Light weight intaglio printing press

Information

  • Patent Grant
  • 6216590
  • Patent Number
    6,216,590
  • Date Filed
    Wednesday, March 1, 2000
    24 years ago
  • Date Issued
    Tuesday, April 17, 2001
    23 years ago
  • Inventors
  • Examiners
    • Colilla; Daniel J.
    Agents
    • Robbins; Daniel
Abstract
The present invention employs a light weight fixed bed to support an intaglio plate, and discloses a print roller mounted on a movable trolley which is advanced across the intaglio plate causing the pressure of the print roller to effect the printing. The trolley is fabricated from light weight beams substantially forming the sides of a hollow box beam, and the print roller is stiffened by support of intermediate rollers tied to a trolley beam. This precludes the print roller from flexing under the load presented by the intaglio plate and the associated paper and felt material as the print roller under pressure traverses the plate. This allows the use of a lighter, smaller diameter print roller. Handwheels attached to the trolley provide spring loaded pressure to control the pressure of the print roller on the intaglio plate assembly. The trolley is driven across the bed and plate by a manually operated external drive wheel, which causes the print roller to rotate under pressure across the plate effecting printing as it rolls. Below the bed of the table is a lower roller attached to the trolley and circumfirentially in contact with the lower bed face. This roller provides support to the underside of the fixed bed to prevent its flexure under the pressure of the print wheel pressing on the plate assembly at the upper surface of the bed. Also supporting this lower roller are intermediate rollers secured to the horizontal lower trolley beam.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to a printing press, and in particular to a press for intaglio printing, including printing of etchings and engravings.




2. Description Relative to the Prior Art




The art of intaglio printing dates back at least to the 15th century, where it was practiced by such well known artists as Rembrandt and Durer. It has developed over time and continues as a method of graphic artistic expression to the present.




The forms of intaglio printing are characterized by having the art work incised on a flat plate (i.e., a printing block plate); either into a ground layer covering the plate or into the surface of the plate itself. The plate surface used, and the means of forming the lines of the print determine the actual classification of the work. However, all intaglio processes involve filling the incised lines of the plate's finished drawing with ink, and carefully removing all remnants of ink from the flat, uncut surfaces of the plate. The plate is then covered with an appropriately wetted print paper (i.e., print fabricating material) which is in turn covered with resilient layers of material such as felt, and then run through a press which applies pressure to the felt and paper forcing it down into the inscribed lines of the plate so that ink is picked up and transferred to the paper.




Because paper fibers must be forced down into the lines and grooves of the inked plate to effect the ink transfer, large forces, uniform across the width of the plate, must be applied to the felt/paper layers as they traverse the press. Presses of the prior art utilize a fixed structure on which is mounted a massive movable bed onto which the plate is laid for printing. The bed is generally propelled by a lower driven roller which causes the plate to move on auxiliary rollers along the length of the table carrying the plate beneath the fixed print roller. The print roller, supported on end bearings fixed in heavy brackets secured to the table, is pressed down onto the felt/paper layers with pressure sufficient to effect the ink/paper transfer as the bed is rolled along the table in a plane parallel to, and at a fixed distance from, the print roller axis, by an appropriate motive means. In the prior art, the print rollers have been substantial steel cylinders with diameters of from 4″ and up, and the lower rollers consisting of steel cylinders with diameters of from 3″ and up. These heavy rollers are used to provide uniform pressure and to maintain straightness and parallelism over their full widths of the bed from 12″ to several feet, and require heavy, rigid support structures. The bed itself must be weighty to resist flexing under the printing forces. Thus the intaglio press of the prior art is a heavy and unwieldy structure. The present invention provides performance equivalent to that obtainable by the presses of the prior art, but with a substantial reduction in complexity and weight.




