Electricity: motive power systems – Braking – Automatic and/or with time-delay means
Patent
1986-12-23
1988-11-15
Shoop, Jr., William M.
Electricity: motive power systems
Braking
Automatic and/or with time-delay means
318567, 318302, H02P 500
Patent
active
047852216
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a driving device of an injection molding machine and, more particularly, to a drive control device of an injection molding machine which uses servo motors as a drive source for driving the injection mechanism, the screw rotating mechanism, the die clamping mechanism, and so on of the injection molding machine.
2. Description of the Relative Art
A conventional injection molding machine is driven by hydraulic pressure, and its drive control is performed by controlling the pressure of hydraulic fluid. However, another conventional injection molding machine has also been developed which uses a servo motor as its drive source. In this type of injection molding machine, when a move command is supplied from a control unit, the drive mechanism for a screw, a die clamping unit and the like of the injection molding machine may not for some reason move as requested by the move command. In that case, the drive mechanism may become uncontrollable. Also, overshooting may occur when the servo motor, and hence, the drive mechanism are accelerated, and the operation speed of the drive mechanism may exceed a preset speed.
SUMMARY OF THE INVENTION
It is an object of the present invention to prevent, in an injection molding machine having a drive mechanism for a screw, and a die clamping unit and the like which are driven by a servo motor, a control unit which controls the drive mechanism from being disabled, and to prevent the drive mechanism from operating at a speed exceeding a preset speed.
In order to achieve the above object, according to the present invention, in an injection molding machine which drives a servo motor as a drive source in accordance with an output from a servo circuit including an error register for storing a difference between a move command from a control unit and an actual shift amount of the servo motor, whether or not a value stored by the error register which is read out by a readout means exceeds a predetermined value is discriminated by discriminating means and, when the stored value is discriminated to exceed the predetermined value, supply of the move command from the control unit is temporarily stopped by stop means.
In this manner, according to the present invention, when the servo motor cannot sufficiently respond to a move command from the control unit, and when the servo motor, i.e., the drive mechanism for an injection mechanism, a die clamping mechanism and the like that are driven by the servo motor, does not follow the move command, output of the move command is temporarily stopped before control of the servo motor and the drive mechanism by the control unit is disabled. As a result, the injection molding machine does not become uncontrollable.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram illustrating a main part of a drive control device of an injection molding machine according to an embodiment of the present invention; and
FIG. 2 is a block circuit diagram showing in detail the motor control circuit of an injection servo motor shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a drive control device of an injection molding machine according to an embodiment of the present invention. Referring to FIG. 1, reference numeral 1 denotes a control unit such as a CNC (a computer-incorporating numerical control unit) having a central processing unit (to be referred to as a CPU hereinafter) 2, a ROM 3 for storing a control program which controls the entire injection molding machine, a RAM 4 for temporarily storing data, a nonvolatile memory 5 for storing an NC program and various preset values, an MDi&CRT (an operation panel with a display) 6, and an input/output circuit 7. These components 2 to 7 are connected to each other through a bus 8. The input/output circuit 7 is connected to a servo circuit 13, a torque limit circuit 14, and a decoder 15 that will be described later in each of motor control circuits 10, 11, and 12.
Reference symbols M1, M2, and M3 denote servo
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Fanuc Ltd.
Martin David
Shoop Jr. William M.
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