US3290830A

US3290830A - Grinding machine

Info

Publication number: US3290830A
Application number: US327936A
Authority: US
Inventors: Ono Hiroshi
Original assignee: CONTROL GRINDING CORP
Current assignee: CONTROL GRINDING CORP
Priority date: 1963-12-04
Filing date: 1963-12-04
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13

Description

Dec. 13, 1966 HlRosHl oNo 3,290,830

GRINDING MACHINE Filed Deo. 4, 1963 5 sheets-sheet 1 Inv/nforv Haroflzz 0120 Dec. 13, T966 HlRosHl oNo GRINDNG MACHINE Filed Dec. 4. 1963 Dec. 13, 1966 HlRosHl ONO 3,290,830

@BINDING MACHINE Filed Dec. 4, 196:5

5 Sheets-Sheet 5 5 shets-sheetf 4 "Filed Dec. 4. 196s n 5 6 0 0 1, W Wn f6.4@ r J a lm W sHlHHHIv .L mm w `v [j 7 j h w m 8 3 1 8 m w3 d o 9. M m o, j; w, f fx 6 ./89 8 l\ 02 d 6 9 Dec. 13, 1966 HlRosl-n ONO 3,290,830

GRINDING MACHINE Filednec. 4. 1963 5 sheets-sheet 5 United States Patent O 3,290,830 GRINDING MACHINE Hiroshi Ono, Chicago, Ill., assignor to Control Grinding Corporation, Chicago, Ill., a corporation of Illinois Filed Dec. 4, 1963, Ser. No. 327,936 14 Claims. (Cl. 51-103) This application is a continuation-in-part of my copending application Ser. No. 240,796, tiled Nov. 29, 1962, now abandoned.

The present invention relates to a novel grinder and more particularly to a grinding machine having a novel workpiece supporting and driving assembly, .a novel grinding wheel supporting assembly and also to a novel dressing tool assembly. Also, the present invention relates to a novel method of operation of a grinding wheel so as to automatically engage and remove the grinding wheel from the workpiece and dress the grinding wheel to the proper size for repetitive cycles of grinding.

The conventional cylindrical grinders presently in use support the workpiece on two centers; or in a collet or chuck .at one end and a center at the opposite end; or in a collet or chu-ck without a support at the opposite end; or on a mandrel where the item involves a sleeve or bushing. In more specialized machines, adjustable supports such as spiders or bearing blocks may be utilized. However, these machines are basically made for the grinding of surfaces other than the surface supporting the workpiece; thus the grinding surfa-ce or area is limited in any grinding operation.

All of these present machines and methods of grinding and supporting the work involve one or more disadvantages which limit their usefulness. For example, if the workpiece is supported on centers, the space for the centers on the ends of the shaft must be provided, center holes have to be .machined in the ends, cleaned and/or checked before insertion into the grinder and a drive attachment such as a dog must be secured to one end of the workpiece -and the drive mechanism of the machine. Also, the machine must be provided with means to receive the centers of the workpiece and, as this usually involves a sliding spring-loaded assembly, such an assembly becomes a source for inaccuracies.

. If a collet or chuck is utilized for holding the workpiece, concentricity and'axial parallelism is difiicult to control. To use spiders or bearing blocks requires workpiece surfaces that are round and smooth before insertion into the grinder and, in many instances, surfaces are required of extreme uniformity in diameter.

The present invention involving the novel support and driving system eliminates or minimizes the need -for the care Iand attention and the inaccuracies associated with or inherent in other known grinding systems. This novel support and driving system provides a rigid support system for a workpiece involving one or more upwardly opening generally V-shaped supports upon which the workpiece rests and a drive member frictionally engaging the workpiece and rotating to cause rotation of the workpiece and urge the workpiece into continuous engagement with the supports.

An important object of the present invention is the provision of a novel support for a cylindrical grinder providing a rigid support for a workpiece to reduce the inaccuracies of the grinding operation and eliminate the necessity for centers on the workpiece. This support has an upwardly opening generally V-shaped notch within which the workpiece rests and rotates relative to the support.

Another object of the present invention is the provision of a workpiece support which provides a more convenient arrangement and system for the insertion or re- Patented Dec. 13, 1966 ICC moval of the workpiece into land from the grinder. This support also decreases the time required to complete -a grinding cycle of the machine.

A further object of the present invention is the provision of a novel work support which is utilized when the supported surface area of the workpiece is to be ground to size and provide a cylindrical surface. This support has a generally V-shaped upwardly opening notch therein, but one lobe of the notch lies in a vertical plane and the other lobe lies in a plane which is angularly disposed to the first lobe. The vertical lobe provides a support surface diametrically opposite the grinding surface of the abrasive wheel which has been found necessary in generating a round surface.

