CN112222599A - Method for eliminating incomplete penetration and weak connection of friction stir welding root - Google Patents
Method for eliminating incomplete penetration and weak connection of friction stir welding root Download PDFInfo
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- CN112222599A CN112222599A CN202010964188.7A CN202010964188A CN112222599A CN 112222599 A CN112222599 A CN 112222599A CN 202010964188 A CN202010964188 A CN 202010964188A CN 112222599 A CN112222599 A CN 112222599A
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- welding
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- stir welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/12—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding
- B23K20/122—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding using a non-consumable tool, e.g. friction stir welding
- B23K20/1245—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating the heat being generated by friction; Friction welding using a non-consumable tool, e.g. friction stir welding characterised by the apparatus
- B23K20/126—Workpiece support, i.e. backing or clamping
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K20/26—Auxiliary equipment
Abstract
The method for eliminating the incomplete penetration and weak connection of the friction stir welding root comprises the following steps: pre-assembling and positioning a workpiece to be welded, ensuring that a butt joint gap is less than or equal to 0.3mm, and keeping the truncated edge of a welding edge not chamfered or beveled; welding from the back of the butt joint by adopting a laser welding method according to the wall thickness deviation value delta of the welding edge of the workpiece1Determining laser weld penetration delta2≥δ1+0.2, the light spot swings circularly in the welding process, the application range of the laser to the welding edge gap is improved, the width of the welding line is 1-3 mm, and the rest height is less than or equal to 0.2 mm; checking the residual height of the laser welding seam, and locally filing the excessive residual height; friction stir welding is performed from the front side, and the length t of the stirring pin is equal to the minimum wall thickness delta of the welding edgemin-0.2, the diameter of the stirring pin tip is greater than the beam waist width of the laser weld. Before the front side is subjected to friction stir welding, the back side of the butt joint is subjected to laser welding, and the laser welding seam fuses the root of a workpiece in advance so as to eliminate stirringThe defect that the root of the friction stir welding is not welded completely can be overcome, and the problem that the component with large thickness fluctuation is not welded completely by friction stir welding can be solved effectively.
Description
Technical Field
The invention relates to friction stir welding, in particular to a method for eliminating incomplete penetration and weak connection at the root of friction stir welding.
Background
In friction stir welding of butt joints, in order to avoid penetration, a stir pin with a length smaller than the thickness of a workpiece is generally used for welding, a butt joint interface at the root of a weld is in a thermal influence area, effective connection is not formed, and tiny lack of penetration at the root of the weld as shown in fig. 1 occurs (the lack of penetration is called weak bonding when the naked eye cannot observe the part).
The lack of root penetration (weak bonding) defect seriously affects the strength of the joint and the service performance of the workpiece, and has particularly high requirements on detection. There are three main approaches in the engineering field to eliminate or reduce lack of penetration (weak bonding): a shim method (CN200810202856.1), a tool grooving method (CN200910123791.6), and a double-side welding method (CN 201810083224.1). The gasket method is that a gasket which is the same as the workpiece is adopted and is arranged between the workpiece to be welded and the back rigid base plate, no gap exists between the gasket and the workpiece to be welded and between the gasket and the back rigid base plate, the gasket is aligned with the center of a welding line, then welding is carried out, and polishing is carried out after welding to remove the gasket. The gasket method changes the butt joint form into butt lap joint, the lap welding can not avoid interface hook (as shown in fig. 2), and the workload of subsequent grinding is very large. The tool grooving method is that a triangular or circular groove is formed in a back rigid tool, adjustment is carried out according to welding thickness, the weak connection part on the back of a welding seam is extruded into the groove through plastic deformation, and polishing and removal are carried out after welding. The tool grooving method can not be disassembled due to the problem of the curved surface of the part during subsequent disassembly, and the polishing workload is large. The double-sided welding method is to weld the two sides by friction stir welding, and can adopt double-sided equal-thickness welding or one side by a short stirring pin. The double-side welding method needs two times of clamping, complex parts need two sets of rigid tools, and the production efficiency is low.
