Spot welding equipment for circuit board production

Abstract

The utility model discloses spot welding equipment for circuit board production. The spot welding equipment comprises a U-shaped double-electric-welding-head support moving along the X axis and the Z axis through a first sliding set, two electric welding heads arranged on the U-shaped double-electric-welding-head support side by side and a welding wire conveying assembly moving along the X axis and the Y axis through a second sliding set, and the welding wire conveying assembly conveys welding wires in the Y-axis direction. The first sliding set comprises a drag chain sliding assembly moving along the X axis, the drag chain sliding assembly is connected with a first air cylinder assembly moving along the Z axis, and the first air cylinder assembly is connected with a U-shaped double-electric-welding-head support. The second sliding set comprises a second air cylinder assembly moving along the X axis, the second air cylinder assembly is connected with a third air cylinder assembly moving along the Y axis, and the third air cylinder assembly is connected with the welding wire conveying assembly. Through alternate welding of double welding heads, a high-precision transmission system and precise wire feeding design, the temperature of a welding spot is remarkably reduced, heat damage and the pseudo soldering rate are reduced, and meanwhile the welding efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to spot welding equipment especially point welding equipment for circuit board production. BACKGROUND

[0002] In the field of electronic manufacturing, the quality of the solder joint directly affects the long-term reliability of the circuit board assembly. The traditional spot welding equipment adopts a single welding head time sequence control mode, and the single heat source is used for continuous welding of the solder pad and the device pin. However, with the popularity of high-density interconnection (HDI) board and miniaturized packaging, the heat accumulation effect in the welding process has become a core bottleneck restricting the consistency of the solder joint.

[0003] Specifically, when the single welding head is continuously welded, the contact thermal resistance between the welding needle and the solder pad will cause heat to continuously accumulate in the local area. Experiments show that when the solder joint temperature exceeds 150% of the solder liquidus temperature, the following chain problems will be caused: intermetallic compound (IMC) overgrowth, which significantly reduces the mechanical fatigue resistance of the solder joint; when the solder joint temperature gradient exceeds 50℃ / mm, the molten solder will form an asymmetric welding angle, causing a risk of false welding. The prior art attempts to alleviate the heat damage by optimizing the heat dissipation structure of the welding head or using low-temperature solder, but the former significantly increases the device volume and cost, and the latter sacrifices the mechanical strength of the solder joint (usually the tensile strength is reduced by 40%). See also the intermittent welding method, which can prolong the heat dissipation period, but the welding efficiency is reduced by more than 50%, which is difficult to meet the demand of modern production line rhythm. SUMMARY

[0004] In order to solve the above technical problems, the utility model provides a spot welding equipment for circuit board production.

[0005] In order to solve the above technical problems, the utility model adopts the technical scheme: a spot welding equipment for circuit board production, comprising a U-shaped double-electricity welding head support moving along the X axis and the Z axis through a first sliding group, two electric welding heads arranged side by side on the U-shaped double-electricity welding head support, and a welding wire conveying assembly moving along the X axis and the Y axis through a second sliding group, the welding wire conveying assembly conveying the welding wire along the Y axis direction.

[0006] The first sliding group comprises a drag chain sliding assembly moving along the X axis, the drag chain sliding assembly is connected with a first cylinder assembly moving along the Z axis, and the first cylinder assembly is connected with the U-shaped double-electricity welding head support.

[0007] The second sliding group comprises a second cylinder assembly moving along the X axis, the second cylinder assembly is connected with a third cylinder assembly moving along the Y axis, and the third cylinder assembly is connected with the welding wire conveying assembly.

[0008] Further, the drag chain sliding assembly comprises a first bottom plate, a first sliding rail arranged on the first bottom plate in the X-axis direction, and a drag chain, a first sliding block being slidingly arranged on the first sliding rail, the first sliding block being connected to a nut on a screw rod arranged in parallel with the first sliding rail, the screw rod being driven and connected by a first motor mounted on the first bottom plate, and the nut being connected to one end of the drag chain.

[0009] Further, the first cylinder assembly comprises a first cylinder connected to the first sliding block in the Z-axis direction and a first guide block, a piston of the first cylinder being connected to the center of the U-shaped double-electric welding head support, the U-shaped double-electric welding head support being slidingly arranged in the first guide block through a first guide column parallel to the first cylinder.

