Abstract:
The invention relates to a method for producing a housing assembly ( 1 ), in particular for an electric machine, wherein a region ( 26 ) of a closure part ( 3 ) is reshaped in the form of an indentation ( 26′ ), in order to thus press material of the closure part ( 3 ) against a housing part ( 16 ) for a non-positive engagement between the closure part ( 3 ) and the housing part ( 16 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a method for producing a housing arrangement, a housing arrangement and a stamping apparatus. 
       TECHNICAL BACKGROUND 
       [0002]    Although applicable to any housing arrangement, the present invention and the problem forming the basis thereof are explained in more detail hereinunder in relation to a housing arrangement for an electric motor. 
         [0003]    Document DE 19 43 053 describes a housing arrangement for an electric motor, which has a housing part and a closure part. The closure part is formed as a bearing plate. The closure part is riveted to the housing part. For this purpose riveting bolts are formed on the housing part. The riveting bolts extend axially through corresponding holes in the closure part. The rivet heads are formed behind the closure part as seen from the housing part, in order thereby to create a positive locking connection between the housing part and the closure part. 
         [0004]    Furthermore, the applicant has in-house knowledge of a method for producing a housing arrangement for an electric motor. In the case of this method, a closure part is pried together with a housing part, i.e. a press fit is produced between the housing part and the closure part. 
         [0005]    In the case of the first approach, described above, for producing a housing arrangement, it has proved to be disadvantageous that the provision of the riveting bolts is associated with considerable manufacturing outlay. In the case of the second approach, described above, it has proved to be disadvantageous that strong axial forces arise during the prying process and lead to deformation of the housing part. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the present invention is to avoid the disadvantages described above. 
         [0007]    This object is achieved in accordance with the invention by a method having the features of claim  1 , by a housing arrangement having the features of claim  10 , and/or by a stamping apparatus having the features of claim  11 . 
         [0008]    Accordingly a method for producing a housing arrangement, in particular for an electric machine, is provided, wherein a region of a closure part is shaped in the form of an indent in order thereby to press material of the closure part against a housing part for a non-positive connection between the closure part and the housing part. 
         [0009]    Furthermore, a housing arrangement, in particular for an electric machine, is provided, having a housing part and a closure part, wherein a region of the closure part is shaped in the form of an indent, whereby material of the closure part is pressed against the housing part for a non-positive connection between the closure part and the housing part. 
         [0010]    Furthermore, a stamping apparatus is provided for use in the method in accordance with the invention, having a plurality of stamps which can each be rotated at the same time about a middle axis of a respective indent to be formed, can be inclined at a varying angle with respect to the middle axis and can be advanced axially in relation to the middle axis, wherein the contact point of a respective stamp on the region can be moved along a hypocycloid in order thereby to displace the material essentially in an axial direction and tangential direction in relation to the middle axis, or having a plurality of stamps which can each be rotated at the same time about a middle axis of a respective indent to be formed, can be inclined at a constant angle with respect to the middle axis and can be advanced axially in relation to the middle axis, wherein the contact point of a respective stamp on the region can be moved along an inclined spiral, in order thereby to displace the material essentially in an axial and tangential direction in relation to the middle axis. 
         [0011]    The idea forming the basis of the present invention is to shape a region of a closure part in the form of an indent in order thereby to create a connection between the closure part and a housing part. This is accordingly a matter of merely local shaping of the closure part, which leads to greater expansion of the closure part in the plane of the indent. However, if this expansion is limited or inhibited by the housing part, a non-positive connection is created between the closure part and the housing part. This non-positive connection is used in the present case to fixedly connect the housing part to the closure part. 
         [0012]    The advantage of the approach in accordance with the invention is that no additional components such as screws, rivets or the like are required to connect the closure part to the housing part. Furthermore, the introduction of force into the closure part or the housing part is only slight owing to the merely local shaping of the closure part, for example, in comparison to the known prying procedure, which means that disadvantageous deformation of the housing part can be avoided. 
         [0013]    Advantageous embodiments and developments of the present invention are apparent from the further subordinate claims and from the description taken in conjunction with the figures of the drawing. 
         [0014]    “Indent” is to be understood in this case to mean a concave plastic deformation in the closure part. The indent preferably has a circular outer contour when seen in the plan view of the closure part. 
