CN113814543A - PTA welding method of double-path powder feeding electric arc mixed powder alloying - Google Patents
PTA welding method of double-path powder feeding electric arc mixed powder alloying Download PDFInfo
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Abstract
The invention discloses a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which comprises 1) electrifying equipment; 2) installing a workpiece; 3) filling materials; 4) installing a tungsten needle; 5) opening a pilot arc; 6) programming a robot; 7) welding programming; 8) starting welding; 9) and finishing welding and the like. The invention realizes the two-way powder feeding mixed welding, realizes the alloying of the electric arc mixed powder material during the welding, and evenly distributes the high-density hard phase between weld metal to obtain the high-quality wear-resistant weld.
Description
Technical Field
The invention relates to the field of welding, in particular to a PTA welding method of double-path powder feeding electric arc mixed powder alloying.
Background
At present, high-hardness wear-resistant alloy is needed in various industries, such as petroleum drilling, coal transportation, mining machinery and the like. In the application of wear-resistant materials, the general hard alloy with larger density such as WC, W2C and the like is preferred, the hardness can reach 1800HRC-2000HRC, the melting point is more than 3000 ℃, the density is more than 15g/cm3, the wear-resistant hard alloy is used as a wear-resistant hard phase and is collided with sandstone ore hardness to play a role in protecting a matrix, and the wear-resistant hard alloy can only be used as the hard phase because the wear-resistant hard alloy has high hardness and brittleness and cannot be combined with the matrix material. To ensure that the bonding with the base material is generally carried out using an adhesive phase, the choice will be made according to the environment of useCobalt-based and nickel-based materials with high temperature resistance and high hardness or iron-based materials with good toughness are used as bonding phases, and the density of the materials of the bonding phases is less than 8g/cm3The melting point is less than 1500 ℃, and the melting point is lower than that of a hard phase.
At present, bonding phase powder and hard phase powder with a set proportion are mixed according to requirements in the market, and the mixture is filled in a bottle and is led into a powder feeder to start welding, but a plurality of problems are caused, and the main reasons are as follows:
the process is as follows: in the welding process, a liquid molten pool is melted when cobalt-based or nickel-based of the liquid molten pool reaches a liquidus, WC and W2C cannot be melted and exist in the liquid molten pool in a solid state, the liquid molten pool can be settled to the bottom of the molten pool due to the large specific gravity, the WC and W2C can cause the root of a welding seam to have ultrahigh hardness and cause the welding layer to fall off after settlement, in addition, the upper half part of the welding seam after settlement has no hard phase, the outer surface of the welding seam at the moment is attractive but smooth without any small salient point, and the welding seam cannot play a wear-resisting role and loses the design effect due to the fact that the hard phase is too heavy and is settled. In practical operation, the mixed powder is generally subjected to overlaying welding by using 3 processes of PTA, laser cladding and flame spray welding, firstly, flame spray welding belongs to a brazing process, and the main problem is that the bonding force is insufficient, and a welding layer is peeled off in hard-to-hard friction. In addition, the flame can cause the decomposition of C and W due to the long heating time of WC and W2C, and the use is not possible. Secondly, the PTA process is a standard PTA powder feeding process, powder is fed in 2 holes, 4 holes or 6 holes and 12 holes, the powder is focused at one position, WC and W2C are extremely easy to settle and cannot be controlled during welding, the welding seam is generally wide in the industry at present to accelerate the solidification speed of a molten pool so as to ensure that a hard phase cannot settle, and the accessibility is reduced greatly, for example, a narrow welding seam cannot be used. Finally, laser cladding welding can solve the problem of hard phase sedimentation, but the effect of the laser cladding welding is similar to that of flame welding, the welding layer cannot be thickened due to insufficient bonding force, so that the peeling phenomenon is caused, and in addition, the welding efficiency of the laser cladding welding is too low, the equipment cost is high, and the production requirement cannot be met.
On the powder: the powder on the market can be mixed with the matrix phase and the hard phase according to the proportion requirement of customers, and the mixture is bottled and transported to be sent to the customers for use, wherein the weight of each bottle is 5 kg. In the process, 2 problems can be caused, firstly, the mixed powder is filled at a ratio of 5KG, after welding, metallographic microscopic amplification test and examination, the ratio of each bottle after welding can not be controlled to be the same, the error is within +/-4%, for example, cobalt base + 55% WC is needed, the ratio of actual WC in the cobalt base is only 49% -51%, the requirement on welding arcs is high due to larger difference of powder, and under the condition of the same welding parameters, the ratio of WC needs to be smaller and larger welding parameters need to be larger due to experiments. In addition, when the mixed powder is in transportation, due to the shaking of vehicles, WC and W2C powder in the bottle can be interlaminated to the bottom of the bottle due to the high density relationship, and when the mixed powder is directly used, segregation, namely uneven distribution of hard phases in welding seams, can be caused by the proportion of bonding phases and hard phases in welding seam metal. Through experimental tests, when the bottle mixed with the powder is placed on a plane and fixed, because the density of WC and W2C is high, the loose ratio of the powder is different from that of the bonding phase, WC and W2C can settle downwards along with the increase of time, and the proportion of the mixed powder is inconsistent. In the above 2 cases, the powder can not be used, mainly because the hard phase is unevenly distributed in the weld metal, which results in the wear resistance of the weld and even the block falling to affect the service state.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the defects and shortcomings of the prior art, the invention provides a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which realizes double-path powder feeding mixed welding, realizes electric arc mixed powder material alloying during welding, and uniformly distributes high-density hard phases among weld metal to obtain high-quality wear-resistant weld.
