062] Comparative Example 2: X-ray flaw detection revealed grade 2-3 shrinkage porosity in the plate-to-tube transition area. All five tensile tests resulted in fracture in this area, with failure loads of 65.8 kN, 67.9 kN, 68.5 kN, 67.6 kN, and 66.2 kN, respectively, with an average of 67.2 kN, lower than the standard of 6.56 kN. Thermal fatigue resistance: average thermal cycle life 1850 cycles, maximum crack length 0.75 mm.

[0063] Comparative Example 3: Of the 5 samples, 4 were found to be non-welded during flaw detection. All fractured at the weld during tensile testing, with failure loads of 70.6kN, 73.9kN, 72.8kN, 71.5kN, and 73.1kN respectively, and an average of 72.38kN, which is 1.38kN lower than the standard. Thermal fatigue performance: average thermal cycle life 4260 cycles, maximum crack length 0.58mm.

[0064] Comparative Example 4: Inspection of 5 pieces revealed 3 pieces with localized incomplete welding. During tensile testing, 3 pieces fractured at the weld seam, and 2 pieces fractured on the conductor side but with low loads. The breaking loads were 69.8 kN, 70.2 kN, 72.6 kN, 70.8 kN, and 68.9 kN, respectively, with an average of 70.46 kN, which is 3.3 kN lower than the standard. Thermal fatigue performance: average thermal cycle life 3680 cycles, maximum crack length 0.45 mm.

[0065] Comparative Example 5: In the tensile test, 3 pieces fractured at the weld, and 2 pieces fractured at the conductor side but with low loads. The breaking loads were 72.5 kN, 70.1 kN, 73.2 kN, 73.4 kN, and 71.9 kN, respectively, with an average of 72.22 kN, which is 1.54 kN lower than the standard. Metallographic examination showed residual oxide film streaks in the weld area with relatively coarse grains. Thermal fatigue resistance: average thermal cycle life 4120 cycles, maximum crack length 0.42 mm.

[0066] Performance Summary Table Table 1 Summary of performance test data for each embodiment and comparative example

[0067] Comprehensive analysis of test results: Using the tensile strength of 1050A pure aluminum at 60MPa as a benchmark, the pass standard was calculated based on 95% of the theoretical tensile strength of the aluminum tube. The average failure load of Examples 1, 2, and 3 of this invention all exceeded the corresponding standard value, and the fracture location 100% avoided the weld (fracture at the aluminum tube or base material). This strongly demonstrates that, under the combined effect of pulse slag removal and precision end-face machining, the forged fine-grained structure strength obtained in the weld zone exceeds the gripping force of the aluminum tube body or the wire crimping point. The tensile loads of Comparative Example 1 (TIG argon arc welding) and Comparative Example 2 (casting) were only 68.9kN and 67.2kN respectively, lower than the pass standard (73.76kN), and all fractured in the weld / transition zone due to welding hot cracks, porosity, or casting shrinkage, indicating severely insufficient strength.

[0068] Comparative Example 3 (pre-processed but not machined, with rough and non-parallel end faces) had a load lower than the standard value, proving that high-precision end face pre-processing is a prerequisite for friction welding quality. Comparative Example 4 (slag removal pulse eliminated, upsetting pressure reduced) and Comparative Example 5 (pulse slag removal eliminated) had loads of 70.46kN and 72.22kN respectively, slightly lower than the qualified standard of 73.76kN. Furthermore, post-weld flaw detection revealed oxide film residue and incomplete welding, proving that pulse slag removal technology is the key guarantee for solving the problem of oxide film removal in 1050A soft aluminum.

