Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE credits
The project ”Investment proposal for grinding station for service work of screw feeders” has been performed during the spring semester 2014 for the course Bachelor’s thesis for degree of Bachelor of science in machine engineering at Karlstad’s University. The project has been performed in cooperation with Fiber Workshop which is a service department in the company Valmet AB. Valmet AB is a company that develops and manufacture soft paper tissue machines. The screw feeder is a part that is used to feed, and squeeze out the water out of woodchips. The service work of the screw feeder mostly consists of service work on two major parts, namely the feeder screw and the split pipe, which the feeder screw is mounted in.
The purpose of the project was to evaluate the service work, namely the grinding in a working environment point of view. Another goal of the project was to present some improvements for this process.
The working environment which has been evaluated is primarily the risk of vibration damage in arm and hand, the risk of ergonomic musculoskeletal disorders and even a dust measurement has been performed, with the help of Hans-Olov Karlsson from the company Clarahälsan.
The result from the working environment survey suggests that the operator exceed the work environment limits in regards to the risk of suffering damages from vibrations in the hand and arm. The grinding work of the split pipe is considered to be a bigger problem in regards to ergonomics than the grinding on the feeder screw. The split pipe requires the operator to stand in a posture that takes more concentration and precision than for the feeder screw. The results from the dust measurements indicate that the levels of dust in the air, during the grinding, are within the approved limits. The safety equipment used by the operator is adequate, there has however been a desire of the client to find a solution that manages the dust.
One of the improvement proposals consists mainly of a number of accessories for the grinder to help improve the problems with vibration and the dust. The possibilities to circumvent the grinding work for the screw pipe altogether have been examined. It is possible to begin to mill the screw pipe in the lathe, which has a powered tool. For it to be possible to mill the split pipe instead of grinding, the lathe machine is in need of an extension arm, to be able to reach down the whole split pipe. This arm has been designed and developed in this project.
2014. , 34 p.