Device and method for measuring and adjusting pressing load values on a press

A method of adjusting local pressing load values on a press having a press slide connected to a reciprocating member of a drive mechanism through a plurality of fluid-actuated cylinders and vertically reciprocated by said reciprocating member, said local pressing load values acting on said press slide at respective local portions thereof through said fluid-actuated cylinders, respectively, when a pressing operation on a workpiece is performed by a reciprocating action of said press slide with an upper die attached thereto, said method comprising the steps of:

• measuring the actual local pressing load values at said local portions of said press slide corresponding to said plurality of fluid-actuated cylinders by attaching a plurality of strain sensors to respective members of the press corresponding to said local portions of the press slide, obtaining said actual local pressing load values on the basis of output signals of said strain sensors, storing in memory means data maps representative of respective relationships between the output signal levels of said strain sensors and the actual local pressing load values at said local portions of the press slide, and converting the output signal levels of said strain sensors into said actual local pressing load values according to said respective relationships;
• and
• adjusting pressure values of a fluid in said plurality of fluid-actuated cylinders independently of each other so that the measured actual local pressing load values at said local portions of the press slide substantially coincide with respective predetermined optimum values.

A method of adjusting local pressing load values on a press having a press slide which is connected to a reciprocating member of a drive mechanism through a plurality of fluid-actuated cylinders and which is vertically reciprocated by said reciprocating member, said local pressing load values acting on said press slide at respective local portions thereof through said fluid-actuated cylinders, respectively, when a pressing operation on a workpiece is performed by a reciprocating action of said press slide with an upper die attached thereto, said method comprising the steps of:

• measuring the actual local pressing load values at said local portions of said press slide corresponding to said plurality of fluid-actuated cylinders;
• and
• adjusting pressure values of a fluid in said plurality of fluid-actuated cylinders independently of each other so that the measured actual local pressing load values at said local portions of the press slide substantially coincide with respective predetermined optimum values, said step of adjusting pressures values of a fluid in said plurality of fluid-actuated cylinders independently of each other comprising determining whether a difference between each of the measured actual local pressing load value and a corresponding one of said predetermined optimum values is larger than a predetermined upper limit, and changing the pressure value of the fluid in a corresponding one of said fluid-actuated cylinders if said difference is larger than said predetermined upper limit.

A method of adjusting local pressing load values on a press having a press slide which is connected to a reciprocating member of a drive mechanism through a plurality of fluid-actuated cylinders and which is vertically reciprocated by said reciprocating member, said local pressing load values acting on said press slide at respective local portions thereof through said fluid-actuated cylinders, respectively, when a pressing operation on a workpiece is performed by a reciprocating action of said press slide with an upper die attached thereto, said method comprising the steps of:

• measuring the actual local pressing load values at said local portions of said press slide corresponding to said plurality of fluid-actuated cylinders;
• adjusting pressure values of a fluid in said plurality of fluid-actuated cylinders independently of each other so that the measured actual local pressing load values at said local portions of the press slide .substantially coincide with respective predetermined optimum values;
• and
• connecting said fluid-actuated cylinders to a common pressure source through respective pressure control means, and wherein said step of adjusting pressure values of a fluid in said plurality of fluid-actuated cylinders independently of each other comprises adjusting said pressure values by controlling said respective pressure control means.