Apparatus for controlling the lateral position of an elongated web

Abstract

This apparatus includes means for changing the length of the path of one edge of a longitudinally moving web in comparison to the length of the path of the other edge. The path lengths are changed in order to shift the web laterally with respect to its path of movement, so as to maintain the web within a predetermined range of deviation from a central position. The apparatus includes an edge sensing means for each edge of the web, and a pair of motors, each controlled by one edge sensing means and operating a device which changes the length of the path for one edge of the web. The device which changes the path length comprises a pair of fixed parallel bars or rollers defining a straight path for one run of the moving web, and a movable bar normally spaced from but movable to engage the web between the two fixed bars and having its end movable by the two motors. The movable bar is convex in the direction of web movement and may also be convex in the direction perpendicular to the direction of web movement. The apparatus is shown as used in connection with a wiping web for an intaglio printing press. The web moves between the plate cylinder of the press and a wiping shoe. The apparatus may be double acting, i.e., each motor may operate one path length changing means upstream from the pad over which the web moves and another path length changing means downstream from that pad.

Description

CROSS-REFERENCES

U.S. Pat. application, Ser. No. 298,443, filed Oct. 17, 1972, by Ivaldo Gazzola et al; and entitled "PRINTING PRESSURE CONTROL APPARATUS FOR INTAGLIO PRESS," discloses a press similar to that illustrated herein and with which the present invention will be used.

U.S. Pat. application, Ser. No. 372,066, filed June 21, 1973, by the present inventors, entitled "INTAGLIO PRINTING PRESS WITH WEB WIPING APPARATUS HAVING SUPPLY AND TAKE-UP REELS OUTSIDE FRAME," discloses a press having a web wiping apparatus with which the present invention may be used.

BRIEF SUMMARY OF THE INVENTION

In any apparatus employing an elongated web of indefinite length, it is necessary to supply some means for maintaining the web in correct lateral alignment with regard to its supply and take-up reels and the intermediate guiding members over which it runs. It has been proposed to guide the moving web, i.e., to shift the moving web laterally, by changing the length of the path traveled by one edge of the web as compared to the length of the path traveled by the opposite edge. For example, the U.S. Pat. to Medkeff, No. 2,814,487, shows an apparatus in which the distances traveled by the two edges of the web are varied by pivoting the supply roll about an axis perpendicular to the axis about which it rotates to deliver the web material.

Himrod et al; U.S. Pat. No. 3,317,101 suggests the use of a "cambering roll" which is variably tilted with respect to the direction of motion of the web for the purpose of shifting the web laterally.

Kurz, U.S. Pat. No. 3,570,735 shows a pair of rolls engaging opposite sides of a web and suggests a shifting of those rolls in some fashion not clearly explained, for "influencing the lateral movement of" the web.

The present invention maintains the web in a central position more stably and without overcontrolling the lateral movement of the web. In the present invention, two edge sensing devices are used, one at each edge of the web, and each edge sensing device controls a motor which changes the distance moved by one edge of the web.

The mechanism for changing the distances moved by edges of the web comprises a non-rotating bar engaging one face of the web and spaced longitudinally of the web between two fixed bars or rollers which define a straight path for one rim of the web. Each motor moves one end only of the movable bar. In a preferred modification, the movable bar has a surface which is convex both in the longitudinal direction of the web and in the lateral direction of the web.

The distance changing mechanism may operate on the web either upstream or downstream, or both, from the working station, e.g., the station where the web wipes against the surface of the cylinder of an intaglio press.

DRAWINGS

FIG. 1 is a somewhat diagrammatic and partly perspective view of a web position controlling apparatus embodying the invention.

FIG. 2 is a fragmentary view illustrating a modification.

FIG. 3 is a sectional view, on an enlarged scale, taken on the line 3--3 of FIG. 2.

FIG. 4 is a sectional view taken on the line 4--4 of FIG. 5, illustrating another modification.

FIG. 5 is a diagrammatic view illustrating a further modification of the invention.

DETAILED DESCRIPTION

FIG. 1

This figure illustrates a plate cylinder 1 for an intaglio press and a wiping pad 2 biased into engagement with the surface of the cylinder 1 by conventional means not shown, and a wiping web 3 which moves from a supply reel, not shown, along the path of movement indicated by the arrows, between the pad 2 and the cylinder 1 and thence to a take-up reel, also not shown. A pair of edge sensing devices are shown at 4 and 5. Each of the devices 4 and 5 comprise a yoke which spans one edge of the web 3. The devices 4 and 5 are fluidic sensors and each has an air inlet connection adapted to be connected through a conduit 6 or 7 to a manifold 8, which receives air from a conduit 11 connected to a supply of air under pressure. Each of the devices 4 and 5 has an internal passage 6a or 7a (FIG. 4) connected to its inlet 6 or 7. Each of the passages 6a and 7a terminates in an opening located on the inside face of one leg of its yoke. Opposed to those openings 6a, 7a are openings 12a, 14a in the opposite leg of the yoke, leading to passages 12a, 14a (FIG. 4) connected to conduits 12 or 14, each communicating with a pressure sensitive element generally indicated at 13 or 15 (FIG. 1). A pair of conduits 16 and 17 lead from the manifold 8 to the pressure sensitive elements 15 and 16. Each of the elements 13 and 15 comprises a bellows 21 or 22 operating a movable switch contact 23 or 24, connected to an upper supply line 25 and cooperating with a stationary contact 27 or 32, respectively connected to an electromagnet 26 in the case of switch contact 23 and an electromagnet 31 in the case of switch contact 24. The opposite terminals of the electromagnets 26 and 31 are connected to a lower supply line 28.

