JP2014147947A - Seam welding device and seam welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seam welding device and seam welding method which prevent a crack of a workpiece and improve quality of seam welding.SOLUTION: A seam welding device includes: a welding device main body 20; a pair of roller electrodes 21 which are arranged on the welding device main body 20, and roll and sandwich a workpiece W with at least two or more base materials W1, W2 laminated; and a pair of slow-cooling heat sources 23 which are arranged at a back in a travelling direction A from the pair of roller electrodes 21 of the welding device main body 20 and heat the workpiece W. Thereby, a periphery of a nugget of the workpiece W is heated, and a difference between a temperature of the periphery of the nugget of the workpiece W and a temperature of the molten nugget is reduced to prevent rapid cooling of the nugget. Thus, rapid contraction in the periphery of the nugget of the workpiece W does not occur, and generation of a crack of the workpiece W can be prevented to improve quality of seam welding.

Description

  The present invention relates to a seam welding apparatus and a seam welding apparatus that perform resistance welding by sandwiching a workpiece in which at least two base materials are laminated by a pair of roller electrodes, and applying pressure and energization while rotating the pair of roller electrodes. Regarding the method.

  Conventionally, a technique for preventing cracks generated by seam welding is known (for example, see Patent Document 1). In Patent Document 1, an edge to be welded of a thin plate is preheated with a converged laser beam prior to the welding. This technology reduces the expected temperature gradient at a given welding speed, increases the maximum welding speed for workpieces, and provides a qualitatively sufficient weld at normal welding speeds for workpieces with low electrical resistance. It was possible.

JP-A-8-229689

Conventionally, when seam welding a workpiece in which at least two base materials are laminated, since the workpiece is small, seam welding is performed by moving the small workpiece to a pair of fixedly arranged roller electrodes. It was.
However, in recent years, in order to perform seam welding of a large workpiece, a welding apparatus main body provided with a pair of roller electrodes is mounted on a robot, and the welding apparatus main body is moved with respect to the workpiece by the robot to perform seam welding.

  In such seam welding, the nugget formed in the workpiece is rapidly cooled, and abrupt contraction occurs in the vicinity of the nugget of the workpiece, and the workpiece is cracked.

  The present invention is to solve the above-described problems, and an object of the present invention is to provide a seam welding apparatus and a seam welding method that prevent cracking of a workpiece and improve the quality of seam welding.

  (1) A welding device main body (for example, a welding device main body 20 described later) and a workpiece (for example, a base material W1 or W2 described later) provided on the welding device main body and laminated (for example, base materials W1 and W2 described later) A pair of roller electrodes (for example, a pair of roller electrodes 21 to be described later) that roll while sandwiching a workpiece W (to be described later), and a traveling direction (for example, a traveling direction to be described later) from the pair of roller electrodes of the welding apparatus main body. A) A seam welding apparatus provided with a first heat source (for example, a pair of heat sources for slow cooling described later) provided behind and heating the workpiece.

  According to the invention of (1), the workpiece is pressurized and energized by the pair of roller electrodes to form a melted nugget in the workpiece, and the workpiece through which the pair of roller electrodes has passed is heated by the first heat source. Thereby, the surface vicinity of the workpiece | work which is easy to cool is heated, and the melted nugget is cooled uniformly uniformly. Therefore, it is possible to prevent the workpiece from cracking and improve the quality of seam welding.

  (2) The apparatus further includes a second heat source (for example, a pair of preheating heat sources 22 described later) that is provided in front of the pair of roller electrodes of the welding apparatus body and that heats the workpiece. The seam welding device according to (1).

  According to the invention of (2), the work is heated by the second heat source before the work is pressurized and energized by the pair of roller electrodes. Thereby, before pressurizing and energizing the work with the pair of roller electrodes, the temperature of the work is raised and the electrical resistance of the work is raised. For this reason, when the workpiece is pressurized and energized with a pair of roller electrodes, the amount of heat generated at the contact portion where the current density of each base material of the workpiece increases, and the nugget is likely to grow.

  (3) A pair of roller electrodes (for example, a pair of roller electrodes to be described later) sandwich a work (for example, a later-described workpiece) in which at least two or more base materials (for example, a base material to be described later) are stacked, and the pair A seam welding method in which resistance welding is performed by applying pressure and energization while rotating the roller electrode of the pair of rollers, and the workpiece is behind the moving direction (for example, the moving direction described later) behind the pair of roller electrodes. And a slow cooling step (for example, Step S53 described later) that suppresses rapid cooling of the workpiece.

