TWO-STAGE WELDING MACHINE AND METHOD TO OPERATE THE SAME
The invention relates to the technique of electric arc welding, and more particularly, to an electric arc welder having a two-stage or two-mode operation and to a method performed by this two-stage electric arc welder. .
Incorporation by Reference - As background information, the pending United States patent application, above, serial number, 866,358 filed May 29, 2001 together with the references incorporated by reference in this application are thus incorporated by reference . Kawai 4,889,969 shows a switch for switching between DIP welding and pulse welding and is incorporated as a reference as background technology.
BACKGROUND OF THE INVENTION Electric arc welders of the GMAW type are often driven by a high speed switching power supply, or power source with a controller to control the current waveform of the welding process. The Lincoln Electric Company of Cleveland, Ohio has pioneered the concept of an electric arc welder with a wave former to control the shape of the waveform of the current during each cycle by using high frequency current pulses , the magnitude of each impulse that is controlled by a pulse width modulator. In these welders, the waveform of the current that exactly controls to perform various welding processes such as pulse welding, constant voltage welding, spray welding, pulse welding, short arc CV welding and STT welding. In these processes, the waveform for each welding cycle is controlled by the impulse width modulator to produce a series of welding cycles that perform a designated process. These arc welding machines are quite versatile; however, they are operated in a selected mode by controlling the impulses created by the waveform former.
The Invention The present invention relates to an electric arc welder, of the type mentioned above, wherein the controller moves between two distinct and separate welding processes, or welding modes. According to the invention, the pulse generator or pulse generator forms a series of pulses forming a first welding process. The controller is movable to perform a second welding process by implementing a series of different impulse forms that constitute a different mode of operation. When counting the cycles in the first mode of operation, the first process is completed and the second process is started. Subsequently, the cycles of the next process are counted until they reach a set number, which indicates that the welder is going to move back to the first welding process. In this way, the electric arc welder has the ability to
perform two separate processes of. welding when changing or 'switching the controller from one mode of operation to another mode of operation. Through this unique two-stage or two-stage operation of an electric arc welder, the welder can perform a welding operation of
alternative way using a first process and then a second process. By. For example, a high-energy process is carried out for a short time and then the welding is converted to a low-energy welding process. If both processes are STT, low STT cycles are implemented
energy, followed by implementation of high energy 'STT cycles. In this way, in one modality, the first process is a high energy process and the second process is a low energy process. A counted number of cycles of each process in the welding process is used to make a
total welding operation by serially implementing the first and second welding processes. As an example, in a specific modality, the first process is a constant voltage spraying process with high heat. The second process is a low heat welding process or GMAW. In the welding operation, the controller implements the first process for several cycles and then the second process for several cycles. In one embodiment of the invention, the first process is a pulse welding process where the pulses have high or high energy. hot. This is used in sequence with a welding process. STT of low heat during several cycles. By alternating between pulse cycles and STT cycles, a total, desired welding operation is performed. In another embodiment, the first process is a pulse welding process that has high heat. This process is alternated with a second welding process, which is a welding process, of constant voltage, of short arc. In a still further embodiment, the first welding process is a pulse process with high heat. The second welding process is a series of pulses where the energy of the pulses is determined by a closed loop feedback of the power exerted. An even further example of the invention is a "mode where the first series of pulses in the pulse welding operation are positive to the electrode to give high heat." The second series of pulses in the pulse welding process are negative, which they comprise constant voltage pulses of "electrode. By moving between these two welding processes, the actual welding operation is controlled to optimize the performance of the welder. According to yet another aspect of the invention, the first welding process of this two-stage or two-stage electric arc welder is a pulse welding process. This process is continued until the arc voltage indicates a short circuit. Then, the two-stage welder is changed to a short, clean welding process, such as a STT welding cycle. In the preferred embodiment, the signal to change from the pulse welding process is not only dependent on the indication of a short by a fall in the arc voltage, but also on the timing of a timer. The control of the electric arc welder moves from the first welding process of the pulse mode in a short cleaning process only when the short is held for a set time. The timer is preferably set to indicate that the short is maintained for at least 1.0 ms and preferably more than a set