CN103586571A

CN103586571A - Device and method for improving quality of aluminum alloy plasma arc welded joint

Info

Publication number: CN103586571A
Application number: CN201310603977.8A
Authority: CN
Inventors: 杜宝帅; 张忠文; 李新梅
Original assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Priority date: 2013-11-25
Filing date: 2013-11-25
Publication date: 2014-02-19
Anticipated expiration: 2033-11-25
Also published as: CN103586571B

Abstract

The invention discloses a device and method for improving the quality of aluminum alloy plasma arc welding joints, including a plasma arc welding machine, the plasma arc welding machine includes a plasma arc welding gun and a plasma arc welding gun nozzle connected with the plasma arc welding gun and located below it, and The welding torch is connected with the ultrasonic vibrating rod through the connecting device, the vibrating unit includes a transducer, an ultrasonic vibrating rod and an ultrasonic tool head connected in sequence, and the transducer is connected with the ultrasonic generator. Under the premise of not changing the original equipment, the ultrasonic vibration is directly applied around the weld through the auxiliary device, and the ultrasonic vibration is used to increase the overflow of bubbles, so as to achieve the purpose of reducing welding defects and improving welding quality.

Description

Improve the device and method of aluminium alloy PLASMA ARC WELDING joint quality

Technical field

The present invention relates to improve the device and method of aluminium alloy PLASMA ARC WELDING joint quality.

Background technology

Aluminium alloy, with its good physics, chemistry and mechanical performance, more and more for all types of industries product, is particularly widely used in Aero-Space, electronics and automobile industry.As important hot-working means of aluminium alloy application, welding has extremely important status.With respect to the welding of steel, Welded difficulty is higher, and welding point is prone to defect, and main problem is that aluminium is easily oxidized and causes oxide slag inclusion, also easily occurs in addition pore, defects i.e.cracks.

PLASMA ARC WELDING is the new welding technology getting up in immediate development, has heat input few, and energy density is concentrated, heat affected area is out of shape little advantage.And, because plasma-arc has higher energy density than common electric arc, utilize its keyhole effect can carry out the welding of large slab, thereby plasma arc welding (PAW) is connected on and in industrial production, have increasing application.Yet when plasma arc is used for welding aluminum alloy,, there is the more serious problem of gas hole defect in the 5XXX series that particularly Mg content is higher.This is due to for the higher aluminium alloy of Mg content, in welding process, except easy formation aluminium oxide, also easily form magnesia, and magnesia is not due to fine and close, more easily absorbs moisture, causes in molten bath, forming in welding process pore.In addition, due to plasma arc high-energy-density and relatively high speed of welding, welding pool solidifies comparatively fast, and gas has little time to overflow, and this has further aggravated to form the tendency of pore.

So far, the way addressing this problem is to add fierce front surface treatment, comprises with chemical method and mechanical means and cleans the surface of welded aluminium alloy and wlding and welding as early as possible after having cleaned.Yet still exist in practical operation, clean and a lot of external factors of the asynchronous grade of welding.Especially when welding ambient humidity is larger, the moisture in atmosphere forms higher arc column hydrogen-pressure by being involved in electric arc, thereby causes higher pore formability, clears up merely workpiece and welding wire and is often difficult to solve pore problem.

Ultrasonic wave is a kind of of sound wave, has the features such as frequency is high, penetration capacity is strong, when ultrasonic, applies pressure to during material, can change the constitutive relation of material, even produces the effects such as high temperature and dither.Therefore in the process of welding, utilize the feature that ultrasonic wave penetration capacity is strong, near welding pool, apply a ultrasonic dither, under certain power, can change the process of setting in molten bath, the fuel factor of its generation can postpone solidifying of molten bath, is conducive to overflowing of bubble, and dither is also conducive to crystallization of refinement process simultaneously, obtaining the tiny seam organization of crystal grain, is favourable for improving Weld Performance.Existing invention at present combines ultrasonic vibration with friction stir welding, mainly utilized ultrasonic vibration to reduce the resistance of deformation of material, reaches the object that increases welding efficiency, improves welding quality.But for ultrasonic vibration is combined to reduce in aluminum alloy welding termination process with PLASMA ARC WELDING, produce pore tendency, the research that improves quality of weld joint, have not been reported.

Summary of the invention

The deficiency existing for solving prior art, the invention discloses the device and method that improves aluminium alloy PLASMA ARC WELDING joint quality, do not changing under the prerequisite of existing equipment, by servicing unit, directly ultrasonic vibration is applied to around weld seam, utilize ultrasonic vibration not only can increase overflowing of facilitated bubble, but also can crystal grain thinning, thereby reach minimizing weld defect, improve the object of welding quality.

For achieving the above object, concrete scheme of the present invention is as follows:

Improve the device of aluminium alloy PLASMA ARC WELDING joint quality, comprise plasma arc welder, plasma arc welder comprise plasma (welding) torch and be connected with plasma (welding) torch and be positioned at its below PLASMA ARC WELDING rifle nozzle, plasma (welding) torch is connected with Under Ultrasonic Vibration lever by jockey, vibration unit comprises transducer, Under Ultrasonic Vibration lever and the Ultrasonic probe connecting successively, and transducer is connected with supersonic generator.

