US2431822A

US2431822A - Abrasive belt polishing machine

Info

Publication number: US2431822A
Application number: US442787A
Authority: US
Inventors: Ernest E Murray
Original assignee: Individual
Current assignee: Individual
Priority date: 1942-05-13
Filing date: 1942-05-13
Publication date: 1947-12-02
Anticipated expiration: 1964-12-02

Description

D 2, 1.947 E. E. MURRAY ARAsIvE BELT Pomsume MACHINE 7 Sheets-Sheet 1 Filed May 13, 1942 De@ 2, 1947. E. E. MURRAY 2,431,822

ABRASIVE BELT POLSHING MACHINE Filed May 13, 1942 'z sheets-sheet 2 fe@ a n @w 2,@ l947- E'. E. MURRAY RASIVE-BELT POLISHINGl MACHINE Filed May 1;, 1942 '7 sheetssheet s VzLyy/ue ATTORN 5- Dec- 2, 1947 E. E. MURRAY ABRASIVE BELT POLSHING MACHINE Filed May 13, 1942 7 Sheets-Sheet 4` INVENTOR y M Ys DecD 2, w47. E. E.

MURRAY

2,4%,822

ABRASIVE BELT POL-ISHING MACHINE v Filed May 13, 1942 '7 Sheets-Sheet 5 A, ya

INVENTQR v Mlr'acg 4MM/2% di@ Dec., 2, T194?, a E. MURRAY 2,4322

ABRASIVE BELT POLISHING MACH'INE Filed May 15, 1942 'T Sheets-Sheet 6 n INVENTOR Z ,fga 2125.' Murray! Y vf; "me

E. E. MURRAY ABRASIVE BELTvPOLISHING MGHNE 7 sheets-snm 'r Filed May l5. 1942 INVENTOR Zsfyurraezgr,

BY I [WM ATTOR YS.

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Patented Dec. '2, 1947 UNITED STATES PATENT OFFICE The present invention relates to nishing or polishing machines, and particularly relates to apparatus for nishing or polishing elongated metal articles which are of a twisted or substantially helical form along the longitudinal axis; for example, airplane propeller blades.

One oi the primary objects of the present invention is to provide machines by which the surfaces of the type of articles mentioned above may be finished or contoured or polished.

Another object of the invention is to provide machines to nish or polish elongated metal articles which have a twisted or substantially helical form along the longitudinal axis and which are transversely flat on one side and cambered on the opposite side.

Another object of the invention is to provide a. machine by which articles of the type mentioned above may be uniformly nished or polished so that the propeller blades so finished have uniform characteristics and will be in dynamic balance when assembled with other blades similarly iinished.

Another object of the invention is to provide a machine of the type mentioned by which there is eiiected considerable saving in time with material production increase.

A further object of the invention is to provide sturdy, accurate machines of the type mentioned which are adapted for accurate mass production.

Other objects of the invention will become apparent from the following specification, the drawings relating thereto, and from the claims hereinaiter set forth.

in the drawings, in which like numerals are used to designate like parts in the several views throughout:

Figure l is a partial side elevational view of a machine for nishing or polishing one side of an airplane propeller blade;

Figure 2 is a view similar to Figure 1, showing the remaining end of the machine as continued from line 2 2 of Figure 1;

Figure 3 is a righthand elevational View of the machine shown in Figure l, with a portion of the endless belt removed;

Figure 4 is a perspective view of a portion of the machine shown in Figure 1, with the endless abrading beltl removed;

Figure 5 is an enlarged, transverse, elevational View of a portion of the machine shown in Figure 1, illustrating the manner in whichthe ar 6 Claims. (Cl. 51--143) port with other co-operating parts of the machine;

Figure 6 is a cross-sectional View taken substantially along the line 6-6 of Figure 5;

Figure 7 is a top plan view of a portion of the machine, showing a propeller blade mounted on the article support;

Figure 8 is a partial, cross-sectional view taken substantially along the line 8--8 of Figure 4 and showing a propeller mounted on the support;

Figure 9 is a fragmentary perspective view of a portion of the machine, illustrating the manner in which the belt is applied;

Figure 10 is a view similar to Figure 9, showing another step in the application of the belt;

Figure 11 is a fragmentary, side elevational view of a portion of the machine, illustrating another form of the invention for finishing or polishing the cambered side of the propeller blade; A

Figure 12 is an enlarged view of a portion of the structure shown in Figure 11 and showing other portions in greater detail;

Figure 13 is a cross-sectional view taken substantially along the line I3-l3 of Figure 12;

Figure 14 is a partial perspective view of the structure shown in Figure 13;

Figure 15 is a cross-sectional view taken along the line l5-I5 of Figure 11.

