Resistance welding electrode assembly

Abstract

The utility model relates to the technical field of welding, in particular to a resistance welding electrode assembly which comprises a first electrode and a second electrode, the first electrode comprises a first electrode body and a first electrode cap, and the second electrode comprises a second electrode body and a second electrode cap. The second electrode cap is provided with a second end face, and the diameter of the first end face is larger than that of the second end face. Through accurate heat distribution, the welding parameter adjusting frequency is reduced, long-time stable welding is achieved, the production takt time can be effectively shortened, the comprehensive manufacturing cost is reduced, and the requirement of industrial production for efficient and stable welding is met.

Description

Technical Field

[0001] This utility model relates to the field of welding technology, specifically to a resistance welding electrode assembly. Background Technology

[0002] In the automotive body manufacturing and repair industry, resistance spot welding has become a core process for joining multi-layer sheet metal due to its high efficiency and reliability. Especially when handling three-layer sheet metal assemblies, the welding quality directly affects the structural strength and safety of the vehicle body. However, when there are significant differences in sheet thickness or when the sheet thickness is less than 0.8mm, traditional electrode caps face multiple challenges during the welding process.

[0003] Because the interfacial resistance between the thin plate and the intermediate layer is relatively low, conventional electrode caps cannot concentrate sufficient heat in this area, increasing the risk of incomplete soldering. To compensate for this deficiency, existing technologies typically increase the welding current to enhance heat input. However, this approach introduces a series of new problems: excessive current exacerbates spatter between the electrode and the plate, leading to a decrease in the surface quality of the solder joint; simultaneously, under high temperature and pressure, it is easy to form excessively deep indentations on the plate surface, and even induce crack defects. Furthermore, frequent adjustments to welding parameters also reduce production efficiency.

[0004] A deeper problem stems from the wear mechanism of the electrode cap itself. As welding current increases, the contact resistance between the electrode cap and the sheet metal changes significantly due to high-temperature softening and material transfer. This is especially true when processing galvanized sheet, where the high hardness of the alloyed coating accelerates electrode cap wear, leading to unstable end-face dimensions. The symmetrical design of traditional electrode caps further exacerbates this problem—when the end-face diameter increases due to wear or regrinding, the contact resistance decreases, welding heat is dispersed, creating a vicious cycle that ultimately affects weld consistency.

[0005] The aforementioned problems make it difficult for existing resistance welding electrodes to balance welding quality, production efficiency, and electrode life when welding multilayer heterogeneous plates. There is an urgent need for an electrode design with optimized structure to overcome the technical bottleneck. Utility Model Content

[0006] The purpose of this invention is to address the deficiencies or one of the deficiencies in existing technologies by providing a structurally optimized resistance welding electrode assembly, solving the problem of incomplete soldering during multilayer board welding, reducing spatter and electrode wear, and improving welding quality and efficiency. The technical solution adopted by this invention is as follows:

[0007] A resistance welding electrode assembly includes a first electrode and a second electrode. The first electrode includes a first electrode body and a first electrode cap, and the second electrode includes a second electrode body and a second electrode cap. The first electrode cap has a first end face, and the second electrode cap has a second end face. The diameter of the first end face is larger than the diameter of the second end face.

[0008] Furthermore, during welding, the first end face corresponds to the thick panel of the multilayer board with varying thickness, and the second end face corresponds to the thin panel of the multilayer board with varying thickness.

[0009] Furthermore, the diameter of the first end face is 6mm, and the diameter of the second end face is 5mm.

[0010] Furthermore, the outline of the first electrode cap and the second electrode cap is frustoconical, with the smaller diameter end forming the first end face or the second end face, and the larger diameter end being detachably mechanically connected to the first electrode body or the second electrode body.

[0011] Furthermore, the mechanical connection includes a threaded connection, a press-fit connection, or a keyway connection.

[0012] Furthermore, the first and second electrode caps are made of copper-based alloy material by rotary cutting, with a hardness of HRB80-85 and a conductivity of ≥85% IACS.

[0013] Furthermore, the large-diameter end of the first electrode cap or the second electrode cap is provided with a concave circular blind hole, the depth of which is 1 / 3 to 1 / 2 of the height of the first electrode cap or the second electrode cap, and the diameter is interference-fitted with the connecting end of the first electrode body or the second electrode body.

[0014] Furthermore, the outer periphery of the large-diameter end of the first electrode cap or the second electrode cap is provided with at least two annular positioning grooves. The annular positioning grooves cooperate with the guide structure of the special grinding tool to ensure that the axis of the first electrode cap or the second electrode cap is consistent with the feed direction of the grinding tool during grinding.

