Multi-pulse welding method
阅读说明：本技术 多脉冲焊接方法 (Multi-pulse welding method ) 是由 R·弗劳恩舒赫 J·阿特尔斯迈尔 D·索林格 M·穆斯 于 2020-04-09 设计创作，主要内容包括：为了在多脉冲焊接方法中使借助焊接装置(1a、1b)同时执行的至少两个脉冲焊接过程彼此同步而规定,焊接装置(1a、1b)借助通信连接(15)相互连接并且经由通信连接(15)将同步信息(SI)从发送焊接装置(1a)发送给至少一个接收焊接装置(1b)并且在接收焊接装置(1b)中使用该同步信息(SI),以使借助接收焊接装置(1b)实施的脉冲焊接过程与借助发送焊接装置(1a)实施的脉冲焊接过程同步。(In order to synchronize at least two pulse welding processes, which are carried out simultaneously by means of the welding devices (1a, 1b), with one another in a multi-pulse welding method, it is provided that the welding devices (1a, 1b) are connected to one another by means of a communication connection (15) and that Synchronization Information (SI) is transmitted from the transmitting welding device (1a) to at least one receiving welding device (1b) via the communication connection (15) and is used in the receiving welding device (1b) in order to synchronize the pulse welding process carried out by means of the receiving welding device (1b) with the pulse welding process carried out by means of the transmitting welding device (1 a).)
1. Method for synchronizing at least two pulse welding processes for performing a multi-pulse welding method, wherein the pulse welding processes are controlled by a pulse frequency (f)D1、fD2) A welding cycle (SZ1, SZ2) which is repeated periodically and has a pulse current phase and a basic current phase, wherein each pulse welding process is carried out by means of a welding device (1a, 1b), wherein the welding devices (1a, 1b) are connected to one another by means of a communication connection (15) and Synchronization Information (SI) is transmitted from a transmitting welding device (1a) to at least one receiving welding device (1b) via the communication connection (15) and is used in the receiving welding device (1b) in order to synchronize the pulse welding process carried out by means of the receiving welding device (1b) with the pulse welding process carried out by means of the transmitting welding device (1a), characterized in that the transmitting welding device (1a) transmits at least one Synchronization Pulse (SP) as Synchronization Information (SI) to the at least one receiving welding device (1b), the at least one Synchronization Pulse (SP) has a defined time relationship with the welding cycle (SZ1) of the pulse welding process of the sending welding device (1a), and the welding cycle (SZ2) of the pulse welding process of the receiving welding device (1b) is synchronized with the received Synchronization Pulse (SP).
2. Method according to claim 1, characterized in that the receiving welding device (1b) receives the pulse frequency (f) of the pulse welding processD2) Is known in the receiving welding device (1b) or is determined from a known welding characteristic curve.
3. Method according to claim 1, characterized in that additionally the pulse frequency (f) of the welding device (1a) is to be transmittedfD1) Or the pulse frequency (f) to be set by the reception welding device (1b)D2) Is transmitted as Synchronization Information (SI) to the receiving welding device (1 b).
4. Method according to claim 3, characterized in that the pulse frequency (F) obtained by the transmission welding device (1a) is transmitted in the reception welding device (1b) by means of a known frequency divider (F)D1) Determining a pulse frequency (f) to be set by a receiving welding device (1b)D2)。
5. Method according to claim 1, characterized in that the sending welding device (1a) continuously transmits the pulse frequency (f) of the welding device (1a) as Synchronization Information (SI) with Synchronization Pulses (SP)D1) Sent to the receiving welding device (1 b).
6. Method according to claim 5, characterized in that the receiving welding device (1b) determines the pulse frequency (f) of the sending welding device (1a) from the period of the received Synchronization Pulse (SP)D1) And the pulse frequency (F) to be set in the receiving welding device (1b) is determined by means of a known frequency divider (F)D2)。
7. Method according to claim 4 or 6, characterized in that the frequency divider (F) is determined in the receiving welding device (1b) from a known welding characteristic curve of at least one welding parameter and from the pulse frequency (F) of the transmitting welding device (1a)D1) Or matched wire feed speed (v)D) And a frequency divider (F) for determining the pulse frequency (F) to be set by the receiving welding device (1b)D2)。
8. Method according to claim 7, characterized in that the pulse frequency (f) required for the pulse welding process of the receiving welding device (1b) is determined from a welding characteristic curve of the pulse welding processD2) From the desired pulse frequency (f)D2) And the acquired pulse frequency (f) of the transmission welding device (1a)D1) Or phaseWire feed speed (v) of wireD) Determining the frequency divider (F).
