Magnetic head for magnetic pick-up tool

A magnetic head for a magnetic pick-up tool includes a magnet having a pick-up surface and a sleeve member having an open end and being slidably positioned over the magnet, the sleeve member being made of a material acted upon by the magnet such that the magnet exerts a force upon the sleeve for maintaining the sleeve in a rest position wherein the open end extends beyond the pick-up surface, wherein the sleeve is slidable in a direction away from the pick-up surface and against the force to a withdrawn with respect to the magnet. A magnetic pick-up tool including a magnet head is also disclosed.

BACKGROUND OF THE INVENTION 
The invention relates to a magnetic head for a magnetic pick-up tool, and a 
magnetic pick-up tool including same. 
Magnetic pick-up tools are used widely for retrieving ferrous metallic or 
other magnetically acted upon materials from difficult-to-reach locations. 
Such tools are used, for example, by mechanics working on automobiles, 
welders, technicians, machinists, fishermen, toolmakers, hobbyists and the 
like. 
A common problem encountered with conventional pick-up tools is that the 
magnet used for retrieving desired objects has attraction not only upon a 
leading or pick-up surface, but on side surfaces as well. Thus, when 
reaching through other ferrous metallic objects, the magnet has a tendency 
to attract or deflect toward an undesired ferrous or other magnetically 
attracted surface or object. 
A further problem experienced in the art is the need to provide a magnet 
which has significant lifting power in a device which is simple and 
efficient to manufacture, and which is compact and convenient to use. 
In light of the foregoing, it is clear that the need remains for a magnetic 
head for a magnetic pick-up tool device which has good lifting power and 
which has reduced or eliminated tendency to attract toward ferrous metal 
or other magnetically attracted objects positioned radially or to the side 
of the magnet. 
It is therefore the primary object of the present invention to provide a 
magnetic head for a magnetic pick-up tool wherein side attractive forces 
of the magnet are substantially reduced or eliminated. 
It is a further object of the present invention to provide a magnetic head 
for a magnetic pick-up tool wherein the effective lifting power of a 
magnet incorporated therein is increased. 
It is still another object of the present invention to provide a magnetic 
pick-up tool incorporating the magnetic head of the present invention 
which is simple and inexpensive to manufacture and easy to use. 
Other objects and advantages of the present invention will appear 
hereinbelow. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the foregoing objects and 
advantages are readily attained. 
According to the invention, a magnetic head for a magnetic pick-up tool is 
provided which comprises: a magnet having a pick-up surface; and a sleeve 
member having an open end and being slidably positioned over said magnet, 
said sleeve member comprising a material acted upon by said magnet such 
that said magnet exerts a force upon said sleeve for maintaining said 
sleeve in a rest position wherein said open end extends beyond said 
pick-up surface, wherein said sleeve is slidable in a direction away from 
said pick-up surface and against said force to a withdrawn position with 
respect to said magnet. 
In further accordance with the invention, a magnetic pick-up tool is 
provided which comprises: a handle member; and a magnetic head attached to 
said member and comprising a magnet having a pick-up surface and a sleeve 
member having an open end and being slidably positioned over said magnet, 
said sleeve member comprising a material acted upon by said magnet such 
that said magnet exerts a force upon said sleeve for maintaining said 
sleeve in a rest position wherein said open end extends beyond said 
pick-up surface, wherein said sleeve is slidable in a direction away from 
said pick-up surface and against said force to a withdrawn with respect to 
said magnet.

DETAILED DESCRIPTION 
The invention relates to a magnetic head for a magnetic pick-up tool which 
serves to reduce or eliminate side pull of the magnet, and further to 
enhance the pick-up force at the pick-up surface of the magnet, all 
advantageously and as desired in accordance with the present invention. 
Referring to the drawings, FIG. 1 shows a magnetic head generally referred 
to by reference numeral 10 and including a magnet 12 having a longitudinal 
axis A and a sleeve member 14 slidably positioned over magnet 12 and 
slidable in a direction along axis A as will be further discussed below. 
Magnet 12 may preferably be a substantially cylindrical magnet as shown, or 
may have any other suitable shape such as, for example, square, 
rectangular, or partially circular, if desired. Magnet 12 preferably has a 
pick-up surface 16, and has a pole corresponding with pick-up surface 16 
for attracting and holding ferrous or other magnetically attracted objects 
to pick-up surface 16. 
