DE19709963A1 - Process for monitoring the production of flat material using a near infrared spectrometer and device for carrying out this process - Google Patents

Abstract

The invention relates to a method for monitoring the production of flat material (20) by means of a spectrometer (42) operating in the near-infrared range, said flat material (20) being transported in its longitudinal direction (22). A transverse bar (26) is positioned at a distance from the flat material (20), which transverse bar runs perpendicular to the longitudinal direction (22) and in which is arranged a large number of optic fibres (28). The first end area of these fibres is directed towards the flat material (20) in such a way that said end area captures the reflected light along a track (30) assigned to each end area, and that the optic fibres (28) transmit the detected light to a commutator (32) in which the second end areas of the individual optic fibres (28) are distributed uniformly and parallel to each other across an arc of a circle, in an order which does not correspond to the order of the tracks (30). In said commutator (32), a transfer fibre (40) which guides the light to the spectrometer (42) is arranged on a turning arm (36) which turns around the centre of the arc of circle and in this way brings the transfer fibre (40) into optical contact with one individual optic fibre (28) after another.

Description

The invention relates to a method for monitoring the product tion of flat material and a pre-working according to this process direction. It is particularly suitable for online process control the continuous production of flat goods such as paper, textiles, Films, etc. Most process chemicals can be handled by the device can be recorded chemically specific. This way you can also quickly most processing, such as B. in papermaking and printing be followed with sufficient precision. The device is suitable there forth in all continuous production processes, where one or several ingredients determine the quality. It is therefore on Wed. shearing, calendering, foulards, squeegees, dampers and dryers installed, components, additives, product orders for coating, impregnation, Laminate and regulate the moisture content when drying more constant can.

Methods and devices of the type mentioned are known. So it is known, for example, to attach an optical fiber to the traverse order, which is moved back and forth by motor, so that the Bahn Flachma material, which is located under the traverse, queried zigzag becomes. However, such mechanical movements are disadvantageous.

The invention has set itself the task of a method and a To specify and develop a device of the type mentioned in the introduction, that the sheet material along a large number of parallel to  Transport direction traces that z. B. at intervals of some Centimeters are provided, is observed and all tracks in succession which is queried, i.e. its information is sent to the spectrometer, whereby during the query not the tracks in their order on the Traverse, but in a clearly different order be tested.

This object is achieved procedurally by a method for monitoring the production of flat material by means of a spectrometer operating in the near infrared, to which light is diffusely reflected via a fiber optic from the flat material, the flat material being transported in its longitudinal direction and at a distance from the flat material a traverse is arranged, which is arranged transversely to the longitudinal direction and in which a larger number of optical fibers are arranged with their first end region towards the flat material, so that the end regions of these optical fibers each receive reflected light along a track assigned to each end region and the optical fibers detected the Relay light to a switch,

• - The one after the other with each optical fiber for a period of time brings at least one transfer fiber into optical contact, which the Light from the optical fiber that is temporarily assigned to it to the spotting scope trometer guides where it is recorded and then evaluated,
• - In which the second end regions of the individual optical fibers are parallel are evenly distributed on a circular arc in a Order that does not match the order of the tracks
• - In which the at least one transfer fiber is arranged on a rotating arm which is rotated around the center of the circular arc and an endbe the transfer fiber gradually extends from the second end region of a light fiber to the second end of the adjacent fiber moves and the transfer fiber with the single optical fiber afterwards brings others into optical contact and
• - In which the transfer fiber is kept freely rotatable, so that despite Dre is twisted as little as possible.

