US2730850A - Sharpening attachment for a cloth cutting machine - Google Patents

Description

Jan. 17, 1956 RQCKWQQD r 2,730,850

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE 6 Sheets-Sheet 1 Filed Dec. 17 1949 INVENTORS Albert M. Rockwood Robert M. Conklin Mm, $1M 8 .14

AGENTS.

17, 1956 v K A. M. ROCKWOOD ETAL 2,730,850

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 6 Sheets-$heet 2 FIGURE 2 INVEN T ORB Albert M. Rockwood BY Robert M. Conklin M, M ,5 A,

AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 n 6 Sheets-Sheet 5 IN VEN TORS Albert M. Rockwood F/GURE 4 BY Robert M. Conklirn m, 9M 3 A AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 6 Sheets-Sheet 4 INVENTORS Albert M. Rockwood BY Roben M. Conklln F/GURE 6 FIGURE 5 Hllllll AGENTS.

J 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE 6 Sheets-Sheet 5 Filed Dec. 17, 1949 F/GURE 7' FIGURE 8 INVENTORS Albert M. Rockwood Robert M. Conklin m w 15 in AGENTS.

Jan. 17, 1956 A. M. ROCKWOOD ETAL 2,730,350

SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Filed Dec. 17, 1949 6 Sheets-Sheet 6 FIGURE 9 F/GURE /0 Albert M. Rockwood BY Robert M. Conklin won, ykum a...

AGENTS.

United States Patent t SHARPENING ATTACHMENT FOR A CLOTH CUTTING MACHINE Albert M. Rockwood and Robert M. Conklin, Columbus, Ohio, assignor, by mesne assignments, to The Wolf Mfirlchine Company, Cincinnati, Ohio, a corporation of O '0 Application December 17, 1949, Serial No. 133,606

3 Claims. (Cl. 51-249) This invention relates to a cloth-cutting machine having a reciprocating knife blade, and more particularly to an automatic sharpening device for grinding the knife blade.

Many attempts have been made to replace the customary method of sharpening the knife by drawing an emery stick downward along the blade. However, the various sharpening mechanisms have had the disadvantages of obscuring the view of the operator when operating the cutting machine or being required to be detached from the machine when not in use. Other devices of the prior art have been manually operated, with the concurrent danger of injury to the operator by accidental contact with the knife blade.

Another problem which has not been satisfactorily met is the effect of the wearing away of the grinding means and the knife edge after a period of use. For the best cutting eifect the included angle of the bevel on the knife edge should be not less than 10 nor more than 25. In prior devices the gradual wearing away of the grinding means and knife edge has resulted in a change in the bevel of the knife edge and a resulting inferior cutting action. Also, since the toe of the knife blade operates on the cloth with a chopping effect, it is desirable to sharpen the bottom end of the knife blade, and until now no satisfactory method has been found to utilize automatic knife sharpening means for this purpose.

One object of the present invention is to provide sharpening means, mounted on a cloth cutting machine, which move vertically along the length of the knife blade as the grinding wheels revolve, and during the same operation grind the toe of the knife blade.

Another object is to provide a reciprocating mechanism for the sharpening means whereby the driving torque is automatically disconnected and the sharpening mechanism braked, after the sharpening cycle is completed.

A further object is to provide a means for operating the sharpening mechanism in which all gears are shielded from any abrasive dust.

Yet another object is to provide a novel support for the grinding means which automatically compensates for Wear of the grinding means so that the knife blade is always ground at the optimum angle for best results in cutting cloth.

Other objects and advantageous features will be apparent from the following detailed description and the accompanying drawings wherein similar characters of reference designate corresponding parts, and wherein:

Figure 1 shows a side elevation of the machine with the presser foot lowered to the position where it is resting on the base.

Figure 2 is a vertical sectional view of the machine, showing the presser foot in the raised position.

Figure 3 is a view of the machine taken along the line 33 of Figure 2.

Figure 4 is a sectional view taken along the line 4-4 of Figure 3.

Figure 5 is a sectional view taken along the line 5--5 of Figure 1.

2,730,850 Patented Jan. 17, 1956 Figure 6 is a sectional view taken along the line 6-6 of Figure 2.

Figure 7 is a sectional view taken along the line 77 of Figure 6.

Figure 8 is a sectional view taken along the line 8-8 of Figure 2.

Figure 9 is a view of the grinding wheels, showing them in operating position to contact the knife blade.

