US2751723A - Lapper for carbide tipped tools - Google Patents

Description

june 26, 3956 K. LINDMARK LAPPER FOR CARBIDE TIPPED TOOLS 3 Sheets-Sheet 1 Filed Feb. 6, 1953 12% KezvZ L. L z'z zdzzzaz" 31109 1956 K. L. LINDMARK LAPPER FOR CARBIDE TIPPED TOOLS 3 Sheets-Sheet 3 Filed Feb. 6, 1953 IIHI I HUIHHTIHI IIII km 9w United States Fatent LAPPER FGR CARBIDE TIPPED TOOLS Karl L. Lindmark, Loves Park, 111., assignor, by mesne assignments, to Feniind Engineering Co., Loves Park, 111., a corporation of Illinois Application February 6, 1953, Serial No. 335,459

7 Claims. (Cl. 51-135) This application relates to improvements upon the dis closure of my copending application, Serial No. 318,360, filed November 3, 1952, which resulted in Patent No. 2,663,978, issued December 29, 1953.

This invention relates to a machine for lapping carbide tipped tools, said machine incorporating a wheel of medium large diameter having a wide fiat rim with a smooth true periphery which serves as a precision supporting pulley for an endless belt of abrasive material that is kept evenly tensioned and running true while driven by means of a smaller motor driven pulley, the wheel and belt thereby cooperating to provide an endless unyielding precision lapping surface to a lap or polish on the arcuate contour of the Wheel to obtain a micro-finish on the tip of a cemented carbide tool bit accurately to a predetermined angle determined 'by the setting of a horizontal tool support at a predetermined elevation with respect to the working face of the wheel.

The principal object of my invention is to facilitate the operation of this machine by the provision of a direct reading height gauge for use in combination with the height adjustment in connection with the slide that serves as an adjustable tool support, this height adjustment, in accordance with the present invention, being operable in either of two ways, depending upon the closeness of accuracy desired and upon how much or how little time the operator is prepared to spend in making said adjustment. The more accurate method, which takes more time, involves setting the micrometer adjustment according to a table of measurements showing the height adjustment for a pillar that carries the tool supporting slide, there being in this table of measurements one for each angle of lap calculated to three decimal places according to the tool height measured from the slide. The other method, which is accurate enough for most purposes and means a big saving in time for the operator, involves setting the micrometer adjustment according to the novel direct reading height gauge, the tool bit being placed on the slide and extended therefrom into close proximity to the vertical gauge post on the flat face of which are graduations in vertically spaced relation, each graduation representing one specific angle in a range from 1 to so that the operator need only raise or lower the slide to the point where the tip of the tool bit registers with the appropriate graduation line. In the event a setting of closer accuracy is desired, the operator can by reference to the table of measurements ascertain the exact reading that should appear on the micrometer for the given tool height and the angle desired and then make a fine adjustment one way or the other to get that exact reading. The direct reading gauge is preferably provided on the outer end of an arm pivoted on a vertical axis on the frame to swing in a horizontal plane from a retracted position parallel to and spaced from the front of the tool supporting slide to an operative position at right angles to said slide Where the gauge is disposed in close enough proximity to the frQnt of. the slide to enice able accurate setting of the micrometer adjustment using said gauge in the manner described.

The invention is illustrated in the accompanying drawings, in Which- Fig. l is a top view and Fig. 2 is a side view of a lapping machine incorporating the direct reading height gauge made in accordance with my invention;

Fig. 3 is a geometrical diagram showing how the dif ferent angles of micro-finishes are obtainable by different heights of adjustments for the tool support pillar in relation to the wheel;

Fig. 4 is a table of height adjustments for the tool support pillar calculated for each of a series of angles in relation to tool heights measured from the tool support slide;

Fig. 5 is an enlargement of a portion of Fig. 2 to better illustrate the direct reading gauge, which appears in side elevation, and

Fig. 6 is a front view of Fig. 5.

The same reference numerals are applied to corresponding parts in these six views.

