Wire feeding speed adaptive control method for arc sensing GTAW

Abstract

The application relates to a wire-filling GTAW wire-filling speed self-adaptive control method based on arc sensing. A droplet transfer frequency calculation method is used to calculate the droplet transfer frequency; a wire-filling speed state identification method is used to identify the current wire-filling speed state; and a wire-filling GTAW wire-filling speed self-adaptive control method is used to self-adapt the wire-filling speed. The application overcomes the problems that it is difficult to realize wire-filling speed state identification and self-adapt the wire-filling speed in the current wire-filling GTAW process.

Description

Technical Field

[0001] This invention relates to the field of adaptive control of GTAW (Growth Tolerancing Actuation) feed speed, and is a method for adaptive control of GTAW feed speed based on arc sensing. Background Technology

[0002] GTAW (Gas Non-Consumable Electrode Welding) is widely used in aerospace, marine engineering equipment, nuclear power plant construction, and other fields. Especially in recent years, the rapid development of arc additive manufacturing technology has placed higher demands on the automation and intelligence of filler wire GTAW. During GTAW, the filler wire speed has a crucial impact on welding efficiency and weld quality; a suitable filler wire speed is beneficial for maintaining arc stability and forming aesthetically pleasing welds. However, currently there is no method for adaptive control of the filler wire speed in filler wire GTAW. To address this challenge, this invention discloses an adaptive control method for filler wire speed in filler wire GTAW based on arc sensing. Summary of the Invention

[0003] The arc-sensor-based adaptive control method for GTAW (Ground-Tracked Wire Arcade) wire filling speed is based on the relationship between the droplet transition frequency ω and the wire filling speed μ. This relationship, where all other parameters remain constant, means that as the wire filling speed increases from a lower setting, the corresponding droplet transition frequency also increases, with the rate of increase gradually decreasing. When the wire filling speed reaches a certain range, the droplet transition frequency almost stops increasing; this range is considered the optimal wire filling speed range. The curve showing the relationship between the droplet transition frequency ω and the wire filling speed μ is shown below. Figure 1 As shown.

[0004] The system schematic diagram of the GTAW (Growth Towing Aid) feed speed adaptive control method based on arc sensing is shown below. Figure 2As shown, the feature is that: the arc-sensing-based GTAW (Gross-Task Welding) adaptive control method for filler wire speed is implemented by an arc-sensing-based GTAW adaptive control system for filler wire speed; the arc-sensing-based GTAW adaptive control system for filler wire speed consists of a droplet transfer monitor, a GTAW adaptive control system for filler wire speed, a filler wire speed sensor, a high-precision wire feeder, a wire feed tube, a welding torch, and a clamping device; the droplet transfer monitor is used to monitor the tungsten electrode arc signal, calculate the droplet transfer frequency using an arc-sensing-based droplet transfer frequency calculation method, and transmit it to the GTAW adaptive control system for filler wire speed via a communication bus; the tungsten electrode arc signal is the arc voltage between the tungsten electrode and the workpiece; the droplet transfer frequency is the number of droplet transfers per unit time; the GTAW... The adaptive wire feeding speed controller identifies the current wire feeding speed status and controls the adaptive wire feeder to adjust the wire feeding speed via a control bus. The wire feeding speed sensor, fixed to the wire feeding port of the high-precision wire feeder, consists of a speed measuring wheel, a clamping wheel, and a wire feeding speed calculation module. The speed measuring wheel rotates due to friction between the welding wire and the speed measuring wheel. The sensor calculates the wire feeding speed in real-time based on the speed and circumference of the speed measuring wheel and feeds it back to the high-precision wire feeder. The speed measuring wheel assists in calculating the wire feeding speed. The clamping wheel helps to fix the welding wire in place. The wire feeding speed calculation module calculates the wire feeding speed in real-time based on the speed and circumference of the speed measuring wheel. The high-precision wire feeder transmits the welding wire and corrects the wire feeding speed in real-time based on feedback, thereby improving the wire feeding accuracy. The clamping device fixes the wire feeding tube to the welding torch. The schematic diagram of the wire feeding speed sensor is shown below. Figure 3 As shown.

