US2645995A - Sheet edge trimmer for printing presses - Google Patents

Description

July 21, 1953' Filed Aug. 4, 1949 Fig. 1

J. J. ISELLA 2,645,995 SHEET EDGE TRIMMER FOR PRINTING PRESSES I 2 Sheets-Sheetl INVENTOR. JOHN J. ISELLA AUSTfN NILHELMCKRLSQN AA. A'ITORQBYS Juiy 21, 1953 J. J. ISELLA 5,

I SHEET sacs TRIMMER FOR PRINTING PRESSES mm Aug. 4. 1949 2 Sheet's=-Sheet 2 xmyxm I Fig. 6 Y r F'z'g. 8 2, 36

AusrlN muqsama chasm on the cylinder.

Patented July 21, 1953 SHEET EDGE TRIMMER FOR PRINTING PRESSES John J. Isella, North Haven, Conn., assignor to National Folding Box Company, Inc., New Haven, Conn., a. corporation of Connecticut Application August 4,1949, Serial No. 108,485

4 Claims. (01. 101-246) This invention relates to the art of making paper boxes from printed sheets of paperboard and relates particularlyto the machine operationsof printing and subsequent cutting and scoring of the printed sheets prior to separation of the sheets into individual blanks from which paper boxes are then formed.

' Aserious cause of waste in the production of paper boxes is mis-alignment of the cutting and scoring die with respect to the imprints on the sheet, as well as misalignment of the several imprints of multi-color blanks.

Nils-alignment is largely due to the difiiculty of clamping the sheets in identical manner in the several presses through which the sheets run. In some cases only one printing operation may be involved which is then followedby a cutting and scoring operation performed on a diiferent press. Zin such a case it is essential to clamp the sheet in the cutting and scoring press as accurately as possible with respect to the single color imprint. In the event the sheets are multicolored it may be necessary to run the sheets through two, or possibly more, printing presses and thereafter through the cutting and scoring press. In the latter casethe likelihood of misalignment is increased since mis-alignment in onlyone of the several presses may be sufficient to render the sheet unusable.

Printing presses as well as cutting and scoring presses are usually of the cylinder type and comprise a cylinder to which the sheets are clamped as they pass through the machine. A feeding mechanism feeds the sheets towards the cylinder where each sheet is arrested when its leading edge strikes one or several stops. A gripper mechanism then grasps the sheet near its leading edge and clamps it against the cylinder surface. The most commonly used form of gripper is a fingerlike device secured to an oscillating gripper shaft This shaft is usually mounted in a recess or trough at the periphery of the cylinder and generally extends parallel to the cylinder axis. Mechanism'is provided on the presses foroscillating this shaft in one direction in order to move the gripper towards the cylinder surface for clamping the sheet thereon, and in the opposite direction for releasing the sheet.

Due to the commonly employed high production rates the sheets hit the aforementioned stops with considerable impact causing the sheets to rebound. The amount of rebound is generally of the'order of zero up to of an inch, and occasionally greater. It is therefore easily understood that mis-alignment traceable to. rebound of the Observation has shown that the degree of rebound is not uniform for the same sheet in a series of presses through which the sheet passes, nor is it uniform for all the sheets passing through the same press.

Continued observation and experiments led to the conclusion, upon which this invention is based, that the degree of rebound is largely dependent on the physical characteristics of the leading edge of the sheet. Prior to this invention it has been common practice to use the raw edge of the sheet as a guide for aligning the sheet in the machine. If this edge was square little difiiculty was encountered. However, all the edges in a pile of sheets are not alike. Some edges are-square or nearly so and others are beveled. A square edge is likely to rebound further than a beveled edge which generally becomes deformed because it is too weak to withstand the impact.

The invention is based on the principle that rebound of the sheets is not objectionable in itself if it were possible to make the rebound substantially constant for all the sheets in all the presses through which the sheets run. The invention is'further based on the conclusion that the raw edge of the sheet cannot be depended upon for alignment purposes.

