Abstract:
A device for aligning two machine shafts which are coupled to one another has:  
     at least one laser light source for emitting laser light;  
     at least one reflector for reflecting the laser light;  
     at least one receiving device for receiving the laser light;  
     a first arithmetic computing device for determining parallel and angular offset of the machine shafts; and  
     an evaluation and arithmetic computing device for determining the distance of the machine mounting elements relative to the plane of symmetry which lies between the machine shafts. The plane of symmetry intersects the axes of the machine shafts essentially perpendicular to longitudinal axes of the shafts, i.e. with an angular error of less than 6°.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a device for alignment of machine shafts.  
           [0003]    2. Description of Related Art  
           [0004]    A device for aligning machine shafts is known from U.S. Pat. No. 4,463,438, inventor Zatezalo. The device of this patent calls for the use of mechanical measurement means. Accordingly, the attainable accuracy in the alignment of machine shafts is limited and depends on various mechanical boundary conditions, for example, on the slack of the measurement means.  
           [0005]    A similar device with much improved accuracy is described in European Patent EP 0145745 of Lysen. Instead of mechanical measurement indicators, EP 0145745 calls for those based on a laser beam. In this way, the utility of shaft alignment instruments was radically enhanced. Overall, the microelectronics and measurement methods provided in each case enabled computer-aided, accurate and much more comfortable alignment of measurement shafts than had been possible in the past. However, to date, the innovative devices of this type have had the disadvantage that various activities must be performed manually before or after the actual measurement process. This relates especially to the input of various parameters, such as, for example, dimension data which must be input manually into the pertinent computer system. Another manual activity consists in manually converting the computed correction values, i.e., shifting or calibrating at least one machine in three directions of space, for which in part a certain expenditure of force is necessary. Although there are suggested solutions for the latter problem, so far there has not been any solution for automating and making more efficient the initial inputting of machine dimensions. This invention solves this special problem.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the invention, a device for aligning two machine shafts which are coupled to one another has:  
           [0007]    at least one laser light source for emitting laser light  
           [0008]    at least one reflector for reflecting the laser light  
           [0009]    at least one receiving device for receiving the laser light  
           [0010]    a first arithmetic means for determining parallel and angular offset of the machine shafts  
           [0011]    an evaluation and arithmetic means for determining the distance of the machine mounting elements relative to the plane of symmetry which lies between the machine shafts and which intersects the axes of the machine shafts essentially vertically.  
           [0012]    Typically, there are two separate laser light transmitting and receiving means, specifically, one for determining the amounts of offset on the shafts, and one for determining the distances of the machine mounting elements among one another or relative to a plane of symmetry which lies between the machine shafts. In one special embodiment of the invention, there is only a single laser light transmitting and receiving means which is used alternately for the indicated determinations of amounts and distances.  
           [0013]    Characteristic of the invention is the procedure of automatically supplying the electronically determined distances between the machine mounting elements to the computing process for determining the correction values with which the displacement values are computed using which optimum alignment of the participating machines and machine shafts can be achieved. Accordingly, it is possible to combine the indicated first arithmetic unit and the indicated evaluation and arithmetic means for determining the distance from the machine mounting elements in a single electronic circuit. This electronic circuit can be functionally connected to a single operating surface (as the output device) and a single input device. In this way, it is now possible to carry out the measurement process which was carried out manually in the past for determining dimensions with computer support, by which the inadvertent introduction of measurement error is clearly reduced and the alignment measure is simplified overall.  
           [0014]    The invention is suitable for use in alignment devices with different designs. These alignment devices can therefore provide a single laser beam for determining the amounts of shaft offset, or two separate laser beams.  
           [0015]    In the indicated determination of distances on an electronic basis, to some extent, triangulation processes or transit time measurements can be used. In transit time measurements, comparatively simple reflectors which are located on likewise simply designed stands can be used.  
           [0016]    The invention is explained in detail below with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view of a mobile device in accordance with the invention for automatic input of distance data into the shaft alignment system;  
         [0018]    [0018]FIG. 2 is a side view of two machines and a measurement means in a first measurement position;  
         [0019]    [0019]FIG. 3 is a side view of two machines and a measurement device in a second measurement position;  
         [0020]    [0020]FIG. 4 is a perspective view of temporarily mounted measurement means for automatic input of distance data into the shaft alignment system  
         [0021]    [0021]FIG. 5 is a view comparable to FIG. 4, the measurement means being located in a different measurement position  
         [0022]    [0022]FIG. 6 shows another embodiment of the invention with a symmetrically arranged reflector. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    As is shown in FIG. 1, the invention calls for optical measurement means, as described, for example, in U.S. Pat. No. 4,463,438, with which the distances are automatically recorded. Two machines  10 ,  20  can be installed in a desired position by means of bolts and nuts  14 ,  34 ,  36 , etc. on a mounting plane. To position the machines in the vertical direction, shims can be used, as are conventionally known, but are not identified in detail in the drawings. The shafts  12 ,  32  of the machines  10 ,  20  are dynamically connected by means of a coupling; their lengthwise axes should be coaxially identical to prevent wear and machine damage.  
