US2439771A

US2439771A - Apparatus for facing and truing abrasive articles

Info

Publication number: US2439771A
Application number: US687737A
Authority: US
Inventors: Eric P Dahlstrom
Original assignee: Carborundum Co
Current assignee: Unifrax 1 LLC
Priority date: 1946-08-01
Filing date: 1946-08-01
Publication date: 1948-04-13
Anticipated expiration: 1965-04-13

Description

April 1-3, 1948.

E. P. DAHLSTROM APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Filed Aug. 1, 1946 4 Sheets-Sheet 1 Etc? INVENTOR. zaiiz'sirom fliiarnqy April 1948- E. P. DAHLSTROM 2, 39,771

APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Filed Aug. 1, 1946 4 Sheets-Sheet 2 INVENTOR.

Eric 7. 2m Z5 from ornqy April 1948. E. P. DAHLSTROM 2,439,771

APPARATUS FOR FACING AND TRUING ABRASiEVE ARTICLES Filed Aug. 1, 1946 4 Sheets-Sheet 3 Jig. 5.

IN VEN TOR.

E1 to 217a?! Z5570? fiifily April 13, 1948. E. P. DAHLSTROM 2,439,771

APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Filed Aug. 1, 1946 4 Sheets-Sheet 4 Patented Apr. 13, 1948 UNlTED STATES APPARATUS FOR FACING AND TRUING ABRASIVE ARTICLES Eric P. Dahlstrom, Niagara Falls, N. Y., assignmto The Carborundum Company, Niagara Falls, N. Y., a corporation of Delaware Application August 1, 1946, Serial No. 687,737

90laims. 1

This invention relates to the manufacture of abrasive articles of the rotatable type such as small size arbored grinding and polishing wheels and cylinders and mounted abrasive bodies of cylindrical shape. It is particularly concerned with methods and apparatus for truing, facing and edging the working surfaces of such rotatable abrading articles so that the grinding or polishing surfaces thereof will be uniform and true with the finished cylindrical surfaces thereof not only evenly surfaced but accurately centered in respect to the arbors or spindles of the articles.

Heretofore truing and edging of rotatable abrasive articles of the aforesaid type have been customarily carried out manually wherein the article to be surfaced is rotatably mounted in a suitable chuck or holding device and a. diamond tool. abrasive dressing stick or one of the conventional dressing tools such as a Bell dresser, Huntington. dresser, or Ross dresser, manually passed across the rotating cylindrical surface to be edged and trued. Whenever extreme accuracy has been desired the particular dressing tool has been likewise mounted in a holder for passage across the rotating surface to be edged and trued, Such practices have required the careful and detailed mounting of each individual article in its holder and have also required a reasonably high degree of skill in the proper positioning of the dressing tool in order for the final article to be satisfactorily trued and edged. Obviously, such practices are highly time-consuming and, if carried out by an operator lacking in the requisite skill, are not completely satisfactory.

It is an object of the present invention to provide an improved apparatus and method for ed ing and truing rotatable abrading bodies obviating the above disadvantages. It isa further object to provide an improved apparatus for facing, edging and truing such articles rapidly and efficiently with a minimum amount of time consumed in carrying out the operations and with a high degree of accuracy in the truing of the abrading articles.

I have found that rotatable abrading bodies such as arbored grinding wheels and cylinders and mounted abrasive articles of cylindrical shape can be quickly and accurately faced, edged, and trued in respect to the arbors or spindles thereof by means of a centerless grinding mechanism modified by the provision of cooperating means for centering the abrading body with respect to the centerless grinding mechanism and presenting the body to the grinding mechanism. Apparatus in accordance with the present invention 2 can be so constructed as to perform the edging and truing operation alone or it can be so constructed as to successively face, edge and true the desired article. According to one embodiment-of my invention, apparatus is provided whereby while one article is being faced, a second article, usually previously faced, is simultaneously edged and trued by the same centerless grinding mechanism.

1o Briefly, the apparatus provided in accordance with the present invention consists of a centerless grinding mechanism of the conventional type together with coacting mechanism adapted for holding a plurality of articles to be faced and is centered and for presenting those articles in a succession of stages to the centerless grinding mechanism in such manner that they are first faced on the flat end surface thereof, when desired, and are then re-positioned and presented to the centerless grinding mechanism in centered relation thereto so that the cylindrical surface of the body is edged and trued-with respect to the nounting arbor or spindle of the body being suraced.