Figure 10 is a view similar to Figure 9, showing the grinding wheels in the inoperative position out of contact with the knife blade.

Figure 11 is a front elevational view of the larger of the two grinding wheels used in this invention;

Figure 12 is a side elevational view of the larger of the two grinding wheels used in this invention.

Figure 13 is a front elevational view of the smaller of the two grinding wheels used in this invention; and

Figure 14 is a side elevational view of the smaller of the two grinding wheels used in this invention.

The improved cloth-cutting machine of this invention as shown in Figure 1 comprises a base 15, a vertical standard 16 mounted thereon, a housing 17 for the motor and knife reciprocating mechanism, and a removable unit 19 containing the sharpening mechanism. The removable unit 19 is secured to housing 17 by means of screws 200 passing through flanges 2431 extending outwardly from the sides of removable unit 19.

The base consists of a pivoting front toe plate 20, a base plate 18, and spring-mounted rollers 22 which are mounted in the base plate to provide for easy movement of the machine during the cloth-cutting operations.

The standard 16 is provided with a vertical slot lined with a wear strip 21 which guides the reciprocating knife blade 24 during its movement.

A housing 17, made in three parts, is attached to the upper part of the standard 16 and encloses an electrical motor, a fan, and a centrifugal switch. Mounted at the bottom of the housing is a toggle switch 202 to control the motor, and a handle 18 for guiding the machine during the cloth-cutting operation. On top of the housing are a carrying handle 28 and a suitable terminal block 29 to supply electric power to the motor.

Knife reciprocating mechanism As illustrated by Figures 2 and 3, the electric motor drives a shaft 30 on which is mounted a fiy-wheel and crank assembly 32. The fly-wheel and crank assembly comprises a counterweight 33 to which a drive rim 34 is connected by suitable fastenings. A crank pin 35 is connected to the fly-wheel and crank assembly 32, and supports the connecting rod bearing 37 and retaining screw 38. This bearing 37 supports connecting rod 39 which is held in place by lock nut 41.

The connecting rod supports between its arms the crosshead 43, and its liner 45, by means of a bushing 42 and a through bolt 46. A split connecting rod is used to reduce wear on the bushing. The through bolt 46 is held in position by anchor nut 47 which, in turn, is secured to the connecting rod by screws 49. The crosshead 43 and liner 45 are separated from the connecting-rod arms by wipers 50. Projecting from the lower end of the crosshead 43 is a lug 51 to which the knife blade is secured by suitable fastening means, such as a bolt and nut 52.

In its vertical movement the crosshead 43 is guided by gibs 54 which are fastened to the front shell casting 55. The alignment of the crosshead requires a delicate adjustment of the gibs so that the knife blade will be properly positioned relative to the standard or satisfactory cutting of the cloth and will not bind on the wear strips in the standard. In the novel device of-the present 'of sharpener housing 66.

invention this adjustment may be accomplished quickly and easily in the following manner as shown in detail in Figure 4:

Gib. springs 56 are fitted around the adjusting pins 57 and are held in contact with the gibs by spring retainers 59 which are screwed into the front shell casting 55. The pins 57 are located in line with the gib hold-down screws 60 so that the locking action of these screws, when applied, will not exert a torque on the gibs which would move them out of alignment. Nuts 61 are fitted onto the ends of the adjusting pins 57 which project through the spring retainers 59. To adjust the gibs 54, the holding screws 60 are loosened and the gibs positioned by means of the nuts 61 on the ends of the adjusting pins 57. The gibs are than locked in position by tightening the holding screws 60.

The crosshead 43 is lubricated by means of elbow cups 62 mounted on the front shell casting 55. The oil is conveyed by copper tubes to the recesses 64 in gibs 54 and through holes to the sliding surface of the gibs. Holes in the side of the c'rosshead allow the oil to pass through the liner 45 and lubricate the bearing surface, which is the bushing 42. Any abrasive particles present will wear this steel bushing rather than the bronze liner, and for this reason, it is so constructed as to be readily replaceable.