[0010] Further, the second cylinder assembly comprises a second bottom plate, a second sliding rail arranged on the second bottom plate in the X-axis direction, and a second sliding block slidingly arranged on the second sliding rail.

[0011] Further, the third cylinder assembly comprises a third cylinder connected to the second sliding block in the Y-axis direction and a third guide block, a piston of the third cylinder being connected to a support plate of the welding wire conveying assembly, the support plate being slidingly arranged in the third guide block through a third guide column parallel to the third cylinder.

[0012] Further, the welding wire conveying assembly comprises a first micro motor and a second micro motor connected to the support plate, a first roller shaft being connected to an output shaft of the first micro motor, a second roller shaft being connected to an output shaft of the second micro motor, and the first roller shaft and the second roller shaft being arranged to roll and clamp the welding wire on opposite sides of the welding wire, so that the welding wire is arranged in a guide hole formed in the support plate in the Y-axis direction.

[0013] The utility model provides a kind of circuit board spot welding equipment, by double welding head alternate welding, high-precision transmission system and accurate wire feeding design, significantly reduce welding point temperature, reduce thermal damage and false welding rate, while improve welding efficiency 75%, it is applicable to miniature component and automobile electronics etc. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is the structural schematic diagram of the utility model.

[0015] Figure 2 It is the structural schematic diagram of first sliding group.

[0016] Figure 3 It is the structural schematic diagram of second sliding group.

[0017] Figure 4 It is Figure 3 The structural enlarged schematic diagram of the part in the ring in it.

[0018] Figure 5 It is the installation position schematic diagram of U-shaped double-electric welding head support.

[0019] In the figure: 1, the first bottom plate; 2, the first sliding rail; 3, the drag chain; 4, the first sliding block; 5, the lead screw; 6, the nut; 7, the first motor; 8, the first cylinder; 9, the first guide block; 10, the U-shaped double-electric welding head support; 11, the first guide column; 12, the second bottom plate; 13, the second sliding rail; 14, the second sliding block; 15, the third cylinder; 16, the third guide block; 17, the support plate; 18, the third guide column; 19, the second micro motor; 20, the first roller shaft; 21, the second roller shaft; 22, the guide hole; 23, the first micro motor. DETAILED DESCRIPTION

[0020] The utility model will be made further detailed explanation in combination with the drawings and specific implementation.

[0021] A kind of spot welding equipment for circuit board production, including the U-shaped double-electric welding head support moved along X axis and Z axis by first sliding group, two electric welding heads are arranged in parallel on the U-shaped double-electric welding head support, and welding wire conveying assembly is moved along X axis and Y axis by second sliding group, welding wire conveying assembly conveys welding wire along Y axis direction;First sliding group includes the drag chain sliding assembly moved along X axis, the first cylinder assembly moved along Z axis is connected to drag chain sliding assembly, and the first cylinder assembly is connected to U-shaped double-electric welding head support;Second sliding group includes the second cylinder assembly moved along X axis, the third cylinder assembly moved along Y axis is connected to second cylinder assembly, and the third cylinder assembly is connected to welding wire conveying assembly.

[0022] Specifically, Figure 1The shown drag chain sliding assembly includes a first bottom plate 1, a first slide rail 2 and a drag chain 3 arranged along the X-axis direction on the first bottom plate 1, a first sliding block 4 is arranged on the first slide rail 2, the first sliding block 4 is connected to a nut 6 on a lead screw 5 arranged in parallel with the first slide rail 2, the lead screw 5 is driven and connected by a first motor 7 mounted on the first bottom plate 1, and the nut 6 is connected to one end of the drag chain 3. The design of the drag chain sliding assembly aims to realize high-precision and low-vibration movement of the welding head in the X-axis direction, and to synchronously manage the expansion and contraction of the cable. During operation, the first motor drives the lead screw to rotate, and it should be understood that the two ends of the lead screw are rotatably arranged on the first bottom plate through bearing supports, and the lead screw drives the nut to move along the axial direction of the lead screw. Since the nut is rigidly connected to the first sliding block, the sliding block can be precisely controlled when sliding along the first slide rail (repositioning accuracy ±0.01mm). The U-shaped double-welding-head support. Among them, one end of the drag chain is fixed to the nut, and the other end is anchored to the bottom plate. The corrugated structure expands / contracts synchronously with the movement of the sliding block, wraps the internal power supply line and air line, and avoids fatigue fracture of the cable due to repeated bending. Compared with the belt or gear and rack scheme, the lead screw-slide rail composite transmission has high rigidity (axial stiffness ≥ 200N / μm) and low reverse clearance (<5μm), which ensures that the welding head can still be stably close to the welding point when high-speed reversing (acceleration 2g), and supports the rapid response and thermal interval control required for double-welding-head alternating welding from the mechanical level.

[0023] Figure 2 and Figure 5 The shown first cylinder assembly includes a first cylinder 8 and a first guide block 9 connected to the first sliding block 4 along the Z-axis direction, the piston of the first cylinder 8 is connected to the center of the U-shaped double-welding-head support 10, and the U-shaped double-welding-head support 10 is slidably arranged in the first guide block 9 through a first guide column 11 parallel to the first cylinder 8. The first cylinder assembly realizes high-precision and anti-bias lifting movement of the U-shaped double-welding-head support in the Z-axis direction, and ensures uniform welding pressure and stable positioning. Specifically, when the piston rod of the first cylinder extends and retracts, it directly drives the center of the support to move vertically along the Z-axis, and the two parallelly arranged first guide columns and the first guide block form a sliding pair, which forcibly restricts the movement of the support along a single axis, eliminating the lateral deviation caused by the asymmetric force of the double-welding-head. The rigid linkage design of the guide column and the cylinder controls the pressure fluctuation when the welding head contacts the pad within ±2N, and simultaneously feedbacks the position signal in real time through the rodless sensing technology in the cylinder, which cooperates with the servo system to realize rapid lifting and precise hovering of the welding head, avoids heat conduction loss caused by too long contact of the welding needle, and provides time-synchronous physical basis for double-welding-head alternating operation, directly inhibiting the heat accumulation effect from the motion control dimension.

[0024] Figure 3 and Figure 4The second cylinder assembly includes a second base plate 12, a second slide rail 13 arranged on the second base plate 12 along the X-axis, and a second slide block 14 slidingly arranged on the second slide rail 13. The third cylinder assembly includes a third cylinder 15 and a third guide block 16 connected to the second slide block 14 along the Y-axis, a support plate 17 of the welding wire conveying assembly connected to a piston of the third cylinder 15, and the support plate 17 slidingly arranged in the third guide block 16 through a third guide column 18 parallel to the third cylinder 15. The second cylinder assembly and the third cylinder assembly can ensure the spatial alignment accuracy of the welding wire end and the welding point. The second cylinder assembly drives the welding wire conveying assembly to move along the X-axis in a large range through the linear cooperation of the second slide rail and the second slide block, and the third cylinder assembly controls the welding wire to be delivered along the Y-axis in a small distance through the precise guidance of the third guide column and the self-lubricating copper sleeve. When the system receives a welding coordinate instruction, the second cylinder assembly first coarsely positions the welding wire conveying assembly to the target area, and then the third cylinder drives the support plate to step along the Y-axis in a pulse mode, and the support plate is forced to be constrained to translate along a single axis only through the guide column, so that the transverse deviation caused by the welding wire tension fluctuation is eliminated. When the two axes are linked, the welding wire is always accurately close to the welding point molten pool during the alternate welding of the double welding heads, the uniformity of heat input is ensured from the dimension of the supply, and the local overheating or virtual welding defects caused by the deviation of the welding wire are avoided.

[0025] Figure 4 The welding wire conveying assembly includes a first micro motor 23 and a second micro motor 19 connected to the support plate 17, a first roller shaft 20 connected to an output shaft of the first micro motor 23, a second roller shaft 21 connected to an output shaft of the second micro motor 19, and the first roller shaft 20 and the second roller shaft 21 rolling and clamping the welding wire on opposite sides of the welding wire to make the welding wire pass through a guide hole 22 formed in the support plate 17 along the Y-axis. The welding wire conveying assembly can realize the directional delivery of the welding wire and ensure the stable supply of the molten solder and the consistency of the heat input. The first micro motor and the second micro motor respectively drive the first roller shaft and the second roller shaft, the surfaces of the first roller shaft and the second roller shaft are covered with a high-friction silicone layer, and the first roller shaft and the second roller shaft form symmetrical rolling clamping of the welding wire. When the system issues a wire feeding instruction, the double motors synchronously drive the roller shafts in a pulse mode to push the welding wire to accurately move forward along the guide hole in a meshing rolling manner. The sliding friction coefficient of the polytetrafluoroethylene coating on the inner wall of the guide hole is reduced to below 0.04, and the roller shaft pressure is closed-loop controlled, so that the welding wire delivery speed fluctuation is less than ±0.5%, the position repeatability is ±0.01 mm, the uneven supply caused by the welding wire vibration or slip is fundamentally eliminated, and the heat accumulation amplification effect caused by the volume fluctuation of the molten pool is avoided.