  According to the invention of (3), the same actions and effects as those of the invention of (1) can be achieved.

  (4) The method further includes a preheating step (for example, step S51 described later) for heating the workpiece and increasing the electrical resistance of the workpiece in front of the clamping position of the pair of roller electrodes. The seam welding method according to (3).

  According to the invention of (4), the same actions and effects as those of the invention of (2) can be achieved.

  ADVANTAGE OF THE INVENTION According to this invention, the seam welding apparatus and the seam welding method which prevent the crack of a workpiece | work and improve the quality of seam welding can be provided.

It is a schematic structure figure showing a seam welding device concerning an embodiment of the present invention. It is a perspective view which shows the welding apparatus main body which concerns on the said embodiment, and its periphery. It is a flowchart which shows the procedure which implements the seam welding using the seam welding apparatus which concerns on the said embodiment. It is a flowchart which shows the detailed procedure of the seam welding which concerns on the said embodiment. FIG. 5A is a diagram illustrating the principle of seam welding according to the embodiment, FIG. 5A is a diagram illustrating the principle in the embodiment, and FIG. 5B is a diagram illustrating the principle in the conventional case. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

First, with reference to FIG. 1 and FIG. 2, the structure of the seam welding apparatus 1 which concerns on this embodiment is demonstrated.
FIG. 1 is a schematic configuration diagram showing a seam welding apparatus 1. FIG. 2 is a perspective view showing the welding apparatus main body 20 and its periphery.

  The seam welding apparatus 1 includes a robot 10, a welding apparatus main body 20, and a control apparatus 30.

The robot 10 is an industrial robot having an articulated arm 11. A base 12 connected to the base end side of the arm 11 is installed on a floor surface of a factory or the like, and the arm is switched to an arbitrary posture by a program operation. 11 can be changed to an arbitrary state.
A base 12 of the robot 10 is rotatable, and the robot 10 has a rotation angle detection unit 13 that outputs a signal corresponding to the rotation angle of the base 12. The robot arm 11 has a six-axis joint, 10 has an axis angle detector 14 that outputs a signal corresponding to the axis angle of each joint of the arm 11.

The welding apparatus body 20 is attached to the tip of the arm 11 of the robot 10.
The welding apparatus body 20 has a pair of roller electrodes 21, a pair of preheating heat sources 22, and a pair of slow cooling heat sources 23.

  The pair of roller electrodes 21 includes a first roller electrode 21a disposed above and a second roller electrode 21b disposed below, and sandwiches a workpiece W in which at least two or more base materials W1 and W2 are stacked. Roll.

The pair of preheating heat sources 22 is disposed in front of the pair of roller electrodes 21 of the welding apparatus body 20 in the traveling direction A of the welding apparatus body 20. The pair of preheating heat sources 22 includes a first preheating heat source 22a disposed above and a second preheating heat source 22b disposed below, and the first preheating heat source 22a heats the upper surface Wa of the workpiece W. The second preheating heat source 22b heats the lower surface Wb of the workpiece W. The pair of preheating heat sources 22 uses, for example, heating elements that generate heat when energized, such as an induction heating device or a coil heater.
When the base materials W1 and W2 have different thicknesses, the pair of preheating heat sources 22 includes the first preheating heat source 22a and the second preheating heat source according to the thicknesses of the base materials W1 and W2. You may adjust the emitted-heat amount with 22b.

The pair of slow cooling heat sources 23 are arranged behind the pair of roller electrodes 21 of the welding apparatus body 20 in the traveling direction A of the welding apparatus body 20. The pair of slow cooling heat sources 23 includes a first slow cooling heat source 23 a disposed above and a second slow cooling heat source 23 b disposed below. The first slow cooling heat source 23 a is an upper surface of the workpiece W. Wa is heated, and the second heat source for slow cooling 23b heats the lower surface Wb of the workpiece W. As with the pair of preheating heat sources 22, for example, the pair of slow cooling heat sources 23 uses heating elements that generate heat when energized, such as an induction heating device or a coil heater.
When the base materials W1 and W2 have different thicknesses, the pair of slow cooling heat sources 23 and the first slow cooling heat source 23a and the second slow heat source 23a correspond to the thicknesses of the base materials W1 and W2. You may adjust the emitted-heat amount with the heat source 23b for cooling.

  As shown in FIG. 2, the welding apparatus main body 20 further includes a base 40, a first support unit 50, a second support unit 60, a moving mechanism 70, and a box 80.

