JPH0260436B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is formed on the edge of a hood panel of a vehicle body, and the edge of one metal plate is sandwiched between the edges of the other metal plate. The present invention relates to a welding device for a folded overlapping part, generally called a hemming part, which is formed by folding and overlapping edges.

(Prior Art) Generally, a folded overlapping portion (hereinafter referred to as a hemming portion) is formed on the outer peripheral edge of a two-ply metal plate such as an engine hood or trunk lid of an automobile. The folded overlapping part is fixed by temporarily fixing the two metal plates by welding.
This is accomplished by, for example, heating a thermosetting resin that has been applied to the surface joint between the two metal plates to connect them.

Therefore, as welding equipment for temporarily fixing overlapping parts such as hemming parts, spot welding machines (Fig. 5) and arc brazing using welding rods (Fig. 6) have been used because of their versatility and ease of use. It was getting worse. 5 and 6 show an example of welding a hemming part 05 when manufacturing an engine hood, and this hemming part 05 is arranged so as to sandwich the outer peripheral edge part 03 of the inner panel 01. It is formed by folding back the outer peripheral edge 04 of the outer panel 02. In the spot welding machine shown in Fig. 5, 06 is a tip, 07 is a back bar, and in the arc brazing shown in Fig. 6, 08 is a tip.
is the arc blazing site.

However, the above-described welding apparatus has the following problems.

Originally, the portion where the hemming portion as described above is formed is a portion that is exposed to the outside, and is treated in this way for safety and appearance.

However, when spot welding or arc brazing is performed, thermal distortion occurs on the surface of the metal plate at the hemming part and the outer metal plate due to high temperatures, resulting in an unsightly appearance. Finishing treatment is required, which takes a lot of man-hours and effort.

In addition, when spot welding is used, it requires a very large current, which tends to increase power consumption and increase costs.Furthermore, the chips and back bars also wear out quickly due to the passing current. Polishing or replacement becomes necessary in a short period of time.

In addition, when using arc brazing,
The skill level of the operator is also required, leading to problems such as variations in welding strength and finish, making it impossible to obtain consistent quality.

By the way, conventionally, in an attempt to solve these problems, an ultrasonic welding device as described in Japanese Utility Model Application Publication No. 57-204887 has been used.

This device consists of an ultrasonic welding machine that applies ultrasonic vibration to a chip using an ultrasonic vibrator, a pedestal that supports the workpiece while pressing it against the chip with a constant pressure, and The device consists of a moving device that moves the workpiece to be welded relative to the chip.

That is, when welding metal plates together using this conventional apparatus, ultrasonic vibration is applied while the metal plates are pressed together. By doing so, the distance between the metals becomes extremely close, an attractive force acts between the atoms, and furthermore, the temperature rise due to frictional heat helps to form a bond between the metals. Therefore, with this conventional device, the heat generated during welding is low, so that no or almost no thermal distortion occurs in the metal plate.

(Problems to be Solved by the Invention) However, in the conventional device as described above, the following problems remain.

That is, although it does not require much operator skill like arc brazing, it is difficult to completely eliminate variations in welding strength because there is no means to confirm welding strength.

Also, although it is possible to reduce the current flowing through the chip compared to spot welding, pressing force and frictional force will be applied to the chip, so if the chip is made of a relatively soft material, However, it wears out quickly and requires polishing or replacement in a short period of time.

(Means for Solving the Problems) The present invention ensures that the surface of a metal plate is not distorted by heat during welding for temporary fixing of folded overlapping parts, and that welding strength above a predetermined level is reliably achieved. It is an object of the present invention to provide a welding device for a folded overlapping part which can be obtained as well as to cause less chip wear, and to solve the above-mentioned problems.

