Patent Publication Number: US-2018050437-A1

Title: Structural Unit

Description:
This application is a divisional application of co-pending U.S. application Ser. No. 13/746,347, filed Jan. 22, 2013, which claims priority under 35 U.S.C. § 119 to patent application no. DE 10 2012 201 329.6, filed on Jan. 31, 2012 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     A structural unit, in particular a grinding wheel, having a hole pattern has already been proposed. There is already a multiplicity of grinding wheels with hole patterns, what are known as multihole grinding wheels, such as are known, for example, from patent specification EP 0 781 629 B1. 
     SUMMARY 
     A structural unit, in particular a grinding wheel, is proposed, having a hole pattern, in particular for sucking away swarf from a machining surface, with at least three recesses which are arranged at least essentially along a first spiral line, and with at least three further recesses which are arranged at least essentially along a second spiral line which intersects the first spiral line in the region of at least one recess. In this context, various structural units which seem expedient to a person skilled in the art may be envisaged such as, for example, brake disks or shower heads, but, in particular, a grinding wheel or a grinding plate are to be understood. In this case, a “grinding wheel” is to be understood, in particular, to mean a unit which forms the tool of a grinding machine, in particular of an eccentric grinding machine, and, during operation, is directly in contact with a workpiece for the removal of material. The unit preferably has at least one carrier layer and at least abrasive layer. The carrier layer is preferably composed of a paper, a foil, a fabric, a fiber or a combination. However, other materials which seem expedient to a person skilled in the art may also be envisaged. The abrasive layer preferably has granulation. Especially preferably, the unit is intended to be connected to a grinding plate via the carrier layer. In this context, a “grinding plate” is to be understood, in particular, to mean a unit of a grinding machine, in particular of an eccentric grinder, which is intended to receive a tool, in particular a grinding wheel. The grinding plate preferably has at least one main surface of extent which serves as a reception surface for the tool. Especially preferably, the grinding plate is driven by the grinding machine. Furthermore, in this context, a “hole pattern” is to be understood, in particular, to mean an arrangement of recesses. In this context, a “recess” is to be understood, in particular, to mean a through hole. It is preferably a round hole, but other hole shapes which seem expedient to a person skilled in the art may also be envisaged. Moreover, a “spiral line” is to be understood in this context to mean, in particular, a curve which runs around a spiral axis. Preferably, a spacing of points of the mapping with respect to the spiral axis changes strictly monotonically in relation to the angle. Especially preferably, mapping of the spiral line in a polar coordinate system can be differentiated at least simply continuously. Furthermore, “at least essentially” is to be understood in this context to mean, in particular, that a distance from a stipulated value, in particular a stipulated position, amounts, in particular, to less than 50%, preferably to less than 25% and especially preferably to less than 10% of a diameter of the recess. 
     An advantageous distribution of recesses can be achieved as a result of the configuration according to the disclosure of the structural unit having the hole pattern. 
     It is proposed, furthermore, that at least a large part of the recesses is arranged along spiral lines having in each case at least three recesses. In this context, “large part of the recesses” is to be understood, in particular, to mean at least more than 50%, preferably at least more than 70% and especially preferably at least more than 90% of the recesses. Advantageous surface utilization can be achieved by virtue of the configuration. Furthermore, uniform distribution can be achieved. 
     Moreover, it is proposed that at least a large part of the recesses is arranged at intersection points of the spiral lines. Uniform surface utilization can thereby advantageously be achieved. 
     Furthermore, it is proposed that the at least two spiral lines be contradirectional to one another with respect to a spiral axis of the spiral lines. Furthermore, in this context, “contradirectional” is to be understood, in particular, to mean that the spiral lines run around their spiral axes in opposite directions away from the respective starting points or toward the respective starting points. Especially advantageous distribution of the recesses can thereby be achieved. 
     Furthermore, it would be conceivable that the distances in each case from two recesses which succeed one another directly along a spiral line, in the case of at least a large part of the recesses, vary by less than 60%, especially preferably by less than 50%, from the maximum distance between two successive recesses. Especially uniform distribution of the recesses can thereby be achieved. 
     Moreover, it would be conceivable that the recesses which are arranged along the same spiral line are arranged in each case in an angular range of less than 360° along the respective spiral line. 
     It is proposed, further, that the contradirectional spiral lines differ from one another in their number. This is to be understood, in particular, to mean that a number of spirals which run in one direction is different from the number of spirals which are contradirectional with respect to these spirals. 
     What can advantageously be achieved thereby is that an asymmetric hole pattern with advantageous surface utilization and with advantageous surface distribution is achieved. 
     Moreover, it is proposed that the number of codirectional spiral lines and/or the number of contradirectional spiral lines correspond/corresponds to a number of the Fibonacci sequence. In this context, a “number of the Fibonacci sequence” is to be understood, in particular, to mean any positive number which is part of the general Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13, 21, . . . ). The sequence commences with the numbers 0 and 1, all further numbers being obtained by the addition of the two preceding numbers. Preferably, this is to be understood, in particular, to mean a number of the Fibonacci sequence which is greater than or equal to 3. Especially preferably, this is to be understood, in particular, to mean a number of the Fibonacci sequence which is greater than or equal to 8. 
     In particular, it is proposed that the number of codirectional spiral lines and the number of contradirectional spiral lines correspond to two successive numbers of the Fibonacci sequence. Especially preferably, the ratio of the two numbers to one another corresponds at least approximately to the golden section. In this context, “at least approximately” is to be understood to mean, in particular, that a deviation from a stipulated value amounts, in particular, to less than 10%, preferably to less than 5% and especially preferably to less than 2%. Furthermore, in this context, the “golden section” is to be understood, in particular, to mean a ratio φ. The ratio φ is given by 
     
