Patent Publication Number: US-RE39624-E

Title: Feed head

Description:
INTRODUCTION AND BACKGROUND 
     The present invention relates to a feed head for receiving nuts which are to be fixed to sheet material in a pressing operation. GB-A-1 474 766 describes a nut which is attached to sheet metal by a pressing operation. The nut has a tubular end which is pressed into an aperture in the sheet metal, deforming the rim of the aperture into a cylinder to embrace the periphery of the nut. The tubular end is turned around the rim to secure the nut against removal, while a flange at the other end of the nut prevents the nut being pushed completely through the aperture. Such nuts are sold by the present applicants under the trade mark FLANGEFORM. 
     To increase production speeds when attaching the nuts to sheet material, the applicants have developed a feed head for receiving the nuts and feeding them one at a time to a pressing station. 
     The feed head needs to be robust enough to withstand the forces exerted in a pressing operation; compact enough to fit easily in a press, to be reliable in operation; and to be easily maintained. A particular difficulty occurs when feeding nuts to the pressing station in that the orientation of nuts is not readily controlled. Thus, it is important to be able to gain access to the feed head and pressing station to remove any nuts which are blocking the feed head. 
     SUMMARY OF THE INVENTION 
     A first aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, the pressing station having a pressing die which is reciprocated transversely to the delivery path under the action of a press to fasten a nut to a sheet metal member, wherein means is provided to reciprocate the pressing die manually. 
     Preferably the means for reciprocating the pressing die comprises a cam which bears on a surface coupled to the die and is rotated to move the die against the force of a return spring. 
     By providing for manual operation of the pressing die, the procedure for clearing the feed head of any obstruction, such as a wrongly oriented nut is greatly facilitated. 
     Preferably, the cam can be used to hold the pressing die in its depressed position. This allows for the press to be operated without operation of the feed head. 
     Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, in which a sensor is provided at the end of the delivery path, at the pressing station, to detect the presence of a nut. 
     By positioning the sensor at the end of the delivery path, rather than to one side, the feed head can be made narrower at the pressing station, allowing multiple feed heads to be used close together. 
     Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, in which a first sensor is provided at the pressing station and a second sensor is provided up stream of the feed head. By providing the second sensor up stream of the feed head it is possible to detect problems before a nut arrives, or is due to arrive, at the pressing station, which provides for better control. 
     Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, comprising a delivery tube connected to the delivery path for delivering nuts to the delivery path, and an electrical connector for connecting sensors in the feed head to external components, wherein the delivery tube and electrical connector are integrated. Providing a single, integrated connector greatly facilitates connection and disconnection of the feed head to ancillary equipment, the nut feeder and control electronics, allowing for the feed head to be mounted in a space with restricted access. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects, preferred features and advantages of the invention will be apparent from the following description and the accompanying claims. 
       In the drawings, 
         FIG. 1  is a cross-section through a feed head forming an embodiment of the invention, along line I—I of  FIG. 2 ; and 
         FIG. 2  is an end view of the feed head of FIG.  1 , 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , a feed head  2  has a pressing die  4  which is shown in its uppermost position. The pressing die  4  reciprocates in a stationary feed head body  6 . The pressing die  4  has a peripheral flange at its upper end held between a collar  8  and a cover plate  10 . A hollow cylinder  12  is also held by a flange  13  at its upper end between the cover plate  10  and collar  8 . A spring  14  urges the cylinder  12  upwards, and hence the cover plate  10 , collar  8  and pressing die  4 . A press (not shown) pressed down on the cover plate  10  to urge the die  4  downwards against the force of the spring  14 . 
     A delivery path  16  is provided at the bottom of the body  6  and ends at  18  under the pressing die  4 . 
     Nuts are fed along the delivery path  16  from a delivery tube  20  which in turn is filled from a parts feeder (not shown). As seen in  FIG. 2 , delivery path  16  is trapezium shaped, being wider at the upper part to receive a laterally extending flange of a nut  22 , seen in  FIG. 2 , and to maintain the orientation of nuts  22  as they pass along the path  16 . 
     In operation, nuts  22  are urged along the delivery path  16  from the parts feeder. When a nut reaches the end  18  of the delivery path  16  it is sensed by a sensor  24  which sends a signal to the press to indicate that the feed head is ready for a pressing operation. The press bears on the plate  10 , to depress the die  4 , and hence urge the nut downwards onto the sheet metal part (not shown) to which the nut is to be fixed. A co-operating die (also not shown) sits under the sheet metal part to deform the nut  22  as it penetrates an aperture in the sheet metal part and so secure the nut in place. 
     Immediately upstream of the pressing die  4  is a locating pin  26 . Pin  26  has a nose  28  which serves to locate and centralize or orient the penultimate nut in the delivery path  16 . Pin  26  is urged downwards by a spring  30 , but held by a cross-pin  32  which extends from the pin  26  and bears on a flange  34  at the bottom of the cylinder  12 . As cylinder  12  is lowered (when the press bears on cover plate  10 ), spring  30  extends to urge the pin  28  downwards. 
     Further upstream of pin  26  is a second sensor  34  which serves to detect the ante-penultimate nut in the delivery path  16 . 
     Sensors  24 ,  34  are wired to an electrical outlet connector  36  which is located immediately above the inlet end  38  of the delivery path  16 . 
     An integrated connector  40  comprises a complementary electrical connector  42  to mate with a connector  36 , and delivery tube  20  which mates with the inlet end  30  of delivery path  16 . 
     Above the connector  36  is a cam  44 . Cam  44  has an exposed hexagonal socket  46  and rotates in a circular bore  48  in the body  6 . At the other end of the cam  44  is a nose  50  which engages a flange  52  at the bottom end of the cylinder  12 . As the cam  44  is manually rotated, by means of a hexagon key inserted in the bore  46 , the nose  50  rotates and so urges the cylinder  12  downwards against the force of the spring  14 , and hence also pulls the pressing die  4  downwards. It will be appreciated that when the cam  44  is rotated through 180 degrees, the nose  50  reaches the bottom of its travel, and the cam can be temporarily “locked” in this position, for example by a small flat provided on the nose  40  where it engages the flange  52 . 
     In use, the feed head  2  is installed a press, and is connected to a parts feeder and control system via connector  40 . Nuts  22  are fed from a parts feeder along delivery tube  20 . The parts feeder is controlled by signals from sensors  24 ,  34  which indicate the presence of nuts in the delivery path  16 . The press is sent a “ready” signal when a nut is detected by sensor  24 . 
     In the event of a jam in the delivery path, or elsewhere in the system, the pressing die  4  can be actuated manually, by rotation of cam  44 , to eject nuts from the delivery path  16 . Also, if it is desired to operate the press without actuation of the feed head pressing die  4 , the die  4  can be head in its lowered position by cam  20 . 
     By locating the sensor  24  at the axial end of the delivery path  16 , the feed head can be made narrow, as seen in FIG.  2 . Thus multiple feed heads can be spaced close together.