Patent Publication Number: US-7222764-B2

Title: Method of operating an apparatus for an intermittent feeding of a strip shaped blank to a press

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a divisional of U.S. Ser. No. 10/402,281 filed on Mar. 28, 2003 now U.S. Pat. No. 6,869,002, and is based on the European Patent Application No. 02 015 172.6 filed on Jul. 8, 2002, of which the priority is claimed and the disclosure of which shall be considered included in this application by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the invention 
   The invention relates to a method of operating an apparatus for an intermitted feeding of a strip shaped blank to a punch press which is equipped with tools adapted for an intermittent working of the strip shaped blank, which feeding apparatus includes a housing and a threaded spindle housing arranged on said housing, an upper shaft assembly and an upper feeding roller mounted on said upper shaft assembly, a lower shaft assembly and a lower feeding roller mounted on said lower shaft assembly, which feeding rollers are adapted to grip said blank to be fed by clamping said blank at both its sides and to feed said blank intermittently by an intermittent rotational movement, of which shaft assemblies at least one is drivingly connected to an intermittently operating electric servomotor and the upper shaft assembly is supported in a rocker which is pivotally mounted at said housing through a rocker shaft, by means of which rocker said upper shaft assembly is moveable towards and away from said lower shaft assembly, which feeding apparatus includes further a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus, and comprises further a rod having a elongate hole and which is moveable between a top dead center position and a bottom dead center position, and having a bolt extending through the elongate hole, whereby in order to insert a fresh strip shaped blank between the upper feeding roller and the lower feeding roller the upper feeding roller is moved into a high lift position in order to set a predetermined distance between the upper feeding roller and the lower feeding roller. 
   The invention relates further to a method of operating such a feeding apparatus, which feeding apparatus comprises a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus, and comprises further a rod which is movable between a top dead center position and a bottom dead center position, which rod has a elongate hole having a upper and a lower end, whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole. 
   The invention relates also to a method of operating the feeding apparatus as set forth above, which feeding apparatus has a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which has a press control apparatus which communicates with the control apparatus of the feeding apparatus, and has further a rod which is moveable between a top dead center position and a bottom dead center position, which rod has an elongate hole having a upper and a lower end, whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole. 
   The invention relates also to a method of operating the feeding apparatus set forth above, wherein the feeding apparatus comprises a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus, and comprises further a rod which is moveable between a top dead center position and a bottom dead center position, which rod has an elongate hole having a upper and a lower end, whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole which punch is driven by a rotating drive and the eccentric disc of the rod is driven by a drive motor, which upper tool has positioning pins for a precise positioning of the strip shaped blank in the press during the working of same, which positioning pins are moved into pre-punched positioning holes in the strip shaped blank and which positioning pins include a conical head portion, which upper feeding roller is moved away from the bottom feeding roller as soon as the conical head portions are moved partly into the positioning holes and thereafter set again onto the strip shaped blank as soon as the conical head portions have been lifted partly out of the positioning holes. 
   2. Description of the Prior Art 
   The punch presses referred to herein are especially high speed presses with stroke numbers up to 2000strokes per minute. These presses are equipped with tools for a working of a (or several) fed strip shaped blank(s), whereby punching operations, embossing operations, bending operations, a riveting, a producing of threads, etc. are performed. 
   The movement of the strip shaped blank which is processed in the press proceeds, thereby, intermittently, thus step by step. During a working step, e.g. a punching, quite obviously no feeding movement of the strip shaped blank occurs. It is often positioned precisely, thus arrested by positioning pins located in the tools. After the termination of the processing step, for instance after a punching tool has been moved out of the hole which has been punched through, the strip shaped blank is fed forwards by a set distance and is again stopped, so that the next subsequent processing step can be performed. 
   The feeding or advancing, resp. movement of the strip shaped blank is accomplished by a (or several, located at the entry and the exit of the press) feeding or forwarding, resp. apparatus (or apparatuses, resp.) in order to draw the strip shaped intermittently off a storage spool and feed same intermittently to the press. 