The present invention is particularly adapted for the iinishing or polishing of airplane propeller blades; but it will be understood by those skilled in the art that according to its broader aspects the present invention is adapted for iinishing or polishing other articles having contours generally similar to such blades.

According to the present practice, propeller blades are nished or polished by hand-controlled methods. In such methods, the operator polishes a portion of the blade under hand control and by the use of templets checks the blade against a master blade. Such hand methods are )unsatisfactory because they are slow, since a substantial amount of time must be spent in checking. Furthermore, it is diiiicult for the operators to obtain uniformity in the nished blades, which results in a further loss of time, in that time must be spent in selecting blades which are all uniform, so that the blades will be in dynamic balance when mounted on the engine.

According to the present invention, machines are provided by which both the flat and cambered sides of the blade may be finished. Not all of the surface of the blade is nished by the present machine, in that a minor portion of the blade adjacent the hub must still be hand finished. However, the major portion of the blade is iinished by machines of the present invention.

It will be understood that the propeller blades are twisted about their longitudinal aXis and that the thickness of the blade increases from the tip to the hub. When iinishing the flat side, there is a straight line at any point along the blade transverse to the longitudinal axis. The blade is mounted upon a reciprocating carriage andis so mounted upon the carriage that it may tilt transversely thereof. Such tilting carriage is reciprocated with respect to an abrading means.

The abrading means includes an endless abradf ing belt having a cylindrical roller engaging the side of the belt opposite to that of, the blade so that the roller urges the rotating belt into engagement with the surface of the propeller. Longitudinal cam elements are disposed on the sidev of the carriage, and the top surfaces of such cam elements are shaped to correspond to the twistin the propeller blade. The surfaces of the cam elements are such that at, any point therealong, a transverse line' across the surfaces yof the opposite carri elerrientsV wouldvb'e coincident with or parallel to a transverse une across the propeller blade.

The roller is mountedfor pivotal movement about a fixed pivot axis and roller elements are mounted for pivotal viii'o'veirient about the same axisv andare integral with the roller mounting.

Such roller elements are vadapted to engage the cam surfaces and cause tli'propeller blade carriage to tilt as it reciprocates with respect to the roller. The pivotal' movement of the pressure roller permits the proper` finishing along the blade due to the variation in thickness along its length. Due tio the uitingy ofthe matie, a transversely straight une on Atrie] blade is' presented to the abrading belt under the roller as the blade passes under such roller. The pressure roller is mounted for accurate vertical, adjustment so as to control the amount of surfacematerial that` is removed.

In finishing the carnbeied side, a roller is provided which is annularly groyedcorrespondihg t0 the'coiit'o'lir of the cambid side of the lblade from the tip to a point adjaceiittlrie hub end thereof. Such roller hasacirciimference corresponding to the length of that part of the blade to be finished and it is caused to rotate in synchro'- nisrnk withmthe reciproc-ation 'of the carriage so that the abrading belt isgiy'en the proper contour as it engages Atheblad'e at the variouspoints along the length thereof', rfhe blade carriage is atthe Sametime ausedjto'tiit' during its reciprocation.

to take @are of triettist irrtrie blade.

Fora better understanding of the invention, reference may be `had to the drawings and partieularly to Figs; lV through 1.0 thereof, in which a machine is illustrated fo'r iinishingor polishing the nat sident menace. The structure comprises a mountinglstandard including a Base plate 2vand waardes stes aan 24'. which are mounted. upon the baise.l plate 26l and which Aare connected together adjacent, they upper ends thereof by a transversehinte'gral portion 261./Ihe. standard thus :forms a` tunnel or aperture therethrough, through which the blade carriage can pass during its reciprocablevmovement t A pair 0f longitudinally extending members 28 and another pair 'of longitudinally Aextending members 30 are connected to longitudinally extending channelV beam s 32 and 34, respectively, and are spaced from each other to providetr'ack- Ways for supporting the reci-procable blade car- 4 riage, generally indicated at 35.

