Spot welding device

Abstract

The utility model provides a spot welding device, which belongs to the field of spot welding and comprises a clamp body, a static arm, a movable arm and a pneumatic piston actuating mechanism. Welding current flows through the abutting part of the movable arm and the static arm; the pneumatic piston executing mechanism is arranged on the clamp body and provided with an output end, the output end is hinged to the middle of the movable arm and pushes the movable arm to abut against the static arm, the output end is at least provided with a first position and a second position, and the output end enters the first position and enables the movable arm to abut against the static arm before welding current climbs. The output end enters the second position when the welding current drops and enables the abutting pressure of the movable arm and the static arm to be increased; the pneumatic piston executing mechanism drives the movable electrode rod to abut against the static electrode rod, so that the output end of the pneumatic piston executing mechanism is switched to the first position to drive the movable electrode rod to apply pre-pressure before welding and holding pressure during welding. And the output end is switched to the second position to drive the movable electrode rod to apply large forging pressure in a short time when the welding current drops, so that impact forging on a welding spot is formed.

Description

Technical Field

[0001] The utility model relates to the technical field of spot welding, in particular to a spot welding device. Background Art

[0002] Spot welding refers to a welding method that uses a cylindrical electrode to form a weld between the contact surfaces of two overlapping workpieces. During spot welding, pressure is first applied to make the workpieces in close contact, and then current is turned on. The contact between the workpieces melts under the action of resistance heat, and a weld is formed after cooling.

[0003] Chinese patent CN104551366B discloses a spot welding device, which discloses that the main structure of the current robot spot welding tongs, whether steel material tongs or aluminum material tongs, relies on the servo motor to drive the movable arm parts to form the closure of the movable and static arms to the welding points, and forms the welding alloy by applying corresponding pressure during the continuous current output process. However, in the key forging process of aluminum material welding, because of the defects of the servo motor itself, that is, it is impossible to suddenly increase a large pressure under the existing pressure in a short time to form impact forging of the welding point, the quality and qualified rate of the welding points welded by the current servo motor driven welding tongs are not satisfactory, resulting in a large number of false welds. Utility Model Content

[0004] In view of this, the utility model proposes a spot welding device for solving the critical forging process in the welding process of aluminum materials. Because of the defects of the servo motor itself, it is impossible to suddenly increase a large pressure under the existing pressure in a short period of time to form impact forging problem on the welding point.

[0005] The technical solution of the utility model is achieved as follows: the utility model provides a spot welding device, including a clamp body, a stationary arm, a movable arm and a pneumatic piston actuator; one end of the stationary arm is fixed on the clamp body; one end of the movable arm is hinged on the clamp body, and the other end of the movable arm rotates around the hinged connection part and abuts the free end of the stationary arm, and the welding current flows through the abutment part of the movable arm and the stationary arm; the pneumatic piston actuator is arranged on the clamp body and has an output end, the output end is hinged to the middle part of the movable arm and pushes the movable arm to abut the stationary arm, the output end has at least a first position and a second position, the output end enters the first position before the welding current climbs and makes the movable arm abut against the stationary arm, and the output end enters the second position when the welding current decreases and increases the pressure of the movable arm abutting against the stationary arm.

[0006] On the basis of the above technical solution, preferably, the pneumatic piston actuator is a film booster cylinder.

[0007] On the basis of the above technical scheme, preferably, it also includes an inverter voltage device, a moving electrode rod and a stationary electrode rod; the inverter voltage device is arranged in the clamp body; the moving electrode rod is inserted in the moving arm, one end of the moving electrode rod passes through the free end of the moving arm to extend outward and the other end is electrically connected to the inverter voltage device; the stationary electrode rod is inserted in the stationary arm, one end of the stationary electrode rod passes through the free end of the stationary arm to extend outward and the other end is electrically connected to the inverter voltage device, and a welding current is formed between the ends of the stationary electrode rod and the moving electrode rod.

