JP2006181620A - Multi-spot welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-spot welding equipment capable of controlling the optimum current for each welding point, securing the high welding quality by preventing occurrence of sparks or current leak, and shortening the welding time by realizing higher speed. <P>SOLUTION: In the multi-spot welding equipment capable of performing the multi-point welding of metallic plates W1, W2 by running the welding current between electrodes 1, 2 from a power supply 3 while holding and pressing the metallic plates (works to be welded) W1, W2 by a plurality of upper electrodes 1 and a plurality of lower electrodes 2 of the same number as the upper electrodes, there is provided a changing switch device (a current changing means) 4, in which the plurality of upper electrodes 1 and the plurality of lower electrodes 2 are constituted independently of each other, each upper electrode 1 and each lower electrode are connected to the power supply 3 independently of each other, and conduction of a pair of the upper electrode 1 and the lower electrode 2 facing each other is simultaneously turned on/off to switch the supply of the current to each welding point of the metallic plates W1, W2, and the welding current successively runs to the plurality of welding points of the metallic plates W1, W2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-spot welding apparatus that performs multi-point welding of workpieces.

  Spot welding (spot welding) is known as a typical resistance welding. In this spot welding, a welding current is passed between both electrodes while the workpiece is sandwiched and pressed between the upper electrode and the lower electrode. This is a welding method in which the workpiece is spot-welded.

  By the way, a multi-spot welding apparatus for performing multi-point welding has been put into practical use. However, since the conventional apparatus employs a method in which a plurality of upper electrodes at each welding point are energized at the same time, the current flowing through each welding point. As a result, there is a problem that not only the welding points can be welded uniformly, but also a large current needs to flow at a time, so that a large-capacity welding transformer is required and the apparatus becomes large.

  Therefore, for example, Patent Documents 1 and 2 propose a multi-spot welding apparatus that employs a method in which a plurality of welding points are not welded at a time but are welded one by one in order.

  In the invention described in Patent Document 1, continuous energization is performed with all the upper and lower electrodes sandwiching and pressing an object to be welded, and the energization to the welding point is sequentially performed by rotating the roller contact of the power supply unit (distributor). A method of switching is adopted.

  Further, in the invention described in Patent Document 2, switching elements provided for each upper electrode are turned on in turn at predetermined time intervals by the control means, and the upper switching elements connected to the ON state during this ON period are connected. A method is adopted in which the welded portion of the work piece corresponding to the electrode is welded for each electrode.

JP 62-028086 A JP 2000-351081 A

  However, in the invention described in Patent Document 1, since the continuous current system is adopted, the optimum current control for each welding point cannot be performed, and the current to the welding point is switched by the rotation of the roller contact. When the roller contact is slow, there is a problem that a reactive current due to a diversion occurs when the roller contact straddles the electrode, and conversely, when the rotational speed is high, a spark is generated from the contact portion.

  Further, in the inventions described in Patent Documents 1 and 2, since the lower electrode is common and these are not individually connected to the power source, current leaks to the adjacent lower electrode and the welding conditions are not stabilized. There was a problem of poor welding efficiency.

  The present invention has been made in view of the above problems, and the intended process is that it is possible to perform optimum current control for each welding point, and it is possible to prevent the occurrence of sparks and current leakage and to ensure high welding quality. A further object is to provide a multi-spot welding apparatus capable of realizing high speed and shortening welding time.

  In order to achieve the above object, the invention described in claim 1 is directed to a workpiece by passing a welding current from a power source to both electrodes while sandwiching and pressing the workpiece with a plurality of upper electrodes and the same number of lower electrodes. In the multi-spot welding apparatus for multi-point welding, a plurality of the upper electrode and the lower electrode are each independently configured, and each upper electrode and the lower electrode are independently connected to the power source, and a pair of opposed upper portions Provide current switching means to switch the supply of current to each welding point of the work piece by turning ON / OFF the continuity between the electrode and the lower electrode at the same time, and let the welding current flow sequentially to the plurality of welding points of the work piece It is characterized by.

