Cooling water drop prevention system

Abstract

To provide a cooling water dropping prevention system for a spot welding machine, which can securely prevent dropping of cooling water from a welding gun tip during replacement of an electrode, without being affected by the scale and type of equipment.SOLUTION: A cooling water dropping prevention system 1 includes a first stop valve 2 provided in cooling water supply piping 15, and a second stop valve 3 provided in cooling water discharge piping 16. One end of first piping 4 is connected to the cooling water supply piping 15 on the more welding gun 11 side than the first stop valve 2. One end of second piping 5 is connected to the cooling water discharge piping 16 on the side further from the welding gun 11 than the second stop valve 3. One end of drain piping 6 is connected to the cooling water discharge piping 16 on the side farther from the welding gun 11 than the second stop valve 3. The other ends of the first piping 4, the second pipe 5, and the drain piping 6 are each connected to a pump unit 7, and the pump unit 7 discharges cooling water, sucked from the first piping 4 and the second piping 5, to the drain piping 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cooling water drop prevention system that prevents water for cooling an electrode from dropping from the tip of a welding gun of a spot welding machine when the electrode is removed from the tip of the welding gun during replacement of the electrode attached to the tip of the welding gun. [Background technology]

[0002] Conventionally, the electrode attached to the tip of the welding gun of a spot welding machine is replaced at a predetermined time. This electrode replacement work is completed by closing a stop valve provided in the cooling water passage to stop the circulation of the cooling water, removing the used electrode attached to the tip of the welding gun, and attaching a new electrode to the tip of the welding gun. However, when the used electrode is removed from the tip of the welding gun, there is a problem that the cooling water that has accumulated in a part of the cooling water passage falls from the opening of the tip of the welding gun and wets the body of the worker and other equipment.

[0003] In order to deal with this, for example, a cooling water drop prevention device disclosed in Patent Document 1 includes a cylinder having an opening at one end connected to a cooling water passage and a guide hole at the center of the other end, and a pair of fluid pressure cylinders arranged side by side in a direction perpendicular to the center line of the cylinder. Inside the cylinder, a partition plate is arranged to divide the inside of the cylinder into a cooling water passage side space and a guide hole side space, and a guide rod is slidably inserted into the guide hole and one end is connected to the partition plate. The other end of the guide rod is connected to the piston rod of the fluid pressure cylinder by a connecting bracket. When the electrode is removed from the tip of the welding gun, a stop valve provided in the cooling water passage stops the circulation of cooling water by the cooling unit, and the piston rod of the fluid pressure cylinder is extended to create a negative pressure in the space inside the cylinder on the cooling water passage side, thereby sucking the cooling water from the cooling water passage into the space on the cooling water passage side and preventing the cooling water from dropping from the opening at the tip of the welding gun. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 087959 Summary of the Invention [Problem to be solved by the invention]

[0005] However, cooling water drop prevention devices such as those in Patent Document 1 are unable to suck in more than a predetermined amount of cooling water into the space inside the cylinder. For example, if the type of welding gun is changed and made larger, there is a risk that all of the cooling water located on the welding gun side of the stop valve in the cooling water passage will not be sucked into the cylinder, and the cooling water will fall from the tip of the welding gun.

[0006] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a cooling water drop prevention system for a spot welder that can reliably prevent cooling water from dropping from the tip of a welding gun during electrode replacement work, regardless of the size or type of equipment. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention is characterized in that, when replacing the electrodes, the pump unit is used to repeatedly suck up the cooling water from the cooling water passage.

[0008] Specifically, the following solution has been implemented in a cooling water drop prevention system that prevents cooling water circulated through a cooling water supply passage and a cooling water discharge passage inside an electrode attached to the tip of a welding gun of a spot welding machine from dropping when the electrode is removed from the tip of the welding gun.

