JP2020104128A - Spot welding gun and spot welding method - Google Patents

Abstract

To provide a spot welding gun and a method of the same which can reduce weight and can improve workability.SOLUTION: A spot welding gun 10 mainly includes a first electrode part 11, a second electrode part 12 arranged opposite to the first electrode part 11, a fixing part 13 which fixes and supports the first electrode part 11 and the second electrode part 12, and an operation part 14 which is connected to the fixing part 13. An operator arranges the first and second electrode parts 11, 12 on a desired part of a vehicle panel 21, and operates to gouge the operation part 14 to form a nugget of two spots by one welding process. As a result, an actuator for moving the first and second electrode parts 11, 12 becomes unnecessary to reduce weight and improve workability.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a spot welding gun and a spot welding method for increasing the number of welding spots and increasing the welding strength, and reducing the weight and improving the workability when spot welding an object to be welded such as an automobile panel.

A structure shown in FIG. 5 is known as a spot welding gun 100 used in a conventional welding apparatus. FIG. 5 is a front view illustrating a conventional spot welding gun 100.

As shown in FIG. 5, the spot welding gun 100 mainly includes a gun head 101, a main electrode rod 102 arranged at the tip of the gun head 101, and a gun arm portion 104 rotatably attached to an arm attachment base portion 103. And a sub-electrode rod 105 which is disposed at the tip of the gun arm portion 104 and faces the main electrode rod 102, and hand grip portions 106 and 107 for an operator to grip and work.

A state in which the main electrode rod 102 linearly moves back and forth by the air pressure supplied from an air supply mechanism (not shown), and a work is sandwiched between the tips of the main electrode rod 102 and the auxiliary electrode rod 105 and pressed. Spot welding can be performed at. Then, the gun arm portion 104 rotates in either a horizontal or vertical direction with the arm attachment base portion 103 as a fulcrum, so that welding work can be performed even at a welding position at a recessed position or a position where an obstacle member exists. It can be performed (for example, refer to Patent Document 1).

JP-A-2002-224845

In the spot welding gun 100, the main electrode rod 102 and the sub-electrode rod 105 sandwich the work piece at its tip, and the work piece is pressurized by the air pressure from the air supply mechanism on the main electrode rod 102 side. Then, the spot welding is performed by passing an electric current. At this time, the main electrode rod 102 and the sub electrode rod 105 face each other in a linear positional relationship, so that a welding point of one welding point, a so-called nugget, is formed on the work in one welding step.

In spot welding, in order to improve the welding strength, continuous welding points are made in one direction on the workpiece, but if the distance between continuous welding points becomes narrower, when forming a new welded spot, the nugget at the adjacent already welded point will be formed. On the other hand, there is a problem that shunt flow occurs and spot welding cannot be performed. On the other hand, in order to solve the problem that cannot be welded due to the shunt, it is necessary to widen the distance between continuous welding points. In this case, the number of welding points for the work is reduced, and the desired welding strength cannot be obtained. Issues arise.

Further, the spot welding gun 100 has a gun head 101 and the like for supplying air to the arm attachment base portion 103, the gun arm portion 104 and the main electrode rod 102, and its weight becomes heavy. Therefore, the operator needs to operate the hand grips 106 and 107 with both hands, which causes a problem that workability deteriorates.

The present invention has been made in view of the above circumstances, and when spot-welding an object to be welded such as an automobile panel, the number of welding points is increased to improve the welding strength, and the workability is reduced by reducing the weight. To provide a spot welding gun and a spot welding method therefor.

The spot welding gun of the present invention is a spot welding gun including a first electrode portion and a second electrode portion that are arranged to face each other with a gap for inserting an object to be welded. , The first electrode portion pressurizes a first pressure area of one main surface of the object to be welded, and the second electrode portion is opposite to the one main surface of the object to be welded. The second pressure area of the other main surface on the side of the first pressure area and the second pressure area in the horizontal direction with respect to the one main surface of the object to be welded. In the shifted state, an electric current is applied to the object to be welded to perform two-point welding.

In addition, in the spot welding gun of the present invention, a fixing portion that fixes the first electrode portion and the second electrode portion in the thickness direction while maintaining the gap, and is connected to the fixing portion. And an operation unit for operating the first electrode unit and the second electrode unit, wherein the first electrode unit and the second electrode are inserted through the fixing unit by hollowing out the operation unit. The part is rotated with respect to the object to be welded, and the first pressure region and the second pressure region are generated in the object to be welded.

