JPS6132115B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-point workpiece spot welding apparatus suitable for performing multiple spot welding on a long planar workpiece.

When spot welding a large number of spot welding points (hereinafter referred to as ``dot points'') using a conventional spot welding machine (hereinafter sometimes abbreviated as ``spot welding''), the welding points are usually started at one end of the workpiece and sequentially welded. Continue dotting to the other end. However, when a multi-dot workpiece is long in one direction, when one end starts dotting, the other end of the workpiece causes a so-called "unruly" phenomenon, which seriously impedes normal welding of the workpiece. arise.

In the apparatus of the present invention, two welding units are supported by a welding machine frame having a width capable of supporting a long workpiece at both ends and lighting the workpiece as described above, and the two welding units are horizontally ( It is characterized by being configured so that it can be moved separately in the length direction of the workpiece), the up-down direction, and the front-rear direction (direction perpendicular to the length of the workpiece).

The multi-dot workpiece targeted by the apparatus of the present invention has a planar shape with a length in one direction, as shown in FIG.
It has a number of dots represented by marks. From both ends of the dots of such a multi-dot workpiece, L ₁ , L ₂ ...
and R ₁ , R ₄ , etc., and each row often includes a plurality of dots such as a, b, . . . e. Counting this row of dots sequentially from both ends, L ₁ from the left toward the center of the workpiece,
L ₂ ... left dot row group of n rows of Ln, and R ₁ and R ₂ from the right
...It is divided into a right-side dot row group with the same number of Rn or one more row up to Rn+1.

According to the apparatus of the present invention, all dot rows of a multi-dot workpiece are divided into the two groups described above, and from the corresponding dots (a or e) of the _L1 row and _R1 row at both ends of the workpiece W,
Dotting can be started simultaneously using one welding head 6L, 9R (to be described in detail later) provided in each of the left and right welding units. The order of dotting is arbitrary, but when dotting starts from L _1a and R _1a , it is usually done 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 L _2a dot and R _2a dot are completed, one of the two welding heads, for example the right welding head 6R, performs the dot at that dot. The welding head 6L is moved to the next welding point R _3a in the row group, but the other left welding head 6L is moved to the next welding point R _3a in the center dot row of the left welding point row group to which it belongs.
Move to the Lna dot of the row corresponding to the dot. 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 dashed arrows, for example. When welding a workpiece with an odd number of dot rows, there may be cases where the final dot row is worked alone on one side (the right if the center of the right dot row group is the Rn+1 row in this example) welding head side. The situation is much better than having two welding heads interfere with each other in the center of the workpiece, making one inoperable.

Next, the welding apparatus of the present invention will be explained in detail based on the drawings.

In Figures 1 to 3, a welding machine frame F that supports the entire device is a frame that connects left and right columnar frames _F3 and _F3 to the rear of a base frame _F1 .
It has a vertical frame F ₂ connected by F ₄ , and this vertical frame is equipped with a unit lateral movement device, the whole of which is indicated by the symbol 1, to support the two left and right welding units UL and UR so that they can move laterally. .

In the embodiment, the columnar frames F ₃ , F ₃ on both sides
Upper and lower lateral guide rails 11, 11 are fixed to , and a left lateral movement frame 10L and a right lateral movement frame 10R are slidably supported by a sliding arm 12. Support brackets 14, 14 are provided on the outer surfaces 13 of the columnar frames _F3 on both sides, and the horizontal side support frames 15, 15 attached to these brackets support the left lateral movement shifter 16L and the right lateral movement shifter 16.
R is supported, and the operating rod 17 of both lateral movement shifters
are connected to each side plate of the left and right lateral motion frames 10L, 10R. Due to the expansion and contraction of the lateral movement shifter, the left and right lateral movement frames 10L and 10R move laterally 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 2
1 and 21, and supports a left unit support frame 20L and a right unit support frame 20R, respectively, so as to be movable up and down. Both unit support frames are attached to handle 2.
By rotating 2, it moves up and down. This device serves as a rapid feed mechanism for the welding unit.

The left and right welding units UL and UR are left and right unit frames 4L attached to the front ends of the left unit advancement/retraction lever 30L and the right unit advancement/retraction lever 30R of the unit longitudinal movement device 3 supported by the above-mentioned both side unit support frames 20L, 20R. , 4R.

