Abstract:
The present invention provides bending apparatuses and methods that can form lithographic plates having different radii, such as for different printing press configurations, without the need to remove and replace the anvils on a bending apparatus. More particularly, the present invention provides bending apparatuses having integrated changeable anvils useable for forming bends having different radii.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Application No. 61/001,848 filed Nov. 5, 2007, the entire contents of which is incorporated herein by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the processing of lithographic plates. More particularly, the present invention relates to equipment for bending lithographic plates for the purpose of mounting and securing such plates on a press plate cylinder. 
     BACKGROUND 
     A typical lithographic plate includes features such as flanges and openings that enable the plate to be mounted on a printing plate cylinder of a printing press. The configuration of these flanges and openings defines the alignment between plural plates installed on a printing press and provides the registration of the various colors of the printed image. Accordingly, precision metal working techniques for bending such flanges and forming such openings are used to ensure precision alignment between plural plates mounted on a printing press. 
     A typical machine used for forming a precision bend in a lithographic plate includes an anvil provided at the end of a supporting surface, a clamping device for clamping a plate to be bent to the supporting surface, and a mandrel for bending the plate around the anvil to form a flange. The anvil has an end with a forming surface that has a predetermined radius and a bend is made by rolling the plate around the radius of the forming surface of the anvil. In this way, the material of the plate conforms to the shape of the anvil to form a bend radius in the flange that is defined by the radius of the forming surface of the anvil. Exemplary machine tools for bending lithographic plates are described in U.S. Pat. No. Re. 31,938, reissued Jul. 9, 1985, to Klukow, U.S. Pat. No. 5,970,774 to Burgess et al., and U.S. Pat. No. 5,454,247 to Powers et al., the disclosures of which are incorporated herein by reference in their entirety for all purposes. 
     Lithographic plate bending machines, as presently known, suffer from certain limitations. Printing presses made by different manufactures have lithographic plate receiving slots that require lithographic plates with mounting flanges having angles and bend radiuses different than those of other manufacturers. This requires the printer to either have multiple benders each with an anvil having an angle and radius unique to the printing press on which the lithographic plate is to be mounted or to remove and replace the anvils each time a lithographic plate is to be bent for a different printing press. 
     SUMMARY 
     The present invention provides bending apparatuses and methods that can form lithographic plates having different radii, such as for different printing press configurations, without the need to remove and replace the anvils on a bending apparatus. More particularly, the present invention provides bending apparatuses having integrated changeable anvils useable for forming bends having different radii. An exemplary apparatus includes a first anvil having a first radius and one or more additional anvils having a different radius. An additional anvil can be moved between a home or retracted position and a working or bending position. When an additional anvil is positioned in the home position the first anvil is used for bending. When the additional anvil is positioned in the working position the additional anvil is used for bending. 
     Advantageously, apparatuses having one or more additional anvils allow bending of different radii with the same bending apparatus without significant reduction in cycle times. Moreover, bending apparatuses in accordance with the present invention allow fast changes between different radii without reduction of the cycle times, utilize competitive mechanics, can be built with standard assemblies without difficult adjustments, have unrestricted utilization of the current work widths per associated tool width, are expandable to three or more radii, are service-friendly, and are usable with pneumatic and/or electrical bending drives. 
     In an aspect of the present invention an apparatus for forming a mounting flange on a printing plate is provided. The apparatus comprises a bending device. The bending device comprises: a supporting bed having a working surface that can position and support a printing plate relative to the bending device; a first anvil comprising a first forming surface having a first radius, the first anvil positioned relative to the working surface of the supporting bed so a printing plate positioned on the working surface of the supporting bed can be bent around the forming surface of the first anvil to form a flange on the printing plate; a clamping device positioned relative to the working surface of the supporting bed, the clamping device having a clamping surface movable between a first unclamped position where the clamping surface is spaced apart from the working surface of the supporting bed and a second clamped positioned where the clamping surface can contact a printing plate positioned on the working surface of the supporting bed to hold the printing plated during a bending operation to form a flange on the printing plate; a mandrel positioned relative to the first forming surface of the first anvil, the mandrel having a body portion and a working surface capable of being controllably rotated about the first forming surface of the first anvil to form a flange on a printing plate when positioned on the working surface of the supporting bed and held by the clamping device; a second anvil comprising a second forming surface having a second radius different from the first radius of the first forming surface of the first anvil, the second anvil moveable relative to the first anvil between a first retracted position where the first anvil is used to form a flange on a printing plate and a second working position where the second anvil is used to form a flange on a printing plate; and a control system that controls operation of one or more of the clamping device, mandrel, and second anvil. 