Further, in the spot welding gun of the present invention, the operating portion is rotatably connected to the fixing portion in the horizontal direction so that the axis of the operating portion substantially coincides with the center of the gap. It is characterized by being

Further, in the spot welding gun of the present invention, the axial center of the first electrode portion is eccentric with respect to the axial center of the second electrode portion before the operation portion is hollowed out. To do.

In the spot welding method of the present invention, the object to be welded is inserted into the gap between the first electrode portion and the second electrode portion of the spot welding gun, and the first electrode portion and the second electrode portion are inserted. A spot welding method in which an electric current is applied while the object to be welded is pressed to weld the object to be welded, wherein the first electrode portion presses one main surface of the object to be welded. The first pressurizing region and the second pressurizing region in which the second electrode part presses the other main surface of the welded object opposite to the one main surface of the welded object are provided. An electric current is applied to the object to be welded in a state in which the nuggets are separated from each other in the horizontal direction with respect to the one main surface to form two nugget points separated in one welding process.

Further, in the spot welding method of the present invention, the spot welding gun includes a fixing portion that fixes the first electrode portion and the second electrode portion in the thickness direction while maintaining the gap. An operating portion that is connected to a fixed portion and that operates the first electrode portion and the second electrode portion is further provided, and the operation portion is provided in the gap between the first electrode portion and the second electrode portion. After inserting the object to be welded, the operation portion is hollowed, the first electrode portion and the second electrode portion are rotated with respect to the object to be welded through the fixing portion, and the object to be welded is It is characterized in that the first pressure area and the second pressure area are generated in the object.

Further, in the spot welding method of the present invention, in the state before the operation portion is hollowed, the axis of the first electrode portion is eccentric with respect to the axis of the second electrode portion. To do.

Further, in the spot welding method of the present invention, the object to be welded is formed by stacking two plate materials, and the nugget at the two hit points is the two plate materials below the first pressure area. It is characterized in that the contact area and its periphery and the contact area of the two plate members above the second pressure area and its periphery are formed separately.

Further, in the spot welding method of the present invention, the object to be welded is formed by stacking three plate materials, and the nugget at the two dot points is the first electrode portion below the first pressure area. A contact area between the plate material in contact with the plate material and the plate material positioned in the middle and the periphery thereof, and the plate material in contact with the second electrode part above the second pressure area and the plate material positioned in the middle It is characterized in that it is formed so as to be separated from the contact area with and the periphery thereof.

A spot welding gun according to the present invention includes a first electrode portion and a second electrode portion that are arranged to face each other with a gap for inserting an object to be welded, and the first electrode portion. The first pressure area due to and the second pressure area due to the second electrode portion are in a state of being shifted in the horizontal direction with respect to one main surface of the object to be welded. With this structure, the welding strength can be improved by forming the nugget with two spots in one spot welding process.

In addition, the spot welding gun of the present invention includes a fixing portion that fixes the first and second electrode portions, and an operation portion that is rotatably connected to the fixing portion. The second electrode portion can be rotated with respect to the object to be welded to generate the first pressure area and the second pressure area in the object to be welded. With this structure, the object to be welded can be pressed by the first and second electrode portions without using an actuator. The workability can be improved by reducing the weight of the spot welding gun.

Further, in the spot welding gun of the present invention, the operating portion is horizontally rotated with respect to the fixed portion so that the axis of the operating portion substantially coincides with the center of the gap between the first and second electrode portions. It is freely connected. With this structure, the object to be welded can be pressed by the first and second electrode parts by hollowing out the operation part, and the pressing force by the first and second electrode parts is made as uniform as possible. be able to.

Further, in the spot welding gun of the present invention, the axial center of the first electrode portion is eccentric with respect to the axial center of the second electrode portion before the operation portion is hollowed. With this structure, it is possible to reliably form the nuggets at the two hitting points in a single welding step, and to improve the welding strength.

In the spot welding method of the present invention, the object to be welded is inserted into the gap between the first electrode portion and the second electrode portion of the spot welding gun, and the first electrode portion causes one main surface of the object to be welded to be inserted. A first pressure area for applying pressure and a second pressure area for applying pressure to the other main surface of the second electrode portion opposite to the one main surface of the object to be welded An electric current is applied to the object to be welded in a state in which the nugget is separated from the surface in the horizontal direction to form two nugget points separated in one welding process. By this spot welding method, a nugget with two hit points can be formed in one spot welding step, and the welding strength can be improved.

