Debaler Instrumentation and Data collection

The goal of the project is to build upon and add to the previous debaler prototype from 2019-2020 school year. We will achieve this by making the debaling process automated by adding an inlet conveyor system capable of carrying 2 bales towards the debaling head, while also integrating a working control system to control the material outflow and will also be able to detect bale jamming/motor stall and correct with no human interaction. By the end our project the debaler should be able to have a bale successfully debaled at a consistent flow for a specified flowrate without any human input other than the loading of the bale.

=Problem Definition= The current debaler prototype is not an automated process, and the main goal from the client is to make the current prototype an automated machine. This requires adding an infeed conveyor to the current processing head, a working control algorithm to detect bale jams, and chute clogs also need to be added to this system. Additional improvements to the prototype such as cleaning off the processing head and making sure all loose (debaled) material goes through the chute are also desired by the client. Testing and data analysis of the system running different types of materials is also required.

Background
As the need for precision agriculturally based feedstocks for biofuels and bio-based products increases, there is a need to debale straw, corn stover, hemp stalks, and other baled herbaceous crops for feeding into industrial processing equipment. The fundamental question is how can we effectively and efficiently turn baled material back into the loose material it was baled from and feed it onto a conveyor for subsequent milling and processing? Existing debalers were developed to support dairies and feedlots where the objective is only to distribute the material in small enough “chunks'' for cows and other animals to eat. Existing methods either do not break apart the flakes well or create a large amount of fines in the process. Forest Concepts needs a debaling mechanism to break down large square bales of stover, switchgrass, and similar materials into uniform streams that can be conveyed into our Crumbler® rotary shear comminution systems.

Deliverables
Our goal is to use available materials and scrap parts to improve the mechanical design, saving our financial resources to develop a control system to sense and correct bale jamming or chute clogs, and monitor the outflow of material. From the testing of various agricultural material we will document recommended operating parameters based on material type.

Specifications
1.	Mechanical device to pull apart and fluff baled agricultural materials 2.	Control algorithm to sense and correct bale jamming 3.	Consistent outfeed of material 4.	Easily transportable by standard highway equipment 5.	Prototype to withstand up to 140 lb bales 6.	Conveyor infeed system able to automatically transport bale to processing head

=Design Considerations= This project was a design continuation from the previous year’s capstone design. At the beginning of the project, it was decided to continue the previous team’s work instead of trying to start from scratch. Therefore, some of the main design elements, such as the processing head, were not reconsidered.

Infeed Conveyor

After an old hay elevator was sourced to be used as the infeed conveyor, the angle at which it would feed into the processing head would have to be chosen. Three angles were discussed, the first being horizontal to the ground, angled from the ground up to the processing head, and finally angled down into the processing head.

Horizontal Angle

Pros:

-Will not have to contend with gravity

-Will not have to redesign processing head stand -Conveyor stand will be simple to build

-Easy to adjust distance between conveyor and processing head after installed

-How existing prototype was built to operate

Cons:

-Will have to lift bale to conveyor

Ground to Processing Head

Pros:

-Easy to load bale

-Will not have to redesign processing head stand

Cons:

-Hard to keep bale together while going up conveyor -Conveyor stand will be more difficult to build

-Hard to adjust distance between conveyor and processing head after installed

-Bale could fall back down conveyor

Down into Processing Head

Pros:

-Gravity assisted

-Easy to adjust distance between conveyor and processing head after installed

Cons:

-Will have to rebuild processing head stand -Difficult to load

-Conveyor stand will be very large and difficult to build

Head Cleaning

During the testing of the previous prototype, it was noted that the hay seemed to wrap around the tines on the processing head instead of falling off after being torn from the bale. This in turn would make a mess flipping hay to places it was not intended to go. To solve this problem two possible solutions were discussed: attaching brushes to the processing head that the fingers would pass through and enclosing the entire processing head.

Brushes

Pros:

-Low cost

-Easily sourced

Cons:

-Initial testing did not yield satisfactorily results -Difficult to properly install

Sheet Metal Enclosure

Pros:

-Would contain any mess made

-Provides protection against spinning processing head

Cons:

-More expensive -Time intensive to create

Bale Jam Sensing

To complete the desired automation effect of limited touch operation, a bale jam sensing system will need to be implemented to ensure the proper function of the machine. To track the bale jamming, two methods were considered, Hall Effect sensors, and current overload on the previously installed VFD.

