Packaging companies are in need of a process to remove plastic nylon from paperboard tube cores. The plastic can be recycled as per government requirements. The current practice of removing plastic utilizes box cutters and floor personnel resulting in an unsafe and time consuming process. There are costly mechanics on the market that are capable of removing the plastic but are too expensive for many companies. By solving this problem, package companies will be able to free up production time, lower safety concerns and allow manpower to be utilized elsewhere.
A proposed device will need to handle a variety of conditions, as rolls can span from 8 to 36 inches wide, weigh up to 300 pounds, and have a 30-inch diameter. When all goals are met the system will be evaluated and refined.
The goals accomplished by this project are: to provide a solution for worker safety, remove plastic more efficiently, lower cost, ass to the current markets solution and thereby broaden the economy.
Proof of Concept
The purpose of this POC is to test the hand calculations that define cutting force required for shear and compare them to real world data. This POC checks to verify that those expected forces are correct in a real world test, as well as ensure that all other forces were accounted for in cutting. The Proof of Concept test will allow the team to know the true cutting for of specific samples that can be scaled larger to aid in future design decisions. A basic explanation of the POC test is a simple designed cutting assembly, designed by the team, will be used to cut specific measured nylon samples on a force testing machine that will allow recording of force data. The smaller details of the test are discussed and organized below.
The Proof of Concept activity begins with securing the blade assembly to the hydraulic testing press, by the top nut with a threaded pin and placing one of the five specifically cut nylon samples. There are two types of nylon testing samples. Swatches are flat layers of nylon cut into 4 separate widths, all swatches have the same length and number of layers. By testing the swatches, the team will better understand needed force as the cross sectional area increases. A nylon 3-inch length roll, in the shape of a cylinder is the other test sample. By testing the nylon roll the team will gather real data on how the cylinder roll will compress during a cut. The machine will apply force to the blade assembly to cut through either a swatch or roll. The test is ran with both a hand sharpened edge blade and with a floor scraper blade which has harder steel and is the sharpest of the two blades. Both blades are Chisel edge blades at a 26-degree angle. The different blades will clarify how sharp the blade needs to be so the best blade for the future prototype can be easily chosen.
|Steps for testing and Gathering Data for the Shear of Nylon.|
|1.||Attach blade assembly to hydraulic testing machine, check for fit and if base and blade edge are parallel.|
|2.||Raise the testing tool and place one nylon test sample under the blade location.|
|3.||Apply estimated force to the nylon test sample. Record the effectiveness of the cut that occurs. (i.e.: number of layers cut, pressure required to cut, etc)|
|4.||If cut does not occur, raise the testing tool, move the same sample to a location along the length that has not been cut or deformed. Apply double the estimated force to the nylon test sample. Record effectiveness of the cut that occurs.|
|5.||Repeat steps 2-4 for all test samples.|
|6.||Switch out the blade type and repeat steps 1-5|
The Proof of Concept design from task 5 has been made as planned. The construction of the assemblies was simple and came together easily because of the detailed designs made by the team.
On December 1st, a mock test was performed to test fit and set up of the assembly. The team wanted to run a preliminary test to insure that when the final test was performed it would be effective and no surprise issue would hurt the quality of the POC test. The mock test found the fit of the tool was perfect. The blade was easily fixed parallel to the base. To further test blade assembly, the dull unsharpened blade was fixed in place, a 2-inch nylon swatch was placed under the blade and 1500 [lbs.] of force was applied. There was no shearing of the nylon sample at all, because the dull side of the blade was used it was expected that there would be no shear. The sample did deform in the cut location and the nylon had visible signs stress in the form of discoloration after the mock test was performed. Now it has been proven, but was suspected, that if the blade is dull shear will not take place. The window of uncertainty is now lower and future tests will clarify even more information.
The dimensions required by the roll have been changed from 24’’x24’’ to 20’’x24’’ (Length, Diameter). This was discussed with WorldPak LLC in order to make the product more affordable by overcoming a discontinuous price jump at 22’’. The price jump requires a large purchase of C-channels. WorldPak found this acceptable as most of their rolls are far below that requirement. The current product set up to handle 22.5’’ rolls.
The product’s weight will be approximately 200-250 lbf. With multiple people and a blade guard it can be transported.
