End-forming toggle-press

Abstract

The press has a punch that slides in a punch-guide, and a ram that slides in a ram-guide, ther respective lines of action forming a T-configuration, whereby one unidirectional stroke of the ram-head provides a complete in/out stroke of the punch. The ram is driven by a prime-mover, which may be a hydraulic ram coupled directly to the ram-head, or preferably is a ball-screw-jack operated by an electric servo motor, under computer control. The ratio between the prime-mover and the ram-head remains constant throughout the stroke of the ram-head.

1 . Punch press, wherein: 
 the press includes a die, for holding a workpiece;    the press includes a punch-head, and a punch mounted therein;    the press is arranged such that, in operation, the punch moves towards and away from the workpiece in the die, as the punch-head moves along a line termed the punch-line;    the press includes a punch-head-guide, for guiding the punch-head along the punch-line;    the press includes a ram-head, and includes a ram-head-guide, for guiding the ram-head along a ram-line;    the arrangement of the press is such that the punch-line and the ram-line intersect, at a point-of-intersection, to form a T;    the configuration of the T is such that the ram-line comprises the cross-bar of the T, and the punch-line comprises the stem of the T;    the press includes a toggle-lever, having a punch-end and a ram-end;    a punch-end-connection connects the punch-end of the toggle-lever to the punch-head;    a ram-end-connection connects the ram-end of the toggle-lever to the ram-head;    the arrangement of the press is such that, during operation, the punch-head undergoes a punch-cycle of movement, being movement of the punch-head along the punch-line from a punch-withdrawn start-position, to a punch-extended position, and back to a punch-withdrawn finish-position;    the arrangement of the press is such that, during operation, the ram-head undergoes a ram-cycle of movement, being movement of the ram-head along the ram-line from a start-point, through the point-of-intersection, to a finish-point;    the arrangement of the press is such that, during operation, the punch-cycle corresponds to the ram-cycle;    the point-of-intersection lies on the ram-line, intermediate between the start-point and the finish-point;    the punch-extended position of the punch-head occurs when the ram-end-connection is at the point-of-intersection;    the arrangement of the press is such that when the punch-head lies at its fully extended position, the ram-head lies at the point-of-intersection, and the toggle-lever is aligned dead-centre with the punch-line, in that a line joining the punch-end-connection to the ram-end-connection lies along the punch-line;    whereby the finish-point of the ram-head lies on the opposite side of the point-of-intersection from the start-point of the ram-head;    the press includes an operable ram-actuator;    the ram-actuator is effective, when operated, to drive the ram-head forcefully along the ram-line, from its start-point, through the point-of-intersection, to its finish-point, all in a first ram-sense along the ram-line;    the ram-actuator includes a prime-mover, having a fixed-element fixed to the frame of the press, and having a movable-element, the prime-mover being an apparatus that converts prime energy from an energy source into powered mechanical motion of the movable-element along a prime-line;    the ram-actuator includes a force-transmission-assembly, for converting forceful movement of the movable-element of the prime-mover along the prime-line into forceful movement of the ram-head along the ram-line;    the force-transmission-assembly is so arranged as to introduce and define a mechanical-ratio between the movement of the movable-element of the prime-mover along the prime-line and the movement of the ram-head along the ram-line;    and the structural arrangement of the ram-actuator is such that the mechanical-ratio when the ram-head is at the point on the ram-line where the mechanical-ratio is largest, is no more than double the mechanical-ratio when the ram-head is at the point on the ram-line where the mechanical ratio is smallest.    
     
     
         2 . Apparatus of  claim 1 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 the mechanical-ratio between the movable-element of the prime-mover and the ram-head, as introduced by the force-transmission-assembly, varies with the position of the ram-head along the ram-line;    and the mechanical-ratio is largest when the ram-head is at the point-of-intersection.    
     
     
         3 . Apparatus of  claim 1 , wherein the structural arrangement of the ram-actuator is such that, in operation, as the ram-head moves from its start-point through the point-of-intersection to its finish-point, the said mechanical-ratio remains substantially the same.  
     
     
         4 . Apparatus of  claim 3 , wherein the structural arrangement of the ram-actuator is such that, in operation, after the ram-head reaches the said finish-point, the ram-head reverses its direction of travel and travels back along the ram-line, all in the opposite ram-sense to the said first ram-sense along the ram-line, from the said finish-point, through the point-of-intersection, back to the said start-point of the ram-head.  
     
     
         5 . Apparatus of  claim 4 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 the ram-head undergoes movement along the ram-line, in correspondence to the movement the movable-element of the prime-mover undergoes relative to the fixed-element along the prime-line;    and the ram-head undergoes a reversal of movement only when the movable-element undergoes a reversal of movement, and in correspondence thereto;    whereby, when the movement of the ram-head along the ram-line is all in the said first ram-sense, the movement of the movable-element is all in a corresponding first prime-sense along the prime-line.    
     
     
         6 . Apparatus of  claim 5 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 the movable-element of the prime-mover undergoes movement relative to the fixed-element, along the prime-line, in correspondence to the movement the ram-head undergoes along the ram-line;    when the movement of the ram-head along the ram-line is all in the said first ram-sense, the corresponding movement of the movable-element is all in a corresponding first prime-sense along the prime-line;    and when the movement of the ram-head along the ram-line is all in the said opposite ram-sense along the ram-line, the corresponding movement of the movable-element along the prime-line is all in the opposite prime-sense to the said first prime-sense along the prime-line.    
     
