Design of a coin roll check weighing system
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The purpose of this report is to detail the design and analysis of a coin roll check weighing system for the Royal Canadian Mint. The intent of this system is to check the number of coins per wrapped roll, reject if needed, and output onto the tiling machine conveyor. This system is required due to newly contracted coin production that requires coin rolls to check weighed. For our design, we choose to solve this problem, using off-the-shelf components and prototyped models. To begin the check weighing system design, we recommended using the original attachments on the current four wrapping machines. After this attachment, our team prototyped a roll reorientation slide and buffer mechanism. The re-orientation slide rotates the rolls 90° and outputs them onto the buffer attachments. Once the roll is queued on the buffer attachment a buffer drop mechanism is used to output a single when signalled by a photoelectric sensor along the main conveyor. These sensors detect openings along the belt between the four wrappers for coin rolls to be dropped. We recommend using the E3H2 Miniature photoelectric sensors from Omron to complete this task. After the roll is dropped, it will begin moving towards the check weighing station. To complete this motion, two narrow flat belt conveyors from Mini Mover Conveyors were selected. These conveyors consist of a horizontal main conveyor under the buffer mechanism and an inclined conveyor to carry the roll up to the check weighing station. To ensure the rolls maintain the correct orientation during transport, adjustable side rail guides from Mini Mover Conveyors were selected. In order to optimize the use of the conveyors with different sized rolls, each conveyor section was fitted with a variable speed drive motor, also from Mini Mover Conveyors. In order check weigh each coin roll after wrapping, an Ishida DASC-G-S015-12-SS check weigher was selected. This check weigher is able to process up to 400 items per minute with accuracy of 0.1 grams. These specifications, along with others, are more than adequate for the Mint requirements. Not only does this system include check weighing but also user defined software and a rejection system. Since these components are all integrated into a single station, the check weighing machine is capable of recording weighing data and outputting in RS232 format. The rejection system is also capable of not only rejecting faulty rolls, but also alerting the operator and stopping the process after 10 consecutive rolls have been rejected. Following the check weighing the station, the coin rolls travel onto a final alignment conveyor, where similar used on the main and inclined conveyor, that re-aligns the coin rolls for the roll transfer attachment. This conveyor, guides, and motor were obtained from Mini Mover Conveyors as well. Finally, after the rolls have been re-aligned, they are dropped onto the tiling conveyor using a prototype roll transfer attachment. This attachment is designed to be adjusted for different roll diameters and lengths to ensure the correct roll orientation onto the tiling conveyor. Lastly, a cost analysis was performed for procuring the commercially available components and manufacturing the prototype components. The total cost of the system came out to be $62.441.86. It should be noted that this cost does not included prototype development and setup costs. This constraint, along with the floor space size, output height, and power methods were all met with our system. The total floor space size for our designed check weighing system was 5.46 feet long by 2.2 feet wide and the output height to the tiling conveyor is 34.75 inches from the roll transfer attachment.