Further, in the spot welding method of the present invention, after inserting the object to be welded into the gap between the first electrode portion and the second electrode portion, the operation portion is hollowed and the first electrode portion and the first electrode portion are inserted through the fixing portion. The second electrode portion can be rotated with respect to the object to be welded to generate the first pressure area and the second pressure area in the object to be welded. With this spot welding method, the object to be welded can be pressed by the first and second electrode portions by the manual work of the worker. An actuator is not required for the spot welding gun, and the weight of the spot welding gun is reduced, so that workability can be improved.

Further, in the spot welding method of the present invention, the axial center of the first electrode portion is eccentric with respect to the axial center of the second electrode portion before the operation portion is hollowed. By this spot welding method, it is possible to surely form the two nuggets at a distance from each other and to improve the welding strength.

Further, in the spot welding method of the present invention, the object to be welded is formed by stacking two plate materials, and the nugget at two hit points is the contact area of the two plate materials below the first pressure area and the contact area of the two plate materials. It can be formed so as to be separated from the periphery thereof and the contact region of the two plate members above the second pressure region and the periphery thereof. By this spot welding method, the nuggets at the two hitting points can be formed at a short distance from each other in one spot welding step, and the welding strength can be improved.

Further, in the spot welding method of the present invention, the object to be welded is formed by stacking three plate materials, and the nugget at two hit points is a plate material that contacts the first electrode portion below the first pressure area. And a contact area between the plate material positioned in the middle and the periphery thereof, and a contact area between the plate material contacting the second electrode portion above the second pressure area and the plate material positioned in the middle and the periphery thereof. It can be formed separately. By this spot welding method, nuggets with two hit points can be formed at a short distance from each other in one spot welding process. Further, the welding strength can be improved by forming the nuggets at two hit points with respect to the plate material positioned in the middle and the plate materials positioned on the upper and lower surfaces, respectively.

It is a side view explaining the spot welding gun which is one embodiment of the present invention. It is a side view explaining the spot welding method which is one embodiment of the present invention. It is an (A) sectional view, a (B) sectional view, a (C) sectional view, and a (D) sectional view explaining a spot welding method which is one embodiment of the present invention. It is a perspective view explaining the spot welding method which is one embodiment of the present invention. It is a front view explaining the conventional spot welding gun.

First, a spot welding gun 10 and a spot welding method according to an embodiment of the present invention will be described in detail with reference to the drawings. In the description of the present embodiment, the same reference numerals are used for the same members in principle, and repeated description will be omitted.

FIG. 1 is a side view illustrating a spot welding gun 10 of this embodiment. FIG. 2 is a side view illustrating a spot welding method using the spot welding gun 10 of this embodiment. 3A to 3D are cross-sectional views illustrating the spot welding method of the present embodiment. FIG. 4 is a perspective view illustrating the spot welding method of the present embodiment.

First, the structure of the spot welding gun 10 will be described with reference to FIG. As shown in the figure, the spot welding gun 10 is used by being incorporated in a spot welding device (not shown) used in an automobile assembly line or the like. The spot welding device has a transformer, a control device, and a cooling device built therein, and the spot welding gun 10 is connected to the spot welding device via a welding cable 15 and a cooling pipe 16. Then, the worker can perform the spot welding work by using the spot welding gun 10 at a desired portion of the vehicle panel 21 (see FIG. 2) which is the object to be welded.

The spot welding gun 10 mainly includes a first electrode portion 11, a second electrode portion 12 arranged to face the first electrode portion 11, a first electrode portion 11 and a second electrode portion. It has a fixed portion 13 that fixes and supports the portion 12, and an operation portion 14 that is connected to the fixed portion 13.

A welding cable 15 is connected to each of the first and second electrode portions 11 and 12, and a large current is caused to flow from the first electrode portion 11 to the second electrode portion 12 during a welding operation, so that a vehicle panel is provided. A nugget is formed at the welding point 21.

