JP2005319485A - Spot welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spot welding equipment capable of enhancing the accuracy of the spotting position when continuously performing a plurality of sets of spot welding at different spot intervals on one line. <P>SOLUTION: When a servo motor 60 is turned to the right when a welding head 50 is viewed from the right side, the interval between guide members 53, 54 is reduced according to the turning quantity. When the servo motor 60 is turned to the left, the interval between the guide members 53, 54 is increased according to the turning quantity. Thus, by controlling the rotational direction and the turning quantity of the servo motor 60 by a control circuit 46, the interval between the guide members 53, 54 can be arbitrarily set. Tip parts of electrode tips 26, 27 are arranged at arbitrary positions on one line, and the interval between the tip parts can be arbitrarily set. A plurality of sets of spot welding can be continuously performed at different spot welding intervals on the line. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spot welding apparatus.

  Conventionally, a series spot welding method, an indirect spot welding method, or the like is known as a welding method between metal plates.

  In the series spot welding method, by applying a welding current between two electrodes while applying pressure from one direction with a pair of electrodes that separate two overlapped metal plates, A melted portion of the metal plate (generally referred to as a “weld nugget”) is generated at the contact point, and the two metal plates are welded in a spot shape by the weld nugget. Therefore, in the series spot welding method, two welding nuggets corresponding to a pair of electrodes are formed. Note that a portion where the electrode is pressed on the metal plate is called a “spot”.

  The indirect spot welding method differs from the series spot welding method in that one of the two stacked metal plates is small, one of the pair of electrodes presses the smaller metal plate, and the other electrode is large This is a point that a welding nugget is generated at a contact portion of both metal plates pressed by the one electrode by flowing a welding current between both electrodes while pressing one metal plate. Therefore, in the indirect spot welding method, only one welding nugget corresponding to the one electrode is formed.

By the way, the series spot welding method includes a type using a back electrode and a type not using it.
In the type using the back electrode, the back electrode is arranged on the back side of the metal plate located on the opposite side to the pressure side of the electrode, one electrode → superposed metal plate → back electrode → superposed metal plate → the other By forming a current path called an electrode and flowing a welding current through the current path, welding is performed in a spot shape on the two metal plates that are overlapped.

  On the other hand, in the type that does not use the back electrode, a current path of one electrode → superimposed metal plate → the other electrode is formed, and a welding current is passed through the current path. Weld in a spot shape. Therefore, it is used when a separate member or the like assembled in the pre-welding process covers the back side of the metal plate to form a closed cross-section and the back electrode cannot be arranged on the back side of the metal plate.

However, the series spot welding method that does not use a back electrode has a drawback that it is difficult to form a sufficient nugget and a blow hole is formed, so that a sufficient welding strength cannot be obtained. It was.
Therefore, the applicant of the present invention presses and contacts a pair of spaced apart electrodes on one surface of two superimposed metal plates and causes a welding current to flow between the two electrodes, and welds the two metal plates. A series spot welding method, wherein the electrode of the one metal plate is press-contacted with a part of the seat surface that is partially higher than the general part, and the electrode has a spherical tip. A series spot welding method has been developed in which the electrode is welded to the seating surface under pressure contact so as to crush the seating surface (see Patent Document 1).

Incidentally, in recent years, in the spot welding method, it is required to arbitrarily change the interval (pitch) between two hit points by changing the interval between the pair of electrodes.
Therefore, in a spot welding apparatus that indirectly welds a material to be welded with the tip portions of a pair of substantially parallel rod-like electrodes disposed on the welding head portion at the tip of the arm, the distance between the pair of electrodes can be varied in the welding head portion. Proposed is a spot welding device that has an electrode spacing variable mechanism that is configured with an electrode turning mechanism that turns one of a pair of electrodes at a predetermined radius around a position different from the other electrode. (See Patent Document 2).
In addition, although patent document 2 does not describe anything about the series spot welding method, the technique of patent document 2 is applicable not only to the indirect welding method but also to the series spot welding method.
JP 2002-239742 A (pages 2 to 6, FIGS. 1 to 4) JP 2002-263848 A (pages 2 to 6, FIGS. 1 to 3)

In recent years, it has been required to perform a plurality of spot weldings continuously at different spot intervals on a straight line.
In this case, in the technique of Patent Document 2, first, the one electrode is turned using an electrode turning mechanism to change the distance between the pair of electrodes, and then the arm is moved so that the pair of electrodes are aligned. Must be repositioned along.
Therefore, when performing an operation of rearranging the pair of electrodes along a straight line, the positional accuracy of the hitting point may be lowered.

In recent years, it has been required to perform spot welding on a curved metal plate. In order to perform reliable spot welding on a curved metal plate, the normal direction of the welded portion (spot) in the curved metal plate and the pressing direction of the electrode must be matched.
However, since the techniques of Patent Document 1 and Patent Document 2 have only a function of pressing a pair of electrodes in a direction perpendicular to a planar metal plate, the normal direction of the welded portion in the curved metal plate and The pressurizing direction of the electrodes cannot be matched, and reliable spot welding cannot be performed on the curved metal plate.

