REVERSIBLE DRIVE TOOL

• US 3,773,117 A
• Filed: 03/31/1971
• Issued: 11/20/1973
• Est. Priority Date: 03/31/1971
• Status: Expired due to Term

• Current Assignee: Paul E. Dussel
• Original Assignee: Paul E. Dussel
• Inventors: Dussel, Paul E.
• Primary Examiner(s): Cohen, Irwin C.
• Application Number:
  US05/129,680
• Time in Patent Office: 965 Days
• Field of Search: 92/61,2,52 91/61,167,170,401 173/108,153,155,159,4
• US Class Current: 173/4
• CPC Class Codes: B23Q 11/04 Arrangements preventing overload of tools, e.g. restricting load
• CPC Class Codes: B23Q 5/00 Driving or feeding mechanisms; Control arrangements therefor automatic control B23Q15/00; copying B23Q33/00, B23Q35/00; specially adapted for boring or drilling machines B23B39/10, B23B47/00; numerical programme-control of machine tools G05B19/18

Abstract

A pneumatically driven tool for rotating a tool bit while advancing the bit into a work piece. The direction of rotation of the tool bit is reversed and the bit retracted from the work piece when a predetermined torque level is reached. The tool consists of a housing, an air motor within the housing for rotating the tool bit, a piston assembly connected to the air motor and slidable in the housing for advancing the tool bit into and out of the work piece, a control valve assembly for regulating air flow to the air motor and the piston, and a longitudinally divided tube supplying the air connections between the air control valve and the air motor.

Claims

1. A reversible drive tool, comprising:

a generally cylindrical housing;

a reversible rotary air motor slidably received in the housing for rotating a tool bit, the air motor having separate forward and reverse inlet ports;

a tube attached to the air motor and extending substantially parallel to the axis of the housing, the tube having at least two separate passages communicating, respectively, with the forward and reverse inlet ports of the air motor;

a substantially cylindrical sleeve positioned within the housing and spaced from the inner wall of the housing to define an annular passage between the housing and the sleeve, an inner surface of said sleeve defining the walls of a chamber, said passage forming a part of the air flow path leading to a portion of said chamber within the sleeve;

a piston connected rigidly to the tube and having a substantially air-tight sliding relation to the walls of the chamber and dividing said chamber into two chamber portions;

means for directing air to either the portion of the chamber remote from the air motor and a first passage of the tube communicating with the forward inlet port of the air motor or the portion of the chamber nearer to the air motor and the other passage of the tube;

means in said tube to provide communication between the first passage of the tube and the portion of the chamber remote from the air motor; and

means to prevent air flow to said first passage of said tube when the piston is at its extreme remote position in the chamber.

2. The reversible drive tool according to claim 1 wherein said means for directing air to the chamber and the passages of the tube comprises a valve assembly including a casing having a through bore in which the divided tube is slidably received, the bore having an enlarged annular portion, the portion of the tube extending into the enlarged portion having an opening communicating with the second passage of the tube, the enlarged portion forming a part of the air passage to the second passage of the tube.

3. The reversible drive tool according to claim 2 wherein the valve assembly includes a spool valve having a plurality of chambers and a pair of end chambers each connected to an air inlet and to a bleeder valve, and also has ports for connecting to atmosphere for secondary exhaust of the air motor.

4. The reversible drive tool according to claim 3 further including sensing means for detecting an increase in air pressure in the first passage of the divided tube, the sensing means producing an air pressure reduction in one of the end chambers of the spool valve upon a pressure increase in the first passage of the divided tube to cause the valve to shift reversing the motor and retracting the piston.

5. The reversible drive tool according to claim 1 wherein said means in said tube to provide communication between the first passage of the tube and the portion of the chamber remote from the air motor, comprises at least a first opening in the tube wall communicating with the first passage of the tube and positioned on the tube such that it communicates with the portion of the chamber remote from the air motor except when the piston is at its extreme position in the chamber and it is blocked thereby.

6. A pneumatically driven tool, comprising;

a generally cylindrical housing;

a valve assembly at the first end of the housing, the valve assembly including an inlet port for connection to a source of air pressure, an exhaust port, and first and second outlet ports, a valve for connecting either the first port to the inlet port and the second port to the exhaust port or vice versa, a through bore extending coaxially with the housing and having an enlarged annular portion intermediate the ends of the bore, the second outlet port communicating with the enlarged portion of the bore;

a tube slidably received in the bore of the valve assembly and extending toward the second end of the housing, the tube being divided longitudinally into first and second separate passages, openings being provided in the tube wall communicating with the first and second passages, respectively, the openings being longitudinally separated from one another whereby the first opening is located toward the second end of the housing and remote from the enlarged portion of the bore and the second opening is located within the enlarged portion of the bore and the second opening is located within the enlarged portion of the bore;

a piston connected to the tube at a point on the portion thereof extending toward the second end of the housing, the piston being slidably received in a chamber adjacent the valve assembly and the first outlet port of the valve assembly communicating with the portion of the chamber between the piston and the valve assembly; and

a rotary air motor connected to the end of the tube toward the second end of the housing, the motor being reversible and having separate forward and reverse air inlets, the first passage of the tube communicating with the forward air inlet of the motor and the second passage of the tube communicating with the reverse air inlet of the motor.

7. The pneumatically driven tool according to claim 6 wherein the opening communicating with the first passage of the tube is located so that said opening is positioned in the through bore of the valve assembly when the tube is in its fully retracted position and communicates with the piston chamber when the tube is advanced from its fully retracted position, sealing means being provided to prevent air flow from the piston chamber to the through bore.

8. The pneumatically driven tool according to claim 6 further including means to manually control the valve.

9. The pneumatically driven tool according to claim 6 further including a pressure actuated means connected to the first passage of the tube and operative, upon a pressure increase in the first passage above a predetermined value, to effect reversal of the valve whereby the air motor is reversed and retracted.

10. In a pneumatically driven tool having a rotary air motor, a housing, a piston slidably received in the housing for advancing and retracting the air motor out of and into the housing, and a control valve assembly controlling the operation of the motor and the piston, the improvement wherein the air motor is a reversible air motor having separate air inlet ports for forward and reverse operation;

and a tube is connected to the motor and to the piston and extending in sliding relation into the valve assembly, the tube having two separate longitudinal passages communicating, respectively, with the forward and reverse air inlet ports of the motor and with separate outlet ports of the valve assembly.

11. The improvement according to claim 10 wherein the tube is comprised of a tubing length divided longitudinally by a wall.