Shunt-type electrode device for projection welding, projection welding machine and projection welding method

Abstract

The purpose of the present invention is to provide a shunt electrode device for projection welding, a projection welding machine and a projection welding method to address the deficiency that the welding quality of a desired welding point of a workpiece cannot be detected during projection welding in the prior art. The shunt electrode device for projection welding comprises a main electrode and a sub-electrode. There are at least two sub-electrodes, which are located on the surface of the main electrode, fixedly connected to the main electrode and conducting current. The projection welding machine comprises an electrode device and a current sensor. The shunt electrode device and the projection welding method are adopted. A main electrode and at least two sub-electrodes are provided. The main electrode is electrically connected to each sub-electrode, and power is supplied to the main electrode and thus to each sub-electrode. The shunt electrode device for projection welding, the projection welding machine and the projection welding method of the present invention improve production efficiency and avoid waste. The quality of welding is reflected according to the welding current, so that the detection of the welding structure and welding are carried out simultaneously, and defective products can be discovered in time.

Description

Technical Field

[0001] The present invention relates to the technical field of electric welding equipment, and in particular to an electrode device for projection welding, a projection welding machine and a projection welding method. Background Art

[0002] Projection welding is a highly efficient welding method that can perform multiple-point welding at the same time. It is to process multiple convex points on the plate in advance, or use the profiles and chamfers on the weldment that can concentrate the current as the mutual contact points during welding. During welding, the contact of the convex points increases the pressure and current density per unit area, thereby welding the objects to be welded together. Projection welding can perform multiple-point welding at one time, which improves productivity. At present, projection welding is a major welding method for welding parts or flat workpieces such as white appliances. During projection welding, since one electrode welds multiple convex points at the same time, when the heights of the convex points are inconsistent, one or more convex points cannot be pressed tightly, resulting in welding defects such as cold welding and sparking. Therefore, it is necessary to detect the welding quality. At present, one method of detection is to use a destructive disassembly method to spot check the welding quality of the welds after the workpiece is completely welded. On the one hand, this quality detection method requires the destruction and disassembly of the workpiece, resulting in waste of the workpiece to be inspected. On the other hand, this sampling method cannot guarantee the welding quality of each workpiece, and it is even more impossible to know the welding quality of the welds you want to know. Another welding quality detection method is to measure the current of the electrode, but this method measures the current of the entire electrode, and it is impossible to know the welding quality of each convex point. For example, when welding workpieces with strict requirements such as waveguides, 24 convex points are stamped out on the four sides of the workpiece as welding points, and each side has 6 points. The customer requires that the welding points of each two adjacent points must be firm, and the welding points at the four corners must be firm, and cold welding is not allowed. The welding methods and welding equipment in the prior art cannot meet the customer's needs for full inspection of welding point quality. Summary of the invention

[0003] The purpose of the present invention is to provide a shunt electrode device for projection welding, a projection welding machine and a projection welding method to address the deficiency of the prior art that the welding quality of the desired welding points of the workpiece cannot be detected during projection welding.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A shunt-type electrode device for projection welding comprises a main electrode and a sub-electrode, wherein the sub-electrodes are at least two and are located on the surface of the main electrode and are fixedly connected to the main electrode and conduct current;

[0006] The sub-electrode is in a vertical column or cone shape or in a bent shape, one end of which is a welding end and the other end is a connecting end, and is fixedly connected to the main electrode through the connecting end, and / or a wire-accommodating groove is provided on the main electrode, and / or the main electrode is in a rectangular body, the sub-electrodes are arranged along the four sides of the main electrode, and the wire-accommodating groove is arranged along the four sides of the main electrode;

[0007] The lower surface of the connecting end of the sub-electrode is provided with a boss, and the surface of the main electrode provided with the sub-electrode is provided with a positioning groove, the boss of the sub-electrode is located in the positioning groove of the main electrode, and the sub-electrode and the main electrode are positioned by the boss and the positioning groove;

[0008] The connecting end is provided with a through hole 1, and a threaded hole 2 or a through hole 2 is provided at a position corresponding to the through hole 1 on the main electrode. The through hole 1 and the threaded hole 2 or the through hole 2 are used to set a connecting piece, and the sub-electrode and the main electrode are fixedly connected together through the connecting piece;

[0009] The through hole one is located on the boss, and the threaded hole two or the through hole two is located in the positioning groove.

