Safety device for ink forming rollers

Abstract: In a safety device (4) for ink forming rollers, (3) each of the rollers is supported on a frame (1) through a moving shaft (5) movable in an axial direction to remove the ink forming roller, a safety pin (19) is provided which is urged and supported on the frame, the moving shaft is formed with a recess (18) for engagement with the safety pin and a guide surface (23) for guiding the safety pin to the recess against the urging force of the safety pin. When the ink forming roller is mounted, the safety pin automatically engages to interrupt movement of the moving shaft, thereby preventing the ink forming roller from falling down due to an external cause such as a power stoppage or a misoperation, and the safety device being prevented from careless locking failure, thereby improving the safety of the printing machine.

Description: FIELD OF THE INVENTION This invention relates to a safety device for ink forming rollers which contact the outer peripheral portion of a plate cylinder to apply ink thereto. BACKGROUND OF THE INVENTION A printing machine is equipped with a sheet feeder, a printing unit, a paper discharge device, and an ink unit, and this printing unit is in contact with a blanket cylinder, an impression cylinder, a transfer cylinder, a plate cylinder and the like, and supported on a shaft. The inking unit is provided with a group of rollers including ink forming rollers corresponding to the plate cylinder, and ink fountains. A plurality of the ink forming rollers contact a single plate cylinder, individually applying ink of different colors to the plate cylinder. The ink forming rollers are provided with patterns according to the printed matter, and, therefore must be replaced when the printed matter is changed or the roller surface is worn out. Prior art ink forming rollers are rotatably supported on the frames, and one end of each cylinder is supported by a moving shaft which is supported on the frames and movable in the axial direction. The moving shaft is mounted with a hydraulic cylinder to which a hydraulic pump is connected. The ink forming rollers are replaced by operating the hydraulic cylinder to move the moving shaft, allowing removal of the ink forming rollers from the frames. Such ink forming rollers are removed by moving the moving shaft in the axial direction by means of the hydraulic cylinder. Therefore the positional holding of the ink forming rollers depends on the hydraulic cylinder. If the hydraulic pump stops due to a power failure or the like, the pressure of the hydraulic cylinder decreases. As a result, the retaining force on the moving shaft, and, in turn, on the ink forming rollers is decreased, and the ink forming rollers can fall down from the frames due to their weight. Furthermore, since the operation of the hydraulic cylinder is controlled by the pressing of a button by an operator, if the operator presses the button by mistake during operation of the printing machine, there may occur defective printing or damage to the ink forming rollers or even damage to the printing machine. To prevent this, a safety pin has been provided in order to prevent the ink forming rollers from falling down even when the hydraulic pump stops or due to the operator's misoperation. Therefore, when the ink forming rollers are mounted, this safety pin is moved by the operator to lock the ink forming rollers, thereby retaining the ink forming rollers in position. When the safety pin is moved to an unlock position to unlock the ink forming rollers, the rollers can then be replaced. Such a safety pin is provided to prevent the ink forming rollers from falling down due to a stoppage of the hydraulic pump or the operator's misoperation. However, since the safety pin is operated manually by the operator, the operator may fail to move the pin to the lock position when the ink forming rollers are mounted. In such a case, the ink forming rollers cannot be prevented from falling down due to a stoppage of the hydraulic pump or the operator's misoperation, and the ink forming rollers or even the printing machine may be damaged. SUMMARY OF THE INVENTION With a view to eliminate such prior art problems, it is a primary object of the present invention to provide a safety device for ink forming rollers, which positively prevents the ink forming rollers from falling down for improving the safety of the printing machine. In accordance with the present invention, there is provided a safety device for ink forming rollers which are rotatably disposed in contact with the outer peripheral surface of a plate cylinder, one end being supported on a frame through a moving shaft, and detachable from the frame by moving the moving shaft in an axial direction, comprising a safety pin provided on the frame and urged in a direction to engage into the moving shaft, the moving shaft being formed with a recess for engagement with the safety pin and a guide surface for guiding the safety pin to the recess against the urging force when mounting the ink forming rollers. When the ink forming rollers are mounted, the guide surface of the moving shaft moves the safety pin against the urging force to automatically guide the safety pin to the recess in the moving shaft. Therefore, the safety pin prevents the moving shaft from moving in the axial direction due to an external cause such as a power stoppage or the like, thereby preventing the ink forming rollers from falling down. Furthermore, when the ink forming rollers are replaced, the safety pin can be removed from the moving shaft against the urging force, making the moving shaft movable in the axial direction and the ink forming rollers replaceable. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a schematic cross sectional view showing an embodiment of the safety device for ink forming rollers according to the present invention. Fig.2 is a schematic cross sectional view of a printing machine. Fig.3 is a schematic cross sectional view of an ink forming roller. DETAILED DESCRIPTION OF THE INVENTION An embodiment according to the present invention will now be described in detail with reference to the drawings. As shown in Fig. 2, a plurality of ink forming rollers 3 are supported on shafts in contact with a plate cylinder 2 which is supported on a frame 1 of a printing machine. Each of the ink forming rollers 3 is provided with a safety device 4. Referring to Fig. 3, one end of the ink forming roller 3 is rotatably supported on one frame by a supporting shaft (not shown) and the other end supported on the frame 1 by a moving shaft 5. Specifically, a cylindrical connecting member 6 is fixedly mounted to the other end of the ink forming roller 3, and a tapered portion 7 is formed at the end of inner periphery of the connecting member 6. A cylindrical member 8 engages with the outer periphery of the moving shaft 5 and integrally mounted by a disk 9 at the end. The cylindrical member 8 is supported by a bearing 10 mounted to the frame 1. An axial groove 11 is formed on the outer periphery of the cylindrical member 8, and a key 12 is fixed to the inner periphery of the bearing 10. The key 12 engages into with the groove 11 to support the cylindrical member 8, in turn the moving shaft 5, so as to be movable in the axial direction relative to the bearing 10 (frame 1) but unrotatable in the circumferential direction. At one end of the ink forming roller 3 side of the moving shaft 5 is integrally formed an engaging portion 13 which engages into with the tapered portion 7 of the connecting member 6. At the frame 1 side is provided a hydraulic cylinder 14, and the front end of a connecting rod 15 of the hydraulic cylinder 14 is connected to the disk 9 connecting the moving shaft 5 and the cylindrical member 8. The hydraulic cylinder 14 is also connected with a hydraulic pump (not shown) to supply hydraulic pressure. Therefore, the hydraulic cylinder 14 can be actuated to move the moving shaft 5 through the connecting rod 15, and the moving shaft can be moved either to an ink forming roller 3 supporting position, indicated by solid lines in Fig.3 where the engaging portion 13 engages with the tapered portion 7, or to an ink forming roller 3 replacement position, indicated by double broken lined in Fig. 3, where the engaging portion 13 is separated from the tapered portion 7. The ink forming roller 3 is provided with the safety device 4 to prevent the ink forming roller 3 from falling down. As shown in Fig.1, a bracket 16 is mounted to the outer periphery of one end of the bearing 10, and a through hole 17 is formed penetrating through the bracket 18 and the bearing 10. A recess 18 is formed at the outer periphery of the cylindrical member 8, at a position corresponding to the through hole 17. A safety pin 19 is slidably supported in the through hole 17, and urged by a spring 20 in a direction of the front end to engage with the recess 18 of the cylindrical member 8. The rear end of an operation lever 21 is rotatably supported on the bracket 16, and to the front end of the operation lever 21 is mounted a stopper lever 22. Furthermore, in the middle of the operation lever 21 is slidably connected the front end of the safety pin 19 by a slot. Therefore, by turning the operation lever 21 in the direction of the arrow in Fig.1, the safety pin 19 can be moved in the arrow direction to pull out the front end from the recess 18 of the cylindrical member 8, and the stopper lever 22 is turned so as its free end to contact against the outer periphery of the cylindrical member 8, as indicated by two-dot broken lines in the Figure, where it is held. At one end of the cylindrical member 8 is formed an inclined surface 23 as a surface to guide the safety pin 19 to the recess 18 when the ink forming roller 3 is mounted. Therefore, when the ink forming roller 3 is mounted, by moving the cylindrical member 8 with the moving shaft 5, the protruding safety pin 19 is pushed by the inclined surface 23 to move upward in Fig.1 against the urging force of the spring 20. Further movement of the cylindrical member 8 causes the safety pin 19 to engage with the recess 18. When the ink forming roller 3 is used, as shown in Fig.1 and Fig. 3, the safety pin 19 is urged by the spring 20 to engage with the recess 18 of the cylindrical member 8, the moving shaft 5 is interrupted in moving in the axial direction, and the ink forming roller 3 is locked in a predetermined operating position