time in the range of at least 0.2 to 0.5 ms. Consequently, only when there is a real short, instead of an incipient short, the electric arc welder switches to the second welding process to clean the detected short circuit. According to the present invention, an electric arc welder is provided which includes a high speed switching power supply with a controller to create a first and second welding processes through the separation between the work piece and the wire welding that advances towards the work piece. The first process uses a first waveform of current and the second process uses a second waveform of current. A circuit is used for the change between the first and second welding processes, wherein the circuit includes a counter for counting the waveforms in the first and second processes. The welder changes from the process that is processed to the other welding process when the count of the waveform of the welding process being processed reaches a pre-selected number for each welding process. By using this two-stage welder, the arc welder can be moved between two separate and different welding processes according to the count or other parameter. According to another aspect of the invention, there is a welding machine Two-stage arc of the type that includes a high-speed switching power supply with a controller to create a pulse wave welding process and a welding process to clean a detected short. A circuit is activated to create a short signal when the arc voltage is below a value indicative of a short and there is a switch to change the controller from the impulse wave process to the short-cut process by a signal of process change created in the creation of the short signal. In an aspect of the invention, the two-stage welder includes a timer to create a change signal only when the short signal is held for a given time, which is defined as greater than about 1.0 ms and, preferably, greater than a time set in the general range from 0.2 to 0.5 ms. Accordingly, when the short is maintained for a preselected time, the two stage welding is changed from the pulse operation mode to a short cleaning operation mode. In the preferred embodiment, the short cleaning operation mode is a STT welding process. In accordance with yet a further aspect of the invention, there is provided a method for operating an electric arc welder of the type that includes a high-speed switching power supply with a controller. This controller creates a first and second welding process through a separation between the work piece and the welding wire that advances towards the work piece by a wire feeder. The first process of the method has a first current waveform. The second process has a second waveform. The method comprises the change between the first and second welding processes and is implemented by counting the waveforms in the first and second processes. He . The welding process that is carried out is changed or moved to the other process when the account of the waveform of the process that is carried out reaches a selected number. In a further aspect of the present invention, there is provision of a method for operating an electric arc welder that includes a high speed switch and power supply with a controller to create a pulse wave process and a welding process. short cleaning. The method comprises creating a short signal when ... the arc voltage is below a value indicative of a short and then moving or changing the controller from the impulse wave process to the short-cut process by a signal of change created in the short circuit detection. In this method, the change signal is created only when the short signal is maintained for a given time which in practice is less than 1.0 ms and currently in the general range of 0.20-0.50 ms. The main object of the present invention is the provision of a two-stage electric arc welding that alternatively performs two welding processes during a single welding operation. Still another object of the present invention is the provision of a two-stage arc welder, as defined above, arc welder having a counter for counting the cycles of a process to determine when a change in the process is to be made. which is done by the welder. Still a further object of the present invention is the provision of a two-stage arc welder, as defined above, a two-stage arc welder that performs a pulse welding process until a non-incipient short is detected. Then, the two-stage welder is changed or moved to a second operating mode to clean the short. Another object of the present invention is the provision of a method for operating a two-stage arc welder, as defined above. Even a further object of the present invention is the operation of a two-stage arc welder, as defined above, two stages comprising one of many combinations of a first different welding process and a second, different, welding process. The two processes alternate back and forth during a single welding operation. These and other objects and advantages will become apparent from the following description taken in conjunction with the accompanying figures.
Brief Description of the Figures Figure 1 is a combined wiring and block diagram illustrating the preferred embodiment in the two-stage arc welder of the present invention; Figure 2 is a flowchart in the block diagram format and an operating method for the two-stage arc welder, whereby a non-incipient short detected changes the welding process that is performed; Figure 3 is a flow chart in the block diagram format showing a further implementation of the two-stage weld, constructed in accordance with the present invention; and Figure 4 is a current graph that: illustrates the operation of two-stage welding according to the implementation of the invention illustrated in Figure 3.