The technical scheme is as follows: the invention relates to a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which comprises the following steps:
1) powering on the equipment: powering on a six-axis robot, a plasma power supply, a welding control system, a welding power supply, a powder feeder, a robot control cabinet and a double-axis collaborative positioner, wherein the power supply is welding equipment, so that the welding equipment is in an editable action state;
2) installing a workpiece: installing a workpiece to be welded on the surface of a rotating shaft of the double-shaft cooperative positioner;
3) filling materials: adding first powder and second powder into a first powder feeding barrel and a second powder feeding barrel of a powder feeder respectively; a first lower powder opening of a nozzle for connecting the first powder pipe and the welding gun is used for the first powder in the first powder conveying barrel to pass through; a second powder outlet of a nozzle for connecting the second powder pipe and the welding gun is used for the second powder in the second powder conveying barrel to pass through; determining the number and the caliber of the first powder dropping port and the second powder dropping port according to the characteristics of the powder;
4) installing a tungsten needle: installing a tungsten needle in the welding gun, adjusting the position of the tungsten needle in the gas supply hole by using a tungsten needle adjusting tool, and opening plasma gas and welding protection gas;
5) opening a pilot arc: the HMI screen of the welding control system is used for opening maintenance, namely a plasma arc is opened, plasma current and plasma gas are started, and an electric arc appears at a plasma central hole of a welding gun;
6) robot programming: remotely controlling a six-axis robot, debugging a plasma nozzle at the lower end of a welding gun to a position 15-19 mm away from the surface of a workpiece to be welded, and setting an arc starting point and an arc ending point; debugging the first powder outlet to the front end in the welding direction, and debugging the second powder outlet to the rear end in the welding direction, so as to realize alloying of the electric arc powder mixing material during welding;
7) welding programming: debugging a welding process parameter curve, a gas process curve and a powder feeding parameter curve by using an HMI screen of a welding control system, and storing the parameters until the JOB calls the JOB or uses the welding process parameters on line;
8) starting welding: starting welding by using a robot demonstrator, starting a main arc by starting a welding power supply, and closing maintenance; in the welding process, the first powder sent out by the first powder feeding port is sent to the center of a welding arc, the robot melts the powder to form a welding seam liquid molten pool when welding to the front end, the second powder feeding port at the rear end sends the other material powder of the second powder feeding barrel to the surface of the liquid metal, and the other material powder is fused with the liquid metal melted by the first powder feeding port, metallurgically deposited and solidified to form a new material;
9) and (4) finishing welding: after the six-axis robot finishes the welding procedure, automatically stopping welding and executing an arc-withdrawing procedure of a welding control system to finish arc-withdrawing welding; closing the main arc and starting the maintenance state; the welding operation is completed.
The welding equipment comprises a robot system, a welding system and a powder feeding system; the robot system comprises a six-axis robot, a robot control cabinet and a double-axis cooperative positioner, wherein the robot control cabinet is respectively connected with the six-axis robot and the double-axis cooperative positioner through data lines; the welding system comprises a plasma power supply, a welding control system, a welding power supply, a welding gun and a water tank, wherein the welding control system is respectively connected with the plasma power supply and the welding power supply, the welding gun is a special plasma double-hole powder spray welding gun, and the welding gun is respectively connected with the plasma power supply, the welding power supply and the water tank; the powder feeding system comprises a powder feeder, a first powder pipe and a second powder pipe, wherein the powder feeder is a negative-pressure double-barrel powder feeder, the powder feeder is provided with a first powder feeding barrel and a second powder feeding barrel, the first powder feeding barrel is connected with a nozzle of a welding gun through the first powder pipe, and the second powder feeding barrel is connected with the nozzle of the welding gun through the second powder pipe; and the welding control system is respectively connected with the robot control cabinet and the powder feeder through data lines.
The nozzle is of a five-hole two-way water-cooling plasma nozzle structure, a first lower powder distributing groove and a second lower powder distributing groove are respectively arranged on the left side and the right side of the upper end face of the nozzle, an air supply hole penetrating through the nozzle is formed in the middle of the nozzle, and the nozzle is provided with a cooling water groove of an annular structure; the first powder distributing groove is connected with the first powder pipe, three first powder openings are formed in the first powder distributing groove, the first powder openings penetrate through the nozzle, the included angle between the bottom of each first powder opening and the horizontal plane is 45 degrees, and the included angle between the three first powder openings is 10 degrees; the second powder discharge chute is connected with a second powder pipe, two second powder discharge ports are formed in the second powder discharge chute and penetrate through the nozzle, the included angle between the bottom of each second powder discharge port and the horizontal plane is 66 degrees, and the included angle between the two second powder discharge ports is 10 degrees.
