JP3094151B2 - Resistance welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection nut (hereinafter referred to as a projection nut) having an upper electrode and a lower electrode, a work set on a guide pin provided on the lower electrode, and a projection welded part on the set work. More specifically, the present invention relates to a resistance welding machine that welds nuts and the like, and more specifically, determines whether a supplied nut is arranged so as to be weldable, and controls the welding so that only the normally arranged nut is welded. Related to welding machines.

[0002]

2. Description of the Related Art Conventionally, when a nut having a projection welding portion is welded, a nut feeder or the like is used, for example, so that the projection welding portion is arranged on the work side and the nut is supplied. However, when supplying a large number of nuts to the resistance welding machine, the nuts may be upside down, the nuts may turn sideways, or the nuts may not be sent. Because of the failure, it was necessary to check the arrangement of the nuts before welding. In this case, the state in which the nut is placed upside down is called “back nut”, and the state in which it is placed in a normal posture is called “normal nut”. A state in which the nut is disengaged from the guide pin and lies down is referred to as "nut disengagement", and a state in which there is no nut is referred to as "no nut".

In order to solve this problem, an apparatus for easily welding only a normal nut to a work is disclosed in Japanese Patent Publication No. 7-125.
No. 46.

The apparatus M1 shown in FIG. 24 includes an upper electrode 42 and a lower electrode 43. A nut 31 having a projection welded portion 31a on the back side is provided with the lower side of the nut 31 facing downward. Resistance welding machine M1 configured to perform resistance welding on the upper surface of the work W supported by the guide pins 45 and the electrode tips 44 disposed on the electrode tip 44, wherein the electrode tips 44 are disposed and fixed to the resistance welding machine main body. A detection rod 48 held by a cylindrical electrode holder 46 and connected to a guide pin via a collar body 47 in the electrode holder 46 is vertically movably disposed, and a sensor holder 49 is provided below the detection rod 48. A sensor 50 for detecting the movement position of the guide pin 45 through the sensor is provided.

[0005] The sensor 50 starts moving from the position where the nut 31 is set by being guided by the guide pin 45.
When the projection welding portion 31a of the nut is moved to the first position where it is brought into contact with the workpiece W, and when the projection welding portion is melted during welding and the nut 31 is moved to the second position where the nut 31 is welded to the workpiece W. And two-stage movement can be detected. And
When the control device detects the detection signals of the first and second positions of the sensor 50 at substantially the same time, and when the control device does not input the detection signals of the first and second positions, it is determined that welding is impossible and an abnormal signal is output. It was controlled to output and stop the welding work.

[0006]

However, in the conventional apparatus, the guide pin 4 is moved by the lowering of the upper electrode 42.
5 to move the guide pin 4
5 itself is not configured to move positively.
For example, when the workpiece W is supplied by a robot or the like, if the guide pin 45 projects above the lower electrode 43, the guide pin 45 enters the movement path of the robot hand unit, and the workpiece W is inserted into the guide pin 45. When it becomes impossible to perform the operation, or when it is desired to correct the upper surface of the electrode tip 44 due to abrasion of the electrode tip 44, it is necessary to manually lower the guide pin 45. That is, since the adjusting screw of the guide pin 45 must be largely loosened and the guide pin 45 must be lowered below the upper surface of the electrode chip 44, the work related to the correction requires time and effort.

Further, since the sensor 50 for detecting the movement position of the guide pin 45 is in contact with the lower surface of the detection rod 48, the electrode tip 44 is corrected by abrasion of the electrode tip 44 or the like, and a new origin position is set. Since the adjustment of the detection position at each location is performed by loosening the respective adjustment screws, the work time for the adjustment also takes a long time.

Further, since the guide pin 45 of the conventional device is formed so as to cover a ceramic material or ceramic, there is a possibility that the guide pin 45 itself may be damaged by a contact impact with the collar body 47. .

