Computer directed loading and unloading devices

A power press arrangement comprising:

• (a) a power press having a press drive, a slide and a working area;
• (b) an element having controlled motion in a loader mechanism for carrying a workpiece into the working area of the press;
• (c) means for monitoring the position of the press drive and its associated slide;
• (d) means for monitoring the motion of the element (b);
• (e) a memory for storing data correlating desired positions for the element (b) with positions of the press drive and its associated slide;
• (f) means for deriving theoretical motion parameters for the element (b) from press position information monitored by the means (c) and the data of the memory (e);
• (g) means for comparing the theoretical motion derived by the means (f) with the motion monitored by the means (d);
• and
• (h) means for controlling the motion of the element (b) based upon the results of the comparisons by the means (g).

A power press arrangement comprising:

• (a) a power press having a press drive, a slide and a working area;
• (b) an element having controlled motion in an unloader mechanism for moving a workpiece out of the working area of the press;
• (c) means for monitoring the position of the press drive and its associated slide;
• (d) means for monitoring the motion of the element (b);
• (e) a memory for storing data correlating desired positions for the element (b) with positions of the press drive and its associated slide;
• (f) means for deriving theoretical motion parameters for the element (b) from press position information monitored by the means (c) and the data of the memory (e);
• (g) means for comparing the theoretical motion derived by the means (f) with the motion monitored by the means (d);
• and
• (h) means for controlling the motion of the element (b) based upon the results of the comparisons by the means (g).

In a press line for performing a series of press operations on a workpiece including a series of power presses each having an individual press drive for cycling a slide in and out of a working area, and conveyors extending between the working areas of adjacent presses, the improvement comprising a conveyor control arrangement for a conveyor associated with each power press comprising:

• (a) means for producing a timing signal representing successive increments of each press cycle of one of the presses;
• (b) means for monitoring the position of the conveyor drive;
• (c) a memory for storing data correlating desired positions for the conveyor with successive increments of each press cycle;
• (d) means for deriving theoretical motion parameters for the conveyor from said timing signal and the data of the memory (c);
• (e) means for comparing the theoretical motion derived by the means (d) with the motion monitored by the means (b);
• and
• (f) means for controlling the motion of the conveyor drive based upon the results of the comparisons by the means (e).

A method of synchronizing the operation of auxiliary apparatus such as loaders, unloaders and conveyors with each of the press drives of a line of power presses comprising the steps of:

• (a) deriving a set of auxiliary equipment position values for a cycle of a press drive;
• (b) driving the press;
• (c) continuously determining the position of the press drive;
• (d) correlating successive press drive positions with the derived auxiliary equipment positions to continuously determine theoretical auxiliary equipment positions;
• (e) continuously monitoring the position of the auxiliary equipment;
• and
• (f) positioning the auxiliary equipment in said theoretical positions based upon the deviation between theoretical and actual auxiliary equipment position values.

A method of synchronizing the operation of auxiliary apparatus such as loaders, unloaders and conveyors with the press drives of each press of a line of power presses comprising the steps of:

• (a) entering a set of discrete position locations corresponding to auxiliary equipment positions at specific points during a press drive cycle;
• (b) deriving a larger set of position locations for the auxiliary equipment corresponding to press drive positions to form a table of auxiliary equipment position values;
• (c) driving the press;
• and
• (d) positioning the auxiliary equipment based upon said table of values during each cycle of press drive operation.

In a press line for performing a series of press operations on a workpiece including a series of power presses each having an individual press drive, slide and working area, an improved transfer mechanism arrangement comprising:

• (a) a plurality of elements each having controlled motion in a mechanism for moving a workpiece relative to the working areas of the presses;
• (b) means for monitoring parameters indicative of the press drive positions;
• (c) means for monitoring the motion of each of the elements (b);
• (d) a memory for storing data correlating desired positions for each of the elements (b) with the press drive position parameters;
• (e) means for deriving theoretical motion parameters for each of the elements (b) from the press position parameters of the means (b) and the data of the memory (d);
• (f) means for comparing the theoretical motion derived by the means (e) with the motion monitored by the means (c);
• and
• (g) means for controlling the motion of each of the elements (b) based upon the results of the comparison by the means (f).

A method of controlling a workpiece handling mechanism associated with a power press having a slide mounted for controlled reciprocating movement along a selected axis, the workpiece handling mechanism being mounted for controlled movement along at least two different axes, said method comprising the steps of

• producing signals representing the actual position of the workpiece handling mechanism along both its axes during the movement of said mechanism along said axes,
• producing signals representing desired positions for said workpiece handling mechanism along both its axes at selected time intervals during a press cycle,
• deriving from said desired positions and said selected time intervals desired incremental positions for said workpiece handling mechanism along said axes at repetitive time increments within each of said selected intervals,
• utilizing said actual position signals and said desired incremental positions to produce a signal representing any error in the actual position of said mechanism in each of said repetitive time increments,
• deriving from said desired positions and said selected time intervals the desired velocity of movement of said workpiece handling mechanism along each of its axes within each selected time interval,
• driving said mechanism along each of said axes at a velocity which is a function of both said desired velocity and any position errors, and
• adjusting the duration of said time increments as a function of any position errors.

A method of controlling a plurality of mechanisms associated with a power press and mounted for controlled movement along a plurality of different axes, said method comprising the steps of

• producing command signals numerically representing desired positions for said controlled mechanisms along each of said axes at selected intervals of press cycle,
• monitoring the actual positions of said controlled mechanisms along each of said axes,
• deriving from said command signals desired positions for said controlled mechanisms along each of said axes at repetitive time increments within each of said selected intervals,
• comparing the actual and desired positions of said controlled mechanisms along each of said axes in each of said repetitive time increments, and measuring any errors in said actual positions in each of said time increments, and
• adjusting the velocity of each mechanism for which a position error is measured in any of said repetitive time increments, whereby all the controlled mechanisms move in precise synchronism with each other along the respective paths defined by said command signals.

A method of controlling workpiece handling mechanisms for moving successive workpieces along multiple axes to load and unload a power press having a slide mechanism mounted for controlled reciprocating movement along a selected axis, said method comprising the steps of

• producing command signals numerically representing successive positions along a desired path for each of said mechanisms, said positions having preselected time intervals therebetween so that said command signals also represent desired velocities for each of said mechanisms along said desired paths to permit closely coordinated movement of the various mechanisms along intersecting paths,
• advancing each of said mechanisms along said desired path at said desired velocities in accordance with said command signals,
• monitoring the actual position of each of said mechanisms as they are advanced along said paths, and producing signals representing said actual positions,
• deriving from said command signals desired positions for each of said mechanisms at repetitive time increments within each of said preselected time intervals between the successive positions represented by said command signals,
• comparing the actual and desired positions of each of said mechanisms in each of said time increments, and measuring any errors in said actual positions with respect to said desired positions in each of said time increments, and
• adjusting the velocity of each mechanism for which a position error is measured in any of said repetitive time increments, whereby all said mechanisms are advanced along said desired paths in precise synchronism with each other and without interfering with each other.