CN1778513A

CN1778513A - Welding joint structure and welding method for thin-wall and small-diameter aluminium alloy pipe

Info

Publication number: CN1778513A
Application number: CN 200410084415
Authority: CN
Inventors: 茅鹏; 徐国祥
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2004-11-22
Filing date: 2004-11-22
Publication date: 2006-05-31
Anticipated expiration: 2024-11-22
Also published as: CN100434227C

Abstract

A jointer structure of thin-wall small-diameter Al-alloy pipe to be welded features that the one end of a Al-alloy pipe to be welded is mechanically cupred to form a recess shape. Its welding method includes such steps as inserting another Al-alloy pipe in said recess, putting a red copper sleeve pipe in them, fixing them by two copper clampers, and welding.

Description

Thin-walled small-diameter aluminium alloy pipe joint structure and welding and welding method thereof

Technical field

The invention belongs to a kind of joint construction of Metal Material Welding.Specifically, be novel joint construction and the welding method that belongs to a kind of thin-walled small-diameter aluminium alloy pipe welding.

Background technology

Present refrigerator, the condenser system of chilling units such as air-conditioning all is that the employing red copper is a conduit, because red copper is than great, the price height, make the production cost of condenser system high, if adopt the thin-walled small-diameter aluminium alloy pipe to substitute copper tube, so, just the production cost of condenser system can reduce more than 80%.Because the proportion of aluminium alloy only is 1/3rd of red copper, its unit price than low 1.5 times of red copper, that is to say that the amount of money of buying one ton of copper tube can be used for buying 5 tons of aluminium-alloy pipes again.So just, can improve the competitiveness of chilling units such as very thin refrigerator of profit and air-conditioner greatly.

But the thin-walled small-diameter aluminium alloy pipe substitutes copper tube, and wherein Zui Da difficulty is to resolve its joint Welding Problems.Resolve the joint welding, one of technology of most critical is that a kind of novel joint construction will be arranged, and the joint of two small-diameter aluminium alloy pipes is two pipes to be docking together straightly traditionally.Its pad has only circle of pipe section, must add welding wire during butt welding, and the welding point protuberance of postwelding is serious, easily causes stress to concentrate, and bearing under the pressure state, easily produces fatigue crack.When welding inside be difficult for through welding, easily produce pore and assorted slag, one careless will burn-through, this manual welding is difficult to weld, and production efficiency is also very low.

Therefore, adopt aluminium alloy thin-walled tubule to substitute copper pipe, matter of utmost importance is to resolve high-quality pipe joint Welding Problems, resolve problems of welded quality, it at first will have a kind of novel joint construction, makes it have maximum solder side, can not make weld flush again without welding wire.

Summary of the invention:

The objective of the invention is to design a kind of novel joint construction and method thereof that is suitable for the butt joint of thin-walled small-diameter aluminium alloy pipe, make and have only a section pad originally, become the pad on a section and a plane.During welding without welding wire, it is uneven to have overcome the welding point protuberance that exists in the prior art, easily producing stress concentrates, inside is difficult for through welding and easily produces defectives such as pore and assorted slag, realized the automation welding, both improved welding quality, improved welding efficiency again, and made aluminium-alloy pipe substitute copper tube and become a reality.

The objective of the invention is to implement by following technological means:

Joint structure and welding at first of the present invention is: wait to connect copper sheathing of aluminium-alloy pipe seam crossing liner described two, and a beading tube ends becomes concavity therein, or overcoat one small casing, thereby form joint structure and welding.

Specific implementation method:

The first step: the end face cutting that will treat welded tube is smooth.

Second step: the end that will treat welded tube makes with mechanical flange and becomes concavity.

The 3rd step: process a bit of red copper sleeve pipe, neck bush during as welding.

The 4th step: control the straight end of welded tube and insert recess, making becomes structure of the present invention.

The 5th step: on two three-jaw chucks, is the melt of regulating weldpool with the connector clamp that assembles, specialized designs three copper chucks that are contained on the scroll chuck of easy heat radiation.

The 6th step; During welding, adopt the tungsten electrode ac argon arc weld, under the inert gas protection, finish welding.Adopt the welding of tungsten electrode ac argon arc weld.During welding,, weld a circle with the little electric current of 20-32 ampere earlier, use big electric current weldering 1～2 circle of 50-55 ampere again the central point of welding gun aligning joint, weld less than 1 circle with decay current then.

Wherein, above-mentioned second step also can adopt overcoat one small casing in the method for seam crossing.

Advantage of the present invention:

Because novel joint construction has increased bonding area greatly, the joint quality reliability has improved greatly, has avoided manual welding easily to cause joint end through welding, weld flush injustice, easily cause stress to concentrate, easily produce bubble, residue, and because wayward quality problems such as burn-through that cause of heat.Because the present invention has adopted novel joint construction must not use welding wire, can realize the automation welding again, make aluminium-alloy pipe substitute copper tube and become a reality, both reduced welding cost, also reduce the production cost of condenser system simultaneously.

Description of drawings

Fig. 1, thin-walled small-diameter aluminium alloy pipe joint construction.

Fig. 2, three-jaw copper chuck schematic diagram.

Fig. 3, the schematic diagram of copper chuck folder aluminium-alloy pipe joint.

As seen from Figure 1, wherein, flat end aluminium-alloy pipe 1, be aluminium-alloy pipe 3,, cut pipe end face to be welded flat earlier during assembling for red copper cover 2 through mechanical flange, then a straight end is inserted into recess, at two sections junction liner red copper covers, make it to form novel joint construction, the body size that the thin-walled small-diameter aluminium alloy pipe is the most frequently used; External diameter is 8mm, and internal diameter is 6.4mm, and wall thickness is 0.8mm.