The former two methods have certain limitations in solving the problems of incomplete or weak welding at the root part of the friction stir welding, and particularly have more obvious disadvantages when the wall thickness of a welding edge is not uniform; for example, when the thickest part of the welding edge is 6.6mm and the thinnest part is 6mm, if the length of the stirring pin is selected to be 6.4mm by adopting the first method, the interface hook defect caused by puncture inevitably exists at the position with the thinner thickness, and the grinding workload is very large; and if the groove is larger and filled by homogeneous materials, and then the long stirring pin is selected for welding, the effect is the same as that of the first method.
The last method has limitation in welding efficiency, needs two sets of tools and has large production investment.
The CN200980152432.1 document discloses butt welding and manufacturing methods using fusion welding and friction stir welding, wherein the root part adopts a fusion welding method with a beveled large fusion depth, the front side adopts friction stir welding, and the two welding methods are combined.
Disclosure of Invention
In view of the above problems, the present invention aims to solve the problems of incomplete penetration and weak root connection in friction stir welding, and to avoid penetration of the stir pin through the workpiece and to solve the problems of incomplete penetration and weak root connection when the uniformity of the welded wall thickness is poor. The method for eliminating the incomplete penetration and weak connection of the friction stir welding root provided by the invention solves the problems of incomplete penetration and weak connection of the friction stir welding root of the butt joint, reduces the requirement of the friction stir welding on the wall thickness consistency of a workpiece, and improves the reliability of the joint.
The technical scheme for realizing the invention is as follows:
firstly, pre-assembling and positioning a workpiece to be welded, ensuring that a butt joint gap is less than or equal to 0.3mm, keeping the welding back basically flush, and keeping the truncated edge not chamfered or beveled at the welding edge;
step two, welding from the back of the butt joint by adopting a laser welding method, and welding according to the wall thickness deviation value delta of the welding edge of the workpiece to be welded1Determining laser weld penetration delta2≥δ1+0.2, weldingThe width of the seam is 1 mm-3 mm, and the rest height is less than or equal to 0.2 mm;
checking the excess height of the laser welding seam, and if the excess height is larger than 0.2mm, locally filing the excess height;
step four, friction stir welding is carried out from the front side, and the length t of a stirring needle is equal to the minimum wall thickness delta of a welding edgemin-0.2, the diameter of the stirring pin end should be larger than the width of the laser weld;
and the laser in the step two adopts a circular swing mode in the welding process, the swing range is 0.8-1.5 mm, the swing frequency is 50-300 Hz, the allowable range of the laser welding to the welding edge gap is improved, and the generation of air holes and splashes is reduced.
Compared with the prior art, the invention has the beneficial technical effects that:
according to the method for eliminating the incomplete penetration and weak connection of the friction stir welding root, the back of the butt joint is subjected to laser welding before the friction stir welding is carried out on the front, and the laser welding seam welded in advance plays a role in eliminating the defect of incomplete penetration (weak connection) of the friction stir welding root;
according to the method for eliminating incomplete penetration and weak connection of the friction stir welding root, the laser welding seam is thin, the welding seam which is subjected to laser welding in advance is forged again during front friction stir welding, the width of the friction stir welding seam is larger than that of the laser welding seam, on one hand, the pore defect of the laser welding seam can be removed, on the other hand, the casting structure of the laser welding seam can be changed into the forging fine-grained structure, the joint strength is improved, and the welding quality is ensured;
the method for eliminating the incomplete penetration and weak connection of the friction stir welding root reduces the difficulty in selecting the length of the stirring pin, the length of the stirring pin is selected to be 0.2mm less than the thinnest area of a workpiece to be welded, the problems of puncture and the like can be effectively avoided, the requirement on the machining precision of the part can be reduced, the application range is very wide, particularly for producing sheet metal parts, the wall thickness of the sheet metal part is uneven, the machining is difficult to ensure the precision, the problem that the incomplete penetration of the friction stir welding root of the part can be well solved by adopting the method, and the applicability of the friction stir welding process is increased;
according to the method for eliminating incomplete penetration and weak connection of the friction stir welding root, laser welding is adopted for pre-welding, the efficiency is high, the control is easy, the welding effect is good, and the polishing process after welding is omitted; root laser welding is carried out in the preassembly process, certain fusion depth is guaranteed, the problem that friction stir welding cannot penetrate through full thickness and cannot be welded completely can be solved, and the process is simple.
