Abstract:
The invention relates to a device ( 2 ) for grinding and/or finishing a workpiece ( 8 ) mounted on and/or in a workpiece mounting ( 22, 28 ). The workpiece ( 8 ) and the workpiece mounting ( 22, 28 ) may be set in an oscillating movement ( 86 ) by means of a drive device ( 60, 108 ) and form an oscillating unit ( 96 ) or part of an oscillating unit ( 96 ), at least one balancer unit ( 94 ) being provided which is driven to run counter to the oscillating movement ( 86 ) of the oscillating unit ( 96 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of International Application No. PCT/EP2006/004714 filed on May 18, 2006, which claims the benefit of EP 05 014 721.4, filed Jul. 7, 2005. The disclosures of the above applications are incorporated herein by reference. 

   FIELD 
   The invention relates to an apparatus for grinding and/or finishing a workpiece received on or in at least one workpiece mount. 
   BACKGROUND 
   The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
   An apparatus of for grinding and/or finishing can be used to produce workpiece surfaces of high and maximum quality, as the workpieces driven by oscillations are machined by means of grinding wheels, abrasive belts or grindstones and/or by means of finishing wheels, belts or stones. In order to achieve short machining time and/or maximum surface quality, workpieces often oscillate at high frequencies. 
   The known apparatuses are associated with the problem that strong vibrations occur at high oscillation frequencies, the vibrations being introduced in the apparatus for grinding and/or finishing a workpiece and ultimately in the environment of the apparatus. It is possible to configure the machine base in a particularly rigid and heavy manner in order to reduce the vibrations that are introduced in the environment of the apparatus. This, however, results in heavy and consequently difficult-to-manage and consequently expensive apparatuses. 
   From DE 200 06 229 U1 it is known to drive a workpiece by oscillations by means of a sleeve that is displaceable in the axial direction. However, such an apparatus shows the disadvantage that vibrations are introduced into the environment of the apparatus as well. This problem is encountered particularly with extremely heavy workpieces, so that with workpieces of this type, for example at an oscillation stroke of +/−1.0 mm, an oscillation frequency is reached which is limited to just a few 100 min −1 . 
   SUMMARY 
   The present disclosure provides an apparatus for grinding and/or finishing a workpiece received on or in at least one workpiece mount, the apparatus enabling high oscillation frequencies. 
   This is achieved according to the disclosure in that at least one balancing unit is provided, which can be driven in the opposite direction to that of the oscillating movement of the oscillating unit. 
   As a result of the balancing unit driven in the opposite direction to that of the oscillating movement of the oscillating unit, the inertia forces created by the oscillating movements of the workpiece and workpiece mount can be compensated for in that inertia forces acting in the opposite direction to said inertia forces are produced. Components, such as the machine base of the apparatus, adjacent to the oscillating unit and the balancing unit are decoupled from the vibrations. This in turn shows the advantage that vibrations in the environment of the apparatus are reduced as well. Thus, at an oscillation stroke of +/−1.0 mm, very high oscillation frequencies in the range of 1500 min −1  can be achieved. 
   According to an advantageous further development of the disclosure, the oscillating unit oscillates along a first axis and the balancing unit oscillates in a second axis that is parallel to the first axis. The parallelism of the axes provides that the inertia forces produced by the oscillating movements of the oscillating unit and balancing unit can be compensated for. The axes do not show to be configured physically; the axes are defined by the movements of the respective centers of gravity of the oscillating unit and balancing unit. 
   It is particularly advantageous if the first and second axes are coaxial to one another. In this way, the moments of inertia produced by the oscillating movements of the oscillating unit and of the balancing unit mutually compensate. This results in significantly reduced vibrations for the apparatus according to the disclosure and the environment thereof. 
   Compensation of forces and moments of inertia can be achieved particularly when the mass of the oscillating unit is equal to the mass of the balancing unit and when the oscillation stroke of the oscillating unit is equal to the oscillation stroke of the balancing unit. The oscillation stroke corresponds to the oscillation amplitude and amounts, for example, to several millimeters. It is also possible to compensate the inertia forces when the mass of the oscillating unit differs from the mass of the balancing unit. In this case, the oscillation strokes must be adjusted accordingly. For example, the mass of the oscillating unit is half of the mass of the balancing unit, wherein the oscillation stroke of the oscillating unit corresponds to double the oscillation stroke of the balancing unit. 
