Abstract:
The invention relates to a novel machining tool and a punching head for use in one such tool. An internal feed channel is formed between the connection for the external feed of components and the readiness position on the joining channel at least over a partial length of a deformable or flexible internal feed, so that the run of this feed within the tool and/or the correction of the feed to the external supply can be optimally matched to the respective tool execution.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a punching head. The invention furthermore relates to a machining tool and a machining device. 
     In the sense of the invention a “machining tool” is especially a deep-drawing and/or punching and/or metal-forming tool for use in a press or similar machining devices. Machining tools of this type are known and are used in the production of workpieces in the form of components for motor vehicle bodies. 
     Fundamentally these machining tools are also known with punching heads or devices which are located in the tool and which are used for attaching nuts or nut-like components. Nuts in the sense of the invention are especially punch nuts and/or rivet nuts and/or insert nuts. Nut-like components in the sense of the invention are nuts, but also these components with a polygonal or cylindrical body and especially also those in which the axial length of the component body is smaller than the maximum diameter of this body. Nut-like components in this sense are also sliding or guide bushings with bushing bodies made similarly to the bodies of punch or insert nuts, but with an opening without a thread. 
     In the sense of the invention a “punching head” is defined as a device with which insertion (joining) and anchoring of fasteners, for example bolts or nuts or bolt-like or nut-like components, for example threaded bolts, unthreaded bolts, punch nuts, rivet nuts, insert nuts or sleeves is possible. 
     The object of the invention is to devise a machining tool which with high operating reliability with respect to at least one punching head which offers simplified execution and also improves freedom of configuration with respect to arrangement and orientation of the punching head. 
     SUMMARY OF THE INVENTION 
     In the invention, the feed of the fastener to the respective punching head and the positioning of these components at the respective transfer or readiness position of the punching head take place without elastic positioning elements such as catches or the like, but solely by delivery air, optionally supported by permanent magnets and/or negative pressure. This yields an especially simple structure. One special advantage of the invention is that the internal feed channel is formed between the connection for the external feed of components and the readiness position on the joining channel at least over a partial length of a deformable or flexible internal feed, so that the run of this feed within the tool and/or the connection of the feed to the external supply can be optimally matched to the respective tool execution, in the construction of the respective tool therefore the run of a rigid guide need not be considered, as is the case in known punching heads which have a rigid, straight feed, or with increased engineering effort an angled, but then likewise rigid internal feed. 
     The punching head as claimed in the invention is used in the conventional manner for inserting fasteners such as bolts or nuts or bolt-like or nut-like components which can also be called joining parts, into workpieces. These fasteners or joining parts are supplied to the punching head via an external feed with compressed air (delivery air). In the guide on the punching head side the fasteners or joining parts are then moved to a readiness position from which they are inserted into the workpiece, for example in one made of sheet metal or flat material, via a joining channel. 
     The means for moving the fasteners within the punching head guide to the readiness position are formed by the external delivery air or the external delivery air flow which is produced for example by at least one compressed air nozzle in the supply unit for the fasteners or joining parts and/or by internal delivery air or an internal delivery air flow which is provided on or in the area of the punching head by at least one air exit nozzle there. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is detailed below using the figures on embodiments. 
         FIG. 1  shows in simplified form a component or fastener in the form of a nut together with a sheet metal workpiece; 
         FIG. 2  shows the blank holder and the bottom part of the machining tool for use in a press, together with a punching head for processing the nuts of  FIG. 1 , in a section; 
         FIG. 3  shows the punching head of  FIG. 2  in a cross section perpendicular to the section of  FIG. 2 ; 
         FIG. 4  shows in an individual representation and in a lengthwise section the cylinder-like housing of the guide for the plunger of the punching head of  FIGS. 2 and 3 ; 
         FIGS. 5 and 6  show in a lengthwise section and in cross section the upper part of the two-part head piece of the punching head of  FIGS. 2 and 3 ; 
         FIGS. 7 and 8  shows in a simplified view and in a side view as well as in a section a feed or injection means of an external supply unit for nuts for inserting these nuts into the external supply hose which leads to the punching head; 
         FIG. 9  shows in a simplified representation a fastener in the form of a bolt, together with a sheet metal workpiece; and 
         FIG. 10  shows a view similar to  FIG. 2 , but for a punching head made for processing of connecting pins. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  the workpiece is of sheet metal, for example a punched or bent part of sheet steel. A fastener in the form of a nut  2  is anchored into the opening of the workpiece  1  by joining and subsequent pressing. 
