Adjuster for printing press

Abstract

An adjuster for first and second print rollers carried on respective first and second supports has a first spindle extending along and rotatable about an axis between the supports and formed with a pair of axially spaced screwthreads of the same hand but of different pitches. One of the screwthreads is threaded into the first support and the other into a first nut rotatable about the axis and axially fixed in the second support. A mechanism serves for either arresting the nut against rotation relative to the second support and or rotating the nut relative to the second support.

Claims

1. In combination with first and second print rollers carried on respective first and second supports, an adjuster comprising: a first spindle extending along and rotatable about a first axis and formed with a pair of axially spaced screwthreads of the same hand but of different pitches, one of the screwthreads being threaded into the first support; a first nut rotatable about the first axis, axially fixed in the second support, and threaded onto the other of the screwthreads; means for arresting the first nut against rotation relative to the second support; and means for rotating the first nut relative to the first spindle.

2. The press-roller adjuster defined in claim 1, further comprising: a third roller having a respective third support; a second spindle extending along and rotatable about a second axis and formed with a pair of axially spaced screwthreads of the same hand but of different pitches; one of the screwthreads of the second spindle being threaded into the third support; a second nut rotatable about the second axis, axially fixed in the second support, and threaded onto the other of the screwthreads of the second spindle; and means displaceable between a holding position for arresting the second nut against rotation relative to the second support or the second spindle and a release position permitting such rotation.

3. The press-roller adjuster defined in claim 2, further comprising: a longitudinal force-generating element between the first and second supports or between the second and third supports.

4. The press-roller adjuster defined in claim 1, further comprising: a longitudinal force-generating element between the first and second supports.

5. The press-roller adjuster defined in claim 1, further comprising: an actuator rotating the first nut.

6. The press-roller adjuster defined in claim 5, further comprising: a drive element connecting the actuator to the first nut.

7. The press-roller adjuster defined in claim 6, wherein the drive element is a belt, a chain, or a set of gears.

8. In combination with first and second print rollers carried on respective first and second supports, an adjuster comprising: a first spindle extending along and rotatable about a first axis and formed with a pair of axially spaced screwthreads of the same hand but of different pitches, one of the screwthreads being threaded into the first support; a first slotted nut rotatable about the first axis, axially fixed in the second support, and threaded onto the other of the screwthreads; means for arresting the first nut against rotation relative to the second support; means for rotating the first nut relative to the first spindle; and means for biasing the first nut axially.

9. In combination with first and second print rollers carried on respective first and second supports, an adjuster comprising: a first spindle extending along a first axis, rotatable about the first axis, and formed with a pair of axially spaced screwthreads of the same hand but of different pitches, one of the screwthreads being threaded into the first support; a first nut rotatable about the first axis, axially fixed in the second support, and split transversely into at least two parts and threaded onto the other of the screwthreads; means for arresting the first nut against rotation relative to the second support by relatively axially moving the parts; means for rotating the first nut relative to the first spindle; and means for biasing the parts axially away from each other.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a side view of the adjuster for a roller constructed according to the invention;

(3) FIG. 2 is an enlarged sectional view of a slotted nut in a bearing;

(4) FIG. 3 is an enlarged sectional view of a split nut in a bearing;

(5) FIG. 4 is an enlarged sectional view of a nut that is firmly seatable to a spindle or a bearing;

(6) FIG. 5 is an enlarged sectional view of the adjuster of a roller with a longitudinal force-generating element;

(7) FIG. 6 is the sectional view of the adjuster for a roller in which the nut is connected to an actuator by a drive element.

SPECIFIC DESCRIPTION OF THE INVENTION

(8) As seen in FIG. 1, a counter pressure roller 9a, a print roller 9b, and an anilox roller 9c are carried on respective first, second, and third supports 7a, 7b, 7c for rotation about respective parallel and normally horizontal axes. First and second spacing-setting spindles 1a and 1b rotatable about respective parallel and vertical axes each have two respective screwthreads 2a, 3a and 2b, 3b of the same hand but slightly different pitches. The screwthreads 2a and 2b are each engaged in a respective nut 4a and 4b that is rotatable in a respective bearing 5a and 5b of the second support 7b that is carried on a guide 8 of the first support 7a for straight-line or linear vertical movement. The other screwthreads 3a and 3b are engaged in respective screwthreads 6a and 6b integrated in the first or third support 7a or 7c, respectively. The same adjuster mechanism is also on the opposite ends of the rollers 9a, 9b, and 9c.

(9) In order to adjust the spacing between the third anilox roller 9c and the second print roller 9b, the spindle 1a is axially coupled to the second slide support 7b and can rotate in the third support 7c.