When the nozzle is used, first powder enters the nozzle through the first powder pipe, the first powder is guided to the lower end of the nozzle through the three first powder discharging ports at the first powder discharging diversion trench, and the three paths of first powder are discharged at an included angle of 45 degrees with the horizontal plane; the included angle between the first powder discharging openings is 10 degrees, the powder is sent out in a semicircular arc shape, and the powder is sent to the position 6mm-7mm right below the air feeding hole; the second powder enters the nozzle through the second powder pipe, the second powder is guided to the lower end of the nozzle through two second powder discharging ports at the second powder discharging distribution chute, the two paths of second powder are sprayed out at an included angle of 66 degrees with the horizontal plane, the included angle between the second powder discharging ports is 10 degrees, and when powder is fed, large-particle powder can be fed to a position 20mm below the air feeding hole.
The six-axis robot and the robot control cabinet form an arc welding robot, an arc welding software package is arranged in the arc welding robot, and the arc welding robot communicates with a welding machine through a communication protocol Pronfinet; the double-shaft cooperative positioner is provided with a turning shaft and a rotating shaft, the turning angle is smaller than 90 degrees, the rotating angle is stepless rotation, and the double-shaft cooperative positioner and the six-shaft robot perform eight-shaft TCP cooperative operation.
The welding control system is positioned between the welding power supply and the plasma power supply, is provided with HMI display, PLC and gas control hardware equipment in the plasma welding process, and controls a welding parameter curve, a gas parameter curve and a filling material curve in the welding process.
Wherein the plasma power supply is a FRONIUSTT2200 rated welding power supply, the current is 3A-220A, and the voltage is 0-35V; the welding power supply is a FRONIUSTT5000 rated welding power supply, the current is 3A-500A, and the voltage is 0-35V.
The first powder conveying barrel and the second powder conveying barrel have the capacity of 25L; the first powder pipe and the second powder pipe are anti-static pipes; the first powder outlet is of a bent structure.
Wherein the diameter of the upper opening of the nozzle is 60mm, and the diameter of the lower opening of the nozzle is 20 mm; the diameter of the air supply hole is 4 mm; the diameter of the first powder discharging opening is 1.2 mm; the diameter of the second powder outlet is 2 mm; the cooling water tank is located the air feed hole periphery, and the width of cooling water tank is 5mm, and the diameter of cooling water tank is 40 mm.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the invention provides a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which effectively solves the problem of WC and W2C sedimentation encountered in powder transportation, and mainly solves the problem that hard phase is easy to settle at the bottom of a molten pool in a welding process. The invention adopts the form of respective powder feeding of double barrels, the bonding phase and the hard phase correspond to one powder feeding barrel respectively, each powder feeding barrel can independently feed powder and gas, the powder mixing proportion is adjusted by adopting an independent powder curve, the powder feeding precision is high, the proportion precision of the arc mixed powder is high, and the error range of the tested precision is less than 1%. When the welding flux is used, the bonding phase is in front of the hard phase and in back of the bonding phase to form two kinds of welding metal powder arc alloying, and the high-density hard phase is uniformly distributed between weld metal to obtain a high-quality wear-resistant weld.
Meanwhile, the invention uses a high-precision negative pressure type double-barrel 25L powder feeder and an electric arc melting pool powder mixing alloying device for feeding powder in two paths of a PTA plasma nozzle double-hole bonding phase and a hard phase in a PTA powder spray welding system for the first time, and discloses a specific welding method. Provides a high-quality process for preventing powder segregation and provides a brand new idea for hardfacing.
Drawings
FIG. 1 is a schematic structural view of a welding apparatus of the present invention;
FIG. 2 is a view showing a state of use of the plasma nozzle according to the present invention;
FIG. 3 is a schematic view of the structure of the lower end surface of the plasma nozzle according to the present invention;
FIG. 4 is a schematic cross-sectional view of a plasma nozzle according to the present invention;
FIG. 5 is a schematic structural view of an upper end surface of the plasma nozzle according to the present invention;
FIG. 6 is a graph illustrating the effect of the embodiment of the present invention;
in the figure, 1 is a six-axis robot; 2 is a plasma power supply; 3 is a welding control system; 4 is a welding power supply; 5 is a powder feeder; 6 is a first powder feeding barrel; 7 is a second powder feeding barrel; 8 is a robot control cabinet; 9 is a biaxial cooperative positioner; 10 is a welding gun; 11 is a first powder tube; 12 is a second powder tube; 13 is a nozzle; 14 is second powder; 15 is a first powder; 16 is a first powder discharging port; 17 is a second powder outlet; 18 is a first dusting splitter box; 19 is a second powder feeding splitter box; 20 is a cooling water tank; 21 is an air supply hole; and 22 is a water tank.
Detailed Description
The technical solution of the present invention is further described with reference to the accompanying drawings and the detailed description.
