Hi,
So im a first year engineering student and we have a project we are working on that most of us dont really have the expertise to figure out. So basically we are making an automated machine to make a particular type of food item that is native to my country.

How it basically works mechanically is there is a cylinder with dough, and a piston that pushes the dough down. The piston is attached to a handle which the user generally turns. We planned on replacing the handle with a motor, So that thw piston can be moved up and down using that. I have attached an image of what we have.

So we have most lf the mechanical bits in place but we have no idea as to what motor we should use. We were told a gear motor rotates both ways and would be a good option but we have no idea on how to decide on the specs. I would really appreciate if someone could give us some guidelines on this and maybe some advice. Thankyou

 

An electric motor requires electricity to power the motor. The first thing you need to decide is will the power be AC or DC?

You need to know if a small, medium, or big motor is required.

A motor delivers torque. You need to measure or estimate how much torque is required. To measure torque, measure how much force is needed to be applied to the handle and multiply that by with length of the arm that is connected to the handle.

You need to know the speed of rotation of the motor. A motors applies maximum torque when it is running at medium speed rather than at slow speed. You need to run the motor at medium speed. Hence you need a reduction gear to connect between the motor axle and the crank axle.

Fortunately, you can do all of the above with trial and error.

An automotive 12VDC windshield wiper motor might just do the job. You may need an additional reduction gear.
If you need more torque you can go to a automotive starter motor.
You may also try a hand drill with an additional reduction gear.

 

That appears to be a simple rack and pinion mechanism, so the input to the shaft does not require very high rpm for that application.
For an economical motor you should have one with a high reduction gear box.
The alternative is to replace the R&P with a worm driven screw, these are often used as Jacks for low rpm-high loads.
A simple way to measure torque required is to use a lever of known length and a spring scale to find the torque (ft/lb) point that the shaft starts to move.
Max.

 

Hi

An electric motor requires electricity to power the motor. The first thing you need to decide is will the power be AC or DC?

You need to know if a small, medium, or big motor is required.

A motor delivers torque. You need to measure or estimate how much torque is required. To measure torque, measure how much force is needed to be applied to the handle and multiply that by with length of the arm that is connected to the handle.

You need to know the speed of rotation of the motor. A motors applies maximum torque when it is running at medium speed rather than at slow speed. You need to run the motor at medium speed. Hence you need a reduction gear to connect between the motor axle and the crank axle.

Fortunately, you can do all of the above with trial and error.

An automotive 12VDC windshield wiper motor might just do the job. You may need an additional reduction gear.
If you need more torque you can go to a automotive starter motor.
You may also try a hand drill with an additional reduction gear.

Hi,
Thankyou so much for ur response!
What do u think about using a gear motor or a servo motor?

 

Thankuo

That appears to be a simple rack and pinion mechanism, so the input to the shaft does not require very high rpm for that application.
For an economical motor you should have one with a high reduction gear box.
The alternative is to replace the R&P with a worm driven screw, these are often used as Jacks for low rpm-high loads.
A simple way to measure torque required is to use a lever of known length and a spring scale to find the torque (ft/lb) point that the shaft starts to move.
Max.

Hi,
Thankyou so much for your response. Yes we it seems that we have to first figure out what the required torque is so will get right to that!

 

Rather than the complication of a servo motor, I would think limit switches would do the trick.
Max.

 

H

Rather than the complication of a servo motor, I would think limit switches would do the trick.
Max.

Hello,
So finally we decided to use a 12V 60RPM 37GB 3A DC Gear motor because it can administer the torque we need. Now we have an issue because we dont know what motor controller to use. The L6203 was suggested to us but other than the data sheet (which has a lot of info i still dont undestand yet) i cant seem to find any infomation online. Will this work woth our motor? Or do we need something else?

 

Do you need to vary the rpm?
A simple 555 circuit should work such as http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
You can use it with 12v.
Or just use a reversing relay if no rpm control required.
Max.

 

Do you need to vary the rpm?
A simple 555 circuit should work such as http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
You can use it with 12v.
Or just use a reversing relay if no rpm control required.
Max.

Thankyou for your response! Yes just the speed and the direction of the motor needs to be changed. So we are using a arduino to feed those instructions. So we just need something to feed the arduino and motor the required power accordingly

 

Forgive my deviation from the current line of discussion, but why not just replace the whole piston assembly with an air cylinder?

If it needs position feedback, mount a position sensor on it to close the loop.

So much simpler than all that motor control monkey business.

 

Thankyou for your response! Yes just the speed and the direction of the motor needs to be changed. So we are using a arduino to feed those instructions. So we just need something to feed the arduino and motor the required power accordingly

The L6203 H bridge should work for you.
Max.

 

Is the bottom of the stroke position or max. force ? If force then might monitor motor current via low resistance sense resistor & comparator. I was going to modify Door 2 with P & N ch. FETS but OP faded away.