Preferred Modalities' Now with reference to the Figures, where exposures are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting the same, Figure 1 shows a new two-stage welder A with a source 10 of power or power comprising a high-speed switching power supply illustrated as the inverter 12 which. it has a three-phase power supply input 14 converted by the rectifier 16 to a DC rail in the lines 20, 22. The output winding 30 of the inverter 12 is the primary winding of the transformer T having a secondary winding 32 for supplying current to a rectifier network 40. This network provides a current level through the positive conductor 42 and the negative conductor 44. A small, standard inductor 50 is connected to a standard contact tip 54, through which a welding wire 60 which forms the electrode E separated from the work piece W to define an arc separation through which the current is passed during the arc welding process. The welder A performs many types of electric arc welding by passing a current in a preselected manner through the gap between the electrode E and the work piece. As the arc melts the wire 60 and the work piece W to perform a welding operation, the wire feeder 100 pushes the wire from the spool 102 at a speed (FS) determined by the rotational speed of the motor 104. This speed is it reads by a feedback tachometer 110 and is controlled by the input voltage to the pulse width modulator 112 from the output of an error amplifier 114. This amplifier has a first input 120 which is the voltage representing the desired wire feed speed (WFS). This speed can be controlled by an analog circuit, or more appropriately, from a lookup table of the waveformer 180. The input voltage 120 determines the speed of the motor 104, actual speed that is monitored by the tachometer 110 by comparison with the voltage on the line 120. The feedback of the actual speed is the voltage on the input line 122. In this way, the wire feed speed is coordinated with the welding process that is implemented by the welding A. The shape of the current wave through the electrode E and the work piece W is determined by the controller 130- the computing program of the type including a computational program pulse width modulator 132 for generating a voltage on the output control line 134 at a pulse rate determined by the set frequency of the oscillator 136. Thus, the High frequency pulses on line 134 are controlled by the voltage on line 140, voltage which is the output of a second error amplifier 150 having a first input controlled by bypass 152 - of perception or current detection. The voltage on line 154 is representative of the arc current of the welding process. A signal of order in line 160 is compared to the actual arc current represented by the voltage on line 154 to cause the pulse width modulator 132 to follow the desired waveform of waveformer or generator 180 by way of order line 160 . The wire feed speed to the error amplifier 114 is also directed from the wave generator or generator. The generator 180 is of the synergistic type so that both the signal 160 of order and the signal or voltage of the wire feed speed (WFS) on line 120 are coordinated. According to the new appearance of welding A, a switch 190 is provided which, in practice, is a counting program switch having one. first position 192 and a second position 194, as shown in Figure 1. When in position 192, waveformer 180 is controlled by order line 182 according to a first Process A of control system 200 process for Process A. In this way, the process control system 200 is connected to the synergistic wave former 180 to implement Process A of the wave former 180 by means of the controller 130. Similarly, when the switch 190 is at position 194, the process control system 202 through the command line 182 causes the wave former 180 to implement the second Process B by means of the signal on the command line 160. In this way, by changing the switch 190 between the positions 192, 194, two welding processes are performed - separated by the welder A. Of course, it is within the present invention to make the switch 190 with more than two positions so that The welding machine can process more than two welding processes in sequence or in series, if this operation is desired. In practice, it is preferred that only two separate welding processes are performed alternatively by the welder A. In accordance with another aspect of the invention, the position of the switch 190 is controlled by the logic circuit on the dotted line 210 from the 212 counter output of cycles. The counter counts each cycle during either Process A or Process B. At the end of the count, as set by the account selector 214 or the account selector 216, the logic circuit on line 210 changes the switch 190 to the other position to implement the other welding process. Counter 212 counts a CA number and then changes to Process B which is maintained until the counter counts a CB number. Then, the switch 190 changes back to the first process, that is, Process A. In the preferred embodiment, one of the processes is a high heat process and the other is a low heat process. The numbers CA and CB are essentially the same. In this way, the welding operation comprises a portion of low heat and a portion of high heat that are implemented repetitively during the total welding process to control the performance of the welding operation whether it is STT, pulse or otherwise. As will be shown, several welding processes can be alternatively selected by a counter. In reality, welding A can be interactive so that the change from one process to the other is determined by parameters as distinguished from account numbers. For example, the voltage sensor 170 produces a voltage at 172 that detects a short, which is used in Figure 2 for the transition between the first Process A and the second Process B, wherein the second process is a process for cleaning arc. The accounts can be drastically different and the interactive parameters can be selected to switch to a preselected process after transitions to a given