US2699019A - Contour polishing machine - Google Patents

Description

E. DACKOR ET AL CONTOUR POLISI-IING MACHINE Jan. 11, 1955 4 Sheets-Sheet l Filed March l2, 1-951 ,f /m im Zw if; H yum hi a M/ www a, i w

Jan. 11, 1955 E. DAcKoR ET AL Y 2,699,019

coNToUR PoLIsHING MACHINE Filed March 12, 1951 l v l Elf/57.5.

4 Sheets-Sheet 2 Jan. 11, 1955 E. DAcKoR ET AL 2,699,019

y coNToUR POLISHING MACHINE A Filed March l2, 1951 4 Sheets-Sheet 3 Jan. 11,` 1955 E. DAcKoR ET AL 2,699,019

coNToUR POLISHING MACHINE Filed March 12, 1951 4 sheets-sheetA United States Patent O CONTOUR POLISHING MACHINE Emil Dackor and Edgar F. Nelboeck, Cleveland, Ohio, assignors to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application March 12, 1951, Serial No. 215,104

8 Claims. (Cl. 51-135) This invention relates to a machine for polishing or abrading work pieces to produce thereon the exact desired contour as determined by a platen or former block. Particularly the invention deals with an abrasive belt type polishing machine especially useful for accurately forming the complicated faces of blades and buckets for gas turbine-engines and the like.

According to this invention, an endless abrasive belt is guided across a` former block or platen having a contour desired for the work piece to be acted on by the belt. Tracking rollers are disposed on opposite sides of the former block in close proximity thereto and are so positioned as to direct the belt tangentially onto and oif of the former block. The belt is pulled across the surface of the former block by a pair of squeeze rollers and is fed back to the former block in a taut controlled tensioned condition. The work piece is mounted on a carrier which is preferably cam actuated to feed the work piece at a desired rate to the abrasive surface of the belt as it passes over the former block. Other feed mechanisms such as viiuid actuated piston means could be used if desired. In order to protect the Work piece against distortion caused by heating during the polishing or abrading operation, a coolant distributing attachment is provided on the Work piece carriage for absorbing heat from the work piece to maintain it at a desired temperature.

While the invention will be hereinafter specifically described as embodied in a polishing or abrading machine for the vanes of turbine engine blades and buckets, it should be understood that the machine is useful for accurately producing any desired contour on a work piece. The invention is, therefore, not limited tothe preferred hereinafter described embodiment.

A feature of the invention resides in the tangential feeding of the belt onto and off of the former block.

Another feature of the invention resides in the feeding of the abrasive belt to the former block in a taut condition of controlled tension.

Another feature of the invention resides in the provision of a cooling attachment on the Work carriage for preventing the work piece from becoming warped even though subjected to appreciable heat liberating friction during the abrading or polishing operation.

It is, then, an object of the invention to provide a machine for rapidly imparting a desired accurate contour to a complicated surface of a work piece such as the vane section of a turbine engine blade or bucket.

A further object of the invention is to provide an endless belt type abrading machine with a formerblock for successively controlling the contour of a portion of the belt to cause the belt to present an abrading surface of desired contour to a work piece.

Another object of the invention is to provide an endless belt type abrading machine with a former block and adjustable rollers on each side of the block for causing the belt to accurately track over the former block and assume the exact shape of the surface of the block.

A still further object of the invention is to provide adjustable tracking pulleys on opposite sides of a former block of a contour polishing machine.

A still further object of the invention is to provide a contour polishing machine with a feed device for progressively advancing a work piece to a polishing belt.

Another object ofthe invention is to-p'rovide a polishai workcarriagethat isJ cooled bx'. meansJ j 6991119 Patented Jan. 11, 1955 ,lCC

of a coolant applied to the surface of the work piece opposite that surface which is being acted on by the machine.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed desciption of the annexed sheets of drawings which, by way of a specific preferred example only, illustrate one embodiment of the invention.

On the drawings:

Figure 1 is a front elevational view of a contour polishing machine according to this invention.

Figure 2 is an enlarged fragmentary front elevational view of the machine of Figure 1.

Figure 3 is an end elevational view of the machine of Figures 1 and 2 taken along the line III-III of Figure l.

Figure 4 is an enlarged vertical cross-sectional view, with parts in end elevation, taken along the line IV-IV of Figure 2.

