Bimetal welding method and welding device

Abstract

The bimetallic welding method comprises the steps that a plurality of annular grooves are formed in the surface, welded to a copper plate, of a steel base body, and a plurality of annular protrusions are formed on the surface of the steel base body; the steel substrate is placed on the lower electrode, and the copper plate is placed on the annular protrusion on the surface of the steel substrate; an upper electrode is placed on the copper plate, and set pressure is applied to the upper electrode; after the set pressure is reached, electrifying the upper electrode, and heating the annular bulge on the surface of the steel substrate to a molten or plastic state according to the generated resistance heat, so that the annular bulge is combined with the copper plate to finish welding; according to the double-metal welding method, the high-pressure energy storage welding process is used for replacing an original silver welding process using precious metal such as silver, and the cost is greatly reduced. Brass is used for welding, the welding method can be applied to the working condition higher than 400 bar, the abrasion resistance is high, and the product performance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of bimetal welding, and in particular to a bimetal welding method and a welding device. Background Art

[0002] Bimetallic shoes are made of alloy steel and copper, and are generally welded or cast to achieve the purpose of combining two different materials. The current mainstream welding processes are brazing and diffusion welding. Brazing requires the use of precious metals with low melting points such as silver, which is costly. Diffusion welding uses bronze, which has poor wear resistance and is not suitable for working conditions with pressures above 400 bar. The sintering process also uses bronze, which has poor wear resistance.

[0003] Existing brazing requires the use of precious metals with low melting points such as silver as brazing materials, which is expensive. Diffusion welding uses bronze, which has poor wear resistance and is not suitable for working conditions with pressures higher than 400 bar. The sintering process increases the density of the composite material through rolling, but the copper alloy layer of the prepared bimetallic sheet still has pores, which will reduce the bearing capacity of the copper alloy layer. In addition, the sintering process also uses bronze, which has poor wear resistance. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a bimetallic welding method and a welding device, which utilize the high-voltage energy storage principle to solve the current problems of high cost, poor wear resistance and low working conditions of slipper welding.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a bimetallic welding method is provided, comprising:

[0007] A plurality of annular grooves are formed on the surface where the steel substrate and the copper plate are welded, so that a plurality of annular protrusions are formed on the surface of the steel substrate;

[0008] placing a steel substrate on the lower electrode and placing a copper plate on the annular protrusion on the surface of the steel substrate;

[0009] The upper electrode is placed on the copper plate and a set pressure is applied to the upper electrode;

[0010] After reaching the set pressure, the upper electrode is energized, and the annular protrusion on the surface of the steel substrate is heated to a molten or plastic state according to the generated resistance heat, so that it is combined with the copper plate to complete the welding.

[0011] In some embodiments of the present invention, the upper electrode and the lower electrode are both made of chromium-zirconium-copper alloy, the structural shape of the upper electrode matches the structural shape of the copper plate, and the structural shape of the lower electrode matches the structural shape of the steel substrate.

[0012] In some embodiments of the present invention, the pressure applied to the upper electrode is 40-60 kN and the energy is 10-20 kJ.

[0013] In some embodiments of the present invention, the pressure is preferably 50 kN and the energy is preferably 12 kJ.

[0014] In some embodiments of the present invention, the number of the annular protrusions is 4-6, and the height of the annular protrusions is 0.4-0.8 mm.

[0015] In some embodiments of the present invention, the top of the annular protrusion is pointed, and the angles of the two sides of the tip are 40°-110°.

[0016] In some embodiments of the present invention, the welding length between the steel substrate and the copper plate is controlled at 1.51±10% mm.

[0017] In the second aspect of the present invention, a bimetallic welding device is provided, comprising an upper electrode, a lower electrode, a pressure head and an electric fusion energy storage welder; the upper electrode is arranged above the copper plate, the pressure head is arranged above the upper electrode, the upper electrode is electrically connected to the electric fusion energy storage welder, and the pulse current generated by the capacitor energy storage welder is transmitted to the contact point between the copper plate and the steel substrate through the upper electrode; the lower electrode is arranged below the steel substrate.

