Abstract:
The invention relates to a tensioning device, in particular a machine vice, with a base body, with a stationary jaw attached thereto and with a movable jaw opposite this, for whose adjustment there is provided a tension rod, wherein the tension rod comprises a support bearing via which the movable jaw is supported by way of a compression rod. The object of the invention is to specify a tensioning device which permits a quick tensioning also of differently dimensioned subjects and furthermore offers the largest possible protection from contamination of the functional parts. This object is achieved in that the movable jaw is formed lockable at various distances to the stationary jaw with the compression rod, preferably by way of clamping bodies.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a tensioning device, in particular for a machine vice, with a base body, with a stationary jaw arranged thereon and with a movable jaw opposite this for whose adjustment there is provided a tension rod, wherein the tension rod comprises a support bearing via which the movable jaw is supported by way of a compression rod. 
     A tensioning device according to this type is known from the German patent document DE-C1 40 18 284. 
     The patent document describes a machine vice with a force amplifier. The movable jaw is moved to the subject to be tensioned by rotating a sleeve on which there is located an outer thread. 
     A coaxially mounted spindle actuates subsequently a force amplifier which creates the necessary tensioning force between the stationary and movable jaw. 
     The movable jaw cooperates with the sleeve as a spindle-nut drive. With this the movable jaw is the nut and the sleeve is the spindle. 
     With the machining of the subject any occuring swarf may fall downwards onto the thread of the sleeve and thus penetrate into the gap between the movable jaw and the thread of the sleeve. The result of this is an increased wear as well as disturbances on adjusting the movable jaw. Furthermore the application of the movable jaw onto the subject demands a disadvantageous, great time expense since for tensioning firstly by way of rotating the sleeve the movable jaw must be traversed onto the subject. 
     BRIEF SUMMARY OF THE INVENTION 
     It is the object of the invention to specify a tensioning device which permits a quick tensioning also of differently dimensioned subjects and furthermore offers a largest possible protection from contamination of the functional parts. 
     This object is achieved with a tensioning device of the known type in that the movable jaw is designed lockable at various distances to the stationary jaw with the compression rod, preferably lockable by way of a clamping body. The locking may again be easily released and after a subject change may again be locked in a new position. By way of a subsequent rotation of the tension rod which with its thread for example engages into a nut of the base body, the subject may be tensioned in the shortest of times. The locking may also advantageously be effected by clamping bodies which are formed in the manner of a free-wheel. By way of a suitable actuating device the position of the clamping body may be changed such that the locking of the movable jaw may be released again in order to change the distance to the stationary jaw arbitrarily. 
     Advantageously the locking may also be formed with a positive fit when the compression rod comprises catching surfaces into which counter-surfaces of the movable jaw or its movable carrier element are engagingly arranged. The movable jaw after releasing the catching may be easily pushed onto the subject so that there is given a quick adjustability of the jaw. 
     After a renewed catching the jaw may be finely adjusted and the necessary tensioning pressure may be mustered by rotating the tension rod or by actuation of a suitable hydraulic or pneumatic cylinder. 
     The catching of the functional parts is effected between the movable jaw and the compression rod or between its movable transport element and the compression rod. 
     The compression rod at the same time essentially retains its relative position to the tension rod. For the quick adjusting thus the movable jaw or its movable transport element is adjusted relative to the compression rod. 
     The compression rod may simultaneously protect the tension rod from contamination when the compression rod is formed as a sleeve which at least partly envelops the tension rod. The tension and compression rod are at the same time coaxially mounted. 
     The operation of the tensioning device is simplified in that for the sleeve there is provided a tensioning position in which the movable jaw or its carrier element is supported via the sleeve on the tension rod, and there is provided an adjusting position in which the movable jaw is designed displaceable relative to the base body. At a certain angular position there arises a frictional connection, prefereably also a positive-fit connection, between the sleeve and the movable jaw or its carrier element. 