Such members

28, 36, 32 and 34 extend Within the tunnel or opening and are connected to the standards 22 and 24 and also to longitudinally spaced standards 3T, which serve to mount the trackway above the floor. The ends of the members 32 and 34 may be connected and braced by transversely extending channel members 38.

The carriage 36 has a transversely tiltable blade support and carriage 46 mounted thereon for reciprocation therewith, upon which tliepropeller blade 42 is mounted. Such propeller blade 42 is, in the embodiment illustrated, the Duralumin type and is twisted about its longitudinal axis and has a flat side 44 and a cambered side 46; as shown in Fig. 8. The carriage l0 is formed with a central bed portion 48 having a plurality of longitudinally spaced, outwardly and upwardly disposed side arms 50. The outer ends of the arms are interconnected by integral, longitudinally extending sides 52, the upper surfaces of which are formed with angle grooves 53. ,A plurality'Cifv transversely extending members 54- are formed on plate members 55 which are i'l'iedly mounted on the bed 52. The members 54 are provided with vertical apertures therein within which vertically adjustable supporting pinsv 56 having rounded upper ends are mounted. Such pins 56 are adapted to be vertically adjusted within the apertures in themembers 5s and are set in their vertical positions by means of set screws 58. It will thus be seen that the pins 56 may be set so that the upper ends thereof properlyengage and support the curved surface of the blade' 4,2, whether thecambered or flat side is disposed downwardly. 'Ihe blade may thus be properly supported on the carriage 40.

In order to the blade on the carriage, a chuck or clamp 60 is mounted on the carriage 40 adjacent the trailing end thereof. Such chuck may be of conventional construction and includes a tapered mandrel 62, Which is properly centered and which is adapted to be received Within the tapered opening formed in the hub of the blade' 42. It Will be understood that such tapered opening is formed in the hub prior to the time that the blade is received for the finishing operation accomplished by the machines of the present invention, so that when the hub is mounted' on the chuck or clamp 60, the blade is properly centered. The chuck 66 may be of conventional construction and in the one illustrated, it includes clamps 64, which are adapted to engage the periphery of the hub, and is formed with releasable screw means so that the blade may be quickly attached yor disengaged from the chuck.

The carriage 36 has longitudinally spaced rollers 66 rotatably mounted at the sides thereof and such rollers are adapted to ride upon the lower track plates 28 and 3U. yLo'n'gitudinally extending guide bars 68 are xedly mounted to the top of the carriage 36 adjacent the sides thereof and the outer faces o'f such membersh are adapted to bear against the facing edges cf the

upper members

28 and 30 so that the carriage 36 is accurately guided Vduring it's recipro'cable movement.

The carriage 40 is adapted to be mounted on the carriage 36 for reciprocable movement therewith and for transverse tilting movement with respect thereto. To so mount the carriage 4D on the carriage 36, longitudinally spaced, depending members 10 `are fixed tothe underside of the bed 4816i the carriage 40. Such members have arcuatelovver edges which are struck upon an arc having a center coincident with the longitudinal center line of the blade, which may be considered as the center line of the mandrel 62. The arcuate edges of the member are generally V-shaped in section, as best shown in Fig. 6. The arcuate edges of the member 16 are adapted t0 be supported upon frusto-conical shaped roller members 12. Such roller members 12 have projecting shafts which are rotatably received within bearings 14 mounted upon the top surface of the carriage 36. The centers of the bearings 14 and, consequently, the centers of the rollers 12 are disposed on an arc about the same center as the arcuate edges of members 10. With this construction, it will be seen that due to the V-edge of the member 10 and the engagement with the roller 12 that the carriage 40 will reciprocate with the carriage 36 but may transversely tilt with respect thereto.

