US 4,592,681 AGranted

Retraction apparatus for automatic feed drills or the like

AssigneeDresser Industries, Inc.

InventorsRobert A. Pennison, Richard E. Eckman

Life of this patent

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Abstract

The automatic feed drill includes a spindle mounted therein for rotating in reciprocating movement. The spindle is rotated by spindle rotation gear that is engaged with the main drive gear which is ultimately driven by an air motor or the like. The feed and retraction movement (reciprocation) is caused by a spindle feed gear that is threaded onto the spindle. The spindle feed gear is engaged with a feed gear which, during feed movement, is driven by the main drive gear, and during retraction movement, is shifted into a position wherein the feed gear is prevented from rotating. The spindle also carries a collar or other abutment that engages a shift lever at the end of the feed movement. The shift lever is moved by the collar, and, due to its interconnection with the feed gear, moves the feed gear out of engagement with the main drive gear and into the position wherein it is prevented from rotating. The apparatus also includes a yieldable stop device that holds the feed gear stopped during retraction movement. In the event that excessive torque is encountered, such as by a lower collar on the spindle engaging the housing, the yieldable stop member rotates at the same speed as the spindle feed gear and thus, prevents further retraction of the spindle and avoids damage to the drill.

Claims11

Dependent claims

Improved retraction apparatus for automatic feed drills including a housing, a rotatable tool spindle located for reciprocating movement in the housing, and driving means located in said housing operably connected with feeding and retraction movements, said driving means including a spindle rotation gear engaged with said spindle to rotate said spindle and slidable thereon, a spindle feed gear engaged with said spindle to cause the reciprocating movement of said spindle, a main drive gear driven by said drive means and engaged with said spindle rotation gear to cause rotation thereof, and a feed gear engaging said spindle feed gear movable into and out of engagement with said main drive gear, said feed gear, when driven by said main drive gear, causing rotation of said spindle feed gear to move said spindle in feeding movement, and, when not driven by said main drive gear, moving said spindle in retraction movement, the improvement comprising:

shift means connected to said feed gear and engageable with said spindle for moving said feed gear out of driving engagement with said main drive gear;
and,
yieldable stop means in said housing engaging and preventing rotation of said feed gear when said feed gear is moved out of driving engagement with said main drive gear, said stop means being yieldable when a predetermined torque is placed on said feed gear by said spindle feed gear during retraction movement of said spindle whereby said spindle feed gear rotates at the same speed as said spindle thereby stopping the retraction movement of said spindle.

Improved retraction apparatus for automatic feed drills including a housing, a rotatable tool spindle located for reciprocating movement in the housing, and driving means located in said housing operably connected with said spindle for rotating and reciprocating said spindle in feeding and retraction movements, said driving means including a spindle rotation gear engaged with said spindle to rotate said spindle and slidable thereon, a spindle feed gear engaged with said spindle to cause the reciprocating movement of said spindle, a main drive gear driven by said drive means and engaged with said spindle rotation gear to cause rotation thereof, and a feed gear engaging said spindle feed gear movable into and out of engagement with said main drive gear, said feed gear, when driven by said main drive gear, causing rotation of said spindle feed gear to move said spindle in feeding movement, and, when not driven by said main drive gear, moving said spindle in retraction movement, the improvement comprising:

shift means including a shift lever member pivotally mounted on said housing, said lever member in a first position, engaging said feed gear to hold said feed gear in driving engagement with said main drive gear and, in a second position, holding said feed gear out of driving engagement with said main drive gear;
and
stop means for limiting the retraction movement of said spindle.

Dependencies are inferred from the claim text.