JP2005052878A - Seam welding method and seam welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seam welding method corresponding to the reduction in the width of a flange and the speed-up of a seam welding rate, and to provide seam welding equipment for performing the method. <P>SOLUTION: In the method, using equipment X1 provided with: an operational part 10 having a means 13 for controlling the rotational displacement of a work W having a flange part F, and displacing the work W; a pair of electrode rings 22 performing welding as the flange part F is held; and a means 23 for detecting the deviation D between a weld planned line and the front edge of a weld locus in the flange part F, the flange part F is subjected to seam welding. The work W is displaced by the operational part 10 so that the pair of electrode rings 22 perform the welding along the flange part F as the rotational displacement of the work W is mainly controlled and correctingly controlled via the means 13. In the correction control, fine control angles are selected in accordance with the deviation D detected by the means 23 from the group of angles including at least two inner correction angles, at least one outer correction angle and 0 degrees, and the rotational displacement of the work W is finely controlled in accordance with the fine control angles based on the main control angles regulated by the main control. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for performing seam welding using an apparatus including a pair of electrode wheels as welding electrodes, and the seam welding apparatus.

Seam welding technology may be used in the production of containers that require airtightness or liquid tightness. For example, in the manufacture of fuel tanks for automobiles and motorcycles, tank halves individually formed by sheet metal pressing are joined by seam welding and processed into a single body. Such seam welding technology is described in, for example, Patent Document 1 and Patent Document 2 below.
JP-A-7-241684 JP 9-314346 A

  FIG. 9 shows a seam welding apparatus X2 which is an example of a conventional apparatus for performing seam welding. The seam welding device X2 is for seam welding a flange portion F of a fuel tank W of an automobile, for example, and includes a work operation unit 60 and a welder 70. The work operation unit 60 includes an articulated robot 61, a work holding unit 62, and a rotation unit 63. The welding machine 70 includes a main body 71, a pair of electrode wheels 72, and a sensor system 73.

  The articulated robot 61 of the work operation unit 60 has its robot arm tip connected to a work holding unit 62 via a rotating means 63, and the fuel tank W held by the work holding unit 62 is three-dimensionally arranged. This is for translational displacement. In such an articulated robot 61, each joint axis is controlled by a predetermined control unit (not shown) included in the work operation unit 60, and a predetermined program programmed in advance according to a planned welding line at the flange unit F is provided. The fuel tank W can be translated and displaced according to teaching.

  The work holding unit 62 is for holding the fuel tank W, and includes a frame 62a, a jig 62b, a clamp 62c, and a confirmation plate 62d. The jig 62b is prepared according to the shape of the fuel tank W so as to receive the upper part of the fuel tank W, and is fixed to one end side of the frame 62a. The clamp 62c is for pressing and supporting the fuel tank W from below, and is provided on the other end side of the frame 62a so as to be adjustable in height and rotatable. The confirmation plate 62d is a part that functions in correction control as will be described later, and is fixed on the jig 62b. The peripheral side surface 62d 'of the confirmation plate 62d is parallel to the planned welding line assumed in the flange portion F of the fuel tank W.

  The rotating means 63 has a portion capable of rotational displacement having a rotational axis extending in the vertical direction, and a rotational displacement having a rotational axis extending in the vertical direction with respect to the fuel tank W held by the work holding portion 62. It is for granting. One end of the rotating means 63 is connected to the tip of the articulated robot 61, and the other end is connected to one end side of the frame 62 a in the work holding unit 62. When the rotating unit 63 is driven to rotate, the fuel tank W held by the work holding unit 62 is rotationally displaced relative to the tip of the articulated robot 61. The rotation angle and drive timing in the rotation drive of the rotation means 63 are each controlled by a predetermined control unit (not shown) provided in the work operation unit 60. The rotating means 63 is configured to be able to be driven to rotate in accordance with predetermined teaching programmed in advance.

  The pair of electrode wheels 72 of the welding machine 70 is for welding the flange portion F over its linear region and corner region while sandwiching the flange portion F of the fuel tank W, and the respective rotation axes are parallel. And are arranged so that the peripheral edges thereof face each other. Both rotation axes of the electrode wheel pair 72 are separated in the vertical direction. The electrode wheel pair 72 is provided so as to be able to move close to and away from each other. Such an electrode wheel pair 72 is configured such that the rotation speed and energization current can be controlled by a predetermined control unit (not shown) provided in the main body 71.

  The sensor system 73 is for substantially tracking the welding trajectory in the flange portion F so as to be used for correction control to be described later with respect to the rotational displacement of the fuel tank W, and includes an arm 73a fixed to the main body 71, A reference member 73b attached to the tip of the arm 73a, a distance measuring sensor 73c attached to the middle of the arm 73a, and a calculation unit (not shown) provided in the main body 71 are provided.

  The reference member 73 b is disposed at a height position facing the confirmation plate 62 d of the work holding unit 62 in a virtual plane including both the rotation axes of the electrode wheel pair 72. The distance measuring sensor 73c is configured to measure a separation distance between the reference member 73b and the confirmation plate 62d. The calculation unit of the sensor system 73 calculates the deviation length of the front end of the welding locus from the planned welding line based on the separation distance measured by the distance measuring sensor 73c and the predetermined reference distance.

  The reference distance is a separation distance between the reference member 73b and the confirmation plate 62d when the electrode wheel pair 72 is positioned on the planned welding line. The difference between the separation distance measured by the distance measuring sensor 73c and the reference distance corresponds to the departure length of the front end of the welding locus from the planned welding line. When the front end of the welding locus deviates from the planned welding line to the outside of the tank, the separation distance measured by the distance measuring sensor 73c is longer than the reference distance. The deviation length at this time is obtained as a positive value, for example. On the other hand, when the front end of the welding locus deviates from the planned welding line to the inside of the tank, the measurement separation distance is shorter than the reference distance. The deviation length at this time is obtained as a negative value, for example.

