JP2555687B2 - Indirect spot welding method - Google Patents

Description

The present invention relates to a spot welding apparatus, and more particularly to a spot welding apparatus using a work robot.

b. Related Art FIG. 4 is a perspective view of a spot welding apparatus using a work robot according to the related art.

A welding gun G is attached to the tip of the arm of the work robot ROBOT, and a large current is applied to a workpiece (not shown) held by the welding gun G to heat and weld the workpiece.

Electric current is supplied to the welding gun as follows.
The output of the timer contactor TM including the switch circuit for interrupting the current is input to the primary side of the transformer PT, and the output from the secondary side is input to the welding gun G via the kickless cable KL and the auxiliary cables AX1 and AX2. Sent. As shown in FIG. 5, the welding gun is provided with two electrodes PL1 and PL2 insulated from each other, and the current is one auxiliary cable AX1, one electrode PL1, one member W1 to be welded, and the other member to be welded. W
2, the other electrode PL2, the other auxiliary cable AX2 or the reverse path. In order to follow the position of the welding gun G attached to the work robot, the transformer PT is formed as a welding portable transformer, and the welding portable transformer PT is suspended on the gantry rail RAIL and can be moved along the gantry rail. It is configured. The pneumatic cable AIR for transmitting the air pressure for operating the welding gun G and the cooling water hose WATER for supplying the cooling water for cooling the welding gun also follow the movement of the welding gun G. It is held along the kickless cable KL. The kickless cable, the pneumatic cable, and the cooling water hose are bundled and movably suspended on the mount rail RAIL via the balancer BL.

The conventional spot welding apparatus having this configuration has the following problems.

The rail RAIL for suspending the portable welding transformer PT for movement is required. For this reason, the facility cost for spot welding and the space occupied by the apparatus increase.

The cable on the secondary side of the transformer is long, so a portable type with a large capacity must be used as the welding transformer.

It is necessary to use expensive cables such as the kickless cable KL and the auxiliary cables AX1 and AX2, and since these cables are broken, the cables must be replaced frequently.

Since the weight of cables and the like becomes a load on the work robot ROBOT, it is difficult to operate the robot at high speed, and further, an abnormality in robot operation such as an axis coincidence abnormality may occur.

INDUSTRIAL APPLICABILITY The present invention relates to a spot welding apparatus using a work robot, which is capable of performing spot welding without using a portable welding transformer, a pedestal rail for suspending the welding transformer, a kickless cable, or the like. I will provide a.

A prior art indirect spot welding apparatus is disclosed in Japanese Utility Model Publication No. 61-42694.

In this publication, one output terminal of a transformer is connected to a welding gun, the other output terminal of a transformer is connected to an electrode provided on an electrode attachment device, and the electrode is brought into contact with an object to be welded.
An indirect spot welding device that performs spot welding by holding an object to be welded with a welding gun, and one output terminal of the transformer is connected to the first welding gun, and the other output terminal is connected to the second welding gun. However, there is disclosed an indirect spot welding apparatus that holds an object to be welded with both welding guns and applies a current to perform spot welding.

c. Problem to be Solved by the Invention In these indirect spot welding, the fixing of the work piece and the connection with the transformer output terminal are performed separately.

INDUSTRIAL APPLICABILITY The present invention is an indirect spot in which a welding current can be made to flow by holding the object to be welded and simultaneously connecting to the output terminal of the transformer and holding the object to be welded with the welding gun. An object of the present invention is to provide a welding method and an apparatus therefor.

