Abstract:
In order to control, in a wire shaping apparatus with a rotatable wire intake device ( 10 ), friction of the wire at the bore wall of a wire holder ( 52 ) which finally leads the wire towards the shaping station, and in order to reduce it to zero if necessary, it is suggested to provide said apparatus, the wire holder ( 52 ) of which can be rotated programmably controlled about the wire axis, with a remote controllable wire brake device ( 114 ) which acts radially upon the wire being fed along, and the wire brake device is programmably controlled.

Description:
This is a division of application Ser. No. 09/085,082, filed May 26, 1998, now U.S. Pat. No. 6,092,565. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to an apparatus for shaping wire. 
     Apparatus for shaping wire is disclosed in U.S. Pat. No. 5,363,681 (WAFIOS FTU  3 ). This apparatus has a flange ( 118 ) which is firmly attached to the bearing body and is provided with a prismatic part ( 140 ) on which a radially adjustable wire guide attachment ( 136 ) is provided which has an eccentric wire guide bore ( 137 ) and which cooperates with a cutting tool ( 14 ). The wire guide ( 130 ) ending at the attachment ( 136 ) always rotates synchronously with the intake roller pairs about the wire axis. This apparatus has already been modified in such a way that the prismatic part at the now rotatable flange, as one unit together with the wire holding attachment, can be guided in a circular movement around the wire axis so that the friction between the wire and the attachment can be eliminated. This is also suggested by DE 197 36 468 A1 (ITAYA) in which, however, the stationary wire guide ( 80 ) between the stationary wire intake rollers ( 14  and  15 ) on the one hand, and the rotatable wire holder ( 70 ) on the other hand, generates friction when the wire is twisted about its lengthwise axis. 
     A particularity of DE 197 36 468 A1 is a remote controlled rotatable wire grip ( 64 ) provided at the rotatable wire guide ( 70 ) for non-rotatable clamping of the wire whereby said wire guide can not turn the wire about its own axis like clamping intake rollers do. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to considerably improve the geometric shape accuracy of the three-dimensional wire bodies produced by the apparatus for shaping wire disclosed by U.S. Pat. No. 5,363,681 and this with an unchanging result, and to increase the output of the apparatus, i.e. to achieve a quality increase of finished workpieces and a performance increase of the apparatus for shaping three-dimensional workpieces. 
     This is achieved by the invention at first by the fact that the outlet wire guide installed rigidly at the bearing body of the rotatable wire intake device of the apparatus for shaping wire according to U.S. Pat. No. 5,363,681 is replaced by a known rotatable wire guide, and secondly, that the rotatable wire guide is equipped according to this invention with a programmably controlled and power controlled wire “braking” device, the shaping process servomotor of which is controlled by the machine control together with the servomotors of the other device aggregates of the apparatus. 
     Due to the common but separately arranged ‘rotating wire intake’ and ‘rotating wire guide’ the azimuthal friction during a synchronous run is completely eliminated, since no relative movement between the wire intake and the wire guide takes place when the wire is turned. This is of special advantage, because the friction between the wire and the wire guide during the shaping process leads to inaccuracies in the workpiece geometry. Further, ‘unlimited’ turning of the wire (to-and-fro) is possible even when the wire guide stands. 
     It goes without saying that the rotating wire intake and the rotating wire guide can also be operated asynchronously. 
     The aforementioned advantage of friction elimination can be optimized by the wire brake device according to the invention which operates programmably controlled and power controlled in each individual section of operation of the workpiece to be produced. The braking pressure on the wire can be programmably controlled in such a way that during the shaping process, for example, when an already finished part of the workpiece in the wire shaping area turns down, a damping effect is generated. Or with an appropriate programmably controlled brake pressure, a supporting or stabilizing effect can be obtained during shaping operations of the standing wire so that the wire and, if necessary, its already finished portion can not twist in its angular position. Further, the brake pressure on the incoming wire can be determined by the computer in such a way that, for example, during winding the play between the incoming wire and the wire guide is reduced so precisely that an exact spring form and spring pitch is obtained during the winding process, whereas feeding of the wire is still possible. 
     Thus it will be possible to compensate for too much play between the wire and the guide resulting, for example, from wear of the wire guide (enlarged wire guide bore), or from too much play resulting from wire diameter tolerances. 