  When performing a welding operation on the flange portion F of the fuel tank W using the seam welding apparatus X2 having such a configuration, first, the tank halves are temporarily fixed by spot welding to the flange portion F at several places. The formed fuel tank W is sandwiched between the jig 62 b and the clamp 62 c and attached to the work holding unit 62. In the state where the fuel tank W is attached in this way, the planned welding line in the flange portion F of the fuel tank W and the peripheral wall surface 62d 'of the confirmation plate 62d are in a parallel relationship. Next, the articulated robot 61 is driven to displace the work holding portion 62, and thus the fuel tank W, and feed the welding start location in the flange portion F between the electrode wheel pair 72. Next, the workpiece operation unit 60 and the welding machine 70 are driven, and the flange portion F is seam welded while the electrode wheel pair 72 is relatively moved over the circumference of the flange portion F.

  At the time of seam welding work on the flange portion F, the electrode wheel pair 72 rotates at a predetermined rotation speed while holding the flange portion F with an appropriate pressing force, and the welding current between the electrode wheel pair 72 is determined at a predetermined timing. Is energized. The work operation unit 60 is driven in accordance with teaching programmed in advance according to the planned welding line at the flange F. In the welding operation for the straight region of the flange portion F, the articulated robot 61 continues to translate and displace the fuel tank W in the virtual plane so that the straight region is linearly fed between the electrode wheel pair 72, and the rotating means. The work operation unit 60 is taught so as to keep the standby state without driving 63. Further, in the welding operation for the corner region of the flange portion F, the translational displacement by the articulated robot 61 and the rotational displacement by the rotation means 63 are cooperatively fueled so as to send the corner region between the electrode wheel pairs 72 in a curved manner. The work operation unit 60 is taught so as to continue being applied to the tank W.

  On the other hand, during the seam welding operation for the flange portion F, the distance measuring sensor 73c in the welding machine 70 constantly measures the distance between the reference member 73b and the confirmation plate 62d. Based on the distance obtained by this measurement and the above-described reference distance, the calculation unit (not shown) of the sensor system 73 calculates the deviation length of the front end of the welding locus from the planned welding line. As described above, the fact that the measurement distance obtained by the distance measuring sensor 73c is longer than the reference distance means that the front end of the welding locus has deviated from the planned welding line to the outside of the tank, and the degree of deviation is determined by the calculation unit. For example, it is calculated as a positive deviation length. On the other hand, the fact that the measurement distance obtained by the distance measuring sensor 73c is shorter than the reference distance means that the front end of the welding locus has deviated from the planned welding line toward the inside of the tank. Calculated as the departure length.

  When the deviation length is not less than a positive threshold (for example, 0.8 mm or more), a predetermined fine control signal is transmitted from the welding machine 70 to the rotating means 63 accordingly. Based on the signal, the rotational displacement of the rotating means 63 is finely controlled in the negative direction from the reference angle defined by the above-described teaching control (for example, -2.0 degrees). When fine control is already performed in the negative direction based on the previous fine control signal, the angle after the fine correction is maintained for the rotational displacement of the rotating means 63. Further, the reference angle is specifically a rotation angle designated for the rotation means 63 in teaching control. By such fine control on the rotational displacement of the rotating means 63, the rotational displacement of the fuel tank W is corrected in the negative direction. The negative direction is a direction in which the relative traveling direction of the electrode wheel pair 72 on the flange portion F is swung inward of the fuel tank W.

  When the deviation length is equal to or less than the negative threshold value (for example, −0.8 mm or less), a predetermined fine control signal is transmitted from the welding machine 70 to the rotating means 63 in response thereto. Based on the signal, the rotational displacement of the rotating means 63 is finely controlled in the positive direction from the reference angle (for example, +1.4 degrees). When the fine correction has already been made in the positive direction based on the previous control signal, the angle after the fine correction is maintained for the rotational displacement of the rotating means 63. By such fine control of the rotational displacement of the rotating means 63, the rotational displacement of the fuel tank W is corrected in the positive direction. The positive direction is a direction in which the relative traveling direction of the electrode wheel pair 72 on the flange portion F is swung outward from the fuel tank W.

  When the deviation length is between both positive and negative threshold values (for example, larger than −0.8 mm and smaller than 0.8 mm), a predetermined fine control signal is transmitted from the welding machine 70 to the rotating means 63 accordingly. Is done. Based on the signal, the rotational displacement of the rotating means 63 is set to a reference angle (0 degree). When fine control is performed in the positive or negative direction based on the previous fine control signal, the rotational displacement of the rotating means 63 is changed to the reference angle, and when the reference angle is already set based on the previous fine control signal. As for the rotational displacement of the rotating means 63, the reference angle is maintained. When the deviation length is between both positive and negative thresholds, only the rotational displacement (reference angle) based on teaching control is included in the rotational displacement of the fuel tank W by such fine control of the rotational angle of the rotating means 63. It will be reflected.

  Since the thickness and surface state of the flange F to be welded are not microscopically uniform, or because the various states of the flange F are not necessarily the same between fuel tanks, only by preprogrammed teaching control. When the drive control of the workpiece operation unit 60 is performed, the welding locus tends to deviate from the planned welding line, and as a result, the electrode wheel pair 72 may fall off the flange portion F. Therefore, the seam welding apparatus X2 employs the above-described technique for finely correcting and controlling the rotating means 63 based on a fine control signal independent of teaching control when controlling the rotational displacement of the fuel tank W. It is.

  However, in the seam welding method performed using the conventional seam welding apparatus X2, in the fine control of the rotational displacement of the workpiece (fuel tank W), the reference angle (the rotation angle specified in the rotating means 63 in the teaching control) is used. ) Is three possible rotation angles including the reference angle. Specifically, the three angles refer to the relative traveling direction of the electrode wheel pair 72 on the flange portion F when the front end of the welding locus deviates from the planned welding line to the outside of the tank more than a predetermined amount. An inner correction angle (for example, -2.0 degrees) for swinging inward of the tank W and an electrode on the flange portion F when the front end of the welding locus deviates from the planned welding line to the inside of the tank beyond a predetermined level. When the outside correction angle (for example, +1.4 degrees) for swinging the relative traveling direction of the wheel pair 72 to the outside of the fuel tank W and the deviation of the welding track front end from the planned welding line are within a predetermined range. The angle for not correcting the reference angle based on the pre-programmed teaching control.

