Patent Publication Number: US-2007102121-A1

Title: Apparatus for cutting to length a tire tread band

Description:
The present application is a continuation-in-part of application Ser. No. 10/165,785, filed Jun. 7, 2002. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates to an apparatus for cutting to length a tread band or strip, which is to be subsequently built up onto a tire carcass.  
      A cut-to-length apparatus of the aforementioned type is disclosed in German patent application 100 38 471.4. In a cut-to-length apparatus of this type, the problem exists that the tread bands to be cut to length must invariably be manually measured in order to ensure that the tread bands are accommodated to the respective carcasses of differing diameters on which the tread bands will be laid. The measuring process can also be fraught with errors so that, in many instances, a follow-up control must be performed to ensure the necessary reliability. If a carcass is built up with a tread band which has too short a length, it is, for all practical purposes, not possible to insert a piece of a tread band without incurring a diminishment in quality.  
      Various processes have been proposed in order to simplify the cutting to length of tread bands. Thus, an apparatus is disclosed in EP-A1-587 650 which measures the extent of the tread band which has already passed by a stop. A disadvantage of this process is that the tread band, being a partially viscous mass, is deformed by this movement including, especially, the movement of the tread band in a curved manner—whereby the length of the tread band is also altered.  
      Until now, the cutting of tread bands had to be performed manually. The worker must memorize the form pattern at the beginning of the tread band, in order to execute the cut with the necessary length of the tread band at a position which corresponds most exactly to the same tire pattern. The tread band therefore is cut regularly at a determined amount shorter than the previously determined length, and this shortening of the tread band is equalized upon mounting on the carcass by a corresponding extension or length elongation. The tread band may never be longer than the previously determined required length of the tread band.  
      The quality of this type of cutting of the tread band is dependent on the experience and capability of the worker for positioning the pattern at the beginning of the tread band and to recognize a correspondingly matched pattern on the end to be cut. In practice, a tread band that was cut too short must be thrown away.  
     SUMMARY OF THE INVENTION  
      The present invention offers a solution to the challenge of providing an apparatus for cutting to length a tread band, which will be subsequently built up or laid upon a carcass, whereby the apparatus is characterized by improved reliability and permits a precise registration of the tread band length.  
      In accordance with the cut-to-length apparatus of the present invention, the length of the tread band is automatically detected, or registered and, at the same time, is accommodated to the manufacturing requirements. In this connection, a CCD camera can, for example, be deployed, with the camera being aimed at the cutting region for correspondingly capturing or registering the cut end of the tread band.  
      In accordance with the present invention, a detection, or registration of the extent of the tread band which has already passed a prescribed location is performed by a control apparatus, so that the transport of the tread band via, for example, a type of transport belt, can be captured or registered by an encoder. The desired tread band length, which corresponds to the circumference of the carcass on which the tread band is to be built up on, is now numerically transformed in the control apparatus of the picture displaying apparatus such that an appropriate tread band length is determined which will yield a direct connection between the front end thereof and the back end thereof. This corresponds substantially to the butt joint of a carcass, which has already been built or laid up.  
      The elongation of the tread band caused by the bending thereof to assume its carcass encircling form can also be compensated for via corresponding calibration, whereby a tread band having a very precise length which permits the build up of the tread band on a carcass with an optimum joint can be produced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Additional advantages, details, and features are set forth in the hereinafter following description of an embodiment of the tread band cut-to-length apparatus of the present invention taken in connection with the figures of the drawing, in which:  
       FIG. 1  is a schematic view of a tread band and the content of a picture display which displays a picture of the front end of a tread band, if the front end of a tread band has been cut, which is stored by the picture displaying apparatus of the present invention;  
       FIG. 2  is a schematic view of a tread band and the content of the picture display in an operating condition shortly before the desired length of the tread band has been reached at which location the back end of the tread band will be cut; and  
       FIG. 3  shows the image displayed on the right half of the display of  FIG. 2  rotated at 180°. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  is a representation of a picture or display  10  of a not-illustrated video capture apparatus for the cut-to-length apparatus of the present invention. The picture is captured or registered via a CCD camera, which captures the image of the region underneath a cutting device  12  that is operable to cut a tread band  14 . The cutting device  12  cuts the tread band  14  and, at the location of the cut, a picture is taken by the CCD camera and stored and displayed on the picture screen  10 .  
      The picture screen  10  is divided into a first portion  16  and a second portion  18 , which are respectively dedicated to the front and back ends of the tread band  14 .  