Figure 5 is a fragmentary bottom plan View, with parts omitted, taken along the line V-V of Figure 1.

Figure 6 is a diagrammatic View of a modified contour polishing machine according to this invention.

As shown on the drawings:

The machine 10 of Figure 1 includes a framework with legs 11 supporting a table 12 and a vertical rear wall 13 carrying an overhanging shelf 14 in spaced relation above the table 12.

Links 15 and 16 are respectively pivoted on opposite ends of the table 12 and rotatably carry rollers or pulleys 17 and 18 respectively. Springs 19 and 20 respectively pull the rollers 17 and 1S outwardly to increase the distance therebetween.

As shown in Figures l and 5, an electric motor 21 is suspended under the table 12 and drives a cam 22. A lever 23 is pivotally mounted on a bolt 24 under the table 12 and has a pin 25 depending therefrom in the path of the cam 22. A spring 26 having one end anchored on a pin 27 depending from the table 12 and the other end anchored on a pin 28 depending from the lever 23 pulls the lever so that the pin 25 rides against the periphery of the cam 22.

The lever 23 projects beyond the end of the table and has an upwardly inclined portion 23a terminating in a forked horizontal end 23h.

An endless abrasive belt 29 is trained around the under sides of the pulleys 17 and 18 and through the forked end 23b of the lever. As shown in Figure 5, this belt yruns between the forked arms and when the motor is driven to rotate the cam 22, the lever 23 will shift between the dotted and solid line positions to shift the belt laterally for a purpose to be more fully hereinafter described.

As best shown in Figure 2, the table 12 has a series of upright transverse plates 31) to 35 inclusive bolted in spaced parallel relation thereon by means of bolts 36. A first cradle support 37 is mounted on vthe table 12 between the plates 30 and 31. A second cradle support 38 is mounted on the table 12 between the plates 32 and 33. rlhese cradle supports 37 and 33 are anchored between the adjacent plates by bolts 39. Each cradle support 37 and 38, such as the support 37 shown in Figure 3, has a fragmental circular recess 40 in its upper end. A cradle 41 is rockably mounted in each recess. The cradle 41 has a rocker bottom 41a fitting between the adjacent plates and locked in adjusted position by set screws 42 threaded through one or both of the adjacent plates such as the plate 30 shown in Figure 3.

Each cradle 41 also has a pair of spaced opposed upright arms 41b forming journals for the axles 43 of a roller or guide pulley.

The rocker 41 between the plates 30 and 31 thus journals an oncoming belt guide pulley 44 while the cradle 41 between the plates 32 and 33 journals an ogoing belt guide pulley 45. These pulleys are respectively positioned and tilted on their rocker supports 49 for correctly guiding the abrasive belt 29 onto and off of a former block or platen 46 mounted between the plates 31 and 32 and secured on the table 12 by means of bolts such as 36.

The former block 46 has a contoured top face orv end 46a projecting above the plates 31 and 32 between the pulleys 44 and 45. The illustrated top face 46a of the former block is generally convex and somewhat twisted along its length to constitute a shaping die for producing the concave and twisted face of a work piece. It will be noted that this face 46a is at a level above the bottoms of the pulleys 44 and 45 and that the belt 29 passes under the pulleys and over the top face 46a with the abrasive face 29a of the belt remote from the face 46a but contacting the faces of the pulleys 44 and 45.

A wringer roll frame 47 is secured on the table 12 between the plates 34 and 35 by means of bolts such as 48 and extends above the plates to journal a lower roll 49 on a fixed axis 50 and to slidably mount journal boxes 51 in vertical grooves such as 47a thereof. The journal boxes 51 rotatably support the axles 52 of an upper roll 53. Compression springs such as 54 act on the journal boxes 51 to urge the roll 53 against the roll 49. Hand screws threaded through the top of the frame, such as the screw 55, control the compression of each spring 54.

As shown in Figure l, an electric motor 56 secured on the table 12 is connected through a sprocket and chain drive 57 with the axle 50 of the lower roll 49 to the drive this roll in a counterclockwise direction. The belt 29 passes between the rolls 49 and 53 and is squeezed into tight engagement with the roll 49 so that rotation of this roll will drive the belt in a counterclockwise direction as indicated by the arrows.