     These improvements on every individual production section will considerably increase the quality of the finished workpieces and this in a constant way even for large scale manufacturing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following text the invention will be explained in detail with reference to the preferred embodiment of the apparatus according to the invention illustrated by way of an example shown schematically in the drawings in which 
     FIG. 1 is a side view of the embodiment partly broken away 
     FIG. 2 is a front view of a portion of the embodiment shown in FIG. 1 
     FIG. 3 is a magnification, partly in section, of detail A of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a rotatable wire intake device  10 , a rotatable wire guide device  12  with a wire brake device  114  (FIG.  3 ), a wire shaping station  14  and a cutting device  16  (FIG. 2) for cutting a certain workpiece length from the endless wire  18 , all of a CNC-controlled apparatus for shaping wire. 
     The used rotatable CNC-controlled wire intake device  10  for intermittent feed of the wire  18  into the wire shaping station  14  and for CNC-controlled twisting of the wire  18  about a predetermined angular value is that disclosed by U.S. Pat. No. 5,363,681. 
     However, the known CNC-controlled rotatable wire intake device  10  disclosed by U.S. Pat. No. 5,363,681 comprises an intake housing  22  in which a total of four wire intake rollers  24  are rotatably mounted to push the wire  18  forwards into the wire shaping station  14 . The rollers  24  are arranged pairwise and are driven intermittently and are programmably controlled, and are speed controlled, to rotate selectively forwards and backwards, by a first CNC controllable servomotor  26  by means of two toothed belt transmissions of which only one  28  is shown here. 
     In order to turn the intaken wire  18  clamped between the wire intake rollers  24 , the intake housing  22  of the wire intake device  10  itself is rotatably mounted on a bearing body  30  attached to the apparatus for shaping wire. The intake housing  22  is driven intermittently, is programmably controlled, and is rotated selectively forwards and backwards, by a second controllable servomotor  34  by means of a toothed belt transmission  36 . 
     On the left side of FIG. 1, the wire intake side of the rotatably mounted intake housing  22 , a usual wire straightening device  38  with horizontally and vertically arranged straightening rollers is attached to the intake housing extension to straighten the wire  18  before it is introduced between the intake rollers  24  after passing through the intake housing  22 . 
     On the right front side of the bearing body  30  of FIG. 1, a two-part wire guide  48  consisting of an upper part  42  and a lower part  44  and supported by the intake housing  22  is mounted rotatably on the bearing body  30  as part of the wire guide device. The wire guide  48  extends to the left until the outlet of the right wire intake roller pair and to the right as it approaches an eccentric wire holder  52 . 
     The wire holder  52  is part of a rotatable wire guide device  12 . This latter further comprises a cantilever  60  on a rotatable flange  62  (FIG. 3) which outside the front plate  58  of the machine frame is rotatable in roller bearings in the plate  58  about the wire axis and is screwed onto the plate  58  with a crown gear  64  (FIG. 3) of a toothed belt drive  66 . The crown gear  64  is driven by means of a toothed belt  68  of a toothed belt drive  66  by a third CNC controllable servomotor  70  programmably controlled, intermittently rotated selectively forwards and backwards. 
     The wire holder  52  which is positioned axially in front of the front outlet of the wire guide  48  which rotates together with the wire intake device  10 , is detachably fixed onto the free end of the cantilever  60 . 
     In order to actuate the wire brake device  114 , a tow bar  116  is guided slidingly in the cantilever  60  of the rotatable wire guide device  12  (see FIG.  3 ). One end of the tow bar  116  is connected with a two-armed lever  120  by means of a bolt  118 . The lever  120  pivots around a bolt  122  in the cantilever  60 . The free lever arm  124  of the lever  120  presses the rounded end of a pressure bolt  128  under prestress by means of a pressure spring  126  guided slidingly in the (two-part-type) wire holder  52 , said pressure bolt  128  having a prismatic recess at its other end. This prismatic end of the bolt  128  cooperates with the passing-by wire  18  whereby friction forces are converted into brake forces. 
     The end of the tow bar  116  opposite the lever  120  is firmly connected with a switching ring  130 . The switching ring  130  is mounted axially displaceably in a slide bushing  132 , but is held in the bushing  132  radially and is not twistable. So in case of a rotating movement of the flange  62 , the switching ring  130  follows this rotation. The switching ring  130  has a groove  134  at its outer circumference into which the two switching claws  136  (one shown) of a two-armed switching lever  138  engage. The switching lever  138  is mounted approximately centrally in a bearing  140  pivoting on a bolt  142 . The bearing  140  is firmly connected to the front plate  58 . 
