Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Mold motion or position control
Patent
1988-05-18
1989-07-11
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Mold motion or position control
264 405, 425171, 425589, B29C 4580
Patent
active
048466549
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a mold clamping mechanism of an injection-molding machine, and more particularly, to a detecting apparatus capable of automatically and accurately detecting a die-touch position of a direct mold clamping mechanism which is driven by means of a servomotor.
2. Description of the Related Art
In a known motor-operated direct mold clamping mechanisms a movable platen disposed between a stationary platen and a rear platen is driven for mold clamping by means of a servomotor which is connected to the movable platen through a transmission mechanism. In the mold clamping apparatus of this type, a predetermined mold clamping force is produced by driving a movable die additionally for a predetermined distance in the direction for pressure contact, from a position where the movable die is in contact with a stationary die. Also, a mold opening end position, a die protection start position, etc. are determined on the basis of the die-touch position. In order to produce the predetermined mold clamping force and to perform a specified die opening/closing operation, therefore, the die-touch position must be detected and set accurately. Since the die-touch position varies depending on the thickness of the dies, moreover, it must be detected and set every time the die thickness is changed.
Conventionally, in detecting the die-touch position, an operator visually determines whether or not the die-touch position is reached by the movable platen, and manually adjusts the location of a limit switch for die-touch position detection so that the limit switch is turned on when the movable platen reaches the die-touchy position. In this case, it is difficult to accurately determine the arrival at the die-touch position. For example, a movable die position in which a mold clamping force of a certain size is already produced may be mistaken for the die-touch position. In consequence, the die-touch position cannot be detected and set accurately, so that satisfactory products cannot be manufactured. Moreover, the fine manual adjustment of the location of the limit switch is so troublesome that the efficiency is lowered.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a die-touch position detecting apparatus of a motor-operated direct mold clamping mechanism, capable of detecting a die-touch position automatically and accurately.
In order to achieve the above object, according to the present invention, there is provided a die-touch position detecting apparatus used in a motor-operated direct mold clamping mechanism which has a movable platen movable relatively to a stationary platen, and a servomotor operatively coupled to the movable platen through a transmission mechanism and adapted to be driven by a servo-circuit.
The die-touch position detecting apparatus comprises drive control means for outputting a pulse distribution to the servo-circuit in response to a die-touch position detecting operation command, thereby moving the movable platen toward the stationary platen, stop means for causing the drive control means to stop the pulse distribution to the servo-circuit when the amount of errors accumulated in an error register of the servo-circuit exceeds a predetermined value, and calculating means for calculating a die-touch position in accordance with the amount of pulse distribution to the servo-circuit and the amount of errors when the pulse distribution is stopped.
According to the present invention, as described above, pulses are distributed to the servo-circuit until the amount of errors accumulated in the error register of the servo-circuit exceeds the predetermined value, after the die-touch position detecting operation command is delivered. When the pulse distribution is stopped, the die-touch position is calculated on the basis of the amount of pulse distribution and the error amount. Thus, the die-touch position can be detected automatically, and the location of a limit switch for die-touch position d
REFERENCES:
patent: 4301100 (1981-11-01), Farrell
patent: 4696632 (1987-09-01), Inaba
Fanuc Ltd.
Heitbrink Timothy W.
Woo Jay H.
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