(10) For fine adjustment of both supports 7b and 7c the nut 4a is rotationally locked to the bearing 5a of the slidable second support 7b. In this mode the screwthread 6 is also firmly connected to the support 7c. Rotation of the spindle 1a leads to axial movement of the spindle 1a relative to the slidable second support 7b while the support 7c is moving in the opposite direction due to the identical orientation of the screwthreads 2a and 3a. A slightly different pitch of the screwthreads 2a and 3a leads to a small relative movement between both supports 7b and 7c.

(11) For coarse adjustment the nut 4a is not rotationally fixed in the bearing 5 and is therefore rotatable in the slidable second support 7b. The screwthread 6 is rotationally locked to the support so that rotation of the spindle 1a leads to a movement of the support 7c relative to the spindle 1a. Since the nut 4 is rotatable in the second support 7b the relative position between the slidable second support 7b and the spindle 1a does not change on rotation of the spindle 1a. As result the whole displacement is determined by the screwthread 3b, so that the movement effected by one rotation is significantly larger than in fine adjustment mode.

(12) According to a preferred embodiment of the invention one press roller is rotatable mounted to supports, and the position of the press rollers is given by the position of the supports. A typical flexographic printing press setup has three press rollers, namely the counter-pressure roller 9c, the print roller 9b and the anilox roller 9a. In a preferred version of this invention the spacing between the print roller 9b and anilox roller 9c is determined by at least one spindle 1a connected by the screwthread 2a with the nut 4a in the slidable second support 7b and by the screwthread 3a threaded into the support 7c. In addition the spacing between the counter-pressure roller 9a and the print roller 9b is determined by at least one spindle 1b engaged with screwthread directly to the support 7a and by the screwthread 2b to the nut 4b in the slidable second support 7b. In this configuration the nuts 4a and 4b are rotatable in the respective bearings 5a and 5b of the second support 7b carrying the middle print roller 9b.

(13) There are thus five possible modes:

(14) 1. Fine adjustment with a driven spindle Nut 4a locked to the support 7b Nut 4a not locked rotationally to the spindle 1a Result: Rotation of the spindle 1a will shift the support 7c relative to the support 7b at a rate determined by the difference between the pitches of the screwthreads 2a and 3a.

(15) 2. Coarse Adjustment with a driven spindle Nut 4a not locked rotationally to the support 7b Nut 4a not locked rotationally to the spindle 1a Result: The displacement rate of the support 7b will be determined solely by the coarse pitch of the screwthread 3a. The spindle 1a will not move axially because of the friction of the bearing seat 5a and the friction resistance of the spindle 1a in the nut 4a is much higher than the friction of the nut 4a to the support 7b. This mode depends on pitch, friction, and other factors. But the impact of these factors is negligible. Especially, the impact is negligible for the coarse adjustment where a high precision is not needed.

(16) 3. Coarse Adjustment with a driven spindle Nut 4a not locked rotationally to the support 7b Nut 4a locked rotationally to the spindle 1a Result: The displacement rate of the support 7b will be determined solely by the coarse pitch of the screwthread 3a. The spindle 1a will not move axially.

(17) 4. Fine adjustment with a driven nut Nut 4a not locked rotationally to the support 7b Nut 4a not locked rotationally to the spindle 1a Result: Since the nut 4a is not locked to the spindle 1a, rotation of the nut 4a leads to rotation of the spindle 1a. Since the nut 4a is axially fixed in the support 7b, the spindle moves axially. Rotation of the spindle 1a will shift the support 7c relative to the support 7b at a rate determined by the difference between the pitches of the screwthreads 2a and 3a.

(18) 5. Coarse adjustment with a driven nut Nut 4a not locked rotationally to the support 7b Nut 4a locked rotationally to the spindle 1a Result: the spindle 1a is not allowed to rotate and the nut 4a is driven (e.g. by the drive 15 of FIG. 6), so the support 7c will be moved at a rate purely determined by the finer pitch of the screwthread 2a. The spindle 1a will not move at all.

(19) FIG. 2 is a detailed sectional view of a spindle 1 and a nut 4. The nut 4 is engaged to a screwthread 2 and can rotate but not move axially in a bearing 5. In order to bias the nut 4 toward the spindle 1, the nut 4 is formed with a transverse slot 10. The nut 4 is biased toward the spindle 1 by a biasing unit 11 that pushes the parts of the nut 4 separated by the slot apart and clamps the nut 4 in the bearing 5. The biasing means 11 could for example be a screw, a pneumatic element or electro-mechanical clamp.

