Attachment for air gauging apparatus

#1. Field of the Invention

#This invention relates generally to air gauging equipment and more particularly is directed towards a new and improved attachment for the nozzle of air gauging apparatus to adapt the apparatus for use with thin, fragile films and rough or irregular surfaces.

#2. Description of the Prior Art

#FIG. 1 is a sectional view in side elevation of an air gauging apparatus equipped with an attachment made according to the invention,

#FIG. 2 is an enlarged sectional detail view in side elevation of the nozzle tip and attachment,

#FIG. 3 is a perspective view of the attachment,

#Referring now to the drawings and to FIG. 1 in particular, there is illustrated a pneumatic servo-mechanism or air gauging follower 10 of the sort disclosed in my U.S. Pat. No. 3,194,055 and to which is attached an accessory 12 made according to the present invention. The follower 10 comprises a nozzle indicated generally at 14 spaced adjacent to work W which typically is a part placed on a flat bearing surface 16. Most preferably, the nozzle 14 is of the extended range type disclosed in my U.S. Pat. No. 2,692,498, dated Oct. 26, 1954, entitled "Air Gauge" and having an air inlet 18, a gauge orifice 20, a tube 22 and a plug 24. While a fuller description of the operation of the nozzle may be obtained from U.S. Pat. No. 2,692,498, in general, air under pressure supplied to the inlet 18 exhausts through the orifice 20 against the work W, developing a work reflected back pressure in the tube 22 which varies inversely as the distance between the nozzle 14 and the work W. Such back pressure is communicated by suitable means to other parts of the apparatus to be described.

#Means are provided for causing the nozzle 14 to follow or float at a uniform distance from the work W. The means comprise a pneumatic cylinder 26 having its upper and lower ends closed by manifolds 28 and 30, respectively, secured to a standard 32 supporting the entire apparatus. A piston 34 is mounted within the cylinder and is adapted to reciprocate therein. The piston is fitted with an elongated, hollow, open-ended piston rod or stem 36 fixed to it and extending lengthwise within the cylinder and projecting through openings in the manifolds. An O-ring 38 provides a fluid-tight, sliding seal between the piston and cylinder.

#The lower end of the piston rod 36 is adapted to snuggly receive the plug 24 of the nozzle 14 threaded thereto. The upper end of the piston rod is closed by a cap 40 which bears against a push rod 42 of a standard dial indicator 44 supported by a bracket 46. The back pressure produced in the tube 22 of the nozzle 14 is effectively communicated to the interior of the piston rod 36 and thence through a port 48 in the rod wall at a point below the piston to the interior of the lower chamber of the cylinder.