REVERSE POLARITY PLASMA ARC ROBOT ADDITIVE MANUFACTURING SYSTEM AND IMPLEMENTATION METHOD THEREFOR
20210146469 · 2021-05-20
Assignee
Inventors
- Zhenmin WANG (Guangzhou City, CN)
- Fubiao ZHANG (Guangzhou City, CN)
- Junhao WEI (Guangzhou City, CN)
- Pengfei WANG (Guangzhou City, CN)
Cpc classification
B33Y10/00
PERFORMING OPERATIONS; TRANSPORTING
B22F10/22
PERFORMING OPERATIONS; TRANSPORTING
B33Y30/00
PERFORMING OPERATIONS; TRANSPORTING
B22F2999/00
PERFORMING OPERATIONS; TRANSPORTING
B22F10/22
PERFORMING OPERATIONS; TRANSPORTING
B23K10/027
PERFORMING OPERATIONS; TRANSPORTING
B33Y50/02
PERFORMING OPERATIONS; TRANSPORTING
B22F2999/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
B23K10/00
PERFORMING OPERATIONS; TRANSPORTING
B33Y10/00
PERFORMING OPERATIONS; TRANSPORTING
B33Y30/00
PERFORMING OPERATIONS; TRANSPORTING
B33Y50/02
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Disclosed are a reverse polarity plasma arc robot additive manufacturing system and an implementation method therefor, the system comprising an industrial robot, an additive manufacturing power source, a wire feeding machine, a machine visual system, an industrial computer, a plasma welding gun, a refrigerating device, a gas device and an auxiliary tool fixture. The industrial robot, the additive manufacturing power source, the wire feeding machine, the refrigerating device, the gas device and the auxiliary tool fixture are all connected to the industrial computer via a CAN bus; the machine visual system is connected to the industrial computer by means of a TCP/IP protocol; the plasma welding gun is connected to the refrigerating device, the additive manufacturing power source, the wire feeding machine, the gas device and the auxiliary tool fixture; and the refrigerating device is further connected to the additive manufacturing power source. The additive manufacturing power source comprises a main-arc power source and a pilot-arc power source, and the main-arc power source and the pilot-arc power source are both connected to the plasma welding gun; and the main-arc power source comprises a main-arc power source main circuit and a main-arc power source control circuit, and the pilot-arc power source comprises a pilot-arc power source main circuit, a pilot-arc power source control circuit and a high-frequency and high-voltage arc ignition circuit. The additive manufacturing power source not only realizes the inverse change of the high-frequency and high-efficiency, but also realizes the integration and digital integration of the pilot-arc power source and the main-arc power source. The main-arc power source and the pilot-arc power source are digitally coordinated by means of a CAN network, and the volume of same is compact, the compatibility is better, the field environment is more adaptable, and the expansion capability is stronger.
Claims
1. A reverse polarity plasma arc robot additive manufacturing system, comprising an industrial robot, an additive manufacturing power source, a wire feeding machine, a machine visual system, an industrial computer, a plasma welding gun, a refrigerating device, a gas device and an auxiliary tooling fixture, wherein the industrial robot, the additive manufacturing power source, the wire feeding machine, the refrigerating device, the gas device and the auxiliary tooling fixture are all connected to the industrial computer via a CAN bus; the machine visual system is connected to the industrial computer over a TCP/IP protocol; the plasma welding gun is connected to the refrigerating device, the additive manufacturing power source, the wire feeding machine, the gas device and the auxiliary tooling fixture; and the refrigerating device is further connected to the additive manufacturing power source, wherein the machine visual system is used to detect information of a workpiece to be additively manufactured and location information thereof, and feed the information into the industrial computer; the machine visual system is used to identify a path, monitor a state and track the workpiece during additive manufacturing; the industrial computer is used to select an additive manufacturing mode and a basic process parameter supporting same, and plan an additive path; the industrial computer performs data processing and remote monitoring on the industrial robot, the additive manufacturing power source, the wire feeding machine, the gas device and the auxiliary tooling fixture during the additive manufacturing; the industrial robot serves as an execution mechanism for controlling the plasma welding gun and the auxiliary tooling fixture to complete corresponding action operations; the additive manufacturing power source is used to provide energy required during the additive manufacturing; the wire feeding machine is used to convey a wire and adjust a feeding speed; the plasma welding gun is used to complete energy conversion so as to provide energy and power for wire fused deposition and transition of molten metal; the refrigerating device is used to provide cooling for the additive manufacturing power source and the plasma welding gun; the gas device is used to provide an ionized gas and a shielding gas to the plasma welding gun; and the auxiliary tooling fixture is used to complete clamping and displacement operations of the workpiece.
