US2875558A - Doctor blade grinder - Google Patents

Description

March 1959 Q A. T. WILLIAMS ET AL 2,875,558

DOCTOR BLADE GRINDER 4' Sheets-Sheet 1 Filed July 28. 1958 INVENTORS ES R. TIDLAND ARTHUR T, WILLIAMS ATTORNEY- March 3, 1959 A. T. WILLIAMS ETAL 2,875,558

DOCTOR BLADE GRINDER Filed July 28, 1958 v 4 Sheets-Sheet 2 INVENTORS "7 Q CHARLES R. TIDLAND ARTHUR T. WILLIAMS ATTORNEY March 3, 1959 A. "r. WILLIAMS ET AL DOCTOR BLADE GRINDER Filed July 28, 1958 4 Sheets-Sheet 3 52 ise INVENTORS CHARLES R. TIDLAND BY ARTHUR T, WILLIAMS ATTORNEY March 3, 1959 A. T. WILLIAMS ET AL DOCTOR BLADE GRINDER Filed July 28, 1958 4 Sheets-Sheet 4 CHARLES R. TIDLAND ARTHUR T. WILLIAMS ATTOR NE DOCTOR BLADE GRINDER Arthur Thomas Williams, Washougal, and Charles Robert Tidland, Camas, Wash, assignors to Tidland Machine Company, *Camas, Wash., a corporation of Washington Application July 2a, 1958, Serial N 751,380

9 Claims. c1. 51-131 This invention relates to an improved grinding machine which has been developed specifically for the grinding ofso-called doctor blades employed chiefly, although not exclusively, in the manufacture of various types of paper.

The customary doctor blade consists of a thin band of steel, usually from to A of an inch in thickness, having a straight edge which bears against the surface of apaper web, for example, which may be employed for smoothing the surface coating, insuring even distribution ofthe coating, and removing any surplus coating.

,lt is essential thatthe edge of the doctor blade which bears against the paper web, or roll, or other element on which the blade is employed, should be absolutely straight. Otherwise theblade cannot perform its function properly. Consequently the working edges of such blades mustbe ground frequently to keep them absolutely straight. However, when doctor blades are long, as in the case of doctor blades used on paper having a width of from 6 to feet, the grinding of the working edge of the blade of such length has presented such a difficult problem that in many instances it has been considered cheaper to purchase a new blade instead of attempting to;.reproducej aperfectly straight edge on a worn doctor blade by, grinding. c r M An ,object of the present invention is .to provide a novel and improved grinding machine with which a perfectly straight edge can be satisfactorily ground on a doctor blade regardless of the length of the blade.

, A related object of the invention is to provide a grinding machine in which the extent to which the working edge of a doctor blade is ground away will be automaticallyrestricted to a predetermined limit, so as to avoid excessive or unnecessary grinding down of the blade.

4 Another object of the invention is to provide a grinder for doctor blades and the like in which the ground straight edge, or longitudinal edge, will also be ground straight in cross section instead of being round in cross section, since a rounded Working edge is less effective on, suchblades and edges become rounded with wear.

,tAfurther object of the invention is to provide a grind- .i ng machine, with efficient clamping means, adapted particularly for doctor blades, by which any doctor blade, regardless of its length, canbe quickly set in place in the machine and; beretained. clamped in proper positiqn during the entire grinding operation. n additional object of the invention is to provide a gr nding machine; especially suited for doctor blades, which will be largelyautomatic in its operation and which; will jenable the desired grinding to, be accom- .p li shed;;quicklyl and efliciently and without requiring any particularly-skill or care on the part of the operator .in harge of the grinding: g ilhe manner in which these objects and other advantages are attained with the grinding machine of the present invention, and the construction and method of operation of the machine, will be described and explained Patented Mar. 3, 1959 -2 briefly with reference to the accompanying drawings, in which: I a 1 Fig. 1 is a sectional elevation of the entire device taken on the line indicated at 1--1 in Fig. 2; Fig. 2 is a plan view with top housing portions omitted and other parts broken away for clarity;

Fig. 3 is a fragmentary sectional elevation on line 3--3 of Fig. 2, drawn to a larger scale; t Fig. 4 is a fragmentary sectional elevation 4.-,-4 of Fig. 3;-

. Fig. 5 is a fragmentary section 3 and 4, drawn to a larger scale; t Fig. 6 is a section on line 6-6 of Fig. 3; and l Fig. 7 is aschematic perspective view illustrating the operation of the automatic control means for limiting the travel of the grinding element towards the work.

