US3250046A - Method of grinding - Google Patents

Description

s. M. NAPP 3,250,046

METHOD OF GRINDING 4 Sheets-Sheet l May 10, 1966 Filed July 1 May l0, 1966 s. M. NAPP METHOD 0F GRINDING 4 Sheets-Sheet 2 Filed July l, 1953 f4 if .IIIIL May 10, 1966 s. M. NAPP METHOD OF GRINDING llflll S. M. NAPP METHOD OF GRINDING May 10, 1966 4 Sheets-Sheet 4 l Filed July 1 1963 United States Patent() 3,250,046 METHDD F GRINDING Sidney M. Napp, Rockton, Ill., assigner to Besly-Welles Corporation, South Beloit, Ill., a corporation of Illinois Filed July 1, 1963, Ser. No. 291,623 12 Claims. (Cl. 51-281) This invention relates generally to grinding, and particularly to a method of grinding.

Accordingly a primary object of the invention is to provide a method of finish grinding a workpiece to very close tolerances.

Another object is to providea method of rapidly nish grinding one workpiece or, alternately, a plurality of workpieces simultaneously in a grinding zone.

A further object is to provide a method of feeding workpieces to a gr-inding zone in which the speed of advancement of the workpiece through the grinding zone is correlated to the degree of finish imparted to the workpiece so that the workpiece'remains in the grinding zone only long enough to be finished ground.

Yet another object is to provide a method of finish grindin-g va workpiece to very close `tolerances in a grinding zone.

Yet a further object is to provide a method of finish grinding a plurality of workpieces simultaneously to close tolerances in a grinding zone.

Yet a further object is to provide a method of finish grinding `in which a plurality of workpieces are maintained substantially equidistantly spaced from one another as they traverse a grinding zone.

Other objects and advantages of the invention will become apparent from a reading of the following description of the invention.

The invention is illustrated more or less diagrammatically in accompanying drawings wherein:

FIGURE 1 is an elevation of a first embodiment of the invention;

v FIGURE 2 is a partial, top plan view of the embodiment of FIGURE l;

FIGURE 3 is a sectional view, to a larger scale, taken substantially along the line 3-3 of FIGURE l;

FIGURE 4 is a view, to a larger scale, taken substantially along the line 4 4 of FIGURE 1;

FIGURE 5 is an elevation of another embodiment of the invention.

FIGURE 6 is a section toa larger scale through the loading mechanism of the embodiment of FIGURE 5.

FIGURE 7 is a view of another embodiment of the invention; l

FIGURE 8 is a section taken substantially along the line 8 8 of FIGURE 7;

FIGURE 9 is an elevation of a belt back-up plate assembly;

FIGURE 10 is atop plan view of the belt back-up plate `assembly of FIGURE 9; and

FIGURE 11 is a section taken substantially along the line 11-11 of FIGURE 9.

Like reference' numerals will refer to like `parts throughout the following description of the drawing.

A grinder is indicated generally at 10 in FIGURE 1. The grinder includes a grinding zone, indicated generally at 1,1, and a loading assembly indicated generally 'at 12. One of a pair of grinding wheels is indicated at 13, the -grinding wheels `being mounted for 4rotationon a pair of opposed, axially aligned shafts, of which is indicated at 14. The loading assembly 12 is mounted on the frame 15. An inner splash guard 16 is secured' to the frame 15 and supports the loading mechanism 12.

An outer splash guard 18 is mounted on frame 15 and provides a base for the left, or rearward end of -a pusher -bar -assembly indicated generally at 19. The pusher bar 3,250,046 Patented May 10,1966

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assembly 19 includes a pusher bar 20 which slides in an outer support rail 21, the outer support rail being supported from the outer splash guard by supporting brackets 22, 23 and 24.