  Since the angle assigned for the correction control by the rotating means 63 is so small, the conventional seam welding method by the seam welding apparatus X2 is sufficiently sufficient for various deviation modes of the front end of the welding locus from the planned welding line. There is a problem that it cannot be handled. Therefore, in the conventional seam welding method using the seam welding apparatus X2, there is a case where good seam welding cannot be performed on a predetermined workpiece. As the width dimension of the flange portion of the workpiece is shortened and the seam welding speed is increased, the above-described problems become more prominent, and the seam welding method using the seam welding apparatus X2 becomes impractical.

  The present invention has been conceived under such circumstances, and a seam welding method suitable for coping with shortening of the flange width and coping with high speed of the seam welding, and the method are performed. It is an object of the present invention to provide a seam welding apparatus.

  According to a first aspect of the present invention, a seam welding method is provided. In this method, a workpiece operation unit for displacing a workpiece having a flange portion, a pair of electrode wheels having mutually parallel rotation axes for sandwiching the flange portion, and welding scheduled in the flange portion A seam welding apparatus is used, which includes detection means for detecting the deviation length of the front end of the welding locus from the line. The work operation part of this apparatus includes a rotation imparting means for imparting to the work a rotational displacement having a rotational axis extending in the direction of separation of both rotational axes of the electrode wheel pair. In this method, the workpiece is displaced by the workpiece operating unit so that the electrode wheel pair performs welding along the flange portion while performing main control and correction control of the rotation displacement of the workpiece via the rotation applying means. In main control, the main control angle of rotational displacement is defined. In the correction control, from the angle group consisting of at least two internal correction angles, at least one external correction angle, and 0 degrees associated with the deviation length, the fineness is determined according to the deviation length detected by the detection means. A control angle is selected, and the rotational displacement is finely controlled according to the fine control angle with the main control angle as a reference. In the present invention, main control of workpiece rotation displacement by the rotation applying means is performed based on teaching provided to the rotation applying means. The inner correction angle is a correction angle for swinging the relative traveling direction of the electrode wheel pair on the flange portion inward of the workpiece. The outside correction angle is a correction angle for swinging the relative traveling direction of the electrode wheel pair on the flange portion to the outside of the workpiece. Moreover, 0 degree is an angle for preventing the workpiece from being rotationally displaced from the reference angle.

  In the seam welding method according to the first aspect, in the correction control of the rotational displacement of the work (for example, the fuel tank) via the rotation applying means during the seam welding operation, a reference main control angle (for main control by teaching) The rotation angle that can be taken by the work with respect to the rotation giving means, and thus the rotation angle given to the work) is two or more internal correction angles, one or more external correction angles, and 0 degrees (reference) A total of four or more including the angle). In a state where the front end of the welding locus deviates from the planned welding line to the outside of the workpiece, the swing angle width allowed when the relative traveling direction of the electrode wheel pair on the flange portion is moved inward of the workpiece is In a state where the front end of the locus deviates from the planned welding line to the inside of the work, it is larger than the swing angle width allowed when the relative traveling direction of the electrode wheel pair is swung outward on the flange. . When the front end of the welding locus deviates from the planned welding line to the inside of the workpiece, if the relative movement direction of the electrode ring pair is moved outward on the flange on the flange, the electrode ring pair will move to the raised portion of the workpiece. It is because it is easy to contact. For the internal correction in which a larger swing angle is allowed, it is easier to set many practical correction angles than for the external correction. However, in the method according to the first aspect of the present invention, such a correction in seam welding is performed. A plurality of angles are set as possible rotation angles of the rotation applying means or the workpiece in the correction control while utilizing the technical features. Therefore, according to the method according to the first aspect of the present invention, the fine control angle can be selected from a larger number of angles than in the prior art, and the correction control of the rotational displacement of the workpiece can be performed more precisely. The seam welding method according to the present invention capable of precise correction control can flexibly cope with the deviation of the front end of the welding locus from the planned welding line. Accordingly, it can cope with shortening of the flange width and the seam welding speed (electrode). It is suitable for responding to the increase in the rotation speed of the wheel pair.

  In a preferred embodiment of the first aspect, the inner correction angle includes a first angle and a second angle having an absolute value smaller than the first angle, and the outer correction angle is a first angle smaller in absolute value than the first angle. Includes 3 angles. Such a configuration is suitable for practically and efficiently setting a larger number of internal correction angles than external correction angles.

  Another seam welding method is provided according to the second aspect of the present invention. Workpiece operating part for displacing a work piece having a flange part, a pair of electrode wheels having mutually parallel rotation axes for welding while sandwiching the flange part, and welding from a planned welding line in the flange part A seam welding apparatus is used that includes detection means for detecting the deviation length of the front end of the locus. The work operation part of this apparatus includes a rotation imparting means for imparting to the work a rotational displacement having a rotational axis extending in the direction of separation of both rotational axes of the electrode wheel pair. In this method, the workpiece is displaced by the workpiece operating unit so that the electrode wheel pair performs welding along the flange portion while performing main control and correction control of the rotation displacement of the workpiece via the rotation applying means. In main control, the main control angle of rotational displacement is defined. In the correction control, after selecting an active angle group from a plurality of angle groups each including a plurality of angles associated with the departure length, a fine adjustment is made from the active angle group according to the departure length detected by the detecting means. A control angle is selected, and the rotational displacement is finely controlled according to the fine control angle with the main control angle as a reference. In the present invention, each angle group that can be selected as an active angle group is based on a set of angles set according to various conditions (material, thickness, width dimension, detour property, etc.) about the flange part to be welded. Become.

  In the seam welding method according to the second aspect, after an active angle group is selected from a plurality of angle groups prepared according to differences in conditions for the flange part to be welded, the active angle group An appropriate fine control angle is selected from the inside, and the workpiece rotational displacement during the seam welding operation is corrected and controlled according to the fine control angle. Such a method according to the second aspect of the present invention is suitable for flexibly responding to changes in various conditions of the flange portion with respect to the deviation of the front end of the welding locus from the planned welding line. Such a seam welding method is suitable for dealing with the shortening of the flange width and the seam welding speed.