   These feeding apparatuses comprise conventionally feeding members in order to feed and forward the strip shaped blank. It is, thereby, clamped and moved forward by the feeding members. When the feeding members return into their initial, that is starting position, the clamping is released. Additionally, the clamping is temporarily released during the time span, during which the tools perform a processing or working, resp. step of the strip shaped blank, specifically in case of positioning pins. 
   Designs of such feeding apparatuses have become known, in which the clamping members are designed as linearly moving clamping tongues. Other designs comprise oscillating segment rollers which perform rotational movements. 
   Furthermore, feeding apparatuses with electrical servomotors have become known. A first servomotor is, thereby, allocated to the feeding operation of the clamping members and a further, second electric servomotor is allocated to the intermittent lifting of a clamping member off the strip shaped blank. Such servomotors are produced and sold by several companies. The operation of these servomotors is electronically controlled. These new feeding apparatuses comprise feeding members in form of completely cylinder shaped feeding rollers mounted on shafts which rotate intermittently always in the same sense of rotation. Of these feeding rollers one is supported in a structural member which is drivingly connected to the further servomotor, based on the operation of which this feeding roller is moved against the strip shaped blank for a clamping of same and away from this member for a releasing of same. 
   Due to the presently extremely high number of strokes, the masses of the moving parts of a feeding apparatus have a large impact due to the forces of inertia and the moments of inertia, and have, furthermore, a large influence regarding the precision of the produced product. Furthermore, due to the time spans for the acceleration and deceleration of movements, the arrangement and design of the moving parts must be selected in such a manner, that an operation of a high number of strokes can be performed safely. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide a method of operating a feeding apparatus, in which in order to set a high lift position of the upper feeding roller its two control apparatuses are controlled in such a manner, that the ram is controlled to move into its top dead center position and the rod is controlled to move into its bottom center position. 
   A further object of the invention is to provide a method of operating a feeding apparatus for setting a high lift position of its upper feeding roller, wherein the ram is kept stationary and the adjusting nut is lowered by a rotating of the threaded spindle, whereby the bolt comes to lie onto the lower end of the elongate hole due to the force exerted by the pressure spring assembly via the rocker and the lever units, so that the first arm of the first double arm lever unit is pivoted downwards, the first arm of the second double arm lever unit is pivoted downwards and the second arm is pivoted upwards, so that the control rod unit is lifted due to these pivoting movements and accordingly the rocker with the upper feeding roller supported therein is pivoted upwards into the high lift position of the feeding roller. 
   Yet a further object of the invention is to provide a method of operating a feeding apparatus set forth above, in which the rod is moved into its bottom dead center position, the adjusting nut is moved downwards by a rotating of the threaded spindle until the upper feeding roller comes to lie on the strip shaped blank due to the pressure exerted by the pressure springs onto the rocker, thereafter the adjusting nut is moved still further downwards until the bolt is at a distance from both ends of the elongate hole, so that the stroke movements of the rod are possible at a stationary state of the bolt. 
   A further object of the invention is to provide a method of operating a feeding apparatus set forth above, wherein in order to set the intermediate lift position, the punch is brought by its rotating drive into a angular position ahead of its bottom dead center position, in which angular position the conical head portions of the positioning pins project only partly into the positioning holes, in which state the eccentric disc of the rod attains a angular position ahead of the top dead center position, whereby the angular distance of the punch between said angular position and the bottom dead center position equals the angular distance of the eccentric disc between its said angular position and the top dead center position, and wherein thereafter the adjusting nut is moved downwards, so that the bolt comes to rest onto the bottom end of the elongate hole and the adjusting nut is moved still more further down until the strip shaped blank is loose due to the lifting off of the upper feeding roller by the movement transmitted through the lever units and the control rod assembly and rocker, and wherein the position attained by the adjusting nut for mentioned angular position of the eccentric disc and the corresponding angular position of the punch are stored in the corresponding control apparatus. 
   Due to the design of the clamping sleeve which is an integral part of the threaded spindle, there is the liberty of selecting and mounting various different electric servomotors and specifically standard motors because no custom produced drive shafts of such electrical servomotors are necessary. 