     In another aspect of the present invention, the above described apparatus comprises a bank of plural anvils wherein each anvil of the bank of anvils comprises a forming surface having a radius distinct from the radiuses of the other anvils of the bank of anvils, each anvil of the bank of anvils moveable in a first direction relative to the first anvil between a first retracted position where the first anvil is used to form a flange on a printing plate and a second working position where each anvil is used to form a flange on a printing plate, each anvil of the bank of anvils moveable in a second direction generally orthogonal to the first direction to position each anvil relative to the first anvil and so each anvil can be positioned in the second working position. 
     In another aspect of the present invention an apparatus for forming a mounting flange on a printing plate is provided. The apparatus comprises a bending device. The bending device comprises: a supporting bed having a working surface that can position and support a printing plate relative to the bending device; a first anvil comprising a first forming surface having a first radius, the first anvil positioned relative to the working surface of the supporting bed so a printing plate positioned on the working surface of the supporting bed can be bent around the forming surface of the first anvil to form a flange on the printing plate; a clamping device positioned relative to the working surface of the supporting bed, the clamping device having a clamping surface movable between a first unclamped position where the clamping surface is spaced apart from the working surface of the supporting bed and a second clamped positioned where the clamping surface can contact a printing plate positioned on the working surface of the supporting bed to hold the printing plated during a bending operation to form a flange on the printing plate; a mandrel positioned relative to the first forming surface of the first anvil, the mandrel having a body portion and a working surface capable of being controllably rotated about the first forming surface of the first anvil to form a flange on a printing plate when positioned on the working surface of the supporting bed and held by the clamping device; an absorber device comprising at least one resilient portion operatively positioned between the working surface of the mandrel and a body portion of the mandrel wherein the resilience of the resilient portion can be controllably adjusted; a second anvil comprising a second forming surface having a second radius different from the first radius of the first forming surface, the second anvil moveable relative to the first anvil between a first retracted position where the first anvil is used to form a flange on a printing plate and a second working position where the second anvil is used to form a flange on a printing plate; and a control system that controls operation of one or more of the clamping device, mandrel, and second anvil. 
     In another aspect of the present invention, an apparatus for forming a mounting flange on a printing plate is provided. The apparatus comprises a bending device comprising: a supporting bed having a working surface that can position and support a printing plate relative to the bending device; a first moveable anvil comprising a first forming surface having a first radius, the first anvil moveable relative to the working surface of the supporting bed so the forming surface of the first anvil can be positioned relative to the working surface of the supporting bed so a printing plate positioned on the working surface of the supporting bed can be bent around the first radius of the first anvil to form a flange on the printing plate; a clamping device positioned relative to the working surface of the supporting bed, the clamping device having a clamping surface movable between a first unclamped position where the clamping surface is spaced apart from the working surface of the supporting bed and a second clamped positioned where the clamping surface can contact a printing plate positioned on the working surface of the supporting bed to hold the printing plated during a bending operation to form a flange on the printing plate; a mandrel positioned relative to the first forming surface of the first anvil, the mandrel having a body portion and a working surface capable of being controllably rotated about the first forming surface of the first anvil to form a flange on a printing plate when positioned on the working surface of the supporting bed and held by the clamping device; a second movable anvil comprising a second forming surface having a second radius different from the first radius of the first forming surface, the second anvil moveable relative to the working surface of the supporting bed between a first retracted position and a second working position where the second anvil is used to form a flange on a printing plate; and a control system that controls operation of one or more of the clamping device, mandrel, and second anvil. 
     In another aspect of the present invention, a method of forming a mounting flange on a printing plate is provided. The method comprises: providing any of the apparatuses described herein; positioning the clamping device in the first unclamped position; positioning a printing plate on the working surface of the supporting bed; positioning the clamping device in the second clamped position thereby clamping the printing plate to the working surface of the supporting bed; positioning the second anvil in the second working position of the second anvil wherein the second anvil is nested with the first anvil; and rotating the mandrel about the center of the first radius of the first anvil. 
     In another aspect of the present invention, an apparatus for forming a mounting flange on a printing plate is provided. The apparatus comprises a bending device. The bending device comprises a supporting bed; a first anvil comprising a first forming surface having a first radius; a clamp and mandrel positioned relative to the first forming surface of the first anvil, the mandrel capable of being controllably rotated about the first forming surface of the first anvil to bend a printing plate when positioned on the supporting surface; a second anvil comprising a second forming surface having a second radius, the second anvil moveable relative to the first anvil between a retracted and working position; and a control system. 
     In another aspect of the present invention a method of forming a mounting flange on a printing plate is provided. The method comprises: positioning a printing plate on a supporting surface relative to a first anvil and a clamp and mandrel of a bending device; moving second anvil from a retracted position to a working position; clamping the printing plate to the supporting surface; and rotating the mandrel about the second anvil. 