9. Method according to claim 8, characterized in that the pulse frequency (f) at the acquired transmission welding device (1a) is set to the next larger or next smaller integerD1) With the desired pulse frequency (f)D2) The ratio between them is used as a frequency divider (F).
10. Method according to any of claims 1 to 9, characterized in that the Synchronization Pulses (SP) are given a phase difference (t) of a predetermined magnitudeP) At the beginning of a welding cycle (SZ1) in a transmitting welding device (1a) and/or at the beginning of a welding cycle (SZ2) in a receiving welding device (1b), with a predetermined phase difference (t)P) Starting after receiving the Synchronization Pulse (SP).
11. Method according to claim 10, characterized in that the phase difference (t) to be set by the receiving welding device (1b)P) Is transmitted as additional Synchronization Information (SI) from the transmitting welding device (1a) to at least one receiving welding device (1 b).
12. Method according to any one of claims 1 to 11, characterized in that the synchronization is started or stopped during the multi-pulse welding method.
13. Method according to any one of claims 1 to 12, characterized in that the pulse frequency (f) of the pulse welding process of the transmission welding device (1a) is determined by means of a pulse-shaped measuring device (1a)D1) Or the pulse frequency (f) of a pulse welding process of a following pulse welding processD2) And/or phase difference (t)P) During the multi-pulse welding process.
14. Arrangement for carrying out a multi-pulse welding method, having at least two welding devices (1a, 1b) designed to carry out at least two pulse welding processes, wherein a pulse welding processBy pulse frequency (f)D1、fD2) Welding cycles (SZ1, SZ2) which are repeated periodically and have a pulse current phase and a basic current phase, the welding devices (1a, 1b) being connected to one another by means of a communication connection (15), and the transmitting welding device (1a) being designed to transmit Synchronization Information (SI) via the communication connection (15) to at least one receiving welding device (1b), the receiving welding device (1b) being designed to use the Synchronization Information (SI) to synchronize a pulse welding process carried out by means of the receiving welding device (1b) with a pulse welding process carried out by means of the transmitting welding device (1a), characterized in that the transmitting welding device (1a) is designed to transmit at least one Synchronization Pulse (SP) which has a defined temporal relationship with the welding cycle (SZ1) of the pulse welding process of the transmitting welding device (1a) as Synchronization Information (SI) to the at least one receiving welding device (1b), and the receiving welding device (1b) is designed to synchronize the welding cycle (SZ2) of its pulse welding process with the received Synchronization Pulse (SP).
Technical Field
The invention relates to a method for synchronizing at least two pulse welding processes for carrying out a multi-pulse welding method, wherein the pulse welding processes are composed of welding cycles that are periodically repeated at a pulse frequency and have pulse current fibers and a basic current phase, each pulse welding process being carried out by means of a welding device, the welding devices being connected to one another by means of a communication connection and synchronization information being transmitted from a transmitting welding device to at least one receiving welding device via the communication connection, and the synchronization information being used in the receiving welding device to synchronize the pulse welding process carried out by means of the receiving welding device with the pulse welding process carried out by means of the transmitting welding device. Furthermore, the invention relates to an arrangement for carrying out the multi-pulse welding method.
Background
The invention relates to pulse welding with a pulsed arc by means of a melting or non-melting welding electrode. In the case of such a welding method, the basic welding current and the pulse welding current increased relative thereto are regularly alternated with one another at a predetermined pulse frequency. During the phase of the basic welding current with the basic welding current, the arc is burnt at low power to keep the weld pool in a liquid state. During the pulse current phase with the pulsed welding current, large droplets of welding wire are formed as weld filler, which eventually strip off and fall into the weld puddle. The welding wire can also be used as a fusion welding electrode, for example in the case of Metal Inert Gas (MIG) welding or Metal Active Gas (MAG) welding, or can be fed to an arc which is burnt between a non-fusion welding electrode and a workpiece, for example in the case of tungsten inert gas (WIG) welding. In the case of WIG welding, the welding method is also commonly referred to as direct current pulse (DC pulse) welding or alternating current tig (WIG ac) welding. Depending on the wire diameter and the material of the welding wire, the wire feed speed and the pulse frequency should be selected and matched to one another in the case of MIG/MAG welding in such a way that a droplet is generated and stripped off at each current pulse. Here, the wire feed speed and the pulse frequency are related to each other. A stable welding process and/or a good welding quality cannot be achieved in case the values of the wire feed speed and the pulse frequency are not properly selected. By means of pulse welding, the heat input into the workpieces can be reduced and controlled, whereby also thinner workpieces can be welded. In addition, a welding result with high quality is obtained by means of pulse welding, for example, as a result of which spatter can be greatly reduced.
