Abstract:
A grinding device is specified, comprising a housing in which a tool spindle for driving a tool is mounted, comprising a protective hood which can be locked on the housing, and comprising means which allow the tool spindle and the protective hood to be locked. An actuating device is provided which is displaceable on the housing between a first position in which the tool spindle is released and the protective hood is locked against rotation and a second position in which the tool spindle is locked against rotation and the protective hood can be adjusted in the angular position thereof on the housing.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority from German patent application 10 2010 044 613.0, filed on Sep. 1, 2010. The entire content of this priority application is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a grinding device, comprising a housing in which a tool spindle for driving a tool is mounted, comprising a protective hood which can be locked on the housing, and comprising means which allow the tool spindle and the protective hood to be locked. 
         [0003]    Such grinding devices are known in principle in the prior art. 
         [0004]    There are also embodiments of such grinding devices in which the tool spindle together with the tool is accommodated on an extension arm on the actual drive, which is connected to the tool spindle via a belt drive in the housing of the extension arm (cf. DE 38 41 644 A1). 
         [0005]    In this case, the rotary movement of the drive motor is transmitted to a belt pulley of the extension arm via the angular gear unit. Likewise located at the other end of the extension arm is a belt pulley which is coupled to the actual tool spindle, to which a tool, for instance a grinding disc, is fastened. 
         [0006]    In addition, such devices have an adjustable protective hood, which is intended to keep flying sparks away from the operator, and a spindle lock. Although the drive machine itself often already has a spindle lock, the spindle should be capable of being locked on the extension arm, since otherwise the belt drive could slip during the tool change. 
         [0007]    Therefore, in addition to the switch for activating the motor, such grinding devices also have two important actuating devices: on the one hand a device for locking the tool spindle and on the other hand a device for locking the protective hood in the desired working position. 
         [0008]    In addition, it is desirable that the protective hood cannot be released from the housing in the position in which it can be rotated, since otherwise the protective hood could fall down unintentionally. There is therefore also a third actuating device, namely for releasing the protective hood from the housing. 
         [0009]    In view of this it is a first object of the invention is to disclose an improved grinding device which permits simplified operation. 
         [0010]    It is a second object of the invention to disclose a grinding device which is particularly suited as a fillet weld grinding machine. 
         [0011]    It is a third object of the invention to disclose a grinding device with a protection hood that can be detached. 
         [0012]    It is a forth object of the invention to disclose a grinding device with a protection that can adjusted into different angular positions and locked in different angular positions. 
         [0013]    It is a fifth object of the invention to disclose a fillet weld grinding device that be easily used. 
       SUMMARY OF THE INVENTION 
       [0014]    According to a first aspect these and other objects are achieved by a grinding device, comprising: 
         [0015]    a housing; 
         [0016]    a tool spindle received within said housing for driving a tool; 
         [0017]    a protective hood which can be locked on said housing; 
         [0018]    a locking arrangement engaging said tool spindle and said protective hood for selective locking; and 
         [0019]    an actuating device arranged is on said housing displaceably between a first position in which said tool spindle is released and said protective hood is locked against rotation, and between a second position in which said tool spindle is locked against rotation and said protective hood can be angularly adjusted on said housing. 
         [0020]    The object of the invention is achieved in this way. 
         [0021]    According to the invention, an actuating element displaceably mounted on the housing makes it possible both to release the tool spindle and lock the protective hood against rotation in the first position and to lock the tool spindle against rotation with simultaneous adjustability of the protective hood in the second position. This can be achieved according to the invention by a single actuating device. The actuating device therefore interacts with both the tool spindle and the protective hood in order to ensure, in the first position, release of the tool spindle and locking of the protective hood against rotation and in order to permit, in the second position, locking of the tool spindle against rotation and adjustability of the protective hood in the angular position. 
         [0022]    In this way, much easier actuation in conjunction with a simplified construction is ensured. 
         [0023]    In a further configuration of the invention, the actuating device also has a third position in which the protective hood can be released from the housing. In this position, the tool spindle can be freely rotatable or can also be locked against rotation. 
         [0024]    For the operator, this third position differs noticeably from the first and second positions, such that release of the protective hood is possible only in this third position. This third position may be, for example, an intermediate position between the first and the second positions, in which third position the actuating device is located in a certain position. On the other hand, this third position could also be reached, for example, by another movement of the actuating device, such as, for instance, by a lateral movement, by overcoming a relatively powerful spring or in some other way. In this way, the protective hood can be released from the normal locking and then removed from the housing. 
