Adaptive control system for hydraulic press brake

In a press brake for bending metallic material sheet workpieces to a desired bend angle of the type having a movable forming member and a fixed forming member and an appropriate tooling set comprising a punch affixed to one of said movable forming member and said fixed forming member and a V-die affixed to the other of said forming members for producing the desired bend angle in the workpiece, means for moving said movable forming member toward said fixed forming member and reversing means for moving said forming member away from said fixed forming member, means for sensing the position of said movable forming member to produce a signal representative of the position thereof with respect to said fixed forming member, and means for sensing the actual force exerted against the workpiece by said movable forming member during a bending operation to produce a signal representative thereof, the improvement in combination therewith comprising digital data processing means responsive to said position and force signals for calculating and determining the precise reversal position at which to activate said reversing means to cause said movable forming member to begin moving away from said forming member in order to compensate for workpiece spring-back so as to produce with said particular punch and die set the desired bend angle in production workpieces, said processing means having a test workpiece test mode comprising:

• means for storing the measured thickness and the measured bend angle of each test workpiece;
• means for storing first sets of data pairs representative of the movable forming member position and force during bending of a plurality of test workpieces;
• means for calculating from said first sets of test workpiece data pairs information representative of the loading characteristics of said plurality of test workpieces;
• means for storing second sets of data pairs representative of the movable forming member position and forming force associated with said plurality of test workpieces during retraction of the movable forming member following reversal;
• means for calculating from said second sets of test workpieces data pairs information representative of the unloading characteristics of said plurality of test workpieces;
• means for calculating the position of the top of that one of said punch and die supporting each test workpiece;
• means for calculating from said information representative of said loading characteristics and unloading characteristics, said measured thicknesses and said measured bend angles of said test workpieces a first mathematical relationship between material strength, material thickness and bend angle;
• means for calculating from said movable member position data, said measured thicknesses and said measured bend angles of said test workpieces a second mathematical relationship between movable member position, material thickness and bend angle;
• said processing means having a production workpiece bend mode comprising:
• means for storing first sets of data pairs representative of the movable forming member position and force during bending of each subsequent production workpiece utilizing said particular punch and die set;
• means for calculating from said first sets of production workpiece data pairs information representative of the loading characteristics of each subsequent production workpiece;
• means for calculating, for each subsequent production workpiece, the thickness thereof from said previously calculated punch or die top position;
• and
• means for calculating, for each subsequent production workpiece, from said loading characteristics of each production workpiece, from said mathematical relationships and said thickness of each production workpiece, said reversal position for each production workpiece necessary to produce the desired bend angle therein with said particular punch and die set.

A method of bending a production workpiece to a desired unloaded bend angle during a forming cycle of a press brake provided with a punch and die set comprising:

• bending a plurality of test workpieces to one or more desired unloaded angles;
• measuring the loading characteristics of said plurality of workpieces during the bending of the test workpieces;
• recording ram position data for the punch during the bending of the test workpieces;
• measuring the unloading characteristics of said plurality of test workpieces as the test workpieces spring back from a loaded to an unloaded state;
• measuring the thickness and bend angle of each test workpiece;
• calculating from said loading and unloading characteristics, said measured thicknesses, said measured bend angles and said ram position data of said test workpieces relationships relating to said reversal position necessary to produce a desired bend angle for said punch and die set;
• commencing to bend a production workpiece utilizing said punch and die set;
• measuring the loading characteristics of said production workpieces during the bending thereof;
• calculating the thickness of said production workpiece;
• calculating for said production workpiece the reversal position necessary to produce the desired bend angle with said punch and die set utilizing said loading characteristics of said production workpiece, said relationships and said thickness of said production workpiece;
• and
• reversing said punch when its position is the same as said calculated reversal position.

In a press brake for bending a metallic material sheet workpiece to a desired bend angle of the type having a frame supporting a bed, a die member mounted on the bed, a ram displaceable with respect to said bed, a punch member mounted on the ram and configured to engage the die to produce the desired bend angle in the workpiece, means for moving the ram toward the bed and reversing means for moving the ram away from the bed, means for sensing the position of the ram to produce a signal representative of actual ram position, and means for sensing the actual force exerted against the workpiece during the bending operation to produce a signal representative of ram force, the improvement in combination therewith comprising digital data processing means responsive to said position and force signals for determining the precise point of punch penetration at which to activate said reversing means to cause ram reversal in order to compensate for workpiece spring-back so as to produce the desired bend angle in a production workpiece, said processor means including memory means and having a stored computer program resident in said memory means including:

• (a) a teach mode executing the steps of:
• (i) collecting ram force and ram position data during the bending of a plurality of test workpieces;
• (ii) measuring the thickness and bend angle of each test workpiece;
• (iii) calculating from said ram force and ram position data and said thickness and bend angle measurements relationships relating to the ram reversal position necessary to produce a desired bend angle;
• (iv) calculating the position of the top of said die;
• and
• (v) storing said calculated relationships and said die top position in said memory means;
• (b) and a bend mode for bending a production workpiece to a desired angle executing the steps of:
• (i) collecting production ram force and ram position data during bending of said production workpiece;
• (ii) recalling said die top position from said memory;
• (iii) calculating the thickness of said production workpiece utilizing said die top position;
• (iv) recalling said calculated relationships from said memory means;
• (v) calculating from said recalled relationships, said production workpiece force and position data and said workpiece thickness the position of ram reversal necessary to produce the desired bend angle in the production workpiece;
• (vi) repeating step (b)(v) if the ram position has not reached said calculated position of ram reversal;
• and
• (vii) activating said ram reversal means to reverse the ram if the ram position has reached said calculated point of ram reversal.