[0008] More preferably, it also includes a flexible connector; the flexible connector is arranged between the inverter voltage and the boom, the flexible connector is U-shaped and its two ends are respectively connected to the inverter voltage and the outer wall of the middle part of the boom.

[0009] Further preferably, the output end also has an initial position and a third position; the output end is in the initial position when the workpiece to be welded is clamped between the moving electrode rod and the end of the stationary electrode rod, the output end enters the third position when the workpiece to be welded is clamped between the moving electrode rod and the end of the stationary electrode rod and the pressure of the moving electrode rod and the end of the stationary electrode rod against each other increases, the output end enters the first position before the welding current rises and the pressure of the moving electrode rod and the end of the stationary electrode rod against each other increases again, and the output end enters the second position when the welding current decreases and the pressure of the moving electrode rod and the end of the stationary electrode rod against each other increases again.

[0010] More preferably, it also includes a first elastic member and a pressure protection assembly; a cavity is opened inside the free end of the movable arm along the direction of pressure application of the movable electrode rod; the movable electrode rod is inserted into the cavity, and a flange is provided on the movable electrode rod; the first elastic member is arranged in the cavity and sleeved on the movable electrode rod, and the two ends of the first elastic member respectively abut on the flange and the inner wall of the cavity away from the static electrode rod; the pressure protection assembly is arranged on the movable arm, and the pressure protection assembly is connected between the movable arm and the movable electrode rod, and the pressure protection assembly enables the movable arm and the movable electrode rod to maintain a relative position or enables the movable electrode rod to move relative to the movable arm.

[0011] Further preferably, the pressure protection assembly includes a slider, a first wedge block and a second wedge block; a slide groove is opened on the outer peripheral wall of the movable arm along the direction of pressure application of the movable electrode rod, and the slide groove penetrates the outer peripheral wall of the movable arm and is connected with the cavity; the slider is arranged in the slide groove and moves along the slide groove, one end of the slider is inserted into the cavity and fixedly connected to the outer wall of the movable electrode rod and the other end extends outward through the slide groove; the first wedge block is arranged on the outer wall of the movable arm, the first wedge block is fixed on the end of the slider extending outward and moves synchronously with the slider; two second wedge blocks are arranged on the outer wall of the movable arm and symmetrically arranged on both sides of the slide groove, the two second wedge blocks cooperate with the first wedge block at the same time, the two second wedge blocks limit the first wedge block from moving in the direction away from the static electrode rod, and the second wedge block moves relative to the movable arm in the vertical direction along the axial direction of the slide groove.

[0012] Further preferably, the pressure protection assembly also includes a limit plate and a second elastic member; the limit plate is arranged on the outer wall of the boom, the limit plate is arranged on the side of the second wedge block away from the first wedge block and is spaced apart from the second wedge block; the second elastic member is arranged between the limit plate and the second wedge block and its two ends are respectively connected to the limit plate and the second wedge block.

[0013] More preferably, the pressure protection assembly also includes a sliding rod; one end of the sliding rod is fixed to the side of the second wedge block away from the first wedge block, and the other end of the sliding rod extends outward through the limit plate in a vertical direction along the axial direction of the sliding groove.

[0014] More preferably, the first wedge block is an isosceles trapezoid, the second wedge block is a right-angled trapezoid, the inclined surfaces of the first wedge block and the second wedge block abut against each other, and the length of the hypotenuse of the trapezoid of the second wedge block is greater than the length of the hypotenuse of the trapezoid of the first wedge block.

[0015] A spot welding device of the utility model has the following beneficial effects compared with the prior art:

[0016] (1) The utility model drives the moving electrode rod to press against the stationary electrode rod through the pneumatic piston actuator, so that the output end thereof switches to the first position to drive the moving electrode rod to apply the pre-pressure before welding and the holding pressure during welding, and switches the output end to the second position to drive the moving electrode rod to apply a larger forging pressure in a short time when the welding current decreases, thereby forming impact forging pressure on the welding point.

