Patent Publication Number: US-7715058-B2

Title: System and method for improved engraving of gravure cylinders by adjusting engraving signal responsive to movement of shoe position

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to engraving devices, and more particularly to a method and apparatus for detecting surface irregularities and for correct adjustment of engraving in response thereto. 
   2. Description of the Related Art 
   Prior art devices of the type shown in U.S. Pat. Nos. 4,450,486; 5,424,846; 5,438,422; 5,424,845; 5,329,215; 5,652,659 typically comprise an engraving head having an engraving device, such as a diamond stylus, and a guide shoe. The guide shoe bore against a surface of a cylinder and provided a reference for the engraving process. An electromagnetic driver mounted within the engraving head caused the engraving device to oscillate into engraving contact with the cylinder as the cylinder rotated about its cylindrical axis, thereby causing either a helical or cylindrical tract of engraved areas or cells to be engraved on the surface of the cylinder. 
   The cylinders engraved oftentimes had surface irregularities, such as indentations or “bumps” or other artifacts that appeared on the surface of the cylinder. In engraving heads of the prior art, the engraving head had a sliding shoe mount assembly that was very stiff and forced the entire engraving head to follow the surface of the cylinder. The goal of the engraving process is to cut diamond-shaped cells into the surface of a copper cylinder that will be used for gravure printing. The depth of the holes or cells must be controlled with an error less than a fraction of a micron (micro meter). This control must take place while the surface of the cylinder moves radially by hundreds of microns. By having the entire head follow the surface of the cylinder, a cutting diamond stylus is provided with a local reference as to where the cylinder surface is so that it can accurately cut to depth. 
   A present shoe mount assembly is provided in the engraving machine model number 850-GS-XX available from Max Daetwyler Corporation, the assignee of the present invention. The head has a brass finger about two inches long that flexes in a radial (cylinder radial) direction under the force of a screw. The finger is mounted to the engraving head casting at the bottom and the sliding shoe mounts to the top end of the finger. The top of the finger is supported radially (again with respect to the cylinder) from behind by a fine-threaded screw. The screw adjusts the position of the shoe with respect to the engraving head casting and provides a stiff support from between the shoe and the casting. The result is a stiff, but adjustable, support for the sliding shoe. The effective mass of the engraving head is, in a typical engraver, approximately six kilograms. 
   In other engraving systems, such as systems provided by Rudolph Hell Company, the engraving head and the shoe diamond is mounted to the tip of a screw threaded into the casting of the engraving head. The axis of the shoe screw is oriented radially with respect to the cylinder surface. Rotating the shoe screw adjusts the relative position of the engraving head casting and thus the position of the cutting diamond relative to the surface of the cylinder. The effective mass of these types of engraving heads is on the order of about two kilograms. 
   The gravure industry has changed recently and where the surface of the cylinder to be engraved could be seen to be nearly perfect, many customers now want to use much rougher cylinder surfaces. With rougher surfaces, more force is applied to the sliding shoe while following the cylinder surface and the force shows up as change in depth of the engraving. The engraving head and the carriage on which it is mounted have mechanical vibrations that can be excited by the shoe dragging on the cylinder surface. Vibration modes can be excited both radially and tangentially to the cylinder. If a lightly dampened vibration mode is driven by a cylinder surface ripple that happens to fall at the vibration resonance, the resulting resonance vibration buildup can be larger than the original surface ripple. All of this causes the size and/or shape of the engraved cells to be inaccurate. 
   What is needed, therefore, is a method and apparatus for improving engraving and overcoming the problems associated with surface irregularities. 
   SUMMARY OF THE INVENTION 
   In one aspect, one embodiment provides a system and method for reducing the mass that is following the surface of the cylinder and, therefore, the engraved response to cylinder surface irregularities. 
   In one aspect, this invention comprises an engraver for engraving a cylinder comprising an engraving bed, an engraving head situated on the engraving bed, the engraving head comprising a shoe for engaging a surface of the cylinder and an engraving stylus, an engraving head control for generating an engraving signal for controlling the engraving stylus, a shoe position sensor coupled to the engraving head control, the shoe position sensor sensing a position of the shoe with respect to the engraving head body and generating a shoe position signal in response thereto, the engraving head control receiving the shoe position signal and adjusting the engraving signal in response thereto. 
