JPS5834233B2 - Spot welding method for multi-dot workpieces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spot welding method for metal plates, in particular a workpiece having a planar shape with a considerably large length in one direction, and a large number of spot welding points (hereinafter referred to as " This is a spot welding method that is particularly effective when the welding method has a welding point (referred to as a dot).

When spot welding (hereinafter sometimes abbreviated as "spot welding") a workpiece with a large number of welding points (hereinafter referred to as "multi-dot workpiece") using a conventional spot welding machine, we usually start from one end of the workpiece. Start dotting and gradually advance to the other end.

However, when a multi-dot workpiece is long in one direction, when you start dotting one end of the workpiece, the other end of the workpiece causes a so-called "unruly" phenomenon, which seriously impedes normal welding of the workpiece. arise.

The method of the present invention is to spot weld a multi-point workpiece that is long in one direction as described above by starting spot welding from both ends of the workpiece simultaneously by using two welding units, and reducing the work time required to do spot welding of all the welding points. It is characterized by not only shortening it by half, but also suppressing the above-mentioned unruly phenomenon and greatly improving work efficiency, and also eliminating inconveniences in work by specifying the order of dotting.

The details of the present invention will be explained below with reference to the accompanying drawings.

The multi-dot workpiece to which the method of the present invention is applied has a planar shape that is long in one direction, as shown in FIG. 4W, and has a large number of dots indicated by X marks.

The dots of such a multi-dot work are L,
, L2... and R1, R2..., and each column is a, b,...
...often includes multiple dots like e.

Counting this row of dots sequentially from both ends, Ll from the left toward the center of the workpiece.

It is divided into a left dot row group of n columns of L2...Ln, and a right dot row group of the same number of R1, R2...Rn from the right or one more column up to Rn+1.

In the present invention, all dot rows of a multi-dot workpiece are divided into the above two groups, and left and right welding units are respectively provided from corresponding dots (a or e) in the L1 row and R1 row at both ends of the workpiece W. One each of welding heads 6L and 6R (Figures 1 to 3)
and start dotting at the same time.

The order of dotting is arbitrary, but when dotting starts from Lla and Rla, it is normal to do it as shown by arrow S in FIG. 4.

In this first step, the two welding heads move symmetrically toward the center of the workpiece.

After performing an arbitrary number of dots in the previous step, for example, when the dots at the L2a dot and R2a dot are completed, one of the two welding heads, for example the right welding head 6R,
The other left welding head 6L is moved to the next dot point R3a in the dot row group, but the other left welding head 6L is moved to the Lna dot point in the row corresponding to the R3a dot point in the central dot row of the left welding dot row group to which it belongs.

Here, after dotting both the Lna and L3a dots at the same time, the remaining dots are dotted (later step) while moving the two welding heads in the same direction as indicated by the broken line arrows, for example.

In workpiece welding with an odd number of dot rows, there is a case where one dot row is worked alone at the end on the welding head side on one side (in this example, if the center of the right dot row group is the Rn+ row, then the right). Such a situation is much more advantageous than one in which two welding heads interfere with each other in the center of the workpiece, making one inoperable.

Next, an example of a welding apparatus for carrying out the above welding method will be described.

In FIGS. 1 to 3, a welding machine frame F that supports the entire apparatus is arranged behind a base frame F1 and left and right columnar frames F3. It has a vertical frame F2 that connects F3 with a connecting frame F4, and this vertical frame is equipped with a unit lateral movement device, the whole of which is indicated by the symbol 1, so that the two left and right welding units UL and UR can be moved laterally. To support.

In the embodiment, both columnar frames F3. Upper and lower lateral guide rails 11, 11 are fixed to F3, and the left lateral movement frame 10L and the right lateral movement frame 10R are connected to the sliding arm 1.
2 and is slidably supported.

Support brackets 14, 14 are provided on the outer surfaces 13 of the columnar frames F3 on both sides, and horizontal side support frames 15, 15 attached to the brackets support the left lateral movement shifter 16.
L and right lateral movement shifters 16R are supported, and the operating rods 17 of both lateral movement shifters are connected to the left and right lateral movement frames 10L, IOR.
connected to each side plate.

By expanding and contracting the lateral movement shifter, the left and right lateral movement frame IOL,
10R moves horizontally separately.

Left and right unit vertical movement devices 2 are installed on both lateral movement frames 10L and 10R, respectively.

Each lateral movement frame has a pair of vertical guide rods 21.21.
The left unit support frame 20IJ and the right unit support frame 20R are each supported vertically movably.

Both unit support frames are moved up and down by rotating the handle 22.

This device serves as a rapid feed mechanism for the welding unit.

The left and right contact units hUL and UR are unit back and forth movement devices 3 supported by the above-mentioned both side unit support frames 20L and 20R.
The left and right unit frames 4L are attached to the front ends of the left unit advancement/retraction lever 30L and the right unit advancement/retraction lever 30R, respectively.
, 4R.

In the embodiment, the left and right unit support frames 20L.