  In a preferred embodiment of the second aspect, the plurality of angle groups includes a first angle group and a second angle group, and the first angle group includes a first internal correction angle as a lower limit angle and a first angle as an upper limit angle. 1 outside correction angle, at least one correction angle between them, and 0 degree, and the second angle group includes the second inside correction angle as the lower limit angle having a larger absolute value than the first inside correction angle, the first outside It consists of a second outer correction angle as an upper limit angle having an absolute value larger than the correction angle, at least one correction angle between them, and 0 degree. It is preferable to appropriately select an active angle group from at least these two types of angle groups in order to flexibly cope with changes in various conditions of the flange portion with respect to deviation of the front end of the welding locus from the planned welding line. is there.

  In another preferred embodiment of the second aspect, the plurality of angle groups includes a first angle group, a second angle group, and a third angle group, and the first angle group is a first inner angle as a lower limit angle. The correction angle, the first outer correction angle as the upper limit angle, at least one correction angle between them, and 0 degrees, and the second angle group is the first lower limit angle having a larger absolute value than the first inner correction angle. 2 internal correction angles, a second external correction angle as an upper limit angle having a larger absolute value than the first external correction angle, at least one correction angle between them, and 0 degrees, and the third angle group includes the first internal correction angle A third internal correction angle having an absolute value greater than or equal to the correction angle and less than the second internal correction angle, a third external correction angle having an absolute value greater than or equal to the first external correction angle and less than the second external correction angle, and 0 degrees. . It is preferable to appropriately select an active angle group from these three types of angle group in order to flexibly cope with changes in various conditions of the flange portion with respect to the deviation of the front end of the welding locus from the planned welding line.

  According to the 3rd side surface of this invention, the apparatus for the seam welding of the said flange part of the workpiece | work which has a flange part is provided. The apparatus includes a workpiece operating unit for displacing the workpiece, a pair of electrode wheels having mutually parallel rotation axes for welding while sandwiching the flange portion, and welding from a planned welding line at the flange portion. Detecting means for detecting the deviation length of the front end of the locus. The work operation unit includes rotation imparting means for imparting to the work a rotational displacement having a rotation axis extending in the direction in which both rotation axes of the electrode wheel pair are separated from each other. In addition, the apparatus includes a main control for defining a main control angle of rotational displacement, an angle group including at least two internal correction angles associated with the deviation length, at least one external correction angle, and 0 degrees. A correction control for selecting a fine control angle according to the deviation length detected by the detection means, and finely controlling the rotational displacement according to the fine control angle with reference to the main control angle; It is comprised so that it can perform about the rotational displacement of a workpiece | work via.

  According to the seam welding apparatus according to the third aspect, the method according to the first aspect of the present invention can be executed. Therefore, according to the apparatus which concerns on a 3rd side surface, in the use process, the same profit as the above-mentioned regarding the 1st side surface can be enjoyed.

  According to a fourth aspect of the present invention, there is provided another apparatus for seam welding a flange portion of a workpiece having a flange portion. The apparatus includes a workpiece operating unit for displacing the workpiece, a pair of electrode wheels having mutually parallel rotation axes for welding while sandwiching the flange portion, and welding from a planned welding line at the flange portion. Detecting means for detecting the deviation length of the front end of the locus. The work operation unit includes rotation imparting means for imparting to the work a rotational displacement having a rotation axis extending in the direction in which both rotation axes of the electrode wheel pair are separated from each other. In addition, the apparatus detects a main control for defining a main control angle of rotational displacement and an active angle group selected from a plurality of angle groups each including a plurality of angles associated with a deviation length. The fine control angle is selected from the active angle group according to the deviation length detected by the means, and the correction control for finely controlling the rotational displacement according to the fine control angle based on the main control angle is given rotation. It is comprised so that it can perform about the rotational displacement of a workpiece | work via a means.

  According to the seam welding apparatus according to the fourth aspect, the method according to the second aspect of the present invention can be executed. Therefore, according to the apparatus which concerns on a 4th side surface, in the use process, the same profit as the above-mentioned regarding the 2nd side surface can be enjoyed.

  In a preferred embodiment of the fourth aspect, the plurality of angle groups include a first angle group and a second angle group, and the first angle group includes a first internal correction angle as a lower limit angle and a first angle as an upper limit angle. 1 outside correction angle, at least one correction angle between them, and 0 degree, and the second angle group includes the second inside correction angle as the lower limit angle having a larger absolute value than the first inside correction angle, the first outside It consists of a second outer correction angle as an upper limit angle having an absolute value larger than the correction angle, at least one correction angle between them, and 0 degree. It is preferable to appropriately select an active angle group from these three types of angle group in order to flexibly cope with changes in various conditions of the flange portion with respect to the deviation of the front end of the welding locus from the planned welding line.

  1 and 2 show a seam welding apparatus X1 according to the present invention. FIG. 1 is a partially cutaway side view of the seam welding apparatus X1, and FIG. 2 is a partially enlarged plan view of the seam welding apparatus X1.

  The seam welding apparatus X1 is for seam welding the flange portion F of the workpiece W, and includes a workpiece operation unit 10 and a welding machine 20. The work operation unit 10 includes an articulated robot 11, a work holding unit 12, a rotating unit 13, and a slide plate 14. The welding machine 20 includes a main body 21, a pair of electrode wheels 22, a sensor system 23 for correction control, and a photosensor 24 for corner detection. The workpiece W is, for example, a fuel tank of an automobile or a motorcycle, and in FIG. As shown in FIG. 2, the flange portion F of the workpiece W has a straight region Fa and a corner region Fb. Further, as shown by a two-dot chain line in FIG. 2, a desired welding locus is assumed as a planned welding line L in the flange portion F.

  The multi-joint robot 11 of the work operation unit 10 has a plurality of joints, and the operation of each joint is independently controlled by a predetermined control unit (not shown) provided in the work operation unit 10. Further, the articulated robot 11 is configured to operate in accordance with predetermined teaching that is programmed in advance and issued from the control unit. The tip of the articulated robot 11 is mechanically connected to the work holding unit 12 via the rotating means 13 and the slide plate 14.

  The workpiece holding unit 12 is for holding the workpiece W, and includes a frame 12a, a jig 12b, a clamp 12c, and a confirmation plate 12d. The jig 12b is prepared according to the shape of the workpiece W so as to receive the upper portion of the workpiece W, and is fixed to one end side of the frame 12a. The clamp 12c is for pressing and supporting the work W from below, and is provided on the other end side of the frame 12a so as to be adjustable in height and rotatable. The confirmation plate 12d is a part that functions in correction control as will be described later, and is fixed on the jig 12b. The peripheral side surface 12d 'of the confirmation plate 12d is parallel to the planned welding line L assumed in the flange portion F of the workpiece W, as clearly shown in FIG. Further, LS dogs 12e are disposed in the vicinity of each corner region on the confirmation plate 12d. Each LS dog 12e is a part that functions in corner detection, as will be described later.

