US3870597A

US3870597A - Drainage foil having a foil blade insert

Info

Publication number: US3870597A
Application number: US423628A
Authority: US
Inventors: Darryl L Getman; Marshall G Swenson
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1972-05-24
Filing date: 1973-12-10
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A drainage foil assembly wherein a structural foil body having a top surface is provided with a plurality of end abutting foil blade inserts which form an upper leading edge and top bearing surface flush with the body top surface. The foil blade inserts are mounted to the foil body solely by the use of springs which urge each of the foil blade inserts into seated engagement with the foil body in the direction of wire travel. The blade top bearing surface is positionable against a traveling wire to induce drainage on the foil side.

Description

United States Patent [1 1 Getman et al.

[ DRAINAGE FOIL HAVING A FOIL BLADE INSERT [75] Inventors: Darryl L. Getman, South Beloit; Marshall G. Swenson, Rockford,

both of 111.

[73] Assignee: Beloit Corporation, Beloit, Wis.

[22] Filed: Dec. 10, 1973 [211 Appl. No.: 423,628

Related U.S. Application Data [63] Continuation of Ser. No. 256,471, May 24, 1972,

abandonedv [52] U.S. Cl. 162/352, 162/374 [51] Int. Cl. D2lf 7/00 [58] Field of Search 162/352, 374

[56] References Cited UNITED STATES PATENTS 3,140,225 7/1964 Truxa 162/352 3,337,394 8/1967 White et a1. 162/374 3393,124 7/1968 Klingler et a1. 162/374 X 3,446,702 5/1969 Buchanan 162/374 3,574.056 4/1971 Jad et a1. 162/352 1 1 Mar. 11,1975

3,576,716 4/1971 Reynolds et al. 162/352 3,619,363 11/1971 Pherson 162/352 3,732,142 5/1973 Beacom et al. 162/374 3,778,342 12/1973 Charbonneau 162/352 FOREIGN PATENTS OR APPLICATIONS 1,958,758 6/1971 Germany 162/374 Primary Examiner-S. Leon Bashore Assistant Examiner-Richard V. Fisher Attorney, Agent, or FirmDirk J. Veneman; Bruce L. Samlan; Gerald A. Mathews [57] ABSTRACT A drainage foil assembly wherein a structural foil body having a top surface is provided with a plurality of end abutting foil blade inserts which form an upper leading edge and top bearing surface flush with the body top surface. The foil blade inserts are mounted to the foil body solely by the use of springs which urge each of the foil blade inserts into seated engagement with the foil body in the direction of wire travel. The blade top bearing surface is positionable against a traveling wire to induce drainage on the foil side.

11 Claims, 11 Drawing Figures PATENTEDHARI 1 I975 -SHEEI1UF3 3370597 PATENTED 1 I975 3,870,597 sum 3 95 3 F/G. 6a (PRIOR ART) FIG. 6b (PRIOR ART) d d 54 d lll 56 55 T\\ F/G. 6c (PRIOR ART) F/G. 6d (PRIOR ART) F/G. 6e (PRloR ART) DRAINAGE FOIL HAVING A FOIL BLADE INSERT This is a continuation, of application Ser. No. 256,471, filed May 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION In the forming section of a papermaking machine, such as the Fourdrinier type, water is removed through the wire on which the fiber-water slurry has been deposited by applying a foil blade to the opposite side of the wire. Usually, the leading edge of the foil is angled slightly away from the oncoming wire as is the trailing portion of the foil. The top surface of the foil over which the wire travels, and its leading edge, are sub jected to heavy wear. These surfaces are made of, or coated with, wear resistant material such as aluminum oxide, tungsten carbide, silicon carbide and chromium oxide to resist abrasive wear as much as possible.

The leading edge skims off the water carried on the wire and the downwardly angled rear portion of the foil produces a slight negative pressure differential on the foil side to induce entrained water to flow through the wire leaving the now considerably more dewatered fibrous mat on the top wire surface.

The position and angles of the leading and trailing rear portions of the foil are discussed more thorougly in U.S. Pat. No. 3,377,236 which is commonly owned with this application and which is incorporated herein by reference.

Drainage foils extend across the width of a papermaking machine and can be over 30 feet long. The first foils were of a one piece design and had their top bearing surface coated with a ceramic or other abrasion resistant material which was usually sprayed on and polished. When the material wore away or was chipped or otherwise damaged, the whole foil had to be removed from the machine and shipped to the manufacturer. This was very time consuming and expensive. Whole extra foils had to be available for use while the other foils were being refitted with abrasion resistant material.