2. The reverse polarity plasma arc robot additive manufacturing system according to claim 1, wherein the additive manufacturing power source comprises a main-arc power source and a pilot-arc power source, and the main-arc power source and the pilot-arc power source are both connected to the plasma welding gun; and the main-arc power source comprises a main-arc power source main circuit and a main-arc power source control circuit, and the pilot-arc power source comprises a pilot-arc power source main circuit, a pilot-arc power source control circuit and a high-frequency and high-voltage arc ignition circuit, wherein the main-arc power source main circuit is used to realize the conversion and transmission of main-arc energy; the main-arc power source control circuit is used to control the normal work of the main-arc power source for each task; the pilot-arc power source main circuit is used to realize the conversion and transmission of pilot-arc energy; the pilot-arc power source control circuit is used to control the normal work of the pilot-arc power source for each task; and the high-frequency and high-voltage arc ignition circuit is used to break down an air gap between a tungsten electrode and a nozzle of the plasma welding gun to establish and sustain an arc.
3. The reverse polarity plasma arc robot additive manufacturing system according to claim 2, wherein the main-arc power source main circuit adopts a dual inverter topology, comprising an input rectification and filtering module, an IGBT high-frequency inverter circuit, an intermediate-frequency transformer, a fast rectification and filtering module, an IGBT low-frequency modulation circuit, and a high-voltage arc stabilization circuit, wherein the input rectification and filtering module is used to convert 380V three-phase alternating current into smooth direct current; the IGBT high-frequency inverter circuit is used to invert the rectified direct current into high-frequency alternating current; the intermediate-frequency transformer is used for energy conversion, so as to provide high-current and low-voltage alternating current required during the additive manufacturing; the fast rectification and filtering module is used to convert the alternating current, which has passed through the intermediate-frequency transformer, into large-current and low-voltage direct current; the IGBT low-frequency modulation circuit is used to perform commutation adjustment, frequency modulation, and inductive filtering on the direct current, which has passed through the fast rectification and filtering module, to output required current and voltage waveforms; and the high-voltage arc stabilization circuit is used to ensure that a relatively high voltage is applied at the time of polarity switching of the output current of the IGBT low-frequency modulation circuit to ensure reliable re-ignition of the arc when the current crosses zero.
4. The reverse polarity plasma arc robot additive manufacturing system according to claim 2, wherein the main-arc power source control circuit comprises a DSC controller, a high-frequency inverter drive circuit, an over-current detection circuit, a current feedback circuit, a low-frequency modulation drive circuit, an arc stabilization circuit drive circuit, a human-machine interaction system, an overheat detection circuit, an over-voltage detection circuit, an under-voltage detection circuit and a CAN communication interface circuit, wherein the DSC controller generates three sets of all-digitized PWM control signals, and controls the low-frequency modulation drive circuit, the high-frequency inverter drive circuit, and the arc stabilization circuit drive circuit respectively; the high-frequency inverter drive circuit is used to convert the PWM control signal generated by the DSC controller into a drive signal required by a power switching transistor IGBT in the IGBT high-frequency inverter circuit; the over-current detection circuit is used to prevent the current passing through the power switching transistor IGBT from being excessive; the current feedback circuit is used to implement closed-loop adjustment of the output current of the power source; the low-frequency modulation drive circuit is used to convert the PWM control signal generated by the DSC controller into a drive signal required by a power switching transistor IGBT in the IGBT low-frequency modulation circuit; the arc stabilization circuit drive circuit is used to convert the PWM control signal generated by the DSC controller into a drive signal required by a power switching transistor IGBT in the high-voltage arc stabilization circuit; the human-machine interaction system is used to implement a dialog between a human and the power source; the overheat detection circuit is used to prevent the temperatures of the power switching transistor IGBTs from becoming too high; the over-voltage detection circuit is used to detect whether the 380V three-phase alternating-current voltage input by the power source is too high; the under-voltage detection circuit is used to detect whether the 380V three-phase alternating-current voltage input by the power source is too low; and the CAN communication interface circuit is used to communicate with other systems to achieve digitized collaboration.