[0018] In some embodiments of the present invention, the lower electrode is provided with a base mounting hole, a steel substrate mating surface and a positioning column mounting hole, the lower electrode is fixed to the base through the base mounting hole, the steel substrate is placed on the steel substrate mating surface, and a positioning guide column is installed in the positioning column mounting hole.

[0019] In some embodiments of the present invention, the manufacturing accuracy of parallelism between the contact surface of the upper electrode plate and the copper plate and the plane of the pressure head is controlled within 0.02, and the roughness is controlled within Ra0.8.

[0020] One or more technical solutions of the present invention have the following beneficial effects:

[0021] (1) The bimetallic welding method provided by the present invention uses a high-pressure energy storage welding process to replace the original silver welding process using precious metals such as silver, which greatly reduces the cost. The present invention uses brass for welding, which can be applied to working conditions above 400 bar, has high wear resistance, and improves product performance.

[0022] (2) The bimetallic welding method provided by the present invention realizes the welding of copper-steel bimetal by projection welding by setting an annular protrusion on the surface of the steel substrate; the welding surface has basically no weld marks, the surface quality is good, the deformation is small, and no grinding is required, which reduces the processing steps and improves production efficiency; at the same time, the welding pressure, energy, and time of this scheme can be adjusted in real time, and it has good flexibility and versatility.

[0023] (3) The bimetallic welding device provided by the present invention is provided with an upper electrode and a lower electrode, and both the upper electrode and the lower electrode are detachable, which is convenient for loading and unloading products and changing models, and the welding quality and stability are good.

[0024] (4) The present invention establishes a welding quality evaluation method that can qualitatively analyze the quality of welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a welding principle diagram of the bimetal welding method of Example 1;

[0026] Figure 2 Schematic diagram of current flow distribution in the welding method of Example 1;

[0027] Figure 3 This is a schematic diagram of the steel base convex ring structure in Example 1;

[0028] Figure 4 Schematic diagram of various convex ring shapes in Example 1;

[0029] Figure 5 It is a schematic diagram of the convex ring structure of the sliding shoe steel base in Example 1;

[0030] Figure 6 This is a physical picture of the welded copper-steel joint surface of Example 1;

[0031] Figure 7 The copper-steel welding contact length of Example 1;

[0032] Figure 8 It is a structural schematic diagram of a bimetallic welding device of Example 2;

[0033] Fig. 9 Schematic diagram of the structure of the upper electrode in Example 2;

[0034] Fig.10 Schematic diagram of the structure of the lower electrode in Example 2.

[0035] In the figure: 1, copper plate; 2, steel substrate; 201, annular protrusion; 3, current; 4, positioning column; 5, upper electrode; 501, guide hole; 502, electrode mounting hole; 6, lower electrode; 601, base mounting hole; 602, steel substrate matching surface; 603, positioning column mounting hole; DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] Explanation of relevant terms:

[0038] Bimetallic slipper: A slipper with a base of alloy steel and a working surface of copper. It has the strength of alloy steel and retains the wear resistance of copper.

[0039] Example 1

[0040] In view of the problems existing in the existing bimetallic welding process, the present invention provides a bimetallic welding method, comprising:

[0041] A plurality of annular grooves are formed on the surface where the steel substrate and the copper plate are welded, so that a plurality of annular protrusions are formed on the surface of the steel substrate;

[0042] placing a steel substrate on the lower electrode and placing a copper plate on the annular protrusion on the surface of the steel substrate;

[0043] The upper electrode is placed on the copper plate and a set pressure is applied to the upper electrode;

[0044] After reaching the set pressure, the upper electrode is energized, and the annular protrusion on the surface of the steel substrate is heated to a molten or plastic state according to the generated resistance heat, so that it is combined with the copper plate to complete the welding.