Referring first to Figs. ,1 and 2, 10 designates a 1013.11.- able circular table for supporting the doctor blade during the grinding operation, this table having an outer cit-.- cular wall 11. The table is keyed on'a vertical shaft 12 which is rotatably mounted and supported on a housing base indicated in general at 1 3 in Fig. 1. A pulley .14 is secured on the bottom end of the shaft 12 and has a belt connection with a motor 15 (Fig. 2) by which the supporting table is rotated. A stationary shield 16 extends around the table 10,being spaced at short distance therefrom and has .a bottom wall equipped with a. suitable drain (not shown). i a

A plurality of identical, equally spaced, radially-adjustable, blade-clamping assemblies 17 (Fig. 2) are mounted on the .table 10. Each of these clamping assemblies consists of abottomplate 18 which carries an online 55 of end wall 19 constituting an arc of;a circle ofthe same radius asthe outer circular wall 11. The bottom plates 18 are formed with central, radially-extendingslots 20 through which pairs of stationary guide bolts 21 ex: tend, thus enabling the bottom plates with their end walls to be moved in and out in a radial direction to a limited extent. Pairs of side brackets 22, carried by the bottom plates, act as supports for the end walls in the clamping assemblies. .An additional center bracket 23 in eachclamping assembly is secured to theibottom plate and to the end wall. Tie rods 24 have their outer ends pivotally connected with the center brackets 23 and their inner ends are pivotally connected with radial lugs carried on a sleeve 25 which is slidably mounted on the vertical shaft 12. A key (not shown) carried by the sleeve 25, engages a longitudinalslot in the shaft 12 so thatthe sleeve is prevented from rotating with respect-to the shaft 12 while being movable up and down on the shaft. The upper end .of the shaft 12 is threaded and carries an internally threaded collar 26. This collar has a peripheral, downwardly-extending" flange which extends down over the upper portion of the sleeve 25. "A pair of screws 27 on this flange engagean annular groove 28 in the sleeve 25. A pair of radially-extending handles 29 are mounted on the collar 26; Thus it will be apparent from Fig. 1 that rotary adjustment of the collar 26. on the shaftLlZ, by causing the sleeveto be moved up or down on the shaft' 12, will result in the clamping assemblies 17 being moved in or outon the 'table 10; p

The doctor bladeisindicated at 30 in Figs. 1 and 2. In many instances the lengthof the doctor-blade may be several times the circumference of the table 10 and in such cases the blade is coiled within the peripheral wall 11 and the blade-clamping assemblies 17 are then moved outwardly by manipulation of the threaded collar 26 until the doctor blade is held clamped between 'the curved end walls 19 of the clampingassemblies and tlie peripheralcwallllof the rotatingtable 10.- L

A grinding element 31 (Fig. 1) is secured on the bottom of a shaft 32 which is rotatably carried in a bearon. line 33 supported in a bracket 34 attached to a grinder head 35. The grinder head 35 is mounted for vertical movement on a-stationary cylindrical support 36. A motor 37 is carried on the grinder head 35 and has a pulley and belt connection with the pulley 38 secured on the top of the grinder shaft 32.

An upper feed screw 39 (Fig. 1), having a bearing collar 40 engaging the top of the stationary cylindrical sup port 36, extends through a feed screw nut 41 secured to the grinder head 35. An adjusting hand wheel 42 is secured on the top of the upper feed screw 39. A key 43 in the grinder head engages a vertical slot or keyway 44 in the cylindrical support 36 so as normally to hold the grinder head 35 against rotating on the cylindrical support 36, while permitting the grinder head to be raised orlowered upon the turning of the upper feed screw 39.