         [0024]    In the preferred embodiment of the invention as shown in FIG. 1, there is a portable computer  50  with a input device  52  and a display  53 , and in its main function, it interrogates mechanical or optical measurement means (not shown in FIG. 1) for determining the translational and angular offset of the machines  10 ,  30 . From the measurement values which have been determined in this way, the desired correction data are computed, with which the machines can be moved into ideal position, if misalignment should be present. However, it is shown in FIG. 1 how the relevant machine dimensions are recorded by means of the computer  50 . To do this, there is an optically acting transmission and receiving means  54 . With it light beams  56  are sent to a reflector  42 . The light beams reflected by the reflector  42  are recorded by the receiving means. Either by means of transit time measurement or by triangulation, is it possible to determine the distance between the computer  50  and the reflector  42  in a relatively accurate manner.  
         [0025]    As shown in FIG. 1, the lengthwise axis of the computer  50  is aligned manually to the center plane of the coupling  20  since the important reference plane is defined by this center plane. Depending on the optical measurement processes used, the reflector  42  can be produced in different technology. Normally, it has diffuse reflection behavior so that its orientation relative to the computer  50  is not critical. To position the reflector  42 , there is a stand  40  of suitable length. The stand  40  can be equipped with magnetic foot  44 , but it can also be set up directly on the mounting plane which belongs to the machine. Therefore, the reflector  42  can be manually positioned such that the axis of symmetry of the stand  40  comes to rest parallel to the lengthwise axis of the nut  14  or of the respective bolt. After completed distance measurement (for which the computer  50  together with its transmitting and receiving means  54  is used), the reflector  42  can be moved from one measurement position into the next for subsequent measurement (c.f. FIGS. 2 &amp; 3). Typically, four such distance measurements can be taken and stored in the memory of the computer for further alignment measures.  
         [0026]    To take the distance measurement, the computer  50  has an input device  52  and a viewing screen  53 . The input device can be a conventional keyboard, or can be implemented by means of a single knob selection device. It is advantageous to equip the computer with a user interface on an alphanumeric, graphic or acoustic basis. The operator can execute the varied measurement tasks in succession in a convenient manner and depending on given or selectable partitions.  
         [0027]    [0027]FIG. 2 shows how the stand  40  is positioned above the mounting nut  16  for the measurement of the distance d″. In a comparable manner, FIG. 3 shows how the stand  40  is positioned above the mounting nut  14  which is assigned to the machine foot  18  for measurement of the distance d′. The computer software can be designed such that the optically determined distance d is automatically converted into the underlying distance d′ if this is necessary and the reflector  42  is not aligned to the mounting nut  14  anyway.  
         [0028]    [0028]FIG. 4 shows an alternative embodiment of the invention. Here, to measure distances, there is a light beam  56 ′ which is produced by a laser light source  60 . This light source can be the same as is used mainly for measuring the radial and angular offset of the shaft pieces  12 ,  32  (the pertinent receiving device or reflector not shown). Before the measurement data are recorded with respect to the amount of shaft offset, the laser light source, in interplay with the pertinent receiving device (not shown in FIGS. 4 &amp; 5), takes a distance measurement so that the pertinent distances between the center of the coupling and the mounting screws  14 ,  16  can be recorded, or equivalent dimensional data which differ by a constant. Therefore, pulsed light is sent to the reflector  42 , the reflected light is sensed with a high-speed photodetector, and based on the transit time, the distance to the reflector  42  is determined electronically. As shown, the laser light source  60  is temporarily mounted on the shaft  32  with a conventional clamping device  70 .  
         [0029]    After two first measurements with respect to the position of the mounting nuts  14 ,  16 , the laser light source  60  is re-clamped or changed and is then used for distance measurement with respect to the mounting nuts  34 ,  36 . This is shown, for example, in FIG. 5; the respective laser light beam is identified with reference number  56 ″.  
         [0030]    For the case in which a measurement system is used which works with two laser beams which work independently of one another, two laser light sources can thus be used. They can be turned against one another for purposes of distance measurement on their respective shaft pieces  12 ,  32  and then are used in interplay with not only an individual, but with respective separate reflectors  42 .  
         [0031]    [0031]FIG. 6 shows another embodiment of the invention which is characterized by a symmetrically located reflector  142 , which need not be changed or repositioned during the individual distance measurements. Preferably, reflector  142  has two reflection surfaces that are located back to back. Reflector  142  is arranged such that the two reflection surfaces essentially coincide with the central coupling plane which vertically intersects the axes of the participating machines. For this purpose, there is advantageously a magnetic holder  144  together with an associated stand rod. The stand rod can be advantageously lengthened or shortened in the manner of a telescope. However, also other stand arrangements can be used, for example, those which are set up on the floor of the building. As is shown in FIG. 6, the computer  50  is moved in the direction of a machine axis until its coordinate value in this respect agrees with that of the machine foot to be measured or the respective mounting screw or bolt. From this position, then, the distance between the computer  50  and the first reflection side of the reflector  142  is optically measured, as is illustrated by the indicated light beam  56 ″. This measurement process is repeated for the coordinates of interest.  
         [0032]    Measurement can be facilitated and can be carried out with better precision when the computer has a transmitter for a marking beam  156 . The light beams which produce this marking fix a plane which is oriented essentially perpendicular to the measurement beam  56 ″. As soon as the marking beam  156  illuminates, for example, the axis of the mounting screw  36  and the measurement beam  56 ″ can hit the reflector, the computer  50  is correctly positioned except for small residual errors.