Abstract:
A draw frame for drafting a sliver includes a drafting unit having a plurality of roll assemblies spaced from one another in a direction of sliver advance. One of the roll assemblies is an output roll assembly situated at a downstream end of the drafting unit as viewed in the direction of sliver advance. A sliver guide is disposed downstream of the output roll assembly and a sliver trumpet is disposed downstream of the sliver guide. The sliver passes through the sliver guide and the sliver trumpet. An electronic camera is arranged to capture images of the sliver at a location which is downstream of the output roll assembly and upstream of the sliver trumpet. An electronic image evaluating unit is connected to the camera for receiving image signals therefrom.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the priority of German Application No. 100 60 227.4 filed Dec. 4, 2000, which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to a quality sensing device arranged at the output of a draw frame. The sliver, as it emerges from the output roll assembly of the drafting unit, passes through a sliver guide and a sliver trumpet, and the quality of the sliver may be measured.  
           [0003]    In practice the quality of the drafted sliver is analyzed by examining the finished sliver outputted by the draw frame. The quality of the sliver, particularly the CV value of the mass uniformity, the mixture ratio and the sliver number is measured as the sliver passes through the sliver trumpet. In this arrangement a determination of, for example, the sliver mass deviations may be made only as related to the entire cross section of the sliver.  
         SUMMARY OF THE INVENTION  
         [0004]    It is an object of the invention to provide an improved apparatus of the above-outlined type from which the discussed disadvantage is eliminated and which, in particular, makes possible a more accurate capture and measurement of further characteristics of the sliver and/or of its material.  
           [0005]    This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the draw frame for drafting a sliver includes a drafting unit having a plurality of roll assemblies spaced from one another in a direction of sliver advance. One of the roll assemblies is an output roll assembly situated at a downstream end of the drafting unit as viewed in the direction of sliver advance. A sliver guide is disposed downstream of the output roll assembly and a sliver trumpet is disposed downstream of the sliver guide. The sliver passes through the sliver guide and the sliver trumpet. An electronic camera is arranged to capture images of the sliver at a location which is downstream of the output roll assembly and upstream of the sliver trumpet. An electronic image evaluating unit is connected to the camera for receiving image signals therefrom.  
           [0006]    The measures according to the invention make possible a more accurate quality determination of the sliver. In particular, the wider shape of the sliver prior to densifying the sliver in the sliver trumpet provides an access to details by virtue of capturing sliver images. It is a particular advantage of the invention that dependent on the resolution, an individual fiber evaluation (examination of fiber hooklets), a determination of fiber imperfections, examination of larger surfaces (for cloudiness) and judging a sliver bundle composed of several slivers as a whole is possible. The evaluated results derived from the image processing may be utilized for an optimal setting of the draw frame. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a schematic side elevational view of a drafting unit of a draw frame incorporating the invention.  
         [0008]    [0008]FIG. 2 is a view similar to FIG. 1, showing the construction according to the invention disposed in the region of the sliver guide.  
         [0009]    [0009]FIG. 3 a  is a sectional top plan view of the sliver guide.  
         [0010]    [0010]FIG. 3 b  is a front elevational view of the sliver guide.  
         [0011]    [0011]FIG. 4 is a schematic side elevational view, with block diagram, of a draw frame, incorporating the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    [0012]FIG. 1 illustrates a drafting unit  1  of a draw frame which may be, for example, an HSR model manufactured by Trtitzschler GmbH &amp; Co. KG, Mönchengladbach, Germany. The slivers  2  (only one is visible in FIG. 1) are withdrawn from coiler cans and together enter the drafting unit after passing through a sensor  28  (FIG. 4).  
