Collet assembly for power tools

A collet assembly for a power tool which releasably receives an end portion of a shaft therein with the shaft having a working element at the opposite end thereof, the collet assembly comprising:

• an inner body having an axial bore configured to receive the shaft therein;
• an outer collet sleeve slidably mounted over the inner body;
• a resilient member having portions in the bore at a predetermined axial position therein for being releasably received in a recess of the shaft;
• and
• cooperating portions of the resilient member and collet sleeve which urge the resilient member portions in the shaft recess out therefrom to allow the shaft to be removed from the collet assembly as an incident of relative sliding movement between the collet sleeve and inner body;
• wherein the resilient member comprises a retaining spring having a pair of legs extending into the bore on either side thereof, the cooperating portions include an arcuate control portion of the spring on the body and a wedge cam member on the collet sleeve adapted to engage the control portion for urging the legs out from the shaft recess as the collet sleeve and inner body undergo relative sliding movement, and
• the arcuate control portion of the retaining spring has a narrow throat portion which opens in a rearward direction and toward the wedge cam member with forward sliding of the collet sleeve relative to the body causing the wedge cam member to urge the spring throat portion apart moving the spring legs out from the shaft recess so that axial forces acting on the sleeve in the rearward direction do not cause the shaft to release from the bore.

A collet assembly for a power tool which releasably receives an end portion of a shaft therein with the shaft having a working element at the opposite end thereof, the collet assembly comprising:

• an inner body having an axial bore configured to receive the shaft therein;
• an outer collet sleeve slidably mounted over the inner body;
• a resilient member having portions in the bore at a predetermined axial position therein for being releasably received in a recess of the shaft;
• and
• cooperating portions of the resilient member and collet sleeve which urge the resilient member portions in the shaft recess out therefrom to allow the shaft to be removed from the collet assembly as an incident of relative sliding movement between the collet sleeve and inner body;
• wherein the resilient member comprises a retaining spring having a pair of legs extending into the bore on either side thereof, the cooperating portions include an arcuate control portion of the spring on the top of the body and a wedge cam member on the collet sleeve adapted to engage the control portion for urging the legs out from the shaft recess as the collet sleeve and inner body undergo relative sliding movement, and
• the wedge cam member has opposite ramp surfaces which progressively force opposite sections of the spring control portion apart as the sleeve and body are slid relative to each other from a predetermined operating position and so that the sleeve and body are biased back toward the predetermined operating position by the opposite sections of the spring control portion acting on the ramp surfaces.

In combination, a power tool for driving a working element, the working element mounted to an elongate shaft thereof, the combination comprising:

• a housing of the power tool having a forward end;
• a collet assembly mounted at the forward end of the housing;
• an inner body of the collet assembly having an axial bore configured to receive the shaft therein;
• an outer collet sleeve slidably mounted over the inner body;
• a recess of the shaft having abutment walls extending normal to the length of the shaft;
• a retaining member disposed at a predetermined position in the bore and received in the recess of the shaft with the retaining member confined by one of the abutment walls to prevent the shaft from being pulled out of the bore;
• and
• an actuator for the retaining member operated by sliding of the collet sleeve to cause the retaining member to shift out from the recess and clear the abutment wall for allowing the shaft to removed from the bore, the actuator includes a first portion on the collet sleeve and a second portion mounted to the inner body with the portions having predetermined positions relative to each other with the retaining member in the shaft recess so that sliding of the collet forwardly away from the tool housing causes the portions to engage each other for shifting the retaining member out from the recess.