Method and apparatus for cleaning printing presses for three dimensional objects

Abstract

An apparatus and method cleans rollers on printing presses that print indicia on three dimensional objects such as candies, confectionaries and other comestible items. The cleaning apparatus moves in three axes to position itself alternately opposite an engraved roller and a blanket roller. The cleaning apparatus dry cleans one roller and dry and/or wet cleans the other roller. The apparatus has a cleaning pad that extends toward a web of cleaning material to press the cleaning material against a roller. The apparatus moves across the roller to wipe ink and/or debris from the surface of the roller.

Claims

1. A method for cleaning a printing press, comprising: providing a moveable cleaner for travelling along a path parallel to the axis of an engraved roller or a blanket roller of the printing press for cleaning the surfaces of the engrave and blanket rollers, wherein the movable cleaner includes a frame, unwind and rewind spindles carried by the frame, wherein the rewind spindle is spaced from unwind spindle, and a web configured for advancing from the unwind spindle to the rewind spindle, wherein the web defines a cleaning surface configured for engaging one of the first and second rollers, the cleaning surface positionable in at least a first retracted position relative to the frame and second and third extended positions relative to the frame; positioning the movable cleaner proximate the blanket roller; performing at least one dry cleaning operation on the blanket roller by extending the cleaning surface of the web from the first retracted position to the second extended position, pressing the cleaning surface against the blanket roller with a first pressure, and moving the moveable apparatus along a path parallel to the axis of the first roller such that the cleaning surface traverses the first roller; positioning the moveable cleaner proximate the engraved roller; and performing at least one wet cleaning operation on the engraved roller by extending the cleaning surface of the web from the first retracted position to the third extended position, pressing the cleaning surface against the second roller with a second pressure, wherein the second pressure is greater than the first pressure, moistening the cleaning surface with cleaning fluid, and moving the cleaner along a path parallel to the axis of the second roller such that the cleaning surface traverses the second roller.

2. A method for cleaning a printing press, comprising: providing a cleaner for travelling along a path parallel to the axis of an engraved roller or a blanket roller for cleaning the surfaces of the engraved roller and the blanket roller, wherein the cleaner includes a frame and a cleaning surface, the cleaning surface being positionable in at least a first retracted position relative to the frame and second and third extended positions relative to the frame; positioning the cleaner proximate the blanket roller and moving the cleaning surface from the first retracted position to the second extended position; performing at least one dry cleaning operation on the blanket roller with the cleaning surface positioned in the second extended position to impart a first pressure on the blanket roller; positioning the cleaner proximate the engraved roller and moving the cleaning surface from the first retracted position to the third extended position; and performing at least one wet cleaning operation on the engraved roller with the cleaning surface positioned in the third extended position relative to the frame to impart a second pressure on the engraved roller, wherein the second pressure is different from the first pressure.

3. The method of claim 2, wherein performing at least one dry cleaning operation includes moving the cleaner along a path parallel to the axis of the blanket roller such that the cleaning surface of the cleaner traverses the blanket roller, imparting the first pressure on the blanket roller.

4. The method of claim 2, wherein performing at least one wet cleaning operation includes moistening the cleaning surface with cleaning fluid, and moving the cleaner along a path parallel to the axis of the engraved roller such that the cleaning surface of the cleaner traverses the engraved roller, imparting the second pressure on the engraved roller.

5. The method of claim 1, wherein the at least one wet cleaning operation is a wet wiping operation at a second pressure and a first fluid flow rate to the cleaning surface.

6. The method of claim 1, wherein the at least one wet clean operation is a wet washing operation at a third pressure and a second fluid flow rate to the cleaning surface.

7. The method of claim 6, wherein the second pressure is different from or the same as the third pressure.

8. The method of claim 6, wherein the second fluid flow rate is greater than the first fluid flow rate.

9. The method of claim 2, wherein the cleaner includes a piston and piston rod for moving the cleaning surface from the first retracted position to the second extended position.

