Paper machinery

2,940,418

June 14, 1960

W. R. PENROD ETAL

PAPER MACHINERY

Filed March 27, 1959

FIG-1

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INVENTORS

WILLIAM R. PENROD 8

By RICHARD W. PHELPS

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ATTORNEYS

2,940,418

Patented June 14, 1960

United States Patent Office

2,940,418

PAPER MACHINERY

William R. Penrod and Richard W. Phelps, Fulton, N.Y., assignors to The Black-Clawson Company, Hamilton, Ohio, a corporation of Ohio

Filed Mar. 27, 1959, Ser. No. 802,449

Claims. (CI. 118—63)

This invention relates to paper machinery, and more particularly, to apparatus for coating paper and other web materials.

The invention has special relation to coating devices of the type known as an “air doctor” or “air knife” which are utilized for doctoring or smoothing a fluid slurry of coating material applied to the surface of a paper web during the coating thereof. Such device commonly includes an elongated tube or pipe extending along and closely adjacent the surface of a backing roll over which the coated web or sheet is passing, and is provided with an axially extending slot nozzle for directing a thin stream of air to impinge upon the coating on the web or sheet passing over the backing roll and thereby to exercise thereon a doctoring function. Illustrative of air doctor apparatus of the character to which this invention relates are disclosed in Terry Patent No. 2,139,628 and the copending application of Richard W. Phelps, Serial No. 708,479, filed January 13, 1958.

It is desirable with air doctor apparatus of this character to provide for fine adjustment to control the size, direction and positioning of the slot from which the air stream emerges with regard to such considerations as the particular results desired, the velocity or pressure of the air being ejected through the slot, the desired uniformity or non-uniformity of the slot gap at various places along the device, etc. Such adjustment may be^;desired at closely spaced points along the slot, particularly with long air doctor devices for use on wide coating machines. Also such adjustment may be desired in addition’ to or independently of other adjustments of the entire air doctor device with respect to a backing roll with which it is associated such as by the supporting and adjusting means indicated in the above patent and pending application.

According to this invention an air doctor device of the ’ character described is provided having an air emitting slot defined by elongated cooperating lip members, with adjustability being provided not only as between the lip members but also independently or mutually with respect to a backing roll or other surface on which a stream of air emitted through the slot is intended to impinge. The adjustment is provided for at relatively closely spaced points along the device, and also the device is provided with self-sealing means within the moving parts of the adjusting mechanism for preventing escape of the air stream other than as directed through the slot as desired.

One object of this invention is to provide, in air doctor devices of the character described, for adjusting the size and direction of a slot through which air emerges for impinging upon the surface to be doctored independently of the support or mounting for the air doctor device itself.

Another-object of this invention is to provide, in an-air doctor device of the character described, independently adjustable lip members defining therebetween a slot through which a stream of air emerges to impinge upon the surface to be doctored, and. particularly to provide such a device wherein each of the lip members is adjust2 able independently with respect to the surface to be doctored.

A further object of this invention.is to provide, in an air doctor device of the character described, independently 5 and individually adjustable lip members defining therebetween a slot for the emergence of an air stream to impinge upon a.surface to be doctored, with each of the lip members being adjustably movable with respect to the source of air in the air doctor and including as a 10 part of its adjusting mechanism a sealing member for preventing escape of air other except through the slot defined by the lip members and as a stream to impinge upon the surface to be doctored.

Other objects and advantages of the invention will be 15 apparent from the following description, the accompanying drawing, and the appended claims.

In the drawing:

Fig. 1 is a transverse section along the line 1—1 Of Fig. 2 through an air doctor device embodying and for 20 practicing this invention and also indicating the association of the device with respect to a backing roll or other surface to be doctored;

Fig. 2 is a front elevational view, partly broken away and partly fragmentary, of an air doctor device.embody25 ing and for. practicing this invention;

Fig. 3 is a fragmentary view on a larger scale of one .of the fulcrum or pivot members in a device as indicated in Fig. 1; and

Fig. 4 is a fragmentary view in perspective showing one 30 .of the lip members of Fig. 1.

Referring to the drawing, which illustrates a preferred embodiment of the invention, an air doctor device of the character to which this invention relates comprises an elongated pipe 19 mounted; generally as indicated in Fig. 35 1 with respect to a backing roll 11 of a conventional paper coating machine, with a paper web having a coating thereon to be doctored being indicated at 12. The mounting of the air doctor across the coating machine is not shown in detail, and it may be satisfactorily supported at its ends 40 as by end bosses 13 in suitable supporting brackets Or ' means such, for example, as disclosed in the above patent and pending application.

