US3616579A - Grinding machine - Google Patents

Abstract

A PAIR OF WORKPIECE-ENGAGING JAWS ARE SLIDEABLY SUPPORTED UPON GUIDE RODS FOR INDEPENDENT MOVEMENT LENGTHWISE THEREOF AND SAID GUIDE RODS ARE SUPPORTED BY PEDESTALS MOUNTED UPON A BASE. THE WORKPIECE IS CHANNEL SHAPED IN THIS EMBODIMENT AND OPENS DOWNWARDLY WHEN IT IS HELD BETWEEN THE JAWS. A PAIR OF VERTICALLY ALIGNED GRINDING WHEELS, ONE HAVING A CONVEX PERIPHERAL FACE AND THE OTHER HAVING A CONCAVE, PERIPHERAL FACE ARE MOUNTED UPON SPINDLES FOR ROTATION ABOUT PARALLEL AXES. THE WHEEL SPINDLES ARE SUPPORTED IN BEARING ASSEMBLIES ADJUSTABLY MOUNTED UPON AN UPRIGHT COLUMN CONNECTED TO THE BASE. A PAIR OF MOTORS ARE MOUNTED UPON THE COLUMN AND CONNECTED TO THE SPINDLES FOR ROTATING SAME INDEPENDENTLY. THE JAWS ARE URGED TOWARD AND AWAY FROM EACH OTHER BY HYDRAULIC ACTUATORS SUPPORTED UPON THE PEDESTALS.

Description

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Nov. 2, 1971 A, MaoKAY Y 3,616,519

GRINDING MACHINE l l i w y /4/ /19/ /34L NOV. 2, 1971 J. A. MacKAY 3,616,519

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GRINDING MACHINE Filed Jan. 7, 1970 7 Sheets-Sheet 5 INVENT'OR Jaw/Amann il@ wm/Zw' J. A. MaCKAY GRINDING MACHINE Nov. Z, 1971 Filed Jan. 7, 1970 '7 Sheets-Sheet 6 V/ Wwf Tf W N4 y im m4 f M /00 Y m W, l/

NOV- 2 1971 J. A. MaCKAY 3,616,579

GRINDING MACHINE Filed Jan. 7, 1970 'T Sheets-Sheet INVENToR ddl/Af A. Afl/IC KAV Y WM/fun@ United States Patent Office 3,616,579 Patented Nov. 2 1971 3,616,579 GRINDING MACHINE `lohn A. MacKay, Warren, Mich., assignor to Unison Corporation, Madison Heights, Mich. Filed Jan. 7, 1970, Ser. No. 1,256 Int. Cl. B24b 7/00 U.S. Cl. 51--82 R 15 Claims ABSTRACT F THE DISCLOSURE A pair of workpiece-engaging jaws are slideably supported upon guide rods for independent movement lengthwise thereof and said guide rods are supported by pedestals mounted upon a base. The workpiece is channel shaped in this embodiment and opens downwardly 'when it is held between the jaws. A pair of vertically aligned grinding wheels, one having a convex, peripheral face and the other having a concave, peripheral face are mounted upon spindles for rotation about parallel axes. The wheel spindles are supported in bearing assemblies adjustably mounted upon an upright column connected to the base. A pair of motors are mounted upon the column and connected to the spindles for rotating same independently. The jaws are urged toward and away from each other by hydraulic actuators supported upon the pedestals.

BACKGROUND OF THE INVENTION This invention relates in general to a grinding machine and, more particularly, to a type thereof especially adapted to simultaneously grind two substantially opposed surfaces of a relatively hard and nonplanar workpiece, the grinding operation being performed accurately, automatically and quickly so that the machine can be adapted to high production operations.

Persons familiar with the use of grinding equipment in performing an operation on relatively hard workpieces have long recognized the diliculties encountered in the grinding of two nonplanar faces of a hard workpiece, such as one made from ferrite, while maintaining a specified dimensional relationship between such faces. Heretofore, it has been customary to grind one face of the workpiece by means of a diamond-surfaced grinding wheel and then grind the second face, often on a second machine. However, especially where the workpiece is small or has an irregular shape, it is extremely diicult to produce uniformly similar pairs of ground faces on the successive parts. Moreover, the existing, two-step process requires at least twice as long for each piece, involves considerable additional handling and usually results in numerous rejects.

For purposes of example, only, specic reference is herein made to a particular workpiece, namely, a fixed field magnet made of ferrite for a small motor, because this workpiece has given rise to the aforementioned problem of accurately matching the shapes and dimensions of successive pairs of Iground surfaces. It is important that the thickness of the field magnet is uniform in order to provide uniformly consistent and effective motors. -In many cases, it is necessary to maintain tolerances of less than live thousandths of an inch and this has not been possible heretofore by means of automatic equipment capable of a large, low-cost output. That is, it has previously been necessary to produce this type of a workpiece either by a high-cost machining operation or by a relatively slow and high-cost, two-step grinding operation, both of which were performed substantially manually.

It is well known that the grinding wheel or grinding wheels must be removed from the spindles of a grinding machine, rather frequently in some instances, to repair them or to replace them with grinding wheels of dilferent contours. Where the workpiece is relatively small, as in the case of a one-piece field magnet for a fractional horsepower motor, such removal has, in the past, been difficult. The grinding wheel spindle is usually supported in and extends from both ends of a bearing assembly, and the grinding wheel is sleeved onto one extended end of the spindle. However, parts of the grinding machine, which hold or guide the workpiece, frequently extend across the face of the grinding wheel or wheels, and these parts must be removed before the grinding wheel or wheels can be released from or placed upon the grinding wheel spindles. That is, there is insufficient room for axial movement of the grinding wheel beyond the end of its spindle to permit removal of the grinding wheel. However, in most of these instances there is adequate room for radial movement of the grinding wheel relative to the spindle, in at least one radial direction, if the spindle did not prevent such movement.

