US2587603A

US2587603A - Turbine blade grinding machine

Info

Publication number: US2587603A
Application number: US93649A
Authority: US
Inventors: Sigmund A Czarnecki
Original assignee: United Aircraft Corp
Current assignee: RTX Corp
Priority date: 1949-05-17
Filing date: 1949-05-17
Publication date: 1952-03-04
Anticipated expiration: 1969-03-04

Description

March 4, 1952 s. A. czARNEcKl TURBINE BLADE GRINDING MACHINE 6 Sheets-Sheet l Filed May 17, 1949 March 4, 1952 s, A, CZARNEQKI 2,587,603

TURBINE BLADE GRINDING MACHINE Filed May 17, 1949 6 Sheets-Skaai'l 2 March 4, 1952 s. A. czARNl-:CKI

TURBNE BLADE GRINDING MACHINE 6 Sheets-Sheet I5 Filed May 17, 1949 www. .MNNNN .DBM

March 4, 1952 s. A. czARNEcKl 2,587,603

TURBINE BLADE GRINDING MACHINE Filed May 17, 1949 6 Sheets-Sheet 4 MalCh 4, 1952 s. A. czARNEcKl 2,587,603

TURBINE BLADE GRINDING MACHINE fiala 57W S. A. CZARNECKI TURBINE BLADE GRINDING MACHINE March 4, 1952 Filed May 17, 1949 l6 Sheets-Sheet 6 Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE 2,587,603 ZlUlRBIllE .lLDE GRINDINQ MACHENE Sigmund A. Czarnecki, Glastonbury, Conn., as-

signor to United AircraftI Corporation, East Hartford, Conn., a corporation of Delaware Application May 17, 194%?E Serial N o.- 93,649

20 Claims. (01.51-143) This invention relates t a, blade grinding machine, and particularly to a machine .for grinding turbine blades with an .abrasive .Cdllying belt.

A n object .of this invention is to. accurately and automatically shape, by grinding, the irregular contour of a turbine blade. A fl'llilher object is to grind the turbine blades with a substantial line Contact to reduce heat distortion in grinding. A still further object is to provide mechanism Which Will cause the abrasive bell? by reA peated passes to accurately form the irregular contour throughout the desired area. A further object is to provide a simple and efficient machine for rapidly Shaping irregularly shaped articles.

Other and additional objects and advantages will be apparent from the following speciiication and claims and from the accompanying drawings lin which Fig. 1 is a front elevation of the grinding Inachine;

Fig. 2 is a side elevation as seen from the right side of Fig. 1;

Fig. 3 is a top view of the grinder of Fig. 1;

Fig. 4 is a section taken on line 4 4 of Fig. 1;

Fig. 5 is a View taken along the line 5 5 of Fig. 4;

Fig. 6 is a sectional View taken along the lines 6 6 of Fig. 4;

Fig. 7 is a view similar to Fig. 6 showing a modified form of cam with the cam and forniing apparatus in operative position;

Fig. 8 is a section along line 8 8 o f Fig. 7;

Fig. 9 is a section along line 9 9 of Fig. '7;

Fig. 10 is a section along line in l of Fig. 4 showing the stop mechanism Fig. 11 is a sectional view on the line Il ll of Fig. 1;

Fig. 12 is a section through the form and blade support;

Fig. 13 is a schematic diagram of the belt tracting mechanism.

Turbine blades generally have an irregular carefully calculated curved convex airicilsurfA face on one side and a similar concave surface on the other side.

In the manufacture of turbine blades, and particularly blades for gas turbines, it has been customary to do the maior portion. of the forin- 2 .ing of tho blade contours by hand operation in order to obtain the necessary calculated irregular conteur to give eihcient gas flow. This has been a particularly tedious and Costly nroooss because the material of Whloh tho blades are Inade is guitevdiilioult to machine in comparison with the ordinary steel, and because removing material iroin these blades manually by means of a grinding or buinng Wheel causes local distortion 'and u .resulting ohongo in tho configuration of the blade, It thus becomes very difficult to manufacture a blade which will nt the contour gauges and not be subject to the material distortion duo to tlio local or .Spot heating caused, by tho hand Wheel-.aludida I, found it necessary to develop moans for pre- Santing Athe Werl; to the abrasive belt and the means for positioning the form roll with respect to the belt and the Work. I also found it necessary to develop a new mechanism for positioning the belt on the rollers and preventing it from oscillating with rosnoot to tho Work- This 1ndchine, which will be described hereinafter, has boon 'round to accurately and rapidly rooroddoo @ily ddled turbine blade shape which has been tried, and. to, .reproduce the blade contour to within limits of flvo-thousdndths of an inch or less. even when materially more Stock had to be removed `from .somo portions, of tho blade forging than other portions,

