In order to construct a pneumatic system (a terminal system including components from a directional control valve to an air cylinder) which is specified by a user, there has been devised a slide rule for designing a pneumatic pressure control system (e.g., see Patent Document 1).
The slide rule has fixed and slidable scales marked on their face and back sides with graduations to satisfy a formula for determining a stroke time of a double-acting cylinder, a formula for determining a cylinder output, a formula for determining an amount of air consumed by the cylinder and a tube connected thereto, and other formulas. In combination with cursor operations, the slide rule can quickly calculate specifications required for designing the pneumatic pressure control system.
Heretofore, it has been customary to select pneumatic devices according to approximate simple calculations on the slide rule because accurate dynamic simulations of a desired pneumatic pressure control system have not been possible. Therefore, the results of a conventional process of selecting pneumatic devices satisfy required values with considerably low probability, making it impossible to construct a desired pneumatic pressure control system of a minimum group of pneumatic devices and to achieve a minimum energy consumption and a minimum cost.
For the above reasons, there has been a demand for a process of quickly selecting a group of optimum pneumatic devices which satisfy conditions specified by the user, using highly accurate and reliable calculating methods. For selecting a pneumatic device, it is necessary to satisfy (1) a load condition (a dynamic condition for a selected system to operate sufficiently under input conditions, such as a load mass and thrust, an application, and a supplied air pressure, of a specified operating unit (pneumatic actuator)), (2) a velocity condition (a condition for a selected system to reach a stroke end of an output member (e.g., the piston of a cylinder) of a pneumatic actuator within a specified full stroke time), (3) a strength condition (a condition for a selected system to satisfy the specified load condition while preventing the pneumatic actuator from being buckled, deformed, or broken), and (4) a connecting condition (a condition for devices making up a selected system to be connected normally).
The applicant of the present application has proposed a method of selecting a pneumatic device in order to satisfy the above conditions (e.g., see Patent Documents 2 through 5). The proposed method is advantageous in that it can select a pneumatic device highly accurately by using a dynamic characteristic analyzing process, unlike a conventional effective area method.    Patent Document 1: Japanese Patent Publication No. 53-21320;    Patent Document 2: Japanese Laid-Open Patent Publication No. 2000-179503;    Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-113808;    Patent Document 4: Japanese Laid-Open Patent Publication No. 2003-113885; and    Patent Document 5: Japanese Laid-Open Patent Publication No. 2003-114913.