Where two radially aligned grinding wheels are used to simultaneously perform a surfacing operation on opposite sides of a workpiece, it is not uncommon to mount the grinding wheels on spindles supported by two separate bearing assemblies which are adjustably mounted upon a supporting column. Where one of the grinding wheels is directly above the other grinding wheel, adjustment of the radial distance between the two grinding `wheels is considerably more complicated than where, for example, the two grinding wheels are on the same horizontal level. The weight of the grinding wheel spindle and bearing assembly can make adjustment diicult and inaccurate. As a result, existing devices for effecting such radial adjustment between a pair of grinding wheels have been complicated and diicult to use, or inaccurate.

In the past, it has been common practice to thread at least one end of a grinding wheel spindle and provide a nut thereon to serve as a retainer for the inner race of the adjacent bearing. However, it has been virtually impossible to cut the threads so that the engaging faces of the nut and bearing race define precisely parallel planes pracisely perpendicular to the spindle axis when said faces are brought into snug engagement. Accordingly, the tightening of the nut almost always creates a few thousandths of an inch of `deflection in the end of the spindle adjacent the nut. This results in a nonuniform distribution of radial forces against the bearings and, therefore, excessive wear and/or inaccurate grinding.

Accordingly, a primary object of this invention is the provision of a grinding machine capable of simultaneously and quickly performing grinding operations on two different surfaces of the same workpiece which is fabricated from an extremely hard material, such as ferrite, while, at the same time, producing a uniformly accurate grinding operation on successive workpieces in a relatively short period of time.

A further object of this invention is the provision of a machine, as aforesaid, which performs the grinding operation automatically, which is capable of gripping and holding the workpiece rmly and accurately, in which the grinding wheels are mounted upon spindles which can be disassembled to permit radial movement of the grinding wheels away from their positions of normal operation, in which the bearing assemblies supporting the grinding wheel spindles can be accurately and easily adjusted toward and away from each other along their supporting structure, and in which the spindle bearings are firmly held in place with respect to each other and the spindle they support without deflecting part of the spindle relative to the remainder thereof.

Other objects and purposes of the` invention will become apparent to persons familiar with this type of equipment upon reading the following description and examining the accompanying drawings, in which:

FIG. 1 is -a broken, side-elevational view of a grinding machine embodying the invention.

FIG. 2 is a broken, top plan view of said grinding machine.

FIG. 3 is a sectional View taken along the line III- III in FIG. 2.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2.

FIG. 5 is a sectional view taken along the line V-V in FIG. 2.

FIG. 6 is a perspective view of a workpiece and the jaws for engaging same.

FIG. 7 is a rear-elevational view of the spindle and motor support column.

FIG. 8 is a sectional view taken along the line VIII- VIII of FIG. 3.

FIG. 9 is a sectional view taken along the line IX-IX of FIG. 3.

FIG. l0 is a diagram of the hydraulic circuit for said grinding machine.

FIG. 11 is a fragmentary top plan view of an alternate grinding machine embodying the invention.

FIG. 12 is a sectional view taken along the line XII- XII in FIG. 11.

FIG. 13 is a sectional View taken along the line XIII- XIII of FIG. 12.

FIG. 14 is a sectional View taken along the line XIV- XIV in FIG. 12.

SUMMARY OF THE INVENTION The objects and purposes of the invention, including those set forth above, have been met by providing a grinding machine having an upright column mounted upon a base structure and adjustably supporting a pair of ver- \tically aligned bearing assemblies, each of which supports a grinding wheel spindle extending from both ends of the bearing assembly. The spindles are connected at corresponding ends of each to a pair of separate motors also mounted upon the column. The other ends of the spindles support a pair of radially aligned grinding wheels. A pair of workpiece-engaging jaws are aflixed to a pair of slides which are supported by and movable along guide rods supported upon pedestals mounted on the base structure. Power cylinders supported by the pedestals move the slides lengthwise of the guide rods DETAILED DESCRIPTION The grinding machine, a preferred embodiment of which is disclosed in FIGS. 1 and 2, has an elongated base supporting a pair of pedestals 1,1 and 12 near the opposite ends thereof and along the front edge thereof. An upright column 13 is mounted upon the base 10 along the rear edge thereof and spaced from the ends thereof. A pair of motors 14 and 1S, and a pair of bearing housings 17 and 18 are mounted upon the upright column 13. A pair of parallel guide rods 21 and 22 are mounted upon and extend between the pedestals 11 and 12 in front of the column 13, and a pair of slides 23 and 24 are supported upon the guide rods 21 and 22 for movement lengthwise thereof while supporting a workpiece 20.

The base 10 (FIGS. 1 and 2) may be a piece of elongated, relatively ilat and rigid material, such as a steel 4 plate, to which the pedestals 11 and 12, and the column 13 are rigidly secured by convenient means, such as bolts and/ or welding. Alternatively, a concrete floor, in which bolts or the like are anchored, may serve as the base for securing said pedestals and column in position.

