For a 4th year project i was part of a team of 5 whereby we needed to design a system that was capable of taking unsorted chocolate flakes then sorting them and somehow inserting them into a conveyor belt that had a rows of 6 ice creams passing by. We each had an invidiual part to complete for the project and i was assigned to the sorting and flake rejection systems although i completed the CAD design for all systems as i was most comfortable out of the group. Basic shapes have been used to represent the individual systems as there was a 2 week time limit for the project so it was not required to be highly detailed. 

Stages 1 through to 6 describe the overall process of turning unsorted unaligned flakes into a stream of 6 columns of flakes that are ready to go into the buffer and don’t contain broken flakes or missing flakes. Initially flakes are unloaded onto a conveyance system and roughly sorted so they are in six columns consisting of not well aligned or complete flakes and brought to a convenient location. The design chosen for the initial sorting of the flakes assumes the conveyor belt with flakes on has been mounted feeding directly into the first conveyor belt in the design. The first conveyor belt has a working area of roughly 700x1100mm and its primary use is to align the incoming flakes and rotate any flakes that might be more perpendicular in relation to the direction of travel. This is done using rollers that are hanging from a bar that is mounted either side of the conveyor belt. The rollers are made from UHMWPE (Ultra-High-Molecular-Weight-Polyethylene) and can rotate using bearings. The ability to rotate means the chocolate flakes should not rub against the roller which could result in a build-up of chocolate. By using UHMWPE, the rollers should be very easy to clean regularly and is safe for food use. Multiple rows of rollers are placed along the conveyor belt in the event the first row does not do an adequate job of roughly aligning the flakes to the direction of travel.  

The flakes are then transported to a second conveyor belt by passing through a set of guides that aligns them perfectly which is stage 3. The guides have different shaped funnels either side of the flake which are designed to prevent jamming in the event of a seriously unaligned flake. The second conveyor belt sits approximately 60mm lower than the first so the flakes can slide down through the guides with the gap between the guides being marginally bigger than the widest flake from a recorded sample to further prevent jamming. These guides would also be made from UHMWPE for its low coefficient of friction and easy to clean properties. Stage 4 and 5 is the process of detecting broken flakes. Once the flakes have been through the alignment process, they are dropped onto a second conveyor belt which is moving quicker than the first. This is done to try and separate broken flakes so there is a gap between each piece making it easier to distinguish if the flake is broken or not.

Stage 5 is the process of measuring the flakes to detect broken ones. The flakes come along the faster conveyor belt and are funnelled into guides which ensures the flakes cannot move out of position. A light gate sensor would be placed either on top of these funnels or on the side and will be able to detect if a flake is passing by. Once the sensor detects a flake passing it will trigger a signal starting a timer, once the flake has passed the sensor will detect there is no object in the way and will stop the timer. With the use of the speed of the conveyor belt it would be an easy calculation to determine the distance the sensor was blocked for therefore determining the length of the flake. If the flake is less than or greater than 1 standard deviation from the mean value of ​​​​​​​a flake, then it will need to be rejected.

During stage 6 the flakes are either allowed to carry on down the buffer or can be rejected using a simple trap door mechanism. The previous stage ends with the flakes being measured and the length being determined ready for rejection if necessary. The trap door works using an actuator which would be mounted to the underside of the buffer or on a separate bar that spans the conveyor belt. This actuator controls the position of a trap door which can pivot at the lower end. Either the trap door would be flush with the buffer frame which would mean the flake would carry on as usual or the actuator would be extended resulting in the trap door pivoting upwards and to the left which would make any flakes coming into the buffer slide down and straight out the bottom. Either end of the actuator would need to be on a pivot as the trap door moves around a central point and not linearly. In the case of a flake needing to be rejected there would likely be a tub underneath the buffer which would catch the rejected flakes and this chocolate could be recycled to minimise waste in the system.

Once the flakes have been sorted they travel down a buffer system which ensures there is a flake ready to go at all times, the flake is then grabbed by one of the 5 grabbers on the moving bar. The bar rotates to line a new flake up with the ice cream below, the whole bar then moves downwards inserting the flake into the ice cream and the flake is released. The reason for multiple grabbers is that it reduces the time needed to move the bar into position as the ice creams move at a rate of 50 moves per minute.