| 摘要 |
PCT No. PCT/JP90/00932 Sec. 371 Date Mar. 25, 1991 Sec. 102(e) Date Mar. 25, 1991 PCT Filed Jul. 19, 1990 PCT Pub. No. WO91/01869 PCT Pub. Date Feb. 21, 1991.An injection/hold pressure control apparatus which permits the production of high-quality molded articles without the need of using an expensive internal mold pressure sensor. When a plurality of points specifying a target injection/hold pressure curve represented as a function of the time period elapsed after the start of injection are manually input in succession, a processor (109) of a numerical control unit (100) calculates a group of target injection/hold pressure data on the basis of the target pressure curve drawn on a screen of a display unit (113), and stores them in a lookup table in a shared memory (102). Upon start of the injection, a comparator (11), connected to a pressure sensor (4) mounted on an injection screw (1) for detecting an actual injection/hold pressure, is connected to the numerical control unit through a first changeover switch (6). The target pressure data is successively read out from the lookup table and delivered to the comparator, and the drive of an injection servomotor (2) is controlled by a torque control section of a servo circuit (200) responsive to the comparator output indicating the deviation between the actual pressure and the target pressure, so that the injection/hold pressure is always controlled to a proper value in a closed-loop, to thereby improve the quality of molded articles.
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