Horizontal rear support frames 31 and 31 are respectively fixed to the rear of 20R, and a left forward/backward cylinder 32L and a right forward/backward cylinder 32R are supported by these, respectively.

The left unit advancement/retraction rod 30L is the left unit support frame 20L.
It extends back and forth through the left advance/retreat cylinder 32L, and moves back and forth together with the piston (not shown) of the cylinder.

Similarly, the right unit advancement/retraction lever 30R is also connected to the right unit support frame 2.
It passes through 0R and the right forward/backward cylinder 32R and moves back and forth.

Both unit advancement/retraction levers 30L, 30R are prevented from rotating around their axes by known means.

The left and right unit frames 4L and 4R have, for example, vertical guide rails 41 on both front sides thereof, and support the left and right head frames 5L and SR, which carry the left and right welding heads 6L and 6R, in a vertically movable manner. .

A head elevating cylinder 40 is supported above the unit frame by a cylinder support plate 42, and raises and lowers the head frames 5L and SR.

The head frames 5L and 5R each consist of an elevating frame 51 that is connected to the head elevating cylinder 40 and moves up and down, and a U-shaped frame 52 that is recessed in a substantially U-shape toward the rear, and the lower portions of the left and right welding heads. An electrode 61 is fixed to the lower front end of the U-shaped frame 52.

The upper electrode 62 is supported by the elevating frame portion 51 so as to be movable up and down, and is moved up and down by the electrode cylinder 60.

The functions of the head elevating cylinder 40 and the electrode cylinder 60 will be explained later.

A workpiece support stand 70 is arranged in front of the welding head, and the horizontally long multi-dot workpiece W is mounted on a vertical frame F.
Support parallel to 2.

The illustrated workpiece support stand 70 is in the form of a pair of L-shaped support stands on both sides, and is fixed on a horizontal pedestal 73 of a workpiece support device, which is generally designated by reference numeral 7, and is a known clamp device (not shown). to support both ends of the workpiece W.

The workpiece support device 7 is entirely supported on a frame F7 fixed to the front of the base frame.

On both sides of the stationary frame F7, there are shaft support frames F5. F is standing, and its swing axis 71
As a result, a swing frame in which the swing plates 72, 72 on both sides are connected by the pedestal 73 is swingably supported.

The swing plate 72 is pivotally supported near its upper end by a swing shaft, and an operating rod 75 of a work shifter 74 such as a hydraulic cylinder is connected to a pedestal 73 that connects the lower end of the swing plate 72, so that the swing plate 72 can rotate. The swing frame is swung around the shaft 71.

This configuration is useful for tilting the workpiece so that its impact surface becomes horizontal when the workpiece W has an arcuate shape or a bent portion W1 as shown in FIG.

F6 is a shifter support frame that supports the base end of the chic; 7
6 is a shifter receiving frame.

Although there is one work shifter 74 in the illustrated embodiment, two work shifters can be arranged on both sides of the pedestal 73 if necessary.

Next, the proximity sensing device 8 will be explained.

Mainly referring to FIG. 3, a mold support frame F8 supported at the rear of the vertical frame F2 has a mold plate 80 fixed thereon with a large number of magnet pins 81 arranged and fixed at predetermined positions. has been done.

On the other hand, the rear ends of the left and right unit advancing and retracting rods 30L and 30R each have an extension portion 33 that reaches above the mold plate 80,
Each supports left and right proximity switches 82L, 82R.

Each proximity switch is supported by a switch support 83 attached to the rear end of the extension portion 33 via an elevating member 84 so that its vertical position can be adjusted. is adjusted so that it can face the upper surface of the magnet pin 81 in close proximity (with a gap of about 2 mm), and moves over the mold plate 80 as the lateral motion frames 10L, 10R move horizontally and the unit advancement/retraction rods 30L, 30R move back and forth. Move each separately.

The magnet pins 81 are arranged corresponding to the positions of a large number of dots on the workpiece W.

When the multi-striking workpiece W is supported by the workpiece support device 7 that is displaced according to the inclination of the striking surface, the magnet pins are arranged at corresponding positions that have been corrected by calculation in advance.

Here, a case will be described in which the method of the present invention is implemented using the spora 11 welding machine of the present invention having the above configuration.

The lower electrode 61 and the upper electrode 62 of the welding head 5 (common to L and R) are normally spaced apart from each other by d as shown in the figure along the vertical axis.
has.

This interval is made to be wider than t (including the case where the workpiece W is thick and has an arcuate or inclined portion Wl, etc., and is tilted as shown by the chain line in FIG. 3).

If the opening between both electrodes (portion d) and the workpiece support surface are not aligned, turn the rapid-forwarding handle 22 of the unit vertical movement device 2 to align the positions as shown in Figures 1 and 3.
In the horizontal direction, the workpiece is allowed to move forward and backward between both electrodes.

The gap between the magnet pin 81 and the proximity switch 82, which changes as a result of this adjustment, is corrected and adjusted manually or automatically by the elevating member 84.

And both welding heads 6L. The 6R electrodes are arranged facing the rows of dots L1 and R1 at both ends of the workpiece.