The operating part of tho mdohno in gonofol and as shown in Fig. ,1, comprises an abrasive belt 2B threaded over belt supporting surfaces of driving pulley 2.2s a ooiitoring pulley ii, a tonsioning pulley 25 and a form roll 2S. 'A motor 3i) drivespulley 22 to drive belt 2b in the direction tShown loy die arrows in Fia 1- A turbine blade 3| is held in a support 32 which osoilldtes or rotates in timed relation with form roll 28. The abrasive belt 2li travels transverse t0 the tulblle bldl? and. S folfdfd im@ @Ontai therewith by the form roll 21S to thoroloy remove stock. to sivo the lolado a Prosolootod Shane- Althourh in tho now 'loroiorrod embodiment and as in .tlio drawing tho olado and form osoilloto in. .tint/od relation, it will loo understood that the blade and form may, if desired, rotate in timed relationl making complete revolutions as. distinct .from odoilldtinsf Two or more blades may tnonloo Carried by tho work Support dt ono time. In such a construction the blade and form may be driven in timed relation by a bevel gear train or a worm and wheel construction and the drive taken through a sliding spline for a gear or splined telescoped shafts to provide for relative vertical movement of the blade and form.

structurally the machine in general comprises a main frame or base 34 supporting

columns

36 and 38 which in turn support a platform 46 on their upper ends. Bolted on to the main frame 34 at the front thereof is a sub-assembly indicated generally at 42 which carries the blade support 32 and the mechanism for oscillating the blade support shown generally at 44 (Fig. 1). A carriage generally indicated at 46 is mounted for vertical adjustment on columns 36 and may be clamped in adjusted position by clamps 48. Carriage 46 acts as a support for motor 36, driving pulley 22, tensioning pulley 26 and indirectly for other mechanism about to be described. Mounted on the carriage 46 is a slide or framework generally indicated at 56 adapted to slide vertically in gib 52. Slide 56 carries form roll 28 and centering pulley 24 as well as the mechanism for operating the centering roll and the mechanism for oscillating the form roll.

The vertical position of carriage 46 with respect to the base 34 may be adjusted by a screw 66. The position of the slide 56 with respect to the carriage 46 is determined by a cam 54. carried by carriage 46, and follower 56 mounted on spindle 58 carried by slide 56 hereinafter described in more detail. The slide 50 is continuously urged upwardly by a piston and cylinder 62, thus urging the follower 56 carried by slide 56 into contact with the cam 54 carried by carriage 46 normally clamped to

columns

36 and 38.

From the above brief description it will be apparent that the work support is located in a iixed vertical position by being secured to the base 34 and that the form roll 28 is carried by a slide 50 which may be moved vertically in the gib 52 by cam 54 and follower 56 to position the form roll with respect to the work.

The nal position of the form roll with respect to the work is determined by the position of carriage 46 which in turn is adjusted by the screw 66.

Provision is made for successive passes of the work with respect to the belt by oscillating the work and form roll in timed relation and for intermittently moving cam 54 in step by step movement so as to force the form roll toward the work in predetermined steps. Hence, each time that the work oscillates under the form roll the relative vertical positions of the work and form roll are adjusted so as to remove a limited predetermined amount of stock at each pass.

By running the abrasive belt transversely over the blades, and having the belt approximately as wide as the surface of the turbine blade to be ground, it is possible to grind the entire length of the blade surface in one pass. It will be appreciated that, due to the relative rolling action of the form and blade, the grinding will take place along a substantially line contact. The blade 3| to be ground is mounted in a support 32 and accurately positioned by locating pins "64 (Fig. 4), and clamped and rigidly held in its support by clamp 66. Support 32 is mounted on a spindle 68 which in turn is mounted in bearings for oscillating movement in a frame 16 which in turn is mounted on the base 34.

A gear 12 keyed to spindle 68 is driven by rack l.

14 to oscillate the spindle and the work carried thereby. Rack '14 is mounted on slide 16 which is slidably mounted in slots in frame 16. Screws 18 passing through slots in slide 16 serve to hold the slide in position and also guide it in its reciprocating movement. Slide 16 is driven from another slide 86 by means of a latch 82 carried by slide 86 and a pin 84 carried by slide 16. Slide 66 reciprocates in a slot in frame 16 and is held in position by a screw 86. Latch 82 may be operated under certain conditions to be described later to disconnect slide 86 from slide 16 so that operation of slide 86 will have no effect on slide 16. A leaf spring 88 continuously urges latch 82 into latching position as shown in Figure'. Slide 86 is reciprocated by a pin' and crank mechanism shown generally at 44 driven by a motor 92 secured to any suitable support such as the support on which the frame or base 34 is mounted. As shown in Figure 9 the stroke of the slide 86 may be adjusted by positioning the adjustable crank pin 94 in the slot 86 in the plate 98. A resilient connection |66 is provided between the crank pin 94 and the sleeve 86 to prevent breakage of the parts in theevent of jamming,r of the slide 86 or its connected4 parts and also to provide for any desired adjustment.