[0017] (2) The utility model limits the movement of the first wedge block by the two second wedge blocks, so that the first wedge block can only push the two second wedge blocks open and move when the moving electrode rod is subjected to a large counter-pressure reaction force. This not only ensures that the moving electrode rod forms multiple pressure effects on the stationary electrode rod during the welding process, but also avoids the problem that the pneumatic piston actuator is difficult to control the stroke length, resulting in excessive pressure on the moving electrode rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a three-dimensional diagram of the spot welding device of the utility model;

[0020] Figure 2 It is a three-dimensional diagram of the spot welding device of the utility model;

[0021] Figure 3 It is a side view of the spot welding device of the utility model;

[0022] Figure 4 It is a partial side sectional view of the movable arm of the utility model;

[0023] Figure 5 It is a side view of the pressure protection assembly of the utility model;

[0024] Figure 6 It is a side view of the pressure protection assembly of the present invention in another state.

[0025] In the figure: 1, clamp body; 2, stationary arm; 3, movable arm; 301, cavity; 302, slide groove; 4, pneumatic piston actuator; 41, output end; 5, inverter voltage; 6, movable electrode rod; 61, flange; 7, stationary electrode rod; 8, flexible connector; 9, first elastic member; 10, pressure protection assembly; 11, slider; 12, first wedge block; 13, second wedge block; 14, limit plate; 15, second elastic member; 16, slide rod. DETAILED DESCRIPTION

[0026] The following will be combined with the implementation of the utility model to clearly and completely describe the technical solutions in the implementation of the utility model. Obviously, the described implementation is only a part of the implementation of the utility model, not all of the implementations. Based on the implementation of the utility model, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] like Figure 1 As shown, combined Figure 2 The utility model discloses a spot welding device, which comprises a clamp body 1, a stationary arm 2, a movable arm 3 and a pneumatic piston actuator 4.

[0028] The clamp body 1, the stationary arm 2 and the movable arm 3 are all made of aluminum alloy. The clamp body (1) is usually composed of two identical left and right plates. A reinforcing plate is arranged between the two plates and a fixed connection is made by a positioning pin and a thread.

[0029] One end of the stationary arm 2 is fixed on the clamp body 1 .

[0030] One end of the movable arm 3 is hinged to the clamp body 1, and the other end of the movable arm 3 rotates around the hinged portion and abuts against the free end of the stationary arm 2. The welding current flows through the abutting portion of the movable arm 3 and the stationary arm 2. The movable arm 3 and the stationary arm 2 can be opened and closed, so that the workpiece to be welded is clamped between the free ends of the stationary arm 2 and the movable arm 3.

[0031] The pneumatic piston actuator 4 is arranged on the clamp body 1 and has an output end 41, which is hinged to the middle of the movable arm 3 and pushes the movable arm 3 to abut against the stationary arm 2. The pneumatic piston actuator 4 is used to replace the traditional motor servo drive device or hydraulic telescopic rod. The reason is that when the aluminum material is welded, the welded part will be subjected to a pressure before welding, and this pressure will be maintained during the welding process. However, in the process of the welding current slowly decreasing, a large instantaneous forging pressure needs to be applied to the aluminum material again. This forging pressure can form impact forging pressure on the welding point, thereby greatly improving the quality of the welding point; however, the process of applying pressure by the traditional motor servo drive device or hydraulic telescopic rod is relatively slow, and usually does not have multiple strokes. Therefore, the traditional motor servo drive device or hydraulic telescopic rod not only cannot realize the application of forging pressure after applying pre-pressure, but also cannot realize the instantaneous application of forging pressure; while the pneumatic piston actuator 4 can usually be divided into multiple front and rear strokes to apply pre-pressure and forging pressure respectively, and the pneumatic piston actuator 4 can apply pressure in a very short time, and can usually complete the pressure stroke within 0.2s.

[0032] Therefore, when the above technical solution is adopted, since the pneumatic piston actuator 4 has at least two strokes, the output end 41 also has at least a first position and a second position; the output end 41 enters the first position before the welding current rises and causes the movable arm 3 to abut against the stationary arm 2 and applies pre-pressure, and the output end 41 enters the second position when the welding current decreases and increases the pressure of the movable arm 3 abutting against the stationary arm 2 to apply instantaneous forging pressure.

