Abstract:
A superfinish machine and a method for operating a superfinish machine are proposed, wherein monitoring an endless polishing band of the superfinish machine is possible.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional Application No. 61/083,522, filed on Jul. 25, 2008, the contents of which are incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present disclosure concerns superfinishing machines which operate with an endless polishing belt or band. Superfinishing is also known as short stroke honing. 
       BACKGROUND 
       [0003]    Superfinish machines which operate with an endless polishing belt are known. 
       SUMMARY 
       [0004]    The present disclosure enables an improved monitoring of the endless polishing band and at the same time minimizes the loss of endless polishing bands. 
         [0005]    This is attained with a superfinish machine having an endless polishing band, with a clamping apparatus for clamping the endless polishing band, with a transport apparatus for transporting the endless polishing band and with resources for monitoring the endless polishing band, wherein the resources for monitoring the endless polishing band may be an optical system. 
         [0006]    The term “optical system”, as used herein, is understood to include, in connection with this disclosure, optical sensors, including the subsequent evaluation of the output signals of the optical sensors. Examples of such optical systems are light barriers in which a sharply focused light beam is directed toward the endless polishing band, reflected from this, and the reflected light beam is recorded by, for example, a photodiode or several photodiodes and converted into an output signal. An image of the endless polishing band can, however, also be recorded and evaluated. Common to the optical systems is that they can distinguish between stoppage and motion of the endless polishing band. Some optical systems can, in addition, also ascertain the stretch traversed by the endless polishing band. The optical system can fall back upon products on the market, therefore, a detailed description of the mode of function will be dispensed with here. The “optical systems” mentioned below will be designated as light barriers for the sake of simplicity. 
         [0007]    By the use of optical systems, e.g. a light barrier, it is possible to record the motion of the endless polishing band. If the transport apparatus is active and at the same time the endless polishing band has not moved in reference to the position at which the light barrier is arranged, a recognition of a band tear is doubtlessly possible. This depends upon whether the torn band jams, takes an unanticipated path, or other unexpected situations arise. In this way, the recording of band tears becomes more error-free and, as a consequence thereof, subsequent damage due to band tears is significantly reduced. 
         [0008]    At least one light barrier may be is positioned at the beginning of the superfinish machine; that means, where the fresh endless polishing band is unwound from a roller and the real processing of the workpiece takes place between the light barrier and the transport apparatus. 
         [0009]    If at least one light barrier is constructed as a one-way light barrier, a compact and simple type of construction can be realized. Typical commercial one-way light barriers can be furnished with a diameter of twelve or eighteen millimeters as regular commercial products. Then, by screwing in such a one-way light barrier, the transmitter as well as the associated receiver are accommodated in one housing, which simplifies the mounting and of course also the wiring of the light barriers. Light barriers can also be used, however, where the light source and the receiver are arranged on different sides of the endless polishing band. 
         [0010]    The laser light of at least one light barrier, for example, with a wavelength of about 650 nanometers, is used as the light source. 
         [0011]    Laser light has the advantage that it furnishes a very thin light beam of less than 1.5 millimeter in diameter. In this way, it is possible to record even the smallest motions of the endless polishing band with certainty because even with the smallest motions of the endless polishing band, the reflection behavior of the endless polishing band changes. Furthermore, it is also possible to record the path the endless polishing band has traversed. As a result, additional monitoring or control and regulation functions of the superfinish machine are possible without engendering additional costs. 
         [0012]    Of course the the present disclosure is nonetheless not restricted to one-way laser light barriers, but other commercially available light barriers can be used which, for example, have one or more LED&#39;s as a light source. 
         [0013]    In order to be able to fix the endless polishing band in place while processing the workpiece and apply a defined tension on the endless polishing band in the region of the workpiece, a clamping apparatus is provided for the endless polishing band in a further aspect of the present disclosure. 
         [0014]    In another configuration, one or more known honing shells over which the endless polishing band is guided are provided between the clamping apparatus and the transport apparatus. 
         [0015]    Further provided is an endless polishing band for finishing machines with a front side and a reverse side, whereby the polishing resources are bound on the front side, wherein markings are arranged at regular intervals on the endless polishing band in the longitudinal direction of the endless polishing band. 
         [0016]    In this way, it is possible with the aid of a one-way light barrier to record the path which the endless polishing band has traversed. This is also possible when light sources other than laser light are used. The transport path of the endless polishing band can be ascertained from the change of output signals of the one-way light barriers which results when the light barrier records an alternating marking and an interstitial space between two markings. This presupposes that the separation of the markings from one another is known. Obviously, the exactitude with which the transport path of the endless polishing band can be recorded depends on the dimensions of the markings. 
         [0017]    It is also possible, with the aid of such inventive markings on the endless polishing band, to recognize the course of polishing of the endless polishing band. If, namely, the band deviates so far laterally out of the scanning range of the light barrier, there is no longer any change between light and dark sections and a corresponding error message can be issued to the control unit of the machine. 