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and ensures the supply of a work to a guide pin and simplifies the work of adjusting the origin position for correcting an electrode tip, thereby reducing the work time. It is an object of the present invention to provide an improved resistance welding machine capable of reducing the length of the guide tip and preventing the guide tip from being worn.

[0010]

Means for Solving the Problems A resistance welding machine according to the present invention is configured as follows in order to solve the above-mentioned problems. That is, comprising an upper electrode and a lower electrode, the lower electrode, an electrode tip that supports the work on the upper part, a guide pin that penetrates the electrode tip, and guides and holds a welding member having a projection welded part on the back surface, A cylindrical electrode holder which holds the electrode tip below the electrode tip and is fixedly disposed on the resistance welding machine main body; and a rod body disposed in the electrode holder and connected to the guide pin. , The welding member is configured to be resistance-welded to the workpiece, and a sensor is disposed below the rod body via a sensor holder so as to detect movement of the guide pin, and the sensor is configured to perform the welding. A first position where the member is moved from a position set on the guide pin to bring a projection weld of the welding member into contact with the work; A second position in which the projection weld is subsequently melted and the welding member is welded to the workpiece; and wherein the rod body is positioned above the rod body. A shaft connected to the guide pin via a buffer member, a rod connected to the shaft below the shaft, and a rod disposed through the rod.
And a coil having an upper portion connected to the shaft via a spring having an urging force and a lower urging force.
At the lower end thereof, and a detection rod for arranging an object to be detected by the sensor, and a cylinder case is disposed and fixed below the electrode holder, and is fixed to the cylinder case. The rod is slidably disposed in the formed fluid chamber, and a cylinder body is provided with the cylinder case and the rod.

[0011]

Preferably, the sensor is a linear output type displacement sensor.

[0013] More preferably, a guide pin cap is provided so as to be fitted to a lower portion of the guide pin, and buffer members are provided between the lower surface of the guide pin and the upper surface of the shaft so as to abut. And the guide pin cap and the shaft are connected so as to be fixed.

[0014]

[0015]

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, the resistance welding machine M includes an upper electrode 2 and a lower electrode 3, and a work W set on the lower electrode has a projection welding portion shown in FIGS. The nut 31 is resistance-welded. FIG. 1 shows an overall cross-sectional view, and FIGS.
FIG. 2 shows an upper enlarged view and a lower enlarged view in FIG. 1, respectively. In welding, the upper electrode 2 is brought close to the lower electrode 3 by an air cylinder or the like (not shown), and welding current is applied to the upper electrode 2 and the lower electrode 3. The main body control device is arranged to perform the control.

The upper electrode 2 is provided with a relief hole 2a which is opened from the lower surface upward in the axial center.

The lower electrode 3 is provided with an electrode tip 4 and a guide pin 5 above the lower electrode 3, and is fixed below the electrode tip 4 to a resistance welding machine main body via a lower electrode mounting horn (not shown). A cylindrical electrode holder 6 is provided and configured. A cooling water jacket 18 is fixed to the outer periphery of the electrode holder 6. The electrode tip 4 has a T-shaped cross section and a through-hole formed in the axial center thereof, and is attached to the upper part of a tubular adapter 7 which is detachably screwed to the upper end of the tubular electrode holder 6. Then, the guide pins 5 are arranged so as to be slid in the through holes of the electrode chips 4, and the workpiece W is supplied and set by a robot (not shown) guided by the guide pins 5 on the upper surface of the electrode chips 4.
Further, nuts 31 shown in FIGS. 4 and 5 are supplied to the guide pins 5 from a nut feeder (not shown).

A projection welding portion 31a is formed on the back side of the nut 31, and a screw hole 31b penetrating therethrough is formed.
Are formed. Then, the rear projection welding portion 31a is arranged on the lower side, and the screw hole 31b is fitted and held in the guide pin 5 of the lower electrode 3.

The guide pins 5 are long in the longitudinal direction, and are formed in three stages from below in FIG. 2, namely, a large-diameter flange portion 5a, a medium-diameter main body portion 5b, and a small-diameter guide portion 5c. Tapered (P-type guide pin) for easy fitting
Is formed.