Referring to the drawings, the machine illustrated in Figs. 1 and 2 is like that disclosed and claimed in the copending application and the reference numeral 10 designates a table forming a part of the frame of the machine supported on legs 11 at a convenient elevation with respect to the floor. A base plate 12 for support of the electric motor 13 and drive pulley 14 fixed to the armature shaft 15 of the motor is supported on the flat top surface 16 of the table 10 for oscillation relative to a pivot pin 17 fixed to the table 10 and received in a hole 13 in the plate, whereby to permit oscillation of the pulley 14 about a vertical axis ab that extends through the axis of the armature shaft 15 at the middle of the pulley 14. This is to enable making the abrasive belt 19 that runs on the pulley 14 and the wheel 20 as a driven pulley track properly and run absolutely true, that is, without any perceptible wabble. A screw-thread adjustment is provided which enables fine adjustment of plate 12 in either direction, the adjusting means including a rod 21 supported for rotation and against endwise movement in a bearing 22 fixed with respect to the top of the table 10. A handwheel 23 is attached to the projecting end of the rod 21 adjacent the bearing 22, and the other end of the rod is threaded, as indicated at 24, and entered in a nut 25 slidable in a bearing 26 fixed to the table 10. The nut 25 carries a pin 27 slidably pivotally engaged in a slot 28 provided in a lug 29 projecting from the plate 12. Thus, one may jog the plate 12 angularly a little one way or the other about the axis ab so as to make the belt 19 run without any perceptible wabble, as required for lapping a true finish.

The motor 13 is also swingable on a horizontal axis with respect to plate 12, as indicated by the pivotal mounting 38, with a view to maintaining the abrasive belt 19 under uniform tension by reason of the tendency of the motor 13 to gravitate about the axis 30 away from wheel 26. However, there is provided under one end of the base 31 of the motor 13 a nearly semicircular cam 32 that is provided as a machined end of a shaft mounted in a bearing 33 provided on one end of plate 12. The cam shaft is adapted to be turned by means of a hand lever 34 through 186 to lift the base 31 of the motor 13 to the extent indicated by the dotted inclined line cd shown in Fig. 2 whereby to free the belt 19 so that it may be easily removed and replaced when worn beyond further use. In like manner, if the belt requires jogging one Way or the other to a central position on pulley 14 and wheel 20, that can be done readily by releasing the tension in the manner just described.

The wheel 20 and abrasive belt 19 cooperate to pro- 3 vide an endless unyielding precision lapping surface on which to lap or polish on the arcuate contour of the wheel to obtain a micro-finish on the tip of a welded carbide tool bit like that indicated at 35 in Fig. 2. The bit 35 is mounted on a tool support or slide 36 and sometimes it is positioned at a desired angle by abutment alongside a protractor slidable back and forth in a groove 36 extending crosswise of the slide parallel to the Working face of the abrasive belt'19. The tool support 36 is adjustable in and out toward and away from the belt 19 and wheel on a table 37 carried on a vertically adjustable pillar 38, the in and out adjustment being obtained by means of a screw 39 rotatable in a bearing 49 on the support 36 and threading in a hole in the table 37. The angle of the surface 41 lapped so accurately on the tip of'the tool bit is determined by the elevation of the pillar 38 and hence the support 36 with respect to the working face of the wheel, it being manifest from an inspection of Fig. 2, in which the top of the support 36 on which the tool bit 35 rests is shown disposed in the plane of the horizontal line ef passed through the center of the wheel 20, that the higher the elevation of the tool support 36 the greater the angle lapped at 41, measuring from a vertical. Although the surface 41 lapped on this machine is on a radius determined by the radius of the wheel 20, that radius is large enough in relation to the thickness of the tool bit 35 for the surface 41 to be considered substantially flat. Merely by way of example but not in any sense as indicating a limitation on this invention, I may state that the wheel 20 in the machine heren in shown is of a 7-inch radius and I have found that this gives good results. The important features, as I at present see them, are:

(l) the lineal speed of the abrasive belt 19;

(2) the type of abrasive belt 19;

(3) the type of cooperating wheel 20, and

(4) the relationship of the tool support 36 to the contour of the wheel 20 so as to obtain the proper angularity of the surface 41 on the carbide tipped tool bit 35.