The invention eliminates the aforementioned alignment difficulties by providing on each sheet a cut alignment edge which is cut during the first printing operation. Since the alignment edge is cut on the printing press it bears a definite relationship with respect to the location of the im print, whereby alignment of the sheet in succeeding presses is greatly facilitated. Preferably the cut alignment edge is formed in such a way that no stock is removed from the sheet in the printing press itself and the sheets are then stacked and narrow strips of stock are then removed by stripping prior to feeding the sheets into the next press which, as hereinbefore mentioned, may be another printing press or may be the cutting and scoring press.

The invention'is equally applicable to cylinder presses of the flat bed type and to cylinder presse of the rotary type.

The aforementioned and various other objects,

features and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, how the invention may be carried out. r The invention also consists in certain new and original-steps as well as features of construction and combination of elements hereinafter set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects 3 and advantages, and the manner in which it may be carried out may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

Figure 1 is a cross sectional illustration on an'enlarged scale of the leading raw edge of a sheet;

Figure 2 is a cross sectional illustration on an enlarged scale of the edge of Figure 1 after deformation caused by striking a stop;

Figure 3 is a perspective view of a portion of the surface of a press cylinder showing a gripper shaft, grippers, and a cutting knife for cutting a square abutment edge on a sheet passing over the cylinder;

Figure 4 is a perspective view of a printed sheet :after cutting of the abutment edges;

Figure 5 is an enlarged plan view of the leading edge of the sheet prior to removal of a strip of stock which exposes the abutment edge;

Figure 6 is an enlarged plan view of the leading edge of the sheet after removal of the strip of stock to expose the abutment edge;

Figure '7 is a plan view of a mounted trimming knife for cutting the abutment edge; and

Figure 8 is a side view, partly in section, of a peripheral portion of a machine cylinder including the trimming knife, and the corresponding portion of a flat bed including a cutting plate cooperating with the knife.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be as generic in their application as the art will permit. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification certain specific disclosure of the invention is made for the purpose of explanation of broader aspects of the invention, but it is understood that the details may be modified in various respects without departure from the broad principles of the invention and that the invention may be practiced by other means and be applied to other structures than the ones shown.

A cross sectional view taken through the leading raw edge of a sheet frequently shows that the edge is not truly square with respect to the surface of the sheet. Figure 1 is an enlarged view of a typical raw leading edge l l of a sheet l2. It is evident that the edge l I does not have sufficient strength to Withstand without deformation an impact upon the stop which arrests the sheet prior to clamping of the sheet on the cylinder of a press.

It was previously mentioned that the sheets tend to rebound from the stop in varying degrees. It is plain that a square edge is likely to cause a greater amount of rebound because of its greater resistance to deformation than a beveled edge suchas shown in Figure 1 because some of the energy is used up in deforming the beveled edge which may then assume a shape as indicated at l I' in Figure 2.

According to the invention the leading edge of the sheet is trimmed during passage of the sheets through a printing press to provide a Cub edge which is square and bears a definite positional relationship with respect to the imprints produced on the sheet during passage of the sheet through the printing press.

Figure 3 shows a small portion of a press cylinder 13. The cylinder is provided with a trouglri 'or recess l 4 through which a gripper shaft I 5 extends. The gripper shaft I5 is pivotally mounted in the end walls of the trough, one such mounting being visible in the end walls [6 and H. Grippers [8 are mounted on the gripper shaft l5. Each gripper comprises a body member i9 from which an arm 20 extends. The gripper arm 20 bears down upon the cylinder surface 2| when the gripper shaft is turned in a counter-clock-wise sense. If the shaft 15 is turned in the opposite sense the gripper arms 20 are lifted off the cylinder surface to release the sheet previously held between the arms 20 and the cylinder surface 2|.

The reach of the arms 20 over the cylinder surface 2| is indicated as D and the position in which the leading raw edge of the sheet comes to rest is indicated at D.

