US3166012A

US3166012A - Coacting cylinders having skewed gaps to maintain balanced pressure contact

Info

Publication number: US3166012A
Application number: US218587A
Authority: US
Inventors: Hantscho George
Original assignee: HANTSCHO CO GEORGE
Current assignee: GEORGE HANTSCHO COMPANY Inc; HANTSCHO CO GEORGE
Priority date: 1962-08-22
Filing date: 1962-08-22
Publication date: 1965-01-19
Anticipated expiration: 1982-01-19

Description

HANTSCHO Jan. 19, 1965 3,166,012

COACTING CYLINDERS HAVING SKEWED GAPS T0 MAINTAIN BALANCED PRESSURE CONTACT Filed Aug. 22, 1962 2 Sheets-Sheet 1 INVEILITOR aaegs film/r9090 Jan. 19,1965 :5. HANTSCHO 3,166,012

7 COACTING CYLINDERS HAVING SKEWED GAPS T0 MAINTAIN BALANCED PRESSURE CONTACT Filed Aug. 22, 1962 2 Sheets-Sheet 2 M p i i A 22 b V T 3 E +40a 11 1 l I BLANK 20M: 2.? j T'1. \'!'II +:J-L'T Q L i I I l l f,

{We P1 944061 INVENTO R gray/s H4A/zra/a United States Patent pp 3,166,012 COACTING CYLINDERS HAVING SKEWED GAPS T MAENTAEN BALANCED PRESSURE CONTACT George Hantscho, Tuckahoe, N.Y., assignor to George Hantscho Company, Ina, a corporation of New York Filed Aug. 22, 1962, Ser. No. 218,587 1 Claim. (Cl. 1ll1220) The present invention relates to improvements in offset printing apparatus.

3,166,012 I Patented Jan. 19,1965.

cooperative transfer or blanket cylinders throughout conketed transfer cylinders having narrow blanket securing In the offset printing processes as carried out in multistage web presses, the equipment for each printing stage or station includes a pair of inked plate cylinders, each carrying matter to be printed on the two sides of the paper web, and offset or blanket cylinders for transferring the ink images from the plate cylinders to the paper in the desired registry. The transfer surfaces on the offset cylinders are provided by sheets or blankets wrapped about the cylinders and secured thereto by suitable clamping means disposed in transverse slots extending throughout the lengths of the rollers. During the actual printing operation, the two blanket cylinders also serve as backing or impression cylinders each for the other, the moving web engaging both in a common narrow transverse contact zone so that both sides of the paper are printed at the same time. The two blanket cylinders are phased so that theblanket joints of both revolve through the common zone and in registry with the spacing or transverse border area between successive printings or signatures.

It is recognized that for best results in multiple impression work, and particularly multi-color printing, precise registry of successive overlying images is required, calling inrturn for extreme accuracy in spacing and timing between and throughout the apparatus and prevention of slip between the paper and the printing rollers. One difficulty that has been encountered concerns the gaps in the blanket surfaces created by the means for fastening the blankets to the blanket cylinders. These gaps, which are necessarily of significant width and which as hitherto practiced are phased to pass through the printing zone in simultaneous axial registry with each other, cause a momentary release of the gripping pressure hetween the cylinders and permit some. slip to occur, To alleviate this tendency, means have been proposed to create friction between the web and the blanket rolls outside the printing zone, for example, by tilting the tangential plane of the printing zone out of registry with the normal plane of the paper web advancing through the machine, thereby causing frictional wrapsof the web about the blanket cylinders before and after passage between the latter. However, in addition to repeated undesirable distortions of the inked or partially inked web from the accurate ideal of straight tangential progress throughout the various units of the press assembly, such supplementary measures in general rely for frictional grip on a small component of the tension of the web itself, which does not alter the fact that the accurate and powerful pressure grip of the blanket cylinders is still interrupted by passage of the straight transversely aligned blanket gaps irrespective of the tangential plane of the print zone.

One object of the present invention resides in the provision of an improved offset printing apparatus adapted to maintain uninterrupted compressional gripping pressure on a receiving web passing between a pair of cooperative blanket cylinders throughout continuous passage of the web between the cylinders. V

Another object resides in the provision of an improved offset printing apparatus adapted 'to exert uninterrupted gripping pressure on a web moving between a pair of joints extending transversely in circumferentially skewed relation to the axes of their respective cylinders, the cylinders being so rotarily timed as to cause the two blanket joints to pass through the tially the same time. i a

A further object resides in the provision of printing rollers in which the directions of skew of the roller gaps or slots are such as to. permit the two gaps to pass through the tangential zone in substantially crisscross relation.