         [0025]    Much easier actuation of the grinding device is obtained overall. The grinding device can be grasped and held with one hand on the extension arm, i.e. on the housing on which the drive belt runs. The actuating device can be operated with one finger of the holding hand. The second hand remains free for releasing the tool or for adjusting or removing the protective hood. 
         [0026]    In an advantageous development of the invention, the actuating device has a slide which is displaceably accommodated on the housing and which is displaceable between the first position, in which the slide acts on the protective hood in order to lock the latter against rotation, while the tool spindle is released, and the second position, in which the tool spindle is locked against rotation and the protective hood can be adjusted in the angular position thereof on the housing. 
         [0027]    The possibility of changing over between the two positions can be realized in an especially simple manner through the use of a slide which is displaceable between the first and the second positions. 
         [0028]    To this end, the slide can have, for example, a first projection which acts in the second position on the tool spindle in order to lock the latter against rotation, a second projection, furthermore, being provided on the slide, said second projection acting in the first position on the protective hood in order to lock the latter against rotation. 
         [0029]    Thus, on the one hand, locking or release of the tool spindle and, on the other hand, release or rotation of the protective hood can be made possible in a simple manner through the use of two projections on the slide. 
         [0030]    In an additional development of this embodiment, at least one locking element on the tool spindle is assigned to the first projection in order to ensure locking of the tool spindle in the second position. 
         [0031]    In this way, not only frictional locking but also positive locking of the tool spindle can be ensured in order to achieve especially reliable locking of the tool spindle against rotation. 
         [0032]    Furthermore, according to a further embodiment of the invention, a plurality of recesses in the protective hood are assigned to the second projection, in which recesses the second projection can be latched in various angular positions in order to ensure locking of the protective hood in the first position. 
         [0033]    A means of adjusting the protective hood in various angular positions can thus be achieved in a simple manner. 
         [0034]    According to a further configuration of the invention, the first projection and the second projection project from the slide in different directions. 
         [0035]    A changeover between the first position and the second position can thus be achieved by a single movement of the slide, that is to say a combined changeover between locking of the protective hood with simultaneous release of the tool spindle on the one hand and locking of the tool spindle with simultaneous release of the protective hood on the other hand. 
         [0036]    In this way, the two functions, namely release of the tool spindle and locking of the protective hood in the first position and locking of the tool spindle with simultaneous release of the protective hood for rotating in the second position, can be achieved in an especially simple manner by displacing the slide. 
         [0037]    In a further configuration of the invention, the slide is moved into the first position in a preloaded manner by a preloading means, in particular by a spring. 
         [0038]    In this way, the slide is regularly in the first position, and so the tool spindle is freely rotatable and the protective hood is locked. It is not until the slide is actively actuated against the action of the spring that the actuating device can thus be shifted into the second position. 
         [0039]    In a further configuration of the invention, the slide has an insert made of a strengthened material, in particular steel, on which the first projection is formed. 
         [0040]    Furthermore, the slide can be made of plastic, in which case the second projection can be formed in one piece with the slide. 
         [0041]    Simple and cost-effect production of the slide from plastic is made possible by these measures, and at the same time wear of the first projection caused by engagement on the tool spindle is avoided. 
         [0042]    According to a further configuration of the invention, a guide lane is provided on the protective hood, from which guide lane recesses project radially outwards and at which at least one aperture is provided in the circumferential direction, said aperture allowing the guide lane to be released from the second projection by rotation of the protective hood when the slide is in the third position in order to allow the protective hood to be removed. 
         [0043]    In this way, release of the protective hood is made possible in an especially simple manner when the slide is located in the third position. This third position may be, for example, an intermediate position between the first and the second positions. In the third position, the second projection is released from the recesses in the radial direction, such that the protective hood can be removed by rotation when the second projection is in alignment with the aperture in the circumferential direction. 
         [0044]    According to a further embodiment of the invention, the slide has an actuating button which can be actuated from outside via an aperture in the housing. 
         [0045]    In this way, the actuating device can be activated in a simple manner by engaging the actuating button in the aperture in the housing. 
         [0046]    In this case, the actuating button is preferably arranged in such a way that inadvertent actuation is not possible. To this end, the actuating button can lie, say, within the housing contour, that is to say it can be reached, but it does not project beyond said housing contour. 