d. Means for Solving the Problems The above-mentioned problems are provided on a workpiece placing means having a first surface made of a conductor and a second surface electrically insulated from the first surface. , The first member to be welded W1 and the second member to be overlapped
To be welded consisting of the welded member W2 of
W1 is placed so as to come into contact with the second surface of the object-to-be-welded mounting means, and has a contact surface electrically connected to one output terminal of the welding transformer. The object to be welded is fixed using a fixing means for fixing the object to be welded by pressing the member to be welded W2, and the first surface of the object to be welded mounting means is connected to the other output terminal of the welding transformer, With the electrodes P1 and P2 of the welding gun having the first electrode and the second electrode which are electrically short-circuited to each other, the first surface of the workpiece mounting means and the first workpiece W1 are connected to each other. An indirect spot welding method, characterized by holding an object to be spot-welded by supplying electric power from a welding transformer, and a welding transformer, and a first surface and a first surface made of a conductor. Of the object to be welded, which has a second surface electrically insulated, and a welding transformer. Has a contact surface connected to the other output terminal via the first electrical connecting means, and the first welded portion W1 contacts the second surface of the workpiece placing means. Fixing means for fixing the object to be welded by pressing the second member W2 to be welded placed on the object to be welded by the contact surface and the first surface of the object to be welded means The second electrical connection means electrically connected to the other output terminal of the transformer, the welding gun having the first electrode and the second electrode electrically short-circuited to each other, and the electrodes P1 and P2. , A welding gun moving means for moving a welding gun to hold the first surface of the object to be welded means and the first member to be welded W1 at a predetermined position, Claim 1 (1) It has been solved by an indirect spot welding apparatus for carrying out the indirect spot welding method described in the paragraph.

e. Action The welded object is fixed by the object to be welded mounting means and the fixing means. The welding current is the output terminal of the transformer, the first surface of the workpiece mounting means, the electrodes P1 and P2 of the welding gun, and the first surface of the workpiece.
Of the first welded member W1 and the second welded member W2 through the closed circuit formed by the welded member W1, the second welded member W2, the contact surface of the fixing means, and the output terminal of the transformer. The members held by the electrodes P1 and P2 of the welding gun on the joint surface generate heat and are spot welded.

f. Example FIG. 1 is a perspective view of the main part of the indirect spot welding apparatus according to the present invention, and FIG. 2 is a conceptual enlarged view of FIG.
FIG. 3 is a block diagram of the indirect spot welding apparatus according to the present invention.

At one end of a sandwich copper plate S formed by fixing a first conductive plate C _A and a second conductive plate C _B each made of a copper plate on both surfaces of an insulating plate I _A made of an insulator, the conductive plates C _A , C _B Are connected to the output terminals T1 and T2 of the welding transformer TM.

The object to be welded W including the first member to be welded W1 and the second member to be welded W2 is a plurality of appropriately placed object-to-be-welded placing means ST.
It is placed on top.

The workpiece mounting means ST is composed of a sandwich copper plate in which conductive plates C1 and C2 made of copper plates are attached to the first surface and the second surface of an insulating plate I made of an insulating material so as to be insulated from each other.

The first conductive plate C _A of the sandwich copper plate S and the conductive plate C1 of the first surface of the object to be welded ST are electrically connected using the first connecting member CN1, and the second surface of the second surface The conductive plate C2 is in electrical contact with the first weld W1 of the workpiece W.

The first member to be welded W1 of the object to be welded W has the end portion of the second member to be welded W2 wound at the welding point as shown in FIGS. 2 and 3, for example.

The electrodes P1 and P2 of the welding gun G are electrically short-circuited.
Therefore, when the conductive plate C1 on the first surface of the object to be welded ST and the first member to be welded W1 of the object to be welded are held by using the electrodes P1 and P2 of the welding gun C, The member to be welded is electrically short-circuited with the conductive plate C1 on the first surface of the object mounting means.

The second member to be welded W2 of the object to be welded W is fixed by a plurality of fixing means FX arranged at appropriate positions. Fixing means FX,
It has a rod body FB which is rotatably supported at one point of the pillar P and is urged by using a fluid pressure means H, and has an abutting member FC made of a conductor insulated from the rod body FB. The welded portion W is fixed by pressing the welded object W with the contact member FC.

The contact member FC of the fixing means FX is connected to the second conductor C _B of the sandwich copper plate S by means of the electrical connecting means CN2 composed of a plurality of copper strips, and the second conductive plate C _B is at its end. Connected to Welding Transformer TM.

Therefore, the output terminal of the welding transformer TM, the first conductive plate C _A , the first connection member CN1, the first surface conductive plate C1, the welding gun G, the first welded member W1, and the second welded member. member W2, the contact member FC fixing means, the electrical connection means CN2, the second conductive plate C _B, open circuit composed of the welding transformer is formed.

