GB2223451A

GB2223451A - Flexographic print mechanisms

Info

Publication number: GB2223451A
Application number: GB8818737A
Authority: GB
Inventors: Dean Anthony Reader; Maurice Victor Jordan
Original assignee: R & J Engineering Ltd
Current assignee: R & J Engineering Ltd
Priority date: 1988-08-06
Filing date: 1988-08-06
Publication date: 1990-04-11
Also published as: GB8818737D0

Abstract

In an improved mounting arrangement for an ink transfer roller in a flexographic print mechanism, a trunnion (18) at each end of the transfer roller (14) is mounted in a bearing (20) housed in the base (34) of a mounting cup (22) arranged to slide transversely to the roller within a guide block, Fig. 1. A head of a rotatable mounting screw (30) is received within the cup (22) with a neck (28) of the screw extending through a slot in the cup wall (26). The rotatable screw (30) may be adjusted by a handwheel (48) to alter the position of the cup (22) and consequently the adjustment of the roller (14) against the printing roller. A supporting block (46) is secured to a side plate (44) by a clamping screw (54) and the mounting screw is threadedly engaged in the block. A lock nut (50) acts against the block to secure the screw in adjusted position. The roller can be easily removed by releasing the supporting blocks at each end and lifting the screws, blocks, cups and roller upwards. <IMAGE>

Description

IMPROVEMENTS RELATING TO FLEXOGRAPHIC PRINT MECHANISMS This invention relates to print mechanisms of the known kind comprising a print roller adapted to bear a flexographic printing plate on its surface, a platen roller arranged to support a web against the printing plate as the web passes between the two rollers during printing of the web, a transfer roller of the anilox type arranged to roll against the printing plate in order to transfer ink to its surface, and an inking roller arranged to roll against the transfer roller in order to spread ink over the surface of the transfer roller, the four rollers being linked to rotate in unison. Such a print mechanism, referred to hereinafter as a flexographic print mechanism of the kind defined, may for example be in a label printing machine for printing and/or overprinting self-adhesive labels fed as a continuous web through the machine.

It is an object of the present invention to provide an improved adjustable mounting arrangement for the transfer roller in such a mechanism, enabling the position and alignment of the roller adjacent to the print roller to be adjusted simply and readily.

The invention provides in one of its aspects a flexographic print mechanism of the kind defined in which at each end the transfer roller is rotatably mounted by an arrangement comprising a slider which bears a trunnion of the roller, a fixed guide member in which the slider is guided for movement in a direction transversely of the roller, and an adjusting mechanism comprising a rotatable screw which determines the position of the slider along the guide member.

Preferably the screw is mounted in a supporting block which can be readily released from supporting structure of the mechanism, so enabling the transfer roller to be removed easily.

To illustrate the invention by way of example, there now follows a detailed description of an anilox roller mounting in a flexographic print mechanism of a label printing machine. The description of the roller mounting is to be read with reference to the accompanying drawings, in which: Figure 1 is a view in elevation of an adjustable end mounting for one end of the anilox roller; and Figure 2 is a view of the mounting in section on the line II-II of Figure 1, the end of the roller being shown mounted.

A flexographic print mechanism of a known kind, in a label printing machine, comprises a horizontal print roller 10, a platen roller 12, a transfer roller 14 of the anilox type, and an inking roller. The inking roller is not shown but is of a conventional kind, serving to spread ink from a reservoir over the surface of the anilox roller. The anilox roller has an etched surface forming a mesh of dots to specification "200 screen" (as is conventional in such print mechanisms).

( LO- is an TC) The print roller 10 has a flexographic printing plate 16 secured to its surface. The four rollers are linked by gearing 17 to ensure rotation in unison. The print roller 10 is mounted over the platen roller 12 to print an impression on to a label passing trapped between the plate 16 and the platen roller. The anilox roller 14 is arranged to roll against the printing plate 16 in order to transfer ink to it in a customary manner.