The first electrode portion 11 is formed of, for example, a copper alloy material having excellent electric conductivity and thermal conductivity, and is formed in a hollow round bar shape. Then, the cooling pipe 16 is arranged in the first electrode portion 11, and by circulating the cooling water in the first electrode portion 11, the first electrode portion 11 becomes a high temperature state during welding. Is prevented from passing.

The tip 11A of the first electrode portion 11 is formed, for example, in a curved shape, and the details thereof will be described later, but when the vehicle panel 21 is pressed, a desired contact is made while rotating with respect to the vehicle panel 21. Can be aligned with the area. Then, the tip end 11A of the first electrode portion 11 can press the vehicle panel 21 in the contact area with the vehicle panel 21.

Similarly to the first electrode portion 11, the second electrode portion 12 is also formed of a copper alloy material and has a round bar shape. Then, the cooling pipe 16 is arranged in the second electrode portion 12, and by circulating the cooling water in the second electrode portion 12, the second electrode portion 12 becomes a high temperature state during welding. Is prevented from passing.

Further, the tip 12A of the second electrode portion 12 is also formed in a curved shape, for example, and is aligned with a desired contact area while rotating with respect to the vehicle panel 21 when pressurizing the vehicle panel 21. can do. The tip 12A of the second electrode portion 12 can press the vehicle panel 21 in the contact area with the vehicle panel 21.

As shown in the figure, the first and second electrode portions 11 and 12 are, for example, formed in a substantially L shape, and have insulating collars 17 with respect to the fixing portion 13 in regions extending in the front-back direction of the paper. It is fixed. The first and second electrode portions 11 and 12 are fixed to the fixing portion 13 via the insulating collar 17 to prevent short circuit.

Specifically, the fixing portion 13 is, for example, a round bar member formed of a stainless material. Then, the first and second electrode portions 11 and 12 are inserted into a pair of through holes (not shown) formed in the fixed portion 13 at regular intervals, and are supported by the fixed portion 13. The first electrode portion 11 is arranged so that its tip end 11A faces downward on the paper surface, and the second electrode portion 12 is arranged so that its tip end 12A faces upward on the paper surface. There is.

With this structure, the tip end 11A of the first electrode portion 11 and the tip end 12A of the second electrode portion 12 have a constant separation width W1 in the thickness direction (vertical direction on the paper surface) of the vehicle panel 21 (see FIG. 2). It is fixed to the fixing portion 13 with the gap 18 included therein. The first and second electrode portions 11 and 12 are not provided with an actuator or the like for varying the separation width W1 of the gap 18, thus realizing the weight saving of the spot welding gun 10 and improving workability. be able to.

The operation unit 14 is, for example, a digital torque wrench, and is arranged so as to extend in a direction perpendicular to the extending direction of the fixing unit 13 (vertical direction on the paper surface) (front-back direction on the paper surface). On the front end side of the operating portion 14, a connecting portion 14A is provided for rotatably connecting along the outer peripheral surface of the fixed portion 13. On the other hand, on the rear end side of the operation section 14, a grip section 14B for an operator to operate the operation section 14 is provided. When not in use, the operation portion 14 is fixed to the connection portion between the second electrode portion 12 and the welding cable 15 via the attachment/detachment lever 19.

Further, as shown by the alternate long and short dash line, the operation portion 14 is fixed to the fixed portion 13 so that the axis 14C of the operation portion 14 substantially coincides with the center of the gap 18 between the first and second electrode portions 11 and 12. Connected to. With this structure, although details will be described later, the first and second electrode portions 11 and 12 are respectively removed by removing the operation portion 14 so that the front surface 21A (see FIG. 3A) and the back surface 21B of the vehicle panel 21 are respectively formed. When pressurizing (see FIG. 3A), the pressure applied to the first and second electrode portions 11 and 12 can be made as uniform as possible.

It should be noted that by hollowing the operating portion 14, the first and second electrode portions 11 and 12 pressurize the front surface 21A and the rear surface 21B of the vehicle panel 21, respectively. Then, the operation unit 14 measures the torque value at the time of pressurization, and the control device (not shown) in the spot welding apparatus determines the pressurization state from the measured value and determines whether the pressurization state is equal to or higher than the set value. When it is determined that there is such a spot, it becomes possible to apply a predetermined current between the first and second electrode portions 11 and 12 to perform spot welding. For example, as an example of flowing the current, as shown in FIG. 1, a limit switch 14D is provided below the operation unit 14, and when the operation unit 14 is carried out, the operation unit 14 causes the limit switch 14D to move. The current flows by contacting with.