   The apparatus according to one form of the disclosure may comprise a headstock and/or a headstock support, a tailstock and/or a tailstock support and/or a rotational workpiece drive mechanism, wherein the above components may be part of the oscillating unit. It is therefore not necessary to minimize the mass of the oscillating unit, in fact, the above components can also oscillate together with the workpiece and the at least one workpiece mount. The appropriate compensation for the oscillating movements of an oscillating unit configured in this way can be provided by a balancing unit, whose stroke and/or mass are adjusted accordingly. 
   It is also possible to arrange the headstock and the tailstock on a common support, which is part of the oscillating unit. This is particularly advantageous for small workpieces. 
   Within the scope of the present disclosure, a workpiece mount shall be understood as a component that is suited to define the position and/or spatial position of a workpiece to be machined. Such a workpiece mount can be formed, for example, by a headstock support. It can also be provided as a workpiece mount that is configured as a tip or sleeve of a tailstock. For workpiece mounts of this type, it is advantageous to configure them such that they can be passively tracked in the direction of the workpiece, particularly if they are spring-actuated and/or piston-actuated. In this way, particularly oblong workpieces can be driven by oscillations at one end, while the other end can be passively tracked without requiring a further drive mechanism. 
   The balancing unit may comprise a balancing body. Said body can be made of, for example, a plurality of metal plates, which are detachably connected to one another. The balancing body advantageously shows fastening means for further masses. 
   If the balancing unit is provided with a balancing body support, the mass of the balancing unit can be adjusted particularly easily in that the balancing body, parts thereof or additional parts comprising masses are fastened to or on the support. 
   The balancing body and/or the headstock and/or the tailstock are advantageously guided in a linear fashion. The aforementioned components can thus oscillate freely in the longitudinal direction of the linear guide, thus ensuring that the components cannot build up any vibrations that are oriented transversely to the longitudinal axis of the guide. A linear guide is also suited for the balancing body support and/or the headstock support and/or the tailstock support and/or the common support for the headstock and tailstock in order to achieve the advantages mentioned above. In the case of linear guidance of the aforementioned supports, it is possible to adjust the apparatus to the geometry of a workpiece to be machined in an especially simple way, particularly to adjust the distance between the headstock and tailstock. 
   Even greater flexibility is achieved when the linear guide or the linear guides are provided on or in a sliding saddle, which is preferably mounted displaceable in relation to a machine base of the apparatus. 
   Within the scope of the present disclosure, it is possible that the drive mechanism, which causes the oscillating unit to oscillate, also drives the balancing unit. This shows the advantage that a further drive mechanism can be dispensed with, so that the apparatus shows fewer components in general. 
   For driving the balancing unit, however, an additional drive mechanism can also be provided, for example when high driving forces are required for particularly heavy workpieces. 
   One embodiment of the disclosure provides that the drive apparatus and/or the additional drive mechanism are configured as rotary drives. Particularly with such a rotary drive, the oscillating unit and/or the balancing unit can be driven by assigned connection rods, which are driven by common or different crank members. The crank members are provided with connection rod bearings offset eccentrically in relation to the axis of rotation of the crank member. The strokes of the oscillating unit and/or of the balancing unit are defined by the selection of the offset between the connection rod bearing and the axis of rotation of a crank member and by the length of the connection rod and the allocation thereof to the oscillating unit and/or balancing unit. 
   If a common crank member is provided for the different connection rods, which each drive the oscillating unit or balancing unit, a particularly simple drive mechanism can be formed for the oscillating unit and the balancing unit. 
   It is also possible, however, that different crank members are provided for driving the oscillating unit and for driving the balancing unit, as a result of which it is possible, for example, to spatially decouple the oscillating unit and the balancing unit from one another. 