[0033] exist Figure 1 In a preferred embodiment shown, specifically, the pneumatic piston actuator 4 is a diaphragm pressurized cylinder, preferably a special-shaped diaphragm pressurized cylinder.

[0034] exist Figure 3 In a preferred embodiment shown, in order to realize the spot welding operation, it also includes an inverter voltage 5, a moving electrode rod 6 and a stationary electrode rod 7.

[0035] The high-power inverter voltage device 5 is arranged in the clamp body 1; the inverter voltage device 5 generates welding current, and the welding current has three stages of current climbing, current holding and current slow decline.

[0036] The movable electrode rod 6 is inserted into the movable arm 3 , one end of the movable electrode rod 6 passes through the free end of the movable arm 3 and extends outward, and the other end of the movable electrode rod 6 is electrically connected to the inverter voltage device 5 .

[0037] The static electrode rod 7 is inserted into the static arm 2, one end of the static electrode rod 7 passes through the free end of the static arm 2 and extends outward, and the other end is electrically connected to the inverter voltage 5, and a welding current is formed between the static electrode rod 7 and the end of the moving electrode rod 6. The moving electrode rod 6 and the static electrode rod 7 are insulated and connected to the corresponding clamp arms. The workpiece to be welded is clamped between the static electrode rod 7 and the moving electrode rod 6. When the welding current generated by the inverter voltage 5 flows to the static electrode rod 7 through the moving electrode rod 6, the welding current will flow through the workpiece to be welded, thereby realizing the spot welding operation thereon.

[0038] exist Figure 3 In a preferred embodiment shown, since the static electrode rod 7 and the moving electrode rod 6 are electrically connected to the inverter voltage device 5 via wires, in order to prevent the movable arm 3 from rotating too far and pulling the wires between the moving electrode rod 6 and the inverter voltage device 5, a flexible connector 8 is also included.

[0039] The flexible connector 8 is disposed between the inverter voltage device 5 and the boom 3. The flexible connector 8 is U-shaped and its two ends are respectively connected to the inverter voltage device 5 and the outer wall of the middle part of the boom 3. The flexible connector 8 is an insulating rubber block.

[0040] exist Figure 1 In a preferred embodiment shown, during the actual welding process, the moving electrode rod 6 applies three pressures to the workpiece in sequence. Specifically, the output end 41 also has an initial position and a third position.

[0041] When the movable electrode rod 6 is rotated so that the workpiece to be welded is clamped between the ends of the movable electrode rod 6 and the static electrode rod 7, the output end 41 is at the initial position at this time.

[0042] After the workpiece to be welded is clamped between the ends of the moving electrode rod 6 and the stationary electrode rod 7, a pre-pressure needs to be applied to the workpiece to be welded, so the output end 41 enters the third position and the pressure against the ends of the moving electrode rod 6 and the stationary electrode rod 7 increases from zero.

[0043] Before welding the workpiece to be welded, it is necessary to apply a second pressure as the welding holding pressure to ensure that the molten pool of the weld does not flow out of the weld during welding. This pressure needs to be applied before the welding current rises. Therefore, the output end 41 enters the first position before the welding current rises and increases the pressure against the end of the moving electrode rod 6 and the static electrode rod 7 again compared to before.

[0044] When welding is completed and the welding current begins to slowly decrease, it is necessary to apply forging pressure to the weld spot that begins to cool, so that the weld spot forms impact forging. Therefore, the output end 41 enters the second position when the welding current decreases, and the pressure against the ends of the moving electrode rod 6 and the static electrode rod 7 increases again.

[0045] exist Figure 4In a preferred embodiment shown, since the pneumatic piston actuator 4 is a diaphragm booster cylinder, and the stroke of the diaphragm booster cylinder is usually difficult to control, this makes it difficult to control the pressure applied by the diaphragm booster cylinder to drive the moving electrode rod 6 to move. If the pressure is too large, it will cause damage to the welding point. Therefore, a first elastic member 9 and a pressure protection assembly 10 are also included.

