A method for resistance brazing a stud to a copper plate

Abstract

The application discloses a stud and copper plate resistance brazing method, and belongs to the technical field of welding. The method overcomes the defects of poor safety and unstable quality of the existing gas heating welding method. The method comprises the following steps: an assembling step, in which filler metal is arranged between the stud and the copper plate at a welding interface; a pressing step, in which the stud and the copper plate are pressed tightly through upper and lower heating blocks; an electric heating step, in which a welding current is applied to generate heat by using contact resistance and material body resistance, the temperature is heated to a temperature above the melting point of the filler metal and below the melting point of the copper plate, and the filler metal is melted; and a cooling step, in which the power supply is stopped, the pressure is kept, the melted filler metal is solidified, and a brazing joint is formed. The application adopts resistance heating, has no open flame, does not need combustible gas, and is high in safety. The welding time is only 1-10 seconds, the efficiency is high, and the method can realize automatic and continuous production, thereby significantly improving the production efficiency. The method only needs electric energy, is low in energy consumption, is accurate in welding temperature control, is sufficient in filler metal filling, and can stably operate in various production environments.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically to a resistance brazing method, particularly suitable for brazing studs to copper plates. Background Technology

[0002] The connection between studs and copper plates is widely used in the electrical, electronic, and refrigeration industries. In existing technologies, the welding of studs and copper plates mostly adopts gas heating welding, using propane and oxygen as fuel, heating the copper plate and stud with a high-temperature flame, and adding solder wire at the joint to make the connection firm.

[0003] However, this existing technology has the following shortcomings:

[0004] 1. Poor safety: The use of open flames poses a fire and explosion hazard, creating safety risks for operators and the production environment.

[0005] 2. Low efficiency: Gas heating is slow, single-point welding takes a long time, and it is difficult to achieve automated continuous production.

[0006] 3. High cost: It requires consumables such as propane, oxygen and solder wire, and needs to be equipped with gas leak detection devices, resulting in high equipment and operating costs.

[0007] 4. Poor quality stability: The flame temperature is difficult to control precisely, which can easily lead to overheating of the base material or insufficient melting of the brazing filler metal, resulting in poor joint quality consistency.

[0008] Therefore, there is an urgent need in this field for a safe, efficient, low-cost method for connecting studs and copper plates with stable joint quality. Summary of the Invention

[0009] The present invention aims to provide a resistance brazing method for studs and copper plates to solve the problems of open flame hazard, low efficiency and high cost of existing gas welding methods.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for resistance brazing a stud to a copper plate includes the following steps:

[0012] Assembly steps: Place the brazing filler metal at the interface between the stud and the copper plate to be soldered;

[0013] Pressurization step: The stud and the copper plate are pressed together by the upper heating block and the lower heating block;

[0014] Electric heating step: Apply welding current, utilize contact resistance and material volume resistance to generate heat, heat to a temperature above the melting point of the brazing filler metal and below the melting point of the copper plate, so that the brazing filler metal melts;

[0015] Cooling step: Stop the power supply, maintain pressure, and allow the molten filler metal to solidify, forming a brazed joint.

[0016] Furthermore, the solder is a soft solder with a melting point lower than that of copper; the soft solder includes tin-based solder, lead-based solder, or zinc-based solder.

[0017] Furthermore, the welding current is a direct current or an alternating pulse current.

[0018] Furthermore, in the pressurization step, the welding pressure is 0.5 MPa-5 MPa.

[0019] Furthermore, in the heating step, the welding time is 1 to 10 seconds.

[0020] Furthermore, in the heating step, the welding temperature is controlled at 300℃-600℃.

[0021] Furthermore, in the heating step, the welding temperature is detected in real time by a temperature sensor, and the welding current and / or welding pressure are adjusted by a controller to maintain the welding temperature within a preset range.

[0022] Furthermore, in the pressurization step, the upper heating block and / or the lower heating block are made of copper alloy or molybdenum alloy.

