船舶焊接生产基础 (12).pdf

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1、Weld deformation Content The hazards of welding deformation 1 Measures to control weld deformation 2 Methods for correcting weld deformation 3 Welding residual deformation of a part or component makes assembly difficulties,which in turn affects the quality of subsequent welding.The hazards of weldin

2、g deformation 1 Excessive residual deformation should also be corrected to increase the manufacturing cost of the structure.The hazards of welding deformation Weld deformation also reduces the performance and load carrying capacity of the welded joint.2 3 Measures to control weld deformation Process

3、 measures 02 Design measures 01 Controls Starting from the design of the welded structure,the methods and means taken to control the welding deformation.After the structural design is completed,it enters the production stage,and the methods and means of controlling deformation are taken before or du

4、ring welding.Design measures Choose a reasonable weld size and groove form.Cross connectors with the same load carrying capacity.a）Do not open the ramp b）Open the groove Choose a reasonable weld cross-section size Measures to control weld deformation Design measures:Reasonably determine the length a

5、nd quantity of welds.Weld length has an impact on weld deformation,so under the premise of meeting the strength requirements and sealing requirements,continuous welds can be replaced by intermittent welds to reduce weld deformation.Measures to control weld deformation Design measures:Reasonably dete

6、rmine the length and quantity of welds.In addition,the number of welds should be reduced as much as possible during the design process.For example,in the thin shell structure,appropriately increasing the thickness of the wall plate can reduce the number of rib plates and achieve the purpose of contr

7、olling welding deformation.Measures to control weld deformation Design measures Arrange the weld position reasonably Fig a The middle weld is concentrated on the neutral shaft side,and the bending deformation is large fig b.c The welds in the middle are symmetrically distributed and well arranged Me

8、asures to control weld deformation Measures to control weld deformation Design measures Figure as ribbed design,where the weld is concentrated below the neutral shaft,will cause bending deformation of the upper arch.Figure b is designed with symmetrical welds distributed on both sides of the neutral

9、 axis,which can reduce and prevent the occurrence of bending deformation.Reasonable arrangement of ribbed welds Arrange the weld position reasonably Process measures Margin method Anti-deformation method Rigid fixation method Choose a welding method reasonably and welding process parameters Thermal

10、equilibrium method Heat dissipation method Choose a reasonable assembly welding sequence Measures to control weld deformation Process measures：Margin method This method is to compensate for the shrinkage of the weldment by appropriately increasing the length or width of the part than the design size

11、 when unloading.The amount of margin can be determined according to the formula and combined with the production experience.The margin method is mainly used to prevent the shrinkage deformation of weldments.Measures to control weld deformation Process measures Anti-deformation method Inverted deform

12、ation method for flat plate butt welding Measures to control weld deformation Rigid fixation method Rigid fixation when splicing thin plates Measures to control weld deformation Process measures Measures to control weld deformation Process measures Rigid fixation method In the absence of reverse def

13、ormation,the weldment member is rigidly fixed to limit the welding deformation.However,for materials such as cast iron and easily hardened steel,cracks are easy to occur when the deformation is blocked,and this method is not suitable.a）T The shaped beams are welded under rigid clamping b）Rigid fixat

14、ion when docking the panels Measures to control weld deformation Process measures Rigid fixation method The assembly welding sequence has a great influence on the deformation of the welded structure,so welding can be minimized by applying welding without the use of tire clamps,using a reasonable ass

15、embly and welding sequence.Measures to control weld deformation Process measures：Choose a reasonable assembly welding sequence.Choose a reasonable assembly welding sequence The weld being welded should be as close as possible to the neutral axis of the structural section Measures to control weld def

16、ormation Process measures 1 First assemble the large and small rib plates with the upper wing plate,weld A weld,at this time the weld A is basically close to the neutral axis of the structural section,and the deformation is minimal.Choose a reasonable assembly welding sequence The weld being welded