The invention relates to a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which comprises the following steps:
1) powering on the equipment: the six-axis robot 1, the plasma power supply 2, the welding control system 3, the welding power supply 4, the powder feeder 5, the robot control cabinet 8 and the two-axis cooperative positioner 9 which are powered on to enable the welding equipment to be in an editable action state;
2) installing a workpiece: installing a workpiece to be welded on the surface of a rotating shaft of the biaxial collaborative positioner 9;
3) filling materials: respectively adding a first powder 15 and a second powder 14 into a first powder conveying barrel 6 and a second powder conveying barrel 7 of a powder feeder 5; a first powder outlet 16 which connects the first powder pipe 11 with a nozzle 13 of the welding gun 10 is used for the first powder 15 in the first powder conveying barrel 6 to pass through; a second lower powder opening 17 which connects the second powder pipe 12 with a nozzle 13 of the welding gun 10 is used for the second powder 14 in the second powder feeding barrel 7 to pass through; determining the number and the caliber of the first powder discharging port 16 and the second powder discharging port 17 according to the characteristics of the powder;
4) installing a tungsten needle: installing a tungsten needle in the welding gun 10, adjusting the position of the tungsten needle in the air supply hole 21 by using a tungsten needle adjusting tool, and opening plasma gas and welding protection gas;
5) opening a pilot arc: the HMI screen of the welding control system 3 is used for opening maintenance, namely a plasma arc is opened, plasma current and plasma gas are started, and an electric arc appears at a plasma central hole of the welding gun 10;
6) robot programming: remotely controlling the six-axis robot 1, debugging a plasma nozzle 13 at the lower end of a welding gun 10 to a position 15-19 mm away from the surface of a workpiece to be welded, and setting an arc starting point and an arc ending point; debugging the first powder outlet 16 to the front end in the welding direction, and debugging the second powder outlet 17 to the rear end in the welding direction to realize the alloying of the electric arc powder mixing material during welding;
7) welding programming: debugging a welding process parameter curve, a gas process curve and a powder feeding parameter curve by using an HMI screen of the welding control system 3, and storing the parameters until the JOB calls the JOB or uses the welding process parameters on line;
8) starting welding: starting welding by using a robot demonstrator, starting a welding power supply 4 to work, starting a main arc, and closing maintenance; in the welding process, the first powder 15 sent out by the first powder outlet 16 is sent to the center of a welding arc, when the robot welds to the front end, the powder is melted to form a welding seam liquid molten pool, the other material powder in the second powder sending barrel 7 is sent to the surface of the liquid metal by the second powder outlet 17 at the rear end, and is fused with the liquid metal melted by the first powder outlet 16 before, metallurgically deposited and solidified to form a new material;
9) and (4) finishing welding: after the six-axis robot 1 finishes the welding procedure, automatically stopping welding and executing an arc-closing procedure of the welding control system 3 to finish arc-closing welding; closing the main arc and starting the maintenance state; the welding operation is completed.
Furthermore, the welding equipment comprises a robot system, a welding system and a powder feeding system; the robot system comprises a six-axis robot 1, a robot control cabinet 8 and a double-axis cooperative positioner 9, wherein the robot control cabinet 8 is respectively connected with the six-axis robot 1 and the double-axis cooperative positioner 9 through data lines; the welding system comprises a plasma power supply 2, a welding control system 3, a welding power supply 4, a welding gun 10 and a water tank 22, wherein the welding control system 3 is respectively connected with the plasma power supply 2 and the welding power supply 4, the welding gun 10 is a special plasma double-hole powder spray welding gun, and the welding gun 10 is respectively connected with the plasma power supply 2, the welding power supply 4 and the water tank 22; the powder feeding system comprises a powder feeder 5, a first powder pipe 11 and a second powder pipe 12, wherein the powder feeder 5 is a negative-pressure double-barrel powder feeder, the powder feeder 5 is provided with a first powder feeding barrel 6 and a second powder feeding barrel 7, the first powder feeding barrel 6 is connected with a nozzle 13 of a welding gun 10 through the first powder pipe 11, and the second powder feeding barrel 7 is connected with the nozzle 13 of the welding gun 10 through the second powder pipe 12; the welding control system 3 is respectively connected with the robot control cabinet 8 and the powder feeder 5 through data lines.
Further, the nozzle 13 is of a five-hole two-way water-cooling plasma nozzle structure, the left side and the right side of the upper end face of the nozzle 13 are respectively provided with a first lower powder distributing groove 18 and a second lower powder distributing groove 19, the middle part of the nozzle 13 is provided with an air supply hole 21 penetrating through the nozzle 13, and the nozzle 13 is provided with a cooling water groove 20 of an annular structure; the first powder distributing groove 18 is connected with the first powder pipe 11, the first powder distributing groove 18 is provided with three first powder openings 16, the first powder openings 16 penetrate through the nozzle 13, the included angle between the bottom of each first powder opening 16 and the horizontal plane is 45 degrees, and the included angle between the three first powder openings 16 is 10 degrees; the second powder discharge chute 19 is connected with the second powder pipe 12, the second powder discharge chute 19 is provided with two second powder discharge ports 17, the second powder discharge ports 17 penetrate through the nozzle 13, the included angle between the bottom of the second powder discharge ports 17 and the horizontal plane is 66 degrees, and the included angle between the two second powder discharge ports 17 is 10 degrees.