         [0047]    According to a further embodiment of the invention, guides on the housing are assigned to the slide, said guides allowing the slide to be displaced in the radial direction of the tool spindle. 
         [0048]    In this way, the slide is reliably guided between the first and the second positions and is locked against rotation. 
         [0049]    As already mentioned above, the tool spindle can preferably be driven via a belt drive, the grinding device preferably being designed as a fillet weld grinder. 
         [0050]    It goes without saying that the abovementioned features and the features still to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0051]    Further features and advantages of the invention can be gathered from the description below of preferred exemplary embodiments with reference to the drawing, in which: 
           [0052]      FIG. 1  shows a perspective view of a grinding device according to the invention; 
           [0053]      FIG. 2  shows a partial longitudinal section through the grinding device according to  FIG. 1  in the region of the tool spindle and of the protective hood, specifically in a first position in which the drive spindle is freely rotatable and the protective hood is locked; 
           [0054]      FIG. 2   a  shows a partial cross section of the grinding device according to  FIG. 2 ; 
           [0055]      FIG. 3  shows a partial longitudinal section through the grinding device according to  FIG. 1  in the region of the tool spindle and of the protective hood, specifically in a second position in which the tool spindle is locked and the protective hood is rotatable; 
           [0056]      FIG. 3   a  shows a partial cross section of the grinding device according to  FIG. 3 ; 
           [0057]      FIG. 4  shows a partial longitudinal section through the grinding device according to  FIG. 1 , although the extension arm is not shown for the sake of clarity, specifically in a third position in which the protective hood can be removed; 
           [0058]      FIG. 4   a  shows a partial cross section of the grinding device according to  FIG. 4 ; and 
           [0059]      FIG. 5  shows a perspective detailed view of the slide from below, inserted into the top part of the housing and guided on guides. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0060]    A grinding device according to the invention is shown in a perspective view in  FIG. 1  and is designated overall by the numeral  10 . 
         [0061]    The grinding device  10  has a drive  11  in the form of an angle grinder drive, having a handle  12  in which a motor  14  is accommodated and on which a gear unit  16  in the form of an angular gear unit is flange-mounted. Accommodated on the outer end of the gear unit  16  is an elongated extension arm  18  which is enclosed by a housing  20 . A tool spindle, in which a tool  22  in the form of a grinding or cut-off tool is clamped in place, and a protective hood  24 , which is accommodated in such a way that it can be shifted into various positions, are located on the outer end of the extension arm  18 . An aperture  21 , into which a finger can reach, is provided approximately in the centre of the extension arm  18  in the housing  20 . 
         [0062]    A belt drive which transmits the output movement of the gear unit  16  of the drive  11  to the tool spindle is accommodated in the extension arm  18 . 
         [0063]    Such a grinding device can be used in particular as a “fillet weld grinder”. 
         [0064]    The grinding device  10  has an actuating device (cf.  FIG. 2 ) which is designated overall by  32  and which can be activated via an actuating button  56  when a finger reaches into the aperture  21  in the housing  20 . Locking of the tool spindle and of the protective hood and removal of the protective hood in certain respective positions can be controlled with the actuating device  32 . 
         [0065]    Shown in  FIGS. 2 and 2   a  is a first position in which the tool spindle  26  is freely rotatable and the protective hood  24  is locked against rotation. 
         [0066]      FIG. 2  shows in more detail the bearing arrangement of the tool spindle  26  by means of two bearings  52  and the drive by means of a belt drive  54 , of which only the belt  55  can be seen. 
         [0067]    At the outer end of the tool spindle  26 , the tool  22  is clamped in place between an outer flange  23  and a mating flange  25 . 
         [0068]    The construction and the functioning of the actuating device  32  are explained in more detail below. 
         [0069]    The actuating device  32  has a slide  34  which is displaceably guided in the radial direction of the tool spindle  26  between two guide webs  35 . The slide  34  is preloaded in a direction away from the tool spindle  26  by a spring  42  embodied as a compression spring and bears from inside against a wall of the housing  20  in the first position shown in  FIGS. 2 and 2   a , said wall being defined by the aperture  21 . The spring  42  is guided and secured in position on a mandrel  44  between a spring receptacle  40 , which is accommodated on the housing  20  in a fixed position, and the actuating button  56  (cf.  FIG. 2   a ). The slide  34  is made of plastic in one piece with the actuating button  56  and the mandrel  44 , for example as a plastic injection moulding, and has, as can be seen in  FIG. 2 , a roughly rectangular outline. 