The mounting arrangement for the anilox roller 14 is illustrated in the drawings, one end mounting being illustrated but there being an identical mounting for the opposite end of the roller. At each mounting, an end portion of the roller 14 forming a trunnion 18 is supported by a ball bearing 20 housed in the base of a mounting cup 22; the cup is aligned coaxially with the roller, the mouth of the cup facing towards the roller. An axially extending slot 24 in the annular cup wall 26 receives a reduced neck portion 28 of a bottom end portion of a radially extending mounting screw 30, the slot being open-ended at the cup mouth.

A head 32 of the screw, received within the cup and broader than the slot 24, prevents radial withdrawal of the screw from the cup.

The cup 22 and bearing 20 together form a slider of the mounting arrangement, a reduced diameter bottommost portion 34 of the base of the cup being a sliding fit between parallel side walls 36 and 38 of a fixed guide block 40. A base plate portion 42 of the guide block 40 is secured to a vertical side plate 44 of the printing machine, the side walls 36 and 38 of the block being inclined at an angle of 300 to the vertical.

The roller 14 is so free to be raised and lowered (at each end) by means of the mounting screw 30 which determines the position of the cup 22 in the inclined guide block 40. The screw, at a position above the guide block 40, is in threaded engagement with a supporting block 46 which it passes through and which is also secured to the side plate 44. A hand wheel 48 is secured on the outer end of the screw 30 to enable the screw to be rotated, and a locknut 50 on the screw above the supporting block 46 can be tightened against an upper face 52 of the block to secure the screw in any adjusted position.

The supporting block 46 is secured to the side plate 44 by means of a clamping screw 54. The screw 54 extends through a clearance slot 56 in the side plate and is threadably engaged in the block; the screw, when tightened, so clamps the side plate. between a head portion 58 of the screw and the supporting block 46.

The slot 56 is aligned with the guide block 40 and is open-ended at a top edge of the side plate.

The mounting arrangement permits the position of the anilox roller 14, at each end, to be adjusted simply and precisely in setting up the machine for printing. Upon releasing the locknut 50, the screw 30 can be turned by means of the handwheel 48 to alter the position of the cup 22 (and so the roller trunnion 18) on the guide block 40. After suitable adjustment the locknut 50 can be retightened to secure the roller in position.

When required, the roller 14 can readily be removed. After releasing the clamping screws 54 of the mountings at each end of the roller, so loosening the grip of the supporting blocks 46 on the side plates 44, the roller assembly can be lifted out from between the side plates, the clamping screws 54 being lifted out of the slots 56 and the mounting cups 22 being drawn upwards from between the side walls 36 and 38 of the guide blocks 40. Reassembly can be achieved simply in the reverse order.

Claims

1. A flexographic print mechanism of the kind defined in which at each end the transfer roller is rotatably mounted by an arrangement comprising a slider which bears a trunnion of the roller, a fixed guide member in which the slider is guided for movement in a direction transversely of the roller, and an adjusting mechanism comprising a rotatable screw which determines the position of the slider along the guide member.

2. A flexographic print mechanism according to claim 1 in which the slider comprises a bearing supporting the trunnion and housed in the base of a mounting cup.

3. A flexographic print mechanism according to claim 2 in which the base of the cup is a sliding fit between parallel side walls of the guide member.

4. A flexographic print mechanism according to either of claims 2 and 3 in which a neck portion of the rotatable screw is received in a slot in the wall of the mounting cup, a head of the screw being received within the cup and being broader than the slot, so preventing radial withdrawal of the screw head from the cup.

5. A flexographic print mechanism according to any one of the preceding claims in which the screw is in threaded engagement with a supporting block, the supporting block being releasable for removal of the roller.

6. A flexographic print mechanism according to claim 5 in which the supporting block is secured to a side plate by means of a releasable clamping screw.

7. A flexographic print mechanism according to either of claims 5 and 6 in which a lock nut is arranged to be tightened against the block to secure the screw in adjusted position.

8. A flexographic print mechanism constructed arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.