US 2372553 A
Description (OCR text may contain errors)
March 27, 1945. coDDlNG-roN 2,372,553
FILE BAND Filed June 11, 1942 iigiu'hand files.
` Patented Mar. 27, 1945 Iby direct and mesne. assignments, to Continental Machines, Incorporated,.Minneapolis,
Minn., a corporation of Minnesota" Application June 11, 1942, Serial No. 446,640 3 claims. (C1. e9-fis) My present invention relates to toothed flexible band files and to novel methods of producingsuch toothed flexible band files, The band illes of the present invention are adapted to be made'endless to run over pulleys or wheels in the manner of band saws and have hardened metal file teeth on the outer wide faces thereof, such teeth being rigid with and projecting directly fromthe underlying flexible portion of the band.l These le bands, it should be understood, are of" the `forrned metal variety similar to the teeth of `:Band filesjmade in accordance with the present invention are relatively very thin so that they,
are adapted to be used in very narrow work openings, can be relatively inexpensively 'produced, and have long iexure and cutting life.
Hitherto, such band files, as have been made available'commercially, have been made up of,I
flexible spring steel bands carrying on their outer wide surfaces a seriesof rigid file sections, each of which sections is similar to a section of a rigid hand le and which sections are laid end to end `with each section anchoredl to the band permit independent iiexing of `the bands in one direction when running over wheels. or pulleys. ii'hese prior art Iiles have been difcult' and expensive to produce and have otherwise been ob- Jectionable because of their essentially'high sales i price, the excessive over-all thickness of the filesection-equipped bands making for difficulty for working in narrow work openings, the essential breaks in the filing surface between adjacent rigid le sections and the extreme likelihood of foreign substances collecting between the flexible bands and rigid Ifiling sections, resulting in mis- Y alignment of the filing surfaces of adjacent rigid filing sections. Although large numbers ofk such "atonlyone point longitudinally thereof so as to prior art file bandshavebeen sold and used over ting life, provides a uniform unbroken iiling surface throughout the length of the band, and
which is generally devoid of the above noted and` file band that can be produced at relatively low K,
cost, is so thin as to permit easy working in very `narrow Work openings, has long ilexure and cutother objections inherent in prier art filing bandsof the type employing rigidle sections.
` "To this end I provide two forms of flexible file Abands in each of which highly hardened file teeth are rigidly carried-directly by a flexible metal backing or supporting structure having a long ilexure life. In one of these forms the band file teeth are formed directly in one wide face of the flexible metal band which forms the flexible support for the teeth; but in the other form thereof, the band is a composite structure comprising an inner flexible metal supporting band having file teeth of different metal anchored fast to its wide o'utersurface. l l
\ The two forms of band illes of the present in- 'vention, together with various objects and adi vantages thereof and novel methods of producing `the same, will hereinafter be more fully described and denned in connection with the accompanying drawing wherein like characters indicate like parts throughout the several views.
Referring to the drawing:
i Fig. 1 is a fragmentary perspective view showing certain elements of the multiple ply or composite band structure in separated relation;
Fig. 2 is a view corresponding to Fig, 1 but showing the elements of the band iile forming structure united;
Fig. 3 is a fragmentary perspective view corresponding to Fig. 2 but illustrating the same after the file teeth have been formed in the outer layer or ply of the band;
L: Fig. 4 is a fragmentary prespect'ive View of the single layer form of band le and showing the same during the tooth forming operation;
Fig. 5 is a more or less diagrammatic view il- -lustrating an apparatus for use in heat hardening f the file teeth in a completed endless file band of either of the forms of Figs. 1 to 3,y inclusive, or Fig. 4; A u Fig. (i is a greatly enlarged fragmentary sectional view in side elevation of a section of the completed le band of the type shown in Figs. 1 to 3, inclusive;
Fig. 7 is a View corresponding to Fig. 6 but showing the form of band file shown in Fig. 4;
Fig. 8 is a fragmentary plan view showing how either form of iile band Would appear if provided with intersecting rows of le teeth.
rlf'he partially completed band, `shown in Fig. 3, comprises a flexible supportingk band structure I0 having long ilexure life,. such as spring steel alloy used in band saws and the like, and to the vouter `Wide face of which are rigidly anchored file teeth II which extend obliquely from edge to edge of the band. In practice, however, and as 'will hereinafter be made further apparent, the completed band, as shown in Fig. 8, will be formed with intersecting rows of teeth II. The teeth II are metallically bonded to the wide outer surface of the flexible supporting band I at I2 by suitable processes such as soldering, brazing, welding or the like.
