US3461618A - Grinding device with workpiece locating mechanism - Google Patents

Description

M. H. LILL ET L GRINDING DEVICE WITH WORKPIECE LOCATING MECHANISM Aug. 19, 1969- Filed Dec. '20. 1965 s sheet-sheet 1 v INVENTORS MELVIN H. LILBL WELDQN B.EL|LEGE BY MM ATTQRNEY Aug. T9, l"96'9 H- mm. ET AL GRINDING DEVICE WITH WORKPIECE LOCA'I'ING MECHANISM Filed Dec. 20, 1965 5 Sheets-Sheet 2 INVENTORS MELVIN H. LILL WELDON B.ELLEGE ATTORNEY Aug. 19, 1969 H, ET AL GRINDING DEVICE WITH WORKPIECE LOCATING MECHANISM Filed Dec. 20, 1965 3 Sheets-Sheet INVENTORS MELVIN H. Ll LL WELDON B.ELLEGE BY MW 5. "ff"*) ATTORNEY United States Patent ice US. Cl. 51-124 3 Claims ABSTRACT OF THE DISCLOSURE A device for grinding semi-circular brake shoes has a rotatable grinding wheel and has a work holder pivotal about an axis. The work holder has a clamping assembly with four spaced positioning projections to engage the brake shoe centrally and locate the brake shoe in one direction in the clamping assembly before clamping. A work positioner for locating one end of the brake shoe in the clamping assembly before clamping has a positioning lug to engage the eye at one end of the brake shoe. The work positioner has a sleeve mounted on the clamping assembly transverse to said one direction. The sleeve is transversely adjustable, for coarse transverse positioning of the lug, and receives a micrometer bar therein which is transversely adjustable in the sleeve for fine transverse positioning of the lug. The lug is adjustably mounted on a slide bar which extends perpendicularly from the micrometer bar.

The present invention pertains to grinding devices and, more particularly, to devices for grinding arcuate surfaces, such as, the convex surfaces of brake shoes, and also pertains to an accessory for use with such grinding devices for positioning the brake shoe in the grinding device.

In processing lined automotive brake shoes, it is usually necessary to dress-down a new lining so that the radius of curvature of the face of lining is substantially the same as that of the brake drum with which the brake shoe is to be used in order that the entire braking surface of the lining will engage the brake drum when the brake is applied. In some brake assemblies the brake shoe pivots into engagement with the brake drum about an anchor pin which is secured either permanently or. adjustably to the backing plate of the brake assembly.

In the case of the permanent non-adjustable anchor pin, it is necessary, in order to obtain optimum braking, to position the anchor eye of the brake shoe in the grinding device a distance from the center of the arc ground on the face of the lining that is equal to the distance between the anchor pin and the center of the brake drum in the brake assembly. When the ground brake shoe is installed in the brake assembly, the anchor eye of the shoe engages the anchor on the backing plate of the assembly 3,461,618 Patented Aug. 19, 1969 shoe in the grinding device so that the: distance between the center of the anchor eye and the center of the arc ground on the face of the lining will be equal to the distance between the anchor pin and the center of the brake drum in a brake assembly.

I Another object of this invention is to provide a grinding device for grinding brake shoe linings with a minimum of error.

Another object of this invention is to provide an accessory for a grinding device which may be adjusted to a predetermined setting associated with the machine with which the workpiece is to be used and which provides a standard for ginding all subsequent workpieces in exactly the same position with respect to the grinding element as the first piece which is ground.

Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings, in which:

FIGURE 1 is a perspective of the grinding device embodyin g the present invention.

FIGURE 2 is an enlarged plan of the grinding device shown in FIGURE 1 with a brake shoe mounted in the grinder in a position which is just prior to the shoe being placed in engagement with the grinding disc of the grinder.

FIGURE 3 is an exploded isometric of the brake shoe positioning accessory.

FIGURE 4 is an enlarged section of the positioning accessory taken along the lines 4-4 of FIGURE 2.

FIGURE 5 is a diagram showing a calibrating procedure for one of the scales used in the accessory.

In FIGURE 1 there is shown an embodiment of the grinding device employing the present invention which comprises a base 10 having mounted thereon a grinding disc 11, a blower assembly 12, a motor 13, a work carraige 14, and a work holder 16 that is slidably adjustable on the work carriage. The work holder has a clamp assembly 18 secured to its outer end for holding a workpiece, such as, an automotive brake shoe.