Sleeve member 14 is preferably provided of a material which is acted upon 
by magnet 12, preferably a ferrous or other magnetically attracted 
material. Various grades of steel are suitable, and a low carbon or very 
low carbon steel or other soft steel is preferred and is effective at 
re-directing flux from magnet 12. Still referring to FIG. 1, sleeve member 
14 preferably has a length 18 in the direction of axis A which is longer 
than a corresponding length 20 of magnet 12, also in the direction of axis 
A. 
In accordance with the invention, sleeve member 14 is acted upon by magnet 
12, and a force is exerted by magnet 12 upon sleeve 14, so as to bias 
sleeve 14 toward a rest position wherein sleeve 14 is substantially 
centered or magnetically balanced along axis A with respect to magnet 12. 
In this position, which is illustrated in FIG. 1, sleeve member 14 extends 
beyond magnet 12, at least beyond pick-up surface 16 of magnet 12, and 
preferably beyond each edge of magnet 12 as shown (see also FIG. 2). 
Sleeve 14 can be biased from the rest position rearwardly and away from 
pick-up surface 16 against the magnetic force of magnet 12 so as to allow 
objects to be picked up using pick-up surface 16 as described below. 
Magnet 12 serves to return sleeve 14 to the rest position after sleeve 14 
is released or the object retrieved is removed from pick-up surface 16 as 
desired in accordance with the invention. 
Magnet 12 normally has side or radial flux, which would undesirably attract 
ferrous or magnetically attractable objects to side surfaces 22 of magnet 
12. According to the invention, sleeve 14 serves to absorb and redirect 
radial flux from magnet 12, so as to substantially deaden or eliminate any 
side attractive forces of magnet 12, so as to advantageously reduce or 
eliminate the possibility of magnet 12 attracting radially positioned 
objects which are not intended to be picked up with magnet 12. As set 
forth above, although high or low carbon, hardened or soft steels are 
suitable, it has been found that low carbon or very low carbon steel for 
sleeve 14 is very well suited for redirecting flux so as to induce another 
pole in front edge or ring 24 of sleeve 14 which serves to enhance the 
pick-up strength or force applied by magnet 12, which is advantageous in 
accordance with the present invention. 
It has been found that sleeve member 14 may most preferably be provided 
having a wall thickness (t) sufficient to redirect substantially all 
radial flux from magnet 12. It has been found that suitable thickness of 
sleeve 14 can be related directly to the flux or power (P) of magnet 12 as 
follows. For a typical magnet, it has been found that for each 60-90 gauss 
of flux of magnet 12, approximately 1/1000 of an inch of sleeve thickness 
is desirable. In other words, a ratio of thickness (t) to power (P) is 
preferably between about 0.001 in/90 gauss to about 0.001 in/60 gauss. 
This relation between sleeve thickness and magnet characteristics has been 
found for a typical magnet to advantageously provide a sleeve which 
economizes material and nevertheless provides the desired dampening of 
side pull and focusing of radial flux from magnet 12 toward edge 24 of 
sleeve member 14 as desired. Of course, this relation may vary depending 
upon the type and grade of magnet used. 
As set forth above, sleeve member 14 is held in the substantially centered 
position of FIG. 1 by magnetic force exerted by magnet 12. In accordance 
with the invention, sleeve 14 is slidable along axis A, in the direction 
of arrows X, against the magnetic bias of magnet 12. Referring also to 
FIG. 2, sleeve 14 is illustrated in the centered position, and, in dashed 
lines, in a rearwardly biased position wherein sleeve 14 has been biased 
against the force of magnet 12 to a position wherein pick-up surface 16 is 
more fully exposed for use in attracting and holding a ferrous or other 
magnetically attracted article. As set forth above, it should readily be 
apparent that upon removal of any such object, or other force biasing 
sleeve 14 against the force of magnet 12, that sleeve 14 will readily 
return to the substantially centered position of FIGS. 1 and 2. 
Still referring to FIG. 2, an alternative embodiment of the invention is 
shown wherein magnet head 10 includes a magnet holder 26 having an 
interior well or opening 28 for receiving magnet 12, and having an 
exterior or peripheral surface 30 which surface is preferably 
substantially matched by sleeve 14 so that sleeve 14 is freely slidable 
along surface 30. In accordance with the invention, magnet holder 26 is 
preferably provided of a non-ferrous material such as, for example, 
aluminum, brass, plastic, non-magnetic stainless steel and the like. 
