JPS5920425B2 - How to control automatic welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for automatic welding equipment using a cam plate and a potentiometer, which eliminates the drawbacks of conventional control methods using sequence control signals, etc. Focusing on the fact that there is a certain relationship between the shape and the control bias of the potentiometer, the purpose is to provide a control method that makes it possible to arbitrarily set a specific bias section by utilizing the control bias of the bore and the potentiometer. do.

In general, as a method of controlling the welding speed of a workpiece having a shape such as a chevron or an ellipse so that it is constant, a patent application filed in 1973 is
There is a method of controlling a reference voltage that determines the magnitude of the welding speed using a cam plate and a potentiometer as disclosed in Japanese Patent No. 2-68564.

In this method, a cam plate is installed on a truck that runs along a rail installed parallel to the welding line, and rotates as the truck moves by detecting the chevron-shaped portion, and the potentiometer is operated by the cam plate. .

One circumference of this cam plate corresponds to one chevron-shaped part of the object to be welded, and the cam curve is determined by calculating the position of the cart so that the welding speed is always constant and the speed of the cart at that position. There is. In the case of an object to be welded having a shape such as a chevron, the speed control ratio of a cart or the like to which a welding torch is attached may theoretically be, for example, about 10:1 between the flat part and the chevron-shaped part.

In this case, in a section where the control ratio of speed etc. is large, the speed etc. is extremely small, so if welding is performed at a theoretically determined speed, the welding result may be unfavorable. Furthermore, in order to solve these problems, in the past, a specific bias different from the bias given by the potentiometer was given to the section where the control ratio was large. The method of applying a specific bias was to use a sequence control signal, etc., and use that signal and a timer to set the bias for a specific section and welding speed. However, with this method of using sequence control signals and timers, for example, it is necessary to install a limit switch and its cam for setting a specific section, and it is necessary to install a limit switch and its cam each time the welding speed changes. There was one drawback, such as the need to set a timer.

These problems remain a practical problem in the control method of automatic welding equipment using a cam plate and a potentiometer.

The present invention has been made in response to these conventional problems), and one embodiment of the present invention will be described below with reference to the drawings.

Fig. 1a is an explanatory diagram showing that a welding torch 2 attached to a truck is welding a chevron-shaped workpiece 1 at a welding speed v. The truck stops, and the torch 2 rotates by an angle α around point p.

Then, in the Yamagata section, the trolleys start running again. In order to keep the welding speed v constant, the trolley traveling speed at that time is v
As shown in FIG. The constant speed section of the bogie using the cam plate and potentiometer is the section. This section is further divided into sections -1 and -2, and section -1 is a section where the control ratio of bogie speed is extremely large;
In other words, the bogie running speed is in section 1. )1. V) This is an extremely small section. Conventionally, a timer or the like was operated using the sequence control signal that became the section, and section -1 was set.

Alternatively, the section-2 may be detected by a limit switch or the like, and the section-1 may be set by combining it with the section's sequence control signal.

FIG. 1b shows the timing when the trolley runs, and FIG. 1c shows the timing when the relay in FIG. 2 is turned on, that is, the timing when a specific bias is applied.

FIG. 2 shows a control method according to the present invention for realizing the speed control as shown in FIG. The variable resistor 5 is connected. The voltage extracted from the variable resistor 5 is applied to an amplifier 6 for impedance conversion.

On the output side of the amplifier 6, a variable resistor r and a potentiometer 8 are connected in series with the variable resistor r. The variable resistor r is used to set the maximum value of the bias controlled by the potentiometer 8.

The variable resistor 9 is used to extract a bias signal for setting a specific speed in section -1 of FIG. Further, the differential amplifier 10 at the final stage uses the output of the amplifier 6 and the voltage on the line 11 as input signals to generate a final reference voltage (-Es) that determines the magnitude of speed, etc. It is fed to the speed governor 4 from above.