Presser foot shaft Positioned in front of the knife blade 24 and standard 16 is the presser foot shaft 65, slidably mounted in a bearing within the lug 72 which projects from the front This is shown inv Figure 5. At the bottom of the shaft 65 is mounted a presser foot 67, in such a manner that the foot will contact cloth to be out only in the vicinity of the knife blade. The rear portion of the presser foot is divided in order that the foot may clear the knife blade. The shaft 65 also serves as a safety guard when lowered to the position in which the presser foot contacts the cloth, as in this position the opertaor is protected from accidental contact with the knife blade. At the upper end of the shaft 65 a handle 68 is mounted for convenience in raising and lowering the presserfoot. The shaft 65, together with the attached presser foot 67, is held in any desired position by means of lock pin 70, which is forced against the shaft 65 by the action of spring 71. Spring 71 and lock pin 70 are held in position in the sharpener housing casting 66 by nut 73' threaded to fit the casting. Yoke 74 fits into the threaded center hole of lock pin 70. Handle 76 is mounted between the arms of the yoke 74 by a stud and-nut 77 and pivots by means of pivot stud 78 which holds it to a lug projecting from sharpener housing casting 66. Thus movement of the handle 76 toward the machine will force the yoke 74 and connected lock pin 70 out of contact with the presser foot shaft 65, permitting vertical movement of the shaft. As the handle 76 is released, the action of spring 71 against the lock pin 70 holds shaft 65 in any desired position.

When the foot shaft is lowered to the position where the presser foot 67 is resting on the base 15, the groove "75 near the upper end of the shaft 65 is moved into a position whereby it may be engaged by the lock pin 70. As the lock pin 70 moves into this groove the resulting pivot action permits the release handle '76 to move a greater distance from the machine to a position where itno longer blocks an interlock control rod 79. When the presser foot is in raised position release handle 76 is immediately under interlock control rod 79 and prevents it from moving downwardly to actuate the sharpener mechanism. When the interlock control rod 79 is free to move downward, the sharpener mechanism may be operatcd. It can thus be seen that the sharpener mechanism can be operated only when the presser foot is in its lowest position, and there is no possibility of injury to the presscr foot or the grinding wheels by accidental contact of these parts during the grinding operation. Such an interlock Sharpener mechanism As shown in Figures 6 and 8, the sharpener mechanism is actuated by the starting lever 80, which is pivotally connected to the upper end of the interlock control rod 79. The opposite end of the starting lever 80 is rotatably fastened by means of stud 81 to a collar welded to support plate 83.

Spring loading pin 84, which is an integral part of the starting lever 80, extends over the actuating pin 85. As the starting lever 30 is depressed, pin 84 bears on the actuating pin 85 which slides downward in bushing 86 mounted in support plate 83, thereby compressing fric tion wheel spring 87 into sliding block 88 and forcing the block assembly downward along guide pins 90 and 91 until the rubber tire on friction wheel 92 contacts the fly wheel rim 34 which supplies driving torque to the sharpening mechanism. Spring 87, which is retained in the sliding block 88 by spring-retainer plates, serves to compensate for wear of the friction wheel 92. Drive pulley shaft 95 is supported in sliding block 88 by means of a bearing 97. Mounted on the end of shaft 95 is the friction wheel 92. Sliding block 88 is held in place by snap rings on the guidepins 90 and 91. Circular motion is transferred from fly wheel rim 34 to friction wheel 92, and by means of shaft 95 to the drive pulley 98. An O-ring belt 99 passing around pulley 98 drives pulley 100.

Bearing housing 101 supports stub shaft 102 on which are mounted pulley and gear 104, shown in greater detail in Figures 6 and 7. The gear and pulley are pinned by pins 105, so that they rotate together. In mesh with gear 104 is gear 106 which is keyed to worm shaft 107 and held in place by a stop nut. Worm shaft 107' is supported by two bearings 108 and 109 located in bearing housing 101. A standard worm 111 is mounted on worm shaft 107, and is pinned to the shaft. The worm drives worm wheel 112 which is keyed to worm wheel shaft 113 and held in place by an elastic stop nut 114. Worm wheel shaft 113 revolves in a bearing 115 mounted in bearing housing 101 and extends into the reversing drive shaft 116.

On the outside of the reversing drive shaft 116 is cut an endless peripheral square thread 117 so that there is a section'extending downwardly which connects with a section extending upwardly which in turn connects with the downwardly extending section. These grooves limit the travel of the sharpening mechanism. The reversing shaft 116 is pinned to the lower end of worm wheel shaft 113 and is suspended from it.