  The rotating means 13 has a portion having a rotational axis extending in the vertical direction and capable of rotational displacement, and the rotational means having a rotational axis extending in the vertical direction with respect to the workpiece W held by the workpiece holding unit 12. It is for granting. Such a rotation means 13 is comprised by the servomotor, for example. One end of the rotating means 13 is connected to the tip of the articulated robot 11, and the other end is connected to the slide plate 14. One end side of the frame 12 a in the work holding unit 12 is fixed to the slide plate 14. In such a configuration, when the rotating means 13 is driven to rotate, the work holding portion 12 fixed to the slide plate 14 or the work W held by the rotating means 13 rotates relative to the tip of the articulated robot 11. Displace. The rotational axis of the rotational displacement extends in the vertical direction as described above. The rotation angle and drive timing in the rotation drive of the rotation means 13 are each controlled by a predetermined control unit (not shown) provided in the work operation unit 10. The rotating means 13 is configured to be able to be driven to rotate in accordance with predetermined teaching programmed in advance.

  The slide plate 14 is for allowing the translational displacement of the workpiece W held by the workpiece holding portion 12 with a low resistance in the horizontal direction. As shown well in FIG. , 14b, 14c and two sets of linear motion guides 14d, 14e. In the present embodiment, two parallel linear motion guides 14d are fixed to the plate 14b side of the plate 14a, and the plate 14b has a low resistance against the plate 14a along the linear motion guides 14d. Slide displacement is possible. On the other hand, in this embodiment, two parallel linear motion guides 14e are fixed to the plate 14c side of the plate 14b, and the plate 14c has a low resistance to the plate 14b along the linear motion guides 14e. The slide can be displaced by force. Further, the linear motion guide 14d and the linear motion guide 14e are orthogonal to each other. The workpiece W held by the workpiece holder 12 mechanically coupled to the articulated robot 11 via the slide plate 14 is within a predetermined range even when the articulated robot 11 is stationary. Translational displacement is possible in the horizontal direction with low resistance.

  The pair of electrode wheels 22 of the welding machine 20 are for welding the flange portion F over the linear region Fa and the corner region Fb while sandwiching the flange portion F of the workpiece W. The electrode wheel pair 22 is disposed so that the respective rotation axes A are parallel and the peripheral edges thereof are opposed to each other as can be understood with reference to FIGS. 1 and 4 together. Both rotation axes A of the electrode wheel pair 22 are separated in the vertical direction Y. The electrode wheel pair 22 is provided so as to be able to move close to and away from each other. Such an electrode wheel pair 22 is configured such that the rotation speed and the energization current can be controlled by a predetermined control unit (not shown) provided in the main body 21.

  The sensor system 23 is for substantially tracking a welding locus (indicated by a thick line in FIG. 2) in the flange portion F so as to be used for correction control to be described later for the rotational displacement of the workpiece W, and is fixed to the main body 21. Arm 23a, a reference member 23b attached to the distal end of the arm 23a, a distance measuring sensor 23c attached to the middle of the arm 23a, and a calculation unit (see FIG. Not shown). From the viewpoint of simplifying the figure, in FIG. 2, the depiction of a part of the main body 21 and the arm 23 a is omitted, and the reference member 23 b is shown in a state separated from the main body 21.

The reference member 23b is opposed to the confirmation plate 12d of the work holding unit 12 in a virtual plane Q including both the rotational axes A of the electrode wheel pair 22, as can be understood with reference to FIGS. Is disposed at a height position. The distance measuring sensor 23c is configured to measure a separation distance between the reference member 23b and the confirmation plate 12d. The calculation unit of the sensor system 23 is based on the separation distance measured by the distance measuring sensor 23c and the predetermined reference distance _R0, and the deviation length of the welding locus front end P (shown in FIG. 2) from the planned welding line L. The length D is calculated.

The reference distance R ₀ is a separation distance between the reference member 23b and the confirmation plate 12d when the electrode wheel pair 22 is positioned on the planned welding line L. The difference between the separation distance measured by the distance measuring sensor 23c and the reference distance corresponds to the deviation length D of the welding track front end P from the planned welding line L. When the front end P of the welding locus deviates from the planned welding line L to the outside of the tank, as shown in FIG. 5A, the separation distance R between the reference member 23b and the confirmation plate 12d is based on the reference distance _R0 . long. In this case, the deviation length D is calculated as a positive value by the distance measuring sensor 23c, for example. On the other hand, when the front end P of the welding locus deviates from the planned welding line L toward the inside of the tank, the measurement separation distance R is shorter than the reference distance R ₀ as shown in FIG. The deviation length D at this time is calculated by, for example, a negative value by the distance measuring sensor 23c.

  The photosensor 24 is for detecting the passage of the LS dog 12e provided on the confirmation plate 12d, and is attached to the main body 21. From the viewpoint of simplifying the figure, in FIG. 2, the depiction of a part of the main body 21 is omitted, and the photosensor 24 is shown in a state separated from the main body 21. The arrangement position of the photosensor 24 is higher than the arrangement position of the reference member 23b and can be understood with reference to FIGS. 1, 2, and 4 together, and seam welding by the electrode wheel pair 22 is performed. In the direction B, it is behind the position where the reference member 23b is disposed or the position of the rotation axis A of the electrode wheel pair 22. On the other hand, the LS dog 12e detected by the photosensor 24 is detected on the confirmation plate 12d, specifically, a predetermined period before the electrode wheel pair 22 enters the corner area Fb from the straight line area Fa in the flange portion F. 24 is disposed at a position detected by 24.

