US2414109A - Method of and machine for making blanks - Google Patents

Description

Jan. 14, 1947. c. D. KNOWLLTON ETAL' 2,414,109

METHOD OF AND MACHINE FOR- MAKING BLAN KS Original Filed March 26, 1942 s She ets-Sheet 1 J 14, 1947' c. D. KNOWLTON ET AL 2,414,109

METHOD OF AND MACHINE FOR MAKING BLANKS Original Filed March 26, 1942 "s Sheets-Sheet 2 Gear 'eEGDc/r'ke 5 y C. D. KNOWLTON ETAL 2,414,109

METHOD OF AND MACHINE FOR MAKING BLQNKS Original Filed March 26, 1942 3 Sheets-Sheet 5 Patented Jan. 14, 1947 METHOD OF AND MACHINE FOR MATKIN G BLANKS Cutler I). Knowlton, Burke, Fairhaven,

Rockport, and George F. 0. Mass, assignors to Hoague- Spragne Corporation, Lynn, Mass, a corporation of Massachusetts Original application March 26, 1942,

436,362. Divided her 4, 1943, Serial 13 Claims. 1

Thi application relates to the manufacture of box blanks such, for example, as that illustrated in United States Letters Patent No. 1,811,135, granted June 23, 1931, on an application filed in the name of C. D. Knowlton. The present application is a division of an application for Letters Patent of the United States, Serial No. 436,362, filed March 26, 1942, in our names.

In the manufacture of box blanks as disclosed in the aforementioned application, webs of shell, cover and lining material are continuously combined to form a Web of blank material from the end of which discrete blanks are severed and fed step by step past a plurality of forming stations at each of which an operation is performed toward the completion of a box blank. ent application is concerned with that station at which slots are formed in theblank to separate the end-wings and the corner-laps and the outer edges of the end-wings are cut awayto accommodate the thickness of the material where the end-wing extensions are folded over the corher-laps during the setting up of the blank to box form.

An object of the present invention relates to the provision of an improved mechanism for performing the above operations. four sets of knives are provided for forming the slots-and the cutawa portions at the outer edges of the end-wings in a single operation. To accommodate blanks of various sizes, provision is made for adjusting the knives relatively to one another. As illustrated herein, the sets of knives are arranged in pairs, each pair being adjustable as a unit toward and away from the other pair, and the sets of each pair are adjustable simultaneously toward and away from each other. Provision is also made for adjusting the knives of each set toward and away from each other.

Another object of the invention relates to the provision of improved means for forming the slots between the end-wings and corner-laps in a manner to providea finished appearance for the edges of the end-wings which are visible in the completed box, and to the method by which this is accomplished. In the attainment of this object the edges of the end-wings along the slots separating them from the corner-laps are so treated that the cover paper extends over the edges. This is effected in the illustrated embodi- To this end,

ment of the invention by turning the marginal portions of the end-wings inwardly when the blank is severed to form theinner edges of the corner-laps, after which the inwardly projecting portions are-severed in-substantially the plane of Serial No.

and this application Decem- No. 512,856

the inner face of the blank to form the edges of the end-wings with the cover paper extending thereover to the inner face of the blank. It will of course be obvious that this method of forming the slots is applicable in those cases in which the blank is not provided with cover paper. When such a blank is treated, the outer surface of the blank will extend over the edge, .thus eliminating the raw edge that would be formed 'bythe conventional slotting methods.

The above and other features of the invention, including various novel details of construction andcombinations of parts, will now'be moreparticularly described with reference to the accompanying drawings, and pointed out in the claims.

In the drawings, V

Fig. 1=-is an end elevation, partly in section,;of one form oiapparatus by which the presentinvention may be carried out;

"Fig. 2 'isa section on the line Ila-II of Fig. ;l, on .alarger .scale than Fig. 1;

"Fig.3 is an exploded view of .oneof the mechanisms for forming the slotbetween a cornerelap and an end-wing;

:"Fig. 4 is a .view,partl-y in section, of .oneof the sets of work engaging members;

Fig. v5 is .a plan View of .a blank as it appears after beingsevered from a compound web .of sheet material;

"Fig. :6 is a plan view ofthe blank'after it has been operated upon by the present apparatus;

'Fig. "7 is a perspective view on a greatly en.- larged. scale'indicating how the cover paperhides the. edge of thelend-wwing whenthe blank is operated upon-by the mechanism of Figs. 3 and 4; and

Fig. 8:is a perspective view of a portion pfa box illustrating the .appearance of the covered edgeoft-he end-wing in the completed box.