A lower feed shaft 45, in vertical axial alignment with the upper feed screw 39, is rotatably mounted in suitable bearings in the housing base 13. A lower clutch member 46-is rigidly secured at the top of the lower feed shaft 45. A feed control disc 47 rests on this lower clutch member 46, being held in place by a downwardlyextending center lug which is received in a center recess within the clutch member 46. An upper clutch member 48 is axially slidable on the lower end of the upper feed screw 39, but is prevented from rotating with respect to the upper feed screw 39 by a suitable key (not shown). A coil spring 49 on the upper feed screw 39, held under compression between a fixed collar 50 and the upper clutch member 48, acts to hold the upper clutch member 48 normally in engagement with the feed control disc 47 and holds the feed control disc 47 firmly in engagement with the lower clutch member 46. The abutting surfaces of the disc 47 and of the two clutch members are knurled or grooved so as to cause the upper feed screw 39 normally to rotate in unison with the lower feed shaft 45 when the latter is rotated.

The upper clutch member 48 carries a collar 51 which is rotatable with respect to the clutch member 48. A pair of diametrically opposite, radially-extending pins 52 are secured in the collar 51 and these pins pivotally support a pair of upper links 53 respectively which in turn are connected with lower links 54 and provide a pair of oppositely positioned toggle assemblies (see also Figs. 3 and 4). The bottom ends of the lower links 54 are pivotally supported on a pair of stationary brackets 55. A U-sha'ped tie bar 56, which is supported by suitable means (not shown) so as to be slidable in a horizontal plane, carries at its ends the pivotal connecting pins by which the respective links 53 and 54 are connected to each other. A control rod 57 (Figs. 2, 4, and 6) is connected to the tie bar 56 and carries a finger knob 58 at its outer end. It will be apparent from Figs. 1 and 4 that pushing the rod 57 to the right, as viewed in Fig. 4, will operate the toggle assemblies formed by the links 53 and 54 in such manner as to raise the upper clutch member 48 against the force of spring 49. The purpose of temporarily raising upper clutch. member 48 is to enable feed control disc 47 to be adjusted, as later explained. The contact of the finger knob 58 with the wall 59 (Fig. 4) of the housing limits the extent to which the toggle assemblies can be moved in the raising of the upper clutch member.

. An eccentric 60 (Fig. 1) secured on the vertical shaft 12, is rotatable in a ring to which one end of a connecting rod 62 is secured. A ratchet wheel 63 (Figs. 2, 3, 4 and 5) is secured on a vertical, rotatably-mounted shaft 64. A pawl-carrying bracket 65 is rotatably mounted on the same shaft 64 at a spaced distance below the ratchet wheel 63, and this bracket 65 carries a pivotally mounted pawl 66 which, as shown best in Figs. 2 and 5, is capable of engaging the teeth on the periphery of the ratchet wheel 63 when the bracket 65 and pawl 66 move in clockwise direction (as viewed in Figs. 2 and 5) and thus produce intermittent clockwise rotation of the ratchet wheel 63. spring (not sh ?!)v in the pawlcarrying bracket 65 normally holds the engaging end of the pawl 66 against the periphery of the ratchet wheel.

A rod-supporting member 67 is pivotally attached to the underside of the bracket 65 (Figs. 3 and 4) and the outer end of the connecting rod 62 is secured to this member 67. From this arrangement it will now be apparent that rotation of the shaft 12 and table 10 (Fig. l), producing rotation of the eccentric 60 and reciprocal movement of the connecting rod 62, and consequently producing oscillation of the pawl-carrying bracket 65, will produce intermittent rotation of the ratchet Wheel 63 as long as the pawl is able to engage the ratchet wheel.

A spur gear 68 (Figs. 3 and 4) is secured on the ratchet wheel shaft 64 and is engaged with a gear 69 on a shaft 70. A spur gear 71 on shaft 70 engages a gear 72 (see also Fig. 1) which is secured on the lower feed shaft 45. Thus rotation of the ratchet wheel 63, through this gear reduction chain, produces rotation of the lower feed shaft 45 and, when the clutch connection between the upper feed screw shaft 39 (Fig. l) and the lower feed shaft 45 is in normal or lowered position, this rotation of the lower shaft 45 causes rotation of the upper feed screw shaft 39 and results in a gradual downward movement of the grinder head 35 and therewith gradual downward movement of the rotating grinding element 31.

