Abstract:
A bearing arrangement including a rolling or sliding bearing that has an inner ring and an outer ring and at least one add-on part provided on the inner ring or on the outer ring, this add-on part being formed of a meltable or curable material and being attached with a positive fit to the inner ring or the outer ring by a generative manufacturing process.

Description:
[0001]    The invention relates to a bearing arrangement comprising a rolling or sliding bearing with an inner ring and an outer ring and at least one attachment part arranged on the inner ring or on the outer ring. 
       BACKGROUND 
       [0002]    Various applications require a bearing with an attachment part. The attachment part can be, e.g., a housing for the mounting of a sensor or for electronic components. 
         [0003]    Conventional bearing arrangements of this type, which are also designated as sensor bearings, are usually built so that an attachment part is bonded to the bearing or an injection molded part is clipped in a sealing groove on one of the rings. However, such attachment parts must be produced specifically for a certain bearing type, because the bearing diameters, geometry of the sealing grooves, and other dimensions are different. This produces high tool costs for deep-drawing dies and/or injection molding dies, so that attachment parts can be produced economically only if large quantities are produced. Accordingly, the variety of types of bearings with sensors is very limited. 
         [0004]    Therefore, it would be desirable to provide a bearing arrangement that is also economical in small quantities. 
       SUMMARY 
       [0005]    The invention is thus based on the object of providing a bearing arrangement with an attachment part that can also be produced economically in small quantities. 
         [0006]    To achieve this object, it is provided according to the invention for a bearing arrangement of the type specified above that the attachment part is made from a meltable or curable material and is attached to the inner ring or the outer ring with a positive fit through a generative production process. 
         [0007]    The invention concerns the idea of producing small quantities of an attachment part through a method that is typically used in the scope of rapid prototyping. A simple replacement of injection-molded or deep-drawn attachment parts by attachment parts that have been produced through a rapid prototyping method is very difficult due to the limited tolerances. In particular, the formation of snap-on contours is problematic, so that a conventional rapid prototyping method is not suitable for series production. 
         [0008]    The meltable or curable material is preferably a plastic material that can be processed by a generative production method. Examples for such a material that can be used for producing the bearing arrangement according to the invention include a UV-curable plastic, that is, a material that can be cross-linked and cured by irradiation with ultraviolet light. The meltable or curable material can be used, e.g., in a melt deposition method. For this purpose, it is heated above its melting temperature and deposited through a suitable apparatus. As another generative production method, a deposition welding method can also be used in which the deposited material is melted by a laser. The deposited material can be prepared as a wire or filament and deposited by a deposition device onto the inner ring or the outer ring. In principle, the material that can be used in the generative production method could also be a metallic material that forms, e.g., with other components, a paste that can be deposited by a corresponding apparatus onto an inner ring or an outer ring and then cured through irradiation with a radiation tool (laser). To generate certain mechanical or electrical properties of the attachment part, it can also be provided that the meltable or curable material is comprised from a plastic material and a metallic material. 
         [0009]    The invention achieves the objective by attaching the attachment part through a generative production method, such as a melt deposition method, with a positive fit onto the inner ring or the outer ring. In this way, the attachment part is connected to the rolling or sliding bearing through a positive-fit connection instead of a non-positive fit. Thus, problems that are produced through a very tolerance-dependent snap-on contour that is produced in a conventional way, for example, in an injection molding method are avoided. In contrast, according to the invention it is provided to print the attachment part with a correspondingly adapted printer, in particular, with a so-called 3D printer, directly on the rolling or sliding bearing. 
         [0010]    In the bearing arrangement according to the invention, it is preferred that the attachment part is produced through the layer-by-layer deposition of multiple layers of the meltable or curable material. In this way, a three-dimensional attachment part can be built up layer by layer. After the hardening of a deposited layer, the next layer can be deposited on top. 
         [0011]    It is also in the scope of the invention that the attachment part surrounds an object on one or more sides or that the object is integrated in the interior of the attachment part. For this purpose, the melt deposition method is interrupted at a suitable point in time after a holding structure has been printed for the object, the object is inserted, and then the attachment part is completed with the inserted object through the continuation of the printing process, so that the object is preferably surrounded on all sides by the meltable or curable plastic material or it is integrated in the interior of the attachment part. 
         [0012]    The object embedded in the attachment part can be, for example, a sensor, a sensor component, an electronic component, or an electronic circuit. In addition, corresponding lines for data transfer and power supply, as well as sensor lines and control lines, etc., can be integrated. 
         [0013]    An especially preferred refinement of the invention is given if, in the bearing arrangement according to the invention, the inner ring or the outer ring has an undercut in which the meltable or curable plastic material is inserted. The undercut can be formed, for example, as a groove, in particular, as a sealing groove, so that a positive-fit connection that guarantees the secure holding of the attachment part on the rolling or sliding bearing is created when the molten plastic material is inserted into this groove or undercut. 
         [0014]    In the bearing arrangement according to the invention, it is also possible to produce conductor tracks by using a modified meltable or curable plastic material that is electrically conductive. For this purpose, the plastic material can be filled, for example, with graphite. The other areas of the attachment part are produced with a different plastic material that is electrically insulating. 