The base 40 is held at the tip of the arm 11 of the robot 10 and supports the pair of preheating heat sources 22.
The first support unit 50 is configured to be movable with respect to the base 40 and supports the first roller electrode 21a.
The second support unit 60 is fixed to the base portion 40 and supports the second roller electrode 21b.
The moving mechanism 70 moves the first support unit 50.
The box 80 is connected to the base 40 and supports the pair of slow cooling heat sources 23.

  The base 40 extends in the vertical direction (X direction) during standby of the welding apparatus main body 20 and is formed into a rectangular parallelepiped shape, a holding plate 42 provided on an upper end portion 41 a of the supporting column 41, and a holding plate 42. A mounting portion 43 rotatably attached to the tip of the arm 11 of the robot 10 while being fixed to the upper surface, and a welding power source 44 provided on one side surface 41b of the support column 41 are provided.

  The holding plate 42 includes a flat portion 42a on which the mount portion 43 is disposed above, a bent portion 42b bent downward along a side surface 41c opposite to the side surface 41b provided with the welding power source 44 of the support column 41, and a bent portion 42b. A projecting portion 42c projecting outward from the lower end of the portion 42b.

  The support column 41 has the first support unit 50 movable below the projecting portion 42c on the side surface 41c of the projecting portion 42c of the holding plate 42 projecting, and the second support unit 60 further extends from the first support unit 50. Have fixed below. The first support unit 50 and the second support unit 60 are arranged in parallel in the X direction on the side surface 41 c of the support column 41.

  The welding power source 44 supplies the welding current to the pair of roller electrodes 21 and supplies the current to the pair of preheating heat sources 22 and the pair of slow cooling heat sources 23. Is output.

  The moving mechanism 70 includes a pair of guide rails 71 extending in the X direction below the bent portion 42b of the holding plate 42 on the side surface 41c opposite to the side surface 41b provided with the welding power source 44 of the support column 41, and the first support unit 50. And a cylinder 73 that is provided on the overhanging portion 42c and drives the rod portion 72 in the X direction.

  The first support unit 50 includes a housing 51 to which the rod portion 72 is fixed, a support shaft member 52 that is provided on the first roller electrode 21a and extends in the horizontal direction (Y direction) when the welding apparatus body 20 is on standby. A spindle rotating mechanism 53 that rotates the first roller electrode 21a in a direction (Z direction) orthogonal to the X direction and the Y direction, and an electrode rotation motor 54 that rotates the first roller electrode 21a are provided.

  The housing 51 has a pair of guide grooves 51 a that engage with the pair of guide rails 71. The first support unit 50 can move smoothly in the X direction in accordance with the drive in the X direction by the cylinder 73 by the pair of guide grooves 51 a of the housing 51 engaging the pair of guide rails 71.

  The support shaft member 52 connects a first shaft portion (not shown) fixed to the first roller electrode 21a, a second shaft portion connected to the electrode rotation motor 54, and the first shaft portion and the second shaft portion. And a universal joint. For example, a constant velocity joint can be used as the universal joint.

  The support shaft turning mechanism 53 includes a support shaft support member (not shown) located in the housing 51, a support shaft turning motor 53a that rotationally drives the support shaft support member, and the power of the support shaft turning motor 53a. A power transmission mechanism (not shown) for transmitting to the support member.

  The second support unit 60 has basically the same configuration as the first support unit 50. For this reason, the 2nd support unit 60 attaches | subjects the same referential mark to the structure which is common in the 1st support unit 50, and abbreviate | omits description.

The second support unit 60 is fixed to the support column 41 in a state where the first support unit 50 is inverted in the X direction. For this reason, the second support unit 60 does not have the guide groove 51 a of the housing 51.
The first support unit 50 and the second support unit 60 are arranged with the first roller electrode 21a and the second roller electrode 21b aligned in the X direction.

  The box 80 is connected to the overhanging portion 42 c of the holding plate 42 and the housing 51 of the second support unit 60.

  The control device 30 includes a robot control unit 31, a preheating heat source control unit 32, a welding power source control unit 33, a slow cooling heat source control unit 34, an electrode rotation motor control unit 35, and a spindle rotation motor control. A unit 36, a cylinder control unit 37, and a storage unit 38.

The robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11.
The preheating heat source control unit 32 controls the pair of preheating heat sources 22 by adjusting the amount of current supplied to the pair of preheating heat sources 22.
The welding power source control unit 33 controls the welding power source 44.
The slow cooling heat source control unit 34 controls the pair of slow cooling heat sources 23 by adjusting the amount of current supplied to the pair of slow cooling heat sources 23.
The electrode rotation motor control unit 35 controls the electrode rotation motor 54.
The support shaft rotation motor controller 36 controls the support shaft rotation motor 53a.
The cylinder control unit 37 controls the cylinder 73.

