GB2205069A - A printing press having a printing roller which always rotates in a unitary direction - Google Patents

Abstract

In a printing press wherein a printing roller effects a horizontal straight reciprocating motion, means 30 is provided for rotating the printing roller in a unitary direction whenever the roller is moved horizontally in any direction. Pinion 32 and 33 are mounted rotatably on the shaft 22 of the printing roller, rack 36 is positioned below the pinion 32 for meshing therewith, and another rack 37 is positioned above the pinion 33 for meshing therewith. The racks 36 and 37 are fixed on a press base so that when the shaft 22 is moved horizontally, the pinions 32 and 33 mesh with the racks 36 and 37 respectively and rotate in opposite directions. Pinion 32 has engagement element 34 on its inward surface and pinion 33 has engagement element 35 on its outward surface for cooperating with notches 312, 382 in annular members 31, 38 so that the printing roller 21 always rotates in the unitary direction. The difference between the printed colours of two continuously printed papers is thereby minimized. <IMAGE>

Description

A PRINTING PRESS HAVING A PRINTING ROLLER WHICH ALWAYS ROTATES IN A UNITARY DIRECTION The present invention relates to a printing press, and more particularly to a highly efficient printing press.

A -printing press is used for the production of printed impression on paper and other material. In a printing process, a printing roller effects a horizontal straight reciprocating motion. In a conventional printing press, as disclosed in British Patent No. 1 477 984, the printing roller rotates in a direction during its forward movement and in the opposite direction during its return movement.

Additionally, an ink feeding means is disposed above the printing roller for transferring the printing ink from an ink reservoir onto a printing block of the printing roller.

It is understood that this two-direction rotation of the printing roller often results in significant difference between the printed colours of two continuously printed papers due to the following reasons: 1. The printing roller effects the horizontal straight reciprocating motion in a direction perpendicular to the fed direction of the papers to be printed. If the carrier means for carrying the printing roller is positioned inaccurately, the significant difference between the printed colours of two continuously printed papers will occur.

2. The printing roller receives the printing ink from a set of ink transfer rollers during its forward movement and from another set of ink transfer rollers during its return movement. The printing ink supplied from two sets of ink transfer rollers onto the printing roller may result in the difference between the printed colours of two continuously printed papers.

3. Two continuously printed papers are printed from the opposite ends thereof so that the significant difference between the printed colours of the two papers may be produced.

Furthermore, prior to printing, the carrier means must be adjusted and tested again and again until it is positioned accurately. This wastes much time.

It is therefore the main object of the present invention to provide a printing press which minimizes the difference between the printed colours of two continuously printed papers.

It is another object of the present invention to provide a printing press which minimizes the time required to adjust a carrier means for carrying a printing roller prior to printing.

According to the present invention, the printing press includes a carrier means for carrying a printing roller thereon, the carrier means is designed so that the printing roller always rotates in a unitary direction when it effects a horizontal straight reciprocating motion. Preferably, a pinion and rack means is provided for maintaining stable horizontal straight reciprocating motion of the carrier means.

The pinion and rack means includes a pinion mounted rotatably on the carrier means, and a rack fixed horizontally on the press base.

Other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings in which: Fig. 1 is a schematic side view showing a part of a printing press according to the present invention; Fig. 2 is a schematic sectional view illustrating the relation between a printing roller and the carrier means for carrying the printing roller in the printing press according to the present invention; and Fig. 3 is an exploded view showing a control means of the printing press according to the present invention.

Referring to the drawings, there is shown a printing press according to the present invention, excluding its ink feeding means. As illustrated, the printing press is characterized. in the carrier means for carrying a printing roller 21. The carrier means is driven by a sliding-block linkage 10 which includes a pair of sliding blocks 14 and a toggle mechanism for driving the sliding blocks 14 to effect a straight reciprocating motion in horizontal direction C in a slide slot B1 in a wall of the press base. The toggle mechanism consists of a rotating wheel 11 drivable by a power source (not shown), e.g. a motor, and links 12 and 13, and a rotating shaft 141 to which the sliding blocks 14 are connected rotatably by ball bearings.

The rotating shaft 141 is provided with a first pinion 15 secured to one end thereof for meshing with a first rack 16 fixed on the press base below the first pinion 15 for maintaining stable sliding movement of the sliding blocks 14.

The shaft 22 of the printing roller 21 is connected rotatably to and between the sliding blocks 14 by ball bearings.

The main feature of the present invention will be described. The carrier means is equipped with a control means 30. As seen more clearly from Fig. 3 with reference to Fig. 2, the control means 30 includes an inner annular member 31, an outer annular member 38, a second pinion 32, a third pinion 33, a second rack 36, and a third rack 37. The inner and outer annular members 31, 38 are fixed on the shaft 22 of the printing roller 21 for defining an annular groove therebetween for mounting rotatably the second and third pinions 32, 33 on the shaft 22 by a pair of ball bearings 39. The second rack 36 is positioned below the second pinion 32. But the third rack 37 is positioned above the third pinion 33.