     In another angular position into which the sleeve may be brought by rotation about its longitudinal axis, this frictional connection, preferably also positive-fit connection is released so that the movable jaw or its carrier element may be displaced relative to the base body. 
     The frictional and positive-fit connection of the sleeve and the jaw may be achieved in that on the sleeve there is provided at least one support surface as a catch surface which is preferably formed as a web. 
     If the movable jaw or its movable carrier element comprises channels adapted to the web then the force transmission from the jaw or its movable carrier element is effected via the channels onto the web of the sleeve. 
     The selective switching of a possible frictional connection or the releasing of the frictional connection is with regard to design made particularly simply in that the collar is only provided at one part of the sleeve circumference. 
     By rotating the collar the webs may rise out of the channels since the carrier part below comprises a longitudinal slot which is wider than the side surfaces of the web. 
     With this rotation any swarf located on the sleeve is moved from the spindle upper side into the inner space of the base body, thus away from the spindle. 
     The sleeve is simultaneously advantageously guided in the movable jaw or in its carrier parts in that the recess below comprises a longitudinal slot which is wider than the web of the sleeve. 
     A particularly comfortable adjustment in order to bring the sleeve out of the tensioning position into the movable adjusting position may be achieved when the sleeve is rotatably mounted about its longitudinal axis. 
     The installation of the movable jaw or its movable carrier element and the manufacture of the engagement of the webs into the channel profile is achieved by way of the measure that the movable carrier element has a symmetrical channel profile for the engagement of the webs of the sleeve. 
     The tensioning width may be advantageously changed by way of a 180° rotated installation of the movable jaw on its carrier element. For this however the carrier element is provided with a fastening profile for the movable jaw, which itself is formed non-symmetrically to the channel profile. By rotating the movable carrier element together with the jaw by 180 degrees in the horizontal, the tensioning range of the tensioning device may be comfortably adjusted. For similar tensioning regions by way of this the constructional length of the base body may be kept shorter. 
     A sufficiently high tensioning force for many cases may be achieved when the tension rod is formed as a part of a spindle-nut drive for adjusting the movable jaw, preferably for this comprises an outer thread which is formed engaging into a nut of the stationary jaw or of the base body. 
     By way of the fact that the nut of the spindle-nut drive is formed of plastic, in many cases one may do away with hydraulic, pneumatic or mechanical force amplifiers. 
     Advantageously the design manner of the tensioning device however also permits the provision of a hydraulic, pneumatic or mechanical force amplifier, preferably acting on the spindle. 
     In practice one embodiment form has shown to be particularly successful in which the sleeve has at least one angular position, which is formed catchable, preferably with a friction fit. On operation the thus locked angular position may be differentiated from the position in which the jaw is freely displaceable. 
     The mustered tensioning force may advantageously be easily controlled when a free end of the spindle comprises a square socket which is formed for receiving a standard torque key. Since such a torque key is present anyway on most shop floors by way of the combination of the quick-adjustment with the spindle-nut drive of the tension rod the tensioning force may be mustered in a comfortable and directed manner. Particular further measures are not required. 
     Advantageously it is envisaged that at least one jaw, preferably the stationary jaw comprises a holding device, in particular a holding edge. By way of this it is possible to grip the tensioning device at the holding device and to transport it. 
     The safety on cleaning the tensioning device is advantageously increased in that at least one jaw comprises a cover plate which preferably is fastened with a screw. In the heads of the fastening screws there accumulates swarf which then on blowing out of the tensioning device may injure the operator. By way of the use of a cover plate the fastening screws are covered so that here no dirt may accumulate. Preferably the cover plate is fastened with only one centric screw. 
     Further dirt accumulation may be advantageously avoided in that the groove is not designed continuous. 