The left pedestal 11, for example, is comprised of a bottom plate 26 which is secured to the base 10, as aforesaid, and an upright plate 27 which is secured rigidly along its lower edge to and extends upwardly from the rightward or inner edge of the bottom plate 26. A pair of braces or gussets 28 and 29 extend between the bottom plate and the upright plate near the front and rear edges thereof, respectively, and are secured thereto as by welding.

The right pedestal 12 may be, and preferably is, a mirror image of the left pedestal 11 described in the foregoing paragraph. Accordingly, parts of the pedestal 12 will be identified hereinafter by the same numerals as the corresponding parts of the left pedestal 11, in addition to the sufix A.

The guide rods 21 and 22 are preferably cylindrical, horizontal and parallel, and they may be hollow to reduce weight. However, said guide rods may be of a dilerent cross-sectional conguration, such as square, and they may be solid, if the need should arise, but their cross-sectional contour must be uniform lengthwise thereof. The opposite ends of the guide rods 21 and 22 are connected to and supported upon the upright plates 27 and 27A of the pedestals 11 and 12, respectively.

The upright column 13 (FIG. 7) has a bottom plate 32, a pair of side plates 33 and 34, a front upright plate 35 and a horizontal top plate 37. The bottom plate 32 is rigidly secured to the base 10, as aforesaid, and is rigidly secured to the front and `side plates, as is the top plate 37, by any convenient means such as welding. The motor 14 (FIG. 2) is adjustably mounted upon the top plate 37 so that the motor shaft 38 thereof extends rearwardly beyond the rearward edge of the top plate 37.

The column 13 (FIG. 7) has a shelf 39 adjustably secured to the rear surface of the front plate 35 and spaced below the top plate 37. The motor 15 is secured upon the shelf 39 so that its shaft 42 (FIG. 7) extends rearwardly beyond the rearward edge of the side plate 34.

The bearing assembly 17 (FIGS. 2, 3 and 9) is comprised of a substantially rectangular housing 43 having a cylindrical, horizontal bore 44 extending lengthwise thereof. The inner side of said housing 43 (FIG. 2) supports a sidewardly projecting key 46 which extends transversely of the bore 44 and is slidably received into the vertical keyway 47 in side plate 34. Said housing 43 also has a plurality, here four, of transverse bolt openings 48 (FIGS. 3 and 8) which extends in a direction substantially perpendicular to said inner side of the housing 43 which bears against the side plate 34. The bolt openings 43 are laterally and vertically elongated and the bolts 49 are slideably received through the openings 48 and are threadedly engaged in threaded openings in the side plate 34, such as the opening 52 in FIG. 8.

The bore 44 (FIG. 9) has a central portion 53 of reduced diameter which extends between the outer races of the front bearings 54 and the outer races of the rear bearings 55, which may be conventional antifriction bearings capable of resisting radial and axial thrust.

A spindle 57 (FIG. 9) has a central portion 58 which is disposed within and rotatably supported by the bearings 54 and 55. The spindle 57 has a rear portion 59 which has a central part 61 of enlarged diameter disposed between a rear extension 62 and a front end 63 which is of the same diameter as the adjacent end of the central spindle portion 58. The adjacent axial faces 64 and 65 of the central portion 58 Iand the rear portion 59, respectively, of the spindle 57 and perpendicular to the central, mutual axis thereof. The central portion 58 is foreshortened so that the front end 63 of the rear portion 59 extends into the inner race of the rearwardmost one of the rear bearings 55 when the front end of said enlarged part 61 is snugly against the inner race of rearwardmost said bearing 55.

The rear end of the central portion 58 has a coaxial, threaded bore 67 at its rearward end, and the rear portion S9 has a coaxial smooth bore 66 through which a bolt 68 is received for threaded engagement in bore 67 to secure the rear portion 59 with respect to the central portion 58 of the spindle 57. The spindle portions 58 and 59 are arranged and constructed so that the faces 64 and 65 are close, but spaced, when the bolt 68 is holding the rear portion 59 tightly against the rearwardmost bearing 55.

A rectangular key 69 (FIG. 9) is disposed within, and extends between, the keyways 70 and 71 in the faces 64 and 65, respectively. Because the key 69 extends transversely of the spindle 57, it has a central opening through which the bolt 68 is slideably received. The key 69 prevents relative rotation between the central portion S8 and rear portion 59.

The central portion 58 has a part 75 of enlarged diameter near the front end thereof which bears against the inner race of the frontwardmost one of the front bearings 54. The frontward end of the enlarged part 75 has an integral, annular flange 80, which overlays the front end of the housing 43 and has a coaxial, relatively large and cylindrical recess 72 in its front end. A coaxial threaded bolt opening 73 communicates with the recess 72 and extends rearwardly into the central portion 58. A pin opening 74 is disposed in the inner end wall of the recess 72 near the bolt opening 73 and extends rearward ly into the central portion 58 from the recess 72.

A pin 76 (FIG. 9) has one end thereof firmly held within the pin opening 74 so that it projects forwardly into the recess 72. The rear face of the flange 80 has coaxial grooves 81 into which are slideably received the coaxial, annular rings 85 which are integral with, and project frontwardly from, the bearing retainer 90 which is mounted upon the front end of the housing 43.

The spindle 57 has a front portion 77 which is preferably cylindrical and has a coaxial opening 78. The front portion 77 has a pin opening 79 in its rear end near the opening 78 and aligned with opening 74 for slideable reception of the forwardly projecting end of the pin 76. The rearward end of the front portion 77 is slideably but snugly disposed within the recess 72. The front end of the front portion 77 has an integral, annular and external flange 82.