   If individual drive mechanisms are not provided for the different crank members, the crank members can be coupled to one another by traction mechanisms, friction and/or gear wheels. In this way, the drive for the oscillating unit as well as the balancing unit can be accomplished with a drive mechanism and crank members that are spatially separated from one another. 
   The drive apparatus and/or additional drive mechanism may also comprise a linear drive, particularly a pneumatically or hydraulically actuated cylinder or a linear motor. Said drives do not translate a rotary movement into a linear, oscillating movement, but instead the oscillating movement is produced directly by the linear drive. Of course, the types of drives selected for the drive mechanism and additional drive mechanism do not show to be the same. For example, the drive apparatus can be configured as a rotary drive and the additional drive mechanism as a linear drive, or the additional drive mechanism can be a rotary drive and the drive apparatus a linear drive. 
   If the linear drive is provided with mechanical advancing units, such as ball screws, toothed belts and/or toothed racks, the arrangement of the linear drive and the transmission to the oscillating unit and/or the balancing unit is flexible with respect to space. 
   The linear drive can act along a lifting axis, which is coaxial to the axis along which the oscillating unit oscillates and/or coaxial to an axis in which the balancing unit oscillates. This shows the advantage that force transfer elements can be dispensed with. 
   The linear drive, however, can also act along a lifting axis which acts at an angle, particularly perpendicular to the oscillation axes of the oscillating unit and/or the balancing unit. This can be particularly advantageous when the space available in the longitudinal direction of the workpiece is limited, for example in the case of particularly long workpieces. In such a design, the linear drive may comprise a swivel and sliding joint, which drives the oscillating unit and/or the balancing unit via one or more push rods. In this way, the linear movement of the linear drive can be easily redirected into a different direction. 
   Within the scope of the present disclosure, it is also possible that the movements of the oscillating unit and the balancing unit are coupled to one another via movement transmission elements, particularly via levers, toothed racks, pinions, toothed belts, or scissor gears. In this way, it is possible to provide only one drive apparatus, which drives the oscillating unit, for example. The movement is then transferred to the balancing unit via the movement transmission elements. It is also possible, however, to drive the balancing unit by the drive apparatus and drive the oscillating unit by the balancing unit via the movement transmission elements. It is also conceivable that a drive apparatus can act on the movement transmission elements, which in turn drive the oscillating unit on the one hand, and the balancing unit on the other hand. 
   When using the aforementioned movement transmission elements, it is advantageous to provide at least one bearing point that is stationary in relation to the movements of the oscillating unit and balancing unit. In this way, particularly in the case of longer movement transmission elements, it can be prevented that these elements or the oscillating unit or the balancing unit connected thereto become destabilized by natural vibrations. 
   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 
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     In order that the invention may be well understood, there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawing, in which: 
       FIG. 1  is a perspective view of an apparatus according to the invention; 
       FIG. 2  is the apparatus according to  FIG. 1  in a top view according to arrow II in  FIG. 1 ; 
       FIG. 3  is the apparatus according to  FIG. 1  in a sectional view according to arrow III in  FIG. 2 ; 
       FIG. 4  is a schematic illustration corresponding to  FIG. 3 ; 
       FIG. 5  is a schematic illustration corresponding to  FIG. 2 ; and 
       FIGS. 6-11  are further embodiments of inventive apparatuses. 
   

   DETAILED DESCRIPTION 
   The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
   In  FIG. 1 , an apparatus for grinding and/or finishing a workpiece is designated overall by the reference numeral  2 . The apparatus  2  shows a headstock side  4  shown on the left and a tailstock side  6  shown on the right. Between the headstock side  4  and tailstock side  6 , an oblong workpiece  8  is received. The workpiece  8  can be machined by grinding and/or finishing when grinding and/or finishing means, which are not shown, such as belts or stones, press onto the workpiece  8  in a direction designated by the numeral  9 . 
   The headstock side  4  shows a machine base  10 , by means of which the headstock side  4  can be fixed relative to the environment of the apparatus  2 . On the machine base  10  an infeed apparatus  12  is provided, which is configured as a lifting cylinder. By means of the infeed apparatus  12 , a sliding saddle  14  can be adjusted in the direction of the tailstock side  6  or in a direction facing away from the tailstock side  6 . For this purpose, the sliding saddle  14  is provided with a linear guide  15 , by which the sliding saddle  14  is guided relative to the machine base  10 . 
