GB1367201A - Power operated fastener tool - Google Patents

Abstract

1367201 Power tools ROCKWELL INTERNATIONAL CORP 4 Jan 1972 [6 Jan 1971] 284/72 Heading B3N A power operated tool comprises a motor 22, an output member and means intermediate the motor and the output member operable beginning with the exertion of a rotation resisting force by a fastener being tightened to absorb kinetic energy from a rotating component or components to prevent said kinetic energy from being transmitted to and thereby overtightening a fastener. The absorption means is a spring 102 that connects driven member 94 to output member 114 via members 98 and 108. Thus as the spring is wound, it exerts an increasing force on said component or components to reduce the speed of rotation of and thereby convert the kinetic energy of the component or components. The absorbing capacity of the spring at least equals the kinetic energy of the motor at no-load speed. As shown the tool has a valve 56 by which the torque output of the tool can be controlled. The valve has a shaft extending forwardly to portion 148. A pawl 150 is spring biased against portion 148. Member 98 forms a cam having a follower 168 that is in engagement with the pawl. During operation member 98 rotates relative to member 114 to which the pawl is connected. When the high point of the cam co-operates with the follower the pawl is pivoted downwardly thus releasing shaft portion 148. Due to a pressure differential across valve 56 the valve is caused to shut. The start positions of the follower and cam can be adjusted by means of adjusting mechanism 120. An epicyclic gear connects the motor to member 94. Fig. 5 shows a device incorporating energy absorbing springs 214, which device can be connected to the output member of a power tool. Fig. 7 shows a tool incorporating a clock spring 214a as shown in the embodiment of Fig. 5. Valve 56a is operated through an actuator 232. During operation the actuator is caused to rotate by pin 244, the position of which is controlled by axial movement of operator member 234. Movement of member 234 is caused by relative rotational movement between output member 212a and member 234 that is connected to member 94a. After a fastening operation the spring returns the components to their original positions by reverse rotation of the rotor of the motor.