The mechanism for oscillating the gripper shaft [5 is conventional and does not form part of this invention. It will therefore be sufficient to state that the shaft is oscillated periodically in a counter-clock-wise direction for gripping a sheet and in a clock-wise direction for releasing it.

Sheets are fed toward the cylinder in a substantially tangential direction as indicated by the arrow '22. The end of the sheet strikes a feeder stop 23 generally equipped with a deflector surface 2 3. The sheet rebounds from the stop a certain distance and is then engaged by the gripper arms 25 which clamp the leading portion of the sheet onto the cylinder surface 2|. The stop 23 may then be lifted by appropriate tilting of its arm to increase its clearance from the cylinder surface and may be dro ed again when the next sheet is fed towards it.

The trough Hi has a recess 26 within which a cutting blade if is mounted. The mounting of the cutting blade is also shown on an enlarged scale in Figure 7 and comprises two clamping plates 28 and 29 between which the blade 27 is held by friction. The blade is preferably shaped in the form of a shallow flat-bottom U. The fiat bottom portion 30 is straight and of substantial length. It may measure about 3 inches. The legs 3| of the U extend at an angle with respect to the fiat-bottom portion 30 and may be approximately /4 of an inch in length. The surface of the clamping plates 28 and 29 which face each other are shaped to fit the U-shape of the blade 21 and bolts 32 serve to clamp the blade between its plates 28 and 29 and to hold the knife assembly within the recess 26. The back of the blade rests against an abutment member 39 which sustains the cutting pressure of the blade.

It is apparent from Figure 3 that the flat bottom portion 33 of the blade 2? lies within the reach of the gripper arms 20 at a distance d from the edge of the trough. The legs 3| of th blade extend closer to the edge of the trough than the distance of the front surface of the stop 23 in the position of the cylinder with respect to the stop in which the sheet is clamped. U-shaped nicks in the edge of the blade lie at a distance from the edge of the trough greater than the edge of the sheet. The cutting edge of the blade severs the stock of the sheet with exception of two points 34 at the U-shaped nicks 40 where the stock remains uncut.

When, therefore, the protruding edge of the blade 27 cuts through the sheet no stock will be removed from the sheet l2, but a strip 33 severed by the cut 30, 3| will remain connected to the 0} sheet along the two relatively weak bridge points it as shown in Figure 5.

The cutting of the sheet. occurs as the cylinder i3 with the sheet clamped thereon rotates and contacts the counter member of the cylinder which may be another cylinder or a flat bed 35 as shown in Figure 8. The counter member carries the printing plates 35 and also carries a hardened striking plate 37 upon which the edge of the blade it! bears when cutting through the stock of the sheet on a cylinder. The sheet is not shown in Figure 8 for reasonsof clarity since it would obstruct the view of the knife 27. It is understood, however, that the sheet overlies the surface 2! extending towards the trough Hi and terminating with its raw leading edge a short distance beyond the nicks at in the knife blade 27.

A printed and cut sheet is is shown in Figure 4. The sheet bears imprints 38 of box blanks and has two cuts 39 near its leading edge 1 l, the

d printing sheets of paper, paperboard, and box board, the cylinder having a longitudinal recess in its cylinder surface, a gripper shaft mounted on said cylinder in said recess, finger elements on said shaft adapted to engage and clam onto the cylinder surface a sheet of paperboard, and a cutting lrnife mounted on the cylinder at said recess within the reach of said finger elements over the cylinder surface for cutting an abutment edge in sheets passing over said cylinder, the knife having the form of a shallow flat-bottom U, the bottom of the U lying substantially parallel tothe gripper shaft, the legs of the U terminating beyond the end position of the leading edge of sheets clamped against the cylinder surface by said linger elements, each leg having a nick in its cutting edge, whereby a strip is cut from the sheet at its leading edge, the strip adv hering to the sheet and being removable thereleading edge being shown in an enlarged plan view of Figure 5 which was previously described.

