lecture10 - Mech 220 Intro to Engineering CAD Assembly...

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Unformatted text preview: Mech 220 Intro to Engineering CAD Assembly Symbols: FASTENERS, WELDING & RIVETING WELDING FALL 2006-07 Inst.: Charbel Seif Office: Extension: e-mail: Wing B - B-303 3629 cs05@aub.edu.lb Inst. Charbel Seif, Mech 220 02/07/11 1 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Assembly types Assembly Elements of Non-Permanent Assembly: •Threaded Fasteners •Keys •Springs Elements of Permanent Assembly: •Riveting •Welding Inst. Charbel Seif, Mech 220 02/07/11 2 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: TYPES OF FASTENERS Inst. Charbel Seif, Mech 220 02/07/11 3 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners x x Threaded Fasteners – Bolts – Studs – Cap Screws – Machine Screws – Set Screws – specialized screw types – Nuts Non-Threaded Fasteners – Washers – Keys – Helical Springs 02/07/11 Inst. Charbel Seif, Mech 220 4 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (4) Machine Screws Threaded MACHINE SCREW: is a small fastener used with a nut to function as a bolt or without a nut to function as cap screw. Standard machine screws are shown (with slotted form). machine screws also come with cross recess. Inst. Charbel Seif, Mech 220 02/07/11 5 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (4) Machine Screws Threaded Inst. Charbel Seif, Mech 220 02/07/11 6 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (4) Machine Screws Threaded Inst. Charbel Seif, Mech 220 02/07/11 7 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (5) Set Screws Threaded SET SCREW: screws into a tapped hole in an outer part, often a hub, and bears with its point against an inner part, usually a shaft. They are made of hardened steel and hold two parts in relative position by having the point SET against the inner part. EXAMPLES of square head and head-less set screws are shown: EXAMPLES of point types: Inst. Charbel Seif, Mech 220 02/07/11 8 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (5) Set Screws Threaded Inst. Charbel Seif, Mech 220 02/07/11 9 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (6) specialized screw types Threaded 6.1 tapping screws: - hardened - form their own thread in a drilled or punched hole 6.2 wood screws Inst. Charbel Seif, Mech 220 02/07/11 10 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (7) Nuts Threaded Nuts are used in conjunction with bolts and cap screws. Available in two wrench styles: square and hexagonal. Inst. Charbel Seif, Mech 220 02/07/11 11 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners- (7) Nuts- Hex nuts & Hex Jam nuts Hex Inst. Charbel Seif, Mech 220 02/07/11 12 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – (7) lock nuts (and washers) Threaded Inst. Charbel Seif, Mech 220 02/07/11 13 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Non-threaded Fasteners – (8) Washers: Plain Plain PLAIN washers: Are commonly used in the assembly of nuts and bolts to provide a smooth surface for the nut to turn against. Inst. Charbel Seif, Mech 220 02/07/11 14 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Non-threaded Fasteners – (8) Washers: Helical spring lock Helical Lock washers: prevents a fastener from loosening due to the vibration or stress. Inst. Charbel Seif, Mech 220 02/07/11 15 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Non-threaded Fasteners – (9) Keys Non-threaded KEYS: used to prevent rotation of wheels, gears, etc.. on their shafts. It is a piece of metal placed so that part of it lies in a groove called ‘key seat’ and protrudes above the shaft and fits into a ‘key way’ cut in the hub. Square key shown assembled Inst. Charbel Seif, Mech 220 02/07/11 16 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Non-threaded Fasteners – (10) Helical Springs Non-threaded Springs are elastic components designed to store energy when deflected. Classified into 1) compression, tension, and torsion type springs. Compression spring representation Tension spring representation Inst. Charbel Seif, Mech 220 02/07/11 17 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Non-threaded Fasteners – (10) Helical Springs Non-threaded Torsion spring representation Simplified spring representation Inst. Charbel Seif, Mech 220 02/07/11 18 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners DRAWING FASTENERS Inst. Charbel Seif, Mech 220 02/07/11 19 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners- (7) Nuts- Hex nuts & Hex Jam nuts Hex Inst. Charbel Seif, Mech 220 02/07/11 20 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Drawing fasteners: Square bolthead Square x Square and hexagonal heads and nuts are drawn across head “A” unless a special reason exists for drawing them across flat “B”. Inst. Charbel Seif, Mech 220 02/07/11 21 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Drawing fasteners: Square bolthead (cont’d) Square Inst. Charbel Seif, Mech 220 02/07/11 22 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Drawing fasteners: Hex bolthead Hex Inst. Charbel Seif, Mech 220 02/07/11 23 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Drawing fasteners: Hex bolthead (cont’d) Hex Inst. Charbel Seif, Mech 220 02/07/11 24 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Threaded Fasteners – x