US2448653A

US2448653A - Size gauging device

Info

Publication number: US2448653A
Application number: US660901A
Authority: US
Inventors: Aller Willis Fay
Original assignee: Sheffield Corp
Current assignee: Sheffield Corp
Priority date: 1946-04-10
Filing date: 1946-04-10
Publication date: 1948-09-07
Anticipated expiration: 1965-09-07

Description

Sept. 7, 1948. w. F. ALLER SIZE GAUGING DEVICE Filed April 10, 1946 LNVE NTOR My m BY V W 7 Jaw 7 ATTORNEY Patented Sept. 7, 1948 SIZE GAUGING DEVICE Willis Fay Aller, Dayton, Ohio, ,assignor toi'lhe Sheffield Corporation, Dayton; Ohiopa corporation of Ohio Application'April 10, 1946,? Serial No.. 660,901

. 4 Claims.

This invention relates to precision gauging of the size of objects.

One object of the invention is the provision of a precision gauging apparatus embodying an air leakage gauging nozzle or nozzles cooperating with the workpiece or object to be gauged as to size, and. an air pressure controlled electric switch having individually adjustable contact blades normally biased into exact positions and cooperating with spring blades controlled by a rigid arm secured to the free end of a curved hollow tube that is responsive to changes in air pressure as such changes are induced in a size gaugingoperation, the construction being such as to operate with no looseness of construction and with extreme preciseness and freedom from error.

' Another object of the invention is the provision of a-gauging apparatus of the character mentloned,,in which the pressure tube has an arcuate extent less than 360 degrees and the switch operating arm to which it isfixed is arranged in the plane of expansive movement of the pressure responsive tube and amplifies the. movement of the tube.

Other objects and advantages of the invention will be apparent from the following. description, the appended claims, and the accompanying drawing, in which,

Fig. 1- is aside view, with the [housing or support in central section, of an air pressure controlled electric switch employed in the present invention;

Fig. 2 is a sectional View taken on the line 22 of Fig. 1;

Fig. 3 is a detail view showing the pressure responsive tube support and the indicating mechanism that may be associated with it;

4 is a detail showing the connection-between the indicating pointer shaft and the end of the pressure responsive tube and also showing a portion-of the rigid switch operating arm; and

Fig. 5 is a view showing the application of the pressure switch in the size gauging apparatus of the present invention.

In accordance with the present invention a precision gauging apparatus is provided that checks compares or selects the sizes'of objects or'parts by measurement of the leakage flow of air supplied under pressure through a gauging nozzle or nozzles cooperating with the object. The air pressure variations caused by size-differences in the object gauged as compared to conditions whenan object or standard of the exact or known 2 size is used, are effectiveon a, pressure responsive curvedtube which in turn-controls adjustable switches that operate electrical "gauging, measuring or selecting devices.

As shown in the drawing, .in which the same reference numerals .have been-used in the several views to designate like pants,v and more particularly with reference to Fig.15,"the.-numeral"63 designates a pipe adapted to be connected" to the factory air line, is an adjustable pressure regulator. that. automatically, maintains a selected air pressure supplied to a restriction 65 in a: pipe 65-communi-cating with' a passage Til'in a'gaugingbody' .68. shown as adapted to receive thepa'rt or article 69 to be gaugedas to size. The passage '19 ext-ends to agauging nozzle H the outer surface ofv which is'spaced' slightly from the surface of the object 69, and the space-between the nozzle ll and the object -69 determines the amount of leakage-that takes place along the outer surface of'thenoz'zle. This space isdetermined'lby the size ofthe object. There are preterably two of these nozzles,- the second nozzle 72 being arranged diametrically opposite the-axis of the'object 69. "The amount of leakage taking place past the ends-of the gauging-nozzles is thus an accurateindication of thesize or diameterof the object; and the" amount of this leakage'is measured by the pressure existing onthe low pressure'side of the restriction 65.

' When an object or master of known size; rrepresenting the maximurn permissible size in-a tolerance range, is applied to the gauging body 68 a certain pressure will exist inthe =pipe-"66. There !Wi11 lbeanother pressure existing when a master of theminim-um' permissible sizeis applied. 'When the [obj set to be gauged isapplied, if it is within tolerance requirements, the 'pressure existing in pipefifi willbe'between the maximum'and minimum pressures determined by the masters.

