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Publication numberUS3392767 A
Publication typeGrant
Publication dateJul 16, 1968
Filing dateNov 15, 1965
Priority dateNov 15, 1965
Publication numberUS 3392767 A, US 3392767A, US-A-3392767, US3392767 A, US3392767A
InventorsJr George B Stillwagon
Original AssigneeGardner Denver Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Magnetic tools
US 3392767 A
Images(1)
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Description  (OCR text may contain errors)

Ju y 16, 1968 G. B. STILLWAGON, JR 3,392,767

MAGNETIC TOOLS Filed NOV. 15, 1965 FIG-4 INVENTOR.

GEORGE B.STILLWAGON,JR.

ATTORNEYS United States Patent 3,392,767 MAGNETIC TOOLS 1 1 GeorgeBhStillwagon, Jr., Dayton, Ohio, assignortov Gardner Denver, Company, Dayton, Ohio, a corporation of Delaware ,Filed'Nov'. 15, 1965, Ser. No. 507,916

9 Claims. (Cl. 145-50) T his, invention relates to driving. tools and more particularly to such tools which incorporate a permanent magnet for picking up and retaining fastening devices to be driven by the tool.

Magnetic pick up screw drivers, sockets, and the like are useful in holding and retaining a fastener to be driven, in order to free the operators .hands of this task while positioning the fastener accurately in relation to the fastener accuratelyin relation to the driver, as in assembly lineoperations. However, the permanent magnet structure in such tools frequently imposes limitations on the design ofvthe tools and has resulted, in some instances, in substantially increased costs as compared to a conventio'na l tool. For example, in screw driven bits, the magnet has frequently been positioned within thetool holder axially behind the bit making relatively ineflicient use of the magnetic material. In bolt clearance sockets, where the magnet 'is received and mounted for axial movement within the socket, it was commonly necessary to shield themagnet with a hard nonmagnetic alloy, such as brass, toprevent the magnet from shorting out on the tool body. Such brass sleeves imposed additional limitation in design as well as added expense.

The magnetic tools of the present invention incorporate a sheet-like magnetic material which is magnetically polarized through its thickness. In other words, the present invention incorporates magnetic material which is thickness-oriented, and which is suitably associated with the tool topro'vide concentric or spaced annular poles, providing efficient use of the magnetic material in a compact tool construction.

It is accordingly an important object of the present invention to provide a magnetic tool in which there is formed spaced-apart concentric pole pieces and between which thereis a strip of thickness-oriented magnetized material.

A more particular object of this invention is the provision of a magnetic tool, as outlined above, in which one of the pole pieces is an annular, concentric sleeve orthe like, and in 'which the tool-body itself may comprise one of the pole pieces.

Accordingly, it is an object of this invention to provide an improved magnetic tool construction which may be utilized in a wide 'variety of forms including but not limited to sockets for driving nuts, sheet metal fasteners, an d'the like, and screw driver bits including but not limited to drivers for cruciform-slotted screws, and ordinary screws.

Another object of this invention is the provision of a magnet assembly which is adapted for retaining fasteners in driving relation to a driving tool and the like, in which the assembly is formed with inner and outer spaced 3,392,767 Patented July 16, 1968 apart pole pieces defining an annular space therebetween, and an annular thickness-oriented magnet is received in the space between a pole piece. f

These and other objects and advantages of the present invention will become apparent from the following description, the accompanying drawings and the'appended claims.

In the drawings:

FIG. 1 is a longitudinal section through a drive socket constructed according to this invention;

FIG. 2-is a transverse section through the socket taken generally along the line 2--'2' of FIG. 1; 1'

FIG. 3 is a'perspective view of a typical strip of thickness-oriented magnetic material used in this invention prior to forming or shaping;

"FIG.- 4 is a perspective view of the material of FIG. 3 after it has been shaped into cylinder;

'FIG. 5 is an elevational view of a screw driver bit con-' structed according to this'invention and showing-atypical fastener to be retained thereon;

FIG. 6 is an enlarged longitudinal section through the magnetic assembly of FIG. 5;

FIG. 7 is a transverse section taken generally along the lines 77 of FIG. 6;

FIG. 8 is an elevational view of a further embodiment of the invention as applied to a smaller screw driver bit;

FIG. 9 is an enlarged longitudinal section through the magnetic assembly of FIG. 8 with the bit shown in elevation;

FIG. 10 is a further partial longitudinal section of the invention as applied to a screw driver, showing the screw driver elevation; and

FIG. 11 is a modification of a portion of the structure shown in FIG. 10 particularly adapted for retaining fasteners of small size.

