Inking apparatus for printing press

Abstract: In an inking apparatus for a printing press, a rotary lever (36) is rotated by adjusting means (32) disposed between a roller arm (20) and the rotary lever (36) around an axis parallel to a swing shaft of the roller arm to move a cam follower (34) mounted to the rotary lever, and a cam (60) mounted coaxially with a plate cylinder (4) is rotated by cam driving means to select pressing state and unpressing state of the ink form roller through the cam follower, thereby preventing the nip pressure from being varied by skewing adjustment of the plate cylinder.

Description: Background of the Invention This invention relates to an inking apparatus for a printing press, which can easily control the contact pressure of ink form rollers on the surface of a printing plate mounted on a plate cylinder, thus eliminating the need for readjustment of the contact pressure after skewing adjustment of the plate cylinder. Heretofore, an inking apparatus mounted on printing presses such as a rotary printing press is provided with an ink fountain and a plurality of rollers. Ink charged in the ink fountain is picked up by rotation of ink fountain rollers and is applied as a film of ink onto the surface of the forming rollers. Furthermore, the film of ink is kneaded and spread in all directions while being transferred between the rollers, and is then supplied by the ink form rollers to the plate surface on the plate cylinder. In the above inking apparatus, the contact pressure between the ink form rollers and the plate surface, that is, a so-called nip pressure, has tended to vary with changes in diameter of the ink form rollers due to thermal expansion, abrasion, and finishing of the plate cylinder. Since the nip pressure largely affects the quality of printed matter, the inking apparatus is provided with a nip pressure adjusting device to adjust the nip pressure in the preparation stage for printing or during printing. As such a nip pressure adjusting device, there has been known, for example, one which is disclosed in Japanese Patent Publication Laid-open No.58-175663/1983. In this device, ink form rollers are individually supported by swingable roller arms, and the roller arms are urged by spring members with adjustable urging force so that the ink form rollers are pressed against the plate surface. Furthermore, when the printing plate is mounted to the plate cylinder of the printing press, the printing plate may be slightly skewed with respect to the plate cylinder, and the individual ends of the printing plate may become shifting peripherally from each other in the reverse directions, resulting in a mis-registration between the right and left sides. In this case, eccentric bearings rotatably supporting the rotary shaft of the plate cylinder on the frames of the printing press are turned to correct the error of registration, that is, so-called skewing adjustment is made. However, with the above nip pressure adjusting device, skewing adjustment of the plate cylinder varies the already adjusted nip pressure. Then, the nip pressure must be adjusted again, requiring additional time and labor. EP-A-0 105 476 discloses a rotary printing press having the features of the preamble of claim 1. Object of the Invention With a view to obviate the above prior art defects of inking apparatus, it is a primary object of the present invention to provide an inking apparatus for a printing press, with a mechanism which is simple in structure, easy to assemble, and low in production cost, which prevents the nip pressure from being varied due to skewing adjustment of the plate cylinder, thereby eliminating the need for readjustment of the nip pressure after skewing adjustment of the plate cylinder. Summary of the Invention In accordance with the present, there is provided an inking apparatus as claimed in claim 1. Brief Description of the Drawings Fig.1 is a schematic cross sectional view showing part of the inking apparatus for a printing press of an embodiment according to the present invention. Fig.2 is a schematic plan view of the inking apparatus for a printing press according to the present invention. Fig.3 is a schematic enlarged cross sectional view showing part A of Fig.2. Fig.4 is a schematic view taken along line IV-IV of Fig.3. Fig.5 is a schematic view showing part of the inking apparatus for a printing press of an embodiment according to the present invention. Detailed Description of the Preferred Embodiments An embodiment of the inking apparatus for a printing press according to the present invention is shown in Figs.1 to 5, and the present invention will be described with reference to these drawings. As shown in Fig.1, a pair of bearing holes 1a formed in right and left frames 1 are inserted rotatably with first eccentric rings 2, with center F₁ of inner holes 2b eccentrically shifted by t with respect to shaft center F of the bearing holes 1a. The inner holes 2b of the pair of first eccentric rings 2 are inserted with second eccentric rings 3, rotatable with respect to the first eccentric rings 2, with center F₂ of inner holes 3b eccentrically shifted by t₁. A pair of rotary shafts 4a of a plate cylinder 4, mounted with a printing plate on its peripheral surface and contacting a blanket cylinder (not shown), are rotatably supported in the inner holes 3b of the pair of second eccentric rings 3, through a pair of rolling-contact bearings 5. The rolling-contact bearings 5 are held with retainer plates 1b mounted to the frames 1, thereby being prevented from axially shifting. Thus, the shaft center of the plate cylinder 4 is coaxial with the center F₂ of the inner holes 3b of the second eccentric rings 3, and is rotatable about F₂ with respect to the frames 1. Therefore, when the right and left first eccentric rings 2 are turned by a same angular phase, the plate cylinder 4 makes an eccentric movement about the shaft center F, and thus the contact pressure between the plate cylinder 4 and the blanket cylinder (not shown) is adjusted. In this state, one of the second eccentric rings 3 of the right and left frames 1 is rotated so that the contact pressure to the blanket cylinder does not change, the outer periphery of the plate cylinder 4 at the rotated side is finely moved by an eccentric movement about F₁. By the fine movement, skewing adjustment of the plate