According to the method for eliminating incomplete penetration and weak connection of the friction stir welding root, the strength of the welding joint is higher than that of a conventional single-side friction stir welding joint, compared with double-side friction stir welding, one friction stir welding clamping is reduced, a back laser welding line with shallow fusion depth can be completed only by adopting a handheld laser head, the flexibility and the flexibility are very high, and the efficiency is improved by at least 1 time.
Drawings
The method for eliminating the root lack of penetration and weak connection of friction stir welding according to the present invention is given by the following examples and the attached drawings.
FIG. 1 is a schematic representation of prior art friction stir welding root lack of penetration (weak bond).
FIG. 2 is a schematic diagram of an interface curve generated by a gasket method according to the prior art.
FIG. 3 is a diagram illustrating pre-weld assembly in accordance with a preferred embodiment of the present invention.
FIG. 4 is a schematic view of laser pre-welding the back of the butt joint according to the preferred embodiment of the present invention.
FIG. 5 is a schematic view of laser pre-welding the back of the butt joint according to the preferred embodiment of the present invention.
FIG. 6 is a longitudinal sectional view of a friction stir weld performed after laser pre-welding the back of the butt joint according to the preferred embodiment of the present invention.
FIG. 7 is a longitudinal cross-sectional effect of a friction stir weld without pre-welding the back.
FIG. 8 is a schematic illustration of the front friction stir welding of a butt joint in a preferred embodiment.
FIG. 9 is a schematic view illustrating the completion of friction stir welding on the front surface of a butt joint according to a preferred embodiment of the present invention.
Detailed Description
The method of eliminating root lack of penetration and weak bonding in friction stir welding according to the present invention will be described in further detail with reference to fig. 3 to 7.
According to the method for eliminating incomplete penetration and weak connection of the friction stir welding root, a laser welding method is firstly adopted on the back surface of the butt joint, the root of the butt joint surface is fused, and a groove does not need to be formed before welding; and then the front surface of the butt joint is welded by friction stir welding.
Before friction stir welding is carried out on the front surface, laser welding is carried out on the back surface of the butt joint, the root of the butt joint surface is fused, and the laser welding seam welded in advance plays a role in eliminating the defect that the root of the friction stir welding is not welded thoroughly (weak connection).
The method of eliminating root lack of penetration and weak bonding of friction stir welding according to the present invention will now be described in detail with reference to specific embodiments.
This embodiment is exemplified by a cylindrical part composed of 4 pieces, i.e. comprising 4 longitudinal seams.