The lpipeiit is in communication with the end of a curvedpressure-responsive tube which, in turn, controlsa pair of adjustable precision switches that are connected to electrical gauging or sizing devices. The tubes and'the switches are arranged in a supportlfl, connected to pipe Sit-by connection 18. r The electrical connections extending irom the switches are shown at 42 and each connected to an electrical relay, is which may be of the electromagnetic or electron type. Connection 43. is. a commonreturn Wire.

The support lDisshowna-s a housingin varicusnoperating pants are contained. .A sheet metal plate i l is secured to the housing by suitable attaching screws l2, the plate being fastened by means of screws it to a supply connection M which forms the support for the fixed end of a curved hollow pressure responsive tube I5 having a free end 85 which is annularly movable in response to changes in air pressure to which the interior of the tube is subjected through the supply pipe E8. The supply pipe is secured to the projecting end of the supply connection It by a suitable attachment nut 69.

A short link 2b is fixed to the free end it of the pressure responsive tube and carries a pivot pin 2i which may be connected, as illustrated in Fig. l, to a pointer operating mechanism to give a visible indication of the pressure, although it should be understood it is quite unnecessary that 1 such linkage and indicating pointer be used. However, where it is desired to provide a direct reading indicating pointer, the pivot pin 2! is connected through a link 22 to a lever 23 having a pivot support at 24 on a mounting plate '25 that is fixed to the supply connection M. The other end of the lever 23 is a gear segment having teeth 26 meshing with a pinion 2'! on the pointer shaft 28. The pointer 32 is visible through a glass 2t and operates over a scale plate 39 having suitable graduations or markings 3|.

The pressure responsive tube H5, at its free end I6, is securely fixed to a rigid switch operating arm 34, which is preferably brazed or soldered directly to the outer side of the end portion of the tube, as will be apparent from Fig. 4, so that the arm 34 lies in and moves in the plane in which the tube expands and contracts. The tube has a length in an annular direction less than 360 degrees so that the integral assemblage constituted by the arm 3 and the tube itself will be quite firm and have adequate strength to prevent oscillation or looseness of the free end of the switch operating arm. This firmness of construction permits the gauge to be mounted on a support subjected to vibration without causing oscillatory movements of the contacts. It also is such that there can be no looseness of the pointer in a direction transversethat in which the pointer has normal movement. The construction, however, is such that the free end of the arm 34 has a movement corresponding to the movement of the free end of the tube. but to a considerably amplified degree. This results from the manner in which the arm is extended outwardly to a po nt remote from the tube, the arm curving around a portion of the tube and then extendin straight outwardly but being so arranged that the only place where the arm and the tube are in contact is at the free end of the tube. where the two parts are securely fixed together against any relative movement. The assemblage constituted by the tube and the arm is mechanically friction ess and there is absolutely no lost motion in these parts.

The free end of the arm 3 (see Figs. 1 and 3) is provided with a pair of lugs 36 and 3'! of electrical insulating material such as hard rubber or the like. The lug 31 operates freely through a hole or slot 38 in a rigid switch blade 39 that extends generally parallel to the direction of the free end of arm 34. If the lug 37 extends far enough through the hole in blade 39 it contacts and moves or flexes a flexible metal spring strip or blade M1. The rigid blade 39 and the spring strip 4B are provided with contact points 4. t! that are normally in contact with one another and close the circuit through the two switch blades and through wires E-Z and 43 that lead to the indicating or controlling device that is governed by the pressure switch. The spring strip ib has an inherent spring bias that hold it normally in engagement with the blade 39 and, as will be apparent from 1, one end of the spring strip is fixed by means of an insulating block 45 to a short spring strip (it that also carries the blade 39. One end of the spring strip M3 is fastened to an outwardly projecting ear i? that is struck up in the metal plate ii, the short spring strip Alt serving to normally bias both of the switch blades upwardly as viewed in Fig. 1 and holding an insulating lug ie on the blade 38 yieldingly against the outer end of an adjustment post at. The position of the post 58 can be readily changed by turning the control knob 5i thus rotating a threaded portion 55 of the post 5 within a fixed nut 55" held in the support ill.

At the opposite side of the arm 3& is a similar switch constituted by the rigid blade 52 having a hole in it through which the lug 36 is freely movable, and the flexible strip or blade 53 that is normally biased towards the blade 52 to hold their contact points 58 in engagement. The strip 53 can be moved outwardly by the insulating lug 36 when the outer end of the arm 34 is moved upwardly from the position shown in Fig. l. The ends of the blades 52 an 53 are carried by a short spring strip E l secured to an ear 55 on plate H. The short spring strip ti l normally urges both the switch blades upwardly as viewed in Figs. 1 and 3, and hold the rigid blade 52 against an adjustable post 56 controlled by adjustment ltnob 5?. The adjustment post '56 extends freely through a hole in the flexible blade 53 and engages an insulating lug 58 on the rigid blade 52.