[0010] A projection welding machine, comprising an electrode device and a current sensor, adopting the above-mentioned shunt electrode device, one or more shunt electrodes are provided with a current sensor corresponding to each other, and the current sensor is used to detect the welding current of the corresponding shunt electrode device;

[0011] An electromagnetic shielding device is provided between at least two adjacent current sensors, or the electromagnetic shielding device is a fence closed on three sides or four sides, and each wall of the fence isolates two adjacent current sensors;

[0012] The electromagnetic shielding device is an electromagnet provided with an insulating layer, and / or the current sensor is a Hall coil or a Rogowski coil; and / or when the electrode is a rectangular body and the split-electrode is arranged along the four sides of the main line as described in claim 2, the electromagnetic shielding device includes an insulating magnetic conductive plate 1 arranged between adjacent current sensors and an insulating magnetic conductive plate 2 arranged in a rectangular ring, and two adjacent insulating magnetic conductive plates 1 and the corresponding insulating magnetic conductive plates 2 form a fence with three closed sides. The current sensor is located in the corresponding fence; or opposite to the insulating magnetic conductive plate 2, an insulating magnetic conductive plate 3 is also provided to form a fence with four closed sides.

[0013] A projection welding method, wherein a main electrode and at least two sub-electrodes are provided, the main electrode is electrically connected to each sub-electrode, power is supplied to the main electrode and thus to each sub-electrode, the current of the main electrode is divided on each sub-electrode, and each sub-electrode contacts with its corresponding convex point to weld the convex point position simultaneously;

[0014] A projection welding method as described in claim 9 is characterized in that during welding, the shunt current of the sub-electrode is detected by a current detection device to obtain the welding current of the corresponding sub-electrode so as to obtain the welding quality of the corresponding convex point.

[0015] In the shunt-type electrode device for projection welding of the present invention, the total current is conducted by the total electrode, and the branch current is conducted through the corresponding projections by the branch electrodes. Therefore, the welding current of the detected projections can be detected, and the welding quality can be judged by the welding current. This makes the detection of poor welding such as cold soldering at the projections simple and reliable, and enables the detection to be carried out simultaneously with welding. There is no need to disassemble the welded parts for random inspection after welding, thereby improving production efficiency and avoiding waste.

[0016] The projection welding machine adopting the structure of the present invention adopts a shunt electrode device and a current detection device. The current detection device detects the welding current condition of the projection point whose position needs to be known, and reflects the welding quality condition according to the welding current condition, so that the detection of the welding quality of each welding point can be carried out synchronously with the welding, and defective products can be discovered in time.

[0017] By adopting the projection welding method of the present invention for welding, the same welding device can be used to weld multiple projections, each sub-electrode divides the current, and the welding conditions of the welding points corresponding to the sub-electrodes are analyzed by detecting the welding current of the sub-electrodes, thereby judging the welding conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the structure of an embodiment of the split-current electrode device of the present invention, wherein some split electrodes are removed;

[0019] Figure 2 is a schematic diagram of the structure of a sub-electrode embodiment;

[0020] Figure 3 It is a schematic diagram of the structure of a total electrode embodiment, on which a wire accommodating groove is provided;

[0021] Figure 4 It is a schematic structural diagram of an embodiment of a shielding device;

[0022] Figure 5 The welding current after the No. 5 point is flattened, where the horizontal axis is the welding time and the vertical axis is the current;

[0023] Figure 6 is the normal welding current at point 5, where the horizontal axis is the welding time and the vertical axis is the current;

[0024] Figure 7 The welding current after the No. 21 point is flattened, where the horizontal axis is the welding time and the vertical axis is the current;

[0025] Figure 8 This is the normal welding current at point 21, where the horizontal axis is the welding time and the vertical axis is the current.