In order that the invention may be more clearly understood, reference is made to the drawings wherein an embodiment of the present invention adapted for facing, edging and truing rotatable abrading articles in rapid succession is set forth, and wherein Figure 1 is a rear elevational view of an apparatus embodying the principles and features of the present invention, and wherein the showing of the centerless grinding mechanism is confined to a partial diagrammatic showing of the grinding wheel and feed wheel thereof;

Figure 2 is a side elevation of'theapparatus shown in Figure 1, showing the feed wheel of the grinding mechanism partially cut away;

Figure 3 is a vertical view, partially in section, of the apparatus shown in Figures 1 and 2;

Figure 4 is an enlarged view, partly in section, taken on the line 44 of Figure 2;

Figure 5 is a top plan view taken on the line 5-5 of Figure 2 with the upper center holding means partially cut away;

Figures 6, 7, and 8 are schematic sketches depicting graphically the various'positions of the abrading body being treated with respect to the centerless grinding mechanism, first, as it is mounted in the apparatus, second, as it is moved into position for the end facing operation, and third, as it is moved into position for the edging and truing operation;

Figure 9 is a rear elevational view of them paratus ofl'igure 1 taken from the same position but enlarged in scope to show the complet centerless grinding mechanism, including the adjusting and operating means therefor;

Figure is a side elevation, partially in section, of a modified form of apparatus consisting of a single rotatable holding member: and

Figure 11 is a rear elevationalview of the mechanism shown in Figure 10, but with the holder angularly displaced to the position which it occupies when an abrasive body held thereby is in process of being faced.

Referring further to the various figures of the drawing, the details of the centerless grinding mechanism which constitutes a part of the complete operating apparatus of the present invention are not set forth since the centerless grinding mechanism may be any one of the conventional centerless grinding mechanisms on the market and the details thereof are not essential for a complete understanding of the nature of the present invention. Consequently, the showing of the centerless grinding mechanism is confined to a schematic showing of the grinding wheel 8, feed wheel Ill and rest or support bar ll thereof, showing the space relationship of those parts of the centerless grinding mechanism to the remainder of the entire apparatus. As therein shown, the axis of the feed wheel Iii is laterally parallel to the axis of the grinding wheel 9 but adjustably inclined at a. slight downward angle senting it to the flat side surface of the grinding wheel of the centerless oration, withdrawing the faced abrasive article and moving it into an accurately centered position for edging and truing the cylindrical surface of the article and simultaneously receiving and moving a second abrasive body into position for the facing operation, presenting the first article to the grinding mechanism in centered relation for edging and truing of the article while presenting the second abrasive body to the grinding wheel to be faced.

Referring again to the various figures of the drawing, the. aforesaid mechanism for holding the articles to be surfaced and'trued and presenting them to the grinding mechanism in proper positions for successively facing and edging, and also truing, comprises a base structure i2 upon which is mounted a suitable framework l3 carrying a mounting plate l4. The mounting plate It is rotatably supported on a shaft i5 and has mounted therein four holders or chucks [6 which are Journaled in the mounting plate It by means of ball bearing assemblies I! so that each holder or chuckis capable of independent rotation. As shown, the holders or chucks are radially equidistant from the center of the mounting plate I4 and equally spaced one from the other thereon. It is to be understood that from the horizontal for the purpose of drawing the article being edged through mechanism, the particular degree of angle governing the rate of travel of the article being treated through the grinding mechanism.