The upper grinding wheel 83 has a central openlng through which the front portion 77 is slideably received so that the grinding wheel 83 can be clamped firmly between the flange 82 and the front side of the ange 75 on the front spindle portion 77 before the rear end of said front portion `57 engages the inner end wall of the recess 72. A bolt J84 is slideably received through the opening 78 for threaded engagement within the opening 73 in the central spindle portion 58. In this embodiment, the periphery of the grinding wheel 83 has a concave surface 86 which is semicircular axially of the wheel.

The bolt openings 48j (FIG. 8) are vertically enlongated to permit vertical adjustment of the housing 43, hence the spindle 57, along the column 13. This adjustment is effected by means of the wedge `87 mounted upon the column 13 directly below the housing 43. The wedge 87 (FIG. 3) has upper and lower edges 818 and 89, respectively, which converge rearwardly. Said wedge 87 also has a pair of spaced bolt openings 92 which are spaced the same distance from the lower edge 89 and are both elongated lengthwise of said lower edge. A pair of bolts 93 are slideably received through the bolt openings 92` and are threadedly engaged within appropriate threaded openings 91 in the side plate 34.

A pair of rollers 94tare rotatably mounted upon parallel axles 96 which are rigidly secured to the side plate 34 so that they are directly below and at the same distance from a common centerline through the bolts 93 when they are attached to the side plate 34. Accordingly, the Wedge 87 .or forwardly relative to the bolts 93.

An adjustment bolt 97 (FIG. 3) is slideably received through an opening 918 in the lug 99 secured to the side plate 34 near the rearward edge thereof. The bolt 97, which is parallel with the lower edge 89 of wedge 87, is threadedly received into a threaded opening 102 in the rearward end of the wedge 87. The bolt 97 can be held against axial movement relative to the lug 99 so that, by turning the bolt 97, the wedge is caused to move either rearwardly or frontwardly relative to the housing 43 `which engages the upper edge of the wedge.

The lower bearing assembly 1-8, and the parts thereof, may be and preferably are identical with the upper bearing assembly 174 and parts thereof. Accordingly, identical referance numerals in addition to the suffix A will be used in identifying parts in and associated with the bearing assembly 18 which correspond to numbered parts in and associated with the bearing assembly 17. For example, the bearing assembly 18 has a housing 43A and a spindle 57A including central, rear :and front spindle portions 58A, 59A and 77A.

The lower grinding wheel 103, in this particular embodiment, is substantially narrower axially than the grinding wheel y83. Accordingly, the front portion 77A is preferably shorter axially than the front portion 77 so that the wheel .103 can be firmly held between the flange `82A and the front portion 75A at the front end of the central portion 58A. However, the same result could be obtained by using annular spacers on opposite sides of the wheel 10:3 mounted upon a front portion 77`. In fact, this would permit the use of identical upper and lower spindle and bearing assemblies. Where spacers are not used, the length of the central portion 58A and/or the location of the housing 43A relative to the column 13 must be different than those of the central portion 58 and/ or housing 43.

The grinding Wheel 103 has a convex peripheral surface 106 which is concentric with, but of substantially lesser radius than, the radius of the concave surface `86 on the upper grinding wheel 83 in a plane defined by the axes ofthe two spindles, for reasons appearing hereinafter. Thus, the bearing and spindle assemblies 17 and 18 are arranged and constructed so that the convex surface 106 on the grinding wheel 103 extends into the concave surface 86 of the grinding wheel l83.

A pair of sheaves 107 and 108 (FIG. 7) are secured to and rotatable with the motor shaft 38 and the spindle rear portion 59, respectively, for rotation therewith and for engagement by a belt 109. In a similar manner, a pair of sheaves 112 and 113 are mounted respectively upon the motor shaft 42 and rear spindle portion 59A for rotation therewith and for engagement by a belt 114.

The slide 23 (FIGS. 2 and 4) is comprised of a pair of slide blocks 1116 and 117 which are slideably supported upon the guide bars 21 and 2.2, respectively, and are both engaged at their leftward ends by the crosshead 1118. The slide 24 is comprised of a pair of slide blocks 121 and 122 which are connected iat their rightfward ends by a crosshead 1'23. The crosshead 1118 is connected to the actuating rod 12'4 of a pressure uid operated cylinder 126 which is supported upon the pedestal 11. The crosshead 123 is connected to the actuating rod 127 of a pressure fluid operated cylinder 128 which is supported upon the pedestal 12.

A workpiece-engaging jaw 129 (FIGS. 4 and 6) is supported upon and between the rightward ends of the slide blocks 116 and 117. Specifically, the jaw 129 is comprised of a pair of L-shaped support members 132 and 1313 have ing up right flanges 134 and 135, respectively, which are secured, as by means of bolts 137 and 138, respectively, to the opposing inside surfaces of the slide blocks 116 and 117. The support members 1312 and 133 (FIG. 4) have horizontal anges 141 and 1427 which are substantially parallel and project toward, but are spaced from,

each other a distance slightly greater than the thickness of the lower grinding wheel 103.

The flanges 141 and 142 have extensions 143 and 144, respectively, which project inwardly (FIGS. 2, and 6) beyond the corresponding ends of the anges 134 and 135, respectively. A stud 146 (FIG. 6) Ais threadedly received into an axially vertical opening in the extension 143 adjacent the inner or rear edge thereof and is adjustably held in position by means of a lock nut 147. A stud 148 (FIG. 5) is threadedly received in an axially vertical opening `in the extension 144 adjacent the inner or front edge thereof, where it is adjustably held by means of a lock nut 149.