When the doctor blade 30 (Fig. 1) has been clamped in position on the table '10 the upper clutch member 48 is temporarily raised, as previously described, and the upper feed screw 39 is turned by the hand wheel 42 until the grinding element 31 is brought down into close pr0ximity to the top edge of the doctor blade to be ground. Then, when the upper clutch member 48 is lowered to normal engaging position and the switches for the motor 37 for the grinder and for the motor 15 (Fig. 2) for the rotating table 16 are turned on, the rapidly rotating grinding element 31, will grind the top working edge 'of the doctor blade while the table 10 rotates. However, since it is necessary to have the top edge of the doctor blade ground to a straight edge, obviously the gradual downward movement of the rotating grinding element 31 must be limited so that the final grinding will be done while the grinding element remains at a fixed distance above the table 10, this fixed distance then determining the constant distance between the two longitudinal edges of the doctor blade. In this manner a straight edge is assured for the working edge of the doctor blade parallel to the other longitudinal edges of the blade. The means by which the gradual downward travel of the grinding element 31 will automatically be halted at a predetermined height above the table 10 will now be explained.

An arm 73 (Figs. 3, 4 and 5) pivotally mounted on the ratchet wheel shaft 64 immediately below the ratchet wheel, carries a curved pawl-engaging member 74, which, when brought into engagement with the pawl 66, bears against the outer end of the pawl and thus keeps the forward tip of the pawl spaced from the teeth on the ratchet wheel periphery. Under such conditions the back and forth travel of the pawl does not produce any rotation of the ratchet wheel. A coil spring 73' having one end fixed and the other end attached to the arm 73 ex erts a constant force to move the arm 73 counter-clocks wise (as viewed in Fig. 5) to bring the member 74 into pawl-engaging position.

The arm 73 has an integral top bracket 75 (Figs. 3, 4 and 5) which extends upwardly and inwardly spaced from the ratchet wheel. A substantially horizontal slidable holding rod 76 (Figs. 2, 3 and 5) has a downwardly-extending finger 77 at one end which engages the edge of the top of the bracket 75 so as to pull the bracket 75, and therewith the arm 73 and pawl-engaging member 74, clockwise against the force of the spring 73' engaging the arm 73, so as to hold the member 74 'normally out of engagement with the pawl 66. The rod '76 is longitudinally slidable in suitable guideways (not shown) and is provided with a lockinglug 79 (Figs. 2, 3 and 5) which lug is adapted to be engaged by the top extension of the forked end of a pivoted locking bar 80 (Figs. 3, 5, 6 and 7) when the locking bar is held in locking position. The locking bar 80 is secured on a rock shaft 81. A spring 82, attached to the locking bar 80, exerts a constant force to raise the forked end of the locking bar to releasing position for the locking lug 79. A wedge member 78 is provided on the rod 76 for moving the end of the locking bar80 downwardly against the force of its spring, and the rod 76 also carries a manipulating. handle 78'.

An actuating bar 83 (Figs. 3, 4 and 7) also secured to'the rock shaft 81, has a pin 84 at its upper end which normally rides on the top face of the feed control disc 47 (see also Fig. l) and, when so doing, holds the locking bar 80. in loweredlocking position with respect to the locking lug 79 on the rod 76. The feed control disc 47 is provided with a slot 85 to receive the pin 84 when the rotation of the control disc 47 causes the slot 85 to be brought into registration with the pin 34. When this occursthe upper end of the actuating bar 83 drops, permitting the rock shaft 81 to. rock slightly and the forked end of the lock 80 to move upwardly under the pull of its spring 82 sufiiciently to release the locking lug 79 of the holding rod 76. This in turn permits the holding rod 76 to slide and the spring-actuated arm 73 (Figs. 2 and 5) to move (counter-clockwise) until the pawlengaging member 74 on the arm 73 engages the pawl 66 and keeps it out of contact with the ratchet wheel 63. The periphery of the control disc 47 carries marking indicia (shown at 47 in Fig. 3) which can be observed through an opening provided in the stationary cylindrical support 36, which opening is provided so as to enable manual setting of the feed control disc 47 to take place.

The operation of the automatic control for the down ward travel of the grinder element 31 is as follows:

The upper clutchelement 48 (Fig. 1) is placed in raised position by' the toggle means previously described. The holding rod 76 is moved to the left until the wedge member 78 (Figs. 3 and 7) forces the end of the locking bar 80 to move down. This causes the upper end of the actuating bar 83 to be raised sufficiently to lift the pin 84 out of the slot 85 on the control disc 47. The control disc 47 is then given a partial rotation, depending upon the amountof downward travel described for the grinder element 31 during the grinding operation. The holding rod 76 is moved slightly to the right and the locking lug 79 becomes engaged by the locking bar 80, since this bar is now held in the lowered position by the raisedposition of the upper end of the actuating bar 83 caused by the riding of the pin 84 on the top of the feed control disc 47. The upper clutch member 48 is then returned to normal lowered engaging position.