[0045] like Figure 1 and Figure 2 As shown, the welding principle of the bimetallic welding method provided in this embodiment is that the substrate is alloy steel, which is pressed by electrodes and pressure is applied, and an electric current is passed through it. The resistance heat generated by the current 3 flowing through the contact surface of the workpiece and the adjacent area is used to heat it to a molten or plastic state, so that it can be combined with the copper plate.

[0046] In this embodiment, the upper electrode and the lower electrode are both made of chromium-zirconium-copper alloy (CuCrZr), the structural shape of the upper electrode matches the structural shape of the copper plate, and the structural shape of the lower electrode matches the structural shape of the steel substrate.

[0047] In this embodiment, the pressure applied to the upper electrode is 40-80kN, and the energy is 10-20kJ. Preferably, the pressure is 50kN, and the energy is 12kJ. Other parameters are not limited. It has been verified that: the welding energy is low, which is insufficient to form an effective nugget, and the welding cannot be completed. The welding energy is insufficient, and the effective nugget area is small, resulting in a small bonding force. Relative to the welding energy, the pressure is too large, and the convex point is pressed too early, resulting in an increase in the contact area, a decrease in the current density, and the loss of the projection welding effect. Therefore, the final welding parameters are designed to be 80kN pressure and 20kJ energy, which is conducive to the formation of effective fusion and improves the welding quality.

[0048] In this embodiment, if Figure 3 and Figure 4As shown, the number of the annular protrusions is 4-6, the height of the annular protrusion is 0.4-0.8 mm, the top of the annular protrusion is pointed, and the angles of the two sides of the tip are 40°-110°.

[0049] At present, this welding process has been successfully applied to the welding of HPV75 sliding shoes. The application process is as follows:

[0050] 1. Steel base shape design. The steel base shape is designed with 4 convex rings, the height of the convex ring is 0.5, and the structure of the convex ring and the groove is as follows: Figure 5 shown.

[0051] 2. Design of upper and lower electrode tooling: Design the upper and lower electrodes according to the structural dimensions of the sliding shoe steel substrate and the copper plate.

[0052] 3. Welding parameter design verification: The optimal parameters are obtained based on the DOE test, with a pressure of 50KN and an energy of 12KJ.

[0053] Specifically, the steel substrate and the copper plate are placed above the lower copper electrode, and the upper copper electrode is pressed down. When the set pressure is reached, the upper copper electrode is energized to achieve welding. The centering pin ensures that the steel substrate and the copper plate are placed in the middle, which plays a positioning and guiding role. The current conducted by the upper copper electrode passes through the copper plate to the steel substrate, and then to the lower copper electrode. The steel substrate is melted by the large current, and the downward pressure of the equipment is used to fuse the steel substrate and the copper plate together to achieve bimetallic welding.

[0054] 4. Welding quality evaluation: After cutting open, use a microscope to observe whether there are gaps, collapses, cracks, etc. on the copper-steel joint surface. Figure 6 . Measure whether the copper-steel contact length is uniform, see Figure 7 The theoretical value of welding contact length is 1.51±10%mm, and the actual measured value is 1.37~1.60mm, which meets the quality standards.

[0055] The bimetallic welding method provided in this embodiment realizes the welding of alloy steel and pure copper by using the pulsed high current generated by the capacitor energy storage welding machine. The entire welding process is completed within 3‰-10‰ seconds, leaving the surface substantially free of welding marks, without the need for grinding, reducing the processing steps, and improving production efficiency. It can not only save the use of rare metals, but also ensure working under high-voltage conditions. At the same time, the welding surface quality is good and the deformation is small.

[0056] Example 2

[0057] In a typical embodiment of the present invention, a bimetallic welding device is provided, such as Figure 8-10As shown, it includes an upper electrode 5, a lower electrode 6, a pressure head and an electric melting energy storage welding machine; the upper electrode 5 is arranged above the copper plate 1, the pressure head is arranged above the upper electrode 5, the upper electrode 5 is electrically connected to the electric melting energy storage welding machine, and the pulse current generated by the capacitor energy storage welding machine is transmitted to the contact point between the copper plate 1 and the steel substrate through the upper electrode 5; the lower electrode 6 is arranged below the steel substrate 2.