Next, a spot welding method using the above spot welding gun 10 will be described with reference to FIG. As illustrated, the first and second electrode portions 11 and 12 are fixed by the fixing portion 13, so that the gap between the tip end 11A of the first electrode portion 11 and the tip end 12A of the second electrode portion 12 is formed. The separation width W1 (see FIG. 1) of 18 (see FIG. 1) does not change. The separation width W1 is a width designed in advance so that the vehicle panel 21 or the like, which is the object to be welded, can be reliably inserted into the gap 18. Therefore, when fixing the first and second electrode portions 11 and 12 to the fixing portion 13, any design change can be made according to the thickness of the object to be welded.

As illustrated, the first and second electrode portions 11 and 12 are not movable in the thickness direction of the vehicle panel 21 (vertical direction in the plane of the drawing) by an actuator or the like. Therefore, the operator first removes the attachment/detachment lever 19 (see FIG. 1) so that the operation portion 14 is rotatable along the outer peripheral surface of the fixed portion 13. Thereafter, the operator holds the grip portion 14B of the operation portion 14, operates the spot welding gun 10, inserts the vehicle panel 21 into the gap 18 from the end portion of the vehicle panel 21, and The electrode parts 11 and 12 are arranged at desired welding points on the vehicle panel 21.

As described above, when the vehicle panel 21 is inserted into the gap 18 between the first and second electrode portions 11 and 12, it depends on the separation width W1 (see FIG. 1) and the thickness of the vehicle panel 21. For example, at least one of the first and second electrode portions 11 and 12 is in contact with the vehicle panel 21, and the other is in non-contact with the vehicle panel 21.

Next, the worker presses the vehicle panel 21 with the first and second electrode portions 11 and 12, so that the grip portion 14B of the operation portion 14 is moved downward, for example, as indicated by an arrow 22. While making it, gouge in the clockwise direction. By the above scooping operation, the fixing portion 13 is inclined at the angle θ1 with respect to the vehicle panel 21 which is horizontal in the front-back direction of the drawing, and the first electrode portion 11 is provided on the front surface 21A of the vehicle panel 21 (FIG. 3A). (Refer to FIG. 2), and the second electrode portion 12 rotates clockwise around the contact point as the center of rotation until it contacts the back surface 21B of the vehicle panel 21.

After that, in a state where the first and second electrode portions 11 and 12 are in contact with the front surface 21A and the rear surface 21B of the vehicle panel 21, respectively, the operator further moves the operation portion 14 in the direction indicated by the arrow 22. Gouge. As a result, the first electrode portion 11 presses the front surface 21A of the vehicle panel 21 downward, while the second electrode portion 12 presses the rear surface 21B of the vehicle panel 21 upward. ..

When the operator moves the grip portion 14B of the operation portion 14 downward and moves it counterclockwise, the operator moves the grip portion 14B of the operation portion 14 upward and moves the grip portion 14B clockwise or counterclockwise. Even in the case, similarly, it is possible to realize a state in which the vehicle panel 21 is pressed by the first and second electrode portions 11 and 12.

Along with the above operation by the operator, in the control device (not shown) in the spot welding device, when the measured value of the pressing force by the first and second electrode portions 11 and 12 reaches the set condition value, Notify the operator that welding is possible. Then, the worker can form a two-shot Nugget separated on the vehicle panel 21 in one welding process by passing a current for a desired time based on the welding conditions.

Next, a spot welding method for forming nuggets with two striking points separated in one welding process will be described with reference to FIGS. 3(A) to 3(D). 3A and 3B show a case where the vehicle panel 21 as the object to be welded is composed of two panels 21C and 21D. On the other hand, FIGS. 3C and 3D show a case where the vehicle panel 21 as the object to be welded is composed of three panels 21E, 21F, and 21G. The following description will be made with reference to FIGS. 1 and 2 as appropriate.

First, in FIG. 3(A), as indicated by the alternate long and short dash line 23, the first electrode portion 11 and the second electrode portion 12 are substantially aligned with each other while the first electrode portion 11 and the second electrode portion 12 are substantially aligned with each other. The portion 11 and the second electrode portion 12 face each other and are fixed by the fixing portion 13 (see FIG. 1).