Improved foils were then developed wherein an abrasion resistant insert was fitted on or over the foil body so that only the insert had to be replaced. In some embodiments, the insert could be replaced while the foil body remained in place on the machine. However, the inserts were as long as the foil body itself and they were adhesively secured, screwed or wedged into the foil body, sometimes with dovetail joints, so that they were very difficult to remove. The abrasion resistant insert, or foil blade, comprising the leading face and/or wire contacting top surface of the drainage foil must be securely held to the foil body to prevent vibration or displacement since any such movement would be extremely detrimental to the formation of the web on the wire traveling over the foil.

Today, paper mills still have to store long lengths of brittle foil blade inserts, on which a small defect could ruin the entire blade, and the manner in which they are fitted to the foil body makes replacement a time consuming process.

U.S. Pat. Nos. 3,140,225 and 3,520,775 illustrate the foil type having a removable top cover of abrasion resistant material. U.S. Pat. No. 3,393,124 shows a wear resistant insert adhesively secured to the foil body. U.S. Pat. No. 3,446,702 illustrates a dovetailed insert wedged into the foil body. U.S. Pat. No. 3,619,363 and 3,535,204 illustrate other arrangements I wherein the foil blade is wedged into the foil body.

A common problem with prior foil designs resides in the fact that the foil blade insert material, such as aluminum oxide, and the foil body metal, such .as stainless steel, have different coefficients of thermal expansion. Thus, during cleanup or even during normal operation, changes in the temperature of the water passing over the foil could cause the two materials to expand or contract to such an extent that they would become unsecured, in the case of adhesive bonding, or considerably loosened or gapped if mechanically fastened to the foil body.

SUMMARY OF THE INVENTION This invention mitigates or obviates the aforementioned problems. Instead of a continuous piece of abrasion resistant material permanently, or near permanently, secured to the drainage foil body, this invention provides a plurality of individual foil blade segments aligned end to end along the entire foil body length which are individually and resiliently secured to the foil body in the direction of wire travel. In this manner, expansion of the foil blade relative to the foil body does not produce any looseness or gaps between these parts. Further, by urging the foil blade against the foil body with a spring or springs in the direction of wire travel, there is no danger a segment will fall out when the papermaking machine is shut down for cleaning.

Individual foil blade segments can be replaced on site at the paper mill with relatively little effort at nominal expense since the whole foil blade need not be replaced. Spare foil blade segments can be easily handled, shipped and stored. The cumbersome foil body need not be removed from the machine or sent to the manufacturer to be refitted with abrasion resistant inserts. Accordingly, it is an object of this invention to provide a drainage foil having an abrasion resistant foil blade which is easily and quickly replaceable.

Another object is to provide a drainage foil on which the foil blade is not bolted or permanently or adhesively secured.

Still another object is to provide a drainage foil and a foil blade of simple design which are easy to manufacture and have a minimum of costly finished surfaces and held tolerances.

Still another object is to provide a drainage foil meeting all the aforementioned objectives and on which the abrasion resistant foil blade comprises both the leading edge and top bearing surface of the foil.

A feature of this drainage foil is the use of a foil blade comprising a plurality of similar segments aligned and held end to end for the entire foil length.

Another feature is the provision of a spring retaining each foil blade segment onto the foil body.

Another feature is the positioning of a spring to urge each foil blade segment into seated engagement with the foil body in the direction of wire travel so that these parts will remain together in operating position without adhesives, bolts or mechanical wedges even when the wire is not moving.

These and other objects, features and advantages of the drainage foil and foil blade insert will be recognized as the description of the preferred embodiments is read in conjunction with the attached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of the drainage foil showing the foil blade inserts aligned end to end and held with end springs.

FIG. 2 is a side elevational view through section IIII of the foil in FIG. 1.

FIG. 3 is an enlargement of the foil body.

FIG. 3a is a cross sectional side view of a foil blade insert for mounting in the foil body in FIG. 3.

FIG. 4 is a cross sectional side view of the foil blade insert and foil body in FIGS. 3 and 3a assembled together.

FIG. 5 is a cross sectional side view of another embodiment of a foil blade insert.