  When performing a welding operation on the flange portion F of the workpiece W using the seam welding apparatus X1 having such a configuration, first, the workpiece W is sandwiched between the jig 12b and the clamp 12c to hold the workpiece. Attach to part 12. In the workpiece W, the tank halves are temporarily fixed in advance by spot welding at several locations on the flange portion F. In such a state of attachment, the planned welding line L in the flange portion F of the workpiece W and the peripheral wall surface 12d 'of the confirmation plate 12d are in a parallel relationship. Next, the articulated robot 11 is driven to displace the workpiece holding portion 12, and thus the workpiece W, and feed a predetermined welding start location in the flange portion F between the electrode wheel pairs 22. Next, the workpiece operation unit 10 and the welding machine 20 are driven to seam weld the flange portion F while relatively moving the electrode wheel pair 22 over the circumference of the flange portion F.

  At the time of seam welding work on the flange portion F, the electrode wheel pair 22 rotates at a predetermined rotation speed while sandwiching the flange portion F with an appropriate pressing force, and a welding current between the electrode wheel pair 22 at a predetermined timing. Is energized. At the same time, the articulated robot 11 and the rotating means 13 in the work operation unit 10 are cooperatively driven according to teaching programmed in advance in accordance with the planned welding line L at the flange F. Specifically, the articulated robot 11 translates the workpiece W according to teaching programmed in advance according to the planned welding line L at the flange portion F. Specifically, the rotating means 13 rotates and displaces the workpiece W as the main control according to teaching programmed in advance according to the planned welding line L at the flange portion F.

  For example, in the welding operation for the straight line area Fa of the flange portion F, the workpiece W is continuously translated and rotated via the articulated robot 11 so as to linearly feed the straight line area Fa between the electrode wheel pairs 22 and rotate. The work operation unit 10 is taught so that a constant rotational displacement angle can be continuously specified for the means 13 in the main control.

  The photosensor 24 detects the passage of the LS dog 12e before a predetermined period before entering the corner area Fb from the straight line area Fa of the flange portion F. When a predetermined period elapses after the detection, the operation for the corner area of the work operation unit 10 is started.

  In the welding operation of the flange portion F to the corner region Fb, the translational displacement achieved via the articulated robot 11 and the rotating means 13 are used to send the corner region Fb between the electrode wheel pairs 22 in a curved manner. The work operation unit 10 is taught so that the rotational displacement based on the main control achieved in this way is continuously applied to the work W. In the rotational displacement main control via the rotating means 13 by teaching programmed in advance according to the shape of the flange portion F, the displacement angle with respect to a predetermined rotational reference position (0 degree in the main control) is the main control angle. Are specified for the rotational displacement of the rotating means 13 itself, and hence the rotational displacement of the workpiece W accompanying this. The workpiece W can be rotationally displaced according to the designated main control angle. The rotational displacement of the workpiece W during the seam welding operation corresponds to a change in the relative traveling direction of the electrode wheel pair 22 with respect to the workpiece W or the flange portion F.

  The rotational displacement of the workpiece W is mainly controlled as described above via the rotating means 13 and is corrected and controlled via the rotating means 13. FIG. 6 shows a flowchart relating to the correction control.

In the correction control, first, in step S1, the distance measuring sensor 23c of the welding machine 20 measures the distance between the reference member 23b and the confirmation plate 12d. This measurement is performed constantly or intermittently at a predetermined timing. Next, in step S2, based on the distance obtained by this measurement and the above-mentioned reference distance R ₀ , the calculation unit (not shown) of the sensor system 23 deviates from the welding locus front end P from the planned welding line L. The length D is calculated. Next, in step S3, a predetermined control unit (not shown) refers to a group of angles prepared in advance based on the obtained deviation length D, and a fine control angle is selected from the angle group. Is selected.

  FIG. 7 is a table listing an angle group G1, which is an example of an angle group referred to in step S3. A total of 13 angles included in the angle group G1 are associated with the departure length D and assigned in advance. Specifically, an outer correction angle (positive correction angle) having a larger absolute value is assigned to a negative deviation length D having a larger absolute value, and a positive deviation length having a larger absolute value. An inner correction angle (negative correction angle) having a larger absolute value is assigned to the length D. For example, +2.1 degrees is assigned as the upper limit angle for deviation length D ≦ −1.2 mm, and +1.05 degrees is assigned for deviation length D ≦ −0.6 mm. For 0.4 mm ≦ deviation length D <0.6 mm, −0.7 degrees is assigned, and for 1.2 mm ≦ deviation length D, −2.8 degrees is assigned as the lower limit angle. ing. In the angle group G1, the absolute value of the lower limit angle is larger than that of the upper limit angle. In addition to these correction angles, 0 degree is assigned to −0.2 mm <deviation length D <0.2 mm. In step S3, one angle corresponding to the latest deviation length D obtained is selected as the fine control angle from such an angle group G1.

  In the correction control, next, in step S4, the rotational displacement of the workpiece W is finely controlled in accordance with the selected fine control angle. Specifically, the main control angle defined by the main control is set as a reference angle (0 degree in correction control), and the rotation of the workpiece W is controlled so as to reach an angular position different from the reference angle by a fine control angle. At this time, when the workpiece W is already positioned at the position in the previous correction control, the workpiece W is not rotationally displaced. As a result of such fine control, the relative traveling direction of the electrode wheel pair 22 with respect to the workpiece W or the flange portion F changes. In the seam welding method of the present invention, the correction control (steps S1 to S4) as described above is performed on the rotational displacement of the workpiece W via the rotating means 13.

  For example, when the electrode wheel pair 22 or the welding track front end P greatly deviates from the planned welding line L to the outside of the workpiece W and the deviation length D obtained in step S2 is 1.5 mm, in step S3, -2.8 degrees is selected as the control angle. In step S4, the predetermined main control angle defined by the main control is set as a reference angle (0 degree in the correction control), and the workpiece W is rotated so as to reach an angular position different from the reference angle by −2.8 degrees. The displacement is controlled. As a result, the relative traveling direction of the electrode wheel pair 22 with respect to the flange portion F changes relatively greatly and is swung toward the inside of the workpiece W.

  For example, when the front end P of the welding locus deviates from the welding planned line L to the outside of the workpiece W relatively small and the deviation length D obtained in step S2 is 0.3 mm, the fine control angle is determined in step S3. -0.35 degrees is selected. In step S4, the predetermined main control angle defined by the main control is set as a reference angle (0 degree in correction control), and the workpiece W is rotated so as to reach an angular position different from the reference angle by −0.35 degrees. The displacement is controlled. As a result, the relative traveling direction of the electrode wheel pair 22 with respect to the flange portion F changes relatively small and is swung toward the inside of the workpiece W.