A guide pin cap 8 is provided in the adapter 7 so as to cover the flange 5a of the guide pin 5 from above, and the main shaft 11 is connected to the lower surface of the flange 5a of the guide pin 5 via an O-ring 9. It is arranged downward. A groove for engaging the O-ring 9 is formed on the upper end surface of the main shaft 11, and when the O-ring 9 is engaged, the lower surface of the flange portion 5 a of the guide pin 5 and the upper surface of the main shaft 11 have side surfaces of the O-ring 9. Except for, a gap is formed. Then, a knock pin 10 is driven below the vicinity of the upper surface of the main shaft 11 to fix the main shaft 11 and the guide pin cap 8. Then, an O-ring 12 is fitted on the outer peripheral surface of the guide cap 8 into which the knock pin 10 is driven in order to prevent the knock pin 10 from coming off.

The main shaft 11 is configured such that an upper portion connected to the guide pin cap 8 is provided in the adapter 7 and a lower portion thereof is provided in the electrode holder 6. Further, a guide portion 11a is formed in the main shaft 11 around the upper part of the electrode holder 6 to be guided in the electrode holder 6 so as to prevent the main shaft 11 from swinging. As shown in 3, the outer peripheral surface is formed in two steps with a larger diameter than the upper part,
A rod connecting portion 11b having an opening hole 11c therein is formed. A female screw 11d is formed at the lower end of the opening 11c, and an upper part of a piston rod 22 of a cylinder body 20 described below disposed below the electrode holder 6 is screwed therein. Further, the coil spring 1 is provided in the opening 11c.
3 is provided, and urges a detection rod 14 described later inserted into the coil spring 13 to move downward. Therefore, the downward movement of the guide pin 5 and the main shaft 11 can be transmitted to the detection rod by the coil spring 13.

The detection rod 14 is formed in the shape of a round bar having a step. The upper end is inserted into the opening hole 11c of the main shaft 11, and a spring guide portion 14a around which the coil spring 13 is wound is formed. A step 15 is formed below the portion 14a. The upper surface of the step 15 is the coil spring 1
3 is formed with a spring receiving portion 15a with which the lower end portion is brought into contact.
The lower surface of the step portion 15 is provided with a contact portion 15b that is in contact with the upper surface of the piston rod. Below the step portion 15, a main body portion 14b is formed so as to slide in the piston rod,
Below the main body portion 14b, a detected object support portion 14c having a smaller diameter than the main body portion 14b is formed. Detector support 14
The end collar 16 is fitted to the base of c (upper part in the figure) so as to contact the lower end of the main body part 14b, and is urged upward by a coil spring 29 disposed in a sensor holder 27 described later. Supported. A dog 17 as a detection object is provided at a lower end of the detection object support portion 14c.
It is fixed so as to be fitted to c. Dog 17
A stop ring 24 is provided on the upper detection object support portion 14c.
And the vertical position of the detection rod 14 is set between the rod portion 15 and the contact portion 15b.

A cylinder case 21 constituting the cylinder body 20 is disposed and fixed below the electrode holder 6. In the cylinder case 21, an air chamber 21a is formed, and a piston rod 22 is disposed so that the piston 22a slides in the air chamber 21a. Piston rod 2
Reference numeral 2 denotes a sliding surface on which the main body 14b of the detection rod 14 slides is formed on the inner periphery, and the main shaft 1
A male screw part 22b screwed to one female screw part 11d is formed. Then, the nut 23 is connected to the male screw portion 22b so as to fix the main shaft 11 and the piston rod 22.
And are screwed together. Furthermore, cylinder case 2
1 is an upper air port 2 for supplying and discharging air to the air chamber 21a.
1b and a lower air port 2c are provided in the vertical direction.