In addition, each of the inner and outer annular members 31, 38 is formed with a tapered notch 312, 382 in the end wall 311, 381 thereof. The inward surface of the second pinion 32 is provided with a first unidirectional engagement element 34 having a radially inwardly curved free end 342 which is biased to move radially inwardly by a first resilient element 341.

Similarly, the outward surface of the third pinion 33 is provided with a second unidirectional engagement element 35 having a radially inwardly curved free end 352 which is biased to move radially inwardly by a second resilient element 351. The incorporation of the engaging members 34,35 with the tapered notches 312, 382 results in unidirectional relative rotation between the second pinion 32 and the inner annular member 31 and between the third pinion 33 and the outer annular member 38. For example, referring to Fig. 1, if the third pinion 33 is fixed, the outer annular member 38 can only rotate counterclockwise. Similarly, if the second pinion 32 is fixed, the inner annular member 31 can only rotate counterclockwise.

In operation, when the sliding blocks 14 are moved to the right, the second pinion 32 rotates clockwise due to the fact that the second rack 36 is positioned above the second pinion 32, and the third pinion 33 rotates counterclockwise due to the fact that the third rack 37 is positioned above the third pinion 33. At the same time, the first engagement element 34 disengages from the notch 312 of the inner annular member 31, while the second engagement element 35 engages with the notch 382 of the outer annular member 38 so that the shaft 22 and hence the printing roller 21 are drived by the third pinion 33 to rotate counterclockwise. It is noted that when the printing roller 21 is moved from the leftmost to the rightmost, it turns 180 degrees itself. When the printing roller 21 is moved from the rightmost to the leftmost, the third pinion 33 rotates clockwise so that the second engagement element 35 disengages from the notch 382 of the outer annular member 38, and the second pinion 32 rotates counterclockwise so that the first engagement element 34 engages with the notch 312 of the inner annular member 31, thereby driving the shaft 22 and hence the printing roller 21 to still rotate counterclockwise. Certainly, when the printing roller 21 is moved from the rightmost to the leftmost, it turns 180 degrees itself. Accordingly, the unidirectional rotation of the printing roller 21 is achieved.

Because the printing roller 21 always rotates counterclockwise, in addition to improved quality of printed products, the rotational speed of the printing roller 21 may be increased to a greater extent in comparison with conventional printing presses without risking significant difference between the printed colours of two continuously printed papers. The efficiency of the printing press is thus promoted.

With the present invention thus explained, it is apparent that various modifications and variations can be made without departing from the scope and spirit of the present invention. It is therefore intended that the present invention be limited only as indicated in the appended claims.

Claims (4)

CLAIMS:

1. A printing press comprising: a sliding-block linkage, including a sliding block means and a toggle mechanism for driving said sliding block means to effect a horizontal straight reciprocating motion; a press base; a printing roller disposed above said press base and having a shaft connected to said sliding block means for synchronous horizontal straight reciprocating motion therewith; and means for rotating stably said printing roller in a unitary direction whenever said printing roller is moved horizontally in any direction.

2. A printing press as claimed in Claim 1, further comprising means for maintaining stable horizontal straight reciprocating motion of said sliding block means.

3. A printing press as claimed in Claim 2, wherein said maintaining means includes a first pinion and rack means, said first pinion and rack means including a first pinion mounted rotatably on said sliding block means and a first rack fixed horizontally on said press base for meshing with said first pinion when said sliding block means is moved horizontally.

4. A printing press substantially as described hereinbefore with reference to the accompanying drawings.

4. A printing press as claimed in Claim 1, wherein said rotating means includes: a second pinion and rack means, including a second pinion mounted rotatably on said shaft of said printing roller, and a second rack fixed horizontally on said press base below said second pinion for meshing with said second pinion when said shaft is moved horizontally; a third pinion and rack means, including a third pinion mounted rotatably on said shaft of said printing roller, and a third rack fixed horizontally on said press base above said third pinion for meshing with said third pinion when said shaft is moved horizontally; and a first locking means for automatically interlocking said second pinion and said shaft of said printing roller when said second pinion rotates in a predetermined direction; and a second locking means for automatically interlocking said third pinion and said shaft of said printing roller when said third pinion rotates in the predetermined direction; whereby, when said shaft of said printing roller moves in a first horizontal direction, one of said first and second pinions rotates in said predetermined direction so that said shaft and hence said printing roller rotate in said predetermined direction due to the fact one pinion and said shaft are interlocked; ad, when said shaft of said printing roller moves back in a second horizontal direct in opposite to said first horizontal direction, the other of said first and second pinions rotates in said predetermined direction so that said shaft and hence said printing roller rotate in said predetermined direction due to the fact that said other pinion and said shaft are interlocked.