Download
1 / 48
480 likes | 610 Vues
pivo t. galet. came. Designing an animated object From a cam and roller mechanism. Objectives of the task. Analyse objects containing mechanisms; Become familiar with mechanical language; Initiation to diagramming;
E N D
pivot galet came Designing an animated object From a cam and roller mechanism
Objectives of the task • Analyse objects containing mechanisms; • Become familiar with mechanical language; • Initiation to diagramming; • Become familiar with simple techniques of linkage and guidance, adapted to the reality of primary school (inexpensive materials); • Use basic tools for primary school; • Design an articulated model.
Why analyse technical objects? • To get to know them better; • To learn to look at them differently; • To develop curiosity and an analytical spirit; • To inspire new designs; • To maintain and repair them.
Analysis process With the students, determine on what occasions is this object used? Professions Activities
Analysis process In this example, there is an ideal opportunity to present electrical circuits and discuss how they work. Possibility of describing the sequence of parts in movement in a mechanical object.
Analysis process How many parts are there? What is each one’s role? How are they connected? What do you have to say about what materials are used? Why were they used?
Analysis process Are there other similar objects? What comparisons can we make? (materials, shapes, fabrication, energy used…) What are the advantages and disadvantages of each object? (impacts)
What can we do in analysis, at the primary level? • Observe objects and place the vocabulary. • Compare objects responding to the same need (materials, shapes, mechanisms or not…) • Describe the sequence of different operations occurring when the object is in action (kinematic chain).
Reflecting upon the technical object… • What to call the components? • How do the parts move in relation to one another? (rotation or translation movement, guidance) • How are the parts linked to one another? (linkage) • How are they represented? • What materials are used? Why were they chosen? • Can they be recycled? (impacts)
How mechanical objects function Example of actions: Push Pull Turn Press Electrical force … Application of a force
How mechanical objects function Examples of movements: Turn (complete or partial rotation) To move horizontally (left-right translation or vice versa) To move vertically (up-down translation or vice versa) To do both simultaneously (helical) Production of movements
How mechanical objects function Transmission of movement: IS THE COMMUNICATION OF THE SAME MOVEMENT FROM ONE PART TO ANOTHER WITH POSSIBLE VARIATIONS IN SPEED. Examples of transmission mechanisms: Chain and cog wheels Gears Pulley and belt Friction wheels Wheel and worm gear Cam and roller
How mechanical objects function Transformation of movement : IS AN ACTION THAT CHANGES THE NATURE OF THE MOVEMENT (rotation to translation or translation to rotation) Examples of transmission mechanisms: Rack and pinion Rod and crank Cam and roller Crank and slide Screw and rack Screw and nut
How mechanical objects function Examples of results: Roll, move forward, move backward, throw, propel, whip, mix, cut, balance, oscillate, topple… Obtaining a result
The ice cream scoop… • Metal and plastic • 8 metallic and 1 plastic part • Angular action spring between the two handles to ensure they reopen • Rack and pinion system to make the curved part inside the spoon move
The ice cream scoop… • 2 different types of metal • No mechanism • 5 obvious parts • Spoon part probably moulded • Extruded handle, possibly out of stainless steel because of the colour • May be an assemblage by pressing
The ice cream scoop… • Plastic • No mechanism • 1 single part formed by moulding, because you can see the mould line • Injection point at the end of the handle • Form fitting handle • Very lightweight
The ice cream scoop… • 2 types of metal and plastic • 6 metallic parts and 1 plastic part • Spoon formed by moulding, for there is the presence of an injection point on the handle, unmolding points in the concave part and junction lines from the mould • Hollow handle with X shaped reinforcement • Angular action spring • Gear system to make the curved part inside the spoon move • All the metal parts are steel, for there are rust marks, except for the yellow coloured rivet, probably brass • Lightweight
Sequence carried out with students1st validation PREPARATION • Observation of a technical object that produces movement; • Components of a technical object: observation game (association of a symbol to a mechanical part or an action, acquisition of a new vocabulary) • Fabrication of a mechanism in a team (3 choices: round cam and roller, rack and pinion, rod and crank)
Sequence carried out with students1st validation REALISATION • Diagramming their ideas of objects to animate (from a children’s tale); • Making their models. model
Our observations… For the analysis part and fabrication starting from technical drawings: • The students are apt to find mechanical parts; • They diagram an idea relatively easily; • They find solutions and draw them. For the design part: • The students have difficulty finding construction solutions for their model; it is therefore necessary to present models of linkage and guidage before designing; • Give the same problem to be resolved to ease classroom management.
What did we change? • Prepared models of links and guides; • Introduced a diagramming exercise; • Concentrated on a single mechanism; • Guided experimentation with this mechanism; • Preparation of the turn key model that can be easily adapted to several tales; • Introduction of a sheet for diagramming their solution starting from turn key models; • Developed tools for teachers to familiarise themselves with mechanisms.
Targeted competencies… Suggest a provisional explanation by drawing; Suggest stages of fabrication; Note difficulties and make adjustments as necessary;
Targeted competencies… Choose materials and techniques; Manipulate the materials safely; Situate objects in their context and the effects of lifestyle on individuals;
Targeted competencies… Use the correct vocabulary in their explanations; Appropriate forms of representation.
Thanks to… Thanks to Nancy Lane, 4th grade teacher, at La Mennais school in Montréal for her implication in validation, winter 2008 and 2009. Her comments: • Very motivating for boys (very weak student is encouraged because he can help others) • Learning through the game very stimulating • Meaningful for the students • Creates much questioning and curiosity among the students • Commitment and perseverance
Essential knowledge touched upon… Page 158 of the program • Effect of a force on the direction of an object • Simple machines • How manufactured objects function • Design and fabrication of machines • Terminology related to the understanding of the material world • Drawings, sketches, diagrams
