JPS5828704Y2 - automatic welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic welding device, and more particularly to an automatic welding device that achieves a welding operation by automatically controlling the positions of a torch and a workpiece relative to each other by a control device.

2. Description of the Related Art Conventionally, automatic welding apparatuses have been put into practical use for the purpose of labor saving, for example, in arc welding, which automatically controls the position of a torch button and/or a workpiece to be welded (hereinafter referred to as a workpiece) so as to be moved automatically.

In such automatic welding equipment, the torch or workpiece is automatically moved even if the torch does not spark due to welding debris (spatter) adhering to the tip of the torch or a short circuit between the torch and the workpiece. , there was a problem of weld leakage.

Therefore, the present applicant has previously proposed an automatic welding device configured to solve these problems.

This interesting automatic welding device was invented in 1986.
No. 4434 (Utility Application No. 50-34802), the outline of which is an automatic welding device including a control means for controlling the mutual positions of a torch and a workpiece, a command means for commanding a welding operation, and a command means for commanding a welding operation. , a first detection means for detecting a predetermined current flowing through the torch, a second detection means for detecting a predetermined voltage between the torch and the workpiece, and an output of the command means and the first detection means. The automatic welding apparatus includes logic means for detecting a mismatch between the output and/or the output of the casing or the second detection means, and controls the control means in response to the output of the logic means.

Even with such an automatic welding device, the following drawbacks remain to be solved.

Generally, the welding current does not suddenly reach a predetermined value in response to a welding command, but chattering occurs at the time of startup or initial excitation.

Furthermore, during welding operation, even if the welding current is normal, the current may be interrupted momentarily due to oil, dirt, etc., for example.

This is the same situation in the case of temporary attachment.

In other words, in the automatic welding apparatus described above, the control means is controlled in immediate response to such transient changes (chattering) during startup, instantaneous changes caused by tacking, etc., and, for example, an alarm is activated. It lingers on.

However, such a transient or instantaneous change should return to normal after a certain amount of time has elapsed, and in such a case, an alarm is not necessary.

Therefore, the main objective of this invention is to provide an automatic welding device that can overcome the above-mentioned particular drawbacks.

To summarize, this invention is an automatic welding device that generates a control signal such as an alarm only when the normal state is not restored even after a certain period of time has passed since the welding current stopped changing.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 1 is an electrical circuit diagram showing an embodiment of this invention.

In terms of configuration, the welding device WD has a torch T.

A required voltage is applied to this torch T and a workpiece (not shown), and a welding current flows therebetween.

The welding current flowing through this torch T is indicated by an ammeter AM.

Further, the welding current is converted into a small current proportional to the welding current and led to the rectifier circuit REC via the current transformer CT.

The output voltage of this rectifier circuit REC is the smoothing capacitor FC
and another resistor, the transistor TR
given as pace input.

The collector of this transistor TR is connected to a positive voltage +VC via a series circuit of a resistor and a photodiode PD1.

The photodiode PDI, together with the phototransistor PTl optically coupled thereto, constitutes a photocoupler PCI.

Then, the collector of the phototransistor PTI is connected to a positive voltage +
Connected to Vcc.

Moreover, the emitter of this phototransistor PTI is similarly grounded by a twisted cable to the outside of the welding device WD.

The photodiode PD2 and the phototransistor PT2 optically coupled thereto constitute a photocoupler PC2.

The collector of the phototransistor PT2 is connected to the positive voltage terminal Vcc via a resistor, and is also applied to one input of an AND gate G, which is further connected to a retriggerable monostable multivibrator (hereinafter simply referred to as "monostable multi") RMM.
is applied to the trigger input T of .

The emitter of this phototransistor PT2 is grounded.

The monostable multi-RMM is triggered in response to the rising edge of the trigger input T and delivers a pulse at the output Q at a time τ after being triggered.

A welding command WELD from a command means (not shown) is applied to the other input of the controller G, and its output is applied to the setting manual of the D-type flip-flop DF.

The D-type flip-flop l)F, in response to the rise of its trigger force T, reads the state of the set force and derives an output Q as a control signal.

The above configuration+KJ=h(', its operation will be explained below with reference to FIG. 2.

FIG. 2 is a waveform diagram of each part explaining the operation of the embodiment shown in FIG.

In the operation, it is assumed that a welding command WELD is derived from a welding control circuit (not shown) at time t1 as shown in FIG. 2a.

In response, the welding device WD is activated, and after a device-specific delay time t has elapsed, welding current begins to flow through the torch T at a time t2, as shown in FIG.

