PHASE ADJUSTING APPARATUS FOR SHEET-FED PRINTING PRESS

Abstract: In a phase adjusting apparatus (10) for a sheet-fed printing press for adjusting a relative phase in a rotational direc­ tion between a paper sheet feeder and a printing apparatus which are coupled through a chain (7), a sprocket (18) is in internal contact with a tension run of the chain and is axially supported by a slide base (15). The slide base is supported to be movable in a direction substantially perpen­ dicular to an extension direction of the tension run of the chain. A slide base driving apparatus (27) is arranged on a press frame (4). A tension sprocket (22) which is biased in a tension direction of the chain by compression coil springs (24) is provided so as to be in contact with a slack run of the chain.

Description: Background of the Invention The present invention relates to a phase adjusting apparatus for adjusting a relative phase between a paper sheet feeder and a printing apparatus in accordance with a paper feed state for the printing press in a sheet-fed printing press. In a sheet-fed printing press, paper sheets stacked on a stack board are drawn by suction one by one by a sheet pick-up device, and are fed onto a feedboard through a feeder board. Thereafter, each sheet is gripped and conveyed by grippers of a swing gripper. The sheets are subjected to printing while being gripped and conveyed by grippers of a plate cylinder of the printing apparatus. In such a sheet-fed printing press, rotation of a motor is transmitted to a printing apparatus, and is then transmitted to the sheet pick-up device of the paper sheet feeder or a paper conveying tape provided on the feeder board through a chain or a line shaft. Known arrangement of this type (see e.g. US-A-1 578 329) comprises a frame and a sprocket which is in engagement with the chain from the inside toward a tension run thereof. If a rotational phase between the paper sheet feeder and the printing apparatus is set at a given value, when the tape is extended or is slid along a paper sheet, the sheet cannot be fed to the printing apparatus at a predetermined timing. Thus, grippers may fail to grip the sheet or may grip it unsatisfactorily, resulting in printing error or obstructions causing the printing press to be stopped. In order to prevent this, a phase adjusting apparatus cooperating with elongated holes and bolts is provided at any location in a driving system between the printing apparatus and the paper sheet feeder. If an abnormality is found upon observation of the gripping state of the grippers, the sheet feed timing of the paper sheet feeder is speeded up or delayed with respect to the printing apparatus. In the known apparatus no phase adjustment can be performed through the chain, the tension and slack runs thereof remaining uninfluenced. Thus the conventional apparatus cannot be operated during operation of a printing press, and adjustment must be performed after the printing press is stopped. Therefore, workability is degraded, and an operator cannot perform any adjustment while observing the gripping state of the grippers. Therefore, in many cases it is impossible to perform one single appropriate adjustment only, and readjustment must be repeated several times. Therefore, an idle time is prolonged, and the number of wasted paper sheets is increased. Another phase adjusting apparatus has been suggested which can be adjusted during the operation of the printing press and uses planetary gears in a driving system between the printing apparatus and the paper sheet feeder. However, this apparatus has a complicated structure, and a distance between the shafts of the gears must be changed. Therefore, the backlash of the gears is increased, thus unstabilizing a phase. Summary of the Invention It is a principal object of the present invention to provide a phase adjusting apparatus for a sheet-fed printing press which will improve the productivity reducing the amount of wasted paper. It is another object of the present invention to provide a phase adjusting apparatus for a sheet-fed printing press which allows easy and quick phase adjustment. In order to achieve the above objects, there is provided a phase adjusting apparatus for a sheet-fed printing press for adjusting a relative phase in a rotational direction between a paper sheet feeder and a printing apparatus which are coupled through a chain, the arrangement comprising a frame and a sprocket which is in contact with the chain from the inside towards a tension run of the chain, characterized by a slide member, mounted on the frame through rails, for supporting the sprocket through a short shaft such that the slide member is movable along the longitudinal direction corresponding to a direction perpendicular to an extension direction of the tension run of the chain, slide member driving means for moving the slide member in the longitudinal direction, and a tension sprocket supported on the slide member through a short shaft and in contact with the chain from the inside towards a slack run of the chain, the tension sprocket being biased by a spring member so that the chain is tensioned. Thus, a phase adjusting apparatus for a sheet-fed printing press is provided which is free from the influence of a backlash of the gears and can stabilize a phase and cope with the requirement for a wide range of a change in phase. Brief Description of the Drawings Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings, which by way of illustration schematically show preferred embodiments of the present invention and the principles thereof and what now are considered to be the best modes contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the scope of the appended claims. In the drawings Fig. 1 shows a side view of a chain driving apparatus to which the present invention is applied; Fig. 2 shows a partially cutaway sectional view taken along a line A-A of