SUMMARY OF THE INVENTION




Rather than using a heavy bed to support an intaglio plate and moving the bed and plate under a fixed print roller, the present invention teaches using a lighter weight fixed bed to support the intaglio plate and mounting the print roller on a movable trolley which is advanced across the intaglio plate causing the pressure of the print roller to effect the printing. The trolley is fabricated from light weight beams substantially forming the sides of a hollow box beam, and the print roller is stiffened by support of rollers tied to a trolley beam and in contact with the print roller at several intermediate points. These intermediate rollers, fixed to the upper beam, preclude the print roller from flexing under the load presented by the intaglio plate and the associated paper and felt material as the print roller under pressure traverses the plate. This allows the use of a lighter, smaller diameter print roller, and further reduces the weight and complexity of the print roller support assembly. Handwheels attached to the trolley provide spring loaded pressure to control the pressure of the print roller on the intaglio plate assembly. The trolley is driven across the bed and plate either by a manually operated external drive wheel or a geared motor, which causes the print roller to rotate under pressure across the plate effecting printing as it rolls. Below the bed of the table is a lower roller attached to the trolley and circumfirentially in contact with the lower bed face. This roller provides support to the underside of the fixed bed to prevent its flexure under the pressure of the print wheel pressing on the plate assembly at the upper surface of the bed. Also supporting this lower roller are intermediate rollers secured to the horizontal lower trolley beam to further provide uniform pressure and structural support during the printing process.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will be described with respect to the drawings of which:





FIG. 1

is a cross-sectional drawing of an end view of the press of the invention,





FIG. 2



a


is a cross-sectional drawing of a prior art mechanism for applying pressure to a print roll,





FIG. 2



b


is a plot of the pressure v. screw position for the mechanism of

FIG. 2



a,







FIG. 3

is a drawing of a side elevation view of the trolley that is part of the press of the invention,





FIG. 4

is a plot of the pressure v. screw position for the screw mechanism of the invention,





FIG. 5

is a plot of the pressure v. screw position for the screw mechanism of the invention for a dual action spring,





FIG. 6

is a drawing illustrating the screw mechanism of the invention with a dual action pressure generating spring,





FIG. 7



a


is a partial elevation drawing of a pressure indicator for measuring the force applied by the print roller onto the intaglio plate, and





FIG. 7



b


is a partial drawing of the scale of the pressure indicator of

FIG. 7



a


shown rotated through 90 degrees relative to

FIG. 7



a.













DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring to

FIG. 1

, the press


10


of the invention consists of a fixed table structure


12


having an attached top flat bed


14


extending the full width and full length of the table


12


, and fixed to it. In the process of printing an etching or engraving, an incised intaglio inked plate (not shown) will be secured to the bed


14


in a fixed position with its top surface overlaid with the print paper and a resilient felt blanket. Pressure onto the felt blanket provides the forcible contact between the paper and the incised plate. Along the width edges of the bed's


14


top surface are rigid sides


16


extending downwards, and attached to these sides


16


are inwardly facing platforms


18


extending the length of the table


14


. A print roller


20


, not fixed relative to the table structure


12


, is part of a trolley assembly


22


whose travel across the bed


14


drives the print roller


20


over the stationary inked plate/paper/felt assembly positioned on the flat bed


14


.




The trolley


22


has two vertical box like members


28


,


30


that form the sides of the trolley


22


, and an upper beam


24


, and lower beam


26


that form the top and bottom of the trolley


22


. Referring to

FIG. 1

, the side members


28


,


30


are positioned alongside the rigid sides


16


of the table top


12


, and the trolley is completed by the upper cross beam


24


tying the box members


28


,


30


together at the top end of the trolley,


22


, i.e. above the bed


14


, and the lower cross beam


26


tying them together at the bottom end of the trolley, i.e. below the bed


14


. Thus the structure of the trolley


22


is substantially a hollow-like box enveloping the table


12


. Attached to the vertical member


30


are two roller bearings of which only one,


34


, is seen in

FIG. 1

, and to the vertical member


28


to be attached are two roller bearings


32


,


33


, of which only one,


32


, is seen in

FIG. 1

, which bear against the rigid sides


16


of the flat bed


14


and transversely guide the trolley


22


while it rolls the length of the table


12


. Additionally, fixed to the upper surface of the lower beam


26


are the inner rings of radial bearings


48


,


50


whose outer races ride on the fixed platform


18


, which support the lower portion of the trolley


22


. (Corresponding bearings, of which one,


51


, is seen in

FIG. 3

are in mirror image positions relative to the bearings


48


,


50


.)