The nozzle 13 is used as follows: the first powder 15 enters the nozzle 13 through the first powder pipe 11, the first powder 15 is guided to the lower end of the nozzle 13 through three first powder ports 16 at a first powder distributing groove 18, and three paths of first powder 15 are sprayed out at an included angle of 45 degrees with the horizontal plane; the included angle between the first powder discharging openings 16 is 10 degrees, the powder is sent out in a semicircular arc shape and is sent to the position 6mm-7mm right below the air feeding hole 21; the second powder 14 enters the nozzle 13 through the second powder pipe 12, the second powder 14 is guided to the lower end of the nozzle 13 through two second powder discharging ports 17 at the second powder discharging diversion trench 19, two paths of the second powder 14 are sprayed out at an included angle of 66 degrees with the horizontal plane, the included angle between the second powder discharging ports 17 is 10 degrees, and during powder feeding, large-particle powder can be fed to a position 20mm under the air feeding hole 21.
Further, the six-axis robot 1 and the robot control cabinet 8 form an arc welding robot, an arc welding software package is arranged in the arc welding robot, and the arc welding robot can communicate with a welding machine through a communication protocol Pronfinet; the double-shaft cooperative positioner 9 is provided with a turning shaft and a rotating shaft, the turning angle is smaller than 90 degrees, the rotating angle is stepless rotation, and the double-shaft cooperative positioner 9 and the six-shaft robot 1 perform eight-shaft TCP cooperative operation. The welding control system 3 is positioned between the welding power supply 4 and the plasma power supply 2, is provided with HMI display, PLC and gas control hardware equipment of the plasma welding process, and controls a welding parameter curve, a gas parameter curve and a filling material curve in the welding process. The plasma power supply 2 is a FRONIUSTT2200 rated welding power supply, the current is 3A-220A, and the voltage is 0-35V; the welding power supply 4 is a FRONIUSTT5000 rated welding power supply, the current is 3A-500A, and the voltage is 0-35V. The capacity of the first powder conveying barrel 6 and the second powder conveying barrel 7 is 25L; the first powder tube 11 and the second powder tube 12 are antistatic tubes; the first chalk opening 16 is a bent structure.
Further, the diameter of the upper opening of the nozzle 13 is 60mm, and the diameter of the lower opening of the nozzle 13 is 20 mm; the diameter of the air supply hole 21 is 4 mm; the diameter of the first powdering port 16 is 1.2 mm; the diameter of the second powder outlet 17 is 2 mm; the cooling water tank 20 is located at the periphery of the air supply hole 21, the width of the cooling water tank 20 is 5mm, and the diameter of the cooling water tank 20 is 40 mm.
The invention provides a PTA welding method of double-path powder feeding electric arc mixed powder alloying, which effectively solves the problem of WC and W2C sedimentation encountered in powder transportation, and mainly solves the problem that hard phase is easy to settle at the bottom of a molten pool in a welding process. The invention adopts the form of respective powder feeding of double barrels, the bonding phase and the hard phase correspond to one powder feeding barrel respectively, each powder feeding barrel can independently feed powder and gas, the powder mixing proportion is adjusted by adopting an independent powder curve, the powder feeding precision is high, the proportion precision of the arc mixed powder is high, and the error range of the tested precision is less than 1%. When the welding flux is used, the bonding phase is in front of the hard phase and in back of the bonding phase to form two kinds of welding metal powder arc alloying, and the high-density hard phase is uniformly distributed between weld metal to obtain a high-quality wear-resistant weld.
Meanwhile, the invention uses a high-precision negative pressure type double-barrel 25L powder feeder and an electric arc melting pool powder mixing alloying device for feeding powder in two paths of a PTA plasma nozzle double-hole bonding phase and a hard phase in a PTA powder spray welding system for the first time, and discloses a specific welding method. Provides a high-quality process for preventing powder segregation and provides a brand new idea for hardfacing.
Example (b):
the method is characterized in that a PTA process additive manufacturing NI60+ 50% WC powder surfacing with the thickness of 3mm is carried out at the position 25mm wide on the surface of the cutting edge of a straight scraper of ore sand mechanical equipment, the macroscopic hardness of a bonding phase is required to be larger than 55HRC after welding, WC is uniformly distributed on the surface of a welding seam, the inside of the welding seam and the bottom of the welding seam are microscopic 100 x without segregation, and the welding seam metal needs to have certain corrosion resistance requirements.
The length of the straight scraper is 200mm, the width of the straight scraper is 50mm, the thickness of the straight scraper is 15mm, the number of the straight scraper is 100, and the repeated positioning precision is required to be +/-0.1 mm. The mixed powder is fed by a single-cylinder conventional gravity type powder feeder, the service life of the product is short and is only one week, the replacement frequency is high, the wear form is that an alloy layer is not wear-resistant, and the metallographic phase shows that WC is distributed in a welding seam in a disordered and uneven manner.
