Patent Publication Number: US-2005135187-A1

Title: Mixing tool receiver on an output shaft of a mixer

Description:
BACKGROUND OF THE INVENTION  
      This invention relates to a mixing tool receiver on an output shaft of a mixer, with a tubular receiver portion into which one shank of a mixing tool can be positively inserted and, at the same time, be twist-proof, and with means for locking the inserted shank in the receiver portion.  
      Agitators and mixers are on the market which are able to mix large volumes of construction materials with the construction material being circulated, as a rule, by rotation of a drum which serves, at the same time, as a vessel for the construction material. However, such mixing machines are designed and economically feasible only for applications where construction material is used by the cubic meter.  
      Manually operable, electrically driven mixing machines are known for stirring and mixing smaller amounts of material and which are also intended for use at construction sites. Stirred and mixed materials are, in particular, ready-mix plasters and mortars, fillers, paints, adhesives and the like.  
      Compared with the prior state of the art, a manually operable mixing machine known by DE 44 40 566 CI shows significant improvements in terms of its handling and security. Thus, in addition to the power controller located on the first handle and which is operable with one hand, there is also a pushbutton as an on/off switch arranged on the second handle, the pushbutton being operated with the other hand. The mixing rods or the mixing rod ends, respectively, are inserted from the bottom into vertically arranged drive output shafts and there held without twisting and secured against axial forces. To be able to do this quickly and simply, a projection on the lower face-side end of the drive output shaft is engaged in a section of a ring welded onto the mixing rod and axial security is provided by means of a screw on the face side. The screw is screwable into an end-side longitudinal thread of the mixing rod end, and the screw head is exposed on the face-side top edge of the drive output shaft.  
      This invention is based on the need of optimizing a mixing tool receiver of the above mentioned species, especially to still further simplify handling.  
     SUMMARY OF THE INVENTION  
      This problem is solved according to the invention by providing a locking device feature having a manually operable slide bushing with a spring-loaded pressure disk slidable on a receiver portion. The locking device has at least one locking bolt guided in a guide channel in the receiver portion. The slide bushing is held axially with a bushing collar on the receiver portion, while an annulus is formed between the receiver portion and the slide bushing, the guide channel in the receiver portion. The guide channel extend obliquely to the longitudinal axis of the receiver portion and the operating direction of the slide bushing, and extends radially outwards to the outside of the receiver portion. The channel is cut so deeply that a cut-through results into the inside area of the receiver portion.  
      The locking bolt is keyed in the guide channel and slidable over the depth of the channel and has such a length that it projects into the annulus in any position with a bolt projection. The bushing collar from the inserting side and the pressure disk in the annulus from the drive side rest against the bolt projection for the purpose of holding and displacing the locking bolt. In a locking position, the locking bolt is displaced by the spring-loaded pressure disk into a radial inside position in the guide channel. The locking bolt protrudes through a cut-through into the inside area of the receiver portion for a locking contact with a locking recess on the shank of the mixing tool. In a release position, the locking bolt is displaced by manually and angularly displacing the slide bushing toward the drive side, by means of the bushing collar, radially outwardly from the area of the locking catch, thus releasing the locking bolt for an inserted shank of the mixing tool.  
      These measures according to the invention allow the mixing tool to be quickly and safely locked in an axial position. For this, only the shank of the mixing tool must be pushed into the tubular receiver portion. Latching the locking bolt into a recess provided on the shank of the mixing tool is then completed without further action by the operating person. Unlocking is easily and quickly done by the operating person simply moving, with a quick flick of the wrist, the slide bushing and thus the locking bolt into the release position.  
      Transmission of forces acting on the mixing tool receiver during the operation of the mixer can be improved by providing two diametrically opposed guide channels which are worked into the receiver portion, with one locking bolt being inserted into each guide channel.  
      In a particularly advantageous aspect, the pressure disk facing the locking bolts is provided with a channel running in the radial direction of movement of the locking bolts. The locking bolts always remain centered in the guide channels during their sliding movement.  
      A controlled sequence of movement of the locking bolts can be achieved by aligning the length of each locking bolt and the wall defining the annulus, i.e. the inside diameter of the slide bushing, so that during their radial outward movement, before leaving the guide channels, the locking bolts come to rest on the wall of the slide bushing.  
      A simply designed, fail-safe structure can be realized in a preferred embodiment such that a pressure spring acting on the pressure disk will surround the receiver portion. The spring is propped within the annulus on a guide ring for the slide bushing which in turn rests on a shoulder of the stepped tubular receiver portion.  
      A rotary engaging connection may be arranged between the mixing tool and tubular receiver portion so that one recess of the receiver portion has a profile corresponding to the shank of the mixing tool. Preferably, the profile is hexagonal.  
      A simple, functionally safe connection between the mixing tool receiver and the output shaft of the mixer is created wherein a drive end section of the receiver portion is provided with an inside thread. A threaded stem of the output shaft provided with an outside thread into which the drive end of the receiver portion can be screwed. The threaded stem simultaneously serves as a stop for the shank of the mixing tool.  
      So that the slide bushing remains easy to handle and use, even under adverse conditions on the construction site a circumferential area of the bushing is provided with a plurality of grooves to ensure an intensive and non-slip contact with the hand of the operating person. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      The construction designed to carry out the invention will hereinafter be described, together with other features thereof.  
