| 摘要 |
The present invention discloses a method and apparatus for controlling the load on the blade of a steel-cutting saw A programmable logic controller senses the spindle motor load current and compares it with the desired optimum operating current. Variations in hardness of the steel member cause the spindle motor current to fluctuate. The advancement of the blade by an electric servomotor is controlled by the PLC. The PLC reduces the rate of advancement of the blade in response to increasing spindle current, thereby reducing the load on the blade. The blade speed is maintained constant by a variable frequency motor powering the spindle motor. The operator selects the blade speed from 3 to 85 RPM, which is maintained by the variable frequency drive. The feed rate is the variable that is controlled by the PLC, by which the load current of the spindle motor is maintained relatively constant.
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