10. The method of claim 2, wherein the cleaner includes a piston and piston rod for moving the cleaning surface from the first retracted position to the third extended position.

11. The method of claim 2, wherein the at least one wet cleaning operation is a wet wiping operation at a second pressure and a first fluid flow rate to the cleaning surface.

12. The method of claim 2, wherein the at least one wet clean operation is a wet washing operation at a third pressure and a second fluid flow rate to the cleaning surface.

13. The method of claim 12, wherein the second pressure is different from or the same as the third pressure.

14. The method of claim 12, wherein the second fluid flow rate is greater than the first fluid flow rate.

15. The method of claim 2, wherein the cleaner includes a piston and piston rod for moving the cleaning surface from the first retracted position to the second extended position.

16. The method of claim 2, wherein the cleaner includes a piston and piston rod for moving the cleaning surface from the first retracted position to the third extended position.

17. A method for cleaning a printing press, comprising: providing a cleaner for travelling along a path parallel to the axis of a first or second roller of the printing press for cleaning the surfaces of the first and second rollers, wherein the cleaner includes a frame and a cleaning surface configured for engaging one of the first and second rollers, the cleaning surface positionable in at least a first retracted position relative to the frame and second and third extended positions relative to the frame; positioning the cleaner proximate the first roller; performing at least one dry cleaning operation on the first roller by extending the cleaning surface of the web from the first retracted position to the second extended position, pressing the cleaning surface against the first roller with a first pressure, and moving the moveable apparatus along a path parallel to the axis of the first roller such that the cleaning surface traverses the first roller; positioning the cleaner proximate the second roller; and performing at least one wet cleaning operation on the second roller by extending the cleaning surface of the web from the first retracted position to the third extended position, pressing the cleaning surface against the second roller with a second pressure, wherein the second pressure is greater than the first pressure, moistening the cleaning surface with cleaning fluid, and moving the cleaner along a path parallel to the axis of the second roller such that the cleaning surface traverses the second roller.

Description

DESCRIPTION OF THE DRAWINGS

(1) The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is a schematic representation of an embodiment of a cleaning apparatus for cleaning engraved and blanket rollers of a printing press;

(3) FIG. 2 shows an area of cleaning cloth superimposed on the engraved roller and the blanket roller;

(4) FIG. 3 is a schematic side view of a speed encoder for determining the speed of the blanket support roller;

(5) FIG. 4 is a bottom perspective view of a cleaning head made in accordance with one embodiment;

(6) FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4;

(7) FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 4;

(8) FIG. 7 is similar to FIG. 6, but showing the cylinder extended to an intermediate position;

(9) FIG. 8 is similar to FIG. 6, but shows the cylinder extended to its fully extended position;

(10) FIG. 9 is a schematic diagram of the interconnection of the various components of one embodiment of the cleaning apparatus;

(11) FIG. 10 is a flow chart showing the operation of one embodiment of the cleaning apparatus;

(12) FIG. 11 is a perspective view of a table supporting the cleaning apparatus; and

(13) FIG. 12 is a side view of the table of FIG. 11 disposed over the engraved and blanket rollers of an offset printing press.

DETAILED DESCRIPTION

(14) Referring to FIG. 1, a cleaner 2 is disposed above a blanket roller 4 that is carried on a first support roller 6 that turns in a clockwise direction. The blanket roller 4 is made of a compliant, resilient material, such as rubber. The blanket roller 4 contacts raised indicia 9 on the surface of engraved roller 3 that is carried on second support roller 7. Engraved roller 3 turns in a counterclockwise direction and passes the raised indicia 9 through ink 300 in tank 302. The engraved roller 3 is made of hard, rigid material, such as ceramic or steel. A doctor blade 304 wipes excess ink off the surface of the indicia 9. Ink on the indicia 9 is transferred to the blanket roller 4 to provide an inked image of indicia on the blanket roller 4. The inked image is transferred to objects 308 that are carried by a conveyor or web 306 that travels in the direction of arrow A. Cloth 58 of the cleaner 2 engages the surface of the blanket roller 4 to remove ink and debris. The cloth 58 is a dry, absorbent cloth with a relatively smooth, non-abrasive finish. At a suitable time, cleaner 2 may be moved to the right in one direction of arrow B and up in one direction of arrow C to locate the cleaner 2 adjacent to raised, rigid indicia 9 on the engraved roller 3. After cleaning engraved roller 3, the cleaner 2 is moved down and to the left in the other directions of arrows B and C to position the cloth 58 adjacent the surface of the blanker roller 4.