Means are provided for reciprocating the carriage 36, and, in the embodiment illustrated, such means is an hydraulic means. The hydraulic reciprocating means here shown is formed of conventional elements and includes an hydraulic cylinder 16 having one end thereof pivotally connected to a transverse pivot shaft 18. Such pivot shaft 18 is mounted upon the end upright members 31, as indicated in Fig. 2. The cap end of the cylinder 16 has the usual reciprocating piston rod 80 projecting therefrom, and the end of such piston rod 80 is connected to the forward end of the table 36 through a depending bracket 82.

Fluid under pressure, from a suitable source, not shown, is introduced into the opposite ends of the cylinder 16 for the purpose of reciprocating the piston rod 80. A conventional control means indicated at 84 is provided in the hydraulic system for controlling the flow of fluid under pressure to the opposite ends of the cylinder 16. Such control means 84 has a hand control thereon for starting and stopping the machine and also has upstanding control fingers 86, which are operatively connected to the control means 84 through a shaft 90. The fingers 86 are of different lengths and are laterally offset and are adapted to be engaged by actuating fingers mounted on the carriage 36 as it reciprocates. One of such fingers is indicated at 92 and it is mounted upon one of the side edges of the carriage 36. It is mounted within a longitudinal groove on the carriage 36 and may be adjustably set within such groove so that the length of stroke, or the point of reversal, of the hydraulic cylinder and piston may be varied. The nger 92 is suitably positioned in the proper location along the length of the carriage 36 and another similar finger 94 is similarly adjustably positioned at a point spaced from the linger 92. It will thus be seen that as the carriage reciprocates in one direction, the finger 92 engages and pivots one of the fingers 86 to rotate shaft 90 to thereby reverse the control valve 84; and when the carriage moves in the opposite direction, the finger 94 engages and pivots the other finger 86 to effect a reversal. Thus, the carriage is caused to reciprocate as long as the iiuid pressure is supplied to the hydraulic cylinder.

The abrading means includes a pivotally mounted abrading head generally indicated at |0I. Such abrading head |0| includes a pair of side arms having upstanding portions |02 and longitudinally projecting portions |04. A transverse mounting plate |06 is formed integral with the upright portions |02 of the side arms and extends therebetween. The side arms, together with the mounting plate |06 are pivotally mounted to the standards 22 and 24 by means u! aligned, horizontal stub shafts ||0 which are supported within bearing brackets ||2 mounted on the standards 22 and 24,

The arm portions |04 may be connected together by means of a bracing rod I|4 adjacent the free ends thereof. Roller elements ||6 are pivotally mounted on aligned, horizontal pivotV shafts to the free ends of the arm portions |04. The function of such rollers |06 will be described in detail hereinafter.

A cylindrical pressure roller ||8 is pivotally mounted to the lower ends of the arms |20 of a mounting bracket |22. Such mounting bracket |22 has a transverse portion which is integral with the upper ends of the arms |20. The mounting bracket |22 is mounted to the mounting plate |66 for vertical adjustment thereon.V In order to so mount the bracket, vertical guide .posts |24, which are cylindrical in form, are mounted on the face of the mounting plate |06 in spaced relation thereto. The ends of such guide bars are secured to outwardly projecting brackets |26 which are fixed to the front of the plate |06 adjacent the upper and lower ends of the guide bars. Such guide posts |24 are, of course, parallel and are slidably received within bearing sleeves secured to the rear face of the transverse portion |22.

The mounting bracket |22 may be vertically adjusted with respect to the plate |06 and is held in adjusted :position by means of a depending screw |28, the lower end of which is threaded and is threadably received within a nut fixed to the back face of the bracket |22. The upper end of the shaft |28 is supported within a worm gear housing |30 so that the bracket |22 together with the roll ||8 is held in its vertically adjusted position. The upper end of the screw shaft |28 has a worm wheel attached thereto which meshes with a worm on the end of shaft |32. rihe shaft |32 projects from within the housing and has a hand wheel |34 connected thereto. The shaft |32 passes through and is supported by an indi-Y cator housing |36 which is mounted upon the upper end of one of the side arms |02. That portion of the shaft |32 within the housing |36 is connected through suitable gears with the indicator means so that as the wheel is turned. the amount of vertical adjustment of the roll H3 is indicated.