   Basically, the design of the feeding apparatus must fulfil three main functions, namely high lifting (inserting strip), adjusting in accordance with the thickness of the strip (the upper roller lies on the strip, play in the elongate hole of the rod) and intermediate lifting (strip lifting ahead of each punching operation). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein 
       FIG. 1  is a section through a first embodiment of the apparatus according to the present invention, 
       FIG. 2  illustrates a portion of  FIG. 1 , drawn on a enlarged scale; 
       FIG. 3  illustrates the first and second section of the upper shaft structure and the lower shaft structure, including the upper and the lower feeding roller, shown in a axially exploded view; 
       FIG. 4  is a section along line IV—IV of  FIG. 1 ; 
       FIG. 5  is a section along line V—V of  FIG. 1 ; 
       FIG. 6  is a section along line VI—VI of  FIG. 1 ; 
       FIG. 7  is a section through a part of the apparatus, in a state in which the electric servomotor with the driving gear wheel and the cross-type disc of the Oldham-type coupling are demounted; 
       FIG. 7   a  illustrates the flange of the electric servomotor with the driving gear wheel in the mounted state, and a part of the Oldham-type coupling; 
       FIG. 7   b  illustrates the cross-type disc of the Oldham-type coupling; 
       FIG. 8  is a section through a further embodiment of the apparatus according to the present invention; 
       FIG. 9  is a section through a part of the apparatus illustrated in  FIG. 8 , in which the drive for the lower roller is demounted; 
       FIG. 10  depicts the illustration of  FIG. 6  in a simplified manner, whereby the feeding apparatus is illustrated in the state of continuous operations without any intermediate lift; 
       FIG. 11  depicts the illustration of  FIG. 6  in a simplified manner, whereby the feeding apparatus is illustrated in the state of the high lift position; 
       FIG. 12  depicts the illustration of  FIG. 6  in a simplified manner, whereby the feeding apparatus is illustrated in the state of the intermediate lift; and 
       FIG. 13  illustrates schematically a punch press cooperating with a feeding apparatus according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The apparatus has a frame  1 . A first electric servomotor  2 , of which the electronic control  3  is shown in a simplified manner is mounted at its flange  4  through threaded bolts  5  to the frame  1 . 
   This first electric servomotor  2  is controlled in a manner which as such is generally known so that it performs step-wise intermittent rotational movements. The duration and the extent of a respective step of the rotational movement are controlled in dependence from the working process to be done in the adjacent following punch press. This electric servomotor  2  includes a drive shaft  6 . 
   An upper shaft assembly  8 ,  9  with an upper feeding roller  10  and a lower shaft assembly  20 ,  21  with a lower feeding roller  22  are located in the frame  1 , which feeding rollers  10 ,  22  are to feed the strip shaped blank  7 , generally a metal strip, in a intermittent fashion. 
   The upper shaft assembly  8 ,  9  is composed of a first shaft portion  8  located axially adjacent the electric servomotor  2 , and of a second shaft portion  9  located axially at a distance from the first shaft portion  8  and remote from the electric servomotor  2 . The upper feeding roller  10  is held between these two shaft portions  8 ,  9  in a clamped state. 
   A threaded tightening bolt  11  extends axially through the second shaft portion  9  located remote from the electric servomotor  2 , which threaded tightening bolt  11  rests against the second shaft portion  9  and is threadingly engaged in the first shaft portion  8  located adjacent the electric servomotor  2 . 
   The two shaft portions  8 ,  9  are held tightened against each other by this threaded tightening bolt  11 , so that the upper feeding roller  10  which is located between these shaft portions  8 ,  9  is firmly held between the two shaft portions  8 ,  9  in a clamped state. 
   This upper feeding roller  10  which consists of several parts and is of a quite light structure features the shape of a hollow circular cylinder having a axially extending inner chamber  12  with a inner circumferential wall  13  and two end surface portions  14  and  15 . See hereto  FIG. 3 . 
   The transition portion  16  between the end surface portion  14  and the inner circumferential wall  13  of the inner chamber  12  features the geometrical shape of the jacket of a truncated cone. The transition portion  17  extending between the end surface portion  15  and the inner circumferential wall  13  of the inner chamber  12  features in the same manner the geometrical shape of the jacket of a truncated cone. 
