METHOD AND APPARATUS FOR WEB TEAR MONITORING OF A MATERIAL WEB

Abstract

This invention relates to a method for web tear monitoring on a machine used for the production and/or treatment of a fiber material web, in particular a paper web or paperboard web, said machine being in particular a paper machine or coating machine on which the fiber material web is conveyed at a defined speed in its longitudinal direction along a defined path, wherein a web tear is detected by way of a light-emitting component and a light-receiving sensor in that light is emitted from the light-emitting component in the direction of the fiber material web to a defined target point and, given the presence of the fiber material web, is reflected and/or let through and/or directed in the target point to the light-receiving sensor. The light is emitted, either by a multiplicity of light-emitting components arranged side by side on a first side of the fiber material web or by one light-emitting component with a linear light source on the first side, in the direction of an assigned multiplicity of light-receiving sensors arranged side by side on a second side of the fiber material web opposite the first side such that a light array extending in the transverse direction of the fiber material web and over its entire width is formed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows an inventive apparatus arranged at an angle to a material web; and

FIG. 2 shows schematically the possible construction of the light-emitting components and light-receiving sensors in the form of a transmitter rail and a receiver rail such as they can be used on the embodiment in FIG. 1 for example.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIG. 1, there is shown a fiber material web 1, for example a paper web, which is moved horizontally in a corresponding machine, for example a paper machine (only two supports to the right and left of the paper web 1 are shown in extracts), in its longitudinal direction. The machine part can be a drying section or a part of a coating machine.

Using a multiplicity of light-emitting components 2 in the form of a transmitter rail which is arranged above the material web 1, a light array 4 is emitted obliquely downward through the material web 1 or through defect points or tear points therein to a multiplicity of light-receiving sensors 3, wherein the latter are constructed likewise in the form of a rail, namely a receiver rail, and arranged underneath the material web 1.

Owing to the acute angle a selected for the angle at which the light array 4 or the individual mutually parallel light rays, of which four are indicated here schematically, strike the material web 1, primarily on its surface, it is possible to construct the longitudinal extension of the transmitter rail and the receiver rail smaller by a multiple relative to the width of the material web 1. As can be seen, the light array 4, which in a lateral plan view has the form of a rectangle, nearly or completely covers the entire width in the transverse direction of the material web 1.

Alternatively it would be possible, of course, for the light-emitting components 2 or transmitter rail to be arranged horizontally above or below the material web 1 and then advantageously constructed with the same width as the material web 1, and for the light-receiving sensors 3 or receiver rail to be arranged in a corresponding embodiment on the opposite side.

Visible in FIG. 2 in somewhat greater detail are the light-emitting components 2 and light-receiving sensors 3 constructed in the form of rails. As can be seen, the transmitter rail includes a multiplicity of light-emitting components, for example transmitter diodes, which are arranged in regular intervals and aligned with each other in the longitudinal direction of the rail. The receiver rail has a construction which corresponds to the transmitter rail except that in place of each individual transmitter diode provision is made for a receiver diode as the light-receiving sensor.

Accordingly, the light array 4 is constructed by a multiplicity of parallel, bundled light rays which correspond in their number respectively to the number of light-emitting components 2 or transmitter diodes and light-receiving sensors 3 or receiver diodes.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A method for web tear monitoring on a machine used for at least one of the production and treatment of a fiber material web, the machine being one of a paper machine and a coating machine on which the fiber material web is conveyed at a defined speed in a longitudinal direction of the fiber material web along a defined path, said method comprising the steps of: detecting a web tear using at least one light-emitting component and at least one light-receiving sensor; andemitting light from said at least one light-emitting component in a direction of the fiber material web to a defined target point such that, given a presence of the fiber material web, light is at least one of reflected, let through, and directed in said target point to said at least one light-receiving sensor, said light being emitted, one of by a plurality of said light-emitting components arranged side-by-side on a first side of the material web and by one light-emitting component with a linear light source on said first side, in a direction of an assigned plurality of said light-receiving sensors arranged side-by-side on a second side of the material web opposite said first side such that a light array extending in a transverse direction of the fiber material web and over an entire width of the fiber material web is formed.

2. The method according to claim 1, wherein said light array is emitted at an acute angle onto one of two broad sides of the fiber material web.

3. The method according to claim 1, wherein said light array is emitted such that said light array forms, on a non-torn material web, a line extending perpendicular to a plurality of lateral edges of the fiber material web and over said entire width of the fiber material web.

4. The method according to claim 1, further comprising assigning to each said light-receiving sensor exactly one said light-emitting component which emits a light ray in a direction of said light-receiving sensor.