A gripping 4member 152 has an inverted, substantially U-shaped cross section, the legs 153 and 154 (FIG. 6) of which are supported upon the adjacent inner edges of the horizontal flanges 141 and 142, respectively, to which they are rigidly secured by means such as the bolts 146 shown in FIG. 5. The gripping member 152 has tive parallel, spaced openings 157 4in its leftward end (FIG. 5). Five plastic pins 159 are snugly received in the openings 157 so that the outer ends of the pins project slightly and uniformly beyond the adjacent end of the gripping member.

The rightward end of the member 152 (FIG. 4) has three integral bosses 160 which extend uniformly from said member and are uniformly spaced. These bosses may be aligned, respectively, with the axes of the upper and two lower openings 157 at the opposite end of the member. A pair of pin openings 158 are provided in the end of the member 152 between the bosses 160 and they receive plastic pins 162 which extend slightly beyond the bosses 160.

The support member 133 may be, and preferably is, identical to the `support member 132. Accordingly, corresponding numerals in addition to the suix A will be used in referring to the various parts of the support member 133 which correspond to numbered parts in the support member 132. More specifically, the horizontal flanges 141A and 142A support, and are secured to, the legs 153A and 154A of ythe gripping member 152A, which has an inverted U-shaped cross section and is preferably identical to the gripping member 152.

The gripping members 152 and 152A have been speciically designed to engage the opposite ends of a U-shaped workpiece 20, the thickness of which is somewhat greater than the thickness of the gripping members 152 and 152A. The workpiece is initially engaged at its opposite ends by the pins 162 on the gripping member 152 and the pins 159A on the gripping member 152A. If the workpiece 20 is engaged firmly, the pins 162 may compress slightly so that the workpiece 20 is ultimately also engaged by the bosses 160.

The pressure cylinders 126 and 128 are connected to and operated by a hydraulic control system appearing in FIG. 8. More specifically, the adjacent ends of the cylinders 126 and 128 are interconnected by a conduit 166 which is in turn connected to the reservoir 167. The outer end of the pressure cylinder 126 is connected by a conduit 168 through. an adjustable restricter valve 169 to a solenoid valve 172. The outer end of the pressure cylinder 128 is connected by a conduit 173 through a restricter valve 174 to the solenoid valve 17 2.

The restricter valve 169 is bypassed by a check valve 176 which permits unrestricted flow into the pressure cylinder 126. The restri-cter valve 174 is bypassed by a checkvalve 177 which permits unrestricted flow into the pressure cylinder 128. The solenoid valve 172 is arranged to alternatively connect the conduits 168 and 173 to the conduits 178 and 179 upon appropriate operation of the solenoids 182 and 183. The conduit 178 is connected to a pressure fluid pump 184 and the conduit 179 is connected to the reservoir 167. The pump 184 is connected by a conduit 186 through a strainer 187 to the reservoir 167, and the pump 184 is driven by an electric motor 188.

8 OPERATION Although the operation will be apparent to persons skilled in this art upon reading the foregoing descriptive material, such operation will be summarized brietiy hereinfater for convenience.

With the grinding machine assembled as appearing in FIGS. l and 2, and by appropriate operation of the solenoids 182 and 183 (FIG. 8), one or the other of the actuating rods 124 and 127 is caused to move slightly away from the other so that a workpiece 20 can be placed upon the studs 146, 146A and 148, 148A of the gripping members 152 and 152A. Thereafter, by appropriate operation of said solenoids 182 and 183,the gripping members 152 and 152A are caused to rmly engage the workpiece 20 therebetween. The engagement provided by the pins 162, 159A, and bosses 160 prevents rocking or wiggling of the workpiece when it is gripped, and the plastic pins, being somewhat compressible, tend ot square themselves automatically to the workpiece.

At the time of loading the workpiece 20 between the gripping members 152 and 152A, the slides 23 and 24 (FIG. 2) will be positioned either in their leftwardmost positions, as shown in FIG. 2, or in their rightwardmost positions so that the space between the gripping members 152 and 152A is readily accessible by the machine operator. The solenoids 182 and 183 are then appropriately operated so that the pressure cylinders 126 and 128 are caused to move the workpiece 20 rightwardly (FIG. 2) between the grinding wheels 83 and 103 to perform the grinding operation. During this rightward movement, escape of the pressure fluid from within the pressure cylinder 128 is restricted to that the pressure cylinder 128 creates a backpressure to the pressure cylinder 126 whereby the workpiece 20 is firmly held between the gripping members 152 and 152A. That is, pressure tiuid is not permitted to move out of one of the pressure cylinders as fast as it is being urged into the other pressure cylinder so that the pressure cylinder into which pressure tiuid is being urged by the pump 184 must always overcome a backpressure created by the other pressure cylinder.

Generally, the workpiece is moved between the grinding wheels twice, rst to the right and then back to the left. However, if additional grinding of a particular type of workpiece is required, the machine can be adapted to produce plural reciprocations of each workpiece. If the workpiece requires just one pass between the grinding wheels, reloading can be accomplished on each pass. After the grinding operation has been completed, the solenoid valves 182 and 183 are then actuated so that the gripping members 152 and 152A are moved away from each other slightly whereby the ground workpiece is released and can be removed and replaced by another.

While manual placement and removal of the workpieces 20 between the gripping members 152 and 152A may be implied from the foregoing it is contemplated that this fnction can be performed by automatic equipment, not s own.