   The ends of the shaft portions  8 ,  9  which face each other include also a portion  18  and  19 , resp. in the geometrical shape of the jacket of a truncated cone. 
   It can be seen clearly, therefore, that after the threaded tightening bolt  11  has been tightened, the respective portions  16 ,  18  and  17 ,  19  which have the geometric shape of a truncated cone abut each other so that the upper feeding roller  10  located between these shaft portions is firmly held in a clamped and guided state. 
   As also can be seen clearly, when the upper feeding roller  10  is to be dismounted it is merely necessary to loosen and unscrew the threaded tightening bolt  11  and to pull it a little out through a opening in the frame  1 , through which opening the threaded tightening bolt  11  is accessible. Thereafter, the feeding roller can be dismounted and removed without any further ado. 
   This state is illustrated on a purely exemplary basis in connection with the still to be described lower shaft portions  20 ,  21  and the lower feeding roller  22  in  FIG. 3 . The illustrated axial distances, which will be entered into further below are designed in a exaggerated manner. 
   The lower shaft assembly  20 ,  21  is also composed of a first shaft portion  20  located axially adjacent the electric servomotor  2  and of a second shaft portion  21  located axially at a distance from the first shaft portion  20  and remote from the electric servomotor  2 . The lower feeding roller  22  is held between these two shaft portions  20 ,  21  in a clamped state. 
   A threaded tightening bolt  23  extends axially through the second shaft portion  21  located remote from the electric servomotor  2 , which threaded tightening bolt  23  rests against the second shaft portion  21  and is threadingly engaged in the first shaft portion  20  located adjacent the electric servomotor  2 . 
   The two shaft portions  20 ,  21  are held tightened against each other by this threaded tightening bolt  23 , so that the lower feeding roller  22  which is located between these shaft portions  20 ,  21  is firmly held in a clamped state. 
   This lower feeding roller  22  which consists of several parts and is of a quite light structure features the shape of a hollow circular cylinder having a axially extending inner chamber  24  with a inner circumferential wall  25  and two end surface portions  26  and  27 . 
   The transition portion  28  extending between the end surface portion  26  and the inner circumferential wall  25  of the inner chamber  24  features the geometrical shape of the jacket of a truncated cone. The transition portion  29  extending between the end surface portion  27  and the inner circumferential wall  25  of the inner chamber  24  features in the same manner the geometrical shape of the jacket of a truncated cone. 
   The ends of the shaft portions  20 ,  21  which face each other include also a portion  30  and  31 , resp. in the geometrical shape of the jacket of a truncated cone. 
   It can be seen clearly, therefore, that after the threaded tightening bolt  23  has been tightened, the respective portions  28 ,  30  and  29 ,  31  which have the geometrical shape of a truncated cone abut each other so that the lower feeding roller  22  located between these shaft portions is firmly held in a clamped and guided state. 
   As also can be seen clearly is that if the lower feeding roller  22  is to be dismounted it is merely necessary to loosen and unscrew the threaded tightening bolt  23  and to pull it out through a opening in the frame  1 , through which opening the threaded tightening bolt  23  is accessible. 
   Thereafter, the feeding roller  22  can be dismounted and removed without any further ado. 
   This state is illustrated in  FIG. 3 . 
   The first shaft portion  8  of the upper shaft assembly which shaft portion  8  is located adjacent the electric servomotor  2  and the first shaft portion  20  of the lower shaft assembly which shaft portion  20  is located adjacent the electric servomotor  2  remain stationary, such as e.g. illustrated in  FIG. 2 . Thus, they are not displaced. The second shaft portion  9  of the upper shaft assembly which shaft portion  9  is located remote from the electric servomotor  2  and the second shaft portion  21  of the lower shaft assembly which shaft portion is located remote from the electric servomotor  2  have been, after the threaded tightening bolts have been loosened, displaced axially in the direction of the arrow C. Accordingly, the feeding rollers  10 ,  22  lie exposed and can be removed from the shafts. It is to be noted that the axial distances between the structural members illustrated in  FIG. 3  are shown exaggerated. The free space between the respective shaft portions, i.e. the distance between these shaft portions must be only that large that the feeding rollers, in order to remove them, can be displaced freely in the radial direction. 