The bellows 21 and 22 are each subject to the difference between the supply pressure in lines 16 and 17 and the somewhat reduced pressure received through the conduits 12 and 14. This pressure difference is balanced, for normal positions of the web 3, by internal springs within the bellows 21 and 22, so that the switches remain open.

The electromagnet 26 operates a piston valve 33 which controls the flow of liquid from a supply line 34 to a hydraulic cylinder 35, and from cylinder 35 to a low pressure drain line 38. The cylinder 35 operates a piston rod 36 pivotally connected to one arm of a bell crank lever 37. The other arm of lever 37 is connected through a universal joint 41 to one end of a guide bar 42.

Similarly, the electromagnet 31 operates a valve 43 which regulates the flow of hydraulic fluid to and from a hydraulic cylinder 44 connected to one arm of a bell crank lever 45. The other arm of the bell crank lever 45 is connected by means of a universal joint 46 to the opposite end of the guide bar 42.

The web 3 approaching the wiping shoe 2, normally passes along a straight path over stationary bars 47 and 48. Between those bars, the web 3 passes under the guide bar 42, which is non-rotating and is normally spaced from the web 3.

The bars 47 and 48 are mounted in fixed frame members 51 and 52 located at the opposite sides of the path of travel of the web 3. The bar 42 is moved by the cylinders 35 and 44 in a direction which intersects the plane defined by the guide bars 47 and 48. This direction is ideally perpendicular to that plane, but need not necessarily be perpendicular. In the illustrated embodiment, for example, the direction of movement of each end of bar 42 is perpendicular to the plane only in one angular position of the supporting lever.

OPERATION OF FIG. 1

As long as the lateral position of web 3 remains within a predetermined range of a middle position shown in FIG. 4, in which range neither margin of the web is blocking the flow of air from either port 6a or 7a to the corresponding port 12a or 14a, the switch contacts 23 and 24 are maintained open, and the valves 33 and 43 are biased by internal springs to their lower position, in which the left ends of the hydraulic cylinders 35 and 44 are connected to hydraulic supply line 34, and the right-hand ends of those cylinders are connected to hydraulic drain line 38. Consequently, the bar 42 remains in its normal position spaced above the web 3.

The devices 4 and 5 may be adjustably mounted to establish selectively the middle position just described.

Assume now that the web 3 shifts to the left from the position shown in the drawing, thus blocking at least partially the flow from the passage 6a to the receiving passage 12a. Hence, the bellows 21 contracts and contact 23 engages the stationary contact 27, energizing the electromagnet 26 to operate valve 33 to its upper position so that fluid moves from the supply line 34 through valve 33 to the right-hand end of cylinder 35, thereby driving the bell crank lever 37 counterclockwise and lowering the left-hand end of the bar 42 into engagement with the left edge of web 3. This increases the length of the path of travel of the left edge of web 3 as compared to the length of the path of travel of the right-hand end. The web is thereby moved back toward the right, decreasing the blockage of flow between passage 6a and the receiving passage 12a. This motion continues until contact 23 opens.

If the web 3 shifts to the right from the middle range of positions, the edge sensing device 5 controls the cylinder 44 similarly through the pressure sensitive device 15 and valve 43, so as to move the lever 45 counterclockwise and lower the right-hand end of the bar 42, thereby increasing the length of the path of the right-hand edge of the web and moving the web back toward the left.

The hydraulic supply lines connected to the motors 35 and 44 are provided with restrictions 53, 54, 55 and 56, which limit the rate of flow of hydraulic fluid into and out of the cylinders 35 and 44, and thereby limit the rate of correction of the lateral position of the web. Alternatively, only one restriction might be provided for each motor. By providing such a limitation on the rate of movement, it is insured that the web will return to its desired position and that the system will then come into balance without overshooting.

The fluid paths through the sensing devices 4 and 5 are normally open, and each device controls a cylinder 35 or 44 on its own side of the web. Alternatively, the sensing devices may be operated with their fluid paths normally blocked, in which case each sensing device controls the cylinder on the opposite side of the web.