     In yet another aspect of the present invention, a method of changing anvils in a bending device is provided. The method comprises the steps of selecting one of plural anvils to use for a bending operation and moving the selected anvil from a retracted position to a working position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate several aspects of the present invention and together with description of the exemplary embodiments serve to explain the principles of the invention. A brief description of the drawings is as follows: 
         FIG. 1  is a perspective view of an exemplary bending apparatus  10  in accordance with the present invention showing a first stationary anvil, second moveable anvil, rotatable mandrel, and a clamping device. 
         FIG. 2  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing a printing plate to be bent by the bending apparatus and the second anvil, mandrel, and clamping device each in a retracted position. 
         FIG. 3  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in a retracted position, the mandrel in a position ready to form a bend in the printing plate, and the clamping device in a clamped position. 
         FIG. 4  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in a retracted position, the mandrel partially rotated around a forming surface of the first anvil, and the clamping device in a clamped position. 
         FIG. 5  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in a retracted position, the mandrel further partially rotated around the forming surface of the first anvil as compared to  FIG. 4 , and the clamping device in a clamped position. 
         FIG. 6  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in a retracted position, the mandrel fully rotated around the forming surface of the first anvil to a desired bend angle, and the clamping device in a clamped position. 
         FIG. 7  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing a flange formed on the printing plate and the second anvil, mandrel, and clamping device each in a retracted position after forming the flange on the printing plate. 
         FIG. 8  is a detail view of the printing apparatus as shown in  FIG. 8  at the completion of forming the flange on the printing plate. 
         FIG. 9  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing a printing plate to be bent by the bending apparatus and the second anvil in a working position nested with the first anvil and the mandrel and clamping device each in a retracted position. 
         FIG. 10  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in the working position, the mandrel in a position ready to form a bend in the printing plate, and the clamping device in a clamped position. 
         FIG. 11  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in the working position, the mandrel partially rotated around a forming surface of the second anvil, and the clamping device in a clamped position. 
         FIG. 12  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in the working position, the mandrel further partially rotated around the forming surface of the first anvil as compared to  FIG. 11 , and the clamping device in a clamped position. 
         FIG. 13  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing the second anvil in the working position, the mandrel fully rotated around the forming surface of the second anvil to a desired bend angle, and the clamping device in a clamped position. 
         FIG. 14  is a cross-sectional schematic view of the bending apparatus of  FIG. 1  showing a flange formed on the printing plate and the second anvil in the working position and the mandrel and clamping device each in a retracted position after forming the flange on the printing plate. 
         FIG. 15  is a detail view of the printing apparatus as shown in  FIG. 13  at the completion of forming the flange on the printing plate. 
         FIG. 16  is a cross-sectional schematic view of another exemplary bending apparatus in accordance with the present invention showing a printing plate to be bent by the bending apparatus and first and second moveable anvils, a mandrel, and a clamping device each in a retracted position. 
         FIG. 17  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the first anvil in a working position, the second anvil in a retracted position, the mandrel in a position ready to form a bend in the printing plate, and the clamping device in a clamped position. 
         FIG. 18  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the first anvil in a working position, the second anvil in a retracted position, the mandrel partially rotated around a forming surface of the first anvil, and the clamping device in a clamped position. 
         FIG. 19  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the first anvil in a working position, the second anvil in a retracted position, the mandrel fully rotated around the forming surface of the second anvil to a desired bend angle, and the clamping device in a clamped position. 
         FIG. 20  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing a flange formed on the printing plate and the first and second anvils, mandrel, and clamping device each in a retracted position. 
         FIG. 21  is a detail view of the printing apparatus as shown in  FIG. 19  at the completion of forming the flange on the printing plate. 
         FIG. 22  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing a printing plate to be bent by the bending apparatus and the first and second moveable anvils, mandrel, and clamping device each in a retracted position. 
         FIG. 23  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the second anvil in a working position, the first anvil in a retracted position, the mandrel in a position ready to form a bend in the printing plate, and the clamping device in a clamped position. 
         FIG. 24  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the second anvil in a working position, the first anvil in a retracted position, the mandrel partially rotated around a forming surface of the second anvil, and the clamping device in a clamped position. 
         FIG. 25  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing the second anvil in a working position, the first anvil in a retracted position, the mandrel fully rotated around the forming surface of the second anvil to a desired bend angle, and the clamping device in a clamped position. 
         FIG. 26  is a cross-sectional schematic view of the bending apparatus of  FIG. 16  showing a flange formed on the printing plate and the first and second anvils, mandrel, and clamping device each in a retracted position. 