17、should be as close as possible to the neutral axis of the structural section Measures to control weld deformation Process measures 2 At the same time,the left and right webs,welding C and B welds,because the welds are basically symmetrical to the neutral axis of the structural section,the downward d

18、eflection deformation is very small.Choose a reasonable assembly welding sequence The structure of The structure of symmetrical symmetrical arrangement of welds arrangement of welds should be welded should be welded symmetrically by an symmetrically by an even number of even number of welders.welder

19、s.The welding sequence of the cylinder body butt weld Process measures Measures to control weld deformation Choose a reasonable assembly welding sequence Welding sequence of long welds(more than 1m).Several welding sequences for long welds a）Segmented desoldering method b）Alternating welding method

20、c）Jump welding method d）Segmented welding method Process measures Measures to control weld deformation Choose a reasonable assembly welding sequence The welding sequence of two welds adjacent to each other The direction and order of welds of two welds adjacent to each other a）Incorrect b）correct Mea

21、sures to control weld deformation Process measures Reasonable selection of welding methods and welding processes Measures to control weld deformation Process measures Welding of asymmetrical cross-sectional structures 1 The distance between the weld seam 1 and 2 from the neutral axis of the structur

22、al section is large,and multi-layer welding is used when welding,and each layer selects a smaller line energy.Reasonable selection of welding methods and welding processes Measures to control weld deformation Process measures Welding of asymmetrical cross-sectional structures 2 The distance between

23、the welds 3 and 4 to the neutral axis is small,and the single-layer welding is used when welding,and the larger line energy is selected.Reasonable selection of welding methods and welding processes Measures to control weld deformation Process measures In this way,the weld deformation produced by wel

24、ds 1 and 2 and welds 3 and 4 is opposite,the size is basically equal,canceling each other out,and the straight member is obtained after welding.Welding of asymmetrical cross-sectional structures 3 Process measures Thermal equilibrium method In the position symmetrical with the weld,the gas flame is

25、used to heat synchronously with the weld,as long as the process parameters of the heating are selected appropriately,the bending deformation of the component can be reduced or prevented.The thermal equilibrium method is used to prevent weld deformation Measures to control weld deformation Heat dissi

26、pation method a）Water immersion method for heat dissipation b）Water spray method to dissipate heat C）Heat dissipation mat method for heat dissipation Measures to control weld deformation Process measures When the residual deformation in the welded structure exceeds the deformation range required by

27、the technical requirements,the deformation of the weldment must be corrected.Manual correction Mechanical orthodontics Flame heating correction method Methods for correcting weld deformation The manual correction method is to use hand hammers,sledgehammers and other tools to hammer the deformation o

28、f the weldment,so that the material extension compensates for welding shrinkage.It is mainly used for the bending deformation of some small simple weldments and the wave deformation of thin plates.Methods for correcting weld deformation Manual correction The mechanical correction method is to extend

29、 part of the metal under the action of mechanical force,produce tensile plastic deformation,and restore the deformed components to the required shape.Methods for correcting weld deformation Correct the bending deformation of the beamCorrect the bending deformation of the beam a)a)Jack correction Jac

30、k correction b)b)Tensioner correctionTensioner correction Mechanical orthodontics Specifically,it is to use jacks,tensioners,presses,etc.to straighten or flatten the weldments.Mechanical correction method is generally suitable for materials with good plasticity and simple shape weldments.Methods for

31、 correcting weld deformation Correct the bending deformation of the beamCorrect the bending deformation of the beam a)a)Jack correction Jack correction b)b)Tensioner correctionTensioner correction Mechanical orthodontics Triangular heating is the triangle of the heating area,which is generally used

32、to correct the bending deformation of structures with greater stiffness and thickness.Methods for correcting weld deformation Flame heating correction method Flame correction of I-beam bending deformation When heated,the bottom edge of the triangle should be on the arched edge of the straightened structure,and the top should be in the direction of the bend of the weldment.Methods for correcting weld deformation Flame heating correction method Flame correction of I-beam bending deformation Thanks for watching