Automated Tooth Paste Dispenser

By: Cameron Bauer

Design OverviewTooth Brush Feeding System-Stack tooth brushes in these cartridges.

Rack and Pinion Dispenser

Pressure Vessel

How the System Works1. The toothbrushes are loaded into the cartridges, these will hold well above 50 tooth brushes.2. A toothpaste bottle is screwed into the vessel and the endcap is screwed on.3. (automation starts)The vessel self primes.4. The rack and pinion moves the dispenser to the first track and stops when the laser shines

through the hole into the eye of the optic sensor. At this point track one starts moving until the optic line of sight is obstructed by a toothbrush head. The working fluid is pumped into the vessel and stops when a fluid meter has measured a specific amount of volume. (This is the amount of toothpaste forced out)

5. The track begins to move the brush again until the laser makes contact with the sensor again at which point the track will continue to move until obstructed by another tooth brush.

6. When the cartridge runs out, the microcontroller will sense that the motors have spun too long without being stopped. The rack and pinon will then move to a new track and make connection with a new optic sensor. It will then repeat the same process then move on to the third track.

7. In the meantime you can refill the empty cartridges while the machine is still running.

Pressure Vessel Design:

• The pressure vessel uses a non compressible working fluid. Using a non compressible fluid allows for an exact amount of toothpaste in each cycle.

• A pressure vessel is a unique addition that allows any shape tube to evenly compress.

• The even compression allows the tooth paste to flow out evenly as intended. Some tooth pastes have patterns in the paste which would not be altered by this process.

• The Drain Valve and Primer Valve run to a fluid reservoir. The pump draws from the reservoir.

1. (manual process)Screw tooth paste tube into the threaded pressure vessel fitting.

2. (manual process)Screw on bottom end cap.3. (Fully Automated)When you press start, the

electronic valve on the bottom of the cap will close, the electronic primer valve on the top will open, and the pump will start pumping fluid into the vessel until fluid starts coming out of the primer valve. The system then knows it is primed and the valve shuts.

4. The pump is inline with a digital fluid meter which communicates with a microcontroller. The microcontroller processes how much fluid enters the chamber.

5. The fluid is incompressible so the device can dispense an exact amount of toothpaste each time. (volume of fluid in = volume paste out)

Design

Process

Primer Valve

Pump and Fluid Meter

Drain ValveEnd Cap

Pressure Vessel Animation

Complete Assembly Animation

Dispense System Features

Assembly tracks for tooth brushes

Laser

Rack and Pinion

Optic Sensor

Drive Belt Motors

How Does the Controller know When to Dispense?

This circuit I designed features a wheat stone bridge, a photo resistor, and an op-amp with no feedback.

The laser connected to the dispenser tube bracket shines through a hole in the base and into the lens of the optic sensor where the photo-resistor is located.

When a toothbrush comes through the assembly track, the laser is cut off from the optic sensor. This causes a change in resistance and the wheat stone bridge will output a positive voltage to the non inverting terminal. This will cause the op amp output to rail to 3.3 V, sending a digital “1” to the controller.

Manual Operation if Automation FailsIf needed, this system can be operated manually when the system power is off. The brushes can be slid along the tracks manually or you can turn the belts by hand to make them slide.The pressure vessel can be hooked up to a manual hand pump or you can apply a dc voltage to the terminals to activate the pump.

Discussion

In a factory environment, this system can stand alone from start to finish. However, the design allows for modifications that will enable a higher volume of toothbrushes and also different feeding systems.To implement this in a factory, depending on the necessary output of brushes, more tracks can be added without changing the design. Multiple pressure vessels can also increase the production rate.If there is already a feeding system, this design will allow the brushes to be added without using the internal stacking cartridges. If you take a close look at the Solidworks model, the brushes can be fed straight through a hole in the back where the belt passes into the cartridges. The cartridges can also be removed. There would be some fine tuning for this machine. Depending on the height of the tooth brush, the dispenser height would have to be altered which is why it is adjustable. The amount of toothpaste would also have to be tuned, however, this is easy as all you would have to do is edit the code.Some potential issues may be that the cartridges could jam due to the toothbrushes not stacking perfectly. For this issue, trays could be made to hold the brushes which would all stack perfectly in the cartridges. These trays could be reused.There should be no issue with lead time as one cycle should theoretically take much less time than the 22 second maximum.

Files:

The Solidworks files are all located in the link below:

https://www.dropbox.com/sh/qu721lo4velst6y/AAB_bxl03GMjNfvaQVz8nyR_a?dl=0