  According to a second aspect of the present invention, in the first aspect of the present invention, by providing a plurality of blocks each including the plurality of upper electrodes and the plurality of lower electrodes, and sandwiching and pressurizing an object to be welded for each block, A plurality of workpieces are welded in order.

  According to a third aspect of the present invention, in the first aspect of the present invention, the current switching unit includes the same number of switching contacts as the number of the upper electrode and the lower electrode, and a cam mechanism that sequentially contacts and separates the switching contacts. It is characterized by comprising.

  According to the present invention, a plurality of upper electrodes and lower electrodes are each configured independently, and each upper electrode and lower electrode are independently connected to a power source, and a pair of upper electrodes corresponding to each welding point are connected by current switching means. The conduction between the electrode and the lower electrode is simultaneously turned ON / OFF to switch the current supply to each welding point of the work piece, and each welding point is sequentially spot welded by flowing the welding current sequentially to a plurality of welding points. As a result, no current leaks to the adjacent lower electrode, no spark is generated, the welding conditions are stable, and a large current can be passed as the welding current, enabling high speed and high welding. The efficiency can be ensured and the welding time can be shortened.

  Further, since the intermittent control method is adopted as the energization control method instead of the continuous control method, optimum current control suitable for each welding point is possible, and high welding quality can be ensured.

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

  FIG. 1 is a block diagram showing a basic configuration of a multi-spot welding apparatus according to the present invention. The illustrated multi-spot welding apparatus includes a plurality (six in this embodiment) of upper electrodes (welding guns) 1. The same number (six in this embodiment) of lower electrodes 2 are provided below each upper electrode 1 so as to face each other. The upper electrode 1 and the lower electrode 2 are configured independently of each other and are independently connected to the power source 3 so that the continuity between the pair of the upper electrode 1 and the lower electrode 2 facing each other is a changeover switch as a current switching means. It is turned ON / OFF simultaneously and sequentially by the device 4.

  Further, a timer (T / C) 5 and a transformer (TR) 6 are provided between the power source 3 and the changeover switch device 4, and a control means 7 is connected to the timer 5. Are connected to a servo motor (M) 8 as a drive source of the changeover switch device 4 and a speed reducer (R / G) 9 that decelerates the rotation of the servo motor 8 at a predetermined ratio.

  By the way, the changeover switch device 4 includes upper and lower changeover contacts 10 and 11 and the changeover contacts 10 and 11 at the same time as the number of the upper electrodes 1 and the lower electrodes 2 (six sets in the present embodiment). In addition, a cam mechanism 13 that makes contact and separation in order is provided. In the present embodiment, six pairs of the upper electrode 1 and the lower electrode 2 are arranged in parallel so as to be opposed to each other in the vertical direction, and numbers “1” to “6” are assigned in order from the end. In FIG. 1, only the switching contacts 10 (10a, 10b), 11 (11a, 11b) and the cam mechanism 13 corresponding to the set of the upper electrode 1 and the lower electrode 2 of the number “6” are illustrated.

  Here, details of the configuration of the changeover switch device 4 in the present embodiment will be described with reference to FIGS. 2 is a side view of the selector switch device, and FIG. 3 is a cross-sectional view taken along line AA of FIG.

  The changeover switch device 4 is provided with a frame 14 having a rectangular frame shape. A top plate 15 that forms the upper side of the frame 14 has a total of six sets of support columns 16 (see FIG. 3). ), The fixed plate 17 is supported by being suspended horizontally. A total of six sets of the switching contacts 10 (10a, 10b), which form a pair of left and right pairs, are attached to the lower surface of the fixed plate 17 via electrical insulating materials 18 (see FIG. 3). The six sets of switching contacts 10 (10a, 10b) are connected to conductive wires 19 (19a, 19b) extending from the transformer (TR +, TR-) 6, respectively, as shown in FIGS. ing.

  Further, vertical rods 20 are respectively disposed between the left and right switching contacts 10 (10a, 10b) of each set, and a total of six rods 20 move vertically through the fixed plate 17. Supported as possible. That is, as shown in FIG. 3, each rod 20 is inserted and supported by the fixed plate 17 through a bush 21 so as to be movable up and down, and a cam follower 22 is rotatably supported at the upper end thereof and is supported at the lower end. A movable plate 23 is attached. Each rod 20 is constantly urged upward by a spring 24 that is compressed between its upper end and the fixed plate 17.