         [0013]    The drafting unit  1  is a 4-over-3 construction, that is, it has a lower output roll I, a lower middle roll II and a lower input roll III as well as four upper rolls  3 ,  4 ,  5  and  6 . The drafting of the sliver  2  in the drafting unit  1  occurs in a preliminary drafting field formed by the roll pairs  6 , III and  5 , II as well as a principal drafting field formed by the roll pair  5 , II and the roll assembly  3 ,  4  and I. The drafted slivers, designated at  14 , reach a sliver guide  7  and are, by means of calender rolls  8  and  9 , pulled through a sliver trumpet  10  in which the slivers are combined into a single sliver  11  which is subsequently deposited by a sliver coiler  12  into a coiler can not shown. Between the output rolls  3 , I of the draw unit  1  and the input opening  7   a  of the sliver guide  7  a CCD-camera  15  is disposed which is connected with an electronic evaluating device  16  (image processing unit) which, in turn, is coupled to an electronic control and regulating device  38  as shown in FIG. 4.  
         [0014]    Turning to FIGS. 2, 3 a  and  3   b , the sliver guide  7  has top and bottom walls  7   e  and  7   f  provided, respectively, with a light transmitting window  17  and  18 . Externally of the top wall  7   e  and facing the window  17 , the CCD-camera  15  as well as two light emitting diodes (LED&#39;s)  19  and  20  are arranged. Spaced from the bottom wall  7 f a light emitting diode  21  faces the window  18 . By virtue of this arrangement the sliver  14  entering the inner space  7 ′ of the sliver guide  7  is optically captured between the inlet opening  7   a  and the outlet opening  7   b . The optical axis of the camera  15  is oriented perpendicularly to the advancing direction B of the sliver  14  within the sliver guide  7 . The walls  7   e  and  7   f  may be pivoted open; the picture-taking occurs through the windows  17  and  18  while the walls  7   e  and  7   f  of the sliver guide  7  are in a closed position. By arranging the light diodes  19 ,  20  on the one hand, and the light diode  21 , on the other hand, at opposite sides of the sliver guide  7 , pictures in transmitted light and reflected light may be taken. The picture taking occurs both during the normal delivery speed (900 m/min and above) and during acceleration and deceleration of the sliver  14 . The sliver guide  7  has an open end  7   a  which is its input and a sliver passage opening  7   b  which is its output. The inner space  7 ′ of the sliver guide  7  is defined by two concavely converging side walls  7   c  and  7   d  as well as the planar top wall  7   e  and the planar bottom wall  7   f.  The inlet opening  7   a  has a larger area than the sliver passage opening  7   b . The passage opening  7   b  is adjoined by transfer tubes  22  and  23  which guide the gathered sliver  14  into the sliver trumpet  10  shown in FIGS. 1 and 4.  
         [0015]    During operation, the sliver  14  discharged by the roll pair  3 , I enters the inner space  7 ′ of the sliver guide  7  through the inlet opening  7   a . Then the sliver impacts on the inner faces  7   c  and is gathered thereby and guided to the outlet opening  7   b . During this occurrence the sliver  14  is densified while air is expelled therefrom which escapes into the ambient atmosphere in the direction of the arrows C and D through the inlet opening  7   a  in a direction against the advancing direction B.  
         [0016]    Turning to FIG. 4, the drafting unit  1  is preceded by a drafting unit inlet  24  and is followed by a drafting unit outlet  25 . The slivers  2  are, pulled by the calender rolls  26 ,  27 , moved through the measuring member  28 . In the drafting unit outlet  25  the drafted slivers  14  reach the sliver guide  7  and are, by means of the calender rolls  8  and  9 , pulled through the sliver trumpet  10  in which the slivers  14  are combined into a single sliver  11 , subsequently deposited in coiler cans.  