The external diameter of liner red copper cover should be less than the internal diameter that is welded tubule, and as being 6.4mm by the little bore of weldering, red copper cover external diameter is 6.4mm to the maximum so, and internal diameter is 5.4mm, and length is 15mm, and opens a longitudinal joint on copper sheathing, and stitching wide is 0.01～0.5mm.Its objective is to adapt to the tolerance that is existed by the welded tube internal diameter, because the fusing point of red copper cover is 1080 ℃, the fusing point of aluminium-alloy pipe is 630 ℃, thus both guaranteed that soldered inwall was smooth during welding, again not can with the copper sheathing weldbonding.Simultaneously, the red copper cover plays thermolysis to a certain degree.Also played and prevented that the Al-alloy metal that melts from staying.

One of main points of the present invention are translated into concavity to an end of joint for pipe with machinery, just can increase solder side greatly, must not adopt welding wire, and the commissure does not have the protuberance phenomenon.

The aluminium-alloy pipe 3 of flange, flange length depend on the demand of the width and the weld metal of argon arc welding electric arc.Evagination place size through flange behind the mechanical flange should be less than the electric arc width of tungsten electrode ac argon arc weld.The present invention selects the tungsten electrode ac argon arc weld for use, its electric arc width is 3-4mm, so the flange length of flange joint should be 3 or be less than 3mm, make it length dimension in the electric arc width, by accompanying drawing 1 as seen, new joint construction, the end face solder side of existing conventional joint, increased recess again and protruded the partly solder side of face, the reliability of weld strength is increased greatly.

The present invention adopts special machine to weld, its mechanical movement automatic control system, be by the program start stepper motor that designs, drive band synchronously by stepper motor again, drive scroll chuck 6 and the copper chuck 5 that is contained on the chuck by synchronous band again, clamp the synchronization mechanism operation automatic control system of being formed by welded tube 7,8 by scroll chuck.With reference to Fig. 2, this figure is a schematic diagram of clamping the aluminium-alloy pipe joint, mainly represents the connection situation between copper chuck 5 and the joint 7,8.

Copper chuck 5 is equipped with in the present invention on scroll chuck 6.Because the thermal conductivity factor of copper is big, adopting the copper chuck mainly is the fusing amount that is used for controlling welding point when welding, and makes the aluminium alloy of fusing just in time fill up weld seam, but does not have weld flush, plays the melt effect of effective control welding pool.This copper chuck 5 is installed on the three-jaw chuck 4 that is positioned on the scroll chuck 6, must with closely contacted by welded tube, between the two bronze medal chucks distance must remain between 8～8.5mm.The quality of copper chuck and shape depend on size of current when selecting electric welding for use, and factors such as aluminium alloy body size are in light of the circumstances through a large amount of concrete sizes of determining the copper chuck of testing.

During welding, assembling place of thin-walled small-diameter aluminium alloy pipe joint should be strictly on guard against that odds and ends such as moisture, greasy dirt, rubbish pollute.The aluminium-alloy pipes that earlier two quilts welded during welding, are clipped by chuck shown in Figure 2 connecting by shown in Figure 1 again, adopt the welding of tungsten electrode ac argon arc weld then.During welding, the central point of welding gun aligning joint, with little electric current weldering one circle of 28-32 ampere, use the big electric current weldering of 50-55 ampere 1-2 circle more earlier, with decay current weldering 1/6 circle, the employing decay current can play insulation effect, and the molten bath is cooled off gradually, reduces stress and concentrates again.

The present invention can adopt the PLC automatic program control to realize welding automatically.Joint construction of the present invention also is applicable to the joint welding of aluminium-alloy pipe thin-walled.

Claims

The joint constructions of 1 one kinds of thin-walled small-diameter aluminium alloy pipes welding is characterized in that, copper sheathing of seam crossing liner that two pipes to be connect connect, and wherein a beading tube ends becomes concavity or the small casing of an overcoat is set at the seam crossing that connects.
The joint construction of 2 aluminium-alloy pipes as claimed in claim 1, it is characterized in that should be less than the electric arc width of tungsten electrode ac argon arc weld through the evagination place size of flange behind the mechanical flange, is generally 3 or less than 3mm.
The joint construction of 3 aluminium-alloy pipes as claimed in claim 1, the external diameter that it is characterized in that liner red copper sleeve pipe is the internal diameter size of aluminium alloy tubule, and puts out a longitudinal joint in red copper, the width of seam is 0.01～0.5mm.
The welding method of 4 one kinds of thin-walled small-diameter aluminium alloy pipes as claimed in claim 1 is characterized in that specific implementation method is:

The first step: the end face cutting that will treat welded tube is smooth;

Second step: the end that will treat welded tube makes with mechanical flange and becomes concavity;

The 3rd step: process a bit of red copper sleeve pipe, neck bush during as welding;

The 4th step: control the straight end of welded tube and insert recess;

The 5th step: with the connector clamp that assembles on two three-jaw chucks;

The 6th step; During welding, adopt the tungsten electrode ac argon arc weld, under the inert gas protection, finish welding; Adopt the welding of tungsten electrode ac argon arc weld.During welding,, weld a circle with the little electric current of 28-32 ampere earlier, use big electric current weldering 1～2 circle of 50-55 ampere again the central point of welding gun aligning joint, weld less than 1 circle with decay current then.
The welding method of 5 aluminium-alloy pipes as claimed in claim 1 is characterized in that it can adopt the PLC automatic program control to realize welding automatically.