From the mechanisml just described, it is obvious that the operation of motor 92 and the pin and crank mechanism 44 will when the latch 82 is inl latching position reciprocate rack 14 and thus oscillate spindle 68 and the turbine blade carried thereby.

Form roll 28 is keyed to spindle 58 which is` mounted in slide 56. Also keyed to spindle 58 is a gear |62 which meshes with a rack |64 carried by a slide |66 slidably positioned in a slot in slide `56. Slide |66 is held in position and additionally guided by screws |68 passing through slots in slide |66 and into slide -56 as shown in Figure 8. Slide |66 is connected to and driven from slide 16 by means of pins ||6 carried by slide |66 and receivable in sockets ||2 in slide 16 when slide 66 is in its lowered or operative position as shown in Figure '7. A catch ||4, carried by slide |66 is adapted to co-act with a projection ||6 formed on the end of pivoted arm ||8 having a common pivot with latch 82 so that when slide 56 is raised carrying with it slide |66, catch ||4 will lift arm ||8 to thereby unlatch 82 from pin 84 as shown in Figure 6, latch 82 being lifted by pin |26 carried by arm ||8, spring and plunger mechanism 66 serving to hold arrn ||8 and latch 82 in the elevated position.

This mechanism prevents the racks |64 and 14 and their associated gears from inadvertently getting outof register while in the separated position in the event the crank mechanism 44 should be inadvertently operated.

As the slide 56 decends a pin |22 carried by slide |66 contacts pivoted arm ||8 forcing it downwardly to bring latch 82 into latching position with pin 84 after connecting pins ||6 have started into sockets |12. Spring and plunger mechanism 86 will now hold arm ||8 in its lowered position. With the mechanism thus far described, it is apparent that operation of the pin and crank mechanism 44 will oscillate gears 12 and |62 in timed relation and will thus oscillate the turbine blade 3| to be ground and the form roll 28 in timed relation.

As indicated above, carriage 46 is vertically adjustable on-

columns

36 and 38 and carries the abrasive belt and indirectly the form roll 28 so that the Vertical position of carriage 46 determines the final position of the form roll with rearef/,eos

specttoblade 3| being ground. The vertical position of carriage .45 is adjusted by screw 60 threaded into carriage 46 and supported on platform ,40. A dial |24 secured to the upper end of screw 60 may be utilized to turn the screw and indicate the position of carriage 4.6. When the carriage has been adjusted to the desired position it may be held in position by being clamped to

columns

36 and 38 by clamps 48. Cam 5 4 is mounted on shaft |26 which in turn is rotatably mounted in bearings in carriage 46 (Figure 4). Provision is made for turning shaft |26 in a step by step motion from the reciprocating motion of spindle 58'. As shown in Figures 4 and 5, spindle 58 has an arm |28 keyed to the end opposite the form roll, which arm carries a roll |30. Two slides |32 and |34 are mounted for reciprocating movement in grooves in carriage 46. These slides carry depending lugs |36 and |38, respectively which have opposed vertical faces |40 and |42 respectively. Roll |30, near the end of each oscillation induced by oscillation Aof the spindle 56, contacts one or the other of vertical faces |40, |42. Slide |32 is spring pressed to the left, as seen in Figure 5, by spring |44 against a stop |46. When roll |38 contacts face |40 it will move slide |32 to the right. Rack |48 carried by slide |32, is accordingly moved to the right and gear |50 in mesh therewith is rotated in a counterclockwise direction as seen in Figure 5. Gear |50 is bolted to an arm |52 freely rotatable on shaft |25 and carrying a spring pressed pawl |54. Pawl |54 coacts with ratchet |56 keyed to shaft |26 so that counterclockwise movement of the ratchet carrying arm |52, as seen in Figure 5, will turn the shaft |26 and thus turn cam 54. The amount of movement is determined by the neutral or central position of slide |32 which in turn is determined by adjustable stop |46.

It will thus be apparent that as spindle 58 is oscillated to oscillate the form roll 28, cam 54 will be actuated at the end of each oscillation. As

will be explained more fully hereinafter, this movement of the cam 54 will serve to advance the form 28 toward the blade work piece 3| while the abrasive belt, positioned by the form roll 28, is out of contact with the blade 3|. Pawl |54 has an extension |62 extending through a stationary slotted arcuate member |64 and carries `a nut |66 on the opposite side of the arcuate member. Arcuate member |64 is carried by a rod |68 mounted for vertical reciprocation in carriage 46. Rod |68 may be vertically lifted from its position shown in Figure 5 by means of a lever |10, pin |12, shaft |14 and a handle |16 to thereby lift the pawl |54 out of operative engagement with the ratchet 56 while permitting the arm |52 to continue to oscillate if desired. With the automatic feed thus disconnected it is possible by removing cap |18 at the front of slide 50 to insert a Wrench through the hole |80 in slide 5.0 and .on to a milled portion I 82 of shaft |26 to therebymanually turn shaft |26 and the cam 54 andthus manually. position the form roll 28.