   On the sliding saddle  14  a plate-shaped headstock support  16  is provided, which is mounted likewise displaceable relative to the tailstock side  6 . The headstock support  16  is used for the arrangement of a headstock  18 , in which a spindle, which is not shown, is provided. Said spindle is driven rotatably by means of a rotary workpiece drive  20 . On the side facing the workpiece  8 , the spindle is provided with a workpiece mount  22 , which is configured as a support. By means of the rotary workpiece drive  20 , the workpiece mount  22  can rotatably drive the workpiece  8  such that it rotates about a workpiece axis  24  (both directions of rotation are possible, see reference numeral  26 ). 
   The workpiece  8  is mounted on the tailstock side  6  in a further workpiece mount  28  configured as a tip. The workpiece mount  28  is mounted rotatable in a tailstock  30 , which is in turn arranged on a tailstock support  32 . The tailstock support  32  can be displaced relative to a machine base  36  parallel to the workpiece axis  24  by means of the linear guides  34 . 
   The tailstock support  32  and hence the tailstock  30  can be driven by a linear drive  38 . The linear drive  38  is provided with a reciprocating piston  40  connected to the tailstock support  32 , the piston being guided in a cylinder  42 . The cylinder  42  is supported on a boom  44  of the machine base  36  and is supplied hydraulically via lines  46 . 
   The position of the reciprocating piston  40  and hence of the tailstock support  32 , of the tailstock  30  and the tip  28  can be detected by a positioning system  48 , which is only shown schematically. 
   On the headstock side  4 , on the side of the headstock  18  facing away from the tailstock side  6  a further plate-shaped support  50  is provided on the sliding saddle  14 . Said support  50  can be displaced in directions parallel to the workpiece axis  24  in the direction of the tailstock side  6  or away from the same. For this purpose, the support  50  is provided with linear guides, which are not shown, and arranged parallel to the workpiece axis  24 . On the support  50  a balancing body designated overall by the numeral  52  is fastened. Said body shows two substantially vertically extending plates  54  and  56 , which are arranged on either side of the rotary workpiece drive  20 . The plates  54  and  56  are connected to one another by a substantially horizontal plate  58 . 
   Furthermore, on the headstock side  4  a drive apparatus  60  is provided, by which the headstock support  16  and the support  50  can be driven by oscillations. This will be described hereinafter with reference to  FIGS. 2 to 5 . 
     FIG. 2  shows the headstock side  4  in a top view. Also shown is the sliding saddle  14 , including the support  50  arranged thereon comprising the balancing body  52 , and furthermore including the headstock support  16  for the headstock  18 . The interaction between the drive apparatus  60  and the support  50  on the one hand, and the headstock support  16  on the other hand, will be described hereinafter in detail with reference to  FIG. 3 . The drive apparatus  60  shows a crank member  62 , which is rotatably mounted in the drive apparatus  60  by means of a lower bearing  64  according to  FIG. 3  and an upper bearing  66  according to  FIG. 3 . Between the bearings  64  and  66 , the crank member  62  is provided with a first connection rod bearing  68  for a connection rod  70 , which is also shown in  FIGS. 2 and 1 . The connection rod  70  is connected to the headstock support  16  via a pin element  72 . 
   Between the bearings  64  and  66 , adjacent to the first connection rod bearing  68 , a second connection rod bearing  74  is provided for a second connection rod  76 . The second connection rod  76  is also shown in  FIG. 2 . The second connection rod  76  is connected to the support  50  for the balancing body  52  via a second pin element  78 . The angular offset of the connection rod bearings  68  and  74  relative to the crank member  62  is 180°. 