The welding materials are required to be:
NI60 powder composition: c (1.0-0.6), Cr (14-17), B (2-4.5), Si (3-4.5), Fe (< 15), and Ni in balance;
WC powder components: w (95-96), LC (3.8-4.1) and trace elements in balance.
The PTA welding method adopting the double-way powder feeding electric arc mixed powder alloying of the invention comprises the following steps:
1) powering on the equipment: the six-axis robot 1, the plasma power supply 2, the welding control system 3, the welding power supply 4, the powder feeder 5, the robot control cabinet 8 and the two-axis cooperative positioner 9 which are powered on are connected with welding equipment, so that the welding equipment is in an editable action state.
2) Installing a workpiece: the straight scraper is arranged on the surface of a rotating shaft of the double-shaft cooperative positioner 9, so that the cutting edge of the straight scraper is upwards positioned at the PA position, the cutting edge is kept in an upward horizontal state, and the straight scraper is clamped to prevent the straight scraper from shaking all around.
3) Filling materials: the powder is screened by using a 80-150-mesh screen to remove smaller or larger powder in the powder before being filled into a powder feeding barrel by adopting a single bottle of NI60 powder and a single bottle of WC powder, the step is to prevent the larger powder from blocking a powder feeding port of the plasma nozzle 13, and in addition, the welding of the smaller powder is different from the welding of the larger powder. The screened powder is respectively poured into a first powder conveying barrel 6 and a second powder conveying barrel 7, namely NI60 powder is poured into the first powder conveying barrel 6, and WC powder is poured into the second powder conveying barrel 7; a first powder conveying barrel 6 and a second powder conveying barrel 7 of the negative pressure type double-barrel powder feeder are respectively connected with a first powder outlet 16 and a second powder outlet 17 of an upper welding gun 10 through antistatic pipes, so that the first powder outlet 16 can independently convey NI60 powder, and the second powder outlet 17 can independently convey WC powder.
The diameters of the three first powder discharging openings 16 are 1.2 mm; the diameter of the two second powder outlet 17 is 2 mm; the included angle between the bottom of the first powdering port 16 and the horizontal plane is 45 degrees, and the included angle between the three first powdering ports 16 is 10 degrees; the included angle between the bottom of the second powder outlet 17 and the horizontal plane is 66 degrees, and the included angle between the two second powder outlets 17 is 10 degrees.
The diameter of the upper opening of the nozzle 13 is 60mm, and the diameter of the lower opening of the nozzle 13 is 20 mm; the diameter of the air feed hole 21 is 4 mm.
4) Installing a tungsten needle: the diameter of the tungsten needle is selected to be 4.0-4.8 mm, the tungsten needle is inserted into the air supply hole 21, the position of the tungsten needle in the air supply hole 21 is adjusted by using a tungsten needle adjusting tool, and the plasma gas and the welding protection gas are opened.
5) Opening a pilot arc: setting plasma current 10A and plasma gas 1.5L/min by using an HMI screen of the welding control system 3, opening maintenance, namely opening plasma arc, starting the plasma current and the plasma gas, and generating electric arc at a plasma central hole of the welding gun 10.
6) Robot programming: remotely controlling the six-axis robot 1, debugging a plasma nozzle 13 at the lower end of a welding gun 10 to a position 15-19 mm away from the surface of a workpiece to be welded, and setting one end of a straight scraper as an arc starting point and the other end as an arc withdrawing point; and debugging the first lower powder opening 16 of the NI60 powder to the front end in the welding direction, and debugging the second lower powder opening 17 of the WC powder to the rear end in the welding direction, so as to realize the alloying of the electric arc mixed powder material during welding.
7) Welding programming: debugging a welding process parameter curve, a gas process curve and a powder feeding parameter curve by using an HMI screen of the welding control system 3, and storing the parameters until the JOB calls the JOB or uses the welding process parameters on line; according to the liquidus temperature of NI60 powder, welding specification parameters should be reduced during welding, and welding current 110A, welding speed 120mm/min, NI60 powder feeding amount 8g/min, WC powder feeding amount 8g/min, plasma gas 2L/min during welding, plasma current 15A, shielding gas 15L/min, NI60 powder feeding gas flow 2L/min, WC powder feeding gas flow 4L/min, swing width 11mm, swing frequency 0.7HZ, and swing left and right stay for 0.3S are set. The robot is used to invoke the parameter mode online.
8) Starting welding: starting welding by using a robot demonstrator, starting a welding power supply 4 to work, starting a main arc, and closing maintenance; in the welding process, the NI60 powder sent by the first powder outlet 16 is sent to the center of a welding arc to be melted to form a welding seam liquid molten pool, when the robot moves towards the front end, the second powder outlet 17 at the rear end can send the WC powder of the second powder sending barrel 7 to the surface of liquid metal, and the WC powder is rapidly solidified about 0.4S after being just scattered to the surface of the welding seam liquid molten pool to form a new alloying material. C (1.3-1.8), WC (49-51), Cr (14-17), B (2-4.5), Si (2.5-3), Fe (15-20), and Ni (balance), namely nickel-based tungsten carbide.