Described plasma arc welder is plasma arc welding with adjustable polarity parameters machine.

Described jockey is the fixture of horizontal positioned.

Supersonic generator is converted to superaudible high frequency ac signal by industrial-frequency alternating current, then converts electrical energy into ultrasonic mechanical vibrational energy through transducer, imports ultrasonic wave, and in welding process, remain hyperacoustic importing by Ultrasonic probe from region to be welded.

The method of improving aluminium alloy PLASMA ARC WELDING joint quality, comprises the following steps:

Step 1: test plate (panel) is utilized before weldering cleaning plant carry out mechanical chipping; Test plate (panel) is docked and fixed with fixture, and abutting direction is along welding direction;

Step 2: the distance and the angle that regulate vibration unit and PLASMA ARC WELDING rifle nozzle, the Ultrasonic probe end of vibration unit is 0.5-3cm with the distance of PLASMA ARC WELDING rifle nozzle, vibration unit axis is 20 degree-70 degree with the angle of plasma (welding) torch axis, PLASMA ARC WELDING rifle nozzle is perpendicular to test plate (panel) and apart from the distance range 0-2 centimetre of test plate (panel), according to different equipment, this distance is selected the best distance that produces aperture, ultrasonic vibration vibration of bar frequency 10-100KHz, amplitude 10-100um, ultrasonic power 200-2000W;

Step 3: setting welding parameter is, welding current 100-400A, speed of welding 10-60 millimeter per minute, plasma gas flow rate 1-3 Liter Per Minute;

Step 4: start gauge tap, import ultrasonic wave by Ultrasonic probe from region to be welded, and remain hyperacoustic importing in welding process.

Cleaning plant in described step 1 is angle grinding machine.

Under Ultrasonic Vibration lever is connected with PLASMA ARC WELDING rifle by fixture, and distance and the angle of capable of regulating vibration unit and PLASMA ARC WELDING rifle nozzle, can guarantee that vibration unit moves with plasma (welding) torch, and at motion process, guarantee the distance of Ultrasonic probe and PLASMA ARC WELDING rifle nozzle.

Beneficial effect of the present invention:

Aluminium alloy PLASMA ARC WELDING easily causes occurring pore in weld seam, and coarse grains problem causes quality of weld joint to decline, and therefore how to improve aluminium alloy PLASMA ARC WELDING joint quality is engineering circles study hotspot always.The present invention is not changing under the prerequisite of original PLASMA ARC WELDING equipment, and the ultrasonic servicing unit contacting with workpiece by increase is applied to ultrasonic vibration around weld seam.Adopt this kind of mode ultrasonic wave to propagate in workpiece and can effectively arrive at liquid state of molten pool metal, its dither brings mechanism to liquid state of molten pool metal, heat effect, cavitation and acoustic streaming effect, and then affect pore forming core, grow up and molten pool metal crystallization behavior.The heat effect that ultrasonic vibration produces, mechanism and acoustic pressure gradient effect will play mechanical agitation to molten pool metal, promote that liquid metal produces strong convection current, the pore forming in molten bath has higher effusion speed, and pore gathers growth tendency and significantly reduced, so the tendency that produces pore in weld seam will significantly improve.On the other hand, ultrasonic vibration can the thick dendrite of fragmentation along fusion area, molten bath to growth inside, reduce dendrite size, and fragmentation dendrite can be used as equiax crystal forming core core, thereby proportion of equiaxed grain in weld metal is significantly improved, and then improve welding joint mechanical property.In welding process, the ultrasonic vibration device increasing can be in company with welding gun synchronous walking, and ultrasonic vibration effect is not affected by welding gun movement velocity, the heat effect that it brings and mechanical agitation can, so that aluminium alloy plasma arc welding (PAW) is connected under higher speed of welding to be implemented, improve PLASMA ARC WELDING efficiency.

Accompanying drawing explanation

Fig. 1 apparatus structure schematic diagram of the present invention;

In figure, 1 plasma (welding) torch, 2 PLASMA ARC WELDING rifle nozzles, 3 jockeys, 4 Under Ultrasonic Vibration levers, 5 Ultrasonic probes, 6 test plate (panel)s, 7 supersonic generators, 8 transducers.

The specific embodiment:

Below in conjunction with accompanying drawing, the present invention is described in detail:

As shown in Figure 1, improve the device of aluminium alloy PLASMA ARC WELDING joint quality, comprise plasma arc welder, plasma arc welder comprise plasma (welding) torch 1 and be connected with plasma (welding) torch 1 and be positioned at its below PLASMA ARC WELDING rifle nozzle 2, plasma (welding) torch 1 is connected with Under Ultrasonic Vibration lever 4 by jockey 3, vibration unit comprises transducer 8, Under Ultrasonic Vibration lever 4 and the Ultrasonic probe 5 connecting successively, and transducer 8 is connected with supersonic generator 7.

The fixture that described jockey 3 is horizontal positioned.