(15) Referring to FIG. 2, area 310 represents the surface of the cloth 58 in contact with the blanket roller 4. The arrow D indicates the cleaner 2 traverses a path back and forth on the surface of the blanket roller 4 while it is turning. The dashed area 310 above engraved roller 3 corresponds to the area of the cloth on the engraved roller 3. The cleaner 2 traverses a path back and forth on the surface of the engraved roller 3 while it is turning. It is optional for cleaner 2 to perform a dry clean operation on the engraved roller 3. The cleaner 2 will also perform a wet wipe while it strongly presses the cloth 58 against the indicia 9 and applies cleaning fluid to perform a wet wipe. In addition, bristles as shown in FIG. 8, further assist cleaning ink and debris from the engraved roller 3. The cleaner 2 may provide a final dry wipe before printing is resumed.

(16) Referring to FIGS. 3 and 12, a speed encoder 22 has an encoder wheel 24 that provides rotational speed information to a motor 232 so that the traverse speed of the cleaner 2 across the blanket roller 4 may be adjusted automatically, depending on the rotational speed of the first support cylinder 6 so that the same amount of contact between the cleaner 2 and the blanket roller 4 is maintained regardless of the first support cylinder's speed. The encoder wheel 24 is mounted in a standard manner for rotational engagement with the first support cylinder by means of a pivot arm 26 mounted to a bracket 28.

(17) Referring to FIGS. 4 and 12, the cleaning head 10 comprises a frame 30 secured to a carrier block 32, which in turn is operably secured to the endless belt 234 within the actuator housing 230. It will be understood that as the belt 234 is actuated clockwise or counterclockwise by the motor 232 the cleaning head 10 will traverse left or right along a linear path parallel to the axis of rotation of the blanket roller 4 and the blanket support cylinder 6.

(18) A base structure 36 is operably secured to the frame 30. A double-acting three-position cylinder 38 is attached to the base structure 36 in a standard manner, such as by bolts 40 shown in FIG. 5. Fluid hoses 42 communicate within the cylinder 38, as will be discussed below. A front portion of the base structure 36 includes a recess 44 in which a backing plate 46 is disposed. The backing plate 46 is operably secured to the cylinder 38 as will be discussed below. A sponge pad 48 and bristles 50 are operably secured to the backing plate 46. The backing plate 46 operates as a pressure plate to transmit pressure from the cylinder 38 to the sponge pad. A cleaning fluid inlet hose 52 communicates with a passageway within the backing plate 46 to deliver the cleaning fluid to the sponge pad 48. The sponge pad, in some embodiments, is an open cell polyurethane foam.

(19) A roll 54 of cloth 58 is carried by an unwind spindle 56. The cloth 58 is coursed from the roll 54 to underneath, in front and on top of the base structure 36 and wound around a rewind spindle 60 driven by a motor 62. The rewind spindle 60 is driven by the motor 62 by conventional means such as belt 72, shown in dashed lines. A low cloth sensor 64 provides an alarm when the supply cloth roll 54 is nearly used up. The sensor 64 includes a pivoting arm 66 with one end in engagement with a used roll 68 and the other end being associated with a switch 70. As the used roll 68 increases in diameter, the arm 66 pivots radially, eventually activating the switch 70 to send an alarm to a controller when the used roll 68 reaches a certain diameter indicative of the cloth roll 54 being nearly used up. For some embodiments, the low cloth sensor 64 is further described in U.S. Pat. No. 5,519,914. In such embodiments, the cloth 58 is a highly absorbent clean room grade, 100% woven polyester linen available from Lymtech Scientific, Chicopee, Mass. under the designation Purity Wipes. However, other cloths including non-woven material may be used in alternate embodiments.