@ne form of blank upon which ,the machine illustrated herein is.designedito operate .is shown at a in Fig. 5 and comprises a layer of.shel1=rnaterial b; a liner.c,.and a-layer of coverpaper 11. hec'over paper-maybe folded around the edges of the blank ate to provide a finished appearance. 'Theiblank isoperated uponzbyithe present machine to form slots f which .separate the endwings :g from thecOrner-laps "The outer. edges 'of the corner-laps are also cutiaway at? to .accommodate .the thickness of the material where the end-wing extensions are folded over the corner laps during-the setting up of the='blanl s-to box form. Side-wing k extend-between b11960!- ner-laps After the blank is thus operated upon, it passes successively through other stations as illustrated in the parent application re- 3 ferred to above to complete the formation of the box blank.

The machine is built on a frame which comprises supporting bars IE) extending lengthwise of the machine and supported on the floor. Extending upwardly from the bars Iii are posts I2 to the upper ends of which are fastened rails I4 which extend lengthwise of the machine. The posts I2 are connected by a cross bar It and the rails I4 are interconnected by one or more cross bars (not shown) to provide a rigid frame work.

The blanks are fed through the folded edges 6 extending normal to the direction of feed by a pair of endless belts it which engage opposite sides of the blank and which feed the blank into engagement with a pair of stops 29 mounted on shafts 22 for movement from the positions illustrated in Fig. 1, downwardly into the path of movement of the blank. With the forward motion of the blank thus arrested the blank is operated upon as will be described, after which the'stops are returned to the positions illustrated and the blank resumes its forward movement through the machine. In order to accommodate blanks of dierent sizes the stops 2c are carried by slides 24 which are mounted for lateral movements on a rack 26 extending crosswise of the machine. This rack is secured to the upper ends of posts 28, the lower ends of which are secured to the rails I4. Pinions 30 carried by shafts 32 supported in the slides 24 engage teeth in the upper surface of the rack 'bar 26 to effect lateral movement of the slides 24 and the stops 2!! carried thereby upon turning the shafts 32.

Prior to operating on the blank after it has come to rest against the stops 20, the blank is properly centralized in the machine by a pair of joggers 34 having ends provided with notches for engagement with the opposite edges of the blanks. The joggers are adjustably mounted in the upper ends of arms 36, the lower ends of which-are secured to slides 38 movable transversely of the machine on slideways 40 formed along the upper sides of cross bars 42 suspended by hangers 44 from the rails I4. The slides 38 are provided wth rack bars 46 engageable with pinions 48 which are operated at a predetermined time to move the joggers toward each other to centralize the blank and then to retract the joggers while the blank is being operated upon. The pinions 48 are operated by a gear 50 mounted on a shaft 52 and connected by an arm 54, a link 56, a lever 58, and a cam roll (not shown) to a cam 60 mounted on a continuously rotating drive shaft 62 whereupon the gear 50 is oscillated to operate the joggers. Provision is made for adjusting the paths of movement of the joggers thereby to accommodate blanks of different sizes. For a more complete description of the mechanisms thus far described, attention is directed to the parent application.

The machine is provided with four sets of cutters, one set operating at each corner of the blank to form the slots separating the end-wings and the corner-laps and to cut away the corner-laps at 7'. The knives by which the slots and recesses are formed in the upper left-hand corner of the blank shown in Fig. 6 are illustrated in Fig. 4. The recess 7 in the blank is formed by a knife 64 movable downwardly past a cooperating shear block 66 to the position illustrated. A second knife 68 moves downwardly with the knife 64 and cooperates with a shear block ID to cut the blank along the line s (Fig. '7). The portion of the endwing adjacent to this cut is turned down at t the machine with sleeves.

around the edge of a knife I2 by the curved rear portion I4 of the knife 68. The knife I2 is spaced sufficiently from the knife 68 at this time so that there is no cutting action between these knives. After the knife 68 has moved downwardly to the position illustrated, the knife I2 moves in a substantially horizontal plane to trim off the downwardly projecting portion of the blank in the plane of the inner face of the blank, thus giving the appearance shown in Fig. '7. It will be noted that the cover paper 01 provides the end-wing g with a finished edge along the slot 1. Thus, when the box is assembled, this finished edge t will appear as indicated in Fig. 8 so that the edge of the layer of shell material is not visible in the completed box.

The mechanisms for operating on the blank at this station are mounted on a pair of carriages I6 (Figs. 1 and 2) mounted on the rails I4 for adjustment lengthwise of the machine. For effecting this adjustment racks I3 are secured to the underside of each carriage near the ends. These racks are engageable with gears mounted on shafts 82 which are supported by bearings 84 secured to the undersides of the rails I4. Each of the shafts 82 has on its outer end a member 86 (Fig. 1) arranged to receive a crank whereby each shaft may be individually rotated to adjust its associated carriage lengthwise of the machine. The carriages are locked in their adjusted positions by gibs 88 secured to the rails by screws 90.

To each of the carriages is secured a pair of gibs 92 (Fig. 2) forming between them a slideway for a pair of slides 94 movable lengthwise of r the carriages or transversely of the machine. The

slides on each carriage are mounted for similar adjustment toward and away from each other by a screw 96 having right and left hand threaded portions passing through threaded sleeves 98 mounted in blocks I00 (Fig. 2) secured to a side of each slide. These sleeves provide individual adjustment of the slides relatively to each other and are locked in the desired positions of adjustment by set screws I32 engaging grooves in the Carried by each of the slides 94 is a bed I04 upon each of which is mounted a pair of shear blocks 66 and I0 (Fig. 2). The inner portion of each bed is secured to its slide by a pair of screws I65 threaded into a rod I08. These rods are journaled in spaced arms projecting from the inner portions of each slide as shown more clearly in Fig. 2. Each pair of screws I08 passes through a bar II!) which engages the upper rearward surface of a bed I84. The screws pass through recesses in the end of the bed as shown in Fig. 2 so that, upon loosening the screws slightly, the bar Ill) and the rod I08 may be swung as a unit to free the rearward portion of the bed. Tongue and groove portions II2 between the slide and bed facilitate the proper positioning of the bed on its slide. Other securing means (not shown) may be provided between the outer portions of the slides and beds more firmly to secure them together.

Secured to the outer portions of the beds I94 and extending upwardly therefrom are supporting frames I I4 having overhanging arm portions IIB (Fig. 1) for supporting the knives 64 and 68. The lower portions of the supporting frames have dovetail grooves II8 with which ocooperate the wedge heads I20 of bolts I22 (Fig. 3) which pass through blocks I24 and receive nuts I26 for rigidly securing theblocks to the frames H4 and the shear blocks 66 to the blocks I24. The blocks I24 may be adjusted along the beds by reason of the dovetail connection provided by the of the gibs (Fig. 2) is backed up by screws I I5 grooves H8 and the heads I20 of the bolts and which permits adjustment of the gib toward the by reason also of the fact that the other ends th gib t t k up for w ar, Th lid are of the blocks I2 a e l da y secured to the bed connected to vertically movable cross-girts I80 y bolts I23 passing through the cks I24 a d which are connected at their oposite ends to nuts I36 received by a T-slot in the bed (Fig. 1). cross-heads I82 (Fig. 1) which are in turn se- Heads 34 of the bolts IZ'B (Fig. 3) hol each cured to the upper ends of vertically movable shear block 66 against the upper surface of its rods I84, These rods pass through bearings I86 upporting block I 24. The supporting block has secured to the side rails I 4 and through bearings a l pin ur a e I36 r directing the scrap from I88 secured to the supporting bars Iii. The rods the blocks. A Conveyor belt (not shown) may are reciprocated by the shafts 62 which carry be p d a the bottom of e machine o eccentrics I 9B connected by straps I92 and pivot carrying material trimmed from the blocks away pins I94 to clamps I96 secured to the rods. The from the machine. 011 the fron f h pp r knife-supporting slides are connected to the ing blocks I24 toward the entrance end of the cross-girts as follows. Threaded through the machine ar adl s ab y secured guide plates upper portions of the slides are sleeves I98 pro- I 8 a a d o engagement y the forward viding in their lower ends abutments for springs edges of the blanks to insure that the blanks will ze Th springs t a ainst flanges 292 near ri e sm ot ly v r h l k the u er ends of rods 204, to the bottoms of The shear blocks 10 are carr ed y pp t n which are threaded nuts acting on the bottoms of frames I ls which are mounted on the beds I04 th bushings t prevent downward movement of for adjustment relatively to the shear blocks 6b the bushings on the rods. The uppe ends of the to vary the distance between the slots f and the rods are provided with heads 2e! clamped be- ClltaWay portions 9' 0f the blank- The frames Mil tween bars 206 secured to the under sides of the a e j t y s e e t t ds by bolts cross-girts and extending therebetween and gilbs I35 and 31 similar to the bolts I22 and '28. ZQQgecuredCto the bars The bars 206 are se The kn ves 72 a s pp t in the frame M9 by cured to'the cross/girts for adjustment by clamproeka le members having Stud shafts M5 ing screws 2H] passing through bars 2I2 resting journaled in bearings 6 mo in arms on the upper surfaces of the cross-girts. These f the Supporting frame Mt]. The knives 72 are clamping screws are loosened to permit the slides normally maintained in their retracted posi- 94 suppgltjng th ech ni ms for operating on ti ns, sho n in by sp I59 ac the blanks to be adjusted transversely of the tween arms I52 on the rockable members Hi2 and machine T r it the lengthwise adjustment recesses I 54 in the frames 5. The positions of the parts with the carriages I6, the gibs 208 to wh ch themembe s I a e moved by t e may be loosened so that the upper ends of the sp s are hmited by e screws I55 actlng rods'zllc may slide relatively to the cross bars against stops I 58 secured to the under sides of Auxiliary clamping screws 299 (Fig. 2) one of the arms I48 of the frames it. Ro s I59 threaded through the arms II6 are provided for are journaled on pins I62 in the arms I 38 and clampingthe Slides 5 against downward moveare e a d y t e bac Sides of Wedges as 4.0 ment in the frames II 4 whenever desired. This t se o e d n a y ahd pp the Wedges may be done whenever the gibs 208 are loosened a ainst lateral thrust. Th se We act on to permit this lengthwise adjustment of the parts.

goils k561i clazal ried bsy theflarniis I52 tic2 otsciilate itlhe thus reliezving the gibs of the weight of the slides. m e Carr h e lllves 0 T1111 8 Springs I (Fig. 2) act on the heads of the downwardly extending por o s t of e blank .15 screws to prevent their accidental turning. When (Flg- 4) alter the Operatlon 0f the khlves 54 the cross-girts are moved downwardly during the and 63 n operation of the machine, they act through the mgxgeal l ggs s m a ggbg i a ge a r l li h y springs 2053 to move the knives and strippers l S e e ah e nlves downwardly to a position limited by the engageare mounted for adjustment relatively to each ment of t 1ewer d of top crews 2 with ilther DQ lill ij lhg p a 1W lt d g stops M6 in the upper surfaces of the supporting oWer e ds 0 e s 1 e PP 6 e5 0 frames I I4. Upon further downward movement th s pp g pl tes aredovetailed as shown of the cross-girts the springs 200 will compress, 1n F1e- 1. Ea h of he knives, as sh w In ethus permitting the wedges I64 to move further gloilgiigtggfgggfiglfig firigmtiaeclfiegrgg gownwairggytgs will he1 dlescritbred, totta ctuate the S nives us compe mg e s 0 ing operaof which are elongated to underlie the projecting n ears 0:11I til; kniiges. faggo lt lql mi liz fig The wedges I?! are2 aijusltably clamped to the upwar .y roug a a in .e er vlower ends of sides w ich are in urn seing an i cl n surface arranged to engage the cured for vertical adjustments by bolt-and-slot dovetailed portion of the plate I'm, whereby the Connections 229 (F 2) ma 222 depending pposite ends of the knives may be m e in from brackets 224. These brackets are connected the desired positions on the plates. Similarly to the c 'os -gjrts ag between bars 225 and supported by the plates I'iil are strippers I'EEi, the gibs 2g3 Clamping screws 230 (Fig 1 passing work engaging portions of which may be formed through bars 223 on t upper urf e of the Sponge rubber arranged to Clamp the blank on o cross-girts adjustably secure the bars 226 to the the t p surfaces of the Shea! blocks 79 1119011 under sides of the cross-girts. Accurate adjustdownward movement of the knives The pment of the vertical positions of the Wedge carrypers normally extend downwardly below the ing slides may be effected by screws 232 threadknives and hold the blanks in position during 70 ed into the brackets 224 and engaging the tops the return upward movement of the knives until of the slides 2I8. Springs 234 act between the they have cleared the blanks. slides and pins projecting from the arms 222 The slides I68 are mounted for verticalm0veto maintain contact of the slides with the heads ment between gibs I78 secured to the overhangof the adjusting screws when the slides are ading arms H6 of the supporting frames II4. One J'usted.

From the above it will be seen that the knives are arranged in four sets, one for operating upon each corner of the blank, the sets of knives being in turn arranged in pairs, one pair operating on the leading portion of the blank and the other pair operating on the trailing portion. The pairs of sets are adjusted toward and away from each other by rotation of the shafts 82 which act through the pinions 80 and the racks 18 to move the carriages I6 along the supporting rails M. In order to permit this adjustment the gibs 88, by which the carriages are locked to the rails, are first loosened and the gibs 208 and 228 associated with the supporting bars 206 and 226, respectively, are also loosened. By means of this adjustment blanks for forming boxes. of different widths may be operated upon by the machine. The sets of knives of each pair are also adjustable toward and away from each other to accommodate blanks of different lengths by loosening the screws 2H) and 230 and rotating the adjusting screws 66. This moves the slides at lengthwise of the carriages 92, these slides supporting the beds I04 and the upwardly extending knife supporting arms H4. After the proper adjustment has been effected, the screws Ziil and 23% are tightened to lock the sets of knives in their adjusted positions. For adjusting the knives of each set relatively to each other the bolts M2 by which the knives are clamped to the supporting plates I!!! are loosened, thus permitting the knives to be moved along the plate into the desired positions of adjustment.

In the operation of the machine, the blanks are fed by the belts l8 into engagement with the stops 2!! into position to be operated upon simultaneously by the four sets of knives. After the blank comes to rest against the stops, the vertical rods use are moved downwardly, whereupon the cross-girts I83 carried thereby move the slides S88 and 2 l3 carrying the knives and the wedges, respectively, downwardly toward the blank. The knives 6d and move into the positions shown in Fig. 4, the knives 64 forming the cutaway portions 3? in the outer edges of the corner-laps and the knives 68 forming the slits s as illustrated in Fig. '7. At the same time, the surfaces [4 of the knives 58 turn the margins t of the end-wings g downwardly around the edges of the knives 12. This action of the knives on fore the cross-girts I80 have completed their downward movement but further movement of the knives is prevented by engagement of the stop screws 2. i i with the stops 2 l 6. Further downward movement of the cross-girts is permitted by compression of the springs 290 associated with the knife slides and the wedges I64 continue their downward movement acting through the rolls N56 to operate the knives 12. These knives cooperate with the surfaces M of the knives 68 to trim the downwardly projecting portions t of the blank in the plane of its lower surface, thereby to form the edges of the end-wings as shown in Fig. '7.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a machine for making a box blank having end-wings, side-wings and corner-laps, oppositely disposed sets of knives for operating on opposite sides of the \blank, each set comprising a knife for trimming the outer edge of a cornerlap and a knife for forming a slot between the corner-lap and the adjacent end-wing, a single adjusting means for moving said sets of knives simultaneously toward and away from each other,

the blank occurs be- 8 a single adjusting means for moving said sets of knives as a unit in a direction normal to said first direction of movement, and means mounting the knives of each set for adjustment relatively to each other.

2. In a machine for making a box blank having end-wings, side-wings and corner-laps, means for operating on each corner of the blank, said operating means being arranged in pairs, each of said operating means including means for trimming the outer edge of a corner-lap and means for forming a slot between the corner-lap and the adjacent end-wing, single adjusting means for each pair of operating means for moving them simultaneously toward or away from each other, single adjusting means for each pair of operating means for moving the pair as a unit toward or away from the other pair of operating means, and means mounting the trimming means of each or the operating means for adjustment relatively to each other.

3. In a machine for operating upon a box blank, means for forming a slot in the blank comprising means for severing the blank along a line and bending an edge of the severed portion inwardly, and means engageable with opposite sides of the inwardly projecting portion of the blank for severing said portion in substantially the plane of the inner face of the blank.

4. In a machine for operating upon abox blank, means for forming a slot in the blank comprising means for severing the blank upon a line and bending an edge of the severed portion inwardly, and means including said first-named means for severing the inwardly projecting portion of the blank in substantially the plane of the inner face of the blank.

5. In a machine for operating upon a box blank, a shearing member for forming a cut in the blank, said member having a work-engaging face arranged to bend the blank inwardly along the line of cut, and means cooperating with a side of said shearing member for severing the inwardly projecting portion of the blank in substantially the plane of the inner face of the blank.

6. In a machine for operating upon a box blank, a shearing member for forming a cut. in the blank, said member having a work-engaging face arranged to bend the blank inwardly along the line of cut, and means operated in response to movement of said shearing member for severing the inwardly projecting portion of the blank zbtgainst the adjacent side of said shearing mem- I. In a machine for making a blank having end-wings, side-wings and corner-laps projecting from the side-wings, said blank including a sheet of shell material to the outer face of which has been applied a sheet of cover material, a vertically movable member for severing the inner edge of the corner-lap and bending the adjacent edge of the end-wing inwardly, a member movable in a substantially horizontal plane for severing the inwardly projecting portion of the end-wing, and means for sequentially operating said members.

8. In a machine for making a blank having end-wings, side-wings and corner-laps projecting from the side-wings, said blank including a sheet of shell material to the outer face of which has been applied a sheet of cover material, a vertically movable member for severing the inner edge of the corner-lap and bending the adjacent edge of the end-wing inwardly, another member movable in a substantially horizontal plane for severing the inwardly projecting portion of the end wing, and means movable with said vertically movable member for operating said other member after the edge of the end-wing has been bent inwardly.

9. In a machine for making a blank having end-wings, side-wings and corner-laps projecting from the side-Wings, said blank including a sheet of shell material to the outer face of which has been applied a sheet of cover material, a vertically movable member for severing the inner edge of the corner-lap and bending the adjacent edge of the end-wing inwardly, a member movable in a substantially horizontal plane for severing the inwardly projecting portion of the endwing, means normally holding said last-named member away from the path of movement of said vertically movable member, a cam roll associated with said horizontally movable member, and a cam movable with said vertically movable member and cooperating with said cam roll for operating said horizontally movable member after the edge of the end-wing has been bent inwardly.

10. In a machine for making a blank having end-wings, side-wings and corner-laps projecting from the side-wings, said blank including a sheet of shell material to the outer face of which has been applied a sheet of cover material, a pair of shearing members movable in a direction at right angles to each other, means for moving one shearing member to sever the inner edge of the corner-lap and to [bend the associated edge of the end-Wing inwardly, and means formoving the other shearing member to trim the projecting portion of the end-wing against the adjacent side of the shearing member first moved.

11. Those steps in the method of making a blank having end-wings, side-wings and cornerlaps projecting from the side-wings, said blank including a sheet of shell mater'ialto the outer face of which has been applied a sheet of cover material, which comprises severing the inner edge" of the corner-lap and bending the adjacent edge of the end-wing inwardly, and then severing the inwardly projecting portion of the end-Wing from one side in substantially the plane of the inner face of the blank while the other side of said portion is supported against lateral movement.

12. In a machine for operating on a box blank, mechanism for forming a slot bounded along one side by a rounded edge comprisingv means for severing the blank along a line to form the opposite edge of the slot and for bending the severed portion inwardly, and means'for severing the inwardly bent portion along a straight line in the plane of the inner face of the blank.

13. Those steps in the method offorming box blanks from a sheet of laminated material composed of a sheet of shell material to the outer face of which has been applied a sheet of cover material which comprises forming a cut in the (blank along a line to form oneeclge of a slot between an end-wing and a corner-lap, bending the material inwardly of the blank to form a rounded edge along the opposite side of the slot and severing the inwardly projecting portion in the plane of the inner face of the blank whereby the cover paper extends over the rounded edge along the opposite side of the slot.

CUTLER D. KNO-WLTON. GEORGE F. C. BURKE.

Certificate of Correction Patent No. 2,414,109. January 14, 1947.

' CUTLER D. KNOWLTON ET AL. I i

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 3, line 25, for dierent read diflerent; column 4, line 70, for ocooperate read cooperate; column 5, line 19, for blacks read blocks; column 9, line 28, claim 10, for a direction read directions column 10, line 6, claim 11, for comprises read comprise; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of October, A. D. 1947.

THOMAS F. MURPHY,

Assistant flommi'ssz'oner of Patents.

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