JP4215652B2 - Bolt welding method and welding apparatus therefor - Google Patents

Description

  The present invention relates to a bolt welding method and a welding apparatus for welding a bolt and a workpiece between upper and lower electrodes and welding them by energization.

  Conventionally, when a bolt is welded to a workpiece such as an iron plate, the workpiece is placed on the lower electrode of the welding electrodes facing up and down, and the bolt is supplied above the workpiece by a bolt supply unit or the like. A welding method is generally known in which a bolt and a workpiece are energized between upper and lower electrodes and the bolt is welded to the workpiece.

Thus, when a bolt is supplied and welded between the upper and lower electrodes of the bolt welding apparatus by the bolt supply unit, for example, as disclosed in Patent Document 1, the bolt is held so that the flange portion is downward. After the bolt supply unit is moved laterally and bolts are supplied between the upper and lower electrodes of the bolt welding apparatus, the entire bolt supply unit is moved upward to open the upper part of the bolt welding apparatus below the upper electrode. A shaft portion of the bolt is inserted into a hole portion to be held, and the bolt is held on the upper electrode by a magnet disposed in the hole portion, so that the bolt is positioned and welded to the workpiece. .
JP 2001-321156 A

  However, in the method of moving the entire bolt supply unit in the lateral direction and the upward direction as in Patent Document 1, the mechanism for that is complicated, and the cost of the apparatus is increased. Further, as described above, when the bolt shaft is inserted into the hole of the upper electrode by moving the entire bolt supply unit, the position of the bolt supplied by the bolt supply unit is accurately set to the position of the hole of the upper electrode. Therefore, it is necessary to finely adjust the position of the bolt supply unit.

  Furthermore, since not only the upper electrode but also the bolt held by the upper electrode becomes hot during bolt welding, there is a problem that if the welding is performed with the bolt attached to the magnet, the magnet is likely to deteriorate due to the heat. There is also.

  The present invention has been made in view of these points, and the object of the present invention is to devise a bolt holding structure by the upper electrode in a bolt welding method and welding apparatus for welding a bolt to a workpiece, An object of the present invention is to reliably hold a bolt with a simple structure and to prevent deterioration of a magnet to which the bolt is attached.

In order to achieve the above object, in the solution means of the present invention, a guide pin is inserted into a through hole provided in the upper electrode so as to be movable up and down, and a magnet is disposed at a lower end portion thereof. Then, by lowering the guide pin below the upper electrode and lifting it with the bolt attached to the magnet, the bolt is held on the upper electrode with a simple configuration. The magnet at the lower end of the guide pin is separated from the bolt and the upper electrode while being sandwiched between them, so that the heat transfer to the magnet is reduced.

Specifically, according to the first aspect of the present invention, a workpiece and a bolt to be welded thereto are supplied between a pair of vertically opposed electrodes, and the workpiece is placed on the lower electrode, while the upper electrode is placed. A bolt welding method in which a shaft portion of a bolt is inserted into a hole opening below and the bolt is held by the upper electrode, and then the bolt and the work are sandwiched between the upper and lower electrodes to be energized and welded. Assumption. A hole opening below the upper electrode is used as a vertical through hole, and a guide pin is inserted into the through hole so as to move up and down, and a magnet is disposed at the lower end of the guide pin. In addition, first, the bolt supplied between the upper and lower electrodes is attached to the magnet at the lower end of the guide pin that protrudes downward from the upper electrode, and then the guide pin is moved upward, The bolt is held on the upper electrode by inserting the shaft portion of the bolt into the through hole of the upper electrode. Then, in such a state that the upper electrode holds the bolt, the upper and lower electrodes are brought close to each other, and the bolt and the work are sandwiched therebetween, and the guide pin is moved upward relative to the upper electrode. is moved, such that heat generated in the upper electrode during the bolt welding is not transmitted to the magnet, performing welding in a state in which the magnet is spaced from the bolt and the upper electrode.

  By this method, if a magnet is provided at the lower end of the guide pin that is inserted through the through hole of the upper electrode so as to move up and down, and a bolt is supplied between the upper and lower electrodes, By attaching a bolt to the magnet at the lower end portion of the guide pin that protrudes downward, and moving the guide pin upward so that the shaft portion of the bolt is inserted into the through hole, the shaft portion of the bolt Is accommodated in the through hole of the upper electrode in a state of adhering to the magnet. Therefore, the bolt can be reliably positioned and held on the upper electrode with a simple configuration without moving the entire bolt supply unit for supplying the bolt between the upper and lower electrodes upward.

