Week 12 & 13

(30MAR - 05APR) (06APR - 12APR)

Week 12 & 13 - CAD Part and Assembly Creation for Final Alpha Prototype

For Week 12, we identified that we had three sub-assemblies for our bottle opener, so we divided ourselves into three teams with two members per team:

Bottom Housing : Greg & Charley
Top Gripper: Kevin & Armando
Linear Lifting: Ty & Stefan

Each team worked on creating the CAD parts for their respective sub-assembly, along with the necessary engineering drawings. Below is the summary of the work done by each sub-team.

Bottom Housing Team Summary

The purpose of the bottom housing sub-assembly is to: (1) attach the lifting and top gripping sub-assembly and (2) allow a set of neutral point of contacts for the jar/bottle to exist so that a counter-torque force can hold it in place while the top gripping sub-assembly unscrews the lid. To create these neutral points of contact, a rack and pinion setup was designed for the purpose of "squeezing" the jar/bottle to create the counter-torque.

A Final CAD mock-up of the rack and pinion gripper sub assembly.

The first part designed for the bottom housing was the bottom base; this part had the most revisions, as it needed to accommodate screw holes for other parts of this sub-assembly, as well as a way to connect the other sub-assemblies. Originally, the base had a circular front that contoured the spot where the bottles/jars would sit, but when it came time to combine the sub-assemblies, these features had to get modified out.

There are exactly 20 holes on the base: eight 0.14 inch diameter to connect the lift assembly to the base, eight 0.2 inch diameter holes for the gearbox and motor housing, and four tapered holes for the shell housing. The 5.5 inch diameter circle with the six 0.75 inch diameter circular valleys is for the interface of the rubber padding that the bottle/jar rests on.

The rubber bottom is a simple part with a slightly complex pattern for the internal ridges. The reason why the part has a pattern is because of aesthetic purposes, most appliances that have a rubber holding dock or area that has a pattern, so it is easier for the user to center their jar/bottle before starting the appliance. Rubber was chosen since it is easy to clean and resistant to most liquids.

The most intricate part designed for the bottom sub-assembly is the shell which houses the rack and pinon, the gripping arms, and the electronics needed to run the appliance. As with other modern appliances, the housing unit would be molded out of plastic. Essentially, the shell is a 17 inch x 17 inch x 10 inch cube with rounded corners and 0.5 inch thick walls. Section A-A is the front face of the device that faces the jar/bottle to be opened and houses the rack and pinion. Section B-B is the back of the shell which has a maintenance hole that a back panel covers, as well as the place for the plug to come out of. The purpose of the maintenance hole is to allow the user to unscrew the panel inside the shell that keeps the rack and pinion in place.

A simple panel was designed to keep the rack and pinion in place on the internal shelf of the housing shell. The hole in the center of the panel is for the axle that connects the gearbox to the pinion gear.

The engineering drawing of the back panel of the shell housing. A small indent was made at the bottom to allow the user to pull off the panel. The holes are tapered on this panel to allow the screw heads to be in flush with the rest of the panel.

A simple rounded top was made to cap off the rack and pinion housing. Ideally, if maintenance needs to be done to this sub-assembly of the appliance, only the top and possibly the back panel needs to be taken off - this should not be difficult, as both use a similar screw type.

The engineering drawing of our rack and gripper combination. Originally, we were going to make these two parts separately and insert the gripper, but since they're both going to be made from the same material, we figured it'd be easier to design them both as one part.

This the design for our grippers. There are going to be 6 of these in total, 3 on each side - this way we can accommodate various bottles/jars of ranging diameter and height.

The engineering drawings of the gearbox housing. The housing is modeled off of simple utility electrical boxes by having one part be a shell while the other acts as a cap.

The engineering drawings of the motor housing components. Like the gearbox housing, the motor housing is modeled off of simple utility electrical boxes. The holes on the face of the box is for mounting the motor to the shell while the hole on the side is for the wiring of the motor.

The engineering drawing of of the motor housing unit assembled.

The engineering drawing of the gearbox assembled.

The final sub-assembly for the bottom housing with a BOM.

Top Gripper Team Summary

Armando and I split up our duties for the top sub assembly - I worked on the internal housing that contained the planetary gear system and Armando then worked on an external housing that would house the entire sub-assembly and be able to be adapted to the lifting sub-assembly.