[0005] The aforementioned adaptive control method for GTAW (Gross Torque-to-Whip) filling speed based on arc sensing is characterized by: calculating the droplet transition frequency using a droplet transition frequency calculation method; this method is achieved by monitoring the characteristics of the arc signal during the transition phase, by monitoring the number of droplet transitions n within time t after filtering the arc signal, and then calculating the droplet transition frequency w = n / t; the arc signal characteristics during the droplet transition phase are the arc signal of the steep descent stage in the tungsten extreme arc signal, calculated by monitoring the voltage value U... r With preset voltage value U s When comparing, when U r s During this process, the droplet transition frequency detector will mark the subsequent arc signal in the same way until the detected voltage value is higher than the preset voltage value. This is counted as one droplet transition. The above operation is repeated, and different types of marking symbols are used for each arc signal segment that needs to be marked. Finally, by counting all the marking types, the total number of droplet transitions within that time period can be obtained; the preset voltage value U s ​Before calculating the droplet transfer frequency, it is necessary to collect an arc signal for a period of time (including at least one droplet transfer), filter it, and then calculate the average of its maximum and minimum values ​​to obtain the frequency, i.e., U. s =(U max +U min ) / 2. The arc signal during the droplet transition stage in the tungsten extreme arc signal is as follows: Figure 5 As shown.

[0006] The aforementioned arc-sensing-based GTAW (Gross Torque-Assisted Wire Actuation) adaptive control method for wire feeding speed is characterized by: adaptively controlling the wire feeding speed using a GTAW method; the GTAW method includes a wire feeding speed state identification method and a wire feeding speed adaptive control method; the wire feeding speed state identification method is achieved by monitoring changes in the droplet transition frequency, and by reducing the wire feeding speed by a certain value, the corresponding rate of change v of the droplet transition frequency is calculated. r And the range of variation of the preset droplet transition frequency change rate [v] smin ,v smax In comparison, the current state of the filling speed is then identified; the rate of change of the droplet transition frequency v is described. r The ratio of the droplet transition frequency change to the corresponding filler speed change is given; the preset droplet transition frequency change rate range is the range of droplet transition frequency change rates corresponding to the optimal filler speed; the filler speed states include three types: filler speed too low, optimal filler speed, and filler speed too high; the term "filler speed too low" refers to the calculated droplet transition frequency change rate v. r >v smax The optimal filling speed is defined as the calculated rate of change of the droplet transition frequency falling within a preset range, i.e., v smin <=v r <=v smax The excessively fast filler speed is the calculated rate of change v of the droplet transition frequency. r <v smin The adaptive control method for filling speed is achieved by monitoring the rate of change of the droplet transition frequency and the current state of the filling speed.

[0007] Beneficial effects of the invention

[0008] This invention relates to an adaptive control method for filler speed in GTAW (Ground-Tracked Atomic Welding) based on arc sensing. The method calculates the droplet transition frequency using a droplet transition frequency calculation method; identifies the current filler speed state using a filler speed state recognition method; and adaptively controls the filler speed using an adaptive control method. This invention overcomes the current difficulties in achieving filler speed state recognition and adaptive filler speed control in GTAW processes. Attached Figure Description

[0009] Figure 1 This is a graph showing the relationship between the droplet transition frequency ω and the filler wire speed μ.

[0010] Figure 2 This is a schematic diagram of the adaptive control system for GTAW (Growth Towing Aid) feed rate based on arc sensing.

[0011] Figure 3 This is a schematic diagram of a wire filling speed sensor.

[0012] Figure 4 Flowchart of the adaptive control method for GTAW filler wire speed based on arc sensing

[0013] Figure 5 This is a schematic diagram of the arc signal during the droplet transition stage in the filtered tungsten extreme arc signal.

[0014] Figure 6 This is a flowchart of the method for identifying the filling speed status.