Hall Effect Sensor

Pros:

-Simple to code

-Low cost

Cons:

-Added failure points

-Added cost

-Only gives one data point

VFD

Pros:

-Already have equipment

-Reliable

-Provides more data

Cons:

-Complicated to program

=Final Design=

The Final design of our project was a machine that consisted of three main parts the Header, Infeed Conveyor, and Control system. We developed our final design from early testing and conceptual designs.

The header was part of the previous team’s prototype, and performs the main function of the debaler. The header has many finger-like tines that stick out from cross bars on a chain. These fingers spin around and pull through a bale to remove material and feed it into the outfeed chute. The previous teams prototype worked but we made a few improvements. For example, the original prototype could not contain debaled material cleanly. As the machine ran material would wrap around the tines and allow material to fall out the back and not into the outfeed chute. This can be seen in the figure below.

The new design of the Header includes a shroud that encases the Header and allows material to be funneled directly into the outfeed chute. The shroud also acts as a safety feature as well only having one face open and exposed to the turning Header tines. For ease of building and to make sure material did not jam in the shroud we chose to cover the whole Header including the turnbuckle that allows for angle adjustment. And since we want to be able to change the angle of the Header there is an access panel on the back of the shroud that allows for easy access.

During our initial testing we discovered that the original motor had little torque that allowed it to stall easy. So during testing when we thought a bale jam was occurring that was not always the case instead it was the motor stalling unable to keep spinning the header. So our last major change to the Header was adding a 1750 rpm 1.5hp motor with a 6 to 1 gear range to allow for plenty of torque.

Our main addition to the previous team’s prototype was the infeed conveyor. Since the previous design you had to manually push bales into the Header, we wanted to create a way to automate that. So, we came up with a way to use a conveyor system to transport bales to the Header. The solution we came up with was cheap and easy to implement. We were able to obtain an old hay elevator and cut it down to the size we needed. This allowed us to put together a system that functions on our relatively low budget. If we would have designed and built a conveyor by ourselves it would have been much more expensive and probably would have taken nearly the whole 2 semesters.

Since we replaced the old Header motor, we were able to reuse that motor to control the Conveyor. This was a great solution because this motor already had a VFD so the speed could be varied, and the direction could be reversed.

The final part of our system is our Control system. We first discussing the project with our client we were hoping to have a fully automated system, meaning one button push and everything runs. Sadly our final design did not consist of that. With none of the team members having experience with controls system we were unable to figure out how to get our system to work fully automated. But our design consists of 2 motors, 2 VFD’s, a double pole double throw switch, and 2 Emergency stops. Each VFD controls 1 motor, and the switch is used to control the Header. So, the switch is used to control forward, stop, and reverse of the Header. And in case of Emergency both E-stops need to be pressed to fully shutdown the machine.

=Validation=

Below is our criteria for Design Validation. We passed all the requirements for our design other than one. The one requirement we did not meet was that of creating a control algorithm that would allow the Debaler to be operated with no human interaction other than an initial start button. We were unable to meet this requirement do to the fact that no of the team members had any experience with controls system. To get this system to work properly a good understanding of logic control was needed to know how to communicate between a PLC and the Header VFD. The other requirement we only partially met was that of testing multiple materials. We only tested grass hay bales because those were the only bales we could obtain. Although we did not test other material we still believe that the Debaler would have no problem debaling this different materials.

=Results=

Our new debaler prototype proved that it could debale a single grass bale with minimal or no fines, with consistent outflow, and minimal or no bale jams. Our first initial test with the small gap and angled back we found to be our worst configuration. Because the gap between the teeth and infeed conveyor was so small and the backwards angle put the bottom of the Header underneath the Infeed conveyor, we found that Jams were a guarantee. We also found that the header could not keep up with conveyor so we would have to stop the conveyor and let the header clear itself before you could run the conveyor again.