Holder 26 preferably freely transmits and does not interfere with flux 
from magnet 12 so that sleeve 14 can freely slide along holder 26 subject 
to the bias of magnet 12. As shown, magnet holder 26 preferably terminates 
toward pick-up surface 16 of magnet 12 in opening 28 as shown, and on an 
opposite side may suitably have shoulders 32 which are sloped inwardly 
toward axis A substantially as shown in FIG. 2. Shoulders 32 serve 
advantageously to guide sleeve 14 into a proper centered position with 
respect to magnet holder 26 and magnet 12 held thereby, especially if 
sleeve 14 is being biased from a position behind magnet holder 26 toward 
the centered position as desired. It should be noted that although holder 
26 is disclosed in terms of a substantially cylindrical member, 
alternative structures could be provided, depending upon the shape of 
magnet 12. Further, alternative structure could be provided for 
positioning between magnet 12 and sleeve 14 as desired to provide for the 
free sliding nature of sleeve 14 relative to magnet 12 subject to magnetic 
force from magnet 12. 
Referring now to FIG. 3, an application of magnet head 10 in accordance 
with the invention is illustrated. As set forth above, magnet head 10 may 
usefully be incorporated into a tool such as a pick-up tool having a 
magnet positioned at one end of a handle, preferably a substantially 
elongate device which can be used to retrieve magnetic objects from 
locations not easily reached by the person in question. FIG. 3 shows a 
magnetic pick-up tool 34 including magnetic head 10 in accordance with the 
invention attached at one end 36 of a substantially elongate handle member 
38 which may be provided with a hand grip 40 as shown. Still further in 
accordance with this preferred embodiment, elongate handle member 38 
includes a telescopic section 42 (partially broken away in FIG. 3) which 
can be used advantageously to provide for a longitudinally extendable tool 
for enhancing the reach of same. Any suitable extendable structure may be 
used in connection with handle member 38, and a telescopic section such as 
an antenna or the like has been found to be quite useful for same. 
Alternatively, other structures may be provided for handle member 38, 
including but not limited to a simple rod, articulated members for pivot 
to fixed angle(s), flexible elongate structures, spring members and the 
like, and any other structure which enhances the use of the tool for a 
particular purpose. 
Still referring to FIG. 3, sleeve member 14 may suitably be provided having 
a knurled, roughened or textured surface 44 positioned around at least a 
portion of the outer surface thereof. Surface 44 may serve in accordance 
with the present invention to provide better grip for manually moving 
sleeve 14 against the bias of magnet 12 as desired. Surface 44 may be 
provided in any desired ornamental pattern, such as an engraved 
diamond-like pattern and the like. 
Referring now to FIG. 4, magnet head 10 in accordance with the invention is 
shown in an operative position wherein sleeve 14 is deflected in a 
direction away from pick-up surface 16 along axis A so as to at least 
partially expose pick-up surface 16. As shown, an object (O) is held by 
pick-up surface 16 of magnet 12, and the force exerted upon object (O) is 
enhanced by the additional pull induced in edge 24 of sleeve 14 by radial 
flux from magnet 12. In an embodiment wherein pick-up surface 16 of magnet 
12 is a North pole, sleeve 14 according to the invention advantageously 
provides another pole, oriented South, along edge 24 as described. For 
example, this orientation of poles in accordance with the invention has 
been found to provide a magnet head 10 having a typical magnet with a 
basic or normal force of attraction of approximately 4000 gauss with an 
additional pull of approximately 1200 gauss, which advantageously serves 
to increase the pulling power or force of magnetic head 10 in accordance 
with the present invention. As set forth above, once object (O) is 
retrieved and removed from magnetic head 10, sleeve 14 is returned by 
magnet 12 to the substantially centered or magnetically balanced rest 
position of FIGS. 1 and 2. 
In accordance with the foregoing, it should readily be appreciated that a 
magnetic head and a magnetic pick-up tool including such head have been 
provided which readily accomplish each and every object of the present 
invention. Further, magnet head 10 of the present invention may suitably 
be incorporated into other tool structures as desired. 
It is to be understood that the invention is not limited to the 
illustrations described and shown herein, which are deemed to be merely 
illustrative of the best modes of carrying out the invention, and which 
are susceptible of modification of form, size, arrangement of parts and 
details of operation. The invention rather is intended to encompass all 
such modifications which are within its spirit and scope as defined by the 
claims.