FIGS. 2-3

These figures illustrate a modification of the apparatus shown in FIG. 1, in which the straight bar 42 of FIG. 1 is replaced by a bar 61 having a web engaging surface 61a, which is convex in the direction of web travel, as seen in FIG. 3, and is also convex in the direction crosswise of the web, as may be seen in FIG. 2. This conformation of the guide bar 61 tends to maintain the web centralized on the bar. Furthermore, if the bar 61 is tilted to one way or the other by the motors 35 or 44, the restoring movement of the web toward the center position is more rapid as compared to the movement with a straight bar 42. This construction of the bar is especially desirable in the case of stretchable webs, such as crinkled kraft paper, which is commonly used for the wiping systems of intaglio presses.

FIG. 4

This figure illustrates a modification of the apparatus of FIG. 1, in which the shoe 2 over which the wiping web runs is oscillated endwise. The shoe 2 is fixed on a shaft 63 for angular movement therewith so that it may be tilted with respect to the plate cylinder 1, as required by the particular plate structure and the particular ink to be wiped therefrom. The shaft 63 carries a double flanged collar 64. Between the flanges of the collar 64 is captured a roller 64 carried by a lever 66, which is oscillated by any suitable conventional means (not shown) as the plate cylinder 1 rotates. The edge sensing means 4 and 5 in this figure are mounted on brackets 67 and 68 fixed on the under side of the shoe 2. The web 3 is thereby made to follow the oscillating lateral movements of the shoe 2. Such oscillating movements of the shoe are common in the art, and are designed to improve the wiping action of the web against the printing plate. By mounting the sensing devices 4 and 5 on the oscillating shoe, the web itself is made to oscillate with the shoe to improve further the wiping action of the web against the plate.

FIG. 5

In this figure, the web 3 moves over the fixed guide bars 47 and 48 under a movable guide bar 61 upstream of its path of movement over the shoe 2 and also moves over a pair of fixed guide bars 71 and 72 and under a movable guide bar 73 located downstream of the path of movement of the web over the shoe 2. The movable guide bar 73 is supported on the end of a lever arm 74 connected by a link 75 to the arm of lever 37 which carries the movable guide bar 61. Hence, the lever 37, lever 74, link 75 and the fixed frame of the press constitute a parallelogram linkage and guide bar 73 follows the movement of the guide bar 61.

By using the mechanism of FIG. 5, the moving web is subjected to a laterally directed position correcting force upstream of the shoe 2 and to another laterally directed position correcting force downstream of the shoe 2. The response of the web to the correctional forces is thereby made more rapid, and the web is enabled to follow the lateral oscillations of the shoe 2 more accurately. Furthermore, the corrective action is the same, regardless of the direction of movement of the web.

The invention has been described as applied to a wiping web for an intaglio printing press. It will be readily understood by those skilled in the art that the invention has particular utility in connection with such a press. Nevertheless, many features of the invention have broader utility in connection with web transport systems in general. In particular, the apparatus of FIG. 5 is useful to control the lateral position of any web passing through a work station where the web is subjected to longitudinal stress. In the apparatus disclosed, the web 3 is subjected to longitudinal stress when it passes the wiping pad 2, since it is being pulled past that pad by the motor driven take-up reel, and the pull of the take-up reel is opposed by the friction between the pad 2 and the cylinder 1.

Claims

We claim:

1. A printing press, comprising:

a. wiping means for removing ink from the surface of an inked intaglio plate, comprising:

1. an elongated web movable longitudinally;

2. a pad for holding a portion of the web against the surface of the rotating cylinder;

3. means for guiding the web between said pad and the cylinder; and

4. means for controlling the lateral position of the web, comprising:

i. two edge sensing means;

ii. means supporting said two edge sensing means at the opposite edges of said web;

iii. two motors, each controlled by one of said edge sensing means;

iv. two fixed guide means extending across and engaging the web and spaced longitudinally of the web, said two guide means defining a straight run for the web;

v. third guide means extending across and spaced from but movable into engagement with the web between the two fixed guide means; and

vi. means controlled by each said motor for moving one end of the third guide means into engagement with the web so that each motor is effective upon operation thereof to change the length of the path traversed by one edge of the web as compared to the length of the path traversed by the other edge.

2. A printing press as in claim 1, including means on the pad supporting said two edge sensing means.

3. A printing press as in claim 1, including:

a. two pairs of fixed guide means, one pair engaging one side of the moving web upstream from the pad and the other pair engaging one side of the moving web downstream from the pad;

b. two movable guide means, one operable to engage the web upstream from the pad and one operable to engage the web downstream from the pad, each movable guide means being operable to engage the web between one pair of said fixed guide means;

c. means operated by each motor to move one end of both the upstream and downstream movable guide means.

4. A printing press as in claim 1, including:

a. means for oscillating the pad parallel to the axis of the plate cylinder; and

b. means on the pad for supporting said edge sensing means.