.As has been described above, spindle 58 carries a cam follower 56 which ,cooperates with cam 54.1110` position slide 5B with respect to carriage 46. The hydraulic or air cylinder and piston 62, being supplied with air or liquid under pressure from any suitablesource, not shown, continuously urges slide 50 upward, spindle 58 being carried entirely by slide 50 is accordingly also continu.v ousl-y urged upward and cam'follower 56 being carried by spindle 58 is thus continuously urged into contact with cam 54. Cam 54 being positioned by slide 46 which in turn is clamped to

columns

36 and 38, therefore, serves to position slide 50 with respect to the blade 3| being ground. As cam 54 rotates in counterclockwise direction as seen in Figure '1, it will contact the follower roll 56 first at A and then at B. As the cam moves over the follower roll from A towards B it gradually forces the form roll toward the work piece thus forcing the abrasive belt into vContact with the work piece. After the -form roll passes point B and reaches point C the slide 50 and the form roll will be withdrawn upwardly by the action of the piston Aand cylinder 62 to remove the abrasive belt from proximity to the blade 3| so that the linished blade maynow ybe removed .and another blade to be finished inserted. As cam 54 moves over the follower roll from position C to position A the slide 50 and cam roll 28 are again forced down into working relation with the new blade 3| thus again forcing the abrasive belt into contact with the blade.

The extent of oscillation is adjusted by means of crank pin 94 so that the blade is moved out of contact with the abrasive belt between successive passes at each end of the oscillation so that operation of ratchet wheel |56 to advance the cam 54 and form 28 will take place between successive passes and while the belt is out of contact with the work and no grinding is taking place.

It is possible to make almost any desired shape of turbine blade in this machine and it will be observed that, as the abrasive belt extends the full length of the blade as it travels transversely thereover, the entire length of the blade is subjected to the abrasive action at the same time. The feeding of the belt toward the work and the consequent pressure exerted thereby, is accurately controlled by means of the cam so that distortion due to local heating is thus entirely eliminated or greatly reduced over that which results from the normal hand grinding or bud-lng. The form roll 23 used is preferably a, non-yielding roll of hardened steel or the like. The blade has been shown in a position for use with a form roll for forming the outside or convex portion of the blade. It will be understood that by the use of an Iappropriate form roll the inside or concave portion of the blade can be accurately ground with equa1 facility. v

As was done in shaping the form for guiding the belt in grinding the aluminum blade in the machine in my Patent No. 2,426,764, the form in this machine is shaped to provide a developed impression of a surface of a finished work piece therein by inserting a, master blade inthe blade support or fixture 32 and reversing the belt 20 so that the abrasive side of the belt is adjacent the form roll. By then running the belt and oscillating the form and blade in the manner just described for grinding the blade, the master blade will serve as a Yformer for guiding the abrasive belt to properly shape the form roll. By then again reversing the belt so that the abrasive side is outside the shaped form roll 28 will act to guide the belt in a manner to reproduce on a forging clamped in xture 32, the form or shape of the master blade which was used to make the form roll 28. It is thus necessary only to provide a master blade which may be utilized to shape the form roll and it is not necessary to go through the tedious process of designing and then machining a form roll to produce the desired blade shape.

In some shapes wherethere is a sharp change in the contour of the article being produced it has been found that the resulting shape of the form roll had a tendency to cause the belt to grind off portions of the work piece Where it was not desired. rIhis was particularly true in grinding the leading and trailing edges of the turbine blade where it was found that if the beltwere pushed down far enough by the form roll to properly shape the leading and trailing edges it would tend to remove an undesired amount of stock from a portion of the blade adjacent the leading edge. This was due to the more or less sharp contours required in the form roll. I have found, however, that by employing an auxiliary cam |84, Figure 6, in place of follower roll 56 (Figure 7) I can change the shape of the form roll so as to make it very nearly cylindrical while still retaining a peripheral depression therein constituting a developed impression of a surface of a finished work piece capable of forming the same irregular shape that would be produced by a, form roll having reentrant portions which might cause an uncontrolled or undesired grinding. rIhe auxiliary cam |84 coacts with cam 54 in the same manner as described in connection with follower roll 56 except that instead of being mounted on bearings for free rotation with respect to spindle 58, as is roll 56, auxiliary cam |84 is keyed to spindle 58 to oscillate therewith. Spindle 58 thus acts as means for positioning cam |84 with respect to slide or framework c. In the form shown in Figure 6 auxiliary cam |84 will move form roll 28 toward blade 3| as it approaches the end of each oscillation. This was the portion of the form roll that had a high spot thereon in forming certain types of blades in the device shown in Figure 7. By thus moving the form roll downward by means of an auxiliary cam |84, Figure 6, it is possible to do away with this high spot on the form roller and thus provide a form roll which approaches a cylinder and which will not carry the abrasive belt into contact with any portion of the blade except the desired portions.