   Reference is now made to  FIG. 7 . The first shaft portion  8  of the upper shaft assembly which shaft portion  8  is located axially adjacent the electric servomotor  2  is supported through a roller bearing  32  in a rocker  33  still to be described, i.e. in the rocker portion  33   b.  The chamber of the lubricant of the roller bearing  32  is sealed off by seals  34   a,    34   b.    
   The second shaft portion  9  of the upper shaft assembly which shaft portion  9  is located remote from the electric servomotor  2  is supported through roller bearings  35  in the rocker portion  33   b.  The chamber of the lubricant of the roller bearing  35  is sealed off by seals  36   a,    36   b.    
   The first shaft portion  20  of the lower shaft assembly which shaft portion  20  is located adjacent the electric servomotor  2  is supported by roller bearings  36  and  92  in frame  1 . The chamber of the lubricant of the roller bearing  36  is sealed off by a seal  37 . 
   The second shaft portion  21  of the lower shaft assembly which shaft portion  21  is located remote from the electric servomotor  2  is supported in the frame  1  by roller bearings  38  and  92 . The chamber of the lubricant of the roller bearing  38  is sealed of by seals  39   a,    39   b.    
   Accordingly, it can be seen that each bearing of the shaft portions  8 ,  9 ,  20 ,  21  is located in its own lubricant chamber and accordingly that the dismounting of the feeding rollers  10 ,  22  can be accomplished without any opening of lubricant chambers. Accordingly, the respective exchanging of the feeding rollers  10 ,  22  can be done in a quite simple manner. 
   According to a first preferred embodiment the upper shaft assembly supported in the rocker  33 , i.e. more precisely the first shaft portion  8  of the upper shaft structure located axially adjacent the electric servomotor  2  supported in the rocker portion  33   a  is drivingly connected to the first electric servomotor  2 . 
   The first shaft portion  8  is connected to a Oldham-type coupling  40  of which the cross-type disc  41  is illustrated separately in  FIG. 7   b.  This Oldham-type coupling  40  is necessary because the first shaft portion  8  (and obviously all parts of the apparatus which are connected to the fist shaft portion) performs lateral movements relative to the as such stationary (except of course the rotating) drive shaft  6  of the electric servomotor  2 . 
   This Oldham-type coupling  40  is followed by an upper spur gear  42  which meshes with a lower spur gear  43 , which in turn is connected to the first shaft portion  20  of the lower shaft assembly located adjacent the servomotor  2 . 
   The coupling of the upper spur gear  42  to the drive shaft  6  of the electric servomotor  2  is accomplished by a multi-part clamping sleeve device with a first clamping sleeve part  44  and a second clamping sleeve part  45 . 
   The co-acting of the clamping sleeve parts  44  and  45  is performed by annular clamping elements  46 . The clamping sleeve screw bolts are identified by the reference numeral  47 . 
   The upper spur gear  42  is made integral with the second clamping sleeve part  45 , so that a considerable saving on moving masses is achieved. 
   According to a preferred embodiment a portion of the Oldham-type coupling is also made integral with the second clamping sleeve part  45 . 
   According to a further preferred embodiment no spur gears are present, so that the lower feeding roller  22  is rotated exclusively by a frictional engagement with the metal strip  7 . 
   A still further embodiment is illustrated in  FIGS. 8 ,  9 ,  9   a.  According to this embodiment the upper feeding roller  10  is rotated by a frictional engagement with the metal strip. 
   In this embodiment the first shaft portion  20  of the lower shaft assembly is driven by the electric servomotor  2 . This shaft portion  20  is, thereby, made integral with the second clamping sleeve part  45 , so that again a minimal rotating mass is present. 
   A further electric servomotor  48  is located on top of a threaded spindle housing  67  of the feeding apparatus. Its electronic control, i.e. the housing thereof, is identified by the reference numeral  49 . 
   This electric servomotor  48  serves for the driving of a threaded spindle  50 . 
   The electric servomotor  48  is to be considered merely as a example of the drive for the threaded spindle  50 . It is also possible to have drives different from the servomotor  48 . 