The teeth Il are preferably formed of alloy steel capable of hardening to provide a long life cutting edge and high speed tool steel is considered highly satisfactory for this purpose.
The band file of Figs. 4 and '7 is a single layer structure in which the file teeth IIa are formed in the outside wide portion of a flexible steel band IIIa. In this form of band iile, the band is made up of steel alloy which may be heat tempered to provide long life flexing characteristics or to provide a high quality cutting surface, and for this purpose high carbon steel alloy is considered satisfactory. Preferably, that portion of the band Ilia of Fig. 7 lying below the teeth IIa may be assumed to be heat tempered to a spring temper, whereas the outer cutting edges of the teeth may be assumed to be tempered to provide a very hard cutting surface.
The preferred method of forming the band of Figs. 1 to 3, and 6, will next be described. The first step in the method of producing this multiple layer or composite file band structure comprises metallically bonding together or uniting the flexible supporting band I0 with a tooth forming outer band A in which the teeth II are subsequently to be formed. As previously indicated, the supporting strip or band IU will be of steel or other alloy providing long ilexure life such as high carbon spring steel, whereas the tooth forming outer ribbonlike band A will be of steel alloy providing the highest possible degree of cutting quality. Preferably, the uniting of the bands lil and A will be by silver soldering which can very readily be accomplished by interposing be` tween the bands I0 and A a very thing sheet of silver solder I2 and then heating the bands I0 and A under pressure to the temperature required to fuse the solder and permanently bond the two layers. In practice, this heating of the elements lil and A under pressure can veri7 readily be brought about by passing the superimposed layers IG and A with their interposed strip of solder between heated pressure rollers so that the bonding is accomplished in a continuous operation. If silver solder or similar bonding agent having a similar low fusing point is used, the-bands or elements IU and A will not be heated to their critical temperatures and no tempering will result during the bonding process. In this case the band I9 may loe-initially tempered to provide the desired ilexing characteristics and the tooth forming layer A may be in a completely vannealed state desirable for tooth forming and the temper of neither thereof will be affected as a result of the bonding operation. However, if brazing or .welding is employed, to bond the layers I0 and A, slow cooling and consequent annealing of the elements will be necessary in order to restore the tooth forming layer A to a working condition and the supporting band Ill to a proper flexing condition.
When the bonding process has been completed, the united elements will appear as in Fig. 2.
The next step in forming the band file of Figs. 1 to 3, inclusive, and 6, comprises forming in the annealed steel layer A the file teeth II, and this is preferably accomplished by cutting or milling grooves obliquely .across the layer Ato provide the teeth II. First the grooves will be cut obliquely across the layer A in one direction, as shown in Fig. 4, and then other tooth forming grooves will be similarly cut obliquely across the layer A in the opposite direction so as to provide intersecting rows of teeth, as shown in Fig. 8. It is desirable, however, that one, and preferably both, of tooth forming sets of grooves be cut all or substantially lall the way through the layer A so that the bases of the teeth are substantially at the point of junction between the bands Ill and A. Preferably also, the grooves; which form the teeth, will be round bottomed so as to reduce the tendency to start cracks. The forming of the teeth II by milling or cutting is greatly preferred over stamping or chisel cutting, since these latter processes tend to fracture the underlying metal which would greatly shortenfthe flexing life of the unit, whereas cutting produces no fractures or other injuries.
The next step in the process of forming the band of Figs. l to 3, inclusivey and 6, comprises hardening the teeth II and this is preferably accomplished by flame hardening which consists in heating the teeth II by direct application of heat thereto and then rapidly cooling the band to prevent penetration of the heat into the underlying supporting band IIJ to such an extent as to raise its temperature beyond the critical point and thereby affect its temper. This hardening or tempering of the teeth is preferably accomplished by flame hardening through the medium of an apparatus such as exemplified in Fig. 5, wherein a completed band file has its ends joined to provide an endless band yand is run over a pair of wheels or pulleys I3 that are independently journaled on a supporting structure I4.
The lower of these wheels I3 runs in a tank I5 wherein cooling or quenching water is maintained to the level established by a drain pipe I6. The wheels I3 may be assumed to be driven at a predetermined speed and while they are turning a tempering ame y is applied to the teeth II as the teeth move there passed. Gas is fed to the iiame y through a suitable pipe I1 and nozzle I8 and the flame and speed of travel of the band are controlled to provide the desired degree oi heating of the teeth.
For immediately cooling the teeth to thereby harden the same and prevent further penetration of heat into the band, a stream of quench water a: is projected onto the toothed surface' of the band in close relation to the ame y. Quench water is supplied through a nozzleequipped pipe I9 and this water runs into the tank and maintains a constant flow therethrough.