       
         
           
             φ 
             = 
             
               
                 
                   1 
                   + 
                   
                     5 
                   
                 
                 2 
               
               ≈ 
               
                 1.618 
                 . 
               
             
           
         
       
     
     What can advantageously be achieved thereby is that the recesses are distributed uniformly on the surface and recesses can be prevented from lying directly one behind the other in the radial direction. 
     It is proposed, furthermore, that the at least one spiral line corresponds at least approximately to a Fibonacci spiral. In this context, a “Fibonacci spiral” is to be understood, in particular, to mean a spiral which is composed of quarter circles. Preferably, the sequence of the radii of the quarter circles corresponds to the Fibonacci sequence, and in this case the numbers of the Fibonacci sequence are to be understood to be unitless. Especially preferably, the quarter circles are placed one against the other so as always to be rotated through 90° with respect to one another. An especially uniform spiral line can thereby advantageously be achieved, as a result of which, in turn, advantageous surface distribution can be achieved. 
     Moreover, it is proposed that at least 50% of the recesses which are arranged along a spiral line have in each case a minimum spacing with respect to a center point which differs from all the minimum spacings with respect to the center point of recesses which are arranged along the two adjacent codirectional spiral lines, so that at least 50% of the recesses of one spiral line lie on radii which are related to the center point and which differ from radii on which the recesses of the adjacent spiral lines lie. Preferably, at least 70% of the recesses which are arranged along a spiral line have in each case a minimum spacing with respect to a center point which differs from all the minimum spacings with respect to the center point of recesses which are arranged along the two adjacent codirectional spiral lines. Especially preferably, at least 90% of the recesses which are arranged along a spiral line have in each case a minimum spacing with respect to a center point which differs from all the minimum spacings with respect to the center point of recesses which are arranged along the two adjacent codirectional spiral lines. In this case, a “center point” is to be understood in this context to mean, in particular, a center point of a main plane of extent of the structural unit. It would be conceivable, furthermore, that at least 50% of the recesses which are arranged along a spiral line have in each case a minimum spacing with respect to a center point which differs from all the minimum spacings with respect to the center point of recesses which are arranged along the two adjacent codirectional spiral lines and the spiral lines adjacent to the adjacent spiral lines. 
     The situation can thereby advantageously be prevented where at least a large number of recesses lies in the circumferential direction directly in the shadow, that is to say on the same radius with respect to the center point, of another recess, as a result of which, with a small fraction of holes, maximum coverage in the circumferential direction can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages appear from the following drawing description. The drawings illustrate two exemplary embodiments of the disclosure. The drawings and disclosure contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them into appropriate further combinations. 
         FIG. 1  shows a structural unit according to the disclosure with a hole pattern and with spiral lines in a diagrammatic illustration, and 
         FIG. 2  shows a system with the structural unit according to the disclosure and with an alternative structural unit according to the disclosure and a machining surface in a diagrammatic illustration. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a structural unit  10  according to the disclosure with a hole pattern  16  for sucking away swarf from a machining surface  18 . The structural unit  10  is formed by a grinding wheel  12 . Furthermore, the structural unit  10  has recesses  20  which are arranged essentially along a first spiral line  22 , and further recesses  24  which are arranged essentially along a second spiral line  26  which intersects the first spiral line  22  in the region of a recess  20 ,  24 . The recesses  20 ,  24  are formed by round holes. 
     All the recesses  20 ,  24 ,  28  of the structural unit  10  are arranged along spiral lines  22 ,  26 ,  30 ,  32  having in each case more than three recesses  20 ,  24 ,  28 . The recesses  20 ,  24 ,  28  of the structural unit  10  are arranged on intersection points of the spiral lines  22 ,  26 ,  30 ,  32 . The spiral lines  22 ,  26 ,  30 ,  32  have in each case a different orientation. The spiral lines  22 ,  26 ,  30 ,  32  have in each case an origin, not visible in any more detail, which is arranged in each case so as to be offset with respect to a center point  34  of the structural unit  10 . The origins of the spiral lines  22 ,  26 ,  30 ,  32  are arranged approximately on an elliptic ring, not visible in any more detail, the center point of which is arranged so as to be offset with respect to the center point  34  of the structural unit  10 . 