Therefore, the main shaft 11 and the piston rod 22 are connected, and the detection rod 14 moving inside the main shaft 11 and the piston rod 22 is connected to the coil spring 1.
The rod body is formed by being connected via the third member 3 and can cope with the movement of the guide pin. Then, the piston 22 a slides in the cylinder case 21, and the upper end surface of the piston rod 22 can abut on the contact portion 15 b of the step portion 15 of the detection rod 14, thereby driving the cylinder body 20 with the guide pin. 5 can be told. That is, the guide pin 5 can perform a small stroke movement driven by the upper electrode 2 and a large stroke movement driven by the cylinder body 20.

An outer plate 25 is provided below the cylinder case 21, and a cylindrical inner joint 26 is provided so as to be fitted on the inner periphery of the outer plate 25.
Female thread portion 26 formed on the inner periphery of inner joint 26
The sensor holder 27 is screwed into a and fixed with a nut 28.

The sensor holder 27 holds the sensor, is formed in a two-stage cylindrical shape, and has a male screw portion 27a which is screwed into the female screw portion 26a of the inner joint 26 at the outer periphery of the upper small diameter portion. The above-mentioned coil spring 29 is disposed in the opening inside so as to urge the end collar 16 upward. An opening 27 b and a female screw 27 c are formed inside the large diameter portion below the sensor holder 27, and the female screw 27
A linear output displacement sensor 30 (hereinafter, referred to as a sensor 30) is screwed to c.

As the sensor 30, for example, a high-frequency sensor is used, and detects the position of the lower surface of the dog 17 of the object to be detected. The detected position is converted into an electric signal and inputted to a sensor body (digital panel meter) not shown. Therefore, when a preset position is detected, the sensor body outputs a corresponding command. Each set position only needs to input the number into the sensor main body.

The above-described detection rod 14 penetrates through the inner joint 26 and is fitted and supported by the sensor holder 27 so that the lower end to which the dog 17 is fixed is arranged in the opening 27b.

Next, an operation when the nut 31 as a welding member is welded to the work W by the resistance welding machine M configured as described above will be described.

First, before explaining the welding operation, the state before setting the nut 31, the guide pin 5, and the work W will be described.

The nut 31 is a guideless type in which a guide portion for guiding a hole of the work W is not formed, and the nut 31 has a projection welded portion 31a of the nut 31 disposed on the lower side (the posture shown in FIG. 5, ie, the posture shown in FIG. 5). The guide pin 5 is inserted into the guide pin 5 by a normal nut, and is fitted to the guide portion 5c of the guide pin 5 and set so as to be supported by the upper surface of the main body 5b.

In this case, the guide pin 5 is of a P type in which the tip of the guide portion 5c has a tapered surface, and the upper end of the guide pin 5 projects slightly from the upper surface of the nut 31. The protruding portion enters the escape portion 2a at a position where the upper electrode 2 contacts the upper surface of the nut.

When the nut 31 is supported by the guide pin 5, the distance from the upper surface of the work W to the lower end of the projection welding portion 31a of the nut 31 is S ₁ , and the distance from the lower end of the projection welding portion to the nut back surface. It is referred to as S _2. Therefore, when the upper electrode 2 is welded to the nut 31 to the workpiece W, the position is the first position to move the distance portion of S ₁ from the position abutting on the upper surface of the nut 31 the upper electrode 2 is lowered further, the first position to move the distance portion of S ₂ is the second position from the position. The distance S between the lower surface of the dog 17 disposed at the lower end of the detection rod 14 and the upper surface of the sensor is S _{1 at} the highest position of the guide pin 5.
+ Equal to or be set more in the S _2. In addition, the distance between the lower surface of the end collar 16 disposed at the base of the detection object support portion 14c of the detection rod 14 and the upper surface of the sensor holder 27 is also set to approximately S at the highest position of the guide pin 5. You. The stroke S ₃ of the piston rod 22 of the air chamber 21 a of the cylinder case 21 is set to be larger than S, and the distance S ₄ between the base end surface of the opening 11 c of the main shaft 11 and the upper surface of the detection rod 14 is in the uppermost position of the main shaft 11, is slightly larger set than S _3.

