Technology Unit Notes Answers (2020) PDF

Technology Unit Science & Technology 306 Ms. T. Agostino Name: __________________________________________ Teacher Copy - Answer key Topics Technical Drawings Views and Projections...

Technology Unit Science & Technology 306 Ms. T. Agostino Name: __________________________________________ Teacher Copy - Answer key Topics Technical Drawings Views and Projections Constraints Properties Materials Mechanical functions Motion systems Types of Technical Drawings: Type Example What to include name of parts force and motion symbols design plan / ______________________ diagram of principles represents the operation Design Plan of Garlic Press technical diagram name of parts _______________________ links and guidance symbols _______________________ legend for materials represents the assembly Technical Diagram of Corkscrew ______________________ freehand drawing sketch with proper basic and geometric lines Cut-away ________________ view of object as if sliced vertically or horizontally to show hidden cross-sectional view internal parts, often used for anatomy Projection with pulled apart exploded view and labeled, numbered parts, often with assembly instructions 2 Drafting Lines 1. Geometric Lines: _________________________________________________________________________________________ drawing lines and curves with a ruler and compass Examples: Finding the center of a circle from the Drawing an arc, using a compass, from lines intersection of center lines. Drawing the rounding of a corner (as in the diagram of a table shown below) 3  2. Basic Lines: lines that represent the details of a simple part of a technical object Name of Basic Description Use Example Line Thick Shows the contours or ________________ visible outline of an Line/contour object Medium Shows the thickness contours or ________________ hidden Dashed line outlines that are Line/contour not visible in the particular view Fine (thin) Shows the center Small dash of a circle or ________________ center in center other symmetrical Line/extension shape Fine (thin) Shows the ________________ extension boundaries of a Line dimension Fine (thin) Shows the length of a part of an ________________ dimension object Line & *always in mm* Leader line = leader line for a dimension Fine (thin) Shows the surface ________________ hatching Slanted created from a Line Equally sectional view spaced ________________ cutting plane Thick To indicate the Line Arrow ends plane of a cross- section 4 Scaling Reduced or enlarged representation of the actual object’s size written as a ratio of __________________________________________ drawing : actual Example: Actual Size Scale Reduction Scale Enlargement The drawing is the same size as The drawing is the The drawing is the 2x bigger than the real the real life object. 2x smaller (or half life object. the size) than the real life object. Practice Question: Determine the scale for each object drawn below, using your ruler and the real life measurements given. Object 1: CD case Object 2: Nut Drawing Actual Scale Drawing Actual Scale (mm) (mm) (mm) (mm) F 54 18 A 61 125 54:18 B 142 61:125 G 62 21 = 3:1 71 This is a _________________________________________. scale reduction This is a _________________________________________. scale enlargement 5 Dimensioning indicates real life (actual) values for length, width, height and depts of an object as well as the diameter of holes _________________________________________________________________________________________________________________ and radius of curves for parts of an object _________________________________________________________________________________________________________________ can be placed outside the drawing or inside, whichever is clearer dimension lines should not be crossed mm usually indicated in _____________________ dimension lines: Example of a skateboard drawing with dimensions: dimension symbols: = diameter of hole or circle _______________________________ = radius of circle or curve _______________________________ = angle in degrees _______________________________ Practice Question: Below is a diagram of a deodorant stick, which has been drawn full-size to scale. a) What type of drawing or view is used to represent the deodorant stick? ___________________________________ cross-sectional view 1:1 b) What is the scale for this drawing? _____________ since the measurements indicated on the drawing match the measurements by the ruler c) For each number in the diagram, give the name of the basic line drawn. 1. dimension 2. extension 3. visible 4. hatching 5. leader 6. hidden 7. center 97 mm d) How tall is the stick if it stands upright? _____________ How wide is the rotating knob? _____________ 24 mm 89 mm How long is the screw? _____________ 97 - 8 = 89 mm ⇒ Workbook: p. 164 # 1, p. 165 #4b, p. 172 #5, 6, 7, 9 p. 173, p. 177 #5-6, p. 179 #4-6, p.180 #5-6 6 Projections Projection: 2-D representation of a 3-D object Types of projections Light rays from object multiview ________________________ are perpendicular to the plane of the paper ___________________ orthogonal Projection Light rays from object ________________________ isometric are perpendicular to (axonometric) the plane of the paper __________________ oblique Light rays from object are oblique to the plane Projection of the paper Multiview Isometric Oblique 7 How are light rays perpendicular to the projection plane in orthogonal projections? Notice the perpendicular relationship Comparing orthogonal and oblique projections: orthogonal Multiview Isometric oblique 8 Multiview Orthogonal Projections ***most common EXAM*** Use: in drafting, showing representing exact angles and measurements 6 There are _____________________ represented in 2-D. _________________________________________________________________________________________________________________________ hidden lines are used to show edges that are behind and can not be seen in the view The most common views shown in technical documents are: top view, front view, right-side view The 6 views: Top Bottom Front Rear Left side Right side Understanding the hidden lines: Keep true edges in solid lines. When edges are not visible in the view, but exist underneath, above or deeper in the object, use dashed hidden lines. 