In the embodiment illustrated, the indications are in thousandths of an inch and the scale would indicate forty thousandths for one revolution of the indicator. It will thus be seen that the indication is quite accurate in that the present invention is designed for precision work. It will also be understood that the gearing which controls the vertical adjustment of the roll I8 must be accurate and such gears have substantially zero back lash.

The abrading belt |40 is attainable on the commercial market. It is fieXible in character and has the abradant secured to the outer surface thereof. Such abradant may be of the required and predetermined grade and ineness. be appreciated that for the roughing work,a belt having a relatively coarse abradant thereon may be used, while for the finishing operations a belt It Will removably Xed to the V-iianges |98 and provide for fixing the two sections together across the space 202 therebetween. The belt is adapted to be passed through the space 202 as shown in Figs. 9 and 10. While the upper section of member 22 is of a rugged character and would probably support itself during the period that the members 2&0 are removed during the application of the belt, a temporary supporting bar 204 is removably mounted to the two sections through bolts 206.

The members 200 are held together by means of tie bolts 208 which are passed between the members 200 within the space 202.

To apply a new belt, the member 204 is first removed and the inside loop of the belt |40 positioned as shown in Fig. 9. The bar 204 is then iixed in position and the tie bolts 208 removed so that the members 200 may be removed. The bracket portion |56 is also removed. The belt may then be passed through the space 202 as indicated in Fig. 10 and may then be positioned about the rollers H8, |42, |44 and |46. Thereafter, the members 200 may be repositioned and Xed in position as shown in Figs. 1 and 4.

A bracing rod 2|0 has one end thereof Xed to standard 24 and the opposite end thereof fixed to standard |52 so that these elements of the machine are properly spaced and placed with respect to each other.

Referring to Figs. 11 vthrough 15, the machine of the present invention is illustrated wherein it is adapted for the finishing or polishing of the camber side of the propeller blade. The machine is generally similar to that described above and corresponding reference numerals have been used to designate corresponding parts. The main differences in the structure, over that for the at side described above, are that the roller |46 is so positioned that the belt approaches the propeller blade for engagement therewith in a substantially horizontal plane or at a slight angle to the horizontal so that the blade is only engaged in line contact under the contact roll. The contacting roller is of a different structure in that its peripheral surface is contoured completely therearound to correspond to the contour of the camber along the length of the blade.

The probeller blade is xed to the carriage 40 in the same manner as that described above eX- cept that the cambered side of the blade is disposed upwardly. It will be understood that the camber on the blade varies from one end of the blade to the other and that the width and the thickness of thel blade also vary. The blade is twisted about its longitudinal axis on substantially a helix so that the cambered side is twisted as well as the at side.

The roller |46 is mounted to a depending yoke bracket 2H, which corresponds to the bracket |84 above described, and the bracket 2|| is disposed downwardly so that the belt |40 approaches the point of contact with the blade in a substantially horizontal plane, or a plane which is at a very slight angle to the horizontal. The reason for this is to insure line contact only with the blade while providing for easy shaping of the belt when it is engaged by the pressure roller and forced into transverse line contact with the blade.

The peripheral portion of the roller 2 l2 is built up of wooden edge pieces 222, which are disposed on inwardly directed peripheral flanges on the end members 2|4 and ZIB, and which may be secured thereto by screws 224 passed through radial flanges formed adjacent the periphery of the end members. The circumference of the roller 2|2 is the same as the length of the propeller blade to be nished. The edges of the wooden members 222 are then formed to provide an annular groove which when developed corresponds to the cambered side of the blade. Such groove is indicated at 226.

The groove is accurately formed so that it has transverse portions which correspond to transverse portions along the length of the blade. One manner in which the groove 226 may be accurately formed is to rst form a rough groove which generally corresponds to the finished groove. Then a master blade may be mounted on the machine and the abrading belt reversed so that the smooth side of the belt is on the outside and the abrading side disposed to engage the peripheral surface of the roller 2 I2. By then reciprocatingthe carriagev in the same manner that is used when finishing a blade, and driving the belt and at the same time interconnecting the wheel 2 l2 with the reciprocating carriage so that it moves in synchronism therewith, the blade will be forced to follow the contour of the master blade and will be forced into engagement with the peripheral surface of the wheel in such shapes as to accurately finish the groove 226. Such groove 226 will then conform exactly to the cambered contour of the blade.