In order to increase the welding efficiency, multi-pulse welding methods are also known, for example tandem pulse welding methods, in which case at least two pulse welding methods are operated simultaneously. In this case, preferably at least two welding wires are melted in a common melt pool. However, each pulse welding method can also have its own weld pool. For this purpose, separate welding devices are required for each pulse welding process, i.e. a power supply, a welding torch and optionally a wire feed unit are required. A pulse welding method is realized by each set of welding device. For MIG/MAG, the multiple pulse welding can be operated in such a way that the welding processes are started and operated independently of one another, i.e. the wire feed speed and the pulse frequency are set individually for each welding process. In the case of WIG welding, only the pulse frequency is usually set, but it is also possible to set the wire feed speed of the weld filler. However, this is more time consuming for the welder, since the welding parameters have to be set correspondingly in all welding devices. In addition, possible interactions due to the simultaneously operating welding process have little to no influence, which can reduce the welding quality.
Tandem pulse welding methods with a synchronous welding process are therefore also known, in which case a pulse frequency is predefined for one welding device and the other welding device follows the welding frequency. Thereby, the two welding processes are synchronized with each other and welding is performed at the same pulse frequency. However, in the case of MIG/MAG welding, this may cause problems if the wire of the following welding process is fed at a different wire feed speed than in another welding process, which is usually desired in order to increase the process stability. In the case of WIG welding, a synchronous welding process is also sought. However, lower wire feed speeds generally require lower pulse frequencies as well, since the power balance of the wire feed and the welding current must be coordinated. Therefore, in the case of an excessively large difference between the wire feed speed in the leading pulse welding process and the wire feed speed in the following pulse welding process, it may happen that the following pulse welding process is operated at an excessively high pulse frequency (which is accepted from the leading pulse welding process), whereby a stable welding process may not be achieved or poor welding results (e.g., welding spatters) may be obtained due to the following pulse welding process.
To solve this problem, it has already been proposed in DE 102007016103 a1 that the pulse frequency of the following pulse welding process in the tandem pulse welding method can be set to an integer multiple of the pulse frequency of the leading pulse welding process. The pulse frequency of the two pulse welding processes should be selected such that the pulse current phases do not overlap. But it is not detailed how the synchronization of the two pulse welding processes can be achieved.
Disclosure of Invention
The object of the present invention is therefore to provide a method for synchronizing a plurality of pulse welding processes which are operated simultaneously in a multi-pulse welding method.
According to the invention, the object is achieved in that the transmitting welding device transmits a synchronization pulse as synchronization information to the at least one receiving welding device, the synchronization pulse having a defined temporal relationship to the welding cycle of the pulse welding process of the transmitting welding device, and the welding cycle of the pulse welding process of the receiving welding device being synchronized with the received synchronization pulse.
By means of the synchronization pulse, the receiving welding device is able to synchronize the pulse welding process to be performed with the pulse welding process in the sending welding device to ensure the desired relationship of the two pulse welding processes with respect to each other. In order to prevent the two pulse welding processes from deviating from each other, it is also possible to repeat such synchronization pulses at regular intervals.
The synchronization information required for synchronizing the pulse welding process can thus be transmitted in a simple manner via the communication connection. The synchronization can thus be carried out automatically without intervention by the welder or without setting the welding parameters.
In order to simply carry out the multi-pulse welding method, the pulse frequency of the pulse welding process of the receiving welding device can be known in the receiving welding device or determined from a known welding characteristic curve.
As an alternative, the pulse frequency of the transmitting welding device or the pulse frequency to be set by the receiving welding device can additionally be transmitted as synchronization information to the receiving welding device. In an advantageous embodiment, the pulse frequency to be set by the receiving welding device can be determined in the receiving welding device from the acquired pulse frequencies of the transmitting welding device by means of a known frequency divider. This enables the pulse welding process in the receiving welding device to follow the pulse welding process in the sending welding device.
A further advantageous embodiment is achieved if the transmitting welding device continuously transmits synchronization pulses as synchronization information to the receiving welding device at least during the synchronization period at the pulse frequency of the transmitting welding device, and the receiving welding device determines the pulse frequency of the transmitting welding device from the period of the received synchronization pulses and determines therefrom the pulse frequency to be set in the receiving welding device by means of a known frequency divider. This enables the pulse welding process in the receiving welding device to follow the pulse welding process in the sending welding device.