ALTERNATE STRUCTURE The alternate griding machine 190 (FIGS. 11 and 12) has a base 191 and a pair of pedestals 192 and 193 which, generally speaking, may be similar to the base 10 and pedestals 11 and 12 of the machine 10 (FIG. 1). A co1- umn 194 (FIG. 12), similar to the column 13 (FIG. 1), is mounted upon the base 191 to support a pair of grinding wheels 196 and 197 in a manner substantially the same as described above with respect to the grinding wheels 83 and 103, respectively.

However, the guide bars 21 and 22 (FIG. 2) of the grinding machine 10 are replaced in machine 190 (FIG. 1l) by a pair of guide rails 198 and 199, which are rigidly secured to and extend between the pedestals 192 and 193. As shown in FIG. 13 and 14, the rails 198 and 199 are verticallyf elongated and have opposing grooves 202 and 203, respectively, in their upper, inner edges which extend the full length thereof. As shown in FIG. 14, the rails 198 and 199 are spaced from each other a distance slightly greater than the thickness of the lower grinding wheel 197. Thus, the grinding wheel 197 can extend upwardly between the rails 198 and 199 to engage the inner concave surface of the substantially semicylindrical workpiece 20 when the lower edges thereof are being guided along and within the grooves 202 and 203.

The upper grinding wheel 196 and lower grinding wheel 197 cooperate to simultaneously engage the upper and lower surfaces, respectively, of the workpiece 20 substantially as set forth above with respect to the grinding wheels 83 and 103. In this embodiment, however, the grinding wheels 196 and 197 are intentionally rotated in the same clockwise direction as appearing in FIG. 12 to cancel out their individual tendencies to move the workpieces in one direction. This is not essential in the machine of FIG. 1.

An intermediate rail support 204, mounted upon the base 191 between the pedestals 192 and 193, minimizes lateral deflection of the rails 198 and 199 during the operation of the alternate grinding machine 10A. Suitable nozzles 206 and 207 (FIG. 12) may be connected to a source of coolant-lubricant fluid, not shown, and directed at the grinding wheels 196 and 197 for conventional pur poses. The excess fluid can, in a substantially conventional manner, be collected in a pan 208 after which it can be filtered and returned to the supply, also in a conventional manner.

The workpieces (FIG. 12) are moved along the rails 198 and 199 by a pair of resiliently flexible drive wheels 211 and 212. The drive wheel 211, like the grinding wheel 196, has a concave peripheral surface which fits around the outer curved surface of the `workpiece 20. The lower drive wheel 212 has a convex peripheral surface which is received into the concave lower surface of each workpiece 20. The upper wheel 211 is mounted upon a shaft 213 rotatably supported by a bearing assembly 214 which is supported upon the column 194 by means of a mounting plate 216.

The lower drive wheel 212 is mounted upon a shaft 217 which is rotatably supported by the bearing assembly 218, which in turn is mounted upon the column 194 by the mounting plate 219. The gear box 222 (FIG. 13) is supported upon the column 194 between the mounting plates 216 and 219, and the output shaft 223 thereof is connected to the shaft 213 by means of the V-belt drive 224.

The shaft 217 is connected to an idler shaft 226 by gears 227 and 228, and said idler shaft 226 is also rotatably supported by the bearing assembly 218. The idler shaft 226 is connected to the output shaft 223 by means of a V-belt drive 229.

The gear box 222 is in turn driven by a motor 232, which is mounted upon the column 194. A relatively slow and adjustable rotational speed of the drive Wheels 211 and 212 can be produced by the gear box 222.

By means of the foregoing drive mechanism, the drive wheels 211 and 212 are rotated in opposite rotational directions so that their adjacent peripheral surfaces are moving in substantially the same direction as they engage opposite sides of the workpiece passing therebetween. Accordingly, the drive wheels 211 and 212 provide a positive continuons urging of the workpieces 20 along the rails 198 and 199 in a rightward direction, as appearing in FIG. 12.

If necessary, or desirable, a hydraulic actuator 233 may be mounted upon the pedestal 192 so that its piston rod 234 extends rightwardly from the pedestal for engagement with the workpieces 20 whereby said workpieces are moved along the rail into positions between the wheels 211 and 212. This arrangement would permit automatic feeding of the machine since the piston 234 could be actuated so as to permit the loading of workpieces 20 onto the rails, either individually or in groups, while the drive wheels 211 and 212 continue to urge the workpieces along the rails.

A pair of drag wheels 237 and 238, which may be substantially identical with the drive wheels 211 and 212, respectively, are secured upon shafts 239 and 240, which are supported by a bracket 241 upon the pedestal 193i. The shafts 239 and 240 are each engaged by adjustable and frictional brake means, such as that indicated at 242 in FIG. 1l, for resisting rotation of the shafts, hence, the drag wheels.

An endless conveyor belt 236 may be mounted near and beneath the righward ends of the rails 198 and 199 so that finished workpieces 20 can be discharged onto said conveyor belt and automatically carried away from the machine.

In operation, workpieces 20 are placed either individually or in groups, upon the rails 198 and 199 (FIG. ll) between the piston 234 and the drive wheels 211 and 212. The pressure applied by the pressure cylinder 233 is only sufficient to move the workpieces 20 along the rails and into engagement by the wheels 211 and 212, which furnish the primary driving force for moving the workpiece into position between the grinding wheels 196 and 197. After the desired grinding operation has been performed by the wheels 196 and 197, the workpieces are then moved by their interengagement along the rightward ends of the rails 198 and 199 until they drop therefrom onto the conveyor belt 236 which carries them away from the machine.

However, the rightward movement of the workpieces 20, after they pass the grinding Wheels, is opposed by the drag wheels 237 and 238. Thus, the group of workpieces between the drive wheels 211, 212 and the drag wheels 237, 238 are positively held in an aligned, side-byeside group which facilitates the grinding and conveying operations.

Although particular preferred embodiments of the invention are disclosed above for illustrative purposes, it Will be recognized that variations or modifications of the disclosed machines, including the rearrangement of parts, lie within the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A grinding machine comprising:

base means;

a pair of pedestals and means securing said pedestals to said base means;

a pair of bearing assemblies supported upon said base means, at least one said assemblies being adjustable toward and away from the other;

a pair of parallel spindles, one thereof being rotatably supported in, and extending from, each of said bearing assemblies;

drive means supported by said base means and connected to said spindles for rotating same;

a pair of radially aligned and peripherally adjacent grinding wheels mounted upon the extended ends of said spindles;

a pair of elongated parallel and spaced guide members extending along the opposite axial sides of said grinding wheels, said guide members being secured `to and extending between said pedestals, and said guide members extending substantially perpendicularly through the plane dened by the axes of said spindles;

a pair of slides supported on said guide members for movement lengthwise thereof and with respect to each other;

a pair of workpieceengaging jaws supported by said slides;

a pair of pressure fluid actuated cylinders mounted upon said pedestals and having actuating rods connected respectively to said slides; and

control means adapted to operate said cylinders whereby said slides are simultaneously reciprocated lengthwise of said guide members.

2. A grinding machine comprising:

column means;

a pair of pedestals and means securing said pedestals with respect to said column means;

a pair of spindle bearing assemblies mounted one above the other upon said column means, at least one of said bearing assemblies being adjustable toward and away from the other;

a pair of parallel and horizontal spindles, one thereof being rotatably supported in, and extending from, each of said bearing assemblies;

drive means on said column means connected to said spindles for rotating same;

a pair of radially aligned, peripherally adjacent grinding wheels mounted upon the extended ends of said spindles;

a pair of elongated, parallel and spaced guide members extending along the opposite axial sides of said grinding wheels, said guide members being secured to and extending between said pedestals, and said guide members extending substantially perpendicularly through the plane defined by the axes of said spindles;

a pair of slides supported on said guide members for movement lengthwise thereof and with respect to each other;

a pair of workpiece-engaging jaws supported by said slides;

a pair of pressure Huid-actuated cylinders mounted upon said pedestals and having actuating rods connected respectively to said slides; and

control means adapted to operate said cylinders whereby said slides are reciprocated lengthwise of said guide members.

3. A machine according to claim 2, wherein each slide is comprised of a pair of slide blocks mounted respectively on said guide members and a crosshead interconnecting said blocks, said actuating rods being connected tosaid crossheads and being `disposed approximately midway between and parallel with said guide members;

wherein each jaw is comprised of a pair of side members rigidly secured to the adjacent sides of said slide blocks and having substantially coplanar flanges projecting toward each other, said flanges being spaced from each other a distance slightly greater than the thickness of the lowermost grinding wheel, and a substantially U-shaped, inverted gripping member rigidly secured to said anges to pass over said lower grinding wheel. 4. A machine according to claim 3, wherein said spindle axes define a vertical plane;

wherein said lowermost grinding wheel has a convex peripheral surface and the uppermost grinding wheel has a concave peripheral surface, the space between said peripheral surfaces being the finished thickness of the workpiece; wherein said gripping member has three spaced pins embedded in each end thereof and projecting slightly and uniformly therefrom, said pins in each end being arranged at the corners of a triangle; and a pair of adjustment screws mounted in and extending above said flanges for engaging the lower surface of the workpiece on opposite sides of the lowermost grinding wheel. l 5. A grinding machine according to claim 2, wherein each bearing assembly has a bearing housing and each spindle has a central section rotatably supported within said bearing housing, said central section having a flanged end adjacent said grinding wheel, said anged end having a coaxial, circular recess and a coaxial threaded opening communicating with said circular recess;

wherein said spindle has a cylindrical section extending through a said grinding wheel and into said circular recess, said cylindrical section having a flange remote from the central section and said grinding wheel being disposed between said anged end and said remote flange;

a bolt extending through said cylindrical section and threadedly received into the threaded opening in said central section; and

key means extending between said central and cylindrical sections for preventing relative rotation therebetween when said bolt is tightened.

6. A grinding machine according to claim 5, wherein said spindle has a second cylindrical section extending into and rotatably supported by said bearing housing at the end thereof remote from said anged end, said second cylindrical section being spaced from said remote end of said central section;

key means between said second cylindrical section and said central section positively opposing relative rotation therebetween, said central section having a coaxial threaded opening in said remote end thereof; and

a second bolt extending through said second cylindrical section and threadedly received into the adjacent threaded opening in said central section, whereby said second cylindrical section is connected to, and firmly urged toward, said central section.

7. A machine according to claim 2, wherein each spindle-support assembly includes a housing having a plurality of vertically elongated bolt openings extending transversely through said housing means;

`a plurality of bolts extending through said elongated openings for rigidly, but releasably, securing said housing means to said column means;

a tapered adjustment bar having a pair of elongated openings extending therethrough, the lengthwise axes of said openings being parallel with and equidistant from the lower edge of said bar;

plural roller means supported on said column means adjacent t0 and in rolling engagement `with said lower edge of said bar; and

screw means interconnected between said bar and said column means for effecting movement of said bar relative to said column means in a direction parallel with said lower edge.

-8. In a surface treating machine having base means, workpiece positioning means mounted on said base means, wheel means adapted to engage said workpiece, and rotary drive means supported upon said base means, a bearing and spindle assembly mounted on said base means and adapted to support said wheel means for rotation by said rotary drive means, comprising:

an elongated bearing housing having a lengthwise opening therethrough of circular cross section;

first and second bearing means disposed within and adjacent the opposite ends of said lengthwise opening;

central shaft means extending through and rotatably supported within said first bearing means, said shaft means extending partially through and being rotatably supported by said second bearing means;

radially outwardly extending and annular flange means on the end of said central shaft means adjacent said first bearing means, said flange means having a circular coaxial recess therein and a coaxial threaded opening communicating with said recess;

cylindrical shaft means having a radially outwardly extending and annular flange near one end thereof, the other end thereof being snugly receivable into said recess;

key means interconnected between said central shaft means and said cylindrical shaft means positively opposing relative rotation therebetween; and

bolt means extending through said cylindrical shaft means and into said threaded opening for holding said lwheel means tightly between the flange means on said cylindrical shaft means and on said central shaft means.

9. A bearing and spindle assembly according to claim 8, including second cylindrical shaft means having a portion of reduced diameter extending into said second bear- 13 ing means, but spaced from the adjacent end of said central shaft means, said central shaft means having a coaxial threaded opening in the end thereof adjacent said second bearing means;

key means between said central shaft means and said second cylindrical shaft means positively opposing relative rotation therebetween; and

second bolt means extending through said second cylindrical shaft means and into said threaded opening for urging said second cylindrical shaft means toward said central shaft means and against said second bearing means.

10. A machine for grinding a workpiece comprising:

base means;

a pair of pedestals and means securing said pedestals to said base means;

a pair of bearing assemblies supported upon said base means, at least one of said assemblies being adjustable toward and away from the other;

a pair of parallel spindles, one thereof being rotatably supported in, and extending from, each of said bearing assemblies;

drive means supported by said base means and connected to said spindles for rotating same;

a pair of radially aligned and peripherally adjacent grinding wheels mounted upon the extended ends of said spindles;

a pair of elongated parallel and spaced guide members extending horizontally along the opposite axial sides of said grinding wheels, said guide members being secured to and extending between said pedestals, and said guide members extending substantially perpenidicularly, through the plane defined by the axes of said spindles;

a pair of drive means arranged to simultaneously engage the opposite sides of a workpiece and move same lengthwise with respect to said guide members toward said grinding Wheels; and

control means adapted to operate said pair of drive means whereby the workpiece is moved between the adjacent surfaces of said grinding wheels.

11. A grinding machine according to claim 10, wherein said pair of drive means comprise upper and lower, resiliently exible drive wheels and motor means for rotating said drive wheels in opposite rotational directions, said drive wheels being adjacent said guide members and adapted to engage the opposite sides of a workpiece supported by said guide members.

12. A grinding machine according to claim 11, including feed means for advancing a supply of said workpieces into engagement between said drive wheels.

1.3. A grinding machine according to claim 11, including upper and lower drag wheels arranged to simultaneously engage the opposite sides of a workpiece supported upon said guide members and moving away from said grinding wheels; and

means connected to said drag wheels for resisting rotation thereof whereby movement of said workpiece is opposed so that the workpieces between said drive wheels and said drag wheels are held firmly together support said wheel means for rotation by said rotary drive means, comprising:

an elongated bearing housing having a lengthwise opening therethrough of circular cross section;

lirst and second bearing means disposed within and adjacent the opposite ends of said lengthwise openma;

central shaft means extending through and rotatably supported within said first bearing means for engagement with said wheel means, said shaft means extending partially through and being rotatably supported by said second bearing means;

cylindrical shaft means having a portion of reduced diameter extending into said second bearing means, but spaced from the adjacent end of said central shaft means, said central shaft means having a coaxial threaded opening in the end thereof adja-cent said second bearing means;

key means between said central shaft means and said cylindrical shaft means positively opposing relative rotation therebetween; and

bolt means extending through said cylindrical shaft means and into said threaded opening for urging said cylindrical shaft means toward said central shaft means and against said second bearing means.

15. A machine for grinding a workpiece comprising:

base means;

a pair of pedestals and means securing said pedestals to said base means;

a pair of bearing assemblies supported upon said base means, at least one of said assemblies being adjustable toward and away from the other;

a pair of parallel spindles, one thereof being rotatably supported in, and extending from, each of said bearing assemblies;

rst drive means supported by said base means and connected to said spindles for rotating same;

a pair of radially aligned and peripherally adjacent grinding wheels mounted upon the extended ends of said spindles;

elongated guide means secured to and extending between said pedestals, said guide means extending substantially perpendicularly, through the plane dened by the axes of said spindles, said guide means being adapted to guide a plurality of workpieces, one after another, between said grinding wheels and away therefrom;

second drive means arranged to engage the workpieces, one after another, and move same lengthwise with respect to said guide means toward said grinding wheels; and

control means adapted to operate said second drive means whereby the workpieces are moved between the adjacent surfaces of said grinding wheels.

References Cited UNITED STATES PATENTS 920,943 5/1909 Forsberg Sl-S() R 961560 `6/191() Trautvetter 51--84 R 3,350,816 ll/1967 Breeding 51-80 A WILLIAM R. ARMSTRONG, Primary Examiner U.S. Cl. X.R. 51-87

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