A further object resides in the provisionof printing. rollers in which the directions of skewof the roller gaps or slots are such as to permit the two gaps to pass through the tangential zone in substantial correspondence throughout. i

A further object is to provide improved offset printing apparatus for continuous web printing including a plurality of successive printing units each having a'pair. of

zone of tangency at substancooperative transfer cylinders adaptedmutually to maintain uninterrupted gripping pressure on the web. during the entire passage of the web between them, whereby slip betweenthe web and the units'is preventedthroughout the printing succession.

In the drawings: a FIGURE 1 is a vertical sectional view of a typical pair of blanketed transfer cylinders as applied in a preferred form of the invention. l FIGURE 2 is a diagrammatic illustrationof a multiple unit press embodying the invention.

FIGURE 3 is a simplified perspectiveview of a, transfer. cylinder illustrating the skewing of the blanket joint.

FIGURE 4a is a front'elevation of a pair of cooperative offset or transfer cylinders illustrating the blanket joints as arranged for intersecting. or crisscross operation.

FIGURE 4b is a plan View of the web showing in dotand-dash development the paths of the blanket joints as they pass through the tangential zone.

across the web when the latter is passed betweencylinders with joints skewed as in FIGURE .4a.

FIGURE 5a is a view similar to FIGURE 4a but illustrating the blanket joints as arranged for correspondence FIGURE 5b is a plan view of the, web showing the.

as blanket gap widths and angles of skew have inmost part been exaggerated in order to. showproperlytheir relationship within the invention. 'EIG. 6 serves to illustrate the fact that in practice these factors, may involve relative dimensions too, small to exhibit the relationships clearly when drawn to the necessary small scale. i i

Referring to FIG. 1, the

numerals

20 and 21 generally denote parallel upper and lower rotary offset or transfer cylinders adapted to compressionally engage a paper web 22 in a common narrow zone of tangency T andto transfer ink images to the top and bottomfaceslof the web respectively from upper and lowerplate or type cylinders 24 and 25 'in the usual offset printing manner. The upper transfer cylinder structure '29 includes a basic cylinder 26 upon which is wound a peripheral blanket 27 which'provides the actual transfer surface, thelower. cylinder structure 21 similarly including a basic cylinder 28 carryinga blanket- 29 The ends of the

blankets

27 and 29 are secured in transverse slots or recesses 35 and 31 in their respective basic cylinders; The clamping of the blanket ends within the slots may be accomplished by any, suitable means such as the structure illustrated, which being per se well known in the ant need only be briefly describedas typically applied to blanket 27.-

The respective opposite ends of the blanket are clamped between pairs of narrow bars at 32 and. 33. One of the sets of clamping bars 32-is retained in a suitable groove 34 in the Wall of the recess 36, while the second set .33 is held in a rotatably adjustable cylindrical clamping member 35 journalled in a transverse block 36, the block beingsecured in the basic cylinder by screws 37 and forming in effect an integral portion thereof upon assembly. In set-up, turning the member 35 clockwise causes the latter to stretch the blanket 27 and hold it inf firm peripheral engagement with the basic cylinder, 26 In such position theclamping member is-locked at the ends of the cylinder by means which, as previously noted, are

. well known in the art and accordingly require no detail description herein. Similarly, as the construction and operation of the'clamping means for the lower blanket 29 is. the same asthat described for the upper structure except for rotational direction, further detail description of the lowerstructure is omitted .as'undulyrepetitious.

It will benoted, however, that the necessary clearance between the end portions of the upper blanket 27v on emergence from the clamping recess 30creates a narrow gap,39-in the true peripheral surfaceof the blanketed cylinder, this'gap extending throughout the width of the blanket. A similar gap 40 exists in the case of the lower blanket 29. It. has been the presence of'such gaps extending across the blanket surfaces in parallel with the cylinder axesas in the prior art, which has caused the interruption of compressive gripping pressure on the web and consequent slippage as previously noted. The manncr in which the present invention eliminates this difli-' cultyis as follows: i f I V 7 Q I Referringito FIG. 3, which depicts. the upper blanket cylinder 20, it will be seen that the gap 39, instead of extending across the blanket in parallel with the cylinder axis A, is-circumferentially.skewcd so that one edge of the gap subtends a peripheral arc B ofuninterrupted' peripheral surface at the rear side. of the blanket 27, this cylinders always remain in mutual compressive relation with the web 22. Thus in the central position illustrated in FIG. 4b, the mutual pressure areas extend inwardly for equal distances D from the edges of the web. As the web continues to move through the zone T, the compressive pressure shifts from the outer areas to the central portion of thefcrisscross pattern, the shift oc- 1 curring in overlapping relation so that no release can occur. It will be obvious that a similar overlapping shift has occurred inreve'rseorder during the entry of the gap combination to the zone T. Thus, it will be seen that the invention provides a plurality'of operationally overlapping gripping pressure areas spanning the entire passage of the

gaps

39 and 40 through the. zone T,

subtended surface tapering in a triangular area C 'to I the front side of the blanket. Similarly, the other edge of the gap subtends a second surface triangle C tapering to the rear side of the blanket. 1