The weight of rolls ranges from 3 lbf. – 300 lbf. and workers often have trouble moving them. Due to this, a trough has been added with easy loading features to insure the roll is secured.
Force specifications for cutting the roll were determined by Core Cutters Co. and are outlined in the PoC Analysis. The force required to cut the roll is estimated to be 4 tons. The hydraulic setup is currently able to put out 7-10 tons of force. This will change based on the control unit and motor selected.
The roll splitter must include highly visible warning labels on the frame and on the blade assembly caution lines will be draw according to OSHA 29 CFR 1910.145. This will remind the user of the proper safety precautions that must be adhered to when using this device.
Moving the product will require multiple workers and the removal and sheathing of the blade. Training in both the use and transportation of the device are necessary to utilize the machine safely. Maintenance of the blade, while infrequent, may be necessary to maintain optimal cutting. Additionally, inspection of the machine should be performed before each session to identify outside hazards or product damage.
The hydraulic pump will be driven by an integrated electrical system that provides the user precise control over the movement of the blade. The system will also have several safety features such as an emergency stop button and stop switch to help prevent harm to users or the machine.
WorldPak gave Team 15 a maximum budget of $5,000 with an expected minimum cost of $2,000. So far, Team 15 has projected a total cost of less than $1,500. This is subject to change slightly as many of the specified items in Table 1 have not been finalized.
Table 1: The table shows the breakdown of cost for the parts that are currently required for the construction of the roll splitter. Note that the most expensive components exist within the hydraulic system.
|Hydraulic power unit||$407.25||1|
|Blade assembly nuts||$3.00||5|
|Blade assembly bolts||$5.00||5|
|(Alt.) Hydraulic power unit||$645.15||1|
Figure 1: The WorldPak logo and company name will be present on the machine. The company logo must be clearly seen on the product to show ownership.
Important Design Details
The product Team 15 is building has a few interesting characteristics. The first of these is the build cost of the product will be reduced significantly through the donation of a blade and C-channels. This helps the team as now the team will not need to purchase a blade or the C-channels required to modify the blade. Another characteristic of the product is the team will be purchasing a hydraulic press and then modifying the frame in order to acquire the dimensions the team needs. Team 15’s machine will also be unique as it is made from four different subassemblies which will be integrated into the frame the team has modified. Each of these subassemblies are very different systems and require a different analysis for each modified part. The team is also integrating a movable base into the machine, which allows the user to change the position of the base to allow smaller rolls to be cut at a quicker time, meaning more rolls can be cut in a shorter time.
The project’s sponsor WorldPak LLC receives a small percentage of irregular plastic packaging rolls that are unusable and need to be recycled. They are requesting a machine that can split irregular plastic rolls faster than a human worker. The purpose of the machine is two-fold: to ease the process of separating plastic film from paperboard cores, and to reduce the time needed to complete the separation process. Although the Core Cutters Company’s machine design is tailored specifically for WorldPak LLC, the machine could be useful for a consumer in need of a compact, affordable hydraulic cutter that can produce up to 10,000 lbs of shear force. The product must perform the cutting specifications in a consistent manner and not have regular periodic flaws.
Figure. 2: This figure shows a detailed 3D SolidWorks model of the full frame structure unit for Core Cutters Co. This is a true scale model of the full design. All dimensions have been chosen for specific design needs and specifications. The modified parts consist of a holding base, a cutting mount, extensions to allow space for the cylinder as well as mounts to hold the cylinder. The hydraulic system will be added to the frame structure unit in the next design phase.
- Obtain “20 ton H-Frame Industrial Heavy Duty Floor Shop Press” from Harbor Freight
- Remove material from D-tab and blade mount guide surface locations to ensure smooth mounting of D-tabs.
- Cut and add holes to added C channel.
- cut plates and holes so c-channel can be attached to H-Frame
- Re-assemble with extension using ⅝ size, 7 inch long bolt and nut set with splice plates.
- Figure 1 displays modified c channel with added holes to extent the frame height. Figure 8 shows the setup needed to extend the frame including bolts and splice plates.
Base Assembly Construction
- Two 6 inch wide x ½ inch thick plates for top of base
- One 4 inch wide x ½ inch thick plate for bottom to create a channel between the two top plates
- Each plate was cut to a length of 22 inches using a wet saw at WorldPak.
