CA2153709A1 - Bi-directional web guide - Google Patents

Abstract

This invention relates to the steering unit of a moving web, referred to as a web guide, that has a bi-directional capability.

In the guiding of a moving web, upon a paper printing press or converting machine, a steering unit is used to keep a reference edge constant to a predetermined position. A pivoted steering plate, mounted with idler rollers, is displaced by a linear actuator guiding the moving web in given direction.

In this invention, a single steering unit is described that has the ability to guide the web in both its forward or reverse direction.

A second steering plate is mounted upon the first. This plate has a pivot point opposite to the first steering plate, giving it the capability of steering in the reverse direction. A locking pin, in the form of a double ended cylinder is utilized to switch steering directions and utilize the same actuator.

Description

SPECIFICATION

This invention relates to a single web guiding unit to steer a moving web in either its forward or reverse direction of travel.

CONVENTIONAL DESIGN

Intermediate web guiding devices generally fall into two categories; offset pivot guide and, steering guide. The most popular design of web guides is the offset pivot type. This device is compact and maintains a high degree of lateral correcting accuracy.

A conventional offset pivot web guide unit, or tracking roller assembly, is built in such a fashion that the moving frame swings in an arc laterally, pivoting about a point located in the 10 entering web plane. The actuator is located at the opposite end of the frame (near the exiting web span), thus moving the web laterally back into the desired position as dictated by the edge sensor. The alignment of the material edge is measured electronically providing feedback to the control system.

Most paper converting machines and printing presses are single directional machines for which these web guides are sufficient. The recent development of bi-directional machines, with the ability to reverse the material in order to place faults during the inspection process or to repeat a process, has given rise for the need of a web guide unit steering in both directions.

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Previously this has been done by either putting two web guide units in tandem or not guiding in the reverse direction (single web guide is locked in its central position). Tandem web guides occupy a greater area of the machine and are twice the cost.

We have found that these disadvantages may be overcome by changing the mechanical configuration to enable to make use of two pivot points used for different web travel directions.
By incorporating a dual steering plate mechanism, with the ability to switch pivot points, a single web guiding unit can be used to steer the web in either the forward or reverse direction.
The design results in a single co",pact unit being used for web processing machines with full bi-directional capabilities.

The design follows the offset pivot type of web guide. The pivot point is the centre of rotation or swing of the steering plate. Conventional design requires this pivot point to be opposite the exit point of the web. The requirement is for the resulting arc movement to be at the point at which the web leaves the guide unit. The edge sensor is mounted at this location to measure the output.

In a bi-directional unit, there are two directions of travel, each one requiring a different pivot point and edge sensor. The new web guide has the ability to switch between two pivot points to reverse the direction of steering.

21$3709 DRAWINGS
In drawings which illustrate embodiments of the invention:

Title Description Figure 1.1 Overview A perspective view of the whole unit identifying key components Figure 1.2 Mechanical Configuration Sideviewof unit Figure 1.3 Plan View of Stationary Frame Top view of [5] stationary frame with key [5] components Figure 2.1 Forward Mode Side view of unit showing position, web direction and activated pivot whilst units is in its forward mode Figure 2.2 Forward Mode- Plan View Plan view of unit showing motion ofactuator cylinder[13], upper & lower frame [7] & [8] motion, cylinder [8]
position and effective pivot point.
Figure 3.1 Reverse Mode Side view of unit showing position, web direction and activated pivot whilst units is in its reverse mode Figure,Z'2 Reverse Mode- Plan View Plan view of unit showing motion oftl~tor cylinder[13], upper plate [7]
motion, cylinder [8] position and effective pivot point.

21~3709 List of System Components E i ' a ~ EDGE ~ E ~ SORS
1b STATIONARY FRAME

8 DOUBLE ENDED CYLINDER ' (locking device) UPPER FRAME GLIDE ROLLERS

A pair of idler rollers, [2] & [4], are fitted to the upper moving frame [7], to carry the web [3]
over the correcting axis. The upper moving frame [7] is mounted upon the lower moving frame [6]. The movement of the upper moving frame [7] is governed by the pivot pin [11 ] and a set ' The double ended cylinder [8] has been drawn offset in Figure 1.2 for clarification. Refer to Figure 1.3 for true location.
2 The bracket [14] connects the linear actuator [13] to the upper moving frame [7] to provide motion.