In order to achieve this objective, the present invention:
An ultrasonic welding machine is constructed by arranging an upper chip and a lower chip made of high-hardness metal to face each other so as to be able to grip the edges of the workpiece, and an ultrasonic vibrator being attached to one of the chips. The ultrasonic welding machine is attached to a supporting part at the tip of a mobile robot, and the mobile robot can move the ultrasonic welding machine on the supporting part along the edge of the workpiece based on motor drive. A relative distance detector is provided between a member on the upper tip side and a member on the lower tip side of the ultrasonic welding machine, and the relative distance detector detects the pressure applied to both chips by driving a pressure cylinder. It is configured to be able to detect the relative distance in the pressure direction, and to output a signal corresponding to this detected distance to a monitor device, and the monitor device is configured to detect the relative distance between the chips before welding and the relative distance after welding. By comparing the relative distance, it is determined that a normal solution has been formed when the distance change is a predetermined value or more, and it is determined that welding is insufficient when the distance change is less than a predetermined value.

(Function) The welding device for folded overlapping portions of the present invention performs welding according to the procedure described below.

First, the edge portions of one metal plate are folded back and overlapped with each other so that the edge portions of the other metal plate are sandwiched, thereby forming a folded overlapping portion.

Next, the upper chip and the lower chip are moved to predetermined positions in the folded overlapping part by a moving robot, and while applying pressure to the folded overlapping part with both chips and crimping them, ultrasonic waves are applied to one of both chips. A vibrator applies ultrasonic vibration parallel to the overlapping surface of the folded overlapping part to ultrasonically weld the folded overlapping part.

At this time, the monitor device monitors whether normal welding strength has been obtained based on the signal from the relative distance detector. That is, a signal corresponding to the relative distance in the pressurizing direction between the upper and lower chips detected by the relative distance detector is input to this monitor device, and the thickness of the welding point can be detected from the distance between the two chips. In other words, in the case of ultrasonic welding, when the welding is completed to the extent that normal welding strength can be obtained, there is a thickness change of more than a predetermined value between before and after welding, and if the welding strength is insufficient, This thickness change (equal to the relative distance change in the pressurizing direction by the pressurizing cylinder) does not reach a predetermined amount. Therefore, the monitoring device determines that normal welding has been completed when the relative distance between the upper and lower chips changes by a predetermined value or more between before and after welding, and if this distance change is less than a predetermined value, welding is determined to have been completed. Decide it's not enough.

After confirming by the monitor that normal welding has been completed with the welding strength reaching the specified strength, the pressure and vibrations are removed from the overlapped part, and a mobile robot moves both chips to the next stage. Move to welding position, etc.

In this way, with the ultrasonic welding device of the present invention, it is possible to confirm whether or not normal welding that achieves the specified strength has been performed, so that the folded overlapping portion can be reliably temporarily fastened with the necessary and sufficient welding strength. can do.

Furthermore, since the upper tip and lower tip are made of high hardness metal, wear caused by pressing force or frictional force is reduced.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, a case will be taken as an example in which an engine hood for an automobile is manufactured.

First, the configuration of the embodiment device will be explained.

Welding device 1 for folded overlapping parts according to an embodiment of the present invention
As shown in FIG.
The main components are a mobile robot 10, an ultrasonic welder 20, a gun arm 30, an upper chip 40, a lower chip 50, and an ultrasonic vibrator 60.

In addition, 101 in the figure is the engine hood 10 at the time of welding.
The engine hood 100 is a fixing device that fixes the engine hood 100, and is composed of a clamp 102 that clamps and fixes the engine hood 100, and a base 103.

Further, reference numeral 104 in the figure is a conveyance device for conveying the engine hood 100 to the fixing device 101 and for conveying it to the next process after welding is completed.

As shown in FIG. 4, the engine hood 100 includes an outer panel 10 made of steel or aluminum.
5 and an inner panel 106, and this bonding is performed by adhering with a thermosetting resin applied to a convex portion 107 formed on the inner panel 106.