Since the bottom of the -lower wheel I3 runs in the quenching water, this wheel will be maintained in a cool condition so that it rapidly dissipates heat rfrom the band under the action of the name, and for thisV reason the flame is preferably applied at a point where the file band is in contact with the lower wheel. Of course, the sharp ends of the teeth will become vmuch harder than the wide base portions thereof during the brief heating period and after the band has passed through the f quench,` the ends of the teeth will be very hard and the degree of hardness will rapidly fade off toward the base of the teeth until at the base the teeth may be very little, if any, above the normal annealed condition thereof. This varying degreel of .hardness is illustrated in Fig. 6 by dot shading.
The darkly shaded area at the tips of the teeth Il indicates an extremely high degree of hardness, whereas the lightly shaded areas at the bases of the teeth indicate a substantially unhardened condition.
Two slightly different methods of producing the form of band file shown in Figs. 4 and 7 will now be described. The first step in either of these methods consists Vin forming in the single layer` bandla the'teeth Ila, which teeth are preferably formed by cutting or milling grooves obliquely across the outer surface of the band Hla to form long teeth I l a, as shown in Fig. 4, after which a second set of grooves Will be cut obliquely across the same surface of the band Illa at the opposite angle so as to form intersecting rows of file teeth just as in Fig. 8. The teeth Ha are out in the band I a while the band Illa, which is preferably of high carbon steel alloy, is in an annealed state. In accordance with one of the two methods of producing the finished band of the type shown in Figs. 4 and 7, I flame harden the teeth While the band a is in an annealed state and accomplish this just as previously described in connection with the multiple layer band and through the use of the apparatus disclosed in Fig. 5. In doing this the tips of the teeth lla are heated to a high temperature and then rapidly quenched by the water stream or spray a: so that the hardness fades off toward the base of the teeth to the point where the bases of the teeth ila remain substantially in an annealed state.
The other, and perhaps preferred method of completing the band of Figs. 4 and 7, comprises tempering the toothed band I0a to a spring temper which will provide the greatest possible degree of flexure life, and then subsequently name hardening the teeth in the manner previously described and wherein the water spray cools the teeth before the heat has penetrated the supporting underlying portion of the band Illa suf-v ficiently to materially affect its spring tempered condition..
In connection with the form of band shown in Figs. 4 and '7, it is particularly important that the groovesithat form the teeth be well rounded at their bases so as to reduce to a maximum the tendency to start ilexure cracks, and it is also important that the tooth tempering heat be quenched before the critical temperature is reached in this area near the bases of the teeth.
In the form of band shown in Figs. 1 to 3, inclusive, and 6, the outer layer A of the band, in which the teeth are formed, comprises what may hereinafter be referred to as a strata capable of hardening to cutting temper or hardness, and the underlying layer I0 constitutes strata adapted to be heat treated to provide high exing qualities. In the form of band shown particularly in Figs. f1 and 7, that portion of the band wherein the teeth lla are out, or at least the outer portion thereof, constitutes a strata adapted to be tempered to cutting hardness, Whereas that portion of the band underlying the teeth constitutes a strata adapted to be tempered to give desired flexing qualities, and this is true even when theentire band I0@ is compounded ofthe same alloy. s
Of course, if the finished band is to have long flexure life, there must be a reasonable degree of flexibility in the teeth themselves and for this reason the fading off of the hardness of the teeth from their tips toward their bases is highly important, for when hardened as above de scribed and indicated in Figs. e and 7, the bases ing strip of thin flexible metal adapted to be trained over the pulleys of an endless band type filing machine; a facing strip of thin metal capable of being hardened; and means permanently securing the strips flatwise together; said facing strip having tooth forming grooves cut in its outer surface to a depth substantially equal to the thickness of the facing strip so that the teeth of the file band are relatively independent and connected to one another primarily through said securing means and the flexible backing strip, and said file teeth being hardened.
2. A flexible le band of the character described comprising: an elongated endless backing strip of thin flexible material adapted to be trained over the pulleys of an endless band type ling machine; and hardened individual iile teeth originally independent from the backing strip, each permanently banded to one face of the backing strip with the teeth in closely spaced relationship to form an abrading surface on the band.
3. A flexible flle band of the character described comprising: an elongated endless backing strip of thin spring steel adapted to be trained over the pulleys of an endless band type filing machine; and a facing strip of relatively thin metal permanently bonded to the backing strip and having closely spaced tooth forming grooves cut in its outer surface to a depth substantially equal to the thickness of the facing strip so as to insure flexibility of the file band.