In order to keep the belt 2i! in position, transversely of the form roll and the pulleys, and longitudinally of the blade- 3|, I provide a tracking mechanism which consists essentially of a centering pulley 24 pivoted for oscillation transversely of the belt and a feeler mechanism indicated generally at |88 for detecting any rnisalignment of the belt and transferring this misalignment into a correcting movement of the centering pulley 24. r)The detecting mechanism, Figures 1, 11 and 13, comprises a support |88 carrying two series of nozzles, four xed nozzles 2| being shown in each series in the drawings, each nozzle having an outlet 2 l2. These nozzles control the bleeding of air from a double acting cylinder and piston |90, |9|, Figure 3, which is connected by means of a crank m2 to a yoke ld pivoted at |96 on a frame |98 bolted on to and extending out from slide 50. From this construction it will be apparent that movement of the piston |9| in the piston and cylinder device |90, |9| will oscillate yoke |94 carrying centering roll 24vabout pivot |96. This movement will cause the belt 20 to move transversely in one direction or the other as the roll 24 is oscillated in one direction or the other. The nozzles of the detecting device |86 are located directly under belt 20 and in contact therewith so as to be normally closed by the belt. The supply of air for the cylinder |90 comprises two separate lines 20G and 202 each having a regulatable restricted orice therein between the source of supply and the cylinder. The air may be supplied from any suitable source, not shown. Separate bleed lines 2M, 206 lead from the opposite ends of the cylinder |90 to the separate detecting mechanisms 208, 2 l0. The restrictions in the

line

200 and 202 are enough smaller than the outlets 2I2 in the detecting mechanism so that when the belt 20 uncovers a nozzle on one side and covers a nozzle on the other it will bleed the pressure from the side of the piston |9| connected with the uncovered nozzle causing a reduction in pressure on that side suficient to cause movement of the piston'ii by the pressure on the other side. This movement of the piston |9| immediately produces the corrective action necessary to restore the belt to its central position.

The belt tension is maintained by pulley 26 mounted on pivoted plate 2M and urged in a direction to maintain tension on the belt by a weight 2K5 connected to the plate 2|4 by the chord 2id extending over a pulley 22S.

While the final size of the nished blade can be determined by proper positioning of carriage l by screw ed, the final size may also be determined by operation of a micro-switch 222 mounted on carriage d5 and operated by an arm 224 secured by any suitable means such as set screw 22S to rod 22@ to shut cii the power to the abrasive belt when the form roll 28 has reached a predetermined position to give the blade its nal size.

It will be appreciated that by the use of suitable belts and abrasives the turbine blade may be nished and polished as well as being ground to size.

If desired a coolant may be used in the grinding or polishing operation.

It is to be understood that the invention is not limited to the specic embodiment herein illustrated and described, but may be used in other Ways without departure from its spirit.

I claim:

1 In a machine for forming' turbine blades or the like, a belt having an abrasive side and a smooth side, a blade support, a form adjacent said support for positioning said belt relative to a blade secured to said support and conforming said belt to form the desired blade shape, means for moving the adjacent surfaces of said form and blade in timed relation with the belt passing between them, means for moving said belt relative to said form and said blade with the abrasive side of said belt facing said blade, said surface moving means and said form alternately bringing said abrasive side and said blade into and out of Contact in successive passes, means relatively spacing said form and said support and means for determining the spacing of said form and said support while said abrasive side and said blade are in contact, means for automatically effecting adjustment of said determining means to effect relative adjustment of said form and said blade support toward each other and to determine the spacing of said form and said support while said abrasive side and said belt are in contact including means for effecting said adjustment in steps in timed relation to movement of said form between said successive passes and when said abrasive is out of contact with said blade.

2. In a belt grinder, having an adjustable beltpositioning and shaping form, and a work support, and having means for passing an abrasive belt between said form and said support for grinding irregularly shaped articles supported on said support, means for moving said form and work support in timed relation to alternately repeatedly position said belt on said work and space the belt therefrom in successive passes, means relatively spacing said form and said support and means for determining the spacing of said form and said support while the belt is positioned on said work, and means for automatically adjusting said determining means in steps in timed relation with said movement of said form and work to adjust said form and said work toward each other, and means timing said adjusting means so as to eiect said adjustment between passes when the belt is spaced from the work.

3. In a belt grinder, having an adjustable beltpositioning and shaping form and a work support, and having an abrasive belt and means for passing said belt between said form and said support for grinding irregularly shaped articles supported on said support, means for moving said form and work support in timed relation to alternately position said `belt on said work and space ,the belt therefrom in successive passes, means `relatively spacing said form and said support and means for determining the spacing of said form and support while said belt is positioned on said work, means for automatically relatively adjusting said determining means in steps in timed relation with the movement of said form and Work while the form and work are being driven by said moving means to progressively adjust said form .and said work toward each other.

