US1812920A - Doctor blade - Google Patents

Description

July 7, 1931. E. s. BALLARD DOCTOR BLADE 2 Sheets-Sheet l Filed May 24, 1930 July 7, 1931. 5, BALLARD 1,812,920 I DOCTOR BLADE Filed May 24, 1930 Z SheetS-Sheet 2 I AT fia/Zma W WQW Patented July 7, 1931 UNITED/STATES PATENT OFFICE ERNEST S. BALLARD, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO STANDARD PROCESS CORPORATION,

OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE DOCTOR BLADE Application filed May 24, 1930. Serial No. 455,373.

The present invention relates to an improved construction of doctor blade for roto gravure and similar printing presses.

As is Well known, it is the practice in rotogravure and similar printing to cause the cylinder to dip into an ink receptacle so that a quantity of ink will adhere to its surface, and to remove the surplus ink from the printingcylinders which revolve within an ink pan by means of a blade-like member known as a doctor blade. The means at present generally utilized for this purpose consists merely of a blade extending lengthwise of the cylinder and generally capable of being moved toward and from the cylinder, the edge of the blade being yieldingly pressed intoengagement with the cylinder bymeans of pressure tending to bodily move the blade itself. Such pressure in most instances is provided by. means of weights that tend to bring the edge of the blade into firm.

contact with the cylinder by flexing the blade lengthwise. With this arrangement the applied pressure frequently is sufficient to cause the flexible blade to bow or assume an arcuate form, if the blade is inherently sufliciently flexible, so that it will present a satisfactory wiping edge to a cylinder, the surface of which does not present a perfectly straight line. When the blade assumes such form it does not present a satisfactory wiping edge and the relatively great pressure increases the danger of cutting the cylinder. And if the inherent flexibility of the blade is reduced to avoid theobjection just stated, the blade becomes too stiff to readily conform to the cylinder surface resulting in an uneven and, accordingly, unsatisfactory removal of the surplus ink. Furthermore, unless the blade is flexible to a high degree particles of grit may collect beneath the blade scratching the cylinder. Such grit particles will simply be carried by a truly flexible blade without damage to the cylinder.

blade should be just as flexible as possible,

'consistentwith' adequate strength, in order In order to function perfectly the doctor surface be not truly cylindrical. This invention aims to secure such flexibility by the utilization of a very thin blade adapted to bear against the cylinder by pressure applied adjacent the edge of the blade itself, in a manner so as not to cause longitudinal flexing of the body of the blade, so that the blade curves sufficiently to accommodate itself to the cylinder surface under such pressure without causing the blade to tend to cut the cylinder.

The primary object of the present invention accordingly, is to provide an improved doctor blade construction for rotogravlire and similar printing press cylinders whereby the above enumerated objections to existing constructions of this character are substantially eliminated.

It is 'a' further object of the invention to provide a doctor blade construction for printing cylinders comprising a relatively thin wiping blade, and means yieldabl'y urging said edge of such blade into pressure wiping contact with said cylinder without deformation of the body of the blade.

It is a still further object of the invention to'provide a doctor' blade construction for printing cylinders comprising a thin wiping blade, and adjustable yieldable means engaging said blade adjacent its edges so that said blade is pressed into yieldable effective wiping engagement with said cylinder with out pressing the blade as a unit against the cylinder.

A still further object of the invention is to provide a doctor blade construction for printing cylinders comprising a highly flexible wiping blade and means engaging the blade at a multiplicity of points adjacent its edge and urging said blade into wiping en-' gagement with said cylinder by separately applied pressure against various very closely spaced portions thereof.

A still further object of the invention is to provide a doctor blade construction for printing cylinders comprising a very flexible wiping blade, and a secondary blade having a serrated edge engaging said wiping blade closely adjacent the-wiping edge thereof, and means for exerting pressure on said secondary blade for urging the edges of said wiping blade into complete wiping engagement with said cylinder substantially independently of the mounting of the doctor blade.

With the above objects in view as well as others that will become apparent during the course of the following disclosure reference will be hadto the accompanying drawings forming part of same and wherein:.

Figure 1 is a side elevational view of the improved construction in accordance with a preferred embodiment of my invention.

Figure 2 is a plan view of the Supplemental or pressure blade.

Figure 3 is a top plan view of the doctor blade slide with the wiping or doctor blade proper operatively connected therewith, the supplementary or pressure blade being omitted for clearness of disclosure.

Figure 4 is a view similar to Figure 1 disclosing a modified embodiment of the invention.

