JPS60148676A - Speed control device of welding wire - Google Patents

Abstract

PURPOSE:To obtain a titled device for controlling automatically a feed speed and simplifying a circuit without being influenced by an external condition such as a temperature, etc., by measuring a wire feed speed with a pulse count conversion by a digital tachometer, in case of an automatic control of a wire feed. CONSTITUTION:A welding wire 9 is fed by a rotation of a roller 11 by a decelerating motor 14, and its speed is converted to a count of a digital tachometer 20 by a detecting roller 27. This count measures by a register 31 a count number in a prescribed time of a counter 30 by a standard timer 32t and a delay 32 and sends it to a processing unit 33. The processing unit 33 instructs a correct feed speed to the decelerating motor 14 by executing an operation by a set welding current value 36, a data table set value 34 and a program 39 for operating a CPU. In this way, a welding wire is fed automatically without being influenced by an external condition, by a simple mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the feeding speed of welding wire.

In semi-automatic welding and automatic welding, the welding wire, which is the filler metal, is fed by sandwiching the welding wire between a pressure roller and a feed roller, and driving the feed roller by a wire feed motor. There is.

The welding wire feeding speed and welding current are as shown in Figure 1 if the wire protrusion length, which is the distance between the welding wire nozzle and the workpiece to be welded, is constant and the welding power source is a constant voltage power source. Since it is uniquely determined as shown in the graph, the welding current is generally adjusted by changing the feeding speed of the welding wire. Therefore, when the wire feeding speed changes from a predetermined speed, the welding current changes, which affects the welding result, such as excessive or insufficient leg length of the welded part.

Particularly in welding robots, the welding current that changes depending on the wire protrusion length is compared with a standard current in the vertical profiling between the welding torch and the workpiece, which is part of arc profiling, and the wire protrusion length is kept constant. It is controlled as follows.

However, as described above, the welding current also changes depending on the wire feeding speed, so if the wire feeding speed changes due to disturbance or the like, the welding current changes and the wire protrusion length changes. As a result, the protrusion length may be too short and the welding wire nozzle collides with the base metal, or the protrusion length may be too long, resulting in poor shielding of the welded area, resulting in welding defects such as blowholes and spots. However, there may be cases where it does not adversely affect left and right arc tracing.

The feeding speed of the welding wire may change not only due to fluctuations in the power supply voltage, but also simply by replacing parts of the wire feeding device, such as the tip, tip, and spring liner.

Conventionally, as shown in FIG. 2, a tacho generator 2 is directly connected to the wire feed motor 1, this generated voltage is compared with a reference voltage 3 by a comparator 4, and the difference voltage is measured by an amplifier 5.
A wire feeding device that amplifies the wire feeding motor 1 by amplifying the voltage at Feeding equipment, etc. were used.

In the above wire feeding device, the wire feeding motor 1
The speed control is performed by changing the reference voltage 3.
As shown in FIG. 3, the reference voltage 3 is generated by separately generating a reference voltage using a Zener diode or the like, and then passing the reference voltage through a variable resistor 5a.
In addition to both terminals 7 and 8, it is common to extract a predetermined voltage from the sliding terminal 8 of the variable resistor and the common terminal 7, and use this as the current command voltage for the reference voltage 3 shown in Figure 2. there were.

However, the temperature characteristic of the above Zener diode is 10mV.
/'C, so the reference voltage is not very stable, and the temperature characteristics of the tacho generator 2 are not very good, so the feeding speed of the welding wire cannot be called constant speed control. Therefore, the welding current was fluctuating,
Particularly in welding ronds, the wire protrusion length was also affected as mentioned above.

Furthermore, in the above-mentioned welding robot, when the wire feeding speed is controlled from the welding robot side, the tachogenerator 2
The generated voltage had to be A/D converted, which obviously resulted in a costly amplifier.