In terms of the device, it is solved by a device for carrying out the method according to claim 1 for monitoring the production of flat material with a spectrometer operating in the near infrared, with a fiber optic which feeds light diffusely reflected from the flat material to the spectrometer, with a traverse which in Distance from the flat material transported in its longitudinal direction is arranged, the flat material extends across this longitudinal direction and in which a larger number of optical fibers are each arranged with their first end region so that the free ends are directed towards the flat material and light along one of them record the assigned track with a switch,

• - In which the second end regions of the optical fibers are parallel to one another and evenly distributed along an arc in a stator are, with their free ends substantially in one plane and their order differs from the order of the tracks,
• - In which at least one transfer fiber is arranged with its one end region in an em rotating arm which has a axis of rotation running parallel to the second end regions and through the center of the circular arc, which holds this one end region so that it contacts one after the other in optical con individual optical fibers comes and is gradually driven ben, so that the optical contact between the transfer fiber and an optical fiber is maintained for a short period of time and
  with a rotary bearing that centrally receives the transfer fiber and keeps it freely rotatable so that it is twisted as little as possible despite the rotation of the rotating arm.

In this case, a spectrometer such as that used is advantageously used is for example described in PCT / DE 96/00662. It works with PbS photoconductors.

According to the invention, the second end regions of the optical fibers are open arranged in a circular arc and are rotated by the rotating arm, which is rotated step by step, each for a short, all light guidefa same period of time connected to the transfer fiber. The order  The fiber optics on the traverse is different from the order of the Transfer fibers on the circular arc. In particular, the arrangement is such that there are never two optical fibers that are directly attached to the traverse are adjacent, are also immediately adjacent on the arc. Ent Therefore, a small section of each one is always along the tracks Track used for surveillance, along the sheet and flat material the query jumps back and forth along the tracks. This will a much better query than with a zigzag back and forth Go there reached.

The more transfer fibers are used, the more often each comes in individual track. The transfer fibers are held mechanically so that they can rotate freely during the rotation of the swivel arm, i.e. itself not be murdered. Either the transfer fiber remains completely unused rotates, or a first section of the transfer fiber is rotated and with a second, unrotated section of the transfer fiber optically coupled.

Near infrared is the area above the visible light, that is understood from 0.8 microns to about 2.5 microns, especially the Range 1.2 to 2.3 microns. As fibers for optical fibers and Transfer fibers will use water-free quartz fibers with a quartz coating det. They have as few OH bands as possible in the near infrared. she also have sufficient mechanical stability. You are an individual sern, the diameter is z. B. 60 microns

Further advantages and features of the invention result from the others Claims and the following description of non-limiting to understand exemplary embodiments that with reference to the Drawing will be explained in more detail. In this show:

Fig. 1 is a schematic representation of the method steps and apparatus according to the invention,

Fig. 2 is a plan view of a portion of a stator of a changeover switch,

Fig. 3 is a Fig. 2 corresponding bottom view of a rotary arm,

Fig. 4 is a partial axial sectional view through a switch to explain the arrangement of the transfer fiber and

Fig. 5 is an illustration corresponding to Fig. 4 for another embodiment of the arrangement of the transfer fiber.

As shown in Fig. 1, a web of flat material 20 , here for example a few meters, z. B. three meters, wide paper web, along a longitudinal direction 22 , which can also be referred to as the conveying direction, transported at high speed, for example several meters per second. The flat material 20 runs along a freely rotatable or rotationally driven roller 24 . In the immediate vicinity of this roller 24 , a cross member 26 is arranged, which he stretches across the entire width of the flat material 20 and in which a plurality of optical fibers 28 are arranged so that their in the area of the cross member 26 first end regions with their free ends Flat material 20 are directed and from there take diffusely reflected light from a lighting source, not shown. The free ends of these optical fibers 28 are equally spaced over the crossmember, for example at a distance of a few centimeters, for. B. 5 cm arranged. Accordingly, is observed with each individual optical fiber along a track 30 which is parallel to the longitudinal direction 22 . In Fig. 1, lanes 1, 2, 3, 4, 5 are. . . (n-1) and n indicated. These traces 30 are of course only present in thought, they are not visible.

The total of n light guide fibers 28 are bundled from the cross member 26 to a switch 32 . Your second end areas are arranged on a stator 34 of this switch 32 evenly distributed on a circular arc. The free ends of these second end regions lie as precisely as possible in a plane that runs parallel to the surface of the stator 34 . They protrude as little as possible, e.g. B. a maximum of 1 mm, in front of the surface of the stator 34 . They are held in a known manner in sockets 51 which allow them to be precisely positioned and, in an improved version, also to be adjusted locally in the plane of the stator.