9 Practice Question: Draw the Top view, front view and right side view for the isometric pictorial shown below. Practice EXAM Question 1: 10 Practice EXAM Question 2: Practice EXAM Question 3: Which view represents the LEFT side view of the following isometric projection? No hidden lines are drawn when the object in view is made of cubes with visible edges. A) B) C) D) 11 Isometric Orthogonal Projections Isometric projections are one type of axonometric projections. All axonometric projections are orthogonal projections in which _______________________________________________ the object is rotated to show all 3 dimensions _________________________________________________________________________________________________________________________ In isometric projections, the object is angled equally toward the sheet of paper (120°). Use: for a pictorial of an object from which views can be drawn, showing exact measurements, but altered angles Some isometric projections appear as perspective drawings. Perspective drawing: _____________________________________________________________________________________________ made to look like real life, with depth (not axonometric) Use: do not show actual scale or dimensions, but preferred by architects to illustrate what the eye actually sees For example: 12 Oblique Projections Object is represented in 3-D. depth is drawn at an oblique angle One face of the object is drawn parallel to the paper, but the ___________________________________________________. The height and length of the object are accurately drawn. Depth is not accurately represented - it is often smaller than the actual object’s depth. Examples: ⇒ Multiview Projections Worksheet ⇒ Workbook: p. 167-170 p. 179 #3, p. 180 #7 13 Constraints Constraint: ___________________________________________________________________________________________________________ a stress (or force) on a material caused by external forces Type of Constraint Symbol Description Example when forces tend to Crushing a can crush, push down on a Pushing a button COMPRESSION material Squeezing a sponge when forces tend to Copper stretched into TENSION stretch, pull on a wire material Tug of war when forces tend to Hands wringing a towel twist a material Earthquake twisting a TORSION bridge when forces tend to Clothes on a clothesline bend a material Sitting on a soft cushion DEFLECTION (bending) when forces tend to cut, Scissors cutting a paper SHEARING tear a material Practice Question: Identify the constraint in each of the following. Draw appropriate constraint symbols on the diagrams. Metal trimmers shaping metal shearing _____________________________ compression Copper flattened ____________________________ tension Copper stretched into metal ____________________________ Stepping on an empty coke can ____________________________ compression Hanging on a rope while rock climbing ____________________________ tension Hands wringing a wet towel ____________________________ torsion Hands squeezing a wet sponge ____________________________ compression Clothes weighing on a clothesline ____________________________ deflection Jumping off a diving board ____________________________ deflection top of support beam ____________________________ compression torsion deflection compression __________________________________ ____________________________ ____________________________ 14 Properties Materials for objects are chosen based on their ability to resist constraints. Property Description hardness resists denting or scratches or permanent deformation stretch without breaking, usually associated with metals used in ductility framework for shaping an object flattened or bent without breaking, usually associated with metals malleability used in framework for shaping an object elasticity returns to their original shape after a constraint resilience resists shock without breaking stiffness/rigidity retains shape after undergoing constraint brittleness breaks or shatters easily without undergoing deformation first electrical conductivity carry an electric current thermal conductivity transmit heat insulator does not transmit heat resistance to corrosion resist oxidation from air or water such as the formation of rust Materials Categories of materials: metals and alloys, wood, plastic, ceramic, glass, composite (reinforced matrix) Metals and Alloys Properties Examples and Use - lustrous (shiny) - malleable Iron (Fe) – cars, utensils, appliances, poles, cables - ductile - electrical conductor Aluminum (Al) – foil, cans, house siding panels Metals - thermal conductor corrodes when exposed to Copper (Cu) – wires, musical instruments oxygen and water (unless treated * corrosion of iron is called "rusting" ex. stainless steel, aluminum, etc.) Corrosion is an oxidation reaction. Some metals, such as nickel, aluminum and chrome are corrosion resistant. Stainless steel contains chromium, which makes it resistant to corrosion, unlike unprotected carbon steel. Alloy: ________________________________________________________________________________________________________________ homogenous micture of 2 or more metals melted together to enhance properties (some alloys are metals mixed with non-metals) 1. ________________________: ferrous alloy metal + iron Ex. steel, cast-iron (iron + more carbon = harder) 2. ________________________: non-ferrous alloy no iron Ex.: brass (copper + zinc), bronze (copper + tin) often used for easy molding and shape memory 15 Wood and Modified wood - hardwood: __________________________________ high level hardness o from deciduous trees Examples: maple, oak, birch o used in flooring and furniture - softwood: __________________________________ low level hardness o from coniferous trees Examples: pine, spruce o used in residential construction, paper Mechanical properties of wood vary according to species of the tree, growth speed and water content. Properties Degradation - hardness - dry wood breaks easily - elasticity - natural moisture and cold - resilience increase hardness and resilience - low thermal and electrical - heat increases malleability conductivity - lightweight - rotting caused from - colors, shades, aesthetic appeal microorganisms and fungi - easily shaped and carved - damage from bad weather v Modified Wood: ________________________________________________________________________________ treated wood or wood with glue, preservatives, plastics Examples: § Plywood – sheets of wood glued together use: building construction, tables § Particleboard – wood chips glued together use: building construction, toys § Fibreboard – smaller wood fibres glued together use: furniture, floating floors More resistant to bad weather Properties Can be made from small trees Can be combined into larger structures than pure wood Can be made with wood chips and waste plywood particleboard (wood chips) fibreboard ⇒ Workbook: p. 182-183 (omit #6) p. 184 #1-2, p. 185, p. 186 #1-5 16  Mechanical Systems mechanical = movement or motion Types of Motion: Type of Motion Description Examples Symbol drawer unidirectional in a straight line, side to sliding window or door translation side or up and down (rectilinear) bidirectional wheels unidirectional door circular laptop screen rotation pair of scissors bidirectional CW = clockwise CCW = counter-clockwise screw unidirectional bottle cap spiraling helical (rotating and translating bidirectional at the same time) Practice Question: Draw appropriate motion symbols on the following technical objects. a) trumpet piston valve b) piston in crank system c) C-clamp d) ceiling fan 17 Typical Mechanical Functions ***most common EXAM*** Function Examples join parts of an object gluing shelves to panel linking nailing frame to wall direct or lead the motion of moving parts sliding window open guiding turning rod around pivot pin fill in gaps between parts to prevent sealing leakage or close up joints to make sealant, caulking (of baseboard), them airtight or water tight - dental sealants block fluid, dust, sound, heat from entering oil and grease (for threads and minimize friction to allow smooth lubrication ball and roller bearings) movement between parts Linking Guiding Sealing Lubricating Linking Common linking components: ___________________ screw ____________________ nut and bolt _______________________ rivet _________________ pivot pin _________________ welding - heat metal to melt and join metals together Symbols: soldering: uses filler metal to join metals Screw or bolt Nut Nut and bolt 18 Types of links: determined by the motion between the linked parts Type Description Example Advantages/Disadvantages Advantage:permanent, complete, Fixed link no movement easy to transport Disadvantage: may need to be replaced if parts become separated Advantage: allows rotation Rotating link rotation Disadvantage: wear and tear Advantage: allows translation Sliding link translation Disadvantage: wear and tear translation Advantage: allows both transation Sliding-rotating link then and rotation rotation Disadvantage: wear and tear joystick Advantage: useful in car joints rotation is multiple and directions heavy machinery Spherical link ball joint Disadvantage: wear and tear Advantage: allows helical Spiral link helical motion Disadvantage: lubrication needed (because of threads) 19 Characteristics of links: **NOT on Secondary 3 Exams** Direct or Indirect Parts held together without a linking Parts held together by linking component components, such as glue, nails, screws, rivets, bolts, welding, etc. Ex. pen and cap, container and lid Rigid or Flexible (Elastic) Linking component is not flexible Linking component or one of the two parts can be deformed and return to its original position Ex. rubber, springs Removable or Non-removable (Permanent) Linked parts can be separated without Linked parts can not be separated damaging the surfaces or the linking without damaging the surfaces or the component linking component Ex. pen and cap, Ex. nailed parts, glued screws can be unscrewed parts Complete or Partial Linked parts can not move Linked parts can move independently independently of one another without while still being linked together breaking the link 20 Guiding Guiding control: the part of the object that _____________________________ directs the moving part (acting as guide) Guided component: the part of the object that is ___________________________ being guided by the guiding control Type of Guiding Guiding Control Examples Tracks on drawers Window grooves Translational grooves, tracks Bolt in door hinge Axle of bicycle wheel Rivet in a pair of scissors Rotational cylinders, rods, axles, holes Threads of screw Threads of sink faucet Helical threads Practice EXAM Question: A part of a system used to raise and lower an anchor on a boat is shown. What is the typical mechanical function of each labeled component (linking, guiding, sealing or lubricating)? Bow roller: ___________________________________ guiding Shackle: ___________________________________ linking Most bow rollers are made with friction-free coated stainless steel. With friction, they would require ________________________________. lubricating 21 Practice Questions: 1. Complete the table below about linking and guiding. 