Method and apparatus for controlling pressure in electric injection molding machine
AssigneeUbe Machinery Corporation, Ltd.
InventorYoshinori Okazaki
Life of this patent
Estimating the term…
Abstract
A rotational angle of a motor operative to propel forward a screw in an injection molding machine is detected at an encoder. An output from the encoder is employed to obtain an angular velocity ω of the motor. From the obtained angular velocity ω, an estimated melt pressure value δ^ that contains no differential term is derived using a certain observer theory. The estimated melt pressure value δ^ is employed to calculate a torque command value TCMD for the motor, which is fed back to the motor. Thus, precise propelling power control unaffected by noises can be executed without the use of a pressure sensor such as a load cell.
Claims3
An apparatus for controlling pressure in an electric injection molding machine, comprising:
- an observer arithmetic unit operative to derive an estimated melt pressure value δ^, based on an observer, from an angular velocity ω of a motor operative to propel forward a screw in an injection molding machine and a torque command value TCMD given to said motor;
- and
- a torque arithmetic unit operative to calculate said torque command value TCMD for said motor using said estimated melt pressure value δ^ derived at said observer arithmetic unit and feed back said torque command value to said motor, wherein
- said observer arithmetic unit comprises:
- a first and second adders operative to subtract the angular velocity ω from an estimated angular velocity value ω^−1 obtained at immediately preceding processing;
- a first and a second adjusters operative to adjust an output value (ω^−1−ω) from the first and second adders into amplitude corresponding to coefficients d1 and d2, respectively;
- a third adder operative to add the torque command value TCMD−1 and an estimated melt pressure value δ^−1 obtained immediately preceding processing;
- a fourth adder operative to add an output value (TCMD−1+δ^−1) from the third adder and a frictional resistance F(ω) over the electric injection molding machine;
- a third adjuster operative to adjust an output value (TCMD−1+δ^−1+F(ω)) from the fourth adder into amplitude corresponding to a coefficient 1/J;
- a fifth adder operative to add outputs from the first and third adjusters;
- a first integrator operative to integrate an output from the fifth adder to obtain an estimated angular velocity value ω^;
- and
- a second integrator operative to integrate an output from the second adjuster to obtain the estimated melt pressure value δ^.
An apparatus for controlling pressure in an electric injection molding machine, comprising;
- an observer arithmetic unit operative to derive an estimated melt pressure value δ^, based on an observer, from an angular velocity ω of a motor operative to propel forward a screw in an injection molding machine and a torque command value TCMD give to said motor;
- and
- a torque arithmetic unit operative to calculate said torque command value TCMD for said motor using said estimated melt pressure value δ^ derived at said observer arithmetic unit and feed back said torque command value to said motor, wherein
- said observer arithmetic unit comprises:
- a first adjuster operative to adjust the angular velocity ω into amplitude corresponding to coefficient E;
- a second adjuster operative to adjust a torque command value TCMD−1 obtained immediately preceding processing into amplitude corresponding to coefficient B;
- a third adjuster operative to adjust a previously obtained dynamic frictional resistance Fd(ωL) into amplitude corresponding to coefficient C;
- a first adder operative to add output values from the second and third adjusters;
- a fourth adjuster operative to adjust an estimated melt pressure value δ^−1 obtained immediately preceding processing into amplitude corresponding to coefficient D;
- a second adder operative to add outputs from the second and fourth adjusters and subtract an output from the first adjuster from a sum of the outputs from the second and fourth adjusters;
- and
- an integrator operative to integrate an output from the second adder to obtain an estimated melt pressure value δ^.
Dependencies are inferred from the claim text.