[0009] That is, the first invention is characterized in that it includes a first stop valve provided in a midway portion of the cooling water supply passage and capable of stopping the supply of cooling water to the inside of the electrode, a second stop valve provided in a midway portion of the cooling water discharge passage and capable of stopping the discharge of cooling water from the inside of the electrode, a first pipe having one end connected to the cooling water supply passage closer to the welding gun than the first stop valve, a second pipe having one end connected to the cooling water discharge passage closer to the welding gun than the second stop valve, a drain pipe having one end connected to the cooling water discharge passage on a side farther from the welding gun than the second stop valve, and a pump unit to which the other ends of the first pipe, second pipe, and drain pipe are connected and capable of discharging cooling water sucked up from the first and second pipes into the drain pipe.

[0010] moreover The pump unit includes a first connecting pipe connecting the other ends of the first pipe and the drain pipe, a second connecting pipe connecting the other ends of the second pipe and the drain pipe, a pair of first check valves provided in a middle part of the first connecting pipe and allowing cooling water to pass only from the first pipe side to the drain pipe side in the first connecting pipe, a pair of second check valves provided in a middle part of the second connecting pipe and allowing cooling water to pass only from the second pipe side to the drain pipe side in the second connecting pipe, a cylinder having a guide hole at one end, and an inner wall of the cylinder. the first connecting pipe having one end connected to the first check valves and the other end connected between the first check valves of the first connecting pipe; and a second connecting pipe having one end connected to the second space and the other end connected between the second check valves of the second connecting pipe. Effect of the Invention

[0011] In the first invention, when replacing an electrode, the circulation of cooling water inside the electrode is stopped by the first and second stop valves, and then the pump unit is started, so that the cooling water that accumulates on the welding gun side of the first stop valve in the cooling water supply passage is pumped up to the pump unit via the first piping, and the cooling water that accumulates on the welding gun side of the second stop valve in the cooling water discharge passage is pumped up to the pump unit via the second piping. Then, the cooling water pumped up by the pump unit is sequentially returned via the drain piping to the side of the cooling water discharge passage farther from the welding gun than the second stop valve, so that the cooling water returned to the cooling water discharge passage is discharged as it is without moving toward the welding gun by the second stop valve. In this way, when the electrode is removed from the tip of the welding gun, regardless of the type or size of the welding gun, all of the cooling water that accumulates in the entire area on the welding gun side of the first stop valve in the cooling water supply passage and all of the cooling water that accumulates in the entire area on the welding gun side of the second stop valve in the cooling water discharge passage can be removed.This makes it possible to reliably prevent cooling water from falling from the tip of the welding gun during electrode replacement work, regardless of the size or type of equipment.

[0012] AlsoWhen cooling water accumulates in the second space, the fluid pressure cylinder is operated to slide the guide rod to one side and move the partition plate so that the first space becomes wider, so that the two first check valves suck cooling water on the welding gun side of the cooling water supply passage closer to the first stop valve into the first space via the first piping, the first connecting pipe and the first suction and discharge pipe, while the two second check valves discharge cooling water accumulated in the second space via the second suction and discharge pipe, the second connecting pipe and the drain piping to the side of the cooling water discharge passage farther from the welding gun than the second stop valve. On the other hand, when cooling water is stored in the first space, by operating the fluid pressure cylinder to slide the guide rod to the other side and move the partition plate so that the second space becomes wider, the two second check valves suck the cooling water on the welding gun side of the cooling water discharge passage from the second stop valve into the second space via the second piping, the second connecting pipe, and the second suction and discharge pipe, while the two first check valves discharge the cooling water stored in the first space via the first suction and discharge pipe, the first connecting pipe, and the drain pipe to the side of the cooling water discharge passage farther from the welding gun than the second stop valve. In this way, by moving the position of the partition plate inside one cylinder back and forth, it is possible to alternately suck up the cooling water from the cooling water supply passage and the cooling water discharge passage and return the sucked up cooling water to the cooling water discharge passage, thereby making it possible to provide an efficient and inexpensive system. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a cooling water drop prevention system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic configuration diagram of a pump unit according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: It should be noted that the following description of the preferred embodiments is merely exemplary in nature.

[0015] 1 shows a spot welder 10 connected to a cooling water drop prevention system 1 according to an embodiment of the present invention. The spot welder 10 is used, for example, in an automobile production line to assemble a plurality of pressed parts (not shown) by spot welding, and includes a welding gun 11 that is substantially C-shaped when viewed from the front.

[0016] A pair of thin rod-shaped shanks 11a are provided at the tip of the welding gun 11 so as to face each other, and one shank 11a side portion is capable of moving toward and away from the other shank 11a.

[0017] An electrode 12 having a roughly bell shape when viewed from the front is removably attached to the tip of each shank 11a. With an object to be welded (not shown) placed between the two electrodes 12, one shank 11a side portion of the welding gun 11 is brought close to the other shank 11a to clamp the object to be welded between the two electrodes 12 and apply pressure. Then, a current is passed between the two electrodes 12 to spot weld the object to be welded.

[0018] A cooling unit 13 for cooling both electrodes 12 is connected to the welding gun 11 .

[0019] The cooling unit 13 comprises a unit body 14 having a pump 14a for circulating cooling water and a tank 14b for storing the cooling water, a cooling water supply pipe 15 (cooling water supply passage) extending from the unit body 14 to each electrode 12, and a cooling water discharge pipe 16 (cooling water discharge passage) extending from each electrode 12 to the unit body 14, and by operating the pump 14a, the cooling water in the tank 14b is circulated through the inside of each electrode 12 via the cooling water supply pipe 15 and the cooling water discharge pipe 16 to cool each electrode 12.

[0020] The cooling water drop prevention system 1 comprises a first stop valve 2 provided in the middle of the cooling water supply pipe 15 and a second stop valve 3 provided in the middle of the cooling water discharge pipe 16, and the first stop valve 2 is capable of stopping the supply of cooling water to the inside of the electrode 12, while the second stop valve 3 is capable of stopping the discharge of cooling water from the electrode 12.

[0021] One end of a first pipe 4 is connected to the cooling water supply pipe 15 on the welding gun 11 side of the first stop valve 2 .

[0022] On the other hand, one end of a second pipe 5 is connected to the cooling water discharge pipe 16 on the side closer to the welding gun 11 than the second stop valve 3, and one end of a drain pipe 6 is connected to the side of the cooling water discharge pipe 16 farther from the welding gun 11 than the second stop valve 3.

[0023] The other ends of the first pipe 4, the second pipe 5 and the drain pipe 6 are connected to a pump unit 7.

[0024] The pump unit 7 has a box-shaped main body case 70, and inside the main body case 70, as shown in Figure 2, a first connecting pipe 71 connecting the other end of the first pipe 4 to the other end of the drain pipe 6, and a second connecting pipe 72 connecting the other end of the second pipe 5 to the other end of the drain pipe 6 are arranged.

[0025] A pair of first check valves 73 are provided in the middle of the first connecting pipe 71, and are continuous in the direction in which the cooling water passes, allowing the cooling water to pass only from the first piping 4 side to the drain piping 6 side of the first connecting pipe 71.

[0026] A pair of second check valves 74 are provided in the middle of the second connecting pipe 72, and are continuous in the direction in which the cooling water passes, allowing the cooling water to pass only from the second piping 5 side to the drain piping 6 side of the second connecting pipe 72.

[0027] The interior of the main body case 70 is provided with a cylindrical body 75 having a guide hole 75a at one end, a partition plate 76 that divides the interior of the cylindrical body 75 into a first space S1 on one side in the direction of the cylindrical center line and a second space S2 on the other side, and a guide rod 77 that is slidably inserted into the guide hole 75a, and one end of the guide rod 77 is connected to the partition plate 76.

[0028] A double-acting air cylinder 78 is disposed on the other side of the cylinder centerline direction of the cylinder body 75 , and the air cylinder 78 is connected to an air supply source via a solenoid valve 79 .

[0029] The piston rod 78a of the air cylinder 78 is located on the center line of the cylindrical body 75 and is connected to the other end of the guide rod 77, so that the partition plate 76 and the guide rod 77 slide along the center line of the cylindrical body 75 by extending and retracting.