Fig. 1; and Fig. 3 shows a partially cutaway plan view when viewed from a direction B of Fig. 1. Description of the Preferred Embodiment An embodiment of the present invention will be described with reference to the accompanying drawing. In Figs. 1 to 3, a driving sprocket 3 is fitted axially, close to a frame 4, on a driving shaft 2 of a printing apparatus and serves as a driving section of a chain driving apparatus 1. A driven sprocket 6 is fitted axially, close to the frame 4 on a driving shaft 5 of a paper sheet feeder and serves as a driven section. A chain 7 is arranged to form a connection or loop between the driving sprocket 3 and the driven sprocket 5. When the driving sprocket 3 is rotated in a direction indicated by an arrow A, the driven sprocket 6 is rotated in a direction indicated by an arrow B, and the chain 7 travels in a direction indicated by an arrow C. Therefore, the lower side (Fig. 1) of the chain 7 corresponds to a tension run or side, and the upper side thereof corresponds to a slack run or side. Tension sprockets 8 and 9 supported by the frame 4 and fixed to shafts each are in contact, respectively, with the tension and slack run of the chain 7 near the driving sprocket 3. A phase adjusting apparatus generally denoted by reference numeral 10 is arranged between the tension sprockets 8 and 9 and the driven sprocket 6. More specifically, a guide rail 11 substantially perpendicular to a line connecting the centres of the shafts 2 and 5, and guide rails 12 and 13 divided in a longitudinal direction and arranged parallel to the rail guide 11 are fixed to the inner surface of the frame 4 by bolts 14. Reference numeral 15 denotes a strip slide base used as a slide member which is formed to be movable with respect to the tension and slack runs such that the upper and lower surfaces are slidable along flange portions of the guide rails 11, 12, and 13 and the inner surface of the frame 4. A short shaft 16 is fixed to the lower end portion of the slide base 15 by a stop 17. A sprocket 18 which is in internal engagement with the tension run of the chain 7 is fitted rotatably on the short shaft 16. A thin-walled portion 15a, having a thickness approximately half that of the slide base 15, is formed in the upper portion of the slide base 15. A rectangular slide block 19 is supported to be movable relative to the tension and slack runs such that its upper and lower surfaces are in slidable contact with the inner surface of the thin-walled portion 15a and the flange surfaces of the slide guides 11 and 12. A short shaft 20 is fixed at the central portion in the widthwise direction of the slide block 19 by a stop 21. A tension sprocket 22 which is in internal engagement with the slack run of the chain 7 is fitted rotatably on the short shaft 20. Furthermore, a pair of stepped spring holes 19a extend vertically through the slide block 19. Furthermore, spring holes 15b are formed in the slide base 15 so as to correspond to the spring holes 19a. Compression coil springs 24 are interposed between collars of spring shafts 23 inserted in the spring holes 19a and 15a and the bottom surfaces of the spring holes 15b, respectively. The compression coil springs 24 accumulate a biasing force in a direction for separating the slide block 19 from the slide base 15 by adjusting screws 25 threadably engaged in threaded portions of the spring holes 19a. More specifically, the tension sprocket 22 is biased on a direction for tensioning the slack run of the chain 7 by the compression coil springs 24. The biasing force can be adjusted by forward or backward movement of each adjusting screw 25. Reference numeral 26 denotes a stopper for the slide block 19, which is fixed to the upper end face of the slide base 15 by bolts; and 15c, a sliding grease groove between the slide base 15 and the frame 4. Reference numeral 27 generally denotes a driving apparatus for moving the slide base 15 to the slack or tension side. The driving apparatus 27 comprises a U-shaped bracket 28 fixed outside the frame 4 at a position corresponding to a divided portion between the guide rails 12 and 13. An operating shaft 30 carrying a knob 29 parallel to the frame 4 is supported pivotally on the bracket 28. A worm 31 is fitted axially on the operating shaft 30. A driving shaft 33 having a worm wheel 32 which is meshed with the worm 31 is fitted pivotally on the frame 4. A pinion 35 meshed with a rack 34 formed on the slide base 15 is fixed to the other end of the driving shaft 33. With this structure, when the operating shaft 30 is pivoted, the driving shaft 33 is pivoted via the meshing between the worm 31 and the worm wheel 32, and the sprocket 18 is moved to the slack or tension run together with the slide base 15 upon meshing between the pinion 35 and the rack 34. Then, a phase between the driving shaft 2 and the driven shaft 5 is adjusted in accordance with expansion/constriction of the tension side of the chain 7. Reference numeral 36 denotes a setting screw which is screwed in the screw hole of the bracket 28 to fix the pivotal movement of the operating shaft 30 at the adjusted position. The operation of the phase adjusting apparatus with the above structure will now be described. The driving shaft 2 is driven and rotated by a motor side, so that respective cylinders of the printing apparatus are rotated and grippers are opened/closed. The rotation of the driving shaft 2 is transmitted to the driven shaft 5 through the chain 7, and paper suction in the paper sheet feeder, paper conveyance by a conveying tape, and the like are performed. Tensile forces by the tension sprockets 8, 9 and 22, and the sprocket 18 act on the chain 7. For example, when the conveying tape and a paper sheet slip with regard to each other in the paper sheet feeder and a feed timing of a paper sheet to the printing apparatus thus is delayed, the set screw 36 is loosened, and then, the operator turns