The present invention aims to solve the above-mentioned drawbacks and to feed welding wire at a desired speed without being affected by disturbances. In a welding wire speed control device that detects the speed of the welding wire and automatically controls the feeding speed of the welding wire by comparing the detected speed with a target speed, the speed of the welding wire is measured by a digital tachometer. The present invention provides a welding wire speed control device.

Here, the digital rotary needle refers to a device that generates pulse signals by rotating, such as a rotary pulse encoder.

Next, embodiments embodying the present invention will be described with reference to the accompanying drawings starting from FIG. 4 to provide an understanding of the present invention.

Here, FIG. 4 is a plan view of a wire feeding device constituting a welding wire speed control device according to an embodiment of the present invention, and FIG.
FIG. 6 is a side view of a wire feeding device constituting a welding wire speed control device according to another embodiment of the present invention, and FIG. 7 is a welding wire speed control according to the above embodiment. FIG. 8 is a block diagram showing a part of the control system of a welding wire speed control device according to another embodiment.

As shown in FIGS. 4 and 5, the welding wire 9 is pressed between a pressure roller 10 and a feed roller 11 from above and below. The feed roller 11 is connected to a wire feed motor 14 via a reducer 13 fixed to the casing 12, and a rotating shaft (not shown) of the wire feed motor 14 has a rotation speed of the wire feed motor 14. A rotary pulse encoder 20 that calculates is directly connected. The pressure roller 10 is rotatably supported by a support member 23 via a pin 24, and one end of the support member 23 is connected to the casing 1 via a pin 21.
A pressure spring 22 is disposed at the other end of the support member 23 to move the welding wire 9 to the feeding roller 1.
It has a structure in which it is compressed to 1. In addition, the above-mentioned welding wire 9
The pressurizing force can be adjusted using a pressurizing amount adjustment knob 25.

Further, the welding wire 9 is guided by conduits 15 and 16, which are guide pipes for the welding wire 9, to a wire clamping pressure section 19 composed of the pressure roller 10 and the feeding roller 11. and 18 to the casing 12.

In the welding wire feeding device 26 described above, the feeding speed of the welding wire 9 is adjusted by detecting the rotational speed of the wire feeding motor 14 that drives the feeding roller 10. As shown in the wire feeding device 29,
A detection roller 27 connected to a rotary pulse encoder (not shown) and a pressure roller 28 that presses the welding wire 9 against the detection roller 27 may be provided separately from the wire feed roller 11 and the like. In the welding wire feeding device 26, if the welding wire 9 and the feeding roller 11 slip, the rotary pulse encoder 2o will be exposed to the welding wire, 9
Although it does not match the feeding speed of the above welding wire feeding device 2,
9, it is possible to accurately detect the feeding speed of the welding wire 9 even if the feeding roller 11 and the welding wire 9 slip. The wire feeding device 29 as shown in FIG.
This is particularly advantageous when large loads are applied to the welding wire 9 being pulled out.

Next, a control circuit for the welding wire feeding device 26 will be explained.

As shown in FIG. 7, a counter 30 counts the output of a rotary pulse encoder 20 directly connected to the rotating shaft of the wire feed motor 14. The counter 30 includes a timer circuit 32. which generates pulses at a constant period T. The value of the register 31 is cleared by a pulse signal that is generated after a delay of T9 time (time set by the delay circuit 32) from the pulse signal from the pulse signal, and the value of the register 31 is is configured to always represent the wire feed rate. The value of the register 31, which is a temporary storage memory, is input to the CPU 33, which is an arithmetic processing unit. A keyboard 36 for inputting a set welding current value is connected to the CPU 33 via an interface circuit 35, and further stores the relationship between the welding current and wire feeding speed, which changes depending on the diameter of the welding wire and the wire protrusion length. A memory 34 that calculates the wire feed speed corresponding to the data table and the previously input set welding current value based on the data table and stores the obtained welding wire feed speed as a set value, and a CPU 33
A ROM 39 containing a program for operating is connected.

The output of the CPU 33 is connected to an amplifier 38 via a D/A conversion circuit 37, and the output of the amplifier 38 is connected to the motor 14.

