JPH0651232B2 - Self-propelled seam welder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a self-propelled seam welder that continuously performs seam welding in which two thin steel plates and a plurality of overlapping portions of two or more thin steel plates are mixed. .

[Conventional technology]

A self-propelled seam equipped with a welding transformer, applying a pressing force to a pair of disc electrodes to which electric power is supplied from the transformer to sandwich a thin steel plate, and rotating the disc electrodes by an electric motor. In a welding machine, for example, as shown in FIG. 3, a thin steel plate 9 is sandwiched by a pair of disc electrodes 1a and 1b supplied with electric power from a welding transformer 5, and a pressing force (not shown) is applied to the disc electrodes. While performing the seam welding, the electric motor 2 is driven to rotate to perform seam welding. In FIG. 3, the phase control circuit 7 controls the firing phase of the SCR 6 by the signal of the welding current setting device 8 to obtain the required welding current. On the other hand, the traveling speed control circuit 3 controls the rotation speed of the electric motor 2 by the signal of the speed setting device 4 to obtain the required traveling speed. Then, the welding current and the traveling speed are respectively adjusted to match the optimum welding conditions. It is generally known that the relationship between the welding current and the traveling speed is such that the welding current decreases as the traveling speed increases, and conversely the welding current increases as the traveling speed decreases. This relationship also shows the welding data obtained by the inventor.

Thus, in seam welding of two or more than two thin steel plates, seam welding is performed by setting welding conditions such as welding current and welding speed according to the number of stacked plates. However, for example, when welding two sheets and four sheets together in a seam welding process such as a welding process of a stainless steel sheet for roof waterproofing, when welding is performed under the welding conditions of two sheets, the welding current is insufficient at the four sheets portion. Unmelted, a healthy welding effect cannot be obtained. Conversely, when welding is performed under the condition of four-ply welding, the welding current becomes excessive at the two-ply portion and burn-through occurs, which is also a sound welding. No effect.

On the other hand, a pressing force is applied to the disk electrode by a spring, a spring, etc., and this pressing force reduces the contact resistance between the steel plates, so that a desired welding current can be obtained. When this pressure force passes through the two-layer stack and the multiple-sheet stack of two or more sheets, the larger the number of stacks, the stronger the pressure, the smaller the contact resistance between the steel plates, and the lowering of the welding current to some extent. However, in the case of seam welding in which two sheets are stacked and four sheets are mixed, the effect of such a spring or spring cannot be expected so much.

Further, the pressure applied by such springs, springs, etc. changes due to wear of the disk electrode, and stable welding results cannot be obtained. As a method for adjusting the pressure, JP-A-58-100981
The method found in the publication is also being tried. However, it is difficult to adjust springs, springs, etc. for thin steel plates with a thickness of about 0.4 mm by such mechanical methods.
It is not perfect in seam welding in which one sheet and multiple sheets of two or more sheets are mixed.

Therefore, regardless of the mechanical method, by detecting the welding current and controlling the ignition phase of the SCR according to the change of the welding current, the input voltage of the primary side of the welding transformer is controlled, and the secondary side of the welding transformer is controlled. There is a method of keeping the welding current constant. This method is intended to make the welding current constant by feedback control of the welding current because the welding current changes due to fluctuations in the power supply voltage, the resistance value of the workpiece, the pressure applied to the disc electrode, etc. It is necessary to take measures even when the decrease in welding current is large. Therefore, it is necessary to make the capacity of the welding transformer sufficiently large, and the weight of the welding transformer becomes heavy, and the self-propelled seam welder equipped with the transformer has extremely poor portability and a roof with poor footing. There is a problem that it is not suitable for in-situ welding such as seam welding for waterproofing of plates.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above point, and it is possible to continuously weld two sheets of thin steel plates and seam welding in which two or more sheets are mixed, and the portability is high. The present invention provides a self-propelled seam welder capable of obtaining good welding quality.