- ¾ inch holes were cut using a CNC Mill at the Manufacturing Lab at UNR
- Bolts, nuts and washers were purchased at Home Depot
- Figure 2 displays the lower connecting plate of the base, with bolt holes and dimensions. This component of the base locks the two upper plates together and slides into the H-Frame.
- Figure 3 displays one of the two upper base plates that rest on the H-Frame.
- Figure 4 shows the full base assembly with bolt holes and optional all-thread bar holes to further contain rolls. This completed component is shown in the bottom of Figure 8.
- Blade Mount Construction
- Cut two, A36 ¼ inch steel plate metal to size with wet saw (see 5)
- Tape up the sharp edge of blade for safety with any weak adhesive tape
- Use water-jet cutter to shorten blade
- Use waterjet to cut 4 holes in sheet metal and blade (see 5 and 6)
- Welding plate metal and H-Frame
- Center the blade onto the middle of the H-Frame Slider
- Place one of each of the two plate metal pieces onto each side of the blade
- Clamp the two plates/ single blade to the plate metal strip forming a T joint add tack welds to insure joint is in place then tack weld full T joint to modified H frame blade mount slider (see Fig .7 )
- Apply a Gas metal arc bead (MIG) to both sides of the T joint then apply 2.75 inch intermittent stitch welds on both sides of the plate metal strip attaching the full T joint to the H frame blade mount slider.
- Note: Ensure blade is removable
- Apply a full weld to the upper and lower D-Tab that mount the hydraulic cylinder. The tabs must be positioned center between the vertical C Channel slide rail and parallel to the full blade mount slider (See 7)
- Bolt blade (including washer) into to sheet metal with ½ inch bolts
- Put H-Frame Slider into frame (see 7 and 8).
- Figure 5 shows the sheet metal cut to size with holes. Two of these will contain the blade in the mount. They will be welded onto, the plate metal strip and then to the H-Frame slider as shown
- Figure 6 shows the blade cut with holes and to the correct length.
- Figure 7 shows D-Tab on top of H-Slider, with the plates welded to the H-Slider and the blade wedged in between the plates. This component is shown in the middle of Figure 8.
- Figure 8 shows an image of the Frame Assembly, Blade Assembly, and hydraulic cylinder constructed to form the Roll Splitter (excluding the Base Mount Assembly).
C-Channel Fixture Bracket
- Cut C Channel down to 5.5 inch sections.
- An auto mill program was formed to mill away unwanted material
- Three separate code were made to mill away material on the web and the legs.
- Code for web side 1 inch slider hole.
- Code for leg side ½ inch holes for bolts
- Three separate code were made to mill away material on the web and the legs.
- Code for one leg to remove material for fit
- The C Channel section must be repositioned correctly after each mill code is run
Figure 9– Custom fixture bracket acts as a washer, for better fit as well as limits the rotation of the clevis pin set for the hydraulic cylinder. A ½ inch bolt and nut is feed through the leg side of the C channel to help limit rotation of the pin through the D tabs.
Hydraulic System Assembly
- Weld D-tabs to frame, as shown at the top of Figure 7
- Mount hydraulic cylinder to D-tabs with clevis pins, washers, and stability braces.
- Connect the Hydraulic Power Unit (HPU) to hydraulic cylinder via hydraulic hoses
- Wire HPU to:
- On/off switch
- Emergency stop switch
- Bypass circuit
- Limiting switch
- Attach HPU to the table
- Attach limiting switch to base so that the H-Slider will collide with it in a manner that the blade does not touch the metal base
Figure 10 shows an image of the HPU (upper left) and control system. The HPU is connected to the power system and the limiting switch (bottom left) underneath the sheet metal plate.
Testing and Results
The first phase of tests performed by the team focused on determining whether shear would occur in a standard 20 inch sample nylon roll. After the first phase of successful tests, smaller, more irregular rolls were tested. To test strength capabilities, 1-inch thick paperboard rolls were cut to gauge shear limits. It was found to be able to cut paperboard without signs of fatigue. The test plan involved a pass-fail criteria, and if any test would have failed, the team would have investigated the cause and redesign or readjust the machine to fix the issue. However, none of the tests failed, and the machine was successfully tested close to 25 times. Each test resulted in a clean, through cut to the core of the roll which allowed for effortless separation of the paper board. An example of a successful test is shown in Figure 1 and in the video files attached to this assignment.