Next, the operation of the welding wire speed control device according to the above embodiment will be explained.

When the wire feed motor 14 is driven, the feed roller 11 is driven via the speed reducer 13, and the welding wire 9 that has been pinched by the pressure roller 10 and the feed roller 11 is fed. At the same time, a rotary pulse encoder 20 directly connected to the rotating shaft of the wire feed motor 14 generates a predetermined pulse signal.

This pulse signal is counted by the counter 30, and the counter 30 is cleared by the timer circuit 33 at the time when the pulse signal generated at a fixed period is delayed by the time Tg set by the delay circuit 32, and this clearing operation is completed. The count amount accumulated for T2 hours just before is stored in register 3.
1, the output of the rotary pulse encoder 20 counted within time T2 is input to the register 31. Therefore, the number of pulses within these 19 hours corresponds to the feeding speed of the welding wire 9.

The CPU 33 stores a register 3 corresponding to the wire feeding speed.
1 and the set value stored in the memory 34, and if there is a difference, the D/A conversion circuit 37 and the amplifier 38
is output to the motor 14 to drive it, and is controlled so that the difference becomes zero.

This allows the wire feed motor 14 to always match the wire feed speed with the set value stored in the memory 34.
is driven, the rotational speed of the wire feed motor 14 is kept constant, and the welding current value is also kept constant.

In the above embodiment, the number of pulses of the rotary pulse encoder 20 within a certain period of time was counted, but as shown in FIG.
0. using the rotary pulse encoder 20. The signal pulse at the output of register 31. In addition to the load pulse signal of 1. through the delay circuit 32a. A pulse signal delayed by T3 time is generated, and this is sent to the counter 30.
Clear pulse of the counter 30. It is also possible to detect the rotational speed of the motor 14 by counting short-cycle pulses generated by the pulse generation circuit 40. In this case, a rotary pulse encoder 20 with one pulse per revolution. Since it uses , it has the advantage of lower manufacturing costs.

As described above, the present invention provides a welding wire speed control device that detects the speed of the welding wire to be fed and automatically controls the welding wire feeding speed by comparing the detected speed with a target speed. This welding wire speed control device is characterized in that the speed of the welding wire is measured by a digital tachometer, so the welding wire is fed at a constant speed without being affected by external conditions such as temperature. Therefore, if the diameter of the welding wire and the nozzle protrusion length are constant, the welding current is uniquely determined and stable welding can be performed, especially in welding where the wire protrusion length is controlled by the welding current. In robots, the wire protrusion length can be maintained constant, so stable welding without welding defects or excessive or insufficient leg length can be expected. Furthermore, when controlling the wire feed speed from the welding robot, a digital tachometer is used to detect the welding wire feed speed, eliminating the need for an A/D conversion circuit, simplifying the circuit and reducing costs. You can try to bring it down.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between wire melting and consumption rate and welding current for various wire diameters, Fig. 2 is a block diagram of a conventional wire feeding device, and Fig. 3 is a connection for generating a dynamic reference voltage. 4 is a plan view of a wire feeding device constituting a welding wire speed control device according to an embodiment of the present invention, FIG. 5 is a side view of the same, and FIG. 6 is another embodiment of the present invention. FIG. 7 is a block diagram showing the control system of the welding wire speed control device according to the above embodiment, and FIG. 8 is another embodiment. FIG. 2 is a block diagram showing a part of the control system of the welding wire speed control device according to the invention. 1 (Explanation of symbols) 9...Welding wire 20...Rotary pulse encoder (digital rotating needle) 33...CPU 34...Memory. Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Takeyu Honjo 2 + u1 field / utsu III WWITIJ Fumio - Figure 4 Figure 7 Figure 5 Figure 6 Figure 8 + O

Claims (1)

[Claims] In a welding wire speed control device that detects the speed of the welding wire to be fed and automatically controls the feeding speed of the welding wire by comparing this detected speed and a target speed, the speed of the welding wire is digitally rotated. A speed control device for a welding wire, characterized in that the speed is controlled by a meter.