4. In a belt grinder, having an adjustable beltpositioning and shaping form and a work holder, saidform being supported on a nivoted support and said work holder being supported on a pivoted. support, the pivot axes of both supports being parallel to each other, means for passing an abrasive belt between said form and said sun,- port between and transversely of said axes with the abrasive face of the belt substantially parallel to said axes and facing the work holder and positionecl and shaped by said form for grinding irregularly shaped work supported on said work holder, means for moving both sun-ports about their respective pivots in timed relation to move said belt positioning and shaping form and the Work supported on said work holder to alternatelv separate said abrasive belt andsaid work and. bring the abrasive side of said belt into contact with said work and maintain contact as belt moves progressively across the work, means for determining the spacing between said pivote-f?. supports during contact of said work and said abrasive, and means actuated between contact periods for adjusting said determining means to automatically reduce said spacing between said supports.

5. A device as described in claim 3 in which the form moving means includes a cam for moving said form toward said work as the form is moved in timed relation.

6. A device as claimed in claim 4 in which the automatic spacing reducing means includes a normally stationary abutment movable between contact periods and an auxiliary camv fixedwith respect to said form and contacting said :abut- 10 ment and movable with said form about the pivoted support for said form for positioning said form with respect to said work.

7. In combination, a belt, a tiltable g-uide for said belt, bleed nozzles arranged one adjacent one edge of said belt and another adjacent the other edge of said belt and normally closed by said belt, a source of iluid pressure, a double acting piston and cylinder construction connected with said tiltabl-e support for tilting the same, means connecting said source with both ends of said cylinder and means connecting one end oi said cylinder with one of said nozzles at one edge of said belt and the other end with another of said nozzles at the other edge of said belt, a restriction in each line between said source and the respective end oi said cylinder restricting the iiow through said lin-e to each cylinder end to less than the flow through an open nozzle whereby when the belt wanders sufliciently to uncover a nozzle, fluid will bleed from the respective end of said cylinder reducing the pressure on that end only to tilt said support and return said belt to centered position.

8. In a belt grinder having a transversely tiltable pulley over which the belt runs and which may be tilted transversely of the belt to transversely adjust the belt travel, a Source of fluid pressure, a chamber having a movable partition therein and connected on opposite sides of the partition with said source, two sets. of bleeder nozzles arranged one adjacent each edge of said belt with the nozzles of each set arranged transversely of said belt and with the belt passing over and closing said nozzles, a restriction in each connection between said sourcer and said chamber smaller than the restriction of said nozzles, said sets of nozzles being connected with said chamber, one on each side of said partition, means connecting said partition with said pulley to tilt said pulley transversely of said belt, whereby transverse movcment of said belt will uncover one or more of the nozzles of one set and bleed uid from one side of said chamber and partition to cause the pressure on the other side to tilt said pulley and return said belt to its original position.

9. A belt grinder having an abrasive belt led between a work piece supported on a work support and a rigid belt shaping form comprising, a pair of pivots having substantially parallel axes arranged transversely of said belt, a work support mounted to move about one of said pivots, a form mounted to more about the other pivot in timed relation to said movement of said work support, a frame supporting and locating said one pivot, a slide mounted on said frame for movement transversely of said pivot axes and toward and from said work support, said other pivot being mounted in and located by said slide, means for moving said work support and form about their respective pivots in timed relation to alternately bring said belt into contact with said work piece and out of contact therewith, an auxiliary cam carried by said slide and movable in timed relation with movement of said form about its pivot, and a movable abutment carried by said frame and means yieldingly urging said auxiliary cam into Contact with said abutment to position said slide and the form carried thereby and limit the movement of said slide while said belt is in contact with said work piece.

10, Means for forming an elongated turbine relation about parallel axes extending transversely of the run of said belt to present said blade to said belt and force the belt into conta-ct with said blade and to separate said belt and blade, means for spacing said form with respect to said blade support comprising a movable abutment having definite positions with respect to said blade support, an auxiliary cam, means mounted on said movable form support for relatively positioning said form and cam, means connected with said form for moving said cam in timed relation with the rotary movement of said form, means urging said form support toward said abutment to urge said cam into contact with said abutment and to Space said form from said blade support.

ll. In a belt sander having an unyielding form for guiding an abrasive belt to accurately form an irregular article from unyielding material, means supporting said form for movement about an axis, means for supporting said article for movement about an axis spaced from and parallel to said first mentioned axis, gear means for driving said form and article about said parallel axes in registering timed relation, means fo-r moving said form in a direction transversely of said axes toward and from said article, and means including a sliding connection for connecting the gear means driving said form with the gear means driving said article to permit said transverse movement of said form while maintaining said registering relation of said form and article.