  Further, since the bolt shaft portion is inserted into the through hole of the upper electrode, the bolt does not protrude greatly below the upper electrode. For example, when the workpiece or the bolt supply unit is moved, the bolt collides with the bolt. Can be prevented from falling.

Further, when the bolt and the work are sandwiched between the upper and lower electrodes and the welding is performed by energizing between the electrodes, the magnet at the lower end of the guide pin is separated from the bolt and the upper electrode . heat is not transmitted to the front SL magnet, which makes it possible to suppress deterioration of the magnet caused by heat at the time of bolt welding.

  As described above, the bolt can be accurately and reliably arranged between the upper and lower electrodes with a simple configuration, and deterioration of the magnet due to heat during bolt welding can be suppressed.

  According to a second aspect of the invention, in the first aspect of the invention, when the bolt is held by the upper electrode, the guide pin is moved upward to a predetermined position so that the flange portion of the bolt does not contact the lower end of the upper electrode. Move to.

  Thereby, the guide pin stops at a predetermined position where the flange portion of the bolt does not contact the lower end of the upper electrode, so that the flange portion of the bolt does not collide with the lower end of the upper electrode when the guide pin is raised. The bolt can be prevented from dropping due to impact.

  According to a third aspect of the present invention, a workpiece and a bolt to be welded to the workpiece are supplied between a pair of vertically opposed electrodes, and the workpiece is placed on the lower electrode, while being opened below the upper electrode. Assuming a bolt welding apparatus in which a shaft portion of a bolt is inserted into a hole and the bolt is held by the upper electrode, and then the bolt and the work are sandwiched between the upper and lower electrodes to be energized and welded. To do. The hole opening below the upper electrode is a through-hole penetrating in the vertical direction. The through-hole is disposed at a lower end of the guide pin and a guide pin disposed so as to be movable up and down. And a magnet for attaching the bolt, a guide pin moving means for moving the guide pin in the vertical direction, and a movement control means for controlling the movement of the guide pin by the guide pin moving means.

  If the bolt welding apparatus according to claim 3 is used, the movement control means moves the guide pin below the upper electrode to attach the bolt to the magnet at the lower end of the guide pin, and in this state the guide By moving the pin upward, the shaft portion of the bolt can be inserted into the through hole of the upper electrode. When the bolt and workpiece are sandwiched and welded between the upper and lower electrodes, the guide pin is raised by the movement control means, and the magnet at the lower end can be separated from the bolt. Therefore, the bolt welding apparatus according to claim 3 can automatically execute the method of the invention of claim 1, and the effects of the invention can be obtained very easily.

More specifically, the movement control means attaches a bolt to the magnet at the lower end of the guide pin that protrudes downward from the upper electrode, and then the shaft portion of the bolt is inserted into the through hole of the upper electrode. The first movement control unit that moves the guide pin upward to hold the bolt on the upper electrode and the upper and lower electrodes approach each other with the upper electrode holding the bolt, After the bolt and workpiece are sandwiched between the upper and lower electrodes, before the bolt is welded, the guide pin is moved upward relative to the upper electrode to generate heat generated by the upper electrode during bolt welding. as but not transmitted to the magnet, it has good Assuming and a second movement control section for separating the magnet from the bolt and the upper electrode.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a hollow portion is formed at the lower end portion of the guide pin, and the magnet is embedded in the hollow portion. Thereby, since the magnet for attaching the bolt is covered with the guide pin, the influence of heat upon welding to the magnet can be further reduced, and deterioration of the magnet due to heat can be surely prevented. .

According to invention of Claim 1, after making a bolt adhere to the magnet of the lower end part of the guide pin inserted so that a vertical movement is possible in the through-hole of an upper electrode, this guide pin is raised, and the axial part of a bolt is said upper side. By inserting the electrode into the through hole of the electrode, the bolt can be held accurately and reliably with a simple structure. Moreover, since the magnet is separated from the bolt and the upper electrode before bolt welding, it is possible to prevent deterioration of the magnet due to heat during welding.

  According to the invention of claim 2, the bolt can be prevented from falling by raising the guide pin to a predetermined position where the flange portion of the bolt does not contact the lower end of the upper electrode. The bolt can be held more accurately and reliably.

According to the bolt welding apparatus according to the invention of claim 3 Symbol placement, by performing a method of the claims 1 invention, it is possible to obtain the effect very easily.

