Abstract:
A holding device for work pieces to be machined, with a fixture and a vacuum holding block which can be set on the fixture, where an automatic or remotely-controllable mechanical locking device, for holding the vacuum holding block in position on the fixture is provided.

Description:
BACKGROUND 
     The invention relates to holding device for work pieces to be machined, having a fixture and a vacuum holding block which can be set on a fixture. 
     Holding devices of this kind are known in a great number of embodiments. One or more vacuum holding blocks, which carry the work piece to be machined, are set on the fixture. The vacuum holding block is held on the fixture, either mechanically or by means of vacuum, and, in turn, holds the work piece by means of vacuum. The work piece is held by suction by the vacuum holding block and thus prevented from moving. With different work pieces, the vacuum holding block usually occupy different positions on the fixture. This means that in the event of a model change, that is to say, in the event of a change from one shape of work piece to another, the vacuum holding blocks have to be moved on the fixture. This is normally carried out manually. Then the vacuum holding blocks have to be again locked in position on the fixture, which is done either mechanically with clamping devices or pneumatically by means of vacuum. Normally tensioning levers are used as mechanical clamping devices. Since these tensioning levers have to be operated manually, the great expenditure of time in repositioning the vacuum holding blocks at a model change is regarded as disadvantageous. 
     A feature of the invention is therefore to continue to develop a holding device of the type described above in such a way that the vacuum holding block can be locked in position much more rapidly. 
     SUMMARY 
     It is advantageous that by means of an automatic or remotely-controlled mechanical locking device, it is no longer necessary to lock each individual vacuum holding block in position individually. Using the device according to the invention, all the vacuum holding blocks or groups of vacuum holding blocks can be locked in position together. This results in a not inconsiderable savings in time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Additional advantages, features and details of the invention can be derived from the claims and the ensuing description, in which, with reference to the drawing, particularly preferred aspects of the invention are described in detail. The features shown in the drawing, as well as those mentioned in the description and in the claims, can be essential to the invention individually by themselves or in any combination. 
     The drawing shows in each of FIGS. 1 to  5  a cross section of five aspects of the holding device of the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a cross section through a first aspect of the holding device of the invention with a fixture  10 , on which a vacuum holding block  12  is positioned. The fixture  10  has grooves open at the edge  14 , in which pneumatic hoses  16  are carried. The hoses  16  are covered by a clamping band  18  which has a back angle tang  20  on its outside. The vacuum holding block  12  has fingers  22  extending down on its underside which have retaining tangs  24  projecting in the direction of the back angle tang  20 . Both the back angle tang  20  as well as the retaining tang  24  have chamfers, which shift the vacuum holding block  12  in the direction of the fixture  10  when the pneumatic hoses  16  expand and thus press it down on the top side of the fixture  10 . 
     FIG. 2 also shows a fixture  10  with vacuum holding block  12 , where a clamping unit  26  is snapped to the underside of the vacuum block  12 . The clamping unit  26  is equipped with a piston  28  which is carried in a cylinder  30  to be movable vertically. Vacuum can be applied below the piston  28  by means of a suction line  32 . In this way, the clamping unit  26  is displaced in the direction of the fixture  10  and locked against it. In turn, the clamping unit  26  keeps the vacuum holding block from moving. So that the area in which a clamping unit  26  and/or a vacuum holding block  12  is located can be supplied with vacuum, the line  32  is equipped with a valve  34 . This valve  34  is, for example, configured as a momentary valve which opens when the cylinder housing  36  is touching it. Sealing is achieved by gaskets  38 . 
     FIG. 3 also shows a fixture  10  with vacuum holding block  12 , where the vacuum holding block  12 , similarly to the embodiment in FIG. 1, is equipped with fingers  22  on its underside, on which magnetic or magnetizable inserts  40  are provided, which act in the direction of the fixture  40 . Antipoles  42  are furnished on the fixture  10  in immediate proximity to the inserts  40 . Of course, the insert  40  and antipole  42  can also be reversed, i.e. provided on the other component. 
     In the case of the aspect in FIG. 4, the fixture  10  is equipped with spring-loaded ball detents  44 , in which a ball  46  engages a matching recess  48  on the inside of the particular finger  22  of the vacuum holding block  12 . 
     In the case of the aspect in FIG. 5, the vacuum holding block  12  is locked to a retracting rail  50 , where this locking action can be carried out by means of clamping pins  52  or similar. A piston  54 , which can be extended downward and which acts on a crosspiece  56  of the retracting rail  50 , is located inside the fixture  10 . As a result, the retracting  50  is shifted downward, and the vacuum holding block  12  is pressed down on the top side of the fixture  10 . 
     The component  50  can also be made in an L-shape, so that the fixture  10  does not have to be completely enclosed. As a result, one side ofthe fixture  10  can be used for additional applications. 
     The aspects shown in the drawing allow the vacuum holding block  12  to be locked in place automatically on the fixture  10  and/or by remote-control, so that the vacuum holding blocks  12  no longer have to secured individually on the fixture  10 .