Hilti Aktiengesellschaft

Hansjorg Nipp

Karl Blaas

Heinz Kousek

Otto Noser

Otmar Ganahl

Hans Leemann

Daniel Baetschmann

An apparatus for locating magnetizable material (5, 6) within a structure (4) includes a scanning head (1) with a permanent magnet (28) for producing a magnetic field in the structure (4). Two field plates (30, 31), adjacent one another on only one pole face of the permanent magnet (28), are interconnected by a differential circuit and measure the magnetic field of the magnet disturbed by the magnetizable material (5, 6). The differential values measured by the pair of field plates form a differential measured signal for establishing, after differentiation, the location of the magnetizable material (5, 6) within the structure (4). The location of the magnetizable material (5, 6) within the structure can be shown on a monitor (7) of an evaluation unit (3).

Apparatus for determining location of an element of magnetizable

In a process using a hand-held drilling device for forming openings in a construction material containing steel reinforcing members, during the drilling step the electrical resistance between the drill bit and the reinforcing members is continuously measured. If the drill bit contacts the reinforcing member the measuring circuit is shorted out and the electrical resistance drops. The drop in resistance can be used as a signal for cutting power to the drilling device or for declutching or braking the device.

Process of forming openings

A hand-held tool, such as a hammer drill or chipping hammer, includes a housing with a driving unit for supplying the driving force for the tool with the driving unit generating vibrations. A handle is mounted on the housing and is displaceable in the direction of the main vibration axis. A stop for the forward movement of the handle is provided by an electromagnet. The electromagnet is formed by a yoke, an armature and a magnetic coil and exerts a controlled constant force on the handle and the housing independently of the position of the handle relative to the housing. The electromagnet can be controlled depending on the position of use of the hand-held tool.

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Mauren, Liechtenstein

Hansjorg Nipp