Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Within LiU Fluid laboratory there had been a number of hydraulic and pneumatic test stands for research projects and teaching. The effort was needed to do more extension within the field of pneumatics. This thesis was about designing, manufacturing, building and testing the Test Stand for vertical application of pneumatic rodless cylinder. It consisted of three main parts; mechanical structure, pneumatic system and electrical and electronics. The design part focused more on the mechanical structure and pneumatic system. Electrical and electronics had to be installed to facilitate actuation and control of the system after mechanical and pneumatic components were assembled together. The mechanical structure consisted of three main parts; cabinet, carriage and ball balancer. For each part three concepts were generated, evaluated and selected to obtain the most promising concept for further development. The design values were given such that the mechanical structure should have total weight not exceeding 500 kg. The pneumatic system would supply maximum pressure of 8 bar. Upstream pressure was considered to be 6 bar after 25% pressure drop assumed to occur in the system. The mass to be lifted was typically 26 kg moving at a maximum speed of 2 m/s. The whole design process was carried out with safety and design for assembly in mind. The methodologies applied in the design included; identification of need, concept generation, concept selection, CAD modeling and simulation and FE Analysis. Development of concepts involved CAD drawings (3D and 2D) in CATIA V5, calculations and selection of appropriate materials for each component. The pneumatic cylinder applied in this design was a rod-less cylinder (Bosch Rexroth; RTC-DA, MNR: R480628571) with a Piston diameter of 50 mm, stroke of 1.2 m and cushioning stroke of 20 mm. More design information on RTC-DA was not available therefore the information in appendix A was based on series RTC-BV which had close similarities with series RTC-DA. The carriage that moves up and down along the cylinder stroke was designed with a mechanism that imparted disturbance to the system. The mechanism could be set to impart either 100.7 N or 151.02 N disturbance. The design was done with the assumptions that:
Spring force Fs and extension x were constant
The system had sonic flow characteristics and critical flow appeared in meter out orifice.
The air was perfect gas which obeyed equation of state
Specific heat was constant
Viscosity was constant
Flow was one dimensional
System pressure drop was 25% of the maximum supply pressure.
Dynamics of the system were estimated analytically and by means of simulation. Corresponding parameter values such as pressure, velocity, flow rate, cushioning stiffness, cushioning force and acceleration were obtained and compared. The product in general conformed to the specifications made prior to the design process.
2014. , 98 p.