Impact drilling tool

US4073348A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Heribert Schramm · Stuttgart, DE
• Steffen Wuensch · Holzgerlingen, DE

Key dates

• Filing date: Jul 13, 1976
• Grant date: Feb 14, 1978
• Expiry date: Jul 13, 1996

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B25D2211/065
• WIPO field: Machine tools
• WIPO sector: Mechanical engineering

Abstract

An impact drilling power tool has a housing, a spindle element mounted in the housing for rotation about an axis and for displacement in axial direction, and an impact element mounted in the housing for displacement axially toward and away from the spindle element. The impact element has an axially arranged extension coaxially received within a blind bore of the spindle element. The impact element has a plurality of cam surfaces provided on helical radial projections of the impact element, and rolling bodies of a cam follower element contact the respective cam surfaces and displace the impact element against the force of coaxial helical springs until encountering interruptions of the projections, upon which the springs rapidly displace the impact element toward the spindle element and an end face of the axial extension impacts the bottom of the blind bore. An output shaft of a driving motor drives a countershaft and via the same and meshing gears also the impact element and the spindle element. The power tool may operate either in a normal drilling mode or in an impact drilling mode.