US1870818A - Grinding machine - Google Patents

Description

.Allg 9 19.32 M. MAAG ET AL 1,870,8w

GRINDING MACHINE Original Filed Nov. 10. 1928 2 She'etsuSheet 1 r I L 1 Fig-2 w X" MMAAG Aug. 9, 1932.

M. MAAG ET Al.

' GRINDING MACHINE 2 Sheets-Shea?l 2l Original Filed Nov. 10. 1928 x J B' Patented Aug. 9, 1932 UNirI-:D sTATEsPATENr ori-ics MAX Mime, or SCHWAMENDINGEN, SWITZERLAND, AND ROBERT sALoMoN, or NEU-1 ILLY-S'UR-SEINE, FRANCE, ASSIGNORS AFFUTER, OF PARIS,v FRANCE 'ro soorn'rnnnrunns DE MAGHINES GRINDING MAGHINE Original application 1ed N'ovember 10, 1928, Serial No. 318,327, and in 'Germany November 23, 1927.

' Divided and this application filed December 28, 1929. Serial No. 417,051.

Our invention relates to a machine for the manufacture of knives, such as safety razor blades, and more particularly to a bladesharpening orgrin'ding machine designed to 5 carry out the method disclosed and claimed in our co-pending application Ser. No.

318,327 of which the present application is a division.`

An object of our invention isa machine which will produce a razor blade having a perfectly sharp and acute edge and which will not inthe course of the grinding or sharpening operation generate any ridge which would neccessit-ate a cumbersome treatment for removal subsequentto the grinding operation proper. Another object of our invention .is a blade-sharpening machine of improved eliciency and accuracy of operation.

The process of sharpening knives, particularlyrazor blades, Which has generally been in use prior to our invention, `involves the neccessity of removing the ridge from the edge after the latter has been ground. After such removal, however, d'ull spots remain on the edge in dependence upon the thickness of the ridge and a subsequent polishing treatment is. required to sharpen said dull spots in order to obtain a sharp edge which is ready for use. Our invention permits of materially reducing this polishing step which does not only involve a material time consumption,- but affects the curvature of the edge'fac'es in the immediate proximity of the edge in an unfavorable manner with the result that the edge is less sharp than it would be with a uniform curvature throughout the entire 1 area of the ground faces.

Our invention permits the generation of a of the grinding operation, so that noridge at all comes to existence during vthe sharpening process. Hence, the edge may be finished with a very slightpolishin treatment which does not adversely aifect t e sensitive educ. f y

ijom the foregoing it will be appreciated that with our novel grinding machine the sensitive edge is carefully preserved from insharp edge free from any ridge as a resultcarrying out our method of sharpening ra`zor jury and that the edge in case it should beinjured may be completely re-generated in a simple manner.

Our invention is based upon the following consideration: Whena work piece is subjected to the operation of grinding or cutting tools the latter exert, as a rule, a pressure on the material operated upon. lfVhere they operate upon a thin edge of the work piece, the' marginal zone of said edge which on ac count of its reduced thickness islunable to re- A sist the pressure, will yield and will be pressed back from the edge to form a ridge which is no longer subjected to the tool and, therefore, is not removed. The conditions which account for the formation of aridge, are always prevailing inthe marginal zone of a sharp edge, the rear faceof which is in an acute angle to the front operated on by the cutting or grinding tool as is the case with knives or similar work pieces. It follows .'70

'that the -:formation of a ridge can be prevented` by providing a support for the marginal zone which supports the latter against the pressure exerted by the tools. Our invention isbased upon the use of such 75 a blade 4support; which is in intimate con 'tact with the rear face of I.the edge,'preferably throughout the entire area of the same up to the very edge, during the course of the grind'- ing process whereby any yielding of the marginal zone and@ consequently, the formation of any ridge is avoided. In other words, we

support the rear falce of the edge in the course of the grinding process, preferably over its entire length,l at least up to the line determining the fina-l situation of the. cutting edge of the blade so.' that ythe support is' partly ground away together with the blade bearing against it. In this regard our invention differs from the prior art in which the support no bearing against the rear face was not ground oil' 'together with the blade.