         FIG. 27  is a detail view of the printing apparatus as shown in  FIG. 25  at the completion of forming the flange on the printing plate. 
         FIG. 28  is an exploded perspective view of a mandrel comprising an exemplary absorber device including plural pneumatic bladders. 
         FIG. 29  is a schematic view of another exemplary bending apparatus in accordance with the present invention showing a moveable anvil and mandrel that comprise die elements and cooperate to form a desired geometric feature on a printing plate and illustrating a first step of a two step bending process wherein the mandrel is partially rotated around a forming surface of the anvil. 
         FIG. 30  is a schematic view of the apparatus of  FIG. 29  showing the moveable anvil in a retracted position and illustrating a second step of the two step bending process wherein the mandrel is fully rotated around the forming surface of the anvil. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2  initially, a perspective view of bending apparatus  10  is shown in  FIG. 1  and a schematic cross-sectional view of bending apparatus  10  is shown in  FIG. 2 . Bending apparatus  10  can be used with a bending system (not shown) wherein plural bending apparatuses are used such as at opposite ends of a bending system. Generally, bending apparatus  10  includes first anvil  12 , second movable anvil  14 , clamping device  16 , and mandrel  18 , operatively integrated with and supported by machine frame  11 . 
     In the schematic view of  FIG. 2  second anvil  14 , clamping device  16 , and mandrel  18  are each shown in a retracted position. As shown, first anvil  12  comprises a supporting bed having a support or working surface that supports printing plate  20  during a bending process to form a flange on printing plate  20  and a forming surface having a first predetermined radius for forming a bend having such radius and at a predetermined angle in plate  20  cooperatively with clamping device  16  and mandrel  18 . The support surface portion of first anvil  12  can be integrated with first anvil  12 , as illustrated, or can be a distinct structural element of bending apparatus  10 . An additional supporting bed having a supporting surface can be provided adjacent to first anvil  12  if desired such as part of a larger bending system that uses plural bending apparatuses at opposite ends of the system. 
     First anvil  12  is preferably static (not moveable) and designed to be operatively integrated with machine frame  11  as can be seen schematically in  FIG. 2 . First anvil  12 , however, can be designed to be moveable relative to any of second moveable anvil  14 , clamping device  16 , and mandrel  18 , if desired. For example, first anvil  12  (or a portion thereof) may be designed to move out of the way of second anvil  14  when second anvil  14  is moved to a working position for forming a flange on a printing plate. 
     Clamping device  16  is designed to clamp or hold printing plate  20  against the support surface, such as can be provided by first anvil  12 , and relative to the forming surface of first anvil  12  while mandrel  18  is rotated about the radius of the forming surface of the first anvil  12  to provide a flange on printing plate  20 . As illustrated, clamping device  16  comprises clamping bar  13  that extends across bending apparatus  10 . Clamping bar  13  includes clamping surface  23 , which may comprise a pad of a resilient material such as rubber or plastic or the like. Clamping bar  13  is attached to bracket  15  having bearing  17 . Bearing  17  rides on linear rod  19  as operatively connected to machine frame portion  29 . A similar bearing and linear rod (and actuator) are used on the opposite side of clamping bar  13  and not readily visible in the Figures. Linear actuator  21  is operatively attached to bracket  15  and functions to move bracket  15  along linear rod  19 , which moves clamping device  16  between clamped and unclamped positions in machine direction indicated by reference numeral  25 . As shown, linear actuator  21  comprises a pneumatically actuated drive device. Linear actuator  21 , however, may comprise any device or mechanism capable of providing linear motion. 
     Second anvil  14  comprises a forming surface having a second predetermined radius for forming a bend having such radius in plate  20  cooperatively with clamping device  16  and mandrel  18 . The angle of the bend is related to the degree of rotation of mandrel  18 . The radius of second anvil  14  is different from the radius of first anvil  12  thus allowing bending apparatus  10  to form a flange on printing plate  20  having a bend radius different from that which can be formed using first anvil  12 . In an exemplary preferred embodiment, the radius of the forming surface of the second anvil  14  is larger than the radius of the forming surface of the first anvil  12 . The first and second anvils,  12  and  14 , can be designed, however, so the radius of the forming surface of the second anvil  14  is smaller than the radius of the forming surface of the first anvil  12 . 
