US2367916A

US2367916A - Method and means for profiling airscrew blades or the like

Info

Publication number: US2367916A
Application number: US503008A
Authority: US
Inventors: Arthur M Young
Original assignee: Bell Aircraft Corp
Current assignee: Bell Aircraft Corp
Priority date: 1943-09-18
Filing date: 1943-09-18
Publication date: 1945-01-23
Anticipated expiration: 1962-01-23

Description

Jan. 23, 1945. A. M. YOUNG 2,367,916

METHOD AND MEANS FOR PROFILING AIRSCREW BLADES OR THE LIKE Filed Sept. 18, 1943 2 Sheets-Sheet 1 INVENTOR Arthur M. Yaung @n aa zwvaw ATT RNEYS A. M. YOUNG 2,367,916

METHOD AND MEANS FOR PROFILING AIRSCREW BLADES OR THE LIKE Jan. 23, 1945.

Filed Sept. 18, 1945 2 Sheets-Sheet 2 INVENTOR Arthur M. Youn ATTORNEYS Patented Jan. 23, 1945 METHOD AND MEANS FOR PROFILING AIR- SCREW BLADES 01;. THE LIKE Arthur M. Young, Bufialo, N; Y., assignor to Bell Aircraft Corporation, Buffalo, N. Y.

Application September 18, 1943, Serial No. 503,008

8 Claims.

This invention relates to methods and means for manufacturing airscrew blades such as airplane propeller or helicopter rotor blades, or the like; and more specifically relates to the profiling of blade blanks into the prescribed airfoil forms thereof.

One of the objects of the invention is to provide improved means for the purpose aforesaid, which means are of simplified mechanical character and adapted to be employed with improved facility and accuracy to produce airscrew blades or the like having taper and twist and airfoil sections of any desired description. Another object is to provide an improved method of shaping standard stock pieces into finished blade profile form with maximum accuracy and minimum labor. Other objects and advantages of the invention will appear from the specification hereinafter.

In the drawings:

Fig. 1 is a perspective of a rotor or propeller blade blank having templet devices of the invention mounted thereon preparatory to processing in accord with the method of the invention;

Fig. 2 is an end view of a machine for practicing the method of the invention;

Fig. 3 is a top plan of the machine of Fig. 2;

Fig. 4 is a side elevation thereof;

Fig. 5 is a perspective of another form of blade shaping machine arrangement of the invention; and

Fig. 6 is a fragmentary end view of the machine of Fig. 5 in operation against a blade blank.

The invention contemplates generally the mounting of a plurality of templets upon a stock piece which has been previously cut to the general or overall sectional dimensions of the article to be formed; the templets being in the form of simple plate-like elements which are centrally apertured and slipped into position upon the blank at intervals in the spanwise direction thereof. The templets are perimetrically contoured so as to have outer profiles paralleling the corresponding prescribed sectional profiles of the article to be finished at the positional stations thereon of the respective templets.

Thus, as illustrated in Fig. 1, a blade blank I is first prepared by planing or otherwise shaping a wood or metal stock piece so as to embo-dy the prescribed overall taper pattern of the blade to be finished, whereby the sides of the blank H) are closely tangential to the final profile form and dimensions of the finished blade.

' from one end thereof to the other.

be performed to provide either a rectangularly sectioned or a round sectioned blank; but as illustrated by Fig. 1 the initial shaping operation has been performed by simple planing or sawing methods whereby the blank I0 is of rectangular sectional form. Also, to provide a finished blade of spanwise tapered form, the blank I0 has been cut to taper gradually in sectional dimensions A plurality of templets designated |2-I4|6-I8 are shown as being slip-fitted into their proper stational position upon the blank; the templets having been first centrally apertured so as to accurately complement and fit upon the blank at the prescribed positions thereof. As indicated at 19, each templet is perimetrically profiled to be exactly parallel to the prescribed profile of the blade to be finished at the respective station of the templet.

It is arranged to mount a circular saw 01' abrading wheel or any other suitable form of revolving cutter device upon a mounting frame in conjunction with a guide so arranged that the guide portion of the mechanism may be disposed to bear against the rims of adjacent of the templets above referred to while the revolving cutter engages the excess portions of the blank between the positions of the templets supporting the guide.

For example, as illustrated in Figs. 2,. 3, 4, the shaping mechanism may comprise a pair of circular saw blades which are mountedaxially of a guide bar 22 which is in the form of a metal tubing interrupted centrall thereof to accommodate the cutter and carried at opposite ends thereof by means of arms 2424 which extend in turn from opposite ends of a cross bar 26. Thus, the cutter support devices provide a square frame or truss comprising the guide bar 22; the arms 24-24; and the cross bar 26. A bracket 28 is mounted upon the guide bar 22 to bridge the gap therein occupied by the cutter devices 20 and to mount thereon an electric motor 30 for driving the cutter 20 through means of a power transmission belt or the like at 32. Diagonal braces 34--34 are carried by the guide bar 22 and the bracket 28 to provide a rigid truss structure.