1) Referring to fig. 3, 4 arc plates are assembled into a cylinder, the outer wall of the cylinder is positioned by manual fusion welding to form a complete circle, the gap between the butt joint surfaces is ensured to be less than or equal to 0.3mm, the welding back surface is basically flush, and the welding edge keeps the truncated edge without chamfering or opening; the butt joint of one arc plate and the other arc plate is a seam to be welded, the outer wall of the cylinder is the front face (the welding side of friction stir welding) of the butt joint, and the inner wall of the cylinder is the back face of the butt joint;
2) a laser welding head is adopted to extend into the cylinder, and welding is carried out from the back of the butt joint (seam), which is shown in figure 4;
the laser welding fuses the root of the butt joint surface according to the wall thickness deviation value delta of the welding edge of the workpiece1Determining laser weld penetration delta2≥δ1+0.2, e.g. maximum weld edge thickness deltamax6.6mm, thinnest deltaminIs 6mm, then delta1＝δmax-δmin0.6mm, weld penetration delta2Not less than 0.8 mm; in the welding process, laser circularly swings, the swing amplitude is 0.8-1.5 mm, the swing frequency is 50-300 Hz, the allowable range of welding edge gaps in laser welding is improved, and air holes and splashing are reduced; the width of the laser welding seam is 1 mm-3 mm, the residual height is less than or equal to 0.2mm, and the width can beAllowing some concavity;
referring to fig. 4, preferably, the ideal shape of the laser welding area is a bell jar shape, which can be realized by optimizing laser welding parameters, such as the weld penetration depth is 0.8mm, and selecting the process parameters: the laser power is 900W, the welding speed is 1.2m/min, the defocusing amount is +/-2 mm, the swing amplitude is 1.5mm, the swing frequency is 50-100 Hz, and the spot size is 0.5 mm;
the laser welding efficiency is high, the control is easy, and the welding effect is good (if the welding surface is smooth, basically no surplus height exists); in addition, generally, the size of the handheld laser welding head is smaller, the requirement on space is basically the same as that of manual arc welding, and the operation can be completed only by adopting the handheld laser welding head;
for a straight seam to be welded, the profiling mold is arranged near the seam to be welded, the laser welding head is arranged on the profiling mold, laser is aligned with the butt joint surface, the profiling mold is used for replacing a handheld mode, and stability of a laser welding process is guaranteed; for complex welding seams, the welding can be realized by means of an actuating mechanism, such as a robot, a machine tool and the like;
3) friction stir welding is carried out from the front surface of the butt joint (seam);
because the laser welding is firstly carried out on the back surface of the butt joint and the laser welding has a certain welding penetration depth, when the friction stir welding is carried out, the length of a stirring needle of the friction stir welding is 0.2mm smaller than the thickness of the thinnest area of the workpiece to be welded, for example, the thickness of the workpiece to be welded is 5.0 mm-5.8 mm, the welding penetration depth of the laser welding is 1mm, and the length of the stirring needle can be 4.8mm, so that the full penetration of the whole welding seam can be realized, as shown in fig. 6;
if the length of the probe is 4.8mm without laser welding in advance, a large lack of penetration inevitably occurs at a position where the thickness is larger than 5.0mm, and if the length of the probe is 5.5mm, a penetration phenomenon occurs at a position where the thickness is small, as shown in fig. 7.
Therefore, the method can eliminate or reduce the defect of incomplete penetration (weak bonding), effectively avoid the problems of puncture and the like, reduce the requirement on the processing precision of parts and has wide application range.
The size of the stirring pin of the friction stir welding should be larger than the width of the laser welding seam (i.e. the width of the friction stir welding seam should be larger than the width of the laser welding seam), so that the friction stir welding area can basically cover the laser welding area, thereby eliminating the air hole defect in the laser welding area and improving the performance of the laser welding area, as shown in fig. 7;
when friction stir welding is carried out, a friction stir welding head is arranged on a tool, the stirring head is opposite to the middle butt joint surface, then friction stir welding is carried out, welding parameters are required to ensure that no tunnel cavity defect exists in the inner part, and the surface indentation is ensured to be 0.1-0.2 mm in the welding process, as shown in figure 5; for example, welding 5mm, and the parameters of the friction stir welding are as follows: the rotating speed is 500-1000 rpm, the welding speed is 150-500 mm/min, and the welding inclination angle is 2.8 degrees.
After all the front friction stir welding is completed, the butt joint surfaces realize full penetration welding connection, as shown in fig. 8; and after the welding workpiece is cooled, disassembling the tool and carrying out subsequent inspection procedures.