When using the device of the illustrated embodiment, the method of the invention is subsequently carried out automatically under the control of a sequence control device (not shown) in combination with the proximity sensing device 8, according to a predetermined program.

For example, the mode is as follows.

When the start switch is turned on, the advancing/retracting cylinders 32L and 32R of the unit forward/backward movement device are actuated, respectively, and both welding heads are advanced toward the dot array L1°R1 at both ends of the workpiece.

Magnet pins 81 corresponding to each stage a to e of the L1 dot row and R1 dot row on the mold plate 80 are arranged at positions where the proximity switch 82 advances as the unit advancement/retraction rod advances.

When the proximity switches 82L and 82R on both sides each reach directly above the magnet pin, they stop the advancing and retracting cylinders to which they belong, and then start the welding units) UL and UR.

The welding unit U (common to UL and UR) of the embodiment operates as follows upon starting.

Upon startup, first the piston of the head elevating cylinder 40 (
(not shown) rises to bring the lower electrode 61 into contact with the lower surface of the workpiece.

An air cylinder is normally used as the head lifting cylinder 40, and its operating pressure is based on the head frame 5 (5L, 5
The weight of the entire welding head 6 (common to R) and welding head 6 (common to 6L and 6R) is set to be smaller than G.

Needless to say, when the head lifting cylinder 40 operates, the work shifter 74 of the work support device 7 operates to horizontally support the first hitting surface W1.

Next, the piston (not shown) of the electrode cylinder 60 descends to press the upper electrode 62 against the upper surface of the workpiece.

Electrode cylinder 60 is typically a hydraulic cylinder.

The electrode pressure P must be selected in a certain relationship with the welding current, and varies depending on the material of the workpiece, plate thickness, contact area between the electrode tip and the workpiece, etc.
The optimal pressing force P can be achieved by adjusting the pressure generated in
Welding can be carried out with the work piece being applied to the workpiece.

When one dotting point is completed, the electrode cylinder 60 and the head lifting/lowering cylinder 40 return to their original states and release the workpiece.

According to the welding unit that operates as described above, the workpiece is clamped between the lower electrode 61 and the upper electrode 62, and current is applied while maintaining the optimal electrode pressure P, so that extremely uniform spot welding can be performed. It can be effective.

Furthermore, if the workpiece supporting device operates so that the dot surface of the workpiece is always horizontal and provided to both electrodes, the welding result will be good and there will be an effect of eliminating wear due to uneven wear of the electrodes.

After the work is released, the forward and backward cylinders 32L and 32R (in the case of lateral movement, the lateral movement shifters 16L and 16R) operate again to move the left and right welding units to the next programmed dot point, and dot dots in the same order. is repeated.

When the programmed number of dots at both ends is completed, only one welding unit moves to the center dot row of the dot row group to which it belongs, for example, the Ln row, and from then on both welding units point in the same direction. Perform spot welding in the later stage of the process by moving the workpiece, and complete the spot welding of one multi-dot workpiece.

According to the method of the present invention described above, spot welding of multi-spot workpieces is performed by two dots per operation, which not only reduces the number of operations to 1/2, but also completely eliminates the phenomenon of workpiece vibration. As a result, work efficiency can be greatly improved.

Moreover, the reduction in efficiency due to interference between the two devices resulting from the use of two welding heads can be easily avoided by implementing the present invention.

In addition, the present invention quickly and reliably clamps the electrodes with the optimum pressure force,
Since the current is applied while the constant pressure is maintained, uniform spot welding can be performed.

In carrying out the method of the present invention, it is extremely advantageous that one welding machine supports two welding units and is capable of moving them individually in the front, back, left, right, and up and down directions.

[Brief explanation of drawings]

The drawings show an example of an apparatus and a workpiece for carrying out the method of the present invention. Fig. 1 is a front view of a spot welding machine, and Fig. 2 is a plan view thereof with a part of the connecting frame cut away. Figure 3 is a cross-sectional side view of the rear support frame with a part of the columnar frame and the front side plate of the lateral motion frame removed, and Figure 4 is a plan view showing an example of a multi-dot workpiece. It is. F...Welding machine frame, W...Multi-dot work, UL
(UR)...Left (l Welding unit, 1...Unit lateral movement device, 2...Unit vertical movement device, 3...Unit longitudinal movement device, 6L (6R)...Left (right) welding head.

Claims (1)

[Claims] 1 A long workpiece in one direction has n dot rows from L1 row to Ln row counting from both left and right sides, and the left dot row group and R1 row to R11 row or Rn 1,000 row is the same number as the left side or one row more. In welding a multi-dot workpiece W having a large number of dots consisting of a right dot row group, after simultaneously welding corresponding dots in the L1 row and R1 row at both ends of the workpiece with two welding heads, the two welding heads The first step is to weld the left and right dot groups in the order in which the head is moved toward the center of the workpiece, and one of the two welding heads is welded to the welding dot row (Ln, Rn or Rn+1
A spot of a multi-dot workpiece in which all dots of the multi-dot workpiece are spot-welded through a subsequent step of spot-welding the remaining dots while moving the two welding heads in the same direction. Welding method.