         [0015]    According to a preferred embodiment of the method in accordance with the invention, the shaping step is carried out by means of a stamp which is rotated about a middle axis of the indent to be formed and is inclined at a varying angle with respect to the middle axis, wherein the stamp is advanced axially in relation to the middle axis and the contact point of the stamp on the region follows a hypocycloid, whereby the material essentially flows in an axial and tangential direction in relation to the middle axis. This movement of the stamp corresponds to the movement also used during radial riveting. In this way, the indent can be formed in the closure part with comparatively low application of force, which means that excessive or any deformation of the housing part can be avoided. 
         [0016]    According to a further preferred embodiment of the method in accordance with the invention, the shaping step is carried out by means of a stamp which is rotated about a middle axis of the indent to be formed and is inclined at a constant angle with respect to the middle axis, wherein the stamp is advanced axially in relation to the middle axis and the contact point of the stamp on the region follows an inclined spiral, whereby the material essentially flows in an axial and tangential direction in relation to the middle axis. The movement of the stamp corresponds to the movement also used during wobble riveting. This movement of the stamp also means that a comparatively only slight application of force is required to form the indent in the closure part, whereby, once again, excessive deformation or any deformation of the housing part can be avoided. 
         [0017]    According to a further preferred embodiment of the method in accordance with the invention, the region is shaped by means of a conical surface of the stamp. The conical surface facilitates formation of the indent. 
         [0018]    According to a further preferred embodiment of the method in accordance with the invention, a plurality of regions of the closure part are shaped in the form of an indent at the same time. In this way, the closure part is shaped consistently so that there is no distortion thereof or tilting thereof with respect to the housing part. 
         [0019]    According to a preferred embodiment of the method in accordance with the invention, the closure part is inserted into a receiving region of the housing part before the shaping step and is clamped to the receiving region by means of the shaping step. As already explained, the forming of the indent in the closure part leads to this closure part being enlarged in the plane of the indent. In order to use this enlargement for the non-positive connection, the closure part is inserted into a receiving region of the housing part in accordance with this embodiment. The enlargement of the closure part associated with the forming of the indent then leads to the closure part being clamped to the receiving region of the housing part. The clamping results from the fact that the closure part is pressed against, for example, two mutually opposing portions of the receiving region. 
         [0020]    According to a further preferred embodiment of the method in accordance with the invention, the closure part is formed with at least one lug which engages into a corresponding recess in the housing part, wherein the indent is formed in the lug. Initially, the lug serves to produce a positive locking connection between the closure part and the housing part, for example, in the peripheral direction of the housing part. Furthermore, the circumstance that the lug is confined by the recess on a plurality of sides, in particular opposing sides, means that the forming of the indent in the lug leads to a better non-positive connection between the lug and the corresponding recess. 
         [0021]    According to a further preferred embodiment of the method in accordance with the invention, an opening in a carrier part is placed onto a spigot on the closure part, wherein the spigot is shaped to engage behind the carrier part. The shaping of the spigot is preferably effected by wobble or radial riveting. This type of connection between the carrier part and the closure part has the advantage that it is easy to produce. Furthermore, no additional components, such as screws, are required. Screws are disadvantageously associated with a hole in the closure part, which can in turn lead to leakages with respect to fluids. Such leakages, however, are to be avoided particularly in the region of the electric motors. 
         [0022]    According to a further preferred embodiment of the method in accordance with the invention, the housing part is formed as a motor housing case, the closure part is formed as a bearing plate and/or the carrier part is formed as a brush carrier part. “Bearing plate” means a closure part which is suitable for receiving a bearing. “Brush carrier part” means a carrier part which is suitable for carrying brushes for an electric sliding contact to the collector or to collector rings of the rotating part of the electric machine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The present invention will be explained in more detail hereinunder with the aid of the exemplified embodiments illustrated in the figures of the drawing in which: 
           [0024]      FIG. 1  shows a partially cut-away and partially schematic plan view of a housing arrangement in accordance with an exemplified embodiment of the present invention in a first state; 
           [0025]      FIG. 2  illustrates the housing arrangement of  FIG. 1  in a second state; 
           [0026]      FIG. 3  illustrates a cross-sectional view A-A from  FIG. 2 ; 
           [0027]      FIG. 4  illustrates a stamping apparatus in accordance with an exemplified embodiment of the present invention; and 
           [0028]      FIG. 5  illustrates a process flow in accordance with an exemplified embodiment of the present invention. 
       
    
    
       [0029]    Unless stated otherwise, in the figures of the drawing, like components, elements and features are designated with like reference numbers. 
       DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0030]    Exemplified embodiments of a housing arrangement  1 , see  FIGS. 1-3 , of a method for producing this arrangement, see  FIG. 5 , and a stamping apparatus  2 , see  FIG. 4 , for use in the method are explained in more detail hereinunder with reference to all the figures. 
       Step S 1   
       [0031]    In a step S 1 , see  FIG. 5 , an e.g. approximately annular bearing plate  3 , see  FIG. 3 , is first provided. The bearing plate  3  is preferably formed as one piece with a plurality of spigots  4 . The spigots  4  extend essentially perpendicular to a main plane of extension H of the bearing plate  3 . The spigots  4  are formed on a rear side  5  of the bearing plate  3 . 
         [0032]      FIG. 1  shows the front side  6  of the bearing plate  3 . Furthermore,  FIG. 1  also shows that a plurality of lugs  11  are formed on an outer circular periphery  7  of the bearing plate  3 . Preferably, four of the lugs  11  are disposed along the periphery  7  of the bearing plate  3 . These can, for example, each be disposed at an angle W of 90° to each other about a middle axis M 1 . 
         [0033]    The bearing plate  3  is produced from metal, preferably steel. 
       Step S 2   
       [0034]    In a step S 2 , a brush carrier part  12 , see  FIG. 3 , is provided. The brush carrier part  12  has through-openings  13 . The through-openings  13  can be formed in the region of indentations  14  in the brush carrier part  12 . 
         [0035]    The brush carrier part  12  is preferably produced from synthetic material. 
       Step S 3   
       [0036]    In a step S 3 , the brush carrier part  12  is pushed with its through-openings  13  onto the spigots  4  of the bearing plate  3 . Subsequently, the spigots  4  are shaped by means of wobble or radial riveting in such a way that a head  15  is formed as shown for spigot  4 ′, see  FIG. 3 . The head  15  engages behind the brush carrier part  12  and therefore fixedly connects the brush carrier part  12  to the bearing plate  3 . During radial or wobble riveting of the spigots  4 , the introduction of force into the brush carrier part  12 , which is inherently sensitive (because it is produced from synthetic material), is only slight and is precisely controllable. 
       Step S 4 : 
       [0037]    In a step S 4 , a motor housing case  16  with a preferably annular cross-section is provided. The motor housing case  16  is formed with recesses  21  on its inner periphery  17 , see FIG.  1 . The recesses  21  are formed to be suitable to receive lugs  11 . Furthermore, the motor housing case  16  is formed with a shoulder  22  as an abutment for the lugs  11  in the axial direction in relation to the middle axis M 1 . 
         [0038]    The motor housing case  16  is formed from metal, preferably steel. 
       Step S 5   
       [0039]    In a step S 5 , the unit consisting of the bearing plate  3  and brush carrier part  12  is inserted into the receiving region, designated generally as  23 , see  FIG. 3 , in the motor housing case  16 . The receiving region  23  is defined by the recesses  21 , the inner periphery  17  and the shoulders  22 . 
         [0040]    During insertion of the bearing plate  3  into the motor housing case  16 , the lugs  11  of the bearing plate  3  come into engagement with the recesses  21 . This engagement ensures a positive locking connection between the bearing plate  3  and the motor housing case  16  in the peripheral direction U in relation to the middle axis M 1 . In the exemplified embodiment illustrated in  FIG. 1 , the lugs  11  are essentially rectangular, being defined by surfaces  24 ,  25  of the recess  21 . The surfaces  25  thus lie opposite each other in the peripheral direction U and ensure the afore-mentioned positive locking connection in the peripheral direction U. The surface  24 , on the other hand, ensures a positive locking connection in the radial direction R in relation to the middle axis M 1 . 
       Step S 6   
       [0041]    In a step S 6 , the bearing plate  3  is fixedly connected to the motor housing part  16 . To this end, regions  26 , see  FIG. 1 , in corner regions of the essentially rectangular lugs  11  are each shaped in the form of an indent  26 ′, see  FIG. 2 . For this purpose, the arrangement consisting of the bearing plate  3  and motor housing  16  is disposed below the stamping apparatus  2 , see  FIG. 4 . 
         [0042]    The stamping apparatus  2  has eight stamps  31 . However, it would be equally possible to provide two, three or more stamps  31 . The stamps  31  are each formed with a conical surface  32 . The conical surface  32  forms a tip  33  in the direction of the bearing plate  3  disposed thereunder. The eight stamps  31  are attached to a holder  34  which, on the inside thereof, has a mechanism, not shown, for movement of each stamp  31  in the manner described below. This movement is explained in more detail hereinunder by way of example with the aid of only one stamp  31 . 