     A blank holder is labeled  3  and the lower part of a multipart tool  5  is labeled  4  and is for example a deep drawing and/or punching and/or metal-forming tool and is used for producing the workpiece  1  and at the same time also for joining and fixing the nut  2  which is made as an insert nut. The tool  5  has a punching head  6  which is attached to the blank holder  3  in this embodiment for inserting the nut into the workpiece  1 . 
     The punching head  6  includes a front head section or head piece  7  which is made in the embodiment shown in two parts consisting of parts  7 ′ and  7 ″, and of the cylindrical housing  8  which stands away over the top of the head piece  7 . In the head piece  7  or in the lower part  7 ″ of this head piece a vertical joining channel  9  is formed which is open on the bottom of the head piece  7 , in the area of an annular contact surface  9 . In the joining channel  9  and in the extension which coaxially adjoins this joining channel to the top, there is a plunger  11  which can be moved by a given stroke (double arrow H) in the plunger axis A S , between an initial position in which the lower plunger end  12  is located above the loading channel  13  which is likewise made in the head piece  7  or in the part  7 ″ and which intersects the joining channel  9 , and in which thus the loading channel  13  to the joining channel  9  or to the readiness position  9 ′ in the joining channel  9  is open underneath the plunger surface  12 , and the position in which the plunger  11  blocks the loading channel  13  toward the joining channel  9  and the plunger end  12  is located in the vicinity of the lower opening of the joining channel  9  or the annular surface  10  there in the joining and press position. On the plunger end  12  in the embodiment shown there are two permanent magnets  14  which are located offset radially to the plunger axis A S  and are offset by 180° against one another relative to this axis. 
     The loading channel  13  which runs radially to the axis A S  with its longitudinal extension is a component of an internal feed, is used in the manner detailed below for feed of nuts  2  to the readiness position  9 ′ and passes into the channel  15  of a flexible feed  16  which is made of a flexible material, preferably of plastic, and which is connected to the head piece  7  by means of a coupling piece  17 . The cross section both of the joining channel  9  and also of the channel  15  of the feed  16  is matched to the shape of the nuts  2  such that in these channels they can have only one given orientation, oriented with their axis A M  perpendicular to the lengthwise extension of the respective channel such that this axis A M  of each nut  2  which is located in the loading channel  13  is parallel to the plunger axis A S . The flexible feed  16  extends as far as the edge of the tool  5  or to an area of this tool where the feed  16  is connected via a suitable coupling  18  to the external supply hose  19  which has a channel with the cross section likewise matched to the shape of the nuts and via which the nuts  2  are supplied to the punching head  6 . 
     At the readiness position  9 ′ there is a sensor  20  which in the presence of a nut  2  delivers to this readiness position  9 ′ a corresponding sensor signal which indicates the readiness of the punching head  6  for inserting a nut  2  into the workpiece  1  which is ready under the punching head  6 . In the absence of a sensor signal  20  the press which has the tool  5  is stopped. 
     At the readiness position  9 ′ there are furthermore two permanent magnets  21  which are located laterally from this readiness position and are offset around the axis parallel to the axis A S . The permanent magnets  21  and the axes around which the permanent magnets are arranged 180° offset against one another, are slightly offset relative to the axis A S  to the closed end of the readiness position  9 ′ which is opposite the joining channel  9 , where the sensor  20  is also located, so that the respective nut  2  which is produced from ferromagnetic material (steel) is moved centered into the readiness position  9 ′ and is also held there by the permanent magnets  21 . 
     As the figures show, the plunger end  12  in the initial position of the plunger  11  has a distance from the plane of the top of the joining channel  9  and thus a distance a) from the top of the nut  2  which is ready at the readiness position  9 ′. At the readiness position  9  there are furthermore two catches  22  which in the embodiment shown are each made as an angle piece with two legs  22 ′ and  22 ″ and which are pivotally supported on the free end of the leg  22 ′ around the axis  23  parallel to the lengthwise extension of the joining channel  9 , against the action of a reset spring  24 . With its legs  22 ″ the catches  22  project laterally into the joining channel  9  on the transition to the readiness position  9 ′ and with the top of their leg  22 ″ facing the leg  22 ′ in the initial position form a guide surface for the nuts  2 , i.e. the continuation of the lower guide surface of the loading channel  13 . When the plunger  12  moves with a nut  2  which is entrained with the plunger  12  and which ad joins the plunger surface  12  out of the readiness position  9 ′ into the joining channel  9 , the two catches  22  are pressed to the side against the action of the reset springs  24 . The joints  23  are located in the representation chosen in the figures above the leg  22 ″, i.e. at a distance from the plane of the annular surface  10  which is greater than the corresponding distance which the legs  22 ″ have from this plane E R . 
     In the embodiment shown, the loading channel  13  and the readiness position  9 ′ are made in the upper head piece part  7 ′. In this head piece part there are also two catches  22  and they are pivotally supported with the joints  23 . 