[0023] Furthermore, in the pressurization step, the welding pressure is provided by a lead screw mechanism driven by a pneumatic cylinder, a hydraulic cylinder, or a servo motor.

[0024] Furthermore, in the cooling step, the pressure is maintained for 0.5 to 3 seconds.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] 1. High safety: It uses resistance heating, which has no open flame and does not require flammable gas, thus eliminating the risk of fire and explosion and eliminating the need for gas leak detection devices.

[0027] 2. High efficiency: Single-point welding time is only 1-10 seconds, and it can be automated for continuous production, significantly improving production efficiency.

[0028] 3. Low cost: It does not require propane, oxygen or solder wire, only electricity, resulting in low energy consumption and significantly reduced material costs.

[0029] 4. High joint quality: The welding temperature is precisely controllable, the heat-affected zone is small, the base material is not overheated, the brazing filler metal is fully filled, and the joint has high strength and good consistency.

[0030] 5. Strong environmental adaptability: It is not limited by ventilation, gas supply and other conditions, and can operate stably in a variety of production environments. Attached Figure Description

[0031] Figure 1 This is a three-dimensional structural diagram of the resistance brazing device according to an embodiment of the present invention.

[0032] Figure 2 This is a front view of the resistance brazing apparatus according to an embodiment of the present invention.

[0033] Figure 3 This is a left-side structural schematic diagram of the resistance brazing apparatus according to an embodiment of the present invention.

[0034] Figure 4 This is a bottom view of the resistance brazing apparatus according to an embodiment of the present invention.

[0035] Figure 5 for Figure 2 A schematic diagram of the AA cross-sectional structure.

[0036] Figure 6 for Figure 4 Schematic diagram of the BB cross-section structure.

[0037] In the diagram: 1. Upper heating block; 2. Stud; 3. Copper plate; 4. Lower heating block. Detailed Implementation

[0038] The following is in conjunction with the appendix Figures 1-6 The present invention will be further described in detail below with specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0039] Example 1

[0040] like Figures 1 to 6 As shown, this embodiment provides a resistance brazing method for studs and copper plates, implemented using the following apparatus:

[0041] The upper heating block 1 is located above the stud 2 to be welded;

[0042] The lower heating block 4 is located below the copper plate 3;

[0043] The power module (not shown in the figure) has its positive and negative terminals connected to the upper heating block 1 and the lower heating block 4, respectively.

[0044] A pressure mechanism (not shown in the figure) is connected to the upper heating block 1 and provides downward welding pressure.

[0045] The specific steps are as follows:

[0046] (1) Assembly steps

[0047] A tin-based solder (Sn-37Pb, melting point approximately 183℃) is placed at the soldering interface between stud 2 and copper plate 3. Copper has a melting point of 1083.4℃, which is much higher than the melting point of the solder.

[0048] (2) Pressurization steps

[0049] The pressurizing mechanism is activated, pressing the stud 2 against the copper plate 3 using the upper heating block 1 and the lower heating block 4. The welding pressure is set to 2 MPa. The upper heating block 1 and the lower heating block 4 are made of copper alloy, which has good electrical and thermal conductivity. The pressurizing mechanism uses a pneumatic cylinder, and the pressure is adjustable.

[0050] (3) Heating with electricity

[0051] The power module is activated, applying a DC welding current. The current flows through the upper heating block 1, stud 2, copper plate 3, and lower heating block 4, generating heat through contact resistance and material volume resistance. A temperature sensor monitors the welding temperature in real time, and the controller adjusts the current based on the temperature signal to maintain the welding temperature at 400℃±10℃. This temperature is higher than the solder melting point (183℃) but much lower than the copper melting point (1083.4℃), ensuring the solder melts fully while the copper base material remains solid. The welding time is 5 seconds.

[0052] (4) Cooling steps

[0053] Turn off the power and maintain a welding pressure of 2 MPa to allow the molten brazing filler metal to solidify under pressure. Hold the pressure for 1 second. After holding the pressure, release the pressure, remove the welded workpiece, and allow the brazing filler metal to fill the joint gap, forming a strong brazed joint.