   The drive shaft of the electric servomotor  48  is identified by the reference numeral  51 . The connection between the drive shaft  51  of the electric servomotor  48  and the threaded spindle  50  is accomplished by a multi-part clamping sleeve device which includes a first clamping sleeve part  53  and annular clamping elements  54 . The clamping sleeve parts  52 ,  53  are tightened against each other by clamping screw bolts  55 . 
   The second clamping sleeve part  53  is coupled to the threaded spindle  50  through a jaw clutch coupling  113 . The threaded spindle  50  is in turn supported in the threaded spindle housing  67  or housing  1 , respectively, through roller bearings  56  and  112 . 
   Accordingly, the threaded spindle  50  is supported free from play independent from the servomotor  48 . 
   Because annular clamping elements are used for connection to the smooth shaft of the servomotor, a standard servomotor, thus no custom made design an be used. 
   An adjusting nut  57  is arranged on the threaded spindle  50 . 
   A double arm lever  93  with a first arm  94  and a second arm  95  is supported on this adjusting nut. This arm  93  is termed in this specification second double arm lever  93 . 
   As clearly can be seen in  FIG. 4 , the adjusting nut has a square cross-sectional shape and is set into an inner space of the first double arm lever  93  which features also a square cross-sectional shape. Accordingly, the adjusting nut is secured against a rotating. 
   A bolt  58  is set into a first arm  94  of the first double arm lever  93 . The bolt  58  extends through an elongate hole  59  in a rod  96 . 
   This rod  96  sits on a excentric disc  97  which is drivingly connected to a third driving motor  99 , for instance a electric servomotor. The control of the servomotor is identified by the reference numeral  100 . 
   The second arm  95  of the first double arm lever  93  is pivotally mounted to a first arm  102  of a second double arm lever  103  through a strap  101 . The second double arm lever  103  is supported on a shaft  60 . The second arm  104  of the second double arm lever  103  is of a forked design, such as illustrated in  FIG. 4  by the reference numerals  65 ,  66  designating the fork levers. 
   The shaft  60  is sealed in the threaded spindle housing  67  oil-tight by seals  61 ,  62 , so that a closed threaded spindle housing  67  as a closed lubrication oil chamber is present, in which the threaded spindle  50  and the above described structure members are located in a maintenance-free manner. 
   Specifically  FIG. 4  illustrates that the shaft  60  projects at both its ends out of the threaded spindle housing  67  and that the forked lever arms  65 ,  66  are clamped onto these projecting ends. 
   These forked lever arms  65 ,  66  are pivotally mounted through a ball end connection to an upper shaft portion  68  and  69 , resp. of a control rod generally identified by  70  and  71 , resp., which upper shaft portions are threadingly engaged with lower shaft portions  72  and  73 , resp. The described shaft positions are secured against a rotation by both nuts  74  and  75 , respectively. 
   The control rods  70  and  71  are pivotally mounted at their lower ends to the rocker  33 . 
   The rocker  33 , in which the upper feeding roller  10  is supported, is mounted at its end opposite the control rods  70  and  71 , resp. to a shaft  79 . This shaft  79  is supported in the frame  1 . The bearings  80 ,  80   a  of the shaft  79  are shown in  FIG. 5 . 
   Thus, it can be seen that the rocker  33  inclusive the upper feeding roller  10  supported in the rocker can perform rocking, that is pivoting movements around the shaft  79 . Accordingly, the upper feeding roller  10  can be moved against the lower feeding roller  22  and the metal strip  7  fed in the direction of the arrow B resting thereupon, and again away from the lower feeding roller  22 . 
   The strip entering table  81  and the strip exiting table  82 , well known in the art, are additionally shown in  FIG. 6 , whereby the metal strip  7  lies at both sides of the lower feeding roller  22  on these two tables  81 ,  82 . 
   The rocker  33  is biased by pressure springs  83  and  84 , resp. against the lower feeding roller  22 . 
   The biasing force of the pressure springs  83 ,  84  is adjusted by threaded spindles  85 ,  86  and locking nuts  87 ,  88  which rest against the threaded spindle housing  67 . 