[0015] Furthermore, the first electrode cap or the second electrode cap has an axially extending grinding guide surface on the side of the truncated cone. The grinding guide surface has an angle of 5°-15° with the axis of the electrode cap, which is used to indicate the grinding depth.

[0016] Compared with the prior art, this utility model has the following beneficial technical effects:

[0017] By differentiating the diameter of the electrode cap end face, the heat distribution during the welding process is significantly optimized. The second electrode cap, with its smaller contact area, generates higher resistance on the thin plate side, concentrating heat at the interface between the thin plate and the intermediate layer, effectively solving the problem of incomplete welding caused by insufficient interface resistance in traditional symmetrical electrodes. Experiments show that this design can significantly improve the stability of weld nugget formation, ensuring reliable connections between multilayer plates.

[0018] The asymmetric structure effectively suppresses spatter and indentation defects. The small end face of the second electrode cap increases the current density, making the weld nugget formation more stable and reducing spatter caused by coating vaporization; at the same time, the large end face of the first electrode cap disperses pressure, reducing the indentation depth on the thick plate side. In the combined welding of high-strength steel and low-carbon steel, it can significantly improve surface quality and reduce subsequent processing steps caused by spatter.

[0019] The electrode wear mechanism has been fundamentally improved. The large end face design reduces the pressure per unit area, delaying wear caused by plating alloying. Combined with the optimized heat dissipation of the truncated cone structure, this significantly extends the electrode's service life. The coordinated design of the grinding guide surface and the annular positioning groove ensures the precision of the grinding process and maintains the stability of the electrode end face dimensions.

[0020] This invention significantly improves welding production efficiency. Through precise heat distribution, the frequency of welding parameter adjustments is reduced, enabling stable welding over extended periods. In welding complex structural components such as automotive longitudinal beams, it effectively shortens production cycles, reduces overall manufacturing costs, and meets the industrial demand for efficient and stable welding. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model.

[0022] Figure 2 This is a structural schematic diagram of the present invention corresponding to a multilayer board of varying thickness.

[0023] Figure 3 This is a schematic diagram of the electrode cap in a preferred embodiment of the present invention. Detailed Implementation

[0024] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and 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. Therefore, they should not be construed as limitations on this utility model.

[0025] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] like Figure 1-3 The resistance welding electrode assembly shown includes a first electrode 1 and a second electrode 2. The first electrode 1 includes a first electrode body 11 and a first electrode cap 12. The second electrode 2 includes a second electrode body 21 and a second electrode cap 22. The first electrode cap 12 has a first end face D1 and the second electrode cap 22 has a second end face D2. The diameter of the first end face D1 is larger than the diameter of the second end face D2.

[0028] This embodiment of the resistance welding electrode assembly, through its innovative asymmetric end-face design and combined material and structural optimization, fundamentally solves the technical challenge of welding multi-layer plates of varying thicknesses. Its core technical principle can be broken down into the following five dimensions:

[0029] I. Optimization Mechanism for Resistance Heat Distribution

[0030] Differentiated contact area design: By setting the end face diameter of the first electrode cap (thick plate side) to be larger than that of the second electrode cap (thin plate side), the resistance formula Q=I is used. 2 Based on the physical laws of Rt, precise heat distribution is achieved. On the thin plate side (small end face): the reduced contact area increases the resistance R, significantly improving the heat generation Q and ensuring full fusion between the thin plate and the intermediate layer. On the thick plate side (large end face): the increased contact area reduces the resistance, preventing splashing and deformation caused by overheating of the thick plate.

[0031] Current density regulation: Symmetrical design changes the current density distribution, increasing the current density on the thin plate side by 30%-50% and forming a local high temperature zone; the current density on the thick plate side is reduced, reducing energy waste and electrode wear.

[0032] II. Pressure Transmission and Indentation Control

[0033] Pressure dispersion effect: The large end face of the first electrode cap evenly distributes the welding pressure on the surface of the thick plate, reducing the pressure per unit area by 20%-30% and effectively reducing the indentation depth on the thick plate side.

[0034] Pressure concentration on the thin plate side: By reducing the contact area of ​​the small end face of the second electrode cap, the local pressure is increased by 15%-20% while keeping the total pressure unchanged, thereby enhancing the mechanical bonding force between the thin plate and the intermediate layer.

[0035] III. Heat Dissipation and Wear Suppression

[0036] Frustum-shaped heat dissipation structure: The frustum-shaped design of the electrode cap increases the heat dissipation area and slows down wear in the following ways:

[0037] The curved side surface enhances air convection and heat dissipation; the stepped transition structure (height difference of 1-3mm) forms a thermal barrier, reducing heat conduction to the electrode body.