Referring to the drawings by reference characters in which like characters designate like parts, 11 designates a printing cylinder of usual construction rotatably journaled in the usual frame 12 with a portionof thecircumference thereof at all times disposed within an ink pan 13 in which, according to common practice, a quantity of ink is held, whereby the printing surface of cylinder 11 is completely inked upon continuous revolution of same in well known manner. The improved doctor blade arrangement with the ink eliminator constructed in accordance with the present invention comsaid opposite end has detachably secured thereto,by means of a nut 22, a hand crank 23 whereby upon turning crank 23 each carriage 16 can be advanced toward or away from cylinder 11 for a purpose hereinafter referred'to. 'If desired both screws 19 can be connected bya shaft and bevel or similar gears utilized for simultaneous rotation in which event only one of the screws 19 need be provided with a hand crank so that carriages 16 .can be simultaneously adjusted by turning one crank handle from one side of the press. Y

Disposed within grooves 17 of the carriages 16 are the opposite edges of the doctor blade slide 25 which is preferably oscillatable parallel with cylinder 11 in well high flexibility. The blade 31 is supported U in such manner that it is disposed at a relatively sharp or acute angle to a tangent to the surface of cylinder 11 with the free edge thereof in wiping contact with the cylinder, which cylinder revolves in the direction indicated by the arrow in Figure 1.

The blade 31 through the weight of support 28 will normally contact the surface of cylinder 11 but with insuflicient pressure to have the necessary wiping action and with insuflicient pressure to cause the blade to flex longitudinally. The blade 31 in accordance with the present invention is constructed of such thin material that it would not withstand direct pressure thereto, in accordance with present practices and besides such pres sure if applied, as before stated, would defeat the desirable extreme flexibility of the free wiping edge of blade '31 because it would bow the blade longitudinally. According to the present invention means for maintaining the edge of blade 31 in full wiping contact with cylinder 11 while maintaining the high flexibility of said blade are provided. .Such means comprises a supplementary or pressure blade 34 preferably supported independently of the wiper blade. One edge of the pressure blade is detachably supported by means of bolts 35 between the sections 36 and 37 of a clamp support 38, which support is provided With terminal lugs 39, that are fixed to a shaft 40 extending through apertures therein and which shaft is rotatably journaled in brackets 41 carried by the opposite ends of slide 25. The free edge of blade 34 is serrated or slit at relatively close intervals, as indicated at 42, in Figure 4, thus providlng a multiplicity of individual spring fingers 43 for contacting blade 31 closelly adjacent the free wiping edge thereof. t may be noted that it is desirable that blade 34 be substantially heavier and stiffer than blade 31 because of the pressure applied thereto in a manner about to be described. By the provision of the yieldable fingers 43 a highly flexible edge is provided even though blade 34 be constructed of heavier material. Secured to one end of shaft 40 is a ratchet wheel 44 to the periphery of which is secured a handle 45, whereby shaft 40 can be rotated throu h wheel 44 upon manual movement of hen le 44 is maintained in shaft 40 through v to separately is readily adjustable 45 for applying pressure to blade 34. Wheel I any adjusted position pressure by engagement a pawl 46 pivotally secured at with the desired therewith of '47 to an extension 48 of one of the brackets y In the construction just disclosed the portions of the edge of a highly flexible wiping blade 31 are separately maintained in pressure engagement with the surface of cylinder 11 re ardless of any inequalities therein because t e yieldable fingers 43 on blade 34 will individually yield to any inequalities in the cylinder surface opposite certain of them while at the same time they place suflicient pressure on the cylinder contacting edge of blade 31 to cause an even wiping action. The amount of pressure of the separate fingers can be readily regulated by rotating handle 45.-

From the foregoing disclosure it will be seen that a novel doctor blade construction is provided comprising a highly flexible cylinder surface wiping edge, including means apply pressure to closely spaced portions of the wiping edge without at the same time applying pressure to the body of the doctor blade, so that said edge is yieldingly in complete surface engagement with the cylinder, and that the pressure is maintained by pressure means operatively associated with the doctor' blade so as to not affect the blade as a whole. It will also be observed that the pressure means for subjecting the flexible wiping edge to effect thorough wiping of the printing cylinder without reducing the effectiveness of the wiping edge. a

While I have disclosed fingers 43 as the preferred ing blade 31 in yieldable spring means for holdyieldable pressure enga ement with cylinder 11, it is obvious that t e pressure may be obtained by various forms of individual springs or by means of an inflated rubber tube mounted to bear adjacent the free edge of blade 31, for example, the main consideration being that the edge of flexible blade 31 be pressedinto wiping engagement with cylinder 11 by pressure means which are highly flexible lengthwise of said wiping edge and will not substantially affect. the body of the doctor blade. This arrangement permits the use of very flexible blades that will readily yield in conformity to any variations from a true cylinder in the printing form.

