EC Driver - 41" Stroke Hydraulic Cylinder
It was decided to use a hydraulic cylinder resting on the floor of the argon spill trough in the EC carriage to drive the EC's motion on the center beam. Space was limited due to the spill bellows and their required support and containment system. The 0.0. of the cylinder had to be limited to 3 to 3-1/2 inches, maximum. The weight of a wet EC and carriage is estimated to be 320 tons. The rolling coefficient of friction of the Tychoway rollers chosen to guide the EC and carriage along the hardened centerbeam ways is claimed to be less than 0.0025. The driver will also need to overcome the forces produced by moving (rotating) the numerous bayonets located at the top of the cryostats in the many piping systems. These forces were conservatively estimated at 1000 lbs. The drive force required to overcome these forces was then calculated to be: 320(2,000) x 0.0025 + 1,000 = 2.600 lbs. (min. required). Due to the uncertainty in the actual roller coefficient of friction and the various unknowns in estimating the resistive forces contained in the piping and cabling systems attached to the cryostat, a conservative design factor of 5 was chosen. This should account for any uncertainty in our estimation of the minimum required drive force and also leaves us with a reserve to fall back on in case any unforeseen problems might arise. Thus the desired capacity of the driver was set at: (2,600) x 5 = 13,000 lbs. (design capacity). Assuming a 3 inch O.D. cylinder with a 1/2 inch wall (2 inch bore), we first analyzed a 1-3/8 inch diameter piston rod. Using Shigley & Mischke's 'Mechanical Engineering Design' (5th Ed.) and it's formulas for long columns with central loading, it was determined that a 1-3/8 inch diameter rod would not suffice, given our safety factor of 2. Increasing the piston rod diameter to 1-1/2 inches proved to be sufficient. The maximum allowable load came out to be approximately 17,000 lbs., which is greater than the 13,000 lbs. design capacity. With a 1-1/2 inch rod, a 2 inch bore and 10,000 psi capacity, the maximum return (retraction) force is: ({pi}/4)(2{sup 2}-1.52) x (10,000) = 13,744 lbs. (return force). This meets the desired design capacity of the cylinder. On the extension of the cylinder, the pressure will be limited such to produce only the 13,000 lb. design capacity. Through the use of a regulator on the cylinder extension inlet, the pressure will be limited to: 13,000/[({pi}/4)(2){sup 2}] {approx_equal} 4,200 psi. (regulator setting) and 4,200 x ({pi}/4)(2){sup 2} = 13,195 lbs. (thrust force). Another reference used by some Fermi engineers in designing hydraulic cylinders is the 'Design Engineers Handbook', Bulletin 0224-B1 published by the Parker-Hannifin Corporation. The piston rod-stroke selection table on page b-5 is used to determine the stroke factor. Our setup most approximates Case II of the table which gives a stroke factor of 0.70. Multiplying this by the actual stroke (41-inch) gives us a basic length of 28.7-inch. Using the piston rodstroke selection graph on page b-6, the 1-1/2 inch rod and 28.7-inch basic length indicate an allowable thrust of approximately 13,000 lbs. According to the Chief Application Engineer at the Parker-Hannifin regional sales office in Des Plaines, IL, a min imum safety factor of 4 can be assumed in the piston rod-stroke selection graph, possibly even higher. This would be at least twice as high as our initial safety factor of 2. Thus we feel our cylinder design falls well within the acceptable region of this reference.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1031841
- Report Number(s):
- FERMILAB-D0-EN-254; TRN: US201201%%1030
- Country of Publication:
- United States
- Language:
- English
Similar Records
End Calorimeter Support Carriage Analysis
Trip Report: RAM-PAC International