Further, the edge portion of the outer panel 105 is folded back and overlapped with the outer circumferential edge portion of the engine hood 100 so as to sandwich the outer circumferential edge portion of the inner panel 106, and a hemming portion (folded overlapping portion) 108 is formed.
is formed.

Note that the engine hood 100 has both panels 1
The fixing device 101 is transferred to the fixing device 101 by the conveying device 104 in a state where the thermosetting resin applied between 05 and 106 is not cured and the hemming portion 108 is formed.
It is sent to.

The moving robot 10 is a robot generally used for welding, and can move the supporting part 11 at the tip to any location on the fixing device 101 by means of a motor drive.

The ultrasonic welding machine 20 shown in FIGS. 2 and 3 is attached to the support part 11 with a mounting bracket 21, and is composed of a gun arm 30, an upper tip 40, a lower tip 50, and an ultrasonic vibrator 60.

The mounting bracket 21 has a U-shaped cross section as shown in FIGS.
A guide rod 24 is vertically supported by a guide rod 23, and a stopper 26 is provided which is supported by a bar 25 horizontally suspended at the intermediate portion and restricts the upward sliding of a slide block 35, which will be described later.

The gun arm 30 is attached to the guide rod 24 of the mounting bracket 21, as shown in FIGS.
It is supported so that it can slide up and down along the
It is floatingly supported by a spring 27 with respect to the support plate 23.

Further, a support plate 32 is provided at the upper end of the gun arm 30 to support an air cylinder 31 as a pressure cylinder that pressurizes the upper cylinder 40, and at an intermediate position, a support plate 32 is provided to support a piston rod 33 that is moved up and down by the air cylinder 31. A guide rail 34 is provided parallel to the piston rod 33, and a lower tip 50 is provided at the lower end of the piston rod 33 at a position directly below the piston rod 33.

A slide block 35 is provided at the lower end of the piston rod 33 and slides along a guide rail 34.

Further, on the side surface of the gun arm 30, as shown in FIG. , move the needle body 36 to the slide block 35.
A differential transformer (relative distance detector) 37 is provided in contact with the. This differential transformer 3
7 is an input part of a displacement control monitor device (monitor device) not shown, which detects the amount of displacement of the slide block 35 with respect to the gun arm 30 during welding, that is, the relative distance between the upper and lower tips 40 and 50. , which outputs an electrical signal according to the detection result. Incidentally, the displacement control monitor device can be constituted by a well-known simple device such as a comparator that outputs Hi when the output signal of the differential transformer 37 is equal to or higher than a predetermined value.

The attachment chip 40 is attached to the slide block 3.
5, coaxially with the piston rod 33, and facing the lower tip 50.

Therefore, by driving the air cylinder 31 to move the piston rod 33 downward,
The thing sandwiched between both chips 40 and 50 can be pressurized from above and below.

Incidentally, both chips 40 and 50 are both made of high hardness metal such as hardened steel or super hard alloy.

The ultrasonic vibrator 60 is an electric one, and is located approximately in the center of the above-mentioned atupachip 40.
It is installed so that it can be vibrated in a direction perpendicular to the 0,50 pressure direction.

In addition, in FIG. 3, the pedestal 1 is disposed between the lower chip 50 and the hemming part 108.
10 with an engine hood 100 as a base 103
It is also supported by the lower tip 50 when welding.
It also presses the hemming part 108 and further suppresses vibration transmission to parts other than the welding point, and includes a support part 111, a peripheral receiving part 112 made of resin or a relatively soft metal, and a hard metal. It has an anvil 113.

Next, the operation of the embodiment will be explained.

First, a hemming portion 108 is formed on the outer peripheral edge of the engine hood 100 before it is transported to the fixing device 101, and a thermosetting resin is applied between the panels 105 and 106 at the convex portion 107. ing.

Next, the engine hood 100 is placed on the fixing device 101 by the conveying device 104, and
The hemming portion is clamped and fixed by clamps 102. Note that during this fixing, a pedestal 110 is placed below the welding point.