         [0043]    The stamp  31  is rotated about the middle axis M 2  of a respective indent  26 ′ which is to be formed. At the same time, the angle W 2  by which the stamp  31  is inclined with respect to the middle axis M 2  is varied. Furthermore, at the same time, the stamp  31  is advanced axially, i.e. along the middle axis M 2  in the direction of the bearing plate  3 . The contact point of the stamp  31  on the region  26  follows a hypocycloid, whereby the material essentially flows in an axial direction F 1 , F 2  (see  FIG. 2 ) and tangential direction in relation to the middle axis M 2 . 
         [0044]    Each of the stamps  31  of the stamping apparatus  2  is moved in this way. The axial advancement can be effected by movement of the holder  34  along the axis M 1 , that is in the direction of the bearing plate  3 , i.e. in this respect the stamps  31  are moved jointly. 
         [0045]    The above-described movement of a stamp  31  corresponds to that in radial riveting. Alternatively, it would also be feasible to keep the angle W 2  constant, wherein then the point of the stamp  31  on the region  26  follows a downwardly inclined spiral. The resulting movement corresponds to the movement during wobble riveting. 
         [0046]    The formed indents  26 ′ are of a shape which is convex in cross-section, see  FIG. 3 , and circular in plan view, see  FIG. 2 . 
       Step S 7   
       [0047]    In a step S 7 , the housing arrangement  1  produced is further fitted out. Thus, for example, a bearing  35 , see  FIG. 3 , can be installed in the bearing plate  3 . Furthermore, the brush carrier part  12  can be provided with brushes, not shown. An electric motor is therefore ultimately produced. 
         [0048]    The material flow in the radial direction, which results from the above-described wobble or radial shaping method, is identified in  FIG. 2  with two arrows F 1  and F 2  for the indents  26 ′. The material flow F 1 , F 2  causes the bearing plate  3  to be enlarged in the main plane of extension H, in which the indents  26 ′ lie. As shown in  FIG. 2 , the material flow F 1  causes clamping of the bearing plate  3  or of the mutually diagonally opposing lugs  11  with the surfaces  24  of the motor housing case  16 . Furthermore, the material flow F 2  leads to clamping of a respective lug  11  between the two surfaces  25  of the motor housing case  16 . 
         [0049]    By means of the stamping apparatus  2  in accordance with the present exemplified embodiment, the four lugs  11  can be formed at the same time with two indents  26 ′ each. This produces a uniform force distribution during the shaping step, whereby a tipping of the bearing plate  3  about the middle axis Ml can be avoided. Furthermore, it saves time to form the plurality of indents  26 ′ simultaneously. 
         [0050]    Although the invention has been described with the aid of exemplified embodiments it is not limited thereto but can be modified in many ways. In particular, the designs and exemplified embodiments described for the housing arrangement in accordance with the invention can be applied in a corresponding manner to the method in accordance with the invention and to the stamping apparatus in accordance with the invention, and vice versa. Furthermore, reference is made to the fact that “a” does not exclude a plurality in this case. 
       REFERENCE LIST 
       [0051]      1  housing arrangement 
         [0052]      2  stamping apparatus 
         [0053]      3  bearing plate 
         [0054]      4  spigot 
         [0055]      4 ′ spigot 
         [0056]      5  rear side 
         [0057]      6  front side 
         [0058]      7  periphery 
         [0059]      11  lug 
         [0060]      12  brush carrier part 
         [0061]      13  through-opening 
         [0062]      14  indentation 
         [0063]      15  head 
         [0064]      16  motor housing case 
         [0065]      17  periphery 
         [0066]      21  recess 
         [0067]      22  shoulder 
         [0068]      23  receiving region 
         [0069]      24  surface 
         [0070]      25  surface 
         [0071]      26  region 
         [0072]      26 ′ indent 
         [0073]      31  stamp 
         [0074]      32  conical surface 
         [0075]      33  tip 
         [0076]      34  holder 
         [0077]      35  bearing 
         [0078]    F 1  flow direction 
         [0079]    F 2  flow direction 
         [0080]    H main plane of extension 
         [0081]    M 1  middle axis 
         [0082]    M 2  middle axis 
         [0083]    R radial direction 
         [0084]    U peripheral direction 
         [0085]    W 1  angle 
         [0086]    W 2  angle