The forward or advancing end of pusher bar 20 terminates in a pusher head assembly indicated generally at 25. The pusher head assembly, which is shown best in FIG- URES 3 and 4, includes a pusher head 26 and a spacer 27, the head and spacer being secured to the pusher bar by a plurality of screws. A pair of side guides 29, 30, are secured to the forward-most end of the pusher head 26 by a plurality of screws. width equal to the width of the forward end of pusher head 26 is also secured to the side guides 29, 30 by screws to form a planar advancing surface 31a. A pair of upper and lower guide rails, `or guide bars, are indicated at 32, 33. The guide `bars are secured to the face plate 33a by a plurality of bolts 34, 35, and are maintained a fixed distance from the front face plate by the annular guide lbar spacers 36, 37. The width of the spacers yand the length of the bolts may be varied to correspond to the width of workpiece to be ground. Preferably the width is such that the pusher head assembly exerts a centered force on the workpiece.

The pusher head 26 is maintainedvertically aligned with the guide ybars by the upper and lower overlapping ends of the side guides 29 and 30. Preferably the width of the guide bars and the width of the pusher head are substantially identical so that there will 4be no or little wobble of the pusher head as it advances through the grinding zone.

The guide bars maybe continuous or discontinuous `from the left end of frame 15 to the grinding zone. In this instance guide bar extensions 39, 40 are aligned with the guide bars 32, 33, respectively. The rear end of extensions 39, 40 are secured to an upstanding bracket 41 which in turn is secured to frame 15.

A driver assembly for the pusher bar is indicated generally at 42. In this instance the drive assembly consists of a pair of short belts 43, 44, each belt being wrapped about a pair of pulleys 45, 46, and 47, 48. A housingcover 42a overlies 'each longitudinal pair of pulleys. The cover is carried by the upper ends of the pulley shafts. In FIGURE 2 the housing cover overlying pulleys 45 and 46 has been removed to show a belt back-up plate assembly 51. The belt back-up plate assemblies are identical and accordingly only one is shown in detail. The pressure of each belt back-up plate as- .sembly against the pusher bar 20 may be adjusted by means of bolt and nut arrangement 42b which moves the assembly transversely relative to the stationary housing cover 42a. At least one pulley in each pair of pulleys is a drive pulley, and preferably the drive pulleys are driven from a common source so 'that the speed of the belts is identical. A power source, such as an electric or hydraulic motor, is indicated at 49. Belt 44 may be adjusted inwardly and outwardly to accommodate different width pusher bars by rotation of hand wheel S0, the pulley assemblies being mounted vfor sliding movement along guide |ways in a manner well known in the art. When the belts are pressed into engagement with the pusher bar Z0 the pusher bar will be moved forwardly or rearwardly, depending upon the speed of the belts, due to the frictional engagement between the bar and belts.

The belt back-up plate assembly, which is indicated generally at 51 in FIGURE 2, is illustrated in detail in FIGURES 9, 10 and 11. The lassembly consists of a frame member having an upper portion 51a and a lower portion 51b which are spaced from one another by spacer portion `51C. A rearwardly extending adjusting flange 51d has a tapped hole 51e which receives the bolt A bottom spacer 31 of a 3 of adjusting assembly 42a. A plurality of belt contacting rollers are indicated at 52. Each roller consists essentially of a shaft received within ve bearing sleeves. The upper and lower ends of each shaft project slightly beyond the top and bottom surfaces of the terminal bearing sleeves and are secured to one another by identical chain links 53. The shaft of right end roller 52a extends outwardly beyond the bearing sleeves a substantial distance at each end of the roller as seen at 52h and 52e. These ends are journaled in notches 52d, 52e formed between recessed are-as in the upper and lower portions 51a, Sib, and notched face plates'SZf and 52g. The links terminate at the left end of the series at a shaft tightener 54 which receives a pair of adjusting screws 54a, 54b. Adjustment of the screws places the rollers under any desired tension. The greater the tension the more nearly the rollers approach a rigid plate, and the greater will be the frictional engagement between the belts `43 and `44 and the pusher bar 20.