  By the way, each of the six movable plates 23 attached to the lower ends of the rods 20 is guided and fixed by a plurality of vertical guide bars 25 inserted through the fixed plate 17 so as to be movable up and down as shown in FIG. The plate 17 is supported so as to be movable up and down, and on each upper surface thereof, a pair of left and right switching contacts 11 (11a, 11a, 10a, 10b) arranged oppositely below the switching contacts 10 (10a, 10b). 11b) is attached via an electrical insulating material 26 (see FIG. 3). Incidentally, 11 (11a, 11b) is connected to each of these six sets of switching contacts, as shown in FIGS. 1 and 3, respectively, with conducting wires 27 (27a, 27b) extending from the upper electrode 1 and the lower electrode 2, respectively. Yes.

  On the other hand, a total of six bearings 28 are attached to the lower surface of the top plate 15 of the frame 14 at appropriate intervals in the length direction (see FIG. 2), and these bearings 28 constitute the cam mechanism 13. The cam shaft 29 is supported horizontally and rotatably. An output shaft 9 a of the speed reducer 9 is connected to one end portion of the cam shaft 29 extending out of the frame 14 via a coupling 30 as shown in FIG. Although not shown, the input shaft of the reduction gear 9 is connected to the output shaft (motor shaft) of the servo motor 8 (see FIG. 1).

  By the way, cams 31 are formed at a total of six locations corresponding to the positions where the rods 20 of the cam shafts 29 are arranged, and as shown in FIG. 3, the cam surfaces formed on the outer peripheral surfaces of the cams 31. A cutout flat portion 31a is formed in a part of the flat plate 31a. Here, the phases of the flat portions 31a formed on the cam surfaces of the six cams 31 are shifted by 60 ° in order from the ends.

  Thus, the upper end portion of the rod 20 urged upward by the spring 24 is in contact with the cam surface of each cam 31 via the cam follower 22, and the cam follower 22 is a flat portion of the cam surface of the cam 31. In a state where the rod 20 and the movable plate 23 are in contact with the circumferential surface other than 31a, the rod 20 and the movable plate 23 are pushed down against the urging force of the spring 24, and the switching contact 11 (11a, 11b), as shown in FIG. 2, is separated by a predetermined distance from the upper switching contact 10 (10a, 10b) opposite thereto, and no power is supplied from the power source 3 to the upper electrode 1 and the lower electrode 2. (OFF state).

  When the cam 31 rotates and the cam follower 22 comes into contact with the flat portion 31 a of the cam surface as shown in FIG. 3, the rod 20 and the movable plate 23 are pushed up by the urging force of the spring 24 and attached to the movable plate 23. The switching contact 11 (11a, 11b) comes into contact with the upper switching contact 10 (10a, 10b), and energization is possible, and energization from the power source 3 to the upper electrode 1 and the lower electrode 2 is possible (ON state). . The conduction path at this time is: transformer (TR +) 6 → conductor 19a → switch contact 10a → switch contact 11a → upper electrode 1 → metal plate W1 → metal plate W2 → lower electrode 2 → conductor 27b → switch contact 11b → switch. The contact 10b → the conductive wire 19b → the transformer (TR−) 6 is obtained.

  Next, multi-point welding of an object to be welded by the multi-spot welding apparatus having the above configuration will be described with reference to FIGS. 4 and 5 are timing charts showing energization control.

  As shown in FIG. 1, when two metal plates (workpieces) W1 and W2 are to be welded as multi-point welding (in this embodiment, six-point welding), these two metal plates W1 and W2 are welded. W2 are stacked one above the other and sandwiched between the six upper electrodes 1 and the lower electrode 2, and the two metal plates W1 and W2 are pressed by the upper electrode 1 and the lower electrode 2 by a pressing mechanism (not shown).