According to invention of Claim 4 , since the magnet for hold | maintaining a bolt was arrange | positioned in the cavity part provided in the lower end part of a guide pin, deterioration of a magnet can be prevented more reliably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

-Overall configuration-
FIG. 1 shows a schematic configuration of a bolt welding apparatus A according to an embodiment of the present invention. The bolt welding apparatus A energizes both electrodes with a bolt X and a workpiece W sandwiched between upper and lower electrodes. The bolt X is welded to the workpiece W, and the bolt welder 1 having the upper and lower electrodes and the bolt X supplied from the bolt aligner 4 are connected between the upper and lower electrodes of the bolt welder 1. And a controller 3 that controls the bolt welding machine 1 and the bolt supply unit 2.

  The bolt welder 1 includes an upper electrode unit 10 and a lower electrode unit 40 disposed on the main body 1a so as to face each other in the vertical direction. The bolt X and the workpiece W are sandwiched between the upper electrode 11 (upper electrode) and the lower electrode 41 (lower electrode) respectively disposed in the lower electrode unit 40.

  The upper electrode unit 10 is configured such that the entire unit moves up and down by an upper electrode cylinder 14 disposed on the upper portion of the bolt welder 1, and a movable portion 1 b that moves up and down by the upper electrode cylinder 14. A substantially cylindrical upper holder 12 fixed via an upper mounting member 1c, a substantially cylindrical upper electrode 11 disposed at the lower end thereof and energized during welding, and connected to the upper end of the upper holder 12 Then, a guide pin adjusting bracket 13 for adjusting the protruding length of a guide pin 15 to be described later, and a lower end portion of the guide pin adjusting bracket 13 are connected and fixed to relatively move the guide pin 15 up and down. It consists of a two-stage upper guide pin cylinder 30 (guide pin moving means).

  When the bolt X is welded to the work W, the upper electrode unit 14 is moved downward by the upper electrode cylinder 14 to sandwich the bolt X and the work W between the upper and lower electrodes 11 and 41. When supplying the bolt X and the workpiece W to the bolt welder 1, the upper electrode unit 14 is moved upward by the upper electrode cylinder 14 so that the bolt X and A work space for supplying and discharging the work W is provided.

  As shown in FIG. 2A, the upper electrode 11 and the upper holder 12 are provided with through holes 11a and 12a penetrating in the vertical direction so as to communicate with each other. In these through holes 11a and 12a, a guide pin 15 is provided which is connected to a piston 34 of an upper guide pin cylinder 30 to be described later and can move up and down in the through holes 11a and 12a. An insulator 11b for insulating the guide pin 15 and the like from the upper electrode 11 is disposed on the inner periphery of the through hole 11a.

  The guide pin 15 has a relatively large diameter resin rod portion 15a and a small diameter stainless steel disposed at one end of the rod portion 15a, as shown in an enlarged view in part in FIG. The pin portion 15b is formed with a hollow portion 15d at a lower end portion 15c of the pin portion 15b. A magnet 16 is disposed in the hollow portion 15d. As will be described in detail later, when the bolt X is supplied between the upper and lower electrodes 11 and 41, the lower end portion 15c of the guide pin 15 is the upper portion. Projecting downward from the electrode 11, the shaft portion Xa of the bolt X is attached to the magnet 16 of the lower end portion 15c.

  As will be described later, the pin portion 15b needs to protect the internal magnet 16 from the heat generated during bolt welding, and is preferably made of stainless steel in consideration of heat insulation and durability. Any material may be used without limitation.

  As shown in FIGS. 1 to 3, the guide pin adjusting bracket 13 has a substantially cylindrical shape with different outer diameters at the upper part and the lower part thereof. A large-diameter holder insertion hole 13a is formed, while a small-diameter cylinder insertion hole 13b is formed on the upper side. Here, the lower portion of the guide pin adjusting bracket 13 surrounding the lower portion of the holder insertion hole 13a is divided into two halved members each having a half cylinder. Are integrally formed to form a main body portion 13d, and the other half member 13e is assembled thereto. Accordingly, the upper holder 12 is connected and fixed to the guide pin adjusting bracket 13 by sandwiching the upper end portion of the upper holder 12 between the two members 13d and 13e and fastening the members 13d and 13e with bolts 13h. can do. With this configuration, the upper holder 12 is connected to the holder insertion hole 13a so that its insertion length can be changed, and the vertical position of the upper holder 12 can be adjusted. The protruding length when the guide pin 15 protrudes below the upper electrode 11 disposed at the lower end of the upper holder 12 can be adjusted.