     Second anvil  14  is designed to be moveable relative to first anvil  12  along machine direction indicated by reference numeral  25  as can be seen schematically in  FIG. 2 . Moving second anvil  14  relative to first anvil  12  allows second anvil  14  to be moved between a retracted non-functional position, as shown in  FIG. 2  and a working functional position as shown in  FIG. 9 . Second anvil  14  is preferably designed so that when in the working position, second anvil cooperatively nests with first anvil  12  and is positioned in a functional position relative to clamping device  16  and mandrel  18 . As used herein the term nesting refers to the relative position of the first and second anvils,  12  and  14 . Preferably, first and second anvils,  12  and  14 , are designed to fit compactly together when second anvil  14  is positioned in the working position. That is, first and second anvils,  12  and  14 , are preferably designed so that adjacent surfaces of first and second anvils,  12  and  14 , closely follow or mirror each other when second anvil  14  is positioned in the working position. 
     As shown, second anvil  14  comprises bar  27  operatively connected to first and second linear actuators,  22  and  28 , respectively, at opposite ends of bar  27 . Linear actuators  22  and  28  are operatively connected to machine frame  11  of bending device  10 . As shown, linear actuators  22  and  28 , comprises pneumatically actuated drive devices. Linear actuators  22  and  28 , however, may comprise any device or mechanisms capable of providing linear motion such as those that use mechanical, electrical, pneumatic, and hydraulic motion or combinations thereof. 
     Mandrel  18  comprises body  50  and absorber device  52 . Body  50  is operatively connected to first and second brackets,  53  and  55 , at opposite ends of body  50  as shown. Body  50  includes contacting surface  51 , which may comprise a pad of a resilient material such as rubber or plastic or the like. Brackets  53  and  55  are pivotably connected to machine frame  11  of bending apparatus  10  at pivot points. The pivot points are positioned at the center of the first radius of the first anvil  12  so that mandrel  18  rotates about the radius of the first anvil  12  when forming a bend in printing plate  20 . As shown, mandrel  18  is operatively connected to actuator  54 , which is operatively connected to machine frame  11  of bending device  10 . Mandrel  18  includes rack and pinion device (not visible in Figures) that provides linear motion for mandrel  18  and pivots for providing rotational motion of mandrel  18 . Preferably, mandrel  18  is designed to move linearly together with clamping device  16 . As shown, actuator  54  comprises a pneumatically actuated drive device. Actuator  54 , however, may comprise any device or mechanism capable of providing the desired motion. 
     Mandrel  18  is shown in more detail in  FIG. 28  as an exploded view. As shown, absorber device  52  of mandrel  18  preferably includes resilient bladders  60 ,  62 , and  64  operatively positioned between first portion  56  of body  50  of mandrel  18 , which contacts printing plate  20  during bending and second portion  58  of body  50  of mandrel  18 , which is attached to, brackets  53  and  55 . First and second portions,  56  and  58  are assembled using bolts  57 , as shown. Any desired technique and structure can be used to assemble first and second portions,  56  and  58 , respectively, and bladders  60 ,  62 , and  64  to form mandrel  18  as long as second portion  58  is movable relative to first portion  56  as controllable by absorber device  52 . 
     Preferably, as shown, bladders  60 ,  62 , and  64  are spaced apart across mandrel  18  and any desired number of bladders or resilient devices can be used. Bladders  60 ,  62 , and  64  function to provide resilience between first and second portions,  56  and  58 , respectively, of body  50  of mandrel  18  when second anvil  14  is used to form a flange on printing plate  20 . First and second portions,  56  and  58 , respectively, also allow second portion  58  to be moved relative to first portion  56 . 
     When second anvil  14  is nested with first anvil  12  in the working position of second anvil  14  the center of the radius of the forming surface of second anvil is spaced apart from the center of the radius of the forming surface of the first anvil  12 . Because mandrel  18  pivots about the center of the radius of the forming surface of the first anvil  12 , resilience provided by bladders  60 ,  62 , and  64  has been found to help allow mandrel  18  to rotate and form consistent bends having the desired bend radius and flange angle. 
     Additionally, absorber device  52  is preferably designed to allow first and second portions,  56  and  58 , respectively, of body  50  to be controllably moved relative to each other. That is, after forming a bend on printing plate  20 , second portion  58  can be retracted away from printing plate  20  so that contacting surface  51  of second portion  58  is spaced apart from printing plate  20  during the return stroke of mandrel  18 . If absorber device  52  comprises pneumatic bladders as illustrated in the exemplary embodiment, for example, the bladders are preferably inflated during a bending stroke of mandrel  18  and at least partially deflated during the return stroke of mandrel  18 . When inflated, however, such inflation is preferably enough to functionally bend printing plate  20  and still provide any desired resilience during the bending stroke. That is, resilience is preferably increased during such bending step, and is particularly useful when bending using second anvil  14 . Deflation of the bladders during the return stroke helps to prevent possible undesirable pressure from being placed on printing plate  20  during the return stroke after the flange has been formed, which pressure could undesirably change the shape of the formed flange. 
