Patent Publication Number: US-3874292-A

Title: Plate clamp

Description:
United States Patent 1 1 1111 3,874,292 Parsley Apr. 1, 1975 15 PLATE CLAMP 3,727,551 4/1973 Kostas et a1. 101/415.1 Inventor: Robert L. y, Dallas, Tex- 3.766,857 10/1973 Schlatter 101/415.1 [73] Assignee: Dahlgren Manufacturing Company, Primary Examiner-Stephen C. Pellegrino Inc., Dallas, Tex. Attorney, Agent, or Firm-Howard E. Moore; Gerald 22 Filed: Sept. 17, 1973 [21] Appl. No.: 397,898 [57] ABSTRACT A plate clamp to detachably secure a printing plate on [52 [1,5, c 101 4154, 01 37 101 332 :1 plate cylinder ofa printing press comprising a row of 5 1m, 3 B41f27/12 spaced pegs positionable through spaced apertures 53 Fie|d f Search 101 4151 37 332 33 formed ad acent the leadmg edge of a prmting plate, 101 379 and a row of spaced pms secured to a shaft mounted for rotation to position the pins through apertures 5 References Cited formed adjacent the trailing edge of the plate. The UNITED STATES PATENTS shaft is urged by a spring to a position wherein the a 7 7 I plate is positively located and tightly drawn about a l gggg 16 529 portion of the circumference of the plate cylinder. 3.381799 5/1968 Luers l01/415.l 6 Claims, 9 Drawing Figures PLATE CLAMP BACKGROUND OF THE INVENTION Lithographic printing plates are generally constructed of thin, flexible metal and have flanges formed on leading and trailing edges thereof. The flange on the leading edge of the plate is generally inserted into a groove or slot formed in the plate cylinder and the trailing edge has been secured by various forms of clamping devices.  
  For example, US. Pat. No. 3,533,355 discloses a clamping member having a row of set screws extending therethrough to permit adjustment of the edge of the clamping member circumferentially about a plate cylinder.  
  Another type of mechanism for clamping plates to plate cylinders in a printing press is illustrated in US. Pat. No. 3,058,417 in which opposite edges of the printing plate are clamped prior to tensioning the printing plate by inflating a rubber tube.  
  Plate clamps heretofore devised required use of tools for tightening screws or bolts to secure a plate clamp in position and required substantial time for changing plates and making the press ready to print.  
 SUMMARY OF INVENTION I have devised an improved plate clamp comprising a shaft having outwardly extending projections or pins spaced along the length thereof positionable through apertures formed along the trailing edge of a printing plate.  
  For attaching a plate to a printing cylinder projections or pegs on the printing cylinder are positioned through apertures adjacent the leading edge of the printing plate. The plate is then wrapped around in portion&#39;of the circumference of the printing cylinder and apertures adjacent the trailing edge of the printing plate are positioned over the projections on the rotatable shaft. A spring on the shaft urges the projections to a position wherin the printing plate is properly tensioned.  
 The shaft is manually rotated to permit removal of the printing plate.  
  The improved plate clamp is attached to a saddle conncctablc to the cylinder of a letter press for example, of the type employed for printing newspapers, to expeditiously convert a letter press for lithographic printing.  
  A primary object of the invention is to provide a plate clamp adjacent to positively engage edges of a printing plate and to automatically draw the plate to a predetermined tension.  
  Another object of the invention is to provide a plate clamp resiliently drawing a printing plate to a predetermined tension by application of a substantially constant force adjacent the trailing edge of the printing plate.  
  A further object of the invention is to provide a saddle for converting a letter press to a lithographic printing press wherein each of the saddles&#39;has a spring urged plate clamp mechanism secured thereto permitting attachment&#39;of the saddle and plate clamp to a cylinder of the letter press.  
  Other and further objects of the invention will become apparent upon referring to the detailed description hereinafter following and to the drawings annexed hereto.  