According to the method for eliminating incomplete penetration and weak connection of the friction stir welding root, the butt joint surface root is fused by laser welding in advance, so that the applicability of friction stir welding engineering application is increased under the condition that the thickness of a workpiece to be welded is not uniform, and the internal quality of a butt joint is ensured; the method for eliminating the incomplete penetration and weak connection of the friction stir welding root does not need back grinding after welding or twice welding, can directly carry out root welding operation after pre-positioning, and has the characteristics of easy operation, high efficiency and high reliability.
Any simple modification, equivalent change and modification of the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (2)
1. The method for eliminating the incomplete penetration and weak connection of the stirring friction welding root is characterized by comprising the following steps:
firstly, pre-assembling and positioning a workpiece to be welded, ensuring that a butt joint gap is less than or equal to 0.3mm, keeping the welding back basically flush, and keeping the truncated edge not chamfered or beveled at the welding edge;
step two, adopting a laser welding method toWelding the back of the butt joint according to the wall thickness deviation value delta of the welding edge of the workpiece to be welded1Determining laser weld penetration delta2，δ2≥δ1+0.2, the width of the welding seam is 1 mm-3 mm, and the rest height is less than or equal to 0.2 mm;
checking the excess height of the laser welding seam, and if the excess height is larger than 0.2mm, locally filing the excess height;
step four, friction stir welding is carried out from the front side, and the length t of a stirring needle is equal to the minimum wall thickness delta of a welding edgemin-0.2, the pin tip diameter being greater than the width of the laser weld.
2. The method for eliminating the incomplete penetration and weak connection at the root of the friction stir welding according to claim 1, wherein the laser welding spot adopts a circular oscillation mode in the welding process, the oscillation range is 0.8mm to 1.5mm, the oscillation frequency is 50Hz to 300Hz, the allowable range of the welding edge gap by the laser welding is increased, and the generation of air holes and splashes is reduced.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023082718A1 (en) * | 2021-11-15 | 2023-05-19 | 哈焊国创(青岛)焊接工程创新中心有限公司 | Welding system for eliminating weld reinforcement and undercut defect and welding method |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008272768A (en) * | 2007-04-26 | 2008-11-13 | Nippon Sharyo Seizo Kaisha Ltd | Welding joint and structure of double skin panel |
| US20100159265A1 (en) * | 2008-12-23 | 2010-06-24 | Douglas Paul Fairchild | Butt weld and method of making using fusion and friction stir welding |
| CN103894726A (en) * | 2014-03-13 | 2014-07-02 | 哈尔滨工业大学 | Friction stir welding method capable of achieving back thickening to eliminate weak connection and adapting to plate thickness changes |
| JP2018039017A (en) * | 2016-09-05 | 2018-03-15 | 日本軽金属株式会社 | Joining method |
| CN109483071A (en) * | 2018-12-27 | 2019-03-19 | 长沙理工大学 | A kind of method of the big thickness plate of laser-agitating friction composite welding |
-
2020
- 2020-09-15 CN CN202010964188.7A patent/CN112222599A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008272768A (en) * | 2007-04-26 | 2008-11-13 | Nippon Sharyo Seizo Kaisha Ltd | Welding joint and structure of double skin panel |
| US20100159265A1 (en) * | 2008-12-23 | 2010-06-24 | Douglas Paul Fairchild | Butt weld and method of making using fusion and friction stir welding |
| CN103894726A (en) * | 2014-03-13 | 2014-07-02 | 哈尔滨工业大学 | Friction stir welding method capable of achieving back thickening to eliminate weak connection and adapting to plate thickness changes |
| JP2018039017A (en) * | 2016-09-05 | 2018-03-15 | 日本軽金属株式会社 | Joining method |
| CN109483071A (en) * | 2018-12-27 | 2019-03-19 | 长沙理工大学 | A kind of method of the big thickness plate of laser-agitating friction composite welding |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023082718A1 (en) * | 2021-11-15 | 2023-05-19 | 哈焊国创(青岛)焊接工程创新中心有限公司 | Welding system for eliminating weld reinforcement and undercut defect and welding method |
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