5. The reverse polarity plasma arc robot additive manufacturing system according to claim 4, wherein the DSC controller comprises a DSC microcontroller, a power source power supply module, an external clock circuit, a reset circuit, and a JTAG debug and download circuit.
6. The reverse polarity plasma arc robot additive manufacturing system according to claim 2, wherein the pilot-arc power source main circuit comprises an input rectification and filtering module, a MOSFET inverter circuit, an intermediate-frequency transformer, and a fast rectification and filtering module, wherein the input rectification and filtering module is used to convert 380V three-phase alternating current into smooth direct current; the MOSFET inverter circuit is used to invert the rectified direct current into high-frequency alternating current; the intermediate-frequency transformer is used for energy conversion, so as to obtain high-current and low-voltage alternating current; and the fast rectification and filtering module is used to convert the alternating current, which has passed through the intermediate-frequency transformer, into large-current and low-voltage direct current.
7. The reverse polarity plasma arc robot additive manufacturing system according to claim 1, wherein the wire feeding machine comprises a wire feeding control system, a high-frequency AC/DC inverter, a wire feeding drive circuit, a wire feeding motor, pinch rollers, and a fixed bracket, wherein the wire feeding control system comprises a DSC controller, an optocoupler isolation module, a voltage sampling module, a transformer filtering module, a power supply module, a fault detection module and a CAN driver.
8. The reverse polarity plasma arc robot additive manufacturing system according to claim 7, wherein the wire feeding drive circuit comprises a high-frequency half-bridge chopper circuit, two diodes, a relay switch, an optocoupler, and a motor load.
9. A method for implementing a reverse polarity plasma arc robot additive manufacturing system, comprising the following steps: S1. selecting, by an industrial computer according to the characteristics of a workpiece and a wire therefor, a corresponding additive manufacturing mode and a basic process parameter supporting same; and detecting, by a machine visual system, information of the workpiece to be additively manufactured and the position thereof, and feeding the information into the industrial computer and plan an additive path to coordinate the movements of an industrial robot and an auxiliary tooling fixture to corresponding workstations; S2. activating a refrigerating device and a gas device to prepare for the work of a plasma welding gun and an additive manufacturing power source; S3. switching on a three-phase power source to supply power to the additive manufacturing power source and a wire feeding machine for conducting an additive manufacturing work; and S4. feeding the wire stably by the wire feeding machine according to process requirements pre-set by the industrial computer, and melting the wire by a plasma arc jet generated by the plasma welding gun, and stacking and shaping the wire following the corresponding path.
10. The method for implementing a reverse polarity plasma arc robot additive manufacturing system according to claim 9, wherein in step S3, after the three-phase power source supplies power to the additive manufacturing power source, a pilot-arc power source of the additive manufacturing power source works first, a high-frequency and high-voltage arc ignition circuit is used to generate a high-frequency and high-voltage signal to break down an air gap between a tungsten electrode and a nozzle of the plasma welding gun to establish and sustain an arc with a very small current; after the ignition of the arc is successful, a DSC controller of the pilot-arc power source sends a pilot-arc success signal to a DSC controller of a main-arc power source, and the main-arc power source is activated to generate a transfer arc between the workpiece and the tungsten electrode; after the transfer arc is successful, the additive manufacturing system can turn off a pilot arc according to the requirements of materials and processes, so as to perform the additive manufacturing process in the case of the transfer arc; and the pilot arc can also continue to work, so as to form a mixed arc of the pilot arc and the transfer arc for additive manufacturing, wherein, in order to finely control the amount of heat input and the amount of molten metal, an output waveform of the main-arc power source includes reverse polarity, variable polarity, and pulse; and the wire feeding speed is constant or is a variable speed or changes in a pulsating manner.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF EMBODIMENTS
[0059] It should be noted that, in the case of no conflict, the embodiments and the features thereof in the present application can be combined with each other. The present application is further described below in detail with reference to the drawings and specific embodiments.