Sharpener tube 119, reversing drive shaft 116, and a square grinding wheel drive shaft are arranged concentrically. Reversing shaft 116 rotates freely inside of sharpener tube 119 which reciprocates vertically. Grinding wheel drive shaft 120 is mounted in the sharpener tube 119 by means of the bearing 121 pressed in the end of the sharpener tube. Thus, drive shaft 120 moves vertically with sharpener tube 119 but may also rotate with respect to it. The upper end of the drive shaft 120 is.

guided by bearing 122, and as the shaft reciprocates it passes through the drive shaft guide 123 which is pressed into the end of reversing drive shaft 116. Drive shaft guide 123 transmits rotary motion from the reversing drive shaft 116 to the grinding wheel drive shaft 120 by means of the square hole therein contained through which square shaft 120 passes. Sharpener tube 119 passes through end seal nut 124 which is screwed into the bottom of sharpener housing 66. The threaded drive shaft 116, the gear mechanism, and the ball bushing 118 are shielded from the abrasive effect of the grinding grit by the seal nut 124. The lower end of sharpener tube 119 supports an adaptor plate 127 to which the grinding head is secured.

The reciprocating mechanism Vertical movement of the grinding mechanism is provided by means of a follower 128 which moves in the endless peripheral groove 117 of the reversing drive shaft 116, as in Figure 8. The follower 128 is mounted in follower guide 129 and is forced in contact with the peripheral groove 117 by means of spring 130. Spring 130 and follower 128 are held in place by retaining nut 131.

Follower guide 129 fits around sharpener tube 119 and is locked to the tube by stud 132 which passes through clamping flanges 134 and is secured by lock washer 135 and nut 136. A finger 137 on the follower guide 129 fits into the groove 138 in the support plate 83 so as to slide vertically but to prevent the guide 129 and sharpener tube 119 from rotating. A flange 139 projecting outwardly from follower guide 129 supports the adjustable pawl release screw 140, shown obscured by the pawl actuating pin 142 in Figure 8.

Automatic sharpening cycle mechanism The sharpening mechanism is automatically disengaged from the fly wheel rim 34 after the completion of one vertical cycle of reciprocation in the following manner: A shaft 141 is fitted through the support plate 83. Pa'wl actuating pin 142 is brazed to the head of shaft 141. On the opposite end of shaft 141 are mounted pawl spacer 143, pawl actuating spring 144, and pawl 145 which is secured to the shaft by key 146, the assembly being held in place by a snap ring 147. When the sharpener starting lever 80 is sufficiently depressed, the spring loading pin 84 passes the notch in pawl 145 and is retained by it as the pawl actuating spring 144 forces the pawl into position.

Upon the completion of the sharpening cycle, as the follower guide 129 moves upward, the adjustable pawl release screw 140 contacts the pawl actuating pin 142 forcing it upward, thereby rotating shaft 141 and pawl 145 against the torque exerted by spring 144. This action releases spring loading pin 84. Spring loading pin 84 and control lever 80 are then forced upward by the friction wheel spring 87 and the tension of O-ring belt .99 to their original position. Sliding block 88 in moving upward carries with it friction wheel 92 and removes it from contact with fly wheel rim 34. As friction wheel 92 continues to move upward it contacts the lug 149 aifixed to support plate 83 and is braked by it. By means of this braking device, the sharpening mechanism is stopped at the highest point of its travel, thereby insuring that the grinding mechanism will be out of the way of the operator when the machine is used for cloth cutting and that the grinding wheels are removed from contact with the knife blade, as will later be described.

This mechanism provides that if the machine should be stopped during its grinding cycle the sharpener starting lever could not be released until the grinding mechanism is returned to its highest position.

Grinding mechanism The grinding mechanism is enclosed within or attached to grinding head housing 150. Thus its gears are protected from the abrasive effects of the dust resulting from: grinding. Rotating movement is furnished by driver gear 151, keyed to the bottom of grinding wheel drive shaft 120. Gear 151 meshes with the gear 152 of grinder shaft 153. Grinder shaft 153 is supported within grinding head housing 150 by means of a bearing 154 held in place by a snap ring 155. The top of grinder shaft 153 fits snugly in adapter plate 127. Drive pulley 157 is threaded onto grinder shaft 153 and rigidly held in place by lock nut 158. Below this lock nut is mounted idler pulley 159, which is held in place by a snap ring.