     The motion of the plunger  11  out of the initial position into the joining position takes place in the conventional manner in that the tool or the press acts on the end  11 ′ of the plunger projecting over the housing  8 , i.e. for each working stroke of the press, first the punching head together with the blank holder  3  is moved toward the bottom  4  of the tool so that the workpiece  1  is clamped on the area at which a nut  2  is to be inserted between the punching head  6  or the annular contact surface  10  and the area  4 ′ of the bottom part of the tool. In the further working stroke of the press then the top part of the tool which is not shown acts on the end  11 ′ of the plunger  12  so that the plunger  11  together with the nut  2  provided on the plunger end  12  moves as the catch  22  is pressed from overhead into the joining channel  9  for joining and pressing the nut  2  in the workpiece  1 . 
     The return stroke of the plunger  11  from the joining position into its initial position can take place for example by a reset spring which is held in the housing  8 , but in the embodiment shown it takes place by compressed air. For this purpose the housing  8  forms a cylinder with a piston  26  attached to the plunger  11 , able to move in its cylinder space  25 . The annular cylinder space  25  which surrounds the plunger  11  underneath the piston  26 , i.e. on the side facing the head piece  7 , is connected via a connection  27  to a compressed air source, for example permanently. This compressed air source is thus made such that it enables volume equalization such that the cylinder space  25  acts as a “pneumatic spring” which pretensions the plunger  11  into its initial position and which is pressed from overhead out of the initial position when the plunger  11  moves. 
     Above the piston  26 , i.e. on the side of this piston facing away from the head piece  7 , in the housing  8  a second annular cylinder space  28  which surrounds the plunger  11  is formed and can be exposed to compressed air in a controlled manner via a connection  29 , such that the plunger  11  is moved out of its initial position into the joining position or is held in this joining position in order to block the joining channel  9  or the readiness position  9 ′ there relative to the loading channel  13 , for example in case of problems or in those cases in which a nut is not to be inserted into the workpiece  1  with the punching head  6 . This control of the plunger  11  via the cylinder space  28  among others makes it possible to produce workpieces  1  selectively with or without nuts  2  using the same tool  5  and/or for several punching heads  6  provided on the tool  5  to provide nuts  2  at certain areas of the respective workpiece  1  or selectively also omit them. 
     The pressure of the controlled compressed air for the cylinder space  28  is chosen such that in spite of the pressure which prevails in the cylinder space  25  the plunger  11  is moved into its joining position and/or held there. Basically it is also possible to control the compressed air feed to the cylinder space  25  such that the cylinder space  25  is vented when the cylinder space  28  is supplied with compressed air in a controlled manner. 
     The feed of the nuts  2  from an external supply unit via the supply hose  19  on the punching head  6  takes place for example individually such that each nut  2  is injected into the loading channel  13  using compressed air via the supply hose  19  and the feed  16  and finally also travels to the readiness position  9 ′ via this delivery air. The injection can take place independently of the motion of the tool or the press of course such that at the start of each working stroke of the press and thus at the start of the motion of the plunger  11  out of the initial position in the direction of the joining position a nut  2  is ready at the readiness position  9 ′. Regardless of this requirement the injection of the nuts  2  can take place independently of the motion of the press or the tool, for example in the form that a nut  2  is injected and is located in the loading channel  13  before the plunger  11  has moved back into its initial position at the end of the working stroke. The nut  2  then lies against the outside surface of the plunger which is moving back and blocking the readiness position  9 ′ so that the nut  2  is moved into the readiness position  9 ′ by the delivery air as soon as the plunger  11  has reached its initial position. The external delivery air is then for example permanently present and is turned off as soon as the signal of the sensor  20  is present. 
     The external delivery air emerges for example at the open end of the joining channel  9  or in the head piece  7  there is additionally an exit channel for this delivery air. The permanent magnets  21  center and also hold the respective nut  2  at the readiness position  9 ′, before the plunger  11  is moved again out of its initial position in the direction of the joining position. In the loading channel  13  there are no catches or similar elements at all which would have to be pressed from the top when the nuts  2  continue to move especially also into the readiness position  9 ′. Rather, the respective nut is moved as far as the readiness position  9  solely by the external delivery air flow without overcoming catches or the like and is held in position there by the external delivery air flow and/or the permanent magnets  21 . Because the plunger end  12  with the permanent magnets  14  in the initial position of the plunger is spaced apart from the top of the respective nut  2  (distance a), the position and location of the nut  2  in the readiness position  9 ′ is prevented from being adversely affected by this permanent magnet  14 . Basically it is also possible to provide for example projection-like contacts for the top of the respective nut  2  at the readiness position  9 ′, the contacts are then pressed elastically to the side by the plunger  11  moving out of the initial position into the joining position. 
     Thus, for example it is possible to make the external delivery air as continuous air and/or to deliver the nuts  2  with this external delivery air as continuous air or as injection air to the punching head  6  such that there are several nuts  2  in the loading channel  13  there. Especially when the nuts  2  are injected onto the punching head  6  before the return of the plunger  11  to its initial position it is also possible to check the presence of at least one nut  2  in the loading channel at a given time by means of a sensor  30  which is located in the loading channel  13 , and when a nut  2  is not present, to inject a nut  2  again into the punching head  6  before the next working stroke begins. 