     Bladders  60 ,  62 , and  64 , as shown, each comprises a pneumatic device that can be pressurized and depressurized as desired when forming a bend and are particularly useful when forming a bend using second anvil  14  because mandrel  18  rotates about the center of the first radius of the first forming surface of the first anvil  12 , which is not coincident with the second radius of the second forming surface of the second anvil  14 . Any device or mechanism or the like capable of providing resilience between first and second portions,  56  and  58 , of body  50  of mandrel can be used. For example, springs or other mechanical devices capable of providing resilience, as well as hydraulic devices such as cylinders and pistons, and resilient material such as foam and rubber or the like can be used. An exemplary pneumatic device that can be used for bladders  60 ,  62 , and  64  comprises a short stroke pneumatic cylinder available from Festo Corporation as part number EV-15/63-4. 
     Bending device  10  also preferably include a control system (not shown). The control system preferably includes a computer having of a central processing unit, memory, and a user interface. The user interface may include, for example, a keyboard or other type of control panel as well as a monitor or display and a printer. The computer, along with other components of the control system, controls the operation of the components of bending apparatus  10 . 
     In general, first anvil  12 , clamping device  16 , and mandrel  18  can be designed according to known bending apparatuses. That is, bending devices that use a single anvil, clamp, and mandrel are well known. For example, such bending devices are described in U.S. Pat. No. Re. 31,938, reissued Jul. 9, 1985, to Klukow, U.S. Pat. No. 5,970,774 to Burgess et al., and U.S. Pat. No. 5,454,247 to Powers et al. the disclosures of which are each fully incorporated by reference herein for all purposes. 
     Referring now to  FIG. 2  in particular, bending apparatus  10  is schematically shown with plate  20  positioned for a bending operation using first anvil  12  with first radius. Clamping device  16  and mandrel  18  are each in a retracted position relative to plate  20  and first anvil  12 . Second anvil  14  is in a retracted (home) position relative to first anvil  12 . Second anvil  14  may be partially or fully retracted. 
     In  FIG. 3  clamping device  16  is shown in the clamped position and mandrel  18  is in a position ready for bending plate  20  as clamped between first anvil  12  and clamping device  16 . Second anvil  14  is in the retracted (home) position relative to first anvil  12 . Resilient device  52  is preferably in an extended or inflated position.  FIGS. 4 and 5  show incremental steps of the bending operation. 
     In  FIG. 6  mandrel  18  is shown rotated around the radius of first anvil  12  and at the end of a bending motion and showing a flange formed on plate  20 . A detail view of plate  20 , clamping device  16 , mandrel  18 , and first anvil  12  at the end of the bending motion of mandrel  18  is shown in  FIG. 8 . In  FIG. 7  clamping device  16  and mandrel  18  are shown in the retracted position after the completed bend. 
     In  FIG. 9  apparatus  10  is shown with plate  20  positioned for a bending operation using second anvil  14  having second radius different from first radius of first anvil  12 . Preferably, the second radius is larger than the first radius. Clamping device  16  and mandrel  18  are in a retracted position relative to plate  20 , first anvil  12 , and second anvil  14 . Second anvil  14  is in the functional working position relative to first anvil  12 . In the working position, second anvil  14  is preferably nested with first anvil  12 . In the illustrated exemplary apparatus  10 , second anvil  14  is moveable between the retracted and working positions along a linear path indicated by machine direction identified by reference numeral  25  and as moved by linear actuator  22 . Second anvil  14  can be designed to be move between the retracted and working positions along any desired path such as an arcuate, elliptical, and/or rotational path. 
     In  FIG. 10  clamping device  16  is closed and mandrel  18  is in a position ready for bending plate  20  as clamped between first anvil  12  and clamping device  16 .  FIGS. 11 and 12  show incremental steps of the bending operation. 
     In  FIG. 13  mandrel  18  is shown rotated around pivot points corresponding with the center of the radius of first anvil  12  by and at the end of a bending motion and showing a flange formed on plate  20 . When rotated, absorber device is configured to provide any desired level of resilience. A detail view of plate  20 , clamping device  16 , mandrel  18 , and second anvil  14  at the end of the bending motion of the mandrel  18  is shown in  FIG. 15 . In  FIG. 14  clamping device  16  and mandrel  18  are shown in the retracted position after the completed bend. 
       FIGS. 16-27  show another exemplary bending apparatus  30  in accordance with the present invention that includes a bank of plural movable anvils.  FIGS. 16-21  are cross-sectional views of apparatus  30  illustrating structural elements of apparatus  30  and illustrating an exemplary bending process using a first anvil  34  nested with a supporting bed  32  and with a second anvil  36  in a retracted position in accordance with the present invention.  FIGS. 22-27  are cross-sectional views of apparatus  30  illustrating an exemplary bending process using the second anvil  36  with the second anvil  36  in a working position and nested with the supporting bed  32  in accordance with the present invention. 