The print roller


20


extending the width of the flat bed


14


is mounted in bearings


47


,


49


secured to the trolley's vertical members


28


,


30


so that the print roller


20


rides with the trolley


22


. As will be explained below in connection with the operation of the pressure generating handwheels


40


,


42


, pressure is applied downwardly at the ends of the print roller


20


to uniformly force it across the felt blanket covering the paper which is to be printed by the intaglio plate. Further extending from the upper beam


24


are two auxiliary roller bearings


36


,


38


in contact with the upper surface of the print roller


20


to maintain print roller


20


rigidity and parallelism against the considerable upward pressure exerted through the felt from the intaglio plate. A drive wheel


44


is coupled to the print roller


20


through bearings


47


,


49


and rotation of the drive wheel


44


propels the trolley


22


and the print roller


20


across the paper/felt/intaglio plate for printing. By a simple modification, a motor drive (not shown) may be used for moving the trolley


22


across the table in place of the drive wheel


44


.




Similarly, a lower roller


46


, equal approximately in length to the width of the bed


14


, is located below the bed


14


, and this roller is supported by intermediate bearings of which only


60


,


62


,


64


are seen in FIG.


1


. These bearings are mounted in blocks connected to the lower beam


26


. The lower roller


46


is in contact with the underside of the bed


14


, and the lower roller's rigidity prevents the bed


14


from flexing during printing.




Before describing the inventive spring loading of the printing roll


20


disclosed in the present invention, it is advantageous to consider the method of positioning, and the pressure exerted by, the print roller as practiced in the prior art. Referring to

FIG. 2



a,


a print roller


91


is shown positioned above a bed


89


covered by a felt/paper layer


81


. The shaft


87


of the print roller


91


is fitted into a bearing pillow block


85


whose upper surface is in contact with the bottom of the screw


95


. Rotation of the screw


95


by handle


93


pushes down on the bearing pillow block


85


to set the pressure of the print roller


91


on the bed


89


and felt


81


. The felt,


81


which distributes the force over the plate, being comprised of organic fibers, has a relatively steep spring constant. From

FIG. 2



b


which shows the linear relationship,


92


, between the movement of the screw


95


and the pressure on the felt


81


, it will be seen that a slight movement (


94


) of the screw


95


results in a relatively large change in the pressure (


96


) on the felt


81


. The pressure control of the present invention solves this problem, as described below.




Referring to

FIG. 3

one of the handwheel assemblies, e.g.


40


, is seen in a detailed side view of the trolley


22


. The structure of the other hand wheel assembly, e.g.


42


is substantially its mirror image. The side member of the trolley


22


labelled


28


, (FIG.


1


), viewed from the side is in the form of a box beam with a top member


52


, side members


54


,


56


, and bottom member


58


. Flat bed


14


, rigid side wall


16


and platform


18


are shown oriented in the longitudinal direction, i.e. the direction of trolley


22


movement during printing.




Pressure is applied to the print roller


20


in the following manner. The print roller


20


is mounted on a bracket


66


which passes through holes


68


,


70


in the cross beam


52


, so that bracket


66


is captive but can move vertically with respect to cross beam


52


. Screw


72


clears a hole


74


in the top of the bracket


66


, and the end of the screw


72


is locked by the nut


82


so it cannot move vertically with respect to the cross beam


52


of the trolley


22


. The lower end of the screw


72


is mounted in bearings


78


,


79


which allows the screw


72


to solely rotate relative to the bracket


66


and to the cross beam


52


. The lower end of the spring


80


is against the top of bracket


66


, and the upper end of the spring


80


is against the bottom of the plate


84


. The screw


72


is threaded through the nut


76


which is locked into place by being welded to a square plate


84


. A housing


86


has a partially opened top surface through which the screw


72


easily passes, and the side walls of the housing


86


are adjacent to the edges of the plate


84


which restrict any rotational movement of the square plate


84


. Rotation of the screw


72


by means of handle


40


compresses or relieves the spring


80


due to the vertical movement of the screw


72


relative to plate


84


and the nut


76


. Hence, the advance or retraction of screw


72


and the resultant vertical movement of the plate


84


controls the degree of compression of spring


80


which generates the force applied between the top of the bracket


66


and square plate


84


. The spring pressure applied to bracket


66


forces the bracket


66


down, (or allows it to move up), controlling the pressure at the line of contact of the print roller


20


against the felt


83


on the intaglio plate.