After passage between the rolls 49 and 53, the belt passes over a guide pulley 58 journaled in arms 59 carried by the end block 35. The belt then passes under the pulley 17, across the intervening space between the pulleys 17 and 18, and thence upwardly from the pulley 18 through the forked end 23h of the lever 23 to a tensioning roller or pulley 60 rotatably mounted on the end of a link 61 which is pivoted at 62 to the upper end of the plate 30. After passage around the pulley 60, the belt advances under the guide pulley 44.

A bracket 63 also carried by the end plate 30 projects horizontally under a rod 64 swingably mounted on the end of the link 61. The rod 64 extends through an aperture in the end of the bracket 63 and a compression spring 65 surrounding the rod between the bracket 63 and the link 61 Supports the link above the bracket. A nut 66 on the rod 64 under the bracket 63 serves to draw the rod through the bracket for controlling the compression of the spring 65 and therefore the height of the pulley 60. This springy adjustment controls the tension of the run of the belt 29 being fed to the roller 44. since raising of the roller 60 will place more slack in the belt loop while lowering the roller will increase the dimension of the belt loop to tighten the belt. The adjustment takes place on the feed-in side of the belt loot) and is controlled so that, while the belt is taut as it is fed to the roller 44, it is not under appreciable tension and can therefore be accurately tracked over the former block surface 46a to exactly follow all of the contours of this surface without. however, becoming kinked or buckled.

In order that the belt will not feed the same abrasive granules to the same spot on the work piece, the lever 23 is oscillated by the cam 22 so that the forked end 2317 thereof will laterally shift the belt as it travels and causes the same to move laterally in the guide pullevs 6l), 44, and 45 to present different grit particles to different areas of the work piece. This arrangement eliminates heretofore encountered grooving due to snagging of abraded metal by certain abrasive grits and continuing a feed the snagged metal along the same path over the work piece.

The shelf 14 projecting over the table 12 slidably carries four vertical rod-like posts 67 having a work carriage 68 mounted on the lower end thereof. The upper ends of the rods 67 project through the shelf 14 and receive compression springs 69 therearound. Retainers 70 on the top ends of the rods 67 hold the springs 69 under compression, thereby causing the springs to raise the carriage 68 toward the shelf 14.

A central rod 71 on the carriage 68 and between the posts 67 also extends upwardly through the shelf 14 and carries a cam roller 72 on the upper end thereof.

Bearing brackets 73 on top of the shelf 14 journal a shaft 74 on which is secured a cam 75 acting on the roller 72. This shaft is rotated as desired by a sprocket and chain drive 76 which can be hand operated or connected to a timing motor (not shown). The cam 75 is shaped so as to feed the carriage 68 downwardly at a desired rate for an abrading operation.

As best shown in Figure 4, the carriage 68 includes a metal block 77 having the lower front portion cut away at 78 and also having a recess 79 in the bottom face thereof adjacent the cut out portion 78. Side plates 80 span the sides of the block 77 to form side walls for the cut out portion 78. Removable transverse plates 81 are positioned between the side plates 80 in the cut out portion 78 and coact to form end walls for an open bottomed chamber 82. The end plates 81 have concave beveled bottom ends 81a contoured to embrace the vane portion V of a turbine bucket work piece W having a root and R seated in the recess 79. These end plates 81 can be changed to provide plates with lower ends 81a shaped in accordance with the contour of the work piece.

A second block 83 is secured under the lower rear corner of the block 77 as by screws 84. This block has an inclined leg 83a through which a locking screw 85 is threaded. This locking screw 85 engages the under face of the root end R of the work piece W to secure the work piece to the under face of the block 77 so that its vane V spans the open bottom of the chamber 82.

A channel 86 is cut into the upper portion of the block 77 and is connected with the chamber 82 through jet like passages 87. A plug 88 is in the end face of the block 77 receives a nipple 89 of a hose 9i) to supply coolant to the channel 86. This coolant is dispersed through the jets 87 to the chamber 82 for cooling the vane V of the work piece W.

A suitable coolant is liquefied carbon dioxide, which is preferably allowed to gasify at the vane V for absorbing heat created by action of the abrasive belt on the surface of the vane directly opposite the surface contacted by the coolant. The coolant can be dissipated through spaces between the side edges of the vane and the side plates 80.. Distortion of the vane or any part of the work piece due to heating is effectively prevented by a coolant such as carbon dioxide.