In this way, the welding current control means CONT including the switching circuit and the like is coupled to the conductive plate C1 on the first surface of the object to be welded means and the contact member FC of the fixing means via the welding transformer TM. It That is, the welding preparation is completed by fixing the welding object using the welding object placing means and the fixing means. In this state, the spot is welded by sandwiching the welding spot with a welding gun. Indirect spot welding can be performed by moving the welding gun as needed.

The welding gun is moved by using a normal work robot ROBOT. At this time, it is unnecessary to attach a welding transformer to the tip of the arm of the work robot. As a result, the inertial mass becomes lighter, and the robot can be moved at high speed. Further, since the shape of the welding gun can be reduced, welding in a narrow space is possible.

The air pressure for welding gun control is the air pressure supply pipe AI.
The cooling water for cooling the welding gun is supplied using R, and the cooling water supply pipe WATER is used.

g. Effects of the invention i) The welding cables such as the kickless cable and the auxiliary cable that are laid around by the work robot are not required. As a result, the load on the robot arm is reduced.

ii) Since the position of the transformer can be fixed, it is not necessary to use a portable transformer and a normal welding transformer can be used. As a result, the occupied volume of the transformer becomes about 2/3. In addition, a stand for suspending the portable transformer is unnecessary.

iii) Since the transformer and sandwich copper plate are connected by a cable, copper bar, etc., there is almost no disconnection accident.

iv) It can be constructed using general-purpose parts.

v) By fixing the object to be welded using the object to be welded mounting means and the object to be welded fixing means, the preparation for indirect spot welding is completed, and the welding gun is appropriately moved using the work robot, Indirect spot welding can be performed by sandwiching the welding points.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an indirect spot welding apparatus according to the present invention, FIG. 2 is a conceptual diagram enlarged view of FIG. 1, and FIG. 3 is a block diagram of an indirect spot welding apparatus according to the present invention. FIG. 4 is a perspective view of a spot welding apparatus using a work robot according to the prior art, and FIG. 5 is a conceptual diagram of a welding gun used in the spot welding apparatus of FIG. AIR …… Air pressure supply pipe C _A , C _B , C ₁ , C ₂ …… Conductive plate CN1, CN2 …… Connecting member CONT …… Welding current control device FB …… Bar FC …… Abutting member FX …… Fixed Means G …… Welding gun H …… Fluid pressure means I, I _A …… Insulation plate P …… Pole P ₁ , P ₂ …… Electrode ROBOT …… Work robot S …… Sandwich copper plate ST …… Place workpiece to be welded Means T1, T2 …… Output terminal TM …… Welding transformer W …… Welded object W1 …… First welded member W2 …… Second welded member WATER …… Cooling water supply pipe

Claims (2)

(57) [Claims] 1. A first object to be welded, which is superposed on a workpiece mounting means having a first surface made of a conductor and a second surface electrically insulated from the first surface. An object to be welded consisting of the welded member W1 and the second member to be welded W2 is referred to as the first member to be welded W1.
Is placed so as to come into contact with the second surface of the object to be welded means, and has a contact surface electrically connected to one output terminal of the welding transformer. The object to be welded is fixed by using a fixing means for fixing the object to be welded by pressing the welding member W2, and the first surface of the object to be welded mounting means is connected to the other output terminal of the welding transformer, Both electrodes P1 and P2 of a welding gun having a first electrode and a second electrode that are electrically short-circuited hold the first surface of the workpiece mounting means and the first member W1 to be welded. Then, the indirect spot welding method is characterized in that the workpiece is spot-welded by supplying electric power from the welding transformer. 2. A welding transformer, a workpiece mounting means having a first surface made of a conductor and a second surface electrically insulated from the first surface, and one of the welding transformers. An abutting surface connected to the output terminal via the first electrical connecting means, so that the first welded portion W1 contacts the second surface of the workpiece placing means. The fixing means for fixing the welded object by pressing the second welded member W2 of the placed welded object with the abutting surface, and the first surface of the welded object placing means are connected to the welding transformer. Second electrically connected to the other output terminal
Electrical connection means, a welding gun having a first electrode and a second electrode electrically short-circuited to each other, and both electrodes P1, P
2. At the predetermined position, the first of the above-mentioned objects to be welded means is placed.
Indirect spot welding for carrying out the indirect spot welding method according to claim (1), which comprises a welding gun moving means for moving the welding gun to hold the first welding target member W1. apparatus.