The two adjustment knobs 5i and 5'? can be so turned as to locate the two pairs of switch blades free of the ends of the insulating lugs 36 and 3'! so that both switches will be closed when the arm 36 is in a centered position as illustrated in Fig. 1, which is a position it assumes when there is some air pressure existing in the interior of the tube. With atmospheric pressure in the tube, the tube will be contracted and the outer end of the arm 34 will move downwardly and engage the flexible spring strip 49 so as to move it out of contact with the rigid blade 39. As the pressure in the tube increases to some predetermined value, and the tube expands it will move the arm 34 upwardly and close the circuit of the switch blades 39 and it]. It may then travel further through a distance controlled by the setting of the knob 57 before the lug 36 engages and opens the switch blade 53 from the rigid blade 52. The amount of motion required of the arm 3 before closing one switch and opening the other can be made as great or as small as desired merely by controlling the position of the knobs 5! and 51.

When a part of standard or known siZe is applied to the body 68, the knobs 5i and 57 are set so that objects that fall within the acceptable range of sizes will not cause either of the two switches to open. Thus when the object to be tested is in place in the body 68, one or the other of the two switches will be opened if the size of the object is either too large or too small. These switches control the relay coils or electron tubes which are suitably connected to electrically energized devices such. asuselector 'gateszor, indicators.

Although-the:insulating-knobs? and 31 are required to: -pass..through 1110165 in. .one. of the switch; blades of. each-pain-of switches, these holes need lonlybe .made slightly largertharr .the size-of the .insulatinglugs sinceno lost motion can be. present .ins..the switclr blades; themselves and. no freedom .of movement is ipermitted the arm 34 in: a: direction. transverse to .that .-in-;wh-ich it -is normally; zmovablegior? in. other words: in; a plane transversento the movement ;of:.:the :pressure responsive tube itself.

Noundue strains. are applied either to the tube, the arm 34, or the switch blades, such as would interfere with the-proper setting and operation of the: apparatus, when the arm is moved excessively in one direction or-the other due to unusually largepressure or due tqzero pressure existing in the tube. *Thismovement-cannot effeet the; setting of the rigid-spring blades of the switches and imposes no unus ual .forces; onathe op r tin :parts ,of t r;m chanism. sinc 1 the flexibl pr n blade can yi l o rd to a very considerable degree; and-will; promptly return to full contact with the rigid blades when the moving force is removed. The switch contacts operate in a precise manner so as to make or break contact at an exact position of the arm with a precision of a fractional part of a. ten thousandth of an inch movement of the flexible contact. The fixed switch blade arrangement is such that the fixed contact does not yield or move when the pressure of the flexible blade is applied to it or removed from it, and regardless of the extent of flexing movement of the flexible blade it will return to bring its contact point into contact with the adjustably fixed blade under the air pressure condition for which the device is set.

The electrical circuit controlled by the

switch blades

39 and 40 is through the

wires

42 and 43, while switch blades 53 and 52 are connected respectively to a wire 60 and to an extension SI of wire 42, all the switches and wires being insulated from the tube and the arm 34 so that no current flow through the tube can take place and inaccuracies of indications due to heating or inductive effect on the tube are completely avoided.

With an air pressure switch of this character the automatic operation of air pressure controlled sizing devices can be effected with precision since any particular pressure that may be applied to the pressure responsive tube I5 will always result in exactly the same position of the switches for any initial setup, and precision comparison readings obtained in a device using a supply pressure of the order of twenty pounds per square inch that will show size variations smaller than a thousandth of an inch and, if desired, to show size variations even smaller than one ten-thousandths of an inch. In such a precision sizing extremely reliable operation is necessary and the pressure controlled switches must be necessarily such that the arrangement can be used on vibrating parts, be applied in any of several positions, and be capable of operation over long periods of time without attention, otherwise the employment of a pressure switch in a size gauging system that employs air leakage as a basis for size measurement would be impractical. It is of utmost importance that the device should repeat time after time With exactness and precision capable to distinguish size difierentials of the order of a part of a thousandth of an inch.