     To support the external delivery air, an internal delivery air flow can also be produced in the direction of the readiness position  9 ′ for example by at least one compressed air exit nozzle on at least one coupling piece  17  or  18 , as is indicated in  FIG. 2  by  17 ′ and  18 ′. The air exit openings in channels  13  and  15  provide for decoupling of the external delivery air flow and the internal delivery air flow, i.e. preventing the internal delivery air flow from counteracting the external delivery air flow. 
     Furthermore it is possible, instead of the permanent magnets  14  or in addition to these permanent magnets, on the plunger end  12  to provide at least one nozzle opening which can be exposed to negative pressure, in order to keep the respective nut  2  on the plunger end  12  even if it consists of a nonmagnetic material, then this negative pressure being controlled such that it is turned on only with the plunger moving out of the initial position. Likewise it is also possible, instead of the permanent magnets  21  or in addition to them, to provide at the readiness position  9 ′ vacuum openings which hold and center the respective nut  2  at the readiness position  9 ′ even if this nut consists of nonmagnetizable material. 
     In particular, the vacuum or the negative pressure is turned on at at least one negative pressure exit opening provided on the plunger surface  12  only when the pertinent nut  2  is located at the readiness position  9 ′, in order not to adversely affect delivery of the nut  2  to the readiness position  9 ′ by the delivery air. 
     Furthermore, it was assumed above that the punching head  2  is located on the blank holder of the tool  5 . Of course, the tool can also be built differently, thus the punching head  6  can be provided spring-mounted on one tool part, for example on the upper part of the two-part tool which is not shown in the Figures. Of course it is also possible to use the punching head  6  for example in turned form, i.e. with the annular contact surface  10  lying at the top on the bottom part of the tool or on a spring bottom. 
       FIGS. 7 and 8  in a side view and in a sectional show a feed or injection position or means of an external supply unit which is not otherwise detailed and via which the nuts  2  are inserted into the external supply hose  19  in succession. 
     This feed and injection means labelled  32  generally in  FIGS. 7 and 8  consists essentially of a guide  33  which is tilted relative to the horizontal in the embodiment shown, and into which the nuts  2  are inserted for example via a vibration head from a disordered set and in which the nuts are moved by the tilt in the direction of the arrow A by the force of gravity, such that the nuts  2  in the guide  33  form a row in which the nuts  2  tightly ad join one another, oriented with the axis of their thread perpendicular to the lengthwise direction of the guide  33 . The end of the guide  33  on one side ad joins the end of the supply hose  19  away from the punching head  6  such that the lengthwise extension of the supply hose  19  or of the channel  19 ′ which is formed in this supply hose and which is matched in its cross section to the shape of the nuts  2  is perpendicular to the axis of the guide  33 . On the side of the guide  33  opposite the supply hose  19  there is an actuating element  34  for a ram  35  with which by activating the actuating element  34  the nut  2  which is already at the pertinent end of the guide  33  is moved into the channel  19 ′. The guide there is formed partially by an elastic catch  33 ′. 
     On the connecting piece  36  with which the supply hose  19  is connected to the guide  33 , there are compressed air exit nozzles  37  which are connected for example permanently to a compressed air source which is not shown, for producing the delivery air with which each nut  2  is delivered or injected by the feed unit  32  to the punching head  6 . Each nut  2  is moved with the ram  35  into the channel  19 ′ so far that this nut is located in the flow direction of the delivery air behind the nozzles  37  and thus entrained with the delivery air emerging from the nozzles  37  and is injected onto the punching head  6 . The ram  35  is preferably controlled by the actuating element  34  such that the ram  35  normally closes the channel  19 ′ and is moved briefly out of the channel  19 ′ only for injection of a new nut  2  and then is moved back again into the channel  19 ′ together with the new nut  2 . 
       FIG. 9  shows in a representation similar to  FIG. 1  a fastener  2   a  which is anchored in the workpiece  1  and which is made as a pin. The tool  5  with a punching head  6   a  is again reproduced in  FIG. 10 . This punching head  6   a  differs from the punching head  6  simply in that the punching head  6   a  is made for processing of pin-like fasteners  2   a . They are supplied to the punching head  6   a  via this external supply hose  19   a  and travel via a punching head-side feed  16   a  and the loading channel  13   a  to the readiness position  9 ′, the pin-like fasteners with their pin axes being oriented perpendicular to the delivery direction. The loading channel  13 , the internal channel  15  and the guide channel which is formed in the external supply hose  19   a  are matched to the shape which the pin-shaped fasteners  2   a  have, i.e. in cross section made roughly T-shaped. 
     It was assumed above that the channel  19 ′ is closed by the ram  35 . Other means, for example, one or more flaps, can be provided to at least partially close the channel  19 ′ after insertion of a joining part ( 2  or  2   a ) in the flow direction of the delivery air before the air inlet nozzles  37 . 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Reference number list 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                  1 
                 workpiece 
               