Thus, the initial stock shaping operation may The cutter support frame is mounted for universal movement of the butter in vertical directions, by means of a pair of stirrups 36-35 which pivotally connect to the cutter support frame at 38 and suspend from a carrying bar which is in turn positionally fixed by means of crooked supports 42-42 extending vertically and in furnished at 48 to extend as explained herein'above shaped and arranged that the guide bar 22 will,

be supported thereby in such manner as to permit the cutter 20 to penetrate into the stock piece between the templets only to the desired depth at any position along the length of the stock piece, whereby to enable the cutter to bring the stock piece into exact conformity with the prescribed surface formation of the blade. If

'the blade blank to be processed is of regular rectangular form; that is, not tapering from one end toward the other, the guide bar 22 will of .course be supported by adjacent of said templets to be disposed exactly parallel at all times to the prescribed contour surface for the finished blade. Whenever a tapering blade is to be produced the blade stock piece is preferably blocked up upon its supports in such manner that the surface portions of the templets to be simultaneousl contacted by the cutter guide bar-22 will be disposed substantially parallel to the guide bar; and to this end the blade stock piece will be necessarily shifted from time to time as diiferent portions of the stock piece are to be surfaced. Also, in such .cases the connections between the ends of the cutter guide bar 22 and the corresponding support arms 24-44 may be slightly loosened if necessary so as to allow the guide bar 22 freedom to adjust itself to make full contacts with the guiding templets.

The stock piece may be shifted longitudinally.

while in operative position under the cutter, and may be rolled about its longitudinal axis; but under all conditions the guide bar will automatically control the cutting operation to reduce the stock piece only to prescribed surface-forma-.

tion and dimensions of the blade to be provided. It will be appreciated that an important feature and advantage of the invention is that the apparatus and method herein described may be successfuly employed by relatively unskilled workmen without danger of harming the work blank as by exceeding the prescribed depth of cutting at any position along the blade. As shown in Figs. 1-2., a control handle may be from the bracket 28 to provide a convenient hand hold device for manual control of positional adjustments of the cutter device. The power conductor or lead for the motor 30 may be conveniently arranged to be carried by the handle,'as indicatedat 48 (Fig. 2).

Whereas, the apparatus of Figs. 2-4 is particularly suited to the processing of relatively heavy blade blanks, Figs. and 6 illustrate another form of apparatus for practicing 'the'method of the invention upon blade blanks which are of such light weight to be adapted to be handled freely by one or more manner as to be lifted bodily and applied against the cutter and shifted longitudinally and rolled ing process is complete. In this case the-apparatus comprises a frame consisting of a'baseboard 50 and a backboard 52 connected together at right angles and mounting a rotary cutter workmen in such until the blade'finishfinished to the prescribed finished at the station comprising,

.ment

templets, said cutter .device having guide means as indicated at 54 to extend at its cutting edge portion into the space between the baseboard and backboard. A guide pillow of cylindrical surface form is provided at 56 to parallel at its outer surface portion the contour of the cutter 52, but to be of a, radius lesser than the radius of the cutter 54 by the same amount that the templets on the work blank are greater in dimension than the profile to which the blank is to be reduced. Thus, the stock piece carrying templets as illustrated in Fig. 1 may be disposed to lie upon the guide block 56 as illustrated in Fig. 6, whereupon the templets will maintain the blank in proper position relative to the cutter blade so as to permit the latter to reduce the stock pieceonly to the prescribed degree. The stock piece may thereupon be rolled and shifted longitudinally from the position shown in Fig. 6 at the will of the operator, whereby the entire outer surface of the stock piece will be blade contour without danger of overcutting.

I claim:

1. The method of profiling an airscrew blade comprising, first shaping a blade stock piece into the form of a quadrilateral section blank which is tapered in the spanwise direction thereof and whereby the sides of said blank are made approximately tangential to the prescribed profile form of the blade to be finished, slidably mounting a plurality of centrally apertured sheet material templets upon .said blank at stations thereon spaced in the spanwise direction thereof. said templets having their respective perimetric portionsso dimensioned and shaped as to parallel the sectional profile of the blade to be thereon corresponding to the positions of said templets, and then bringing a rotary cutter into stock removing engagement with said blank at positions between said templets, said cutter having guide means carried therewith to engage perimetric portions of adjacent of said templets between which the stock reducing operation is progressing whereby said guide means limit the depth of stock reduction to the prescribed profile dimensions of the fin ished blade.