A loading platform is indicated generally at 55. It will be understood that within the scope of the invention lany suitable mechanism for delivering a workpiece to be ground to the loading platform 55 may be employed. Likewise, any suitable pusher or loading mechanism may be used to move the workpiece from the loading platform 55 into position between the upper land lower guide bars.

Three limit switches are indicated at 60, 61, 62. Limit .switch 60 is bolted to a bracket 63 which in turn is secured to the outer spl-ash guard 18. A plunger 64 carrying a roller 65 extends downwardly from the limit switch to a position just above the upper edge of pusher bar 20. Limit switches 61 and 62 are similarly bracket mounted to outer splash guard 18, and each contains a plunger 64a or 64b and a follower roller 65a or 65h. The pusher bar carries a pair of cams 66, 67 which extend upwardly above the upper edge of the pusher bar a distance suicient to engage, and actuate, the limit switch rollers and plungers.

Referring now to the embodiment of FIGURES and `6, a feeding assembly is indicated generally at 69, a loading mechanism at 70, the grinding zone at 71, and the discharge zone at 72. Upper and lower guide bars are indicated at 73, 74. In this instance the pusher bar 75 terminates at a pusher head 76 which has a pair of notches 77, 78 formed therein. Again the pusher bar is maintained in alignment with the guide rails 73 and 74 by the overlap of the guide rails by the pusher head side plates, one of which is indicated at '79.

The feeding assembly 69 includes a chute 80, the upper portion of which is angled as at 81, and the lower portion 82 of which is generally vertically aligned with the base of the machine. The chute, 'as best seen in FIG- URE 6, includes a pair of side plates `83, 84, which are secured by any suitable means at their lower end to a bottom plate 85. A plurality of workpieces 686 are shown in the chute preparatory to being placed on the lower guide rail '74.

The workpieces are dropped downwardly to the bottom of the chute two at a time,'one from each tier of workpieces, by an escapement device indicated generally at 86a. The workpiece escapement device includes a housing 87 and -four escapement pins 88, 89, and 90, 91. The pins are reciprocated by a pair of iluid cylinders 92, 93, the piston rod of each cylinder being connected to a horizontal pair of escapement pins by a suitable yoke mechanism. v

The loading mechanism 70 consists of a pair of hardened steel loading plungers 95 fastened, at their inner ends, to a yoke member 96. The yoke is reciprocated from its extreme right position illustrated in FIGURE 6 toward face plate 33a by air cylinder 97 whose piston rod is connected to yoke 96.

A limit switch 98 is mounted on a support bracket 99. Roller 100 and a plunger connected thereto is actuated each time a cam 101 secured to the bottom of yoke 96 engages it. The cam 101 is so positioned that the plungers will have moved a pair of workpieces into the notches 77, 78, of pusher head 76 before the cam strikes plunger 100. Depression of the plunger initiates forward motion of pusher bar 75 by starting the pusher bar motor in a forward direction.

The pusher 76 is shownin an unloaded position in dotted lines in discharge zone 72. The workpiece received in notch 78 rolls down exit chute 103 as soon as the forward notch 78 passes over the left or inner end of the exit chute. In the illustrated position the workpiece carried by notch 78 has rolled down the lchute out of the figure. Notch 77 has just cleared the end of the chute and workpiece B is just starting down the chute.

It should be understood that the speed-up mechanism of FIGURE 1 can just as readily be employed with the embodiment of FIGURE 5. If a speed-up mechanism is employed, the cams on pusher bar 75 vmll be so arranged that the pusher head 76 will not be speeded up until notch 77 has traversed a distance into the grinding zones suiiicient to achieve the desired nish on workpiece B.

In the embodiment of FIGURES 7 and 8, the pusher head assembly 105 urges a pair of vertically disposed workpieces D and E through the grinding zone. In this instance three guide rails 106, 107 and 108 have been provided, the longitudinal axis of guide rail 107 being coincident with the horizontal axis of the grinding zone. Pusher head assembly 105 includes a pusher bar 109 which in this instance is disposed between the upper and middle guide rails.

The pusher bar 109 is connected to side plates 110 and 111 by screws 113. A pair of pusher heads 114, 115 are secured to the side plates 110, 111 by suitable bolts, not numbered. The leading edge of each pusher head lies flush with the leading edge of the side plates 110, 111. As in the previous embodiments the side plates 110, 111 slight overhang the upper and lower guide rails to maintain the pusher head in alignment as the pusher bar advances the pusher head assembly and the workpieces through the grinding zone.

The identical speed-up mechanism of FIGURE 1 can be employed with this embodiment. That is, since the workpieces D and E are substantially vertically disposed each will be given its desired nish at substantially the same instant. It is therefore `unnecessary to maintain one workpiece in the grinding zone a little longer than need be as in the case of the embodiment of FIGURE 5 wherein the workpieces are arranged in tandem.

It should also be understood that the speed-up mechanism may or may not be employed, depending upon various conditions including the desired rate of .production, cost considerations and other factors.

The use and operation of the invention -is as follows:

In the embodiment of FIGURES 1, 2 and 3 the workpiece to be finish ground is delivered to the loading platform 55 by any suitable mechanism. At this time the pusher bar 20 with its pusher head assembly 25 is in its extreme left position as indicated in solid lines in FIG- URE 1. The workpiece A is then moved by any suitable mechanism from the loading platform into the dotted line position of FIGURES l and 3. Movement of the workpiece into position manually or automatically initiates operation of motor 49 in a direction to rotate drive belts 43, 44 in a pusher bar advancing direction. The pusher bar advances toward and into the grinding zone at a predetermined rate of speed.

Optionally, the pusher bar may be moved rapidly to the grinding zone, and slowed just prior to its entry so that the workpieces will be travelling at an optimum speed as they enter the grinding zone.

It has been discovered that the workpiece is actually finish ground during the rst few inches of the grinding zone. It is, therefore, unnecessary to advance the workpiece through the entire grinding zone at the same rate at which it entered. Pusher bar 20 is therefore speeded up after a pre-determined travel in the grinding zone and the workpiece quickly cleared through the remainder of the zone. The speed of the pusher bar is increased by l depression of plunger 64a by cam 67 on the pusher bar.

Limit switch 61 is connected into the motor circuit in such a fashion that the motor speed is increased upon actuation of the limit switch.

The pusher bar continues moving to the right until cam 67 depresses plunger 64b of limit switch 62. Limit switch'62 is incorporated into the motor circuit in such a manner as to cause motor 49 to reverse. At the time of reversal of direction the pusher head assembly 25 will have pushed the workpiece through the grinding zone to a point at which it has cleared the grinding zone and been discharged.

The pusher bar 20 then retracts, that is, moves to the left, at the rapid rate of speed until again reaching the FIGURE 1 position. When cam 65 depresses plunger 64 of limit switch 61, motor 49 is cut out. Another workpiece is then placed between guide rails 32 and 33 by the loading mechanism. The loading mechanism initiates motor 'operation and the cycle is repeated.

In the embodiment of FIGURES 5 and 6 a pair of workpieces B and C are pushed into notches 77 and 78 of pusher head 76 -simultaneously by hardened steel plungers 95. Lower escapement pins 89, 91'have pre viously been retracted by cylinder 93 to permit workpieces B and C to drop to the bottom of chute 81 in line with the plungers 95. Limit switch plunger 100 is actuated by yoke 96 at or near the extreme left limit of travel of the plungers 95. Limit switch 98 initiates advancing motion of pusher head 76 toward the grinding zone 71.

The pusher head 76 maintains workpieces B and C equidistantly spaced from one another during their travel in the grinding zone. "I'his is important in order to produce an acceptable finish grind.

The pusher head 76 may advance completely through the grinding zone at its entering speed. Alternately, and preferably, the speed of the pusher head is increased as soon as workpiece B has reached that point in the grinding zone at which the desired finish has been irnparted to it. The pusher head is thereafter speeded up by a limit switch and cam system similar to that shown in the FIGURE l embodiment. The exact point at which the pusher bar 75 is speeded will vary from workpiece to workpiece. The length of stroke and the point during the stroke at which the speed of the pusher bar is increased can be adjusted by varying the position of cams 66, 67, and even the position of the limit switches 60, 61 and 62.

In the embodiment of FIGURES 7 and 8 a pair of 4workpieces D and E are pushed into position between guide bars 106, 107, and 108 by a loading mechanism which may, in effect, be a substantial duplicate of the FIGURE 6 mechanism displaced approximately 90 from the FIGURE 6 position.

Again movement of the workpieces D and E into position between the guide rails will initiate advancing motion of the pusher bar toward the grinding zone. It is desirable to maintain the workpieces as close to` the hori- Zontal center line of the grinding zone Ias possible. In this instance the longitudinal axis of the middle guide rail 107 is coincident with the horizont-al center line of the grinding zone so that each workpiece is spaced equidistantly from the horizontal center li-ne of the lgrinding zone and as close thereto as possible.

The rate of advance of the workpieces through the grinding zone can be speeded up after a pre-determined travel inthe grinding zone by means of a speed-up mechanism similar to that shown in the embodiment of FIG- URES l and 2. i

Although severalk embodiments of the invention have been illustrated and described, it will at once be apparent to those skilled in the art that funther mod-ifications might .be made without departing from the essential spirit of the invention. Accordingly it is intended that the scope of the invention be limited, not by the above exemplary description, but only by the scope of the claims as interpreted in light of the pertinent prior art.

Iclaim:

1. A method of rapidly finish grinding a workpiece in a grinding zone, said method 4including the steps of advancing the workpiece toward the grind-ing zone,

moving the workpiece at' a pre-determined speed through the grinding zone in engagement with a grinding surface along a uni-directional path for a period of time sufficient to substantially completely finish grind the workpiece,

said workpiece traveling. during the aforesaid period of ltime, a substantial portion but less than fall of the total length of the grinding zone, and after the workpiece has been finish ground but before it reaches the end of t-he grinding zone, imparting `a controlled linear movement to the workpiece by in-l creasing the rate of speed to a rate 'above' the entering speed to thereby quickly clear the workpiece from the grinding zone `along a path of movement coincident with the initial path of movement in the grinding zone.

2. The method of finish grinding of claim 1 further characterized in that -the workpiece moves at a substantially constant rate of speed during the initial finish grind portion of its travel in the grinding zone.

-3. The method of finish grinding of claim 1 further characterized in that the workpiece moves at a substantially constant rate of speed from its starting position until the time its speed is increased within the grinding zone.

4. A method of finish grinding :a workpiece in a grinding zone, said method including the steps of imparting advancing motion to a workpiece to ibe finish ground towarrd a grinding zone, said -advancing mo-tion fbeing simultaneously imparted to guiding means associated therewith,

moving the workpiece at la pre-determined speed through the grinding zone in engagement with a grinding surface for a period of time sufficient to finish grind the workpiece,

said workpiece traveling, during the aforesaid time,

a substantial portion but less than all of the total length of the grinding zone, and

`after the workpiece -has been finish ground but before it reaches the end of the grinding zone, increasing its rate of speed a'bove the entering speed to thereby quickly clear the workpiece from the grinding zone, land after the workpiece has cleared the grinding zone,

imparting retracting motion to the workpiece guiding means having a speed greater than the speed at which the workpieces moved through the finish grind portion of the grinding zone.

5. The method of finish grinding of claim 4 further characterized in that the speed of the concluding Iadvancing motion and the speed of the retracting motion are substantially constant.

6. The method of finish grinding of claim 4 further including the step of grinding the workpiece on two parallel faces simultaneously.

7. A method of finish grinding Ya plurality of workpieces in a common grinding zone simultaneously, said method including the steps of advancing a first and .a second workpiece to be ground through a grinding zone,

maintaining' said workpieces equidistantly spaced from lthey reach the end of the grinding zone, increasing L the rate of speed of the Workpieces to a value above the rate that they were being finish ground :to thereby quickly clear the Workpieces from the grinding zone.

8. A method of grinding a plurality of Workpieces in a common grinding zone simultaneously, said method including the steps of advancing :a irst workpiece to be ground through the grinding zone, advancing a second workpiece to be ground through the grinding zone, f

maintaining said Workpieces on `opposite sides of, and

equidistantly spaced from, a center line of the grinding zone, as they move th-rough Ithe zone in engagement with a grinding surface, and

after the Workpieces have been finish ground, but

before they rea-ch the end of the grinding zone, increasing their rate of speed aibove their entering -speed to thereby quickly yclear the Workpieces from the grinding zone,

said Workpieces being moved through Ithe grinding zone at identical speeds at :any given moment.

9, The method of cl-ose tolerance grinding of the plurality of Workpieces of claim 8 further characterized in that the Workpieces enter, and leave, the grinding zone, ,substantially simultaneously.

10. A method of finish grinding a plurality `of Workpieces in a common grinding zone substantially simultaneously, said method including the steps of moving a first and a second workpiece to be ground,

in tandem, through a common grinding zone, said workpiece being moved through `the grinding zone at substantially identical `speeds at any given moment,

maintaining ythe Workpieces a common distance from one another during that period of time in which both Work-pieces are being finish ground Iby eng-agement with a grinding surface, and

after the workpieces have been finish ground, but -before they reach the end of the grinding zone, increasing their rate of speed above their entering speed to thereby quickly clear the workpieces from the grinding zone. l

11. The method of nish grinding a plurality of Workpieces in a common grinding zone substantiallysimultaneously of `claim 10 further characterized in that the workpieces move along a common path.

12. The method of nish grinding a plurality of workpieees in a common grinding zone substantially simultaneously of claim 10 4further characterized in that the speed of the Workpieces is simultaneously increased after the workpiece last to enter in the grinding zone has been finish ground.

References Cited by the Examiner UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner.

L. S. SELMAN, Assistant Examiner.

Claims (1)

1. A METHOD OF RAPIDLY FINISH GRINDING A WORKPIECE IN A GRINDING ZONE, SAID METHOD INCLUDING THE STEPS OF ADVANCING THE WORKPIECE TOWARD THE GRINDING ZONE, MOVING THE WORKPIECE AT A PRE-DERMINED SPEED THROUGH THE GRINDING ZONE IN ENGAGEMENT WITH A GRINDING SURFACE ALONG A UNI-DIRECTIONAL PATH FOR A PERIOF OF TIME SUFFICIENT TO SUBSTANTIALLY COMPLETELY FINISH GRIND THE WORKPIECE, SAID WORKPIECE TRAVELING DURING THE AFORESAID PERIOD OF TIME, A SUBSTANTIAL PORTION BUT LESS THAN ALL OF THE TOTAL LENGTH OF THE GRINDING ZONE, AND AFTER THE WORKPIECE HAS BEEN FINISH GROUND BUT BEFORE IT REACHED THE END OF THE GRINDING ZONE, IMPARTING A CONTROLLED LINEAR MOVEMENT OF THE WORKPIECE BY INCREASING THE RATE OF SPEED TO A RATE ABOVE THE ENTERING SPEED TO THEREBY QUICKLY CLEAR THE WORKPIECE FROM THE GRINDING ZONE ALONG A PATH OF MOVEMENT COINCIDENT WITH THE INITIAL PATH OF MOVEMENT IN THE GRINDING ZONE.

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