      As can be seen in  FIG. 1 , the picture of the cut tread band is shown in the first picture portion  16  in a 180 degree reversed position.  
      As seen in  FIG. 2 , the tread band  14  is transported via a transport device in the direction indicated by the arrow  20 . A dimension measuring device  22  measures the extent of the tread band which has been transported therepast. As soon as the desired end of the tread band has moved into the region of the cutting device  12 , a picture of this portion of the tread band is shown on the second picture portion  18  on the picture screen  10 . In this connection, the camera captures the picture of an area  24  of the tread band, which is an area of the tread band substantially bordering on the cutting device  12  lying just before and extending to the location on the tread band at which the cutting device will cut the tread band to create the back end thereof.  
      The transport device for transporting the tread band is controlled either through operator manipulation or automatically, such that the appropriate position for the actuation of the cutting device  12  is reached. The operator then views the movement of the tread band in the right-hand picture portion  18  on the picture screen  10 , and can, for example, undertake the cutting of the back end of the tread band if the two picture samples are congruent. In this connection, a separation line  26  is shown between the picture portions  16  and  18  at an appropriate location on the picture screen.  
      In accordance with a modification of the preferred embodiment of the cut-to-length apparatus of the present invention, it is provided that the cutting device is, as well, automatically actuable once the desired congruity is present.  
      According to a further modification of the preferred embodiment of the cut-to-length apparatus of the present invention, the picture screen is configured as a touch screen for permitting control of the transport device, whereby an operator intervention permits an immediate visual feedback.  
      According to yet another modification of the preferred embodiment of the cut-to-length apparatus of the present invention, it is provided that the position of the cutting device  12  can be re-adjusted in connection with the occurrence of shifting tread bands in order to make possible a fine or precise comparison, for example, via the touch screen.  
      The form pattern of the tread band to be mounted on the carcass should be advanced continuously to the abutting position of the front and back ends, in order to obtain an optimal retread tire. This requirement represents a primary quality feature of retread tires.  
      As described above, upon cutting of the front or forward end of the tread band or at its beginning, an image with the cutting edge  17  is produced, which displays the tire pattern directly at the beginning of the tread band. This image is shown rotated about 180° on a display device.  
      The previously determined, required length of the tread band, which is provided from the diameter of the carcass, is entered for controlling the device of the present invention. After the tread band is transported according to the length of this entered value, the control of the transport stops, and a second image is released, which now displays the end region of the tread band. The right edge of this image ( 30 ) represents therefore the maximum length of the tread band and the left edge of the image  28  represents the position on the tread band, which is provided from the maximum length less the width of the image region.  
      A tire pattern is repeated regularly at a specific distance on the tread band. The width of the image, in each case, must cover at least the distance in which the tire pattern is repeated once.  
      Both produced images are displayed on a display device  10 , for example, in the left half of the display screen  16 , the image rotated at 180° of the beginning of the tread band with the cutting edge  17  is shown, and in the right half  18 , the image of the end of the tread band is shown. By means of the illustration rotated at 180° of the left image, the representation of the pushing or advancement of the tread band is provided on the display screen at the separating line  26  of both images or image screen halves  16 ,  18 , as it is provided when the cut is to be performed at the position of the separating line  26 .  
      The operator now can scroll the correct image on the display screen  10  until the correspondingly matched pattern on the tread band end fits the tread band beginning  17 . This matching, or congruence, of the tire pattern on the display screen center  26  indicates where a cut is to be performed of a face of the tread band, at which point the tire pattern, without misalignment, runs further between the two abutting ends.  
      The scrolling on the display screen  10  is determined by the control, and the tread band  14  is transported according to the values determined in this manner. Upon reaching the cutting position, the control prompts cutting of the tread band by the cutting device  12 . Cutting of the tread band  14  takes place, then, exactly at the position that corresponds with the position of the separating band, or separating line  26 , in the display screen center.  
      If the displayed image of the last displayed image is rotated at 180°, as shown in  FIG. 3 , then the maximum length of the tread band  30  is located to the left in the right display screen half  18 . Scrolling of the displayed region of the tread band end on the display screen  10 , with the position  30  which corresponds with the maximum length of the tread band as shown in  FIG. 2 , would begin at a shorter tread band. Errors that occur in this manner can be effectively avoided, in that the operator immediately releases a cut at the first position, at which he found a congruence of the tire pattern according to  FIG. 3 , and a further cut approximately at the position  30  of the maximum length of the tread band.  
      The specification incorporates by reference the disclosure of German priority document 101 27 746.6 filed 8 Jun. 2001.  
      The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.