My engineering project

Cave_man

Cave_man

Cave_man

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Im doing a project for my BTEC and its a double unit or something, I have to create a product with a high level of engineering quality or remaster a design of something to improve its system and how it works... blah blah blah and takes months to do, I really couldn't think of anything that wasn't to difficult so my lecturer sorted me and three other classmates out with a task.

The task was to create a hole punch which will electronically punch a hole when you push a button and needs to be portable (not to big and something with can be transported with ease). The punch needs to go through a bio-degradable plastic and 2 layers of some sort of tape stitched with glass to reinforce it (basically talking about 8 sheets of paper).

The problem is where do we start, what calculations are needed, what can power it, how do you control it, what parts etc...

Just thought if anyone has any suggestion it would be greatly appreciated and i know it seem lazy for me to post it but I do need help as we are behind already due to a mixup.
 
Maybe some large solenoids, excellent at producing large forces over very small distances, which is probably applicable to your usage (~1 mm thick I would have thought).

Not going to be small or portable though.
 
i'm thinking a spring-powered punch, retracted (relatively slowly) by an electric motor.

you put the whatever into the jaws, press the button --> *WHAM* it punches the holes, then *Whirrrrr* as it retracts the punches, simultaneously readying it for another use.

this means you don't need big, expensive Capacitors that a Solenoid demands, and it also reduces your power requirements considerably, because the spring-piston system is more efficient than the solenoid design, albeit slower. :)
 
Aod said:
i'm thinking a spring-powered punch, retracted (relatively slowly) by an electric motor.

you put the whatever into the jaws, press the button --> *WHAM* it punches the holes, then *Whirrrrr* as it retracts the punches, simultaneously readying it for another use.

this means you don't need big, expensive Capacitors that a Solenoid demands, and it also reduces your power requirements considerably, because the spring-piston system is more efficient than the solenoid design, albeit slower. :)
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I like, it's only slow when you're changing the paper.
 
Sounds to me like you will need quite a bit of force to go through that lot.

As The_blue said, cams are your friend.

Use a small geared motor with plenty of torque coupled to a cam. Have a return spring on your punch.

To electronically control the punch, I assume it is push button once to do the punch, not push and hold? If you the simplest way would be to use a monostable 555 timer, and work out the time it takes for a full revolution of the cam. Use components to create this time delay.

It is quite an easy thing to construct, as for calculations you need to suss that out. You need to find the force in gf.cm (Gram Force Per Centimeter) req to punch through the material. The select a geared motor with the req force.

Solenoids at that size won't have the req power/voltage ratio.

There is a high street place that specialises in components, starts with an M. They have a range of heavy duty planetry geared motors starting at 4.5v, making it ideal for a battery powered unit.
 
Pinter75 said:
Sounds to me like you will need quite a bit of force to go through that lot.

As The_blue said, cams are your friend.

Use a small geared motor with plenty of torque coupled to a cam. Have a return spring on your punch.

To electronically control the punch, I assume it is push button once to do the punch, not push and hold? If you the simplest way would be to use a monostable 555 timer, and work out the time it takes for a full revolution of the cam. Use components to create this time delay.

It is quite an easy thing to construct, as for calculations you need to suss that out. You need to find the force in gf.cm (Gram Force Per Centimeter) req to punch through the material. The select a geared motor with the req force.

Solenoids at that size won't have the req power/voltage ratio.

There is a high street place that specialises in components, starts with an M. They have a range of heavy duty planetry geared motors starting at 4.5v, making it ideal for a battery powered unit.
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said cam system would take AGES to punch, and would be very very sensitive to loads that are thicker/stronger than the rated load.

Hang on, Why are we doing all this little kids work for him?

Cave_man, you have your ideas. GET TO WORK.

:)
 
I work on photocopiers that feature a hole punch unit and they do indeed work on a cam system.

If its any use to you, i can might be able send you some info that will give you an idea of what you are going to need.
 
Cave_man said:
i know it seem lazy for me to post it but I do need help as we are behind already due to a mixup.
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No, it doesn't *seem* lazy at all, it actualy *is* lazy. :p ;)

They seem to have given you a very specific material to work with, I suspect they are expecting you to precisely work out the failure stress for this composite material as a starting point before you do anything else. Get your materials science books out, or if it is a production material simply ask the manufacturers.
 
is it the project that counts as 2 units ? i designed a bmx part with about 70 pages of pics and words . distinction.

dont use the lecturers suggestion as you wont find it intresting enough to do much work on. you will soon get bored. i spent the first 6 months thinking of an idea even though everyone else had got one straight away

dont think your behind. i did the whole year project over about 3 weekends just because i was so behind from not having an idea. if its something you want to do then its easy .




if your sticking with the whole punch then its got to be an automatic gas powered rifle with 2 barrels that are punch width apart :p maybe some sort of flamethrower on there for when the office is cold
 
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Just be careful with the control aspect that the controller doesn't have a hand free to accidentally stray under the punch. In this case either have a protective screen and/or two pushbuttons which must be held.

I'm assuming they'll be looking at the health and safety aspect of this thing as well.
 
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