Often the representation of fasteners may be approximate or even symbolic because the notes and specifications are sufficient: » ½-13UNC-2A X3 Reg Sq Bolt » 3/8-16UNC-2A X3½ Hvy Semifin Hex bolt x If an accurate drawing of a fastener is not essential, the W and H dimension of hexagonal and square nuts may be obtained using the following formals: Regular Heavy series » W=1.5*D » H=2/3*D Inst. Charbel Seif, Mech 220 W=1.5*D+1/8 H=3/4*D 02/07/11 25 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Permanent Assembly WELDING SYMBOLS Inst. Charbel Seif, Mech 220 02/07/11 26 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Types of welded joints x Welding process may be divided into at least three classes: – Arc Welding: where heat is generated by an electric arc that raises to the proper temperature the parts to be joined. – Gas welding: involves the use of a combustible gas, such as a mixture of oxygen and acetylene. It is a popular method for field work because it uses easily portable equipment and requires no electrical sources. – Resistance welding: is a heat and squeeze process. The parts that are to be welded while being forced together by mechanical pressure, are raised to the temperature of fusion by the passage of a heavy electrical current through the junction. Inst. Charbel Seif, Mech 220 02/07/11 27 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Types of weld x There are Many types of welds than can be used to join the parts together. Inst. Charbel Seif, Mech 220 02/07/11 28 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Types of welded joints x x x There are five types of welded joints. The types are named by the geometric relationship between the two parts. A useful correlation of joint types and weld types is shown in table below. Inst. Charbel Seif, Mech 220 02/07/11 29 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols Welding types, sizes and positions must be translated into symbols so users of drawings will know clearly all information about a particular weld. The American Welding Society standard AWS A2.4-86 has compiled a listing of all necessary welding symbols. The general symbol serves for every case for every type of weld. Not every weld case would require all aspects of the general symbol. Inst. Charbel Seif, Mech 220 02/07/11 30 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols x x x The general meaning for the “other side versus arrow side” is shown in figure A. B shows an arrow side U groove weld C gives the other side U groove weld. Inst. Charbel Seif, Mech 220 02/07/11 31 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols x x Symbols above the dashed lines are other side symbols. Symbols below the dashed lines are arrow side symbols. Inst. Charbel Seif, Mech 220 02/07/11 32 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols x Additional weld symbols are available: » » » » Weld all around: Means to weld completely around particular joint indicated Field weld: welds are to be done on the construction site. Melt-thru: joints to have 100% penetration in welds made from one side Backing: means an extra piece has been added to serve as spacer around which the weld is made » Consumable inserts: an insert is added to become part of the melt. » Contours Flush: the melt thru is to be made by with the surface by grinding. Inst. Charbel Seif, Mech 220 02/07/11 33 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols x Welds comes in a variety of types and combinations, as we have already seen. Inst. Charbel Seif, Mech 220 02/07/11 34 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Welding symbols x A welding drawing shows a unit or part made of several pieces of metal, with each welded joint described and specified. Inst. Charbel Seif, Mech 220 02/07/11 35 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Permanent Assembly Symbols RIVETING SYMBOLS Inst. Charbel Seif, Mech 220 02/07/11 36 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Riveting x x x x Rivets are used for making permanent fasteners, generally between pieces of sheet or rolled metal. Rivets are round bars of steels with a head formed on one end and are often put in place red-hot so that a head can be formed on the other end by pressing or hammering. Rivet holes are punched, or drilled with a larger diameter from that of the rivet. The shank of the rivet is made just long enough to give sufficient metal to fill the hole completely and make the head Inst. Charbel Seif, Mech 220 02/07/11 37 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Riveting x x Large rivets are used in structural steel constructions The dimension of the rivet head is proportional to the rivet diameter. Inst. Charbel Seif, Mech 220 02/07/11 38 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: Riveting x Plates are connected by either lap or butt joints – Figure (a) above shows a single riveted lap joint. – Figure (b) above shows a double riveted lap joint – Figure (c) above shows a single strap butt joint. – Figure (d) above shows a double strap butt joint. 02/07/11 Inst. Charbel Seif, Mech 220 39 Mech 220: 10th LECTURE ASSEMBLY SYMBOLS: ANSI Riveting Symbols Inst. Charbel Seif, Mech 220 02/07/11 40 Mech 220: 10th LECTURE Mech Thank you Inst. Charbel Seif, Mech 220 02/07/11 41 ...
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