2. The method of profiling an airscrew blade first shaping a blade stock piece into the form of a blank whichis tapered in the spanwise direction thereof and whereby the sides of said blank are substantially tangential to the prescribed sectional profile form of the blade to be finished, mounting a plurality of templets upon said blank at stations thereon spaced in the spanwise direction thereof, said templets being so arranged and having their perimetric portions so dimensioned and shaped as to equidistantly paralled the sectional profile prescribed for theblade to be finished and then moving a stock cutter device into stock removing engagewith said blank at positions between said carried therewith to engage perimetric, portions of adjacent of said templets between which the stock is being reduced whereby said guide means limit the depth of stock reduction to the prescribed profile of the finished blade.

3. Means for profiling an airscrew blade comprising, a plurality of centrally apertured sheet material templets adapted to be slidably mounted upon a-blade blank at stations thereon spaced in the spanwise direction thereof, said templets having'their respective perimetric portions so dimensioned and shaped as to parallel the sectional profile of the blade to be finished at the station thereon corresponding to the position of said templets, and a rotary cutter device adapted to be moved into stock removing engagement with said blank at positions between said templets, said cutter device having guide means carried therewith to engage perimetric portions of adjacent of said templets between which the stock is to be reduced whereby said guide means limit the depth of stock reduction to the prescribed profile and dimensions of the finished blade.

4. Means for profiling an airscrew blade comprising, a plurality of templets adapted to be mounted upon a blade blank at stations thereon spaced in the spanwise direction thereof, said templets having their respective perimetricportions embracing said blank externally thereof and so dimensioned and shaped as to parallel the sectional profile of the blade to be finished at the stations thereon corresponding to said templets, and a cutter device adapted to be moved into stock removing engagement with said blank at positions between said templets, said cutter device having guide means carried thereby to abut perimetric portions of adjacent of said templets between which the stock is to be reduced whereby said guide means limit the depth of stock reduction to the prescribed profile of the finished blade.

5. The method of shaping a stock piece into curved surface article form comprising, first shaping the stock piece into the form of a blank having the sides thereof approximately tangential to the prescribed profile form of the curved surfaces to be finished, slidably mounting a plurality of centrally apertured sheet material templets upon said blank at stations thereon spaced in the spanwise direction thereof, said templets having their respective perimetric portions so dimensioned and shaped as to parallel the sectional profile of the article to be finished at the station thereon corresponding to the positions of said templets, and then bringing rotary cutter means into stock removing engagement with said blank at positions between said templets, said cutter means having guide means carried therewith to engage perimetric portions of adjacent of said templets between which the stock reducing operation is progressing whereby said guide means limit the depth of stock reduction to the prescribed profile dimensions of the finished article.

6. The method of finishing a stock piece into tapered and curved surface article form comprising, first shaping the stock piece into the form of a blank which is tapered in the spanwise direction thereof and whereby the sides of said blank are made approximately tangential to the prescribed profile form of the article to be finished, slidably mounting a plurality of centrally apertured sheet material templets upon said blank at stations thereon spaced in the spanwise direction thereof, said templets having their respective perimetric portions so dimensioned and shaped as to parallel the sectional profile of the article to be finished at the station thereon corresponding to the positions of said templets, and then bringing rotary cutter means into stock removing engagement with said blank at positions between said templets, said cutter means having guide means carried therewith to engage perimetric portions of adjacent of said templets between which the stock reducing operation is progressing whereby said guide means limit the depth of stock reduction to the prescribed profile dimensions of the finished article.

7. Means for profiling a stock piece into curved surface form comprising a plurality of templets adapted to be mounted upon said stock piece at stations spaced in the spanwise direction thereof, said templets having their respective perimetric portions so dimensioned and shaped as to parallel the sectional profile of the article to be finished at the station thereon corresponding to said templet, and cutter means adapted to be moved into stock removing engagement with said stock piece at positions between said templets, said cutter means having guide means carried therewith to engage perimetric portions of adjacent of said templets between which the stock reducing operation is processing, whereby said guide means limit the depth of stock reduction to-parallel the profile of said article.

8. Means for profiling an airscrew blade comprising, a plurality of templets adapted to be mounted upon a blade blank at stations thereon spaced in the spanwise direction thereof, said templets having their respective perimetric portions embracing said blank and so dimensioned and shaped as to parallel the sectional profile of the blade to be finished at the stations thereon corresponding to said templets, and a cutter device comprising a rotary cutter mounted upon a base and a guide pillow of cylindrical surface form extending from said base and having the cylindrical surface portion thereof disposed concentrically of the axis of rotation of said cutter and at a distance inwardly from the peripheral portion of said cutter equal to the distance between the perimetric portions of said templets and the prescribed profile of the blade to be finished, whereby said templets-carrying blank may be moved into engagement with said cutter at positions between said templets, whereby said guide pillow cooperate-s with said templets to limit the depth of stock reduction to the prescribed profile of the blade to be finished.

ARTHUR M. YOUNG.