The abrasive belt 19 and wheel 29 combination replace the so-called diamond wheels, which are made of diamond chips or dust. This novel combination does a much better job using far less expensive abrasive belts 19, like the silicon carbide belts that were used heretofore only for polishing glass, ceramics, and non-ferrous materials. There again, the mention of silicon carbide should not be taken as in any sense a limitation on the invention, inasmuch as other abrasive materials could doubtlessly be used to equal, if not better, advantage. The belt 19 is preferably, though. not necessarily, one constructed with a cloth backing and made quite thin and pliable and without any appreciable variation in thickness throughout the length thereof, that is, without any overlapping of ends. Inasmuch as the machine must be constructed so that the periphery of thewheel will be true and have a hard surface, because there must be no cushioning action, the wheel 29 is preferably of cast iron or meehanite having a wide flat rim 42 with a smooth true periphery 43. A sheet metal dust and safety guard, only a portion of which is indicated at 44 in Fig. 2, is preferably provided suitably attached to the'table 10 and enclosing the major portion of the-wheel 20 and pulley 14 and the abrasive belt 19 operating thereon, leaving exposed for performance of the lapping operation a portion of the front of the wheel 20 above and below'the tool support 36. Dust discharged downwardly from the front of the wheel is conducted through the passage 45 into a pan 46 that is removably suspended on the front of the machine, as indicated at 47. Any suitable precision'bearing support of the kind shown may be provided for the wheel 20, it being, of course, very important that the periphery 43 of rim .42 be truly concentric to the axis of rotation, because its trueness is the basiso'f the micro-finishes lapped on thetoolbits. "Q

The pillar 38 supporting the table 37 is slidable in a vertical guide bearing 48 provided on the front end of the table 10 and has a keyway 49 in which the inner end of a screw 50 is slidably received to hold the pillar against turning, and, when the screw is tightened, lock the pillar in an adjusted position. An axial hole 51 provided in the lower end of the pillar is threaded and receives a pillar adjusting screw 52 that is swivelled in a bearing 53 for rotation with a hand wheel 54. This hand wheel-is graduated on the periphery from zero to 125 and the threads on the screw 52 are so related to these graduations that one complete revolution of the wheel means a vertical adjustment of .125, namely, /8 inch. The pillar 38 has graduations thereon in eighths of an inch, so that the operator can tell partly from the reading on the pillar 33 and partly by reference to the reading on the wheel.

54, what the machine is set for, down to a thousandth of an inch. The wheel 54, of course, turns with reference to an index mark M on the front of the table 10, where the reading on the wheel 54 is taken. The screw 50 is loosened whenever the height adjustment of the tool support 36 is to be changed, and this screw is tightened again after such an adjustment.

Referring to Figs. 3 and 4, which illustrate one method of operation, using a table of measurements to determine the micrometer adjustment for the elevation of the slide 36, the are 43 represents a portion of the periphery of the rim 42 of wheel 20 with the abrasive belt thereon, as indicated at 19. The dimension 55 is what appears on pillar 38 when the tool support is at zero elevationnamely, at line ef, Fig. 2. The dimensions indicated at 56 are elevations above the horizontal plane of the line ef for a series of angles 515. In other words, a line drawn tangent to the are 43 at any one of these scaled points makes an angle A to the vertical equal to that indicated adjacent the dimension, the angle A illustrated in Fig. 3 being 15. Now, referring to the table 57 shown in Fig. 4, it will be seen that for each angle from 5 to 15 there is a series of dimensions 58 and that these are in columns under the headings A", /8, etc., to 2", which refer to tool height or thickness. The operator, as directed in the instructions 59, first determines the tool height; then he sets the pillar 38 to the height shown in the table under that tool height. Thus, if it is say a A" tool bit the dimension indicated for at 5 angle is 1.750. That checks with Fig. 3 because l.390-}-.6l0=2.000, and 2.000.250=1,750. .The slide 36 is accordingly set very accurately to lap the specified ang e.

I Referring next to Figs. 5 and 6, which illustrate another method of operation, using the direct reading gauge 60 provided in accordance with the present invention in determining the elevation of the slide 36, the tool bit 35 in accordance with this method is placed on the slide and extending therefrom, as indicated in dotted lines in Figs. 2 and 5, into close proximity to the flat front face 61 of the gauge post wherevertically spaced graduations 62 are provided, as clearly appears in Fig. 6, to indicate the various levels for the various angles of lapping. These graduation lines are .125" apart and the numerals from O to 15 indicate the angles measured from a vertical. The operator, therefore, need only raise or lower the slide 36 to the point where the tip of the tool bit 35 registers with the graduation linefor the desired angle. Such a setting is accurate at leastto two decimal places and if a setting of closer accuracy to the third decimal place is desired, the operator can by referring to the table 57 estimate the actual micrometer reading for the given tool height and the angle desired and then make whatever slight correction in the setting of the wheel 54 may be necessary to get that exact reading. The gauge post 60 is provided preferably on the outer end of an arm 63 that is pivoted on a vertical axis on a pin 64 that has a press fit in a hole 65 provided in a projection 66 on the front of the wheel support 67. An accurately machined washer 68 spaces the arm 63 from the top face of the projection 66' so that the arm 63 may be swung easily from a retracted position parallel to and spaced from the front of the tool supporting slide 36 to an operative position substantially at right angles to said slide, where the gauge post 6%, as clearly appears in Figs. 2 and 5, is disposed in close enough proximity to the front of the slide 36 to enable accurate setting of the micrometer adjustment, using the gauge 63 in the manner described. This method of operation is accurate enough for most purposes and means a big saving in time for the operator. Many of these lapping machines will not be equipped with a table 57 for that reason, accuracy to a second decimal place being sufiicient for most work.

In conclusion, attention is called in Figs. 1 and 2 to an eccentric 69 on the end of a stub shaft 70 mounted in a bearing 71 provided in the same projection 66 that carries the pin 64. A lever 72 is attached to the shaft 70 and is shown in Fig. 2 in raised operative position holding eccentric 69 frictionally engaged with the inner periphery of the rim 42 to stop rotation of the wheel 20. The lever 72 is otherwise swung downwardly into abutment with the table holding eccentric 69 in retracted relationship to the rim of the wheel 20. Quick stoppage of the wheel saves time for the operator when a belt 19 is worn and has to be replaced.

it is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. In combination, an endless abrasive belt of suitable width, a suitably rotatably supported wheel of appreciable radius having a rim with a wide fiat smooth unyielding periphery on which said belt operates under tension, means for driving said belt and wheel, a work support having a surface in a plane parallel to a radius of said wheel on which a tool bit the tip of which is to be lapped by contact with said abrasive belt is adapted to be carried, a pillar on top of which said support is carried for adjustment in a direction parallel to a tangent to said wheel, a guide for said pillar, means for adjusting said pillar in said guide, and an elongated gauge member disposed adjacent said work support parallel to said pillar on the face of which toward the work support are provided transverse graduations spaced longitudinally of said gauge member, said graduations indicating directly the different levels for supporting a tool bit for lapping dilterent angles on the tool bit tip, whereby said work support with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted to a predetermined position for a predetermined angle of lapping by adjusting it with the tool bit movable in close proximity relative to the gauge member.

2. In combination, an endless abrasive belt of suitable width, a suitably rotatably supported wheel of appreciable radius having a rim with a wide fiat smooth unyielding periphery on which said belt operates under tension, means for driving said belt and wheel, a work support having a surface in a plane parallel to a radius of said wheel on which a tool bit the tip of which is to be lapped by contact with said abrasive belt is adapted to be carried, a pillar on top of which said support is carried for adjustment in a direction parallel to a tangent to said wheel, a guide for said pillar, means for adjusting said pillar in said guide, said pillar adjusting means including means giving a micrometer reading for each adjustment, said combination including a table of figures representing difierent micrometer measurements in which there is correlated with the angle of lapping desired the predetermined micrometer measurement for pillar adjustment for each of a series of tool bits of diflerent thicknesses, and an elongated gauge member disposed adjacent said work support parallel to said pillar on the face of which toward the work support are provided transverse graduations spaced longitudinally of said gauge member for indicating any given pillar adjustment independently of the means indicating the micrometer adjustment of the pillar, said graduations indicating directly the different levels for supporting a tool bit for lapping difierent angles on the tool bit tip, whereby said work support with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted with the micrometer adjustment to a predetermined position for a predetermined angle of lapping by adjusting it without reference to the micrometer readings and with the tool bit movable in close proximity relative to the gauge member and the pillar adjustment is then adapted to be corrected by only a slight amount of operation of the micrometer adjustment to secure a micrometer reading given in the table of figures so as to get the pillar adjusted more accurately to the prescribed micrometer measurement for the given tool and the angle of lapping desired.

3. in combination, an endless abrasive belt of suitable width, a suitably rotatably supported wheel of appreciable radius having a rim with a wide flat smooth unyielding periphery on which said belt operates under tension, means for driving said belt and wheel, a work support having a surface in a plane parallel to a radius of said wheel on which a tool bit the tip of which is to be lapped by contact with said abrasive belt is adapted to be carried, a pillar on top of which said support is carried for adjustment in a direction parallel to a tangent to said wheel, a guide for said pillar, means for adjusting said pillar in said guide, said work support including a slide on which the work is carried adjustable in a direction at right angles to the pillar and parallel to the radius of said wheel toward and away from the periphery of the wheel, and an elongated gauge member disposed adjacent said work support parallel to said pillar on the face of which toward the work support are provided transverse graduations spaced longitudinally of said gauge member, said graduations indicating directly the different levels for supporting a tool bit for lapping different angles on the tool bit tip, whereby said work support with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted to a predetermined position for a predetermined angle of lapping by adjusting it with the tool bit movable in close proximity relative to the gauge member.

4. A lapping machine comprising, in combination, a suitably rotatably supported wheel of appreciable radius having a rim with a wide flat smooth unyielding periphery, means for driving said wheel at a high speed, means pro viding an abrasive covering of uniform thickness on the contour of the rim of said wheel suitable for lapping a micro-iinish on the tip of a carbide tipped tool, means for adjustably supporting a tool bit to be lapped on the tip so that the bit is adjustable to any one of a series of lappin positions parallel to one another and closer to or farther away from a certain radius of the wheel, so that the greater the distance from the said radius the greater the angle of lapping obtainable by reason of the lapping being done on the contour of the wheel, and an elongated gauge member disposed adjacent said adjustable tool bit supporting means parallel to the direction of its adjustability and having on the face toward said means transverse graduations spaced longitudinally of said gauge member, said graduations indicating directly the diiferent levels for supporting a tool bit for lapping difierent angles on the tool bit tip, whereby said tool supporting means with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted to a predetermined position for a predetermined angle of lapping by adjusting it with the tool bit movable in close proximity relative to the gauge member.

5. A lapping machine comprising, in combination, a suitably rotatably supported wheel of appreciable radius having a rim with a wide flat smooth unyielding periphery, means for driving said wheel at a high speed, means providing an abrasive covering of uniform thickness on the contour of the rim of said wheel suitable for lapping a micro-finish on the tip of a carbide tipped tool, means for adjustably supporting a tool bit to be lapped on the tip so that the bit is adjustable to any one of a series of lapping positions parallel to one another and closer to or farther away from a certain radius of the wheel, so that the greater'the distance from the said radius the greater the angle of lapping obtainable by reason of the lapping being done on the contour of the Wheel, an elongated gauge member disposed adjacent said adjustable tool bit supporting means parallel to the direction of its adjustability and having on the face toward said means transverse graduations spaced longitudinally of said gauge member, said graduations indicating directly the different levels for supporting a tool bit for lapping different angles on the tool bit tip, whereby said tool supporting means with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted without reference to the micrometer readings to a predetermined position for a predetermined angle of lapping by adjusting it with the tool bit movable in close proximity relative to the gauge member, and a table of figures representing different micrometer measurements in which there is correlated with the angle of lapping desired the predetermined micrometer measurement relating to the distance of said tool supporting means from the aforesaid radius, the micrometer adjustment being then adapted to be operated a slight amount one Way or the other until the micrometer reading thereon agrees with the table in so far as the given tool bit and the angle of lapping desired are concerned.