   In another aspect, this invention comprises an engraving head for use on an engraver having an engraving bed, a headstock and tailstock for rotatably supporting a cylinder, the engraving head comprising a shoe for engaging a surface of the cylinder, an engraving stylus, an engraving head control for generating an engraving signal for controlling movement of the engraving stylus, and a shoe position sensor coupled to the engraving head control, the shoe position sensor sensing a position of the shoe with respect to the engraving head body and generating a shoe position signal in response thereto, the engraving head control receiving the shoe position signal and adjusting the engraving signal in response thereto. 
   In still another aspect, this invention comprises a method for engraving a cylinder on an engraver having an engraving head comprising the steps of rotatably mounting the cylinder on the engraver, sensing a movement of a shoe position with respect to the engraving head body and generating a shoe position signal in response thereto, adjusting an engraving signal in response thereto. 
   Another object of one embodiment is to able customers to use substantially lower quality cylinders, that is, surface cylinders with substantially greater surface irregularities and to improve printing, even though it is done from lower quality cylinders. 
   Still another advantage is that it may be possible to use lower shoe pressures, which reduces the marking of the engraved surface and coupling less energy into vibration modes in the engraving head and carriage on which the engraving head is mounted. 
   Another embodiment is that the moving shoe technology is rather simple in design and robust and should enable easier manufacturability with lower precision tooling. 
   These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an engraving machine including one embodiment of the invention; 
       FIG. 2  is a fragmentary view showing a shoe holder relative to a stylus arm and stylus; 
       FIG. 3  is a fragmentary view of an engraving head in accordance with one embodiment of the invention; 
       FIG. 4  is an enlarged view of the shoe holder shown in  FIGS. 2 and 3 ; 
       FIG. 5  is an exploded view of the shoe holder shown in  FIGS. 2 and 3 ; 
       FIGS. 6A-6D  are various views illustrating the shoe riding along a surface of a cylinder having imperfections; 
       FIG. 6E  is various diagrams showing an engraving drive signal, an adjusted engraving drive signal and shoe position signal generated by a shoe sensor associated with the shoe support; 
       FIG. 7  is a fragmentary view illustrating the pivotal mount of the engraving head and a damper associated therewith; 
       FIG. 8  is a fragmentary view showing the engraving head and damper in a operating position; 
       FIG. 9  is an enlarged view of a damper well for receiving fluid; 
       FIG. 10  is a view of a shoe sensor circuit in accordance with one embodiment of the invention; and 
       FIG. 11  is a flow diagram illustrating a control algorithm for sensing movement of the shoe and adjusting the engraving signal in accordance with one embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  is a general perspective view of a preferred embodiment of an engraver, designated generally as engraver  10 . 
   In the embodiment being described, the engraver  10  is a gravure engraver, but the invention may be suitable for use in other types of engravers, such as laser engravers. 
   The engraver  10  is a gravure engraver for engraving a surface  12   a  of a cylinder  12  which will subsequently be used to print a predetermined pattern of cells on a substrate. The cylinder  12  will then be placed in a printing machine and in a gravure printing process to thereby print via the gravure printing process on the substrate. The cylinder  12  has the surface  12   a  which has an engravable coating, such as copper. 
   The engraver  10  comprises a base  14  having a headstock  16  and a tailstock  18  slidably mounted on a bed  20  situated on the base  14 . The headstock  16  and tailstock  18  are slidably and adjustably mounted on the bed  20  with suitable bearings and drive train (not shown) such that the headstock  16  and tailstock  18  can rotatably support the cylinder  12  there between. The engraver  10  also comprises a carriage  22  which is slidably mounted on the bed  20  with suitable bearing and drive train (not shown). The carriage  22  may be driven in a direction of double arrow  24  in order to affect engraving as described herein. Notice also that engraver  10  comprises an engraving head  26  which is slidably or moveably mounted on the carriage  22  such that it can be driven towards and away from the cylinder  12  in the direction of double arrow  28  in  FIG. 1 . 