21537~9 of horizontal glide rollers or bearings [10], both of which are secured to the lower moving frame [6]. Motion comes from the linear actuator [13] and is connected to the upper moving frame [7] via a bracket [14]. This bracket [14] passes through the lower moving frame [6].

The lower moving frame [6] also employs a pivot pin [9] and a set of glide rollers [12] to achieve the required mechanical motion. Mounted upon the stationary frame [5], the lower moving frame [6] supports the upper moving frame [7] and also the double ended cylinder [8].

The linear actuator [13] can be in the form of a pneumatic cylinder, hydraulic cylinder or electric linear actuator. The double ended cylinder [8] can be a pneumatic cylinder or a solenoid type device.

The bi-directional capability is achieved by switching pivot points according to web direction.
The lower and upper frames [6] & [7] have dirrerenl pivot points [9] & [11 ] respectively. The frame which is moved is governed by the position of the double ended cylinder [8] which acts as a locking pin. This cylinder [8] either locks the upper frame [7] to the lower frame [6] or locks the lower frame [6] to the stationary frame [5]. A single linear actuator [13] is used to create the lateral arc movement in either the upper moving frame [7] or the upper and lower moving frames [6] & [7].

The upper frame's [7] movement is relative to the lower frame [6]. When the cylinder [13] is in the lower position, the lower frame [6] is secured to the stationary frame [5] and the upper 20 frame [7] moves independently of the lower frame [6] (see Figure 3.1). With the cylinder [8] in its up position, Figure 2.1, the lower and upper frame [6] & [7] become rigid and act as one plate. The lower frame's [6] motion is dependent upon the upper [7] and both are pivoted about [9].

FORWARD MODE

The web is travelling in its forward direction (left to right), refer to Figure 2.1. Edge sensor [1 a] on the right hand side of the web guide is activated; at the exit point of the web from the unit. The double ended cylinder [8] is in its 'up' position: the upper frame [7] is now locked onto the lower frame [6]. With the two moving frames [6] & [7] acting as one; the pivot point [9] for the two frames is on the stationary frame [5]. Displacement of the linear actuator [13]
10 causes the swing motion of the upper and lower frames [6] & [7], to occur at the exit point of the web as shown in Figure 2.2.

REVERSE MODE

The web is travelling in its reverse direction (from right to left), refer to Figure 3.1. Edge sensor [1 b] on the left hand side is activated; at the exit point of the web from the unit. The cylinder [8] is in its 'down' position: the upper frame [7] is now free to move independently of the lower frame [6] with the lower frame [6] locked onto the stationary frame [5]. Displacement of the linear actuator [13] causes the swing motion of the upper frame [7] only, to occur at the exit point of the web.

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CONTROL SYSTEM

The system must have the additional ability to electronically switch between the two edge sensors [1 a] & [1 b] in accordance to the web direction. Another output is also required for the double ended cylinder [8] which governs the directional mode.

PERFORMANCE

The advantage of the system is that only one unit is required upon the machine, providing a compact arrangement. Using a conventional web guide, two would be required in series to 10 achieve a bi-directional capability.

Only one linear actuator is required. The ~ctu~tor is mounted centrally about the steering plate as opposed to mounting at the exit point of the web, as in conventional designs. This arrangement reduces the mechanical advantage. An actuator with a larger thrust capacity would need to be used. The relationship between actuator displacement and arc movement or plate swing is greater, ie. a 1/4" movement of the actuator results in a 1/2" movement at the end of the steering plate.

The unit can be used in conjunction with different edge sensors. Single edge (outer or inner), centre guiding or electric eye line guiding can all be accommodated.

21537~9 In the drawings and specifications, there has been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not the purposes of limitation.

Claims

The embodiments of the invention for which an exclusive property or privelage is claimed is defined as follows:

(1) An automatic web guiding unit with the ability of steering in two directions of web travel, and the ability to automatically switch between the two modes using a stacked steering plate design each having its own pivot point.
(2) A unit as defined in claim 1, in which manual switching mode is employed.