| 摘要 |
PURPOSE:To control the strength of a generated magnetic field supplying a set current to a magnetic field generating coil by controlling the current to the magnetic field generating coil controlling a duty ratio by using a switching element, e.g., such as a transistor or a gate turn-off thyristor. CONSTITUTION:A magnetic field generating coil 12 and a fixed mold 14 are installed on a fixed board 10, a magnetic field generating coil 18 and a movable mold 20 are installed on a movable board 16 and a required current can be supplied to the magnetic field generating coils 12 and 18 from a magnetic field control equipment 28. Four switching elements 34, 36, 38 and 40 consisting of, e.g., such as a transistor or a gate turn-off thyristor make a bridge circuit and the terminal 52 between the first element 34 and the second element 36 and the terminal 54 between the third element 38 and the fourth element 40 are each connected to the plus or the minus of a D.C. power source 38 respectively. A current detector 50 and the magnetic field generating coils 12 and 18 are connected in series between the terminal 56 between the second element 36 and the third element 38 and the terminal 58 between the fourth element 40 and the first element 34. |