               
                   
                  2 
                 nut 
               
               
                   
                  2a 
                 pin 
               
               
                   
                  3 
                 blank holder 
               
               
                   
                  4 
                 bottom part of the tool 
               
               
                   
                  4′ 
                 tool area 
               
               
                   
                  5 
                 tool 
               
               
                   
                  6, 6a 
                 punching head 
               
               
                   
                  7 
                 head piece of the punching head 
               
               
                   
                  7′ 
                 top head piece part 
               
               
                   
                  7″ 
                 bottom head piece part 
               
               
                   
                  8 
                 housing 
               
               
                   
                  9 
                 joining channel 
               
               
                   
                  9′ 
                 readiness position 
               
               
                   
                 10 
                 annular contact surface 
               
               
                   
                 11 
                 plunger 
               
               
                   
                 11′ 
                 top plunger end 
               
               
                   
                 12 
                 bottom plunger end 
               
               
                   
                 13, 13a 
                 loading channel 
               
               
                   
                 14 
                 permanent magnet 
               
               
                   
                 15, 15a 
                 channel 
               
               
                   
                 16, 16a 
                 feed 
               
               
                   
                 17 
                 coupling piece 
               
               
                   
                 17′ 
                 compressed air exit nozzle 
               
               
                   
                 18 
                 coupling piece 
               
               
                   
                 18′ 
                 compressed air outlet nozzle 
               
               
                   
                 19, 19a 
                 external supply hose 
               
               
                   
                 19′ 
                 channel of the external supply hose 
               
               
                   
                 20 
                 sensor 
               
               
                   
                 21 
                 permanent magnet 
               
               
                   
                 22 
                 catch 
               
               
                   
                 22′, 22″ 
                 leg 
               
               
                   
                 23 
                 joint 
               
               
                   
                 24 
                 reset spring 
               
               
                   
                 25 
                 cylinder space 
               
               
                   
                 26 
                 piston 
               
               
                   
                 27 
                 connection 
               
               
                   
                 28 
                 cylinder space 
               
               
                   
                 29 
                 connection 
               
               
                   
                 30 
                 sensor 
               
               
                   
                 32 
                 delivery unit 
               
               
                   
                 33 
                 guide 
               
               
                   
                 33′ 
                 spring-mounted catch 
               
               
                   
                 34 
                 actuating element 
               
               
                   
                 35 
                 ram 
               
               
                   
                 36 
                 connecting piece 
               
               
                   
                 37 
                 compressed air nozzle 
               
               
                   
                 a 
                 distance 
               
               
                   
                 A 
                 direction of motion 
               
               
                   
                 A S   
                 plunger axis 
               
               
                   
                 A M   
                 axis of the nut 
               
               
                   
                 E R   
                 plane of the annular contact surface 10