Power tool and method of operating an automated drilling operation

Patent metadata

Field	Value
Publication number	US-9731393-B2
Application number	US-201214356082-A
Country	US
Kind code	B2
Filing date	Oct 25, 2012
Priority date	Nov 4, 2011
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A power tool includes a pneumatic motor with an output shaft, a spindle that is drivingly connected to the output shaft via a drive gear to provide a rotational movement to the spindle and via a feed gear to provide a translational movement to the spindle. A cylinder that governs the gear transmission to the feed gear is arranged to be translated between a retraction gearing position and an advancement gearing position. The retraction gearing includes a retraction torque limiting coupling adapted to be released when an operational torque (T) exceeds a retraction threshold torque (T R ) in order to terminate retraction. A lock mechanism is arranged to selectively block the cylinder in the retraction gearing position through engagement between a tooth of a ratchet on the lock mechanism and a shoulder on the cylinder. The lock mechanism assures that the cylinder is kept in the retraction gearing position during an initial phase of the retraction of the spindle.

First claim

The invention claimed is:

1. A power tool comprising:
a motor; and
a spindle which is drivingly connected to the motor via a drive gear that provides a rotational movement to the spindle and via a feed gear that is threaded onto the spindle such that mutual rotation between the feed gear and the spindle provides an axial movement to the spindle between a fully advanced position and a fully retracted position;
wherein a first gear transmission is arranged to drive the feed gear so as to advance the spindle, and a second gear transmission is arranged to drive the feed gear so as to retract the spindle;
wherein the spindle operates at an operational torque (T) and the second gear transmission includes a retraction torque limiting coupling adapted to be released when the operational torque (T) exceeds a retraction threshold torque (T R );
wherein a lock mechanism is arranged to selectively lock the retraction torque limiting coupling such that it will not be released;
wherein the lock mechanism is arranged to lock the retraction torque limiting coupling when the spindle is in the fully advanced position; and
wherein the retraction torque limiting coupling comprises a smoothly toothed engagement which is held together by a spring, and the spring has a spring action (F A ) that corresponds to the retraction threshold torque (T R ), such that the smoothly toothed engagement is released when the operational torque (T) exceeds a value of the retraction threshold torque (T R ).

2. The power tool according to claim 1 , wherein a cylinder for controlling gear transmission to the feed gear is arranged to be translated between a first gearing position which corresponds to the first gear transmission and a second gearing position which corresponds to the second gear transmission, and wherein the spring acts on the cylinder towards the second gearing position in which the smoothly toothed engagement is achieved.

3. The power tool according to claim 2 , wherein the cylinder defines a closed chamber which is sealed off by sealings with respect to a surrounding housing and an annular housing element, and wherein the chamber is expandable against the action of said spring to push the cylinder towards the first gearing position away from the annular housing element by application of a pneumatic pressure inside said chamber.

4. The power tool according claim 3 , wherein the second gear transmission includes a second torque limiting coupling adapted to be released when the operational torque (T) exceeds a value of an advancement threshold torque (T A ), which is higher than the value of the retraction threshold torque (T R ).

5. The power tool according to claim 4 , wherein a valve is arranged to release the pressure acting in the chamber in response to the operational torque (T) exceeding the value of the advancement threshold torque (T A ) such that the second torque limiting coupling is released and such that the cylinder is translated towards the second gearing position by the action of the spring.

6. The power tool according to claim 2 , wherein the lock mechanism comprises a ratchet which is rotatable around an axis between a blocking position in which a tooth on the ratchet is pointed towards an interaction area of the cylinder in order to interact with a shoulder on the cylinder, and a non-blocking position in which the tooth does not reach a moving area of the cylinder and wherein the interaction between the tooth and the shoulder on the cylinder blocks the cylinder from moving out of the second gearing position.

7. The power tool according to claim 6 , wherein the lock mechanism further comprises a lever which is connected to the ratchet so as to rotate together with the ratchet, and wherein the spindle includes a stop ring which is arranged to act on the lever to position the ratchet in the blocking position as the spindle reaches a forward position.

8. The power tool according to claim 7 , wherein the ratchet and lever are spring loaded towards an open position.

9. The power tool according to claim 7 , wherein an interconnection between the lever and the ratchet includes a freedom of motion that allows the ratchet to rotate with respect to the lever, and wherein a spring is arranged between the lever and the ratchet to act on the ratchet towards the blocking position whereby the ratchet is movable with respect to the lever out of the blocking position against the action of the spring.

10. The power tool according to claim 9 , wherein the ratchet is supported in the blocking position on a support, and wherein an interaction between the support and the ratchet restricts the ratchet from rotating further in a direction in which the cylinder moves past the interaction between the shoulder and the tooth and out of the second gearing position.

11. The power tool according to claim 10 , wherein the ratchet has an outer cam profile that engages the support and that limits a rotational movement of the ratchet in the second gearing position.

Assignees

• Atlas Copco Ind Technique Ab

Inventors

• Eriksson Ulf Mikael
• Georgsson Wilhelm Mattias

Classifications

• B23Q5/027 Primary

  reciprocating members · CPC title

• Y10T74/18576

  including screw and nut · CPC title

• B23Q5/402

  in which screw or nut can both be driven · CPC title

• B23Q5/326 Primary

  screw-operated · CPC title

• F16H25/20

  Screw mechanisms (with automatic reversal F16H25/12) · CPC title