         [0015]    In addition, the invention relates to a method for producing a bearing arrangement, comprising a rolling or sliding bearing with an inner ring and an outer ring and at least one attachment part arranged on the inner ring or on the outer ring. The method according to the invention distinguishes itself in that the attachment part is made from a meltable or curable material that is deposited through a generative production method with a positive fit on the inner ring or the outer ring. Preferably, the material is a plastic material. The generative production method is preferably a melt deposition method. 
         [0016]    In the method according to the invention, it is preferred that after the deposition of a part of the meltable or curable plastic material, an object is arranged on top and/or fastened on top and then another part of the meltable or curable plastic material is deposited that at least partially surrounds the object. 
         [0017]    To simplify the production of the bearing arrangement, in the method according to the invention it can be provided that the rolling or sliding bearing is fixed in a holder that can pivot and/or rotate about multiple axes and whose position is changed at least once during the deposition of the meltable or curable plastic material. For the melt deposition method, the molten plastic material is typically extruded from a nozzle that is arranged perpendicular, so that the plastic material exits the nozzle vertically downward. By use of the holder, the bearing arrangement and especially the position at which the molten plastic material is to be deposited can be brought into a suitable position. In the scope of this production method, the position of the holder with the rolling or sliding bearing mounted to this holder is changed once or multiple times. Accordingly, in the method according to the invention, preferably at least two layers of the meltable plastic material are deposited with different directions of deposition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The invention is explained below using an embodiment with reference to the drawings. The drawings are schematic representations and show: 
           [0019]      FIG. 1  a sectioned side view of a bearing arrangement according to the invention, 
           [0020]      FIG. 2  a holder that is used for producing the bearing arrangement according to the invention, 
           [0021]      FIG. 3  a detail from  FIG. 2  in the area of a printing head, 
           [0022]      FIG. 4  a detail of an attachment part, 
           [0023]      FIG. 5  a bearing ring during the production of the attachment part, 
           [0024]      FIG. 6  the bearing ring shown in  FIG. 5  in a different position, 
           [0025]      FIG. 7  a sectioned view of another embodiment of a bearing arrangement according to the invention, 
           [0026]      FIG. 8  a detail of a bearing ring with mounted attachment part, and 
           [0027]      FIG. 9  a similar embodiment like that shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]      FIG. 1  shows a bearing arrangement  1 , comprising a rolling bearing  2  with an inner ring  3  and an outer ring  4  between which rolling elements formed as balls  5  are held. In the sectioned view of  FIG. 1 , it can be seen that the outer ring  4  has a sealing groove  6  in which a mirror-inverted projection  8  of an attachment part  7  is arranged. The attachment part  7  is formed by a generative production method, in the illustrated embodiment by a melt deposition method. Through the production, the attachment part  7  is connected with a positive fit to the outer ring  4 . 
         [0029]    In the attachment part  7  there is an object that is formed in this case as a sensor. The sensor can be, e.g., a rotational speed sensor in which a pulse encoder ring interacts with a magnet and a Hall IC; the magnet and the Hall IC can be arranged in the attachment part  7  that is connected to the outer ring  4 ; the pulse encoder ring (not shown) can be connected to the inner ring  3 . 
         [0030]      FIG. 2  shows the method for producing the bearing arrangement  1 . The rolling bearing  2  is mounted on a holder  9  that has a rotatable journal  10  and a tensioning device  11  that is arranged on the free end of the journal  10  and through which the rolling bearing  2  is held. The holder  9  is rotatable and pivotable about multiple axes, namely about its longitudinal axis, which is represented by the reference symbol  12 . It can also be moved along two orthogonal axes  13 ,  14 , wherein the axis  13  is a horizontal axis and the axis  14  is a vertical axis. Finally, the holder  9  can rotate about an axis  15  (z-axis) that is orthogonal to the two axes  13 ,  14  and extends vertically out of the plane of the drawing in the representation of  FIG. 2 . The holder  9  is used as a positioning device to position the mounted roller bearing exactly under a print head  16 . The print head  16  is a component of a 3D printer with which a melt deposition method can be performed. This method is also called Fused Deposition Modeling (FDM). In the FDM method, a plastic filament is melted and placed layer by layer by an extruder with a fine nozzle (print head  16 ) in strips in order to form a defined component, in the present case, the attachment part  7 . The deposition of the melted plastic material melts the individual extruded strips and a solid plastic part is produced. By positioning the holder  9 , i.e., through rotation and one-axis or multiple-axis displacement, the roller bearing  2  held by the holder  9  is positioned exactly under the opening of the stationary print head  16 . Because the molten plastic material exists on the bottom side of the stationary print head  16 , it is necessary to position and track the material to be printed accordingly. 