After doing so, the mobile robot 10 operates according to the program and moves the ultrasonic welding machine 20 to a predetermined position, that is, a position where the welding point of the hemming part 108 and the pedestal 110 are arranged between both chips 40 and 50. move it to

In addition, during such movement, the ultrasonic welding machine 2
The air cylinder 31 of No. 0 is connected to the slide block 35.
The gun arm 30 moves upwardly until it is restricted by the stopper 26. In this state, the gun arm 30 moves downwardly relative to the mounting bracket 21, and the spring 27 is shortened and becomes a rigid body.

Therefore, when the spring 27 is in the shortened state, the gun arm 30 is not supported in a floating manner with respect to the support portion 11 and the mounting bracket 21, and does not wobble when the ultrasonic welding machine 20 is moved.

Next, both chips 40 and 50 are attached to the hemming portion 108.
When the welding point and the anvil 113 are placed in a position sandwiching the anvil 113 from above and below, the air cylinder 31 is operated so that the slide block 35 and the hot tip 40 are guided by the guide rail 34 and slide downward.

Then, the gun arm 30 (lower tip 50) moves upward due to the elastic force of the spring 27, and the upper tip 40 moves downward relative to the gun arm 30 (lower tip 50). By this operation, both chips 40, 50 can be accurately positioned.

Then, as shown in Figure 3, both chips 4
Hemming part 108 and anvil 113 at 0.50
When the two panels 105 and 106 in the hemming section 108 are pressed together with a predetermined pressure, the ultrasonic vibrator 60 is operated to press against the hot tip 40 in a direction perpendicular to the pressing direction, that is, both panels 105 and 106 in the hemming section 108 are pressed together. Ultrasonic welding is performed by applying vibration in a direction parallel to the overlapping surface of 106.

In this ultrasonic welding, rubbing occurs between the edge of the outer panel 105 on the side of the attachment tip 40 and the upper surface of the edge of the inner panel 106 at the hemming portion 108 shown in FIG. Welding is done by

Note that during this ultrasonic welding, both chips 40 and 50 are connected to the displacement control monitor device (not shown).
The differential transformer 3 regulated by the slide block 35 applies a predetermined pressing force.
The position of the needle body 36 of No. 7 is read as the 0 position, and the pressure direction (vertical direction in the figure) of both chips 40, 50 is compared between this 0 position and the position after ultrasonic welding (this difference is in microns). (slight difference in units),
If the distance between both positions is greater than or equal to a predetermined value, welding is determined to be normal.
When the predetermined value is not reached, it is determined that the welding is insufficient. That is, in the case of ultrasonic welding, when welding is completed to a level that provides normal welding strength, a change in thickness greater than a predetermined value occurs between before and after welding. If the welding strength is insufficient, this thickness change will not reach a predetermined amount, so the differential transformer 37
Air cylinder 3 with both chips 40 and 50 obtained by
It is possible to determine whether or not welding is possible by detecting the relative distance in the pressurizing direction according to No. 1 instead. In a normal welding state, the necessary welding strength can be obtained. Further, the change in the thickness of the hemming portion 108 that causes this difference occurs between the two panels 105 and 106 on the atsupachip 40 side where the above-mentioned rubbing occurs and is not exposed to the outside when attached to the vehicle body. No changes such as distortion occur on the surface side.

When welding at this welding point is completed, the mobile robot 10 moves the ultrasonic welding machine 20 to the next welding point, and all welding points are welded by ultrasonic welding.

Note that this ultrasonic welding is performed on both panels 105 and 106.
It is for temporary fixing when joining the panels 105 and 106, and is not intended to completely join the panels 105 and 106.

Thereafter, when welding at all points is completed, the engine hood 100 is transported to an oven by the transport device 104 and heated to harden the thermosetting resin, and the joining of both panels 105 and 106 is completed.