(20) FIG. 3 shows another version of a nut 4 that is rotatable in a bearing 5. In this embodiment of the invention the nut 4 is split into an upper part 4 and a lower part 4 separated by a gap 16.

(21) In this preferred embodiment of the invention the upper part 4 of the split nut and the lower part 4 of the split nut 4b are pushed in axially opposite directions by a biaser 11. This compensates for wear of the nut and/or screwthreads and minimizes the clearance between the nuts 4a and 4b and the respective screwthreads 2a and 2b.

(22) A preferred embodiment of the invention is shown in FIG. 4, wherein the nut 4 is split into two parts, the upper part 4 and the lower part 4 and set in the bearing 5. In this embodiment of the invention the nut could be rotationally locked to the bearing 5 by a first clamp 12. Furthermore, the nut 4 could be rotationally locked to the spindle 1a by a second clamp 12. This embodiment of the invention makes it possible to firmly rotationally fix the nut 4 in the bearing 5 or in the spindle 1a.

(23) FIG. 5 shows another embodiment of the invention in which a longitudinal force-generating element 13 is provided between the supports 7b and 7c. This longitudinal force-generating element 13 pushes the supports apart or pulls them together in order to reduce clearance between the nuts 4a and 4b and the corresponding screwthreads 2a, 2b, 3a, and 3b. Due to this longitudinal force-generating element 13 wear of the screwthread or nut material is compensated for and precise adjustment or positioning of the supports 7 is ensured. The longitudinal force-generating element 13 is for example a mechanical cylinder, electro-mechanical cylinder or pneumatic cylinder.

(24) In a preferred embodiment of the invention a longitudinal force-generating element 13 is provided between the slidable second support 7b and the support 7c and between the slidable second support 7b and the support frame 7a so that a precise positioning between counter-pressure roller 9a and print roller 9b and between print roller 9b and anilox roller 9c could be effected.

(25) A user-friendly embodiment of the invention is shown in FIG. 6, where a nut 4a is rotated about the axis of the spindle 1a by a drive or actuator 15. In this embodiment of the invention coarse adjustment is effected when the nut 4a is rotationally locked to the spindle 1a and rotatable in the bearing 5a. In this case rotation of the nut 4a leads to rotation of the spindle 1a while due to the rotational connection between the spindle 1a and the nut 4a the spacing between the spindle 1 and the slidable second support 7b does not change. But the rotation of the spindle 1a leads to linear movement of the support 7c that is moving with respect to the slidable second support 7b. In this mode movement depends only on the pitch of the screwthread 2a or of the screwthread 3a.

(26) In this embodiment fine adjustment is effected when the nut 4a is rotatable in the bearing 5a and also not rotationally fixed to the spindle 1a. In this mode rotation of the nut 4a leads to a linear movement of the spindle 1a relative to the slidable second support 7b that is determined by the pitch of screwthread 2a. At the same time the support 7c is moving into longitudinal direction due to the rotation of the spindle 1a. The identically orientated screwthreads 2a, 3a lead to an opposite movement of the support 7c. The resulting movement is than determined by the difference of the pitch of the screwthreads 2a, 3a and therefore very precisely tunable.

(27) The nut 4a is rotationally drivable connected to an actuator 15 by a drive element 14 in another preferred embodiment of the invention. This drive element is for example a belt, a chain or a combination of gears.

(28) In a preferred version of the invention the spacing between the two supports 7b and 7c is determined by two spindles 1a that are both driven by one actuator 15 rotationally drivable connected by a drive element 14. In this way one actuator 15 could be used to adjust the positions of the rollers 9b and 9c along their longitudinal axes.

(29) Another embodiment of the invention that is not shown in FIG. 6 has all of the nuts 4a rotationally driven by a single actuator 15 and drive element. This drive element is for example a drive belt, a drive chain or a set of drive gears. This embodiment of the invention provides the option to move all spindles 1 and therefore, all the rollers by only one actuator 15.

(30) In an embodiment of the invention that is not shown in the figures. all of the nuts 4a are rotationally connected to a single actuator 15 by a drive element 14 and all of the nuts 4a are rotationally fixed on the spindle 1a by a first clamping lever 12b or in the bearing 5 by a second clamping lever 12a. With this embodiment of the invention it is possible to drive all the spindles 1 with a single actuator 15 and automatically switch each spindle 1a between coarse or fine adjustment.

(31) An adjuster or a roller according to this invention provides a solution with minimal construction costs and required space, that can be manually or motor driven to enable an easy change between coarse and fine adjustment.