Before welding, the upper electrode 2 is arranged at an upper position, and the guide pins 5 are arranged such that the upper surface of the main body 5b of the guide pin 5 projects above the upper surface of the electrode chip 4. I have. In this state, since air is supplied to the cylinder body 20 through the air port 21c,
The piston rod 22 is pushed upward, and the main shaft 11 screwed to the male screw portion 22b of the piston rod 22 is moved upward. Then, the guide pin 5 is projected above the electrode chip 4 together with the guide pin cap 8. The detection rod 14 is also pushed up by the piston rod 22 at the contact portion 15b of the step portion 15.

Next, the operation of welding will be specifically described.

1) First, in order to supply a work into the resistance welding machine M, the guide pin 5 is moved below the upper surface of the electrode tip 4 by the cylinder body 20 to prevent interference between the robot and the guide pin 5. I do. In this case, a command is issued from the main controller to supply air to the air port 21b of the cylinder body 20. When air is supplied to the air port 21b, the piston rod 22 moves downward in the air chamber 21a of the cylinder case 21, as shown in FIG. Then, the main shaft 11 moves downward, and the guide pin 5 descends via the guide pin cap 8. At this time, since the coil spring 13 inserted into the opening hole portion 11c of the main shaft 11 is compressed and a biasing force acts downward, the detection rod 14 is moved downward.

In this state, the piston rod 22
Stroke S ₃ of is greater than S. Therefore, before the piston rod 22 reaches the lowest position, the end collar 1
6 comes into contact with the upper surface of the sensor holder 27, and the dog 17 comes into contact with the upper surface of the sensor 30. However, since the coil spring 13 can be further deflected, the piston rod 22 descends as it is.

2) Next, the work W is set. The work W arranged at a predetermined position is conveyed into the resistance welding machine M by a robot (not shown) or the like, and the holes WA formed in the work W are arranged so as to correspond to the guide pins 5. Then, the air circuit of the cylinder is switched again to move the guide pin 5 upward so as to pass through the hole WA of the work.

3) The start button of the resistance welding machine M is pressed, and the nut 31 is supplied. When the work W is set, a nut feeder (not shown) is operated, and the nut 31 is inserted into the guide pin 5.

4) The upper electrode 2 is lowered. When the nut supply completion signal is output, the air circuit of the air cylinder for the upper electrode 2 (not shown) of the resistance welding machine M is switched, and the upper electrode 2 descends. At this time, the welding machine timer operates simultaneously.

5) The nut 31, the guide pin 5, and the detection rod 14 descend. When the upper electrode 2 comes into contact with the upper surface of the nut 31 and further descends, the nut 31 and the guide pin 5 simultaneously move downward. At this time, since the air circuit of the cylinder 20 has not been switched, the piston rod 22 is at the raised position. However, the lowering of the guide pin 5 causes the O-ring 9 to be compressed, and the gap (S ₅ ) between the lower surface of the guide pin 5 and the upper surface of the main shaft 11 disappears and comes into contact, and the main shaft 11 is pushed down.

6) When the lower end surface of the projection welded portion 31a of the nut 31 moves by the position S ₁ on the upper surface of the work W, that is, when the dog 17 moves to the first position, the sensor 30 detects the dog 17. , And outputs the signal of the first position. At the same time, the device timer is activated. At this time, if the sensor 30 has not detected the second position of the dog, it is determined to be normal and a welding instruction signal is sent to the welding machine timer.

7) The welding machine is operated to carry out current supply and welding. 8) The nut 31, the guide pin 5, and the detection rod 14 are further lowered. Projection weld 31 of nut 31
a is the nut 31, the guide pin 5 is further lowered melt, the rear surface of the nut 31 is moved S ₂ minutes reaches the upper surface of the workpiece W, that is, the dog 17 reaches the position of the second position (see FIG. 8) , The sensor 30 detects the dog 17 and outputs a signal of the second position. The positional relationship of the piston rod 22 at this time is shown in FIG.