As described above with reference to FIGS. 1 and 2, the operator holds the grip portion 14B of the operation portion 14 and operates the spot welding gun 10 to move the gap 18 between the first and second electrode portions 11 and 12. Then, the vehicle panel 21, which is the object to be welded, is inserted. Then, while the operator moves the grip portion 14B of the operation portion 14 downward, as shown by the arrow 24, the operator grips the grip portion 14B in the clockwise direction, whereby the first and second electrode portions 11 and 12 are respectively moved to the vehicle. The front surface 21A and the rear surface 21B of the panel 21 are pressed.

As shown in FIG. 3(B), the operator scoops the operating portion 14 so that the first electrode portion 11 has the vehicle panel 21 at the axis indicated by the alternate long and short dash line 23 (see FIG. 3(A)). After contacting the front surface 21A of the vehicle, the curved front end 11A rolls to the right side of the paper surface, and presses the front surface 21A of the vehicle panel 21 downward in the pressing area indicated by the circle 25. On the other hand, the second electrode portion 12 rotates clockwise around the pressure area indicated by the circle 25 as the center of rotation, and the second electrode portion 12 rotates in the pressure area indicated by the circle 26 as the vehicle. The back surface 21B of the panel 21 is pressed upward.

As shown in the drawing, the first and second electrode portions 11 and 12 are disposed on the vehicle panel 21 at a position displaced in the horizontal direction (for example, the left-right direction on the paper) with respect to the front and back surfaces 21A and 21B of the vehicle panel 21. From above and below. Then, when the measured value of the pressing force by the first and second electrode portions 11 and 12 reaches the set condition value, a current is passed for a desired time based on the welding condition, so that the vehicle panel 21 once Two nuggets 28, 29 separated from each other are formed in the welding process.

At this time, the dotted line 27 indicates the path of the current, but the current flows from the first electrode portion 11 to immediately below the pressure area indicated by the circle 25, and then immediately above the pressure area indicated by the circle 26. To the second electrode portion 12. As a result, in the vehicle panel 21, the first nugget 28 is formed immediately below the pressure area indicated by the circle 25, and the second nugget 28 is formed immediately above the pressure area indicated by the circle 26. A nugget 29 is formed.

As described above, since the vehicle panel 21 is composed of the two panels 21C and 21D, the two nuggets 28 and 29 are formed in the boundary region between the panels 21C and 21D and the periphery thereof. Then, the two nuggets 28, 29 are formed so as to be separated from each other so as to have a separation width W2.

As shown in FIG. 3(A), as indicated by the alternate long and short dash line 23, when the axis of the first electrode portion 11 and the axis of the second electrode portion 12 are substantially aligned, It is not limited to the case where the first electrode portion 11 and the second electrode portion 12 face each other. For example, even when the first electrode portion 11 and the second electrode portion 12 face each other in a state where the first electrode portion 11 and the second electrode portion 12 are eccentric from the beginning. good. In this case, the spacing between the two nuggets formed in one welding step is wider than the spacing W2, but the same effect can be obtained.

Next, in FIG. 3C, as indicated by a chain line 31, the first electrode portion 11 and the second electrode portion 12 are substantially aligned with each other in a state where the first electrode portion 11 and the second electrode portion 12 are substantially aligned with each other. The electrode portion 11 and the second electrode portion 12 face each other and are fixed by the fixing portion 13 (see FIG. 1). As described above, the vehicle panel 21 is composed of the three panels 21E, 21F, 21G.

As shown in FIGS. 3(C) and 3(D), the operator scrapes the operation unit 14 (see FIG. 2), and as shown by the arrow 32, the first electrode unit 11 has a circle 33. The surface 21A of the vehicle panel 21 is pressed downward in the pressing area indicated by. On the other hand, the second electrode portion 12 pressurizes the back surface 21B of the vehicle panel 21 to the upper side in the pressurizing region indicated by the circle 34.

Then, when the measured value of the pressing force by the first and second electrode portions 11 and 12 reaches the set condition value, a current is passed for a desired time based on the welding condition, so that the vehicle panel 21 once Two nuggets 35 and 36 separated from each other are formed in the welding process.

As shown in the figure, the dotted line 37 indicates the path of the current, but the current flows from the first electrode portion 11 to immediately below the pressure area indicated by the circle 33, and thereafter, the pressure area indicated by the circle 34. From immediately above to the second electrode portion 12. As a result, the first nugget 35 is formed in the boundary area between the panels 21E and 21F and the periphery thereof, and the second nugget 36 is formed in the boundary area of the panels 21F and 21G and the periphery thereof. The two nuggets 35 and 36 are formed so as to be separated so as to have a separation width W3.