The groove 226 may be more deeply formed, to a predetermined amount, than the nished article and then such peripheral portion may be covered with an asbestos material, or the like, to take up the oversize, if desired.

In finishing a blade, the belt |40 is, of course, positioned with the abradant disposed outwardly. Such belt is driven counterclockwise, viewing Figure 12, and as it approaches the roll 2|2, it is engaged by the peripheral surface of such roll and urged against the cambered side of the blade. The belt is caused to follow the contour of the peripheral surface of the roller 2|2, as shown in Figure 13.

The purpose of leading the belt |40 to the wheel 2|2 in a substantially horizontal plane is that there is a tendency for the belt to curl transversely and by bringing it into contact with the roller 2|2 in this position, the belt will conform more readily to the peripheral contour of the wheel 2 I2 than it would if it were brought in at an angle.

Also, it will be seen that when the belt |40 leaves the roller 2|2, it must be angled upwardly to its position about the drive roller |42. While in contact with the roller it is curved upwardly, as shown in Figure 13, and it is diiicult to bend the belt in the required direction. To decrease this quick change in direction of the belt and to facilitate the change in direction of travel of the belt, a straightening roller 230 is disposed between the rollers 2|2 and |42. Such roller 230 has its peripheral surface slightly curved as shown in Figure 15 so that it partially straightens the belt transversely and reduces the angle which the belt must turn in passing from roller 2 |2 to the roller |42.

The roller 230 is mounted upon a shaft 232, the

ends of which are disposed within suitable bearings 234.V Such bearings 234 may be removably mounted to the upper ends of standards 236 which are xed to the side members. 32.

Means are provided for synchronizing the movement between the carriage 40 and the roller 2|2 as the carriage is reciprocated with respect to the roller so that the proper transverse line of the groove 226 will engage the belt |40 to give it the proper contour for the corresponding transverse line on the cam-bered side of the blade. In the embodiment here illustrated, such means includes an annular drum member 238 which is fixed to the end member 2|6. Such member 238 is provided with a spiral groove 240 therein, and the circumference of the member 238 is the same as the length of the blade. A cable 242 is disposed within the groove 240 and is welded to the groove, as indicated at 246. The ends of the cable 242 are crossed and extend in opposite directions. Such ends are secured within clamps 248, which are mounted to brackets 25D. The brackets 250 are secured to the ends of carriage 36, The ends of the clamps 248 are threaded and lhave nuts associated therewith so that they may be drawn up to tension the cable 242 and to take up any elongation which may develop therein.

It will thus be seen that as the

carriages

36 and 40 reciprocate, the carriage 40 transversely tilts and Ithe roller 2 l2 is caused to rotate in synchronism with the recprocation of the carriage.

.Instead of using the cable and drum connection here shown, it will be understood that the same synchronous movement between the pressure roller and the blade or blade carriage may be obtained by the use of a gear and rack. In such event, the rack would be mounted on the carriage 36 and would be adapted to mesh with a spur gear which would correspond in position to the drum 238. With the rack and gear, adjustments may be more easily made.

What is claimed is:

1. Apparatus for finishing and contuoi'ing a propeller blade, comprising a standard, an elongated article support mounted on said standard for Vreciprocable movement thereon, an endless abrading element mounted vabove and adjacent said article support, a roller element having a length greater than the width of the article being formed, means pivotally mounting said roller transversely of said article support above the lower reach of said abrading element for free vertical movement so that said rroller element is disposed to engage and urge said abrading element into engagement with the article, means mounting said article support for tilting movement with respect to said roller element in a plane substantially normal to the` direction of said reciprocable movement, elongated cam means mounted on said article support for movement therewith .and having a cam surface facing said -roller element, follower means mounted on said `mounting means for the roller element and movable therewith,.said follower means engaging said Yelongated cam means to cause said support to tilt -to various angles as it reciprocates with respect to Vsaid roller element, means for adjusting said roller 'with re-l spect to the article support independently .of the position of the follower :means-.means for reciprocating said support, and means for driving said abrading element.