l2. In a belt grinder, in which an abrasive belt is led between a work piece supported on a work support and a rigid belt shaping form, a pair of pivots having substantially parallel axes extending transversely of said belt, and substantially parallel to the face of said belt, a work support, a form support, one of said supports mounted to move about one of said pivots, the other support mounted to move about the other pivot means for moving said supports about their respective pivots in timed relation, a frame supporting and locating said one pivot, a movable framework supporting and locating said other pivot and mounted on said frame for movement 1n opposite directions along the same path transversely of said pivot axes and toward and from said one support, a movable abutment carried by said frame, means yieldingly urging said framework toward said abutment, an auxiliary cam, means on said framework coacting with said cam and yieldingly urging said cam into Contact with said abutment to positively position said framework, and the support carried thereby, with respect to said one support and limit the transverse movement of said framework, means for moving said cam in timed relation with said supports to repeatedly move said framework and said other support in one direction along a predetermined path transversely of said pivot axes toward said one support and in the opposite direction along the Same path away from said one support, while said supports move about their respective pivots, to repeatedly bring` said belt into contact with said work piece, psiiiiilly 1, 61-

atively locate said two supports while the belt is in contact with said work piece and separate said belt and work piece, and feed mechanism including means for moving said abutment in timed relation to movement of said supports about their pivots' to gradually feed said supports t0 ward each other.

13. In a belt grinder having means, including belt supporting surfaces, for leading an abrasive belt between a work piece supported on a work support and a rigid belt shaping form, a pair of pivots having substantially parallel axes extending transversely of and substantially parallel to the face of said belt supporting surfaces, a wol-k support, a form support, one of said supports mounted to move about one of said pivots, the other support mounted to move about the other pivot in timed relation to the movement of said one supA port, means for moving said supports about their respective pivots in timed relation, a frame supporting and locating said one pivot, a movable framework supporting and locating said other pivot and mounted on said frame for movement in opposite directions along the saine path transversely of said pivot axes and toward and from said one support, means for spacing said sup ports with respect to each other for grinding the work piece to a predetermined size by positioning said framework with respect to said frame, comu prising positioning means on said frame, .positioning means on said framework, and an auxil-i iary cam movable in timed relation with movement of said supports about their axes and cod acting with said positioning means to position said framework, means for yieldingly urging said framework toward the positioning means on said frame and urging said positioning means and said cam intocoacting relation while the work piece is positioned on the belt. Y

14. In a belt grinder having means, including' belt supporting surfaces, for leading an abrasive belt between a work piece supported on aqwork support and a rigid belt shaping form, a pair of pivots having substantially parallel axes ari-j ranged transversely of, and substantially parallel to the face of said belt supporting surfaces, a Workl support mounted to move about one of said pivots, a form mounted to move about the other pivot in timed relation to said movement of said work support, means for moving said work support and form about their respective pivots in timed relation, a frame supporting and locating said one pivot, a framework supporting and locating said other pivot and mounted on said frame for movement in opposite directions along the same path transversely of said pivot axes and toward and from said Work support, means for spacing said support and form with respect to each other for grinding the work piece to a predetermined size by positioning said framework with respect to said frame comprising, positioning means on saidl frame, positioning means on said framework, and an auxiliary cam movable in timed relation with movement of said supports about their axes and coacting with said positioning means to position said framework, means for yieldingly urging said framework toward the positioning means' on said frame and urging both said positioning means and said cam into coacting relation while the work piece is positioned on the belt.

15. In a belt grinder for shaping an elongated turbine blade or the like in which an abrasive belt is led between a blade supported on a blade support and a substantially unyielding rigid belt Shaping form. a pair of pivots having substantial-v ly axes extendingtransversely of said belt and substantially parallel to the4 face of said. belt,` a blade support, a form, support,` one of said supportsmounted, to move about one of said pivots, the, other support mounted to move about the other, pivot in timed, relation to the movement of said one support, a frame supporting and locatingsaid one. pivot,- a movable framework supporting; and locating said other pivot and mounted on` saidV frame for movement transversely of said pivot axes and toward and from said one support, means for moving, said supports about their respective pivots in timed relation to repeatedly present said blade to saidy belt and force said belt into. contactv with said blade and to separate said belt. and. blade between contact. periods, means for spacing said supports with respect to each other for grinding the work piece to a predetermined size by positioning said framework with respect to said frame, comprising positioning means on said frame, positioning means on said framework, and an auxiliary cam movable in timed relation with movement of said supports about their axes and coasting with said positioning means to position said framework, means for yieldingly urging said framework toward the positioning means on said frame and urging said cam and both said positioning means into coacting relation while the workpiece is positioned for grinding.

16. In a belt grinder as claimed in claim 15 means for adjusting one of said positioning means in timed relation with the movement of said supports to gradually feed said form toward said blade.