5. The method according to claim 4, wherein said light ray is a bundled light ray.

6. The method according to claim 4, further comprising assigning to said plurality of light-receiving sensors a recognition pattern which stipulates for each said light-receiving sensor a light intensity limit value which is compared with a light intensity actually detected by said light-receiving sensor, on the basis of which at least one of comparison warnings are issued and safety actions are taken on the machine.

7. The method according to claim 6, wherein said recognition pattern is programmed, using a control device, on the basis of a plurality of material web properties.

8. The method according to claim 7, wherein said recognition pattern is created automatically on the basis of entered said plurality of material web properties.

9. The method according to claim 8, wherein said entered plurality of material web properties includes at least one of a gsm substance and an intended use of the fiber material web.

10. The method according to claim 8, wherein said intensity of said light from one of said light-emitting component and said plurality of light-emitting components is adjusted in accordance with a light transmission of the fiber material web such that said assigned plurality of light-receiving sensors one of always and essentially always receives said emitted light with a result that said intensity of received said light is lower at least one of when there is material web in respective said target point assigned to respective said light-emitting component, according to a number of light passages through the fiber material web, and according to a density of the fiber material web than when no fiber material web is present.

11. An apparatus for web tear monitoring on a machine used for at least one of the production and treatment of a fiber material web, the machine being one of a paper machine and a coating machine on which the fiber material web is conveyed at a defined speed in a longitudinal direction of the fiber material web along a defined path, said apparatus comprising: at least one light-emitting component including one of one light-emitting component with a linear light source on a first side of the fiber material web and a plurality of said light-emitting components arranged side-by-side on said first side; andat least one light-receiving sensor which is assigned to said at least one light-emitting component in that light from said at least one light-emitting component is emitted in a direction of a defined target point and, given a presence of the fiber material web, is at least one of reflected, let through, and directed in said target point to said at least one light-receiving sensor, said at least one light-receiving sensor including a plurality of said light-receiving sensors which are positioned side-by-side on a second side of the fiber material web opposite said first side, said plurality of light-receiving sensors being assigned to one of said light-emitting component and said plurality of light-emitting components such that said light which is emitted from one of said light-emitting component and said plurality of light-emitting components in a direction of said assigned plurality of light-receiving sensors forms a light array extending in a transverse direction of the fiber material web and over an entire width of the fiber material web.

12. The apparatus according to claim 11, wherein one of said light-emitting component and said plurality of light-emitting components and said plurality of light-receiving sensors form a single-piece transmitter rail and a single-piece receiver rail, which oppose each other on opposite sides of the fiber material web such that a plurality of parallel light rays is emitted in the form of a grid-shaped light strip of constant width from said transmitter rail in a direction of said receiver rail.

13. The apparatus according to claim 12, wherein said plurality of parallel light rays are bundled light rays.

14. The apparatus according to claim 11, further comprising a control device connected to one of said light-emitting component and said plurality of light-emitting components and to said plurality of light-receiving sensors, said control device configured for controlling: a detection of a web tear using said at least one light-emitting component and said at least one light-receiving sensor; andan emission of light, one of by said plurality of light-emitting components arranged side-by-side on said first side of the fiber material web and by said one light-emitting component with said linear light source on said first side, in said direction of said assigned plurality of light-receiving sensors arranged side-by-side on said second side of the fiber material web opposite said first side such that said light array extending in said transverse direction of the fiber material web and over said entire width of the fiber material web is formed.

15. A machine which transports a fiber material web in a longitudinal direction thereof along a defined path, the machine being one of a paper machine and a coating machine, said machine comprising: an apparatus for web tear monitoring including: at least one light-emitting component including one of one light-emitting component with a linear light source on a first side of the fiber material web and a plurality of said light-emitting components arranged side-by-side on said first side; andat least one light-receiving sensor which is assigned to said at least one light-emitting component in that light from said at least one light-emitting component is emitted in a direction of a defined target point and, given a presence of the fiber material web, is at least one of reflected, let through, and directed in said target point to said at least one light-receiving sensor, said at least one light-receiving sensor including a plurality of said light-receiving sensors which are positioned side-by-side on a second side of the fiber material web opposite said first side, said plurality of light-receiving sensors being assigned to one of said light-emitting component and said plurality of light-emitting components such that said light which is emitted from one of said light-emitting component and said plurality of light-emitting components in a direction of said assigned plurality of light-receiving sensors forms a light array extending in a transverse direction of the material web and over an entire width of the fiber material web, one of said light-emitting component and said plurality of light-emitting components and said plurality of light-receiving sensors being arranged at an angle in relation to a surface of the fiber material web such that said light array is emitted at an acute angle onto one of two broad sides of the fiber material web.