(20) Referring to FIG. 5, the backing plate 46 includes a passageway 74 that communicates with the inlet hose 52 and outlet ports 76 to deliver the cleaning fluid from a reservoir to the sponge pad 48 and to the cloth 58. Since the sponge pad 48 is in direct contact with the cloth 58, the cleaning fluid in the sponge pad is absorbed by the cloth.

(21) Referring to FIG. 6, the bristles 50 are disposed along the top and bottom edges of the sponge pad 48. The bristles 50 are slightly shorter than the thickness of the sponge pad 48.

(22) The cylinder 38 comprises chambers 78 and 80 separated by a wall 82. A piston 84 with a piston rod 86 is disposed in the chamber 78. A piston 88 and its associated piston rod 90 are disposed within the chamber 80. The piston rod 86 extends through an opening in the wall 82 and engages the piston 88. The piston rod 90 extends through an opening through an end wall 92 and through an opening in a bottom wall 94 of the recess 44. A bolt 96 or other standard means secures the piston rod 90 to the backing plate 46. An end wall 98 encloses the chamber 78. Fluid inlet port 100 communicates with the chamber 78 and inlet ports 102 and 104 with the respective chamber 80, as best shown in FIG. 6.

(23) The cylinder 38 has a fully retracted position, as shown in FIGS. 5 and 6, an intermediate extended position, as shown in FIG. 7 for dry cleaning either roller 3 or 4, and a fully extended position, as shown in FIG. 8 for wet cleaning engraved roller 3. In the retracted position, the pistons 84 and 88 are both retracted and the backing plate 46 is fully seated within the recess 44.

(24) When pressurized fluid, such as compressed air, is supplied to fluid inlet port 100, the piston 84 moves to the wall 82, and pushes the piston 88 to an intermediate position within the chamber 80, thereby pushing the backing plate 46 partway toward the blanket roller 4, causing the cloth 58 to make contact with the blanket roller 4 with sufficient pressure to wipe the blanket roller 4 or the engraved roller 3 as it turns with the respective support cylinders 6, 7. At this position, called the dry wipe mode, a very low air pressure, for example less than 20 psi, allows the sponge pad 48 and the cloth 58 to float over the surface of the plate 4. The dry wipe mode allows the cloth to lightly collect ink from the blanket roller and debris (hickies) from the roller surfaces, and allows a light, dry and continuous wiping of each roller, resulting in greatly improved printing quality without stopping the press to handle the blanket roller and without any cleaning fluid.

(25) To clean the engraved roller 3, the printing operation is interrupted and the cleaner 2 is repositioned to urge the web 58 of cleaning material against the engraved roller 3. It is optional to provide one or more initial dry wipes of the engraved roller 3 before making a wet wipe. After the initial dry wipes are finished, the cleaner operates in its wet wipe mode.

(26) The cleaner 2 traverses the surface of the engraved roller 3 while the roller is turning. The cleaner 2 may clean the engraved roller 3 in a wipe mode or a wash mode. In the wipe mode, the pressure applied to the web 58 and the cleaning fluid supplied to the web are less than the wet wipe mode. In a further optional operation, the cleaner 2 may provide one or more dry wipe modes.