The present invention has been made to solve the above-described problem, and the object thereof is to improve the positional accuracy of the spot when performing a plurality of spot welds continuously at different spot intervals on a straight line. Is to provide a simple spot welding apparatus.
Another object of the present invention is to provide a spot welding apparatus capable of performing reliable spot welding on a curved metal plate.

  According to the first aspect of the present invention, a pair of spaced apart electrodes are brought into pressure contact with one surface of two superimposed metal plates, and a welding current is passed between the two electrodes. The pair of electrodes pressurize the metal plate in the same direction, and at least one of the pair of electrodes with respect to the other, the pressurizing direction of the metal plate A technical feature is provided with a parallel moving means for changing the distance between the pair of electrodes by parallel translation in an orthogonal direction.

  According to the second aspect of the present invention, a pair of spaced apart electrodes are brought into pressure contact with one surface of two superimposed metal plates, and a welding current flows between the two electrodes. A series spot welding apparatus for welding at least one of the pair of electrodes relative to the other by tilting at an arbitrary angle, the normal direction of the welded portion on the surface of the metal plate, and the pair It is a technical feature that a tilting means is provided to match the direction in which the electrode of the metal plate presses the metal plate.

  According to a third aspect of the present invention, a pair of spaced apart electrodes are brought into pressure contact with one surface of two stacked metal plates, and a welding current is passed between the two electrodes. A series spot welding apparatus for welding a pair of electrodes by translating at least one of the pair of electrodes with respect to the other in a direction orthogonal to the pressing direction of the metal plate. A parallel moving means for changing the interval, and by tilting at least one of the pair of electrodes with respect to the other at an arbitrary angle, the normal direction of the welding location on the surface of the metal plate, and the pair of electrodes Is provided with a tilting means for matching the direction in which the metal plate is pressed.

(Claim 1)
According to the first aspect of the present invention, by appropriately setting the distance between the pair of electrodes by the parallel movement means, the tip portions of the electrodes are arranged at arbitrary positions on a straight line, and the distance between the tip portions of the electrodes is set. Since it can be arbitrarily set, a plurality of spot weldings can be continuously performed at different spot intervals on a straight line. In the first aspect of the invention, since the distance between the electrodes is changed simply by translating the pair of electrodes, it is possible to prevent the positional accuracy of the hit points from being lowered as in Patent Document 2.

(Claim 2)
According to the invention of claim 2, by tilting at least one of the pair of electrodes with respect to the other at an arbitrary angle by the tilting means, it is possible to arbitrarily set the pressing direction of each electrode. The normal direction of the welding location on the surface of the metal plate can be matched with the pressurizing direction of each electrode. Therefore, in the invention of claim 2, reliable spot welding can be performed on the curved metal plate.

(Claim 3)
According to the invention of claim 3, it is possible to provide a spot welding apparatus having the functions and effects of the inventions of claims 1 and 2.

(Explanation of terms)
The correspondence between the constituent elements described in [Means for Solving the Problems] described above and the constituent members described in [Best Mode for Carrying Out the Invention] described below is as follows. .

  “Parallel moving means” includes air cylinders 24 and 25, rails 51 and 52, guide members 53 and 54, male screws 55 and 56, ball screws 57 and 58, mounting member 59, servo motor 60, motor shaft 61, and toothed pulley. 62 to 64, a toothed belt 65, mounting members 66 and 67, and pistons 68 and 69.

  The “tilting means” includes an air cylinder 25, a piston 69, mounting members 80 to 82, a servo motor 83, and a speed reducer 84.

(First embodiment)
[Configuration of First Embodiment]
FIG. 1 is a perspective view showing a schematic configuration of a spot welding apparatus 20 according to the first embodiment embodying the present invention.
The spot welding device 20 includes a six-axis robot arm 22, air cylinders 24 and 25, electrode tips 26 and 27, a control device 40, a welding head 50, and the like.

  The electrode tip 26 is attached to the tip of a piston 68 protruding from the air cylinder 24, and the electrode tip 27 is attached to the tip of a piston 69 protruding from the air cylinder 25. The head main body 23 of the welding head 50 is attached to the wrist portion 22 a of the six-axis robot arm 22, and the air cylinders 24 and 25 arranged in parallel are attached to the front side of the head main body 23. The air cylinders 24 and 25 are supplied with compressed air from an air pump (not shown).

  The six-axis robot arm 22 has the electrode chips 26 and 27 supported by the air cylinders 24 and 25 at predetermined positions on two metal plates Wa and Wb (for example, steel plates and aluminum alloy plates, for example). Move. Each of the air cylinders 24 and 25 expands and contracts the piston by the air pressure of the compressed air supplied from the air pump, thereby moving the electrode tips 26 and 27 attached to the tip of the piston forward and backward. The tip portions 26a and 27a of 26 and 27 are brought into pressure contact with the metal plate Wa.

