JPS63126674A - Power source for welding - Google Patents

Abstract

PURPOSE:To reduce the occurrence of spatters by inputting a pulse fall period signal and a clock signal and turning a switching element ON-OFF by theoretical product of said two signals to control easily the fall speed of a pulse current. CONSTITUTION:A pulse period command signal Tp from a welding output controlling element control circuit part 12 is outputted to a pulse fall period detection circuit part 13. The fall period detection circuit part 13 outputs a pulse fall period signal Tpf which is of an H level only in a period from the fall starting of the pulse current until the falling to a prescribed current value and of an L level in other periods by said Tp signal and a welding current value detection signal Aw from a shunt 7. The Tpf signal is inputted to a switching element driving circuit part 15 and the theoretical product of said Tpf signal and a clock signal Ck from a clock generation circuit part 14 where a time ratio of the H - L levels can be set optionally is calculated and afterward, the switching element 16 is turned ON - OFF. The switching element 16 is turned ON synchronizing with the H level of the clock signal Ck only in the fall period of the pulse current.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is used to control the pulse current fall rate of a pulsed arc welding power source that applies welding output in a pulsed manner to cause welding wire to transfer in a sprayed manner. This relates to a welding power source.

Conventional Technology The conventional technology for controlling the falling speed of pulse current is to adjust the number of turns of a welding reactor.

Problems to be Solved by the Invention In the conventional method of adjusting the number of turns of a welding reactor, the connection of the reactor must be changed every time the falling speed of the pulse current is changed, resulting in a problem with specific efficiency. However, unless the pulse current fall rate is changed depending on the type of welding material and welding speed, good bead appearance and spatter generation suppression effect cannot be obtained.

In addition, with welding power supplies that have a fast fall rate and a small inductance of the welding reactor, there is a problem with the responsiveness of the control circuit, which causes ripples at the peak of the pulse current, which inhibits smooth spray transfer. There was a problem with the generation of arcing noise. Therefore, the current situation is that conventional welding power sources are supplied to the market with the number of turns of the welding reactor set so that these problems do not significantly occur.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention inputs a pulse period command signal that commands the period from the start of the rise to the start of the fall of the pulse current, and a detected value signal of the welding current. a pulse falling period detection circuit section that outputs a pulse falling period signal that is at an H level during a period from the start of a current fall until the current falls to a predetermined current value, and is at an L level during other periods;
A clock generation circuit section outputs a clock signal that can arbitrarily set the time ratio of the H-L level, and the above-mentioned pulse falling period signal and the above-mentioned OFF signal are input.
It is equipped with a switching element drive circuit section that turns the switching element ON and OFF based on the AND of signals, and a control winding provided on the same core as the welding reactor is connected in parallel to the switching element via an impedance element. By the means described above, the control winding of the welding reactor is connected to the impedance element by the switching element only during the falling part of the pulse current and during the period when the clock signal is at the H level, so that the inductance is small. Therefore, the welding current fall speed becomes faster. During other periods, the control winding of the welding reactor is open, resulting in a small amount of inductance and a slow rate of fall of the welding current. Therefore, by changing the time ratio of the H-L level of the 0tsuk signal, the time from when the welding current starts falling until it falls to a predetermined current value, that is, the pulse current falling speed, can be easily set arbitrarily. .

Example Embodiments of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, 1 is a welding power input terminal, 2 is a welding main transformer, 3 is a rectifier/smoothing section, 4 is a welding output control element,
6 is a regeneration diode, 6 is a welding power output terminal, 7 is a shunt, 8 is a welding reactor with a control winding on the same core, 9 is a contact tip for energizing, 10 is a welding wire, 11 is a The object to be welded, 12 is a control circuit section of the welding output control element 4, 13 is a pulse falling period detection circuit section, 14 is a clock generation circuit section, 15 is a switching element drive circuit section, 16 is a switching element, and 17 is an impedance element. It is.

The control circuit section 12 of the welding output control element 4 determines the pulse period, pulse width, pulse peak current value, etc. in accordance with the welding material, wire diameter, wire feeding speed, etc., and detects the welding current value from the shunt 7. An ON-OFF control signal is output to the welding output control element 4 by performing shift feedback control using the signal AW.