  The storage unit 38 stores teaching data and welding control data of the robot 10. The welding control data includes movement speed data regarding the movement speed of the welding apparatus main body 20 fixed to the tip of the arm 11 of the robot 10 and rotation speed data regarding the rotation speed of the pair of roller electrodes 21.

Next, a procedure for performing seam welding using the seam welding apparatus 1 will be described with reference to FIGS.
FIG. 3 is a flowchart showing a procedure for performing seam welding using the seam welding apparatus 1. FIG. 4 is a flowchart showing a detailed procedure when performing seam welding.

  As shown in FIG. 3, first, the workpiece W is set at a predetermined position (step S1). As the workpiece W, for example, a large workpiece in which at least two base materials W1 and W2 are stacked, such as a body of an automobile, can be used. The base materials W1 and W2 in the workpiece W are individually formed by press molding or the like, and the size of the gap between the base materials W1 and W2 is not constant.

  Subsequently, the control device 30 creates teaching data for the robot 10 (step S <b> 2), and stores the created teaching data in the storage unit 38.

Next, the robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11 to move the welding apparatus main body 20 to the welding point (step S3). Specifically, the robot control unit 31 moves the welding apparatus main body 20 so that the welding point of the welding target portion of the workpiece W is positioned between the pair of roller electrodes 21.
The welding apparatus main body 20 moved to the welding point brings the lower second roller electrode 21b into contact with the lower surface Wb of the workpiece W.

  Next, the cylinder controller 37 controls the cylinder 73, moves the first support unit 50 to the second support unit 60 side below, and sandwiches and pressurizes the workpiece W with the pair of roller electrodes 21 (step S4). ).

  Subsequently, the control device 30 performs seam welding on the welding point (step S5). Specifically, the control device 30 performs seam welding by performing processing of steps S50 to S54 described later shown in FIG.

  That is, the electrode rotation motor control unit 35 drives the electrode rotation motor 54 to rotate the pair of roller electrodes 21, thereby energizing the pair of roller electrodes 21 with the pair of roller electrodes 21 in the welding point. (Step S50).

  Subsequently, the preheating heat source control unit 32 energizes the pair of preheating heat sources 22 to generate heat, and heats the upper surface Wa and the lower surface Wb of the workpiece W with the pair of preheating heat sources 22 (step S51). The temperature of the workpiece W heated by the pair of preheating heat sources 22 is about 500 ° C., for example.

  Subsequently, the welding power source control unit 33 supplies a welding current to the pair of roller electrodes 21 (step S52). Thereby, the nugget is grown in the workpiece W at the position where the pair of roller electrodes 21 are sandwiched, and resistance welding is performed to obtain a constant welding strength.

  Subsequently, the slow cooling heat source control unit 34 energizes the pair of slow cooling heat sources 23 to generate heat, and heats the upper surface Wa and the lower surface Wb of the workpiece W with the pair of slow cooling heat sources 23 (step S53). . The temperature of the workpiece W heated by the pair of slow cooling heat sources 23 is about 700 ° C., for example.

  And the control apparatus 30 determines whether the seam welding was complete | finished about all the welding points (step S54). If it is determined that the seam welding has not been completed (step S54 → NO), the process proceeds to step S50, and the processes after step S50 are performed.

  On the other hand, when it is determined that seam welding has been completed (step S54 → YES), the cylinder control unit 37 controls the cylinder 73 and moves the first support unit 50 away from the second support unit 60 upward. The pressure of the workpiece W by the pair of roller electrodes 21 is released (step S6).

Next, the robot control unit 31 controls the robot 10 to change the posture of the robot 10 and the arm 11 to move the welding apparatus main body 20 to the standby position (step S7).
Thus, the procedure for performing seam welding is completed.

  According to the seam welding apparatus 1 according to the above-described embodiment, the following effects can be obtained.

  (1) The workpiece W is pressurized and energized by the pair of roller electrodes 21 to form a melted nugget in the workpiece W, and the workpiece W having passed the pair of roller electrodes 21 by the pair of slow cooling heat sources 23 is used. Heat. Thereby, the surface vicinity of the workpiece | work which is easy to cool is heated, and the melted nugget is cooled uniformly uniformly. Therefore, generation | occurrence | production of the crack of the workpiece | work W can be prevented and the quality of seam welding can be improved.