2. Apparatus for nishing `and icontouring a propeller blade, comprising astandard, an elongated article support mounted .on said .standard for reciprocable movement thereon, 4endless abrading element mounted above. and adjacent said article support, aroller element having a length greater than the width of the article being formed, means` pivotally mounting said roller transversely of saidv article support above the lower reach of said abrading element for free vertical movement so that said roller element is diss posed to engage and urge said abrading element into engagementy with the article, means mounting said article support for tilting movement with respect to said roller element in a plane normal to the direction of said reciprocable movement, elongated cam elements mounted on said article support along the sides of the article on said support and having cam surfaces facing said roller element, followers mounted on said mounting means for the roller element above said cam elements and movable therewith, said followers engaging said cam elements to cause said support to tilt to various angles as it reciprocates with respect to said roller element and to control the pivotal movement of said roller about its pivot mounting means for adjusting said roller with respect to the article support independently of the position of the followers, means for reciprocating said support and means for driving said abrading element.

3. Apparatus for finishing and contouring a propeller blade, comprising a standard, an elongated article support mounted Von said standard? for reciprocable movement thereon, an endless abrading Yelement mounted above and adjacent said article support, -a roller element having a length greater than `the width of the article being formed, means pivotally mounting said roller transversely of said article support above the lower reach of said abrading element for free vertical movement so that said roller element is disposedto engage and urgesaid abrading element into engagement with the article, means mounting said article support for tilting movement with respect to said roller element in a plane normal to the direction 0f said reciprocable motion, elongated cam elements mounted on said article support and having cam surfaces facing said roller element, roll followers mounted on said mounting means for the roller element and movable therewith, said followers being disposed outwardly of said roller element and engaging said cam elements to cause said support t0 tilt to various angles as it reciprocates with respect to said roller element, means for adjusting said roller with rcspect to the article support independently of the position of the follower means, means for reciprocating said support and means for driving said abrading element.

4. In a blade finishing machine, in combination, a frame, a blade support on said frame, a head bracket adjustable on said frame relative to said support, a roll carrying bracket supported on said head 'bracket and adjustable relative to the latter and to said support, a pressure roll carried by said last mentioned bracket and aoljustable therewith, a plurality of guide rollers carried by said frame in parallel relation with said roll on opposite sides of said roll and having their axes of rotation disposed within the vertical limits of said roll, an abrasive belt running over said rollers and having its lower reach 'passing beneath said roll and in engagement therewith, and means on said frame for maintaining said belt under substantially constant tension during operation for various adjustments of said brackets.

` 5. `1in a blade finishing machine, in combination, a frame, a horizontal blade support on said frame, a head bracket adjustably supported on said frame, a roll carrying bracket adjustably supported on said head bracket, a pressure roll carried by said last mentioned bracket adjustable therewith, a plurality of guide rollers carried by said frame in parallel relation with said roll on opposite sides of said roll and having their axes of rotation disposed within the vertical limits of said roll, an abrasive belt running over said rollers having one reach thereof passing between said roll and the blade on said support, means for reciprocating said support longitudinally of the blade supported thereon, means including a driving pulley fast on one of said rollers for moving said belt over the blade on said support, and means carried by said support and roll for oscillating said roll in timed relation to the reciprocations of said blade.

6. In a blade finishing machine, in combination, a frame having a generally horizontal bed, a carriage movable along said bed, a blade supporting cradle carried by said carriage and rockable transversely thereof, a head bracket adjustably supported on said frame, a roll carrying bracket adjustably supported on said head bracket toward and from the blade on said supporting cradle, a plurality of guide rollers carried by said frame in generally parallel relation on opposite sides of said roll, an abrasive belt running over said rollers having a reach thereof passing between said roll and the blade on said cradle. means for reciprocating said carriage to move the blade longitudinally beneath said roll, means for reversely rotating said roll by the reciprocation of said carriage, and means for adjusting said roll carrying bracket to move said roll toward and from said blade.

ERNEST E. MURRAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS