US2729921A - Automatic file-sharpening machine - Google Patents

Description

Jan. 10, 1956 R. L. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 1 4G INVENTOR, eosser 4. 004 x fir 0.6?

Jan. 10, 1956 R. L. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 2 IN VEN TOR, 805597 L. 09V

BY fi a aria/Quays Jan. 10, 1956 R. DAY 2,729,921

AUTOMATIC FILE-SHARPENING MACHINE Filed May 17, 1954 3 Sheets-Sheet 3 Is I INVENTOR BOBEQT 4. 05W

I? arraeusys' United States Patent AUTOMATIC FILE-SHARPENWG MACHINE Robert L. Day, Sun Valley, Califl, assignor of one-half to Harry L. Williams, Los Angeles, Calif.

Application May 17, 1954, Serial No. 430,305

9 Claims. (Cl. 51--96) This invention relates to improved automatic filesharpening machinery. A feature of this invention is the provision of machinery for sharpening files having arcuate teeth.

Another feature of this invention is the provision of novel machinery for automatically sharpening files having curved teeth.

Still another feature of the invention is the provision of a new and useful machine for automatically sharpening a file having curved teeth.

These and other features of the invention are provided by a machine wherein a file to be sharpened is held on a file-holding platform. This platform is given an oscillatory motion about a pivotal point. A grinding wheel is positioned at a distance from the pivotal point substantially equal to the radius of the curved teeth of the file to 9 be sharpened. Means are provided for lowering the grinding wheel onto one of the teeth of the file and for subsequently continuously lowering the grinding wheel to compensate for wear. Means are also provided for advancing the file to present a succeeding tooth to be sharpened to the grinding wheel each time the oscillating plat form attains one of its extremes of oscillation.

The novel features that are considered characteristic of this invention are set forth with particularity in the embodiment of the present invention;

Figure 2 shows the manner in which a file is passed under the grinding wheel by the oscillating motion of the file-holding platform;

Figure 3 shows the relative operative grinding wheel and a file;

Figure 4 is a section taken on line 4-4 of Figure 1, showing the details of the file-holding platform;

Figure 5 is a section through the file-holding platform taken on line 5-5 of Figure 1;

Figure 6 shows in perspective the details of the file holder employed in the embodiment of the invention;

Figure 7 is a section through the mounting of the file holder taken on the line '7-7 of Figure 5;

Figure 8 shows in perspective details of a file support which supports the part of the file under the grinding wheel;

Figure 9 shows details of the mechanism as seen in Figpositions of a ures 1 and 4 for lowering the grinding wheel upon the file continually;

Figure 10 shows a file having file teeth whose axis of concentricity is not on the longitudinal axis extending through the file;

Figure 11 shows how a file may beshifted to a position for sharpening which compensates for such lack in concentricity;

Figure 12 shows a cross-section through the file-holding platform, the location of which section is on line 12-12 in Figure 14;

Figure 13 is a sectional view of the file holder and the surrounding structure taken on the line 13--13 of Figure 12;

Figure 14 is another sectional view through the fileholding platform taken on the line 14--14 of Figure 12;

Figure 15 is another section to show the mechanism for supporting and holding a file, which section is taken on the line 1515 of Figure 12;

Figure 16 shows the advancing bar used for successively advancing the file teeth under the grinding wheel;

Figure 17 shows a guide bar which helps to guide a file under the grinding wheel; and

Figure 18 shows the guide bar plate through the groove of which the file is guided to be pushed. under the grindin g wheel.

Figure 1 is a drawing of an embodiment of my invention consisting of a supporting post 10 upon which there is adjustably clamped a base platform 12. As may be better seen in Figure 4, a file-holding platform 14 is supported on this base pivotally. A motor 16 is also supported from this base. This motor has a belt 18 which drives a wheel 20 which, in turn, drives a crank arm 22 which is connected by a link 23 to one side of the pivotally supported file-holding platform. Accordingly, when the motor is driven, the file-holding platform 14 will oscillate about its pivotal support 24. A grinding wheel 26 and an associated driving motor 23 are supported on opposite ends of a yoke 30 which is pivotally suspended from the post or column 10. The yoke size is such that the grinding wheel 26 is supported over the file-holding platform 14 when it is in its central position. The weight of the electric motor 23 tends to pivot the yoke so that the grinding wheel 26 is urged upwards. However, a flat member 32 is slidingly mounted on the column. It has a locknut 34 attached to one side and an adjustable screw 36 attached to the other. The adjustable screw 36 is used to bear down on the side of the yoke 30 on which the grinding wheel 26 is attached. The sliding fiat member 32 is supported by means of a screw member 38 which extends threadably through the locknut 34 and through a threaded collar 40 which is rotatably supported from the base platform 12. This can be seen better from Figures 4 and 9. The collar has a ratchet ring 42 around it. It will be appreciated that as the screw member 38 is pushed upward or downward by turning the collar 40 the adjustable screw 36 bears down or lets up on the side of the yoke on which the grinding wheel is mounted. Thus the grinding wheel position may be ad justed to be in position upon the tooth 46 of a file 44 mounted on the file-holding platform, as may be more readily seen from Figure 3.

The file-holding platform 14 is oscillated by driving the motor 16 supported from the base platform, the motor 28 supported from the yoke is driven, and, through the associated drive belt, drives the grinding wheel. The oscillating file-holding platform passes a file toothe under the grinding wheel by describing an arc in the manner illustrated in Figure 2. The grinding wheel is positioned at a distance from the pivotal mounting: of the file-holding platform substantially equal to the radius of curvature of a file tooth.

Means are provided for gradually lowering the grinding wheel in order to compensate for the reduction in diameter occasioned by the wear. This may be seen by regarding Figures 1, 4, and 9. As previously stated, the collar 40 which is rotatably mounted upon the base platform 12 has a ratchet ring 42 mounted around its outside. A pawl member 48 is spring biased to be in tender with the ratchet ring. A pawl driving rod 50 is movably supported and is attached at one end to the pawl member. A spring 52 is employed to bias the rod. The other end of the rod is pushed by the oscillating file-holding platform when it reaches one extreme of oscillation. The spring then returns the rod to its initial position. It will be appreciated, therefore-, that when the file-holding platform pushes the rod it also actuates the pawl and ratchet to rotate the collar a given amount. This causes the screw member 38 to move downward. The flat member is also moved downward, causing the grinding wheel to be moved downward a desired amount.

A file holder mechanism is provided for holding the file upon the file-supporting platform under the grinding wheel. Figure 4 shows this file holder in plan and Figure 6 in perspective. It consists of two parallel members 60, 62 and two parallel crossbar members 64, 66

which serve to pivotally support the two parallel mem bers in parallel. The inner surfaces of the two parallel members are brought to a somewhat narrow 'or knife edge 68 in order to support and hold the file inserted :therebetween' againstsidewise motion and yet permit motion longitudinally with a minimum of friction. The two grossbar members are supported by two posts 70, 72. ,The posts are pivotally supported in two fiat bearing members 71, 73 which, in turn, are supported on a file holder base ;member 75. Figure 7 shows the'det'ail of the support by the bearing member. From one of the posts 70, a spring 'biasyis applied by a spring 74 to one of the crossbar members 64 in order to bring the two parallel members 60, 62 together. In order to spread the paral lel members, a key (not shown) may be inserted through the square opening provided in a rotating member 76 which is turned in a direction against the spring bias to engage. a projection 78 on the under side of one of the parallel members 62 to thus open or spread the two parallel members. This may be more readily seen in Figure 5.

Underneath the portion of a file under the grinding wheel which is clamped by the file holder there is provided aspring-biased file support. This serves to support the file against the downward thrust of the grinding wheel. Figure 8 is a perspective view of this platform.

Sectional views may be seen in Figures 12 and 14. Referring now to Figure 8, the file support includes a lower flat member 80 and an upper fiat member 82. The upper flat member bears against the lower surface of the file held in the file holder. It is rotatably supported along its longitudinal axis above the central portion of the lowermember by two hinge members 84, 86 which are attached to the lower fiat member. Four stops 88 are provided (only two of which may be seen) on the under side of the upper flat member which limit the 1 amount of rotation to a desired amount. The lower flat member is alsorotatably supported on one side by two hinge members 90, 92. These are fastened to a wall of the file-holding platform, as may be seen in Figure 15. The other side of the lower fiat member is supported by a spring 94 (shown in Figures 14 and 15). This spring pushes upward against the lower fiat member from a plate 96 which rests on the file-holding platform 14. The height of the spring-biased side of the lower flat member, and thereby the force with which the file is urged against the grinding wheel, is adjusted by an adjustable screw 08 which has a lever arm 100 at one end andis threaded through the lower platform extending through the spring 24 into the fiat member 96. The end extending into the ast inefnher is held there, permitting the screw 98 to [he uraa but not withdrawn. Thus by turning the lever arm the one end of the lower flat member can be lowie d or raised. This changes the spring bias and the upwaidforc'e of the upper member against a tile. It will be appreciated that this arrangement permits the springbiased file support to be self leveling and to compensate for variations in height or wear of file teeth being ground.

Figure 10 shows a portion of a file wherein the axis of concentricity 102 of the file teeth does not fall on the longitudinal axis 104 of the file. Since the file-holding platform is oscillated in an are which has the same center as the file teeth, it will be appreciated that when there is lack of concentricity the grinding wheel will not sharpen all of a file tooth. However, if a file, having such lack of concentricity, is shifted or turned in a manner shown in Figure 11, the file tooth 106 will be completely sharpened since its arc is made to coincide with the are through which the platformtravels under the grinding wheel. This requires that the file be permitted to rotate slightly as it passes under the grinding wheel. This is achieved by mounting the file holder base member 75 on a bearing 106 (see Figure 12). The bearing is positioned right under the grinding wheel. This permits the file to be rotated to compensate for the lackofconcentricity. The degree of such rotation is limited by the supporting wall structure 107, 108 on the file-holding platform. I

In order to achieve automatic operation, the teeth of a file must be successively advanced under the grinding wheel. A plate 110 having a groove 112 (shown in Figure 18) is mounted over a file to be sharpened, as may be seen from Figure 18. Two guide blocks 114, such as are shown in Figure 17, are used with the plate 110; one is mounted on either side of the groove in the positions indicated by the holes. The actual advancement of the file teeth is performed by the teeth-advancing block shown in Figure '16, having a teeth-engaging member 116 and a roller-engaging member 118. The end of the teeth-engaging member is shaped to conform to the curve of the file teeth and is pointed so that it can readily slip behind the ridge of a tooth, as can be seen in Figure 12. The teethengaging member and roller-engaging member have a pivotal joint 120 at their lower ends and have a spring 122 biasing them apart at their upper ends. Thus, since as shown in Figure 12 the teeth-advancing block has its roller-engaging member sliding in the groove 112 over the file, the teeth-engaging member is urged pivotally downward by the spring 122 to engage a tooth for advancement. The roller-engaging member has an arcuate back portion 124 which crosses it to form a T. A projecting member 126 is mounted on the arcuate portion. It has a hole therein to receive a stop screw 128. The stop screw is adjusted to limit the amount of backward travel given to the teeth-advancing block by two'springs 130 which are positioned between the guide blocks 114 and the T extensions of the arcuate back portion 124 (see Figures 5 and 12). V

Referring now to Figures 1 and 4, the reason for the back structure of the teeth-advancing block will be seen. Two roller members are mounted on the base platform 12 at a height equal to that of the arcuate back portion.

Each time the file-holdingplatform approaches an extreme of its oscillation, the teeth-advancing block is urged inwardly by a roller. In being urged inwardly, it moves forward and carries therewith the file. The distance it moves may be adjusted by adjusting the position of the roller. As shown in Figure 4, means are provided consisting of an adjusting screw 136 and a threaded ring 138 for properly positioning the roller to enable the movement of the file only one tooth distance. The spring 140 holds the roller arm tight against the adjusting screw. The arcuate back portion is shaped to engage the rollers.

Accordingly, in operation, the file is mounted by opening the file holder and depositing the file therein with the first tooth under the grinding wheel and then locking the file holder. Adjustments are made so that on each extreme of oscillation the file advances only one tooth. This can be done'by adjusting the positions of the two roller wheels 132, 134 with the adjusting screws 136 and the stop screw 128 in the tooth-advancing mechanism. The grinding wheel is then lowered and the automatic filesharpening mechanism is then started. The platform oscillates and the file is progressively advanced past the grinding wheel until every tooth has been sharpened. The file is then removed, turned over and replaced, and the file teeth are then automatically sharpened on that side.

The grinding wheel and its associated driving mechanism and a file can become hot during a grinding operation. Any of the well known arrangements for air cooling or spraying of a liquid coolant may be employed in order to keep the apparatus cool.

Accordingly, there has been described and shown herein a novel and useful mechanism for automatically sharpening file teeth.

I claim:

1. Apparatus for sharpening files having curved teeth comprising a supporting column, a base platform supported from said column, a file-supporting platform pivotally mounted on said base platform, means to hold a file on said platform, means to adjustably support a grinding wheel from said column over said means to hold a file with its grinding edge at a distance from said pivotal mounting of said file-supporting platform substantially equal to the radius of curvature of a file tooth, means to oscillate said file-supporting platform. about its pivotal mounting to pass a file tooth under said grinding wheel, means actuated when said file-supporting platform is at one extreme of its travel to lower said grinding wheel a sufiicient distance to compensate for reduction in diameter caused by wear, and means actuated at each extreme of oscillation of said file-supporting platform to advance a succeeding file tooth under said grinding wheel.

2. Apparatus as recited in claim 1 wherein said means to hold a file on said platform includes a spring-biased means to hold a file by the edges, a spring-biased means to urge said file upwards toward said grinding Wheel, means to pivotally support said spring-biased means to urge said means to hold a file by the edges upwards at a point underneath said grinding wheel, and means to limit the amount of said so-supported means is permitted to pivot.

3. Apparatus as recited in claim 2 wherein said springbiased means to hold a file by the edges includes a first pair of parallel bars, between which a file is placed, a pair of parallel crossbars, means to pivotally support each of said first pair of parallel bars on each of said pair of parallel crossbars to always maintain said first pair of bars parallel and said pair of crossbars parallel, means to apply a spring bias to one of said crossbars to urge said first pair of parallel bars together.

4. Apparatus as recited in claim 1 wherein said means to adjustably support a grinding wheel from said column includes a yoke pivotally attached to said column, means to support said grinding wheel from one end of said yoke, and means attached to the other end of said yoke to pivot said grinding wheel away from said file-supporting platform, and said means actuated when said file-supporting platform is at one extreme of its travel to lower said grinding wheel a sulficient distance to compensate for reduction due to wear includes a flat member slidably attached to said column above said yoke, a locknut attached to one side of said flat member, an adjustable screw threaded through the other side of said flat member to adjustably contact said pivotally attached yoke on the grinding wheel side of its pivotal attachment, a collar having its interior threaded and ratchet teeth mounted on its exterior, means to rotatably support said collar on said base platform with said collar opening aligned with said locknut opening, an opening in said base platform underneath said collar opening, a screw threaded through said locknut and said collar and extending through said opening whereby said flat member is adjustably supported above said yoke, a pawl, means supporting said pawl at a position to be moved when said file-supporting platform reaches one extremity of its oscillation to engage 'and'rotate said collar by its ratchet teeth whereby said screw, said flat member and its adjustable screw are lowered to lower said grinding wheel an amount to compensate for its reduction in diameter due to wear.

5. Apparatus as recited in claim 1 wherein said means to advance a succeeding file tooth under said grinding wheel includes a roller-engaging member slidably supported over the position of a file on said file-supporting platform, means to yieldably bias said member to a given position over said file position, a first and a second roller, means supporting said first and second rollers at positions on said base platform on either side of said file-supporting platform to engage and move said block from said given position when said file-supporting platform approaches either extreme of oscillation, a tooth-engaging member having one end adapted to engage a file tooth, means pivotally supporting the other end of said toothengaging member at the lower end of said slidably supported roller-engaging member and means to yieldably bias said one end of said tooth-engaging member downwards towards a file.

6. Apparatus for sharpening files having curved teeth comprising a supporting column, a base platform supported from said column, a file-supportingplatform pivotally mounted on said base platform, means to oscillate said file-supporting platform about its pivot, a file holder including a first pair of parallel bars between which a file is placed, a pair of parallel crossbars, means to pivotally support each of said first pair of parallel bars on each of said pair of parallel crossbars to always maintain said first pair of bars parallel and said pair of crossbars parallel, and means to apply a spring bias to one of said crossbars to urge said first pair of parallel bars together, means to mount said file holder on said file-hold ing platform, means to pivotally support said file holder on said file-holding platform, means to limit the amount said file holder is permitted to pivot, and means to adjustably support a grinding Wheel from said column over said file holder at a distance from said file-holding platform pivotal mounting substantially equal to the radius of curvature of a file tooth.

7. Apparatus for sharpening files having curved teeth comprising a supporting column, a base platform supported from said column, a file-holding platform pivotally mounted on said base platform, means to oscillate said file-holding platform about its pivot, a file holder including a first pair of parallel bars between which a file is place, a pair of parallel crossbars, means to pivotally support each of said first pair of parallel bars on each of said pair of parallel crossbars to always maintain said first pair of bars parallel and said pair of crossbars parallel, and means to apply a spring bias to one of said crossbars to urge said first pair of parallel bars together, means to yieldably bias upwards a file held in said file holder, means to pivotally support said file holder on said file-holding platform, means to limit the amount said file-holding frame is permitted to pivot, a yoke pivotally attached to said column, a grinding wheel, means to support said grinding wheel from one end of said yoke over a file on said file-holding platform, means attached to the other end of said yoke to pivot said grinding wheel away from said file-supporting platform, means actuated when said file-supporting platform is at one extreme of its travel to lower said grinding wheel a sufficient distance to compensate for reduction due to wear including a fiat member slidably attached to said column above said yoke, a locknut attached to one side of said flat member, an adjustable screw threaded through the other side of said fiat member to adjustably contact said pivotally attached yoke on the grinding wheel side of its pivotal attachment, a collar having its interior threaded and ratchet teeth mounted on its exterior, means to rotatably support said collar on said base platform with said collar opening aligned with said locknut opening, an opening in said base platform underneath said collar opening, a screw threaded through said locknut and said collar and extending through said opening whereby said flat memher is adjustably supported above said yoke, a pawl,- means supporting said pawl at a position to be moved when said file-supporting platform reaches one extremity of its oscillation to engage and rotate said collar by its ratchet teeth whereby said screw, said flat member and its adjustable screw are lowered to lower said grinding wheel an amount to compensate for its reduction in diameter due to Wear.

'8. Apparatus for sharpening files having curved teeth comprising a supporting column, a base platform supported from said column, a file-supporting platform pivotally mounted on said base platform, means to oscillate said file-supporting platform about its pivot, 21 file holder including a first pair of parallel bars between which a file is placed, a pair of parallel crossbars, means to pivotally support each of said first pair of parallel bars on each of said pair of parallel crossbars to always maintain said first pair of bars parallel and said pair of crossbars parallel, means to apply a spring bias to one of said crossbars to urge said first pair of parallel bars together, means to yieldably bias a file in said frame upwards, means to pivotally support said file holder on said file-supporting platform, means to limit the amount said file holder is permitted to pivot, means actuated at each extreme of oscillation of said file-supportingv platform to advance a succeeding file tooth under said grinding wheel including a roller-en aging member slidably supported over the position of a file on said file-supporting platform, means means supporting said first and second rollers at positions on said base platform on either side of said filesupporting platform to engage and move said rollererigaging member from said given position when said filesupporting platform approaches either extreme of osc'il lation, a tooth-engaging member having one end adapted to engage a file tooth, means pivotally supporting the other end of said tooth-engaging member at the lower end of said roller-engaging member and means to yieldably bias said one end of said tooth-engaging member downwards towards a file.

9. An automatic file-sharpening machine for files with curved teeth including a file-supporting platform, means to hold a file on said platform,- means to position a grinding wheel with its grinding edge in contact with the teeth of a file clamped on said platform said means including means to automatically lower said grinding wheel to compensate for reduction in diameter occasioned by wear, means to move said platform and said wheel in a relative oscillatory motion to pass substantially an entire file tooth under said grinding wheel, and means to move, said file to bring a succeeding file tooth under said wheel for sharpening after said Wheel has passed over a file tooth.

References Cited in the file of this patent UNITED STATES PATENTS 1,131,999 Denley et al. Mar. 16, 1915 1,777,135 Bailey Sept. 30, 1 930 2,212,999 Faulder Q. Aug. 27, 1940 2,222,034 Jackson Nov. 19, 194() 2,375,703 Swartzwelder May 8, 1945 FOREIGN PATENTS 35,361 Switzerland Jan. 5, 1906 131,637 Switzerland Feb. 28, 1929

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