  On the other hand, in the cylinder insertion hole 13b, a screw portion formed on the outer periphery of the lower end portion of the upper guide pin cylinder 30 is screwed to a screw portion formed on the inner surface of the cylinder insertion hole 13b. The upper guide pin cylinder 30 and the guide pin adjusting bracket 13 are connected and fixed. As a result, the upper holder 12, the guide pin adjusting bracket 13, and the upper guide pin cylinder 30 are joined together in the axial direction in order.

  The guide pin adjusting bracket 13 is provided with an air hole 13c communicating with the through holes 11a and 12a through the holder insertion hole 13a. A tube or the like (not shown) is provided in the air hole 13c. Compressed air is supplied through this. Then, by supplying compressed air to the air holes 13c for a predetermined time after the bolt welding (for example, approximately 0.2 seconds), the spatter accumulated in the through holes 11a and 12a at the time of welding is blown downward. ing.

  As shown in the schematic diagram of FIG. 4, the upper guide pin cylinder 30 has a configuration in which two substantially cylindrical cylinders are connected to each other vertically, and two independent cylinder chambers 31 and 32 are provided. The cylinder chambers 31 and 32 are arranged in two upper and lower pressure chambers 31a and 31b by piston heads 33a and 34a formed on the upper portions of the cylinder pistons 33 and 34, respectively. And 32a and 32b.

  Further, the rod portion 33b extending below the upper cylinder piston 33 is disposed so that the lower portion thereof penetrates the partition wall 35 that partitions the cylinder chambers 31 and 32 and projects into the lower cylinder chamber 32. Has been. As a result, when the upper cylinder piston 33 moves downward or the lower cylinder piston 34 moves upward and the cylinder pistons 33 and 34 come into contact with each other, one cylinder piston 33 Will work as. That is, in a state where the cylinder pistons 33 and 34 are not in contact with each other, the lower cylinder piston 34 moves up and down according to the pressure in the pressure chambers 32a and 32b, while the cylinder pistons 33 and 34 move together. In the abutted state, the lower cylinder piston 34 is integrated with the upper cylinder piston 33 to move up and down in accordance with the pressure in the pressure chambers 31a, 31b, 32a and 32b.

  Further, the upper guide pin cylinder 30 has an inlet port 30a, 30b, 30c for injecting compressed air into the pressure chambers 31a, 31b, 32a, 32b in the cylinder, respectively at the upper end side, substantially the center, and the lower end side. The inlet 30 a is connected to the upper pressure chamber 31 a of the upper cylinder chamber 31, and the inlet 30 b is connected to the lower pressure chamber 31 b and the lower cylinder chamber 32 of the upper cylinder chamber 31. The inlet 30c communicates with the upper pressure chamber 32a and the lower pressure chamber 32b of the lower cylinder chamber 32, respectively. Thus, by controlling the air pressure supplied to the inlets 30a, 30b, 30c, respectively, the air pressure in the pressure chambers 31a, 31b, 32a, 32b is changed, and the two cylinder pistons 33, 34 are moved. Each can be moved up and down.

  Specifically, compressed air having an equal pressure is supplied to the inlets 30b and 30c by a compressed air supply device (not shown), while compressed air having a higher pressure is supplied to the inlet 30a. It has become so. For example, when the supply of compressed air to the inlet 30c is stopped and the atmosphere is opened, the lower pressure chamber 32b of the lower cylinder chamber 32 is opened to the atmosphere and the pressure becomes lower than the upper pressure chamber 32a. While the lower cylinder piston 34 moves downward (indicated by an arrow in FIG. 4), the pressure in the upper pressure chamber 31a and the lower pressure chamber 31b of the upper cylinder chamber 31 does not change, so the upper cylinder piston The position of 33 will not change.

  As shown in FIGS. 2 and 4, the lower end of the lower cylinder piston 34 is connected and fixed to the upper end of the above-described guide pin 15, so that the lower cylinder piston 34 moves up and down. The guide pin 15 can be moved up and down.

  Further, as shown in FIGS. 1, 2 and 4, the upper guide pin cylinder 30 has switches 36 to 39 for detecting the vertical positions of cylinder pistons 33 and 34 disposed therein. Is provided. These switches 36 to 39 are configured to output a signal when the piston heads 33a and 34a of the cylinder pistons 33 and 34 come close to each other by a predetermined amount or more, and the controller outputs a piston head according to a signal from the switches 36 to 39. The positions of 33a and 34a are detected, and the bolt welding apparatus A to be described later is controlled based on the position information.