  As shown in FIG. 5, when the start signal is turned on by the timer 5 based on the command from the control means 7, the upper electrode 1 and the lower electrode 2 are welded objects by a pressurizing mechanism (not shown). W1 and W2 are sandwiched and pressurized. The activation signal is turned on until six spot welding is completed on the metal plates W1 and W2 (see FIG. 4).

  When a time (squeeze) Δt1 from when the activation signal is turned on until energization is possible has elapsed, the control means 7 activates the servo motor 8 and at the same time sends a one-point command ON signal to the timer 5 as an energization command. Output. Then, the timer 5 instructs the transformer 6 to flow a welding current to the first welding point after a predetermined time Δt2 (in this embodiment, 2/50 (= 0.04) sec). Output a one-point welding ON signal.

  At this time, in the changeover switch device 4 shown in FIGS. 2 and 3, the cam surface of the cam (the rightmost cam in FIG. 2) 31 corresponding to the first welding point is in the position shown in FIG. The flat portion 31a of the cam surface is positioned below, and the cam follower 22 contacts the flat surface 31a. Then, the rod 20 always urged upward by the spring 24 moves up together with the movable plate 23, and a pair of left and right switching contacts (switching contacts corresponding to the first welding point) 11 attached to the movable plate 23. (11a, 11b) are in contact with the upper switching contacts 10 (10a, 10b) facing these, respectively, so that the upper electrode 1 and the lower electrode 2 corresponding to the first welding point are connected to the power source 3, A welding current having a predetermined value flows between the upper electrode 1 and the lower electrode 2 at the first point through the timer 5 and the transformer 6 from the power source 3, whereby the two metal plates W1 and W2 are connected to the first point. The welding point is spot welded (see FIG. 4). Note that energization is performed only for a predetermined time Δt3 (8/50 (= 0.16) sec in this embodiment) shown in FIG.

  By the way, the rotation of the servo motor 8 is decelerated at a predetermined ratio by the speed reducer 9 and transmitted to the cam shaft 29 of the changeover switch device 4, and the cam shaft 29 is rotationally driven at a predetermined speed. Here, as described above, the flat portions 31 a formed on the cam surfaces of the six cams 31 are shifted in phase by 60 ° from the ends in order, so that the rotation of the cam shaft 29 causes the next second point. When the flat portion 31a of the cam surface of the cam 31 corresponding to the welding point (second cam from the right in FIG. 2) is positioned downward as shown in FIG. 3, the flat portion 31a comes into contact with the flat portion 31a via the cam follower 22. The second (second from the right in FIG. 2) rod 20 moves upward together with the movable plate 23, and a pair of left and right switching contacts (switching contacts corresponding to the second welding point) 11 attached to the movable plate 23 ( 11a, 11b) abuts on the upper switching contact 10 (10a, 10b) opposite to each other, so that the upper electrode 1 and the lower electrode 2 corresponding to the second welding point are connected to the power source 3 and energized. It becomes possible. At the same time, the rod (the rightmost rod in FIG. 2) 20 corresponding to the first welding point of the changeover switch device 4 is pushed down together with the movable plate 23 by the cam surface of the cam 31. The left and right paired switching contacts 11 (11a, 11b) are separated from the upper switching contacts 10 (10a, 10b) facing them, and the upper electrode 1 and the lower portion corresponding to the first welding point from the power source 3 The electrode 2 is in a state where it cannot be energized (OFF state).

  Thus, when the upper electrode 1 and the lower electrode 2 corresponding to the second welding point are connected to the power source 3 as described above, as shown in FIG. A dot command ON signal is output to the timer 5. Then, since the timer 5 outputs a two-point welding ON signal as a command for flowing a welding current to the second welding point with respect to the transformer 6, the timer 5 passes through the timer 5 and the transformer 6 from the power source 3. A welding current having a predetermined value flows between the upper electrode 1 and the lower electrode 2 at the second point, whereby the two metal plates W1 and W2 are spot-welded at the second welding point (see FIG. 4). .

  In the same manner, a total of six sets of the upper electrode 1 and the lower electrode 2 are switched by the changeover switch device 4 and turned on / off sequentially from the end. As shown in FIG. 4, the two metal plates W1 are turned on. , W2 are sequentially and sequentially welded to the first to sixth welding points in this order.