Figure 1 shows an example of a successful clean cut on an irregular roll.
The product was designed to cut nylon rolls longitudinally which measure up to 20 inches long and 24 inches in diameter. The testing proved that the product can easily perform as designed, and it will likely have a longer longevity than what was originally predicted.
The Roll Splitter did not fail at any point during testing. The main reason for this is that a large focus was given to foresight. The team noticed a potentially fatal flaw of the original design, and the team took appropriate measures to correct the issue before testing began. The flaw in review posed a threat of catastrophic mechanical failure of the blade assembly and/or hydraulic piston since an improper positioning of a nylon roll could create a moment on the blade assembly and misalign it during cutting.
A specially-machined fixture was then designed to secure the pin location between the frame, hydraulic cylinder, and blade mount in order to prevent inadvertent movement of the blade assembly. This fixture ensured the required measure of stability for the design. The unit was never tested without this part because it was clear after assembly that it was necessary in the design’s success. The fixture bracket was the final detail needed to insure a successful unit capable of shearing nylon roll on the first attempt. A drawing of this fixture is shown in Figure 2.
The Roll Splitter provides a safe, efficient solution for the problems presented by separating nylon from paperboard cores by hand. Previously, workers in the packaging industry would use box-cutter knives to cut through the rolls, and this process was inefficient and fatiguing. The workers’ fatigue and their desire to cut rolls more quickly caused the workers to injure themselves often. The Roll Splitter’s implementation allows users to separate the plastic from the cores without endangering themselves, and it increases worker productivity due to its ease of use and workers’ reduced fatigue.
Market Testing and Results
The product was well-received by WorldPak, the sponsor and intended user of the Roll Splitter. Team 15 surpassed WorldPak’s expectations in the effectiveness of the Roll Splitter, and WorldPak intends on implementing it in the near future. Team 15 met all requirements set by WorldPak, and one of the sponsor employees found the use of the Roll Splitter quite enjoyable and satisfying.
This design fulfills all needs set by Core Cutters Company’s design team and sponsor, WorldPak. The unit is far safer and much more efficient than using box cutters to process the roll. Safety was a top priority during the design of the the unit. The end result is a purpose focused device that is safely and easily controlled to completely cut the roll for the worker. All the worker must do is separate the two materials after the cut has occurred greatly reducing the time and work needed to complete the task.
Meet the Team
Tyler is a senior Mechanical Engineering student at the University of Nevada, Reno. Originally from Henderson, Nevada, he will be graduating in May 2017 with a minor in Mathematics. Tyler will be aiming to move into industry with goal to work with computational fluids. He plans on pursuing a masters to achieve this goal.
Skylar Van Rensselaer
Skylar is a senior mechanical engineering student from Carson City, Nevada. In spring 2017, he will graduate from the University of Nevada, Reno a bachelor’s degree in mechanical engineering. As an aerospace propulsion technician in the Nevada Air National Guard, Skylar has utilized his engineering knowledge and skills to contribute to the maintenance of military aircraft and advance his progress toward an associate’s degree in aviation maintenance technology from the Community College of the Air Force. After graduation, Skylar will pursue a military career in aviation and continue to develop his design skills pertaining to aerospace, defense, and autonomy.
Ricardo is a senior in mechanical engineering at the University of Nevada, Reno. By next year he will be the first member in his family to receive a bachelor’s degree. He currently works as an engineering student intern at Hoover Dam, so after graduation he would like to work in power generation.
Brad is a senior at the University of Nevada, Reno. He is actively pursuing a bachelor’s degree in Mechanical Engineering. Brad has spent his academic experience balancing his accumulative knowledge of math and science with hands on experience in the field of welding. He was born and raised Las Vegas, Nevada and in 2009 moved to Reno to begin his college career. After Graduation Brad will be looking to apply his background and knowledge in the field of manufacturing/design.
Patrick is a senior in Mechanical Engineering at the University of Nevada, Reno. He has completed his courses with of current GPA of 3.70. Patrick McPherson is from Yreka in Northern California and plans to move into the field of robotics or control engineering. After a few years in the industry, he plans to return to get a Master’s degree in Engineering.