[精选]制造工程与技术(热加工)英文版joining_processes_and_e.pptx
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1、成型技术基础ManufacturingEngineeringandTechnology-HotProcesses制造工程与技术(热加工)制造冷加工与热加工特点热加工:Casting铸、Forming锻、Welding焊、HeatProcessing热处理张大童、曹彪、黄珍媛Part Joining Processes and Equipment Joining:Connect parts together.Joining is an all-inclusive term(总称)总称),covering processes such as welding,brazing,soldering,ad
2、hesive bonding(胶接)(胶接),and mechanical fastening.Give some examples of Joining Processes you known.Why joining processes?Without joining,there would not be modern industry.Because products or parts would bel Impossible to manufacturel Expensivel Difficult to maintenancel Hard to get different propert
3、iesl Difficult to transportationjoining processes classificationSee Fig.V.3 What difference between welding and adhesive bonding,or mechanical fastening?Adhesive bondingMechanical fasteningJoining ProcessesweldingFusionBrazing and solderingSolid stateChemicalElectricalElectricalChemicalMechanicalPro
4、cess selection:whichs preferred,which not?长征二号丙火箭长征二号丙火箭8月发射月发射卫星失利故障原因:卫星失利故障原因:二级飞行段二级游机分机与伺服机构连接部位失效造成,因为连接部位的可靠性存在薄弱环节。The choice of a joining process depends onl The applicationl The joint designl The materials involvedl The shapes of the components to be joined,their thicknesses,and their size
5、sl Others:the location of the joint within the product,component numbers,the operator skill required,costs and so on.吴吴 林林 教授教授:1.1.制造技术的三个基本功能:成形、连接、改性;制造技术的三个基本功能:成形、连接、改性;2.2.古代焊接起源于中国,现代焊接发展于西方;古代焊接起源于中国,现代焊接发展于西方;3.3.焊接已经逐渐从技术走向科学。焊接已经逐渐从技术走向科学。n三种焊接原理还没有形成一个统一的科学理论;三种焊接原理还没有形成一个统一的科学理论;n宏观、细观、
6、界观、微观;宏观、细观、界观、微观;n还有若干自然现象:太空环境下材料的粘连,冰和肌肉的粘连等;还有若干自然现象:太空环境下材料的粘连,冰和肌肉的粘连等;n各种新材料的连接,特别是陶瓷、高温材料、碳纤维、复合材料、各种新材料的连接,特别是陶瓷、高温材料、碳纤维、复合材料、异种材料等的连接问题有待于实现和发展。异种材料等的连接问题有待于实现和发展。焊接的问题基本上是一个材料界面的科学问题焊接的问题基本上是一个材料界面的科学问题手艺手艺 技术技术 科学科学 27 Fusion-Welding Processes 熔焊熔焊weldingFusionBrazing and solderingSolid
7、 stateChemicalElectricalElectricalChemicalMechanicalShielded Metal-ArcSubmerged ArcPlasma ArcGas Metal-ArcFlux-Cored ArcGas Tungsten-ArcElectron-BeamLaser-BeamElectro-gasElectro-slagAtomic Hydrogenet alTopicstoDiscussIntroductionOxyfuelGasweldingArc-WeldingProcesses:ConsumableelectrodeElectrodesArc-
8、WeldingProcesses:NonConsumableProcessThermitWeldingElectronBeamWeldingLaserBeamWeldingCuttingWeldingSafety27.1 Introduction Fusion welding:It is defined as the melting together and coalescing of materials by means of heat.Heat(energy)is usually supplied by chemical or electrical means.Filler metals(
9、填充金属)(填充金属)may or may not be used.Filler metals:Metals added to the weld area during welding.Autogenous weld(自熔焊缝)(自熔焊缝):Fusion welds made without the addition of filler metalsl Basic principles of each process l Equipmentl Advantages and limitationsl Capabilities GeneralCharacteristicsofFusionWeldi
10、ngProcesses27.2 Oxyfuel Gas WeldingOFW 气焊,氧乙炔焊气焊,氧乙炔焊weldingFusionBrazing and solderingSolid stateChemicalElectricalElectricalChemicalMechanicalOxyfuel gasThermit1.Oxyfuel Gas Welding(氧燃气焊接,气焊)(氧燃气焊接,气焊):A general term used to describe any welding process that uses a fuel gas combined with oxygen to
11、 produce a flame,which is the source of the heat that is used to melt the metals at the joint.2.Oxyacetylene welding(氧乙炔焊)(氧乙炔焊):The process utilizes the heat generated by the combustion of acetylene gas(C2H2)in a mixture with oxygen.C2H2+O2 2CO+H2+heat (1/3 of the total)2CO+H2+1.5O2 2CO2+H2O+heat (
12、2/3)Other fuel gases?27.2.1 Types of flamesNeutral flame(中性焰)中性焰):The ratio of acetylene and oxygen is 1:1.Its widely used for OFW of most materials.Oxidizing flame(氧化焰)(氧化焰):The ratio is smaller than 1.Its harmful for steel welding,it can be used for the welding of copper and copper-based alloys.Re
