Press for form pressing meat products, and method of use

Abstract

In an embodiment, a form press includes three die assemblies which form press a meat product along the height, width and length thereof. Each die assembly includes a single proportional directional valve which operates a hydraulic cylinder under control of a controller. The three die assemblies are first operated under position control, and are thereafter operated under force/position control. A controller controls each proportional directional valve based on input from a bottom-side pressure sensor, a rod-side pressure sensor, and a die assembly position sensor, in a closed-loop manner for each corresponding hydraulic cylinder.

1 . A form press configured to form press a meat product, comprising:
 a frame having a press plate, which defines a longitudinal axis;   a first, a second, and a third die assembly mounted on the frame, corresponding to a height axis, a width axis, and a length axis, respectively;   each die assembly including a die assembly position sensor and hydraulic cylinder, the hydraulic cylinder having a piston and piston rod, wherein each hydraulic cylinder has a bottom-side chamber and a rod-side chamber;   a closed-loop hydraulic control system configured to control each corresponding hydraulic cylinder, the closed-loop hydraulic control system including:
 a controller; 
 a proportional directional valve operatively coupled to each corresponding hydraulic cylinder; 
 each corresponding hydraulic cylinder having bottom-side pressure sensor and a rod-side pressure sensor; and 
   the controller configured to operatively control the proportional directional valve based on input from the bottom-side pressure sensor, the rod-side pressure sensor, and the die assembly position sensor, in a closed-loop manner for each corresponding hydraulic cylinder.   
     
     
         2 . The form press according to  claim 1 , wherein the controller varies the operating position of each corresponding proportional directional valve continuously between an extend operating position, a neutral operating position, and a retract operating position, until each die assembly provides a predetermined pressure level against a food product exerted by each corresponding die assembly. 
     
     
         3 . The form press according to  claim 2 , wherein the controller is configured to control the corresponding hydraulic cylinders in a closed-loop manner, based on information provided by the bottom-side pressure sensor, the rod-side pressure sensor, and the die assembly position sensor. 
     
     
         4 . The form press according to  claim 1 , wherein the first die assembly includes a first die configured to move along the height axis, the second die assembly includes a second die configured to move along the width axis, and the third die assembly includes a third die configured to move along the length axis. 
     
     
         5 . The form press according to  claim 4 , wherein the press plate and the plurality of dies define a press chamber therebetween, the press chamber configured to compress a food product within. 
     
     
         6 . The form press of  claim 1 , wherein and die assembly position sensors corresponding to the height axis and the length axis, are linear position sensors. 
     
     
         7 . The form press of  claim 1 , wherein the die assembly position sensor corresponding to the width axis is an encoder. 
     
     
         8 . The form press of  claim 2 , wherein the controller initially operates in a position control mode, and sets each corresponding proportional directional valve to the extend operating position, and moves each cylinder piston rod to a predetermined axial setpoint position based on position information from each corresponding die assembly position sensor. 
     
     
         9 . The form press of  claim 8 , wherein the controller initially operates in the position control mode if information from the corresponding bottom-side pressure sensors and rod-side pressure sensor indicates that measured pressure is below a predetermined low-pressure value. 
     
     
         10 . The form press of  claim 8 , wherein the controller is configured to operate in a force control mode after completing operation in the position control mode. 
     
     
         11 . The form press of  claim 10 , wherein the controller operates in the force control mode and sets each corresponding proportional directional valve to the extend operating position, and moves each cylinder piston rod until the corresponding pressure sensors indicate that a desired setpoint pressure level is reached. 
     
     
         12 . The form press of  claim 11 , wherein the controller operates in the force control mode if information from the corresponding die assembly position sensor indicates that the corresponding piston rod is at an axial position less than a predetermined maximum axial position. 
     
     
         13 . The form press of  claim 11 , wherein the controller, in the force control mode, continuously controls the corresponding proportional directional valve between the extend operating position, the neutral operating position, and the retract operating position, so as to continuously increase the pressure in the corresponding cylinder until the desired setpoint pressure level is reached. 
     
     
         14 . The form press of  claim 11 , wherein once the desired setpoint pressure level is reached for the corresponding cylinder, the controller sets the corresponding proportional directional valve to the neutral operating position. 
     
     
         15 . The form press of  claim 14 , wherein the controller sets the corresponding proportional directional valve to the retract position after the neutral operating position has been maintained for a predetermined period of time. 
     
     
         16 . The form press of  claim 14 , wherein the controller sets the corresponding proportional directional valve to the retract position after the neutral operating position has been set. 
     
     
         17 . The form press of  claim 10 , wherein after the neutral operating position has been set, the controller sets the corresponding proportional directional valve to the retract operating position to retract the corresponding piston rods to an open-chamber position. 
     
     
         18 . The form press of  claim 10 , wherein movement of the corresponding piston rod in the position control mode is substantially faster than movement of the corresponding piston rod in the force control mode.