where the engaging portion 13 engages into with the tapered portion 7. In this case, even when the hydraulic pump to hold the hydraulic cylinder 14 in position stops operating due to an external cause such as a power stoppage or the like, the moving shaft 5 is interrupted by the safety pin 19 in moving in the axial direction, and the ink forming roller 3 will never fall down. When the ink forming roller 3 is replaced, first the operation lever 22 is turned to pull out the safety pin 19 from the moving shaft 5, making the moving shaft 5 movable in the axial direction. Then, the hydraulic cylinder 14 is operated to release the engaging portion 13 of the moving shaft 5 from the tapered portion 7, allowing removal of the ink forming roller 3 for replacement. At this moment, in the roller replacement position, since the cylindrical member 8 is moved to the inside of the bearing 10, the operation lever 22 has no supporting surface, and the safety pin 19 tends to be locked by the spring 20. To mount another ink forming roller 3, that ink forming roller 3 is set on the frame, and the hydraulic cylinder 14 is operated to cause the engaging portion 13 of the moving shaft 5 to engage into with the tapered portion 7. At this moment, since one end of the cylindrical member 8 is formed into the inclined surface 23, the safety pin 19 is raised by the inclined surface 23, and, when the cylindrical member 8 comes in the vicinity of a roller supporting position, the safety pin 19 engages into with the recess 18, where it is locked. Furthermore, when the safety pin 19 engages into with the recess 18, the operation lever 22 contacts the cylindrical member 8, however, since the spring 20 forcibly push down the safety pin 19, the operation lever 22 becomes the state indicated by solid lines in Fig.1 by the spring force, disturbance is prevented. Thus, the safety device 4 having the safety pin 19 is provided in addition to the hydraulic cylinder 14 to hold the ink forming roller 3, thereby preventing the ink forming roller 3 from falling down due to an external cause such as a power stoppage or the like. Furthermore, since the safety pin 19 is always urged by the spring 20 in the engaging direction, when the moving shaft 5 is moved to mount the ink forming roller 3, the safety pin 19 positively engages with the recess 18 to lock the ink forming roller. As described above in detail with reference to the embodiment, in the safety device for ink forming rollers according to the present invention, the ink forming roller is supported on the frame through the moving shaft, which is movable in the axial direction to allow removal of the ink forming roller, and the frame is provided with the safety pin which is urged. The moving shaft is formed with the recess, which engages with the safety pin, and the guide surface, which guide the safety pin to the recess against the urging force when the ink forming roller is mounted. Therefore, when the ink forming roller is mounted, the safety pin automatically engages into with the recess to interrupt movement of the moving shaft, making the moving shaft unmovable even when the holding condition of the ink forming roller is released due to an external cause such as a power stoppage or a misoperation of the operator, thereby preventing the ink forming roller from falling down. Furthermore, the safety device is prevented from careless locking failure, thereby improving the safety of the printing machine.

Claims: A safety device for ink forming rollers each rotatably disposed in contact with the outer peripheral surface of a plate cylinder, one end of said ink forming rollers being supported on a frame through a moving shaft, and detachable from said frame by moving said moving shaft in an axial direction, comprising a safety pin provided on said frame and urged in a direction to engage with said moving shaft, said moving shaft being formed with a recess for engagement with said safety pin and a guide surface for guiding said safety pin to said recess against the urging force when mounting said ink forming rollers. The safety device for ink forming rollers of Claim 1 wherein said safety pin is movable in a direction perpendicular to an axial direction of said moving shaft. The safety device for ink forming rollers of Claim 1 wherein said recess is formed on the outer peripheral surface of said moving shaft, and said guide surface is formed at one end in an axial direction of said moving shaft and is an inclined surface continuing to the outer peripheral surface of said moving shaft. The safety device for ink forming rollers of Claim 1 wherein said safety pin is connected with an operation lever to pull out said safety pin from said recess, and said operation lever is connected with a stopper lever to hold said operation lever in an operating condition. The safety device for ink forming rollers of Claim 4 wherein a supporting surface to interrupt movement of said stopper lever is formed on the outer peripheral surface of said moving shaft.

Inventors: UMETSU ISAO C O KOMORI CORP SE, UMETSU, ISAO, C/O KOMORI CORP., SEKIYADO PLANT
Applicants: KOMORI PRINTING MACH, KOMORI CORPORATION
Application year: 1991
Main classification: B41F31
IPC codes: B41F33, B41F31