How to Design Compressed Can Machine by SolidWorks

I did this design project during my small internship at TickLab, a Mechanical Engineering Lab.

The machine I design must be able to compress 60 cans/minute. Assume that somehow I can supply 1 can for every second, so the frequency of this mechanism in 1 Hz (60 rotation/minute => 1 rotation/sec). We have Frequency = omega (angular velocity) / 2 pi (equals to 1 circle). So omega (angular velocity) = 2 pi = 6.283 rad/sec.

Because this is just a design project, so mostly you will work with software to do calculations and simulations:

• SolidWorks (Used for 3D design)
• AUTOCAD (After analyze and choose the correct data, simulates the motion by 2D drawings)
• Excel (Used to analyze the data and present data effectively)
• MechAnalyzer (Used to obtain velocity vector, acceleration vector and motion trajectory data)

My whole design was inspired by this video on Tiktok

• Link: https://www.youtube.com/watch?v=_8HD0mr_D68&feature=share

After carefully watching and analysing the motion of the machine in this video, I conclude this thing works on the slider-crank mechanism.

There are something we needed to know before calculations:

We all know to compress the can, we need certain amount of forces. According to Newton's 2nd law: F = m*a. From that formula, we know there are 2 big problems we need to solve:

• The acceleration problem (a)
• The mass problem (m)

In acceleration problem, we need to know these things:

• Does the length or ratio in this mechanism affects the acceleration?
• If yes, which length or ratio produces the largest acceleration?

In the mass problem, we need to know only 1 things:

• What is the mass needed to produce enough forces to compress the can?

Because Mass and acceleration are interdependence. Since it is easier to change the design dimension than to increase the mass in manufacturing, I decided to solve for the acceleration problem first.

This is how this mechanism works:

• The mechanism consists of a crank, transmission rod and a slider. As the crank rotates around, it pulls the transmission rods, also pulling the slider go up and down. When the slider goes down, it is when the can starts to be compressed.

Let's pick a specific time interval in the mechanism and naming the parts as follows:

• Crank was named AB
• Transmission rod was named BC
• The motion trajectory the slider travels was AC.

When you open the MechAnalyzer softwares, first you need to choose the correct mechanism. You can choose Slider-crank mechanism in the navigation area (bottom left corner). There are 3 panels you need to know:

• Position panel is there to help you see the motion of mechanism over time
• Velocity panel is to illustrate the magnitude of the velocity. The longer the bar, the larger the speed.
• Acceleration is to illustrate the magnitude of the acceleration. The longer the bar, the larger the acceleration.

As I stated above, we solve for acceleration problems first, and the first step is to find the suitable ratio. Let's just fixed some ratio in order to solve for suitable ratio

• Pretend length of AB = 5mm
• Angular velocity = 6.283 rad/sec
• Angle BAC = 60 degree

We will solve for a range of ratio BC/AB from 1.5 to 2.1

Plug everything into the software Mechanalyzer above and then click draw to get the results like above. Because velocity and acceleration are positive correlates, we just need to focus which ratio produces the largest velocity at this particular position.

Then you just need to change the length of BC according to the ratio.

After doing a lot of simulations on the MechAnalyzer software, we obtain the following table. As you can see, the larger the ratio, the smaller the velocity, and thus the smaller the acceleration.

• So we will choose the ratio 1.5 to produce the largest velocity and acceleration.

According to US patent, the forces needed to compress the can is around 5 to 20 pounds, which is 22 Newtons to 88 Newtons. Thus, we just need to produce the force in this range. For purpose of manufacturing, we should produces the slider with mass larger than 5kg.

From Newton's 2nd Law: F = m*a

• Mass = 5kg (max mass)
• F = 22 Newtons
• So accelerations = 4.4 m/s^2

Now, using the MechAnalyzer software again, with the ratio 1.5, now we just need to change the length of AB and BC in order to produces the acceleration larger than 4.4 m/s^2

As you can see, the acceleration here is presented in mm/s^2, so to convert to m/s^2 you just need to divide by 1000. Here, the ratio is fixed, angular velocity is fixed, only the angle BAC changed to 45 degree. If you looks carefully at the tiktok video in step 1, you see the time the slider starts to compress the can was around 45 degree, so we choose acceleration at that time.

• From the data, we have a wide range of accelerations to choose since they all larger than 4.4 m/s^2
• However, to make the manufacturing easy to cheap, we should choose the lowest acceleration, which AB and BC lengths equal to 125mm and 187.5 mm respectively

From the data I collected, I design the crank and transmission rod as below. The next step is to design the slider. To design the slider, you need to consider 1 thing:

• Slider is supposed to slider on some surface. And that slide has friction forces. So you need to choose materials for slider and that surface that has the lowest Friction Coefficient.

Using the internet, I was able to figure out that wood has the lowest Friction Coefficients. So I design both the slider and surfaces with wood materials.

Because the type of motion you choose here involves rotary motion. That's why the most suitable engine or motor is the DC motor. In order for the motor to be able to moves the system, it must produces enough torque. The formula to calculate the torque needed is provided above.

Motor is actually a standard parts, so you have to look up on the internet, my criteria to select a motor is:

• Guarantee number of rotation (N) > 60 rotations/minute. This must attained while bearing the loads
• Voltage around 12V (12V is the voltage of a small battery). I don't want to use big battery just to power this simple machines

With that in mind, I look up on Arduino shop and found JGB37-550 DC6V 12V motor. I also check the Engineering parameters of the motor:

• With the torque produces while bearing loads is around 10kg.cm, it actually powerful enough to moves the slider effectively (mass of slider around 5kg).
• Also the rpm while bearing load is 107 rpm, so it is way higher than 60 rotations/minute (which is really good)
• Also the current needed to supply just 1.5A, just equal to small size battery.

With the dimensions on the internet, I briefly design the motor in SolidWorks

This can container I was inspired by the Cyclone Dust machine because of 2 reasons:

• First, because its structure is so similar to the Cyclone Dust machine so it is easy to manufacturing. One thing you need to consider in design is always design your thing similar to the one already have in the market because it is much cheaper to produces and it is easier to produce.
• Second, as you can see inside the Cyclone, it is like the funnel, so all the can will automatically going down without get stuck to each other.

As you can see the Cyclone I design have a hole in the bottom, so when the slider compressed the can, it upper surfaces actually cover the hole of the cyclone so no cans can fall down. When it pulls up, the hole of the cyclone is opened, so the can will be able to fall down. It kinds of like an improvement to let the can falls down automatically.

And after a lot of hardworks, finally you just finish design the Compressed Can Machine. Theoretically, if you decide to build it, you will definitely change the design a lot more, because there always a big gap between design and reality. However, you could visit my other instructables "How to design 3D foldable shelves" to learn more about 3D printing.

Thanks so much for spending time reading this, I really appreciate your enthusiasm.