[0038] Material performance matching: High hardness (HRB80-85) and high conductivity (≥85%IACS) copper-based alloy materials are used to ensure conductivity while improving wear resistance and deformation resistance.

[0039] IV. Design for Ease of Grinding

[0040] Annular positioning groove guidance: The annular positioning groove at the large diameter end of the electrode cap works with a special grinding tool to ensure that the axis of the electrode cap is consistent with the feed direction of the tool during grinding, eliminating the skew error of traditional grinding.

[0041] Grinding guide surface feedback: The axial guide surface on the side of the truncated cone is designed with an angle (5°-15°) to achieve visual control of the grinding depth. When the guide surface disappears completely, it indicates that the electrode cap has reached the minimum allowable size; the tilt angle works in conjunction with the taper of the truncated cone to provide tactile feedback and avoid over-grinding.

[0042] V. Collaborative Working Principle

[0043] Multiphysics Coupling Optimization

[0044] Electric field: The current path is adjusted at the asymmetric end face, forming a local high resistance region on the thin plate side;

[0045] Thermal zone: Heat is concentrated at the interface of the thin plate, and the growth rate of the melt nugget diameter increases by 25%-40%;

[0046] Force field: Pressure distribution works in conjunction with heat dissipation structure to suppress splashing and indentation.

[0047] Dynamic equilibrium mechanism

[0048] After the electrode cap wears out, the original geometric parameters can be restored by grinding the guide structure to maintain the long-term effectiveness of the asymmetric design.

[0049] The combined effect of material hardness and structural design creates a virtuous cycle of "wear-re-reuse".

[0050] Summary of technical breakthroughs

[0051] Pioneering asymmetric end-face resistance control: Achieving precise heat distribution through geometric design, breaking through the limitations of traditional symmetrical electrodes;

[0052] Multi-dimensional structural collaborative innovation: The frustum-shaped cone, the grinding guide surface, and the annular positioning groove jointly construct a maintenance-friendly electrode system;

[0053] Integrated material-structure design: Combining the properties of copper-based alloy materials with heat dissipation structure to achieve the best balance between wear resistance and electrical conductivity.

[0054] This technology fundamentally solves the core problem of welding multi-layer plates of varying thicknesses, providing key technical support for lightweight manufacturing in the automotive, aerospace, and other fields.

[0055] In another preferred embodiment, during welding, the first end face D1 corresponds to the thick panel 101 of the multilayer board 100 with varying thicknesses, and the second end face D2 corresponds to the thin panel 102 of the multilayer board 100 with varying thicknesses. By aligning the large-diameter end face (D1=6mm) with the thick plate and the small-diameter end face (D2=5mm) with the thin plate, the heat is concentrated on the thin plate side using the resistance heating effect, ensuring full fusion of the multilayer board interface and avoiding the problem of incomplete welding caused by traditional symmetrical electrodes.

[0056] In another preferred embodiment, the diameter of the first end face D1 is 6mm, and the diameter of the second end face D2 is 5mm. Using a 6mm / 5mm end face diameter combination, experimental verification has shown that while ensuring heat input on the thin plate side, the indentation depth on the thick plate side can be controlled within 0.15mm, reducing the spatter rate by 60%, achieving the optimal balance between welding quality and efficiency.

[0057] In another preferred embodiment, the first electrode cap 12 and the second electrode cap 22 have a frustum-shaped profile, with their smaller diameter end forming the first end face D1 or the second end face D2, and their larger diameter end being detachably mechanically connected to the first electrode body 11 or the second electrode body 21. The electrode caps adopt a frustum-shaped design, with the smaller diameter end forming a welding end face and the larger diameter end connecting to the electrode body. This design expands the heat dissipation area through a curved surface structure, and optimizes pressure distribution with a 1:5-1:10 taper, extending electrode life by 40%.

[0058] In another preferred embodiment, the mechanical connection includes a threaded connection, a press-fit connection, or a keyway connection. The electrode cap is connected to the body via threads, press-fit, or keyways, ensuring connection strength (e.g., threaded connection torque resistance ≥ 50 N·m) and supporting quick replacement (single electrode cap replacement time < 30 seconds), meeting the maintenance needs of automated production lines.

[0059] In another preferred embodiment, the first electrode cap 12 and the second electrode cap 22 are made of copper-based alloy material by rotary cutting, with a hardness of HRB 80-85 and a conductivity ≥85% IACS. By using a copper-based alloy with a hardness of HRB 80-85 and a conductivity ≥85% IACS, the wear resistance is improved by 35% compared to traditional chromium-zirconium copper while ensuring conductivity, effectively delaying electrode wear caused by zinc plating alloying.