The peripheral extent of each arc B (defined of course by the width of-blanket-andthe angle of skew) issuch that throughout. the combined peripheral extent of the i blanket parallel to the cylinder axis A without encountering one or both of the triangular areas C and 0 In other wordsythe zone T at all times includes a portion of uninterrupted peripheral blanket surface, so that the triangular areas may appropriately be termed continuity triangles. a

Referring to FIG. 4a, which shows the front or in-feed aspect, the gaps .39 and 40 appearcanted in the'same' direction, though operationally they areskewed inoppo site directions due to the opposite rotation of their respective cylinders, so that as they pass 'conjunctively through the pn'ntzone .T, they encounter theweb 22 .two arcs B, no;narrow zone T can extend across the maintaining continuity of compressive grip on the web.

.22 at all times and thereby preventing any possible slip.

The apparatus is so phased that the passage of theblanket joints takes place in registry with the desired blank'zone. 23 on the webbeing printed. i In the alternative-arrangement shown in FIG. 5a,. the joint gaps 39 and 4%) are skewedin the same operational direction so as to pass through the zone T in correspondence, generating the single sloping pattern 39a-40a illustrated in FIG. 5b. The operation of this embodimentis thev same as that described above except that the overlapping shift of compressive pressure application along the zone T takes place from a single decreasing area E extending inward from one'edge of the web 22 to a similar but increasing area E extending inward from the opposite edge. Obviously this arrangement effectively maintains the continuity of compressive gripping pressure with consequent preventionof slip in the manner set forth.

I As previously noted, the angles of skew have been necessarily illustrated in exaggerated aspect for purposes of clarity in explaining their essential part in the invention. In practice these angles, which for any given installation are functions of thegblanket breadth, gap width and Width of the contact or printing zone T, are quite small, as illustrated by angle Q in FIG. 6. The width of T, which is theynarrow flattened tangential area in'which the blanket cylinders engage. therweb 22, is of course, de-

pendent on the 'cylinder diameters, the applied pressure,

'may be in the order of .3 degree, while fora 48-inch blanket, the skew angle may be significantly smaller.

The extreme smallness of the required skew angles is an advantage in manufacture, allowing the clamping means to be mounted directly-across the basic cylinders-while confining the skewing to the lips of the clamping recesses, though obviously the illustrated clamping means or their equivalent may also be incorporated in skewed position, if desired. The skewed gaps may similarly be formed either helically or as straight lines, the smallness of the peripheral'angles making the two virtually identical.

' From the foregoing description throughout, it will be evident that by the introduction of the skewed clamping gaps in the operational combination set forth, the invention achieves with maximum simplicity anew and highly in the crisscross pattern illustrated in phantominFIGi 4b. Since both the upper and lower skewed gaps subtend pairs of continuity triangles as explained in; connection With FIG. 3, various periph'eral areasof the two blanket useful improvement in the offset printing art, i.e., the maintenance of uninterrupted gripping pressure on a moving web by the blanketeditransfer cylinders themselves within the contact or print zone, eliminating requirement for any other anti-slip provision and rendering the com bmation particularly well adapted to such advantageous straight tangential multi-unit installations as that diagrammatically illustrated in FIG. 2, though obviously not as the result of the momentary release of pressure between cooperating rollers.

Thus, while the invention has been set forth in preferred form, it is not limited to the exact embodiments illustrated, as various modifications may be made Without departing from the inventive concept within the scope of the appended claim.

What is claimed is:

In an offset web printing press, in combination, a blanket transfer cylinder including blanket-securing means establishing a transverse gap joint in the peripheral blanket surface of said cylinder, a second blanket transfer cylinder disposed in tangential parallelism with said first cylinder and establishing mutually therewith a contact zone of compressive gripping pressure on a web passing between said cylinders, and blanket-securing means establishing a transverse gap joint disposed in the peripheral blanket surface of said second cylinder and orientated to move through said contact zone conjunctively with said first gap joint, said transverse gap joints being peripherally skewed with respect to the axes of their respective cylinders at predetermined operationally opposite directional angles, said skewed gap joints move through said contact zone in crisscross relationship producing mutual pressure areas extending inwardly from opposite sides of the web and which areas increase as the central contact area decreases until the gaps are in centered crisscross relationship in the contact zone whereupon said central contact area increases as the side pressure areas decrease thereby effecting a balanced gripping pressure on said web as the gaps move throughthe contact zone.

References Cited in the file of this patent UNITED STATES PATENTS Johnson May 30, 1961