It is particularly advantageous if the frequency divider is determined in the receiving welding device from a known welding characteristic curve and the pulse frequency to be set by the receiving welding device is determined from the pulse frequency of the transmitting welding device and the frequency divider. The pulse frequency required for the pulse welding process is preferably determined from a welding characteristic curve consisting of the set wire feed speed of the pulse welding process of the receiving welding device, and the frequency divider is determined from the required pulse frequency and the acquired pulse frequency of the transmitting welding device. The pulse frequency of the receiving welding device can therefore be set optimally in consideration of the stored welding characteristic curve, whereby the pulse frequency of the receiving welding device can be set optimally in consideration of the stored welding characteristic curve, whereby the welding process can be taken into account in the determination of the pulse frequency.
It may be advantageous for the multi-pulse welding method to transmit a synchronization pulse at the beginning of a welding cycle in the transmitting welding device with a predefined phase difference and/or to start a welding cycle in the receiving welding device with a predefined phase difference after receiving the synchronization pulse. In this way, a desired phase position of the pulse welding process can be ensured.
Drawings
The invention is explained in more detail below with reference to fig. 1 to 7, which show exemplary, schematic and non-limiting advantageous embodiments of the invention. The attached drawings are as follows:
figure 1 shows an arrangement for performing a multi-pulse welding method,
figure 2 shows a welding cycle in a multi-pulse welding method,
figure 3 shows the synchronization of the pulse welding process by means of a communication connection between the relevant welding devices,
figure 4 shows the synchronization achieved by means of the synchronization pulses,
figure 5 shows a possible welding characteristic of a pulse welding process,
FIG. 6 shows a pulse welding process with an intermediate pulse, an
Fig. 7 shows synchronized switching during welding.
Detailed Description
The invention is explained below with respect to a tandem pulse welding method (i.e., having two pulse welding processes) as an example of a multi-pulse welding method. However, it is naturally also conceivable to expand the following embodiments for a multi-pulse welding method with more than two pulse welding methods. The multi-pulse welding method is distinguished in particular by the fact that at least two pulse welding processes are operated simultaneously, so that in the case of the tandem pulse welding method two pulse welding processes are operated. The multiple pulse welding processes can all operate in the same weld puddle, but it is also possible that different pulse welding processes operate in partially different weld puddles.
One possible configuration for a tandem pulse welding method is schematically illustrated in fig. 1. Two separate welding devices 1a, 1b are provided, each having a power supply 2a, 2b, a wire feed unit 3a, 3b (in the case of WIG welding also no wire feed unit 3a, 3b) and a welding torch 4a, 4 b. The power sources 2a, 2b each provide the required welding voltage, which is applied to the welding wires 5a, 5b, respectively, which are the fusion welding electrodes of the welding process. For this purpose, for example, contact sleeves can be provided in the welding torches 4a, 4b, to which a welding voltage is applied, for example via welding lines 6a, 6b, and which are in contact with the welding wires 5a, 5 b. However, it is also possible to use welding torches 4a, 4b having non-fusion welding electrodes to which a welding voltage is applied via welding lines 6a, 6 b. In this case, the welding wires 5a, 5b are fed to an arc that burns between the non-melting welding electrode and the material.
In each case, a defined welding current flows through the welding electrodes, wherein, of course, a second welding line for contacting the workpiece is provided for this purpose, which is not shown in fig. 1. The welding wires 5a, 5b are fed by the wire feeding units 3a, 3b, respectively, at a determined wire feeding speed. The wire feeding units 3a, 3b can be integrated in the welding devices 1a, 1b, respectively, but may also be separate units. The welding wires 5a, 5b and the welding lines 6a, 6b of the welding devices 1a, 1b and optionally also further lines (for example control lines or coolant lines) between the power sources 2a, 2b and the welding torches 4a, 4b can also be guided in a common or multiple hose line groups. The hose sets can be coupled to the welding torches 4a, 4b and to the power supplies 2a, 2b via suitable coupling means. In the welding devices 1a, 1b, control units 7a, 7b are also provided, which control and monitor the pulse welding process. For this purpose, the control units 7a, 7b preset or are able to set the required welding parameters, such as pulse frequency, wire feed speed, welding current value, pulse current duration, basic current duration, etc. Input/output units 8a, 8b can also be provided for inputting or for displaying specific welding parameters or welding states. Such welding devices 1a, 1b are of course sufficiently known and need not be described in detail here. For a multiple pulse welding method with more than two pulse welding processes, of course, more welding devices 1a, 1b are provided in each case. A plurality of welding devices 1a, 1b of the multi-pulse welding method (optionally also together with associated wire feed units 3a, 3b) can also be arranged in a common housing.