   The design shown in  FIG. 3  is schematically illustrated in  FIGS. 4 and 5 , the reference numerals having been transferred accordingly from  FIGS. 1 to 3 . For example, the sliding saddle  14  is only shown schematically as a stationary mount. For simplification purposes, the linear drive  38  is further shown as a spring. The crank member  62  illustrated schematically in  FIG. 4  can rotate about an axis of rotation  80  upon actuation of the drive apparatus  60 . The first connection rod bearing  68  of the connection rod  70  is offset by a dimension  82  in relation to said axis of rotation  80 . Accordingly, the second connection rod bearing  74  for the connection rod  76  is offset from the axis of rotation  80  by the dimension  84 . When the crank member  62  rotates, said rotary movement is transmitted via the connection rod  70  and the pin element  72  to the headstock support  16 , which is mounted displaceable relative to the sliding saddle  14  such that the headstock support  16  performs an oscillating movement designated by the numeral  86 . The headstock support  16  can perform a forward stroke designated by the numeral  86   a  in the direction of the tailstock side  6 , which is followed by a return stroke  86   b . The forward stroke  86   a  and the return stroke  86   b  correspond to the oscillation stroke and amount to double the offset  82 . 
   The connection rod  76 , which drives the support  50  for the balancing body  52  via the pin element  78 , is also driven by the rotation of the crank member  62 . The rotation of the crank member  62  is therefore translated into an oscillating movement  88  of the support  50  with the balancing body  52 . The support  50  with the balancing body  52  can perform a forward stroke  88   a  in the direction of the tailstock side  6  or a return stroke  88   b . The forward stroke  88   a  and the return stroke  88   b  correspond to the oscillation stroke of the support  50 . Said stroke amounts to double the offset  84 . 
   The headstock support  16 , the headstock  18 , the rotary workpiece drive  20 , the workpiece mount  22 , the workpiece  8 , the workpiece mount  28 , the tailstock  30 , and the tailstock support  32  form an oscillating unit, which is designated overall by the reference numeral  96  in  FIGS. 4 and 5 . Said unit  96  is driven by the drive apparatus  60 . In order to guarantee secure retention of the workpiece  8  between the workpiece mounts  22  and  28  even during a return stroke  86   b  of the headstock  18 , the linear drive  38  is prestressed such that it builds up a tension force, which is designated by the numeral  90  in  FIG. 1  and acts in the direction of the workpiece  8 . 
   The support  50  and the balancing body  52  form a balancing unit, which in  FIGS. 4 and 5  is designated overall by the reference numeral  94 . During an oscillating movement of the oscillating unit  96 , which is composed as described above, the balancing unit  94  oscillates too. The movements of the oscillating unit  96  and balancing unit  94  act in opposite direction to one another. Thus, if the oscillating unit  96  performs a forward stroke  86   a , the balancing unit  94  at the same time performs a return stroke  88   b . If during further rotation of the crank member  62  the oscillating unit  96  performs a return stroke  86   b , the balancing unit  94  is moved in the opposite direction with a forward stroke  88   a.    
   The support  50  and the balancing body  52  oscillate along an axis  92  shown in  FIGS. 1 and 2 . The axis  92  is arranged coaxial to the workpiece axis  24 , in which the oscillation movement  86  of the oscillating unit  96  takes place. 
   In the exemplary embodiment shown in  FIGS. 1 to 5 , the geometry of the drive of the oscillating unit  96  (offset  82 , length of the connection rod  70 ) corresponds to the geometry of the drive of the balancing unit  94  (offset  84 , length of the connection rod  76 ). This means that the oscillation stroke of the oscillating unit  96  is equal to the oscillation stroke of the balancing unit  94 . To achieve ideal compensation for the vibrations produced by the oscillating movement of the oscillating unit  96 , the oscillating unit  96  shows the same mass as the balancing unit  94 . The workpiece  8  is part of the oscillating unit  96 . If another workpiece that shows a different weight is to be machined, the balancing unit  94  can be adapted accordingly by accordingly adding or removing weight to or from the balancing body  52 . 
   With reference to  FIG. 6 , a further embodiment of the invention will be described hereinafter. It is similar in design to the apparatus according to  FIGS. 1 to 5 . For example, a crank member  62  is provided, which can be driven rotatably by a drive apparatus, which is not shown, in order to drive a balancing unit, designated overall by the numeral  94 , by oscillations via a connecting rod  76 . The crank member  62  acts on an oscillating unit designated overall by the reference numeral  96  via a connection rod  70 . The unit shows an oblong support  98 , which replaces the headstock support  16  and tailstock support  32  that are shown in  FIGS. 1 to 5 . The headstock  18  and the tailstock  30  are fastened on the common support  98 . In order to enable an adjustment to the length of the workpiece  8 , the tailstock  30  is displaceable relative to the common support  98 , which is indicated by the double arrow  100 . 