     
         7 . Apparatus of  claim 1 , wherein the force-transmission-assembly comprises a direct mechanical connection between the movable-element of the prime-mover and the ram-head, having no capacity for relative movement.  
     
     
         8 . Apparatus of  claim 7 , wherein the prime-line is co-linear with the ram-line.  
     
     
         9 . Apparatus of  claim 8 , wherein the prime-mover is a hydraulic ram.  
     
     
         10 . Apparatus of  claim 1 , wherein the prime-line is a circle, being the line of movement of a point on the armature of an electric motor, about the axis of the motor.  
     
     
         11 . Apparatus of  claim 10 , wherein the force-transmission-assembly includes a re-circulating-ball screw-jack, driven by the electric motor.  
     
     
         12 . Apparatus of  claim 1 , wherein the force-transmission-assembly includes the said mechanical-ratio as a gear-ratio, and the gear-ratio remains constant during operation.  
     
     
         13 . Apparatus of  claim 1 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 when the ram-head lies at its start-point on the ram-line, the toggle-lever lies inclined at no more than about sixty degrees to the punch-line, in a first sense;    and when the ram-head lies at its finish-point on the ram-line, the toggle-lever lies inclined at no more than about sixty degrees to the punch-line, in the opposite sense.    
     
     
         14 . Apparatus of  claim 13 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 when the ram-head lies at its start-point on the ram-line, the toggle-lever lies inclined at about forty-five degrees to the punch-line, in a first sense;    and when the ram-head lies at its finish-point on the ram-line, the toggle-lever lies inclined at about forty-five degrees to the punch-line, in the opposite sense.    
     
     
         15 . Apparatus of  claim 13 , wherein the structural arrangement of the ram-actuator is such that, in operation: 
 when the ram-head lies at its start-point on the ram-line, the toggle-lever lies inclined at more than about thirty degrees to the punch-line, in a first sense;    and when the ram-head lies at its finish-point on the ram-line, the toggle-lever lies inclined at more than about thirty degrees to the punch-line, in the opposite sense.    
     
     
         16 . Apparatus of  claim 1 , wherein: 
 the ram-actuator includes a start-point-adjuster, which is effective to adjust the start-point of the ram-head on the ram-line;    the ram-actuator includes a finish-point-adjuster, which is effective to adjust the finish-point of the ram-head on the ram-line.    
     
     
         17 . Apparatus of  claim 16 , wherein the start-point-adjuster and the finish-point-adjuster comprise: 
 a means for measuring the distance of travel of the movable-element along the prime-line;    a means for reversing the directional sense of the movement of the movable-element along the prime-line when the movable-element reaches a set-point;    and a means for moving the set-point along the prime-line.    
     
     
         18 . Apparatus of  claim 17 , wherein: 
 the force-transmission-assembly includes a re-circulating-ball screw-jack, driven by an electric motor, the motion of which is under the control of a computer, as to the extent of the travel of the movable-element along the prime-line;    and the means for moving the said set-point along the prime-line comprises a means for controlling the computer.    
     
     
         19 . Apparatus of  claim 1 , wherein the structural arrangement of the ram-actuator is such that, in operation, the punch-line is a straight line, and the ram-line is a straight line at right angles to the punch-line.  
     
     
         20 . Apparatus of  claim 19 , wherein the ram-head-guide includes a fixed ram-head-abutting-surface, which faces towards the punch, and against which the ram-head slides as the ram-head moves along the ram-line.  
     
     
         21 . Apparatus of  claim 20 , wherein: 
 the ram-head-abutting-surface is a flat, straight surface;    the ram-head includes an abutment-surface, which is correspondingly flat and straight, and which slides and rubs directly against the ram-head-abutting-surface as the ram-head moves along the ram-line;    the ram-head-abutting-surface is aligned at right angles to the punch-line;    and the structural arrangement of the apparatus is such that, at dead-centre, all the force acting along the punch-line on the punch is reacted to the frame of the apparatus through the direct engagement of the said surfaces.    
     
     
         22 . Apparatus of  claim 1 , wherein: 
 the press includes a plurality of punches, and includes a magazine in which the punches are mounted;    and the press includes an operable indexing-means, which is effective, when operated, to index the magazine, and thereby to move one of the punches into a position in which the said one of the punches is co-linear with the punch-line.    
     
     
         23 . Apparatus of  claim 22 , wherein the structural arrangement of the indexing-means is such that, when the press is operated, and the punch-head moves towards and away from the punch-extended position, along the punch-line, the whole magazine, with the punches carried therein, moves, as a whole unit, in unison with the punch-head.  
     
     
         24 . Apparatus of  claim 1 , wherein the workpiece comprises a length of hollow tubing.  
     
     
         25 . Apparatus of  claim 1 , wherein: 
 the press includes first and second jaws, for clamping the workpiece, and includes an operable clamping-means, which is effective, when operated, to hold the workpiece securely, as the press is operated;    the clamping-means includes respective operable first and second jaw-movers;    the clamping-means includes a jaw-datum, located on the fixed frame of the press;    the first jaw-mover is effective, when operated, to move the first jaw into abutment against the jaw-datum;    the second jaw-mover is effective, when operated, to move the second jaw into abutment against the first jaw;    the clamping-means includes a locking-means, which is effective to hold the first jaw in abutment against the jaw-datum when the second jaw moves into abutment against the first jaw.