| 摘要 |
A fastener feed assembly for a tool such as a power screwdriver having a drive member such as a rotatable bit includes a base fixed to the tool and a nose assembly slidably related to the base. The nose assembly includes a workpiece engaging surface, and when the tool is moved toward the workpiece during a fastener driving operation, the base moves toward the nose assembly. A return spring separates the base and nose assembly when the tool is withdrawn away from the workpiece. A strip of fasteners is fed from a magazine along a feed path through the nose assembly with sequential fasteners located in a drive position. Normally the drive member is spaced from a fastener in the drive position. During movement of the tool toward the workpiece in a driving operation, the drive member moves into engagement with a fastener in the drive position, and then continues to move in order to drive the fastener into the workpiece. A pawl is engageable with the strip in order to advance the strip along the feed path. During the driving operation, a feed mechanism operates in response to movement of the base toward the nose assembly to cock the pawl by moving it away from its home position along the strip away from the drive position. A lost motion arrangement delays cocking of the pawl until after secure engagement of the drive member with a fastener in the drive position. In response to withdrawal of the tool from the workpiece, the feed mechanism returns the pawl to its home position to feed an adjacent fastener of the strip to the drive position. Feed movement of the pawl is delayed until withdrawal of the drive member from the strip feed path. The strip includes a carrier with structure deformed during the drive operation for preventing reverse movement of the strip during cocking of the pawl. |
