制造方法課件(重慶大學(xué))

1、1PRACTICAL APPLICATIONSChapter 8 PRACTICAL APPLICATIONS Now that we have reached the end of this part of the course, lets have an interesting quiz to see how much you know! In addition, it will show you applicable, this course is to understanding how some items we encounter in our everyday life are

2、manufactured and what they are made of.Exercise 1For each of the items (A-F), suggest the material(s) used and the manufactured process (es) involve.Chapter 8 PRACTICAL APPLICATIONSFigure 8-1 Items seen/used in daily lifeChapter 8 PRACTICAL APPLICATIONSMy answers:A: Material(s): Manufacturing proces

3、s (es):B: Material(s): Manufacturing process (es):C: Material(s): Manufacturing process (es):D: Material(s): Manufacturing process (es):E: Material(s): Manufacturing process (es):F: Material(s): Manufacturing process (es):Chapter 8 PRACTICAL APPLICATIONSC: Fan Speed ButtonsMaterial:Manufacturing pro

4、cess (es):D: Enclosing Metal CageMaterial:Manufacturing process (es):E: Electrical Contact PlateMaterial:Manufacturing process (es):F: External Plastic CasingMaterial:Manufacturing process (es):G: Gear Box CoverMaterial:Manufacturing process (es):Figure 8-2 Used in daily lifeChapter 8 PRACTICAL APPL

5、ICATIONSI: GearsMaterial:Manufacturing process (es):J: Motor RodMaterial:Manufacturing process (es):K: Metal Fan PlateMaterial:Manufacturing process (es):H: Gear Box Enclosing The GearMaterial:Manufacturing process (es):Figure 8-3 Used in daily lifeChapter 8 PRACTICAL APPLICATIONSExercise 4How is th

6、e cap of this aerosol can manufactured? (Hint: View Multimedia Video on Press working)Figure 8-4 An acrosol canChapter 8 PRACTICAL APPLICATIONSExercise 5Q: What are the various components of this baby milk bottle made of and how are they manufactured?Figure 8-5 A baby milk bottleMy Answers:Chapter 8

7、 PRACTICAL APPLICATIONSFINAL EXAMPLE: DISSECITION OF A CAR The car is an engineering amalgam of various materials and mechanisms put together. It is an excellent “vehicle” for teaching mechanical, giving you plenty of “mileage” for future research. Interested to know what are some of the materials i

8、n a car? Listed below are some of the components that can be found in a car.Figure 8-6 Car componentsChapter 8 PRACTICAL APPLICATIONSA: Main body (composed of different individual fenders)Figure 8-7 Front corner of carMaterial: Mild steel. (unless the car is an Audi A 8 WITH an entirely aluminum fra

9、me and body panels, or a typical racing/sports car with a glass fibre or carbon fibre composite body.)Manufacturing Process: Cold rolled sheet metal, stamped and pressed to shape.Chapter 8 PRACTICAL APPLICATIONSB: Bonnet Material: Mild steel. But some cars are using aluminum to reduce weight. Manufa

10、cturing Process: Cold rolled sheet metal, stamped and pressed to shape.C: Windscreen and side windows Material: Tempered Glass (To minimize shattering when broken) Manufacturing Process: Casting.D: Bumpers Material: Shape regenerating polypropylene or acrylonitrile butadiene styrene (ABS) Manufactur

11、ing Process: Injection molding.Chapter 8 PRACTICAL APPLICATIONSE: Rims Material: Steel, Aluminum alloy or Titanium alloy. Manufacturing Process: Can be produced by die casting, spinning, forging, roll forming, or a combination of processes.Figure 8-8 More Car componentsChapter 8 PRACTICAL APPLICATIO

12、NSF: Mirror Cover (Exterior housings)Material: Steel, Acylonitrile butadiene styrene Manufacturing Process: Injection molding.G: Headlamps, Tail lamps, Fog lamps, Signal Lamps Material: Steel: Older cars of cheap makes use acrylic for the transparent cover. Most cars today use polycarbonate for the

13、transparent covers due to its high impact strength. The reflectors in the headlamp assembly are metallised plastics in which about 0.1 micron of aluminum is sputtered on the plastics to form a reflecting surface. To protect the aluminum coating from losing its reflectivity thereby compromising on th

14、e amount of light being reflected, an overcoat of silicon monoxide is vapor deposited. Manufacturing Process: Injection molding.Chapter 8 PRACTICAL APPLICATIONSH: Engine blockMaterial: Cast iron, which also has the additional advantage of corrosion resistance in the presence of water besides being e

15、asier to cast than mild steel. However end cars are turning to aluminum for such engine blocks to achieve weight reductions.Manufacturing Process: Sand casting, although certain sections can be die cast if the engine is made of aluminum alloy.Chapter 8 PRACTICAL APPLICATIONSI: Catalytic Converters M

16、aterial: The catalyst used contains platinum, palladium and rhodium. The shell is made of mild steel. Manufacturing Process: Rolled from mild steel billet, holes are punched, seams are welded.Chapter 8 PRACTICAL APPLICATIONSJ: Steeling wheel and gear shift lever Material: High end cars usually have

17、these wrapped tastefully in leather and walnut wood. Low range cars have these made of polyurethane (PU) or cellulose acetate (CBA). Manufacturing Process: The PU is compression molded, the CBA is injection molded.Chapter 8 PRACTICAL APPLICATIONSK: DashboardUpper Dashboard Material: Soft touch plast

