Linear feed control for a rotary tool

Claim 2

A linear feed control for a rotary tool comprising the combination of a tool mounted for rotary movement and for linear movement; a rotary drive motor connected to transmit said rotary movement to said tool; a linear drive motor connected to transmit said linear movement to said tool; a torque sensor connected to said rotary drive motor to sense torque transmitted to said tool and having means to originate a torque feedback signal proportional to said torque; a linear force sensor connected to said linear drive motor to sense linear force transmitted to said tool and having means to originate a linear force feedback signal proportional to said force; a comparator connected to receive said torque feedback signal and said linear force feedback signal and having means to originate a command signal when said torque feedback signal exceeds a predetermined limit relative to said linear force feedback signal; and a linear drive control connected to receive said command signal and to modify said movement transmitted to said tool in response to said command signal.

Claim 3

A linear feed control for a rotary tool as set forth in claim 1 wherein said rotary drive motor is a DC electric motor having an armature energized by a DC source; and said torque sensor includes a resistance in series with said armature circuit of said rotary drive motor to develop a voltage drop proportional to the torque transmitted to said tool and means connected across said resistance to detect said voltage drop and to originate a torque feedback signal proportional to said voltage drop.

Claim 4

A linear feed control for a rotary tool as set forth in claim 1 wherein said linear drive motor is a hydraulic motor having fluid ports to receive fluid under pressure to drive said motor; said linear force sensor includes a pressure sensor connected to at least one of said fluid ports to detect fluid pressure at said port with output terminals to emit electrical signals proportional to said fluid pressure and means connected to said output terminals to receive said electrical signals and to originate a linear force feedback signal proportional to the linear force transmitted to said tool; and said linear drive control includes an electrically controlled hydraulic valve and means connected to receive said command signal and to originate a control signal responsive to said command signal and to transmit said control signal to said electrically controlled hydraulic valve to control said electrically controlled hydraulic valve.

Claim 5

A linear feed control for a rotAry tool comprising the combination of a rotary tool mounted for rotary movement and for linear movement; a rotary drive motor connected to said rotary tool to rotate said rotary tool; a rotary motor speed control means connected to operate said rotary drive motor at a preset speed; a linear drive motor connected to said rotary tool to impart said linear movement to said rotary tool; a linear motor speed control means connected to said linear motor to control the speed of said linear motor responsive to a command signal; a linear motor speed feedback signal source and a linear speed reference signal source connected to originate a linear speed error signal, and connected to said linear motor speed control to maintain said linear movement at a preset speed; a torque sensor connected to said rotary drive motor to sense torque demand on said rotary drive motor and to generate a torque feedback signal proportional to said torque demand; a force sensor connected to said linear force exerted by said linear drive motor and to generate a linear force feedback signal proportional to said force; and a comparator connected to said torque sensor and said force sensor to receive said torque feedback signal and said linear force feedback signal and to transmit a command signal to said linear motor speed control to modify said error signal to vary said linear motor speed from said present speed when the value of said torque feedback signal relative to said linear force feedback signal transgresses a predetermined limit.

Claim 6

A linear feed control for a rotAry tool comprising the combination of a rotary tool mounted for rotary movement and for linear movement; a rotary drive motor connected to said rotary tool to rotate said rotary tool; a rotary motor speed control means connected to operate said rotary drive motor at a preset speed; a linear drive motor connected to said rotary tool to impart said linear movement to said rotary tool; a linear motor speed control means connected to said linear motor to control the speed of said linear motor responsive to a command signal; a linear motor speed feedback signal source and a linear speed reference signal source connected to originate a linear speed error signal, and connected to said linear motor speed control to maintain said linear movement at a preset speed; a torque sensor connected to said rotary drive motor to sense torque demand on said rotary drive motor and to generate a torque feedback signal proportional to said torque demand; a force sensor connected to said linear force exerted by said linear drive motor and to generate a linear force feedback signal proportional to said force; and a comparator connected to said torque sensor and said force sensor to receive said torque feedback signal and said linear force feedback signal and to transmit a command signal to said linear motor speed control to modify said error signal to vary said linear motor speed from said present speed when the value of said torque feedback signal relative to said linear force feedback signal transgresses a predetermined limit.

Claim 7

A linear feed control for a rotary tool as set forth in claim 4, wherein a clamping circuit is connected to receive said linear motor speed feedback signal and to receive said force feedback signal and connected to said linear motor speed control to limit said command signal preventing said command signal from reversing the direction of said linear motor.

Claim 8

A linear feed control for a rotary tool as set forth in claim 4, wherein said rotary tool is a blast hole drill having a stem rotatably and slidably mounted through a bushing in a platform; said rotary drive motor is connected to a transmission and said transmission transmits rotary drive torque from said rotary drive motor to said stem; and said linear drive motor is connected to a second transmission and said second transmission transmits linear drive force from said linear drive motor to said stem.

Claim 9

A linear feed control for a rotary tool as set forth in claim 4 wherein said linear motor speed control means includes a common connection of said reference signal source and said linear speed feedback signal source algebraically algebraically sum said reference signal and said speed feedback signal to produce said error signal, and means connected to receive said error signal and to transmit a control proportional to said error signal to said linear motor speed control means to control said linear drive speed.

Claim 10

A linear feed control for a rotary tool as set forth in claim 7 wherein said linear drive motor is a hydraulic motor having at least one of its ports connected to a hydraulic pump to be powered by fluid pumped by said hydraulic pump; and said control means is an electrically controlled directional and flow control hydraulic valve connected in series between said hydraulic pump and said linear drive motor.

Claim 11

A linear feed control for a rotary tool as set forth in claim 8 wherein said rotary drive motor is a DC motor having an armature energized by a controllable DC power source; and said rotary speed control means is connected to a speed control potentiometer adjustable to indicate a desired motor speed and across said armature to detect armature voltage to control the output of said DC source to said armature.

Claim 12

A linear feed control for a rotary tool as set forth in claim 9 wherein said means connected to receive said error signal is a servo valve amplifier having one inpuT terminal connected to said common connected reference signal source and linear speed feedback signal source, said input terminal also being connected to said comparator to receive said command signal, and having an output terminal connected to said electrically controlled hydraulic valve; said torque sensor includes a resistance connected in series with said armature of said DC motor and a torque feedback amplifier having input terminals connected across said resistance and an output terminal emitting said torque feedback signal; said force sensor includes a fluid pressure sensor connected at least to said one port of said hydraulic motor to sense fluid pressure and to originate a fluid pressure signal proportional to said fluid pressure, and a force feedback amplifier having an input terminal connected to receive said signal proportional to fluid pressure and an output terminal transmitting a linear force feedback signal proportional to said fluid pressure signal; said torque feedback amplifier and said linear force feedback amplifier being adjusted so that said torque feedback signal is normally less than a preset maximum relative to said linear force feedback signal; and said comparator is a comparator amplifier having input terminals connected to receive said torque feedback signal and said linear force feedback signal and output terminal connected in series with a blocking diode to transmit a command signal only when said torque feedback signal exceeds said maximum.

Claim 13

A linear feed control for a rotary tool as set forth in claim 10 wherein said tool is a blast hole drill having a drill stem rotatably and axially slidably mounted in a bushing through a platform; said linear drive motor is a rotary hydraulic motor; and said rotary drive DC motor is driving by a Ward-Leonard drive.