         [0070]    Accommodated on that end region of the slide  34  which faces the tool spindle  26  is a steel insert  36 , from which a first projection  38  projects beyond the outline of the slide  34  in the direction of the tool spindle  26 . A lug ring  28  is pressed onto the tool spindle  26  or is secured against relative rotation in another manner. Four lugs  30  which project outwards are provided at equal angular distances apart on the lug ring  28 . 
         [0071]    Furthermore, a second projection  50  is provided on the slide  34 , said projection  50  being offset from the first projection  38  by a certain amount in the direction of the spring receptacle  40  and projecting upwards into the drawing plane in the illustration according to  FIG. 2 . This second projection  50  is therefore likewise shown hatched in  FIG. 2 , is of rectangular design and is enclosed by two correspondingly shaped legs of the insert  36 . The second projection  50  therefore serves at the same time to fix and position the insert  36  inside the slide  34 . 
         [0072]    In the position shown in  FIGS. 2 and 2   a , the second projection  50  interacts with an associated recess  46  in the protective hood  24 . 
         [0073]    As can be seen from the illustration according to  FIG. 4 , the protective hood  24  has a guide lane which is designated overall by  48  and in which a total of five recesses  46 , extending radially from the tool spindle  26 , are arranged at equal angular distances apart. Furthermore, the guide lane  48  has apertures  58 ,  59  which are offset radially inwards relative to the recesses  46  and which enable, in an intermediate position, the second projection to move out of the guide lane  48  in the circumferential direction. 
         [0074]    In  FIG. 4 , the second projection is shown in this position by  50 ″ precisely inside the aperture  58  at one end of the guide lane  48 . 
         [0075]    In the first position, which is shown in  FIGS. 2 and 2   a  and in which the slide  34  is located in the end position remote from the tool spindle  26 , the second projection  50  engages in one of the recesses  46  in the protective hood  24 , such that the protective hood  24  is locked against rotation. In  FIG. 2 , the associated recess  46  is concealed by the extension arm  18 . In  FIG. 2   a , however, it can be seen how the second projection  50 , with a lug at the end, engages in the recess  46  and thus locks the protective hood  24 . Furthermore, in the first position, the first projection  38  is at a sufficient distance from the lugs  30  of the lug ring  28 . The tool spindle  26  is therefore freely rotatable in the first position, while the protective hood  24  is locked by means of the second projection  50 . 
         [0076]    If the slide  34  is now displaced in the direction of the tool spindle  26  by the actuating button  56  being pushed in against the action of the spring  42 , the first projection moves into the position  38 ′ right up to the lug ring  28  of the tool spindle  26  and locks the tool spindle  26  against rotation by bearing against a lug  30 . At the same time, the second projection is located in a position designated by  50 ′, and so said projection is released from the underlying recess  46  of the protective hood  24 . 
         [0077]    The protective hood  24  can therefore be rotated within the guide lane  48  in this second position, in which the tool spindle  26  is locked against rotation. 
         [0078]    If the actuating button is released from the position  56 ′ shown in  FIGS. 3 and 3   a , the actuating button moves again under the effect of the spring loading in a direction away from the tool spindle  26 , such that the locking of the tool spindle  26  is neutralized and the protective hood  24 , with suitable rotation, can be locked with one of the recesses  46  on the second projection  50 , such that the first position depicted in  FIGS. 2 and 2   a  is again obtained. 
         [0079]    The intermediate position briefly mentioned above, namely the third position, in which it is possible to release the protective hood  24  from the housing  20 , is now shown in  FIGS. 4 and 4   a . In this third position, the slide is located in an intermediate position designated by  34 ″, which is reached by appropriate actuation of the actuating button  56 ″. In this intermediate position, the second projection lies in an intermediate position, designated by  50 ″, between the first position and the second position, such that the second projection is in alignment either with the one aperture  58  at the one end of the guide lane  48  or with the second aperture  59  at the other end of the guide lane  48 . The protective hood  24  can therefore be moved out of the second projection  50 ″ by a further rotation with the guide lane  48  and can therefore be released and removed from the housing  20 . 
         [0080]    To this end, a marking is expediently located on the actuating button  56 , said marking indicating how far the actuating button  56  has to be pushed in in order to reach this third position  56 ″ in which removal and fastening of the protective hood  24  is made possible.