【正文】 easily slow. Because standard paonents are used to construct the logic, it is easier to build than a mechanical control . Pneumatic control parts are subject to wear. As does a mechanical control, an electromechanical control uses switches, relays, times counters, and so on, to construct logic, it is faster and more flexible. The controllers using electromechanical control are called relay devices. The values in the express the relative tool distance from the home position. This distance is shown in the relative or incremental coordinates, U and W. when reading the values in the not possible to know directly how far the tool is from the part origin. Just how far it is from the home position. mounted on exhaust ports of air valves and actuators to reduce noise and prevent operating personnel from possible injury resulting not only from exposure to noise but also from high— speed airborne sign of the coordinates is zero or negative because the tool cannot move farther than the machine origin . thus at present , the values are zero so 設(shè)計(jì)巴巴工作室 the tool is at the home position. The values in the are normally used when setting up the tools in order to find the real tool distances from the part origin. The values in the absolute position express the absolute tool distance from the part origin. This distance is shown in shown in absolute coordinates, x and z .the sign may be positive or negative, depending on the quadrants in which the tool is moving. because of the pressibility of air， it is impossible to obtain precise controlled actuator velocities with pneumatic systems． also， precise positioning control is not obtainable． While pneumatic pressures are quite so far is to good. This is an important piece of information for the operator when maching, since any value in the absolute position is directly related to the part. The secret of hydraulic system’s SUCCESS and widespread use is its versatility and manageability． Fluid power is not hindered by the geometry operations when the potential difference between the tool and the work piece is sufficiently high, a transient spark discharges through the fluid, removing a very small amount of metal from the work piece of the machine as is the ease in mechanical systems． Also，power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical 1imitations of materials as are the electrical systems． For example， the performance of an electromag is limited by The saturation limit of steel． On the other hand， the power limit of fluid systems is 1imited only by the strength capacity of the material． In the express the relative tool distance from the home position. This distance is shown in the relative or incremental coordinates, U and W. when reading the values in the not possible to know directly how far the tool is from the part origin. Just how far it is from the home position. The sign of the coordinates is zero or negative because the tool cannot move farther than the machine origin . thus at present , the values are zero so the tool is at the home position. The values in the are normally used when setting up the tools in order to find the real tool distances from the part origin. Industry is going to depend more and more on automation in order to increase productivity． This includes remote and direct control of production operations，manufacturing processes。 bearings， reduction gears， etc． are eliminated． This provides a simple， pact system． In addition， very little input torque is required to produce the control needed for the toughest applications． This is important where 1imitations of control space require a small steering wheel and it bees necessary to reduce operator fatigue． 設(shè)計(jì)巴巴工作室 There are several types of shaft couplings。automatic． protection against overloads， and infinitely variable speed contr01． Fluid power systems also have the highest horsepower per weight rati0 of any known power source． In spite of al 1 these highly desirable features of fluid power， it is not a panacea for all power transmission problems． work revolves as the table moves along the ways, a helical or spiral cut is produced。 Air source similar to an electrical system where you mere