         [0018]    The markings can be applied on the reverse side and/or the front side of the endless polishing band. In the case of light barriers with laser light as a light source, it is also possible to draw on the polishing means of the endless polishing band as markings. Furthermore, it is also possible to use the roughness of the polishing paper on the reverse side as a marking. 
         [0019]    In a further aspect, constructing the markings as openings in the endless polishing band is provided. Then it is also possible to use a light barrier in which the transmitter and the receiver are arranged on opposite sides of the endless polishing band. 
         [0020]    Further provided is a method for operating a superfinish machine with an endless polishing band, with a clamping device for the endless polishing band, with a transport apparatus for the endless polishing band and with at least one light barrier for monitoring the endless polishing band with which the workpiece is processed, in that the used section of the endless polishing band is replaced by an unused section of the endless polishing band after processing the workpiece, whereby the motion of the endless polishing band is recorded simultaneously by means of at least one light barrier and an error message is issued if the endless polishing band does not move although the transport apparatus is active. 
         [0021]    This method makes possible an error-free recording of band tears, since, regardless of what takes place between the light barrier and the transport apparatus with the torn endless polishing band, the endless polishing band can never be transported in the region of the light barrier by the transport apparatus arranged further behind, if the band is torn. 
         [0022]    Without additional hardware, the transport motion of the endless polishing band can be recorded with an intact endless polishing band. In this way, it is possible to regulate the transport of the endless polishing band, in that the transport device is shut off as soon as the expected feed of the endless polishing band is reached. The expected feed is established depending of the shape of the workpiece and the honing shells. The safety allowance when transporting the endless polishing band, and thus also the consumption of the endless polishing band, can be significantly reduced by means of the polishing band transport according to the present disclosure. In this way, the consumption of endless polishing bands can be reduced by 50% which is reflected in correspondingly diminished costs for the endless polishing band. 
         [0023]    Further features and forms of the present disclosure will be apparent, to one skilled in the art, from the following drawings, their description and the patent claims. 
         [0024]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0025]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0026]      FIG. 1  shows a schematic representation of a first aspect of a superfinish machine of the present disclosure; 
           [0027]      FIG. 2  shows another aspect of a superfinish machine of the present disclosure; 
           [0028]      FIG. 3  shows a section from an endless polishing band with markings applied in accordance with the disclosure; and 
           [0029]      FIG. 4  shows a flow chart of a method for operating a superfinish machine. 
       
    
    
       [0030]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION 
       [0031]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0032]      FIG. 1  shows a schematic side view of a superfinish machine of the present disclosure. The superfinish machine  1  of the present disclosure serves in connection with the aspect represented in  FIG. 1  for superfinishing a cylindrical workpiece  3 , such as for example, a bearing of a crankshaft. 
         [0033]    The fine processing of the workpiece  3  takes place with the aid of an endless polishing band  5  which is guided through a honing shell  7 . In the state represented in  FIG. 1 , the superfinish machine  1  and, as a consequence, also the endless polishing band  5  are not in engagement with the workpiece  3 . 
         [0034]    A clamping apparatus  9  and a light barrier  11  of the present disclosure are arranged above the honing shell  7  in  FIG. 1 . The endless polishing band is furthermore diverted by various rollers, until it is finally guided over a transport roller  13  beneath the honing shell  7 . 
         [0035]    In the area of the transport roller  13 , the endless polishing band  5  is pressed on the transport roller  13 . This can take place by means of a non-depicted contact drum. The transport roller  13  is activated in the aspect represented in  FIG. 1  through a tooth wheel  15  as well as a crank  17  with linear drive  19 . A not represented freewheel is present between the crank  17  and the toothed wheel  15 , so that the transport roller  13  can be transported as far as desired by repeated activation of the linear drive  19 . 
         [0036]    Naturally, it is also possible to provide an electric motor or another drive for the transport roller  13  instead of the drive described. 
         [0037]    The endless polishing band  5  first moves from above at the light barrier  11 , past the clamping device  9 , across the honing shell  7  and is then transported over the transport roller  13 . 
         [0038]    If the workpiece  3  is now to be processed, the clamping device  9  is activated, so that the endless polishing band  5  can no longer be tightened further. At the same time, the transport roller  13  is acted upon in the direction of transport with a predetermined torque, so that the endless polishing band  5  has a pre-stressing. In this state, the workpiece  3  and the superfinish machine  1  are moved toward each other. During the processing, the workpiece  3  is set into rotation and the endless polishing band  5  and the honing shell  7  execute an oscillating motion in one direction which runs perpendicular to the drawing plane. 
         [0039]    When the processing of the workpiece  3  is concluded, the superfinish machine and the workpiece  3  again move into the position represented in  FIG. 1 . After this, a new workpiece  3  is inserted and the endless polishing band  5  which is worn out and clogged by processing is replaced. This takes place in such a way, that the clamping apparatus  9  is opened and the transport roller  13  is rotated to a predetermined extent. 
         [0040]    At the same time, the light barrier  11  is activated in accordance with the present disclosure. If the endless polishing band  5  is not damaged, the endless polishing band  5  is passed by the light barrier  11  by a rotation of the transport wheel  13 , when the clamping apparatus  9  is open. This motion of the endless polishing band is detected by the light barrier  11 . 