The order in which the second end regions of the optical fibers 28 are arranged along the circular arc on the stator 34 is on the one hand significantly different from the order of the tracks 30 and on the other hand deliberately different. In a preferred embodiment, two light guide fibers 28 , which are directly adjacent to the stator 34, are assigned clearly different tracks in the traverse 26 . At n = 60 Lichtlei terfaser 28 z. B. the typical jumps at least 10, typically at least 20 tracks. If the flat material is three meters wide, the tracks 30 are in this case at a distance of 5 cm from one another.

A rotating arm 36 is directly assigned to the stator 34 , this rotating arm rotates step by step around an axis of rotation 38 which is perpendicular to the plane of the circular arc and runs through the center thereof. An end region of a transfer fiber 40 is held on the rotating arm at a center distance that corresponds exactly to the radius of the circular arc in such a way that it can be brought into alignment with the individual second end regions of the optical fibers 28 as tightly and as flush as possible, i.e. an optical, contactless contact the best possible quality between each individual fiber fiber 28 and the transfer fiber 40 can be produced. Accordingly, the distance between the free end of the transfer fiber and the free ends of the optical fibers 28 is chosen to be as small as possible. The second end regions of the optical fibers 28 and also the mentioned end region of the transfer fiber 40 are parallel to one another and parallel to the axis of rotation 38 . The transfer fiber 40 has the task of feeding the optical information obtained from the individual optical fiber fibers 28 to a spectrometer 42 . There, the spectrum is recorded and evaluated in a manner known per se and the result is used for production control.

The rotating arm 36 rotates in steps, for this purpose it is, for example, with a continuously rotating drive motor via a suitable mechanical device, for. B. Maltese transmission, connected, or the motor itself is a stepper motor, either from home or is operated by a control electronics as a stepper motor. Maltese transmissions are known per se, they are used, for example, in film recording and playback devices in order to move a film jerkily in the image plane.

Stepper motors are known for example for clock drives and other Stellauf tasks. Also suitable for the invention are motors which rotate continuously per se, but are stopped and positioned in the individual angular positions of the optical fibers 28 by means of electronics, which will be discussed later, in such a way that the best possible match between the individual optical fibers 28 and the transfer fiber 40 is reached.

In FIGS. 2 and 3 on the stator 34 and the rotary arm 36 is shown not only the circular arc on which the free second end regions che of the optical fibers 28 and the free end of the transfer fiber find 40 be, but in the embodiment shown, outside of this circle, point-shaped light sources are also arranged on a circular arc 44 exactly on the same radii as the individual light guide fibers 28 . There are as many light sources 46 as optical fibers 28 are provided. It is particularly advantageous to make the light sources 46 adjustable, at least adjustable in the circumferential direction. The punctiform light sources 46 can be formed, for example, by very small holes that are illuminated from the outside by a common illuminant, for example a tungsten lamp. On the rotary arm 36 is in an Ab from the axis of rotation 38 , which corresponds to the radius of the circular arc 44 , an optical receiver arrangement 48 is provided, which can receive and evaluate the light source 46 from the light. It is followed by electronics that are connected to the motor 49 . The opti cal receiver arrangement is, for example, elongated in the circumferential direction or consists of several individual optical receivers. The optical receiver arrangement 48 is designed such that when the rotary arm is rotated, a signal from a light source 46 is already recorded before the transfer fiber 40 and the optical fiber 28 associated with the light source 46 are in agreement. If this match is achieved, however, the optical receiver arrangement emits a special signal, for example a maximum signal. This makes it possible to determine the exact position of the optical fiber 28 with respect to the transfer fiber 40 via the optical receiver arrangement for each individual optical fiber 28 and to use the signals from the optical receiver arrangement 48 for controlling a motor 49 , which always precisely rotates for interrupts briefly when transfer fiber 40 and an optical fiber 28 are in optical contact.