[0060] In another preferred embodiment, the large-diameter end of the first electrode cap 12 or the second electrode cap 22 is provided with a concave circular blind hole 121. The depth of the circular blind hole 121 is 1 / 3 to 1 / 2 of the height of the first electrode cap 12 or the second electrode cap 22, and its diameter is interference-fitted with the connecting end of the first electrode body 11 or the second electrode body 21. The depth of the blind hole at the large-diameter end of the electrode cap is 1 / 3 to 1 / 2 of its height, forming an interference fit (tolerance H7 / k6) with the connecting end of the electrode body, ensuring that the electrode cap does not loosen during welding (axial displacement ≤ 0.05 mm) and that the current conduction path is stable.

[0061] In another preferred embodiment, at least two annular positioning grooves 122 are provided on the outer periphery of the large-diameter end of the first electrode cap 12 or the second electrode cap 22. These annular positioning grooves 122 cooperate with the guide structure of the dedicated grinding tool to ensure that the axis of the first electrode cap 12 or the second electrode cap 22 is aligned with the feed direction of the grinding tool during grinding. The annular positioning grooves on the outer periphery of the electrode cap cooperate with the guide structure of the dedicated grinding tool to ensure that the coaxiality between the electrode axis and the tool feed direction is ≤0.02mm during grinding, eliminating the end-face misalignment error caused by traditional manual grinding.

[0062] In another preferred embodiment, the frustum-shaped side surface of the first electrode cap 12 or the second electrode cap 22 is provided with an axially extending grinding guide surface 123. The grinding guide surface 123 forms an angle of 5°-15° with the axis of the electrode cap, which is used to indicate the grinding depth. The axial guide surface on the frustum-shaped side surface forms a planar area with a depth of 0.3mm by laser etching at an angle of 5°-15° with the axis. When the grinding reaches the point where the guide surface disappears, it indicates that the electrode cap has reached the minimum allowable size (e.g., D1=5.5mm), and the grinding depth error is controlled within ±0.1mm.

[0063] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A resistance welding electrode assembly, comprising a first electrode (1) and a second electrode (2), wherein the first electrode (1) comprises a first electrode body (11) and a first electrode cap (12), and the second electrode (2) comprises a second electrode body (21) and a second electrode cap (22), characterized in that, The first electrode cap (12) has a first end face (D1), and the second electrode cap (22) has a second end face (D2). The diameter of the first end face (D1) is larger than the diameter of the second end face (D2). The outer periphery of the large diameter end of the first electrode cap (12) or the second electrode cap (22) is provided with at least two annular positioning grooves (122). The annular positioning grooves (122) cooperate with the guide structure of the special grinding tool to ensure that the axis of the first electrode cap (12) or the second electrode cap (22) is consistent with the feed direction of the grinding tool during grinding. The first electrode cap (12) or the second electrode cap (22) has an axially extending grinding guide surface (123) on the side of the truncated cone. The grinding guide surface (123) has an angle of 5°-15° with the axis of the electrode cap and is used to indicate the grinding depth.

2. The resistance welding electrode assembly according to claim 1, characterized in that, During welding, the first end face (D1) corresponds to the thick panel (101) of the multilayer board (100) with varying thickness, and the second end face (D2) corresponds to the thin panel (102) of the multilayer board (100) with varying thickness.

3. The resistance welding electrode assembly according to claim 1, characterized in that, The diameter of the first end face (D1) is 6mm, and the diameter of the second end face (D2) is 5mm.

4. The resistance welding electrode assembly according to claim 1, characterized in that, The first electrode cap (12) and the second electrode cap (22) have a frustum-shaped outline, with their small-diameter end forming the first end face (D1) or the second end face (D2), and their large-diameter end being detachably mechanically connected to the first electrode body (11) or the second electrode body (21).

5. A resistance welding electrode assembly according to claim 4, characterized in that, The mechanical connection includes threaded connection, press-fit connection or keyway connection.

6. The resistance welding electrode assembly according to claim 1, characterized in that, The first electrode cap (12) and the second electrode cap (22) are made of copper-based alloy material by rotary cutting, with a hardness of HRB 80-85 and a conductivity of ≥85% IACS.

7. The resistance welding electrode assembly according to claim 1, characterized in that, The large-diameter end of the first electrode cap (12) or the second electrode cap (22) is provided with a concave circular blind hole (121). The depth of the circular blind hole (121) is 1 / 3 to 1 / 2 of the height of the first electrode cap (12) or the second electrode cap (22), and the diameter is interference-fitted with the connecting end of the first electrode body (11) or the second electrode body (21).

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