In order to carry out the tandem welding process, the two welding torches 4a, 4b are arranged in the illustrated embodiment locally relative to one another such that they can work in a common weld puddle 11 on a workpiece 10. This arrangement relative to each other may be fixed, for example in the way: the two welding torches 4a, 4b are arranged on a welding robot 12, which guides the two welding torches 4a, 4b (as shown in fig. 1). However, the arrangement may also be variable, for example in the manner: each welding torch 4a, 4b is guided by a welding robot 12. It is also not important whether the welding torches 4a, 4b are arranged one after the other continuously, side by side or in any other way offset from one another with respect to the welding direction. It is also immaterial whether lap welding, build-up welding or any other welding method is carried out by means of a pulse welding process. These embodiments are of course also applicable in a similar manner to multi-pulse welding processes with more than two pulse welding processes.
According to FIG. 2, by means of a welding current ISThe course over time t illustrates the sufficiently known pulse welding method. During pulse welding, the basic current ISGPulse higher than thatCurrent ISIAt a predetermined pulse frequency fDPeriodically alternating with each other. Of course, the pulse frequency fDIs as a period duration t of the welding cycle SZDDerived from the inverse of (a), the welding cycle being derived from having a basic current ISGAnd has a pulse current ISIThe phase of the pulse current. During the pulse current phase, the welding droplets should be respectively stripped into the respective weld puddle 11. The pulse frequency f can also be modified during weldingDAnd/or the basic current ISGOr a pulse current ISIThe value of (c).
Welding current IS1、IS2The course of the time-dependent course of the signals in fig. 2 is of course idealized and is shown in a simplified manner. Of course, in reality, there will be a certain current ramp at the flanks. Likewise, it is generally provided that the welding current ISAt the slave pulse current ISITransition to basic current ISGIn the case of (3) a step-like or other current profile to assist in stripping the droplets. Short intermediate current pulses are usually also provided in the basic current phase in order to increase the process stability, as will also be described in more detail later. However, this does not change the cycle duration t of the welding cycle SZDAnd the pulse frequency f derived therefromD。
In the case of the tandem pulse welding process according to the invention, the two pulse welding processes are synchronized with each other in such a way that: pulse frequency f of the two pulse welding processesD1＝1/tD1、fD2＝1/tD2Are in a predetermined specific relationship with one another, and the resulting welding cycles SZ1, SZ2 have a predetermined specific phase relationship with one another. Preferably, the following applies: one pulse frequency is an integer multiple of the other pulse frequency. This, in turn, is, of course, also universally applicable in a similar manner to multi-pulse welding methods in which the individual pulse welding processes are synchronized with one another. In the example of fig. 2, for example, the pulse frequency f of the following pulse welding processD2Is, for example, the pulse frequency f of the predominant pulse welding processD1Double, but vice versa. Additionally, having a higher pulse frequency fD2With respect to a welding current profile having a lower pulse frequency fD1The welding current profile of (2) is delayed in time by a phase difference tPI.e. starting with a pulse current I staggered in timeSIOf (2) is performed. However, the phase difference can of course also be expressed as a pulse frequency f relative to the prevailing pulse welding processD1The phase angle of (c).
In general, the predominant pulse welding process has a higher pulse frequency fD1And the following pulse welding process has a lower or the same pulse frequency fD2. In the case of a multi-pulse welding method, there is a leading pulse welding process and a plurality of following pulse welding processes, wherein in this case the leading pulse welding process also preferably has the highest pulse frequency and the following pulse welding processes have a lower or the same pulse frequency. However, the pulse frequency of each following pulse welding process does not have to be equal to one another.
In order to carry out the tandem pulse welding process, the respective pulse frequency f must be known in both welding devices 1a, 1b or in the control units 7a, 7bD1、fD2And also the possible phase difference t is knownP. That is to say the welding current IS1、IS2The time-dependent profiles must be synchronized with one another. To achieve this, the two welding devices 1a, 1b must be synchronized with one another.
For this purpose, the welding devices 1a, 1b, 1c of the multipulse welding method, and generally the control units 7a, 7b, 7c of the welding devices 1a, 1b, 1c, are connected to each other via a communication connection 15, which may be wired or wireless, as shown in fig. 3. Via the communication connection 15, at the start of the multi-pulse welding process, synchronization information SI is transmitted from the welding device 1a, which prefers the leading pulse welding process, to the other welding devices 1b, 1c, which prefer the following pulse welding process. The synchronization information SI is used in the receiving welding devices 1b, 1c to adapt, in particular synchronize, the pulse welding process carried out by the welding devices 1b, 1c to the pulse welding process carried out by the transmitting welding device 1 a.
