Printing machine provided with plate cylinder driving device

Abstract

Plate cylinder driving devices of a printing machine are provided with a drive shaft driving the plate cylinder, a drive helical gear fixed to the drive shaft, and an anti-backlash helical gear rotatably connected to the drive shaft and is biased by at least a spring towards a direction for preventing backlash. Both the drive helical gear and the anti-backlash helical gear are engaged with the main gear, and a plate provided with plural holes accommodating rollers is provided between the drive helical gear and the anti-backlash helical gear. Friction between the anti-backlash gear and the drive gear is reduced by a simple mechanism in the plate cylinder driving devices in a printing machine.

Claims

1. A printing machine comprising a main gear and plate cylinder driving devices driving individual plate cylinders wherein: each of said plate cylinder driving devices is provided with a drive shaft driving a plate cylinder, a drive helical gear fixed to the drive shaft, and an anti-backlash helical gear which is rotatably connected to the drive shaft and is biased by at least a spring towards a direction for preventing backlash; the drive helical gear and the anti-backlash helical gear are both engaged with the main gear; and a plate provided with plural holes in which rollers are accommodated is provided between the drive helical gear and the anti-backlash helical gear.

2. The printing machine provided with plate cylinder driving devices according to claim 1, wherein said rollers have a column shape, circular in a radial section thereof, and have axial directions perpendicular to the drive shaft.

3. The printing machine provided with plate cylinder driving devices according to claim 1, wherein said plate is made of synthetic resin.

4. The printing machine provided with plate cylinder driving devices according to claim 1, wherein contact members are fixed to both the drive helical gear and the anti-backlash helical gear respectively and are in contact with the rollers, at contact areas with the rollers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 A partial vertical sectional view of a printing machine according to an embodiment

(2) FIG. 2 A front view of the drive helical gear and the plate according to the embodiment

(3) FIG. 3 A partial sectional view of the plate and the helical gears

(4) FIG. 4 A front view of the anti-backlash helical gear

DESCRIPTION OF THE INVENTION

(5) The best embodiment for carrying out the invention will be described in the following embodiment.

(6) FIGS. 1 to 4 indicate a printing machine according to the embodiment. As shown in FIG. 1, the main gear 2 of the printing machine is associated with plate cylinder driving devices 4 for each color component. Each plate cylinder driving device 4 is equipped with a drive helical gear 6, an anti-backlash helical gear 8, a drive shaft 10, and so on, and drives the plate cylinder unshown by the drive shaft 10. In addition, the helical teeth 3 of the main gear 2 are associated with the helical teeth 7 and 9 of the gears 6 and 8 respectively. Further, the gears 2, 6, 8 are cylindrical gears according to the embodiment; however, they may be bevel gears or hypoid gears.

(7) To the drive shaft 10, a coupling member 12 is joined for example by an unshown key and the drive helical gear 6 is coupled with the coupling member 12 by stud bolts 26. The drive helical gear 6 is provided with holes 24 threaded partly and the threaded holes 24 are engaged with the stud bolts 26. The stud bolts 26 penetrates through holes 25 in the anti-backlash gear 8, and the anti-backlash gear 8 is biased towards the drive gear 6 by nuts 27 and coil springs 28 in order to keep the gears 6, 8 in parallel. A gap 22 is provided between the coupling member 12 and the gear 8 in order to reduce the friction between them. This construction allows the gear 8 to rotate within the clearance between the through holes 25 and the stud bolts 26 relative to the gear 6. The connection mechanism of the gears 6, 8 to the coupling member 12 is arbitrary and is not limited to the stud bolts 26 shown in figures or the like.

(8) At one end of the coupling member 12, a holder 14 is fixed by bolts 29. The holder 14 is provided with plural arms 15, and the arms 15 hold one ends of tensile springs 30 respectively. The other ends of the tensile springs 30 are connected to bolts 32 or other connection members so as to be connected with the gear 8. In this way, the anti-backlash gear 8 is biased relative to the drive gear 6 towards the positive rotational direction of the gears 6, 8. The biasing springs are not limited to the shown tensile springs 30 but may be compression springs or flat springs.