FIG. 6a through 6e show cross sectional side views of various prior art configurations of foils.

PREFERRED EMBODIMENTS A drainage foil 10, commonly referred to as a foil, is shown in FIG. 1 as viewed from above on which a plurality of foil blade inserts 12 are mounted in end to end abutting adjacency in groove 14 formed in the top leading corner thereof. The foil body 16, designed to resist deflection, is pivotally mounted in the forming section of a paper making machine about journals 17, shown schematically, so that the top bearing surface 18 of the foil blade is brought into skimming engagement with the wire on which a liquid containing fibers has been deposited by a headbox (not shown). The wire is indicated schematically by arrow 20 traveling in the indicated direction, known as the machine direction (i.e., from the headbox to the reel on a paper making machine). The foil body, groove 14 and abutting foil blade inserts 12, extend transversely to the machine direction.

Adjoining blade inserts 12 are not fastened to one another, but are urged into contact at their butt joints 22 by restraining end springs 25 mounted to the foil body 16 at either end thereof with screws 27 and resiliently biased against the outermost ends 23 of the outermost foil blade inserts 12. Square butt joints 22 are preferred between adjacent foil blade inserts 12 since angled joints have a more pointed corner edge which is more susceptible to chipping and fracture. Also, foil blade inserts having angled end joints, with respect to the direction of wire travel, would require special end foil blade pieces to hold the pointed ends in.

In the two embodiments shown in FIGS. 2 through 5, corresponding items are correspondingly numbered and suffixes a, b will be used to distinguish items in the assembled foils shown in FIGS. 4 and 5. Reference to a numeral in one figure will be understood to be reference also to corresponding numerals in the other figures.

As shown in FIGS. 2 and 3a, the foil blade inserts 12 are shaped in cross section somewhat like the letter T. The top bearing surface 18 and leading underface surface 24 intersect to form leading edge 26. A lower, horizontal lip surface 28, substantially parallel to surface 18, extends inwardly from leading surface 24 and corresponding leading edge surface 9 on the foil body and is supported against a corresponding mounting surface 30 on foil body 16. In similar fashion, a second surface 32 on blade insert 12 extends downwardly from the top bearing surface 18 at an acute angle with both wire 20 traveling in the machine directionand surfaces 19, 28.

Edge a is flush with top surface 19 of foil body 16. Surface 32 is supported on corresponding mounting surface 33 in the groove of foil body 16.

As shown in FIGS. 3 and 4, a notch 48 is formed in the lower portion of groove 14, coextending therewith, substantially vertical with surface 30.

A commercially available continuous wave spring 40 is inserted along the leading wall 38 of notch 48 to urge the foil blade insert 12 into seated engagement with foil body 16 in the machine direction. In a modification, wave spring 40 is made up of individual units aligned with, and corresponding in number to, the foil blade inserts 12 to urge each of them into seated engagement with the foil body.

The lower blade lip surface has

coplanar portions

28, 28 which extend on either side of the downwardly extending portion 46 of foil blade 12a and is supported on a corresponding coplanar portions of mounting surface 30, 30' in groove 14a. The vertical rib portion 46 of blade insert 12, being narrower than notch 48, does not contact the

side walls

38, 49 or bottom wall 36 of notch 48. In the T shaped foil blade embodiment, only

dimensions

43a and 44a are held to close machined tolerances such as about i 0.0005 inch to about 0.00l inch to accurately fit the foil blade into the foil body.

Surfaces

28, 32 on the foil blade insert and surfaces 30, 33 on the foil body are the only surfaces, except the top bearing surface 18 and underface surface 24 on the foil blade, which need be made smooth or finished. Accordingly, surfaces 28, 32, 30, 33 are referred to as finished mounting surfaces. None of the surfaces on downwardly extending rib portion 46, including rib bottom surface 34, or notch 48 have to be finished in any particular manner.

Surface 19 is substantially coplanar with aligned top bearing surfaces 18 of foil blade inserts 12. It can be seen that edges 26 and surfaces 18, 24 are aligned longitudinally along the foil body length extendingtransversely across the machine. Usually, the leading edge portion of surface 18 is beveled or arcuately turned downwardly slightly to form a small (i.e. 05) acute angle 21 with the plane of the oncoming wire 20. In the case of an arcuately curved surface, the angle 21 would be measured between the plane of the wire and a plane tangent to the surface at the leading edge. In operation, top bearing surface 18 is brought into contact with wire 20 and the foil body may be rotated about supporting journals 17 such that foil body top surface 19 may diverge from the plane of the wire 20 at a small angle (i.e., about 05), depending on the position of leading edge 26. Liquid is skimmed off the underside of wire 20 by face surface 24 and a slight negative pressure differential is formed in the gap between wire 20 and surface 19 which induces liquid to flow therebetween and out of the wire.

The foil blade insert 12b in FIG. 5 has the general cross sectional area shape of a parallelogram. A notch 50 angles upwardly and forwardly, in the direction of wire 20b travel, from the bottom surface 28b of foil blade 12b.

Surface

28b, 28b has coplanar portions extending on either side of notch 50 to bear on corresponding portions of

surface

30b, 30b. A communicating notch 48b is in the bottom of groove 14b and a L- shaped spring 52, one for each segment of blade insert 12b, is positioned in these notches to urge foil blade 12b into seated engagement with foil body 16b in the direction of wire 20b travel. As in the T shaped embodiment, only dimensions43b and 44b are held to close tolerances to ensure an accurate fit with foil body 16b and coplanar alignment between surfaces 18b and 19b along flush edge 45b. Also, as with the T-shaped insert, surfaces 28b, 32b, 30b, 33b, are referred to as finished mounting surfaces.

In each of the embodiments shown in FIGS. 3, 4 and 5,

grooves

14, 14a, 14b and

notches

48, 48b extend continuously for the foil length which, in operating position, is transverse to the machine direction of wire travel 20. Foil blade inserts 12 are provided in two standard lengths of IO and 12 inches which allows the foil blade to be built up to any length within two inches. Similarly, wave springs 40, 40a and right angle spring 52 coextend in the grooves or notches in which they are positioned as they urge the foil blade inserts into operating engagement with the foil body. There are no press or interference fits between the foil blade inserts and the foil body since only springs are used to mount the foil blades to the foil body. To replace one or all of the foil blade inserts, one or both of the end springs 25 are removed and the foil blade inserts are slid into or out of position. No unscrewing, pulling dovetailed or force fit wedges or breaking adhesive bonds is necessary.

When the papermaking machine is in operation and the wire is moving in direction 20, the force of

springs

40, 40a, 52 is complimented by the force component of the wire contacting the top bearing surfaces 18, to drive the foil blade surfaces 28, 32 into the wedge formed between mounting

surfaces

30, 33 on the foil body. In each of the embodiments, back face 35 is formed on blade insert 12 so that a gap 39 in groove 14 is formed between the corresponding inner face 37 on the foil body and blade insert, thereby obviating the necessity for finishing these faces to expensive machined tolerances. When the machine is shut down for cleaning or repairs, springs 40, 40a, 52 hold the blade foil elements in position against the foil body, and end springs 25 hold the butt joints of the adjoining foil blade segments together against one another. Since no

spring

40, 40a, 52 or foil blade segments are fixedly secured to one another or to the foil body, any change in length due to relative thermal expansion or contraction between foil blades and foil body will have no effect on the security with which these parts are positioned in place. The foil blade inserts are secured to the foil body solely with springs. It should be noted that, with respect to the embodiments shown in FIGS. 4 and 5,

notches

48, 48b and 50 need not be held to any costly machined tolerances since they only provide means to mount the springs which attach the foil blade segments to the foil body and do not serve to align these parts.

Various abrasion resistant materials, such as aluminum oxide, chromium oxide, tungsten carbide and silicon carbide have been used for the foil blade inserts and, undoubtedly, other materials will also function satisfactorily. Aluminum oxide is the preferred material for the foil blade inserts. The foil bodies are generally made of stainless steel to resist corrosion, although other corrosion resistant materials, such as plastic, can be used.

Some prior art embodiments of foils and the methods used to mount them are shown in FIGS. 6a-6e. FIG. 6 shows what is believed to be the first of the modern foils wherein a stainless steel foil 54 is coated with an abrasion resistant coating 57 on its top bearing surface 58. Foil 54 was as long as the foil body 55 on which it was mounted and had to be removed and returned to the coating manufacturer when coating 57 was worn or damaged. Face edge 56 was not coated with an abrasion resistant material.

In FIG. 6b, a dovetailed, abrasion resistant insert 60 is press fit into the foil body 54b at a location where its top bearing surface 58b contacted the wire traveling in direction 20b. This did not provide sufficient wear resistance for the leading edge so the foil blade insert shown in FIG. 6c was developed which had the face edge 56c and top bearing surface 58c of abrasion resistant material. If this foil blade is screwed into the body, it is very difficult to remove. If it is adhesively secured and loosens, it can fall out of the foil body during cleanup when the machine is stopped.

FIG. 6d shows a foil similar to that of FIG. 6a except the entire top 58a is made of abrasion resistant material in an attempt to eliminate problems in mounting a foil blade into the foil body. This was far more costly than a similar insert made of abrasion resistant material.

FIG. 62 illustrates a foil having a dovetailed blade wherein a costly and complicated movable mechanical wedge apparatus 62 locks the foil blade 586 into position against the direction of wire travel 2le. Thus, any looseness in the wedge apparatus 62 will allow the blade to move and, possibly, vibrate in operation which is, of course, extremely detrimental to good paper formation.

The common problem with prior art foils is that they either require the whole foil to be removed from the machine for repair or the abrasion resistant insert is difficult to remove. In the case of dovetailed inserts, the foil blade inserts are very difficult to remove for replacement. Anyone familiar with dovetailed joints can well appreciate the difficulty in separating two pieces 20 to 30 feet long which are snugly fit together.

Thus, it will be seen that an invention has been set forth which incorporates the features and achieves the objectives desired. It should be understood that while the specific embodiment referred to a foil on a papermaking machine, the foil could operate on other web forming machines, such as non-woven fabrics, with equal efficiency. Also while the position of the foil relative to the wire would not change significantly, the foil could operate as well against a wire moving at an angle to a horizontal plane or even vertically. Further, while no material has been referred to in conjunction with the wire, it is understood the wire could be metallic, plastic or made of synthetic fibers.

We claim:

1. An elongated drainage foil for removing liquid from a contiguous drainage wire traveling in a given direction on a web making machine, the foil extending transversely to the direction of wire travel when in operating position, comprising:

a. a body member having top and leading edge surfaces extending along the length thereof and having a coextending groove in the intersection of said top and leading edge surfaces, said groove having just two mounting surfaces which are inclined one to the other;

b. a foil blade insert member polyhedron disposed within said groove having abrasion resistant leading and top bearing surface faces forming a leading edge toward the oncoming traveling wire direction, said top bearing surface face being flush with said top surface and positionable against the wire, and

having just two inclined mounting surfaces engaged with respective ones of said groove mounting surfaces;

c. resilient means interposed between said body and foil blade members within the groove urging said foil blade member against said body member in the direction of wire travel, thus cooperating with the two mounting surfaces to provide the sole means of attaching the foil blade insert member to the body member.

2. A drainage foil as set forth in claim 1, wherein:

said foil blade insert member comprises at least two similar segmented parts aligned end to end in said groove transversely to the direction of wire travel; and

restraining means mounted on said body member and bearing against the outermost ends of said foil blade member parts, thereby maintaining abutting contact between adjoining ends thereof.

3. The drainage foil as set forth in claim 2, wherein:

said adjoining ends of adjacent foil blade member parts have butt joints.

4. The drainage foil as set forth in claim 2, wherein:

said resilient means comprises individual units, each of which bears against corresponding ones of said foil blade member parts.

5. The drainage foil as set forth in claim 2, wherein:

the leading portion of said top bearing surface turns downwardly at a small acute angle with respect to the plane of the wire in the oncoming direction of its travel.

6. The drainage foil as set forth in claim 2, wherein:

the cross section of the foil blade member polyhedron is in the shape of a parallelogram when viewed through a plane normal to its leading edge and top surface;

one of said foil blade member inclined surfaces is substantially parallel with said top bearing surface face;

another of said foil blade member inclined surfaces is inclined at an acute angle with the wire in its direction of travel such that the force of the wire urges the foil blade member into wedging engagement with the body member;

a notch is in said body member groove coextending therewith;

said foil blade member includes a corresponding coextending notch in communication with said body member notch;

said resilient means comprises a spring mounted within both said notches and coextending therealong.

7. The drainage foil as set forth in claim 6, wherein:

8. The drainage foil as set forth in claim 6, wherein:

9. The drainage foil as set forth in claim 2, wherein:

the foil blade member is in the general shape of a T,

having a substantially horizontal and vertical portions, the top of which horizontal portion comprises the top bearing surface;

one of the body member mounting surfaces is substantially parallel with said top bearing surface face;

a notch is in said body member groove coextending therewith;

the vertical portion of said foil blade member is positioned within said notch such that a gap is formed between its leading edge and the respective leading edge of said notch, and the bottom surface of said horizontal portion is in bearing engagement with one of the body member mounting surfaces;

the resilient means comprises a wave spring positioned within said gap, coextending therein.

10. The drainage foil as set forth in claim 9, wherein:

the horizontal portion has a second surface having an 'upper edge flush with said body member upper surface, and extends downwardly from said edge at an acute angle with the wire in its direction of travel and engages another corresponding mounting surface in said body member. 11. The drainage foil as set forth in claim 9, wherein: the leading portion of said top bearing surface turns downwardly at a small acute angle with respect to the plain of the wire in the oncoming direction of its travel.

Claims

1. An elongated drainage foil for removing liquid from a contiguous drainage wire traveling in a given direction on a web making machine, the foil extending transversely to the direction of wire travel when in operating position, comprising: a. a body member having top and leading edge surfaces extending along the length thereof and having a coextending groove in the intersection of said top and leading edge surfaces, said groove having just two mounting surfaces which are inclined one to the other; b. a foil blade insert member polyhedron disposed within said groove having abrasion resistant leading and top bearing surface faces forming a leading edge toward the oncoming traveling wire direction, said top bearing surface face being flush with said top surface and positionable against the wire, and having just two inclined mounting surfaces engaged with respective ones of said groove mounting surfaces; c. resilient means interposed between said body and foil blade members within the groove urging said foil blade member against said body member in the direction of wire travel, thus cooperating with the two mounting surfaces to provide the sole means of attaching the foil blade insert member to the body member.

2. A drainage foil as set forth in claim 1, wherein: said foil blade insert member comprises at least two similar segmented parts aligned end to end in said groove transversely to the direction of wire travel; and restraining means mounted on said body member and bearing against the outermost ends of said foil blade member parts, thereby maintaining abutting contact between adjoining ends thereof.

3. The drainage foil as set forth in claim 2, wherein: said adjoining ends of adjacent foil blade member parts have butt joints.

4. The drainage foil as set forth in claim 2, wherein: said resilient means comprises individual units, each of which bears against corresponding ones of said foil blade member parts.

5. The drainage foil as set forth in claim 2, wherein: the leading portion of said top bearing surface turns downwardly at a small acute angle with respect to the plane of the wire in the oncoming direction of its travel.

6. The drainage foil as set forth in claim 2, wherein: the cross section of the foil blade member polyhedron is in the shape of a parallelogram when viewed through a plane normal to its leading edge and top surface; one of said foil blade member inclined surfaces is substantially parallel with said top bearing surface face; another of said foil blade membeR inclined surfaces is inclined at an acute angle with the wire in its direction of travel such that the force of the wire urges the foil blade member into wedging engagement with the body member; a notch is in said body member groove coextending therewith; said foil blade member includes a corresponding coextending notch in communication with said body member notch; said resilient means comprises a spring mounted within both said notches and coextending therealong.

7. The drainage foil as set forth in claim 6, wherein: said resilient means comprises individual units, each of which bears against corresponding ones of said foil blade member parts.

8. The drainage foil as set forth in claim 6, wherein: the leading portion of said top bearing surface turns downwardly at a small acute angle with respect to the plane of the wire in the oncoming direction of its travel.

9. The drainage foil as set forth in claim 2, wherein: the foil blade member is in the general shape of a T, having a substantially horizontal and vertical portions, the top of which horizontal portion comprises the top bearing surface; one of the body member mounting surfaces is substantially parallel with said top bearing surface face; a notch is in said body member groove coextending therewith; the vertical portion of said foil blade member is positioned within said notch such that a gap is formed between its leading edge and the respective leading edge of said notch, and the bottom surface of said horizontal portion is in bearing engagement with one of the body member mounting surfaces; the resilient means comprises a wave spring positioned within said gap, coextending therein.

10. The drainage foil as set forth in claim 9, wherein: the horizontal portion has a second surface having an upper edge flush with said body member upper surface, and extends downwardly from said edge at an acute angle with the wire in its direction of travel and engages another corresponding mounting surface in said body member.