Referring to the figures of the drawings which illustrate preferred embodiments of the invention, a magnetic pick up socket 10 is shown in FIGS. 1 and 2 as having a body 11 of generally tubular configuration. The socket shown in FIGS. 1 and 2 is of the type known as a clearance socket, since it provides an opening to receive the threaded end of a bolt while a fastener is being driven on the bolt. Accordingly, the body 11 is formed with a forward end 12 and a rearward end 13 and a generally cylindrical bore 14. The forward end 12 is formed with a non-circular outline which, in this case, is shown as hexagonal. The rearward end 13 is shown as forming a square drive socket 15, adapted, for instance, to be received on the square shank of a driver.

The socket includes forming a pair of spaced-apart, generally annular and axially extending pole pieces. In this embodiment, the body 11 forms one of the pole pieces, and a steel sleeve 18 received in the bore 14 forms the other pole piece. As shown in FIGS. 1 and 2, the pole pieces formed by the body 11 on the one hand, and by the sleeve 18 on the other, define an annular space therebetween within which is received a strip 20 of thickness-oriented magnetized material, such as as shown in FIGS. 3 and 4.

The magnetized material is preferably a rubber bonded barium ferrite composition which has magnetic properties similar to those displayed by isotropic barium ferrite sin tered magnets. A suitable material for this purpose is disclosed in US. Patent No. 3,211,966 and the types I and I-H sold under the tradename of Plastiform by Leyman Corporation, 5178 Crookshank Road, Cincinnati, Ohio.

The characteristic feature of the material 20 is that it is normally magnetized through the thickness, as distin guished from magnets in which the poles are formed at the longitudinal ends. Accordingly, the magnetic properties of this material may be considered as being thickv 3 ness oriented. Since the bonding material is an elastomeric, such as rubber, the material may be formed into a cylinder such as shown in FIG. 4. This is the shape which the material of the magnetassumes when it is pressed into the bore 14 between the sleeve 18 and the body 11, substantially as shown in FIG. 2.

Preferably, the strip making up the magnet 20 is formed of such a length as to form a complete cylinder when encapsulated within the tool. However, it is within the scope of this invention to employ, instead, segments of a cylinder comprising the magnetic material 20 between the annular pole pieces.

The forward end 23 of the magnet 20 is shown as being slightly recessed inwardly of the axial end of the sleeve 18. Also, the axial end 24 of the sleeve is proportioned in the socket opening 12 so that it comes into physical contact with a fastener received within the socket. Since the annular socket body 11 at the socket opening 12 forms one of the poles of the magnet, and since the end 24 of the sleeve 18 forms the other, it will be seen that when a fastener is received in the socket, it closes the magnetic space between the poles, resulting in an efficient and powerful retaining force on the fastener. The axial opening 25 formed within the sleeve 18 defines a clearance space through which the end of a bolt may be received while the fastener is being driven thereon.

It will be seen from this embodiment that there is no relative movement between the magnetic assembly and the body of the tool. Once the magnetic assembly has been positioned in the bore 14, it becomes a permanent part of the tool. Further, all need for brass sleeves or bushings of other non-magnetic material and magnet positioning springs are eliminated.

FIGS. 5-7 show the invention applied to a screw driver bit. In this embodiment, there is shown a bit which is formed from hexagonal stock and has a rear driven portion 31, an intermediate body portion 32 and driving head 35. The driving head 35 may be formed with driving wings 36, as shown in FIG. 5, to be received within the slotted recesses of a fastener 38.

In this embodiment, an integral magnet assembly is shown as being received on the intermediate or central portion 32 of the bit 30. This magnet assembly again comprises a pair of spaced annular pole pieces including an inner sleeve 42 which is proportioned to be received over the bit 30, and an outer sleeve 44. The outer sleeve 44 is formed with a rearward inwardly turning end or rim 45 defining an axial opening 46.