  In the metal plate Wa, a convex portion having a seating surface 30a that is partially higher than the general portion 35 at a portion (welding location, hitting point) where the tip portions 26a, 27a of the electrode tips 26, 27 are in pressure contact. 30 is formed.

  FIG. 2 is a circuit diagram showing an electrical configuration of the control device 40 that controls the welding current supplied to the electrode tips 26 and 27 of the spot welding device 20.

The control device 40 includes a welding transformer 42, a voltage detector 44, a control circuit 46, an AC power supply 48, thyristors SCR1 and SCR2, and the like. A device including the voltage detector 44, the control circuit 46, and the thyristors SCR1 and SCR2 is referred to as a “timer contactor”.
The electrode tips 26 and 27 are electrically connected to the secondary winding of the welding transformer 42. An AC power supply 48 is electrically connected to the primary winding of the welding transformer 42 via the thyristors SCR1 and SCR2.

The voltage detector 44 detects the voltage between the electrode tips 26 and 27 (secondary voltage of the welding transformer 42) and outputs the voltage value (voltage data) to the control circuit 46.
The gate terminals of the thyristors SCR 1 and SCR 2 that are connected in parallel in opposite directions are connected to the control circuit 46.
The control circuit 46 outputs a trigger signal to the gate terminals of the thyristors SCR1 and SCR2 based on the voltage between the electrode chips 26 and 27 detected by the voltage detector 44, thereby controlling the welding from the AC power supply 48. Switching between energization / interruption of the welding current supplied to the primary side of the transformer 42 and phase control are performed.
The control circuit 46 also controls the expansion and contraction of the pistons by the 6-axis robot arm 22 and the air cylinders 24 and 25, and drive control of servo motors 60 and 83 to be described later.

  FIG. 3 is a partial cross-sectional view for explaining a spot welding process of the metal plates Wa and Wb by the electrode tips 26 and 27 of the spot welding apparatus 20.

  First, as shown in FIG. 3 (A), the tip portions 26a, 27a of the electrode tips 26, 27 are positioned above the convex portion 30 of the steel plate Wa with respect to the two metal plates Wa, Wb superimposed. As described above, the electrode tips 26 and 27 are moved and positioned by the six-axis robot arm 22.

  Next, as shown in FIG. 3 (B), by extending the pistons of the air cylinders 24, 25, the electrode tips 26, 27 attached to the tips of the pistons are moved, and the electrode tips 26 are moved. , 27 are brought into pressure contact with the metal plate Wa.

  At this time, even after the tip portions 26a, 27a of the electrode tips 26, 27 are in contact with the seating surface 30a, the pistons of the air cylinders 24, 25 are extended and the pressurization by the electrode tips 26, 27 is continued. The seating surface 30a is crushed in the direction of the steel plate Wb. In other words, the presence of the convex portion 30 causes the electrode tips 26 and 27 to crush the seating surface 30a so as to narrow the space K formed between the metal plates Wa and Wb. As a result, a concave portion having a spherical recess is formed on the seat surface 30a, and a contact surface 30c that protrudes spherically toward the metal plate Wb is formed on the back side of the seat surface 30a.

  Subsequently, as shown in FIG. 3C, pressurization by the electrode tips 26 and 27 is further continued, and the top of the spherical contact surface 30c formed on the back side of the seating surface 30a is brought into contact with the metal plate Wb. Let That is, the most protruding portion of the contact surface 30c is brought into point contact with the metal plate Wb earlier than the other portions. As a result, the contact surface 30c is in point contact with the metal plate Wb via the point contact portion 30d. That is, the point contact portion 30d, which is a place where the electrode tips 26 and 27 are pressurized, becomes a hit point.

In this state, the control circuit 46 controls the thyristors SCR1 and SCR2 to energize the welding current from the AC power supply 48 to the primary side of the welding transformer 42. Energize the welding current in between.
Then, an energization path (solid line with an arrow in the figure) having a large contact resistance narrowed in a dot shape by the point contact portion 30d is formed, and the welding current flowing through the energization path has a higher current density than the energization path by surface contact. It is done. The resistance heating value is increased by the welding current, and the metal plates Wa and Wb at the point contact portion 30d are melted to produce a weld nugget Na, and both the metal plates Wa and Wb are welded in a spot shape by the weld nugget Na. The

After that, by continuing the pressurization and energization by the electrode tips 26 and 27, the point contact portion 30d of the metal plate Wa sinks so as to sink into the metal plate Wb, and the surface direction along the spherical contact surface 30c. The welding nugget Na is sequentially formed so as to go to, and spot welding is completed.
Note that the pressure applied when the tip portions 26a, 27a of the electrode tips 26, 27 pressurize the metal plate Wa is set to a relatively low pressure (for example, about 50 kgf).

