Framtagning av model, för små frö till precisionssåmaskin

Sammanfattning: This thesis project was to develop a module for a forest precision seeder. The projectis made at BCC AB. BCC is a worldwide supplier of forest seed centre andcontainerized nursery equipment. BCC develops, designs, produces and salesmachines for forest seed handling.BCC s existing precision seeder can not handle seed that are tinier than 1 mm indiameter. With a growing market in countries with much eucalyptus forest is there aneed for a seeder that can handle those seeds. Eucalyptus seed is very small, between0,5 – 2 mm. The problem is that the machine should saw only 1 seed in each cell in theplastic pot. If it saws 0, 2 or more seeds in every cell someone has to take care of themistake later when the plant has grown bigger. This type of mistakes costs a lot ofmoney for the nurseries. Therefore the machine has to be very accurate. The accuracyfor BCC s existing machine is with optimal circumstances 99 %.The thesis is made as a development project. The first step was to establish a problemformulation and do some research of both BCC and their competitors machines.Next step was to find different principal solutions to the main problem, separate just 1seed from the other. After evaluation of all the principal solutions was it clear that theneedle principle was the best. 36 needles or actually nozzles suck just one seed a thetime. The holes in the nozzles are much tinier then the seed, in the present case just0,26mm.Then the nozzles pick up the seed a vibrator vibrate the seed bin, in other case thenozzles picking up more than just 1 seed at the time. To prevent that dirt block thenozzle a cleaning needle is put inside the nozzle. A short air blast runs the needle outin the nozzle and the vacuum (that sucks the seed) runs it back.The result of the project is a 1:1 scale prototype that has been tested.The test result shows that the developed module has a reliability of 92 % when it istested under optimal circumstances. 92 % is not good enough for a seeder that shouldbe sold. The author thinks that the principle has potential to manage BCC srequirements on reliability. To manage this problem the module must be furtherdeveloped.