[0046] A cavity 301 is provided inside the free end of the movable arm 3 along the direction in which the movable electrode rod 6 applies abutting pressure.

[0047] The moving electrode rod 6 is inserted into the cavity 301 , and a flange 61 is provided on the moving electrode rod 6 .

[0048] The first elastic member 9 is disposed in the cavity 301 and sleeved on the moving electrode rod 6, and the two ends of the first elastic member 9 are respectively abutted against the flange 61 and the inner wall of the cavity 301 away from the static electrode rod 7. The first elastic member 9 can be a spring, and the first elastic member 9 plays the role of buffering the pressure applied by the moving electrode rod 6.

[0049] However, the pressure applied by the movable electrode rod 6 needs to reach and maintain a certain strength, so the pressure protection component 10 is arranged on the movable arm 3, and the pressure protection component 10 is connected between the movable arm 3 and the movable electrode rod 6. Before the pressure applied by the movable electrode rod 6 does not exceed a certain preset pressure value, the pressure protection component 10 keeps the movable arm 3 and the movable electrode rod 6 in relative position; and when the pressure applied by the movable electrode rod 6 exceeds the preset pressure value, the pressure protection component 10 can move the movable electrode rod 6 relative to the movable arm 3, so that the first elastic member 9 can buffer the pressure applied by the movable electrode rod 6.

[0050] exist Figure 5 In a preferred embodiment shown, specifically, the pressure protection assembly 10 includes a sliding block 11 , a first wedge block 12 and a second wedge block 13 .

[0051] A slide groove 302 is provided on the outer peripheral wall of the movable arm 3 along the direction of the abutting pressure applied by the movable electrode rod 6 , and the slide groove 302 penetrates the outer peripheral wall of the movable arm 3 and is connected with the cavity 301 .

[0052] The slider 11 is disposed in the slide groove 302 and moves along the slide groove 302 . One end of the slider 11 is inserted into the cavity 301 and fixed to the outer wall of the moving electrode rod 6 , and the other end of the slider 11 passes through the slide groove 302 and extends outward.

[0053] The first wedge block 12 is arranged on the outer wall of the movable arm 3 . The first wedge block 12 is fixed on the end portion of the sliding block 11 extending outward and moves synchronously with the sliding block 11 .

[0054] Two second wedge blocks 13 are arranged on the outer wall of the movable arm 3 and symmetrically arranged on both sides of the slide groove 302. The two second wedge blocks 13 cooperate with the first wedge block 12 at the same time. The two second wedge blocks 13 limit the movement of the first wedge block 12 in the direction away from the static electrode rod 7. The second wedge blocks 13 move in the vertical direction along the axial direction of the slide groove 302 relative to the movable arm 3.

[0055] When the above technical solution is adopted, before the pressure applied by the moving electrode rod 6 exceeds the preset pressure value, since the two second wedge blocks 13 block the top of the first wedge block 12, the reaction force of the pressure applied by the moving electrode rod 6 on the first wedge block 12 is insufficient to push open the two second wedge blocks 13, and it is also impossible to move along the slide groove 302, thereby achieving the goal of keeping the relative position of the moving electrode rod 6 and the movable arm 3 fixed; but when the pressure applied by the moving electrode rod 6 exceeds the preset pressure value, the reaction force of the pressure applied by the moving electrode rod 6 on the first wedge block 12 is sufficient to push open the two second wedge blocks 13, thereby driving the moving electrode rod 6 along the slide groove 302 along the first wedge block 12 and retreating relative to the movable arm 3, thereby being buffered by the first elastic member 9.

[0056] exist Figure 6 In a preferred embodiment shown, in order to prevent the first wedge block 12 from pushing out the second wedge block 13 before the reaction force is insufficient, and to enable the second wedge block 13 to be reset after being pushed out, the pressure protection assembly 10 also includes a limit plate 14 and a second elastic member 15.