FIGS. 4A and 5A are plan views of the welding head 50 of the first embodiment.
4B and 5B are front views of the welding head 50 of the first embodiment.
4 shows a state in which the distance between the electrode tips 26 and 27 is the narrowest, and FIG. 5 shows a state in which the distance between the electrode tips 26 and 27 is the largest.
6 and 7 are right side views of the welding head 50 of the first embodiment.
6 shows a state where the pistons 68 and 69 of the air cylinders 24 and 25 are retracted most, and FIG. 7 shows a state where the pistons 68 and 69 of the air cylinders 24 and 25 are extended most.

  The welding head 50 according to the first embodiment includes a head body 23, air cylinders 24 and 25, rails 51 and 52, guide members 53 and 54, male screws 55 and 56, ball screws 57 and 58, a mounting member 59, a servo motor (servo Motor) 60, motor shaft 61, toothed pulleys 62 to 64, toothed belt 65, mounting members 66 and 67, pistons 68 and 69, shunts 70 to 73, mounting members 74 and 75, and the like.

Each rail 51, 52 is disposed at a position parallel to the longitudinal direction of the welding head 50, and is attached and fixed to the front side of the head body 23.
The guide members 53 and 54 are fitted to the rails 51 and 52 so as to be slidable and not dropout.

Each guide member 53, 54 is formed with a through hole (not shown) in the lateral direction, a female screw (not shown) is formed in the through hole, a ball (not shown) is incorporated in the screw groove, The male screws 55 and 56 are inserted into the through holes of the guide members 53 and 54, and the female screws in the guide members 53 and 54 and the male screws 55 and 56 are screwed together.
Therefore, the male screws 55 and 56 are arranged in parallel with the rails 51 and 52.
The guide member 53 functioning as a ball nut and the male screw 55 constitute a right-handed ball screw 57. The guide member 54 functioning as a ball nut and the male screw 56 constitute a left-handed ball screw 58.

The plate-like attachment member 59 is attached and fixed to the right side surface side of the head main body 23.
A servo motor 60 is built in the head body 23, and the motor shaft 61 of the servo motor 60 is inserted into a through hole (not shown) formed in the mounting member 59, and the motor shaft 61 protruding from the mounting member 59 has teeth on the motor shaft 61. The attached pulley 62 is fixedly attached.
The right ends of the male screws 55 and 56 are inserted into through holes (not shown) formed in the mounting member 59, and toothed pulleys 63 and 64 are provided on the right ends of the male screws 55 and 56 protruding from the mounting member 59. It is fixed.
A toothed belt 65 is hung on each toothed pulley 62-64.

The air cylinders 24 and 25 are arranged at positions orthogonal to the male screws 55 and 56, and the upper ends of the air cylinders 24 and 25 are connected to the guide members 53 and 54 via L-shaped mounting members 66 and 67. It is fixed on the front side.
The electrode tips 26 and 27 are attached and fixed to the tip portions of the pistons 68 and 69 projecting downward from the lower ends of the air cylinders 24 and 25, respectively.

The air cylinders 24 and 25, the pistons 68 and 69, and the electrode tips 26 and 27 are arranged at positions that overlap when the welding head 50 is viewed from the side surface side.
When the welding head 50 is viewed from the front side, the tip of the piston 68 is bent to the left, and the tip of the piston 69 is bent to the right. As shown in FIG. The distance between the electrode tips 26 and 27 is set to be small in a state where 25 is close.

A welding transformer 42 is built in the head body 23.
Each of the shunts 70 to 73 is formed by bending a plurality of laminated copper thin plates into a U shape, and its electric resistance is set small.
The shunts 70 and 71 are arranged so that the entire length can be changed by bending in the longitudinal direction of the welding head 50, and the shunts 72 and 73 are arranged so that the entire length can be changed by bending in the lateral direction of the welding head 50. Yes.

One end of each shunt 70, 71 is attached and fixed to the back side of each piston 68, 69, and the other end of each shunt 70, 71 is attached to each shunt 72, 73 via L-shaped attachment members 74, 75. It is attached and fixed to one end, and the other end of each shunt 72, 73 is connected to the secondary winding of the welding transformer.
The electrode tip 26 is electrically connected to the secondary winding of the welding transformer 42 via the shunt 70, the attachment member 74, and the shunt 72. The electrode tip 27 is electrically connected to the secondary winding of the welding transformer 42 via the shunt 71, the attachment member 75, and the shunt 73.

  As described above, the shunts 70 to 73 are used to connect the electrode tips 26 and 27 to the secondary winding of the welding transformer 42 from the secondary side of the welding transformer 42 to the electrode tips 26 and 27. This is because, since the current value of the welding current that is energized is large, the electrical resistance is too high in a normal wiring material, and current loss increases.