     The rotating of the sleeve is simplified in that the grip is at least partly knurled. The knurling has furthermore the advantage that it forms a marking. The left end of the knurling before actuation of the tension rod bears flush on the base body. Without the knurling there exists the danger that the operator does not notice that the spindle-nut drive is overwound which has the result that the tension rod is pressed against the lid of the base body. By way of the knurling the operator may much better estimate how much distance there is still present between the lid and the tension rod. 
     It is advantageously envisaged that in the grip there is incorporated a marking, preferably a flute. This flute is in the basic condition the distance to the base body about which the tension rod may be maximally rotated. If the marking after actuation of the tension rod bears flush on the base body a further rotation of the tension rod need not take place. 
     One advantageous embodiment of the invention envisages that on the left end of the nut there are arranged disk springs. The tension rod on actuation is pressed against these springs by which means a pressure is exerted onto the tension rod. This pressure build-up is an additional precautionary measure which is to remind the operator that the tension rod is no longer distanced far from the maximal abutment. 
     By way of the fact that the movable jaw comprises grip windows the displacement of the jaw by hand is simplified. 
     In order to prevent an excessive force build-up on the subject it is advantageously envisaged that the nut is formed as a sliding clutch. If the build-up tensioning force exceeds a maximum value, the nut slides through, by which means a force limitation takes place. 
     A constructional simple measure in the design of the sliding clutch lies in setting the nut between two O-rings. The pressing force is matched such that on exceeding the maximal allowable tensioning force a sliding-through of the nut is effected. 
     The stability of the tensioning device is increased in that the nut is formed of metal, preferably bronze or brass. 
     The invention is described in a preferred embodiment example by way of example with reference to the drawings, wherein further advantages of the invention may be deduced from the details of the drawings. Parts which with regard to function are the same are provided with the same reference numerals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The Figures of the drawing show individually: 
     FIG. 1 an axial section through the machine vice according to the invention, 
     FIG. 2, a view according to arrow A in FIG. 1 with 3 various catching positions of the movable jaw, 
     FIG. 3, shows the same view as FIG. 2 in a different position, 
     FIG. 4 a schematic functional sketch of a tensioning device with a clamping body and 
     FIG. 5 a plan view of the movable jaw. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1,  1  indicates the machine vice according to the invention. It consists of a base body on whose one end there is arranged a stationary tensioning jaw  3 . Additionally in the base body  2  there is mounted a movable tensioning jaw  4 . A subject which is not shown is tensioned between the tensioning surface  5  and  6  of the tensioning jaws  3  and  4 . The tensioning forces which occur with this are accommodated by a tension rod  7 . 
     This tension rod  7  is designed as a spindle whose thread  8  engages into a plastic nut  9  of the base body. 
     The movable jaw  4  is via a suitable positive-fit connection as a fastening profile rigidly connected to its carrier element  10 . The carrier element on the one side comprises channels  11  into which the webs  12  of a sleeve  13  engage. By way of this engagement into the channel profile there also arises a positive-fit connection between the sleeve  13  and the carrier element  10 . 
     The sleeve  13  is for its part axially passed through by the tension rod  7 , wherein the sleeve  13  in the region of the free end of the tension rod  7  is supported on this so that the sleeve  13  acts as a compression rod. 
     Since the sleeve  13  and the tension rod  7  are rotatable relative to one another, between the right, outer end and the sleeve  13  and the spindle  7  there is provided a thrust bearing. The sleeve  13  is supported thus via the thrust bearing  14  on a disk spring assembly  15  which in turn via the divided support ring  16  is supported on the collar  17  in order to introduce the occuring tensioning forces on the collar  17  into the tension rod  7 . 
     A grip  18  is connected to the sleeve  13  in a rotationally fixed manner by way of pins  19  so that by rotating the grip  18  the angular position of the sleeve  13  may be adjusted. 