Supersonic generator 7 is converted to superaudible high frequency ac signal by industrial-frequency alternating current, through transducer 8, convert electrical energy into ultrasonic mechanical vibrational energy again, by Ultrasonic probe 5, from region to be welded, import ultrasonic wave, and in welding process, remain hyperacoustic importing.

Step 1: utilize cleaning plant to carry out mechanical chipping before weldering test plate (panel) 6; Test plate (panel) 6 docking are fixed with fixture, and abutting direction is along welding direction;

Step 2: the distance and the angle that regulate vibration unit and PLASMA ARC WELDING rifle nozzle 2, Ultrasonic probe 5 ends of vibration unit are 0.5-3cm with the distance of PLASMA ARC WELDING rifle nozzle 2, vibration unit axis is 20 degree-70 degree with the angle of plasma (welding) torch 1 axis, PLASMA ARC WELDING rifle nozzle 2 is apart from the distance range 0-2 centimetre of test plate (panel) 6, according to different equipment, this distance is selected the best distance that produces aperture, and angle is perpendicular to test plate (panel) 6; Ultrasonic vibration vibration of bar frequency 10-100KHz, amplitude 10-100um, ultrasonic power 200-2000W.

Step 3: setting welding parameter is, welding current 100-400A, speed of welding 10-60 millimeter per minute, plasma gas flow rate 1-3 Liter Per Minute.

Step 4: start gauge tap, import ultrasonic wave by Ultrasonic probe 5 from region to be welded, and remain hyperacoustic importing in welding process.

Cleaning plant in described step 1 is angle grinding machine.

Under Ultrasonic Vibration lever 4 is connected with plasma (welding) torch 1 by fixture, and distance and the angle of capable of regulating vibration unit and PLASMA ARC WELDING rifle nozzle 2, can guarantee that vibration unit is with plasma (welding) torch 1 motion, and at motion process, guarantee the distance of Ultrasonic probe 5 and PLASMA ARC WELDING rifle nozzle 2.

Embodiment:

(1) comparative example:

Adopting 5083 aluminium sheets of 10 millimeters of thickness is welded piece, the docking test plate (panel) of wide 10cm, long 25cm, weldering front surface carries out simple and mechanical cleaning with angle grinding machine, and Plasma Welding parameter is: ion-gas 1.39L/min forward current 260A, reverse 290A, 40 millimeters per minute of speed of welding.

Postwelding adopts Ultrasonic Nondestructive to carry out pore ranking, is three grades, and pore mainly concentrates near melt run, and cross section is visible obviously gross blow hole sometimes.

(2) welding parameter is the same with comparative example, and difference is to add ultrasonic vibration, and ultrasonic vibration vibration of bar frequency is 30KHz, and amplitude is 50um, and Ultrasonic probe is 5 millimeters of places in welding pool the place ahead.It is one-level that postwelding Ultrasonic NDT is carried out pore ranking, and cross section is without the obvious visible pore of naked eyes.

Claims

1. The device for improving the quality of aluminum alloy plasma arc welding joints is characterized in that it includes a plasma arc welding machine, the plasma arc welding machine includes a plasma arc welding torch and a plasma arc welding torch nozzle connected to the plasma arc welding torch and positioned below it, and the plasma arc welding torch The welding torch is connected with the ultrasonic vibrating rod through the connecting device, the vibrating unit includes a transducer, an ultrasonic vibrating rod and an ultrasonic tool head connected in sequence, and the transducer is connected with the ultrasonic generator.

2. The device for improving the quality of aluminum alloy plasma arc welding joints according to claim 1, wherein the plasma arc welding machine is a variable polarity plasma arc welding machine.

3. The device for improving the quality of aluminum alloy plasma arc welding joints according to claim 1, characterized in that, the connecting device is a clamp placed horizontally.

4. The method for improving the quality of aluminum alloy plasma arc welding joints as claimed in claim 1, characterized in that, comprising the following steps:

Step 1: Clean the test plate mechanically with a cleaning device before welding; fix the test plate butt joint with a fixture, and the butt joint direction is along the welding direction;

Step 2: Adjust the distance and angle between the vibration unit and the nozzle of the plasma arc welding gun. The distance between the end of the ultrasonic tool head of the vibration unit and the nozzle of the plasma arc welding gun is 0.5-3cm, and the angle between the axis of the vibration unit and the axis of the plasma arc welding gun is 20 degrees. -70 degrees, the plasma arc welding gun nozzle is perpendicular to the test plate and the distance from the test plate is 0-2 cm, the vibration frequency of the ultrasonic vibration rod is 10-100KHz, the amplitude is 10-100um, and the ultrasonic power is 200-2000W;

Step 3: Set the welding parameters as follows: welding current 100-400A, welding speed 10-60 mm per minute, plasma gas flow 1-3 liters per minute;

Step 4: Start the control switch, and the ultrasonic tool head will introduce ultrasonic waves from the area to be welded, and keep the introduction of ultrasonic waves during the welding process.

5. The method according to claim 4, characterized in that, the cleaning device in the first step is an angle grinder.