The printed sheets l2 are stacked in conventional manner prior to feeding of the sheets into thenext press, which, as hereinbefore stated may 1 be a cutting and scoring press or may be another printing press. While stacked, the cut edges 39 are exposed by removing the strips 33 therefrom. This causes the strips to tear cfi at the weak;

bridge point 3d. The stripped sheet then has the appearance as shown in Figure 6. The straight bottom portion 39' of the out has produced a square new abutment edge which bears a definite positional relation with respect to the imprinted blanks and serves to align the blanks in subsequent machine operations.

Since all the new abutment edges thus formed in all the sheets are alike, square, and equidistant from the initial imprints on each sheet any rebound which occurs in subsequent machine opl erations is so nearly uniform for all sheets as to eliminate the common rule-alignment errors experienced prior to this invention due to the nonuniformity of rebound of the sheets.

The invention thus eliminates effectively a common source of waste and annoyance without complicating the machin operations in any way. Existing machines may be converted at relatively little expense to embody and practice the invention.

What is claimed is:

1. In a cylinder printing press for printing sheets of paper, paperboard and box board, the press including a cylinder, a counter member for the cylinder including a printing plate on the 1 counter member, a stop for engaging the leading edge of sheets fed into the press, and gripper means for clamping the sheets to the cylinder, the improvement which comprises a pair of cutting elements on said cylinder and counter member o respectively, the cutting elements comprising a knife and a striking plate opposite said knife, the knife including a portion extending substantially parallel to the leading edge of sheets passing through the press, said parallel portion lying within that marginal portion. of the cylinder which is defined by the reach of said gripper means, whereby an abutment edge is cut at the leading margin of the sheet at a predetermined position with respect to the imprint on the sheet, said out abutment edge being adapted for positioning the printed sheet in subsequent machine operations.

2. A cylinder for cylinder printing presses for from by stripping.

3. A cylinder for cylinder printing presses for printing sheets or paper, paperboard, and box board, the cylinder having a longitudinal recess in its cylinder surface, a gripper shaft mounted on said cylinder in recess, finger elements on said shaft adapted to engage and clamp onto the cylinder surface a sheet of paperboard, and cutting irnife mounted on the cylinder at said recess within the reach of said finger elements over the cylinder surface for cutting an abutment edge in sheets passing over said cylinder, said cutting knife being substantially U-shaped, the bight of ii being flat and substantially parallel to the shaft, the legs of the U extending towards said recess, the spacing of the legs being less than the space between the finger elements between which th knife is mounted.

A cylinder for cylinder printing presses for printing sheets of paper, paperboard, and box board, the cylinder having a longitudinal trough in its cylinder surface, a gripper shaft mounted on said cylinder in said trough, finger elements on said shaft adapted to engage and clamp onto the cylinder surface a sheet of paperboard, said trough including a recess extending further into the cylinder surface than the remainder of the edge of the trough over which said finger elements extend, a pair of clamping plates mounted within said recess, and a cutting blade clamped between said clamping plates in a position substantially radial with respect to the cylinder axis and between, and within the reach of, said finger elements over the cylinder surface for cutting an abutment edge in sheets passing over said cylinder.

JOHN J. ISELLA.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 747,695 Gay Dec. 22, 1903 972,390 Vavra Oct. 11, 1910 1,4 8,48l Sherman June 6, 1922 1,579,180 Thayer Mar. 30, 1926 1,668,258 Adsit May 1, 1928 1,977,556 Eclrhard Oct. 16, 19 4 2,934,259 Price Mar. 17, 1936 2,098,165 Riggenbach Nov. 2, 1937 2,225,529 Beall Dec. 17, 1940 2,28l,5 7 Haynes May 5, 1942 2,418,067 Barnes et al. Mar. 25, 1947 2,467,973 Gannon et a1 Apr. 19, 1949 2,469,526 Sloat May 10, 1949

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