[0026] Description of Reference Numerals

[0027] 100-total electrode; 101-threaded hole two or through hole two; 102-positioning groove; 103-wire groove;

[0028] 200-sub-electrode; 201-welding end; 202-connecting end; 203-through hole 1; 204-boss;

[0029] 300-current sensor;

[0030] 400-Electromagnetic shielding device; 401-Magnetic conductor DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0032] like Figure 1 and Figure 2 As shown, the projection welding machine of the present invention comprises a current sensor 300, an upper electrode and a lower electrode, wherein the upper electrode and / or the lower electrode is a shunt electrode.

[0033] The shunt-type electrode of the structure of the present invention comprises a main electrode 100 and at least two sub-electrodes 200, each sub-electrode is arranged on the surface of the main electrode and protrudes from the surface of the main electrode, and there is a gap between the two sub-electrodes. The main electrode and each sub-electrode are electrically connected to each other. The sub-electrode can be a part of the main electrode, or the main electrode and the sub-electrode can be arranged separately. When the sub-electrode is a part of the main electrode, the end of the main electrode, that is, the welding end of the main electrode used for welding with the workpiece, is arranged separately as a sub-electrode. With this structure, when welding, the main electrode is driven by the same driving device, and the current of the main electrode is controlled by the same circuit. Each sub-electrode is used to correspond to a convex point or multiple convex points, and these multiple convex points can be treated as a detection unit during detection. There are many ways to arrange the sub-electrodes, such as simply arranging in rows, forming a matrix, annularly arranging, or having no specific rules. The arrangement is determined by the position of the convex points. No matter which arrangement is adopted, there must be a certain gap between each adjacent sub-electrode to ensure that the current of the sub-electrodes is not mutually conductive. The height of each sub-electrode is specifically set according to the specific welding object. When the sub-electrodes and the main electrode are of an integrated structure, a preferred embodiment is that the sub-electrodes are cylindrical bodies arranged on the surface of the main electrode, that is, there are at least two electrode columns on the surface of the main electrode. When the sub-electrodes and the main electrode are separate, the overall shape of each sub-electrode is cylindrical, one end of the sub-electrode is a connecting end 202 fixedly connected to the surface of the main electrode by a fixed connection device or a fixed connection structure, and the other end is used as a welding end 201 for welding workpieces. For example, each sub-electrode can be a straight column or a straight cone, or an irregular geometric shape, such as L-shaped, trapezoidal, oblique column or oblique cone, etc. In short, each sub-electrode is isolated from each other and not connected, the bottom of each sub-electrode is fixedly connected to the main electrode by conductive glue or a threaded hole is set at the bottom of the sub-electrode, and a through hole 2 or a threaded hole 2 101 is set on the main electrode. The main electrode and the sub-electrode are fixedly connected by bolts, and a structure combining bolts and conductive glue can also be used. In a more preferred structure, the two ends of the sub-electrode are bent into an "L" shape, one of the bent ends is a connection end 202, and the other bent end is a welding end 201. A threaded hole 2 or a through hole 2 101 is provided on the connection end, and the position of the threaded hole 2 or the through hole 2 corresponds to the position of the through hole 1, and the main electrode and the sub-electrode are fixedly connected by connecting bolts. Preferably, a boss 204 is provided below the connection end, and a positioning groove 102 is provided on the surface of the main electrode where the sub-electrode is provided, the through hole 1 is located on the boss 204, and the through hole 2 or the threaded hole 2 is located in the positioning groove. The positions and shapes of the boss and the positioning groove are adapted. When the sub-electrode and the main electrode are fixedly connected, the boss is located in the positioning groove, which facilitates the installation and positioning of the sub-electrode, so that the position between the sub-electrodes corresponds to the position between the convex points, so that the position of each sub-electrode and each convex point on the workpiece is accurate during welding, and the occurrence of cold welding or welding failure is prevented. In addition, the connection between the sub-electrode and the main electrode can be stable and reliable, and it is not easy for the two to be misaligned.