   The adjusting of the pressing on force proceeds by a reading of the position of discs,  89 ,  90  relative to a scale  91 , which discs rest on the pressure springs  83 ,  84 . 
   Obviously, a scale is allocated to each pressure spring  83 ,  84 . 
   The described feeding apparatus is adapted to feed a strip shaped blank  7 , e.g. a metal strip  7 , to a press which is equipped with tools for a intermittent working of the strip shaped blank  7 . 
   This feeding apparatus and the press  76 , a punch press, allocated to the feeding apparatus are illustrated schematically in  FIG. 13 . 
   The punch press  76  includes a drive  77 . Such as known to the person skilled in the art, this drive  77  can include a electromotor which drives a crank shaft or a shaft with eccentric discs. This crank shaft or eccentric disc is drivingly connected to a rod  78 . A punch  105  is pivotally mounted to this rod  78 . The punch  105  supports a upper tool  106 , which conclusively is moved upwards and downwards when the punch press  76  is in operation. The upper tool  106  is equipped with working tools, e.g. punches  107 . The upper tool  107  is, furthermore, equipped with positioning pins  108 , each having a conical head portion  109 . 
   In operation, such as is generally known, prior to the impacting of the working tools, thus e.g. punches  107  onto the strip shaped blank  7  for the working or processing proper, the positioning pins  108  are moved into pre-punched holes in the blank  7  in order to precisely center same. The upper feeding roller  10  is, thereby, lifted off the lower feeding roller  22  during a short time span by a short distance, so that no clamping force is exerted onto the blank  7 . This position of the upper feeding roller  10  is called intermediate lift. 
   Furthermore, the stationary lower tool  110  and the control apparatus  111  of the punch press  70  are illustrated in  FIG. 13 . 
   As can be seen, the control apparatuses  49 ,  110  of the feeding apparatus and of the punch press  76  communicate, because the operation of the feeding apparatus must be coordinated with the operation of the punch  76 . 
     FIG. 10  illustrates the positions of the schematically designed parts of the feedings apparatus during a continuous operation phase. During the continuous phase operation the upper feeding roller  10  and the lower feeding roller  22 , are both driven by the electric servomotor  2  in a intermittent fashion, so that the blank  7 , such as generally known, is fed step by step. The (electronic) control apparatus  49  of the feeding apparatus cooperates, thereby, with the (electronic) control apparatus  111  of a punch press  76 . See hereto  FIG. 13 . The punch press  76  comprises a moveable upper tool  106  and a stationary lower tool  110 . The upper tool  106  is mounted to a punch  105 . The punch  105  is driven by a rotating drive  77 , e.g. a electric motor and crank shaft or eccentric shaft through a rod  78 , whereby the rod  78  represents purely schematically the drive connection between the drive  77  and the punch  105 . 
   Thus, the punch is moveable between a top dead center position and a lower dead center position. 
   The dimension of the thickness of the strip shaped blank  7  and correspondingly the distance between the upper feeding roller  10  and the lower feeding roller  22  is represented in  FIG. 10  by the letter E. 
   In order to be able to insert a fresh strip-like blank  7 , thus for instance a metal strip between the upper feeding roller  10  and the lower feeding roller  22 , the upper feeding roller  10  must be lifted off so that it is at a set distance D from the lower feeding roller  22 , which is larger than the distance E. This distance D and the lifted off position of the upper feeding roller  10  are illustrated in  FIG. 11 . 
   In the art, this position of the feeding roller  10  is called high lift position. 
   In order to set this high lift position the control apparatuses  49  and  111  of the feeding apparatus and of the punch press  76  are controlled in such a manner, that the punch  105  of the punch press is located remote from the lower dead center position and the rod  96  is located remote from the top dead center position. In which specific positions the punch  105  and rod  96  are located is not of importance as long as the punch is not located at the lower dead canter position. Generally, and this is known by the person skilled in the art, the control apparatuses  49  and  111  of the feeding apparatus and the punch press are operated in such a manner, that the punch  105  of the punch press is located at the top dead center position and the rod  96  is located at the lower dead center position. The now following description proceeds from these latter dead center positions. When said dead center positions are arrived at, the adjusting nut  57  is lowered by a corresponding rotating of the threaded spindle  50 . 