The rotation of the table 10 will now result in a gradual rotation of the control disc 47 and upper feed screw 39 and consequently a gradual lowering of the grinding element 31 until the slot 85 on the control disc 47 reaches the pin 84 of the actuating bar 83, When this happens the pin 84 drops down into the slot 85, the slight downward swing of the actuating bar 83 causes a slight upward swing of the locking bar 80, releasing the holding rod 76. The holding rod 76, being released, allows the arm 73 to be moved by its spring 73' until the pawlengaging member 74 engages the pawl 66 and holds it out of contact with the ratchet wheel 63. This causes the rotation of the ratchet wheel, and consequently the rotation of the upper feed screw 39, to cease. Thereupon the grinding element 31 remains at such predetermined fixed distance above the table 10 while the grinding of the doctor blade is completed.

If desired, means may be included in the device for varying the comparative rate of rotation of the ratchet wheel 63 (and therewith the rate of rotation of the upper feed screw 39 and consequentlythe downward travel of the grinder element 31) with respect to the rated rotation of the table 10. Such a special means as shown in-Fig. 5. A plate 86 is rotatably mounted on the ratchet wheel shaft 64 above the ratchet wheel. This plate has a downwardly-extending curved flange at its outer edge, the flange being curved so as to constitute an arc of a circle concentric withthe ratchet wheel The flange extends down beyond the ratchet wheel periphery and is located sufficiently close to the ratchet wheel periphery so that it can be moved into thezpath of the ratchet-engaging tip of the pawl 66 during the return (or counter-clockwise) stroke of the pawl-carrying bracket 65. An adjusting lever 87 is attached to the plate 86 and carries a finger knob 88 which is movable in a slot 90 in a guide plate 89. By adjusting the knob 88, and therewith the plate 86 with its downwardly-extending flange, a slight distance (clockwise) so as to cause the pawl 66 to ride on the outside face of the flange during part of there turn (or counter-clockwise) stroke of the pawl-carrying bracket, the number of ratchet teeth over which the pawl will move with each stroke can be reduced. In this Way the intermittent partial rotations of the ratchet Wheel can be adjusted to a limited extent by this special means, if desired. i

Minor modifications would be possible in the grinding machine assembly without departing from the major features of the same or the scope of the invention.

We claim:

1. In a grinding machine of the character described for grinding doctor blades and the like, a rotating table, means for rotating said table, means for clamping a flexible blade on said table in circular position concentric with the axis of rotation of said table, a grinding element positioned above said table and above the path of said blade, a grinder head supporting said grinding element, an upper feed screw supporting saidhead, a lower feed shaft mounted below said upper feed screw in axial alignment with said upper feed screw, a clutch assembly-connecting said lower feed shaft. and said upper feed screw, manually operable means for disconnecting said clutch assembly, shaft-driving means connected with said lower feed shaft and operated by the rotation of said table, whereby the rotation of .said table, when said clutch assembly is connected, will cause said upper feed screw to be rotated and 'said grinder head and grinder to move downwardly, and a pre-settable limit element for automatically discontinuing the operation of said shaftdriving means during the rotation of said. table.

2. In a grinding machine of the character described for grinding doctor blades and the like, a rotating table, means for rotating said table, anouter circular wall on said table, a plurality of clamping assemblies radially movable on said table for clampinga flexible blade against said outer wall, a rotatable grinding element positioned above said table and abovethe'path of said blade, a grinder head supporting said grinding element, means for rotating said grinder element in said head, an upper feed screw supporting said head, a lower feed shaft mount-ed below said upper feed screw in axial alignment with said upper feed screw, a clutch assembly connecting said lower feed shaft and said upper feed screw, manually operable means for disconnecting said clutch assembly, manually operable means for rotating said upper feed screw when said clutch assembly is disconnected, shaftdriving means connected with said lower feed shaft and operated by the rotation of said table, whereby the rotation of said table, when said clutch assembly is connected, will cause said upper feed screw to be rotated and said grinder head and grinder to move downwardly, a pre-settable limit element in said clutch assembly normally rotated with said shafts, and interrupter means operable by said element for automatically discontinuing the operation of said shaft-driving means during the to tation of said table.