The work carriage 14 is best shown in FIGURE 1 and includes a lower slide 20 and an upper pivot mem ber 22. The lower slide and the upper pivot member are connected by a pivot post or bolt 24, shown schematically in dotted lines in FIGURE 2 which permits rotation of the pivot member relative to the slide. A set of guide rails 26 are provided on the base 10 to engage the lower slide and the upper pivot member such that the upper pivot and, when the brake is applied, the lining is moved into the brakedrum along an arc, the center of which is the anchor pin. In order to have optimum braking, the are through which the centerof the arc of the lining travels must be tangent at the center of the brake drum to a member is both slidable with respect to the base and pivotable about the pivot post 24 on an imaginary axis X through the center of the pivot post. The upper pivot member is adjusted longitudinally relative to the base by a fast adjustment mechanism 32 and a fine adjustment mechanism 34.

The work holder 16 includes a plate 35 that is slidably mounted on the upper pivot member 22 and is retained thereon by a set of guide plates 36 which have a vertical reference face 37. The work holder is adjustable longitudinally relative to the upper pivot member by a rough feed mechanism 38 and a slow feed mechanism 40. The slow feed mechanism also serves as a handle for oscillating the upper pivot member about the pivot post 24. Fixed to the innermost end of the slide plate 35 is the clamp aswith the toe of the shoe contacting the brake drum first.

sembly 18. A lever 44 for opening and closing the clamp assembly is pivotally mounted to the top thereof. As best shown in FIGURE 1, a brake shoe 5 is securely held by the clamp assembly when the lever is in its lowermost position. The clamp assembly is also provided with sets of spaced upper and lower positioning projections 46' (only the upper projections are shown in FIG. 2) for aligning the brake shoe in the clamp assembly before it is locked in place by the clamping mechanism.

That part of the mechanism which has just been described corresponds to the mechanism disclosed in our copending application Serial No. 455,373, filed May 13, 1965, now U.S. Patent No. 3,394,500 granted July 30, 1968, to which reference may be had for the details of construction and operation of the instant device and which is incorporated herein by reference. Briefly stated, in order to position a brake shoe on the grinder previously described, it is necessary to lift the lever 44 to release the clamp assembly and insert the brake shoe against the four projections 46 on the clamp assembly.

A typical brake shoe has a lining L, a table t to which the lining is secured, and a web w. The web is formed with an anchor eye E which is adapted to engage an anchor pin or positioning lug (not shown) secured to the backing plate of the wheel assembly of an automobile. The lining of the shoe is generally centered by sight with the table of the shoe engaged by all four of the positioning projections 46. Thus, similar shoes may be similarly ground by generally centering each of the shoe linings in the clamp assembly with the shoe tables abutting the positioning projections.

Although this method of placing the shoes in the clamp assembly is acceptable for many types of brake shoes; it is somewhat undesirable when employed with brake shoes of the so-called fixed anchor type. The fixed anchor type of brake shoe is positioned in the brake assembly on the vehicle such that its motion is limited to pivoting about an anchor pin fixed to the backing plate of the wheel assembly. If the center of the arc of the face of the lining does not travel along an are about the anchor pin which is tangent at the center of the drum to a drum radius perpendicular to a drum radius passing through the anchor pin, the lining will not contact the drum properly and it will be impossible to correct the position of the shoe. To overcome this problem when the brake shoe is used with a fixed anchor pin, the instant invention provides an anchor eye positioning abutment which locates the anchor eye of the brake shoe while being ground at a distance from the center of the arc ground on the lining which is equal to the distance between the anchor pin and the center of the drum with which the shoe will be employed.

As best shown in FIGURES 2, 3 and 4, the instant invention takes the form of an accessory to be used on the grinding device, as hereinbefore described, which cooperates when used therewith to improve the grinding device. The accessory comprises an index sleeve 60 having a longitudinal slot 62 (FIG. 3) and a key-way 64. Aligned longitudinally with the slot 62 are a plurality of indexing apertures 66. Circumscribing the index sleeve are a plurality of equi-spaced lettered indexing lines A-E.

The sleeve has a longitudinal bore 70 and is counterbored at one end as at 72. The bore receives a micrometer bar 76 having a diameter just less than the bore such that the micrometer bar is snugly but slidably retained in the index sleeve. The end of the micrometer bar adjacent the counterbore 72 is of a reduced diameter as at 78 and is circumscribed by a spring 80 which abuts against the larger diameter portion of the micrometer bar and a shoulder 81 formed between the bores 70 and 72 and against a snap ring 82 mounted in a groove 84 in the counterbore 72. The reduced diameter portion is threaded at its outer end and has threaded thereon a bushing 86. A dial knob 88 circumscribes the bushing and is secured thereto by a set screw 90. The dial knob is provided with fifty equi-spaced measuring marks 91 (FIG. 2) which cooperate with an indicator line 92 (FIG. 2) scribed on the outer face of the index sleeve 60 to indicate partial rotation of the dial knob.