Figure 9 shows further details of the centerless grinding mechanism, including the grinding wheel 9 and regulating wheel i0 which are provided with suitable truing mechanisms, generally indicated at 50 and 5|, for truing the peripheral surfaces of the grinding and regulating wheels, respectively, when required. Mounted upon the stationary base structure of the centerless grinding mechanism is a carriage 52 supported on surface ways so as to be movable longitudinally of the base structure; carriage 52 supports the regulating wheel l0 and its associated mechanism. A threaded shaft 53 connected to carriage 52, and together with hand wheel 54, provides means for moving the carriag 52 and regulating wheel in longitudinally along the base of the centerless grinding machine to adjust the distance between the regulating and grinding wheels as desired. The grinding wheel 9 is rotated at a high speed in clockwise direction, being connected to and the grinding drivenby a conventional source of power (not shown), and effects a stock removal from the abrasive body being edged. The regulating wheel II, which rotates at a relatively slow speed, and similarly connected to and driven by a conventional source of power (not shown in the drawing) controls the rate of rotation of the work'in the machine. in operation, the parallel opposed faces of the wheels travel in opposite directions and form a grinding throat therebetween through which the abrading body to be edged passes. i

The centerless grinding mechanism as shown is modified by the provision of a holding and positioningmechanism adapted to receive and hold a plurality of rotatable abrasive bodies to be surfaced, accepting and moving each one in rapid succession in a series of'stages into correct position for facing the flat end surface thereof, prethe number of holders or chucks on the mounting plate need not necessarily be four, as shown, but may be any other reasonable number, the partial revolution of the mounting plate after each operation obviously depending upon the number of holders. The socket area It of each holder is preferably formed of or lined with an extremely hard, wear-resistant material such as a bonded tungsten carbide composition, and is of a size to permit a close fit between it and the mounting spindle of the abrasive article to be held therein. The mechanism shown in the drawings is depicted as provided with holding sockets as provided for in thesurfacing and truing of mounted abrading articles 20. When arbored rotatable abrading articles are being surfaced and trued the holding means, instead of being as shown, are provided with corresponding spindles set in the sockets or in place of the sockets, the spindles being of a size to closely fit the arbors of the abrasive articles to be surfaced.

Each of the holders or chucks I6 is slidably mounted to permit independent axial movement to and from the grinding mechanism and are normally held out of engagement with the grinding mechanism by means of springs 2| which are mounted on a shank 22 of each holding means extending rearwardly from the rear face of the mounting plate i4 and terminating in an enlarged head or button 23 suitable for engagement by the

adjustable extension arms

24 and 25 of an operating lever 26. The shorter of the two extension arms 24 is adjustable for length by loosening the lock nut 21 thereon and moving the threaded portion 28 of the extension arm and again settlngthe lock nut to maintain the desired position. This adjustable extension arm 24, upon forward movement of the operating lever 26, engages the shank 22 of the particular holding means It in position for the facing operation, 1. e.,

be faced. The length of the extension arm is determined by the length of the abrasive article grinder for the facing op-' being faced and the amount of facing to be performed thereon. The second and longer extension arm 23 of the operating lever 23 at the same time engages the shank 22 of the holding means which isin position for the edging and truing operation, i. e., the holder in the bottom center position, and imparts an axial movement thereto toward the grinding mechanism. This axial movement is greater than the movement imparted by the adjustable extension arm to, the holder in the left hand position and is sufllcient to carry the abrading body 23 held by the bottom center holding means into full engagement by the grinding wheel 3 and feed wheel it of the centerless grinding mechanism and supported in the proper centered relationship to assure accurate centering of the cylindrical surface, when edged, in respect to the spindle or arbor of the article being edged and trued.

Rotation of the mounting plate through the partial revolution necessary forbringing each holding means successively into positions for the various operational steps, and which is one quarter of a revolution'when four holders are employed, is accomplished as follows: As the operating lever 26 is pulled back and drawn out of holding and pontioning mechanism can be diswith means for vertical adjustment. The rotat able mounting plate It and associated structureare likewise capable of lateral adjustment for the centering of the holding meansby which it presents the work to the grinding mechanism to be engagement with the shanks 22 of the holding means It the springs 2| ull the holders it away from the grinding mechanism and the operating lever 23 is forced against the trip arm 30 which operates a. valve mechanism 3| which then allows compressed air to enter a cylinder 32 actuating a piston in the cylinder, which piston is connected to a rack gear 33 which engages an intermediate unidirectional or free gear 34 which in turn is meshed with peripheral gearing 3b of the mounting plate ll, imparting one-quarter of a revolution to the mounting plate ll. Withdrawal of the operating lever 23 from the trip arm 30 cuts off the supply of air to the cylinder 32 and conventional spring means provided therein withdraws the piston which, because of the unidirectional action. of the intermediate free gear 34 does not impart any corresponding reversing movement to the mounting plate It. The pneumatic action of the air cylinder is dampedor cushioned by means of Hannah speed control valves 36 located in th air line. compressed air is further regulated by means of a conventional air pressure regulator 31. An axially movable stop rod or bar 33 mounted upon the framework I3 and having a tapered gear tooth top face 39 adapted for closely meshing with the peripheral gearing of the mounting plate it, and normally held out of engagement therewith by spring til is so positioned that upon forward movement of the operating lever 23 it is meshed with the peripheral gearing 35 of the mounting plate It so as to make any minor adjustments necessary to bring the mounting plate It to an exactly 90 turn upon each actuation thereof by the rack gear 33.