The addition of the spring


80


to the screw assembly


72


allows the print roller


20


to move up and down with changes in print plate thickness, or with changes of the felt's spring constant due to varying moisture in the felt while maintaining substantially the same pressure on the plate and paper being printed. Referring to

FIG. 4

, the corresponding relation between screw motion and pressure at the roller for the spring assembly of the invention is seen. The overall slope of the spring rate/felt rate curve


98


may be made flatter, since it is controlled by the spring


80


rather than by the randomly variable spring constant of the felt


83


. A small, readily controllable, change is screw position


100


results in a small pressure change of the roller on the felt


102


, as compared to the large change


96


illustrated in

FIG. 2



b,


as practiced in the prior art.




Additionally, the spring force may be made non-linear relative to rotation of the screw. Referring to

FIG. 5

, the initial spring rate (


104


) is seen to be very low, increasing (


106


) as the print roller continues to press into the felt. This allows the initial setup of the felt/paper at a minimal force between the print roller


20


and the felt/paper using a coarse adjustment of the screw


72


, and after the felt/paper have been correctly position under the roller, a few additional screw turns generates the high pressure needed for printing.




At the four corners of the top lip of the housing


86


four screws are threaded through the lip, of which only screws


88


,


90


are seen in the view of FIG.


3


. The positions of these threaded screws limit the upward motion of the plate


84


, and accordingly the rise of the print roller


20


above the bed


14


under control of the handle


40


.




In a second embodiment of the invention, a structure implementing a multiple constant spring is shown in

FIG. 6

, which may be used in setting print roll


20


pressure in place of the spring system of

FIG. 3. A

spring


108


(corresponding to the spring


80


of

FIG. 3

) surrounds a screw


73


(corresponding to screw


72


). The spring


108


consists of a series of stacked Belleville disc spring washers , and it will be appreciated that by selecting differing heights and thicknesses for these washers


108


, and stacking them in proper order, a dual constant spring arrangement may be effected. That is, a less stiff upper set of discs, followed by stiffer lower discs will provide the dual spring constant.

FIG. 5

shows the resultant spring constant of the dual spring constant structure. Initially, the low spring constant (


104


) controls the pressure, but when this spring segment is full compressed, the stiffer spring constant (


106


) takes over. Other types of spring elements may be placed in series in an equivalent manner.




In a third embodiment of the invention, a pressure measuring indicator


100


is mounted on the bracket


66


′. (In the drawings, different but related elements are identified with the same reference characters, albeit that corresponding elements in the various drawings are distinguished by primes.) The pressure measuring indicator


100


has an arm


102


that is pivoted at the point


104


. A boss


106


on the arm


102


is in contact with the underside of plate


84


′. As the handwheel


40


′ compresses the spring


80


′ by moving the plate


84


′, the arm


102


is deflected about the pivot point


104


due to the force on the boss


106


exerted by the plate


84


′. A pointer


108


is mounted on the free end of the arm


102


, and a juxtaposed pressure scale


110


is secured to the bracket


66


′. Depending on the compression of the spring


80


′, the pointer


108


indicates on the scale


110


the corresponding pressure applied to the print roller. It will be noted that the boss


106


may be located anywhere along the portion of the arm adjacent to the plate


84


′; the closer the boss


106


is to the pivot point


104


the greater the magnification of the swing of the pointer


108


over the scale


110


relative to the movement of the plate


84


′. A light spring


112


biases the arm


112


so that the boss


106


remains in contact with the bottom of the plate


84


′. It will be appreciated that in practice two of the disclosed indicators


100


are used on the press of the invention; each in association with a corresponding handwheel


40


,


42


, so that controlled pressures may be applied to each end of the print roller


20


(FIG.


1


).




The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. For example, while the invention has been described in terms of printing of etchings or engravings from an intaglio plate, it will appreciated that other forms of printing such as lithography, printing from handset type, or wood blocks may be practiced on the press of the invention. Applicant generically refers to use of “printing blocks” to inclusively cover the above broad printing techniques.