9) The upper electrode 2 rises. When the time of the welding machine timer expires and a welding completion signal is sent to the timer on the device side, the air circuit of the upper electrode 2 is switched and the upper electrode 2 rises. And the welding instruction signal / start signal is OF
At the same time as F, the air circuit of the cylinder 20 on the side of the lower electrode 3 is switched, and the guide pin 5 moves down together with the piston rod 22.

10) The work is replaced.

The operation of the resistance welding machine M is performed as described above. The time chart in this case is shown in FIG. In the above case, the normal nut is arranged. However, when the nut is supplied, only the normal nut is not always arranged. For example, a back nut is arranged, a nut detachment is arranged,
Sometimes without nuts.

Next, the operation when the back nut is arranged will be described.

Steps 1) to 4) are the same as those for the normal nut.

5) The nut 31, the guide pin 5, and the detection rod 14 descend. After the upper electrode 2 descends and comes into contact with the projection welding portion 31a of the nut 31, the nut 3
1 moves down to the second position at once with the guide pin 5 (see FIG. 9). Therefore, the sensor 30 is the first dog.
Since the position of the position and the position of the second position are detected almost simultaneously while the timer of the device is operating, the control device determines that there is an abnormality and switches the air circuit of the upper electrode 2 to switch the upper electrode 2. To raise.

6) Correct the abnormal location and restart. The abnormal signal is output continuously until reset processing is performed when the abnormal signal is confirmed.

The time chart in this case is shown in FIG.

Next, a description will be given of the operation in the case where the nut has been removed. In this case, the nut 31 is not inserted into the guide pin 5 and is turned sideways (see FIG. 10), or is turned upright on the side of the guide pin 5 (see FIG. 11). However, the same control is performed in each case.

The operations 1) to 4) are the same as described above.

5) Since the upper electrode 2 interferes with the nut 31 and the lowering of the upper electrode 2 stops, the guide pin 5 and the detection rod 14 do not lower. Therefore, the sensor 30 is the dog 1
7, the first position cannot be detected, the timer on the device side does not operate, and no welding instruction signal is output. Further, the sensor 30 does not detect the second position of the dog 17 either. Since the welding machine timer operates simultaneously with the lowering of the upper electrode 2, the time is up without conducting welding. Therefore, the timer of the apparatus receives the signal of the time-up, determines that welding is incomplete, and issues an abnormal signal. The abnormal signal continues until the reset processing.

6) Correct the abnormal part and restart.

FIG. 16 shows a time chart in this case.

Next, a case without a nut will be described.

The operations 1) to 4) are the same as described above. However, the hole diameter (d ₂ ) of the escape hole 2a of the upper electrode 2
The operation differs depending on the size of. For example, escape hole 2a
Pore size (d ₂₎ is smaller than the outer diameter of the guide portion 5c of the guide pin 5 the outer diameter of the body portion 5b of (d ₁₎ greater than the guide pin 5 (D), i.e., D> d _2> d ₁ Then, as shown in FIG. 12, 5) the upper electrode 2 descends to the upper surface of the work W at a stretch, and the guide pin 5 and the detection rod 14 also descend to the second position at a stretch. Therefore, the sensor 30 detects the first position and the second position of the dog 17 almost at the same time while the timer on the device side is operating. Therefore, the control device determines that there is an abnormality, and switches the air circuit of the upper electrode 2 to switch the upper electrode 2. To rise.

6) Correct the abnormal part and restart. The abnormal signal continues until reset processing is performed when the abnormal signal is confirmed.

The time chart in this case is shown in FIG.

Further, as shown in FIG. 13, if the hole diameter d2 of the escape hole 2a is larger than the outer diameter of the main body 5b of the guide pin 5, that is, if d ₂ > D, 5) the upper electrode 2 can be Although it descends to the upper surface of W, the guide pin 5 and the detection rod 14 do not descend. Therefore, the sensor 30 cannot detect the first position of the dog 17, the device timer does not operate, and no welding instruction signal is output. Further, the sensor 30 does not detect the second position of the dog 17 (see FIG. 13). Since the welding machine timer operates simultaneously with the lowering of the upper electrode 2, the time is up without conducting welding. Therefore, the timer of the apparatus receives the signal of the time-up, determines that welding is incomplete, and issues an abnormal signal. The abnormal signal continues until the reset processing.