  For example, when the degree of deviation of the welding track front end P from the planned welding line L is extremely small and the absolute value of the deviation length D obtained in step S2 is less than 0.2 mm, in step S3, the fine control angle is 0 degrees is selected. In step S4, a predetermined main control angle defined by the main control is set as a reference angle (0 degree in the correction control), and the rotational displacement of the workpiece W is controlled so as to maintain or reach the reference angle. The As a result, the relative traveling direction of the electrode wheel pair 22 with respect to the flange portion F is not changed or hardly changed in many cases in the very vicinity of the planned welding line L.

  For example, when the welding track front end P deviates from the planned welding line L inward of the workpiece W and the deviation length D obtained in step S2 is −0.7 mm, in step S3, the fine control angle is set to +1. 05 degrees is selected. In step S4, a predetermined main control angle defined by the main control is set as a reference angle (0 degree in correction control), and the rotational displacement of the workpiece W is reached so as to reach an angular position that is different from the reference angle by +1.05 degrees. Is controlled. As a result, the relative traveling direction of the electrode wheel pair 22 with respect to the flange portion F changes and is swung toward the outside of the workpiece W.

  In the seam welding method according to the present invention, the workpiece W is moved by the rotational displacement control through the rotating means 13 including the main control and the correction control as described above, and the translational displacement control through the articulated robot 11. While being displaced, the welding work by the electrode wheel pair 22 is performed. Thereby, the flange part F of the workpiece | work W is continuously welded over the whole linear area | region Fa and the corner area | region Fb.

  According to the seam welding method according to the present invention, in the correction control of the rotational displacement of the workpiece W via the rotating means 13 during the seam welding operation, the rotation angle that the workpiece W can take with respect to the reference main control angle is A large number. In a state where the front end P of the welding locus deviates from the planned welding line L to the outside of the workpiece, the swing angle width allowed when the electrode wheel pair 22 is swung inward of the workpiece W on the flange portion F is the welding width. In a state where the trajectory front end P deviates from the planned welding line L to the inside of the workpiece W, the swing angle width allowed when the electrode wheel pair 22 is swung outward from the workpiece W on the flange portion F, large. For internal correction in which a larger swing angle is allowed, it is easier to set many practical correction angles than for external correction. In the present invention, while utilizing such technical features in seam welding, a plurality of angles are set as possible rotation angles of the rotating means 13 or the workpiece W in the correction control. Therefore, according to the present invention, the fine control angle can be selected from a larger number of angles than before, and the correction control of the rotational displacement of the workpiece W can be performed more precisely. The seam welding method according to the present invention capable of precise correction control can flexibly cope with the deviation of the front end P of the welding locus from the planned welding line L. Accordingly, it is possible to cope with the shortening of the flange width and the seam welding speed. It is suitable for dealing with higher speeds.

  In the present invention, the angle groups G2 and G3 shown in FIG. 8 are prepared together with the angle group G1, and the angle group referred to in step S3 is set in advance as an active angle group among the angle groups G1 to G3. You may choose.

  A total of nine angles included in the angle group G2 are associated with the departure length D and assigned in advance. For example, an upper limit angle of +1.4 degrees is assigned to the deviation length D ≦ −0.8 mm, and +0.7 degrees is assigned to the deviation length D ≦ −0.4 mm. For 0.4 mm ≦ deviation length D <0.6 mm, −0.7 degrees is assigned, and for 0.8 mm ≦ deviation length D, −2.0 degrees is assigned as the lower limit angle. Yes. In addition to these correction angles, 0 degree is assigned to −0.2 mm <deviation length D <0.2 mm. In the angle group G2, the absolute value of the lower limit angle is larger than that of the upper limit angle.

  In the angle group G2, the upper limit angle for correction control has an absolute value smaller than that of the angle group G1, and the lower limit angle has an absolute value smaller than that of the angle group G1. When the planned welding line L is close to the raised portion of the workpiece W, the angle group G2 in which the relative maximum deflection angle of the electrode wheel pair 22 with respect to the flange portion F in the correction control is smaller than the angle group G1. This is suitable for avoiding contact of the electrode wheel pair 22 with the raised portion. Accordingly, for example, in the flange portion F of the single workpiece W, the region where the distance between the planned welding line L and the workpiece bulge portion is relatively short, or the entire welding portion L and the workpiece bulge over the entire flange portion F. For the workpiece W having a short distance from the part, it is preferable to select the angle group G2 as the active angle group.

  The angle group G3 is made up of three angles assigned in advance in association with the departure length D. For the deviation length D ≦ −0.5 mm, +1.4 degrees is assigned, and for the deviation length D−−2.0 degrees, −2.0 degrees is assigned. In addition to these correction angles, 0 degree is assigned to -0.5 mm <deviation length D <0.5 mm.

  In the angle group G3, the same internal correction angle (+1.4 degrees) as the upper limit angle in the angle group G1 is assigned to the deviation length D having a smaller absolute value than in the angle group G1. Similarly, the same outer correction angle (−2.0 degrees) as the lower limit angle in the angle group G1 is assigned to the deviation length D having a smaller absolute value than in the angle group G1. In the case where the distance from the workpiece raised portion of the planned welding line L is secured, or in the corner region Fb, the relative maximum deflection angle of the electrode wheel pair 22 with respect to the flange portion F in the correction control tends not to be strictly limited. is there. Therefore, for example, in a region where the distance between the welding line L and the workpiece bulge portion is relatively long in the flange portion F of the single workpiece W, the distance between the welding line L and the workpiece bulge portion over the entire flange portion F. If the workpiece W is long or the corner region Fb of the flange portion F can be sharply corrected, it may be preferable to select the angle group G3 as the active angle group.

It is a partially cutaway side view of the seam welding apparatus according to the present invention. FIG. 2 is a partially enlarged plan view of the seam welding apparatus shown in FIG. 1. It is an enlarged view of a slide plate. It is a side view of the welding machine in the seam welding apparatus shown in FIG. The separation mode of the reference member and the confirmation plate when the front end of the welding locus deviates from the planned welding line is shown. 3 shows a flowchart of correction control in the present invention. An example of an angle group for correction control is shown. Represents another group of angles. An example of the conventional seam welding apparatus is represented.