A key 93 (FIG. 4) is pressed into a groove 94 on the micrometer bar and slides in the keyway 64. The key and keyway, cooperate to permit relative longitudinal movement between the index sleeve and the micrometer bar but restrains them against relative rotational move- 4 ment. With the dial knob 88 fastened to the bushing 86 and the bushing threaded to the micrometer bar 76, rotation of the dial knob will cause axial movement of the micrometer bar against or with the bias of the spring 80. Each of the measuring marks 91 equal 0.001 inch axial movement of the micrometer bar. Accordingly, a full revolution of the knob causes 0.050 inch of axial movement of the bar. The opposite end of the micrometer bar is provided with a snap ring 106 (FIG. 4) mounted in a groove 108 and with a plurality of longitudinally spaced increment grooves 110 which cooperate with the edge 111 of a beveled guide surface 112 for-med on the end of the index sleeve farthest from the counterbored portion 72 to indicate axial movement of the bar. Each groove equals one revolution of the dial knob or 0.05 inch axial movement of the micrometer bar.

As assembled it can be readily seen that rotation of the dial knob 88 clockwise, when viewed from the side of the grinding device closest to the dial knob, draws the micrometer bar 76 toward the dial knob against the force of the spring 80. Consequently, at all times the interlocking threads in the micrometer bar and the bushing are pressed tightly against one another to assure snug engagement therebetween.

As best shown in FIGURES 2 and 3, a link casting 116 is provided with a first horizontal bore 118 which receives the free end of the micrometer bar 76. A blind bore 120 extends normally and rearwardly from the first bore. A set screw 122 securely fastens the link casting on the micro-meter bar such that the longitudinal axis of the blind bore is substantially horizontal. A slide bar 126 is received in the blind bore and is provided with a longitudinal groove 128. A set screw 130 secures the slide bar in the blind bore with the groove facing upward. Thus, the slide bar 126 is mounted in the link casting disposed perpendicular to the micrometer bar 76 and with the longitudinal groove 128 substantially vertical.

A mounting member 134 has a horizontal bore 136 which receives the free end of the slide bar 126. A set screw 138 is threaded into the mounting member and abuts against the groove 128 to adjustably and securely fasten the mounting member on the free end of the slide bar. The mounting member is also provided with a vertical bore 140.

A generally cylindrical positioning abutment lug 142 is positioned in the bore 140 and is provided with a flat portion 146 and with a plurality of cylindrical reduced portions which correspond to the curvature of the anchor eyes of a large variety of diiferent type brake shoes. By raising or lowering the positioning abutment or by reversing it in the vertical bore 140, any one of four curvatures on the lug 142 can be utilized.

An adjusting screw 144 is threaded into the mounting member 134 and abuts against the fiat portion 146 of the positioning abutment lug to adjustably and securely retain the positioning abutment lug in the mounting member. By releasing the adjusting screw 138, the mounting member may be slid longitudinally along the slide bar. The slide bar has a plurality of calibration lines 147 which cooperate with a machined edge 148 on the mounting member 134 to accurately position the mounting member on the slide bar so that the axis of the anchor lug 142 is the same distance from the grinding disc at the beginning of the grinding operation as is the axis of pivot post 24.

When assembled in the grinder, the index sleeve 60 is received in a transverse horizontal bore 200 (FIGS. 2 and 4) in the base 201 .of the clamp assembly 18. A set screw 202 is threaded into a threaded hole 204 which intersects the bore 200. The index sleeve is rotated in the bore 200 until the indexing apertures 66 are aligned with the threaded bore 204. The set screw is then screwed into engagement with one of the apertures to hold the index sleeve against movement. An auxiliary threaded hole 206 intersects the bore 200 and will be in alignment with the slot 62. When brake shoes for which the particular letter setting A-E is not known, the set screw 202 is removed from the hole 204 and threaded into the auxiliary hole. The index sleeve will then be securely held in the desired axial position since the screw will engage the slot 62.

Each of the above measuring and indexing lines cooperate to locate the positioning abutment lug 142 a dis tance from a radius of the pivot post 24 to the grinding disc exactly equal to the distance between the anchor pin and the center of the brake drum with which the particular brake shoe is to be employed. It should be noted that the base 201 of the clamp assembly has a vertical machined face 210 that is aparallel to and spaced 1.625 inches from a vertical longitudinal plane XX that passes through the axis of the pivot post 24. The index sleeve 60, the micrometer bar 76, the link casting 116, the slide bar 126, and the mounting member 134 are so designed and proportioned that, when the snap ring 106 abuts the edge 111 of the index sleeve 60 and the reference line A on the sleeve is just exposed alongside the machined face 210 of the clamp, the center of the abutment lug 142 is 3% inches from the plane XX. Since the marks A- E are spaced A t-inch apart, the lug 142 can be quickly positioned firinch further away from the plane XX by loosening the thumb screw 202, shifting the sleeve until the mark B is adjacent the surface 210. Similarly, mark C indicates a 4% inch setting, and mark D indicates a 4 /2 inch setting.

Since the distance from the pivot axis X to the grinding disc will depend upon the size of the brake shoe being ground and, since the distance from the axis of the anchor lug 142 to the grinding disc 11 must be approximately equal to the distance of the axis X from the grinding disc when the face of the shoe contacts the disc at the beginning of the grinding operation, the slide bar 126 must be calibrated so that when each mark on the bar, indicating a {particular diameter of brake shoe, is positioned adjacent the face 148 of the mounting member 134, the axis of lug 142 will be an appropriate distance from the face of the disc.

The bar 126 is calibrated by following the procedure indicated in FIGURE 5. In the grinding machine of FIG- URE 2 the faces of the positioning projection 46 of the clamp, against which the table 2 of the shoe abuts, are formed on an arc V of a circle whose radius R is 5.485 inches. The center of the circle is in plane XX and on a vertical projection of a point P on the slide plate 35, the projections 46 are equi-spaced from the plane XX, and are V intersects radius R at W. For a typical 9" brake shoe, the combined thickness of the brake lining L to be ground and the table if of the shoe may be considered to be 5 Accordingly, the face of the brake shoe when it contacts the grinding disc 11 will be on an arc Y that intersects R at point Z which is from point W. Since the face of a 9" shoe should be 4 /2" from the axis of the pivot post 24 when grinding is started, the point on slide plate 35 that is directly in vertical alignment with the axis of post 24 is 4 /2" from point Z and this point is indicated as point T. The center of the anchor lug 142 is therefore on a line M that is perpendicular to the plane X-X and passes through point T.

It should be noted that the reference face 148 on the mounting member 134 is spaced from a parallel plane passing through the center of lug 142. Accordingly, the reference mark 9 on the bar 126 will be opposite the face 148 and will be spaced from line M.

Point T for a 10-inch shoe is obtained by striking an are about point Z on a 5" radius. The lug 142 will be on line M and the reference line 10 on slide bar 126 will be from line M. 'Point T for an 11" shoe is obtained by striking an are about point Z on a 5%." radius, and the reference mark 11 on bar 126 will be %;2" from the line M.

By using the above procedure, reference marks can be made on slide bar 126 for shoes of any size, each of these marks will indicate the distance the anchor lug is spaced from the grinding disc when grinding begins. It will be understood that the thickness of the lining L and the thickness of the shoe table 1 may vary slightly for different size shoes. Also, the curvature of the tables of the shoes vary and, accordingly, they may not engage the faces of the projections in exactly the same manner. Thus the points T, T and T" which have been developed for typical shoes will not be perfectly accurate if shoes having any of the above mentioned variations are ground. However, it has been found that, if the slide bar 126 is calibrated according to the above procedure, the finished shoes will effectively engage the brake drum when put into operation.

In the operation of the brake shoe grinder with the accessory installed, it is necessary first to determine the position of the anchor pin in the brake assembly with respect to the center of the brake drum. These measurements can be determined beforehand and published on a printed form, or individual measurements can be made as the occasion arises. For example, the 1963 Ford Galaxie has ll-inch brake shoes and has an anchor pin located 4.625 inches from the center of its brake drum. The setting on the accessory to locate the positioning abutment lug 142 at a point 4.625 inches from the plane XX along a line perpendicular to the plane would be D. 125. To set the grinder, the cap screw 202 is screwed through the hole 204 and the index sleeve 60 is slid axially in the bore 200 until the indexing line marked D appears at the entrance to the bore 200 adjacent the face 210 of the clamp assembly. This first adjustment positions lug 142 at 4.50 inches from plane XX. Next the dial knob 88 is rotated until the micrometer bar 76 is extended out of the index sleeve an additional amount equal to 0.125 inch. This will be attained by two full revolutions of the dial knob and a further partial rotation until a measuring mark 91 numbered 25 is aligned with the indicator line 92. For convenience the two revolutions of the dial knob can be readily detected by viewing the number of spaced increment marks which are visible beyond the beveled guide surface 112 since, as aforementioned, each full revolution of the dial knob will move an increment groove into alignment with the beveled guide surface.