     The spiral lines  22 ,  26 ,  30 ,  32  are contradirectional to one another with respect to a spiral axis, not visible in any more detail, of the spiral lines  22 ,  26 ,  30 ,  32 . Some of the spiral lines  26 ,  32  run, in comparison with the rest of the spiral lines  22 ,  30 , in opposite directions around their spiral axes away from the respective origins or toward the respective origins. 
     The distances from in each case two recesses  20 ,  24 ,  28  which succeed one another directly along a spiral line  22 ,  26 ,  30 ,  32  vary, in the case of the recesses  20 ,  24 ,  28 , by less than 50% from the maximum distance between two successive recesses. 
     The recesses  20 ,  24 ,  28  which are arranged along the same spiral line  22 ,  26 ,  30 ,  32  are arranged in each case in an angular range of less than 360° along the respective spiral line  22 ,  26 ,  30 ,  32 . 
     The contradirectional spiral lines  22 ,  26 ,  30 ,  32  differ from one another in their number. A number of the spiral lines  22 ,  30  which run in each case in the same direction with respect to their specific orientation differs from a number of spiral lines  26 ,  32  which run in an opposite direction thereto. 
     The number of codirectional spiral lines  22 ,  30  and the number of contradirectional spiral lines  26 ,  32  corresponds to a number of the Fibonacci sequence. The number of codirectional spiral lines amounts to  34 . The number of contradirectional spiral lines amounts to  21 . The numbers of spiral lines  22 ,  26 ,  30 ,  32  correspond to successive numbers of the Fibonacci sequence. The ratio of the two numbers thus constitutes an approximation to the golden section. 
     The spiral lines  22 ,  26 ,  30 ,  32  correspond to Fibonacci spirals. The codirectional spiral lines  22 ,  30  and the contradirectional spiral lines  26 ,  32  are arranged in each case so as to be rotated and offset with respect to one another. The codirectional spiral lines  22 ,  30  are arranged in each case to be offset to one another and successive spiral lines  22 ,  30  are in each case rotated through approximately 10.59°. Furthermore, the contradirectional spiral lines  26 ,  32  are arranged in each case so as to be offset to one another and successive spiral lines  26 ,  32  are in each case rotated through approximately 17.14°. 
     The recesses  20 ,  24 ,  28  which are arranged along a spiral line  22 ,  26 ,  30 ,  32  have in each case a minimum spacing with respect to the center point  34  which differ from all the minimum spacings with respect to the center point  34  of recesses  20 ,  24 ,  28  which are arranged along the two adjacent codirectional spiral lines  22 ,  26 ,  30 ,  32 . Consequently, as seen in the circumferential direction about the center point  34  of the structural unit  10 , there is no recess  20 ,  24 ,  28  of the structural unit  10  which lies directly in the shadow of another recess  20 ,  24 ,  28 . After each recess  20 ,  24 ,  28 , a blank space lies on the successive spiral line  22 ,  26 ,  30 ,  32 , as seen in the circumferential direction. Furthermore, after a large part of the recesses  20 ,  24 ,  28 , a blank space lies on the two successive spiral lines  22 ,  26 ,  30 ,  32 , as seen in the circumferential direction. 
       FIG. 2  shows a system with the first and with a further example of the embodiment of the disclosure. The following descriptions and drawings are restricted essentially to a description of the combination of the exemplary embodiments. The set-up, as described above, can also be applied to the further exemplary embodiment, with the exception of the different configuration, particularly with regard to an arrangement of the recesses. It would also be conceivable, however, that the further exemplary embodiment has an alternative set-up according to the disclosure. 
       FIG. 2  shows a system  36  with the structural unit  10  according to the disclosure and with a structural unit  10 ′ according to the disclosure. The system  36  is formed by an eccentric grinder  38 . Furthermore, the structural unit  10 ′ is formed by a grinding plate  14 . The grinding plate  14  has recesses which are arranged correspondingly to the recesses  20 ,  24 ,  28  of the grinding wheel  12 . The grinding plate  14  is connected directly to a drive shaft, not visible in any more detail, of the eccentric grinder  38 . It would basically be conceivable however, also to have an alternative connection between the grinding plate  14  and a drive unit, not visible in any more detail, of the eccentric grinder  38 . The grinding wheel  12  and the grinding plate  14  are positively connected via connection elements, not visible in any more detail. The recesses  20 ,  24 ,  28  of the grinding wheel  12  preferably lie exactly on the recesses of the grinding plate  14 . Basically, however, an advantageous overlap of the recesses  20 ,  24 ,  28  can be achieved by means of the hole pattern  16  independently of an angular position of the grinding wheel  12  on the grinding plate  14 . The grinding wheel  12  has, on a side facing away from the grinding plate  14 , a grinding surface  40  with granulation. A machining surface  18  is arranged parallel to the grinding surface  40 .