ADAPTER FOR SOCKET WRENCHES The invention relates to an adapter for socket wrenches, which comprises a shaft having an attachment for inter¬ changeable sockets, each of which having an axially ex- tending through bore, which at one end has a grip designed for receiving the shaft attachment and at the other end a grip for a bolt head or a nut, the adapter having a similar grip for the shaft attachment and an adapter attachment similar to the shaft attachment. This kind of socket tools are very frequent as well in workshops and factories as in homes, and are used for the tightening and the release of screw joints. Generally the sockets are sold in sets with standard dimensions of the various bolt or nut grips, while the grip for the shaft attachment is the same for all sockets in a set of sockets. In general the shaft attachment is a 1/2" square attachment and mostly a reversible ratchet mechanism is provided in the shaft, permitting the attachment to be rotated in the shaft in one direction and preventing it from being rotated in the opposite direction, i. e. the direction of actua¬ tion. Some ratchet shafts are also provided with devices for measuring the torque, so called dynamometric wrenches. A problem in this connenction, which is very well known to most people in the art, is the fact that the bolt or nut being operated by the tool is loosely received therein and of that reason sometimes will drop out from the socket, in particular, when the member has been released from the screw joint, of which it contstitutes a part. This causes problems, since the bolt or nut can not be left remaining on the place, where it has been dropped, as in many cases there will be a risk that it later may cause damages on a member in the drop area. Many times this results in an annoying, time and cost consuming operation to get hold of

the dropped bolt or nut, particularly if the area is difficult to reach.

Attempts have been made to eliminate this problem, at least in part, by various solutions. For example a piece of paper or a tape may be applied around the bolt or the nut or in the socket grip for improving the frictional enga¬ gement therebetween. However, this solution suffers from the disadvantage that it can not be used at the release of the bolt or nut, since the tape will be compressed in the socket. Further, the method requires a separate step of operation; the preparation and the application of a tape for each occasion.

Another proposed solution comprises the use of an adhesive inserted into the socket. Neither is this solution attractive, as the adhesive, which should not be left there permanently, may be difficult to remove as desired. More¬ over it may be difficult to determine in which manner the adhesive should be applied to fulfil its purpose.

The object of the invention is to provide a means, which permits a bolt or a nut to be fixed in an easy manner in a socket without any risk of dropping it during assembly or disassembly, but yet so that it without any difficulties may be removed from the socket. This should be accomplished without any interventions of any kind in the socket or in the ratchet shaft.

This object is solved in accordance with the invention by an adapter having those features defined in the charac¬ terizing part of claim 1.

Thereby a nut or a bolt head may be attracted and held, remaining in the socket without any risk of dropping out, due to the strong magnetic field of the neodynium magnet. Thanks to that, many unnecessary and time consuming occasions of searching for dropped bolts or nuts will be

avoided .

In a most preferred embodiment the magnet is self- adjusting within a limited area of movement in relation to the member to be tightened or removed, in such a manner that the magnet always will tend to take a position, in which it will affect the member in question with a maximum force.

A preferred embodiment will now be described with refe¬ rence to the annexed drawing, wherein: Fig 1 is a side elevational view of an adapter according to the invention,

Fig 2 is a side elevational view, partly in section, of a variant of the embodient, shown in fig 1,

Fig 3 is an elevational view of a magnetic device in the adapter as seen from the socket attachment end,

Fig 4 is a view similar to that of fig 3, showing a further variant of the magnetic device of the adapter according to the invention.

The adapter, shown in fig 1 has essentially the shape of an extension adapter, generally included in most socket sets, and comprises a grip 3 for a ratchet shaft, not shown, attachment. In this case it is a standard type 1/2" square attachment, but any type of attachment may be used. The grip is followed by a massive rod 5 provided at its other end with a 1/2" square attachment 7 intended for engagement with a corresponding socket grip. The present adapter corresponds so far to a quite normal extension adapter.