(27) During the wash mode, pressurized fluid is supplied to the fluid inlet port 102, the piston 88 moves to the end wall 92 and causes the backing plate 46 to move further towards the engraved roller 3, thus further depressing the sponge pad 48 and causing the bristles 50 to protrude through the weave of the cloth 58 and make contact with the engraved roller 3 to provide thorough scrubbing of the contoured surface of the engraved roller 3. At this position, more aggressive cleaning is provided by the bristles whenever the press is not in production. During the wash mode, a higher pressure, for example 30 psi, is supplied to the inlet port 102 to allow a greater force to be applied to the backing plate 46, urging the bristles to make more forceful contact with the plate. A higher fluid flow rate is also provided to the sponge pad 48 to allow a more thorough washing of the engraved roller 3, which is done offline when printing is not being performed. The wash mode thoroughly soaks the sponge pad to assist with the removal of dried ink from the surface of the engraved roller 3. Separate liquid control is provided for the wet wipe mode compared to the wash mode.

(28) The various components of the cleaner 2 are controlled from a programmable controller 106. The inlet hose 52 for the cleaning fluid is connected to a solenoid valve 108 which in turn is connected to a liquid pressure vessel 110 with a level sensor 112 connected to the controller 106. The inlet fluid port 110 of the cylinder 38 is connected to a solenoid valve 114. The fluid inlet port 102 is connected to another solenoid valve 116, set at a higher pressure than the valve 114. The valves 114 and 116 are controlled from the controller 106. A compressor 118 supplies compressed air to the pressure vessel 110 and to the cylinder 38.

(29) The operation of the cleaner 2 will now be described. Referring to FIG. 10, the cleaner 2 has three cleaning modes, namely the dry wipe mode, the wet wipe mode and the wash mode. The dry wipe mode is used to remove debris (hickies) on the blanket roller 4 while printing is ongoing. The wet wipe mode is used to gently clean the engraved roller 3 while printing is paused and the wash mode is used to vigorously wash and rinse the engraved roller 3 while the press is offline.

(30) Under the dry wipe mode, the blanket roller width is selected at 120 to control the traverse distance of the cleaning head 10. The traverse speed for the cleaning head 10 across the blanket roller 4 is selected at 124. A cloth advance time is selected at 126 which determines the operation of the rewind motor 62 to draw a new, clean section of the cloth 58 over the sponge pad 48. After the cleaner 2 is started at 128, alarms are checked at 130 for low cloth from the sensor 64. The cleaning head 10 is then moved to the edge of the blanket roller 4 at 132, the cloth is advanced at the selected time at 134, and the sponge pad is extended to the intermediate position at 138 by operating the valve 114 to provide compressed air into the chamber 78. The cleaning head 10 then traverses the length of the blanket roller 4 at 142 while the traverse speed is adjusted based on the speed of the plate cylinder 6, as determined by the speed encoder 22. The cleaning head reverses direction at the end of the blanket roller 4 at 144 and dry cleans the roller as the cleaning head returns to the opposite end of the blanket roller 4. The cleaning head is then retracted at 146 by providing compressed air through the inlet port 104 into the chamber 80. The whole process may be repeated starting at 130 for as many times as desired until the operator exits at 148. In some embodiments, the dry wipe mode is set to cycle at predetermined times such as every ten minutes.

(31) Prior to entering the wet wipe mode, the printing action is interrupted and the cleaner 2 is repositioned to be closely adjacent to the engraved roller 3. The engraved roller 3 is periodically cleaned less frequently than the blanket roller 4. In one embodiment, the engraved roller 3 is cleaned once every hour. During the wet wipe mode, the engraved roller 3 width is selected at 120 to control the traverse distance of the cleaning head 10. A liquid pulse time is selected at 122, which determines the amount of time the solenoid valve 108 is pulsed to inject the cleaning fluid to the sponge pad. The traverse speed for the cleaning head 10 across the engraved roller 3 is selected at 124. A cloth advance time is selected at 126 which determine the operation of the rewind motor 62 to draw a new, clean section of the cloth 58 over the sponge pad 48. After the cleaner 2 is started at 128, alarms are checked at 130 for low cloth from the sensor 64 or for a low liquid level from the sensor 112. The cleaning head 10 is then moved to the edge of the engraved roller 3 at 132, the cloth is advanced at the selected time at 134, the cloth is moistened at 136 by operating the valve 108 and the sponge pad is extended to the intermediate position at 138 by operating the valve 114 to provide compressed air into the chamber 78. The cleaning fluid is then pulsed at 140 by intermittently operating the valve 108, thereby injecting the cleaning fluid through the passageway 74 to the sponge pad 48. The cleaning head 10 then traverses the length of the engraved roller 3 at 142 while the traverse speed is adjusted based on the speed of the support cylinder 7, as determined by the speed encoder 22. The cleaning head is then stopped at the end of the engraved roller 3 at 144. The cleaning head is then retracted at 146 by providing compressed air through the inlet port 104 into the chamber 80. The whole process may be repeated starting at 130 for as many times as desired until the operator exits at 148.