  As shown in FIG. 1, the lower electrode unit 40 includes a substantially cylindrical lower holder 42 fixed to the main body 1a of the bolt welder 1 via a lower mounting member 1d, and an upper end of the lower holder 42. What is comprised by the substantially cylindrical lower electrode 41 arrange | positioned facing the said upper electrode 11, is different from the above-mentioned upper electrode unit 10, and is being fixed to the main-body part 1a of the bolt welding machine 1 It is.

  The bolt supply unit 2 is fixed to an L-shaped bar 17 provided in the bolt welder 1, and receives a bolt X supplied from a bolt aligner 4 through a tube 20 as shown in FIG. And a cylinder portion 22 for moving the bolt holder 21 between the upper and lower electrodes 11 and 41 of the bolt welding machine 1.

  As shown in an enlarged view in FIG. 5B, the bolt holder 21 is provided with a bolt holding hole 21a having a substantially circular cross section that opens upward, and the upper portion of the bolt holding hole 21a is located upward. It is formed in a mortar shape that spreads out. Then, the bolt X carried from the bolt aligner 4 through the tube 20 is supplied into the bolt holding hole 21a with the flange portion Xb facing downward. An air hole 21b for venting air is provided on the bottom surface of the bolt holding hole 21a, so that the bolt X is not obstructed by the air in the bolt holding hole 21a and the bolt holding hole 21a. It can be smoothly dropped on the bottom of the.

  The cylinder portion 22 is fixed to the L-shaped bar 17 through a fixing bracket 23, and a piston (not shown) disposed in the cylinder and a cylinder rod 24 integrally connected to the tip thereof are pneumatically connected. It is configured to move in the axial direction. That is, the cylinder rod 24 is in an initial position in which a piston integral with the rod 24 is inserted to the back of the cylinder, and from this state, the bolt holder 21 is connected to the upper and lower electrodes 11, 41 of the bolt welder 1. It can be extended until it is in between. Here, the initial position of the cylinder rod 24 is detected by a signal from a switch 25 provided at the rear end of the cylinder portion 22, while the bolt holder 21 is positioned between the upper and lower electrodes 11 and 41. If so, the position of the cylinder rod 24 at that time is detected by a signal from a switch 26 provided substantially at the center of the cylinder portion 22, and the controller 3 controls the bolt welding apparatus A based on these signals. It is supposed to be.

  The controller 3 is for controlling the bolt welding apparatus A at the time of bolt welding, and detects each operation of the bolt welding apparatus A based on signals from the switches 25, 26, 36 to 39, as will be described later. Operation control of the bolt welder 1 and the bolt supply unit 2, control of ON / OFF of compressed air supplied to the inlets 30a, 30b, and 30c of the upper guide pin cylinder 30 are performed. .

  Here, by controlling the supply of compressed air to the inlets 30a, 30b, 30c of the upper guide pin cylinder 30, the cylinder pistons 33, 34 and the guide pin 15 in the upper guide pin cylinder 30 are moved up and down. The controller 3 is a movement control means.

-Operation of bolt welding device A during bolt welding-
Next, operation | movement of the bolt welding apparatus A in the case of welding the volt | bolt X to the workpiece | work W is demonstrated based on FIGS.

  First, as shown in FIG. 6, the bolt X is supplied from the bolt aligner 4 to the bolt holder 21 of the bolt supply unit 2 through the tube 20. At this time, the bolt X is supplied to the bolt holding hole 21a of the bolt holder 21 so that the flange portion Xb is directed downward. At this time, the compressed air is being supplied to the inlets 30a, 30b, 30c of the upper guide pin cylinder 30, and the piston head 34a of the lower cylinder piston 34 of the upper guide pin cylinder 30 is switched to the switch 38. This is a state detected by a signal from.

  And after the said bolt X is supplied to the bolt holding hole 21a of the bolt holder 21, as shown in FIG. 7, in the cylinder part 22 of the bolt supply unit 2, the cylinder rod 24 is extended to an axial direction by air pressure, The bolt holder 21 is moved between the upper and lower electrodes 11 and 41 of the bolt welder 1. When the bolt X in the bolt holder 21 reaches the axis Z connecting the upper and lower electrodes 11, 41, this is detected by a signal from the switch 26 of the cylinder portion 22, and the cylinder rod 24 Stop the operation.