The planetary system consists of a sun gear, 3 planet gears, and a ring gear. The sun gear rotates and causes the planet gears to rotate as idler gears, thus allowing the ring gear to rotate. Because of this setup, the ring gear was made a bit thicker than what Inventor’s gear generator created. The reason for making the ring gear thicker was so that it could be attached to the bottom plate that held the planetary system in place. As opposed to drilling holes and using screws to secure the ring gear to the bottom plate, since ring gear will be either 3-D printed or molded, cavities were made on one side of the gear and extrusion were made on the bottom gear so the ring gear can simply sit in place/snap on.

With the planetary set secured onto the bottom gear plate/cover, a top gear cover/housing would go to the bottom plate but rest on it, so that it could be secured to it as well using screws.

The motor and the set gears, for now, are resting on top of the top gear cover. This will likely change since Armando will create a motor housing for it to be properly secured. The last component I worked before handing the sub-assembly over to Armando over was a force sensor (black component in the picture). It is similar to how a piston works - the black housing contains a small piston inside that pushes against the force sensor inside the black housing. The force sensor has a removable top to allow the force sensor to be properly placed inside and has screw holes to attach to the bottom plate of the sub-assembly. Below are all the parts I created:

This is the top gear cover that houses the planetary gear system and secures to the bottom gear cover.

This is the bottom gear cover that secures the planetary gear system. The “prongs” secure the ring gear in place

The is the rings gear with the cavities so it can “snap on” to the bottom gear cover.

This is the planet gear (x3) with an off-center hole to attach the “gripper” to it.

This is the sun gear.

This is the force sensor housing that secures the force sensor and the piston.

This is the force sensor piston that pushes against the force sensor in the housing. (Note: it may have to be redesigned - may be difficult to put inside the housing - unless it's somehow assembled inside)

This the force sensor housing top cover - this how the force sensor gets secured inside the housing.

This is the pinon gear that connects to the shaft of the motor.

This is the gear that meshes with the pinon gear for our gearbox.

For the top housing, I created a housing composed of four separate pieces. The housing includes a bottom, middle, top, and motor housing piece which are fastened by 2 inch long ¼ inch diameter screws. The top housing piece includes vent holes to provide air flow for the motor. The motor housing plate includes holes to allow the motor to be mounted with M4 screws. The bottom piece has a 7 inch diameter hole to allow the gear housing to stay intact. The two pictures from the right of the sub-assembly above shows how my outer housing parts interface with Kevin's internal housing parts. The right hand picture shows the sub-assembly without the top cover to show how the motor interfaces in the motor housing plate.

This is the motor housing plate which is mounted to the middle housing part.

This is the middle housing piece for the outer housing.

This is the bottom housing part of the outer housing.

This is the top motor housing with vent holes to increase airflow between the motor and the outside temperature from the housing.

This is the final sub-assembly for the top gripper with a BOM (note: the force sensor was not included in the BOM).

Linear Lifting Team Summary

When it came down to deciding on what type of lifting mechanism to use, it came down to choosing either a pulley system or a linear rail / screw system. Our first concept of the pulley systems was to approach it as something similar to what would typically be found in elevator shafts, or the pulley / belt system found in some 3-D printers. However, with Kevin’s advice and prior research, we decided to look more into the CNC rail system. After looking at some of the concepts for these rails, we decided to move on with the CNC rail system and forgo the pulley system.

We pulled up some designs via YouTube and from other engineering blog posts about CNC rail systems, and it pointed in in the direction to utilize a system similar to this:

Using that system set-up as a reference, the following parts and assembly drawings were created:

This is the horizontal connection part that will connect the top gripper sub-assembly to the linear lifting sub-assembly. The U-shaped cut out is for the top gripper sub-assembly to fit onto, and the square-patterned holes on the side are for the 90° brackets for the lead screw and guide rails. This is the part that will be linearly moving in a vertical direction for our project.

This is the lower housing part for the lead screw and the guide rails. The lead screw will be bolted onto the bottom surface of this part, the guide rails will fit into the holes, and the bottom housing sub-assembly will be connected to this part as well. This part may be subject to change, to ensure that everything will connect properly.

This is the linear rail assembly with a BOM.

This is the guide rod assembly with a BOM.

This is the final sub-assembly for the linear lifting system with a BOM.

This is the final alpha prototype assembly drawing with a BOM.

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