The inner sleeve may be recessed at the rearward end thereof as indicated at 48 to receive snap rings 49 which engage the body of the bit 30. As shown in FIG. 6, the axial extent of the recess 48 is such as to permit limited axial movement of the assembly 40 with respect to the snap rings 49, so that the magnet assembly may align itself on the bit 30 in position to contact the fastener 38. This provision for such limited axial movement of the assembly provides a means for compensating for variations in the length of the recesses in the fasteners, and for the wear of the tip 36 of the bit, while always assuring direct contact of the terminal ends 50 and 51 of the sleeves 42 and 44 with the fastener 38.

Again, as described above, a strip of thickness oriented magnetized material 20 is formed in the annular space defined between the sleeves 42 and 44, and forms opposite magnetic poles at the ends 50 and 51. Since the ends 50 and 51 come into full contact with the head of the fastener 38, and since the construction of the magnet assembly is such that there is a minimum of leakage between the pole pieces, there results a highly efficient use of the magnetic force of the material 20 resulting in a compact and durable magnet assembly.

The embodiment shown in FIGS. 8 and 9 is somewhat similar to that of FIGS. 5-7 except that this embodiment is particularly adapted for use where compact size is desired. Accordingly, there is shown a screw driver bit which. is formed with a hexagonal driven portion 61 and a generally cylindrical driving end 62 of substantially reduced diameter, such as for driving relatively small screws. In this embodiment, the magnet 20 is formed in the shape of a cylinder and is received directly on the cylindrical surface of the bit end 62 and is retained or encircled by a sleeve 65.

The sleeve 65 has a forward tapered end 66 which may be rolled to reduce the crosssectional size of the forward end. However, it is important that the forward end 66 does not contact the bit and an annular clearance 67 has been provided to prevent shorting of the magnetic flux path.

In the embodiment of FIGS. 8 and 9, the driving end of the bit 60 becomes one of the pole pieces, and the sleeve 65 becomes the other pole piece. This embodiment has been found to be highly efficient and satisfactory for retaining fasteners in driivng position on the bit 60.

In FIGS. 10 and 11 there is shown a further embodiment of the invention as applied to an elongated screw driver shank in which the magnet assembly is slidably mounted on the shank of the screw driver for retaining a threaded fastener in spaced relation to the end of the screw driver initially, while permitting the screw driver to move into operative engagement with the fastener while retaining the fastener in position. In this embodiment, the screw driver is shown as including an elongated shank with a driven end 81 thereon adapted to be received within a suitable socket. The forward end of the shank 80 is tapered and forms a screw driving blade 82.

A magnet assembly 85 is shown as being mounted over the shank 80 for limited axial movement thereon. For this purpose, the shank 80 is provided with an annular groove 86 and a snap ring 87 therein. The assembly 85 includes an outer sleeve 90 with an inner snap ring 92 at the rearward end thereof engageable with the ring 87 to limit the extent of forward movement of the assembly 85 on the shank 80-. The sleeve 85 may be further provided with a snap ring stop 92, and a spring 94 is received within the sleeve 85 in compression between the stop 92 and the ring 97, to urge the assembly 85 forwardly, as shown in FIG. 10.

The magnet assembly 85 further includes an inner sleeve 95 which is concentric with the sleeve 85 and which is received generally at the forward end thereof and which terminates at a forward end 96. The end 96 is spaced axially inwardly of the forward end of the sleeve 85. The material 20 is shown as being received in the annular space between the sleeves 95 and 85, and is spaced slightly inwardly of the forward end 96, as shown at 98 in FIG. 10.

The embodiment of FIG. 11 is similar to that of FIG. 10 except that it shows a construction which is particularly adapted for use with fasteners of small size. In this embodiment, the sleeve 85 supports at its forward end an auxiliary pole piece member 100 which, as shown, comprises an annular sleeve with an inwardly turned end 102. The inwardly turned end 102 is thus proportioned to engage the circumferential edge of the fastener 105 while the inner sleeve 95 engages the face of the fastener. Alternatively, the sleeve 85' may be molded or formed with an inwardly turned ledge so as to engage the fastener 105.