   Due to the pressure springs  82 ,  84  above the rocker  33  and the lever units  93  and  103  the bolt  58  abuts the lower end of the elongate hole  59 . 
   Due to the downwards movement of the adjusting nut  57  the first arm  94  of the first double arm lever unit  93  is pivoted upwards and its second arm  95  is pivoted downwards. This second arm  95  pulls the first arm  102  of the second double arm lever device  103  also downwards. Accordingly, the second arm  104  of the second double arm unit  103  is pivoted upwards. Conclusively, the control rod assembly  68 – 75  is lifted and accordingly the rocker  33  with the upper feeding roller supported therein is pivoted into the high lift position of the upper feeding roller  10 , in which position it has mentioned distance D from the lower feeding roller  22 , so that a fresh strip shaped blank  7  may be inserted. 
   For the continuous operation the upper feeding roller  10  must lie on the strip shaped blank  7 , whereby a clamping force for a frictional engagement of the strip-like blank must be exerted by the upper feeding roller  10  and the lower feeding roller  22 . 
   The clamping force is produced by pressure springs  83 ,  84 . Thus, the bolt  58  is no longer to abut the lower end of the elongate hole  59 . To this end, the adjusting nut  57  is lowered from the high lift position by a rotating of the threaded spindle  50 , until the upper feeding roller  10  lies on the strip shaped blank  7 . 
   Due to the continued lowering movement of the adjusting nut  57  the first double arm lever  93  is forced to perform a pivoting movement, because the rocker does no longer move because the upper feeding roller  10  is kept to lie on the strip-shaped blank by the pressure springs  83 ,  84 . Mentioned pivoting movement causes a upwards pivoting of the first arm  94  with the bolt  58 , so that the bolt  58  is located in the elongate hole  59  between its ends. This means, that the rod  96  can basically perform stroke movements without a action onto the bolt  58 . 
   A further movement during operation of the feeding apparatus with the punch press is the intermediate lifting. 
   It has been mentioned above that a upper tool  106  of a punch press can be equipped with positioning pins  108  for a precise positioning of the strip-shaped blank  7 . 
   In order to allow such a positioning, it is necessary that the strip-like blank must lie unencumbered during a short time span. This means that the upper feeding roller  10  must be lifted off the strip-shaped blank  7  for a short time span into a intermediate lift position. 
   This intermediate lift position is produced by the rod  96 . 
   Firstly, the punch press  76  is operated into the stroke position, in which the intermediate lift position shall occur and in which the conical head portions  109  of the positioning pins  108  are inserted partly into the positioning hole. This position is illustrated in  FIG. 13 . 
   In this position the punch  105  of the punch press  76  is located at a angular position ahead of the bottom dead center position. Accordingly, a angular distance between mentioned angular position and the bottom dead center position is present. 
   The rod  96  of the feeding apparatus has now been simultaneously moved upwards by operation of its drive motor  99  into a position ahead of its top dead center position. Accordingly, there also exists a angular distance between this angular position and the top dead center position. 
   The angular distance mentioned in connection with the punch press is the same angular distance as present at the feeding apparatus. 
   Now, the adjusting nut  57  is moved downwards by a rotating of the threaded spindle  50 . Accordingly, the bolt  58  comes to rest on the lower end of the elongate hole  59 . Then, the adjusting nut  57  is moved still further downwards, so that due to the now following pivoting movements of the lever units and of the rocker  33  the upper feeding roller  10  releases the strip-shaped blank. In this released state the strip-shaped blank is loose to such a extent that it can be moved manually. This position of the adjusting nut  57  is stored together with the corresponding angular positions in the control apparatuses  49  and  111 . 
   This means, that during the continuous operation the rod  96  with its elongate hole  59  can freely move relative to the bolt  58  without influencing the bolt, with the exception that if the rod  96  reaches the above mentioned angular position ahead of the top dead center position of the rod  96 , the lower end of the elongate hole  59  engages the bolt  58 , lifts it up and after the top dead center position has been passed, the bolt  58  is again released. 
   While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.