         [0031]      FIG. 3  shows the print head  16  at an enlarged scale. The print head  16  has a hole  17  through which the melted plastic material flows until it emerges at the end of the print head  16 . In  FIG. 3  it can be seen that the roller bearing  2 , more precisely, its outer ring  4 , has been positioned under the print head  16  so that the emerging plastic material can be deposited into the sealing groove  6 . Through corresponding rotation and optional displacement of the roller bearing  2 , the sealing groove  6  can be filled with the meltable plastic material in one processing step. By depositing the plastic material into the sealing groove  6 , a positive-fit connection is produced. Then another layer of the plastic material can be deposited onto the plastic material in the sealing groove  6 . In this way, the attachment part  7  is gradually built up in multiple layers. In one design, the attachment part  7  can extend around the entire circumference, so that a ring-shaped attachment part is formed. In another design, the attachment part can be generated only over one part of the circumferential direction. 
         [0032]      FIG. 4  shows the processing step when the positive-fit connection between the roller bearing  2  and the attachment part to be printed is produced by pressing the meltable plastic material  18  into the sealing groove  6  that has an undercut. 
         [0033]      FIG. 5  shows the outer ring  4  of the roller bearing  2  that has been brought into the position shown in  FIG. 5  through the holder  9 . In this position, the meltable plastic material can be output from the print head  16  into the sealing groove  6 . In  FIG. 5  it can be seen that the holder  9  has tilted the outer ring  4  by an angle  19 . After the sealing groove  6  has been filled, the remaining section of the attachment part is printed, as shown in  FIG. 6 . To do this, the outer ring  4  is rotated through the holder  9  back into a horizontal position, as is shown in  FIG. 6 . In this position, the attachment part  7  can be completed. To do this, the melted plastic material is deposited in multiple layers. The holder  9  moves the mounted bearing arrangement  1  horizontally, in order to position the area to be printed under the print head  16 . 
         [0034]      FIG. 7  is a sectioned view and shows the bearing arrangement  1  with the printed attachment part  7  that is arranged with a positive-fit connection in the sealing groove  6  of the outer ring  4 . A first shoulder  20  of the attachment part  7  was printed in a first position of the print head  16 , which produces a special first layering direction. A second shoulder  21  of the attachment part  7  was printed in a second layering direction, after which the roller bearing  2  was rotated by use of the holder  9  into a second, horizontal position. By depositing the melted plastic material onto a previously produced layer, the individual extruded strips melt with each other and produce the solid attachment part  7  in which at least two layers have different directions of deposition. 
         [0035]      FIG. 8  is a similar representation as  FIG. 4  and shows the area of the sealing groove  6  of the outer ring  4  during the production of the attachment part  7 . The generated positive-fit connection is generated in this embodiment through over-extrusion, i.e., by printing an especially thick track  22  of the meltable plastic material. In this way, the plastic material is printed into the sealing groove  6 , any tolerances are equalized, and a positive-fit connection is automatically produced. If necessary, multiple especially thick tracks can be printed one next to the other and optionally one over the other. Then finer layers  23  of the plastic material are printed over or next to the track  22 , which completes the attachment part  7 . Tracks or layers with different thicknesses can be printed through corresponding control of the print head  16  which can have, for example, a nozzle with variable diameter. Alternatively, the layer thickness can also be influenced by the advancing speed of the material to be processed. In general, other parameters of the production method can also be varied in order to generate a certain product or certain properties. In addition to the already mentioned adjustment of the nozzle diameter and a changing of the material advance, the feed rate of the print medium, that is, the plastic material, the distance between the workpiece and the print head, or the print head temperature can also be varied or adapted. In practice, some or all of the mentioned parameters are monitored and controlled or regulated. 
         [0036]      FIG. 9  shows a similar embodiment as  FIG. 8  and represents a detail of the bearing arrangement  1  in the area of the sealing groove  6 . Instead of one especially thick track of the melted plastic material, in the embodiment of  FIG. 9 , multiple fine layers  24  are printed axially one next to the other in the sealing groove  6 . Then a second layer of multiple strips of the plastic material arranged one next to the other is deposited. In this way, multiple layers are produced, wherein the attachment part  7  is formed. 
         [0037]    In one modification of the production method, initially a first part of the attachment part is printed in order to fill the sealing groove. Then the printing process is interrupted and an object such as a sensor or a sensor component is deposited on the plastic material. Then the printing process is continued until the attachment part is completely surrounded by plastic material. For producing a conductive connection, a meltable plastic material can also be used that is electrically conductive. To do this, plastic material is filled with graphite. In this way, an object such as a sensor can be reliably protected from environmental effects and integrated into an attachment part. In addition, electrical connections can be provided. 
         [0038]    The described method for producing a bearing arrangement has the advantage that it can also be performed economically at small quantities and guarantees a secure connection of an attachment part to a bearing. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           1  Bearing arrangement 
           2  Roller bearing 
           3  Inner ring 
           4  Outer ring 
           5  Ball 
           6  Sealing groove 
           7  Attachment part 
           8  Projection 
           9  Holder 
           10  Journal 
           11  Tensioning device 
           12  Reference symbol 
           13  Axis 
           14  Axis 
           15  Axis 
           16  Print head 
           17  Hole 
           18  Plastic material 
           19  Angle 
           20  Shoulder 
           21  Shoulder 
           22  Track 
           23  Layer 
           24  Layer