  By the way, a plurality of (six in the present embodiment) upper electrodes 1 and the same number of lower electrodes 2 are made into one block, and these blocks are divided into a plurality (in the example shown in FIG. 1, the numbers “1” to “1”). 2 ”, a block composed of the upper electrode 1 and the lower electrode 2 labeled“ 6 ”and a block composed of the upper electrode 1 and the lower electrode 2 labeled“ 7 ”to“ 12 ”), By sequentially sandwiching and pressing the metal plates W1 and W2 and W3 and W4 that are to be welded for each block, a plurality of sets of metal plates W1 and W2, W3 and W4 are provided by one power source 3 and one changeover switch device 4. Can be welded in order.

  Here, the welding conditions in the present embodiment are as follows.

・ Servo motor rotation speed: 1,200 rpm
-Initial pressurization time: 10 cyc (10/50 sec)
-Energizing time: 55 cyc (55/50 sec)
-Stop time: 10 cyc (10/50 sec)
・ Current value: 10,000A
-Welding speed: 6 striking points / 2 seconds (tact), 1 striking point / 0.33 seconds As described above, in the present embodiment, each of the plurality of upper electrodes 1 and lower electrodes 2 is configured independently, The upper electrode 1 and the lower electrode 2 are independently connected to the power source 3, and the changeover switch 4 simultaneously turns ON / OFF the pair of the upper electrode 1 and the lower electrode 2 corresponding to each welding point to be welded. Since the supply of current to each welding point of the metal plates W1 and W2, which are objects, is switched and each welding point is sequentially spot-welded by flowing welding current sequentially from the end to a plurality of welding points, Since no current leaks to the electrode 2 or sparks are generated, the welding conditions are stabilized, and a large current can be passed as the welding current, so that high speed can be achieved and high welding efficiency can be ensured. If possible In both cases, the welding time can be shortened.

  In addition, since the intermittent control method (control method using a pulse value) is adopted as the energization control method instead of the continuous control method, optimum current control suitable for each welding point is possible, and high welding quality can be ensured.

  The present invention is useful for a multi-spot welding apparatus that welds a plurality of welding points one by one in order.

It is a block diagram which shows the basic composition of the multi-spot welding apparatus which concerns on this invention. It is a side view of the changeover switch device of the multi spot welding device concerning the present invention. It is the sectional view on the AA line of FIG. It is a timing chart which shows the electricity supply control in the multi spot welding apparatus which concerns on this invention. It is a timing chart which shows the electricity supply control in the multi spot welding apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper electrode 2 Lower electrode 3 Power supply 4 Changeover switch apparatus (current switching means)
5 Timer (T / C)
6 Transformer (TR)
7 Control means 8 Servo motor (M)
9 Reducer (R / G)
10, 11 Switching contact 13 Cam mechanism 17 Fixed plate 20 Rod 22 Cam follower 23 Movable plate 24 Spring 29 Cam shaft 31 Cam W1-W4 Metal plate (to-be-welded)

Claims (3)

In a multi-spot welding apparatus that multi-point welds a workpiece by flowing a welding current between both electrodes from a power source while sandwiching and pressing the workpiece with a plurality of upper electrodes and the same number of lower electrodes,
A plurality of the upper electrode and the lower electrode are independently configured, and the upper electrode and the lower electrode are independently connected to the power source, and the conduction between the pair of the upper electrode and the lower electrode facing each other is simultaneously turned ON / OFF. A multi-spot welding apparatus characterized by comprising a current switching means for switching off the current supply to each welding point of the workpiece to be welded, and flowing a welding current sequentially to a plurality of welding points of the workpiece.   A plurality of blocks each including the plurality of upper electrodes and the plurality of lower electrodes are provided, and the workpieces are welded in order by sandwiching and pressurizing the workpieces for each block. Item 1. Multi-spot welding apparatus according to item 1.   2. The multi-spot according to claim 1, wherein the current switching means includes a number of switching contacts equal to the number of the upper electrodes and the lower electrodes, and a cam mechanism that sequentially contacts and separates the switching contacts. Welding equipment.

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