While the means above disclosed are at present preferred for placing blade 34 under pressure, the supplemental blade 34 may be subjected to ressure b means similar to that now use but app ied directly to the doctor blade. Such means are illustrated in Figure 6, wherein blade 34 is supported by a clamp 61 carried on a shaft 62 journaled suflicient pressure to.

in brackets 63 of slide 25. The clamp 61 is provided with an arm 64 to the free end of which is secured a rope or cable 65, which passes around pulley 66 and has secured to the free end thereof a weight 67 for subjecting blade 34 and fingers 43 carried thereby to pressure for holding blade 31 in yielding pressure wiping engagement with cylinder 11. The weights 67 are removable whereby the pressure on blade 34 may be varied according to the number of weights supported by cable 65.

he invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

\Vhat I claim and desire to secure by United States Letters Patent is:

1. In combination with the doctor blade for a printing press, of means to cause said blade to yieldingly contact with the printing form comprising independent yielding elements engaging the blade at closely spaced points along the length and adjacent the edge thereof that' contacts said form.

2. In combination with the doctor blade of a printing press, means to cause said blade to yieldingly contact with the printing form, comprising a blade carrying a multiplicity of Independently yieldable spring fingers engaging the blade at relatively closely spaced points along the length and adjacent the edge thereof that contacts with said form. v 3. In combination a doctor blade support for a printing press, a flexible doctor blade pivotally mounted in said support, and means to cause said blade to yieldingly contact with the printing form comprising an independently pivotally mounted blade embodying a multiplicity of separate s ring fingers arranged to engage the bla e at points along the length and adjacentthe edge thereof that contact with said form.

4. In combination, a support for the doc tor blade of a printing press, a relatively highly resilient doctor blade pivotally mounted on said su port so that it contacts with the printing form at an acute angle to a tangent drawn from the point of contact in a direction opposite to the direction of rotation of the form, and means to cause said blade to yieldingly contact with the printing form comprising an independently mounted member carrying a multiplicity of spring fingers contacting with the doctor with " thereof cent the edge thereof that contacts with said form, said spring fingers serving to independently yieldingly urge various portions of the blade against the form.

5. In combination, a support for the doctor blade of a printing press, a relatively highly resilient doctor blade pivotally mounted in said support and biased toward a printing form by a component of the weight of the blade and its mounting, and means to supplement 'the pressure of the doctor blade of the printing form comprising independently yielding spring fingers' engaging the front of the blade at points along the length and adjacent the edge that contact With-said form, said spring fingers being so mounted with respect to the blade as to apply yielding pressure to v the edge of the blade without tending to cause t e blade to flex bodily in a direction longitudinal to the form.

6. In combinat'on, a support for the doc tor bladeof a printing press, a highly re silient doctor blade mounted on said support and meansto apply a yielding pres-' sure to the edge of the doctor blade, said means comprislng a'blade-like element pivotally mounted on said support, said bladelike element being provided'with a multiplicity' of. spring fingers arranged to contact with said doctor blade adjacent the operative edge thereof.

7. The combination defined in claim 6 in which said blade-like element is provided with means to supplement the action of said spring fingers, said means being adjustable.

'8. The combination defined in claim 6 in which said blade-like element is arranged so as to present an acute angle with said doctor blade, so that the spring fingers exert a pressure against the blade in a direction to cause it. to yieldingly contact with the printing form without substantially restricting the yieldability of the blade in conforming to the surface of said form.

9. The combination defined in claim-6 in which said support is mounted for slidable adjustment toward and from the printing form.

10. In combination with the doctor blade of a printing press, of means to apply yielding pressure to said blade comprising an element contacting only with said blade im--- mediately adjacent its operative edge, so as element being inherently readily yieldable at all points thereof at which it contacts with said edge.

11. The combination defined in claim 10 in which said element comprises a flexible.

and resilient blade slit at relatively closely spaced intervals to provide a multiplicity of resllient fingers.

12. Means to apply yielding pressure tothe operative edge of the doctor blade of a.

' to apply said pressure at said edge, said

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