The pipe 10 forms an air chamber closed by a flange 14 at each end, and one or both of the end. bosses .13 45 which form parts of the flanges 14 is hollow for the introduction therethrough of a supply of air under pressure to the interior of the pipe 10. Along so much of the length of pipe 10 as extends across the width of the web 12 on backing roll 11 to be doctored, there is provided a 50 series of discharge holes 15 for the emergence of streams of air under pressure from the interior of pipe 10, which streams of air are to be directed to impinge upon¹ the surface 12 to be doctored as an elongated “knife” of air thereacross.

The air stream from the holes 15 is controlled by a pair of elongated and converging lip members 20 and 21 which form a nozzle defining therebetween a relatively narrow slot 22 for directing the stream of air to impinge with the required velocity and force on to the sur60 face 12 to be doctored. The lower lip member 20 is shown as a generally flat plate, but the upper lip member 21 includes a flange 23‘ integral with or welded.to a reinforcing strap. 24 to which the lip member 21 is secured by a plurality of cap screws 25, and bracing ribs ⁶³ 26 are welded to the flange 23. and, plate 24 at spaced locations therealong. This. upper lip assembly also incorporates means for flexing the lip member 21,,particularly to assure accurate alignment of-the working edge __ of the lip. Such adjusting means include: a plurality of ⁰ set screws 27 threaded through the plate¹24-for engagement with the lip 21, and such flexing of the lip is also

2,940,418 facilitated by the groove 28 extending longitudinally of its upper surface.

The lip members 20 and 21 are mounted on the pipe TO generally in the positions shown in Fig . 1 and in such relation with the holes IS in. pipe 10 as to direct the stream of air from these holes through the slot 22 for impingement in the desired manner and direction on the web surface 12 to be doctored. In addition, the mountings of the lip members 20 and 21 in accordance with the invention incorporate special provision for adjusting and controlling the position of each of the lip members with respect to each other and to the web surface.

Referring particularly to Fig. 1, the lower lip member 20 is secured to the underside of the pipe 10 by a plurality of screws 30 which pass freely through the bores 31 in the lip member 20 and are threaded into receiving bores 32 in the pipe. A rod 33 extends substantially the full length of the lip 21 in retaining grooves 34 and 35 in the opposed surfaces of the lip member 20 and the pipe 10 to form a fulcrum about which the lip member 20 can be rocked. Such rocking movement is effected and controlled by a plurality of set screws 36 which extend through the lip member 20 along its back edge for adjustable engagement with the wall of pipe 10 and thus cooperate with the screws 30 in the rocking adjusting movement of the lip member 20. The part 38 in Fig. 1 is a dust seal.

A similar adjustable mounting is provided for the lip member 21 and includes cap screws 40 passing freely through the flange 23 into tapped bores 41 in the pipe 10. The fulcrum rod 44 extends substantially the full length of the lip member 21 in retaining grooves 45 and .46 in the opposed surfaces of the flange 23 and pipe 10, and the set screws 47 cooperate with the screws 40 to effect the desired rocking movement of the lip assembly about the rod 44. This entire assembly is also shown as provided with a sheet metal cover 50 mounted by means of screws 51 threaded into the reinforcing ribs 26.

In the' use of this air doctor construction as described, either or both of the lip members 20 and 21 may be adjusted with great accuracy to the proper relatiop with the other lip member and the surface 12 to be doctored, and it will be noted that the mounting construction of the invention facilitates adjustment of the upper lip member 21 into an overhanging relation with the lower lip member 20 by the preferred range of several thousandths of an inch in order to direct the flow of air downwardly against the surface 12 and thereby to aid in keeping the lower lip member 20 clear of accumulated slurry from surface 12 which might otherwise tend to collect thereon.

The mounting and adjusting constructions of the invention are thus simple but highly accurate, and they have the further advantage of incorporating effective seals against escape of the pressure air between either lip member and the pipe 10, since with the screws 30 and 40 clamping the lip members to the pipe 10 through the fulcrum rods 33 and 44, the rods serve also as effective sealing members. A particular advantage of the constructions of the invention is that all adjustments are made from outside the pipe 10 and thus require minimum time and dismantling of any of the associated equipment. Furthermore, all of these advantages are obtained with component parts which are individually economical to produce and also are easily assembled in the finished device. .

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that this invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.