The setscrew 138 is then loosened and the mounting member 134 is slid along the slide bar '126 until the reference mark 11 on bar 126 is just visible alongside reference surface 148 on the mounting member. When this setting has been made the setscrew is tightened to lock the mounting member on the bar 126.

At this point the positioning abutment lug 142 is exactly 4.625 inches from the plane X--X along a line perpendicular to the plane, and the anchor lug is positioned on the imaginary line M" through the axis X of the pivot post 24. Next the shoe is placed in the clamp assembly 18 with the table I abutting the positioning projections 46 and the anchor eye E of the shoe engaging the positioning abutment lug 142. The grinding device is then set to grind an 11" shoe by adjusting the fast adjustment 32 as explained in the above-mentioned pending application Serial No. 455,373. Such a setting is indicated in FIGURE 2 wherein it will be noted that the imaginary line M" is in back of a line passing through the axis X. The next step will be to make a fine adjustment by manipulating slide 35 to move the slide toward the grinding disc until reference mark 11 on slide 35 is opposite the reference face 37 of guide plates 36 as also explained in said application Serial No. 455,373. The work holder 16 is then moved toward the grinding disc until the lining is just touching the disc at which time line M" will be aligned with axis X. The motor is turned on and the shoe is pivoted about the pivot post 24 and fed, by the slow feed mechanism 40, until the face of the lining is evenly ground. The shoe may then be removed and is ready for installation in the brake assembly.

From the foregoing description it will be apparent that the present invention provides a brake shoe positioning member that may be quickly and accurately adjusted so that linings can be effectively ground on shoes of various sizes. The micrometer bar 76 and its associated mechanisms provide means for accurately positioning the anchor eye of any shoe the desired distance from the pivot axis X, and the slide bar 126 and its associated mechanisms provide means for positioning the anchor lug substantially the same distance from the grinding disc as is the pivot post 24.

As is readily apparent, the advantages provided by the accessory are many. For example, similar shoes may all be positioned in exactly the same manner and the ground surface on each lining will approximate the curvature of the brake drum with which the shoe is used. In addition the anchor eye of the shoe can be positioned with respect to the grinder by extremely accurate and readily adjustable measuring elements which may be preset by referring to a reference chart thus permitting a single accessory to be used for a large variety of brake shoes.

While a preferred apparatus for carrying out the invention has been shown and described, it will be understood it is capable of modification and variation While still employing the principles of the invention. It is to be understood, therefore, that the scope of the invention should be limited only by the scope and proper interpretation of the claims appended hereto.

Having thus described the invention, that which is be lieved to be new and for which protection by Letters Patent is desired is:

1. In a device for grinding an arcuate brake shoe having an eye at one end, said device having a grinding element and having a pivotal Work holder to swing the brake shoe relative to the grinding element, said work holder having a clamping assembly with positioning projections to engage the brake shoe centrally for locating the center of the brake shoe in one direction before clamping,

the improvement comprising an adjustable threaded micrometer bar mounted on said work holder in an axis transverse to said one direction for axial movement relative to the WOIk holder on adjustment of the micrometer bar, a graduated bar mounted on said micrometer bar for adjusting movement with said micrometer bar and relative thereto parallel to said one direction, and an upstanding positioning lug mounted on said graduated bar to engage the brake shoe eye.

2. The device of claim 1 in which a graduated sleeve is mounted in the clamping assembly to receive said micrometer bar, said sleeve being positionable in the clamping assembly on said axis for coarse axial adjustment of the positioning lug.

3. The device of claim 1 in which said positioning lug has stepped diameters and is vertically adjustable on said graduated bar.

References Cited UNITED STATES PATENTS 2,289,693 7/1942 Blazek 51-277 X 2,345,161 3/1944 Thomason 51277 X 2,398,628 4/1946 Dykoski 51-277 X 2,629,270 2/ 1953 Kaehlert 33185 X 2,734,319 2/1956 Billeter.

2,974,450 3/ 1961 McVey.

2,820,331 1/1958 Billeter 5196 2,901,869 9/1959 Billeter 5196 HAROLD D. WHlTEI-IEAD, Primary Examiner US. Cl. X.R.

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