[0058] like Fig. 9 As shown, the upper electrode 5 is provided with a guide hole 501 and an electrode mounting hole 502. Fig.10 As shown, the lower electrode 6 is provided with a base mounting hole 601, a steel substrate matching surface 602 and a positioning column mounting hole 603, the steel substrate 2 is placed on the steel substrate matching surface 602, the guide hole 501 of the upper electrode corresponds to the positioning column mounting hole 603 of the lower electrode 6, and the positioning guide column 4 is installed in the positioning column mounting hole 603, and the steel substrate is positioned by the provided positioning column to avoid displacement of the steel substrate during welding.

[0059] Furthermore, the manufacturing accuracy of parallelism between the contact surface of the upper electrode plate and the copper plate and the plane of the pressure head is controlled within 0.02mm to ensure that the welding pressure is uniform and stable, and the roughness is controlled within Ra0.8. At the same time, the wear limit length is specified, and the tooling is scrapped after exceeding the wear length.

[0060] The bimetallic welding device provided in this embodiment is provided with an upper electrode and a lower electrode, and both the upper electrode and the lower electrode are detachable, which is convenient for loading and unloading products and changing models, and has good welding quality and stability.

[0061] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A bimetallic welding method, characterized in that: include: A plurality of annular grooves are formed on the surface where the steel substrate and the copper plate are welded, so that a plurality of annular protrusions are formed on the surface of the steel substrate; placing a steel substrate on the lower electrode and placing a copper plate on the annular protrusion on the surface of the steel substrate; The upper electrode is placed on the copper plate and a set pressure is applied to the upper electrode; After reaching the set pressure, the upper electrode is energized, and the annular protrusion on the surface of the steel substrate is heated to a molten or plastic state according to the generated resistance heat, so that it is combined with the copper plate to complete the welding.

2. The bimetallic welding method according to claim 1, characterized in that: The upper electrode and the lower electrode are both made of chromium-zirconium-copper alloy. The structural shape of the upper electrode matches the structural shape of the copper plate, and the structural shape of the lower electrode matches the structural shape of the steel substrate.

3. The bimetallic welding method according to claim 1, characterized in that: The pressure applied to the upper electrode is 40-60 kN and the energy is 10-20 kJ.

4. The bimetallic welding method according to claim 3, characterized in that: The pressure is preferably 50 kN and the energy is preferably 12 kJ.

5. The bimetallic welding method according to claim 1, characterized in that: The number of the annular protrusions is 4-6, and the height of the annular protrusions is 0.4-0.8 mm.

6. The bimetallic welding method according to claim 1, characterized in that: The top of the annular protrusion is pointed, and the angles of the two sides of the tip are 40°-110°.

7. The bimetallic welding method according to claim 1, characterized in that: The welding length between the steel substrate and the copper plate is controlled at 1.51±10% mm.

8. A bimetallic welding device, used to implement the bimetallic welding method according to any one of claims 1 to 7, characterized in that: It includes an upper electrode, a lower electrode, a pressure head and an electric melting energy storage welding machine; the upper electrode is arranged above the copper plate, the pressure head is arranged above the upper electrode, the upper electrode is electrically connected to the electric melting energy storage welding machine, and the pulse current generated by the capacitor energy storage welding machine is transmitted to the contact point between the copper plate and the steel substrate through the upper electrode; the lower electrode is arranged below the steel substrate.

9. The bimetallic welding device according to claim 8, characterized in that: The lower electrode is provided with a base mounting hole, a steel substrate matching surface and a positioning column mounting hole. The lower electrode is fixed to the base through the base mounting hole. The steel substrate is placed on the steel substrate matching surface. The positioning guide column is installed in the positioning column mounting hole.

10. The bimetallic welding device according to claim 8, characterized in that: The manufacturing accuracy of parallelism between the contact surface of the upper electrode plate and the copper plate and the plane of the pressure head is controlled within 0.02mm, and the roughness is controlled within Ra0.8.

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