It is plainly evident that the pneumatic cylinder mechanism described herein for actuating the mounting plate can be replaced by a similarly operable hydraulic-acting cylinder or by suitable mechanical devices without departing from the spirit and principles of the present invention.

The mounting plate It and associated framework I3 is capable of vertical adjustment since the framework i3 is provided with an upwardly extending column 43 mounted in suitable vertically extending dovetailed slideways or gibbs M by which it is vertically adjustable by means of hand wheel 35. This vertical adjustment of the trued and edged since it is also supported on horizontal dovetail slideways or gibbs 43 which are operable by means of hand wheel 41.

Operation of the facing, truing and edging apparatus as shown in the various figures of the drawing is carried out as follows: Assuming that the rotatable mounting plate It and associated structure or framework has been vertically and horizontally adjusted so that the bottomly positioned holding means is correctly and accurately centered with respect to the grinding and feed wheels of the centerless grinder so that an abrading body held by that particular holding means or chuck will reside in the position shown in Figure 8, the steps are carried-out in the following manner. A mounted cylindrical abrading body to be surfaced, edged and trued is placed in the socket iii of the holding means resting in the top center position (see Figure 6). The operating lever 23 is then pulled back into engagement with the tri arm 30 which opens valve 3i letting air into the cylinder 32 which actuates the piston contained .in the cylinder, thereby rotating the mounting plate It through, for example, onequarter .of a revolution by means of the gearing means previously described. This partial revolution of the mounting plate It brings the holder containing the abrasive body 22 inserted therein to the left hand position shown in Figure I. At

this point a second abrading body is inserted in the second holder or chuck which has been brought to the top position on the mounting plate and the operating lever 28 again pushed forward whereupon the holding means in the left hand position shown in Figure 'l is moved forward so that the abrading body 20 held thereby is presented to the flat face 29 of the grinding wheel 9 to be faced thereby. The lever 28 is then pulled The flow of 1 back to again press against trip arm so and operate valve mechanism 3| whereby the piston in air cylinder 32 is again actuated to impart another one-quarter revolution to the mounting plate Hi bringing the third holding means into the upper position (shown in Figure 6) ready for insertion of an article to be surfaced. At the same time, the second of the previously inserted abrasive articles is moved to the left hand position (shown in Figure '7) and the holder carrying the abrasive article previously faced is moved into the bottom position (shown in Figure 8) properly centered and positioned for the edging and truing operation. The operating lever 26 is again pushed forward whereupon the stop bar 38 first engages the gearing 35 of the mounting plate It to make an minor adjustments necessary for limiting the rotation of the mounting plate to exactly so as to accurately center the lower holding means, immediately following which the

extension arms

28 and 25 of the operating lever 26 impart axial movements to the left hand and bottomly positioned holding means, respectively, to bring the abrasive article held by the holder in the left hand position (see Figure "1) into en-' gagement with the fiat face of the grinding wheel for facing, and simultaneously bringthe faced abrasive article held by the holding means in the The forward movement of assent:

7. lower position (see Figure 8l-into engagement with the grinding wheel I and feed wheel ll of the grinding mechanism for edging and centering. the holding means in the bottom position is of suiiicient extent to hold the abrasive article being surfaced accurately centered radially with respect to the grinding wheel until it has traveled a substantial distance beyond the forward edge ll of the grinding wheel I, thereby assuring accurate truing of the abrasive article which is then readily released from its holder. The chuck or holder in the right hand position on the mounting plate is idle. Once the operations have proceeded to this point it is obvious that upon each forward movement of the operating lever 28 one abrasive article is being faced while a previously faced abrasive articie is being edged and trued and upon each withdrawal of the operating lever a new abrasive body is inserted in the top holder for subsequent facing, edging and truing. It is further evident that the articles being surfaced are always presented in exact alignment to the grinding'mechanism whereby the end face of the abrasive article is accurately surfaced so that the finished face will be at a true right angle to the axis of the article and the article being edged and trued also presented in correctly centered relationship to the grinding mechanism, thereby eliminating any possible error in surfacing of the articles once the apparatus has been correctly adjusted for the particular'abrasive articles to be surfaced.

Although I have described as my preferred embodiment of the invention an apparatus provided with a plurality of holding means or chucks and adapted for facing as'well as edging and truing rotatable abrasive articles, a simpler but modified form of the apparatus embodying many of the principles and features of the present invention such-as shownv diagrammatically in Figures 10 and 11 can be utilized wherein, instead of a plurality of chucks ofholders mounted upon a rotatable mounting plate together with means for rotating the mounting plate to bring the respective holders into operational positions as hereinabove described, such modified apparatus may consist simply of a single rotatable holding means It similar to one of the holders or chucks described above and capable of vertical and lateral adjustment and provided with an operating lever or arm 26, said holding means It being capable of axial movement and mounted in conjunction with a coactlng centerless grinding mechanism so as to rotatably hold and present rotatable abrading bodies to the grinding mechanism for, facing, edging and truing operations. In the case of such a simplified apparatus, the framework l2 supporting the rotatable holder is preferably pivotedv at the base at IS so that the holder can'be moved angularly into position for the facing operation as shown in Figure 11 after which it is returned to its vertical position and the single holding means thereof then moved for. ward axially to bring the faced abrasive body held thereby into centered engagement with the grinding wheel and feed wheel of the grinding mechanism to edge and true the cylindrical surface of the abrasive body.

Such a simplified form of apparatus is incapable of the operational speed of production of the apparatus provided with the rotatable mounting plate and multiple holding means, but might be preferred in those cases wherein relatively small numbers of abrasive bodies are to be edged and trued and a high degree of accuracy ,nism so that said abrading body a is desired, but quantity of output is or secondary importance.

The particular grinding wheel employed in the centerless grinding mechanism and the operating speeds of the grinding wheel and feed wheel of the eenterless grinding mechanism are de- Pendent largely upon the particular type of abrasive body being edged and trued. For example, in the edging and truing of small size abrasive bodies of the type described in U. 8. Patent No. 2,355,667 in which the abrasive body consists of a felted fibrous abrasive-containing structure, highly satisfactory results have been obtained by using a resinoid bonded 123 grit silicon carbide grinding wheel of Nil-B4 grade, operating at a speed of 1100 revolutions per minute with a feed wheel speed 01 130 revolutions per minute. However, it is not desired to limit the present invention to the use of any particular type of grinding wheel or to any particular speed thereof, nor is it desired to limit the present invention to the edging and truing of any specific type of abrasive article since it is possible to face, true and edge rotatable abrasive bodies by the apparatus and methods herein described regardless of the type of bond of the abrasive body.

Having described my invention in detail, it is desired to claim:

1. An apparatus adapted for use with a centerless grinding mechanism for facing. e ing and truing rotatable abrading bodies, said apparatus comprising, in combination, a supporting framework, a rotatable mounting plate carrying a plurality of rotatable holding means for holding the abrading bodies to be acted upon, each of said holding means being independently capable of axial movement. spring means for independently retaining each of said holding means normally out of engagement with the centerless grinding mechanism, means for independently moving one of said holding means axially toward the fiat side of the grinding wheel of said grinding mechanism to dress the fiat end face of an abrading body held by said holding means, means for simultaneously moving another of said holding means and the abrading body being held thereby axially into engagement by said grinding mechais acted upon by said grinding wheel to edge and true the curved surface of said body while it is rotatably held and g surface of said grinding wheel until truing of said abrading body is assured whereupon said abrading body is released from its holding means to pass between the grinding wheel and feed wheel of the grinding mechanism, rest means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the feed wheel of the centerless grinding mechanism, means for adjusting the vertical position of the aforesaid mounting plate, means for adjusting the lateral position of said mounting plate, mechanism for rotating said mounting plate through a partial revolution to move the holding means carrying the faced abrading body into position for the aforesaid edging and truin operation and to move another of the holding means carrying a newly inserted abrading body into position for the aforesaid facing operation, and means for actuating said rotating mechanism.