13、ducing or carburizing flame(还原焰或碳化焰)(还原焰或碳化焰):The ratio is bigger than 1.Its for brazing,soldering,and flame-hardening because of its lower temperature27.2.2 Filler Metals(填充金属)填充金属)and Flux(焊剂)(焊剂)Filler metals are used to supply additional material to the weld zone during welding.They are availabl
14、e as rod or wire made of metals compatible with those to be welded.These consumable filler rods may be bare,or they may be coated with flux.The purpose of the flux:to remove oxides from the surfaces to generate gaseous and slag shield to take part in the metallurgical reactions27.2.3 Welding practic
15、e and EquipmentWelding Torch(焊炬)(焊炬)EquipmentOperation Prepare the edges to be joined,and establish and maintain their proper position by the use of clamps and fixtures;Open the acetylene valve,and ignite the gas at the tip of the torch.Open the oxygen valve,and adjust the flame for the particular o
16、peration;Position:Hold the torch at about 450 from the plane of the workpiece,with the inner flame near the workpiece and the filler rod at about 300-400 ;Speed:Touch the filler rod to the joint and control its movement along the joint length by observing the rate of melting and filling of the joint
17、.Safety Compressed gas:Exploding;Burning Back;Flame,heat and light injuring:goggles with shaded lenses(带遮光片(带遮光片的护目镜)的护目镜),face shield(面罩)(面罩),gloves(手套)(手套),protective clothing(防(防护服)护服).Process CapabilitiesLow cost but more heat input;Most ferrous and nonferrous metals(6mm)(黑色金属黑色金属 有色金属)有色金属)Manu
18、al:Portable(便携的)(便携的),versatile(通用的)(通用的),economical for simple and low-quantity work;For fabrication and repair work.27.3 Arc-welding process:Consumable-electrode(熔熔化极)化极)weldingFusionBrazing and solderingSolid stateChemicalElectricalElectricalChemicalMechanicalShielded Metal-ArcSubmerged ArcPlasma
19、 ArcGas Metal-ArcFlux-Cored ArcGas Tungsten-ArcElectron-BeamLaser-BeamElectro-gasElectro-slagAtomic Hydrogenet alArc-welding processWhat is arc?What kind of arc can be used for welding?An arc is produced between the tip of the electrode and the workpiece to be welded,by the use of an AC or a DC powe
20、r supply(电源)(电源).Polarity(极性)(极性)for DC.(straight and reverse)正接正接 反接反接Arc-welding process involves either a consumable or a non-consumable electrode.(熔化极(熔化极 or 非熔化极)非熔化极)27.3.1 Shielded Metal-Arc Welding (SMAW)焊条电弧焊(手工电弧焊)焊条电弧焊(手工电弧焊)Welding practice The electric arc is generated by touching the t
21、ip of a coated electrode(焊条)(焊条)against the workpiece(工件)(工件)and then withdrawing it quickly to a distance sufficient to maintain the arc;The heat generated melts a portion of the tip of the electrode,of its coating,and of the base metal in the immediate area of the arc;A weld(焊缝)(焊缝)forms after the
22、 molten metal,a mixture of the base metal,the electrode metal,and substance from the coating on the electrode,solidifies in the weld area.Shielded Metal-Arc Welding-Arcbase metal 母材母材 weld metal 焊缝焊缝electrode 焊条,电极焊条,电极 coating 涂层,药皮涂层,药皮shielding gas 保护气体保护气体 solidified slag 凝固焊渣凝固焊渣(27.4)Electrode
23、sIntroductionElectrodes are used as consumables in SMAW.They are made up of welding wire(core)and coating.Electrodes are classified according to the strength of the deposited weld metal,the current,and the type of coating.Typical coated electrode dimensions are 150 to 460mm in length and 1.5 to 8mm
24、in diameter.As the thickness of the sections to be welded increases,the required current and electrode diameter also increase.Welding wire(core)Acts as one pole of the arc and filler metal.Electrode coatings Electrodes are coated with claylike materials that include silicate(硅酸盐)(硅酸盐)binders(粘合剂)(粘合
25、剂)and powdered materials such as oxides(氧化物)氧化物),carbonates(碳酸盐)(碳酸盐),fluorides(氟化物)(氟化物),metal alloys,and cellulose(纤(纤维素)维素).The coating,which is brittle and participates in complex interactions during welding,has the following basic functions:03Functions of coating to stabilize the arc:to improve
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