US2658429A

US2658429A - Paperboard forming machine

Info

Publication number: US2658429A
Application number: US137375A
Authority: US
Inventors: Bernard A Malkin
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-01-07
Filing date: 1950-01-07
Publication date: 1953-11-10
Anticipated expiration: 1970-11-10

Description

Nov. 10, 1953 B. A. MALKIN 2,658,429

PAPERBOARD FORMING MACHINE Filed Jan. 7, 195.0 4 Sheets-Sheet l Yi 52H H H1 H Mfg-07W@ 5 NOV. 10, 1953 B. A. MALKIN PAPERBOARD FORMING MACHINE 4 Sheets-Shee 2 Filed Jan` 7, 1950 mmmvv lll. r/IA Illa e4 s www NOV. 10, 1953 |3 A, MALKlN 2,658,429

PAPERBOARD FORMING MACHINE Filed Jan. '7, 1950 4 Sheets-Sheet 5 Nmf, 10, 1953 Filed Jan. '7, 1950 2@ d 7 4406 fio :Hi

FICL

4 Sheets-Sheet 4 Patented Nov. 10, 1953 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to improvements in cylinder-mold machines employed in the pulp and paper industry for the manufacture of paper and paper pulp products.

The salient feature of the invention consists in the provision of an improved type of cylindermold on which the stock is formed into a sheet of desired thickness.

As compared with conventional cylinder-molds, one important advantage of the improved cylinder-rnold provided in accordance with the present invention is that it enables thin sheets of excellent formation to be produced from thicker stock than has heretofore been considered feasible and thus reduces the oost of production by reducing the amount of dilutionwater and power required.

Another advantage of the improved cylindermold is that it may be used in a variety of ways to provide a wide range of different types of installations designedto meet different operating conditions or the requirements of different mills. It may be used with or without suction boxes and with or without a vat. For example, when one or more suction boxes are arranged within the improved cylinder-mold, the vat may be dispensed with and replaced by various other means for feeding the stock to the forming surface of the mold. The improved mold, either with or without suction boxes arranged therein, may also be used to advantage in a conventional vat as a replacement for the conventional type of cylinder-mold. When the improved mold, without suction boxes, is installed in a conventional vat as a replacement for the conventional cylindermold the improved mold may be immersed in stock supplied to the Vat circle in the conventional manner. In this case the improved mold provides a more rigid sheet-forming surface than the conventional mold and may, under certain circumstances, haveV other advantages. When the improved mold, with one or more suction boxes arranged therein, is installed in a conventional vat as a replacement for the conventional mold, the stock may be supplied to the vat circle and picked up by the mold in the usual manner. ln this case the improved mold provides a desirable rigid sheet-forming surface and the effective suction applied through the suction boxes may be varied in accordance with various factors, such as variations in the nature and density of the stock, to control the thickness, formation and other characteristics of the sheet. Alternately, when the improved mold, with one or more suction boxes arranged therein, is installed in a conventional vat as a replacementjor the conventional mold, the stock may be fed to the forming surface of the mold independently of the vat circle. This may be accomplished, for example, by forcing the stock through an approach passage to an apron plate positioned so that the stock ilows over the apron plate onto an upper portion of the cylinder-mold which is travelling over the suction box or boxes arranged within the mold. This latter arrangement, due to the provision of the suction box or boxes and to the fact that the improved mold alfords a better type of forming surface than the conventional mold, provides an improved cylinder mold machine which is capable of handling stock at higher densities and feed velocities than is possible with conventional types of cylinder-mold machines. It also lends itself to the use of improved means for controlling the flow and distribution of the stock delivered to the forming surface of the mold.

Proceeding now to a more detailed description of the invention reference will be had to the accompanying drawings in which- Fig. 1 is a top plan View of an apparatus embodying my invention.

Fig. 2 is a vertical sectional view through the apparatus shown in Fig. l.

Fig. 3 is an elevational view of the front end of the apparatus.

Fig. l is a transverse sectional View of the apparatus taken along the lines 4--4 of Fig. 2.

Fig. 5 is an enlarged fragmentary view of one end of the cylinder mold.

Fig. 6 is an enlarged detail vieW of a fragment of the outer surface of the roll shown in Fig. 5.

Fig. 7 is a sectional view taken along the lines 'lof Fig. 6.

Fig. 8 is an enlarged detail view taken between the lines 8 8 of Fig. 5.

Fig. 9 is a detail View in elevation of the gate assembly.

Referring more particularly to the drawings, 5 generally indicates a vat including a vat circle ia `which may be of a conventional construction and 6 a cylinder mold having outer bearing surface bands 'l adjacent its front and rear ends. The mold is supported for rotation in the vat by the bands 'i on bearings 8 carried by front and rear ends 9 and iii of the vat. An external gear I l secured about the rear end of the mold adjacent rear bearin-g band l meshes with a pinion i2 mounted on the rear end lil of the vat. The pinion is power driven by a motor (not shown) suitably coupled thereto, as indicated at lli, for

` rotation of the mold through gear i I.

Stock is supplied under pressure from a source (not shown) to an approach passage I5 through a supply pipe I6. An adjustable flow deflector I1 in the upper section of approach passage I5 regulates and directs the flow of stock to an apron I8 which carries the stock to the surface of the cylinder mold. Apron I9 is confined at its ends by pond plates I9a. An adjustable gate assembly regulatesthe stock flow over the apron and onto the mold. Conventional outside deckles 2| define the maximum Width of the sheet on the mold surface.

The cylinder mold 6 comprises a hollow shell provided with openings between longitudinally extending ribs 26 on the outerisunface over which a wire covering, generally indicated @1321, is placed- The details of the 'openings 'and the arrangement of the wire covering are hereinafter more fully described. The cylinder mold is arrangs@ ici n-.astma with an endless. felt. which Vpasses..*attinenti tn s. incisi ande .s911013 sell 2.9 nivctally incnntcd. sin -braslftt 39- Ths. niessnre cf @Quan 1501i 2.5i 0n @slt 3% causes the. ifiit. t0 -picis un .the innesti sheet 0f. sind; etres the mold- AThe nin is disposed in seth irelnticn te the tss nf. the, crlinnernieidtnat, the felt.. contacts with. the. mold. unser Bresser@ and Aniclgs un the farmed sheet `frein the .mold after itfhaspassed-over the mold. ennscillatine shawer 'pipe .3l is. arrangedacrcss the machine sn. that its spray 'washes ythe `cuter snr-face Qithe mold- A second .showery pine 3fm with adjustable Yangl@ 0f sprayis arranged to. spray the underside 0f the apron t0. Yprevi-:nt any stock -hreaccumulating thereon. Bassages 3.2 atthe-ends of the mold connect with white water collection chambers 32a at the ends. of the vat which are drained by any `suitable'eross pipe 3.3. Excess white water is also drained directly from vat circle 5a, if desired, through conventional valves 3.4 communicating 4with the cross pipe 33. 'Gross pipe=33 is drained through a centralpassage 33a.

rA suctionlboxSS having wheels 36 mounted at the rear end is slidably inserted A`into; mold v6 through'o'ne end thereof. The suction box is provided with two separate suction kcompartments l! and 38 so `that the amountof 'vacuum may be varied as required. The upper-'ends of comipartments-Sandare provided with outer longitudinally. extending deckle holders 40 and =4| which have'decklelpackings 42 and "3 :mounted therein for confining the breadth 'of the suction opening. An intermediate longitudinally extendin'g decltrleholderl y'44 having a deoklepacking 45 mounted therein, 'separates the two compartments. End deckle holders 46 hav-ing- 'deckle .fpa'ckings 541 xnounted therein, 'extend arouately across the upper end ofthe compartments 4for 'confln'ingthe' length of th'esuctio'n opening.

Ilhe suction box is provided with front and "rear sedientos; extensions@ ands l respectively,

tsrsnctinn bcn'sstensions '50. and. 55'! Thss'sps "arsresgsctivcly Y'supported by the frcnt'anid rear ends s anni@ if thirst:@inspanningen- 'Lifting rines. 59. 'and '6.9 attire tndf. sans 55. sind' trpfs'vlise. mesniny'wnish nie nismay nennt.-

ffil'ed.- .Suction ben 351s rntatabls 'relative tegens `55 'and 5t,- Tne bins. is sessies asainstflaterel siss1smtnt in? s sneiillnsr'?. Qn rsr siitsnsien 51 which is tetten. against-Ons siqssf; fixed cap 56 and a worm and quadrant assembly 65.

the worm being carried by the cap and the quad= rant being secured about the periphery of extension 5I in butting engagementwiththeremaining side of said cap. The suction box may be rotated in order to obtain the correct operating position for various products. Rotation is effect-- ed through the worm and quadrant assembly 65;

.Show PP@ 1. 0 @Xfld lengtlWlS of the Suc tion box fand is :suitably secured to its outer sur= face by brackets 1| so that, when the box is in its position shown in Fig. 4, the cylinder mold will be. sprayed. from its inner surface to the outs Vside yso as to Vclean the cylinder mold prior to its passage over the suction surface of the box. A

lead pipe 12 extending through closure 53 of rear suction box extension 5I is connected to one end shower pipe 1D and at its outer end to a suitable source of water -supply (not shown). A nipple QQnnsetiQn. l5. is .ccnnsctcsi at. one .end thngn opening, 11. tnt side wall of. reni tension. 5.1 to tne'snstinn nempsrtrnsnt 3.8. Nipple 15 i's connected at its 'outer end through flexible nos@ member if! t0. a vacuum. snmp (net, snewni- Asimilar tonneetien is made. between snstien csinpartlnent @i andar-annum pump. (not shawn) through opening 18 in extension 5l. The flexibis nnss members. permit. rotation. cf the. suction bsx Without. disscnnsttins the va'tnnrn lines- Frsn't. section bnx'cxtsnsion 51.1 is Previas@ with 'a snai nine elbow 8l. having. separaten Qceninss 8.2 and Lt5 communicating the ,suction cantantmsnts. 3.1. and sa. respectively thrash suitable passages in this sid@ Wall sf. extensicn50- fer distiinise 0f the. White Water trom the siicticn bsx- Elbovv'l is suitably arranged rabout front extensisn 5l? to nnrniit retntien ci said tstensisn'se'lstirs te the clbow- Sealing rines 85. in Channels 8.6 about. the inner surfnet' Qf the elbow provide scaling nisnns. between the 'adict-tnt surfaces.. 0f the einen and attend. aisne th side enses sf the slltinwt Qvsifiew pines 8.8 are ccnvntisnallrf sr- .rnnsesi te cQntrQl-ths. 1st/n1 Qt the White rattio in tine vat. when such. Central is. desirable.-

Tiie artisans Passes@ .5 is snnnssited. at 'its .naiss traine. Sissi sunny pip'ls an@ is arranged et .sans side @fthe rat.. 54 The. inner side wat? 92 ef the schwach passage. is dirette@ inwnrsllyftcnani. enter sie@ Wall t5' frein the ts cnn/'ids restricted. threat '94. inY the linnn.' ssctin with the, inner.- wall tanins outw'srdy fnnn the rstsiited tnieattcinstf the .forward end si sieren la Tnsnefisttcr Il is. sinnsatn. in ssstiiiiy tannins nein. tisser scanned. snc .95 to its lower rennes@ @ne 9t- 'ine detector is. arranged lens-@wisest thsannseacn passage with its lower @ne it nneiestins ttc-are the. restricted threat an@ is canned. at. its nsis by -adinstins ,insenasnninrisinsbeanins blacks. t1. arranges tsr vertical. angine increment in snide Ait acrimed cn ine rat end walls wnsl and sans 9i! threaded in tearing tlsslss. il nrqvincs the vertical. adiustnicnt. A qnndisnt it@ c. sind bis elses @land csnnested to the lswernc @nectar U permits. .nsnlar adjustment. cf saine- Witn this vsii"-.reingeteilt the sltcsk. new to, the agitan. ami-thence to the cilinder incid, ina-y he snitblr res-nit@ Without. altering the stock ,d This. is. particularly desirable whenI the ri nutystnppingytne fnnnine .operi-men.. and, in East; .such resnlationis'lncre effectiveA during cp- -eratian fer the. neasnntnat. the results will appear as. the. shcetis, draw-n @ifi the. mold..

The adjustable gate assembly 20 is arranged lengthwise of the vat over the apron |9 and is supported for vertical adjustment by wheel and screw members |02 at opposite ends. The screw portion of member |02 is threaded through the gate so that rotation of the screw causes the gate to move vertically toward or away from the upper surface of the apron to regulate the flow of stock over the apron to the cylinder mold. A pair of adjustment plates |03 are pivotally secured at their inner ends, as indicated at |04, to the centre of gate 20. The outer ends of plates |03 are secured for adjustment to screws |05 carried by the outer ends of the gate. It frequently happens that the iibres in the stock iiow become more concentrated at the outer edges, with a resulting unevenness in the sheet formed thereby. By adjusting the outer ends of plates |03 through the medium of screws |05, any desired quantity of the bres may be directed toward the centre prior to deposit on the surface of the cylinder mold.

As previously pointed out the cylinder mold shell is provided with openings between longitudinally extending ribs 26 on the outer surface. The outer surfaces of ribs 26 are spirally grooved, as indicated at |06, to permit spiral winding of a wire |01 forming the base of wire covering 21, about the circumference of the mold at approximately 1/4" pitch. The wire is soldered or otherwise secured in grooves |06 at intervals to prevent unwinding or other displacement of the wire from the grooves. Inner and outer wire mesh |08 and |09 are then successively placed over the wire coil |01. The ends of the outer wire mesh are lapped over end rings |0 and secured by clamping rings which are butted against rings ||0 and fastened in place by suitable bolts ||2 or other suitable means. Rings |0 also serve to close the ends of the lengthwise drainage channels ||4 formed between ribs 26.

The openings 25 in the shell are preferably arranged in staggered series along the alternate channels I4 with the bore of each opening in offset relation to the radius of the shell for drainage of the channels. The offset is such that the bottom of each opening will be slightly in advance of the upper end. The particular advantage in offsetting the openings is that greater quantities of Water can be drawn off from the channels. This is caused by the fact that the water passing through the mesh from the stock tends to follow the direction of rotation rather than to flow at right angles to the direction of rotation. The angular disposition of the suction openings also serves to increase the eiciency in the wash of the cylinder by shower pipe '|0.

It has been indicated heretofore, that my improved cylinder-mold may be employed in a variety of ways to provide a Wide range of different types of installations designed to meet different operating conditions or other requirements. It may also be used with or without suction boxes and with or without a vat. In the appended drawings, I have shown, for illustrative purposes, a board forming machine including my improved cylinder-mold mounted in a vat assembly of a conventional type, a suction box assembly removably fitted in the ends of the vat and extending through the mold shell, and a stock delivery assembly attached to the vat including an approach passage, gate assembly and apron.

In the particular adaptation of my improved cylinder mold to the conventional vat assembly, as shown in the drawings, substantially all of the component elements of the board forming machine bear a cooperative relationship' with one another. Certain of the elements, however, are not necessarily employed in the prescribed manner for which they were originally intended. Also certain elements may be removed, if desired, without impairing the e'iciency of the board forming operation,

To operate the board machine, suction box 35 is adjusted in the mold shell so that the outer deckle of suction compartment 33 lies opposite or relatively close to the plane of the apron I9. The degree of closeness is dependent on such contributing factors as the stock flow, the stock consistency, the speed at which the mold is driven, the vacuum applied to the suction box and/or the type of sheet required. The head of the incoming stock through the approach passage |5 is controlled adjacent the restricted throat S4 by the deliector I7 which is vertically and tiltably adjustable by the wheel and screw mechanism and by the quadrant |60 respectively to regulate the flow of stock to the gate assembly 20, which, in turn, distributes the flow over the apron IS to the revolving cylinder mold 6. The suction in compartment 3B tends to lay the stock libres flatly on the wire mesh and at the same time to draw oli a substantial amount of the water in the stock which is drawn into channels Ht and thence through openings 25 in the mold. The angular disposition of openings 25 in relation to the rotation of the mold and the direction of carry of the stock tends to accelerate the withdrawal of the water through the openings in the mold since it minimizes any baffling eiiect against the walls of the opening which would be encountered if the openings were arranged radially of the mold. The withdrawal of the water from the fibres on the screen is continued as they are carried over the second suction compartment 3l. The thus formed sheet is then lifted from the mold by pressure contact of felt 28 brought about by the action of couch roll 29 thereagainst.

Although I have shown a dual compartment suction box, in many instances a single compartment suction box will serve the needs. However, I rind that the dual type is more universal since it can be regulated to provide uniform suction.

throughout or to apply high and low vacuum toe either compartment at varying degrees to meet, As a further alternative the suction box may be divided into any suitablespecific requirements.

ing of the deflector permits different positions oi adjustment in the passage including one extreme position in which all the stock is caused to iiow' in an inclined direction over one side of the flow' deiiector toward the gate, a second extreme position in which all oi the stock is caused to ow in an oppositely inclined direction over the opposite side of the 'low deflector toward said gate, and various intermediate positions in which the iiow deflector serves to divide the flow of stock toward the gate 2h into two streams of varying quantities flowing over opposite sides of the flow deiiector. With this adjustable flow deflector a ow of stock can be delivered through the approach passage to meet any specification and can be modified at all times to compensate for any 7 variations. in. the stock. supply to the approach Rasge..

Gate 0 raised or lowered by screw, .membells. tu to. regulate. the-density of: the stock How trom; the app-roach passage .to- -be .distributed Vover apron l-Q- 1,5 des-'med distribution may be further regulated by means of adiiustmsnt plates |03 carried by gate 2,0, by raising or lowering said plates at their outer ends,l inthe manner vheretofore described, to distribute the nbres in the stock more evenly across the apron beforeA it reaches the mold surface.

Showers 3|, l0 andl 3|.a, are strategically placed to wash the outer and inner surface of the mold Vand the under side of apron I9 to clear anystock libres passing beyond the exposed surface .or the suction box compartments.

the particular application of the invention aboyedescribed, the vat circle .5a ,catches the `Wash and any excess water carrying it to the4 c ollection chambers 32a through valve openings 34, where it is discharged through cross pipe 33.4 The conventional overilow pipes 88 serve no useful purpose in this application and could, therefore, be removedirnproved cylinder mold in itszapplication as ai suction type board forming machinemay be usedv ina conventional vat without my stock delivery and' apronassembly.` The stock isconven- .tionallysupplied to the vat circle immer-sing the mold therein, and is picked up4 by the revolving mold, in the* usual manner. In this event; the overflow pipes 88;E serve to maintain the levelA in the Av atcircle in a` conventional manner, the improved moldj providesfa, rigid sheet formingfsurface andthe effective suction-.applied through the` suction box compartments may` be varied in accordance with various factors such as variations inthe nature andV density'. of the stock, to

controlthe thickness, formation and other characteristics of theisheet.

In anotherk application of myimproved cylinder mold as a suction type board machinathe vat may be dispensedA with, mounting thev mold for rotation on suitable frameswith one or more suctionboxesarranged within the mold. Various .means for feeding stock-to the forming surface .of the mold; mayV be employed, such asl the. approach passage hereinabove described and an apron havingv pond plates at either side to carry the stock onto an upper portion of` the moldwhich is travelling over the suction boxor; boxeswithin the mold, This arrangement, due tothe provision of the suction box or boxes and tothe fact that the improvedA mold affords a better type .of forming surface thanthe-A Conventional mold,

provides an improved .cylinder-mold-machine which is capable ofY .handling stock at, higher densities and feed velocities than is. possible with conventional types of cylinder-mold. machines. The arrangement, when employing my particular stock feed assembly, also lends itself toltheuse of the various previously. outlinedy improvedi devices for controlling the. flow and distribution of the stock delivered togthe forming.v surf-ace of the mold.

A still further application of my. cylinder-mold may be as a replacement for the conventional non-suction type4 of: cylinder-mold. .When the improved mold, without suction boxes,` is. installed in the-vat asy a replacement for the`A conventional mold, the improved moldJ maybe ,immersed in stock supplied to the vatk circlelin the conventionalmanner. In such a case myim- `proved mold provides a more rigid=.sheet.forming 8 surface..v The, channels l 1 4. beneath .the raised mesh and the angularly disposed opennss in the mold surface provide rapid drainage of the water from the-'fibres on the mold surface.

Alternatively,y the stock may be directly fed' to vthe forming surface of the mold independently .of .the vat, circle. This may be accomplished, for

example, through the medium of' my stock feed assembly,y delivering the stock through the appreach passage, over the apron and onto the upper portion `of the mold surface. The vat circle Aserves `to catch allofy the drained water and ex- Goss. stock which is carried away through the ends of the mold as well as through suitable drainage openings in the vat circle.

I claimt:

1.r A. paper making machine of the character described comprising; a foraminous cylindermold', ya horizontal apron having its inner edge extending horizontally along and positioned close tothe ascending side of the cylinder-mold so that stock deliveredover said apron to the cylinder-moldis formed into a web or sheet on the portion of the cylinder-mold which is travelling upwardly from said apron, pond plates extending upwardly from said apron and serving to laterally conne thestream of stock delivered to thecylinder-mold over said apron and a suction box arranged in the cylinder-mold so that the suction area or areas of said suction boxface .toward and underlie that portion of the cylinderinold which lis travelling upwardly from the 3911011- 2. A paper making machine *as set `forth in claim-1, including means mounting said suction box for rotation about a horizontal axis and adriusting means connected to said suction box for rotatingthe latter about said axis to various positions of angular adjustmentwith reference to said cylinder-mold and said apron.

3. `A. paper making machine as setforth in clairnal, in which the cylinder-.mold includes a metal shell provided with rows of drainage openings extending from the inner` to the outer vsur- `'and `extending between said pond plates in spaced relation'to the adjacent ascending side of the cylinder-mold, and slice plate adjusting means supporting-said slice plate and operable -to vadjust the slice plate to and from the upper surface of said-apron.

-5. A-papermaking-machine as setforth in claim 1 comprising a main vertically disposed slice plate positioned/directly above theapron and extending between said pond plates in spaced relation .to the adjacent ascending Side of .the cylinder-mold, slice. plate adjusting means supporting said slice plate andoperable to ad- --iust :theslice lplate to and trom the upper sur- :face of said, apron, apairof auxiliary slice plates having 'their inner ends pivotally secured to the vcentral portion of the main slice plateadjacent the lower.' edgeof the latter and adjusting means connected between said main slice plate and the outer. ends of the auxiliary slice plates and op- @roble to swing the auxiliary slice plates down- Ynardly.to .inclined positions projecting below the lower edge ofthe main slice plate.

6. A paper making machine as set forth in claim l, including a vertical approach passage having a stock inlet at its lower end through which stock is delivered to said passage and having a stock outlet at the upper end through which stock passes horizontally from said passage over said apron and is delivered radially to that portion of the cylinder-mold which is travelling upwardly from said apron, said approach passage being bounded at the outer side by a straight vertical outer side wall extending above the apron and being bounded at the inner side by an inner side wall comprising relatively inclined upper and lower wall sections, said upper wall section inclining downwardly and outwardly from the outer edge of the apron toward the outer side wall of said approach passage to provide the latter with a constricted throat located below the apron, said lower wall section inclining upwardly and outwardly toward said outer wall section and having its upper end joined to said upper wall section at said constricted throat, and a flow defiecting and throttling member arranged in the approach passage above but immediately adjacent said constricted throat, and means mounting said now deiecting and throttling member for swinging movement about a horizontal axis lying parallel with the outer Wall of said approach passage and passing through the flow deilecting and throttling member intermediate the upper and lower edges of said member.

7. A paper making machine comprising a foraminous cylinder-mold mounted to rotate about a central horizontal axis, means for rotating said cylinder-mold, a horizontal apron having its inner edge positioned close to and extending along the ascending side of the cylinder-mold so that stock delivered over said apron to the cylinder-mold is formed into a web or sheet on the portion of the cylinder-mold which is travelling upwardly from said apron, pond plates eX- tending upwardly from said apron and serving to laterally confine the stream of stock delivered over the apron to said cylinder-mold and a vertical approach passage having a stock inlet at the lower end through which stock is delievered to said passage and having a stock outlet at the upper end through which stock is delivered over said apron and directed radially against the portion of the cylinder-mold which is travelling upwardly from said apron, said approach passage having the greater portion of its length disposed below said apron and being shaped to provide a now passage gradually decreasing in area from the stock inlet to a restricted throat portion located beyond the apron and then gradually increasing in area from said throat portion toward the outer edge of said apron, and a pivotally mounted flow deflector located in said approach passage above but immediately adjacent the constricted throat portion of said passage.

8. A paper making machine as set forth in claim 7, including a vertically disposed slice plate positioned directly above the apron and extending between said pond plates and slice plate adjusting means supporting said slice plate and operable to move said slice plate in a vertical direction toward and away from the upper surface of the apron.

BERNARD A. MALKIN.

References Cited in the Ille of this patent UNITED STATES PATENTS Number Name Date 1,627,882 Berry May 10, 1927 1,714,238 Pope May 21, 1929 1,937,426 Formaini Nov. 28, 1933 1,964,291 Kutter June 26, 1934 2,006,519 Standley July 2, 1935 2,243,773 Randell May 27, 1941 2,249,128 Goldsmith July 15, 1941 2,329,553 Newbould Sept. 14, 1943 2,339,711 Lowe et al Jan. 18, 1944 2,396,696 Berry Mar. 19, 1946 2,528,189 Temperley Oct. 31, 1950