  Thereafter, as shown in FIG. 8, the supply of compressed air to the inlet 30c on the lower end side of the upper guide pin cylinder 30 is stopped and released to the atmosphere, whereby the lower cylinder chamber 32 in the cylinder 30 is opened. The pressure in the lower pressure chamber 32b is reduced. Thereby, the pressure in the upper pressure chamber 32a becomes larger than the lower pressure chamber 32b, and the lower cylinder piston 34 in the upper guide pin cylinder 30 moves downward. Accordingly, the guide pin 15 integrated with the lower cylinder piston 34 also moves downward, so that the lower end of the guide pin 15 approaches the shaft portion Xa of the bolt X, and the tip of the pin portion 15a of the guide pin 15 The shaft portion Xa of the bolt X is attached to the magnet 16 arranged in the above. At this time, the piston head 34a of the lower cylinder piston 34 is detected by a signal from the switch 39 of the upper guide pin cylinder 30.

  Next, as shown in FIG. 9, approximately 1 second after the piston head 34a of the lower cylinder piston 34 is detected by the signal from the switch 39, the compression to the inlet 30b of the upper guide pin cylinder 30 is performed. While the supply of air is stopped and the atmosphere is released, compressed air is supplied to the inlet 30c, so that the inside of the lower pressure chamber 32b is lower than the upper pressure chamber 32a of the lower cylinder chamber 32 in the cylinder 30. The lower cylinder piston 34 is moved upward by increasing the pressure. As a result, the guide pin 15 and the bolt X attached to the lower end of the guide pin 15 also move upward, and the shaft portion Xa of the bolt X is inserted into the through hole 11a of the upper electrode 11 so that the bolt X Is held by the upper electrode 11.

  In this way, the shaft Xa of the bolt X can be moved only by moving the guide pin 15 upward with the shaft Xa of the bolt X attached to the magnet 16 of the lower end 15c of the guide pin 15. It can be easily inserted into the through hole 11 a of the upper electrode 11.

  Further, by inserting the shaft portion Xa of the bolt X into the through hole 11a of the upper electrode 11, positioning of the bolt X with respect to the upper electrode 11 is performed, and even when the bolt X is held on the upper electrode 11, Since the bolt X does not protrude greatly downward, interference with the workpiece W or the like can be prevented. Therefore, the bolt X can be accurately and reliably held on the upper electrode 11.

  Here, as described above, when the supply of compressed air to the inlet 30b is stopped, the stop position of the lower cylinder piston 34 is determined by the flange portion Xb of the bolt X attached to the lower end of the guide pin 15. It is a position (predetermined position) that is not in contact with the lower end of the upper electrode 11 and has a predetermined interval d. By stopping the guide pin 15 at this position, the bolt X does not collide with the lower end of the upper electrode 11 when the bolt X is raised, and the bolt X is prevented from dropping due to an impact at the time of collision. can do.

  When the flange Xb of the bolt X attached to the lower end of the guide pin 15 reaches the position of the predetermined distance d from the lower end of the upper electrode 11, the flange 38 is located at the position of the switch 38 of the upper guide pin cylinder 30. The piston head 34a of the lower cylinder piston 34 arrives, and the switch 38 outputs a signal.

  As described above, the supply of compressed air to the inlet 30c of the upper guide pin cylinder 30 is stopped, so that the lower end portion 15c of the guide pin 15 protrudes downward from the upper electrode 11, and the magnet of the lower end portion 15c. 16 with the shaft portion Xa of the bolt X attached thereto, and in that state, while supplying compressed air to the inlet 30c of the upper guide pin cylinder 30, the supply of compressed air to the inlet 30b is stopped, The procedure of moving the guide pin 15 upward and inserting the shaft portion Xa of the bolt X into the through hole 11a of the upper electrode 11 corresponds to the first movement control portion of the movement control means.

  Then, after detecting the piston head 34a of the lower cylinder piston 34 by a signal from the switch 38 of the upper guide pin cylinder 30, the bolt holder 21 of the bolt supply unit 2 reaches its initial position as shown in FIG. The cylinder rod 24 is shrunk so as to return. Then, after detecting that the cylinder rod 24 has returned to its initial position by a signal from the switch 25 (see FIG. 5) of the cylinder portion 22, the workpiece W is placed on the lower electrode 41 as shown in FIG. The upper electrode unit 10 is moved downward by the upper electrode cylinder 14. As a result, the bolt X held by the upper electrode 11 is sandwiched between the upper and lower electrodes 11 and 41 together with the workpiece W and is pressed.

  Thus, when the bolt X is sandwiched between the upper and lower electrodes 11 and 41, the guide pin 15 and the cylinder pistons 33 and 34 are connected to the flange portion Xb of the bolt X as shown in FIG. The piston head 33a of the upper cylinder piston 33 reaches the position of the switch 37 of the upper guide pin cylinder 30 because it is pushed by the predetermined distance d with respect to the upper electrode 11 and moves upward. Is output. After approximately 1 second, as shown in FIG. 12, the supply of compressed air to the inlet 30a of the upper guide pin cylinder 30 is stopped, and the upper pressure of the upper cylinder chamber 31 communicating with the inlet 30a is stopped. By reducing the pressure in the chamber 31a, the upper cylinder piston 33 and the lower cylinder piston 34 are integrally moved upward.

