Electricity: motive power systems – Positional servo systems – Limit or end-stop control
Patent
1999-11-16
2000-12-05
Nappi, Robert E.
Electricity: motive power systems
Positional servo systems
Limit or end-stop control
318560, 264 405, 264 407, G05G 500
Patent
active
06157158&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a mold clamping control apparatus.
BACKGROUND ART
In a conventional motor-driven mold clamping apparatus, mold clamping force is generated by use of a mechanism such that an output shaft of an electric motor such as a servomotor is connected to a toggle mechanism via a ball screw. Rotation generated through drive of the servomotor is transmitted via the output shaft to the ball screw and is then converted to thrust force by the balls crew. The thrust force is then amplified by the toggle mechanism to thereby obtain a mold clamping force. Further, a crosshead is disposed between the ball screw and the toggle mechanism, and the above-described thrust force is transmitted to the toggle mechanism via the crosshead.
In the conventional motor-driven mold clamping apparatus, in order to generate a preset mold clamping force, the crosshead must be moved to a precise position corresponding to the mold clamping force.
However, since the relationship between the position of the crosshead and mold clamping force becomes nonlinear as a result of the structural limitation of the toggle mechanism, calculation for obtaining the position of the crosshead is difficult. Therefore, a desired mold clamping force cannot be generated with precision. In addition, since each individual mold clamping apparatus involves mechanical error of a different degree, even if calculation for obtaining the position of the crosshead is possible, the calculation must be performed for each of the mold clamping apparatuses, resulting in an increase in cost thereof.
Moreover, when play is produced in movable parts such as the ball screw and pins and bushes of the toggle mechanism, or when the friction characteristics of the movable parts change, the mold clamping force changes accordingly, resulting in molded products of deteriorated quality.
An object of the present invention is to solve the above-mentioned problems in the conventional mold clamping apparatus, and to provide a mold clamping control apparatus capable of accurately generating mold clamping force, reducing the cost of the mold clamping apparatus, and improving the quality of molded products.
DISCLOSURE OF THE INVENTION
To achieve the above object, a mold clamping control apparatus according to the present invention comprises: a stationary platen to which a stationary mold is attached; a movable platen to which a movable mold is attached, the movable platen being disposed such that the movable platen can reciprocate while facing the stationary platen; a motor; motion conversion means for converting rotational motion generated through drive of the motor to linear motion and for transmitting the linear motion to a movement member; a transmission mechanism connecting the movement member and the movable platen; detection means for detecting the position of the movement member; memory means for storing, in a relational manner, positions of the movement member during movement in accordance with a predetermined position pattern, and a mold clamping force generated at each of the positions; a mold clamping force setting device for setting a mold clamping force; a mold clamping force pattern generator for generating a mold clamping force pattern on the basis of the set mold clamping force; and position control means for reading from the memory means positions of the movement member corresponding to the mold clamping force pattern and for driving the motor.
In a mold clamping force adjustment mode, positions of the movement member during movement in accordance with a predetermined position pattern and a mold clamping force generated at each of the positions are stored in the memory means in a relational manner. In a mold clamping force generation mode, positions of the movement member corresponding to the mold clamping force pattern are read from the memory means, and the motor is driven on the basis of the read positions of the movement member. Therefore, the movement member can be moved to a precise position corresponding to a mold clam
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patent: 5149471 (1992-09-01), Catanzaro et al.
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patent: 5587633 (1996-12-01), Aoki et al.
patent: 5929583 (1998-07-01), Catanzaro et al.
Leykin Rita
Nappi Robert E.
Sumitomo Heavy Industrie's, Ltd.
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