   The engraver  10  also comprises a plurality of actuators of drive means or drivers  30  that are capable of rotatably driving the cylinder  12 . The drivers  30  comprise suitable motors and drive mechanisms (not shown) for selectively driving carriage  22  and engraving head  26  to engrave the engrave cells into the surface  12   a  of the cylinder  12 . If desired, the drivers  30  may also comprise at least one suitable drive motor and drive train (not shown) for driving the headstock  16  and tailstock  18  into and out of engagement with the cylinder  12 , thereby eliminating the need for manual adjustment. For example, the drivers  30  may cause the headstock  16  and tailstock  18  to be actuated to a fully retracted position (not shown) or to a cylinder support position shown in  FIG. 1 . The drivers may be selectively energized to cause the headstock  16  and tailstock  18  to be actuated either independently or simultaneously. 
   Although, not shown, a single drive motor may be used with a single lead screw (not shown) having reverse threads (not shown) on which either end causes the headstock  16  and tailstock  18  to move simultaneously towards and away from each other as the lead screw is driven. Driving both the headstock  16  and tailstock  18  permits cylinders  12  of varying lengths to be loaded by an overhead crane, for example, whose path is perpendicular to the axis of rotation in the cylinder  12 . However, it should be appreciated that a stationary headstock  16  and tailstock  18  may be used when with a driven headstock  16  and tailstock  18 , respectively, if, for example, a cylinder loading mechanism (not shown) loads the cylinder by moving in a direction which is generally parallel to the axis of rotation of the engraver. 
   The drivers  30  may also drive a lead screw (not shown) which is coupled to the carriage in order to affect the driving of the carriage  22  in the direction of double arrow  24 . Likewise, drivers  30  may also drive a drive train or lead screw which causes the engraving head  26  to move on the carriage in the direction of double arrow  28  towards and away from the cylinder  12 . The engraving head  26 , carriage  22  and the driven movement thereof is similar to that shown in U.S. Pat. Nos. 5,438,422, 5,424,845, 5,329,215 and 5,424,846, U.S. Pat. No. 4,450,586 issued to the same assignee as the present application on May 22, 1984; U.S. Pat. No. 4,438,460 issued to the same assignee as the present invention on Mar. 20, 1984; U.S. Pat. No. 4,357,633 issued to the same assignee as the present invention on Nov. 2, 1982; and U.S. Pat. No. 5,329,215 issued to the same assignee as the present invention on Jul. 12, 1994, all of which are incorporated herein by reference and made a part hereof. 
   The engraver  10  comprises control means, a controller or a computer  34  for controlling the operation of the engraver  10 , engraving head  26  and also comprises an engraving control  37  for generating an engraving signal ES ( FIG. 6E ) corresponding to a selected predetermined pattern to be engraved. The computer  34  also selectively controls all the drive motors, such as drivers  30  mentioned above, in the engraver. The engraving control  37  controls the oscillation or movement of an engraving stylus  40  in response to the engraving control  37 . 
   Notice in  FIG. 1  that the system and engraver  10  further comprises a shoe sensor circuit  38  whose structure and operation will be described later herein. 
   Referring now to  FIG. 2 , notice that the engraving head  26  comprises the engraving stylus  40  that holds a cutting tool, such as a diamond stylus  42  in a manner that is conventionally known. The engraving head  26  further comprises a shoe holder assembly  44  that is mounted and secured directly to a body  26   a  of the engraving head  26  as described later herein. The shoe holder assembly  44  comprises a shoe  46  that engages and “rides” along the surface  12   a  of the cylinder  12  as the stylus  42  is caused to oscillate in order to engrave cells (not shown) in the surface  12   a  of the cylinder  12 . It should be understood that the shoe assembly  44  is fixably or moveably mounted to the engraving head housing  26   a  in a manner that will now be described relative to  FIGS. 2-5 . 
   Notice in the exploded view in  FIG. 5 , the shoe assembly  44  comprises a shoe support  48  onto which a main shoe block or holder  50  is adjustably mounted. Notice that the shoe  46  is integrally secured and mounted to a front face  50   a  ( FIG. 5 ) in shoe block  50  with a conventional machine screw  54  that is received in a threaded aperture  57 . Note that the shoe holder  50  has the front face  50   a  and a rear face  50   b  that are coupled or flexibly mounted directly to support  48  with a first spring sheet  56  and second spring sheet  58 . The first spring sheet  56  is coupled or secured to a face  48   a  of support  48  with a first mounting block  60  having apertures  60   a - 60   d  for receiving the threaded machine screws  62 ,  64 ,  66  and  68  respectively. The first spring sheet  56  comprises apertures  70 ,  70   a ,  70   b ,  70   c  and  70   d  that also receive the machine screws  94 ,  96  and  62 - 68 , as shown. The machine screws  62 - 68  are screwed into the threaded apertures (not shown) in the face  48   a  of support  48 . 