     Generally apparatus  30  is similar to apparatus  10  described above and includes supporting bed  32 , first movable anvil  34 , second movable anvil  36 , clamping device  38 , mandrel  40 , and a control system (not shown). In the illustrated exemplary embodiment, first and second anvils,  34  and  36 , respectively, provide a moveable bank of anvils in which any desired number of anvils can be used. Supporting bed  32 , in the illustrated embodiment, is not used for forming a bend in a printing plate cooperatively with clamping device  38  and mandrel  40  but may include a forming surface having a radius for forming a bend if desired. For example, supporting bed  32  can be designed to function as an anvil as is described above with respect to apparatus  10 . If supporting bed  32  is designed to function as an anvil, mandrel  40  is preferably designed to include and absorber device such is described above with respect to mandrel  18 . 
     Supporting bed  32  is preferably static (not moveable) but can be designed to be moveable relative to any of first moveable anvil  34 , second moveable anvil  36 , clamping device  38 , and mandrel  40 . For example, supporting bed  32  (or a portion thereof) may be designed to move out of the way of first anvil  34  or second anvil  36  when such anvil is moved to a working position. Supporting bed  32 , clamping device  38 , and mandrel  40  can be designed according to known bending apparatuses and as described above. In particular, mandrel  40  may be designed to include an absorber device capable of providing resilience during a bending operation as described above with respect to absorber device  52  of mandrel  18 . 
     In  FIG. 16  apparatus  30  is shown with plate  42  positioned for a bending operation using first anvil  34  having a forming surface having a first radius. Clamping device  38  and mandrel  40  are in a retracted position relative to plate  42  and supporting bed  32 . First anvil  34  and second anvil  36  are each in a retracted position relative to supporting bed  32 . First anvil  34  and second anvil  36  may be partially or fully retracted. 
     In  FIG. 17  clamping device  38  is shown in the closed position and mandrel  40  is in a position ready for bending plate  42  as clamped between supporting bed  32  and clamping device  38 . First anvil  34  is in a working position relative to supporting bed  32 . In the working position, first anvil  34  is preferably nested with supporting bed  32 , as shown. In the illustrated exemplary apparatus  30 , first anvil  34  is moveable between the retracted and working positions along a linear path indicated by a machine direction identified by reference numeral  49  and as moved by linear actuator  44 . First anvil  34  can be designed to be moved between the retracted and working positions along an arcuate, elliptical, and/or rotational path.  FIGS. 18 and 19  show incremental steps of the bending operation. 
     In  FIG. 19 , in particular, mandrel  40  is shown rotated around the center of radius of first anvil  34  and at the end of a bending motion and showing a flange formed on plate  42 . That is, mandrel  40  is preferably designed to rotate around a point that coincides with the center of the radius of the forming surface of first anvil  34 . A detail view of plate  42 , clamping device  38 , mandrel  40 , supporting bed  32 , and first anvil  34  at the end of the bending motion of the mandrel  38  is shown in  FIG. 21 . In  FIG. 20  clamping device  38  and mandrel  40  are shown in the retracted position and first anvil  34  is shown in the retracted position after the completed bend. 
     Referring to  FIG. 21  in particular, first anvil  34  includes optional plate  35  that is positioned relative to the radius of first anvil  34 , as shown. The radius of first anvil  34  functions to provide a first bend in plate  42  and plate  35  functions to provide a second bend spaced from the first bend during a single bending rotation of mandrel  40 . Plate  35  provides additional leverage to form the second bend under the force of the mandrel  40  during bending. Plate  35  is designed to provide the desired bend geometry and is preferably adjustable to provide different bend geometries with the same anvil. As shown, second anvil  36  preferably includes similar plate  37 . Plates  35  and  37  are optional and not required. It is also noted that second anvil  14  of apparatus  10  described above may also include a plate functionally and structurally similar to plates  35  and  37  if desired. 
     In  FIG. 22  apparatus  30  is shown with first and second anvils,  34  and  36 , respectively, in the retracted position after forming a bend with first anvil  34 . In  FIG. 23 , apparatus  30  is shown with plate  42  positioned for a bending operation using second anvil  36  having a forming surface having second radius different from the radius of the forming surface of first anvil  34 . Clamping device  38  and mandrel  40  are in a retracted position relative to plate  42 . In the configuration of apparatus  30  shown in  FIG. 23 , second anvil  36  has been translated linearly in the machine direction indicated by reference numeral  48  relative to the position of second anvil  36  shown in  FIGS. 16-22  and is in a position ready to be moved to a working position relative to supporting bed  32 . Any desired mechanism or device can be used to translate second anvil  36  along direction  48 . Preferably first and second anvils,  34  and  36 , respectively, are designed as a bank having any desired number of anvils that is translated along direction  48 . 