Explanation of symbols

X1, X2 Seam welding equipment F Flange Fa Linear area Fb Corner area 10,60 Work operation part 11,61 Articulated robot 12,62 Work holding part 12a, 62a Frame 12b, 62b Jig 12c, 62c Clamp 12d, 62d Confirmation plate 12e LS dog 13,63 Rotating means 14 Slide plate 20,70 Welding machine 22,72 Electrode wheel 23,73 Sensor system 24 Photo sensor

Claims (8)

From a work operation part for displacing a work having a flange part, a pair of electrode wheels having mutually parallel rotation axes for sandwiching the flange part, and a planned welding line in the flange part Detecting means for detecting the deviation length of the front end of the welding trajectory of the workpiece, and the work operating section detects rotational displacement having a rotational axis extending in a separating direction of both rotational axes of the electrode wheel pair. A method for seam welding the flange portion using a seam welding device, including rotation imparting means for imparting to
While the main displacement and correction control of the rotational displacement of the workpiece via the rotation imparting means, the workpiece operating portion is displaced by the workpiece operating unit so that the electrode wheel pair performs welding along the flange portion,
In the main control, a main control angle of the rotational displacement is defined,
In the correction control, the deviation length detected by the detection means is selected from an angle group consisting of at least two internal correction angles, at least one external correction angle, and 0 degrees, which are associated with the deviation length. A seam welding method in which a fine control angle is selected according to the main control angle, and the rotational displacement is finely controlled according to the fine control angle.   The inner correction angle includes a first angle and a second angle having an absolute value smaller than the first angle, and the outer correction angle includes a third angle having an absolute value smaller than the first angle. The seam welding method according to 1. From a work operation part for displacing a work having a flange part, a pair of electrode wheels having mutually parallel rotation axes for sandwiching the flange part, and a planned welding line in the flange part Detecting means for detecting the deviation length of the front end of the welding trajectory of the workpiece, and the work operating section detects rotational displacement having a rotational axis extending in a separating direction of both rotational axes of the electrode wheel pair. A method for seam welding the flange portion using a seam welding device, including rotation imparting means for imparting to
While the main displacement and correction control of the rotational displacement of the workpiece via the rotation imparting means, the workpiece operating portion is displaced by the workpiece operating unit so that the electrode wheel pair performs welding along the flange portion,
In the main control, a main control angle of the rotational displacement is defined,
In the correction control, after selecting an active angle group from a plurality of angle groups each including a plurality of angles associated with the departure length, the active control is performed according to the departure length detected by the detection unit. A seam welding method in which a fine control angle is selected from an angle group, and the rotational displacement is finely controlled according to the fine control angle with the main control angle as a reference. The plurality of angle groups includes a first angle group and a second angle group,
The first angle group includes a first inner correction angle as a lower limit angle, a first outer correction angle as an upper limit angle, at least one correction angle therebetween, and 0 degrees,
The second angle group includes a second inner correction angle as a lower limit angle having a larger absolute value than the first inner correction angle, a second outer correction angle as an upper limit angle having a larger absolute value than the first outer correction angle, and these The seam welding method according to claim 3, comprising at least one correction angle between 0 and 0 degrees. The plurality of angle groups includes a first angle group, a second angle group, and a third angle group,
The first angle group includes a first inner correction angle as a lower limit angle, a first outer correction angle as an upper limit angle, at least one correction angle therebetween, and 0 degrees,
The second angle group includes a second inner correction angle as a lower limit angle having a larger absolute value than the first inner correction angle, a second outer correction angle as an upper limit angle having a larger absolute value than the first outer correction angle, and these At least one correction angle between and 0 degrees,
The third angle group includes a third internal correction angle having an absolute value that is greater than or equal to the first internal correction angle and less than the second internal correction angle, and an absolute value that is greater than or equal to the first external correction angle and less than the second external correction angle. The seam welding method according to claim 3, comprising a third outer correction angle having a value and 0 degree. An apparatus for seam welding the flange portion in a workpiece having a flange portion,
A workpiece operating unit for displacing the workpiece;
A pair of electrode rings having rotation axes parallel to each other for welding while sandwiching the flange portion;
Detecting means for detecting the deviation length of the front end of the welding locus from the planned welding line in the flange portion,
The work operation unit includes rotation imparting means for imparting to the work a rotational displacement having a rotation axis extending in a separating direction of both rotation axes of the electrode wheel pair,
Main control for defining a main control angle of the rotational displacement;
A fine control angle is selected according to the deviation length detected by the detecting means from an angle group consisting of at least two inner correction angles, at least one outer correction angle, and 0 degrees associated with the deviation length. And correction control for finely controlling the rotational displacement according to the fine control angle with the main control angle as a reference,
A seam welding apparatus configured to be able to execute the rotational displacement of the workpiece via the rotation applying means. An apparatus for seam welding the flange portion in a workpiece having a flange portion,
A workpiece operating unit for displacing the workpiece;
A pair of electrode rings having rotation axes parallel to each other for welding while sandwiching the flange portion;
Detecting means for detecting the deviation length of the front end of the welding locus from the planned welding line in the flange portion,
The work operation unit includes rotation imparting means for imparting to the work a rotational displacement having a rotation axis extending in a separating direction of both rotation axes of the electrode wheel pair,
Main control for defining a main control angle of the rotational displacement;
After selecting an active angle group from a plurality of angle groups each including a plurality of angles associated with the departure length, a fine control angle from the active angle group according to the departure length detected by the detection means Correction control for finely controlling the rotational displacement in accordance with the fine control angle with the main control angle as a reference,
A seam welding apparatus configured to be able to execute the rotational displacement of the workpiece via the rotation applying means. The plurality of angle groups includes a first angle group and a second angle group,
The first angle group includes a first inner correction angle as a lower limit angle, a first outer correction angle as an upper limit angle, at least one correction angle therebetween, and 0 degrees,
The second angle group includes a second inner correction angle as a lower limit angle having a larger absolute value than the first inner correction angle, a second outer correction angle as an upper limit angle having a larger absolute value than the first outer correction angle, and these The seam welding device according to claim 7, comprising at least one correction angle between and 0 degrees.

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