The optical receiver arrangement 48 can also be implemented in another form, for example with a bar code disk. Then, however, the second end regions of the respective optical fibers 28 must be adjustable in such a way that they can be clearly assigned to a bar of the bar code disk.

In the exemplary embodiment according to FIG. 1, one end region of the Transferfa water 40 is rotatably supported in the rotary arm 36 . A bearing 50 is used for the rotary bearing which is as precise as possible and has low bearing friction, for example a needle bearing. An inner sleeve of such a bearing 50 comprises a jacket of the transfer fiber 40 and thus precisely fixes the transfer fiber 40 . The transfer fiber 40 is covered at least over part of its course by a flexible, non-rotatable jacket, in particular a tallwell hose 52, and is thus protected. The jacket preferably also takes on torsional forces. The transfer fiber 40 is bent as little as possible within the mechanically permissible radii of curvature; it is preferably fixed by means of a clamp 54 , which is located on the axis of rotation 38 and is stationary.

In the exemplary embodiment according to FIG. 5, the transfer fiber 40 is divided into two sections. A first section is mounted in a torsionally rigid manner in the rotating arm 36 , so there is no needle bearing provided there. For this, this first part is held at the location of the bracket 54 in a warehouse 50 . It is there in direct optical contact with a second section with the transfer fiber 40 , which closes the connection to the spectrometer 42 . In this embodiment, the first section of the transfer fiber 40 thus rotates with the rotary arm 36 , this is in contrast to the embodiment in which a bearing 50 is provided in the rotary arm 36 .

In the embodiments mentioned so far, the rotary arm 36 has only one transfer fiber 40 . This is not necessary, it can also use several transfer fibers, e.g. B. record 2, 3, etc. if it is trained ausgebil det. It is thereby select a symmetrical arrangement, beispielswei se at two transfer fibers 40 would enable them to 180 °, with three Transferfa fibers an offset of 120 ° choose etc.

The changeover switch 32 is arranged in a housing 56 . This is dust-tight and preferably also air-tight. All critical optical transitions in the area of the switch 32 are protected, in particular dust-protected. The housing 56 is for example with dry gas such. B. nitrogen, constantly flushed and kept under positive pressure or other suitable measures, such as a micro opening, are provided to prevent access to dust, humidity, etc. to prevent ver.

A particular advantage of the device according to the invention is that the changeover switch 32 can be arranged at a distance from the flat material 20 . Dust and the like accumulate repeatedly during production. Only the cross member 26 is in the immediate vicinity of the flat material 20 . Here it is advisable to constantly flush around the free first end regions of the optical fibers 28 with compressed air, compressed gas and the like, so that no dirt and the like can settle on the free ends.

Fig. 1 is still on each track more extended regions 58. These, which are only intended to clarify the measuring principle and are actually not visible, are intended to clarify that while they are traversing under the traverse 26 , the respective track is detected by the spectrometer 42 measuring technology. The drawing of Fig. 1 illustrates that a derar term area 48 of a track is very many tracks away from the subsequently or previously detected area of another track. In an advantageous embodiment, the jumps are at least half of the tracks greater than 1/10 of the total number of tracks, preferably greater than 1/6, in particular 1/5 and preferably 1/4 of the total number of tracks. As a result, the location on the flat material 20 , which is currently being detected by the spectrometer 52, jumps back and forth, which leads to a good detection of the entire width of the flat material 20 .

Claims (9)

1. A method for monitoring the production of flat material ( 20 ) by means of a spectrometer ( 42 ) operating in the near infrared, to which light which is diffusely reflected by the flat material ( 20 ) is fed via a fiber optic, the flat material ( 20 ) in its longitudinal direction ( 22 ) is transported and at a distance from the flat material ( 20 ) a traverse ( 26 ) is arranged, which runs transversely to the longitudinal direction ( 22 ) and in which a larger number of optical fibers ( 28 ) with its first end region towards the flat material ( 20 ) are arranged so that the end areas of these optical fibers ( 28 ) each receive reflected light along a track ( 30 ) assigned to each end area and the optical fibers ( 28 ) pass the detected light on to a changeover switch ( 30 ),

