US 4,720,897 A · Automatic fastening machine with brushless electric motor for drill spindle drive

Abstract

In an automatic fastening machine comprising a frame, drilling assembly carried by the frame for drilling a fastener receiving hole in a workpiece and an arrangement carried by the frame for installing a fastener in the hole drilled in the workpiece, the drilling assembly comprising a drill spindle having an axis of rotation and a drilling tool at one end thereof and rotatably mounted in a ram movable on the machine frame toward and away from the workpiece, the improvement of a brushless synchronous a.c. servomotor including an output shaft having an axis of rotation and an arrangement for connecting the motor directly to the drill spindle with the axis of rotation of the motor shaft coincident with the axis of rotation of the drill spindle. There is also provided a fan on the frame and positioned to direct cooling air onto the motor. There is further provided a heat sensor embedded in the motor winding and a readout operatively connected to the heat sensor for providing an indication of motor winding temperature.

Claims14

Dependent claims

In automatic fastening machine comprising a frame, drilling means carried by said frame for drilling a fastener receiving hole in a workpiece and means carried by said frame for installing a fastener in the hole drilled in said workpiece, said drilling means comprising a drill spindle having an axis of rotation and a drilling tool at one end thereof and rotatably mounted in a ram movable on said machine frame toward and away from the workpiece, the improvement comprising;

(a) a brushless synchronous a.c. servomotor including an output shaft having an axis of rotation, said motor having a torque range from about 40 lb.-in. to at least about 60 lb.-in., a speed range of from about 200 r.p.m. to at least about 5000 r.p.m., a low profile and small size and maximum weight of about 10 pounds and a cycling capability of about 30 times per minute;
and
(b) means for connecting said motor directly to said drill spindle with the axis of rotation of said motor shaft coincident with the axis of rotation of said drill spindle.

In an automatic fastening machine comprising a frame, drilling means carried by said frame for drilling a fastener receiving hole in a workpiece and means carried by said frame for installing a fastener in the hole drilled in said workpiece, said drilling means comprising a drill spindle having an axis of rotation and a drilling tool at one end thereof and rotatably mounted in a ram movable on said machine frame toward and away from the workpiece, the improvement comprising:

(a) a brushless synchronous a.c. servomotor including an output shaft having an axis of rotation, said motor having a continuous stall torque of about 41 lb.-in., constant no load speed of about 5000 r.p.m., torque constant of about 4.9 lb.-in/A, voltage constant of about 58.3 volts/krpm, mechanical time constant of about 1.38 ms., electrical time constant of about 2.62 ms., resistance of about 1.50 ohmns at 25.degree. C., continuous stall current of about 9.9 amperes, peak stall current of about 42.7 amperes, inertia without brake of about 2.5.times.10.sup.-3 lb.-in.-sec.sup.2 and weight of about 10 pounds;
and
(b) means for connecting said motor directly to said drill spindle with the axis of rotation of said motor shaft coincident with the axis of rotation of said drill spindle.

Dependencies are inferred from the claim text.

Automatic fastening machine with brushless electric motor for drill spindle drive

Life of this patent

Automatic fastening machine with brushless electric motor for drill spindle drive

Life of this patent

Abstract

Claims14