[0060] As shown in
[0061] The machine visual system is connected to the industrial computer over TCP/IP. The refrigerating device is further connected to the additive manufacturing power source and the plasma welding gun respectively. The wire feeding machine is further connected to the plasma welding gun. The gas device is connected to the plasma welding gun. The auxiliary tooling fixture is connected to the plasma welding gun.
[0062] The industrial robot serves as an execution mechanism, which mainly completes the position and pose adjustment of the welding gun and clamps the welding gun to perform the corresponding movement.
[0063] Among the main circuit and the DSC control circuit of the additive manufacturing power source, the main circuit part of the welding power source that realizes the conversion and transmission of energy during welding, is the core part of the entire welding system; and the DSC control circuit thereof that mainly implements the generation of power switching transistor PWM drive signals, the PID adjustment on sampling signals, the communication processing of the human-machine interaction system and the wire feeding system, the related protection for the main circuit and other functions, is responsible for the process control of the entire additive manufacturing process and is therefore the “brain” of the entire welding power source.
[0064] The wire feeding machine is responsible for adjusting the wire feeding speed. The wire feeding speed must be well matched with parameters such as the magnitude of current during additive manufacturing and the speed during fused deposition additive manufacturing so as to reduce the occurrence of welding defects, so the wire feeding speed must have a wide adjustment range to ensure the anti-interference performance and wire feeding stability of the wire feeding system.
[0065] The machine visual system is mainly used for realizing functions such as path identification, state monitoring, and tracking during the additive manufacturing process. The industrial computer mainly performs functions such as coordinated control over various parts of the system, hierarchical planning, and expert system.
[0066] The plasma welding gun mainly completes energy conversion so as to provide energy and power for wire fused deposition and transition of molten metal. The refrigerating device mainly provides cooling for the additive manufacturing power source and the plasma welding gun. The gas device mainly provides an ionized gas and a shielding gas. The auxiliary tooling fixture mainly performs functions such as clamping and displacement of the workpiece.
[0067] As shown in
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[0075] The working principle of the present invention is as follows:
[0076] firstly, selecting, by an industrial computer according to the characteristics of a workpiece and a wire therefor, a corresponding additive manufacturing mode and a basic process parameter supporting same; secondly, detecting, by a machine visual system, information of the workpiece to be additively manufactured and the position thereof, and feeding the information into the industrial computer and plan an additive path to coordinate the movements of an industrial robot and an auxiliary tooling fixture to corresponding workstations; and activating a refrigerating device and a gas device to prepare for the work of a plasma welding gun and an additive manufacturing power source. A three-phase power source supplies power to the additive manufacturing power source and a wire feeding machine to start an additive manufacturing work. A pilot-arc power source of the additive manufacturing power source works first, a high-frequency and high-voltage arc ignition circuit is used to generate a high-frequency and high-voltage signal to break down an air gap between a tungsten electrode and a nozzle of the plasma welding gun to establish and sustain an arc with a very small current. After the ignition of the arc is successful, a DSC controller of the pilot-arc power source sends a pilot-arc success signal to a controller of a main-arc power source, and the main-arc power source is activated to generate a transfer arc between the workpiece and the tungsten electrode. after the transfer arc is successful, the additive manufacturing system can turn off a pilot arc according to the requirements of materials and processes, so as to perform the additive manufacturing process in the case of the transfer arc; and The pilot arc can also continue to work, so as to form a mixed arc of the pilot arc and the transfer arc for additive manufacturing. The wire is fed stably by the wire feeding machine according to predetermined process requirements, and the wire is melted by a plasma arc jet generated by the plasma welding gun, and is stacked and shaped following the corresponding path. In order to finely control the amount of heat input and the amount of molten metal, an output waveform of the main-arc power source may have various shapes, including reverse polarity, variable polarity, pulse, etc. The wire feeding speed may also be constant or be a variable speed or change in a pulsating manner, etc. The state information of the industrial robot, the additive manufacturing power source, the wire feeding machine, the gas device, the auxiliary tooling fixture, etc. are fed into the industrial computer over the CAN bus network for data processing and remote centralized monitoring, thereby further improving the level of automation and intelligence of the additive manufacturing process.
[0077] Although the embodiments of the present invention have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.