• - The successively each individual optical fiber ( 28 ) for a period of time with at least one transfer fiber ( 40 ) in optical contact, which directs the light of the light fiber ( 28 ) assigned to it at times to the spectrometer ( 42 ), where it detects and is then evaluated,
• - In which the second end regions of the individual optical fibers ( 28 ) are arranged parallel to one another on a circular arc, in an order that does not correspond to the order of the tracks ( 30 ),
• - In which the at least one transfer fiber ( 40 ) is arranged on a rotary arm ( 36 ) which is rotated around the center of the circular arc and an end region of the transfer fiber ( 40 ) step by step from the second end region of an optical fiber ( 28 ) to the second end region of the neighboring beard optical fiber ( 28 ) moves and the transfer fiber ( 40 ) with the individual optical fiber ( 28 ) successively in optical contact and
• - In which the transfer fiber ( 40 ) is freely rotatable so that it is twisted as little as possible despite the rotation of the rotating arm ( 36 ).

2. The method according to claim 1, characterized in that for at least at least half, preferably all n optical fibers ( 28 ) the following statement applies: the one optical fiber ( 28 ) on the switch ( 30 ) immediately adjacent fiber is on the cross member ( 26 ) at least n / 10 tracks ( 30 ), preferably at least n / 5 and in particular n / 4 tracks ( 30 ) removed. 3. Device for carrying out the method according to claim 1 for monitoring the production of flat material ( 20 ) with a spectrometer ( 42 ) operating in the near infrared, with a fiber optic which feeds the spectrometer ( 42 ) diffusely reflected light from the flat material ( 20 ) , with a crossbar (26) which is spaced from the transported in its longitudinal direction (22) of flat material (20) transversely to this longitudinal direction (22) engages over the flat material (20) and in which a larger number of optical fibers (28 ) are each arranged with their first end area so that the free ends are directed towards the flat material ( 20 ) and receive light along a track ( 30 ) assigned to them, with a changeover switch ( 30 ),

• - In which the second end regions of the optical fibers ( 28 ) are arranged parallel to one another and evenly distributed along a circular arc in a gate ( 34 ), their free ends lying essentially in one plane and their order being different from the order of the tracks ( 30 ) differentiates
• - In which at least one transfer fiber ( 40 ) is arranged with its one end region in a rotating arm ( 36 ) which has a rotation axis ( 38 ) which runs parallel to the second end regions and through the center of the circular arc and which holds this one end region in such a way that he successively comes into optical contact with the individual optical fibers ( 28 ) and is driven step by step, so that the optical contact between the transfer fiber ( 40 ) and an optical fiber ( 28 ) is maintained for a short period of time and
  with a rotary bearing ( 50 ) which centrally receives the transfer fiber ( 40 ) and keeps it freely rotatable so that it is twisted as little as possible despite the rotation of the rotary arm ( 36 ).

4. The device according to claim 1, characterized in that the trans ferfaser ( 40 ) at its one end region in the rotating arm ( 36 ) is rotatably gela gert. 5. The device according to claim 3, characterized in that the trans ferfaser ( 40 ) has a first section which is arranged in a coaxially with the axis of rotation ( 38 ) of the rotary arm ( 36 ) arranged pivot bearing ( 50 ) freely rotatable on this pivot bearing ends and is optically coupled there with a second, stationary section. 6. Device according to one of claims 3 to 5, characterized in that the transfer fiber ( 40 ) has a fiber sheath and that in the pivot bearing of the sheaths of the transfer fiber ( 40 ) is contained in a rigid sleeve. 7. The device according to claim 1, characterized in that the trans ferfaser ( 40 ) with a non-twistable, but flexible hose, in particular corrugated hose, for. B. metal shaft hose ( 52 ), with which it is preferably rotatably connected. 8. The method according to claim 3, characterized in that the number n of optical fibers ( 28 ) is greater than 20, preferably greater than 40 and in particular greater than 50. 9. The device according to claim 3, characterized in that the order switch ( 30 ) is arranged in a dustproof housing ( 56 ), which is preferably hermetically sealed.