[Means for Solving the Problems]

The gist of the present invention is a self-propelled seam welding machine in which a welding transformer is mounted, an object to be welded is sandwiched by a pair of disc electrodes, and the disc electrodes are rotationally driven by an electric motor while applying a pressing force. In, a reference current setting device for setting the reference welding current, a detector for detecting the welding current, a comparison circuit for comparing and amplifying the setting signal of the reference current setting device and the welding current signal detected by the detector, A self-propelled seam welding machine, comprising: a traveling speed control circuit that controls a rotational speed of the rotary drive motor for the disk electrode according to an output signal of the comparison circuit.

[Action]

 The present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a self-propelled seam welder according to the present invention. In FIG. 1, a reference current setting device 13 for setting a reference welding current is provided, a detector 11 for detecting a welding current is provided, and a setting signal of the reference current setting device and a welding current signal detected by the detector are provided. A comparison circuit 10 for comparison and amplification is provided, and a signal from the comparison circuit is input to the traveling speed control circuit 3 to control the rotation speed of the electric motor 2 that rotationally drives the disk electrodes 1a and 1b. Further, the switching contacts 12a and 12b are used to switch between the traveling speed control according to the present invention and the traveling speed control by the conventional speed setter 4 shown in FIG. 3, and the other one when the contact 12a is closed. The contact 12b is opened, and conversely, when the contact 12a is opened, the contact 12b is closed to switch between running speed control by welding current detection and running speed control by the speed setter 4.

Next, FIG. 2 shows the configuration of the comparison circuit 10 shown in FIG. Second
In the figure, the welding current signal detected by the detector 11 is amplified by the amplifier 14, and the reference current setter 13 is amplified by the comparison amplifier 15.
When the welding current detected by the detector 11 and the welding current set by the reference current setting device 13 match, the control electric motor 17 is rotated by the DC servo amplifier 16 after being comparatively amplified with the setting signal of The output of the DC servo amplifier 16 becomes zero and the control electric motor 17 is stopped. A potentiometer 18 whose slider moves by its rotation is mechanically attached to the control electric motor. A voltage signal corresponding to the position of the slider of the potentiometer is input to the traveling speed control circuit 3 shown in FIG. 1, which controls the rotation speed of the electric motor 2. At that time, with respect to the welding current set by the reference current setting device 13, when the welding current detected by the detector 11 is low, the traveling speed is slowed down, and when it is high, the traveling speed is increased. The rotation direction of the control electric motor 17 and the movement direction of the slider of the potentiometer 18 are matched.

Now, in FIG. 1, the switching contact 12a is opened and the contact 12b is closed, and the speed setter 4 is adjusted to match the proper welding speed. Next, two thin steel plates are sandwiched between the disc electrodes 1a and 1b, and seam welding is performed, and the welding current setting device 8 is adjusted so that the welding current becomes an appropriate welding current. The phase control circuit 7 controls the ignition phase of the SCR 6 by the signal of the welding current setting device to control the primary voltage of the welding transformer 5, and the welding current is adjusted to a desired value. Switching contact 1 in this state
2a is closed and the contact 12b is opened, the appropriate welding current is set by the reference current setting device 13, two thin steel plates are again sandwiched between the disc electrodes to perform seam welding, and the welding speed at this time is the appropriate welding. The output of the comparison circuit 10 is adjusted so that the speed is achieved.

Next, seam welding is performed by sandwiching the mixed thin steel plates of two-ply and four-ply plates between the disc electrodes, and at the two-ply part, the welding is performed at the proper welding speed of the two-ply part and the four-ply part is formed. In this case, the welding current sharply decreases due to the increase in the resistance value of the steel plate, and the detection signal of the detector 11 decreases. As a result, a difference from the proper welding current set by the reference current setting device 13 is generated, the output signal of the comparison circuit 10, that is, the input signal of the traveling speed control circuit 3 becomes small, and the disc electrodes 1a, 1b are rotationally driven. The rotation speed of the electric motor 2 becomes slow. Then, the welding current decreases again as the welding speed decreases, and when the proper welding current set by the reference current setting device 13 is reached, the output of the comparison circuit 10 becomes a constant value and the proper welding speed is maintained. Further, when the four-sheet overlapping portion is applied to the two-sheet overlapping portion, the welding current sharply increases due to the decrease in the resistance value of the steel sheet, and the detector 1
The detection signal of 1 increases. As a result, the reference current setting device 1
3, the output signal of the comparison circuit 10, that is, the input signal of the traveling speed control circuit 3 becomes large, and the rotation speed of the electric motor 2 that rotationally drives the disk electrodes 1a, 1b increases. Get faster Then, as the welding speed increases, the welding current decreases again, and when it reaches the proper welding current set by the reference current setting device 13, the comparison circuit 10
Output becomes a constant value and maintains an appropriate welding speed.