[0054] Example 2

[0055] Unlike Example 1, in this example:

[0056] Solder filler metal: Zinc-based soft solder (Zn-5Al, melting point approximately 382℃) is used.

[0057] Welding temperature: The controller maintains the welding temperature at 480℃±10℃, which is higher than the melting point of the brazing filler metal (382℃) and lower than the melting point of copper (1083.4℃).

[0058] Welding pressure: set to 1.5 MPa.

[0059] Welding time: Set to 4 seconds.

[0060] Heating block material: The upper heating block 1 and the lower heating block 4 are made of molybdenum alloy, which is suitable for high-temperature welding.

[0061] Pressurization mechanism: A servo motor-driven lead screw mechanism is used to achieve precise pressure control.

[0062] Pressure holding time: 1.5 seconds.

[0063] The remaining steps are the same as in Example 1. This example is suitable for applications requiring high welding temperatures.

[0064] Example 3

[0065] Unlike Example 1, in this example:

[0066] Solder filler metal: Lead-based soft solder (Pb-5Sn, melting point approximately 308℃) is used.

[0067] Welding current: AC pulse current is used, with a pulse frequency of 50Hz.

[0068] Welding temperature: The controller maintains the welding temperature at 420℃±10℃.

[0069] Welding pressure: set to 3 MPa.

[0070] Welding time: Set to 3 seconds.

[0071] Pressure holding time: 0.8 seconds.

[0072] The remaining steps are the same as in Example 1. This example is suitable for applications requiring high welding speeds.

[0073] Comparative example (existing gas welding methods)

[0074] The copper plate and stud are heated using a propane-oxygen flame, and solder wire is added at the connection point. This method poses a safety hazard due to open flame, the single-point welding time is approximately 20-30 seconds, it consumes propane, oxygen, and solder wire, and requires a gas leak detection device. Compared with embodiments 1-3 of this invention, the existing method is inefficient, costly, and unsafe.

[0075] The resistance brazing method for studs to copper plates provided by this invention can be widely used in applications such as electrical connection terminals, grounding studs, and refrigeration pipe fasteners where studs need to be brazed to copper plates. This method requires no special gases or open flames and can be implemented safely, efficiently, and at low cost in conventional production workshops, demonstrating significant industrial practical value.

Claims

1. A method for resistance brazing a stud to a copper plate, characterized in that, Includes the following steps: Assembly steps: Place the brazing filler metal at the interface between the stud and the copper plate to be soldered; Pressurization step: The stud and the copper plate are pressed together by the upper heating block and the lower heating block; Electric heating step: Apply welding current, utilize contact resistance and material volume resistance to generate heat, heat to a temperature above the melting point of the brazing filler metal and below the melting point of the copper plate, so that the brazing filler metal melts; Cooling step: Stop the power supply, maintain pressure, and allow the molten filler metal to solidify, forming a brazed joint.

2. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: The solder is a soft solder with a melting point lower than that of copper; the soft solder includes tin-based solder, lead-based solder, or zinc-based solder.

3. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: The welding current is either direct current or alternating pulse current.

4. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: During the pressurization step, the welding pressure is 0.5 MPa-5 MPa.

5. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: In the heating step, the welding time is 1 to 10 seconds.

6. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: In the heating step, the welding temperature is controlled at 300℃-600℃.

7. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: In the heating step, the welding temperature is detected in real time by a temperature sensor, and the welding current and / or welding pressure are adjusted by a controller to maintain the welding temperature within a preset range.

8. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: In the pressurization step, the upper heating block and / or the lower heating block are made of copper alloy or molybdenum alloy.

9. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: In the pressurization step, the welding pressure is provided by a lead screw mechanism driven by a pneumatic cylinder, a hydraulic cylinder, or a servo motor.

10. The resistance brazing method for studs and copper plates according to claim 1, characterized in that: During the cooling step, the pressure is maintained for 0.5 to 3 seconds.

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