[Operations and effects of the first embodiment]
The rotation of the servomotor 60 is transmitted from the toothed pulley 62 to the toothed pulleys 63 and 64 via the toothed belt 65. The male screws 55 and 56 rotate with the rotation of the toothed pulleys 63 and 64. That is, the male screws 55 and 56 are rotationally driven by the servo motor 60.
Here, the rotation direction of the servo motor 60 (toothed pulley 62) and the rotation direction of each toothed pulley 63, 64 (each male screw 55, 56) are the same.

Therefore, when the servo motor 60 rotates in the clockwise direction (arrow α direction shown in FIG. 6) when the welding head 50 is viewed from the right side, the male screws 55 and 56 also rotate in the clockwise direction.
Here, since the ball screw 57 constituted by the male screw 55 and the guide member 53 is a right-hand screw, the guide member 53 moves away from the toothed pulley 63 as the male screw 55 rotates in the clockwise direction (shown in FIG. 4). Move in the direction of arrow γ).
Since the ball screw 58 formed by the male screw 56 and the guide member 54 is a left-hand screw, the guide member 54 approaches the toothed pulley 64 as the male screw 56 rotates in the clockwise direction (the arrow shown in FIG. 4). move in the δ direction).

When the servo motor 60 rotates counterclockwise (in the direction of arrow β shown in FIG. 6) when the welding head 50 is viewed from the right side, the male screws 55 and 56 also rotate counterclockwise.
Here, since the ball screw 57 constituted by the male screw 55 and the guide member 53 is a right-hand screw, the guide member 53 approaches the toothed pulley 63 as the male screw 55 rotates in the counterclockwise direction (shown in FIG. 5). Move in the direction of arrow δ).
Since the ball screw 58 formed by the male screw 56 and the guide member 54 is a left-hand screw, the guide member 54 moves away from the toothed pulley 64 as the male screw 56 rotates in the counterclockwise direction (the arrow shown in FIG. 5). Move in the γ direction).

Thus, when the welding head 50 is viewed from the right side, when the servo motor 60 is rotated in the clockwise direction (the direction of the arrow α shown in FIG. 6), the guide members 53 and 54 are rotated according to the amount of rotation. The interval is shortened. Further, when the servo motor 60 is rotated in the counterclockwise direction (the direction of the arrow β shown in FIG. 7), the interval between the guide members 53 and 54 increases according to the amount of rotation.
Therefore, by controlling the rotation direction and the rotation amount of the servo motor 60 by the control circuit 46, the interval between the guide members 53 and 54 can be arbitrarily set.

Here, the guide members 53 and 54 are fitted to the rails 51 and 52 so as to be slidable and non-detachable, and the rails 51 and 52 are arranged at positions parallel to the longitudinal direction of the welding head 50. Therefore, the guide members 53 and 54 can move only in the lateral direction of the welding head 50.
The air cylinders 24 and 25 are fixedly attached to the guide members 53 and 54 via the mounting members 66 and 67. The air cylinders 24 and 25 are orthogonal to the male screws 55 and 56 (rails 51 and 52). It is arranged at the position to do.
As shown in FIG. 4, the dimensions of the ball screws 57 and 58 are set so that the electrode tips 26 and 27 do not come into contact with each other when the distance between the guide members 53 and 54 is minimized.

As described above, in the first embodiment, the electrode tips 26 and 27 attached and fixed to the tip portions of the pistons 68 and 69 protruding downward from the air cylinders 24 and 25 are respectively connected to the metal plates Wa and Wb. In the same direction.
Then, at least one of the electrode tips 26 and 27 (air cylinders 24 and 25) is parallel to the direction perpendicular to the pressing direction of the metal plates Wa and Wb (lateral direction of the welding head 50) with respect to the other. By moving, the distance between the electrode tips 26 and 27 can be varied.
Further, the air cylinders 24 and 25, the pistons 68 and 69, and the electrode tips 26 and 27 are arranged at positions where they overlap when the welding head 50 is viewed from the side.

  Therefore, according to the first embodiment, the tip portions 26a, 27a of the electrode tips 26, 27 are arranged at arbitrary positions on a straight line only by controlling the rotation direction and the rotation amount of the servo motor 60, and the tip portions Since the interval between 26a and 27a can be arbitrarily set, a plurality of spot weldings can be continuously performed at different hitting point intervals (intervals between the point contact portions 30d) on a straight line.

Since the positional accuracy of the tip portions 26a, 27a of the electrode tips 26, 27 is defined by the rotation amount of the servo motor 60 and the accuracy of the ball screws 57, 58, it is easy to increase the positional accuracy. .
Moreover, in 1st Embodiment, since the space | interval of each electrode tip 26 and 27 is changed only by translating each guide member 53 and 54, it can prevent that the positional accuracy of a hit point falls like patent document 2. FIG. .