     The arm of the switching lever  138  opposite the switching claws  136  is provided with a lever eye  144  with an internal thread into which a threaded spindle  146  is screwed. The threaded spindle  146  is connected non-rotatably by means of a coupling  148  with the shaft end  150  of a CNC controllable servomotor  152 . 
     For the shaping process of the fed wire, the holder  52  can be brought into the most favorable position for this by means of the rotatable wire guide device  12 , for example, in order to allow a turndown of the partly finished workpiece or in order to turn the wire holder  52  into such a position that when the finished workpiece is cut off the endless wire, the cutting knife  100  of the cutting device  16  cuts the wire  18  against the higher wall thickness of the holder  52  which simultaneously serves as a counterknife. 
     The wire shaping station  14  is located at the front plate  58  which simultaneously is the shaping side of the apparatus for shaping wire. It comprises several processing units fixed radially around the wire guide bore  74  of the wire holder  52 . In FIG. 2 three of these units are shown: a winding/bending unit  78 , a CNC twisting unit  80 , and a CNC slide unit belonging to the cutting device  16 . The winding/bending unit  78  is described in detail in U.S. Pat. Nos. 5,363,681 and 5,105,641. In FIG. 1, on the right side of the wire holder  52  a vertical shaft  80  of the winding/bending unit  78  is provided vertical to the wire feeding device which is driven rotatably by a fourth CNC controllable servomotor  84  whereby the degree of shaft rotation, the sense of rotation, and the standstill can be freely selected. In order to allow the shaft  80  to carry out, in addition to its rotating movement, if necessary, a simultaneous longitudinal displacement, another CNC controllable servomotor (not shown) is foreseen. The amount of the longitudinal displacement of the shaft  82  is also freely selectable by the CNC control. 
     At the bottom end of the shaft  82 , in a conical support, a tool holder  86  known from U.S. Pat. No. 5,105,641 is fixed rigidly but detachably which can bear several tools arranged around its circumference and distributed over its length. In the embodiment shown as an example these are two winding tools  88  (FIG. 1) and  90  (FIG. 2) with several operating zones for the wire  18  as well as a bending tool  92  (FIG.  2 ). 
     The slide unit belonging to the cutting device  16  is driven by another CNC controllable servomotor  96  by means of a crank drive (not shown) and a connecting rod (not shown). The cutting knife  100  is held exchangeably in a support  104  at the free end of the cutting slide  102  guided lengthwise displaceably in a slide guide of the cutting device  16 . 
     The mode of operation of the apparatus according to the invention with reference to the embodiment shown in the example is as follows: 
     When the fist servomotor  26  is activated, the straightened endless wire  18  stretched between the intake rollers  24  is intermittently moved forward horizontally in a straight line through the wire guide  48  and the holder  52  by means of the CNC controlled intake rollers  24  to enter the wire shaping station  14  where it is formed according to the tools which become active on the tool holder  86 . CNC controlled withdrawal of the wire is also possible by reversal of the sense of rotation of the motor. 
     Bringing the individual tools into position before the shaping process and the active movement of the tools for the shaping of the workpiece are brought about by CNC activation of the servomotors of the winding and bending unit  78  as known from the exemplary U.S. Pat. No. 5,105,641. 
     The endless wire  18  delivered by the intake rollers  24  and CNC controlled by the second servomotor  34  by way of the toothed belt transmission  36  and the intake housing  22 , is turned through a predetermined angle and at the right moment, optionally simultaneously with the feeding of the wire  18  by the intake rollers  24 , into the most suitable position in space for carrying out the next operating step for each individual section of the wire shaping operation. 
     Simultaneously with the wire turning by the rotatable wire intake device  10 , when the ‘rotating wire intake’ and the ‘rotating wire guide’ run synchronously, the wire holder  52  is turned into the most suitable position for the shaping process by CNC activation of the third controllable servomotor  70 . At the same time the programmably controlled and power controlled wire brake device  114  can be put into operation by activating the CNC controllable servomotor  152 . The amount of brake force transmitted by the pressure bolt  128  onto the wire  18  is predetermined by the CNC machine control depending on the respective shaping process.