초록 ▼

A turning guide for a running web and which guide has a curved guide surface with air slots therein and pressurized air supplied from a blower is delivered through a plenum to the guide to form a cushion of pressurized air which floatingly supports the web. An adjustable damper operated by a servomo

A turning guide for a running web and which guide has a curved guide surface with air slots therein and pressurized air supplied from a blower is delivered through a plenum to the guide to form a cushion of pressurized air which floatingly supports the web. An adjustable damper operated by a servomotor regulates air flow and controls the clearance spacing between the curved guide surface and the web. Control apparatus for the servomotor comprises an electronic control unit, including a memory and a central processing unit (CPU), to which are connected an ultrasonic signal generator, an ultrasonic signal receiver, temperature sensing devices located with the ultrasonic signal sensors, a sensor responsive to blower operation, and a sensor responsive to web presence. In operation, after a desired web clearance set-point is entered into the memory and blower operation and web presence are established, an ultrasonic signal from the signal generator is reflected off of the web to the signal receiver. The time interval between initiation and reception of the ultrasonic signal, compensated for ambient temperature, is compared to the stored web clearance set-point value and, if necessary, a control signal from the electronic control unit operates the damper servomotor to change the pressure of the air cushion and thus move the web relative to the running guide surface to establish and maintain the selected web clearance spacing.

대표청구항 ▼

Web processing apparatus comprising: a contactless web guide; first means operable to support a web in spaced apart relationship from said contactless web guide; and control means operable to transmit, reflect off of said web, and receive an ultrasonic signal which travels through air to ascertain t

Web processing apparatus comprising: a contactless web guide; first means operable to support a web in spaced apart relationship from said contactless web guide; and control means operable to transmit, reflect off of said web, and receive an ultrasonic signal which travels through air to ascertain the actual position of said web relative to a predetermined position with respect to said web guide by measuring the distance traversed by said ultrasonic signal between transmission and reception thereof by measuring the time interval between transmission and reception of said ultrasonic signal and by effecting temperature compensation of said time interval in accordance with the ambient temperature of the air through which said ultrasonic signal travels; and to effect operation of said first means to move said web from said actual position to said predetermined position.