The modified machine 10a of Figure 6 includes many parts identical with or corresponding to parts of the machine 10 of Figure l, and these parts have, therefore, been marked with the same reference numerals. in the machine 10a, however, the work carriage 68 on the posts 67 is raised and lowered by a uid pressure operated jack having the piston thereof actuating the rod 71 on the carriage. This jack can be hydraulically or pneumatically operated at pressures controlled to urge the workpiece W against the belt 29 on the former block 46 with a desired force.

The guide pulleys 44 and 45 on cach side of the former block 46 are journaled on forked arms 101 and 102 respectively, and each arm has a ball stud 103 on the end thereof mounted in a socket 104. The ball and socket mountings for the forks permit the pulleys 44 and 45 to swivel in all planes for tracking the belt 29 over the former surface 46a.

The forked lever 23 of the machine 10 is replaced on the machine 10a by a concave V-type centering pulley 105 which centers the belt feed to the pulley 44.

Operation The contour polishing or abrading machine 10 is placed in operation by moving the cam 75 so that its low spot engages the cam follower roller 72, whereupon the springs 69 will raise the carriage 68 toward the shelf 14 and away from the abrasive belt 29. A turbine bucket or blade work piece W is then mounted in position on the under face of the block 77 as illustrated in Figure 4 with the vane portion of the blade or bucket spanning the open bottom of the chamber 82. The set screw 85 is tightened against the root R to lock the work piece in position on the lock.

The motor 56 is energized to drive the wringer rollers 49 and 53 for driving the belt 29 in a counterclockwise direction. The tension of the spring 65 for the roller 6i) is adjusted so that the belt will merely have a taut run over the former block surface 46a but will not be loose enough to flap or buckle. The guide pulleys 44 and 45 have their supporting cradles 41 adjusted so that the belt is directed tangentially onto and off of the surface 46a.

The motor21 is energized to oscillate the vforked end 23bof the lever, thereuponshifting'the belt'laterally'andcausing the top run of the belt to oscillate as it tracks under the rollers 44 and 45 and over the surface 46a. The spring tension on the rollers 17 and 18 is adjusted so that the belt will be held taut along its return path to the upper run.

The feed drive 76 is placed in operation to rotate the cam 75 a desired rate for lowering the carriage 68 to move the work piece down on top of that portion of the belt passing over the former surface 46a. The speed of advancement of the cam is such that the Work piece will be progressively advanced against the belt as the abrading and polishing operation continues. The shape of the cam is such that the amount of advancement is carefully regulated.

Carbon dioxide from a suitable source is fed through the tube 90 during the abrading operation at a rate to keep the work piece W sufficiently cool so that distortion will not take place.

Since the belt is only pulled across the former surface and is fed to the former surface substantially free from tension, high speed operation is accomplished without damage to the belt.

The platen or former block surface 46a is preferably made of very hard wear resisting material such as a die alloy. This surface is accurately formed and will reproduce a mating surface on the work piece.

The guide pulleys are preferably wider than the abrasive belt to accommodate lateral shifting of the belt by the oscillating lever 23. The pulleys preferably have flanged ends to prevent overshifting of the belt.

As shown in Figures 1 and 2, the guide pulleys or rollers 44 and 45 are inclined in opposite directions due to the twist along the length of the former surface 46a. These positions of the rollers or pulleys maintain the belt in full conformity with the complicated contour of the surface 46a without permitting the belt to kink or buckle.

The machine a operates in substantially the same manner as described above in connection with the machine 10. However, the jack 100 is controlled by a lluid, and lifting springs for the carriage 68 are not necessary.

From the above descriptions it will therefore be understood that this invention provides an endless abrasive belt type polishing or abrading machine wherein a former block or platen backs up the belt and a work piece to cause the belt to produce a contour on the work piece exactly mating with the contour of the former or platen surface.