On the test when we changed our angle from -17° to 0° we discovered that if you do not loosen the motor from the chain you have the chance to bend the shaft. Because the motor is now mounted independently of Header if you change the angle you will start to put extra tension onto the chain of the motor much more than is necessary. So, we learned if you are going to change the angle loosen the motor and remove chain then change the angle and remount the motor.

After we got a replacement motor, we were able to test again. These next tests are when we got our best results. Before we changed our gap from 1” to 4” we were able to debale most of a bale but if a big bale flake got pulled into the header the gap was to small and would create a jam. Therefore, we increased our gap to 4” this allowed the debaler to be able to consistently debale material with minimal jams compared to the 1” gap. Although we fixed the jamming the material that was no coming out was not perfectly fluffed. When large bale flakes would be sucked into the Header the gap was now large enough that the material would almost just fall through without getting fluffed the full amount. Now although these larger flakes were not as fluffed as some of the other material as soon as these pieces were grabbed, they very easily fell apart and were no longer compact.

So, there are a few ways to fix this that we did not have time to test, but if the gap was lessened to say 2” we believe jams will still be minimal but the larger flakes have a greater chance to be torn apart. We also needed a better way to hold the bales together. We had two bent rods trying to hold the front of the bale, but these did not work great and would allow those big flakes to fall into the header. With these modifications we believe the debaler would be running at optimum efficiency.

=Recommendations=

Mount Header motor to Header

- The first prototype model had the motor mounted directly to the Header so that when you changed the angle the chain tension would remain constant. On our design we mounted the motor independently of the Header. This meant that everytime you want to change the angle you must first loosen the motor. We recommend that the next team create a new motor mount that is mounted to the header, so that you don’t accidentally over tension the chain and bend the motor shaft.

Change Header motor drive system

- Along with mounting the motor to the Header, we would also like to recommend some type of clutch system on the Header drive. This would protect the motor from over torquing itself when an overload happens. We believe the easiest way to implement this would be to change from a chain drive to a belt drive that would allow slippage in the case of over torqueing.

Add Brushes to top bar

- One of the greatest challenges yet to be solved on the debaler is not allowing full bale flakes to fall into the Header. We did some research into this and recommend to ways to help prevent this. Currently we are using to semi stiff rods angle to let the bale push into them while also trying to hold the bale upright. The problem is they don’t provide enough pressure to hold the bale up until it makes contact with the header. So the solution we recommend is to add stiff 2-5” brushes that span across the cross bar currently on the Header. This should hold the bale, but the brushes can get pushed into the Header and shouldn’t cause any interference.

Add side Funnel plates

- Along with the Brushes we also recommend adding two side plates one on either side of the Infeed conveyor that are angle so that the gap into the header is reduced. This will cause some restriction that the infeed conveyor will have to overcome but should provide enough pressure to hold to bale together, and not let flakes fall forward.

Increase Finger length on processing Head

- During some of the first rounds of testing we saw the Header struggle sometimes to grab material from the bale. So we recommend doing some testing with different lengths of fingers to see if that would improve performance.

Set plate gap to 2"

- Another issue that seems to be the root cause of jams is the gap between the Infeed conveyor table and the header. During testing we ran at 1” and 4”. 1” was too small and cause jams frequently, 4” didn’t cause jams but material was fluffed as well. We have thought of two ways to address this. One keep changing the gap until optimal distance is found we believe somewhere between 2-3”. Or second you remove the plate on the infeed conveyor and add some type of fingers like cultivator fingers. You would still want these fingers to span across the conveyor and be able to support the bale. But if you had these finger as close to the header as possible the fluffed material would be pulled through fluffing as it was pulled through. And if a flake happens to get pulled in the fingers can deflect and be less likely to cause a jam but would also keep the flake from staying together.

Replace Conveyor motor

- The motor that was broke during testing is getting replaced through its warranty. We recommend the next team use that motor to control the conveyor. Every once in a while during testing the conveyor would stall and would have to be shut off and then back on again. The replacement motor has double the horsepower and torque and would work great for the conveyor.

=Team Members=

=Additional Documentation=

Project Schedule



Meeting Minutes

Presentations



Client Interview