Another object of the present invention is the provision of a novel driving mechanism to rotate the workpiece and constantly urge the workpiece onto its supports. This driving .mechanism provides -a rotatable drive wheel which frictionally contacts the cylindrical surface of the workpiece causing its rotation and urges the workpiece downwar-d onto the supports.

The present invention also comprehends the provision of a novel driving mechanism for the workpiece utilizing two drive wheels positioned on diametrically opposite sides of the workpiece. The double drive wheel system is particularly adapted for use where a greater amount of torque is required to rotate the workpiece against the force of the abrasive wheel than can be normally generated with a single drive wheel. The two drive wheels operate at equal angular velocities but at different tangential velocities to rotate the workpiece `and urge the workpiece downward into the spaced supports.

The present invention further comprehends the provision of a novel supporting arrangement for an abrasive wheel to provide -a smoother approach path and greater accuracies into the workpiece. Rather than moving the grinding wheel directly into the workpiece in a horizontal plane perpendicular to the axis thereof, the wheel is mounted on an arm or support which in turn is pivotally mounted on the machine. The wheel moves in an arc from behind and below the work to approach the work and moves substantially tangentially into the surface to be ground. Another object of the present invention is the provision of a dressing tool for the grinding wheel which dresses and sizes the wheel before each grinding operation. This dressing tool is stationarily mounted on the reciprocating table of the grinder yand the grinding wheel is moved into engagement with the tool just prior to the beginning of a grinding cycle.

A further object of the present invention is the provision of a drive system, work supports and abrasive wheel mounting and dressing system which not only can be utilized for a cylindrical grinder, but which are adapted for use on conventional surface grinders, thread grinders, centerless grinders and universal grinders as well as other types of machines for working with metals.

The present invention also comprehends the provision of a novel operational cycle for the grinder for repetitive work with each workpiece being ground to exact size. This method of operation includes the steps of bringing the abrasive wheel substantially tangentially into the workpiece, moving the workpiece laterally relative to the wheel, removing the wheel substantially tangentially from the workpiece, and dressing and sizing the wheel for the next cycle.

The present invention further comprehends a novel grinder cycle of operation for repetitive work to grind a limited area on a workpiece including the steps of bringing the abrasive wheel substantially tangentially into the work, removing the abrasive wheel from the work,

*movably secured or carried the incrementally feeding the wheel inwardly and passing a dressing attachment past thev abrasive wheel to dress the wheel for the next grinding cycle.

Further objects are to provide a construction of maximum simplicity, eiiiciency, economy, and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

In the drawings:

FIGURE 1 is a side elevational view of the grinding machine embodying the novel work supports, workpiece driving means, pivotal support arrangement for the abrasive wheel and dressing tool attachment.

FIG. 2 is a partial top plan view of the grinding machine shown in FIG. 1 with the abrasive wheel assembly omitted.

FIG. 3 is a partial front elevational View of the grinding machine.

FIG. 4 is an enlarged side elevational view of one work support, the mounting for the drive wheel and a partial vertical cross sectional view of the dressing tool assembly.

FIG. 5 is a side view, partially in vertical cross section, of the other work support of FIGS. 1 to 3.

FIG. 6 is a partial horizontal cross sectional view taken on the line 6 6 of FIG. 5.

FIG. 7 is a vertical cross sectional View of the support for the drive wheel shown in FIGS. 1 to 3 disclosing the actuating system for moving the drive wheel to and from the work.

FIG. 8 is a partial top plan view of a grinding machine with the alternate workpiece driving assembly utilizing a pair of drive wheels.

FIG. 9 is a partial side elevational View of the pair of drive wheels, workpiece and support.

FIG. 10 is an end elevational view, partially in vertical cross section of the drive assembly for operating the drive wheel or wheels.

FIG. 11 is a view partially in vertical cross section taken on the line 11-11 of FIG. 10.

FIG. 12 is a perspective view of an alternate embodiment of the abrasive wheel supporting assembly utilizing a tangential slide mounting for the abrasive wheel.

Referring more particularly to the disclosure in the drawings wherein are shown the illustrative embodiments of the present invention, FIGS. 1 to 3 disclose a grinding machine 10 having a stationary base 11 with a sliding member or table 12 reciprocatory sliding movement.

Mounted on the table 12 is a swivelled mounting table 13 upon which is resupports and driving mechanism for a workpiece 14. The table 13 contains longitudinal slots 15 which are an inverted T-shape in cross section for the heads of the bolts used to secure the various members to the table. Also, suitable driving means is connected to the table 13 for reciprocatory movement and-other adjustments as are well known in the art.

The workpiece supporting means comprises at least one V-support 16 positioned in such a way as to support the workpiece 14 in a horizontal plane and substantially parallel -to the spindle of a grinding wheel assembly 17. The support 16 includes a mounting block 18 which is adjustably secured to the table 13 by one or more bolts 19. Each block 1S has a dovetail slide 21 on its upper horizontal surface cooperating with a complementary groove in the adjusting block 22 mounted for horizontal adjustment toward and away from the assembly 17. The block 22 is hollow in part and is provided with a clamping plate 23 therein, which plate is secured to a threaded stem 24 (see FIG. 6) cooperating with an internally threaded sleeve 25. The sleeve terminates in an exposed knob 26 which is actuated by a suitable tool. The plate 23 has angled surfaces 27, one of which engages block 22 and the other contacts the edge surface of a vertical supmounted thereon for longitudinalported plate 28 of the work support 16. The plate is mounted in a complementary groove or slot 29 1n the block 22 and is adapted to be vertically adjustable there- The plate terminates at its upper end in a rearwardly extending portion 31 which carries the upwardly opening notch 32 having lobes with contact surfaces 33a and 33h. The notch 32 is positioned rearwardly away from the vertical support or plate 28 to provide free access for the grinding wheel assembly 17. The contact surfaces 33a and 33b when extended form substantially equal angles with a line extending from the point of contact between the workpiece 14 and the abrasive wheel through the center of the workpiece.

Each support 16 is adjustable longitudinally of the table 13, vertically relative to the table in the adjusting block 22 and horizontally toward and away from the grinding wheel assembly 17 through the slide 21. These adjustments are all important to provide adequate adjustment depending upon the tolerance in roundness and diameter of the workpiece to be ground and the desired conguration of the finished workpiece. Further, it is important to have the lobes of the support 16 forming substantially equal angles with a vertical plane through the vertex of the notch 32 so that any variations in the roundness of the supported surface of the workpiece will be translated in a slight vertical variation in the axis of the workpiece at that support and not into variations of movement toward and away from the grinding wheel assembly.

Although two identical supports 16 may be utilized where grinding occurs on a non-supported surface of the workpiece 14, the machine in FIGS. 1 to 4 discloses a second embodiment of support 34 utilized when the surface 35 of the workpiece 14 contacting the support 34 is to be ground. This support is used so that the surface 35 may be ground accurately to a round cylindrical surface without degeneration into a many-sided geometrical figure. The support 34 includes an identical mounting block 18 having a horizontal dovetail slide 21 for an adjusting block 36. A vertical support or plate 37 is clamped in the same manner as shown in FIG. 6 for vertical adjustment, but the plate 37 is provided with a rearwardly and upwardly extending arm or lobe 38 with an angularly positioned contact surface 39.

The opposite side of the plate 37 is cut away to provide space for a horizontally adjustable plate 41 having at its inner end a vertical contact surface 42. This plate 41 has a horizontal base 43 with a dovetail slide 44 mounted in a complementary slot in the upper surface of the block 36 and a depending arm 45 (see FIG. 3) which is received in the slotted upper end 46 of the block 36 with a suitable clamping member 47 to securely retain the plate 41 in horizontally adjusted position.

The contact surface 39 is positioned so that the point of engagement with the workpiece 14 is diametrically opposed to the point of contact between the workpiece and drive wheel to be later described. Similarly, the point of contact of the vertical surface 42 with the workpiece 14 is diametrically opposed to the point of contact between the workpiece and the abrasive wheel at the nal grinding position. This positioning of the vertical surface 42 relative to the abrasive wheel has been found to be very important in the generation of a round surface on the supported surface 35 of the workpiece 14. Although this support 34 is described for the instance where the supported surface 35 of the workpiece is to be ground, other specialized conditions of grinding may require the use of this work support.

A stop member 48 is mounted at one or Iboth ends of the workpiece 14 to prevent axial movement thereof during a grinding operation. Such a stop member is preferably adjustable to provide for changes in the length of the workpieces. The location of the stop member depends on the action of the axial force derived from the work driving mechanism 49 rotating the workpiece.

The driving mechanism 49 (as seen in FIGS. 2 and 3) provides rotation for the workpiece 14 during grinding and includes a base member 51 adjustably mounted on the table 13 by one or more suitable bolts 52 and extends transversely across the table at one end thereof. Mounted on the end of the base member 51 away from the grinding wheel assembly 17 is a drive motor assembly 53 including an electrically or uid actuated motor. As more clearly shown in FIGS. l0 and ll, the motor drives a shaft having a gear 54 thereon which meshes with a spiral gear 55 mounted on a drive shaft 56 which extends parallel to the base member 51 and through the drive motor assembly and a pair of

drive wheel assemblies

57 and 57a. The two assemblies 57 and 572L are identical and only one assembly will be described with like reference numerals identifying the elements of the other assembly.