   Likewise, a second block  72  comprises apertures  72   a ,  72   b ,  72   c  and  72   d  for receiving the screws  74 ,  76 ,  78  and  80 , respectively. The screws  74 - 80  are received in the apertures  72   a - 72   d  and corresponding apertures  82   a ,  82   b ,  82   c  and  82   d  in spring sheet  58  and threaded into the threaded apertures  84 ,  86 ,  88  and  89  as shown. It should be understood that support  48  has surfaces  48   c  and  48   e  that are machined to provide relief areas to allow unobstructed and small motion of the spring sheets  56  and  58  in the direction of double arrow C in  FIG. 4 . 
   The shoe block  50  is clamped to the spring sheets  56  and  58  with spacer blocks  90  and  92  that have apertures  90   a ,  90   b  and  92   a ,  92   b , respectively, that receive the machine screws  94  and  96 ,  98  and  100 , respectfully, as shown. The screws  94 - 96  are situated through the apertures  90   a  and  90   b  and through apertures  70  and into threaded apertures on the face  50   b . The screws  98 ,  100  are situated through apertures  92   a  and  92   b  and through aperture  92   d  and  92   c  and into the threaded openings on the face of block  50  as shown. 
   Note that a surface  48   a  of support  48  comprises a notched-out or relief area  48   b . A surface  48   c  provides a stop against which the surface  56   a  of spring sheet  56  can move to stop excessive forward movement of the shoe holder  50  toward the cylinder  12 ; after the support  48  is mounted to the engraving head housing  26   a  of engraving head  26 . The support  48  comprises a notched-out area  48   d . A surface  48   e  provides a stop to prevent excessive aft movement via spring plate surface  58   a  of the shoe  46  away from the surface  12   a  of cylinder  12 . Thus, the surfaces  48   c  and  48   e  prevent the spring sheets  56  and  58  from moving beyond a plane defined by the surfaces  48   c  and  48   e , thereby permitting the spring sheets  56  and  58  to move closer to the surfaces  48   c  and  48   e , respectively. This enables control of the movement of the shoe holder  50  relative to the support  48  and shoe  46  toward and away from the surface  12   a  of cylinder  12 . 
   Note from the assembly illustrated in  FIG. 4  that the main shoe block  50  carries and moveably supports the shoe support  52  that holds the shoe diamond and provides linear travel radially relative to the cylinder surface  12   a  because the spring sheets  56  and  58  are mounted in a generally parallel relationship and in a parallelogram-type mount configuration. This enables the required linear travel of the shoe holder  50  relative to the surface  12   a  of the cylinder  12  and relative to the engraving head  26 . In one embodiment of the invention, the required range of travel of the shoe holder  50  is on the order of about plus or minus 100 microns (micro meters). The spring mount region or area  110  ( FIG. 5 ) at the front of the holder  50  is dropped vertically to define the area  110  for the shoe diamond plate or shoe support  52 . The shoe diamond plate  52  mounts to the front of the shoe holder  50  as shown. Alignment grooves  50   d  and  50   c  are machined into a front face  50   f  of the shoe holder  50  to control the orientation of the shoe diamond plate and therefore the shoe  46 . 
   In one embodiment, such as the embodiment illustrated in  FIG. 4 , the shoe block  50  is made of a lightweight material, such as aluminum, to keep its mass low. The shoe block  50  comprises a target  50   e  ( FIG. 4 ) for a linear induction or proximity sensor  102 . In this regard, notice that the main shoe block  50  comprises the target or projection  50   e  that lies in a plane that is generally parallel to the plane in which the spring sheets  56  and  58  lie. The target  50   e  that cooperates with the linear induction or proximity sensor  102  that senses a movement of the block  50  and generates a sensed shoe position signal (SSP) ( FIG. 6 ) in response thereto. The sensed shoe position signal SSP is received by the engraver control  37  and which may adjust the engraving drive signal ES to provide an adjusted engraving drive signal (AS) in response to the shoe position signal SSP. The operation and function of the sensor and engraving control will be described later herein. 