In the simplest case, the synchronization information SI is the respective synchronization pulse SP transmitted by the transmitting welding device 1a via the communication connection 15. Here, the synchronization pulse SP is in a defined temporal relationship with the welding cycle SZ1 in the transmission welding device 1 a. The synchronization pulse SP is preferably set at the pulse frequency f in the transmission welding device 1a at the beginning of the welding cycle SZ1 (e.g., at the beginning of the basic current phase)D1And (5) sending. The synchronization pulse SP can also be stored or set with a specific phase difference t relative theretoPAnd (5) sending. To achieve more precise synchronization, it is also possible to synchronize at a phase difference tPKnown delay times, such as reaction times of the transmitting, receiving welding devices 1b, 1c, etc., are taken into account.
The synchronization pulse SP can be transmitted as a current or voltage pulse on the wired communication connection 15 between the two welding devices 1a, 1 b. It is also possible, however, for the communication connection 15 to be embodied as a data bus, on which bus messages are transmitted. In this case, the synchronization pulses SP can be transmitted as bus messages, which can be implemented not only by wire (cable, glass fiber, etc.) but also wirelessly (Wifi, bluetooth, etc.). The welding current profile Is synchronized with the received synchronization pulse SP in the receiving welding devices 1b, 1c, for example, in such a way that the welding cycle SZ2 in the receiving welding device 1b Is set to a pulse frequency fD2Starting with the receipt of a synchronization pulse (e.g., with a base current phase). Corresponding pulse frequency fD1、fD2Can be stored or set in the welding apparatuses 1a, 1b, 1 c.
Similarly, the phase difference t can be stored or set in the welding device 1b, normally a following welding deviceP. For this reason, the welding cycle SZ2 in the reception welding apparatus 1b can be set to the phase difference tPStarting after the reception of the synchronization pulse SP.
Additional welding parameters required, e.g. welding current ISI1、ISG1、ISI2、ISG2Of course, the pulse current duration, the basic current duration, etc. are likewise stored or set in the welding devices 1a, 1b, 1c, so that the welding devices 1a, 1b, 1c can carry out a pulse welding process.
Which welding device 1a, 1b is the sending welding device, i.e. the welding device which is the leading welding device in the synchronization and which is the receiving welding device, i.e. the welding device which follows in the synchronization, is not essential per se for the invention. This can be stored or set, for example, in the welding devices 1a, 1b, 1c participating in the multi-pulse welding method. The setting can of course also be changed, even during welding.
The setting can be made by the welder, for example via the respective input/output unit 8a, 8 b.
However, a higher-level control unit, for example a robot control or a process control, can also be provided, which is connected to the welding devices 1a, 1b, 1c and presets the settings. For this purpose, the welding devices 1a, 1b, 1c and the superordinate control unit can be connected in parallel or in series with one another via a data bus in order to be able to carry out the setting. If the communication connection 15 is implemented as a data bus, this data bus can also be used for the setting.
It is also conceivable to use welding parameters, such as the pulse frequency fDOr wire feed speed vDSettings are stored as to which welding device of the welding devices 1a, 1b, 1c is leading in synchronization. It may be provided here, for example, that the highest pulse frequency f is usedDThe welding devices 1a, 1b, 1c carrying out the pulse welding process are always transmitting welding devices and, in addition, receiving welding devices.
In one embodiment, the additional information can be transmitted via the communication connection 15.
For example, the transmission welding apparatus 1a transmitting the synchronization information SI can also set its pulse frequency fD1Or the pulse frequency f to be set by the reception welding device 1bD2The synchronization information SI is transmitted, for example, in separate or identical bus messages. If transmitting its own pulse frequency fD1Then can be connectedThe welding apparatus 1b stores or sets a frequency divider F therein (as shown in fig. 3). By means of the frequency divider F, it is then possible to simply derive the received pulse frequency F fromD1In determining the pulse frequency fD2Is fD2＝fD1and/F. Of course, it is advantageous here if the two pulse frequencies fD1、fD2Are integer ratios (e.g., 1/2, 1/3, 1/4) with respect to each other, that is, the frequency divider (Frequenzteiler) F is an integer. This also enables the pulse frequency fD1、fD2During the multi-pulse welding process. For this purpose, for example, the prevailing welding device 1a sets a new welding pulse frequency fD1It is sufficient to send it to the following welding device 1b, which then determines again and sets the pulse frequency F according to the frequency divider FD2. Thereby, the pulse frequency f of the welding device 1b is receivedD2Following the pulse frequency f of the transmission welding device 1aD1. In another case, the receiving welding device 1b obtains the pulse frequency f to be set directly from the transmitting welding device 1aD2Thus, no setting is required in this respect on the receiving welding device 1 b. In both cases, the handling of the multi-pulse welding process is made easier for the welder.