6) Correct the abnormal location and restart. The abnormal signal continues until reset processing is performed when the abnormal signal is confirmed.

The time chart in this case is shown in FIG.

The above description has been made in connection with the case where the nut is a guideless nut. As shown in FIGS. 17 and 18, the nut as a welding member has a projection welded portion 32a on the back side. In some cases, the guide nut 32 has a screw hole 32b penetrating the shaft center portion and has a guide portion 32c for guiding a hole of the work W. In this case, the first position and the second position are detected only when welding is performed normally, and the first position and the second position are not detected in other states. Therefore, the discrimination between the front and back can be dealt with by the same control method as in the case of the nut without guide described above. (Refer to FIGS. 19 to 23.) When the guide chip 4 is worn and corrected, the first position of the origin is adjusted by setting the work W and the normal nut 31 on the guide pin 5 and lowering the upper electrode 2. It is only necessary to correct and store the output value of the sensor 30 at that time in the control device. The position of the second position does not need to be corrected if the shape of the nut 31 is the same.

In this embodiment, the cylinder 20
Is provided so that the movement of the guide pin 5 is made different from the movement of the upper electrode 2.
May be arranged anywhere on the lower electrode 3.

The sensor 30 uses a high-frequency sensor, but any sensor using an optical sensor or a linear output type displacement sensor, regardless of whether it is a contact type or a non-contact type, is used. Can be used.

Further, the guide pin 5 and the main shaft 1
The connection structure with the first connector 1 is not limited to this embodiment as long as the guide pin 5 can be prevented from being damaged by impact. Further, the buffer member interposed between the guide pin 5 and the main shaft 11 is not limited to the O-ring, but may be an elastic resin member.

[0070]

According to the present invention, in the resistance welding machine, the guide pin for holding the work / welding member is moved by the cylinder body disposed in the lower electrode separately from the downward movement by the upper electrode. Therefore, when supplying the work, a robot or the like can be arranged to supply the work easily and reliably.
Correction work can be performed very easily without manually moving the guide pins.

Further, the piston rod constituting the cylinder body and the main shaft connected to the guide pin operate integrally, and the detection rod, which is provided with the object to be detected and slides inside the piston rod, is the main rod. Since it is connected to the shaft via a spring, the guide pin can be moved within the stroke range of the piston rod by the operation of the cylinder body, and when the guide pin is moved by the upper electrode, the piston rod is arranged at the upper end of the stroke. This does not hinder the movement of the guide pin, and the movement of the guide pin can be performed by another drive of the upper electrode and the cylinder body.

Further, since the sensor is a linear output displacement sensor, when the wear of the electrode tip is corrected, the position set by the correction is adjusted by pressing the nut and the work between the upper electrode and the lower electrode. The output value may be corrected and stored, and the work of adjusting the origin can be performed extremely easily.

If the wear correction of the electrode tip is overlapped and the protrusion of the guide pin on the electrode tip becomes too large, the sensor holder fixing nut is loosened and the sensor holder is lowered, so that the sensor holder is integrated with the main shaft via the detection rod. Can be easily reduced to a predetermined size, and then the work can be returned by performing the above-mentioned origin adjustment. Therefore, it is effective for effective use of the electrode tip.

Further, since the guide pin is connected to the rod body located below the guide pin via the buffer member, the buffer member can absorb the shock caused by the upper electrode. it can. Therefore, the wear of the guide pins can be extremely reduced.

In this embodiment, the guide pin has a P-shaped (point-type JIS) shape. However, the guide pin has a tip that is lower than the nut height when the nut is welded. Can be used in exactly the same way, and the same effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a resistance welding machine according to an embodiment of the present invention.