         [0017]    The calender rolls  15 ,  16 , the lower input roll III and the lower mid roll II which are mechanically connected to one another, for example, by a toothed belt, are driven by a regulating motor  31 , while the respective upper rolls  6  and  5  are idlers driven by friction from the respective lower rolls. The regulating motor  31  receives a desired rpm value. The lower output roll I and the calender rolls  8  and  9  are driven by a principal motor  32 . The regulating motor  31  and the principal motor  32  have a respective regulator  33  and  34 . The rpm regulation is effected by means of a closed regulating circuit in which the regulating motor  31  and the principal motor  32  are provided with a respective tachogenerator  35  and  36 . At the drafting unit inlet  24  a mass-proportional magnitude, for example, the sliver cross section of the slivers  2  are measured by the inlet measuring member  28 . At the drafting unit outlet  25  the cross section of the exiting sliver  11  is sensed by an outlet measuring organ  37  associated with the sliver trumpet  10 . The central computer unit (control and regulating device)  38 , for example, a microcomputer with a microprocessor, transfers the setting of the desired magnitude for the regulating motor  31  to the regulator  33 . The measured magnitudes sensed by the measuring member  28  are applied to the central unit  38  during the drafting process. From the measured magnitudes sensed by the measuring member  28  and the desired value for the cross section of the exiting sliver  11  in the central unit  38  the setting magnitude for the regulating motor  31  is determined. The measured magnitudes sensed by the outlet measuring organ  37  serve for monitoring the exiting sliver  11 . By means of such a regulating system, fluctuations in the cross section of the inputted sliver  2  may be compensated for by a suitable regulation of the preliminary drafting process, that is, an evening of the outputted sliver  11  may be achieved. In the system illustrated in FIG. 4, 39 designates an inputting device and  16  schematically designates the image processing device, also shown in FIG. 1. The camera  15  is connected to the central unit  38  with the intermediary of the image processing device  16 . By means of this arrangement the results of the image analysis may be used in a closed regulating circuit for optimizing the drafting process. The results of the image analysis of the drafted sliver  14  may be stored in a memory  47 .  
         [0018]    By means of the CCD-camera  15  pictures may be taken of the drafted slivers  14 . It is also feasible to take pictures of the drafted slivers  14  by digitalized photodiodes. The evaluation of the digital image information may be performed on-line by an image analyzing software. The camera axis is oriented preferably perpendicularly to the traveling direction of the slivers  14  as they pass through the sliver guide  7 . The camera  15  may be moved along the inner frame width of the machine on rails to take pictures along the working width of the drawing frame. Expediently, the camera  15  may be moved automatically away from the slivers  14  or a wide-angle setting of the camera may be effected to capture the entire sliver width. It is also feasible to pivot the camera  15  about an axis  15 ″ in a plane perpendicular to the sliver advancing direction B to take pictures over the working width of the draw frame. Advantageously, pictures are taken in the middle sliver zone to examine the sliver for cloudiness. Grounds for such cloudiness may be an unsatisfactory short-fiber guidance, poor clamping of the sliver, or erroneous drafting unit settings. Further, pictures from such a sliver region may be used for analyzing the degree of parallelization of the slivers, the fiber hook number and size, the structural influence of the material and the generation of dust. Based on all these parameters, the quality of the drafting process may be determined. Advantageously, pictures are also taken especially of the edge zones for analyzing the guidance of the fibers in the edge zones during the drafting process (closed or discontinuous sliver image at the edges). By a width-wise scanning of the sliver by the camera it may also be determined whether longitudinally extending streaks are present in the sliver. Such streaks may appear if the slivers are improperly guided into the drafting unit, that is, the slivers are overlapping or are at an excessive distance from one another. Based on the analysis of the entire sliver width, an evaluation of the initial draft in this region may be performed. It is a further advantage of the invention that the orientation of the slivers and fibers may be analyzed since the number and the position of the obliquely and straight-running slivers represent a measure for the effective starting draft. The starting draft of the calender roll pair is dependent from the following parameters: delivery speed, draft, friction, sliver number, material, soiling, and the like. In this manner the real starting draft of the calender roll pair may be objectively sensed. Images for the fiber orientation at an optimal starting draft may be stored in the control unit  38 . In particular, by means of a closed regulating circuit, the starting draft of the calender roll pair may be fully automatically or semi-automatically optimized (for example, by replacing the wheels manually).  
         [0019]    While the invention was described in connection with a regulated draw frame, it is to be understood that the invention may find application in a non-regulated draw frame as well.  
         [0020]    It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.