[0030] A first suction and discharge pipe 7a is arranged between the first connecting pipe 71 and the cylindrical body 75, the first end of which is connected to the first space S1 and the other end of which is connected between the two first check valves 73 in the first connecting pipe 71, and a second suction and discharge pipe 7b is arranged between the second connecting pipe 72 and the cylindrical body 75, the second end of which is connected to the second space S2 and the other end of which is connected between the two second check valves 74 in the second connecting pipe 72.

[0031] Next, the operation of the cooling water drop prevention system 1 according to the embodiment of the present invention will be described in detail.

[0032] When the electrode 12 is replaced in the above-mentioned welding gun 11, the cooling water drop prevention system 1 is started, and the control unit (not shown) starts the first stop valve 2 and the second stop valve 3 to stop the circulation of the cooling water inside the electrode 12, and then starts the pump unit 7 to operate the air cylinder 78. When the piston rod 78a of the air cylinder 78 extends, the partition plate 76 moves together with the guide rod 77 sliding to one side to widen the first space S1 while narrowing the second space S2. Then, the two first check valves 73 suck the cooling water on the welding gun 11 side of the first stop valve 2 in the cooling water supply pipe 15 into the first space S1 via the first pipe 4, the first connecting pipe 71, and the first suction and discharge pipe 7a.

[0033] Next, when the piston rod 78a of the air cylinder 78 contracts while cooling water is pooling in the first space S1, the partition plate 76 moves together with the guide rod 77 sliding to the other side, widening the second space S2 while narrowing the first space S1. Then, the two second check valves 74 suck the cooling water on the welding gun 11 side of the cooling water discharge pipe 16 from the second stop valve 3 into the second space S2 via the second pipe 5, the second connecting pipe 72, and the second suction and discharge pipe 7b, while the two first check valves 73 discharge the cooling water pooling in the first space S1 via the first suction and discharge pipe 7a, the first connecting pipe 71, and the drain pipe 6 to the side of the cooling water discharge pipe 16 farther from the welding gun 11 than the second stop valve 3.

[0034] Furthermore, when the piston rod 78a of the air cylinder 78 extends in a state where the cooling water is accumulated in the second space S2, the partition plate 76 moves together with the guide rod 77 sliding to one side, widening the first space S1 while narrowing the second space S2. Then, the two first check valves 73 suck the cooling water on the welding gun 11 side of the cooling water supply pipe 15 from the first stop valve 2 into the first space S1 via the first pipe 4, the first connecting pipe 71, and the first suction and discharge pipe 7a, while the two second check valves 74 discharge the cooling water accumulated in the second space S2 via the second suction and discharge pipe 7b, the second connecting pipe 72, and the drain pipe 6 to the side of the cooling water discharge pipe 16 farther from the welding gun 11 than the second stop valve 3.

[0035] In this manner, the pump unit 7 is capable of pumping up the cooling water from the first pipe 4 and the second pipe 5 and discharging it to the drain pipe 6 .

[0036] As described above, in the cooling water drop prevention system 1 in the embodiment of the present invention, the cooling water that accumulates on the welding gun 11 side of the first stop valve 2 in the cooling water supply piping 15 is pumped up to the pump unit 7 via the first piping 4, and the cooling water that accumulates on the welding gun 11 side of the second stop valve 3 in the cooling water discharge piping 16 is pumped up to the pump unit 7 via the second piping 5. The cooling water pumped up by the pump unit 7 is then sequentially returned via the drain piping 6 to the side of the cooling water discharge piping 16 farther from the welding gun 11 than the second stop valve 3, so that the cooling water returned to the cooling water discharge piping 16 is discharged as it is without moving toward the welding gun 11 by the second stop valve 3. Therefore, when removing the electrode 12 from the tip of the welding gun 11, all of the cooling water that accumulates in the entire area of ​​the cooling water supply pipe 15 on the welding gun 11 side from the first stop valve 2 and all of the cooling water that accumulates in the entire area of ​​the cooling water discharge pipe 16 on the welding gun 11 side from the second stop valve 3 can be removed regardless of the type and size of the welding gun 11, so that it is possible to reliably prevent the cooling water from dropping from the tip of the welding gun 11 during the replacement work of the electrode 12, regardless of the size and type of the equipment. Also, by moving the position of the partition plate 76 inside one cylinder 75 back and forth, it is possible to alternately suck up the cooling water from the cooling water supply pipe 15 and the cooling water discharge pipe 16 and return the sucked up cooling water to the cooling water discharge pipe 16, so that an efficient and inexpensive system can be provided.