[0057] The limiting plate 14 is disposed on the outer wall of the movable arm 3 , and the limiting plate 14 is disposed on a side of the second wedge block 13 away from the first wedge block 12 and is spaced apart from the second wedge block 13 .

[0058] The second elastic member 15 is disposed between the limit plate 14 and the second wedge block 13 and its two ends are respectively connected to the limit plate 14 and the second wedge block 13. The second elastic member 15 may be a spring. The magnitude of the extrusion force under which the second elastic member 15 undergoes elastic compression determines the magnitude of the preset pressure value.

[0059] exist Figure 6 In a preferred embodiment shown, in order to limit the moving direction and range of the second wedge block 13 , the pressure protection assembly 10 further includes a sliding rod 16 .

[0060] One end of the slide rod 16 is fixed to the side of the second wedge block 13 away from the first wedge block 12 , and the other end of the slide rod 16 extends outward through the limit plate 14 along the vertical direction of the axial direction of the slide slot 302 .

[0061] exist Figure 5In a preferred embodiment shown in the figure, the first wedge block 12 is an isosceles trapezoid, and the second wedge block 13 is a right-angled trapezoid. The first wedge block 12 abuts against the inclined surfaces of the second wedge block 13. The length of the trapezoidal hypotenuse of the second wedge block 13 is greater than the length of the trapezoidal hypotenuse of the first wedge block 12, so that the first wedge block 12 needs to be subjected to sufficient reaction force to apply sufficient extrusion pressure to both sides, and then it can push open the two second wedge blocks 13 at the same time, avoiding the problem that the first wedge block 12 can easily push open the two second wedge blocks 13 to move, and the pressure protection function cannot be achieved.

[0062] 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 in the protection scope of the present invention.

Claims

1. A spot welding device, characterized in that: It comprises a clamp body (1), a stationary arm (2), a movable arm (3) and a pneumatic piston actuator (4); One end of the stationary arm (2) is fixedly mounted on the clamp body (1); One end of the movable arm (3) is hingedly connected to the clamp body (1), and the other end of the movable arm (3) rotates around the hinged portion and abuts against the free end of the stationary arm (2), and a welding current flows through the portion where the movable arm (3) abuts against the stationary arm (2); The pneumatic piston actuator (4) is arranged on the clamp body (1) and has an output end (41). The output end (41) is hinged to the middle of the movable arm (3) and pushes the movable arm (3) to abut against the stationary arm (2). The output end (41) has at least a first position and a second position. Before the welding current rises, the output end (41) enters the first position and causes the movable arm (3) and the stationary arm (2) to abut against each other. When the welding current decreases, the output end (41) enters the second position and increases the pressure of the movable arm (3) and the stationary arm (2) abutting against each other.

2. A spot welding device according to claim 1, characterized in that: The pneumatic piston actuator (4) is a film-pressurized cylinder.

3. A spot welding device according to claim 1, characterized in that: It also includes an inverter voltage device (5), a moving electrode rod (6) and a stationary electrode rod (7); The inverter voltage device (5) is arranged in the clamp body (1); The movable electrode rod (6) is inserted into the movable arm (3), one end of the movable electrode rod (6) passes through the free end of the movable arm (3) and extends outward, and the other end is electrically connected to the inverter voltage device (5); The static electrode rod (7) is inserted into the static arm (2), one end of the static electrode rod (7) passes through the free end of the static arm (2) and extends outward, and the other end is electrically connected to the inverter voltage (5), and a welding current is formed between the static electrode rod (7) and the end of the moving electrode rod (6).

4. A spot welding device according to claim 3, characterized in that: It also comprises a flexible connector (8); the flexible connector (8) is arranged between the inverter voltage (5) and the movable arm (3); the flexible connector (8) is U-shaped and its two ends are respectively connected to the inverter voltage (5) and the outer wall of the middle part of the movable arm (3).

