Magnetic grinding device and magnetic grinding control method

A magnetic grinding device, comprising:

• an electromagnet, a base, a grinding piece fixing table, a programmable power supply, a machine tool, a permanent magnet grinding rod, a controller and a grinding medium, wherein,
• one end of the electromagnet is arranged on the base;
• a magnet platform of the grinding piece fixing table is connected with the other end of the electromagnet;
• and the grinding piece fixing table is used for fixing a to-be-ground workpiece;
• the grinding medium covers a to-be-ground workpiece;
• the magnet platform is a plate pole which is used for gathering magnetic fields formed by the electromagnet after electrification on the upper surface of the plate pole, and distributing the magnetic fields uniformly;
• an output end of the programmable power supply is connected with a coil of the electromagnet;
• and the programmable power supply is used for supplying power for the electromagnet;
• the permanent magnet grinding rod is arranged on the machine tool and located above the to-be-ground workpiece;
• the machine tool is used for controlling the permanent magnet grinding rod to magnetically grind the surface of the to-be-ground workpiece;
• and the controller is connected with the programmable power supply and the machine tool, separately, and
• the controller is used for acquiring grinding points, on the to-be-ground workpiece, of the permanent magnet grinding rod through the machine tool, and controlling an output voltage of the programmable power supply by utilizing a removal amount of a blank workpiece surface shape of the to-be-ground workpiece, the grinding points and a pulse width modulation (PWM) control method, so as to magnetically grind the to-be-ground workpiece,
• specifically comprising:
• establishing a Cartesian coordinate system by taking a projection point, on the surface of the to-be-ground workpiece, of a grinding head of the permanent magnet grinding rod as an origin 0, wherein a Z axis of the Cartesian coordinate system is parallel to the permanent magnet grinding rod, and an XOY plane formed by an X axis and a Y axis of the Cartesian coordinate system is parallel to the surface of the to-be-ground workpiece;
• and comparing the blank workpiece surface shape with a finished workpiece surface shape and determining a removal amount of each coordinate point on the surface of the to-be-ground workpiece by utilizing the Cartesian coordinate system;
• computing a grinding pressure of the coordinate point by utilizing the removal amount of the coordinate point according to a formula
• P
• =
• ϕ
• Kvt
• ,
• wherein p represents the grinding pressure;
• Φ represents the removal amount;
• K represents a constant coefficient;
• v represents a linear velocity of the grinding head;
• and t represents a grinding time
• computing a magnetic field intensity of the coordinate point by utilizing the grinding pressure of the coordinate point according to a formula P=K1H, wherein P represents the grinding pressure;
• K1 represents a constant;
• and H represents the magnetic field intensity;
• computing an electromagnet voltage of each point on the surface of the to-be-ground workpiece according to a formula
• E
• =
• H
• *
• Le
• *
• R
• N
• ,
• wherein E represents the electromagnet voltage;
• H represents the magnetic field intensity;
• Le represents an effective length of a magnetic path of the electromagnet;
• R represents the an impedance of the coil of the electromagnet;
• and N represents the turns of the coil of the electromagnet;
• and starting the machine tool to acquire grinding points, at the blank workpiece surface shape, of the current permanent magnet grinding rod and electromagnet voltages of the grinding points, controlling an output voltage, at the grinding points, of the programmable power supply by utilizing the electromagnet voltages of the grinding points and the pulse width modulation (PWM) control method such that the electromagnet is electrified to form magnetic fields;
• and adsorbing, by the grinding points, magnetic grinding powder to form a magnetic grinding head so as to grind the surface of the to-be-ground workpiece.