process in a detectable welding condition. In practice, Process A is usually a high energy process and Process B is a low energy process. The CA and CB account numbers are essentially the same. To change the welding operation, the CA number is increased or the CB number is decreased to increase the heat during the welding operation. Similarly, to decrease the heat, the CA number is decreased or the CB number is increased. Of course, combinations can be used. of these increases or decreases when selecting the desired total heat during a welding operation. In a preferred embodiment, Process A and Process B are the same, but with waveforms of different sizes. They can be welds of. impulses or welding STT. However, according to the invention, the processes can be completely diverse. For example, in practice, Process A is a constant voltage spraying process with high heat and Process B is a low heat process G AW of impulses. The controller 212 is set by the count selectors 214, 216 to the total heat desired for the welding operation. In practice, Process "A is a high-heat pulse welding process while Process B is a STT welding process with a lower wire feed speed. Also, in practice, Process A is a pulse welding process with higher heat and Process B is a short arc constant voltage process. An even further implementation of the present Process A of the invention is a pulse welding process and Process B is a closed loop control process, such as a process wherein the current is controlled by the power or output power. Even a further implementation of the present invention is where Process A is a positive, pulse electrode welding process and Process B is a constant, negative electrode voltage welding process. In this implementation of the present invention, a polarity switch is added in the output circuit before the inductor 50, polarity circuit which is changed at the same time as the switch 190. Others. implementations of the present invention comprise various combinations of the welding process to perform the desired total welding operation. An interactive control system 220 schematically illustrates Figure 2, wherein the waveform generator and the control 222 create the voltage on the control line .134, as previously described. The control 130 is in block 222. The voltage controls the power supply 12 which is monitored by a process control network 224 together with the voltage on line 172 of the voltage sensor 170, shown in Figure 1. The timer 226 of the process control network is set to a time generally greater than about 1.0 ms and preferably greater than a set time in the general range of 0.2-0.5 ms. The output of the timer network is a logic circuit on line 232 addressed to a decision block 230 to decide whether or not there is a short circuit that has been detected for a time greater than the set time of time 226. The position of the switch 190 is controlled by the decision block 230. When there is a short that exceeds the set time of the timer 226, the switch 190 moves to the position 194. In this way, when there is a non-long-term excipient short, the switch 190 changes to the alternative position 194 to implement the second process of welding. In this implementation of the present invention, the first process is a pulse waveform controlled in accordance with the waveform determined by a system shown as block 240. Block 242 represents a system for creating a STT waveform or other short cleaning welding process. The system 220 performs the first stopped operation mode as an impulse waveform controlled by the system represented by the block 240. Whenever there is a short, the voltage on the line 172 falls below a threshold. This determines a short circuit. This detected condition is synchronized by the timer 226. If the time of the short exceeds the set time of the timer, the logic circuit on line 232 indicates to the block the decision that there is a real short circuit, not incipient. This logic circuit immediately shifts the counting program switch 190 to the arc cleaning welding process, indicated as a STT process. When the short is cleaned according to the short cleaning process, the voltage on line 172 immediately changes to an arc voltage or plasma level. This is above the threshold and causes the decision block 230 to change the switch 190 to the position 192 for implementation of the impulse waveform controlled by the system represented by the block 240. Accordingly, the system 220 does not comprise a cycle counter, but instead perceives a welding parameter for the actual change of the welding process from one welding process to another. This occurs rapidly and "occurs whenever the selected parameter is detected." In Figures 3 and 4, system 250 is illustrated schematically where the waveform generator and control 180 create the voltage on control line 134. As previously described, the voltage controls the power supply 12 which is monitored by the GMAW or FCAW welding process 252. The system 250 includes a low heat welding process represented by block 260. Process A is a process low heat STT welding process. Similarly, a high heat STT welding process is represented by block 262. Counter 212 causes the first STT 260a pulses to be processed as shown in Figure 4. After the counted the desired number of STT pulses 260a by cycle counter 212, switch 190 is changed to position 194 by the logic circuit on line 210. This generates large STT or high heat pulses , 262a, as shown in Figure 4. These high heat pulses are counted according to the number selected for counter 212. In this way, the number of waveforms per cycles of high and low STT is adjusted to determine the total heat during a welding operation. The invention comprises a welder of two or more stages that implements in sequence differently different welding processes. Preferably, the duration of these processes is determined by a counter; however, a parameter can be used to switch between welding processes. Only the representative processes have been analyzed and other welding processes can be used when the invention is implemented.