4 Type of Link Type of Guiding Guiding Guided Characteristics (motion of Control Component of Link guided part) direct rigid none fixed none none non-removable complete indirect rigid rotating rotational rivet blade non-removable partial direct rigid helical threads of bottle cap spiral removable bottle complete 2. Below is a diagram of ball and socket joint that can be found in the hip or shoulder. Refer to the diagram above to answer the questions about the typical mechanical functions of this joint in the human body. a) What is the MAIN typical mechanical function of this joint? Explain your answer. guiding - directs rotational movement of bone b) What type of link is created by this joint in the human body? ___________________________ spherical c) Provide the characteristics of the link between the parts. _________________, direct _________________, rigid _________________, non-removable _________________ partial ⇒ Workbook: p. 188-189 22 Motion Systems The two types: 1. Motion transmission system: the SAME type of motion is relayed from driver to driven _________________________________________________________________________________________________________________ 2. Motion transformation system: ________________________________________________________________________________________________________________ DIFFERENT type of motion is relayed from driver to driven ◦ Driver: _______________________________________________________________________________________________ component in object that received force to set in motion ◦ Driven: _______________________________________________________________________________________________ component in object that receives the motion from driver ◦ Intermediate: located between the driver and the driven. _______________________________________________________________________________________________ carries motion from driver to driven – not all motion systems have an intermediate Examples of intermediates: chains, belts Practice Question: Indicate whether the following are example of motion transmission or motion transformation systems. a) corkscrew: ____________________________ transformation b) clothesline: ____________________________ transmission c) wheels of a train: ____________________________ transformation d) lip gloss/chap stick: ____________________________ transformation e) manual eggbeater: ____________________________ transmission f) wrench: ____________________________ transformation 23  can the driver and Motion Transmission Systems the driven switch? System Symbol Description Reversibility - toothed gears - rotation to rotation Yes gear train - gears without teeth Yes - motion relies on friction friction gear between parts - rotation to rotation wheel - threaded rod with gear(s) No - rotation to rotation worm is always worm and worm gear - one full turn of worm moves the driver, the or wheel one tooth = speed wheel can not wheel and worm gear worm decrease move the worm - toothless gears called “pulley” Yes with belt joining them belt and pulley - rotation to rotation - gears called “sprocket” with Yes chain and sprocket chain joining them - rotation to rotation Speed Changes: ______________________________= more teeth ______________________________= larger diameter ______________________________ slower movement because, it takes longer to complete 1 full revolution speed decrease (driver is smaller than driven, small to big): speed increase (driver is bigger than driven, big to small): 24 Direction of Movement: gears in contact move in ________________________________ opposite direction gears on the same side of belt or chain move in the ______________________ same direction gears on opposite sides of the belt or chain move ______________________ opposite direction opposite direction Look out for twisted belts è Examples of Motion Transmission Systems Gears with rotational axes that are perpendicular (90° shafts) are examples of bevel gears. 25 Motion Transformation Systems System Symbol Description Reversibility - rotation ↔ translation Yes rack and pinion rack = toothed bar - rotation → translation screw gear No type 1: screw rotates, nut translates (within each type 1 type 2 type 2: nut rotates, screw translates type) - rotation → translation No cam and follower cam = egg shaped or circular with axle off-center cam is the driver - rotation ↔ translation Yes connecting rod and crank Examples of Motion Transformation Systems Rack and pinions: Screw Gears: Cam and Followers: Slider-Crank: ⇒ Workbook: p. 190-196 26 Final Exam Appendix Symbols of Motion, Force and Constraints: MOTION FORCE CONSTRAINTS Note: there are additional constraint symbols that you should be familiar with Some Symbols of Mechanical Components (used in diagrams): Screw or bolt Nut Nut and bolt Complete link (2 surfaces) Free in rotation and Free in rotation Complete link Free in translation fixed in translation and translation No movement possible and fixed in rotation (rotational guide) (helical guide) (translational guide) Angular spring Compression spring Gear (toothed) Wheel or pulley (torsion spring) (Front view) (Front view) Tension spring Ball joint Gear Pulley (extension spring) (Side view) (Side view) Rack Worm (threaded rod) 27