     The tensioning forces engaging on the jaw  4  are thus via pegs  20  transmitted onto the carrier element  10 . From here they are transmitted via the stationary-jaw-side surfaces of the channels onto the support surfaces of the webs  12 . The sleeve  13  leads these then via the thrust bearing  14  onto the spring assembly  15 , support ring  16  and the collar  17  onto the tension rod  7 . The flow of force is then from the tension rod  7  closed via the outer thread  8 , nut  9  and tensioning jaw  3 . 
     In the intermediate space between the tensioning surfaces  5  and  6  there is laterally provided a swarf exit opening  21  within the vice. By way of a sealing ring  22  the swarf is prevented from entry into the intermediate space between the sleeve and the spindle. The sealing ring  23  prevents the entry of dirt into the gap of the thread between the spindle thread  8  and the nut  9 . 
     An abutment ring  24  which is fastened on the tension rod  7  prevents the axial displacement of the sleeve  13  in the direction of the fixed jaw  3 . 
     At the free end of the tension rod  7  by way of screws  25  there is fastened an adapter ring  26  which has a square socket  27  into which a standard torque key may be inserted. The screws  25  tension the adapter ring  26  rigidly with the divided support ring  16  and fix the adapter ring  26  with the associated square  28  on the tension rod  7  in a rotationally fixed manner. 
     The fixed jaw comprises a holding device  39  in the form of a holding edge. This simplifies the transport of the tensioning device. 
     The jaws  3 ,  4  comprise cover plates  40 ,  41 . These cover the fastening screws  42  of the jaws  3 ,  4  by which means it is advantageously avoided that here there accumulates swarf. The cover plates  40 ,  41  are in each case fixed with a centric screw  43 . 
     The groove  44  in which the peg  20  is guided is formed laterally closed. With a continuous groove  44  swarf would accumulate therein. 
     The grip  18  is knurled. Before actuation of the tension rod  7  the left end of the knurling bears flush on the base body  2 . The knurling is displaced by the actuation of the tension rod  7  into the base body  2 . By way of the knurling the operator may estimate how far the tension rod  7  has already been traversed into the base body  2 . 
     At a twelve millimeter distance from the left end of the knurling there is incorporated a marking  45  in the form of a flute. As soon as the flute and the base body  2  are flush the maximal allowable screwing-in position of the tension rod in the nut  9  is achieved. 
     On the left side of the tension rod  7  there are arranged disk springs  46 . If the tension rod  7  is screwed far into the nut  9  the tension rod  7  abuts against the springs  46  by which means a pressure is exerted onto the tension rod  7 . This pressure build-up serves the operator as a indication that the maximal allowable screwing-in position of the tension rod  7  is achieved. 
     The nut  9  is formed as a sliding clutch. For this the nut  9  is set between two O-rings  48 . If the built-up tensioning force exceeds a maximum value a sliding through of the nut  9  occurs. 
     FIG. 2 shows a view of the tensioning device according to the invention from the view according to arrow A in FIG.  1 . The spindle  7  is located in the centre. It passes through the sleeve  12  which in FIG. 2 points downwards. The side surfaces of the web  12  are indicated at  29 . These continue vertically in the sleeve  13  so that the sleeve comprises deepenings corresponding to the broken lines which here in the region between the webs result is a prismatic outer surface. 
     These deepenings render the sleeve particularly sensitive to dirt since in these regions the gap to the carrier element  10  becomes particularly large. 
     The carrier element  10  is led within the base body  2  by way of two lateral guide ledges. The guide ledges  30  engage into a corresponding groove  31  of the carrier element  10 . 
     In the represented position of the web  12  the carrier element  10  may be axially displaced along the guide ledge  30 . Any swarf present on the sleeve is conveyed from the edge  34  into the web intermediate spaces. The edge  34  is adapted to the outer contour of the recess for the sleeve in the carrier element. The recess  32  comprises on the lower side a slot  33  which exceeds the width of the web  12 . Swarf which has entered in the intermediate space may fall out through this opening of the slot  33 . Furthermore in this manner the web  12  is released so that the carrier element  10  is displaceable. 