[0037] In the embodiment of the present invention, the cooling water is pumped up from the cooling water supply pipe 15 and the cooling water discharge pipe 16 using the pump unit 7 that pumps up the cooling water by moving the partition plate 76 inside the cylinder 75 back and forth. However, other types of pump units may be used as long as they can pump up the cooling water from the first pipe 4 and the second pipe 5 and discharge the cooling water to the drain pipe 6.

[0038] Furthermore, in the embodiment of the present invention, the air cylinder 78 is used as the fluid pressure cylinder that activates the pump unit 7, but other types of fluid pressure cylinders may also be used. [Industrial Applicability]

[0039] The present invention is suitable for a cooling water drop prevention system that is connected to a spot welding machine and prevents cooling water for cooling an electrode from dropping from the tip of a welding gun when the electrode is removed from the tip of the welding gun during electrode replacement work. [Explanation of symbols]

[0040] 1. Cooling water drop prevention system 2 First stop valve 3. Second stop valve 4. First Pipe 5. Second piping 6 Drain piping 7 Pump Unit 7a First suction and discharge pipe 7b Second suction and discharge pipe 10 Spot welding machine 11 Welding gun 11a Shank 12 electrodes 15 Cooling water supply piping (cooling water supply passage) 16 Cooling water discharge piping (cooling water discharge passage) 71 First connecting pipe 72 Second connecting pipe 73 First check valve 74 Second check valve 75 Cylinder 75a Guide hole 76 Partition 77 Guide Rod 78 Air cylinder (fluid pressure cylinder) S1 1st space S2 2nd space

Claims

[Claim 1] A cooling water drop prevention system for preventing cooling water circulated through a cooling water supply passage and a cooling water discharge passage inside an electrode attached to a tip of a welding gun of a spot welding machine from dropping when the electrode is removed from the tip of the welding gun, comprising: a first stop valve provided in the middle of the cooling water supply passage and capable of stopping the supply of cooling water to the inside of the electrode; a second stop valve provided in the middle of the cooling water discharge passage and capable of stopping the discharge of the cooling water from inside the electrode; a first pipe having one end connected to the cooling water supply passage on a side closer to the welding gun than the first stop valve; a second pipe having one end connected to the cooling water discharge passage on a side closer to the welding gun than the second stop valve; a drain pipe having one end connected to a side of the cooling water discharge passage farther from the welding gun than the second stop valve; a pump unit to which the other ends of the first pipe, the second pipe and the drain pipe are connected and capable of drawing up cooling water from the first pipe and the second pipe and discharging it to the drain pipe, The pump unit includes a first connecting pipe connecting the other ends of the first pipe and the drain pipe, a second connecting pipe connecting the other ends of the second pipe and the drain pipe, a pair of first check valves provided continuously with a middle part of the first connecting pipe and allowing cooling water to pass only from the first pipe side to the drain pipe side in the first connecting pipe, a pair of second check valves provided continuously with a middle part of the second connecting pipe and allowing cooling water to pass only from the second pipe side to the drain pipe side in the second connecting pipe, a cylinder having a guide hole at one end, and a cylinder center line extending inside the cylinder. a first suction / discharge pipe having one end connected to the first space and the other end connected between both first check valves of the first connecting pipe, and a second suction / discharge pipe having one end connected to the second space and the other end connected between both second check valves of the second connecting pipe.

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