[0069] Under testing in a self-restrained thermal fatigue testing machine (alternating cycles at room temperature and 350°C), the weld zone of this invention achieved an average thermal cycle life of 4620-4920 cycles, with a maximum crack length of only 0.16-0.22 mm, significantly better than Comparative Examples 1-5 (cycle life 1850-4260 cycles, crack length 0.42-0.75 mm). In particular, Comparative Example 2 (casting) was prone to macroscopic cracks under thermal stress due to internal shrinkage porosity, resulting in a cycle life of less than 1900 cycles; Comparative Example 1 (TIG weld) had only 2150 cycles due to porosity and thermal cracks in the weld zone. The comparison shows that this invention completely eliminates oxide film inclusions and incomplete welding defects through pulse slag removal, resulting in a dense forged structure in the weld zone, effectively resisting fatigue cracking caused by alternating thermal stress. Furthermore, Example 1 exhibited a higher load than the standard, demonstrating extremely strong process robustness and fully meeting the requirements for high-reliability wire clamps in industrial mass production.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A friction welding manufacturing method for a compression-type equipment clamp, characterized in that, Includes the following steps: Step 1: Provide a T-shaped blank (1), wherein the welding boss end face (2) of the T-shaped blank (1) is a plane; pre-treat the welding boss end face (2) and the end face of the aluminum tube (3); Step 2: The pre-treated T-shaped blank (1) and the aluminum tube (3) are clamped in a friction welding machine, and the aluminum tube (3) and the T-shaped blank (1) are rotated relative to each other. The T-shaped blank (1) and the aluminum tube (3) are welded together in sequence through the friction preheating stage, the stable friction stage and the upsetting stage. Step 3: Remove the weld spatter (4) extruded from the welding area to obtain the compression type equipment clamp.

2. The manufacturing method according to claim 1, characterized in that: In step one, the pretreatment includes machining the end face (2) of the welding boss and the end face of the aluminum tube (3) to make their surfaces flat and the roughness Ra is 3.2-6.3μm, and to ensure that the two end faces are parallel; then degreasing and cleaning are performed.

3. The manufacturing method according to claim 2, characterized in that: The parallelism of the two end faces is no greater than 0.05mm.

4. The manufacturing method according to claim 1, characterized in that: In step two, the process parameters for the friction preheating stage are: spindle speed of 800-2000 rpm, first-level friction pressure of 10-30 MPa, and duration of 2-8 seconds. The process parameters for the stable friction stage are as follows: maintain the rotation speed, apply a secondary friction pressure of 25-60 MPa for 3-12 seconds, and control the interface temperature at 0.6-0.9 times the solidus temperature of the aluminum alloy material to be welded. The solidus temperature refers to the critical temperature at which the aluminum alloy changes from a solid state to a liquid state. The process parameters for the upsetting stage are as follows: brake the spindle, apply upsetting pressure of 85-150MPa within 0.5s, and hold the pressure for 3-10s.

5. The manufacturing method according to claim 4, characterized in that: Between the friction preheating stage and the stable friction stage, there is also a slag discharge pulse stage to break up and extrude the interfacial oxide film.

6. The manufacturing method according to claim 5, characterized in that: During the slag discharge pulse phase, the pressure rises to 50-70 MPa in 0.3-1.5 seconds and returns to the secondary friction pressure in 0.2-0.8 seconds, with the number of repetitions being 1-3 times.

7. The manufacturing method according to claim 1, characterized in that: The T-shaped blank (1) is made by cutting extruded aluminum profiles, with a plate thickness of 10-40mm and a width of 80-300mm; the aluminum tube (3) is a seamless extruded aluminum tube with an outer diameter of 30-100mm.

8. The manufacturing method according to claim 1, characterized in that: During friction welding, the axial shortening of the spindle and the welding interface temperature are monitored in real time. When the axial shortening falls within the preset target range and the interface temperature curve deviates from the standard curve by ≤±10℃, the welding is deemed qualified; otherwise, an automatic alarm is triggered and the weld is rejected. The preset target range for axial shortening is determined based on the outer diameter of the aluminum tube and is 3-15mm. The interface temperature standard curve is a temperature-time reference curve obtained through multiple tests of the same material and specifications under the same process parameters.

9. The manufacturing method according to any one of claims 1 to 8, characterized in that: The T-shaped blank (1) and the aluminum tube (3) are both made of 1050A pure aluminum.

10. A compression-type equipment clamp, characterized in that: The product is manufactured by any one of claims 1 to 9, and is formed by welding a T-shaped blank (1) and an aluminum tube (3). The welding area between the T-shaped blank (1) and the aluminum tube (3) is free of cracks and pores, and the room temperature tensile strength of the welding area is not less than 95% of that of the base material.

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