In principle, for a desired phase difference tDThis can also be handled. Phase difference t which may also be zeroDCan be stored or set in the welding devices 1a, 1b or can be transmitted by the welding device 1a as synchronization information SI to another welding device 1b, for example in a separate bus message or in a common bus message with the other synchronization information SI.
Phase difference tDIt is also possible to set the welding device 1a, 1b variably, for example as time or as a percentage. Preferably, the phase difference t can also be variedDThe setting is variable between 0 and 100% in individual percentage increments, for example in increments of 1%. Here, for example, 25% corresponds to a phase difference of 90 °, and 50% corresponds to a phase difference of 180 °. Phase difference tDThe setting of (b) can be carried out by the welder or can be predefined by the higher-level control unit, for example again via a data bus as described above.
It is also possible to consider the desired phase difference tDSynchronization is performed at the point in time when the synchronization information SI is transmitted. The transmission welding apparatus 1a can delay the synchronization information SI by the phase difference t after the start of the pulse current phase, for exampleDTo the receiving welding device 1 b. In this case, the desired phase difference tDPossibly stored in the sending welding device 1a or set there. Then, the welding apparatus 1b starts its own pulse current phase or basic current phase (depending on the synchronization) when receiving the synchronization information SI, thereby automatically setting the desired phase difference tD. Thus, the phase difference t is changed/adjustedDIs possible during the welding process.
In a further possible embodiment, the transmitting welding device 1a, for example the welding device which is present during tandem pulse welding, continuously uses the synchronization pulse SP as synchronization information SI at its own pulse frequency fD1I.e. with a time period tD1Transmission as shown in fig. 4. The synchronization pulse SP is in turn in a defined temporal relationship with the welding cycle SZ1 in the sending welding device. For example, a synchronization pulse SP is sent at the beginning of each welding cycle SZ1, taking into account the phase difference tPSent at the beginning of the pulse current phase. The synchronization pulses SP can in turn be transmitted as current or voltage pulses on a wire as communication connection 15 or as bus messages on a wired or wireless data bus as communication connection 15. The welding device 1b, which is received, for example, is followed in a tandem pulse welding process, can be evaluated in an evaluation unit (hardware and/or software), for example, in the control unit 7b, from the period t of the received synchronization pulseD1Simply determining the pulse frequency f of the transmission welding device 1aD1For example in a comparator circuit with a counter or from a timestamp of a received bus message.
The welding cycle SZ2 in the receiving welding device 1b is again synchronized in time with the synchronization pulse SP, for example in such a way that: the start of the welding cycle SZ2 in the reception welding apparatus 1b is synchronized with the reception of the synchronization pulse SP.
In the receiving welding device 1b, a frequency divider F can again be stored and can then be selected from this according to FD2＝fD1Determining the pulse frequency F in the receiving welding device 1bD2. Of course, it is advantageous here if the two pulse frequencies fD1、fD2Are in integer ratios with each other. After the continuous transmission of the synchronization pulse SP at least during the synchronization period, the pulse frequency f of the welding device 1b is receivedD2Pulse frequency f of automatic follow-up transmission welding device 1aD1。
In addition to the synchronization pulse SP, the transmission welding apparatus 1a can also transmit a pulse frequency f to be setD2Is sent to the receiving welding device 1b, for example again in a separate or same bus message. In this case, the synchronization pulse SP can be used to ensure and control the synchronization of the two welding apparatuses 1a, 1 b.
Of course, the time delay of the synchronization pulse SP relative to the welding cycle SZ1 in the transmission welding device 1a can be reset to the phase difference t of the two current-induced flow profiles in the two welding devices 1a, 1bP. Here, the welding device 1b is set to the welding current IS2The time profile is synchronized with the received synchronization pulses SP, as shown in fig. 4. Alternatively, the desired phase difference t can be determinedPStored or set in the reception welding device 1b as welding parameters. In this case, the receiving welding device 1b may delay the welding cycle SZ2 in time by the phase difference tPAssociated with the reception of the synchronization pulse SP. In principle, however, both may also be simultaneous.
