输液液体滴数计算公式（共1篇）

输液液体滴数计算公式（共1篇） 以下是网友分享的关于输液液体滴数计算公式的资料1 篇，希望对您有所帮助，就爱阅读感谢您的支持。 液压计算公式[一]篇一 Fluid Power Formula These Formula Cover All Fluid Power Applications In This Manual For Computer Programs To Work Problems By Simply Filling In The Blanks See Your Local Fluid Power Distributor 1 Many Companies Web Site Or CD Also See The Fluid Power Data Book Packaged With This Manual For Charts and Other Fluid Power Information Fluid Power Formula 1 Fluid Power Formula 2 Fluid Power Formula 3 Fluid Power Formula 4 Fluid Power Formula 5 Fluid Power Formula 6 Fluid Power Formula 7 Fluid Power Formula 2 8 Fluid Power Formula 9 Fluid Power Formula 10 Fluid Power Formula Continued on Next Page 11 Fluid Power Formula Continued on Next Page 12 Fluid Power Formula 13 Fluid Power Formula Fluid Power Formula SIZING A HYDRAULIC CIRCUIT On the facing page is an exercise sizing a simple single cylinder hydraulic circuit with straight forward parameters. The example gives basic requirements for sizing a hydraulic 3 cylinder powered machine. In the real world of circuit design, experience, knowing the process, the environment, the skill of the user, how long will the machine be in service, and other items affect cylinder and power unit choices. Before designing any circuit it is necessary to know several things. First is force requirement. Usually, the force to do the work is figured with a formula. In instances where there is no known mathematical way to figure force, use a mock up part on a shop press or on a prototype machine for best results. If all else fails, an educated guess may suffice. The sample problem requires a force of 50,000 pounds. Second, choose a total cylinder stroke. Stroke length is part of machine function and is necessary to figure pump size. Use a stroke of 42 inches in this problem. Third, how much of the stroke requires full tonnage? If only a small portion of the stroke needs full force, a HI-LO pump circuit and/or a regeneration circuit could reduce first cost and operating cost. This cylinder requires full tonnage for all 42 inches. Load, unload and dwell are part of the overall cycle time, but should not be included when figuring pump flow. Use a 4 cylinder cycle time of 10 seconds for this problem. Finally, choose maximum system pressure. This is often a matter of preference of the circuit designer. Standard hydraulic components operate at 3000 PSI maximum, so choose a system pressure at or below this pressure. If a company has operating and maximum pressure specifications, adhere to them. Remember, lower working pressures require larger pumps and valves at high flow to get the desired speed. On the facing page part A, taking the square root of the maximum thrust, times 110%, for fast pressure buildup, divided by the maximum system PSI, divided by .7854. This gives a minimum cylinder bore of 5.244”. Choose a standard 6” diameter cylinder for this system. To figure pump capacity, take the cylinder piston area in square inches, times the cylinder stroke in inches, times 60 seconds, divided by the cycle time in seconds, times 231 cubic inches per gallon. This shows a minimum pump flow of 61.7 GPM. A 65 GPM pump is the closest flow available. Never undersize the pump since this formula figures the cylinder is going maximum speed the whole stroke. The cylinder must accelerate and decelerate for smooth 5 operation, so travel speed after acceleration and before deceleration should actually be higher than this formula allows. Figure horsepower by taking GPM times PSI times a constant of .000583. This comes out to 75.79 HP, and is close to a standard 75 HP motor. This should be sufficient horsepower since the system pressure does not have to go to 2000 PSI with the cylinder size used. The tank size should be at least two to three times pump flow, which is three times sixty-five, or 195 gallons, so a 200 gallon tank is satisfactory. When using single acting cylinders or unusually large piston rods, size the tank for enough oil to satisfy cylinder volume without starving the pump. 15 Fluid Power Formula Fluid Power Formula SIZING A PNEUMATIC CIRCUIT Sizing air cylinders is similar to sizing hydraulic cylinders. Most air systems operate around 100 to 120 PSI with approximately 80 PSI readily available at the machine site. 6 This gives little or no option for selecting operating pressure. Since the compressor is part of plant facilities, the amount of cubic feet per minute (CFM) of air available for the air circuit usually is many times that required. It is good practice though, to check for ample CFM flow capabilities at the machine location. The only items needed to figure an air circuit is maximum force required, cylinder stroke, and cycle time. With this information, sizing cylinders, valves, and piping is simple. To figure the cylinder bore required, use the formula given at A. Notice the added multiplier on the force line. For an air cylinder to move at a nominal rate, it needs approximately 25% greater thrust than the force required to offset the load. When the cylinder must move fast, figure a force at up to twice that required to balance the load. The reason for this added force relates to filling an empty tank from a tank at 100 PSI. When air first starts transferring, a high pressure difference allows fast flow. As the two tanks get closer to the same pressure the rate of transfer slows until the gauges almost stop moving. The last five to ten PSI of transfer takes a long time. As the tanks get close to the same pressure, there is less reason for 7 transfer since pressure difference is so low. If an air cylinder needs 78 PSI to balance the load, then it has only 2 PSI differential to move fluid into the cylinder at a system pressure of 80 PSI. If it moves at all, it is very slow and intermittent. As pressure differential increases, from higher inlet pressure or less load, the cylinder starts to move smoothly and steadily. The greater the differential the faster the cylinder movement. Once cylinder force is twice the load balance, speed increase is minimal. Using the 1.25 figure in the formula shows a cylinder bore of 1.72” minimum. Choose a 2” bore cylinder since it is the next size greater than 1.72.” To size the valve use the “flow coefficient,” or Cv rating formula. The Cv factor is an expression of how many gallons of water pass through a valve, from inlet to outlet, at a certain pressure differential. There are many ways of reporting Cv valve efficiency and some may be misleading. Always look at pressure drop allowed when figuring the Cv , to be able to compare different brands intelligently. The formula shows a valve with 1/8” ports is big enough to cycle the 2” bore cylinder out 14” and back 14” in 4 seconds. There are many charts in data books as well as valve manufacturers catalogs that 8 take the drudgery out of sizing valves and pipes. There are several computer programs as well to help in proper sizing of components. 17 9