The drive wheel assembly includes a base 58 having a dovetail member 59 depending from the base and adapted to be slidably mounted in a complementary channel in the base member 51. An internally threaded opening 61 extends axially through the dovetail member 59 to receive an elongated threaded adjusting screw 62 extending through the drive motor assembly 53 and the

bases

58, 58 to adjust the

drive wheel assemblies

57 and 57a relative to the table 13 and to the workpiece 14. A pair of parallel stationary brackets 63 are secured to and extend upwardly from the base 58, and each bracket is provided with a rounded upper edge 64 and a circular opening 65 through which the drive shaft 56 extends. An end cap 66 is mounted in each opening 65 and receives a reduced end of a sleeve 67 keyed to the shaft 56 by a key 68. A sealing gasket 69 is mounted between the end of the sleeve 67 and the end cap 66. A worm 71 is secured to the sleeve 67 and the sleeve is rotatably mounted in the end cap through roller bearings '72.

A pivotal housing 73 is secured to the end caps 66, 66 and pivots relative to the stationary brackets 63. The housing has a base member 74, a pair of end members 75 and a curved cover 76 all secured together (see FIG. 11). A worm gear 77 meshing with the worm 71 is rotatably mounted in the end members 75 through` roller bearings 78 and sealing gaskets 79 seal the extended ends 81 of the gear in the end member 75. A drive wheel shaft or spindle 82 is extended through and is keyed to the worm gear 77. The housing 73 is adjustably held against pivotal movement by suitable screws 83 (FIG. ll). As can be seen by these drawings, rotation of the motor causes rotation of the spur gear 54 and the spiral gear 55, drive shaft 56, worm 71, worm gear 77 and drive wheel shaft.

In the grinding machine shown in FIGS. 1 to 4, a single drive wheel or disc 84 is utilized to frictionally engage and rotate Vthe workpiece 14. The wheel 84 has its periphery covered with a facing 85 of neoprene or other suitable material to enhance frictional engagement with the workpiece 14. The shaft or spindle 82 may have one or more universal joints 86 therein so that the spindle portion carrying the disc 84 is substantially parallel to the longitudinal axis of the workpiece 14. The disc 84 is positioned so as to be diametrically opposite the contact or lobe 33b and surface 39 supporting the workpiece 14. A slight angular displacement between the axis of the drive wheel and the longitudinal axis of the workpiece is necessary if it is desired that the workpiece be urged axially against the stop 48. For rotation of the disc 84 in the direction of the arrow shown in FIG. 1, the angle has to be positive for an axial force in the direction shown by arrow 87 in FIG. 2.

The spindle or shaft 82 for the disc 84 is rotatably mounted in a bearing lblock 89 in a drive Wheel support assembly 88 having abase 91 connected to the table 13 by suitable bolts 92. The base 91 has an upwardly extending portion terminating in a horizontally disposed housing 93 which extends toward the workpiece 14. The

housing includes a hollow cylinder 94 for a piston 95 reciprocable therein. An end cap 96 closes the cylinder 94 and provides a passage 97 from a nipple 98 for the entrance or egress of oil or other fluid actuating the piston 95. A generally horizontal link 99 is secured at one end to the piston and at the opposite end to a generally vertical link 101 secured at its lower'end to a rod 102 which extends from both sides of the housing 93. An end cap 103 closes the housing at its inner end.

A compression spring 104 is mounted in the cylinder 94 with one end abutting the piston 95 and the opposite end abutting a ange or ring 105 in the cylinder 94; both the spring and flange surrounding the link 99. An angularly positioned slide 106 having a dovetail 107 thereon has a pair of spaced or bifurcated arms 108 depending therefrom with the lower ends of the arms secured to the extended ends of the rod or shaft 102. An adjustable block 109 having a complementary groove receiving the dovetail 107 has a split upper portion 111 with a passage or opening 112 to receive a cylindrical projection 113 on the bearing block 89. A clamping screw or bolt 114 extends through the portion 111 to clamp the projection 113 therein. This clamping arrangement provides for the angular displacement of the axis of the drive disc 84 relative to the longitudinal axis of the workpiece 14 to create the axial force urging the workpiece against the stop 48.

A threaded spindle 115 extends parallel to the dovetail 107 and threadingly engages and extends through the adjustable block 109. The spindle is rotatably mounted in a flange 116 secured to the slide 106 and a handwheel 117 is mounted on the opposite end of the spindle to alter the position of the adjustable block 109.

In operation, iluid pressure exerted on the piston 95 in the cylinder 94 urges the link 99 rearwardly to rotate the rod 102 and arms 108 in a clockwise direction, as seen in FIG. 7, to urge the disc 84 against the workpiece 14. When the fluid pressure is terminated, the spring 104 urges the piston in the opposite direction to move the drive disc 84 away from the workpiece 14 so that the finished workpiece may be removed from the supports and another substituted therefor.

At the opposite end of the table 13 is mounted a dressing tool assembly 118 for dressing and sizing the abrasive wheel after each grinding cycle. This assembly includes a base member 119 adapted to be secured to the table 13 by a bolt or other suitable fastener 121. Pivotally mounted on the base as at 122 is an adjustable arm 12.3. A depending rod 124 is pivotally mounted in the arm at 125 adjacent to the pivot 122 and .extends into an opening 126 in the base where it terminates in an enlarged head 127. A helical compression spring 128 has one end bearing on the head 127 and the opposite end bearing against a shoulder 129 formed adjacent the upper end of the opening 126. i

The free end 131 of the arm 123 rests upon the upper end of an adjustable rod or spindle 132. The housing or barrel 133 for the rod is mounted in the base 119 and with a knurled handle or thimble 134 provides a micrometerlike adjustment of the rod 132. The opposite end of the arm 123 extends beyond the pivot 122 and terminates in an enlarged circular portion having a transverse opening 135 therein. A shaft 136 is secured at one end by suitable means in the opening 135 `and car-ries the dressing tool 137 at its opposite end with the dressing tool extending inward toward the grinding wheel assembly 17 (FIG. l).

The grinding wheel assembly includes a spindle base or bed 138 mounted on the machine base 11 and movable toward `and away from the table 13 due to a rack 139 and pinion 141 with the pinion extending downward through the base 11 for connection to a suitable incremental drive means such as a motor 140. An abrasive wheel 142 is shown mounted at one end of a rotatable shaft or spindle 143 with a pulley 144 mounted at the opposite end. The spindle is rotatably mounted in suitable bearing means secured to a pivotally mounted frame orsupport 145 upon which also is secured a motor 146. The motor drives a pulley 147 and rotates the spindle 143 and the abrasive wheel 142 through a drive belt 148 extending between the pulleys 144 and 147.

A pivot pin or shaft 149 is mounted to extend between two arms 151 projecting upward from the base 138. The support 145 has a bearing member which is mounted on the shaft 149 to allow for pivotal movement of the support 145 and abrasive wheel 142 relative to the base 138 from a position below and behind the work to a position contacting the work.

A cam means 152 is utilized with the pivotally mounted grinding wheel assembly 17 toprovide the desired cycle of operation of the abrasive wheel 142 into and away from the work. A cam follower or roller 153 is mounted in a bracket 154 secured to the base 138 and cooperates with a rotatable cam 155. This cam is mounted on a shaft 156 rotatably mounted in the support 146. A worm gear 157 is keyed to the shaft 156 and operatively engages a worm 158 on a shaft 159 of a motor 161. The cam 155 is generally symmetrical with an irregular contour and is positioned above the cam roller 154 so that rotation of the cam 155 will lift and lower the support 145 around the pivot pin 149.

The shape of the cam 155 provides for a rapid initial movement of the abrasive wheel 142 up to but not contacting the workpiece, a slow movement as the wheel 142 engages the work to a position where the longitudinal axis of the workpiece 14, the axis of the wheel 142 and the pivot pin 149 are in alignment, a slow downward movement to disengage the abrasive wheel from the workpiece followed by a rapid downward movement to the lowest portion of ther abrasive wheel and then a pause to allow lateral movement of the table before starting another cycle.

A switch 162 has an arm 163 adapted to engage projections 164 on the worm gear 157 to stop the movement of the abrasive wheel 142 in its fully raised position where substantial transverse movement of the table 12 is required for grinding a substantial area of the workpiece. The switch 162 is connected to suitable means controlling operation of the motor 161.

In operation, the motor assembly 53 drives the drive wheel 84 to rotate the workpiece 14 and urge the workpiece into contact with the supports 16. The motor 146 rotates the abrasive wheel 142 at suitable speeds for grinding. When -the motor 161 is started to drive the cam 155, the abrasive wheel is moved into engagement with the workpiece 14. The use of the supports 16 make it possible to grind ,the surfaces of the workpiece which are not in contact therewith to a predetermined diameter even with minor variations in the diameter of the surfaces 35 `directly contacting the supports as long as the grinding surface 165 of the abrasive wheel 142 is always in the same finalposition relative to the supports. Geometrically it can be shown that for practical variations of the diameter of the surfaces 35, the differences in radius of the surface of the workpiece would be insignificant. Further, the positioning of the supports eliminates the tendency to grind a taper on the workpiece.

By the use of a single pivot point 149 for the suspension of the grinding wheel spindle assembly, it is possible to remove the abrasive wheel 142 away from one workpiece 14 for removal of that piece and insertion of another workpiece and then engage the grinding wheel with the new workpiece with very high repetitive accuracy. If no other part of the machine is disturbed, the two possible sources of repetitive error are in the pivot pin 149 and in the positioning of the cam means 152. The bearing engaging pin 149 can easily be arranged to have no play for all purposes because of its construction and the only error will then occur in the positioning of the abrasive wheel 142 by the cam means 152. If the center of the workpiece 13, the center of the grinding wheel spindle 143 and the center of the pin 149 are all in one approximate straight line, then the radial difference of the workpiece `due to small errors in the positioning of the grinding wheel can be determined geometrically to be very close to zero and of no practical signicance.

This method of suspension of the grinding wheel 142 and its spindle 143 makes it possible to eliminate the expensive and precision lead screws, slides, cogs and levers that are found on more conventional machines. Also, this suspension provides an easy and Arapid system for movement of the grinding wheel away from the workpiece and into a position for dressing and sizing with the prepositioned dressing tool 137.

It can be seen that the suspension with the pivot pin 149 results in the desired engagement action, and if the center distance between the spindle 143 and the pivot pin 149 were increased to approach infinity, the engagement action would approach a tangential sliding action.

It should be noted that at the fin-a1 grinding position for the abrasive wheel 142, the axis of the workpiece 14, the point of contact between the workpiece and the abrasive wheel 142, and the axis of the abrasive wheel are all aligned in `a horizontal plane as seen in FIG. 1. Further, when the abrasive wheel 142 is at its rest position away from the workpiece 14, the axis of the abrasive wheel 142 and the axis of the dressing tool 137 are aligned in a horizontal plane. This latter alignment is necessary to properly dress the wheel 142 after an incremental in-feed of the wheel through the rack 139 and pinion 141 so that repetitive grinding cycles are uniform. To provide for a consistent horizontal alignment of the abrasive wheel axis with the dressing tool, an adjustable stop membr 166 is mounted -on the base 138 and adapted to engage an abutment 167 formed on the under surface of the pivoted support 145.

Utilizing the above described structure, a novel method of semi-automatic or automatic operation may be -obtained to repetitively grind successive workpieces. A suitable drive motor is secured to the pinion 141 to rotate the pinion for a small increment of rotation each time that the abrasive wheel is lowered to its inoperative position. The predetermined increment of rotation of the pinion 141 actuates the rack 139 to incrementally advance the grinding wheel assembly 17 relative to and toward the

supports

16 and 34 and the dressing tool assembly 118 mounted on the table 13 for the dressing operation. A crank assembly is shown to reciprocate the tables 12 and 13.

At the start of a cycle of operation, the abrasive wheel 142 is retracted and the table 12 may be at either end of its reciprocatory movement depending on the operating cycle desired. If only a small area of the workpiece 14 is to be ground so that reciprocation of the table 12 during actual grinding is not required, the cycle comprises four stages: l) Upward movement of the grinding wheel into the work; (2) downward lmovement to disengage the abrasive wheel from the work; (3) simultaneous or separate left or right movement ofthe table and incremental in-feed of the abrasive wheel with the dressing -tool on the table passing across the face of wheel for dressing; and (4) return movement of the table in the opposite direction to its initial position preparatory to grinding.

If a substantial surface area is to be ground, the table 12 is positioned at the right hand end of its reciprocatory movement as seen in FIG. 1. This grinding operation comprises another four stage cycle: 1) Upward movement of the abrasive wheel 142 into grinding engagement with the workpiece 14; (2) the abrasive wheel is held in its raised position as the table 12 carrying the supports, workpiece drive system and dressing tool assembly moves to the left so that the wheel 142 passes over the work` piece being ground and beyond the dressing tool assembly; (3) downward movement of the abrasive wheel -followed by incremental in-feed of the abrasive wheel; and (4) movement of the table 12 to the right which causes the dressing tool 137 to pass across the face of the abrasive wheel to dress it as the wheel moves back to its initial position. The rapid and then slow movement of the abrasive wheel into the work and the slow aud then rapid movement away from the work provides a slow movement when the abrasive wheel engages the workpiece to prevent grooving or otherwise marring the workpiece by movement of the wheel.

Obviously, other suitable drive assemblies may be substituted for the illustrated drive assemblies for the table 12 and the movement of the abrasive wheel 142.

An alternate embodiment of drive means for the workpiece 14 is shown in FIGS. 8 and 9. In many cases the torque to drive the workpiece shaft against the force created by rotation of the abrasive wheel 142 must be increased. Utilizing the single drive wheel 84 to increase the torque applied to the workpiece 14, the wheel is moved toward and against the work to exert greater force upon the surface of the workpiece. The greater force applied on the wheel 84 gives greater traction between the drive wheel and the workpiece so as to increase the torque, but this also results in greater friction between the workpiece and the

supports

16 and 34. Therefore, a point is reached where the application of greater force on the drive wheel 84 will not result in an efficient increase in torque.

When greater torque is required than can be efficiently created by the single drive wheel 84, a double drive wheel system is used. This drive system utilizes the identical drive motor assembly 53 shown in FIGS. 1() and 1l, utilizing both

drive wheel assemblies

57 and 57a. Each

assembly

57, 57a drives a drive wheel shaft or spindle 82, 82a, respectively. A pair of neoprene covered

discs

169, 169"L are mounted on the spindles 82, 82a with the discs rigidly displaced approximately 180 apart as measured from the center of the spindle of one disc 169 to the center of the workpiece 14 and then to the center of the other disc 169e. Both discs are positioned relative to the supports 16 such that the point of contact of the supports and the workpiece 14 form approximately equal angles to the point of contact between the discs 169, 169a and the workpiece.

The diameter of the disc 169A is slightly greater than that for disc 169ab and the angular velocity of the discs will be equal for both spindles 82, 82a as they are driven by a common drive shaft 56. Thus, the tangential velocity of disc 169 will be greater than that of disc 169a and, with the discs rotating in the directions shown by the -arrows in FIG. 9, the workpiece 14 will be rotated as shown by the arrow and simultaneously forced downward into the supports due to the tangential velocity differences between the discs. If the direction of rotation of the discs is reversed, but retaining equal angular velocities, the difference in tangential velocities will create forces to remove the workpiece from engagement with the supports, and thus accomplish removal of the workpiece from the grinder.

The axial force necessary to position the workpiece 14 axially against a stop 48 is created by a small angular displacement between the polar axis of the discs 169, 1695' and the longitudinal axis for the workpiece 14 as previously described for the drive disc 84. The forces exerted upon the workpiece 14 by the drive discs 169, 169a are `all in a substantially horizontal plane and thus there is no substantial force from the discs acting to force the workpiece into the supports except due to the difference in tangential velocity of the discs. Therefore, increasing the force exerted by the discs on the workpiece 14 to increase the developed torque does not increase the frictional forces in the manner described for the single drive disc 84.

FIG. l2 relates to a tangential slide assembly 171 supporting and moving the grinding wheel assembly 17. As previously stated, the distance between the center of the grinding wheel spindle 143 and the pivot pin 151 may be increased to approach infinity and the arc of move- 1@ ment of the abrasive wheel 142 approaches a tangential slide. In the assembly 171, the abrasive wheel 142 is mounted on its spindle 143 and is driven by a motor 146. These components are mounted on a slide 172 which operates in a track 173 of a substantially vertical support 174. A feed screw 175 in the support has a handwheel 176 at its upper end for manual operation and a reversible motor is located within the support 174 to automatically move the grinding wheel tangentially into and out of grinding contact with the workpiece 14. Automatic controls contemplated for the feed screw are known in the art and are not illustrated here.

It is obvious that the support for the workpiece and for the grinding wheel and the embodiment of drive means for the workpiece may be easily embodied in a semi-automatic or automatic machine operation by utilizing a suitable control system designed to give control and coordination of the various functions.

While the various features have been shown and described as being advantageously applicable to grinding operations, it is not my desire or intent to unnecessarily limit the scope or 4the utility of the improved features by virtue of these illustrative embodiments.

Having thus disclosed the invention, I claim:

1. In a grinder, a pair of supports for supporting a workpiece, each support including an upwardly opening generally V-shaped notch adapted to receive the workpiece and providing a pair of contact lobes, at least one of said supports lhaving a substantially vertical contact lobe and an angularly arranged contact lobe, at least one drive wheel frictionally engaging the surface of the workpiece to rotate the same and positioned to Contact the surface of the workpiece at a point diametrically opposite to the point of contact of the workpiece with one contact lobe of a support, and an abrasive wheel adapted to arcuately swing into substantially tangential engagement with the workpiece and contact the workpiece at a point approximately diametrically opposite to the point of contact of the workpiece with the vertical lobe of the support.

2. In a grinder, a pair of supports for a workpiece, an abrasive wheel adapted to engage the workpiece, and a pair of drive wheels positioned to contact substantially diametrically opposite sides of the workpiece at a point spaced from said abrasive wheel and between said supports, said supports being positioned generally below the workpiece and the drive wheels, said drive wheels being simultaneously rotated in the same direction but one wheel having a greater tangential speed than the other so that said drive wheels rotate the workpiece and urge it downwardly into -the supports.

3. In a grinder as set forth in lclaim 2, in which the drive wheel having a greater tangential speed has a diameter slightly greater than the other drive wheel.

4. In a grinder as set forth in claim 2, in which reverse rotation of said drive wheels removes the workpiece from the work supports.

5. In a grinder, a pair of spaced supports for a workpiece, a pair of drive wheels positioned to contact substantially diametrically opposite sides of the workpiece, said drive wheels being simultaneously rotated in the same direction but one wheel having a greater tangential speed than the other so that said drive wheels rotate the workpiece and urge it downwardly into the supports, a pair of drive shafts for the drive wheels, a pair of drive wheel assemblies operated simultaneously from a single drive motor, each drive wheel assembly connected to and rotating one of said drive shafts, and means to angularly adjust said drive wheel assemblies and drive shafts.

6. In a grinder, a pair of spaced supports for a workpiece and a pair of drive wheels positioned to contact substantially diametrically opposite sides of the workpiece, said drive wheels being simultaneously rotated in the same direction but one wheel having a greater tangential speed than the other so that said drive wheels rotate the workpiece and urge it downwardly into the supports, said supports having upwardly opening generally V-shaped notches, and at least one of said supports is provided with an upwardly opening generally V-shaped notch having a substantially vertical lobe and a lobe positioned at an acute angle relative to the vertical lobe, said last-mentioned support including a block, an elongated plate mounted in said block for horizontal adjustment and having a flat contact surface at one end forming the vertical contact lobe, and a vertically adjustable plate mounted' in said block and terminating at its upper end in a point having a vertical surface and an angular surface forming the angular contact lobe.

7. In a grinder as set forth in claim 6, in which said horizontally adjustable plate has a vertical surface intersecting an angularly arranged surface which is generally parallel to the angular lobe of the vertically adjustable plate, said workpiece being supported on said lobes such that the surface contacting the lobes is also exposed to contact by an abrasive wheel.

S. In a grinder, a rotatable spindle, an abrasive wheel mounted on the spindle, support means for the spindle, means to rotate said spindle and abrasive wheel, a support carrying said supporting means at one end, a pivotal mounting for the opposite endl of the support, means to move said support and said abrasive wheel in an arcuate path into and away from substantially tangential engagement with a workpiece, a slide member carrying the pivotal mounting for the support, stop means adapted to limit movement of the support to a predetermined inactive position for the abrasive wheel, and a dressing tool adapted to dress the grinding surface of the abrasive wheel when it is in its inactive position.

9. In a grinder as set forth in claim 8, including means to move the dressing to'ol transversely to said abrasive wheel, and means to incrementally move the slide member toward the workpiece for intermittently dressing the abrasive wheel.

10. In a grinder as set forth in claim 9, in which said means to move the dressing tool includes a table assemlbly mounted for horizontal reciprocation transversely of said abrasive wheel, said table carrying the workpiece and the dressing tool spaced therefrom, said abrasive wheel moving in an arcuate path from an inactive position below and behind the workpiece Where the wheel is aligned with the dressing tool to a grinding position where the longitudinal axis of -the workpiece, the axis of the spindle supporting the abrasive wheel and the axis of the pivotal mounting for the support all lie on a straight line.

11. In a grinder as set forth in claim 10, in which said stop means limits downward movement of the abrasive wheel to a predetermined position relative to said dressing tool.

12. In a grinder as set forth in claim 10, in which said dressing tool includes a base member secured to the table assembly, an adjustable arm pivotally mounted on the base, a dressing ltool secured to the inner end of the arm, and adjustment means in the base cooperating with the outer end of the arm.

13. In a grinder as set forth in claim 12, in which said pivotal connection between the base and the arm includes a rod pivotally mounted on the arm, said base having a recess, said rod depending into the recess and terminating in an enlarged head, a compression spring in said recess biasing the head downward, and a pivot adjacent the rod between the arm and the base.

14. In a grinder as set forth in claim 10, including a pair of work supports mounted on said table assembly, each support having an upwardly opening generally V-shaped notch, at least one of said supports having a vertical contact lobe opposite said abrasive wheel and an angularly arranged contact lobe forming the notch.

References Cited by the Examiner UNITED STATES PATENTS 1,421,133 6/1922 Albertson.

1,473,520 11/1923 Rosak 51--165 X 1,976,110 10/1934 Binns 51-103 2,028,315 1/1936 Bruhl et al. 51-105 2,179,714 11/1939 Davis 51-236 2,411,972 12/1946 Melin 519-236 X 2,598,679 6/1952 Dryer 51-289 2,719,391 10/1955 Brown 51-236 2,872,757 2/1959 Ekholm 51-103 2,896,377 7/1959 Walkling 51-103 3,056,243 10/ 1962 Flanders 51-289 3,094,817 6/1963 Bartholomew 51-103 FOREIGN PATENTS 1,090,900 4/ 1955 France.

LESTER M. SWINGLE, Primary Examiner.

Claims

2. IN A GRINDER, A PAIR OF SUPPORTS FOR A WORKPIECE, AN ABRASIVE WHEEL ADAPTED TO ENGAGE THE WORKPIECE, AND A PAIR OF DRIVE WHEELS POSITIONED TO CONTACT SUBSTANTIALLY DIAMETRICALLY OPPOSITE SIDES OF THE WORKPIECE AT A POINT SPACED FROM SAID ABRASIVE WHEEL AND BETWEEN SAID SUPPORTS, SAID SUPPORTS BEING POSITIONED GENERALLY BELOW THE WORKPIECE AND THE DRIVE WHEELS, SAID DRIVE WHEELS BEING SIMULTANEOUSLY ROTATED IN THE SAME DIRECTION BUT ONE WHEEL HAVING A GREATER TANGENTIAL SPEED THAN THE OTHER SO THAT SAID DRIVE WHEELS ROTATE THE WORKPIECE AND URGE IT DOWNWARDLY INTO THE SUPPORTS.