This welding current is given to the rectifier circuit RFC by the current transformer CT, but since it is at the time of starting at this time, a sufficient current is not obtained immediately and becomes a steady current at time t3 with repeated chattering.

Therefore, the transistor TR changes accordingly from time t2 to t.
The on/off is repeated at 3'E, and the ON state continues until time t3.

When the transistor TR is turned on, a current flows through the photodiode PDI constituting the photocoupler PC1, and the diode PDI emits light.

In response, the phototransistor PTI constituting the photocoupler PC1 is turned on, and the photodiode PD2 constituting the photocoupler PC2 emits light.

When the photodiode PD20 emits light, the phototransistor PT2 optically coupled thereto is turned on.

When the phototransistor PT2 is turned on, its collector is forced to the ground potential and falls to a low level (hereinafter referred to as "L").

The state of point A on the collector of this phototransistor PT2, that is, the welding state signal, is shown in FIG. 2C.

The welding condition signal at point A shown in Fig. 2C is a monostable multi-R
It is applied to the trigger input T of the MM and the AND gate G.

It is triggered every falling edge of the trigger input T and delivers a pulse of time τ to the output Q.

In other words, as shown in Fig. 2d, the output Q of the monostable multi-RMM is at the level (hereinafter referred to as rHJ).

At the falling edge of the output Q at time t4, the D-type flip-flop DF is triggered. It is.

Therefore, the output Q of this D-type flip-flop DF, that is, the control signal, is rLJ's it.

Therefore, the welding control circuit to which this control signal is applied does not generate any alarm, and the welding operation is not interrupted.

After that, at time t5, it is assumed that the welding current flowing through the torch T is momentarily interrupted due to oil, dirt, or the like.

At this time, the welding state signal at one point A of welding current and the output Q of the monostable multi-RMM are shown in Fig. 2 and Fig. 2 C, respectively.
1 It becomes as shown in Fig. 2 d.

Here, the monostable multi-RMM at time t6 shown in FIG.
In response to the falling of the output Q of the D-type flip-flop DF
is triggered.

However, even at this time t6, the above-mentioned time t
As in case 4, the setting force for the D-type flip-flop DF is up to rLJ 1, and the control signal is rLJ 11.
It is.

Then, at time t7, for some reason, the torch T
Assume that the welding current flowing through the welding current is cut off and then continues in that state.

At this time, as shown in Fig. 2d, the button is pressed at time t7 (the rise of the welding signal at point A), the monostable multi-RMM is triggered, and the output Q7 = EI at t8t for a period of time τ. H”.

In response to the fall of the output Q at time t8, the D-type flip-flop DF is triggered.

At this time, as can be seen from button a in Figure 2 and button C in Figure 2, the two-man power of the ANDGATE is rHJ, and D
The setting force of the type flip-flop DF is "H".

Therefore, at time t8, rHJ is read into the D-type flip-flop DF, and its output Q and therefore the control signal are set to rHJ.

This rHJ control signal is given to the welding control circuit.

In response, for example, an alarm is generated and, for example, the welding operation is interrupted.

In addition, in the above embodiment, in order to prevent undesired interruption of the welding operation due to transient changes, the retriggerable monostable multivibrator RMM was used to determine the time. The method is not limited to this, and any time-limiting means may be used.

As described above, according to this invention, it is possible to prevent weld leakage by automatically detecting an undesired state of the torch, stopping the automatic position control of the automatic welding device or issuing an alarm, and instantly An automatic welding device that does not respond to target or transient changes (that do not degrade welding quality) is obtained.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing an embodiment of this invention. FIG. 2 is a waveform diagram of each part for explaining the operation of the embodiment of FIG. 1. In the figure, WD is a welding device, T is a torch, PCI, P
C2 is a photocoupler, RMM is a retriggerable monostable multivibrator, G is an AND gate, and DF is a D-type flip-flop.

Claims (1)

[Scope of utility model registration request] (1) An automatic welding device that automatically controls the positions of a torch and a workpiece relative to each other in response to a welding command signal to automatically achieve a welding operation, wherein welding is performed in accordance with a welding current of the torch. means for generating a welding state signal representative of what is actually being done; time-limiting means for deriving a fixed time output in response to erasure of said welding state signal; and when said fixed time period has elapsed, said welding command control signal derivation means for deriving a control signal when welding is not performed even after a certain period of time of 1 has elapsed based on the welding state signal and the welding state signal; logic gate means for deriving an output when the welding state signal is absent; and state storage means for reading the output of the logic gate means in response to the output of the time limit means, the output of the state storage means being used as a control signal. Automatic welding equipment designed to (section) The automatic welding apparatus according to claim 1 or 2, wherein the time limit means is a retriggerable monostable multivibrator.