Pulse frequency f required for pulse welding processD1、fD2Alternatively, the frequency divider F can be set by the welder on the welding device 1a, 1 b. However, this requires the welder to have a deep process knowledge, which cannot be assumed. It is therefore possible to specify the pulse frequency fD1、fD2From other welding parameters set, in particular from the wire feed speed VD(which in turn is usually related to the welding current) or the welding current ISTo derive the same. For this purpose, in the welding devices 1a, 1b, for exampleWelding characteristic curves for different welding wires can be stored in the control unit 7a, 7b or the memory unit, as shown in fig. 5 at the wire feed speed VDAs shown by way of example. According to the set wire feeding speed VDFrom which the desired pulse frequency f can be deducedD. It is advantageous for the synchronization that the pulse frequency f thus determined isDIs set to another pulse frequency fDThe next integer ratio is formed. The required frequency divider F can then also be derived therefrom, which is preferably set to the next integer. It follows that, if welding characteristic curves are stored in both welding devices 1a, 1b, it is also possible to use the wire feed speed v in an equivalent mannerD1Instead of the pulse frequency fD1To the receiving welding device 1 b.
A tandem pulse welding process is shown in FIG. 6, where fD1＝fD2(i.e., divider F ═ 1) and the phase difference is 90 °. In addition, in the case of two pulse welding processes, short intermediate pulses ZP1, ZP2 are provided in the basic current phase, i.e. the welding current ISI1、ISI2A short rise in time. Of course, the duration and the amplitude of the intermediate pulses ZP1, ZP2 can be stored or configured in the welding device 1a, 1 b. It is of course possible here that not all pulse welding processes of the multi-pulse welding method are provided with intermediate pulses ZP1, ZP 2. It is likewise conceivable that such intermediate pulses ZP1, ZP2 are not provided in each welding cycle SZ1, SZ2, but only in every xth welding cycle, which can likewise be stored or configured. The intermediate pulses ZP1, ZP2 are preferably arranged during the pulse welding process such that they are in the phase of the pulse current of the respective other pulse welding process. This is particularly easy to achieve, for example, if the phase difference is 180 °, in which case the phase of the primary current and the phase of the pulse current in the two pulse welding processes coincide with one another.
The synchronization of the pulse welding process of the multiple pulse welding method according to the invention can be started and stopped during welding as required. Preferably, in the case of starting welding, the arc is stabilized during each pulse welding processAfter a fixed burn, i.e. after ignition of the arc or when a set wire feed speed v is reachedDSynchronization is started. At the end of the multiple pulse welding process, e.g. when the wire feed speed vDWhen the lowering is started, the synchronization is preferably also ended. This can be done automatically by the welding device 1a, 1b or manually by the welder.
It is also possible that the synchronization of the individual pulse welding processes varies during welding. Other frequency dividers F can be set or derived during welding, for example. However, the wire feed speed of the following pulse welding process can also be varied, which can likewise lead to other pulse frequencies fD2Or a frequency divider F. Other phase differences t between the pulse welding processes can likewise be required or setP. Such variations can be caused, for example, by a multi-pulse welding process (e.g., an automated running welding program) and/or by a welder.
For example, at the pulse frequency f required by the leading pulse welding process and synchronized with the following pulse welding processD1And a pulse frequency f which can be derived from a stored welding characteristic curve (as in fig. 5, for example) on the basis of the set welding parametersD2The deviation between these can exceed limit values which are provided or stored in the welding devices 1a, 1 b. In this case, the control units 7a, 7b of the welding devices 1a, 1b can, for example, switch to the next frequency divider F, for example from F-1 to F-2, or in the other direction, that is from F-2 to F-1. Here, the phase difference t can also be adjusted as requiredP。
Fig. 7 shows, for example, the pulse frequency f which is the same in the tandem pulse welding methodD1、fD2I.e. fD1＝fD2And the synchronous switching of the phase difference of 180 DEG to the pulse frequency f of the following pulse welding processD2Halved, i.e. fD2＝fD1/2 or divider F2 and phase difference tPIs 0 deg.. Shows the welding current I of the prevailing pulse welding process as a function of time tS1And a welding current I of the following pulse welding process as a function of time tS2(dotted line). The switching is at a point in time tUThe process is carried out. Switching to a new pulse frequency f by means of said switchingD2The above. The new phase position is optionally set within several welding cycles SZ1, SZ2 depending on the implementation of the control. In the example according to fig. 2, the new phase position is set within four welding cycles SZ1 of the prevailing pulse welding process.