  As described above, after the bolt X is sandwiched between the upper and lower electrodes 11 and 41, the guide pin 15 is lifted so that the lower end portion 15c of the guide pin 15 is attached to the axis of the bolt X before bolt welding. It can be separated from the part Xa. As a result, heat generated in the upper electrode 11 during bolt welding is not transmitted to the magnet 16 disposed on the lower end portion 15c of the guide pin 15 via the bolt X or the like, thereby suppressing deterioration of the magnet 16 due to heat. be able to. Since the lower end portion 15c of the guide pin 15 is also separated from the upper electrode 11 as shown in FIG. 12, the heat of the upper electrode 11 itself is not transmitted.

  Moreover, since the magnet 16 is arranged in the stainless steel guide pin 15 as described above, the influence of heat generated during bolt welding can be further reduced, and deterioration can be suppressed more effectively. Can do.

  When the cylinder pistons 33 and 34 are moved upward as described above, the cylinder pistons 33 and 34 are moved upward to a position where the cylinder head 33a of the upper cylinder piston 33 is detected based on a signal from the switch 36 of the upper guide cylinder 30. Move to. At this time, a new bolt X ′ is supplied from the bolt aligner 4 to the bolt holder 21 of the bolt supply unit 2 through the tube 20.

  Here, in a state where the bolt X and the workpiece W are sandwiched between the upper and lower electrodes 11 and 41, before the bolt welding, the supply of compressed air to the inlet 30a of the upper guide pin cylinder 30 is stopped, thereby The procedure of moving the guide pin 15 upward to move the magnet 16 at the lower end 15c of the guide pin 15 away from the bolt X corresponds to the second movement control unit of the movement control means.

  After the cylinder head 34 of the upper cylinder piston 33 is detected by a signal from the switch 36, that is, the bolt X is sandwiched between the upper and lower electrodes 11 and 41, and the lower end of the guide pin 15 is In a state of being separated from the shaft portion Xa of the bolt X, the upper and lower electrodes 11 and 41 are energized to weld the bolt X to the workpiece W.

  After the bolt welding, the upper electrode unit 10 is moved upward by the upper electrode cylinder 14, while compressed air is supplied to the inlets 30a and 30b of the upper guide pin cylinder 30, respectively. The 30 cylinder pistons 33 and 34 each return to the initial state as shown in FIG. 6, and the bolt welding operation is completed.

  Therefore, according to the above-described embodiment, the guide pin 15 is inserted into the through hole 11a of the upper electrode 11 so as to be vertically movable, the magnet 16 is disposed at the lower end portion 15c of the guide pin 15, and the upper and lower When the bolt X is supplied between the electrodes 11 and 41, the lower end portion 15c of the guide pin 15 is protruded downward from the upper electrode 11, and the bolt X is attached to the magnet 16 of the guide pin 15. In this state, the guide pin 15 is moved upward, and the shaft portion Xa of the bolt X is inserted into the through hole 11a of the upper electrode 11 so that the bolt X is placed at a predetermined position of the upper electrode 11 with a simple configuration. Can be held accurately and reliably.

  In addition, before the bolt X is clamped between the upper and lower electrodes 11 and 41 and the bolt is welded, the magnet 16 at the lower end of the guide pin 15 is separated from the shaft portion Xa of the bolt X. Since the heat generated during welding is not transmitted from the bolt X to the magnet 16 of the guide pin 15, the deterioration of the magnet 16 can be prevented.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiment, but includes various other configurations. That is, in the above-described embodiment, the guide pin 15 is moved up and down by the upper guide pin cylinder 30 for air pressure control. However, the present invention is not limited to this, and the guide pin 15 is moved up and down like a drive mechanism such as a motor. Any driving mechanism that can be moved may be used.

  As described above, the bolt welding method and the welding apparatus thereof according to the present invention can accurately and reliably position the bolt between the upper and lower electrodes with a simple configuration, and can hold the bolt on the upper electrode. Since deterioration of a magnet can be prevented, it is particularly useful when, for example, spot welding a bolt to a workpiece.