     In  FIG. 23  clamping device  38  is closed and mandrel  40  is in a position ready for bending plate  42  as clamped between supporting bed  32  and clamping device  38 . Second anvil  36  is shown in the working position wherein second anvil  36  is nested with supporting bed  32 . In the illustrated apparatus  30 , second anvil  36  is moveable between the retracted and working positions along a linear path indicated by a machine direction identified by reference numeral  49  and as moved by linear actuator  46 . Second anvil  36  can be designed to be move between the home and working positions along an arcuate, elliptical, and/or rotational path.  FIGS. 24 and 25  show incremental steps of the bending operation. 
     In  FIG. 25  mandrel  40  is shown rotated around the radius of second anvil  36  and at the end of a bending motion and showing a flange formed on plate  42 . Preferably, second anvil  36  (or any additional anvil of the bank of anvils) is positioned so the center of the radius of the forming surface of the second anvil  36  coincides with the location of the point about which mandrel  40  rotates. That is, each anvil of the bank of anvils is preferably moved to a working position where the center of the radius of the forming surface of an anvil coincides with the point about which mandrel  40  rotates. A detail view of plate  42 , clamping device  38 , mandrel  40 , and second anvil  36  at the end of the bending motion of the mandrel  40  is shown in  FIG. 27 . In  FIG. 26  clamping device  38  and mandrel  40  are shown in the retracted position after the completed bend. 
     In  FIGS. 29 and 30 , another exemplary bending apparatus  70  in accordance with the present invention is schematically shown. Bending apparatus  70 , as shown, includes first anvil  72  having a forming surface having a first radius and a supporting bed, second movable anvil  74 , clamping device  76 , mandrel  78 , and a control system (not shown). Printing plate  80  is also shown positioned on the supporting bed of first anvil  72  and after a first bending operation in  FIG. 29  and after a second bending operation in  FIG. 30 . Bending apparatus  70  can be designed in accordance with the designs of exemplary apparatuses  10  and  30  described above. That is, design elements and features from bending apparatuses  10  and  30  may be incorporated into apparatus  70  as desired. 
     Second moveable anvil  74  and mandrel  78  are designed to cooperatively function as a die to form a desired feature in a flange of a printing plate. As shown, second anvil  74  includes male die portion  82  and mandrel  78  functions as a female die. In  FIG. 29 , printing plate  80  is shown clamped against the supporting bed of first anvil  72  by clamping device  76 . Second anvil  74  is shown in a working position. Mandrel  78  is shown rotated around the radius of the forming surface of the first anvil  72  to form a partial bend in printing plate  80  and to form an optional geometric feature from the cooperative action of the male die portion  82  and mandrel  78 . 
     Further referring to  FIG. 29 , mandrel  78  includes first forming surface  84  and second adjustable forming surface  86 . Mandrel  78  is shown rotated around the radius of the forming surface of the first anvil  72  to form a partial bend in printing plate  80  and to form an optional desired feature from the cooperative action of the male die portion  82  and first and second forming surfaces,  84  and  86 , respectively of mandrel  78 . In particular, first and second forming surfaces,  84  and  86 , function to force printing plate  80  against male die portion  82  of mandrel  78  such as is illustrated in  FIG. 29 . Second forming surface  86  is adjustable and designed to be moveable relative to first forming surface  84  in any desired direction to adjust the geometry of the feature form. As shown, the formed feature comprises a dimple but any desired feature can be formed in printing plate  80 . 
     Referring to  FIG. 30 , printing plate  80  is shown clamped against the supporting bed of first anvil  72  by clamping device  76 . As compared to the position shown in  FIG. 29 , second anvil  74  has been linearly translated along a machine direction identified by reference numeral  88  wherein second anvil  74  is positioned in a retracted position. Mandrel  78  is shown further rotated around the forming surface of first anvil  72  thus further bending the flange being formed on printing plate  80 . In this way, a two-step bending process is used. The first bending step bends the flange to a first angle and forms any desired geometric feature in the flange. The second step further bends the flange to a second angle greater than the first angle and may be overbent to provide compensation for springback effects. Such two-step bending process can be used with any of the bending apparatuses described herein. 
     The present invention has now been described with reference to several exemplary embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference for all purposes. The foregoing detailed description has been provided for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that changes can be made in the exemplary embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the exemplary structures and methods described herein, but only by the structures and methods described by the language of the claims and the equivalents of those structures and methods.