The welding output control element control circuit section 12 outputs the pulse period command signal Tp to the pulse falling period detection circuit section 13 .

The pulse fall nine period detection circuit section 13 uses the welding current value detection signal Aw from the Tp multiplied signal shunt 7 to keep the pulse current at H level only during the period from the start of the fall of the pulse current until the current falls to a predetermined current value IB. outputs the borrowed signal Tpf for nine periods of the falling pulse, which is at L level.

This pulse falling period detection circuit section 13 is realized by the circuit configuration shown in FIG. 13-1 to 13 in Figure 3
-6 is a resistor, 13-7 is an amplifier, 13-8 is a comparator, 1
3-9 is an AND element, and 13-10 is a logic inversion element. In Fig. 3, the detection signal of the welding current value is transmitted to the amplifier 13-
7, the signal is amplified to a level that can be handled by the control circuit. This value and the comparison level (second
The comparator 13-8 compares the Aw
If the O value is smaller than , L level is output, and if it is a dog, H level is output. The output of the comparator 13-8 and the inverted signal of the pulse period command signal Tp are logically operated by the AND element 13-9, and the AND element 13-9 is operated as shown in FIG.
The pulse falling period signal Tpf of E) is output.

The Tpf signal is input to the switching element drive circuit section 15, and after being ANDed with the clock signal Ck from the clock generation circuit section 14, which can arbitrarily set the time ratio of H-L level, the switching element 16 is turned ON- Since the switching element 16 is turned off, as shown in FIG. 2 CB),
Clock signal Ck only during the falling period of the pulse current
Turns on in synchronization with the H level of As a result, the induced voltage VL generated in the control winding provided on the same core of the welding reactor 8 repeatedly connects and disconnects to the impedance element 17, so when the welding reactor 8 is connected, the inductance amount of the welding reactor 8 is small. If it is opened, the welding current at the falling part of the pulse current will be the value shown in Figure 2 (CA).
It becomes step-like as shown in the figure. Therefore, the H of clock signal Ck
By changing the time ratio of the -L level, the falling speed of the pulse current to the IB level can be freely controlled.

Note that the clock generation circuit section 14 is made of a commercially available type. -I
Since it can be easily realized using C or a microcontroller peripheral IC, a detailed explanation is omitted. Also, the value below the predetermined current value is the third
In the embodiment shown in the figure, the pulse current is set to the value until it drops to the base current value, but depending on the resistance values of the resistors 13-5 and 13-6, the switching element 16 can be turned ON by the clock signal during the base current period. -Can be turned off.

Furthermore, although the main circuit configuration of the welding power source is shown as a secondary chopper type in FIG. 1, it may be a primary inverter set.

Effects of the Invention As described above, according to the present invention, the falling speed of the pulse current can be easily controlled arbitrarily, and when priority is given to the bead appearance, the pulse current falling speed can be made slow, making it easier to perform high-speed welding, etc. When the average arc voltage is lowered, the falling speed of the pulse current can be made uniform, the generation of spatter can be reduced, and a welding power source with a wide range of compatibility can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a welding power source showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part in FIG. FIG. 8... Welding reactor, 12... Control circuit section, 13... Pulse fall 9 period detection circuit section, 14... Clock generation circuit section, 15・・・・・・
- Switching element drive circuit section, 16...Switching element. Name of agent: Patent attorney Toshi Nakao (1 person)
figure

Claims (1)

[Claims] The pulse period command signal that commands the period from the start of the rise to the start of the fall of the pulse current and the detected value signal of the welding current are input, and the period from the start of the fall of the pulse current until the current falls to a predetermined current value is H. a pulse falling period detection circuit section that outputs a pulse falling period signal that is at L level during other periods, and a clock generation circuit section that outputs a clock signal that can arbitrarily set the time ratio of H-L level. , a switching element drive circuit section that receives the pulse falling period signal and the clock signal and turns on and off the switching element by logical product of these two signals, and is provided on the same core as the welding reactor. A welding power source characterized in that a control winding is connected in parallel to the switching element via an impedance element.