FIG. 2 is an upper sectional view of the lower electrode.

FIG. 3 is a lower sectional view of the lower electrode.

FIG. 4 is a plan view of the projection nut.

FIG. 5 is a front sectional view of the same.

FIG. 6 is an operation state diagram showing a movement state of a guide pin by operation of the cylinder body.

FIG. 7 is an operation state diagram showing a movement state of a guide pin during the welding.

FIG. 8 is a diagram showing a normal nut during welding;

FIG. 9 is a diagram showing the operation of the back nut.

FIG. 10 is a diagram showing a state in which a nut is disengaged;

FIG. 11 is a diagram showing an actuation of nut removal according to another embodiment.

FIG. 12 is a diagram showing an operation state without a nut;

FIG. 13 is a diagram showing an operation state without a nut;

FIG. 14 is a time chart showing the time of welding a normal nut.

FIG. 15 is a time chart showing an operation without a back nut and without a nut.

FIG. 16 is a time chart showing a state in which the nut is removed and the nut is not operated.

FIG. 17 is a plan view of another projection nut.

FIG. 18 is a front sectional view of the same.

FIG. 19 is a diagram showing another nut when welding a normal nut;

FIG. 20 is a diagram showing the operation of the back nut of another nut;

FIG. 21 is a diagram showing a state in which another nut is disengaged;

FIG. 22 is a diagram showing another nut when it is actuated;

FIG. 23 is a diagram showing the operation of another nut without a nut

FIG. 24 is a front sectional view of a conventional resistance welding machine.

[Explanation of symbols]

 M: resistance welding machine 2: upper electrode 2a: escape hole (opening hole) 3: lower electrode 4: electrode tip 5: guide pin 6: electrode holder 9: O-ring (buffer member) 11: main shaft (rod body) 11a ... Guide part 11c ... Opening hole part 13 ... Coil spring 14 ... Detection rod (rod body) 16 ... End collar 17 ... Dog (detected body) 20 ... Cylinder body 21 ... Cylinder case 22 ... Piston rod (rod body) 27 ... Sensor holder 29 ... Coil spring 30 ... Sensor W ... Work

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 11/14 B23K 11/24 B23K 11/30

Claims (3)

(57) [Claims] 1. An electrode comprising an upper electrode and a lower electrode, wherein the lower electrode guides and holds an electrode tip for supporting a workpiece on an upper part thereof and a welding member penetrating the electrode tip and having a projection welded part on the back surface. A guide pin, a cylindrical electrode holder that holds the electrode tip below the electrode tip and is fixedly disposed on the resistance welding machine main body, and a rod body that is disposed in the electrode holder and connected to the guide pin, The welding member is configured to be resistance-welded to the work, and a sensor is disposed below the rod body via a sensor holder so as to detect movement of the guide pin. Is moved from a position where the guide pin of the welding member is set to contact a projection welding portion of the welding member with the work. A resistance welder configured to detect a position and a second position where the projection weld is subsequently melted and the welding member is welded to the workpiece. via the cushioning member to the guide pin at the top of the body
A shaft coupled Te, a rod connected to the shaft below the said shaft, through said rod slidably move within said rod together is arranged, at the top the shaft and the lower above the bottom while being connected through a spring having a biasing force
A detection rod disposed at a lower end portion of the detection member, the detection rod being provided with an object to be detected by the sensor, and a cylinder below the electrode holder. A case is disposed and fixed, the rod is slidably disposed in a fluid chamber formed in the cylinder case, and a cylinder body is configured including the cylinder case and the rod. Machine. 2. The resistance welding machine according to claim 1, wherein said sensor is a linear output displacement sensor. 3. A guide pin cap is provided at a lower portion of the guide pin so as to be fitted thereto, and a buffer member is provided between the lower surface of the guide pin and the upper surface of the shaft so as to abut. 3. The resistance welding machine according to claim 1 , wherein the guide pin cap and the shaft are connected so as to be fixed.