# US 6,357,334 B1 · Method and apparatus for the control of a die casting or similar machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,357,334 B1 - Document ID: US6357334B1 - Status: Granted - Kind: B1 - Application number: 09/386,554 - Filed: 1999-08-31 - Granted: 2002-03-19 - Earliest claimed: 1999-08-31 - Assignees: Tymac Controls Corporation - Inventors: John R. Mickowski - Web page: https://patentgrep.com/patent/US6357334B1 ## CPC - F15B 21/087: {Control strategy, e.g. with block diagram} - B22D 17/32: Controlling equipment - G05B 19/416: characterised by control of velocity, acceleration or deceleration (G05B19/19 takes precedence) - G05B 2219/42055: Pi control for speed - G05B 2219/45204: Die, mould making - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract An improved control system for die casting or similar machines wherein a closed loop velocity feedback circuit is supplemented with an integration circuit and two filtering circuits to compensate for the frequency response of the pilot valve in the die casting machine. The integration circuit serves to more accurately cause the velocity of an element being controlled to match the desired/commanded velocity, and also caused the velocity to more rapidly match the desired/commanded velocity. ## Claims ### Claim 1 A method of controlling a reciprocating apparatus, said method comprising the steps of: measuring a parameter of the reciprocating apparatus that is desired to be controlled, comparing said measured parameter to a desired value of said parameter to generate an error signal; integrating said error signal, and utilizing said integrated error signal to adjust said parameter. ### Claim 2 (depends on 1) The method of claim 1 wherein said parameter is a velocity associated with a moving piston inside a die casting machine or other machine having a reciprocating ram. ### Claim 3 (depends on 2) The method of claim 2 wherein said step of utilizing comprises the step of controlling a pilot valve in a die casting machine or other machine having a reciprocating ram. ### Claim 4 (depends on 3) The method of claim 3 wherein said pilot valve has a frequency response and wherein said step of comparing further comprises the step of filtering said error signal in a manner to compensate for said frequency response of said pilot valve. ### Claim 5 (depends on 3) The method of claim 3 wherein said step of controlling the pilot valve includes the step of limiting said control with a clamp circuit that overrides the step of controlling and limits said pilot valve to a specified opening, said specified opening being dependant upon said desired parameter value, said parameter being velocity. ### Claim 6 (depends on 3) The method of claim 3 further comprising the step of subtracting from said integrated error signal a signal indicative of a position of said pilot valve in order to generate a first difference signal. ### Claim 7 (depends on 6) The method of claim 6 further comprising the step of differentiating the first difference signal. ### Claim 8 (depends on 7) The method of claim 7 wherein said signal indicative of said pilot valve is twice differentiated. ### Claim 9 Apparatus for controlling a velocity of a reciprocating piston comprising: means for comparing a desired velocity to the actual velocity to be controlled and for generating an error signal in response to said comparison; means for integrating the error signal; and means for employing the integrated error signal to control and adjust said actual velocity. ### Claim 10 (depends on 9) The apparatus of claim 9 further comprising a compensation circuit for providing correction in response to a frequency response exhibited by said reciprocating piston. ### Claim 11 (depends on 9) The apparatus of claim 9 wherein said means for employing includes a pilot valve. ### Claim 12 (depends on 11) The apparatus of claim 11 further comprising a compensation circuit for compensating for phase lag of said pilot valve. ### Claim 13 (depends on 9) The apparatus of claim 9 comprising a clamp circuit which overrides and prevents any correction caused by said integrated error signal beyond a specified value. ### Claim 14 (depends on 11) The apparatus of claim 11 wherein said pilot valve controls the fluid flow to a main valve. ### Claim 15 Apparatus for controlling a die casting machine comprising: a velocity transducer for measuring the velocity of a reciprocating piston in said die casting machine; a comparator for comparing said velocity to a specified velocity profile, and for generating a difference signal in response to said comparison; and means for integrating said difference signal, and for combining said integrated difference signal with a signal indicative of a position of a valve. ### Claim 16 (depends on 15) Apparatus of claim 15 wherein said signal indicative of a position of said valve is filtered through a filter, said filter operating in a manner such that it corrects for phase lag of said valve. ### Claim 17 (depends on 16) Apparatus of claim 16 wherein said valve comprises both a pilot valve and a main valve. ### Claim 18 Apparatus for controlling a machine comprising: means for measuring velocity of a reciprocating piston; means for generating an error signal between said measured velocity and a predetermined velocity; and means for integrating said error signal, and for inputting said integrated error signal as a control signal to a pilot valve. ### Claim 19 (depends on 18) The apparatus of claim 18 wherein said machine is a die casting machine. ### Claim 20 (depends on 18) The apparatus of claim 18 wherein said machine is a molding machine.