(9) Between the gears 6, 8, a heat-resistant and self-lubricating plate 16 made of a synthetic resin is provided. The plate 16 consists of poly-ether-ether-ketone, poly-phenylene-sulfide, polyimide, or the like and is provided with plural holes: rollers 18 accommodated within the holes are in contact with the gears 6, 8. The rollers 18 are made of a hard steel or the like, have a column shape which is circular in a radial section, and the axes of them are perpendicular to the drive shaft 10. To the gears 6, 8, are joined and fixed plural contact members 20, 21 respectively, made of hard steels or the like, at areas in contact with the rollers 18.

(10) FIGS. 2 and 3 indicate the alignment of the plate 16 to the gears 6 and 8. The gears 6 and 8 are provided with ring-like recesses 40 and 41 respectively, and, within the recesses 40 and 41, the plate 16 is accommodated: the plate 16 do not have a substantial contact with the gears 6, 8. The plate 16 has holes 33 which accommodate the rollers 18, and a gap 38 in the vicinity of the helical teeth 7, 9 is provided between the gears 6, 8. Further, the plate 16 has holes 25′ through which the stud bolts 26 penetrate.

(11) The plurality of the rollers 18, the plurality of the holes 33, and the plurality of the contact members 20 and 21 are respectively provided, and the plurality of holes 24 and the plurality of holes 25 are provided. The plate 16 has grooves 34 in its front and rear faces to supply a lubricant such as a grease or a lubricating oil between the rollers 18 and the contact members 20, 21, and the face and rear grooves 34 are connected through at least a through hole 35.

(12) FIG. 4 depicts the gear 8: the gear 8 is provided with the plural holes 25 for making the stud bolts 26 pass and plural screw holes 42 for fixing the bolts 26 and it is further provided with at least a lubricant inlet 44 connected to the groove 34.

(13) The functions of the embodiment will be described. The plate cylinders of the printing machine are driven by the drive shafts 10 so as to move synchronously with the main gear 2. When the main gear 2 rotates along the positive direction, the helical gears 7 of the drive shaft 6 are engaged with and are driven by the helical teeth 3 of the main gear 2, and, when the main gear 2 stops, the gear 6 tends to further rotate. At this instance, the anti-backlash gear 8 is biased by the tensile springs 30 towards the positive rotational direction of the main gear 2 and therefore it inhibits the inertial rotation of the gear 6 towards the positive direction. As a result, when the main gear 2 stops, the gear 6 stops simultaneously, and the drive shaft 10 is driven accurately and without backlash.

(14) When the main gear 2 stops, the gears 6 and 8 rotate relatively at a slight extent. This rotation is supported by the rollers 18, therefore, the biasing force by the tensile springs 30 are not canceled by the friction, and the backlash is reliably prevented. Note that the axial directions of the rollers 18 are perpendicular to the drive shaft 10 and that they are capable of supporting the relative rotation between the gears 6 and 8 when the main gear 2 stops.

(15) The rollers 18 consist of the harder material than that for the gears 6, 8, and therefore, the contact members 20, 21 are provided in order to prevent the gears 6, 8 from being worn. The lubricant is supplied via the lubricant inlet 44, the grooves 34, and the through hole 35 and it prevents the wear of the rollers 18 and the contact members 21 and 22.

(16) Since the plate 16 consists of the heat-resistant and self-lubricating synthetic resin, it may be used when the inside of the printing machine becomes heated to an elevated temperature and it wears very slowly due to its self-lubricating property.

(17) The inventive feature of the invention lies in the reduction of wear of the gears 6 and 8 by the rollers 18 accommodated within the holes of the plate 16, and other features may adequately be altered. In particular, the connection of the gear 8 to the gear 6 and to the drive shaft 10, the connection of the holder 14, and the species and the connection of the springs 30 are arbitrary.

(18) TABLE-US-00001 DESCRIPTION OF SYMBOLS  2 main gear  3 helical tooth  4 plate cylinder driving device  6 drive helical gear  8 anti-backlash helical gear 7, 9 helical tooth 10 drive shaft 12 coupling member 14 holder 15 arm 16 plate 18 roller 20, 21 contact member 22 gap 24, 25 hole 26 stud bolt 27 nut 28 coil spring 29 bolt 30 tensile spring 32 bolt 33 hole 34 groove 35 through hole 38 gap 40, 41 recess 42 screw hole 44 lubricant inlet