3. In a grinding machine for grinding doctor blades and the like, a, rotating work support, means for rotating said support, means forclamping a flexible blade on said support in circular position concentric with the axis of rotation ,of said support, a grinding element spaced from said support in alignment with the path of said blade on said support, said grinding element and said support being movable relatively towards each other to bring said grinding element against the edge of the blade clamped on said support, means operated 'by the rotation of said support for producing gradual relative travel of said grinding element and said support towards each other, and means for limiting said gradual relative travel of said grinding element and said support relatively towards each other during continuation of the rotation of said support.

4. In a grinding machine of the character described, a rotating table, means for rotating said table, means for clamping a flexible doctor blade on said table in circular position concentric with the axis of rotation of said table, a rotatable grinding element positioned above said table and movable downwardly towards said table against the top edge of the doctor blade clamped on said table, means for rotating said grinding element, means operated. by the rotation of said table for producing gradual travel of said grinding element downwardly towards said table, and means for automatically limiting said gradual travel of said grinding element downwardly towards said table during the rotation of said table.

5. In a grinding machine of the character described for grinding doctor, blades and the like, a rotating work support, an outer circular wall on said support, a plurality of clamping assemblies radially movable on said support for clamping a flexible blade against said outer circular wall, means for moving said assemblies in unison radially on said support, a grinding element spaced from said support, said grinding element and said support being movablerelatively,towards each other, means actuated by the rotation of said support for producing gradual relativetravel of said grinding element and said support towards each other, manually operable means for discontinuing said gradual relative travel of said grinding element and said support towards each other during continuation of the rotation of said support, and pre-settable means for automatically limiting said gradual relative travel of said grinding element and said support towards each other during continuation of the rotation of said support.

6. In a grinding machine of the character described for grinding doctor blades andthe like, a rotating table, means for rotating said table, an outer circular wall on said table, a plurality of identical clamping assemblies radially mounted on said table, each of said clamping assemblies having an end wall constituting an arc of a circle concentric with said outer wall, means for moving said assemblies in unison radially on said table, whereby to clamp a flexible blade between said end walls of said clamping assemblies and said outer circular wall, a grinding element positioned above said table and movabledownwardly towards said table against the top edge of the blade clamped on said table, manually operable means for moving said grinding element downwardly or upwardly, means operated by the rotation of said table for producing gradual travel of said grinding element downwardly towards said table, and manually operable means for discontinuing said gradual downward travel ofsaid grinding element towards said table during the continuation ofthe rotation of said table.

7. In a grinding machine for grinding doctor blades and'the like, a rotating table, means for rotating said table, means for clamping a flexible blade on said table in circular position concentric with the axis of rotation of said table, a grinding element positioned above said stable and movable downwardly towards said table against the top edge of the blade clamped on said table, manually operable means for movingsaid grinding element downwardly or upwardly, means operated by the rotation of said table for producing gradual travel of said grinding element downwardly towards said table, and pre-settable means for automatically limiting said gradual travel of said grinding element downwardly towards said table during continuation of the rotation of said table.

8. In a grinding machine of the character described, a-

rotating table, means for rotating said table, an outer circular Wall on said table, a plurality of clamping assemblies radially movable on said table for clamping a flexible lade against said outer Wall, a grinding element positioned above said table and movable downwardly towards said table against the top edge of the blade clamped on said table, means operated by the rotation of said table forproducing gradual travel of said grinding element downwardly towards said table, manually operable means for discontinuing said gradual downward travel of said grinding element towards said table during continuation of the rotation of said table, and pre-settable means for automatically limiting said gradual travel of said grinding element downwardly, towards said table during continuation of the rotation of said table.

9. The combination set forth in claim 8 with the addition of means for adjusting the relative rate of said gradual travel of said grinding element downwardly towards said table with respect to the rate of rotation of said table.

References Cited in the tile of this patent UNITED STATES PATENTS 1,502,099 Higgins July 22, 1924 2,424,544 Alsdorf July 29, 1947 2,721,425 Christensen Oct. 25, 1955 FOREIGN PATENTS 110,446 Germany May 7, 1900

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