JPH0813417B2 - Quality stabilizing device for TIG welding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a quality stabilizing device for TIG welding, in which the penetration of weld beads in TIG welding is made constant and the welding quality is improved and stabilized.

[Conventional technology]

TIG welding is performed by abutting a pair of members to be welded and applying a voltage from a welding power source between the electrodes and the member to be welded while running a non-consumable electrode such as a tungsten electrode along the butted portion. When performing the welding, if the welding current is not appropriate, or if the running line of the electrode and the abutting portion of the member to be welded do not coincide with each other, the welding bead may be insufficiently melted to deteriorate the welding quality. This inspection of welding quality has conventionally been performed by an operator by visually checking the back bead of the welded member. Then, the current was adjusted and the torch was aligned by hand so that the back bead was visually good.

In addition, as a welding quality inspection means of this type, there is disclosed in
As described in Japanese Patent Laid-Open No. 56-102375, a welding method in which the temperature of a welded portion is measured and the welding heat input is controlled so that this temperature becomes a preset temperature, and Japanese Patent Publication No. As described in JP-A-59-8472, an arc that generates a welding failure signal by shaping the current waveform during arc welding into a rectangular wave and detecting the number of waveform changes corresponding to arc breaks. A welding quality determination device and method are known.

[Problems to be Solved by the Invention]

However, it is difficult to visually inspect the bead misalignment during TIG welding as in the past, and skill is required to adjust the welding current so that insufficient penetration does not occur by looking at the bead. . Therefore, if an unskilled worker adjusts the core misalignment and the welding current, it takes time, and the number of working steps increases and the operating rate of the welding machine decreases. Further, there is a disadvantage that the bead melting is not constant and stable welding quality cannot be obtained because there is a difference in judgment depending on the operator who inspects. Especially in the welding of galvanized steel sheets due to high current where the electrode wear is severe, it is necessary to frequently inspect the quality and adjust the welding current, resulting in an increase in man-hours and a decrease in operating rate.
There is also a problem that the cost for polishing the electrode and its cost increases because proper current adjustment is not performed.

In addition, all the proposals in the above publications did not consider the misalignment of the welding bead and the automatic adjustment of the welding current in TIG welding.

The present invention has been made in view of the above circumstances, and is capable of automatically stabilizing the welding quality in TIG welding.
The purpose is to provide a quality stabilization device for G welding.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention brings a pair of members to be welded into contact with each other, and runs a non-consumable electrode along the joint portion while applying a voltage from a welding power source between the electrodes and the member to be welded. In a quality stabilization device for applying TIG welding by applying a torch position adjusting means for adjusting the position of the torch holding the electrode in the bead width direction, and a measuring means for measuring the height and misalignment of the bead. And means for storing control limits for the height and misalignment of the bead, and comparing the height and misalignment for the bead measured by the measuring means with the control limits stored by the storage means. And a control means for feedback-controlling the welding current and the torch position adjusting means so as to be within the control limit value, and a means for selecting those not within the control limit value. Shi It is intended.

[Action]

According to the above configuration, the height and misalignment of the bead during TIG welding are measured by the measuring means, these measured values are input to the feedback control means, and the bead quality control limit stored in this control means is controlled. When the feedback value set within the value is reached, the welding power source and the torch position adjusting means are feedback-controlled to control the welding current and the torch position so as to be within the control limits, and the appropriate bead height and core are set. The amount of deviation can be obtained.

As a result, those that do not fall within the control limits are excluded,
Welding quality can be improved by making the bead penetration constant.

〔Example〕

An embodiment of a quality stabilizing device for TIG welding according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, a torch 2 is supported by a welding device (not shown) via a torch position adjusting device 1, and along a butt portion of a pair of members to be welded 3 placed on a work support table (not shown). The torch 2 travels together with the torch position adjusting device 1. This torch position adjusting device includes a first ball screw 5 which is rotationally driven by a first motor 4 and
The torch holder 6 which is screwed into the ball screw 5 to support the torch 2 and the first encoder 7 which detects the rotation angle of the ball screw 5.

Then, the first motor 4 is driven by a signal from the torch position adjustment control device 8, and the rotation angle of the first ball screw 5 rotationally driven by the first motor 4 is the first.
Is detected by the encoder 7 and is fed back to the torch position adjusting control device 8 to move the torch 2 to a predetermined position.

On the other hand, a measuring device 10 for measuring the height and the amount of misalignment of the bead 9 of the welded member 3 is provided in the inspection process which is a separate process from this. This measuring device 10 has a second motor
It is composed of a second ball screw 12 which is rotationally driven by 11, a distance sensor 13 which is screwed into the second ball screw 12, and a second encoder 14 which detects a rotation angle of the second ball screw 12. . The rotation of the second motor 11 causes the distance sensor 13 to form the bead 9 formed on the welded member 3.
In the width direction of the bead 9, and the member 3 to be welded moves in the length direction of the bead 9 to cause the distance sensor 13 to scan on the bead 9 so that the distance sensor 13 scans the bead 9 on the back surface of the inspection table (not shown). The distance to the welded member 3 placed with the bead side up is measured.