[0026] In summary, the utility model discloses a left and right parallel double welding head alternation welding, high rigidity drag chain - screw composite transmission and closed loop control wire feeding system, realize the comprehensive optimization of welding spot heat cumulative effect inhibition, welding efficiency promotion and process precision strengthening, it should be noted that, when the welding head alternation, control U type support along the X axis lateral deviation 5mm (deviation programmable adjustment), make the idle welding head away from the work area, avoid heat radiation superposition and the risk of physical collision, double welding head time-sharing pulse welding makes single point heat action interval extend to traditional mode's 2 times, peak temperature reduces 26% (from 315 to 235), effectively inhibit intermetallic compound excessive growth and PCB heat damage, X-Z / Y axis cooperative positioning system (repeat accuracy ± 0.01mm) combine symmetrical roller pressure wire feeding (speed fluctuation < ± 0.5%), guarantee the solder uniform wetting and molten pool stability, the virtual welding rate drops to 0.3% below, simultaneously, double welding head asynchronous working mode makes unit time welding point number promotion 75% (reaches 210 points / min), in solving the heat management problem, break through the efficiency bottleneck, especially suitable for miniaturization package and high frequency production line, give both high yield and low cost mass production demand.

[0027] The above embodiments are not a limitation of the utility model, and the utility model is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the technical solution of the utility model also fall within the protection scope of the utility model.

Claims

1. A spot welding device for circuit board production, characterized in that, It includes a U-shaped double welding head support that moves along the X and Z axes via a first sliding group, on which two welding heads are arranged side by side, and a welding wire conveying assembly that moves along the X and Y axes via a second sliding group, wherein the welding wire conveying assembly conveys welding wire along the Y-axis direction. The first sliding group includes a cable chain sliding assembly that moves along the X-axis, the cable chain sliding assembly being connected to a first cylinder assembly that moves along the Z-axis, and the first cylinder assembly being connected to the U-shaped double welding head bracket. The second sliding assembly includes a second cylinder assembly that moves along the X-axis, the second cylinder assembly being connected to a third cylinder assembly that moves along the Y-axis, and the third cylinder assembly being connected to the welding wire conveying assembly.

2. The spot welding equipment for circuit board production according to claim 1, characterized in that: The cable chain sliding assembly includes a first base plate, a first slide rail and a cable chain arranged along the X-axis on the first base plate, a first slider slidably arranged on the first slide rail, the first slider being connected to a nut on a lead screw arranged parallel to the first slide rail, the lead screw being driven by a first motor mounted on the first base plate, and the nut being connected to one end of the cable chain.

3. The spot welding equipment for circuit board production according to claim 2, characterized in that: The first cylinder assembly includes a first cylinder and a first guide block connected to the first slider along the Z-axis direction. The piston of the first cylinder is connected to the center of the U-shaped double welding head bracket. The U-shaped double welding head bracket is slidably disposed in the first guide block through a first guide post parallel to the first cylinder.

4. The spot welding equipment for circuit board production according to claim 1, characterized in that: The second cylinder assembly includes a second base plate, a second slide rail disposed on the second base plate along the X-axis direction, and a second slider slidably disposed on the second slide rail.

5. The spot welding equipment for circuit board production according to claim 4, characterized in that: The third cylinder assembly includes a third cylinder and a third guide block connected to the second slider along the Y-axis. The piston of the third cylinder is connected to the support plate of the welding wire conveying assembly. The support plate is slidably disposed in the third guide block by a third guide post parallel to the third cylinder.

6. The spot welding equipment for circuit board production according to claim 5, characterized in that: The welding wire feeding assembly includes a first micro motor and a second micro motor connected to a support plate. The output shaft of the first micro motor is connected to a first roller shaft, and the output shaft of the second micro motor is connected to a second roller shaft. The first roller shaft and the second roller shaft are arranged to roll and clamp the welding wire on opposite sides so that the welding wire passes through the guide hole opened in the support plate along the Y-axis direction.

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