18、ics are employed in high end cars, e.g. polyolefin co-polymers. Lower Dashboard Material: Hard wearing plastics are employed, e.g. ABS.Manufacturing Process: injection molding.Chapter 8 PRACTICAL APPLICATIONSIf you were to observe a headlamp or tail lamp removed from its housing, you will notice tha

19、t there is a back surrounding plastic at the back of the transparent cover.This is made of acrylonitrile butadiene styrene or ABS in short (not to be confused with the other acronym Antilock Braking System which is a standard feature in almost all case today). ABS has excellent impact resistance but

20、 cannot be transparent.Chapter 8 PRACTICAL APPLICATIONSL: Decorative interior strips Material: In expensive cars, you get genuine wood trims, such as burr walnut, chestnut or birds eye maple. Aluminum is employed liberally in cars with a sporting image. The so called “wood” you see in cars at the lo

21、wer end of the market are nothing more than a polymer which have been cubic with the grain design of the wood.Chapter 8 PRACTICAL APPLICATIONSM: Seats Material: Leather is becoming a standard equipment in most cars today. But there are still some cars which have PVC seats and others with fabric seat

22、s. A new emerging material is Alcantara (a synthetic suede) which heats up less than leather when exposed to direct sunlight for hours (thereby not scorching you bottom) and grips you better than leather.Chapter 8 PRACTICAL APPLICATIONS These are just some of the common items you see in a car. There

23、 are still thousands of other parts in less conspicuous areas of a car waiting for you to explore. For example, polyisoprene is employed in the sidewalls of some tires, cords made of Kevlar are sometimes used to reinforce tires, polyisoprene (a type of synthetic rubber) is used to make the bladders

24、of some windscreen wipers, polybutadiene (another type of synthetic rubber) is employed in the hoses in the engine compartment, etc. This is the end of my book, bu it should not be the end of you life-learning. Look around you and you will find lots more to discover in this world. God bless. Associa

25、te Professor MAJ(NS) Dr Seah Kar Heng (aka“Have KAR will travel”).22PINDEXINDEXINDEXINDEXINDEXAPPENDIX Joining by means of another metal (known as a solder or soldering alloy) of melting point below 550oC and below recrystallisation temperature of the parts being joining is achieved by negligible al

26、loying diffusion between the solder and the parent metal. Joining is achieved by mechanical locking or adhesion. Joint has low strength, low hardness, low temperature applications, cannot withstand strong vibrations. Cheap and convenient method of joining, chiefly for electrical contacts.APPENDIXApp

27、lications: Electrical solders are basically tin-lead alloys(soft solders), usually 50-55% composition for common general use. There are other combinations used for various special purposes, e.g, with Pb, Bi, Ag, Cu, Zn. Some have no tin at all (depends on cost and availability of tin ) but tin helps

28、 improve the wetting property and lowers the melting point of the soldering alloy. Ccopper solders are used for joining the cylindrical portion of three-piece mild steel cans.Parent metals Cu, Fe, Pb, Ni, Sn, Zn and many of their alloys may be soldered. Aluminium and stainless steels need special te

29、chniques to prevent the formation of oxide films (aluminium and chromium oxides respectively)APPENDIXSoldering iron, molten bath, electrical induction or resistance (do not overheat, otherwise intermetallic compounds will form). To solder well (good adhesion), surfaces must be clean (free from oil,

30、grease, oxide layer). Apply a layer of flux (usually in the form of paste) before soldering. Roles of flux: 1. Flux cleans the surfaces and dissolves oxide layers formed prior to soldering. 2. Prevents oxidation of surfaces when hot . 3. Lowers surface tension of molten solder and promotes wetting o

31、f metal surfaces. APPENDIXBRAZINGJoining by means of another metal (non-ferrous), known as a brazing alloy, of melting point greater than550oC and generally below recrystallistation temperature of the parts being joined (used brazing alloy). This ensures that there is no annealing of the parent meta

32、l. The traditional brazing alloy used to be copper alloy. (The word “braze” comes from the word “brass”). However, nowadays there are silver and aluminium brazes too, some alloying/diffusion takes place between the brazing metal and the parent metal.APPENDIXTypes of Brazing Alloys: 1.copper and copp

33、er alloys For brazing at around 1200oC (usually for steel parts) 2. Silver brazing alloys Ag-Cu-Zn alloy. For brazing at 600-850oC, 3.Aluminium brazing alloys For brazing at around 700oC.Note: Brazing alloys must wet the surfaces to be brazed, i.e, adhesion between the braze material and the parent

34、metal must be good.APPENDIXApplications1. When you dont want to lose strength through a microstrucural change, e.g., in a precipitation hardened alloy or in a cold-worked material.2. When you want to avoid grain growth. 3. When you want to avoid over tempering.4. When you want to join dissimilar met

35、als, e.g., Al alloys, Mg alloys, Ni alloys, Cu alloys (brass, bronzes, Cu-Be, Cu-Si), carbon and low alloy steels, stainless steels, high speed steels, cast iron cemented carbides, titanium, zirconium, tungsten, molybdenum.APPENDIX The strength of a brazed joint may be higher than that of the brazing alloy if the thickness of the fill metal is less than 75 m. Copper-brazed joins between steel parts are