Automated Monoblock Pill Filling Station

Fall 2022 - Spring 2023
Machine Design - Kinematics and Kinetics &
Machine Design - Elements
Project Overview
The scope of this project was to create a monoblock pill filling station for a small batch vitamin distributor. A fully automated system must fit in a 20"x20"x40" frame and for 12 x 75cc pill bottles, convey, fill, and fully cap before exiting the system. Small spherical beads were used as pill surrogates. The project was sponsored by Norwalt Design and Omega Design.
My Contributions
For this phase of the project, I worked in a variety of the subsystems to create the final functional prototype. I wired, programmed and connected the motor to an Arduino Uno (C++) to control the motion of the rotary table. I also had a large contribution in the assembly process of the design and iterating each of the subsystem components, such as the cap placement slide, the cap tightening screw, the rotary table, and the guide rails of the system. I played a crucial role in helping coordinate a design team to finish the functional prototype in the later stages of the semester.
Final prototype (December 2022)
Final completed design (May 2023)
Prototype Design
Completed December 2022
Recipient of the People's Choice Award at the Fall Design Showcase (2022).
For this phase of the project, I worked in a variety of the subsystems to create the final functional prototype. I wired, programmed, and connected the motor to an Arduino Uno (C++) to control the motion of the rotary table. I also had a large contribution in the assembly process of the design and iterating each of the subsystem components, such as the cap placement slide, the cap tightening screw, the rotary table, and the guide rails of the system. I played a crucial role in helping coordinate a design team to finish the functional prototype in the later stages of the semester.

The final prototype operates by performing each of the required tasks (conveying the bottle, filling it with 30 pills, placing a cap onto the top, and tightening the cap) by a seperate subsystem, all placed around a rotary table. The bottle transfer subsystem is handled by a long, acrylic chute which folds in three sections to reduce the size in storage. When fully extended, fasteners join the sections to create a rigid channel to load in the 12 bottles before operation begins. During operation, an Arduino Uno (controlled by a simple on/off switch) connects to a motor belt system to turn the main rotary table. As the rotary table moves, the bottles from the chute drop down into the designated slots as guide wires push them to the correct orientation to prevent jamming.

Pill filling is controlled by a rotating cylindrical system which can store 30 pills per tube for 12 tubes (the size of a batch). When the bottles travel underneath the system, a motor turns the pill filler slightly to deposit the contents of a single tube into the bottle below via a hole in the base plate of the mechanism.

Cap placement requirs minimal assembly as well as a small extending slide attaches the top of the subsystem to allow 12 bottle caps to be loaded before operation. Two metal tongs at the base of the slide hold the caps at a slight angle to allow the bottles to drag the cap out of the system and on top of the bottle. A hinged roof is added to push the caps down on the bottle necks squarely.

The bottles then reach the third subsystem station, the cap tightener. A lead screw is used to descend the system on top of the bottle until contact is made with the top of the bottle. The cap tightener block, a rubber mounted system, rotates via a motor to fully tighten the cap onto the bottle. Once tightened, the lead screw retracts the system upwards to allow the bottle to continue its journey around the rotary table counter clockwise. A small block finally knocks the bottles out of the device and into a storage container positioned below.



A fully functional prototype is shown below. This design serves as a prototype for the final design, with each of the subsystems to be robustly manufactured by laser cutting acrylic, 3D printing, or CNC/machining methods. Extensive design validation and verification will also follow in the spring 2023 semester. The project is set to be completed by May 2023.

Final Design
Completed May 2023.

For this phase of the design, I took a larger leadership role in assisting in each subsystem and especially with completing the automation and pill filling components. I created the CAD models of the pill filling subsystem to be laser cut and wrote the completed automated code to control the rotary table and pill filling systems. I assisted in the electrical wiring and circuitry as well. I iterated several of the designs to the one shown, including the passive cap placement and cap tightening subsystems. I performed design validation and failure analysis on the system as well.

The final design was rotated to a vertical configuration as shown. The bottle transfer subsystem was iterated to be more compact, easier to store, and with higher precision control on bottle placement.

The pill filling system saw several design changes. First, the system was made out of laser cut acrylic, brass tubes, PVC, and plastic filament. A pill tank was created out of PVC tubing to house 450 pills. A custom 3D printed agitator was designed to sit inside this tank and ensure each pill tube was fully filled and to prevent overfilling when in motion. Support plates and bracing pieces were laser cut out of acrylic and hold 12 brass pill tubes. On the bottom of the system, a sensor detects when a bottle reaches the system which tells the Arduino to dump 30 pills into the bottle. When a bottle is not in the system, the assembly shakes back and forth to ensure pills are fed into the tubes.

Cap placement was iterated to be more reliable after repeated uses. Metal tongs were fashioned to both hold the cap in place and to push it flush onto the bottle as it moves. This passive system was a large success.

Cap tightening was reverted back to a passive design and uses a friction plate block, made out of machined aluminum with foam overlayed on the edge, and a plastic roof to apply a downwards pressure during tightening.

The rotary table was made out of laser cut acrylic which removed tolerancing errors on the bottle position. This vertical configuration allowed for a direct drive motor to be attached. The wiring for both motors are fed into a soldered breadboard, two stepper motor drives, and an Arduino Uno.

The code of the system controls the pill filling subsystem and the rotary table, the two major motion elements of the design. The system operates by first controlling the rotary and moving the bottles through the system until a bottle reaches the pill filling subsystem. The pill filling assembly at this point stops shaking, rotates to the next filled tube, and empties it after the bottle and pill tubes have been adjusted to the correct position. After a brief delay, the system resumes motion until the next bottle comes.

An example of each subsystem in action can be observed by the full system demonstration shown below. For more information on this project, please reach out!

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