It will be understood that modifications and variations may be effected Without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. An abrading machine comprising a frame having a table and a support overlying the table, a former block on said table having a top end contoured to produce a desired mating contour on a work piece, guide pulleys on said table on opposite sides of said former block, rockable cradles rotatably journaling said guide pulleys, means on said table supporting said cradles in adjusted position to carry the guide pulleys at the desired angles of inclination, a pair of squeeze rolls carried by said frame and defining a pressure nip therebetween, an endless abrasive belt having an upper run over the top of said former block under said guide pulleys and through said nip, additional guide pulleys supporting said belt in an open loop beneath the upper run thereof, an adjustable guide pulley in said loop controlling the tension of the upper run of the belt, means for laterally oscillating said belt, means for driving one of said squeeze rollers to advance the belt, a work carriage slidably suspended on said support over the table, a cam on said support for advancing said carriage toward said former block, means for xedly mounting a Work piece on the under face of said carriage for positioning over said former block, means for circulating coolant through said carriage over a work piece carried thereby, and means for rotating said cam to feed a work piece on said carriage to the abrasive belt area passing over the former block.

2. A machine for forming a surface on a work piece which comprises a former element having a rigid shaping surface, a carriage having means for securing a work piece thereto, guide means for advancing said carriage toward and away from said rigid surface of the former element, and endless abrasive belt, rotatable guide pulleys on opposite sides of said former element positioned to tangentially direct the abrasive belt onto and olf of the rlgid surface of said former element, squeeze rolls for pulllng the abrasive belt across said rigid surface of the former element, and adjustable means for feeding the belt in a taut controlled tension condition to said rigid surface of the former element.

3. In an abrading machine of the looped belt type including a platen receiving the belt thereover and guide pulleys holding the belt in an open loop, the improvements which comprise a pair of squeeze rollers receiving the belt through the nip thereof to pull the belt across the platen and an adjustable roller in the loop of said belt controlling the tension of the run of the belt to the platen for feeding the belt to the platen in a taut controlled tension state.

4. In a contour polishing machine of the looped abrasive belt type which comprises a former element in the loop of the belt having a rigid die surface contoured to produce a desired complementary surface in a work piece, guide pulleys on opposite sides of the former element, means tiltably mounting said guide pulleys for controlling the angles of inclination thereof to cause the pulleys to feed the abrasive belt tangentially onto and off of said rigid former element, and press rollers receiving the abrasive belt in the nip therebetween and positioned for pulling the belt across the former element.

5. A machine for polishing the vanes of turbine buckets and the like which comprises a blade holder having a hollow chamber spanned by the vane of the blade, means for feeding a coolant through said chamber to cool the vanes, a rigid former block having a top surface contoured to produce a mating surface on the vane of a blade carried by said holder, means for shifting said holder toward and away from said top surface of the former block, guide pulleys for guiding an endless abrasive belt across the top surface of said former block, and means for tilting pulleys adjacent opposite sides of the former block to track the guide belt over the surface.

6. A contour polishing machine comprising a former block, an'endless abrasive belt having a smooth face trained over said block and an opposed abrasive face, a Work carriage slidably mounted adjacent said block, a fluid pressure operated jack for shifting said carriage to press a work piece against the abrasive face of the belt on the former block, pulleys guiding the belt on opposite sides of the former block, means swivelly mounting said pulleys, and means for driving said belt.

7. In a machine for forming a surface on a work piece including a rigid former surface and an abrasive belt trained over said surface, guide pulleys on opposite sides of the former surface for guiding the belt thereacross, and adjustable mountings for said guide pulleys for tiltting each of said guide pulleys relative to the former surface about an axis transverse to the axis thereof for directing the belt tangentially onto and olf of the former surface.

8. In an abrading machine of the looped belt type including a platen receiving the belt thereacross, guide pulleys holding the belt in an open loop and means for driving the belt, a member having facing guide surfaces engageable with opposite side edges of the belt, and means for oscillating said member laterally of the belt in a direction substantially parallel with the plane of the belt to reciprocably shift the belt sidewise as the belt is driven.

References Cited in the tile of this patent UNITED STATES PATENTS 933,305 Jackoboice et al. Sept. 7, 1909 1,490,555 Brochets Apr. l5, 1924 1,635,399 Fischer July 12, 1927 1,675,183 Loelfler June 26, 1928 1,735,903 Johnson Nov. 19, 1929 1,866,848 Freeman et al. July 12, 1932 2,109,069 Lippold Feb. 22, 1938 2,139,952 Giles Dec. 13, 1938 2,453,972 Clare et al. Nov. 16, 1948 2,479,506 Payton Aug. 16, 1949

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