It will therefore be seen that this invention provides a compact and highly efficient magnetic tool and magnet assembly for such tools. The tool body itself may be utilized as one of the pole pieces or separate annular concentric pole pieces may be provided. The thickness-oriented magnetic material utilizes a minimum of space while maximum utilization is made of the magnetic properties thereof.

While it is preferred that the material of the magnet 29 be formed of flexible material, as described above, and magnetized through its thickness, it is within the scope of this invention to use cylindrical magnets of other compositions, such as, for example, barium ferrite ceramic which are similarly thickness-oriented with respect to magnetic poles. The term thickness-oriented magnetized material as used herein is intended to refer to any such suitable material formed either flat and subsequently rolled or curved as by form-ing or bending, or formed initially as an annulus or sleeve.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein within departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A rotatable magnetic tool for picking up magnetically attractable threaded fasteners and retaining such fasteners in a driving position thereon and for rotatably driving such fasteners, comprising a tool body having a fastener driving portion, means forming a pair of spacedapart generally annular pole pieces having terminal ends adjacent the driving portion of said body and defining an annular space therebetween with at least one of said pole pieces being proportioned to engage a fastener thereby and magnetically retain said fastener in said driving position, and an annular thickness-oriented elastomeric strip magnet received in the said annular space between said pole pieces forming opposite magnetic poles at the said terminal ends.

2. The tool of claim 1 in which one of said pole pieces includes said tool body.

3. The tool of claim 1 in which said tool body comprises a screw driver bit, and in which said magnet is supported in circumferential relation to the bit adjacent the driving end thereof.

4. The tool of claim 1 in which said tool driving portion comprises a socket wrench having means in said body forming an axial opening, said magnet being received in said opening, and one of said pole pieces being formed as a tubular sleeve received within said magnet and defining a bolt clearance space therein in generally axial alignment with the driving portion of said tool.

5. The tool of claim 1 in which said pole pieces comprise a pair of concentric tubular sleeves received on said body.

6. The tool of claim 1 in which said pole pieces comprise a pair of concentric sleeves, means closing the annular space between said sleeves at an end thereof remote from said tool driving portion, and means slidably mounting said pole pieces on said body.

7. A magnetic pick up socket wrench for picking up and driving fasteners, nuts and the like com-prising a body, 5

means adjacent one end of said body forming a driving portion of non-cricular outline for engaging such fastener and further defining an axial bore within said socket body,

an annular strip of elastomeric thickness-oriented magnetic material received in said socket body inwardly of said driving portion, and a generally tubular pole piece received in said body radially inwardly of said strip and forming a relatively close fit with said strip with a forward portion thereof positioned in said driving portion to engage a fastener therein and defining an axial clearance opening therethrough.

8. A magnetic pick up screw driver comprising a driving bit having a plurality of screw driving wings formed on one end thereof, a screw retaining magnet assembly on the body of said bit including an inner sleeve forming a first pole piece and an outer sleeve forming an outer pole piece and defining an annular space therebetween, a strip of thickness-oriented magnetized material received in said annular space in surrounding relation to said first pole piece, means on said first pole piece for gripping said bit body and retaining said magnet assembly thereon, and the forward edges of said pole pieces forming opposite annular magnet poles and being proportioned to engage a fastener and retain the same in driving position on said bit.

9. A rotatable magnetic tool for picking up magnetically attractable threaded fasteners and for retaining such fastensrs in a drive position thereon and for rotatably driving such fasteners comprising ,a tool body forming a screwdriver bit having a driving end, means forming a pair of spaced apart generally concentric pole pieces with said bit body forming the inner of said concentric pole pieces said concentric pole pieces defining an annular space therebetween with said bit driving end being proportioned to engage a fastener thereon and magnetically retain said fastener in said driving position, and an annular thicknessoriented elastomeric strip magnet received in said annular space between said pole pieces forming opposite magnetic pole-s at said pole pieces with said driving end of said bit extending beyond the end of said strip magnet.

References Cited UNITED STATES PATENTS 2,864,417 12/1958 Scholten 7-1 2,999,275 9/ 1961 Blu-me 156243 3,007,504 11/1961 Clark --50 3,253,262 5/1966 Stillwagon, et a1. 145-50 FOREIGN PATENTS 1,266,884 6/ 196-1 France.