FIG. 5 is a diagram illustrating the principle of seam welding according to the present embodiment, FIG. 5A is a diagram illustrating the principle of the present embodiment, and FIG. 5B is a diagram of the conventional case. It is a figure explaining a principle.
The principle in this embodiment in which the workpiece W is pressurized and energized by the pair of roller electrodes 21 and the workpiece W that has passed the pair of roller electrodes 21 by the pair of slow cooling heat sources 23 will be described.
When the workpiece W is pressurized and energized by the pair of roller electrodes 21, the electrical resistance of the portion between the base materials W1, W2 and the small contact area between the pair of roller electrodes 21 and the workpiece W increases. For this reason, when the pair of roller electrodes 21 is energized, the current density of the portion having the high electric resistance is increased, the portion having the high electric resistance is easily heated and melted, and the nugget N is easily formed. That is, the nugget N includes a contact portion between the base materials W1 and W2 sandwiched between the pair of roller electrodes 21, the first roller electrode 21a and the upper surface Wa of the work W, and the second roller electrode 21b and the lower surface Wb of the work W. It is easy to grow into a shape with a corner Na extending in the four directions of the contact boundary in the cross section like a nugget N in the left figure (see (a) left figure). .
In the conventional case, the nugget N grown in the above shape is easier to cool the upper surface Wa and the lower surface Wb of the workpiece W than the inside of the workpiece W, so that the molten metal at the corner Na portion close to the upper surface Wa and the lower surface Wb. The molten metal at the corner Na portion is pulled to the non-melting portion side as shown by the arrow in the figure (see the middle figure in (b)). As a result, cracks S are likely to occur near the corner Na (see (b) right figure).
On the other hand, in the present embodiment, the upper surface Wa and the lower surface Wb, which are easily cooled, are heated by heating the workpiece W through which the pair of roller electrodes 21 have passed with the pair of slow cooling heat sources 23 against the conventional phenomenon as described above. Maintaining the high temperature, the vicinity of the corner Na of the nugget N is uniformly and slowly cooled with the central portion of the nugget N, and the molten metal at the corner Na becomes difficult to be pulled to the non-molten portion as shown by the arrows in FIG. (See the middle figure). As a result, the seam welded workpiece W is not cracked (see the right figure).

  (2) Before pressurizing and energizing the work W with the pair of roller electrodes 21, the work W is heated with the pair of slow cooling heat sources 23. Thereby, before pressurizing and energizing the work W with the pair of roller electrodes 21, the temperature of the work W is raised, and the electrical resistance of the work W is raised. Therefore, when the workpiece W is pressurized and energized by the pair of roller electrodes 21, the amount of heat generated at the contact portion where the current density of each of the base materials W1, W2 of the workpiece W increases, and the nugget N is likely to grow. .

Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the scope of the present invention.
In the present embodiment, the pair of preheating heat sources 22 and the pair of slow cooling heat sources 23 are fixedly arranged. However, for example, the first preheating heat source 22a and the first slow cooling heat source 23a may be mounted on the first support unit 50 and moved up and down similarly to the first roller electrode 21a.

DESCRIPTION OF SYMBOLS 1 ... Seam welding apparatus 20 ... Welding apparatus main body 21 ... A pair of roller electrode 22 ... A pair of heat source for preheating 23 ... A pair of heat source for slow cooling 30 ... Control device W ... Workpiece | work W1, W2 ... Base material A ... Advancing direction

Claims (4)

A welding apparatus body;
A pair of roller electrodes provided in the welding apparatus main body and sandwiching and rolling a workpiece in which at least two or more base materials are stacked; and
A seam welding apparatus, comprising: a first heat source that is provided behind the pair of roller electrodes of the welding apparatus body in a traveling direction and heats the workpiece.   The seam welding apparatus according to claim 1, further comprising: a second heat source that is provided in front of the pair of roller electrodes of the welding apparatus main body and that heats the workpiece. A seam welding method for sandwiching a work in which at least two base materials are laminated with a pair of roller electrodes, and performing resistance welding by applying pressure and energizing while rotating the pair of roller electrodes,
A seam welding method comprising: a slow cooling step of heating the workpiece and suppressing rapid cooling of the workpiece behind the clamping position of the pair of roller electrodes.   4. The seam welding method according to claim 3, further comprising a preheating step of heating the workpiece in front of the sandwiching position of the pair of roller electrodes in a traveling direction to increase an electrical resistance of the workpiece. .

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