In the embodiment, the left and right unit support frames 20L, 2
Horizontal rear support frames 31, 31 at the rear of 0R
are fixed, 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 connected to the left unit support frame 20L and the left advancement/retraction cylinder 32.
It extends back and forth through L, and moves back and forth together with the piston (not shown) of the cylinder. Similarly, the right unit advancement/retraction lever 30R also passes through the right unit support frame 20R and the right advancement/retraction cylinder 32R and moves back and forth. Both units advance/retract levers 30L, 30R
is prevented from rotating around its axis by known means.

The left and right unit frames 4L and 4R have, for example, vertical guide rails 4 on both front sides thereof.
1, and vertically movably supports left and right head frames 5L, 5R carrying left and right welding heads 6L, 6R. 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 5R.

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 is located at the lower part 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 lifting cylinder 40 and the electrode cylinder 60 will be explained later.

A work support stand 70 is disposed in front of the welding head, and the workpiece W which is long in the lateral direction is
is supported parallel to the vertical frame F 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 in front of the base frame. On both sides of the metering frame F ₇ , there are shaft support frames F ₅ and F ₅ that support the swing shaft 71.
The swing shaft 71 allows the swing plates 72, 72 on both sides to
A swing frame connected by the pedestal 73 is swingably supported.

The swinging plate 72 is pivoted near its upper end by a swinging shaft, and an operating rod 75 of a work shifter 74, such as a hydraulic cylinder, is connected to a pedestal 73 connecting the lower end of the swinging plate 72. 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 shifter, and 76 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 . A template 80 is placed in position and fixed. 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, and each of the left and right proximity switches 82L and 82
I support R. 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 the magnetic pin 81
It is adjusted so that it can face the upper surface of the unit in close proximity (with a gap of about 2 mm), and moves separately on the mold board 80 as the lateral movement frames 10L and 10R move laterally and as the unit advancement and retraction rods 30L and 30R advance and retreat. 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 work supporting device 7 which is displaced according to the inclination of the dot-striking surface, the magnetic pins are arranged at corresponding positions corrected by calculation in advance.

Here, the use of the spot welding machine of the present invention having the above configuration will be explained.

The lower electrode 61 and the upper electrode 62 of the welding head 6 (common to LR) normally have the illustrated spacing d along the vertical axis. This interval is made to be larger than the thickness t of the workpiece W (including the case where the workpiece has an arc shape or an inclined part _W1 and is tilted as shown by the chain line in FIG. 3). There is.
If the opening between both electrodes (d part) and the workpiece support surface are different from each other, turn the rapid-forwarding handle 22 of the unit vertical movement device 2 to align the position as shown in Figures 1 and 3, and then level it. The workpiece is allowed to move forward and backward between both electrodes in the direction of . The magnet pin 81 and the proximity switch 8 change depending on this adjustment.
2 is corrected and adjusted manually or automatically by the elevating member 84. And both welding heads 6
Electrodes L and 6R are dot rows L ₁ and R ₁ at both ends of the workpiece.
placed opposite.

The spot welding apparatus of the present invention can be operated automatically under the control of a sequence controller (not shown) in combination with a 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 operate, respectively, to move both welding heads to the dot rows L ₁ , 32 at both ends of the workpiece.
Move toward R ₁ . A of each of the L ₁ dot row and R ₁ dot row on the mold plate 80 is placed at the position where the proximity switch 82 advances as the unit advancement/retraction rod advances.
- e Magnet pins 81 corresponding to each stage are arranged. When the proximity switches 82L and 82R on both sides respectively reach directly above the magnet pin, they stop the forward and backward cylinders to which they belong, and then start the welding units UL and UR.

The welding unit U (common to UL and UR) in the example is:
When it is started, it operates as follows.

Upon startup, the piston (not shown) of the head lifting cylinder 40 rises to bring the lower electrode 61 into contact with the lower surface of the workpiece. Head lifting cylinder 4
Normally, an air cylinder is used for 0, but its operating pressure is set to be greater than G, where G is the entire weight of the head frame 5 (common to 5L, 5R) and welding head 6 (common to 6L, 6R). . Needless to say, when the head lifting cylinder 40 operates, the work shifter 74 of the work supporting 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 must be selected depending on the workpiece material, plate thickness,
Since the pressure varies depending on the contact area between the electrode tip and the workpiece, by adjusting the pressure generated in the electrolytic cylinder 60, it is possible to perform welding while applying the optimal pressure P to the workpiece.

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

According to the welding unit that operates as described above,
The workpiece is held between the lower electrode 61 and the upper electrode 62, and the current is applied while maintaining the optimal electrode pressure P, so that extremely uniform spot welding can be performed. Furthermore, if the workpiece support device operates so that the welding surface of the workpiece is always horizontal and available to both electrodes, the welding result will be good and there will be an effect of eliminating wear due to one-sided wear of the electrodes.