(Second Embodiment)
[Configuration of Second Embodiment]
FIGS. 8A, 9A, and 10A are plan views of the welding head 50 according to the second embodiment.
FIGS. 8B, 9B, 10B, 11 and 12 are front views of the welding head 50 of the second embodiment.
FIG. 13 is a right side view of the welding head 50 of the second embodiment, and shows a state in which the pistons of the air cylinders 24 and 25 are retracted most.

  FIG. 8 shows a state in which the air cylinder 25 is arranged in a direction perpendicular to the rail 52 and the interval between the air cylinders 24 and 25 is narrowed. FIG. 9 shows a state in which the air cylinder 25 is arranged in a direction perpendicular to the rail 52 and the interval between the air cylinders 24 and 25 is widened. FIG. 10 shows a state in which the air cylinder 25 is tilted toward the air cylinder 24 and the interval between the air cylinders 24 and 25 is narrowed. FIG. 11 shows a state in which the air cylinder 25 is tilted toward the air cylinder 24 and the distance between the air cylinders 24 and 25 is widened. FIG. 12 shows a state in which the air cylinder 25 is tilted to the opposite side of the air cylinder 24 and the interval between the air cylinders 24 and 25 is widened.

In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
The second embodiment is different from the first embodiment only in the following points.

  [A] In the welding head 50 of the second embodiment, the mounting member 67 is omitted from the first embodiment, and the head body 23, air cylinders 24 and 25, rails 51 and 52, guide members 53 and 54, male screws 55 and 56, Ball screws 57 and 58, mounting member 59, servo motor (servo motor) 60, motor shaft 61, toothed pulleys 62 to 64, toothed belt 65, mounting members 66 and 67, pistons 68 and 69, shunts 70 to 73, In addition to the mounting members 74 and 75, the mounting members 80 to 82, a servo motor (servo motor) 83, a speed reducer 84, and the like are included.

  [A] The upper end portion of the air cylinder 25 is attached and fixed to a substantially L-shaped attachment member 80, and the lower end portion of the attachment member 80 is attached and fixed to a plate-like attachment member 81. A plate-like attachment member 82 is attached and fixed to the front side of the guide member 54. An attachment member 81 is rotatably attached to the front side of a portion 82a that extends downward from the guide member 54 in the attachment member 82. That is, the air cylinder 25 is rotatably attached to the guide member 54 via the attachment members 80 to 82.

  [C] The servo motor 83 is fixedly attached to the bottom of the head main body 23, and is disposed on the back side of the portion 82a of the attachment member 82 that extends downward from the guide member 54. A motor shaft (not shown) of the servo motor 83 is attached and fixed to an input shaft (not shown) of the speed reducer 84, and an output shaft 85 of the speed reducer 84 is a through hole (not shown) formed in the portion 82a of the mounting member 82. The tip of the output shaft 85 of the speed reducer 84 protruding from the portion 82a is fixedly attached to the mounting member 81.

  [D] The electrode tips 26 and 27 are arranged at positions that overlap when the welding head 50 is viewed from the side. The air cylinder 25 and the piston 69 are arranged in front of the welding head 50 in front of the air cylinder 24 and the piston 68. When the welding head 50 is viewed from the front side, the tip end of the piston 68 is bent leftward, and the tip of the piston 69 is bent rearward.

[Operation and Effect of Second Embodiment]
Also in the second embodiment, as in the first embodiment, the interval between the guide members 53 and 54 can be arbitrarily set by controlling the rotation direction and the rotation amount of the servo motor 60.
Therefore, in the second embodiment, in the state where the air cylinder 25 is arranged in the direction perpendicular to the rail 52, the same operation and effect as in the first embodiment can be obtained.

Since the output shaft 85 of the speed reducer 84 is fixedly attached to the mounting member 81, the mounting member 81 is rotationally driven by the servo motor 83 via the speed reducer 84. The air cylinder 25 is fixedly attached to each of the mounting members 80 and 81 which are integral parts.
Therefore, when the welding head 50 is viewed from the front side, when the output shaft 85 of the speed reducer 84 is rotated clockwise, the air cylinder 25 tilts toward the air cylinder 24 according to the amount of rotation (FIG. 10, FIG. 11). Further, when the output shaft 85 of the speed reducer 84 is rotated in the counterclockwise direction, the air cylinder 25 tilts to the opposite side of the air cylinder 24 according to the amount of rotation (FIG. 12).

Therefore, the control circuit 46 controls the rotation direction and rotation amount of the servo motor 83 to control the rotation direction and rotation amount of the output shaft 85 of the speed reducer 84, whereby the tilt direction and tilt angle of the air cylinder 25 are arbitrarily set. Can be set.
The speed reducer 84 converts the high speed / low torque rotational energy input from the servo motor 83 to the input shaft to the low speed / high torque and outputs it from the output shaft. The speed of the servo motor 83 is required. It is provided in order to increase the torque by reducing the rotation speed. Therefore, the heavy air cylinder 25 can be tilted using the servo motor 83 with a small torque.