         [0041]    The light barrier  11  operates in the depicted aspect with a laser light source and is directed toward the reverse side of the endless polishing band  5 . Due to the altered reflection behavior of the endless polishing band  5 , if it is brought into motion, the light barrier  11  issues a corresponding output signal to the non-depicted control unit of the superfinish machine. In this way, the control unit of the superfinish machine recognizes that the endless polishing band  5  is intact. 
         [0042]    In this case, the light barrier  11  of the present disclosure cannot furnish an output signal which contains information on whether the endless polishing band  5  is moving or standing, especially if it operates with a laser light source. It is rather also possible to ascertain the path which the endless polishing band  5  executes. This information can be used to regulate the feed of the endless polishing band  5 . Accordingly, the endless polishing band  5  is only fed by exactly the stretch until the honing shell  7  is once again covered completely by an unused, fresh, endless polishing band  5 . The processing of the next workpiece  3  can then take place. 
         [0043]    The recording of the transport of the endless polishing band  5  and the corresponding feedback or actuation of the transport roller  15  makes possible a considerable diminution of consumption in the polishing band, since the polishing band  5  can be completely used over its entire length. With conventional superfinish machines  1 , operations usually take place with a 10-50% safety allowance, since the band feed can only be controlled but not regulated. 
         [0044]    If the endless polishing band  5  should now be torn, then the endless polishing band  5  does not move past the light barrier  11 , despite the fact that the clamping apparatus  9  is open and the transport roller  13  is rotating. As a consequence thereof, the output signal of the light barrier  11  changes in relation to an intact endless polishing band  5  which is recognized by the control unit. Consequently, it is possible in to detect with certainty a torn endless polishing band  5  and to issue a corresponding error message, to issue a corresponding warning signal, and/or to stop the superfinish machine  1 . 
         [0045]    Another aspect of a superfinish machine of the present disclosure is represented in  FIG. 2 . Identical components are provided with the same reference numbers and what was stated with respect to  FIG. 1  correspondingly applies. The basic difference between the aspects in accordance with  FIGS. 1 and 2  consists in the fact that two honing shells  7 . 1  and  7 . 2  are used in the second aspect and the band guidance takes place in another manner. 
         [0046]    A section of the reverse side of an endless polishing band  5  of the present disclosure is represented in  FIG. 3 . Rectangular markings  21  are imprinted on the reverse side of the endless polishing band  5 . If now instead of a light barrier  11  with a laser light source, a light barrier  11  with, for example, an LED is used as a light source, it is possible likewise to monitor the transport of the endless polishing band  5  with the aid of the markings  21 . 
         [0047]    The light source of the non-depicted light barrier  11  is directed toward the markings here, so that during the transport of the endless polishing band  5  in its longitudinal direction a sequence of dark markings  21  and light interstitial spaces  23  are transported passing under the light barrier  11 . In this way it can first be determined whether the polishing band  5  is moving. By counting the markings  21  and/or the interstitial spaces  23 , it is moreover possible to ascertain the path on which the endless polishing band  5  is transported. The length of the markings LM and the length of the interstitial spaces  23  LZ are entered in  FIG. 3 . 
         [0048]    It is in addition also possible in connection with this aspect to record the guidance of the endless polishing band as well. Namely if the endless polishing band  5  deviates laterally, then the markings  21  wander out of the working range of the light barrier  11  (not depicted), so that the light barrier  11  also recognizes no sequence of dark markings  21  and light interstitial spaces  23  despite the transport of the endless polishing band  5 . As a consequence of this, the light barrier  11  issues an error message and the superfinish machine is stopped. 
         [0049]    A method in accordance with this disclosure is represented in  FIG. 4 . After the start, the clamping apparatus  9  is triggered in a first function block  25  and the transport apparatus is activated. This means that, for example, the transport roller  13  is actuated and being driven. 
         [0050]    In a second function block  27 , the motion of the endless polishing band  5  is recorded with the aid of the light barrier  11 . Subsequently, it is verified in block  29  whether the transport apparatus is active and whether at the same time the endless polishing band  5  is moving. If this query (“Y”) is positive, then the path on which the endless polishing band  5  is translated is recorded in a function block  31 . 
         [0051]    In another block  33 , it is compared whether the path of the endless polishing band  5  traversed is shorter than or equal to a predetermined target value. If the path of the endless polishing band  5  is greater than or equal to the target value, then the transport apparatus is shut off in function block  35 , and the process is concluded. 
         [0052]    As long as the query in block  33  is negative, that means, as long as the path of the endless polishing band  5  actually traversed is smaller than the target value, the program once again branches before function block  31  (recording the path of the endless polishing band). 
         [0053]    If a query in the function block  29  shows that the transport apparatus is active and the endless polishing band  5  is not moving, then an error message is issued in a function block  37 . This error message can then trigger an acoustic warning signal and/or lead to a shut-down of the superfinish machine  1  with the aid of the machine control unit. 
         [0054]    It should be noted that the disclosure is not limited to the forms described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the protection of the disclosure.