   The embodiment according to  FIG. 7  is comparable to the embodiment according to  FIGS. 1 to 5 . The oscillating unit  96  shown in  FIG. 7  corresponds to the oscillating unit according to  FIG. 5 , which shows a headstock support  16 , headstock  18 , workpiece mount  22 , workpiece  8 , tip  28 , tailstock  30 , and tailstock support  32 . The balancing unit  94  shown on the left in  FIG. 7  can, as is shown in  FIG. 5 , comprise a support  50  and a balancing body  52 . 
   In the embodiment according to  FIG. 7 , a drive apparatus, which is not shown, drives a first crank member  62 , which causes the oscillating unit  96  to oscillate via a connection rod  70 . In addition to the first crank member  62 , a second crank member  102  is provided, which is driven by the first crank member  62  via a traction mechanism  104  configured as a belt drive. Thus, the crank member  102  can cause the balancing unit to oscillate via the connecting rod  76 , the oscillation acting in opposite direction to the oscillating movement of the oscillating unit  96 . 
   In the embodiment according to  FIG. 8 , an additional crank member  102  is also provided. Each crank member  62  and  102  is driven by an individual drive mechanism, that is, the crank member  62  is driven by a drive apparatus  60 , which is not shown in detail, and the crank member  102  by an additional drive, which is not shown in detail. The embodiment according to  FIG. 8  shows the advantage that a spatial separation is possible between the oscillating unit  96  and the balancing unit  94 . It is necessary, however, to coordinate the drive mechanisms  60  and  106  with one another via a suitable controller in order to ensure that the movement of the balancing unit  94  is in the opposite direction to the movement of the oscillating unit  96 . 
   The previously described drive apparatuses and additional drives were rotary drives. In  FIGS. 9 and 10 , configurations are proposed which are based on linear drives. In  FIG. 9 , for example, a balancing unit is designated overall by the reference numeral  94 , and an oscillating unit overall by the numeral  96 . The oscillating unit  96  is driven by a first linear drive  108 , which forms the drive apparatus for the oscillating unit  96 . In order to drive the balancing unit  94 , an additional drive is provided in the form of a second linear drive  110 . The linear drives  108  and  110  can be formed, for example, by hydraulically actuated cylinders. By suitable activation, opposing movements of the linear drives  108  and  110  and hence of the oscillating unit  96  and balancing unit  94  can be produced. 
   In the embodiment according to  FIG. 10 , only one linear drive  108  is required as a drive apparatus. Via a swivel and sliding joint  112 , said apparatus drives a first push rod  114  acting on an oscillating unit  96 . The swivel and sliding joint acts on a balancing unit  94  via a second push rod  116 . 
   Finally,  FIG. 11  shows an embodiment wherein the drive apparatus of an oscillating unit  96  is formed by a linear drive  108 . The apparatus drives a headstock support  16  by oscillations and coaxial to a workpiece axis  24 . The headstock support  16  shows a swivel and sliding joint  118 , which is coupled to a lever  120 . The lever  120  shows a stationary mount  122  arranged at the center of the length of the lever  120 . On the side opposite to the swivel and sliding joint  118 , the lever  120  shows a further swivel and sliding joint  124 , which is provided on the support  50  of the balancing unit  94 . The balancing unit is therefore driven causally by the linear drive  108 , however by interconnecting the oscillating unit  96 . The oscillating unit  96  oscillates along the workpiece axis  24  and the balancing unit  94  oscillates in an axis  92  parallel to the workpiece axis  24 . An additional drive  126  for the balancing unit  94 , the drive being indicated with dotted lines in  FIG. 11 , is not required, but may be provided. 
   It should be noted that the disclosure is not limited to the embodiment 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 and of the present patent.