Magnetic bit holder and hand tool incorporating same

Abstract

A hand tool has an elongated shank with a handle at one end and a bit holder at the other end, the bit holder including a cylindrical body having a distal end surface and an axis, the body having an axial bore formed in the end surface of non-circular transverse cross section and terminating at an inner end surface. A neodymium permanent magnet is freely received in the bore and retained against the inner end surface by a thin circular retainer, formed of metal or plastic, which is interference-fitted in the bore. Both flat, disk-like and concave, bowl-shaped retainers are disclosed. A shock-absorbing cushion may be disposed between the magnet and the inner end surface of the bore. A bit formed of magnetizable material is mateably received in a socket portion of the bore and retained in place by the magnet. The portion of the bore receiving the magnet may have a different cross section from the socket portion. The magnet may be disposed in an encapsulation which interference fits in the bore.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to hand tools and, in particular, to tools incorporating a bit holder for receiving interchangeable bits, such as screwdriver bits or the like. The invention has particular application to tools in which bits are magnetically retained in a bit holder.2. Description of the Prior ArtTypical current magnetic bit holders include a cylindrical body having a socket formed axially in one end thereof for mateably receiving an associated bit. The inner end surface of the socket has further formed therein an axial hole of reduced cross section receiving an associated magnet to retain the bit in place in the socket. A suitable permanent magnet is press-fitted or crimped into the magnet hole for magnetically retaining the associated bit in place. The magnet is commonly formed of a material such as Alnico and has considerable mass, typically being approximately one inch long and approximately one-quarter inch in dia...

AI Technical Summary

Benefits of technology

It is a general object of the invention to provide an improved magnetic bit holder which avoids the disadvantages of prior bit holders while affording additional structural and operating advantages.

A further feature of the invention is the provision of a bit holder of the type set forth, which can effectively use a neodymium magnet.

Yet another feature of the invention is the provision of a bit holder of the type set forth which can effectively retain a neodymium magnet in place, minimizing the risk of fracture thereof and assuring adequate retention even in the event of fracture.

Problems solved by technology

However, neodymium magnets are extremely brittle and cannot be press fit or crimped, nor can they be impacted in use by a bit, since such handling may cause the magnet to fracture and separate from the tool.

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