(32) The wash mode is similar to the wipe mode except that the cylinder 38 is extended to its fully extended position at 160. Each cycle can be repeated as many times as desired at 162 until the operator exits at 164.

(33) In some embodiments, the engraved roller 3 is traversed one or more times in a dry wipe mode, followed by wet wipe mode, an optional wash mode, and concluded with one or more dry wipes.

(34) Turning to FIGS. 11 and 12, the cleaner 2 is supported below a table 200 in the actuator housing 230. The table has a top 202 and four legs 204. Table top 202 has two end openings 206, 207 and a central opening 208. A carriage plate 210 has vertical supports 216, 217 that extend through the end openings 206, 207 and hold a housing 230 that supports the cleaner 2. The openings 206, 207 allow the carriage plate 210 and vertical supports 216, 217 to move laterally within openings 206, 207. A motor 209 drives endless belt 212 to move the carriage plate 210 and the cleaner left and right as shown by arrow B of FIG. 1. Lateral guides 213, 214 hold the carriage plate 210 and the cleaner 2 in position perpendicular to the axes of the engraved roller 3 and the blanket roller 4.

(35) A stepper motor 222 moves a screw drive 224 up and down in the directions of arrow C of FIG. 1. The bottom of the screw drive is coupled to the housing 230. The cleaner 2 is fixed to a support on the endless belt 234. The cleaner 2 is driven back and forth across the faces of the rollers 3, 4 by a motor 232 connected to an endless belt 234 that is also supported by the housing 230. The conveyor belt 306 moves the objects 308 in the direction of arrow A so that the image of letter A on the surface of the of blanket (print) roller 4 contacts and is printed on the objects.

(36) Other embodiments of the cleaner may use fewer electronic controls and permit manual setting of travel piston pressure and liquid volumes. For example, where a user operates embodiments to apply a single mark, letter, or a combination of letters and numbers to a candy, tablet, lozenge or troche, the blanket (print) roller may be only 2-3 feet long and could be operated mostly manually with the operator setting minimal values such as the travel of the cleaner, the pressure of the backing plate and the volume of the cleaning fluid.

(37) Other embodiments of the cleaner may be used to clean small, three dimensional objects of virtually any shape including simply shaped items with opposite flat surfaces spaced from each other by a uniform thickness or other shapes including top and bottom surfaces of any polygon as well as top and bottoms with opposite curved surfaces to form a sphere, an ovoid or other multi-curved shapes. Still other embodiments may be used with general purpose offset printing presses to clean rollers that print on surfaces of thin or thick substrates, including and not limited to paper, cardboard, and sheets of plastic.

(38) In some embodiments, the pressure applied during dry cleaning the engraved roller is the same pressure applied while cleaning the blanket roller. In other embodiments, the pressure may be different, including more or less than the pressure applied to the blanket roller. In some embodiments, the pressure applied during the wet, wipe mode may be the same as the pressure applied during the dry cleaning mode, more pressure, or less pressure.

(39) While preferred embodiments of the invention have been shown and described, modifications and variations may be made thereto by those of ordinary skill in the art without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to be limitative of the invention as further described in the appended claims. Those skilled in the art understand that other and equivalent components and steps may be used to achieve substantially the same results in substantially the same way as described and claimed.