The.pnesentint nt on.accomplish s..these'des ble results.

.J'WhiIe th fen nofs app rat aher inzdeseri e constitutes; a: preferred a embodiment; of the: inventi n, it ;is, to bezunderstood that thelinvention is;not;li mited to thisgprecise form of apparatus, and-that bans sx xbe :inade therein withou ep rtin fzfmm t e co f. the vention :Which iszdefin dzin th appende cla m What 5 la me is I 1. iIn-agprecisionr. gau ing app rat s for n ing-the sizeof an object; by: measuring the amount of. air. leaka supplie un er. pre su thr h a gauging noz l or nozzl cooperatin wi h h object: in combination; a gau in noz l f rcooperationwith the object tube. gauged-a pressure responsivecurved tube having a fixed end; and having. aclosed ;,freeend which :has expansive movement .-in-, a 'plane in accordance with .pressure changes; a support; for the ifixed, end of said tube. meansplaoingthefixed endof said tube in com municationwith saidmozzlega rigid armfixedly secured: atone endsthereof; ,to the free end;- ofthe tube. and :proj ectingwf-rom the tube to ;a remote location; so the remote endof the; arm-moves in accordance with the:movementrof the. freeendwf the tube, a rigid switch blade at each side of said arm, a flexible spring blade at each side of said arm biased to contact with its respective rigid blade and movable from its respective rigid blade by said arm, means fixed with respect to said support for carrying said blades, and means for independently adjustably setting said rigid blades to precisely located positions.

2. In a precision gauging apparatus for gauging the size of an object by measuring the amount of air leakage supplied under pressure through a gauging nozzle or nozzles cooperating with the object, in combination, a gauging nozzle for cooperation with the object to be gauged, a pressure responsive curved tube having a fixed end and having a closed free end which has expansive movement in a plane in accordance with pressure changes, a support for the fixed end of said tube, means placing the fixed end of said tube in communication with said nozzle, a rigid arm fixedly secured at one end thereof to the free end of the tube and projecting in the plane of expansive movement of the tube to a location remote from the tube so the remote end of the-arm moves in accordance with the movement of the free end of the tube but to an amplified degree, a rigid switch blade at one side of said arm, a flexible spring blade biased to contact with the rigid blade and movable from the rigid blade by said arm, means fixed with respect to said support for carrying said blades. means for adjusting the position of said rigid blade to a precisely located position, and an electrical relay connected to said blades and electrically independent of said tube.

3. In a precision gauging apparatus for gauging the size of an object by measuring the amount of air leakage supplied under pressure through a gauging nozzle or nozzles cooperating with the object, in combination, a gauging nozzle for cooperation with the object to be gauged, a pressure responsive curved tube having a fixed end and having a closed free end which has expansive movement in a plane in accordance with pressure changes, a support for the fixed end of said tube, means placing the fixed end of said tube in communication with said nozzle, a rigid arm fixedly secured at one end thereof to the free end of the tube and projecting in the plane of expansive movement of the tube to a location remote from the tube so the remote end of the arm moves in accordance with the movement of the free end of the tube but to an amplified degree, an insulating lug near the outer end of the arm, a perforated rigid switch blade through which the lug is freely movable, a flexible spring blade biased to contact with the rigid blade and movable from the rigid blade by said lug, means fixed with respect to said support for carrying said blades, and means for adjustably setting the position of said rigid blade to a precisely located position.

4. In a precision gauging apparatus for gauging the size of an object by measuring the amount of air leakage supplied under pressure through a gauging nozzle or nozzles cooperating with the object, in combination, a gauging nozzle for cooperation with the object to be gauged, a pressure responsive curved tube having a fixed end and having a closed free end which has expansive movement in a plane in accordance with pressure changes, a support for the fixed end of said tube, means placing the fixed end of said tube in communication with said nozzle, the tube having an annular extent less than 360, a rigid arm fixedly secured at one end thereof to the free end of the tube and projecting in the 8 plane of expansive movement of the tube to a location remote from the tube so the remote end of the arm moves in accordance with the movement of the free end of the tube, a lug at each side of the outer end of the arm, a pair of perforated rigid switch blades one at each side of said arm through which the lugs are .freely movable. a flexible spring blade biased to contact with each rigid blade and movable from the rigid blade by said lugs, means fixed with respect to said support for carrying said blades, and means for independently adjusting the position of each of said rigid blades.

WILLIS FAY AILER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS