US2789815A - Apparatus for inserting tissue sheets in folder blanks while being folded - Google Patents

Description

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April 23, 1957 .1. F. NASH, JR.. ETAL 2,739,315 APPARATUS FOR INSERTING TISSUE SHEETS IN FOLDER BLANKS WHILE BEING FOLDED 5 Sheets-Sheet 1 Filed Jan. 19, 1954 hula, w

INVENTORS $44455 F? Mae; we. (7/484 [5 0 M4674,

ATTORNEYS April 23, 1957 J. F. NASH, JR.. ETAL. 2,789,815

APPARATUS FOR .INSERTING TISSUE SHEETS IN FOLDER BLANKS WHILE BEING FOLDED Filed Jan. 19, 1954 5 Sheets-Sheet 2 ATTORNEYS April 23, 1957 J. F. NASH, JR.. ETAL 2,789,815

- APPARATUS FOR INSERTING TISSUE SHEETS IN FOLDER BLANKS WHILE BEING FOLDED Filed Jan. 19, 1954 5 Sheets-Shea? 3 C/A'IZZESO. WAS/7 AAWEIf/I/CE 5/45/6001! I ATTORNEYS April 23, 1957 J. F. NASH. JR, ETAL 2,789,315

APPARATUS FOR INSERTING TISSUE SHEETS IN FOLDER BLANKS WHILE BEING FOLDED 5 Sheets-Sheet 4 Filed Jan. 19, 1954 INVENTORS ATTORNEYS April 23, 1957 J. F. NASH, JR.. ETAL 2,789,815

APPARATUS FOR mssmmc nssua: SHEETS IN FOLDER BLANKS WHILE BEING FOLDED 5 Sheets-Sheet 5 Filed Jan. 19, 1954 BYWW/I ATTORNEYS United States Patent APPARATUS FOR INSERTING TISSUE SHEETS IN FOLDER BLANKS WHILE BEING FOLDED James F. Nash, Jt., Charles D. Nash, and Lawrence H. Basham, Alderson, W. Va.

Application January 19, 1954, Serial No. 404,874

Claims. (Cl. 270-45) This invention relates to a machine for cutting and inserting flimsy sheets of tissue paper successively into folders with an edge of the sheet in substantial coincidence with the apex of the angle of fold, simultaneous with the creasing of the folder from a flat blank.

This is an operation that cannot be successfully performed if the crease in the blank is made by a buckling device, since the gradual bending of the blank in the formative stages of creasing, together with the limp character of the insert sheet rule out any positive control which would reliably locate the edge of the sheet at the line of fold in the completely creased folder.

The invention has in present contemplation the insertion of a sheet of tissue paper within a folded color chart in the act of folding the same, between the series of painted chips on opposite inner faces of the color chart, to protect opposite chips from coming in direct contact, thereby preventing interbleeding of the colors.

The general object of the invention is to provide a machine that will present fiat folder blanks successively at an inserting station at which the unwound end portion from a reel of the tissue insert material hangs suspended above the folder blank with its edge close thereto, in a vertical plane substantially intersecting the potential crease line of said blank, to provide a creasing knife at one side of the plane of said suspended tissue for imparting a dihedral fold to said blank, driving its apex down into pinched relationship between a pair of cooperating rolls, and to provide a cutter for severing from the vertically suspended portion of said tissue material a section of sheet length, the operation of said cutting knife being so timed that the severed sheet and creasing knife descend together into the dihedral fold with the leading edge of the sheet at the apex of the fold whereby it is clamped in this position while the folding of the blank is completed by the passage of the blank between the feed rolls.

Another object of the invention is to provide tensioning means for the flight of tissue between the reel and said feed rolls, including a roll floating in a loop of said tissue which operates a brake on the reel responsive to slackening of said loop for avoiding back lash of said reel.

Still another object of the invention is to provide means for adjustably varying the length of the tissue sheet severed from the vertically suspended portion of said tissue.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the drawings which accompany and form a part of the following specification, and throughout the several figures of which the same reference characters have been used to designate identical parts:

Figure 1 is a side elevation of a machine embodying the principles of the invention;

Figure 2 is an end elevation of the same;

ZFigure 3 is a horizontal section taken along theline 33 of Figure 2;

Figure 4 is a section taken along the line 4-4 of Figure 2;

Figure 5 is a perspective view of the end cam that operates the cutting knife;

Figure 6 is a section taken along the line 6-6 of Figure 4;

Figure 7 is a section taken along the line Figure 2;

Figure 8 is a section taken along the line 8-8 of Figure 7;

Figure 9 is a'horizontal sectional view taken along the line 9-9 of Figure 4.

Referring now in detail to the several figures, the machine comprises a base, generally designated by the reference character, 1, which includes a horizontal rectangular frame having side members 2 and 3 and end members 4 and 5. Said frame is supported by legs 6, 7, 8 and 9 at the corners, and an intermediate leg 10 on the left side, referred to Figure 1. An intermediate frame member 11 extends across the frame parallel to the side member 2.

A table 12 extends horizontally below the rectangular frame, being suitably secured thereto, having its forward end 13 upturned and provided at intervals with slots 14 affording guideways for the ribbon belts 15 of a belt conveyor 16. Said ribbon belts pass over pulleys 16' on a drive shaft 17, mounted at the front of the machine. The opposite endportions of said ribbon belts pass over similar pulleys 18, on a lay shaft 19, journaled in hearing lugs 20 secured to the rear side frame member 2. As shown, the upper flights of the ribbon belts 15 pass above the level of the table 12. At the rear, said table is provided with an upstanding stop support 21, Figures 3 and 4, having secured thereto the vertically depending fingers 22, which extend below the plane of the upper flights of the ribbon belts, projecting through slots 24 in the table. The stop support 21 is adjustable in the longitudinal direction of the ribbon belts by means of the bolt and slot connection 23, best shown in Figure 3.

The drive shaft 17 is driven by a belt and pulley connection 26 from the motor 27 through the gear reduction 28.

Flat folder blanks, one of which is indicated at 25 in Figure 3, are laid upon the conveyor 16 by any conventional sheet feeding means, not shown, such as vacuum cups, synchronized with the operation of the inserting machine.

which each is lined up and its motion temporarily arrested, the ribbon belts passing continuously beneath said blank. The blank in this position is at the creasing station, the timing of the feed of blanks to the conveyor 16 being such that one blank is folded and moved entirely through the conveyor, as will appear, before another blank takes its place at the creasing station. Figure 4 shows that the table 12 has an opening 29 extending between two adjacent ribbon belts, and that beneath this opening are arranged the cooperating feed rolls 30, which are driven in opposite directions so that they approach in their upper arcs. The opening 29 and the rolls 30 are of adequate length to accommodate the longest folder blank which the machine is adapted to handle, the extent of the length of this opening being indicated in Figure 3. The feed rolls 30 are geared together at one end and driven by a belt and pulley connection 31 from the gear reduction 28.

A long oscillating arm 32 is fixed to a shaft 35, jour naled in brackets 33, secured to the frame member 5. The free end of said arm carries a downwardly directed rectilinear'creasing knife 34. The forward end of the Patented Apr. .23, 1957 These are carried successively by the conveyor; to aposition against the stop fingers 22, by means of shaft 35 carries a crank arm 36, which at its free end is provided with a roller 37 engageable with a face cam 38, Figure 2, mounted on the drive shaft 38, having a helical cam face similar to that of the cam shown in Figure 5, and engaged by the roller through weight of the arm 32. The action of this cam is to periodically and suddenly depress the creasing knife 34, striking the flat folder blank positioned at the creasing station, initiating a fold line in said blank and driving it downward through the opening 29 into pinched relation between the feed, rolls 30. Upon engagement by said feed rolls the folder blank passes between them, being flat folded in passage.

Proceeding now to the mechanism by which a tissue.

sheet is fed in receptive proximity to the folder blank at the creasing station, a pair of upright channel standards 39 are mounted upon the parallel side frame member 2 and intermediate member 11 similarly positioned inspa-ced relation. Said standards support a vertically adjustable tissue. feeding unit, generally indicated by the reference character 49, and which comprises a pair of spaced frame plates 41 and. 42 tied together in parallel relationship by the cross member 43. Said frame plates each include a vertically depending portion 44 embraced within the channeled standards 39, and vertically adjustable therein. Forwardly of the depending portions 44, the frame plates have the similar depending portions 45, which support at their lower ends a three-sided rectangular frame 46, to the transverse portion of which a fixed cutting knife 47 is secured. The front of said frame is open to permit the incursion of the movable cutting knife 48, which cooperates with the fixed knife in severing a tissue sheet, as will later appear.

A reel shaft 49 rests in open hearings in the tops of the frame plates 41 and 42, extending across the feedingunit 40. This shaft has a brake 50 secured thereto adjacent one end. Said brake comprises a bushing 51 fixed to the shaft 49 and a complementary brake element comprising a rubber sleeve 52 surrounding the bushing 51 and frictionally engaging the latter, said sleeve being riveted to the adjacent face of a ratchet wheel 53, which of itself is freely revoluble about the shaft 49. A split brake band 54 surrounds the sleeve 52, having a manual adjusting screw 55, by means of which the sleeve can be more or less constricted to give the proper frictional pressure against the bushing 51. The adjacent frame plate 42, Figure 7, has a pawl 56 pivoted thereto at 57, the nose of said pawl being engageable with the teeth of the ratchet wheel 53. Normally, when the pawl 56 is out of engagement with the ratchet wheel, the entire brake mechanism rotates with the shaft 49, there being. no braking effect. As soon as the pawl moves to a teeth engaging position, the rubber sleeve 52 is immobilized and the shaft 49 isrotatable under a braking pressure determined by the adjusted friction of the sleeve relative to the bushing 51.

A shaft 58 bridges the frame plates 41 and 42 at the top, being journaled in closed bearings in said frame plates. This shaft carries a tensi-oning roll 59. At a distance below the tensioning roll, a pair of cooperating feed rolls 6t) and 61 are mounted. These rolls are tangent to one another along a line which is substantially in a vertical plane intersecting the folder blank along the potential line of fold of the latter. The feed rolls 60 and 61 are geared together at one end, one of the intermeshing gears being shown at 62 in Figure 2. The roll 60 has a drive gear 63 at its opposite end outside of the frame plate 41. Said rolls are driven by the following serially related instrumentalities from the motor 27, there being a crank arm 64 fixed to the armature shaft, and connected by a link 65 to the lower end of a rocking lever 66. Said rocking lever, as shown, is a straight rod, clamped. to the shaft 67, the latter being journaled, atits ends. in; bearings,

A link 70 having a boreherethmllsh, is-

slidably mounted upon the upper portion of said rocking lever and adjustable thereupon by means of the thumb screw 71. Said link forms the connection for a pivotally mounted rack bar 72 which intermeshes with the gear 63 on the feed roll 60. In order to prevent the rack bar from jumping the teeth of the gear 63, it is overlain in the region of said gear by a keeper 73 which is pivoted to the frame plate 41 coaxially with respect to the feed roll 60, so as to move complementary to the shift in angularity of the rack bar in different positions of its range of stroke.

The gear 63 is the outer element of a unidirectional clutch, best shown in Figure 4, said gear being an annulus surrounding a ratchet wheel 74 fixed to the shaft of the feed roll 60, with a spring pawl 75 fixed to the annulus and engaging the teeth of the ratchet wheel. The annulus and ratchet wheel are coupled by the pawl during the rightward stroke of the rack bar 72, and released upon reverse movement of said rack bar.

In Figure 1, a reel 76 is shown, consisting of a continuous web of tissue paper mounted nonrotatably upon the reel shaft 49 by means of tapered chucks 77 in its ends, both of which are shown in Figure 8. The end portion of said Web, unwound from said reel, is draped over the tension roll 59, from which it descends substantially vertically, passing between the feed rolls 6t) and 61, the free portion below said feed rolls hanging vertically, extending through thecutting plane of the knives 47 and 48, with its lower end close. to the plane of the underlying folder blank. The length of working stroke of the rack bar 72 is such as to impart an extent of rotation to the feed rolls which will lower a length of tissue below the cutting plane equal to the length of the desired insert.

When the rack bar 72 changes its direction at the outer end of its working stroke, the pull of the unwound portion of the web upon the reel is relieved, but the reel would continue to revolve under its inertia in the absence of means to prevent it, unwinding a surplus length of web which would not all be taken up on the next working stroke, and which would soon accumulate in uncoutrollable quantity; This is prevented by the brake 50, which is actuated by the following means responsive to variations in slackness of the web between said reel and said feed rolls.

A wide; rectangular bail 78 has parallel side arms 79 and 80, with eyes 81 at their free ends which freely encircle. the reel shaft 49 at points adjacent its opposite ends. A light roller- 82 is journaled on the bight portion 83' of the bail. In the form of bail shown the arm is detachable from the bight portion 83, the end of the latter extending through a hole in the arm 80, and being latched by a spring projected ball detent 84 in the arm 80, which engages a depression in the adjacent end of the bight portion. The arm 80 is detached from the bight portion of the ball and slipped from the reel shaft 49- aftersaid shaft has been lifted fromits bearings to permit thereel of tissue to be slipped upon the roll shaft.

The bail 78 rests with the roller 82 bearing upon a loop 85 of the Web drawn between the reel and tension roll 59. One end of the bight portion of the bail has a rectilinear extension 86 at one side, which projects within the bifurcated end of a rod 87, rigidly but adjustably secured to the pawl 56. When the feed rolls 6t) and 61 begin to operate, the tissue web between said rolls and the. reel is tensioned, shortening the loop 84, lifting the bail and with it the bifurcated end of the rod 87 which tilts the pawl 56 in a clockwise direction, releasing the brake 50. This permits the reel to unwind freely responsive to the demands of the feed rolls. When the feedrolls stop at the end of the rocking stroke of the rack bar 72, the roll continues to, unwind. a. little further under its inertia, lengthening the loop 84 which lowers the bail 78 and rod 87, thereby bringing the pawl56. into engagement with the. ratchet wheel 53, inhibiting free movement of the'brake asa whole, and subjecting the reel shaft 49 to braking friction between the rubber sleeve 52 and the bushing'Sl. Further unwinding of the reel is quickly stopped.

Reverting to the tissue feeding unit 40, which is best shown in Figure 1, this has been described as being vertically adjustable through the depending portions 44 which slide in channeled standards 39 and are locked in adjusted position by the set screws 88. This vertical adjustment is made for the purpose of spacing the cutting plane of the knives 47 and 48 at various distances from the plane of the underlying folder blank to permit the cutting of inserts of different length, as required. The movable knife 48 is pivotally mounted on the frame 46, which is fixed at the bottom of the depending portions 45 of the frame plates 41 and 42, by the pivot bolt 89, and is moved into cutting contact with the fixed knife 47 through the operation of a driving train, which includes a face cam 90, Figures 1, 3 and mounted on the end of a driven shaft 111, which is engaged by one end of a rocking lever 91 intermediately pivoted on a vertical axis 92. The opposite end of said rocking lever is engaged in a slot in the lower end of a second rocking lever 93 which is pivoted at an intermediate point on a horizontal axis 94. The upper end of the rocking lever 93 is coupled by a pivot and slot connection 95 to the end of a longitudinally reciprocable push rod 96 slidably through fixed guide bearings 97 and 98. A spring 99 in compression between the bearing 97 and a collar 100 on the push rod reacts through the push rod and rocking levers to hold the free end of the rocking lever 91 with resilient pressure against the cam 90.

A vertically disposed coupling element 101 is fixed to the free end of the push rod 96. This coupling has the form of a relatively thin strip or flange 102, with an enlarged bead 103 of uniform spherical cross-section extending along one edge. In order to assure the rigid uprightness of the coupling element 101, a guide rod 104 is fixed to said coupling element at a distance from the push rod and extending parallel thereto, passing slidably through bores in the bearings 97 and 98. The coupling element is made long so that it can maintain coupling engagement with the movable knife 48, throughout the range of vertical adjustment of the tissue feeding unit 40. A complementary coupling element is carried by the movable knife, consisting of a plate 105 having a keyhole slot 106 therethrough, fittably embracing the bead on the coupling element 101. Since the knife 48 moves arcuately, while the push rod 96 moves rectilinearly, the plate 105 is attached to the knife 48 by a pin and slot connection represented by the headed studs 107, which play in slots 108 in said plate. The rocking lever 93 is oscillated by the cam 90 in such a manner as to progressively withdraw the movable knife from the fixed knife, and to suddenly release the push rod, permitting the spring to drive it on its cutting stroke, bringing the keen edges of the knives suddenly into shearing engagement.

In operation, the ribbon belts 15 run continuously. Flat folder blanks are fed to the ribbon belts by conventional feeding means, not involved in the present invention, but which operates in timed relation to the tissue inserting mechanism. The folder blank travels on the belt until its strikes the stop fingers 22, which stop at a definite position beneath the inserting mechanism, the belts continuing to travel beneath it. While the blank is traveling toward the inserting station, the feed rollers 60 and 61 lower the end portion of the continuous tissue web from the roll 76, which hangs vertically over the folder blank with its lower edge in substantial registry with the potential fold line.

Substantially simultaneously. the creasing knife and insert cutting knives are operated so that as the creasing knife descends upon the blank, the insert sheet descends vertically beside it, being carried down with its lower edge at the apex of the dihedral angle formed in the blank by the creasing knife so that when the apex of said angle is caught between the rolls 30, the insert is also caught and held in position while the folding of the blank is completed by its passage between said rolls. The folded blank is delivered upon a deflecting plate 109, from which it slides upon a conveyor 110 which may take it to a buckling machine for further folding of the folder. It is practical to use a buckling machine for the second folding, for the tissue sheet is already held in position within the folder frictionally between its leaves. For producing a longer insert, the feeding unit 40 is raised, the depending portions 44 being elevated within the channeled standards 39 and immobilized in adjusted position by the set screws 88. The length of the insert is determined by the distance of the plane of the cutting knives from the plane of the underlying folder blank. The amplitude of rotation of the feed rolls 60 and 61 must be correspondingly adjusted to draw down the desired length of tissue. This adjustment is made by loosening the thumb screw 71 and sliding the link 70 on the rocking arm, thereby adjusting the length of the rocking stroke of the rack bar 72.

While we have in the above description disclosed a practical embodiment of the invention, it will be understood by those skilled in the art that the specific details of construction and arrangement of parts, as shown, are by way of example and not to be construed as necessarily limiting the scope of the invention.

What we claim is: I

1. Apparatus for inserting a tissue sheet between the sides of a folder while the folder blank is being folded to form said sides, comprising a table having an opening therethrough, means for suspending the unwound end portion of a continuous reeled web of tissue in a vertical plane intersecting said opening, and above a flat folder blank supported by said table with its intermediate portion over said opening, the latter being narrower than said blank, cutting means for severing an insert sheet from the end of said unwound portion, feeding means engageable with said web above said cutting means for drawing said web down until the end edge thereof is substantially at the plane of said folder blank, downwardly movable creasing means engageable with said blank along a line substantially in said vertical plane for forcing said blank through said opening thereby creasing it along said line, driven folding rolls beneath said opening between which the apex of said creased blank is introduced by said creasing means, the operation of said creasing means and cutting means being so synchronized that severed tissue sheet drops gravitationally into the apex of the angle of fold of said blank simultaneously with the forming of said apex by said creasing means and being retained in this position through constriction of sad apex between said folding rolls.

2. Apparatus for inserting a tissue sheet between the sides of a folder while the folder blank is being folded to form said sides, comprising a table having an opening therethrough, means for conveying successive flat folder blanks to a position on said table in which their intermediate portion overlies said opening, the latter being narrower than said blank, means for suspending the unwound end portion of a continuous reeled web of tissue in a vertical plane intersecting said opening, and above a fiat folder blank in said position, cutting means for severing successive insert sheets from the end of said unwound portion, one for each blank, feeding means engageable with said web above said cutting means operating in alternation with the cutting stroke of said cutting means for drawing said web down until the end edge thereof is substantially in the plane of said folder blank, downwardly movable creasing means engageable with said blank along a line substantially in said vertical plane for forcing said blank through said opening thereby creasing it along said line, driven folding rolls beneath said opening between which the apex of said creased blank is introduced by said creasing means and between which said creased blank passes, the operation of said creasing means and cutting means being so synchronized that a severed tissue sheet drops gravitationally into the apex of the angle of fold of said blank simultaneously with the forming of said apex by said creasing means, and being retained in this position through constriction of said apex between said folding rolls.

3. Apparatus for inserting a tissue sheet between the sides of a folder while the folder blank is being folded to form said sides, comprising a table having an opening therethrough, means for conveying successive flat folder blanks to a position on said table in which their intermediate portion overlies said opening, the latter being narrower than said blank, means for suspending the unwound end portion of a continuous reeled web of tissue in a vertical plane intersecting said opening, and above a fiat folder blank in said position, cutting means for severing successive insert sheets from the end of said unwound portion, one for each blank, interconnected feed rolls above said cutting means frictionally engaging said web at opposite sides, a gear coupled for unidirectional movement to one of said feed rolls, a reciprocatory rack bar in mesh with said gear for operating said rolls in alternation to said cutting means for drawing said web down through insert length distances with the end edge of said web substantially in the plane of said folder blank, means for reciprocating said rack bar, downwardly movable creasing means engageable with said blank along a line substantially in said vertical plane for forcing said blank through said opening thereby creasing it along said line, driven folding rolls beneath said opening between which the apex of said creased blank is introduced by said creasing means and between which said creased blank passes, the operation of said creasing means and cutting means being so synchronized that a severed tissue sheet drops gravitationally into the apex of the angle of fold of said blank simultaneously with the forming of said apex by said creasing means, and being retained in this position through constriction of said apex between said folding rolls.

4. Apparatus for inserting a tissue sheet between the sides of a folder while the folder blank is being folded to form said sides, comprising a table having an opening therethrough, means for conveying successive flat folder blanks to a position on said table in which their intermediate portion overlies, said opening, the latter being narrower than said blank, downwardly movable. creasing means engageable with said blank along a line above said opening for forcing said blank through said opening thereby creasing it along said line, a tissue insert forming and' inserting unit above said table comprising a support, a reel shaft journaled thereupon, a reel secured to said shaft containing a continuous wound tissue Web, means on said support for suspending an unwound end portion of said web in a vertical plane which substantially embraces the crease line ofsaid folder blank, with the end edge of said web substantially in the plane of said folder blank, cutting means carried by said support for severing insert sheets from; the end of said unwound, portion, one for each blank, the distance of the line of severance from said folder blank determiningthe length of an insert, interconnected feed rolls carried by said support above said cutting means, frictionally engaging said web at opposite sides, a gear coupled for unidirectional move ment' to one of said feed rolls, a reciprocatory rack bar in mesh with said gear for periodically unreeling insert lengths of web from said reel, driven folding reels beneath said opening, between which the apex of said creased folder blank is introduced by said creasing means and between which said creased folder blank passes, the operation of said creasing means and cutting means being so synchronized that a severed tissue sheet drops gravitationally into the apex of the angle of fold of said folder blank simultaneously with the forming of said apex by said creasing means, being retained in this position through constriction of said apex between said folding rolls, means, for adjusting said tissue insert forming and inserting unit vertically with respect to said table to vary the distance of said cutting means from the plane of said blank, and means for correspondingly varying the length of the working stroke of said rack bar.

5. Apparatus for inserting a tissue sheet between the sides of a folder while the folder blank is being folded to form the sides, comprising a "base frame, a table carried thereby having an opening therethrough, means for conveying successive flat folder blanks to a position on said table in which their intermediate portion overlies said opening, creasing means engageable with said folder blank along a line above said opening for forcing said blank through said opening thereby creasing it along said line,- a tissue insert forming and inserting unit above said table comprising a supporting frame vertically adjustableiwit'n respect to said table and carrying the following instrumentalities: a shaft for a reel of wound tissue web, a roller for suspending an unwound end portion of said web in a vertical plane which substantially embraces the crease line of said web, cutting means below said suspending roller comprising a fixed and a cooperating movable knife for severing successive insert sheets from the end of said unwound portion, the distance of the line of severance from the plane of said folder blank determining the length of said insert sheet which length is, changed by vertical adjustment of said unit, and interconnected feed rolls above said cutting means frictionally engaging said web, a gear coupled for unidirectional movement to one of said feed rolls, a reciprocatory rack bar in mesh with said gear for periodically operating said feed rolls to unwind insert lengths of web from said roll, a pitman pivotally mounted on said base frame, a slidable connection on said pitman, said rack bar being hingedly secured to said connection, the latter being slidably adjustable to vary the stroke of said rack bar, reciprocatory means mounted on said base frame for operating said movable knife, including interengaging complementary coupling elements having slide and guide relationship in a vertical direction to allow for vertical adjustment of said unit insert forming and inserting unit, said pitman and knife operating means. being synchronously driven to sever the inserts in the intervals between working strokes of said rack bar.

References Cited in the file of this patent UNITED STATES PATENTS 718,316 Cottrell Jan. 13, 1903 1,591,418 Ferguson July 6, 1926 2,482,059 Gates Sept. 13, 1949 2,541,737- Bardsley et al Feb. 13, 1951

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