ROBERT C. RIORDON, Primary Examiner. WILLIAM FELDMAN, Examiner.

R. V. PARKER, IR., Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2864417 *Mar 30, 1956Dec 16, 1958Indiana Steel Products CoMagnetic hammer
US2999275 *Jul 15, 1958Sep 12, 1961Leyman CorpMechanical orientation of magnetically anisotropic particles
US3007504 *Jul 25, 1957Nov 7, 1961Wade StevensonMagnetic tool holder
US3253262 *Dec 30, 1960May 24, 1966Bunker RamoData processing system
FR1266884A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3630108 *May 11, 1970Dec 28, 1971Gardner Denver CoMagnetic tool
US3707894 *Feb 10, 1971Jan 2, 1973Gardner Denver CoMagnetic fastener driving tool
US3731722 *Oct 8, 1971May 8, 1973Carr HKeeper accessory for various types of conventional tools
US3808918 *Sep 4, 1973May 7, 1974Carr HMagnetic keeper accessory for wrench sockets
US4603608 *Sep 20, 1984Aug 5, 1986Deutsche Gesellschaft Fur Wiederaufarbeitung Von Kernbrennstoffen MbhRemotely-manipulated apparatus for performing maintenance work in shielded cells
US4692073 *Jul 1, 1986Sep 8, 1987Martindell J RichardHandle adapter and chuck apparatus for power bits
US4920833 *Dec 12, 1988May 1, 1990Eric RosenthalBlind setting rivet
US4936172 *Mar 9, 1989Jun 26, 1990Jackson Jack DInterlocking screw and screwdriver
US5014379 *Nov 20, 1989May 14, 1991Hull Harold LCombination tool
US5056386 *Nov 22, 1989Oct 15, 1991Black & Decker Inc.Screwdriver bit and finder system
US5146814 *Jun 3, 1991Sep 15, 1992Vasichek Richard AMagnetic keeper accessory for wrench sockets
US5163345 *Feb 25, 1992Nov 17, 1992Snap-On Tools CorporationSpring-loaded magnetic driver and method of assembly thereof
US5178048 *Oct 24, 1991Jan 12, 1993William MatechukMagnetic fastener retainer
US5191691 *Feb 10, 1992Mar 9, 1993Yoshitaka AoyamaApparatus for feeding slender parts
US5199334 *May 28, 1992Apr 6, 1993Vasichek Richard AMagnetic keeper accessory for wrench sockets
US5277088 *Jan 8, 1993Jan 11, 1994Vasichek Richard AMagnetic keeper accessory for wrench sockets
US5400681 *Sep 13, 1993Mar 28, 1995Strauch; Melvin D.Screw driving extension apparatus
US5425523 *Apr 5, 1993Jun 20, 1995MiradcoApparatus for establishing predetermined positions of one element relative to another
US5458030 *Nov 2, 1993Oct 17, 1995Betts; GeoffreyScrewdrivers
US5542320 *Jun 28, 1995Aug 6, 1996Vasichek Enterprises LlcMagnetic keeper accessory for wrench sockets
US6006630 *Aug 12, 1997Dec 28, 1999Vasichek Enterprises LlcMagnetic keeper accessory for wrench sockets
US6026717 *Jul 23, 1998Feb 22, 2000Anderson; WayneDriver tool with high energy magnetizer/demagnetizer on tool handle
US6026718 *Sep 28, 1998Feb 22, 2000Anderson; WayneHigh energy magnetizer and selective demagnetizer integral with driver tool or the like
US6032557 *Sep 1, 1998Mar 7, 2000Anderson; WayneDriver tool kit with high energy magnetizer/demagnetizer on tool handle(s)
US6047620 *Jan 14, 1998Apr 11, 2000Kozak; BurtonTool for inserting and removing one-way fasteners, an off-center tool for inserting and removing one-way fasteners
US6060801 *Sep 28, 1998May 9, 2000Anderson; WayneHigh energy magnetizer/demagnetizer for drill housing
US6105474 *Jul 31, 1996Aug 22, 2000Anderson; WayneDriver tool with efficient high energy permanent magnetizer on tool handle