It is a front view showing a schematic structure of a bolt welding device concerning an embodiment of the present invention. (A) The front view which shows schematic structure of the whole upper electrode unit (b) It is an expanded sectional view which expands the pin part of a guide pin and shows the cross section. It is (a) front view (b) bottom view of the bracket for guide pin adjustment. It is the schematic diagram which showed typically the schematic structure of the upper guide pin cylinder. It is the front view which shows schematic structure of the whole (a) bolt supply unit, (b) It is the elements on larger scale which expand and show a bolt holder. It is a figure which shows the state in which the volt | bolt was supplied to the volt | bolt supply unit. It is a figure which shows the state in which the volt | bolt was supplied between the upper and lower electrodes by the volt | bolt supply unit. It is a figure which shows the state which a guide pin descend | falls and attaches a volt | bolt to the lower end. It is a figure which shows the state which the guide pin raised and hold | maintained the volt | bolt to the upper electrode. It is a figure which shows the state which the bolt holder of the bolt supply unit returned to the initial position. It is a figure which shows the state which clamped the volt | bolt between the upper and lower electrodes. It is a figure which shows a mode that the lower end of a guide pin is spaced apart from a volt | bolt and bolt welding is performed.

Explanation of symbols

A bolt welding device 1 bolt welding machine 2 bolt supply unit 3 controller (movement control means, first movement control unit, second movement control unit)
4 Bolt aligner 10 Upper electrode unit 11 Upper electrode (upper electrode)
11a Through hole 15 Guide pin 15c Lower end 15d Cavity 16 Magnet 30 Upper guide pin cylinder (guide pin moving means)
40 Lower electrode unit 41 Lower electrode (lower electrode)
X Bolt Xa Shaft Xb Flange W Work

Claims (4)

A workpiece and a bolt to be welded to the workpiece are supplied between a pair of vertically opposed electrodes, and the workpiece is placed on the lower electrode, while a bolt shaft is placed in a hole opening below the upper electrode. A bolt welding method in which the bolt and the workpiece are held between the upper and lower electrodes, energized and welded after the bolt is held by the upper electrode,
The hole opening below the upper electrode is a through hole penetrating in the vertical direction. A guide pin is inserted into the through hole so as to be movable up and down, and a magnet is disposed at the lower end of the guide pin. Has been established,
After the bolt supplied between the upper and lower electrodes is attached to the magnet at the lower end of the guide pin protruding below the upper electrode,
Holding the bolt on the upper electrode by moving the guide pin upward and inserting the shaft portion of the bolt into the through hole of the upper electrode,
With the upper electrode holding a bolt, the upper and lower electrodes are brought close to each other, the bolt and workpiece are sandwiched therebetween, and the guide pin is moved relatively upward with respect to the upper electrode. as heat generated by the upper electrode during the bolt welding is not transmitted to the magnet, the bolt welding wherein the welding is performed in a state in which the magnet is spaced from the bolt and the upper electrode. In claim 1,
A bolt welding method, wherein when holding a bolt on the upper electrode, the guide pin is moved upward to a predetermined position so that the flange portion of the bolt does not contact the lower end of the upper electrode. A workpiece and a bolt to be welded to the workpiece are supplied between a pair of vertically opposed electrodes, and the workpiece is placed on the lower electrode, while a bolt shaft is placed in a hole opening below the upper electrode. A bolt welding apparatus in which the bolt and the workpiece are held between the upper and lower electrodes, energized and welded after the bolt is held by the upper electrode,
The hole that opens below the upper electrode is a through-hole penetrating in the vertical direction, and a guide pin that is disposed so that the through-hole can be moved up and down.
A magnet disposed at a lower end portion of the guide pin and for attaching the bolt;
Guide pin moving means for moving the guide pin in the vertical direction;
Movement control means for controlling movement of the guide pin by the guide pin moving means ,
The movement control means includes
After attaching a bolt to the magnet at the lower end of the guide pin protruding downward from the upper electrode, the guide pin is moved upward so that the shaft portion of the bolt is inserted into the through hole of the upper electrode. A first movement control unit for holding a bolt on the upper electrode;
With the upper electrode holding the bolt, the upper and lower electrodes approach each other, and after the bolt and workpiece are sandwiched between the upper and lower electrodes, the guide pin is inserted into the upper electrode before welding the bolt. And a second movement control unit that moves the magnet away from the bolt and the upper electrode so that heat generated in the upper electrode during bolt welding is not transmitted to the magnet. A bolt welding apparatus characterized by that. Oite to claim 3,
A bolt welding apparatus, wherein a hollow portion is formed at a lower end portion of the guide pin, and a magnet is embedded in the hollow portion.

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