Design Technology 3. GRAP 1051
Technology Journal
CHEN_JIAZHEN(KEN)_S3191677
INTRODUCTION
The technology course is quite interesting and it combines theory and practical closely. In metal class I learnt 3 different properties from steel, aluminum and brass include how to cutting and sanding with those 3 different materials. In plastic class I learnt properties of different types plastic. I learnt how to making bio-plastic, making rotomoulding, injection mould, also learnt some way to join plastic and metal such as snap, heat staking, vibration welding and ultrasonic welding. In CAD class I learnt how to use solidworks to make a 3D print mould and create surface. Those knowledge all come to my BBQ tong project.
BRIEF The final assignment was asked us using all the knowledge and experimentation we gained from metal, CAD and plastic class make a BBQ tong utilizing a 400mm x 200mm x 0.8mm steel sheet with minimum 2 metal and 2 plastic processes. The tongs were also required to have a spring without glues, welding and bolts.
Research
my research key words -bbq tong with spring - bbq tong with fork - plastic finger guard
DEVELOPMENT DRAWINGS
MOCK-UP The concept of my BBQ tong design was come from spatula and fork. The spatula part is designing for turning meat and fork is designing for taking meat.
Firstly, I use 1mm cardboard to making a mock-up. Because if I can do and cutting and bending on 1mm cardboard that means I can do those on 0.8mm steel sheet as well. Using scalpel to etching curves and bends them easily. . Using scalpel to etching curves and bends them easily. fold a piece of cardboard to make a srting
CAD I use solidworks to transfer my mock-up to 3D model. I learnt a lots from last CAD assignment such as “sheet metal”. In solidworks you cannot bend 2 different angles in one bend line at same time (sketch). So I cut a triangle and bent separately. Then I use “loft” tool to connect it all up. When making the phone cradle assignment, we learnt how to make a 2 parts mould for the object could be sent to be 3D printed. This time I also use the same way to make my injection mould.The CAD also allow to create a Dxf which would allow the design as a flattened model to be laser cut. REV No. -
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learnt how to do CAD injection mould from last project
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learnt how to make exploded view from “pulley” project.
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METAL printing
printing 1:1 technical drawing and paste on the 0.8mm steel sheet. Cutting 1:1 technical drawing and use double-side tape pasted on a 0.8mm steel sheet. Therefore I can cut and bend steel sheet clearly
drilling
curve cutting
Actually the band saw doesnt allow to cutting a curve. So I cutting like this. Cut blue lines first then red lines.
bending
Put the sheet metal on this magna bender, aim at bending line. After that push magne-switch to lock the metal then follow the graduation to bend whatever angle you want.
Before cutting out thebody pieces I used a hole punch to mark and then drill out all the pivot. Then I use two slips to hole the metal sheet and aim at the hole. After that I follow the technical drawing (which sticks on the metal) to drilling holes.
after bending, I can cut the fork part
cutting
ThirdlyďźŒI use metal band saw to cut the 2 parts. But I did not cut
the fork part at this time. cut the curve after bending,because it is too narrow to bend
When I bent curve I left some part put of the magna bender, then bend it, it will be a curve.
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PLASTIC FINGER GUARD
In Plastic class, I discussed with Libby, i decided to use snap and overmoulding to make FINGER GUARD. First plastic process I decided to do a snap. I use solidworks created a 3D injection mould.Actually snap is a good way to join plastic and metal. It is easy to make. But the shortcoming is the finger guard cannot cling the bbq tong surface. Because it is hard to calculate the dimension( the space between snap and metal surface) accurately, a little error amount will lead the snap slack. Comparatively speaking overmoulding is much more strong the snap. I would cut two pieces of timber to clip the metal surface.
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Injection Moulding Process.
1.Guide Pins – fixed to one half of the mould and align the two halves by entering the holes in the other half. 2.Runner – passageways in the mould connecting the cavities to the sprue bush. 3.Gate – Frequently the runner narrows as it enters the mould cavity. 4.Sprue Bush – Tapered hole in the centre of the mould into which the molten plastic is first injected. 5.Mould Cavity – The space in the mould shaped to produce the finished component(s). 6.Ejector Pins – These pins push the moulding and sprue/runner out of the mould.
EXCURSION the excursion of PDM gave me an view into how moulding and injection moulding works in industry which is very helpful for me .because I got a better understanding of the injection moulding process and how the colour is mixed. And after that excursion we have a injection moulding assignment that I can do some practice from theory. Then in CAD class we learnt how to make a moulds 3D printed. In work we learnt how to make the parts using silicone. All of these were very useful and I can use these knowledge to make this finger guard.
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FINAL I use a spring from a normal BBQ tong and bought a book bending rivet. Actually they are not fit. I filed the spring hole and rivet surface and use hammer to join them.
There are still some problems I need to pay attention 1, the holes I drilled were not on a centerline. The sheet metal was moving when I drilling. Next time maybe I need 2 pieces wood to hold that. 2, I bent to much angle that I want, the 2 pasts BBQ tong looks like a little bit unbalance. 3. The fork part is still to narrow. When I cut that the sharp point got some change.
ALL in all in this semester I learnt a lot from TECHNOLOGY. Like the properties of different materials, the skill of making metal stuff, improve my CAD technique. All of this experience and knowledge can apply my future design.
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