 DESCRIPTION OF THE DRAWING Drawings of a preferred embodiment of the invention are annexed hereto so that the invention may be better and more fully understood, in which:  
  FIG. I is an end view of a printing cylinder having a pair of saddles secred thereto, each saddle having plate clamps incorporated therein;  
 FIG. II is a perspective view of a saddle;  
  FIG. III is a fragmentary exploded perspective view of a saddle and plate clamp;  
  FIG. IV is an enlarged fragmentary elevational view of the plate clamp illustrated in FIG. I;  
  FIG. V is a cross-sectional view taken along lines VV of FIG. IV;  
  FIG. VI is a cross-sectional view taken along the lines VIVI of FIG. V;  
  FIG. VII is a cross-sectional view taken along the line VII-VII of FIG. V;  
  FIG. VIII is a cross-sectional view taken along line VIII-VIII of FIG. V; and  
  FIG. IX is a fragmentary cross-sectional view similar to FIG. VIII illustrating a method of rotating the plate clamp for engaging or disengaging a printing plate.  
  Numeral references are employed to designate like parts throughout the various figure of the drawing.  
 PREFERRED EMBODIMENT Referring to FIG. I of the drawing, the number 1 generally designates a printing cylinder having journals 2 adjacent opposite ends thereof rotatable in a bearing (not shown).  
  Saddles 4 and 6 are of identical construction having leading edges 4a and 6a and trailing edges 4 b and 6b respectively. The concave sides 4c and 6c of the respective saddles have notches 6d formed therein, as best illustrated in FIGS. II and III, to receive lugs on cylinder 1 securing the saddles to the plate cylinder.  
  As best illustrated in FIG. II, the leading edge 6a of saddle 6 has pegs 8 extending outwardly therefrom to extend through apertures 310a formed in a deflected flange 12a adjacent leading edge of printing plate 15.  
  As best illustrated in FIG. III the trailing edge 6b of saddle 6 has a semi-circular seat 16 formed therein. Sockets 18 are formed in opposite ends of seat 16 to receive pin 20 on hinge element 22. Pin 20 has an aper ture 20a extending transversely therethrough to receive a dowel 24 when positioned in hole 18:! extending through the edge 6b of saddle 6 and intersecting socket l8.  
  Hinge element 22 has a lug 26 formed thereon positioned to engage shoulder 28 on a tail stop comprising elongated rectangular bar 30 extending longitudinally through gap 32 formed in a surface of cylinder 1 of the compression lock-up type.  
  As best illustrated in FIGS. III and V, hinge element 22 has a bore 32 extending therethrough to receive the journal 34 on the end of shaft 36. Opposite ends of shaft 36 have reduced diameter portions 38 formed thereon to provide shoulders 40 and 42 adjacent each end thereof. It should be appreciated that the bore 32 through hinge element 22 receives journal 34 on the end of shaft 36 while shoulder 42 in maintained in abutting relation with hinge element 22 preventing longitudinal movement of shaft 36 relative to saddles 4 and 6.  
  Hinge element 22 has a hole 44 formed therein to receive end 46 of coil spring 48. The opposite end 50 of bolts as has been coil spring 48 extends into a hole 52 formed in shoulder 40 on shaft 36.  
  Connector means such as pins 58 extend into spaced apertures b formed in flange 12b of printing plates 14 and 15. Rotation of shaft 36 is limited by stop pin 65 secured to saddle 4 and positioned in slot 66 formed in shaft 36.  
  The operation and function of the apparatus hereinbefore described is as follows:  
  Saddles 4 and 6 are attached to cylinders 1 in the same manner and employing conventional connector lugs heretofore employed for attaching letter press plates to a printing cylinder. Either compression or tension lock-up devices may be employed.  
  After saddles 4 and 6 have been connected to cylinder-1 printing plate is connected about the outer surface of saddle 6 by positioning apertures 10a extending through flange 12a adjacent the leading edge of plate 15 about pegs 8. Tool T is inserted in opening 60 formed in a central portion of shaft 36 and shaft 36 is rotated to the position illustrated in the dashed outline in FIG. IX. Pins 58 are positioned through apertures 10b extending through flange 12b adjacent the trailing edge of plate 15. When tool T is released springs 48 will urge shaft 36 to the position illustrated in full outline in FIG. IX drawing the plate to a predetermined tension established by the spring; constant of springs 48.  
  Plates 14 and 15 can be removed by positioning tool T through the slot 12c in the central portion of flange 12!) into opening 60 and rotating shaft 36 to the position illustrated in the dashed outline in FIG. lX.  