5. A spot welding device according to claim 3, characterized in that: The output end (41) also has an initial position and a third position; the output end (41) is in the initial position when the workpiece to be welded is clamped between the ends of the moving electrode rod (6) and the stationary electrode rod (7); the output end (41) enters the third position when the workpiece to be welded is clamped between the ends of the moving electrode rod (6) and the stationary electrode rod (7) and the pressure of the moving electrode rod (6) and the stationary electrode rod (7) against each other is increased; the output end (41) enters the first position before the welding current rises and the pressure of the moving electrode rod (6) and the stationary electrode rod (7) against each other is increased again; the output end (41) enters the second position when the welding current drops and the pressure of the moving electrode rod (6) and the stationary electrode rod (7) against each other is increased again.

6. A spot welding device according to claim 3, characterized in that: It also includes a first elastic member (9) and a pressure protection component (10); A cavity (301) is provided inside the free end of the movable arm (3) along the direction in which the abutting pressure of the movable electrode rod (6) is applied; The moving electrode rod (6) is inserted into the cavity (301), and a flange (61) is provided on the moving electrode rod (6); The first elastic member (9) is arranged in the cavity (301) and sleeved on the moving electrode rod (6), and two ends of the first elastic member (9) are respectively abutted against the flange (61) and the inner wall of the cavity (301) at one end away from the stationary electrode rod (7); The pressure protection component (10) is arranged on the movable arm (3), and the pressure protection component (10) is connected between the movable arm (3) and the movable electrode rod (6). The pressure protection component (10) enables the movable arm (3) and the movable electrode rod (6) to maintain a relative position or enables the movable electrode rod (6) to move relative to the movable arm (3).

7. A spot welding device according to claim 6, characterized in that: The pressure protection assembly (10) comprises a sliding block (11), a first wedge block (12) and a second wedge block (13); A slide groove (302) is provided on the outer peripheral wall of the movable arm (3) along the direction in which the abutting pressure of the movable electrode rod (6) is applied, and the slide groove (302) penetrates the outer peripheral wall of the movable arm (3) and is connected to the cavity (301); The slider (11) is arranged in the slide groove (302) and moves along the slide groove (302); one end of the slider (11) is inserted into the cavity (301) and fixedly connected to the outer wall of the moving electrode rod (6), and the other end passes through the slide groove (302) and extends outward; The first wedge block (12) is arranged on the outer wall of the movable arm (3); the first wedge block (12) is fixed on the end portion of the slider (11) extending outward and moves synchronously with the slider (11); The two second wedge blocks (13) are arranged on the outer wall of the movable arm (3) and symmetrically arranged on both sides of the slide groove (302). The two second wedge blocks (13) cooperate with the first wedge block (12) at the same time. The two second wedge blocks (13) limit the first wedge block (12) from moving in a direction away from the static electrode rod (7). The second wedge block (13) moves in a direction perpendicular to the axis of the slide groove (302) relative to the movable arm (3).

8. A spot welding device according to claim 7, characterized in that: The pressure protection assembly (10) further comprises a limiting plate (14) and a second elastic member (15); The limit plate (14) is arranged on the outer wall of the movable arm (3), and the limit plate (14) is arranged on a side of the second wedge block (13) away from the first wedge block (12) and is spaced apart from the second wedge block (13); The second elastic member (15) is arranged between the limiting plate (14) and the second wedge block (13), and two ends thereof are respectively connected to the limiting plate (14) and the second wedge block (13).

9. A spot welding device according to claim 8, characterized in that: The pressure protection assembly (10) further comprises a slide rod (16); one end of the slide rod (16) is fixedly mounted on the side of the second wedge block (13) away from the first wedge block (12), and the other end of the slide rod (16) extends outwardly through the limit plate (14) in a vertical direction along the axis of the slide groove (302).

10. A spot welding device according to claim 7, characterized in that: The first wedge block (12) is an isosceles trapezoid, the second wedge block (13) is a right-angled trapezoid, the inclined surfaces of the first wedge block (12) and the second wedge block (13) are in contact with each other, and the length of the trapezoidal hypotenuse of the second wedge block (13) is greater than the length of the trapezoidal hypotenuse of the first wedge block (12).

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