   Returning to  FIGS. 2-5 , note that the vertical spring sheets  56  and  58  are on the order of about 35 millimeters tall and about 12 millimeters wide. The thickness of the spring sheets  56  and  58  is chosen to give the block  50  a proper or predetermined amount of stiffness. The block  50  approximate stiffness should be in the region of about one micron of deflection per Newton of applied force, but a smaller or larger amount of stiffness may be used. Note that spring sheets  56  and  58  are clamped onto their bottom and top quarter of quarters of surfaces  56   a  and  58   a  to enable the sheets  56  and  58  to flex in an elongated S shape. Thus, it should be understood that the spring sheets  56  and  58  are considered to be a “fixed-fixed” type of mount. 
   As illustrated in  FIG. 4 , the sensor  102  is mounted in the bracket  104  as shown. The bracket  104  is, in turn, secured to the support  48  with machine screws  106 ,  108  that are threadably received in threaded apertures (not shown) in the support  48 . Notice that after the sensor  102  and bracket  104  are mounted to the block  50 , the sensor  102  becomes operatively associated with a surface  50   e   1  of the target  50   e , as illustrated in  FIG. 4 . It should be understood that as the shoe holder  50  moves in the direction of double arrow C in  FIG. 4 , the surface  50   e   1  will move in relation to the sensor  102 , which is fixed relative to the support  48 . The sensor  102  cooperates with target  50   e  and senses this movement and generates the sensed signal SSP in response thereto. The sensed signal SSP will be received by the engraver control  37  and computer  34  and further processed as described later herein. Thus, the transducer or sensor  102  senses the target  50   e  of the shoe holder  50  and thereby measures a relative position of the shoe holder, and consequently, a position of the shoe  46  relative to the support  48 . 
   A damping means or system will now be described relative to  FIGS. 7-9 . Notice that the engraving head  26  is mounted on a platform axle  111 . The axle  111  is mounted on a pair of supports  112  and  114  that are bolted to a surface  22   a  ( FIGS. 6A-D ) that is integral with or mounted to carriage  22  as shown. The engraving head  26  is mounted on a frame  116 , mounted on axle  111 , that pivots about an axis E of axle  111 , thereby permitting the head  26  to pivot in the direction of double arrow D toward and away from the cylinder  12  as shown. 
   Mounted between the pivoting engraving head  26 , frame  116  and surface  22   a  of the carriage  22  is a damping system or means  118 . As best illustrated in  FIGS. 7-9 , note that the surface  22   a  of carriage  22  comprises an aperture  120  for receiving and supporting a spring  122 . An end  122   a  of spring  122  engages a surface  116   a  of the frame  116  onto which the engraving head  26  is mounted. A guide screw or bolt  124  may be received in an aperture or opening  128  defined by the coil of the spring  122  to facilitate maintaining the spring  122  in a generally upright position after the platform or frame  116  is moved from the non-engraving position illustrated in  FIG. 7  to the engraving position illustrated in  FIG. 8 . 
   As illustrated in  FIG. 7 , notice that the damper  118  comprises a well  130  and a comb  132  having a plurality of combs  134  that are generally parallel. In the embodiment being described, the well  130  receives a viscous fluid, such as silicone oil. It should be understood that when the engraving head  26  is moved to the engraving position illustrated in  FIGS. 1 and 8 , the combs  134  interleave with a plurality of combs  136  so that there is a large parallel surface areas and small gap between the combs  134  and  136 . The volume of area  130   a  toward and away from cylinder  12  and in the well  130  between the combs  136  with the viscous fluid. When the engraving head  26  moves in the direction of double arrow D ( FIG. 7 ) or generally parallel to the planes in which the combs  134  and  136  lie, the viscous liquid or fluid undergoes a shear. The area  130   a , gap (i.e., distance between combs) and fluid viscosity are chosen to develop a desired viscous damping force, which is defined as Newtons of force developed per unit of velocity (meters per second). The value of the damping is selected to achieve a damped resonance between the mass of the engraving head  26  and a spring coefficient of the shoe mount as dictated by the spring sheets  56  and  58 . The damping coefficient or value must also satisfy a compromise that a force developed during cylinder run-out or rotation tracking does not cause excessive shoe movements, which is a correction that can be handled electronically. 