[0034] Figure 4 One specific embodiment structure is shown, in which the main electrode is a rectangular body, and a plurality of sub-electrodes 200 are arranged on the upper surface of the main electrode 100 along the inner side of the four sides of the main electrode. Each sub-electrode stands upright on the surface of the main electrode, and adjacent sub-electrodes are arranged at intervals. Each sub-electrode is an L-shaped electrode column with two bent ends. One bent end of each electrode column constitutes a welding end 201, and the other bent end is a connecting end 202 for fixed connection with the main electrode. A through hole 1 203 is arranged on the surface of the connecting end for setting a connecting component such as a bolt, and a threaded hole or a through hole 2 101 is arranged at the corresponding position of the main electrode for forming a connecting hole of a connecting component with the through hole 1 203. The sub-electrode can be used as a current measuring unit to measure the current of the corresponding convex point during welding, and the virtual welding condition of the corresponding welding point can be understood by the measured current of the sub-electrode. The boss is an oblong and the positioning groove is a rectangle. The width of the boss is adapted to the width of the positioning groove, and the two are connected by a transition fit or a clearance fit.

[0035] In order to verify that the concept of the present invention can objectively reflect the welding quality of the convex points at the detected points, the convex points at points 5 and 21 of a workpiece are flattened during welding to make poor contact with the corresponding electrodes during the welding process, simulating a cold weld. Figure 5-Figure 8 As shown, the welding current of the corresponding convex welds at point 5 and point 21 is shown. It is obviously smaller than the welding current of the convex welds of the corresponding points in normal welding, and the effective time of continuous welding is short. Therefore, it can be explained that the electrode with the structure of the present invention can shunt the total current, and the welding quality can be detected in real time by measuring the size of the shunt current. The detection result is reliable and the detection method is simple and convenient. When connected to the host computer, the quality of each convex weld of the workpiece can be monitored in real time, and the current data of each convex weld of the workpiece can be traced.

[0036] In the present invention, in a better embodiment, the current sensor 300 preferably adopts a Hall coil or a Rogowski coil. A current sensor may be set for each electrode, or a current sensor may be set for multiple electrodes, or a current sensor may be set for one or several electrodes, depending on the specific requirements of the convex welding points to be understood. For example, for the quality requirements mentioned in the background technology, it is required that no cold solder joints appear between two adjacent convex welding points, and no cold solder joints appear between the convex welding points at the four corners. Then, at least one Hall coil or Rogowski coil is set for the electrode corresponding to each of the four corners, and at least one Hall coil or Rogowski coil is set for the two electrodes corresponding to two adjacent two points. When the current of the convex welding points at the two points shows a weak current with a value lower than the normal value, it means that it is unqualified. It is best to set a current sensor for each electrode to understand the welding quality of the welding point at each point so as to correct defective products. When a Hall coil or a Rogowski coil is used as a current sensor, the Hall coil or the Rogowski coil can be sleeved outside the connection end of the sub-electrode, and the connection wire of each Hall coil or the Rogowski coil is connected to the wiring terminal, and the power supply is connected through the wiring terminal, and there is a gap between two adjacent Hall coils or the Rogowski coils. With this structure, since the Hall coil or the Rogowski coil is sleeved outside the sub-electrode, the spacing between the sub-electrodes will be increased, which will hinder the corresponding position between the sub-electrode and the convex point, and the connection wire is exposed to the environment, which is not conducive to on-site operation. Therefore, it is best to adopt a structure in which a boss 204 is provided on the lower surface of the connection end of the sub-electrode, and the boss 204 constitutes the detection position of the current, and the Hall coil or the Rogowski coil is located outside the boss of the corresponding electrode. In this way, a space for accommodating the Hall coil or the Rogowski coil is formed between the lower surface of the connection end of the sub-electrode and the upper surface of the total electrode and the outer surface of the boss. It is preferred that the shape of the boss matches the shape of the Hall coil or the Rogowski coil. When the Hall coil or the Rogowski coil is an oblong ring, the boss is an oblong ring. The Hall coil or the Rogowski coil is sleeved outside the boss. The Hall coil or the Rogowski coil senses the welding current flowing through the sub-electrode. In a more preferred structure, Figure 3 As shown, a wire groove is provided on the upper surface of the main electrode as a structure for accommodating the connecting wires of the current sensor. The wire groove is used to collect the connecting wires of each current sensor so as to be centrally enclosed. It is best to set a closing cover on the wire groove to enclose the connecting wires of the current sensor in the wire groove to prevent the connecting wires from being exposed. For example, Figure 4 and Figure 3 In the illustrated embodiment, the wire accommodating groove 103 is located in the area outside the positioning groove. The wire accommodating groove is annular and is located inside or outside the ring formed by the positioning groove.