  From the foregoing it should be readily apparent that printing plates can be quickly and accurately position&#39;ed about the surface of the printing cylinder without necessitating&#39;loosening and tightening of screws or heretofore required for securing plate clamps. I  
  While the plate clamp hereinbefo&#39;redescribed has been illustrated in combination with a&#39;s&#39;addlc for adapting a letter press to a lithographic printing press, it should be appreciated that the plate clamp structure can be connected directly to the plate cylinder of a lithographic printing press adjacent opposite sides of a gap extendinglongitudinally thereof. It should further be appreciated that the plate clamp hercinbefore described is sufficiently compact to be employed in web presses wherein the printing plate extends about substantially all of the circumference of the plate cylinder.  
  While the embodiment ofthe invention hereinbefore describedand illustrated in the attached drawing is a preferred embodiment of the invention, other and further embodiments of the invention may be devised without departing from the basic concept thereof.  
 Having described my invention, 1 claim;  
 , 1.,Apparatus to secure a printing plate having apertures formedinflanges on leading and trailing edges.  
  4 ient means being adapted to urge the connector pins on the shaft into&#39;the gap &#39;formedin&#39; the cylinder.  
  2. The combination called for in claim 1 wherein the means to rotatably secure the shaft to the cylinder comprises: a hinge element having a bore extending therethrough; and means to secure said hinge element to the cylinder, and wherein the shaft has ajournal formed on the end thereof; a shoulder adjacent said journal, said journal being positioned in the bore in the hinge element such that the shoulder on the shaft engages said hinge element to limit longitudinal movement on the shaft relative to hinge element.  
  3. Apparatus to secure a printing plate to a cylinder having a longitudinally extending gap formed therein comprising: means to secure a first edge of a printing plate adjacent a first edge of the gap formed in the cylinder; a shaft; connector meansI to secure a second edge of a printing plate to said shaft; a saddle to rotatably secure the shaft adjacent the second edge of the gap formed in the cylinder; means to secure the saddle about a portion of the surface of a cylinder, saidsaddle having a seat formed in an edge thereof; hinge means to rotatably secure said shaft in said seat; and resilient means secured between the shaft and the saddle, said resilient means being adapted to urge the connector means on the shaft into the gap formed in the cylinder.  
 4. The combination called for in claim 3.wherein the hinge means to rotatably secure said shaft in saidseat comprises: a hinge element having a &#39;bore&#39; &#39;extending longitudinally therethrough; a pin on said&#39;hinge-element extending into a socket formed in said seat-in the saddle; and a spring positionable about said shaft-,one end of said spring being secured to said hinge element and the other end of said spring being secured to said shaft. l w  
  5. A printing press cylinder comprising: a cylinder; a printing plate having leadingand trailing edges; a first flange on said leading edge; a secondflange on said; trailing edge, each.of said flanges having a row, of aper tures formed therein; spaced pegs secured to said cylinder said pegs extending through apertures. in said first flange on the leading edge of the printing plate; a shaft; hinge means rotatably securing opposite ends of&#39;said&#39; shaft to said cylinder; torsion spring means aboutjea&#39;ch end of said shaft; means securing first ends of each of said torsion springs to said cylinden&#39;means securing second end of said torsion springs to said shaft; and spaced pins on said shaft positioned through apertures in said second flange on the trailing edge of said print ing plate, said torsion springs urging said pins ma posi tion wherein the printing plate is drawn to a controlled tension about said cylinder. i  
  6. Apparatus to secure a printing plate about the surface of a cylinder comprising: a saddle&#39;havin&#39;g first and second edges and a seat formed in a first edge thereof; means to secure the saddle about a portion ofthe-surface of the cylinderaspaced hinge elements; each of. said hinge elements having a boremextending therethrough; means securing said-hingeelem-entsadjacent said first edge of said saddle; a shaft ,havingopposite ends rotatably secured in said bores in said hinge ele ments, said shaft extending longitudinally of said seat; a spring positioned about said shaft; meanssecuring. one end of said spring to one ofsaid hinge elements; means securing a second end of said spring to said shaft; means to secure a first edge of the printing&#39;plate to said shaft; and meansto secure a s econd edge of the printing plate adjacent said &#39;second edge of said saddle.