      The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:  
       FIG. 1 a  perspective view of a mixing tool receiver with mixing tool and output shaft;  
       FIG. 2  again a perspective view of the mixing tool receiver, with the slide bushing omitted;  
       FIG. 3 a  longitudinal section of the mixing tool receiver in a locking position;  
       FIG. 4 a  longitudinal section of the mixing tool receiver in the release position; and  
       FIG. 5 a  sectional view of the mixing tool receiver along line along V-V in  FIG. 4 . 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT  
      Referring now in more detail to the drawings, the invention will now be described in more detail.  
       FIG. 1  shows a mixing tool receiver  1  of a manually operable mixer, comprising inter alia, a tubular receiver portion  2 , whose inside area  3  is provided with a profile  4 , preferably a hexagonal profile. Tubular receiver portion  2  is surrounded by an axially (longitudinal axis  5 ) movable slide bushing  6  whose circumferential area is provided with a plurality of grooves  7  for better manual handling. A bushing collar  8  forms the face-side end of the slide bushing  6 .  
      A drive side end  9  of tubular receiver portion  2  is provided with an inside thread  10  ( FIG. 3 ) into which a threaded stem  12  of an output shaft  13  of the mixer can be screwed. The threaded stem is provided with an outside thread  11 , with flattenings  14  on both sides provided on the circumference of the output shaft  13  for applying a fork wrench.  
      Inside area  3  of the mixing tool receiver  1  can receive a shank  16  of a mixing tool  17 . The shank is provided with corresponding profile  15 . A circumferential channel  18  arranged in the area of the shank  16  is used, as explained further below, to axially lock mixing tool  17  in mixing tool receiver  1 .  
       FIG. 2  illustrates tubular receiver portion  2 , with slide bushing  6  omitted so that additional functional elements of mixing tool receiver  1  can be seen which are present in an annulus  19  ( FIG. 3 ,  FIG. 4 ) formed between slide bushing  6  and receiver portion  2 .  
      For this purpose, a guide ring  20  is first provided for axially movable slide bushing  6  wherein the ring rests on a shoulder  21  of the stepped tubular receiver portion  2 . On guide ring  20  is positioned a pressure spring  22  surrounding the receiver portion  2 . The pressure spring applys a pressure disk  23  on the opposite side which in turn contacts two diametrically opposed locking bolts  26 ,  27 , inserted into guide channels  24 ,  25  which have been worked into the receiver portion  2 .  
      As can best be seen in  FIGS. 3 and 4 , the guide channels  24 ,  25  are formed in tubular receiver portion  2  with the channel length extending obliquely to the longitudinal axis  5  of the receiver. The guide channels extend radially outward toward the outside of the receiver, and obliquely to the operating direction of slide bushing  6 . The guide channels  24 ,  25  are cut in so deeply that a cut-through  28 ,  29  is formed into the inside area  3  of receiver portion  2 .  
      Each locking bolt  26 ,  27  is inserted positively and slidably along the channel depth of guide channels  24 ,  25 . The bolts have such a length that they project into annulus  19  so that bushing collar  8  and the pressure disk  23  in annulus  19  engage the respective bolt projection for the purpose of joint holding and displacement of locking bolts  26 ,  27 , as can best be seen in  FIGS. 4 and 5 .  
      When the radially inwardly moving locking bolts  26 ,  27  arrive at the channel bottom of guide channels  24 ,  25 , a stop is created for pressure disk  23  on which pressure spring  22  acts. The axial movement of slide bushing  6  is in turn defined by a stop safety ring  30  which is inserted into a circumferential deepening  31  in receiver portion  2 .  
      The pressure disk  23  is equipped on a side facing locking bolts  26 ,  27  with a channel  32  along the radial movement direction of locking bolts  26 ,  27  and receiving them. Here, the two locking bolts are sliding or, respectively, rolling along channel flanks  33 ,  34  and are thus always centrically guided.  
      As results from  FIG. 5  in particular, the length of each locking bolt  26 ,  27  and wall  35  of the slide bushing  6 , defining annulus  19 , are aligned so that the locking bolts will engage, during their radial outward movement prior to leaving the guide channels  24 ,  25 , wall  35  of slide bushing  6  (rests  36 ,  37 ).  
      Mixing tool  17  is now inserted in a positive and torsion-proof axially locking manner into mixing tool receiver I or, respectively, it is removed from the mixing tool receiver  1 , in the following manner:  
      When inserting shank  16  of mixing tool  17  into inside area  3  of tubular receiver portion  2 , there is a torsion-proof catch connection already due to the matching profiles  4 ,  15 . At the same time, locking bolts  26 ,  27  are pushed obliquely, radially outwardly against the spring force of pressure spring  22 . The pressure disk  23  is moved in the same manner in the direction of the output shaft  13 .  
      If, upon further insertion of mixing tool  17 , the circumferential channel  18  comes into the action area of locking bolts  26 ,  27 , the bolts will latch into the circumferential grove  18 . Mixing tool  17  is thus axially locked. Further insertion would also be prevented by threaded stem  12  of output shaft  13  which insofar acts as a stop.  
      Transferring the mixing tool  17  into the release position is by manually displacing slide bushing  6  toward output shaft  13  (arrow  38 ). Locking bolts  26 ,  27  are then displaced by means of the bushing collar  8 , obliquely radially outwardly from the area of the locking catch. The inserted shank  16  of the mixing tool  17  is then released.  
      While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.