cylinder 4 is made to correct mis-registration of the printing plate. As shown in Figs.1 and 2, above the plate cylinder 4 of the above-described arrangement, a pair of vibrating rollers 15, positioned at the end of the inking apparatus, are rotatably supported through bearings 17. Each of the vibrating rollers 15 is provided with a vibration mechanism (not shown), and the vibrating rollers 15 are rotated by a driving source (not shown) to make a reciprocal movement with a predetermined period in a direction parallel to the axial line of the vibrating rollers 15. Furthermore, each of the vibrating rollers 15 rotatably contacts a pair of ink form rollers 18. Specifically, both end shafts 15a of the vibrating rollers 15 are mounted rotatably with pairs of roller arms 20 adjacent to each other, and an ink form roller 18 contacting against the vibrating roller 15 is rotatably supported at one of front portions 20a of the roller arm 20. As shown in Fig.5, the other front portion 20b of the roller arm 20 is rotatably linked with one end side of a first spring holder member 51 and a guide bar 52. At the other end of the guide bar 52, a second spring holder member 53 is slidably engaged with the guide bar 52. The second spring holder member 53 is rotatably mounted to the frame 1, and the portion of the guide bar 52 between the second spring holder member 53 and the first spring holder 51 is wound around with a compression coil spring 28 so as to extend the section between the spring holder members 1 and 53. Therefore, a rotating force about the end shaft 15a is applied to the roller arm 20 by the compression coil spring 28 pressing downward while sliding the second spring holder member 53 and the guide bar 52. Thus, the ink form roller 18 is pressed towards the plate cylinder 4 side by a rotating force generated by a pressure member 30 comprising the spring holder members 51 and 53, the guide bar 52, and the compression coil spring 28. Furthermore, as shown in Fig.3, the ink form roller 18 is supported rotatably about shaft center C on a holder 35 through a bearing 35a. The holder 35 is rotatably engaged with a rotary shaft 36a connected with a rotary lever 36 through a key 36b, and shaft center C₁ of the rotary shaft 36a has an eccentricity h₁ with respect to the shaft center C. Referring to Fig.3, at the lower end side of the rotary shaft 36a is mounted a cam follower 34, of which the outer peripheral surface rotatably contacts against a cam 60, and shaft center C₂ of the cam follower 34 has an eccentricity h₂ with respect to the shaft center C₁. As shown in Fig.1 and Fig.2, the cam 60 is rotatable relative to the plate cylinder 4, and is rotatably mounted to a bearing holder 7 so that it is concentric with shaft center F₂ of the plate cylinder 4. The holder 35, as shown in Fig.3, is also engagingly supported on the roller arm 20. At the front end of the rotary lever 36, which is rotatable with respect to the holder 35, is engaged an adjusting pin 37 with a female thread formed inside. At the roller arm 20 side, an adjustment screw 32, which is an adjusting means threaded with the adjusting pin 37, is engaged through a pin 31 engaged with the roller arm 20. Furthermore, the roller arm 20 incorporates a loosening prevention mechanism for the adjusting screw 32 comprising a ball 31a, and a spring 31b pressing against a knurled knob 32a of the adjusting screw 32. Therefore, when the adjusting screw 32 is rotated against the force of the spring 31b, the adjusting screw 32 pushes the adjusting pin 37 threaded with the adjusting screw 32 out to the upper left side in Figs.4 and 5, or, reverts it back to the right side. This causes the rotary lever 36 and the rotary shaft 35a to rotate relative to the holder 35. As a result, the shaft center C₂ of the cam follower 34 mounted to the rotary shaft 35a is moved along an arc about the shaft center C₁ of the holder 35 which supports the rotary shaft 36a, and the position of the shaft center C₂ varies relative to the shaft center C of the ink form roller 18. Thus, through the movement of the cam follower 34, the position of the ink form roller 18 can be varied relative to the plate cylinder 4 in the radial direction, thereby adjusting the nip pressure. Referring to Fig.2, the rod end 42 side of an air cylinder 41 as cam driving means is rotatably mounted to the frame 1 (not shown) through a pin 43. A cylinder rod 44 of the air cylinder 41 is linked to a lever 45, of which the rear end is swingably supported on the frame 1 through a pin 46, through engagement with a pin 47. The lever 45 is rotatably mounted with a rod 49 through a connecting pin 48 which engages with the lever 45 and the rod 49. Furthermore, the cam 60 is connected with the front end of the rod extended from the lever 45, so that the cam is rotatable through a pin 50. Therefore, when the cylinder rod 44 of the air cylinder 41 extends, the cam 60 is rotated clockwise through swinging of the lever 45 and sliding of the rod 49. As a result, the cam follower 34 contacting against the cam 60 becomes movable in the radial direction of the plate cylinder 4, releasing the ink form roller 18 from the plate cylinder 4. Thus, during printing, the cam 60 is fixed in the position shown in Fig.2 to press the ink form roller 18 against the plate cylinder 4. When not printing, the cam 60 is rotated clockwise to push up the cam follower 34 in the radial direction, thereby releasing the ink form roller 18 from the plate cylinder 4. With the above-described arrangement, even when the skewing adjustment is made after the nip pressure is adjusted by the adjusting screw 32, the cam follower 34 follows the movement of the cam 60 due to the pressing force of the pressure member 30, thereby eliminating the need for nip pressure readjustment. In this embodiment, the pressing force is generated by the compression coil spring 28 of the pressure member 30. However, the present invention is not limited to this, but the pressing force can alternatively generated using other conventional means known in the art, such as an air cylinder. Furthermore, the rotary lever can alternatively be pressed towards the plate cylinder 4 side by the front end of an adjusting screw protruded by rotation of the adjusting screw, rather than the adjusting screw 37 directly engaged with the adjusting screw 32 as used in this embodiment.