Claims
  • 1. A printing press comprising:a) a fixed stationary bed, b) a spring loaded print roller adapted for contacting and rotationally traversing said bed, c) at least a first support roller in contact with said print roller, and d) at least a second support roller in contact with said bed.
  • 2. The spring loaded print roller of claim 1 further comprising first and second springs, wherein the pressure exerted by said springs are a linear function of the lengths of said springs.
  • 3. The printing press of claim 2 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 4. The spring loaded print roller of claim 1 further comprising first and second springs wherein the pressure exerted by said springs are a nonlinear function of the lengths of said springs.
  • 5. The printing press of claim 4 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 6. The spring loaded roller of claim 4 wherein said first and said second springs comprise the combination of spring components having two distinguishable spring constants.
  • 7. The printing press of claim 6 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 8. The press of claim 6 wherein said first and said second nonlinear springs comprise first and second sets of stacked Belleville washers, said first and second sets differing in mechanical spring properties.
  • 9. The printing press of claim 8 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 10. A printing press comprising:a) a fixed bed having a length and a width, said bed having an upper surface and a lower surface, b) a trolley assembly having a frame encompassing said bed, said trolley adapted for movement along said length of said bed, said trolley straddling said width of said bed, said trolley further comprising, c) a cylindrical print roller rotatably mounted on a bracket movably positioned in said frame, wherein said print roller may be raised and lowered with respect to said bed, d) a least one support roller mounted on said frame in rolling contact with said print roller whereby said at least one support roller provides stiffening support to said print roller, e) first and second screws whose rotational positions relative to said frame raises and lowers said bracket relative to said bed, f) first and second springs in engagement with said first and second screws, wherein said first and said second springs apply pressure to said bracket and said print roller dependent upon the rotational position of said first and said second screws, g) first and second handles for rotating said first and said second screws, and h) a third handle for rotating said print roller, wherein when said bed is under pressure exerted by said print roller, said trolley is frictionally movable along said length of said bed by rotation of said third handle.
  • 11. The press of claim 10 wherein a multiplicity of rollers attached to said frame and contacting said bed, provide guidance of said trolley in movement along said length of said bed.
  • 12. The press of claim 10 wherein a support roller is mounted in said frame contacting the underside of said bed, whereby said support roller provides stiffening of said bed under pressure exerted by said print roller on said bed.
  • 13. The press of claim 12 wherein said support roller is in rolling contact with a multiplicity of bearings secured to said frame.
  • 14. The press of claim 10 wherein said bracket is surmounted by a housing comprising a multiplicity of adjustment screws, said adjustment screws controlling the maximum excursion of said bracket in lifting said print roller above said bed.
  • 15. The press of claim 10 wherein the pressure exerted by said first and said second springs is a linear function of the physical lengths of said springs.
  • 16. The printing press of claim 15 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 17. The press of claim 10 wherein the pressures exerted by said first and said springs are nonlinear functions of the lengths thereof.
  • 18. The printing press of claim 17 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 19. The press of claim 17 wherein said first and said second springs comprise the combination of spring components having two distinguishable spring constants.
  • 20. The printing press of claim 19 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 21. The press of claim 19 wherein said first and said second nonlinear springs comprise first and second sets of stacked Belleville washers, said first and second sets differing in mechanical spring properties.
  • 22. The printing press of claim 21 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 23. In a printing press including a print roller, a printing block plate and print fabricating material in contact with said printing block plate, the improvement comprising:a) at least two springs adapted to apply pressure to said print roller, whereby said pressure forces said print roller into intimate contact with said printing block plate and said print fabricating material to effect printing by said press, wherein the pressure exerted by said springs is a nonlinear function of the lengths thereof.
  • 24. The printing press of claim 23 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 25. The press of claim 23 wherein said springs comprise the combination of spring components having two distinguishable spring constants.
  • 26. The printing press of claim 25 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
  • 27. The press of claim 25 wherein said nonlinear springs comprise first and second sets of stacked Belleville washers, said first and second sets differing in mechanical spring properties.
  • 28. The printing press of claim 27 further comprising first and second pressure indicators wherein the pressures exerted by said first and second springs are displayed.
Parent Case Info

This application is a continuation-in-part of U.S. application Ser. No. 09/368,679 filed Aug. 5, 1999, now abandoned.

US Referenced Citations (9)
Number Name Date Kind
358857 Henry Mar 1887
404058 Snow May 1889
1824211 Jobke Sep 1931
3577917 Nantz May 1971
3633505 Ferrari Jan 1972
4704962 Healey Nov 1987
5325637 Yasuda et al. Jul 1994
5346199 Martin et al. Sep 1994
5609054 Ogawa et al. Mar 1997
Continuation in Parts (1)
Number Date Country
Parent 09/368679 Aug 1999 US
Child 09/516353 US