9) And (4) finishing welding: after the six-axis robot 1 finishes the welding procedure, the welding is automatically stopped, and the arc-closing procedure of the welding control system 3 is executed to finish the arc-closing welding; closing the main arc and starting the maintenance state; the welding operation is completed.
10) Workpiece replacement: and (3) taking away the welded reamer on the biaxial collaborative positioner 9, installing a new reamer, clamping to enable the position of the new reamer to be the same as that of the new reamer, starting to weld a switch button on the robot demonstrator, repeatedly operating, finishing welding all 99 parts by the robot, and ensuring the required repeated positioning precision by using the robot.
Analysis of use effect: during welding, the swing width is 11mm, when the robot swings to the edge and stays for 0.3S, the electric arc can spread to the edge by itself to ensure the full and round welding line. The existing time of the liquid molten pool in motion is short, the robot can swing uniformly to enable the welded metal surface to be in a fish scale pattern shape, and dense and hemp raised points, namely WC hard phases, are arranged on the surface of a welding line. After welding, cutting samples are subjected to 100X detection on the surface of a weld joint of the weld joint NI60, WC is uniformly distributed in the weld joint and at the bottom of the weld joint, no defects such as air holes exist, the service life of the reamer manufactured by the novel electric arc powder mixing process is prolonged by 3 times compared with that of the reamer manufactured by the prior art through customer use feedback, and a good use effect is obtained.
Claims (9)
1. A PTA welding method of double-path powder feeding electric arc mixed powder alloying is characterized in that: the method comprises the following steps:
1) powering on the equipment: the six-axis robot (1), the plasma power supply (2), the welding control system (3), the welding power supply (4), the powder feeder (5), the robot control cabinet (8) and the two-axis cooperative positioner (9) which are powered on and are welding equipment are powered on, so that the welding equipment is in an editable action state;
2) installing a workpiece: installing a workpiece to be welded on the surface of a rotating shaft of the biaxial collaborative positioner (9);
3) filling materials: adding a first powder (15) and a second powder (14) into a first powder conveying barrel (6) and a second powder conveying barrel (7) of a powder feeder (5) respectively; a first powder discharging port (16) which is connected with the first powder pipe (11) and a nozzle (13) of the welding gun (10) is used for the first powder (15) in the first powder conveying barrel (6) to pass through; a second powder outlet (17) which is connected with the second powder pipe (12) and a nozzle (13) of the welding gun (10) is used for the second powder (14) in the second powder conveying barrel (7) to pass through; determining the number and the caliber of the first powder dropping port (16) and the second powder dropping port (17) according to the characteristics of the powder;
4) installing a tungsten needle: installing a tungsten needle in a welding gun (10), adjusting the position of the tungsten needle in the air supply hole (21) by using a tungsten needle adjusting tool, and opening plasma gas and welding protection gas;
5) opening a pilot arc: the HMI screen of the welding control system (3) is used for opening maintenance, namely a plasma arc is opened, plasma current and plasma gas are started, and an electric arc appears at a plasma central hole of the welding gun (10);
6) robot programming: remotely controlling a six-axis robot (1), debugging a plasma nozzle (13) at the lower end of a welding gun (10) to a position 15-19 mm away from the surface of a workpiece to be welded, and setting an arc starting point and an arc stopping point; debugging the first powder outlet (16) to the front end in the welding direction, and debugging the second powder outlet (17) to the rear end in the welding direction, so as to realize the alloying of the electric arc powder mixing material during welding;
7) welding programming: debugging a welding process parameter curve, a gas process curve and a powder feeding parameter curve by using an HMI screen of the welding control system (3), and storing the parameters until the JOB calls the JOB or uses the welding process parameters on line;
8) starting welding: starting welding by using a robot demonstrator, starting a welding power supply (4) to work, starting a main arc, and closing maintenance; in the welding process, the first powder (15) sent out by the first powder outlet (16) is sent to the center of a welding arc, when the robot welds to the front end, the powder is melted to form a welding seam liquid molten pool, the other material powder in the second powder sending barrel (7) is sent to the surface of the liquid metal by the second powder outlet (17) at the rear end, and is fused with the liquid metal melted by the first powder outlet (16) before, metallurgically deposited and solidified to form a new material;
9) and (4) finishing welding: after the six-axis robot (1) finishes the welding procedure, the welding is automatically stopped, and the arc-closing procedure of the welding control system (3) is executed to complete the arc-closing welding; closing the main arc and starting the maintenance state; the welding operation is completed.
2. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the welding equipment comprises a robot system, a welding system and a powder feeding system; the robot system comprises a six-axis robot (1), a robot control cabinet (8) and a double-axis cooperative positioner (9), wherein the robot control cabinet (8) is respectively connected with the six-axis robot (1) and the double-axis cooperative positioner (9) through data lines; the welding system comprises a plasma power supply (2), a welding control system (3), a welding power supply (4), a welding gun (10) and a water tank (22), wherein the welding control system (3) is respectively connected with the plasma power supply (2) and the welding power supply (4), the welding gun (10) is a special plasma double-hole powder spray welding gun, and the welding gun (10) is respectively connected with the plasma power supply (2), the welding power supply (4) and the water tank (22); the powder feeding system comprises a powder feeder (5), a first powder pipe (11) and a second powder pipe (12), the powder feeder (5) is a negative-pressure double-barrel powder feeder, the powder feeder (5) is provided with a first powder feeding barrel (6) and a second powder feeding barrel (7), the first powder feeding barrel (6) is connected with a nozzle (13) of a welding gun (10) through the first powder pipe (11), and the second powder feeding barrel (7) is connected with the nozzle (13) of the welding gun (10) through the second powder pipe (12); and the welding control system (3) is respectively connected with the robot control cabinet (8) and the powder feeder (5) through data lines.
3. The PTA welding method of two-way powder feeding electric arc mixed powder alloying according to claim 1 or 2, wherein: the nozzle (13) is of a five-hole two-way water-cooling plasma nozzle structure, the left side and the right side of the upper end surface of the nozzle (13) are respectively provided with a first lower powder distributing groove (18) and a second lower powder distributing groove (19), the middle part of the nozzle (13) is provided with an air feeding hole (21) penetrating through the nozzle (13), and the nozzle (13) is provided with a cooling water tank (20) of an annular structure; the first dusting shunting groove (18) is connected with the first powder pipe (11), the first dusting shunting groove (18) is provided with three first dusting ports (16), the first dusting ports (16) penetrate through the nozzle (13), the included angle between the bottom of each first dusting port (16) and the horizontal plane is 45 degrees, and the included angle between the three first dusting ports (16) is 10 degrees; powder splitter box (19) are connected with second powder pipe (12) under the second, and powder splitter box (19) has seted up two second under powder mouth (17) under the second, and powder mouth (17) run through nozzle (13) under the second, and powder mouth (17) bottom is 66 with horizontal angle under the second, and the contained angle between two second under powder mouth (17) is 10.
4. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 3, characterized in that: when the nozzle (13) is used, first powder (15) enters the nozzle (13) through the first powder pipe (11), the first powder (15) is guided to the lower end of the nozzle (13) through the three first powder openings (16) at the first powder dividing groove (18), and the three first powder (15) are sprayed out at an included angle of 45 degrees with the horizontal plane; the included angle between the first powder discharging ports (16) is 10 degrees, the powder is sent out in a semicircular arc shape and is sent to the position 6mm-7mm right below the air feeding hole (21); the second powder (14) enters the nozzle (13) through the second powder pipe (12), the second powder (14) is guided to the lower end of the nozzle (13) through two second powder discharging openings (17) at the second powder discharging diversion trench (19), two paths of second powder (14) are sprayed out at an included angle of 66 degrees with the horizontal plane, the included angle between the second powder discharging openings (17) is 10 degrees, and when powder is fed, large-particle powder can be fed to a position 20mm right below the air feeding hole (21).
5. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the six-axis robot (1) and the robot control cabinet (8) form an arc welding robot, an arc welding software package is arranged in the arc welding robot, and the arc welding robot communicates with a welding machine through a communication protocol Pronfinet; the double-shaft cooperative positioner (9) is provided with a turning shaft and a rotating shaft, the turning angle is smaller than 90 degrees, the rotating angle is stepless rotation, and the double-shaft cooperative positioner (9) and the six-shaft robot (1) perform eight-shaft TCP cooperative operation.
6. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the welding control system (3) is positioned between the welding power supply (4) and the plasma power supply (2), is provided with HMI display, PLC and gas control hardware equipment in the plasma welding process, and controls a welding parameter curve, a gas parameter curve and a filling material curve in the welding process.
7. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the plasma power supply (2) is a FRONIUTT 2200 rated welding power supply, the current is 3A-220A, and the voltage is 0-35V; the welding power supply (4) is a FRONIUSTT5000 rated welding power supply, the current is 3A-500A, and the voltage is 0-35V.
8. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the capacity of the first powder conveying barrel (6) and the second powder conveying barrel (7) is 25L; the first powder pipe (11) and the second powder pipe (12) are anti-static pipes; the first powder outlet (16) is of a bent structure.
9. The PTA welding method of the two-way powder feeding electric arc powder mixing alloying of claim 1, which is characterized in that: the diameter of the upper opening of the nozzle (13) is 60mm, and the diameter of the lower opening of the nozzle (13) is 20 mm; the diameter of the air supply hole (21) is 4 mm; the diameter of the first powdering port (16) is 1.2 mm; the diameter of the second powder outlet (17) is 2 mm; the cooling water tank (20) is located on the periphery of the air supply hole (21), the width of the cooling water tank (20) is 5mm, and the diameter of the cooling water tank (20) is 40 mm.
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