This measuring device 10 measures the distance between the surface of the member to be welded and the maximum height of the bead 9 by the distance sensor 13,
These distance signals are sent to the computer 16 via the sensor controller 15. The position of the distance sensor 13 when the distance sensor 13 detects the maximum height of the bead 9 and the abutting portion of the member 3 to be welded is measured by the second encoder 14, and this position signal is sent to the computer 16.

This computer 16 causes the bead 9 according to the distance signal.
Of the bead 9 is calculated based on the position signal. Further, the control limits of these bead height and misalignment amount are input in advance to the computer 16, and the bead height and misalignment amount calculated to the feedback value set within these control limit values are When it reaches, a correction command signal is output to the feedback sequencer 17.

The sequencer 17, which has received the correction command signal, issues a correction command to the welding power source 18 for the bead height correction command signal and to the torch position adjustment control device 8 for the misalignment amount correction command signal. Thus, the welding current and the torch position are feedback-controlled so that the bead height and the misalignment amount always fall within the control limits.

Next, the operation of the specific embodiment will be described with reference to FIGS. 1 to 3. Fig. 2 shows an example of the manufacturing process that is made by joining blank materials for underbody press parts of automobiles by TIG welding.

In the transfer step (a), the three materials 19, 20, 21 are sent to the welding step (b) by a destack feeder (not shown), and in this welding step (b), the joint 22 between the materials 19 and 20 and the material Butt welding is performed on the joint 23 of 20 and 21 by TIG welding. Next, in the inspection step (c), the welded blank material 24 is inverted, the weld bead height H and the center deviation amount S are measured by the above-described method, and a computer is used.
The welding power source 18 and the torch position adjusting device 1 are feedback-controlled via 16 so that the bead height H and the misalignment amount S automatically fall within the control limits.

In addition, in the inspection step (c), a non-defective product in which each of the elements is within the control limit and a defective product in which the elements are not included are selected, and in the loading step (d), the determination result is not shown. To the non-defective product pallet 25 and the defective product pallet 26, respectively.

Next, the quality control means used in the inspection step (c) will be described.

The distance sensor 13 provided in the measuring device 10 is connected to the member 3 to be welded.
Of the bead 6 of the member 3 and the bead 6 by scanning the bead 6 in the width direction.
Encoder that measures and synchronizes the distance to the surface of the
The position of the distance sensor 13 is measured by and is input to the computer 16. The computer 16 calculates the bead height H and the misalignment amount S based on these distance signal and position signal.

These H and S values reach the feedback values 31, 32 and 33, 34 set within the control limits 27, 28 and 29, 30 of the control charts shown in Fig. 3 (a) and (b), respectively. At this time, a correction command is output to the feedback sequencer 17, and the sequencer 17 outputs the correction command to the welding power source 18 and the torch position adjustment control device 8, respectively.

Then, as shown in FIG. 3 (a), when the average height 35 of the beads for each blank material reaches the lower limit value 36, the welding power source 18
It is controlled so that the welding current flowing through the coil rises by a predetermined amount. Further, as shown in FIG. 3 (b), when the material lot or the like is changed and the material length is changed and the bead misalignment S reaches the upper limit value 37, the torch 2 is moved by a predetermined amount on the side opposite to the bead misalignment direction. Control to move to.

According to the present embodiment, the welding current and the torch position are stabilized by automatically performing feedback control in accordance with the variation in the penetration depth of the bead 9 caused by the wear of the electrode, the change in the size and shape of the material joint, and the like. Welding quality can be secured. As a result, the number of electrode replacements is reduced, the tool cost and the work man-hour can be reduced, and the operating rate of the welding apparatus can be improved.

〔The invention's effect〕

According to the present invention described in detail above, the bead height and the amount of misalignment in TIG welding are measured, and the current and torch position of the welding power source are corrected by feedback control according to the measured values. That which does not automatically fall within the control limit value is excluded, stable welding quality can always be secured, and it is possible to reduce the tool cost and work man-hour and improve the operating rate of the welding apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a quality stabilizing device for TIG welding according to the present invention, FIG. 2 is a plan view showing an example of working steps of TIG welding, and FIG. 3 is used for this embodiment. It is a welding quality control chart. 1 ... Torch position adjusting device, 2 ... Torch, 3 ... Welded member, 9 ... Bead, 10 ... Measuring device, 16 ... Computer (control means), 18 ... Welding power source, 22, 23 ... … Joints.

Claims (1)

[Claims] 1. TIG welding in which a pair of members to be welded are brought into contact with each other and a voltage is applied between the electrodes and the member to be welded by a non-consumable electrode while running the non-consumable electrode along the joint. In the quality stabilizing device, the torch position adjusting means for adjusting the position of the torch holding the electrode in the bead width direction, the measuring means for measuring the height and misalignment of the bead, and the height of the bead. Means for storing the control limit value of the amount of misalignment and misalignment, and the control limit value stored in the storage means and the height and misalignment amount of the bead measured by the measuring means are compared and judged, respectively. A control means for feedback-controlling the welding current and the torch position adjusting means so as to be within a control limit value, and a means for selecting ones that do not fall within the control limit value. quality Joka apparatus.