As in the case of FIGS. 3(A) and 3(B), the first electrode portion 11 and the second electrode portion 12 are eccentric from the beginning in the first eccentric state. The electrode part 11 and the second electrode part 12 may face each other.

Next, with reference to FIG. 4, a spot welding method for forming a plurality of nuggets 35, 36 (see FIG. 3(D)) spaced at regular intervals at continuous hit points will be described. It should be noted that the continuous welding point welding method described with reference to FIG. 4 is realized by repeatedly performing the one welding step described with reference to FIGS. 3A to 3D, and therefore will be described below. A description will be given with reference to FIGS. 1 to 3 as appropriate.

In FIG. 4, for example, a frame member 41 forming a part of a frame of a vehicle (not shown) is shown, and the frame member 41 is composed of three panels 42, 43, 44. As shown in the figure, the frames 42 and 44 are pressed into a substantially U-shaped cross section, and welded regions 45 and 46 are formed at both ends thereof. On the other hand, the frame 43 is a plate-shaped body and is arranged between the frames 42 and 44, and can increase the strength of the frame member 41.

In the welding regions 45, 46 of the frame member 41, the three frames 42, 43, 44 are arranged in an overlapping manner. As described above with reference to FIGS. 3(C) and 3(D), the operator operates the operation unit 14 (see FIG. 1) of the spot welding gun 10 (see FIG. 1) to make a solid circle. As indicated by mark 47, the first electrode portion 11 (see FIG. 1) of the spot welding gun 10 pressurizes the surface 41A side of the frame member 41. On the other hand, similarly, on the back surface 41B side of the frame member 41, the second electrode portion 12 (see FIG. 1) of the spot welding gun 10 is also on the back surface 41B side of the frame member 41, as indicated by a dotted circle 48. Pressurize. The pressure areas indicated by the circles 47 and 48 are pressure points by the first and second electrode portions 11 and 12 at the time of continuous dot striking, but are separated by a certain distance in the extending direction of the frame member 41. The width W4 is arranged.

Then, the first nugget 35 (see FIG. 3D) is moved to the panel 44, which is directly below the circle 47, by passing an electric current in the above-mentioned pressurized state by the first and second electrode portions 11 and 12. The second nugget 36 (see FIG. 3D) is formed in the boundary region of 43 and its periphery, and in the boundary region of the panels 43 and 42 immediately above the circle 48 and its periphery. At this time, the gap width W5 between the adjacent nuggets 35 and 36 is set to, for example, about 20 mm, so that when the new nugget 35 is formed, the welding current is shunted to the nugget 36 at the already-struck point, and the new nugget 36 is divided. It is possible to prevent the situation where the nugget 35 cannot be formed.

As a result, the operator inserts the welding regions 45 and 46 of the frame member 41 once into the gap 18 (see FIG. 1) between the first and second electrode portions 11 and 12 of the spot welding gun 10 and then separates them from each other. It is possible to perform spot welding with continuous welding points while sliding the spot welding gun 10 in the extending direction of the frame member 41 while keeping the widths W4 and W5. The worker can improve the work efficiency by the welding work by repeating the above. Further, as compared with the case of the conventional spot welding at one spot, the number of nuggets 35 and 36 formed in the welding regions 45 and 46 can be increased and the welding strength can be increased.

In addition, in the present embodiment, the first and second electrode portions 11 and 12 are fixed via the fixing portion 13, and a worker performs an operation of scooping the operation portion 14 connected to the fixing portion 13. The case of forming the nugget with two hit points in one welding process has been described, but the present invention is not limited to this case. For example, the spot welding gun 10 may be provided at the tip of the arm of the welding robot, and the arm may perform a hollowing operation to form a nugget having two hit points in one welding process.