the operating shaft 30 while holding the knob 29 during the operation of a printing press. Then, the driving shaft 33 is pivoted through the worm 31 and the worm wheel 32, and the sprocket 19 is moved downward in Fig. 1 together with the slide base 15 through the pinion 35 and the rack 34. In this case, a force for moving the sprocket 18 by the driving apparatus 27 overcomes the biasing force of the compression coil springs 24. Therefore, although the total length of the chain 7 is kept unchanged, the length of the tension run of the chain 7 becomes larger than that of the slack run. More specifically, assuming the driving shaft 2 is fixed in position, the driven shaft 5 is slightly pivoted in the direction indicated by arrow B, and the phase of the driven shaft 5 is advanced with respect to the driving shaft 2. Therefore, the phase of the paper sheet feeder is advanced with respect to the printing apparatus, and a paper feed timing for the printing apparatus which has been delayed due to paper slippage can be speeded up or advanced, thus resuming the operation at a normal timing. It should be noted that the tension sprockets 8 and 9 are fixed to the shafts, and are simply rotated at identical positions. After phase adjustment, the set screw 36 is tightened so as not to change a phase. The operator can perform the above operation during the operation of the printing press while observing the paper feed state for the printing apparatus. Note that if the chain 7 is elongated due to long-term use to result in an increase in total length thereof, and a phase of the driven shaft 5 is delayed with respect to the driving shaft 2, the normal phase can be obtained by the same operation as described above. In this embodiment, the tension sprocket 22 is arranged along a line substantially perpendicular to the chain 7 while it is biased against the sprocket 18 by the compression coil springs 24. For example, the tension spring 22 may be arranged independently to be separated from the sprocket 18 and to be located at, for example, a position of the tension sprocket 8. As can be understood from the above description, according to the present invention, a slide member with a sprocket which is in internal contact with a tension run or side of a chain for coupling a paper sheet feeder and a printing apparatus in a sheet-fed printing press, is provided. The slide member is supported to be movable in a direction substantially perpendicular to an extension direction of the tension side of the chain. Operating means are provided to a press frame, and a chain sprocket is arranged which is biased in a tension direction of the chain by a spring member so as to be in contact with the slack run or side of the chain. Thus, when a phase between the paper sheet feeder and the printing appratus is changed due to slippage between a sheet and a conveying tape or elongation of the chain, it can be adjusted by operating the operating means during the operation. Therefore, productivity can be improved, and the number of wasted paper sheets can be reduced. In addition, since an adjustment can be performed while observing a sheet feed state, it can be performed quickly and appropriately. Since, in contrast to conventional apparatus, no planetary gears are used, a phase is free from back-rush and is stabilized, and an amount of adjustment can be increased, thus coping with a wide range of change in phase.

Claims: A phase adjusting apparatus (10) for a sheet-fed printing press for adjusting a relative phase in a rotational direction between a paper sheet feeder and a printing apparatus which are coupled through a chain (7), the arrangement comprising a frame (4); and a sprocket (18) which is in engagement with said chain from the inside toward a tension run of said chain; characterized by a slide member (15), mounted on said frame through rails (11, 12, 13), for supporting said sprocket through a short shaft (16) such that said slide member is movable along the longitudinal direction corresponding to a direction essentially perpendicular to an extension direction of the tension run of said chain; slide member driving means (27) for moving said slide member in the longitudinal direction; and a tension sprocket (22) supported on said slide member through a short shaft (20) and in engagement with said chain from the inside toward a slack run of said chain, said tension sprocket being biased by a spring member (24) so that the chain is tensioned. An apparatus as claimed in claim 1, characterized in that said slide member (15) comprises a thin-walled portion (15a) at an upper portion thereof, a slide block (19) having screw stepped holes (19a), spring pins (23) fitted in said stepped screw holes, and adjusting screws (25) threadably engaged with said stepped holes and engaging with upper ends of said spring pins, said spring pins being surrounded by said spring members. An apparatus as claimed in claim 1 or 2, characterized in that said slide member driving means (27) comprises an operation shaft (30) with a knob (29), a worm (31) mounted on said operating shaft, a worm wheel (32) meshed with said worm, a driving shaft (33) one end of which is coupled to said worm wheel, a pinion (35) coupled to the other end of said drive shaft, a rack (34) formed on said slide member and meshed with said pinion, so that said slide member is moved through said operation shaft, said worm, said worm wheel, said drive shaft, said pinion, and said rack along the longitudinal direction upon roation of said knob. An apparatus according to claim 3, characterized in that a longitudinal direction of said slide member (15) is substantially perpendicular to a line connecting the axes of the driving and the driven sprockets (3 and 6).

Inventors: FURUKAWA, SHIGEO SEKIYADO WORKS KOMORI PRINTING
Applicants: KOMORI CORPORATION
Application year: 1987
Main classification: B41F21
IPC codes: F16H35, F16H7, B65H5, B41F13