17. In a belt grinder for shaping an elongated turbine blade or thelike in which an abrasive belt is led between a blade supported on a blade support and a substantially unyielding rigid belt shaping form, a pair of pivots having substantially parallel axes extending transversely of said.

belt and substantially parallel to the face of said belt, a blade support, a form support, one of said supports mounted to move about one of said pivots, the other support mounted to move about the other pivot in timed relation to the movement of said one support, a frame supporting and locating said one pivot, a movable framework supporting and locating said other pivot and mounted on said frame for movement transversely of said pivot axes and toward and from said one support, means for oscillating said supports about their' respective pivots in timed relation to repeatedly present said blade to said belt and force said belt into contact with said blade between said blade and form and to separate said belt and blade between contact periods, means for spacing said supports with respect to each other for grinding the blades to a predetermined size by positioning said framework with respect to said frame, comprising positioning means on said frame, positioning means on said framework, and an auxiliary cam reciprocable in timed relation with movement of said supports about their axes and coacting with said positioning means to position said framework, means for yieldingly urging said framework toward the positioning means on said frame and urging said positioning means and said cam into coasting relation, means for adjusting one of said positioning means in timed relation with oscillation of said Y supports to gradually feed one of said supports toward the other support, and means for limiting the extent of said feeding adjustment to limit the blade size.

y 18. In means for forming an 'elongated metal turbine blade or the like, a frame, a blade support mounted on saidv frame for oscillation about an axis extending lengthwise of said blade, a movable framework mounted on said frame for movement toward and from said blade support, a substantially unyiel'ding rigid' metal form mounted on said movable framework to oscillate about an axis parallel to said bladesupport axis, means for passing an abrasive belt transversely across said blade and between said blade and form, means for oscillating said support/and form in timed relation. about` their .respective axes to repeatedly force said belt into contact with said blade between said blade and form and alternately space said belt from said blade, an auxiliary cam, means for reciprocating said cam in timed relation with the oscillation of said support and form, a movable abutment carried by said frame, means urging said framework toward said abutment, means on said framework coating with said cam and urging said cam into contact with said abutment to position said framework with respect to said blade support, and means actuated in timed relation with said oscillations to adjust said abutment in steps while said belt is spaced from said blade to gradually feed said form toward said blade.

19. In a machine for nishing irregularly shaped articles, in combination, a travelling belt having an abrasive surface, a work support, a contact roll for positioning the abrasive surface of said belt relative to a piece of work on said support, said roll having a peripheral depression therein constituting a developed impression of a surface of a finished work piece, means for effecting relative reciprocatory movements between said roll and said work piece, said means comprising positioning means having a predetermined location with respect to said work support and positioning means having a predetermined location with respect to said roll axis, atleast one of said positioning means being movable and connected withits respective work support or roll to effect reciprocation thereof, a cam coacting with both said positioning means to relatively'position said work support and roll while said belt is in contact with said work, and means to actuate said cam to reciprocate said movable positioning means and effect said relative reciprocatory movement while said belt is in contact with said work, and means for oscillating said roll -about its axis in timed relation with said reciprocatory movements.

20. In a machine for nishing irregularly shaped articles, in combination, a travelling belt having an abrasive surface, a work support, a contact roll for positioning the abrasive surface of said belt relative to a piece of work on said support, said roll having a peripheral depression therein constituting a developed impression of a surface of a finished work piece, means for effecting relative reciprocatory movements between said roll and said work piece, said means comprising positioning means having a predetermined location with respect to said work support and positioning means having a predetermined location with respect to said roll axis, at least one of said positioning means being movable and con- "nected with its respective work support or roll to eifect reciprocation thereof, a cam coacting with both said positioning means to relatively position said work support and roll while said belt is in contact with said work, and means to actuate said cam to reciprocate said movable positioning means and effect said relative reeiprocatoiy movement While said belt is in contact with Ysaid work, means for oscillating said roll about its axis in timed relation with said reciprocatory move ments, and means for eiecting relative adjust- 5 ment of said roll and work support toward each other by adjusting one of said positioning means with respect to its respective Work support or roll in timed relation with the oscillation of said roll, and means for limiting the extent of said timed 10 relative adjustment.

SIGMUND A. CZARNECKI.

REFERENCES CITED The following references are of record in the 15 file of this patent:

Number Number 16 g UNITED STATES PATENTS- Name Date Ensign July 30, 1901 Herrmann Mar. 3, 1908 Blevney et al Dec. 27, 1910 Loeilier June 26, 1928 Bates et al Dec. 18, 1934 Johnson Dec. 15, 1936 Herdick Feb. 24, 1942 Clausing Feb. 23, 1943 Clausing July 4, 1944 FOREIGN PATENTS Country Date Great Britain Mar. 22, 1939 Germany Oct. 13, 1939