Induction preheating device and preheating method for welding copper alloy annular seam

Abstract

The invention relates to an induction preheating device and method for welding a copper alloy annular seam, the induction preheating device comprises an induction power supply, a cover body, an induction coil, a silicon steel sheet and a positioner, a containing cavity is formed in the cover body, an air inlet hole and an air outlet hole are formed in the containing cavity, the induction coil is located in the containing cavity, and the silicon steel sheet is located in the induction coil. The position changing machine is located below the induction coils, a concave containing groove is formed in the position changing machine, a silicon steel sheet is arranged in the containing groove, the induction coils correspond to the silicon steel sheet and are used for being arranged on the two sides of a welding seam, and the induction coils are electrically connected with the induction power source. By means of the non-contact heating characteristic of electromagnetic induction, compared with traditional overall furnace feeding or flame baking, local heating can be accurately achieved, the heating efficiency is greatly improved, energy consumption is reduced, pollution caused by contact type heating is avoided, and meanwhile the problems that traditional preheating temperature control is poor, and uniformity is insufficient are solved.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and specifically to an induction preheating device and method for welding annular seams of copper alloys. Background Technology

[0002] When traditional MIG welding (Metal Inert Gas Welding) automated equipment is used to weld large copper alloy ring-shaped parts, problems such as poor fusion, porosity, and deformation easily occur during the welding process due to the extremely high thermal conductivity of copper alloys. To address this, traditional processes typically rely on preheating methods such as whole-piece furnace heating or localized flame baking. However, these methods suffer from inaccurate temperature control, high energy consumption, harsh working environments, and poor heating uniformity, and are difficult to integrate precisely with modern automated welding processes. More significantly, existing preheating methods cannot achieve precise temperature control of the preheating area, easily leading to localized overheating or underheating of large copper alloy ring-shaped parts during the heating process, resulting in a deterioration in material properties. Without preheating before welding, the rapid heat transfer of copper alloys causes the welding heat to dissipate quickly, resulting in a sharp increase in the temperature gradient between the weld and the base material, leading to defects such as shallow penetration, incomplete fusion, and discontinuous weld formation. Summary of the Invention

[0003] This invention addresses the existing technical problems by providing an induction preheating device and method for welding annular seams of copper alloys.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: An induction preheating device for welding annular seams of copper alloys includes an induction power supply, a cover, an induction coil, a silicon steel sheet, and a positioner. The cover is provided with a receiving cavity, and the receiving cavity is provided with an air inlet and an air outlet. The induction coil is located in the receiving cavity, and the positioner is located below the induction coil. The positioner is provided with a recessed receiving groove, and the receiving groove is provided with a silicon steel sheet. The induction coil corresponds to the silicon steel sheet and is used to be set on both sides of the weld. The induction coil is electrically connected to the induction power supply.

[0005] Based on the above technical solution, the present invention can be further improved as follows: Preferably, the weld is located within the projection range of the silicon steel sheet.

[0006] Preferably, the distance between the inner edge of the silicon steel sheet and the inner edge of the weld is 20mm-35mm, and the distance between the outer edge of the silicon steel sheet and the outer edge of the weld is also 20mm-35mm.

[0007] Preferably, the distance between the induction coil and the weld is 5mm-10mm.

[0008] Preferably, the cavity is provided with a support plate, and the support plate is provided with a plurality of positioning grooves evenly distributed along the circumference. The induction coil is provided with a plurality of sets accordingly, and the induction coil is located in the positioning groove.

[0009] Preferably, a support frame is fixed on the inner wall of the cover, and the support frame is connected to the support plate; or, a locking block is installed on the cover, an adjusting rod is installed on the locking block, the adjusting rod passes through the cover and is connected to the support plate, and a locking bolt is installed on the side wall of the locking block, the locking bolt being used to lock the adjusting rod.

[0010] Preferably, the weld is located within the projection range of the induction coil, the distance between the inner edge of the induction coil and the inner edge of the weld is 10mm-15mm, and the distance between the outer edge of the induction coil and the outer edge of the weld is 10mm-15mm.

[0011] Preferably, the power of the inductive power supply is 50-80KW, and the current frequency of the inductive power supply is 5-20Hz.

[0012] Preferably, the cover, the support plate, and the positioner are all provided with an alumina ceramic coating.

[0013] This invention also discloses a preheating method for welding annular seams of copper alloys, employing the induction preheating device described above, and comprising the following steps: Preheating preparation: Install all components in place, evacuate the cavity, and then introduce inert gas; Preheating: The induction power supply is started, and the induction coil generates an alternating magnetic field to preheat the weld. The temperature of the preheating area is monitored by an infrared temperature sensor. When the temperature of the preheating area reaches the set value, the induction power supply is stopped. After the weld is completed, flip the workpiece to be welded and repeat the above steps.

[0014] The beneficial effects of this invention are: (1) By taking advantage of the non-contact heating characteristics of electromagnetic induction, this invention can accurately achieve local heating compared with the traditional whole furnace or flame baking, which not only greatly improves heating efficiency and reduces energy consumption, but also avoids pollution caused by contact heating. At the same time, it solves the problems of poor temperature control and insufficient uniformity of traditional preheating, and effectively ensures the preheating quality of copper alloy annular seams.

[0015] (2) The device of the present invention has multiple sets of induction coils connected in parallel, connected in series to an induction power supply, and matched with low-frequency parameters. Combined with the low oxygen environment and the assistance of ceramic coating, it not only achieves uniform and rapid preheating of the annular seam, overcoming the heat loss problem caused by the high thermal conductivity of copper alloy, but also prevents workpiece oxidation and equipment energy loss, thereby improving production efficiency and welding joint stability.

[0016] (3) The heating device of the present invention is detachable and can be flexibly adapted to the double-sided welding requirements of copper alloy annular seams. This not only expands the applicable scenarios of the device, but also ensures the consistency of welding quality on both sides of the annular seam through unified preheating parameters, thus promoting the efficient and refined development of copper alloy annular seam welding manufacturing technology. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of the induction preheating device of the present invention; Figure 2 This is a cross-sectional schematic diagram of the induction preheating device of the present invention; Figure 3 This is a schematic diagram showing the distribution of the induction coils of the present invention; Figure 4 This is a schematic diagram showing the connection between the support plate and the adjusting rod of the present invention; Figure 5 This is a cross-sectional view of the workpieces to be welded (part 1 and part 2) after they have been flipped over according to the present invention. Figure 6 This is a schematic diagram showing the connection between the support plate and the adjusting rod after the two parts to be welded are flipped over according to the present invention.

[0018] The attached diagram is labeled as follows: 1. Induction power supply; 2. Cover; 3. Air inlet; 4. Air outlet; 5. Part to be welded 1; 6. Part to be welded 2; 7. Induction coil; 8. Silicon steel sheet; 9. Positioner; 10. Weld seam; 11. Support plate; 12. Support frame; 13. Clamp; 14. Adjusting rod; 15. Locking block; 16. Locking bolt. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention.

[0021] like Figures 1 to 6 As shown, this invention discloses an induction preheating device for welding annular seams of copper alloys, including an induction power supply 1, a cover 2, an induction coil 7, a silicon steel sheet 8, and a positioner 9. The cover 2 has a receiving cavity. In this embodiment, the part to be welded 5 is a flange. To ensure normal welding of part to be welded 5 and part to be welded 6, two covers 2 are provided. The cover 2 is a semi-cylindrical cover, divided along a longitudinal section, and has matching mating surfaces. In use, the two covers 2 are spliced ​​together to form the receiving cavity; the two covers 2 cooperate with each other through the mating surfaces and are fixed. The two housings 2 form a complete cylindrical cavity. A receiving hole is provided at the center joint of the two housings 2 for the weldment 5 to pass through. The cavity also has an air inlet 3 and an air outlet 4. An induction coil 7 is located inside the cavity, and a positioner 9 is located below it. The positioner 9 has a recessed receiving groove containing a silicon steel sheet 8. The induction coil 7 and the silicon steel sheet 8 are positioned correspondingly and are used to position the coil on both sides of the weld 10 formed by the weldment 5 and the weldment 6. The weld 10 is annular. The induction coil 7 is electrically connected to the induction power supply 1. The weldment 5 and the weldment 6 are made of high-resistivity alloy copper, such as cupronickel, beryllium copper, brass, or aluminum bronze, to ensure effective induction heating. The induction power supply 1 has a power of 50-80KW. This higher power provides sufficient energy density to overcome heat loss from the copper alloy, ensuring that the entire target volume reaches the preheating temperature quickly and uniformly within the set heating time, thus improving production efficiency.

[0022] Copper alloys have high electrical conductivity and a significant skin effect at high frequencies, which can easily cause surface overheating and slow internal heating. Setting the current frequency of the induction power supply 1 to 5-20Hz can increase the eddy current penetration depth, allowing energy to act directly on the area 10mm-30mm below the surface (skin effect), achieving uniform heating from the inside out, reducing temperature difference, and improving heating effect.

[0023] Weld 10 is located within the projection area of ​​silicon steel sheet 8. The distance between the inner edge of silicon steel sheet 8 and the inner edge of weld 10 is 20mm-35mm, and the distance between the outer edge of silicon steel sheet 8 and the outer edge of weld 10 is also 20mm-35mm. This allowance ensures that the magnetic lines of force completely cover weld 10 and the nearby base material, achieving uniform heating and avoiding excessively low local temperatures at the weld edge due to abrupt changes in magnetic lines of force, thus guaranteeing welding quality.

[0024] The distance between the induction coil 7 and the weld 10 is 5mm-10mm. If the distance is too large, it will reduce the magnetic field coupling efficiency, and if the distance is too small, it will easily cause local overheating of the workpiece. This distance range can ensure the welding quality of the weld 10.

[0025] The cavity contains a support plate 11, on which multiple positioning grooves are evenly distributed circumferentially. Multiple sets of induction coils 7 are correspondingly provided, each located within one of the positioning grooves. The support plate 11 provides a stable mounting base for the induction coils 7. The positioning grooves ensure uniform spacing between the induction coils 7, thereby achieving a balanced magnetic field distribution and avoiding uneven temperature distribution caused by excessively strong or weak local magnetic fields. In this embodiment, two semi-circular support plates 11 are provided, with a gap between the inner hole of the support plate 11 and the workpiece 5 to be welded.

[0026] When welding the two parts to be welded, part 5 and part 6 of the same model, a support frame 12 is welded and fixed on the inner wall of the cover 2. The support frame 12 is connected to the support plate 11 to ensure that the position of the induction coil 7 remains stable during the welding process and improve the convenience of operation.

[0027] When welding parts of different thicknesses or copper alloy materials, a locking block 15 is installed on the cover 2. An adjusting rod 14 is installed on the locking block 15, passing through the cover 2 and connecting to the support plate 11. A locking bolt 16 is installed on the side wall of the locking block 15 to lock the adjusting rod 14. Each support plate 11 is connected to one or more adjusting rods 14, which are threadedly connected to the locking block 15. In use, by rotating the adjusting rod 14, the height of the support plate 11 and the induction coil 7 can be flexibly adjusted, thereby adjusting the distance between the induction coil 7 and the weld seam 10, improving magnetic field coupling efficiency, ensuring welding quality, and adapting to parts of different sizes. The locking bolt 16 is installed on the side wall of the locking block 15. After adjustment, tightening the locking bolt 16 fixes the adjusting rod 14, ensuring that the positions of the support plate 11 and the induction coil 7 do not shift. This adjustable design significantly improves the equipment's versatility, enabling it to adapt to welding tasks for various specifications of copper alloy ring parts. It also simplifies the operation process, reduces adjustment time when changing workpieces, and further improves production efficiency.

[0028] Furthermore, the adjusting rod 14 is provided with multiple evenly spaced graduations along the axial direction, which allows operators to precisely control the displacement of the adjusting rod 14 according to actual needs, thereby achieving precise adjustment of the distance between the induction coil 7 and the weld 10. The design of the graduations not only improves operability but also provides a basis for the standardization of welding process parameters, ensuring the consistency and repeatability of each preheating process.

[0029] Multiple sets of induction coils 7 are connected in parallel and connected in series to the induction power supply 1 to ensure heating uniformity and improve overall heating efficiency. The parallel arrangement makes the induction coils 7 fit the contour of the annular seam more closely, expanding the heating area and reducing temperature difference; the overall series connection of the induction power supply 1 ensures consistent current, making the power of each induction coil 7 balanced and avoiding uneven heating caused by different impedances. This method is particularly suitable for uniform and rapid preheating of irregularly shaped copper alloy annular seams.

[0030] The spacing between adjacent induction coils 7 is 1-5mm to ensure uniform preheating of the preheating area. Each group of induction coils 7 has 8-20 turns. Multiple groups of induction coils 7 are arranged in a ring, with each group having the same number of turns. This ensures the coverage area of ​​the magnetic field and avoids the problems of low heating efficiency and high energy consumption caused by impedance imbalance.

[0031] Weld 10 is located within the projection range of induction coil 7. The distance between the inner edge of induction coil 7 and the inner edge of weld 10 is 10mm-15mm, and the distance between the outer edge of induction coil 7 and the outer edge of weld 10 is 10mm-15mm. The heating zone is of moderate and uniform width, which can well cover weld 10 and the heat-affected zones on both sides, thereby achieving the highest efficiency and optimal power utilization, and ensuring that the magnetic field energy is effectively absorbed by the workpiece to be welded, thus guaranteeing the preheating effect.

[0032] Furthermore, the cover 2, the support plate 11, and the positioner 9 are all coated with an alumina ceramic coating to prevent the eddies generated during induction heating from flowing in the worktable, thus preventing energy loss and equipment damage, and improving the service life of the equipment.

[0033] Example 1 This invention also discloses a preheating method for welding annular seams of copper alloys, comprising the following steps: (1) Preparations before preheating First, an alumina ceramic coating is applied to the cover 2, the support plate 11, and the positioner 9. Then, the fit of the silicon steel sheet magnetic yoke is checked, with a 25mm margin between the inner and outer diameters of the silicon steel sheet 8 and the inner and outer diameters of the weld 10. Next, the two covers 2 are assembled together to form a cavity, and a vacuum is drawn to -0.1MPa. Then, an inert gas, such as argon, is introduced to ensure a low-oxygen environment throughout the preheating process.

[0034] (2) Start heating Multiple sets of annularly distributed induction coils 7 are connected in parallel and series to an induction power supply 1. When the induction power supply 1 is activated, the induction coils 7 generate an alternating magnetic field, causing eddy currents to heat the internal components of the workpieces to be welded (part 1 5 and part 2 6). The temperature of the preheating zone is monitored in real time by an infrared temperature sensor. The induction power supply 1 stops when the preheating zone temperature reaches the set value, achieving precise temperature control of the preheating zone. The induction coils 7 have 15 turns, the induction power supply 1 has a frequency of 15Hz, and a power of 50KW. The preheating zone is an annular area with an outer diameter of 260mm and an inner diameter of 200mm, with a depth of 60mm (i.e., the thickness of part 2 6), and a preheating time of 50s-80s.

[0035] The cover 2 and induction coil 7 are removed, and existing MIG welding equipment is used to weld the first part 5 and the second part 6. During welding, the positioner 9 drives the first part 5 and the second part 6 to rotate, so that the MIG welding torch can uniformly weld the annular weld 10. Among them, the heavy copper alloy components dissipate heat very slowly. For example, it takes 24 hours for a 1t aluminum bronze component to cool from 1000℃ to room temperature of 25℃, with a temperature drop of 0.8℃ / min. Therefore, removing the cover 2 and welding directly will not affect the overall welding quality.

[0036] After welding the front side, flip the two parts to be welded over, referring to... Figure 5 and Figure 6 As shown, the cover 2 has an opening on its lower side. The cover 2 can be rectangular or cylindrical. Since the workpiece to be welded, 5, is relatively tall, another positioner 9 is installed on the ground plane for ease of operation. The workpiece to be welded, 5, is mounted on the positioner 9, with its upper part protruding above the ground plane, thereby reducing the overall height of the welding device and improving ease of operation. A clamp 13 is installed on the workpiece to be welded, which supports the silicon steel sheet 8. Preheating is then performed using the same parameters as for the front welding. The cover 2 is then removed for welding the flip weld 10.

[0037] During the preheating process, the preheating time is calculated as follows: 1) Temperature rise in the preheating zone: ΔT = T - T0; Where T0 is the initial temperature of the preheating zone, in °C; and T is the final temperature of the preheating zone, in °C. 2) The heat consumed is Q1: Q1 = m1 × c × T1 = m1 × c × ΔT 3) The output energy of induced power supply 1 is Q2 = P × t; Where t is the heating time, in seconds; m—mass of the copper alloy in the heated area, kg; c — Specific heat capacity of copper alloy, kJ / (kg) ℃); P—Rated power of the induction heating equipment, kW; 4) The energy utilization efficiency is: η1 = Q1 / Q2 × 100%; Example 2 In this embodiment, the preheating time is 100s-120s, and the rest is the same as in Embodiment 1, so it will not be repeated here.

[0038] Example 3 In this embodiment, the preheating time is 160-180 seconds, and the rest is the same as in Embodiment 1, so it will not be repeated here.

[0039] Example 4 In this embodiment, the power of the inductive power supply 1 is 60KW, and the rest is the same as in embodiment 1, so it will not be described again.

[0040] Comparative Example 1 The preheating annular areas of the parts to be welded, 5 and 6, are heated with acetylene until the preset heating temperature is reached, at which point heating is stopped.

[0041] The heat generated by burning acetylene is calculated using the following formula: Q3=n×∣Δc H°∣; Among them, Q3-the heat released by the combustion of acetylene, kJ; The amount of substance of n-acetylene, in mol; |ΔcH°|—The heat released by the complete combustion of 1 mol of acetylene, |ΔcH°|=1299 kJ; Since: n = m × M; m - mass of acetylene, g; M - Molar mass of acetylene, 26.04 g / mol; Therefore, Q3 = m × M × |ΔcH°|.

[0042] Since the size of the preheating zone and the final heating temperature in this comparative example are the same as in Example 1, the heat required for the preheating zone is also the same as in Example 1, which is Q1; therefore, the energy utilization efficiency in this comparative example is η2, where η2 = Q1 / Q3 × 100%. Table 1. Experimental data of Examples 1-4 and Comparative Example 1

[0043] According to the data in Table 1, the heating efficiency of Examples 1 to 4 is 40%, while the heating efficiency of Comparative Example 1 is only 8%. The existing heating method used in Comparative Example 1 has a serious problem of energy loss. According to Examples 1 to 4, the higher the output heat, the higher the preheating temperature. Although Comparative Example 1 has a high output heat (15700KJ), its efficiency is extremely low (8%). Therefore, the effective heating is less and the time is longer.

[0044] The above data shows that, under the same workpiece weight (total mass of the two parts to be welded is 1600 kg), the high-efficiency (40%) induction heating device of the present invention (Examples 1-4) can achieve the target preheating temperature in a shorter time and with lower energy consumption. The output heat is positively correlated with the preheating temperature, and the heating speed increases with increasing power. In contrast, although Comparative Example 1 has high input power and large output heat, its efficiency of only 8% results in low heating efficiency, extremely long heating time, and serious energy waste.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An induction preheating device for welding annular seams of copper alloys, characterized in that, The device includes an induction power supply (1), a housing (2), an induction coil (7), a silicon steel sheet (8), and a positioner (9). The housing (2) has a receiving cavity with an air inlet (3) and an air outlet (4). The induction coil (7) is located inside the receiving cavity. The positioner (9) is located below the induction coil (7). The positioner (9) has a recessed receiving groove with a silicon steel sheet (8) inside. The induction coil (7) corresponds to the silicon steel sheet (8) and is used to be installed on both sides of the weld (10). The induction coil (7) is electrically connected to the induction power supply (1).

2. The induction preheating device for welding annular seams of copper alloys according to claim 1, characterized in that, The weld (10) is located within the projection range of the silicon steel sheet (8).

3. The induction preheating device for welding annular seams of copper alloys according to claim 2, characterized in that, The distance between the inner edge of the silicon steel sheet (8) and the inner edge of the weld (10) is 20mm-35mm, and the distance between the outer edge of the silicon steel sheet (8) and the outer edge of the weld (10) is also 20mm-35mm.

4. The induction preheating device for welding annular seams of copper alloys according to claim 1, characterized in that, The distance between the induction coil (7) and the weld (10) is 5mm-10mm.

5. The induction preheating device for welding annular seams of copper alloys according to claim 4, characterized in that, The cavity is provided with a support plate (11), and the support plate (11) is provided with a plurality of positioning grooves evenly distributed along the circumference. The induction coil (7) is provided with a plurality of sets accordingly, and the induction coil (7) is located in the positioning groove.

6. The induction preheating device for welding annular seams of copper alloys according to claim 5, characterized in that, A support frame (12) is fixed on the inner wall of the cover (2), and the support frame (12) is connected to the support plate (11); or, a locking block (15) is installed on the cover (2), and an adjusting rod (14) is installed on the locking block (15). The adjusting rod (14) passes through the cover (2) and is connected to the support plate (11). A locking bolt (16) is installed on the side wall of the locking block (15), and the locking bolt (16) is used to lock the adjusting rod (14).

7. The induction preheating device for welding annular seams of copper alloys according to claim 4, 5, or 6, characterized in that, The weld (10) is located within the projection range of the induction coil (7). The distance between the inner edge of the induction coil (7) and the inner edge of the weld (10) is 10mm-15mm, and the distance between the outer edge of the induction coil (7) and the outer edge of the weld (10) is 10mm-15mm.

8. The induction preheating device for welding annular seams of copper alloys according to claim 5, characterized in that, The cover (2), the support plate (11) and the positioner (9) are all provided with an alumina ceramic coating.

9. The induction preheating device for welding annular seams of copper alloys according to claim 1, characterized in that, The power of the inductive power supply (1) is 50-80KW, and the current frequency of the inductive power supply (1) is 5-20Hz.

10. A preheating method for welding annular seams of copper alloys, employing the induction preheating device according to any one of claims 1 to 9, characterized in that, Includes the following steps: Preheating preparation: Install all components in place, evacuate the cavity, and then introduce inert gas; Preheating: Start the induction power supply (1), the induction coil (7) generates an alternating magnetic field to preheat the weld (10), and monitor the temperature of the preheating area by the infrared temperature sensor. When the temperature of the preheating area reaches the set value, the induction power supply (1) stops. After the weld (10) is completed, flip the workpiece to be welded and repeat the above steps.

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