[0015] In the figure: Δμ is a pre-set small segment of the filler wire speed change value, Δω is the corresponding droplet transition frequency change, and v r v is the calculated rate of change of the droplet transition frequency. smin With v smax These are the preset maximum and minimum values ​​of the droplet transition frequency change rate.

[0016] Figure 7 Flowchart of the adaptive control method for filler wire speed.

[0017] In the figure: q0, q1, and q2 are calculated using equation (1). k is the kth calculation cycle. e(k) is calculated using equation (2).

[0018] ec(k) is calculated using equation (3). K p K i and K d These are the PID control parameters.

[0019]

[0020] In the formula, K p T is the proportionality coefficient. I Let T be the integration time constant. D is the differential time constant.

[0021] e(k) = v r (k)-v s (2)

[0022] In the formula, v r(k) represents the rate of change of the droplet transition frequency obtained in the kth calculation cycle, v s =(v smin +v smax ) / 2.

[0023] ec(k)=e(k)-e(k-1) (3) Detailed Implementation

[0024] To better illustrate the technical solution and beneficial effects of the invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments of the invention are not limited thereto.

[0025] Step 1: Calculation of droplet transition frequency

[0026] In the GTAW (Gross-Filled Wire Actuation) process, the droplet transition frequency change rate can be used to reflect whether the current filling speed meets expectations. Before identifying the filling state, it is necessary to calculate the current droplet transition frequency. To address this challenge, this invention discloses a method for calculating the droplet transition frequency. Figure 2 As shown, before calculating the current droplet transition frequency, Figure 2 The droplet transition monitor in the system receives a tungsten extreme arc signal for a certain period of time (at least one droplet transition time) in advance, and obtains the maximum voltage value U in this arc signal after filtering. max and minimum voltage value U min Thus, the preset voltage value U is calculated. set =(U max +U min ) / 2. When calculating the droplet transition frequency, within time t, the droplet transition monitor will output the filtered voltage value U r with U set For comparison, when U r ≤U set At that time, the droplet transition frequency detector will mark the subsequent arc signal until U r >U set This is counted as one droplet transition. The above operation is repeated, and different types of marking symbols are used for each arc signal that needs to be marked. Finally, by counting all the marking types, the total number of droplet transitions n in this period can be obtained. Finally, the current droplet transition frequency w = n / t is calculated and transmitted to the GTAW filler wire speed sensor.

[0027] Step 2: GTAW Filler Speed ​​Adaptive Control

[0028] In the GTAW (Growth Toweld Awakening) process, the feed rate has a significant impact on welding efficiency and weld quality. Therefore, it is necessary to control the feed rate during welding to obtain the optimal feed rate. To address this challenge, this invention discloses an adaptive control method for feed rate in GTAW, including a feed state recognition method and a feed rate adaptive control method. Before implementing adaptive feed rate control... Figure 2 The GTAW (Gross-Task Arrival) feed rate adaptive controller in the molten wire system calculates the corresponding droplet transition frequency change rate v by reducing the feed rate by a certain value. r The current filling speed status is then identified by comparing it with a preset range of droplet transition frequency changes. The filling speed status identification process is as follows: Figure 6 As shown. When v r >=v smax or v r <=v smin When the filling speed is too slow or too fast, the GTAW filling speed adaptive controller will use the filling speed adaptive control method to control the filling speed. Figure 2 The high-precision wire feeder in the middle adjusts the wire feeding speed until v r =v s , where v s =(v smin +v smax ) / 2. The flowchart of adaptive control of filler speed is as follows: Figure 7 As shown. During the adaptive filler speed process, Figure 2 The filling speed sensor in the machine monitors the filling speed in real time and feeds it back to the high-precision wire feeder. The high-precision wire feeder calculates the difference between the actual filling speed and the theoretical filling speed and corrects the filling speed in real time, thereby improving the filling accuracy.