   Referring now to  FIG. 10 , the engraver control  37 , which may be situated on a common card (not shown) as other components (not shown) of the computer  34 , comprises the circuit  138  ( FIG. 10 ) having signal electronics are generally characterized in that a relatively small positioned transducer or sensed shoe position (SSP) signal is generated by the sensor  102  and is amplified to a level where it can be sent to the engraving head  26  electronics card (not shown). The amount of amplification is adjusted so that the resulting commanded motion of the cutting stylus  42  generally matches or relates to the motion of the shoe  46  which is affixed to the main shoe block  50 . If the sensor  102  has a drift greater than acceptable for engraving, a drift correction circuit  140  may be added to the amplification electronics. A low pass noise filter  142  may also be added to the electronics to reduce or eliminate noise above a predetermined frequency, thereby improving the signal-to-noise ratio of the correction signal. 
     FIG. 10  illustrates the circuit  138  for performing the correction described herein. A simplified illustration will now be described relative to the views in  FIGS. 6A-6D . In the illustration being shown in  FIG. 6A , the cylinder  12  has an imperfection, such as a “bump” B 1  or B 2  or indentation I 1  or I 2 . Note that the movement of the shoe  46  is independent of the stylus  42 . 
   As illustrated at blocks  160  and  182  in  FIG. 11 , the shoe  46  is driven against cylinder  12  and the drives  30  ( FIG. 1 ) rotate cylinder  12 . The shoe  46  follows the surface  12   a  of the cylinder  12  and upon encountering the bump B 1  or B 2 , the shoe  46  follows surface  12   a  and moves away from the cylinder  12 . If the imperfection was an indentation, such as I 1  or I 2 , for example, the block  50  and shoe  46  move toward an axis of the cylinder  12 . In response to the movement of the block  50 , the sensor  102  cooperates with the target  50   e  and generates the sensed shoe position signal (SSP) in response thereto at block  164  in  FIG. 11 . The drift correction circuit  140  may be provided to correct for long term sensor drift at the start of engraving. The low pass noise filter  142  may be provided to reduce or eliminate signal noise above a predetermined kilohertz level in order to improve the correction signal that will be used by the engraving head  26  electronics. 
   A gain control  144  is provided to set the amount of SSP signal on line  152  which is received by engraver stylus arm electronic control  150  along with engraving command signals received from the computer  34 . Thus the SSP signal on line  152  is added to the engraving signal ES from the engrave control computer  34  and the combined adjusted signal AS is sent to the engraver drive electronics  146 . The engraving signal AS is received by an amplifier  148  which, in turn, energizes an engraving stylus drive motor  158  which is coupled by a conventional drive linkage  156  to the stylus  42 . 
   Advantageously, the circuit  138  provides means, system and apparatus for generating a correction signal in response to a movement of the shoe  46  by sensing the movement of the shoe  46  and then generating the sensed signal SSP that is used to modify the engraving command signal ES to provide the adjusted signal AS. Thus, accurate adjustments of the stylus  42  can be adjusted to accommodate for imperfections in the surface  12   a  in the cylinder  12 . 
     FIG. 6  illustrates a series of diagrammatic views showing the corresponding movement of the shoe  46  and the corresponding signals AS, ES and SSP. 
   Referring now to  FIG. 11 , a general procedure or method of correction will now be described. The procedure starts at block  160  wherein the guide shoe  46  is placed against the cylinder surface  12   a  of cylinder  12 . The cylinder  12  is rotated for engraving at block  162 , the sensor  102  cooperates with target  50   e  and generates the sensed signal SSP in response to imperfections in the surface  12   a  of cylinder  12  which in turn corresponds directly to the shoe  46  as it follows the surface  12   a . If necessary, the engraving signal is adjusted (block  166 ). The circuit  138  causes the engraver control  36  to adjust the engraving drive signal ES in response thereto. Thereafter, the engraver performs engraving (block  168 ). 
   Upon completion of engraving, the cylinder  12  is removed (block  170 ) from the engraver  10  and ultimately used in a printing press for printing on a substrate. 
   While the method herein described, and the form of apparatus for carrying this method into effect, constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention, which is defined in the appended claims.