US6138538 *Mar 30, 1998Oct 31, 2000Neijndorff; EduardFinish-protective tool pieces and finish-protective collars
US6182537Nov 2, 1998Feb 6, 2001Vasichek Enterprises, LlcMagnetic spark plug keeper accessory for wrench sockets
US6278349Feb 9, 2000Aug 21, 2001Giffen Tec Inc.Apparatus for magnetizing a metallic driving tool
US6374709Nov 1, 2000Apr 23, 2002Vasichek Enterprises LlcMagnetic spark plug keeper accessory for wrench sockets
US6499168 *Feb 15, 2000Dec 31, 2002Wayne AndersonDrill adapter with efficient high energy permanent magnetizer
US6530299 *Nov 20, 2001Mar 11, 2003Tsai-Fa LiuJoint adapter for a power drill screw driver
US6655240Jun 14, 1999Dec 2, 2003Snap-On Tools CompanyInsulating driver with injection molded shank and fluted working tip
US7051630 *Aug 1, 2003May 30, 2006Young Man LeeInsulated magnetic screwdriver
US7107882 *Oct 1, 2004Sep 19, 2006Chang Wun-HaiSlip-resistant magnetic sheath for a screwdriver
US7159491 *Sep 7, 2005Jan 9, 2007Easco Hand Tools, Inc.Oil drain plug socket for a wrench assembly
US7261023 *Jun 22, 2004Aug 28, 2007Vessel Industrial Co., Ltd.Bit holder device
US7530771 *Sep 27, 2006May 12, 2009Burton KozakNon-ferrous bit for use with a magnetic chuck
US7594874Apr 12, 2006Sep 29, 2009Meissner Richard KQuick connect climbing hold
US7788997 *Apr 7, 2006Sep 7, 2010Combined Products Co., #1, Inc.Magnetic device for holding and driving bits and fasteners
US7905164Sep 18, 2008Mar 15, 2011Combined Products Co. #1 Inc.Adjustable one way screw remover
US8087328Oct 20, 2010Jan 3, 2012Burton KozakAdjustable one way screw remover
US8215206Nov 14, 2007Jul 10, 2012Combined Products Co. #1 Inc.Damaged bolt and screw removing devices
US8276482Aug 11, 2009Oct 2, 2012Combined Products Co. #1 Inc.Damaged bolt and screw removing devices
US20130125714 *Nov 29, 2012May 23, 2013The University Of North Carolina At Chapel HillScrew holder-driver apparatuses, systems and methods
DE10148943A1 *Oct 2, 2001Nov 28, 2002Holland Letz Felo WerkzeugSchraubvorrichtung für Schraubendreher-Einsätze
DE10148943B4 *Oct 2, 2001Feb 26, 2004Felo-Werkzeugfabrik Holland-Letz GmbhSchraubvorrichtung für Schraubendreher-Einsätze
DE19907837A1 *Feb 24, 1999Sep 14, 2000Schmidt Ulrich Ush SchraubwerkScrew driver has bush containing hollow cavity, permanent magnet with thrust surface, threaded connection and lock nut ring
DE20312920U1 *Aug 18, 2003Sep 23, 2004Felo-Werkzeugfabrik Holland-Letz GmbhScrewdriver has a blade made from ferromagnetic steel with a profiled tip for interlocking with a screw, and a magnetic holding unit for screws
EP1027959A2 *Feb 8, 2000Aug 16, 2000Makita CorporationMagnetically attractive driver bit assembly
EP1260319A2 *May 16, 2002Nov 27, 2002Felo-Werkzeugfabrik Holland-Letz GmbhScrew driving device for screwdriver bits
EP1637285A1 *Jun 22, 2004Mar 22, 2006Vessel Industrial Co., Ltd.Bit holder device
WO2000045998A1 *Feb 3, 1999Aug 10, 2000Wayne AndersonDriver tool with high energy magnets
WO2005000531A1Jun 22, 2004Jan 6, 2005Yasuaki TaguchiBit holder device
Classifications
U.S. Classification81/451, 81/125, 7/165, 7/901, 81/900, 81/438
International ClassificationB25B23/12
Cooperative ClassificationY10S7/901, Y10S81/90, B25B23/12
European ClassificationB25B23/12