Here, the air cylinder 25 and the piston 69 are arranged in front of the welding head 50 in front of the air cylinder 24 and the piston 68.
Therefore, as shown in FIG. 10, when the air cylinder 25 is tilted toward the air cylinder 24, it is possible to prevent the air cylinder 25 from contacting and interfering with the air cylinder 24, and the welding head 50 from the front side. When viewed, the air cylinders 24, 25 can be crossed.

  FIG. 14 shows the air cylinders 24 and 25, the pistons 68 and 69, the electrode tips 26, and the like when spot welding is performed on the curved metal plates Wa and Wb using the spot welding apparatus 20 of the second embodiment. It is explanatory drawing which shows the state of 27. FIG.

  In the second embodiment, since the air cylinder 25 can be tilted, the normal lines Na and Nb of the seating surface 30a (point contact portion 30d) of the welding location (spotting point) in the curved metal plates Wa and Wb are provided. The direction and the pressurizing direction of the electrode tips 26 and 27 (the expansion and contraction direction of the pistons 68 and 69) can be matched.

That is, as shown in FIG. 14A, when the metal plates Wa and Wb are concave, the directions of the normal lines Na and Nb and the directions of the normal lines Na and Nb are obtained by tilting the air cylinder 25 toward the air cylinder 24. The pressing directions of the electrode tips 26 and 27 can be matched.
As shown in FIG. 14B, when the metal plates Wa and Wb are convex, the directions of the normal lines Na and Nb are obtained by tilting the air cylinder 25 to the opposite side of the air cylinder 24. And the pressing directions of the electrode tips 26 and 27 can be matched.

  Therefore, according to the second embodiment, by simply tilting the electrode tip 27 with respect to the electrode tip 26 at an appropriate angle only by controlling the rotation direction and the rotation amount of the servo motor 83, the curved metal plate It is possible to match the directions of normal lines Na and Nb of the welding locations (spots) with the pressing directions of the electrode tips 26 and 27, so that reliable spot welding can be performed on the curved metal plate.

  15 shows the air cylinders 24 and 25, the pistons 68 and 69, the electrode tips 26, and the like when spot welding is performed on the curved metal plates Wa and Wb using the spot welding apparatus 20 of the first embodiment. It is explanatory drawing which shows the state of 27. FIG.

Since the air cylinder 25 cannot be tilted in the first embodiment, the directions of the normal lines Na and Nb of the seating surface 30a (point contact portion 30d) of the welded portion (spot) in the curved metal plates Wa and Wb and The pressurizing direction of each electrode tip 26, 27 (the expansion / contraction direction of each piston 68, 69) cannot be matched.
That is, in the first embodiment, similarly to the techniques of Patent Document 1 and Patent Document 2, the electrode tips 26, perpendicular to the planar metal plates Wa, Wb as shown in FIGS. Since only the function to pressurize 27 is provided, it is not possible to perform reliable spot welding on each of the curved metal plates Wa and Wb as shown in FIG.

[Another embodiment]
By the way, the present invention is not limited to the above-described embodiments, and may be embodied as follows. Even in this case, operations and effects equivalent to or more than those of the above-described embodiments can be obtained.

(1) In each embodiment, as long as the electrode tips 26 and 27 can move forward and backward, the air cylinders 24 and 25 can be moved back and forth to any mechanism (for example, a mechanism using a hydraulic cylinder, a mechanism using a ball screw). Or a mechanism using a rack and pinion).
For example, in the case of an advancing / retreating mechanism using a ball screw, the electrode tips 26 and 27 may be attached to a ball nut and a male screw screwed into the ball nut may be driven by a motor.
In the case of a forward / backward moving mechanism using a rack and pinion, the electrode tips 26 and 27 may be attached to the rack, and the pinion screwed into the rack may be driven by a motor.

  (2) In the second embodiment, the air cylinder 24 may be tiltable similarly to the air cylinder 25. In this way, the angle formed by the electrode tips 26 and 27 can be set with higher accuracy, so that the operation and effect of the second embodiment can be further enhanced.

  (3) In each of the above embodiments, one of the ball screws 57 and 58 may be omitted, and only one of the air cylinders 24 and 25 may be movable.

  (4) In each of the above-described embodiments, the feed screw mechanism may be configured by removing the ball from the guide members 53 and 54 of the ball screws 57 and 58 and using only female screws.

  (5) In each of the above embodiments, the ball screws 57 and 58 are simultaneously driven by one servomotor 60. However, an individual servo motor may be provided for each of the ball screws 57 and 58, and the ball screws 57 and 58 may be driven separately. In this way, only one of the air cylinders 24 and 25 can be translated.

  (6) In each of the above embodiments, if each guide member 53, 54 can be translated, each ball screw 57, 58 can be moved to any translation mechanism (for example, a mechanism using a rack and pinion, an air cylinder, A mechanism using a hydraulic cylinder may be used.