In the' drawings We have illustrated a pre.- 'A ferred embodiment of our novel grinding machine which is particularly well adapted for 'ne blades forming the subject-matter of the aforementioned application. ln Fig. 1 we have shown a side view of the machine; Fig. 2 is the top view and-Fig. 333e@ j is a perspective partial viewof the machin the part situated to the left of line :zr-w o Fig. 1 being broken away. Fig. 4 illustrates a razor blade and Fig. 5 is a diagram indicating the successive stages of the method of operation.

The frame 1 is provided with a horizontal' tional engagement with the shoulder 7 and the disc 8 for common rotation.

In the recessed central part of frame 1 an auxiliary guide 12 is arranged and kept in place by means of a bolt 13 to adjustably accommodate a carrier 13 carrying a blade holder 17, 18, 20. The carrier 13 is displaceable in longitudinal direction and may be arrested in any desired positiopiby'means of clamping screws 14 and 14. *The ends of carrier 13 are formed with u wardly projecting arms having twp poin d screws 15- and 16 inserted in axial registry. These screws serve topivotally support a block 17 and to keepl the latter in a predetermined position.

*of itsV surface may Attached to block 17 is an upwardly projecting sprln leaf 20 carrying at its upper end'a second lock 18 which is integral with an upwardly projecting blade holder part 19 cooperating with another blade holder part 21 hinged to block 18 by means of a pivot 22 (Fig. 3). Both blade holder parts are adapted tov keep between them a razor blade 23 such as shown in Fig. 4, and are for this purpose provided with a bolt 51 attached to the part 19 and projecting through a hole provided in part 21 to receive a clamping nut 24. Furthermore, the part 19 is provided with two pins 25 and 25 projecting through registering openings in part 21. The blade 23 is slipped with its holes 52 and 52 over these pins and, then, `part 21 is folded over the blade and pressed thereupon by the nut 24l which is applied to the bolt 51. Thus it will be seen, that the razor blade 23 is kept in upright operative position relative to the grinding wheel.

Furthermore, a blade support is arranged on frame 1 to bear against the rear face of the edgeto support the latter. As a part of the supporting face of the support is ground away in each cycle of operation, the support is preferably shiftable in the direction of-its supportingface whereby successive portions be brought into contact relation tothe blade.

' In the embodiment shown, the support is,

for this purpose, formed by a rotatable /cylin ing a shaft 28 which is parallel to shaft '6 and arranged at the same level. The shaft 28 carries the cylinder 29. This cylinder has a peripheral recess 30 serving to give the Agrinding disc an unobstructed and free access to the edge of the razor blade 23, compare Fig. 4.

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Mounted on and secured to shaft 28 is a cord pulley 31 provided with clutch teeth 32 adapted to engage registering recesses in the lateral face of the supporting cylinder 29.

,The pulley is, furthermore, provided with worm gear teeth 33 engaging a worm 34 carried by a vertical shaft 46 rotatable in a suitable vertical bearing provided in the standard 26. On pulley 31 a cord 35 isfwound having its one end attached thereto, at 31', and

and having its other end' hanging downwardly and provided with a weight 36.

The carriage 3 is formed with a downwardly directed projection 37 which is recessed to accomodate the end of a helical spring 38 bearing against an adjustable screw 39 -inserted in the front'wall of frame 1 and rmitting of an adjustment ofthe pressure exerted by thespring on the carriage 3 which is pressed towards the right and thus kept in permanent engagement with a cam 40 mounted upon a horizontal. cam shaft 41 journalled in frame 1 and lcontinually subjected to a slow rotation by suitable driving means not shown in the drawings. On this shaft a second cam 42 is mounted having a projection 43 arranged to cti-operate with a horizontal push rod 44'shiftably mounted in frame 1. In the course of each revolution of shaft 41, this push rod is once shifted towards the right thereby engaging the one arm ,of a bell crank 45 freely swingably mountedl upon the lower end of shaft 46. The other arm of the bell crank 45 carries a pawl 47 arranged to engage a ratchet wheel 48 rigidlyattached to shaft 46 and kept in engagement therewith by action of a sprlng leaf 49 bearing against the pawl. The bell crank 45 is kept in perma-` nent contact with the push rod 44 by means of a tension spring 50 vextended between a suitable projection of frame 1 and one arm of the bell crank.

The operation of the machine is as follows: A rapid rotation in the direction of the arrow of Fig. 1 is imparted to the grinding disc 8 by a suitable belt (not shown) driving the pulley 9. Simultaneously, the cam shaft 41 .is slowly rotated in clockwise direction.

When the parts assume the position shown in Fig. 1 the projection 37 is in engagement with the portion of cam of smallest radius so that carriage Siassumes its position nearest -to, in fact in contact with, the supporting cylinder 29. In this position a cycle of operation has just been finished. In the course ofv the subsequent rotation of cam 40 through an angle of 90 the carriage 3 ,is moved towards its uttermost left point and the disc 8 is withdrawn from blade 23 permitting the blade holder 13 to be removed after a release of the clampng screws 14 and 14 and to be replaced by a similar spare holder provided with a new blank to be sharpened.

In the course of the further rotation of cam 40 through another 90 the grinding disc- A corresponding turn has been imparted to worm 34 and to the supporting cylinder 29.

When the section 43 has moved past the push rod 44 the latter and the bell crank are restored to their normal position by action of the tension spring 50. The purpose of the turnoi the cylinder 29 preparatory to a new cycle will be later explained.

In the course of the rotation of cam 40 through the third quarter of'a revolution the carriage 3 is gradually advanced towards the support 3() and the new razor blade in cont-act therewith until thelatter is engaged by the grinding disc 8 and is sharpened by the latter transformed into a nearly iinished condition requiring but a. slight polishing treatment, whereupon aV new cycle of operation is initiated.

In order' to reset the grinding machine for the subsequent operation, the blade holder 13 is removed upon a suiiicient release of tneclamping screws 14 and 14u and is replaced by a spare blade holder which contains a new blank and is Xed in place by re-tightening the screws or bolts 14 and 14. This replacement of the blade holder is to be effected during the period of the return of the carriage 3 toward its left end positionunder action of the cam 40 which is driven at so low a speed as will afford the time required for such replacement.

'In Fig. 5 we have diagrammatically illustrated the successive stages ofthe operation.

-In this iigure the reference numeral 8 designates the grinding disc and I to V designate live successive positions of the grinding disc assumed in the course from its outermost position I to its innermost position V in which the advance is ,completed ,and another cycle 'of operation is started. 23/illustrates a razor blade, the finished profile of which is confined by the corner points-A, N, L, D, E while the original form of the blank as it is inserted in the blade holder, is indicated by the point-s A, B, C, D, E. It will be observed that the blank is formed by a blade having a finished back C, D, E, and an unfinished front A, B which is to be ground to produce the front'face N, L of the edge. 29 is ,the supporting cylinder, the peripheral face of which serves to support the rear face of the edge and, for this purpose, is kept in intimate Contact therewith and stationary thereto during the grindin process.

As heretofore mentioned, the supporting cylinder is provided with a peripheral recess extending between the points K, L, Fig. 5. This recess is increased in vcircumferential length vin the course of the operation on account of the stepwise turn imparted to thc support 29. Its` original shape is desigv until the edge L was situated in the central plane l? of the razor blade so that a portion K, I, O, K was cut out of the cylinder. When' subsequently to each cycle the supporting cylinder is turned through the angle y a, the recess K, L is successively enlarged as each time another section G, I-I, L is cut out of the circumference until eventually the entire cylinder is'used up and a new cylinder of the prescribed diameter must be substituted. The depth QR of penetration of the grinding disc 8 depends on the edge angle i 2 a of the razor blade which is to be produced. The larger this angle is to be made, the lower arranged must be the blade 23 with regard to the line S, T connecting the centers of the supporting cylinder 29 and grinding disc 8, and the 'more towards the right will be positioned the blade so that the grinding disc will deeper cut into the supporting cylinder 29 until the razor blade edge is situated in the central plane P.

When the grinding disc 8 approaches the positlon I on itswaytoward'the'supporting cylinder 29 a blank having its front in unfinished condition has been substituted for Y the/razor blade inished in the preceeding cycle. 'As soon as the position II has been reached the grindingv process proper commences, the edge B of the blade being progressively cut away until the position III has been reached where the portion designated by the letters B, F, G, has been ground off.'

' on account of small di erences in shape, the

^ razor blade gradually approaches t cross-sectional profile with the points C and D on different sidesof the lcentral plane has been chosen.

While the grinding disc advances from as pjosition III to the position'IV, the portion F, M, G is cut away so that the edeofthe G. where it arrives at the time IV. During this period, however, the edge C freely extends through the space its back lacking any support whatsoever, so that a ridge of the width C, G will be formed. This ridge represents the rim leaf which yields un Ver the pressureof the grinding'dise and is bent out of the way of the latter on account of its reduced thickness and' tenderness.` In the moment, however, position IV is reached, the grinding disc beginsA to operate upon a marginal zone conned by the edge G of the razor blade which is supported by portion G, C D of the supporting cylinder 29 and, for t is reason, cannot yield to the grinding ressure. Consequently, the advancing grin ing disc engages fthe root of the ridge leaf'which is' bearing against the supporting cylinder 29 and as a result of the frictional engagement with the grinding disc is abruptly torn off.

While the grinding disc advances from IV to V it exerts a unitary grinding action on the supporting cylinder and the` razor blade simultaneously cuttinglaway the portions G,

M, N, L of the blade and G, H, L, of the supporting cylinder. In the course of this stage ofthe grinding rocess the edge gradually advances from y to L and, in this phase, another ridge cannot be formed because the edge is continually supported while it is subjected to the Igrinding pressure. LHence, it will appear that as soon as, or even before, the point L is reached, the edge will be perfectly sharp and free from any ridge so that any subsequent treatmentof the razor blade with a view to removing a ridge is rendered superfluous.

The faces NL and LD are truly concave in the immediate proximity of the edge and are thereby distinguished` from the razor blades produced by known methods in which the edge is deformed by bending stresses and subjected to a polishing treatment which removes V material near the edge and thereby distorts `thelground concave face transforming it in 4theimmediate proximity of the edgeinto a Y c p v of heat or by mechanical stresses exerted by the polishing tool.

It might be suggested that it would appear sufficient to' turn the supporting cylinder 29, preparatory to the grindin phase, with the edge of its recess up to 51e point L only rather than up to the point G inasmuch asl the ridgelis removed in the moment the contact of the supporting cylinder and the grinding disc occurs, which' occurrence miglht just y as well be ostponed until the ed e as advanced to In this case a simp e support having the form of a simple plate of the profilev U, V, L, W, Y would do as this plate would not be consumed and, for this reason, would not necessitate anyl replacement. It is to be observed, however, that in this case the operation would be finished in the moment the ridge leaf is torn away. This tearing pif,

however, always occasions small irregularities and 'recesses on the edge so thatthe `latter does not comply with the requirements of. e uttermost exactitude and does not satisfy the demands for a perfect razor blade.

Besides, the unavoidable wear ofthe grinding disc accounts for a certain irregularity of the final position of the razor blade ed` e which, accordingly, does not always exact y coincide with point L of the supporting cylinder. It follows that, while a perfect grinding disc could perhaps be adjusted to always exactly reach the position V .thereby removing the rid e even with a simple support plate U, V, W, Y, under ordinary conditions,'for instance with a worn grinding disc, the position V would sometimes not exactly be reached so that a ridge leaf would be left. For this reason we advance the grinding disc beyond the position IV thereby cutting into the support-29. This operation compensates for the unavoidable small deviations in the reasonable requirements regarding the exactness of the elements of the machine, to provide, as it were, a safety coeiicient with regard to the supporting action, in that we support the rear face of the edge beyond the point L markin the final location of the finished cutting e ge, and in that we artially cut away'thls sulpported Zone toget er with its support wh' el the grinding disc,v appreaches its innermost position. VThe'portion of the support cut away in each cycle must, of

course, be replaced preparatory to the sitbsequent cycle. -l f By the machine heretofore described a cutting edge is obtained which is sharp and without any ridge, regardless of whether or not the elements of the machine operate quite accurately and whether the final edge exactly coincides with the point L in the central plane P.

Obviously, the requirement of replacing the cut-away portion ofthe support prior to every cycle may be complied with in a great variety of constructions. We prefer, however, to use `a supporting cylinder such as heretofore described as in this manner the replacement after each cycle may be accomplished in an extremely simple manner by turning the cylinder until its edge confining the recess has been moved beyond the location of the iinal blade edge by such an amount as safety compensates for the eiects of possible inaccuracies of the machine.

ln producing the rear :tace C, D of the razor blade a similar method of supporting the back of the blade need not be employed, it being suiiicienta to support the original blank having the profile A, B, Z, E by a small support blade Z, A', B', C', as in this case the configuration of the edge D is without any' consequence so that the formation of a ridge does not matter. The function of the sup-` port in this case would simply be to prevent the blade which is given the profile ANDZE from being sprungr out of shape. It may be mentioned that this preparatory stage does notv form part of our invention and that the proiile ANDZE may be produced in any suitable manner before the blade is sharpened with our novel machine.

An essential requirement for the eicient operation of our machine is an intimate contact of the supporting cylinder .with the rear face of the blade edge or at least with the zone confined by the inal edge. In order to avoid unreasonable requirements regarding the accuracy of the adjustment of the blade holder, the latter is preferably of yielding properties. In the embodiment shown for instance, it includes in its structure a spring leaf` 20 permitting 4a small lexion vertical to its plane as well as a small turn about its vertical axis.

ln adjusting the blade, we first align the blade edge inthe desired level parallel to the axis of the supnortingcylinder and, subsequently. somewhat release one of the pointed screws 15 or 16, whereupon we turn the en- -tire blade holder about the axis 15. 16 to bring the blade in full contact .with the supporting cylinder. Then, the released pointed screw is tightened again so as lto arrest the sure while the spring leaf 20 is slightly bent.

to produce such pressure. This will also be the case, ifblades of a slightly diierentsize are inserted as the iexibility of the spring leaf 20 compensates for small dierences between the shape .of the individual blades. The blade holder, however,. will be subject to small deviations from its vertical position.

If it stands forwardly inclined with regard to v its normal position, the pointl D of the rear face is. liable to come intol contact with the periphery of the supportin cylinder instead of the point G so that the nal edge would not be supported. This may obviously be avoided by dimensioning the radius of the supporting cylinder slightly smaller than the radius of the curvature of the porfile section C, E or,

in other words, thanthe radius of the grinding disc employed in producing the rear face of the blade. In this manner, of course, a perfect contact over the entire surface of the rear face C, D is obviated, buty an ecient support of that zone is secured in which the final edge is situated and this is what counts; In dimensioning the diameter of the supporting cylinder unavoidable inaccuracies and differences of the individual blades are to be taken in consideration. The diameter must which would permit of such a rotation unless particular precautins were'taken. Any turn of the supporting cylinder during its engagement with -the grinding disc, however, would cause the latter to jam or perhaps even to crack. For this reason, means must be provided which obviate a back-lash in the driving gear of the supporting cylinder. This `may be achieved in the simplest manner by causing the driving members to be in permanent contact with'each -other in a sense contrary to their driving effect. For this purpose we have provided the weight 36 which subjects shaft 28 to a torque of the same sense as that produced by the engaging grinding disk. This torque causes the teeth of the worm gear 33 to keep contact with the thread of the self-locking worm 34 whereby the supporting cylinder is prevented from being turned by the grinding disc. It follows that the advance ,of the supporting cylinder through the anglesla is, exactly speaking, performed by action. of the weight 36 rather than by the worm gear 34, 33 which really merely determines the exact degree of such advance.

What we claim is:

1. A blade sharpening machine comprising 4 a grinding element, a support, a blade holder viat of said: support lis. ground off in the course of to keep a blade therebetween in grinding position and in contact with said support, the latter being adapted Ito be kept stationary during the grinding cycle and to be advanced between successive cycles in the direction of its supporting face whereby successive portions of its surfacepmay be brought into contact relation to said blade for successive cycles of operation.

2. In a blade sharpening machine, the combination comprising a bladesupport, a rotating grinding wheel, means to move the Wheel towards said support to such an extent that a portion of the vsupport is ground away, and a blade holder associated with said support to keep a blade stationary relative to said support and in intimate contact with the portion cut away,.while the blade is being ground.

3.- In a blade sharpening machine, the combination comprising a blade support, a rotating grinding wheel, means to reciprocate said wheel to and from said blade support, means associated with the support to advance the support step by step into the path `of saidgrinding wheel in slynchronism with the reciprocation of theisame, whereby a portion e'aehstroke vjofsaid grinding Wheel, and a blade holder adapted to keep a blade stationary relative to said support and with its rear marginal zone in intimate contact withsaid portion for the purpose of subjecting its front to the action of said grinding wheel' while its edge is supported by4 said portion. 4. A blade sharpening machine comprising a frame, a carriage slidably arranged thereon, a rotating grinding disc mounted on said carriage and having its axis transverse to the direction of movement of said carriage, a blade-supporting cylinder mounted You said frame in opposition to said grinding disc and having its axis parallel to the axis of said disc, means to reciprocate said carriage to cause said grinding ldisc to cut into said cylinder, and a blade holder arranged between said disc and said cylinder and adapted to keep a blade in upright position with its mar-v ginal portion in contact with said cylinder and in the path of said disc.

5. A blade sliarpening machine comprising a frame, a carriage slidably arrangedthereon, a rotating grinding disc mounted on said carriage and having its axis transverse to the path of said carriage, a blade-supporting cylinder mounted on said frame in opposition to said grinding disc and having itaxis parallel to the axis of said disc, means to reciprocate said carriage to cause said grinding disc to cut into said cylinder, means to turn said cylinder about its axis through a definite angle, once at each reciprocation of said carriage, and a blade holder arranged betweensaid disc and said cylinder and adapted to keep a blade in upright position with its marginal portion in contact with said cylinder and in the path of said disc.'

6. The combination set forth in claim 4, in which said blade holder comprises an upright spring leaf and al clamping device attachedto movement being suiiicient for said grinding wlieel to cut into said portion while sharpening the supported edge of the blade, means to mount said support for a movement which will bring another portion of it into contacting relation with a blade after said firstmentioned portion. has been ground off, and

l0 the upper end thereof and adapted to receive means for maintaining said support in posiv tion relative to said grinding wheel against the grinding pressure exerted by thelatter.

. 8. In a blade Ysharpening machine, the combination comprising blade supporting means ofnon-resilient and non-abrasive material, a rotating grinding wheel, means for reciprocating said wheel in the direction to and from said supporting means, means asso- *ciated with said supporting means for intermittently advancing said supporting means into the path of' said grinding wheel in synchronism with the reciprocation of the same, whereby a portion of said supporting means will be ground o in the course of each forward stroke of said grinding wheel, and a lblade holder adapted to keep a blade stationary relative' to said support and with its one marginal face in intimate contact with said portion for the purpose of subjecting its other marginal face to the action of said grinding wheel while the very edge of the blade is supported by said portion.

9.- A blade sharpening machine comprising a,frame,-a carriage slidably arranged thereon, a rotating grinding disc mounted on said carriage and having its axis. horizontal and transverse to said carriage, a

blade' supporting body of non-abrasive and non-resilient material'mounted on said frame 1n opposition to said grinding disc, means to reciprocate said carriage to cause saidgrinding disc to cut into said body, and a vblade holder arrangedbetween said disc and said body and adapted to keep a blade inA upright position with its marginal portion in contact with said body and in the path of saiddisc to be ground off simultaneously with -said body.

10. In -a blade sharpening.` machine, the

combination comprising a non-resilient and non-.abraslve support having a rectilinear portion dlmensloned to support the marginal face of a. razor blade along its entire edge, a bladeholder associated therewith to keep a blade stationary relative to, and in intimate Contact with said portion of the support, agrnding wheel and means to move said wheel towardssaid support and said blade such a distance that contacting portions of the blade and said support are snlultaneously ground away.

In testimony whereof we alix our signatures.

MAX MAAG. ROBERT SALOMON.

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