For securing a nut or a bolt head in the socket, in particular after the removal thereof from the screw joint, the end of the square attachment is recessed and provided with a high energy permanent magnet, sometimes called a supermagnet, in the recess. Preferably the magnet is of

neodynium, though other kinds of supermagnetic materials are conceiveable having similar performances, e.g. samarium-cobalt magnets. Magnets of neodynium comprise sintered neodynium, iron and boron and can relatively easy be formed to a desired shape, e. by extrusion. In general, neodynium magnets have an energy density, which is 9-11 times greater than that of conventional permanent ferrite magnets, the corresponding value of samarium-cobalt magnets being about 6. The magnet is sized so that it will extend into the socket to the vicinity of the nut or bolt grip, so it will attract and hold the member present in the socket, when it has been released. In the case shown in fig 1 the neodynium magnet is placed in a steel sleeve, being pressed into the adapter attachment 7.

9 Further the magnet has an oriented crystal structure, i.e. it has amsotropic characteristics with a strong magnetic field in the longitudinal direction of the adapter 1 and a relatively weak magnetic field m the transverse direction. The steel sleeve, in which the magnet is placed, additionally reduces the magnetic field m the transverse direction, so that the magnetic field in the socket vir¬ tually will be zero. In that way, the inconvenience, which exists with screw drivers having interchangeable tips, which are held at the tool end by a ferrite magnet, in that the tool end will be attracted by and stuck to other parts, will be avoided. This problem is completely eliminated m the socket tool of the invention.

A further disadvantage of ferrite magnets is that a ferrite magnet will become demagnetized, if subjected to impacts, thereby loosing its function. The impact demag¬ netizing phenomenon does not exist in case of neodynium magnets, thus the tool will maintain all its properties, even during heavy work conditions. It would be impossible

to use a ferrite magnet during such circumstances, since its maximum magnetic field would be insufficient for the retaining of e.g. a heavy bolt within the socket.

In a variant, shown in fig 2, of the basic embodiment of fig 1, the neodynium magnet is resiliently connected to the adapter 1 in such a manner that it automatically will ad¬ just itself to the end surface of the bolt head or the nut in case of a possible misalignment in the socket. In this respect the magnet 9 is inserted in a steel sleeve 11, connected to one end of a spring (not shown) , which is contained in and connected at the other end with a threaded bushing 13 to be screwed into a threadened bore in the square attachment 7 of the adapter. By this the neodynium magnet will be movable in all directions, as is indicated by the double arrow, as well in the longitudinal direction as angularly in relation to the axis. Thus it may always optimally adjust itself to the nut or bolt head to be removed and applied, respectively. Further, it should be understood that the magnet need not be countersunk in the adapter attachment 7, but may lie completely outside the end surface of the adapter attach¬ ment 7, e.g. via a pivot joint.

The magnet may have a single pole or a plurality of poles. An example of a device having a plurality of poles is shown in figures 3 and 4. In the twin pole embodiment of fig 3, one pole 12, in this case the south pole, forms a sleeve enclosing the other pole 14, in this case the north pole, and in the variant of fig 4 two semi-cylindrical poles, one south pole 16 and one north pole 16, are en- closed in a cylindrical casing 19. Various variants of this theme are of course conceiveable, e. g. having a plurality of south and north poles in order to opimize the tool.

It is advantageous that the neodynium magnet is formed

as a separate unit, since it easily may be detached from the tool, when not needed, and since the neodynium magnet with its strong magnetism sometimes adversely may affect certain operations, for which there is no need of the magnet. In addition the magnetic adapter may be marketed as a separate unit for supplementing existing sets of sockets without any need of interventions in existing tools.

To make the magnet accesible when needed, the bore in the adapter attachment may be formed to have such a length that the magnet completely may be contained therein, the magnet being displaceable therein, so that it may be with¬ drawn or brought out therefrom when needed.

Even if the neodynium magnet has been applied to an extension tool, it should be obvious to the man skilled in the art, that the connection rod 5 may have any desired length. Basically, it would be sufficient, if it had an attachment grip 3, a bolt or nut attachment 7 connected thereto, and a neodynium type magnet connected to the attachment 7. When retaining very heavy bolts or nuts in a big socket, the retaining force of the socket may additionally be amplified by prior to operation placing a washer of a supermagnetic material in the socket, which will be re¬ tained by the magnet of the attachment 7, thereby ampli- fying the force therefrom.