     By way of a resilient catch  49  shown in FIG. 1 the vertical position with a manual rotation of the sleeve  13  may be easily found. 
     FIG. 3 shows the same view as FIG. 2 but at a position of the sleeve  13  in which the sleeve  13  is locked with the carrier element  10 . 
     For this purpose the sleeve  13  is brought into a position rotated by 180 degrees with respect to FIG.  2 . With this rotational movement the web  12  immerses into the channels  11  of the carrier element  10 . On account of the prismatic configuration of the web intermediate spaces of the sleeve, any dirt is conveyed by this rotation downwards so that it may fall out through the longitudinal slot  33 . 
     In the position shown in FIG. 3 which likewise is feelably locking to the operating person, there exists a positive-fit between the sleeve and the carrier element  10 . By rotating the tension rod  7  there is then effected a fine movement of the movable jaw  4 . 
     The tensioning device according to the invention may be changed in a varied manner within the scope of the invention. 
     For example instead of the spindle nut  9  also a hydraulic or pneumatic tensioning device may be provided. 
     However also instead of the spindle-nut drive, mechanical force amplifiers may be applied. 
     The insertion end for the spindle may also be provided at the other end, or the nut of the spindle may be displaced to the other side of the spindle. 
     Instead of a positive-fit locking this locking may also be realised also non-positively, for example by way of a clamping body. One possibility is shown in FIG. 4 with which a clamping plate assumes the job of a clamping body. The compression rod  13  is at the same time formed as a sleeve which on the outside however comprises a smooth surface. 
     If the movable jaw  4  is displaced in the direction of the fixed jaw no clamping takes place. The clamping plate  35  is passed through by the sleeve  3 . On displacing, the plate may pivot about the pivot bearing  36  against the compression force of the spring in the direction of the movable jaw so that there arises sufficient play for the sleeve  13  in the opening  37  of the clamping plate in order to be able to displace the plate on the sleeve. 
     On displacing in the opposite direction as a result of the force of the spring  38  the plate chocks on the sleeve so that the movable jaw is locked on the sleeve  13 . 
     The locking may be released in that the plate  35  is moved against the force of the spring in the direction of the movable jaw by hand or by way of other suitable actuating devices. In this condition the distance of the jaws may be freely changed. 
     In this manner a universally applicable tensioning device may be created which permits a quick adaptation of the tensioning width to the subject to be tensioned and furthermore is particularly insensitive to dirt with respect to the changing conditions of application in the manufacturing operation. 
     In FIG. 5 there is shown a plan view of the movable jaw  3 . On both sides of the jaw there are incorportated grip windows  47  which permit a simple displacing of the jaw  3 . The cover plate  41  is fixed by a central screw  43 . The groove  44  is not formed continuous but is closed at the sides. 
     List of Reference Numerals 
       1  machine vice 
       2  base body 
       3  fixed jaw 
       4  movable jaw 
       5  tensioning surface 
       6  tensioning surface 
       7  tension rod 
       8  thread 
       9  nut 
       10  carrier element 
       11  channel 
       12  web 
       13  sleeve, compression rod 
       14  thrust bearing 
       15  disk spring assembly 
       16  support ring 
       17  collar 
       18  grip 
       19  pin 
       20  peg 
       21  swarf exit opening 
       22  sealing ring 
       23  sealing ring 
       24  abutment 
       25  screw 
       26  adapter ring 
       27  square socket 
       28  square 
       29  side surface 
       30  guide ledge 
       31  groove 
       32  recess 
       33  slot 
       34  edge 
       35  clamping plate 
       36  pivot bearing 
       37  opening 
       38  compression spring 
       39  holding device 
       40  cover plate 
       41  cover plate 
       42  fastening screw 
       43  centric screw 
       44  groove 
       45  marking 
       46  disk springs 
       47  grip window 
       48  O-rings 
       49  resilient catch