| 摘要 |
A fully automated handheld screw driving device (D) comprises an automatic feeding mechanism of screws (15) to the screwdriver bit (7) from an integral storage magazine (26), an automatic speed control mechanism for controlling the rotary speed of the screwdriver, an automatic force control mechanism for controlling the seating force of the screwdriver bit on the screw, an adjustable depth control mechanism for controlling the final screw depth in the work surface, and an adjustable seating torque control mechanism for controlling the final screw head seating torque. The screws (15) are spirally wound on a replaceable bobbin (48) removably mounted in the magazine (26). The device (D) can accommodate a full range of practical screw sizes and can be fitted with exchangeable bits (7) for use with screws having standard recessed star or square heads and various bolt heads. A central microprocessor (28) is used to control all operating functions of the screw driving device (D). Control of seating torque is achieved by directly measuring armature voltage, field current and armature current. The machine dynamic behavior is used to determine a proportionality coefficient between torque and the product of field and armature currents. The proportionality coefficient is recalculated for every operating cycle of the device to continuously compensate for the effect of temperature on the magnetic characteristics of the motor. Rotary speed and torque of the two motors used in the device are tightly controlled using feedback techniques. |