In the case of ultrasonic welding as described above, both panels 10
5,106 is not melted by heat, the temperature is extremely low compared to other welding, and both panels 10
No thermal distortion occurs in 5,106.

As explained above, in the examples,
It has the following effects.

Since the method is such that no or almost no thermal distortion occurs in the folded overlapped part, there is no or almost no need for finishing treatment of the folded overlapped part after welding, thereby saving manufacturing man-hours and labor. I can do it.

It does not require the same level of skill as arc brazing, and the differential transformer 37 and displacement control monitor can accurately determine whether the welding strength has reached the specified strength, so welding can be repeated with uniform welding strength. Overlapping parts can be temporarily fixed, making it easier to maintain constant product precision.

Since the upper chip 40 and the lower chip 50 are made of a high-hardness metal, and the upper chip 40 and the lower chip 50 are made of high-hardness metal, they are highly durable with little wear.

Energy consumption during welding is based on ultrasonic vibrator 6.
Since only those used for the operation of 0 are used, the number of welds can be significantly reduced compared to the case of spot welding.

Ultrasonic welding machine 6 by mobile robot 10
Since welding is performed by moving the welding point 0, a large number of welds can be performed in a short period of time, and the versatility of the device can also be increased.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments. However, the present invention is not limited to this, and may be applied to welding of trunk lids and folded overlapping parts (hemming parts) formed in members used for things other than automobiles.

(Effects of the Invention) As explained above, the welding device for folded overlapping parts of the present invention has the advantage that thermal strain can be prevented from occurring at all or almost no in the folded overlapping parts. , it has the following effects:

That is, in the welding device for folded overlapping parts of the present invention, by providing a relative distance detector and a monitoring device, it is possible to accurately temporarily fasten the folded parts with a welding strength higher than a predetermined level at all times. Another advantage is that the product accuracy can be stabilized.

Furthermore, since the upper tip and lower tip are formed of high-hardness metal as a means of reducing wear, the durability of the tip is improved and the effort of polishing and replacement can be saved.

[Brief explanation of drawings]

Fig. 1 is an overall perspective view showing a welding device for folded overlapping parts according to an embodiment of the present invention, Fig. 2 is a perspective view showing main parts of the embodiment equipment, and Fig. 3 is a sectional view showing main parts of the embodiment equipment. , FIG. 4 is a sectional view showing an engine hood welded by the embodiment apparatus, and FIGS. 5 and 6 are perspective views showing a conventional example. 10... Mobile robot, 20... Ultrasonic welding machine, 30... Gun arm, 37... Operating transformer (mutual distance detector), 40... Atsupachip, 50
...Lower tip, 60...Ultrasonic vibrator, 105
... Outer panel (metal plate), 106 ... Inner panel (metal plate), 108 ... Hemming part (folding and overlapping part).

Claims (1)

[Scope of Claims] 1. An upper chip and a lower chip formed of high-hardness metal are arranged facing each other so as to be able to clamp the edges of the workpiece, and an ultrasonic vibrator is attached to one of the chips. An ultrasonic welding machine is configured, the ultrasonic welding machine is attached to a supporting part at the tip of a mobile robot, and the mobile robot is driven by a motor to move the ultrasonic welding machine on the supporting part to the object to be welded. A relative distance detector is configured to be movable along an edge, and is provided between an upper tip side member and a lower tip side member of the ultrasonic welding machine, and the relative distance detector is configured to be movable along an edge of the ultrasonic welding machine. is configured to be able to detect the relative distance in the pressurizing direction of both chips due to the drive of the chip, and is configured to output a signal corresponding to this detected distance to a monitor device, and the monitor device is configured to detect the relative distance between the chips before welding the chips. Compare the relative distance with the above-mentioned relative distance after welding, and when this distance change is a predetermined value or more, it is determined that normal welding has been completed, and when the distance change is less than a predetermined value, it is determined that welding is insufficient. Features: Welding equipment for folded overlapping parts.