. 2. An apparatus adapted for use with a centerd n t id truing rotatable abrading bodies, said apparatus centered radiall against the peripheralcomprising, in combination, a supporting framework,'a rotatable mounting plate carrying a plurality of rotatable holdingmeans for holding the abrading bodies to be acted upon, each of said holding means being independently capable of axial movement, spring means for independently retaining each of said holding means normally out of engagement with the centerless grinding mechanism-means for independently moving one of said holding means axially toward the flat side of the grinding wheel of said grinding mechanism to dress the flat end face of an abrading body held by said holding means. means for simultaneously moving another of said holding means and the abrading body being held thereby axially into engagement by said grinding mechanism so that said abrading body is acted upon by said grinding wheel to edge and true the curved surface of said body while it is rotatably held and centered radially against the peripheral grinding surface of said grinding wheel until truing of said abrading body is assured whereupon said abrading body is released from its holding means to pass between the grinding wheel and feed wheel of the grinding mechanism, rest means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the feed wheel of the centerless grinding mechanism, means for adjusting the vertical position of said mounting plate, means for adlusting the lateral position of said mounting plate, mechanism for rotating said mounting plate through a partial revolution to move the holding means carrying the faced abrading body into position for the aforesaid edging and truing operation and to move another of the holding means carrying a newly inserted abrading body into position for the aforesaid facing operation, and means for actuating said rotatable mechanism, said plate-rotating mechanism comprising gearing means including an intermediate unidirectional or free gear which connects gear means on said mounting plate with gear means attached to the drive piston of an actuating cylinder mechanism, means for actuating said piston, and stop means for limiting the rotative action imparted by said piston to exactly the degrees of turn desired.

3. An apparatus adapted for use with a centerless grinding mechanism for facing, edging and truing rotatable abrading bodies, said apparatus comprising, in combination, a supporting framework, a rotatable mounting plate carrying a plurality of rotatable holding means for holding the abrading bodies to be acted upon, each of said holding means being independently capable of axial movement, spring means for independently retaining each of said holding means normally out of engagement with the centerless grinding mechanism, means for independently moving one of said holding means axially toward the flat side of the grinding wheel of said grinding mechanism to face the flat end surface of an abrading body held by said holding means, means for simultaneously moving another of said holding means and an abrading body held thereby axially into engagement by said grinding mechanism so that said abrading body is acted upon by said grinding wheel to edge and true the curved surface of said body while it is rotatably held a d centered radially against the peripheral grinding surface of said grinding wheel until truing of said abrading body is assured whereupon said abrading body is released from its holding means to pass between the grinding wheel and feed wheel of 10 the grinding mechanism, means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the feed wheel of the centerless grinding mechanism, means for adjusting the lateral position of said mounting plate, mechanism for rotating said mounting plate through a partial revolution to move the holding means carrying the faced abrading body into position for the aforesaid edging and truing operation and to move another of the holding means carrying a newly inserted abrading body into position for the aforesaid facing operation, and means for actuating said rotating mechanism.

4. Apparatus adapted for use with a center less grinding mechanism for facing, edging and truing rotatable mounted abrading bodies, said apparatus comprising, in combination, a supporting framework, a rotatable mounting plate carrying a plurality of centering chucks, each of said chucks being independently capable of axial movement, means for independently retaining each of said centering chucks normally out of engagement with the centerless grinding mechanism, means for independently moving one of said chucks axially toward the flat side of the grinding wheel of said grinding mechanism to face the flat end surface of a mounted abrading body held in said chuck, means for simultaneously moving another of said chucks and an abrading body held thereby axially into engagement by said grinding mechanism so that said abrading body is acted uponby saicl' grinding wheel to edge and true the curved surface of said body while it is rotatably held and centered in said chuck radially against the peripheral grinding surface of said grinding wheel until centering of said abrading body is assured whereupon said abrading body is released from its chuck to pass between the grinding wheel and feed wheel of the grinding mechanism, means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the coacting feed wheel of the grinding mechanism, means for adjusting the vertical position of said mounting plate, means for adjusting the lateral position of said mounting plate, mechanism for rotating said mounting plate through a partial revolution to move the chuck carrying the faced abrading body into position for the edging and truing operation and to move another of the chucks carrying a newly inserted abrading body into position for said facing operation, means for actuating said rotating mechanism, said plate-rotating mechanism comprising gearing means including an intermediate unidirectional or free gear which connects gear means on said mounting plate with gear means attached to the drive piston of an actuating cylinder mechanism, means for actuating said piston, and stop means for limiting the rotative action imparted to said plate by said piston to the degree of turn desired.

5. An apparatus for successively facing, edging and truing rotatable abrading bodies comprising (A) a centerless grinding mechanism comprising a grinding wheel and a coacting feed wheel together with adjusting means and operating means therefor, and (B) mechanism coacting therewith for accurately positioning and feeding the abrading bodies to be faced, edged and trued to said grinding mechanism, said positioning and feeding mechanism comprising a supporting framework, a rotatable mounting plate carrying a plurality of rotatable holding means for hold- 11 ing the abrading bodies to be acted upon, each of said holding means being independently capable of axial movement, spring means for independently retaining each of said holding means normally out of engagement with the centerless grinding mechanism. means for inde-' pendently moving one of said holding means axially toward the flat side of the grinding wheel or said centerless grinding mechanism to dress the flat end face of an abrading'body held by said holding means, means for simultaneously moving another or said holding means and an abrading body held thereby axially into engagement by said grinding mechanism so that said abrading body is acted upon by said grinding wheel to edge and true the curved surface of said body while it is rotatably held and centered radially against the peripheral grinding surface of said grinding wheel until truing of said abrading body is assured whereupon said abrading body is released from its holding means to pass between the grinding wheel and feed wheel of said centerless grinding mechanism, rest means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the feed wheel of said centerless grinding mechanism, means for adiusting the vertical position of said mounting plate.

, means for adjusting the lateral position of said mounting plate, mechanism-for rotating said mounting plate through a partial revolution to move the, holding means carrying the faced abrading body into position for the aforesaid edging and truing operation and to move another of the holding means carrying a newly inserted abrading body into position for the aforesaid facing operation, and means for actuating said rotating mechanism, said platerotating mechanism comprising gearing means including an intermediate unidirectional or free gear which connects sear means on said mounting plate with gear means attached to the drive piston of an actuating cylinder mechanism, means for actuating said piston, and stopmeans for limiting the rotative action imparted to said plate by said piston to exactly the degrees of turn desired.

6. An apparatus for successively facing, edging and truing rotatable abradlng bodies comprising (A) a centerless grinding mechanism comprising a grinding wheel and a coasting feed wheel together. with adjusting means and operating means therefor, and (B) mechanism coacting therewith comprising a plurality of independently rotatable holding means mounted upon a rotatable mounting plate, said holding means being adapted for receiving and bringing a rotatable abrading body against the flat side face of the grinding wheel or said centerless grinding mechanism to face the flat end surface of said rotatable abrading body and simultaneously feeding a rotatable abrading body to said grinding mechanism in radially centered relationship thereto to edge and true the curved grinding surface of said abrading body, and means for rotating said mounting plate to bring each of said holding means successively into positions for (1) receiving an abrasive article to be surfaced and trued; (2) the end-facing operation; and (3) the edging and truing operation.

7. Apparatus for edging and truing rotatable abrading bodies comprising (A) a centerless grinding mechanism comprising a grinding wheel and a coacting feed wheel together with adjusting means and operating means therefor, and

' aeeomi (B) mechanism for holding and positioning the abradingbody-tobe dgedendtmed and for feeding said abradlng body to said grin ing mechanism, said positionin and feeding mechanism comprising a support ing a rotatable holding means forholding the abrading body to be edged and trued. means for adjusting the vertical position of said holding means, means'for adjusting the lateral position of said holding means, said holding means being capable of axial movement. means for retaining said holding means normally out of engagement with the aforesaid centerless grinding mechanism, means for imparting axial movement to said holding means and to an abrading body held thereby to bring the abrading body into engagement with the grinding mechanism so that said abrading body is acted upon by the grinding wheel of said mechanism to edge and true the curved surface of said body while it is rotatably held and centered radially against the peripheral grinding surface of said grinding wheel until truing of said abradlng body is assured whereupon said abrading body is released from its holding means to pass between the grinding wheel and feed wheel of the grinding mechanism to be edged and trued thereby, and rest means for further supporting said abrading body in the latter part of its path of travel between the grinding wheel and the coacting feed wheel of the centerless grinding mechanism.

8. Apparatus for successively facing, edging and truing rotatable abrading bodies comprising (A) a centerless grinding mechanism comprising a grinding wheel and a coacting feed wheel together with adjusting means and operating means therefor, and (B) mechanism for holding and positioning the abrading body to be acted upon and for feeding said abrading body to said grinding mechanism, said positioning and feeding mechanism comprising a supporting framework carrying a rotatable holding means for holding the abrading article to be faced, edged and trued, said holding means and supporting framework being pivotally mounted to permit angular movement of the holding means, means for adjusting the vertical position of said holding means, means for adjusting the lateralposition of said holding means whereby said holding means is normally positioned to present an abrading body held thereon centered radially in respect to the grinding wheel and feed wheel of said centerless grinding mechanism, said holding means being capable of axial movement, means for retaining said holding means normally out of engagement with the aforesaid centerless grinding mechanism, means for imparting angular movement to said holding means to bring said holding means and an abrading body held thereby into position for facing the flat end surface of the abrading body against the flat side surface of the grinding wheel when'the holding means is moved axially against the grinding wheel, means for imparting axial movement to said holding means, and rest means for further supporting said abrading body in the latter part of its travel between the grinding wheel and coacting feed wheel of the centerless grinding mechanism.

9. An apparatus adapted for use with a centerless grinding mechanism for facing, edging and truing rotatable abrading bodies, said apparatus comprising, in combination, a supporting framework, a rotatable peripherally geared mounting plate carrying tour rotatable holding means for 7 holding the abrading bodies to be surfaced and g framework carry-' trued, said holding means being radially equidistant from the center of the mounting plate and equally spaced one from the other thereon,

- each of said holding means being independently capable of axial movement, spring means for independently retaining each of said holding means normally out of engagement with the centerless grinding mechanism, means for independently moving one of said holding means axially toward the fiat side of the grinding wheel of said grinding mechanism to dress the flat end face of an abrading body held by said holding means, means for simultaneously moving another of said holding means and an abradins body held thereby axially into engagement by said grinding mechanism so that said abradin body is edged and trued by said grinding wheel while it is rotatably held and centered radially against the peripheral grinding suriace of said grinding wheel until centering oi said abradins body is assured whereupon said abrading body is mounting plate through one-quarter of a revolution to move the holding means carrying the faced abrading body into position for the aforesaid edging operation and to move another 01' said holding means carrying a newly inserted abrading body into position for the aforesaid facing operation, and means for actuating said released from its holding means to pass between the grinding wheel and teed wheel of the grinding mechanism to be dressed thereby, means for further supporting said abrading body in the latter part or its path oi travel between the grinding wheel and the feed wheel of the centerless grinding mechanism, means for. adjusting the lateral position or said mounting plate for positioning each holding means thereon in turn in centered relationship to the centerless grinding mechanism, mechanism for rotating said' rotating mechanism, said plate-rotating mechanism comprising gearing means including an intermediate uni-directional or free gear which connects gear means on said mounting plate with gear means attached to the drive piston or an actuating cylinder mechanism, means for actuating said piston, said stop means for limiting the rotative action imparted by said piston to exactly a 90 turn.

ERIC 1?. DAHLSTROM.

REFERENCES orrnn The following references are of record in the ille or this patent:

UNITED STATES PATENTS I Number Name Date 1,270,770 Barnes July 2, 1918 1,814,862 Booth July 14, 1981 2,898,887 Muller Apr. 18, 1946 FOREIGN PATENTS Number Country Date 517,824 Great Britain Feb. 9, i940 559,227 Germany 861ml), 1932