〔Example〕

Using the present invention, seam welding was performed in which SUS304 and a plate thickness of 0.4 mm were laminated in two layers and four layers were mixed. As a result of the welding experiment, the proper welding current and the proper welding speed for each of the two-layer and four-layer stacks were obtained by performing a welding experiment at a speed of 4 m / min for the two-sheet portion, a welding current of 3400 A, and two for the four-sheet portion.
The speed was m / min and the welding current was 3400A. Therefore, when a welding experiment according to the present invention was performed by setting 3400A with the reference current setting device, the welding speed was 4m / min at the two-ply portion, 3400A, and 3400A was maintained at the four-ply portion (2m. / Min) kept stable. On the contrary, if the four-ply part and the two-ply part are applied in this state, the running speed is 3400.
It increased to the speed of maintaining A (4 m / min).

As a result, the actual welding current was always stable at 3400 A, there were no visual defects, and the nugget width was 2.5 on average.
mm was shown, and no abnormalities were observed in the peel test, which was very good.

〔The invention's effect〕

As described above, according to the present invention, the actual welding current is detected with respect to the current value set by the reference current setting device that sets the reference welding current, and the rotation speed of the disc electrode is controlled by the deviation thereof. Since the traveling speed can be controlled, it is possible to keep the welding current constant by controlling the traveling speed corresponding to the change of the resistance value of the object to be welded and the fluctuation of the power supply voltage. As a result, seam welding in which two or more sheets of thin steel sheets are mixed can be continuously performed, and good welding quality can be obtained. Since the traveling speed can be controlled in response to fluctuations, the welding transformer need only meet the maximum appropriate welding current, and thus a lightweight and portable self-propelled seam welder can be provided.

[Brief description of drawings]

1 is a block diagram showing the construction of a self-propelled seam welding machine according to the present invention, FIG. 2 is a circuit diagram showing the construction of the comparison circuit 10 of FIG. 1, and FIG. 3 is a conventional self-propelled seam welding machine. It is a block diagram showing a machine. 1a, 1b ... Disc electrode, 2 ... Electric motor, 3 ... Travel speed control circuit, 4 ... Speed setting device, 5 ... Welding transformer, 6 ... SCR, 7 ... Phase control circuit, 8 ... … Welding current setting device, 9… Thin steel plate, 10… Comparison circuit, 11… Detector, 12a, 12b… Switching contact, 13… Reference current setting device, 14… Amplifier, 15… Comparison amplifier , 16 …… DC servo amplifier, 17 …… control motor, 18 …… potentiometer, 19 ～ 24 …… fixed resistor, 25 …… capacitor.

Front page continuation (72) Inventor Hiroshi Kashihara 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa Inside Nippon Steel Co., Ltd. 2nd Research Laboratory (72) Inventor Toru Saito 5-10-1, Fuchinobe, Sagamihara-shi, Kanagawa Nippon Steel Corporation Second Technical Research Center

Claims (1)

[Claims] 1. A self-propelled seam welder equipped with a welding transformer, a pair of disc electrodes for sandwiching an object to be welded, and an electric motor for rotating the disc electrodes to set a reference welding current. Reference current setting device, detector for detecting welding current, comparison circuit for comparing and amplifying setting signal set by the reference current setting device and welding current signal detected by the detector, and output signal of the comparison circuit And a traveling speed control circuit for controlling the rotation speed of the rotary drive electric motor for the disc electrode according to the present invention.