Claims

1. An adaptive control method for feed wire speed in GTAW (Growth Tolerancing Actuation) based on arc sensing, used to adaptively control the feed wire speed during the GTAW process, characterized in that: The aforementioned arc-sensing-based adaptive control method for GTAW (Ground-To-Waste Wire Feeding) speed is implemented by an arc-sensing-based adaptive control system for GTAW speed. This system comprises a droplet transition monitor, a GTAW speed adaptive controller, a wire feed speed sensor, a high-precision wire feeder, a wire feed tube, a welding torch, and a clamping device. The droplet transition monitor monitors the tungsten electrode arc signal, calculates the droplet transition frequency using an arc-sensing-based method, and transmits it to the GTAW speed adaptive controller via a communication bus. The tungsten electrode arc signal is the arc voltage between the tungsten electrode and the workpiece. The droplet transition frequency is the number of droplet transitions per unit time. The GTAW speed adaptive controller identifies the current wire feed speed status and controls the adaptive wire feeder's speed via a control bus. The wire feed speed sensor is fixed to the high-precision wire feeder's feed port and consists of a speed measuring wheel and a pressure sensor. The system comprises a tensioning wheel and a wire feeding speed calculation module. The friction between the welding wire and the speed measuring wheel drives the speed measuring wheel to rotate. The wire feeding speed is calculated in real-time based on the speed and circumference of the speed measuring wheel and fed back to the high-precision wire feeder. The speed measuring wheel assists in calculating the wire feeding speed. The tensioning wheel cooperates with the speed measuring wheel to fix the welding wire. The wire feeding speed calculation module calculates the wire feeding speed in real-time based on the speed and circumference of the speed measuring wheel. The high-precision wire feeder transmits the welding wire and corrects the wire feeding speed in real-time based on feedback, thereby improving the wire feeding accuracy. The clamping device fixes the wire feeding tube to the welding torch. The arc-sensing-based GTAW wire feeding speed adaptive control method adaptively controls the wire feeding speed, including a wire feeding speed state recognition method and a wire feeding speed adaptive control method. The wire feeding speed state recognition method is achieved by monitoring the change in the droplet transition frequency. By reducing the wire feeding speed by a certain value, the corresponding droplet transition frequency change rate v is calculated. r The current filling speed state is then identified by comparing it with the preset range of droplet transition frequency change rate; the droplet transition frequency change rate v r The ratio of the droplet transition frequency change Δω to the corresponding filler speed change Δμ is given. The preset droplet transition frequency change rate range is the range of droplet transition frequency change rates corresponding to the optimal filler speed. The filler speed states include three types: filler speed too low, optimal filler speed, and filler speed too high. The term "filler speed too low" refers to the calculated droplet transition frequency change rate v. r >v smax The optimal filling speed is defined as the calculated rate of change of the droplet transition frequency falling within a preset range, i.e., v smin <=v r <=v smax The excessively fast filler speed is the calculated rate of change v of the droplet transition frequency. r <v smin The adaptive control method for filling speed is achieved by monitoring the rate of change of the droplet transition frequency and the current state of the filling speed.

2. The adaptive control method for GTAW filler speed based on arc sensing according to claim 1, characterized in that: The droplet transition frequency is calculated using a method that monitors the characteristics of the arc signal during the transition phase. Within time t, after filtering the arc signal, the number of droplet transitions (n) is monitored, and the droplet transition frequency w = n / t is calculated. The arc signal characteristics during the droplet transition phase are those of the steep descent stage in the tungsten end arc signal. This is achieved by monitoring the voltage value U... r With preset voltage value U s When comparing, when U r s During this process, the droplet transition frequency detector marks the subsequent arc signal until the detected voltage value exceeds a preset voltage value. This is then counted as one droplet transition. This process is repeated, using different marking symbols for each segment of the arc signal to be marked. Finally, the total number of droplet transitions in that arc signal segment is counted. The preset voltage value U... s Before calculating the droplet transition frequency, it is necessary to pre-acquire an arc signal that includes at least one droplet transition time, filter it, and then calculate its maximum value U. max With minimum value U min The average value is obtained, i.e., U s =(U max +U min ) / 2.​

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