[0037] In order to increase the accuracy of the detection data, the position of the current sensor and the position between the electrodes should be fixed to prevent the sensor position from changing, causing the induction signal zero position to change, making the detection signal inaccurate. When the current sensor is set outside the welding end, the current sensor and the welding end are fixed together by AB glue to make the position between the two stable. When the current sensor is located outside the boss, the sub-electrode and the main electrode are fixedly connected by bolts, so the position between the two is relatively fixed. In order to better achieve the position fixation between the two, the current sensor is bonded to the surface of the main electrode and / or the lower surface of the sub-electrode with AB glue.

[0038] like Figure 1 As shown, in projection welding, the current is generally large, reaching tens or hundreds of kA. When the welding current is large, the magnetic field generated between the currents of adjacent sub-electrodes and the magnetic field generated by the Hall coil or Rogowski coil itself will cause mutual interference to the adjacent Hall coil or Rogowski coil. To avoid interference, an electromagnetic shielding device 400 is set at least between two adjacent current sensors. When current passes through adjacent sub-electrodes, it will not interfere with the current sensors on the adjacent sub-electrodes, reduce mutual inductance, and shield the magnetic field generated by the adjacent electrodes and sensors. The shielding device uses a magnetic conductor as a material, and an insulating layer is set outside the magnetic conductor to make the electrodes and current sensors non-conductive and non-magnetic between the shielding device. A relatively effective and simple structure is to set a magnetic conductor 401 coated with insulating paint between adjacent sub-electrodes to isolate the currents of adjacent electrodes. A more effective way is to surround the three sides of the Hall coil or Rogowski coil with insulating magnetic conductors. A more effective way is to surround the four sides of the Hall coil or Rogowski coil with insulating magnetic conductors to form a fence-like structure.

[0039] In order to further reduce the interference of electrical and magnetic signals, twisted pair cables are used as the connection line between the current sensor and the data collector.

[0040] The present invention provides a projection welding method, which includes a main electrode and a sub-electrode, wherein the main electrode is conductively connected to each sub-electrode, and power is supplied to the main electrode so as to supply power to each sub-electrode at the same time, and the current of the main electrode is shunted on each sub-electrode, and each sub-electrode contacts with its corresponding convex point to weld the convex point position simultaneously. When welding, the shunted current of the sub-electrode is detected by a current detection device to obtain the welding current of the corresponding sub-electrode, so as to obtain the welding quality of the corresponding convex point. The shunted electrode and projection welding machine of the above structure can be used to implement the welding method of the present invention.

Claims

1. A shunt electrode device for projection welding, characterized in that: It comprises a main electrode and sub-electrodes, wherein there are at least two sub-electrodes, which are located on the surface of the main electrode, fixedly connected to the main electrode and conducting current, and the sub-electrodes are bent, one end of which is a welding end, and the other end is a connecting end, which is fixedly connected to the main electrode through the connecting end, and a boss is provided on the lower surface of the connecting end of the sub-electrode, and a positioning groove is provided on the surface of the main electrode on which the sub-electrodes are provided, and the boss of the sub-electrode is located in the positioning groove of the main electrode, and the sub-electrode and the main electrode are positioned by the boss and the positioning groove, and the boss is used to set a current detection device, and the current detection device is a Hall coil or a Rogowski coil, and a space for accommodating the Hall coil or the Rogowski coil is formed between the lower surface of the connecting end of the sub-electrode, the upper surface of the main electrode and the outer surface of the boss.

2. The shunt-type electrode device for projection welding according to claim 1, characterized in that: The main electrode is provided with a wire accommodating groove.

3. The shunt-type electrode device for projection welding according to claim 2, characterized in that: The main electrode is in a rectangular shape, the sub-electrodes are arranged along the four sides of the main electrode, and the wire-accommodating grooves are arranged along the four sides of the main electrode.

4. The shunt-type electrode device for projection welding according to claim 2 or 3, characterized in that: The connecting end is provided with through hole one, and the position corresponding to through hole one on the main electrode is provided with threaded hole two or through hole two. Through hole one and threaded hole two or through hole two are used to set a connecting piece, and the sub-electrode and the main electrode are fixedly connected together through the connecting piece.

5. The shunt-type electrode device for projection welding according to claim 4, characterized in that: The through hole one is located on the boss, and the threaded hole two or the through hole two is located in the positioning groove.

6. A projection welding machine, comprising an electrode device, characterized in that: It also includes a current sensor, which adopts the shunt electrode device described in any one of claims 1-5, and a current sensor is set corresponding to one or more shunt electrodes. The current sensor is used to detect the welding current of the corresponding sub-electrode of the shunt electrode device, and the cold welding condition of the corresponding welding point is understood by the measured current of the sub-electrode. When the current of the sub-electrode corresponding to the convex welding point shows a weak current with a value lower than the normal value, the welding quality is unqualified. The current sensor is a Hall coil or a Rogowski coil, and the Hall coil or the Rogowski coil is located in the positioning groove outside the boss.

7. The projection welding machine according to claim 6, characterized in that An electromagnetic shielding device is arranged between at least two adjacent current sensors, or the electromagnetic shielding device is a fence closed on three sides or four sides, and each wall of the fence isolates two adjacent current sensors.

8. The projection welding machine according to claim 7, characterized in that The electromagnetic shielding device is an electromagnet provided with an insulating layer, and / or when the shunt electrode device described in claim 3 is adopted in which the main electrode is a rectangular body and the sub-electrodes are arranged along the four sides of the main electric line, the electromagnetic shielding device includes an insulating magnetic conductive plate 1 arranged between adjacent current sensors and an insulating magnetic conductive plate 2 arranged in a rectangular ring, two adjacent insulating magnetic conductive plates 1 and the corresponding insulating magnetic conductive plate 2 form a fence closed on three sides, and the current sensor is located in the corresponding fence; or an insulating magnetic conductive plate 3 is also provided opposite to the insulating magnetic conductive plate 2 to form a fence closed on four sides.

9. A projection welding method, characterized in that: A shunt electrode device for projection welding as described in any one of claims 1 to 5 is used, wherein a main electrode and at least two sub-electrodes are provided, the main electrode being electrically connected to the sub-electrodes, power is supplied to the main electrode and thus to the sub-electrodes, the current of the main electrode is shunted on the sub-electrodes, and the sub-electrodes are in contact with their respective corresponding convex points to weld the convex point positions simultaneously, during welding, the shunt current of the sub-electrodes is detected by a current detection device to obtain the welding current of the corresponding sub-electrode, the cold welding condition of the corresponding welding point is understood by the measured current of the sub-electrode, when the current of the sub-electrode corresponding to the convex welding point is a weak current with a value lower than the normal value, the welding quality is unqualified, and the welding quality of the corresponding convex point can be obtained.

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