The voltage on line 11 is applied by relay contacts 13 and 14 to the voltage set by variable resistor 9 when contact 13 is closed, that is, when relay 15 is closed, and the voltage set by variable resistor 9 is applied to When 14 is closed, the voltage from potentiometer 8 is applied. Next, the inside of the dotted line 16 will be explained. The inside of the dotted line 16 is a circuit for detecting the section -1 in FIG. 1, and the interval of the section -1 is set by the variable resistor 1r.

The larger the voltage taken out by the variable resistor 17, the wider the section -1 in FIG. 1 becomes. Regarding the output of the differential amplifier 18, when the section changes from the section shown in FIG. However, when the sliding terminal of the potentiometer 8 comes close to the ground line, a negative output is generated. That is, the point of change in the output of the potentiometer 8 over the operating period changes depending on the variable resistor 1r. The previously mentioned relay 15 is turned on only when the output of the differential amplifier 18 is positive.

Further, the amplifier 19 is simply for amplifying the transistor 2.
0 is for driving the relay 15. Relay 15 may alternatively be a switching element or its equivalent. Here, assuming that the potentiometer 8 has a resistance value of 1KΩ, an output value of 2W, and a reference voltage of 5V, the moving speed of the welding torch 2 (speed of the trolley) in section 1 is 70 to 210 h/M.
in, section 70-1407! Set the potentiometer 8 in the Lllll/Mi range, 1.77 to 0.17.
It can be changed up to 2 times (COs 8も).

Conventionally, as a method for applying a specific bias that is set separately from the bias applied by the potentiometer 8, a limit switch and a sequence control signal, or a combination of these and a timer, etc., have been used to determine the period in which a specific bias is applied and its magnitude. However, this method first requires a dog for the limit switch (a plate for the closing section), and since the dog has a relationship with the cam plate, there are various issues in terms of installation and adjustment. There is a problem.

Also, if you want to change a particular bias interval, you must adjust the dog. Furthermore, if a specific bias interval is set with a timer, the time limit of the timer must be reset each time the speed of the truck changes.

On the other hand, the method according to the present invention does not require a dog for a mechanical limit switch and solves problems such as adjusting the installation of these parts.

Further, the specific bias section can be changed by a variable resistor connected to the slider of the potentiometer, and there is no need to adjust the dog. Furthermore, even if the speed of the cart changes, the specific bias section can be kept the same, so you don't have to reset the time limit each time, as you would do if you set the section with a timer. In the method according to the present invention, the specific bias also changes at the same rate depending on the magnitude of the speed, so it is an extremely effective control method.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing that a chevron-shaped workpiece is being welded by a torch attached to a trolley while controlling the speed at a constant speed, and Figure 2 is an illustration showing the speed control as shown in Figure 1. FIG. 2 is a circuit diagram of an apparatus for carrying out the suppression method of the present invention. 1... Work to be welded, 2... Welding torch,
3...Bogie motor, 4... Speed governor,
5... Variable resistor, 6... Amplifier, 7
...Variable resistor, 8...Potentiometer, 9...Variable resistor, 10...Differential amplifier, 13,14... ...Contact, 15...
...Relay, 17...Variable resistor, 18...
...differential amplifier, 19...amplifier.

Claims (1)

[Claims] 1 In a control method for an automatic welding device that controls the welding speed of a chevron-shaped workpiece using a potentiometer driven by a cam plate, the voltage taken out by a variable resistor connected to the sliding terminal of the potentiometer is The voltage applied to the fixed terminal of the potentiometer is applied to one terminal of the dynamic amplifier, and the voltage applied to the fixed terminal of the potentiometer is applied to the other terminal, and the output of the differential amplifier obtained from these two inputs is used to connect a relay or switching element, etc. is operated, and the input signal of the differential amplifier, which uses this switching element to create the reference voltage that determines the speed, is switched to obtain a speed different from that controlled by the potentiometer. Features: Control method for automatic welding equipment.