6. A lapping machine comprising, in combination, a suitably rotatably supported wheel of appreciable radius having a rim with a wide flat smooth unyielding periphery, means for driving said wheel at a high speed, means providing an abrasive covering of uniform thickness on the contour of the rim of said wheel suitable for lapping a micro-finish on the tip of a carbide tipped tool, means for adjustably supporting a tool bit to be lapped on the tip so that the bit is adjustable to any one of a series of lapping positions parallel to one another and closer to or farther away from a certain radius of the wheel, so that the greater the distance from the said radius the greater the angle of lapping obtainable by reason of the lapping being done on the contour of the wheel, said tool bit supporting means including a slide on which the work is carried adjustable in a direction at right angles to the other direction of adjustment described, namely, parallel to the said radius of said wheel toward and away from the periphery thereof, and an elongated gauge member disposed adjacent said adjustable tool bit supporting means parallel to the direction of its adjustability and having on the face toward said means transverse graduations spaced longitudinally of said gauge member, said graduations indicating directly the difierent levels for supporting a tool bit for lapping difierent angles on the tool bit tip, whereby said tool supporting means with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted to a predetermined position for a predetermined angle of lapping by adjusting it with the tool bit movable in close proximity'relative to the gauge member. I

7. In alapping machine comprising a suitably rotatably supported wheel of appreciable radius having a rim with a Wide flat smooth unyielding periphery, means providing an abrasive covering for said wheel suitable for lapping a micro finish on the tip of a carbide tipped tool, means for driving said wheel, a work support having a surface in a plane parallel to a certain radius of said wheel on which a tool bit the tip of which is to be lapped is adapted to be supported for lapping contact with said abrasive, a pillar on top of which said support is carried for adjustment in a guide in a direction at right angles to said radius, and means for adjusting said pillar in said guide, the improvement which consists in the provision of an arm mounted on said machine for pivotal movement about an axis parallel to said pillar and supported accurately in a given plane parallel to said work support, said arm carrying an elongated gauge member disposed parallel to said pillar and having on one face thereof transverse graduations spaced longitudinally of said member, said graduations indicating directly the different levels for supporting a tool bit for lapping different angles on the tool bit tip, whereby said work support with a tool bit resting thereon with the tip disposed adjacent said gauge member is adapted to be adjusted to a predetermined elevation for a predetermined angle of lapping by adjusting said support with the tool bit movable in close proximity lengthwise relative to the gauge member.

References Cited in the file of this patent UNITED STATES PATENTS 85,537 Sawyer Jan. 5, 1869 278,578 McLaughlin May 29, 1883 287,144 Madden Oct. 23, 1883 462,185 Wilson et al Oct. 27, 1891 504,306 Norton Aug. 29, 1893 1,288,908 Johnson -Dec. 24, 1918 1,528,685 Murphy Mar. 31, 1925 1,841,411 Kux Jan. 19, 1932 1,981,174 Hi1le Nov. 20, 1934 2,220,268 Olsen Nov.'5, 1940 2,367,107 Emmons Jan. 9, 1945 2,449,519 Sutton Sept. 14, 1948 2,573,220 Riedsel et a1 Oct. 30, 1951 2,578,662 Bader Dec. 18, 1951 2,597,256 Murray May 20, 1952 2,632,981 Kniep Mar. 31, 1953 2,663,978 Lindmark Dec. 29, 1953 FOREIGN PATENTS 67,799 7 Austria Aug. 1, 1914 Switzerland Aug. 15, 1947

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