Patent Document 2 describes that an air cylinder is used as the pressurizing means, but this pressurizing means (air cylinder) presses a pair of electrodes individually toward the material to be welded. Thus, the distance between the pair of electrodes is not variable. And it is not disclosed at all in patent document 1 and does not suggest about changing the space | interval of an electrode using this pressurization means.
For this reason, it is not easily conceivable by those skilled in the art from Patent Document 2 to replace the ball screws 57 and 58 of the above-described embodiments of the present invention with a mechanism using an air cylinder.

  (7) Although each said embodiment is applied to the welding apparatus which performs a series spot welding method, this invention is applicable also to the welding apparatus which performs an indirect welding method.

The perspective view which shows schematic structure of the spot welding apparatus 20 in 1st Embodiment and 2nd Embodiment which actualized this invention. The circuit diagram which shows the electric constitution of the control apparatus 40 which controls the welding current supplied to each electrode tip 26,27 of the spot welding apparatus 20. FIG. The partial cross section figure for demonstrating the spot welding process of the metal plates Wa and Wb by the electrode tips 26 and 27 of the spot welding apparatus 20. FIG. FIG. 4A is a plan view of the welding head 50 of the first embodiment. FIG. 4B is a front view of the welding head 50 according to the first embodiment. FIG. 5A is a plan view of the welding head 50 of the first embodiment. FIG. 5B is a front view of the welding head 50 of the first embodiment. The right view of the welding head 50 of 1st Embodiment. The right view of the welding head 50 of 1st Embodiment. FIG. 8A is a plan view of the welding head 50 of the second embodiment. FIG. 8B is a front view of the welding head 50 of the second embodiment. FIG. 9A is a plan view of the welding head 50 of the second embodiment. FIG. 9B is a front view of the welding head 50 of the second embodiment. FIG. 10A is a plan view of the welding head 50 of the second embodiment. FIG. 10B is a front view of the welding head 50 of the second embodiment. The front view of the welding head 50 of 2nd Embodiment. The front view of the welding head 50 of 2nd Embodiment. The right view of the welding head 50 of 2nd Embodiment. Using the spot welding apparatus 20 of the second embodiment, the states of the air cylinders 24 and 25, the pistons 68 and 69, and the electrode tips 26 and 27 when spot welding is performed on the curved metal plates Wa and Wb. FIG. The state of each air cylinder 24, 25, each piston 68, 69, and each electrode tip 26, 27 when spot welding is performed on each curved metal plate Wa, Wb using the spot welding device 20 of the first embodiment. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Spot welding apparatus 23 ... Head main body 24, 25 ... Air cylinder 26, 27 ... Electrode tip 26a, 27a ... Tip part of electrode tip 30 ... Convex part 30a ... Seat surface 35 ... General part 40 ... Control apparatus 42 ... Welding transformer 44 ... Voltage detector 46 ... Control circuit 48 ... AC power supply 50 ... Welding head 51, 52 ... Rail 53, 54 ... Guide member 55, 56 ... Male screw 57, 58 ... Ball screw 59, 66, 67, 74, 75, 80 ... 82 ... Mounting member 60,83 ... Servo motor 61 ... Motor shaft 62-64 ... Toothed pulley 65 ... Toothed belt 68,69 ... Piston 84 ... Speed reducer SCR1, SCR2 ... Thyristor Wa, Wb ... Metal plate

Claims (3)

This is a series spot welding apparatus in which a pair of spaced apart electrodes are brought into pressure contact with one surface of two superimposed metal plates, a welding current is passed between both electrodes, and these two metal plates are welded. And
The pair of electrodes pressurizes the metal plate in the same direction,
Parallel movement means for varying the interval between the pair of electrodes by translating at least one of the pair of electrodes with respect to the other in a direction perpendicular to the pressing direction of the metal plate is provided. Series spot welding equipment characterized by. This is a series spot welding apparatus in which a pair of spaced apart electrodes are brought into pressure contact with one surface of two superimposed metal plates, a welding current is passed between both electrodes, and these two metal plates are welded. And
By tilting at least one of the pair of electrodes at an arbitrary angle with respect to the other, a normal direction of a welded portion on the surface of the metal plate, and a direction in which the pair of electrodes press the metal plate A series spot welding apparatus comprising a tilting means for matching the two. This is a series spot welding apparatus in which a pair of spaced apart electrodes are brought into pressure contact with one surface of two superimposed metal plates, a welding current is passed between both electrodes, and these two metal plates are welded. And
Translation means for varying the distance between the pair of electrodes by translating at least one of the pair of electrodes with respect to the other in a direction perpendicular to the pressing direction of the metal plate;
By tilting at least one of the pair of electrodes at an arbitrary angle with respect to the other, a normal direction of a welded portion on the surface of the metal plate, and a direction in which the pair of electrodes press the metal plate A series spot welding apparatus comprising a tilting means for matching the two.

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