Further, the first and second electrode portions 11 and 12 are fixed to the fixing portion 13 in a state of having a constant separation width W1, and at least one of the first and second electrode portions 11 and 12 is Although the case where the actuator is not movable has been described, the present invention is not limited to this case. In the spot welding gun 10 of the welding device, for example, at least one of the first and second electrode portions 11 and 12 is movable in the vertical direction with respect to the front surface 21A or the rear surface 21B of the vehicle panel 21 by an actuator, and The axis of the first electrode portion 11 and the axis of the second electrode portion 12 are horizontally eccentric with respect to the front surface 21A or the rear surface 21B of the vehicle panel 21. Then, by driving the actuator in the vertical direction, a current is caused to flow in a state in which the front surface 21A and the back surface 21B of the vehicle panel 21 are pressed by the first and second electrode portions 11 and 12, so that one time It is also possible to form the nuggets at the two separated spots in the spot welding process. Besides, various modifications can be made without departing from the scope of the present invention.

10 Spot Welding Gun 11 First Electrode Part 12 Second Electrode Part 13 Fixed Part 14 Operating Part 14B Grip Part 15 Welding Cable 16 Cooling Pipe 18 Gap 19 Detachable Lever 21 Vehicle Panel 21C, 21D, 21E, 21F, 21G Panels 28, 29, 35, 36 Nuggets

Claims (9)

A spot welding gun comprising a first electrode portion and a second electrode portion which are arranged to face each other with a gap for inserting an object to be welded,
The first electrode portion pressurizes a first pressure area of one main surface of the object to be welded, and the second electrode portion is opposite to the one main surface of the object to be welded. The second pressure area of the other main surface of
An electric current is applied to the object to be welded in a state where the first pressure area and the second pressure area are shifted in the horizontal direction with respect to the one main surface of the object to be welded. A spot welding gun characterized by spot welding. A fixing portion that fixes the first electrode portion and the second electrode portion in a state in which the gap is maintained in the thickness direction,
An operating unit that operates with the first electrode unit and the second electrode unit while being connected to the fixing unit,
The first electrode part and the second electrode part are rotated with respect to the object to be welded through the fixing part by hollowing the operation part, and the first pressure is applied to the object to be welded. The spot welding gun according to claim 1, wherein an area and the second pressure area are generated. The operation section is rotatably connected to the fixed section in the horizontal direction so that the axis of the operation section substantially coincides with the center of the gap. Spot welding gun described. The axial center of the said 1st electrode part is eccentric with respect to the axial center of the said 2nd electrode part in the state before hollowing out the said operation part, The Claim 2 or Claim 3 characterized by the above-mentioned. Spot welding gun. The object to be welded is inserted into the gap between the first electrode portion and the second electrode portion of the spot welding gun, and the object to be welded is pressed by the first electrode portion and the second electrode portion. In the spot welding method, in which a current is passed in the state where the welding target object is welded,
A first pressure region where the first electrode portion presses one main surface of the object to be welded, and another second electrode portion of the other side opposite to the one main surface of the object to be welded. A second pressing region for pressing the main surface is shifted in the horizontal direction with respect to the one main surface of the object to be welded, and a current is applied to the object to be welded to perform one welding step 2. A spot welding method, characterized in that two nuggets separated from each other are formed. The spot welding gun is
A fixing portion that fixes the first electrode portion and the second electrode portion in a state in which the gap is maintained in the thickness direction,
An operating unit that operates with the first electrode unit and the second electrode unit while being connected to the fixing unit,
After inserting the object to be welded into the gap between the first electrode portion and the second electrode portion, the operation portion is gouged, and the first electrode portion and the second portion are inserted through the fixing portion. The electrode part of 1 is rotated with respect to the object to be welded to generate the first pressure region and the second pressure region in the object to be welded. Spot welding method. 7. The spot welding method according to claim 6, wherein the axial center of the first electrode portion is eccentric with respect to the axial center of the second electrode portion before the operation portion is hollowed out. .. The object to be welded is formed by stacking two plate materials,
The nuggets at the two hitting points are a contact area of the two plate materials below the first pressure area and the periphery thereof, and a contact area of the two plate materials above the second pressure area and the area thereof. The spot welding method according to any one of claims 5 to 7, wherein the spot welding method is formed separately from the periphery. The object to be welded is formed by stacking three plate materials,
The nugget at the two hit points includes a contact area between the plate material in contact with the first electrode portion below the first pressure area and the plate material located in the middle and the periphery thereof, and the second pressure area. 6. The contact area between the plate material in contact with the second electrode portion above the area and the plate material located in the middle and the periphery thereof are formed separately from each other. 7. The spot welding method according to any one of 7 above.

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