Claims: An inking apparatus for a printing press of the type including roller arms (20) having rear ends swingably supported on frames (1) supporting vibrating rollers (15), ink form rollers (18) having a center C and with both ends rotatably supported on front ends of said roller arms (20), and pressure members (30) exerting a rotating force on said roller arms (20) to press said ink form rollers (18) against a printing plate on the surface of a plate cylinder (4); further including a rotary lever (36) rotatably mounted to a shaft parallel to a swing shaft of said roller arms (20), a cam (60) mounted coaxially with said plate cylinder (4) for selecting pressing state and unpressing state of said ink form rollers (18) against said plate cylinder (4) through a cam follower (34) mounted to said rotary lever (36), cam driving means (41, 44, 49 etc.) for driving said cam (60), and adjusting means disposed between said roller arms (20) and said rotary lever (36) for varying pressing force of said ink form rollers (18) to said plate cylinder (4) by varying relative positions between said ink form rollers (18) and said cam follower (34) through rotation of said rotary lever (36) relative to said roller arms (20); said rotary lever (36) being rotatably mounted to said roller arms (20) through a holder (35) rotatably supporting said ink form rollers (18) and engagingly supported on said roller arms (20), said adjusting means (32) having a knob (32a) at its rear end, the rear end side of said adjusting means (32) being rotatably mounted to said roller arm (20) through a pin (31) engaged with said roller arm (20), and a front end of said adjusting means (32) being threaded with a rotary lever (36) rotatably mounted to said roller arm (20), whereby said front end acting as an adjusting screw for rotating said rotary lever (36) relative to said roller arm (20) by turning said adjusting screw; characterized in that the portion of said holder (35) supported on said roller arms (20) has a cylindrical form, a rotary shaft (36a) is rotatably supported inside the cylindrical portion, the center (C₁) of said rotary shaft (36a) is eccentric to the center (C) of said ink form roller (18), said rotary lever (36) is mounted to one end of said rotary shaft (36a), said cam follower (34) is mounted directly to the other side of said rotary shaft (36a) with the center (C₂) thereof eccentric to the center (C₁) of said rotary shaft (36a), whereby when rotating said adjusting means (32), said rotary shaft (36a) rotates to change relative position of said cam follower (34) to said ink form roller (18) to adjust a contact pressure between said plate cylinder (4) and said ink form roller (18). The inking apparatus of Claim 1 wherein said cam driving means comprises an air cylinder (41) having a rear end rotatably supported on said frame (1), a lever (45) swingably supported on said frame (1) and connected to a cylinder rod (49) extendibly disposed at a front end side of said air cylinder (41), and a rod (49) having a front end connected to said cam (60) for transmitting extension and contraction of said cylinder rod (44) to said cam (60). The inking apparatus of Claim 1 wherein said adjusting means is mounted to said roller arm (20) with its rear end threaded with said roller arm (20), and a front end side of said adjusting means contacts against said rotary lever (36), whereby said front end acts as an adjusting screw (32) having a protrusion amount of said front end adjustable by turning said adjusting screw (32). The inking apparatus of Claim 1 wherein said knob (32a) at the rear end of said adjusting screw (32) is knurled and is only rotatable when adjusting the contact pressure of said ink form roller (18) to said printing plate (4) by way of loosening prevention mechanism having a ball (31a) incorporated in the position of said roller arm (20) opposing the knurled rear end of said knob (32a) and a spring (31b) incorporated in said roller arm (20) for pressing said ball (31a).

Inventors: MIYAMOTO TOSHIO, SUGIYAMA HIROYUKI, MIYAMOTO, TOSHIO, SUGIYAMA, HIROYUKI, MIYAMOTO, TOSHIO, C/O KOMORI CORPORATION, SUGIYAMA, HIROYUKI, C/O KOMORI CORPORATION
Applicants: KOMORI PRINTING MACH, KOMORI CORPORATION
Application year: 1991
Main classification: B41F31
IPC codes: B41F31