According to the welding unit that operates as described above,
Since the contact pressure (welding pressure) of both electrodes that clamp the workpiece is always maintained at a constant pressure of α+β, it is effective to obtain extremely uniform spot welding. Furthermore, if the workpiece supporting device operates so that the welding surface of the workpiece is always horizontal and available to both electrodes, welding results are good and there is an effect of eliminating wear due to one-sided wear of the electrodes. However, the device of the present invention is not required to have such a specific configuration.

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

When dots at both ends of the programmed number of dots are completed, only one welding unit moves to the dot row in the center of the dot row group to which it belongs, for example, the Ln row, and
Thereafter, the welding units on both sides move in the same direction to perform spot welding in the latter step, thereby completing spot welding of one multi-dot workpiece.

According to the welding device of the present invention as described above, spot welding of multi-spot workpieces is performed by spot welding two spots per operation, which not only reduces the number of operations to 1/2, but also prevents the workpiece from flailing. As a result, it can be completely suppressed, which has the effect of greatly improving work efficiency. Moreover, there is an effect that a decrease in efficiency due to interference between the two devices resulting from the use of two welding heads can be easily avoided.

[Brief explanation of the drawing]

The drawings show an example of a spot welding device and a workpiece according to the present invention. FIG. 1 is a front view of the spot welding device, FIG. 2 is a plan view of the spot welding device with a part of the connecting frame cut away, and FIG. The figure is a side view showing the rear support frame in cross section with a part of the columnar frame and the front side plate of the lateral movement frame removed, and FIG. 4 is a plan view showing an example of a multi-dot workpiece. F...Welding machine frame, W...Multi-dot workpiece,
UL, UR...Left (right) 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)

[Scope of Claims] 1. A vertical frame F ₂ including left and right columnar frames F ₃ , F ₃ provided at the rear of both sides of the base frame F ₁ of the spot welding machine, and a horizontal horizontal guide rail supported by the vertical frame F ₂ 11, 11, horizontal guide rail 1
1 and 11, a left lateral movement frame 10L and a right lateral movement frame 10R, which are supported by the columnar frame _F3 on the left side and move the left lateral movement frame 10L from side to side, and a left lateral movement shifter 16L and the right side. The right lateral movement frame 1 is supported by the columnar frame F ₃ .
Right lateral movement shifter 16R that moves 0R left and right;
A left unit support frame 20L is supported by the left and right lateral motion frames 10L and 10R so as to be movable up and down, respectively.
and a left forward/backward cylinder 32L and a right forward/backward cylinder 32 supported at the rear of the right unit support frame 20R, left and right unit support frames 20L, 20R, respectively.
R, left unit advancement/retraction rod 30 that moves back and forth by left and right advancement/retraction cylinders 32L, 32R, respectively.
L and right unit advancement/retraction levers 30R, left and right unit frames 4L and 4R supported by the front ends of left and right unit advancement/retraction levers 30L, 30R, left and right unit frames 4L, 4R, respectively.
Left welding unit UL and right welding unit UR supported respectively, and left and right welding heads 6
A multi-point workpiece spot welding device characterized by comprising a workpiece support stand 70 that supports the workpiece across the front surfaces of L and 6R. 2 The left and right welding units UL and UR are
Left and right head frames 5 are supported by left and right unit frames 4L and 4R, respectively, so that they can be raised and lowered.
L, 5R, and lower electrodes 6 fixed to the front ends of the U-shaped frames of the left and right head frames 5L, 5R, respectively.
The left and right welding heads 6L, 6R are equipped with a welding head 1 and an upper electrode 62 that can be raised and lowered in opposition thereto, and are connected to the left and right head frames 5L, 5R, respectively.
left and right head lifting cylinders 40 that expand and contract with an operating pressure that generates a force greater than the sum of the weights G, and left and right electrode cylinders that are connected to the upper electrode 62 and can apply a predetermined electrode pressure P to the workpiece. 60. A spot welding device for multi-dot workpieces according to claim 1, wherein the spot welding device is constituted by a spot welding device for a multi-dot workpiece. 3 The work support stand 70 is the left and right shaft support frame.
It is placed on a pedestal 73 of a swinging frame that can swing around swinging shafts 71, 71 on both sides supported by _F5 , _F5 , and operates with a welding machine frame as a base on the swinging frame. A multi-spot workpiece spot welding apparatus according to claim 1, wherein an operating rod 75 of a workpiece shifter 74 is connected.