The knife blade is ground by means of two abrasive 6 grinding wheels 160 and 161, one of which is larger than the other. The grinding wheels are slidably mounted on shafts 162. The shafts are supported by bearings 164 within the fixed bearing supports 165. Bearing supports 165 are secured by fastening means 166 to grinding head housing 150. The grinding wheels 160 and 161 are positioned at an angle of about 10 degrees from the vertical and an angle of from 5 to 12 degrees from the plane of the knife blade 24. The arrangement of the grinding wheels 160 and 161 will grind the blade 24 evenly at all points during the reciprocating movement and will also grind the toe of the knife blade. In prior machines the included angle of grind on the knife has varied with wear, but the positioning in the present machine will insure that as either the grinding wheels or the knife blade wear, the angles at which the grinding surfaces contact the knife blade will not change, but will remain constant and give optimum grinding results during a long period of use. Shafts 162 also support pulleys 167, which are pinned to the shafts by taper pins. The grinding wheels are driven in opposite directions by a single O-ring belt 168 which passes over drive pulley 157, grinder shaft pulleys 167, and idler pulley 159.

Grinding wheels 160 and 161 are held in contact with the knife blade by means of a spring-loaded mechanism as in Figure 9. Bell cranks 169 are mounted on the grinding head housing 156 by pivot studs 170. Fingers 171 are fastened to the bell cranks 169 by means of screws and pins. Slots at the end of the fingers 1'71 fit around the ends of the grinding wheel shafts 162. Torsion springs 174 acting on the bell cranks 169 force the grinding wheels 160 and 161 against the knife blade 24.

When the grinding mechanism is raised to its highest position, as in Figure 10, the position at which the mech anism is stopped by the brake as described hereinbefore, the bell cranks 169 contact pins 175 which are loaded by springs 176 and which are secured in place by snap rings. When the bell cranks 169 are forced into contact with the spring-loaded pins 175 the bell cranks are rotated in such a manner that the grinding wheels 16% and 161 are moved out of contact with the knife blade 24. However, when the grinding mechanism moves downward during the grinding cycle, the spring-loaded pins 175 move down until stopped by their snap rings, and as the bell cranks 169 move out of contact with the springdoaded pins, the action of the torsion springs 174 forces the the grinding wheels into contact with the knife blade. As the grinding wheels go below the upper limit of travel of 'the top of the blade, they are forced in still further, thereby grinding the toe of the blade.

Operation 0 the sharpener When it is desired to sharpen the knife blade, the machine is removed from the cloth being cut. The presser foot release handle 76 is moved toward the machine, allowing the presser foot shaft 65 to move downward until the presser foot 67 rests on the base plate 15. The presser foot handle 76 is released and moves outward from the machine until it clears the interlock control rod 79. The sharpener starting lever 36 can now be depressed until it locks through the action of notched pawl 145 catching spring-loading pin 84. The interlock control rod 79 now blocks the movement of handle 76 so that the presser foot shaft 65 cannot be moved until the grinding cycle is completed. In this position friction wheel 92 contacts flywheel rim 34 and the grinding mechanism is set in operation. As the sharpening mechanism begins to descend, the rotating grinding wheels 160 and 161 contact the knife blade 24. When the mechanism is lowered a short distance beyond the point where the grinding wheels begin to sharpen the toe of the knife blade, the mechanism begins to rise. As it reaches its upper position the springloading pin 84 is released from notched pawl 145, and

the friction wheel 92 rises until it is braked. The foot shaft release handle 76 may now be moved toward the machine and the presser foot shaft 65 raised. The machine is now ready for further cutting operations.

As can be seen by the foregoing description the improved machine of this invention 'is simple in construction, requires a minimum of maintenance and any part may be conveniently and quickly replaced with no need for delicate adjustment. It can be operated by a person without particular skill, with little danger of accidental injury from moving parts.

It will be understood that modifications may be made in the design and arrangement of the parts without departing from the scope of this invention, which is intended to be limited only as required by the following claims.

What is claimed is:

1. In a cloth cutting machine having a reciprocating knife blade and a motor for moving said blade, a sharpening device comprising a peripherally threaded hollow shaft, a circular tube positioned coaxially outside said threaded shaft, a follower secured to said tube and engaging the threads on said threaded shaft, a housing removably attached to said machine and enclosing said tube, said housing and said tube enclosing the peripheral surface of said threaded shaft, means for rotatably supporting said threaded shaft in said housing, power transmission means between said motor and said shaft, a noncircular drive shaft inside said threaded shaft, a guide member fixed to said threaded shaft having an opening complementary to said drive shaft through which said drive shaft reciprocates, a grinder-head housing secured to the lower end of said tube enclosing the bottom of said tube and said drive shaft, knife-grinding means mounted below said tube and separated from said tube and said shaft by said grinder-head housing, and power transmission means between said drive shaft and said grinding means.

2. In a cloth cutting machine having a reciprocating knife blade and a motor for moving said blade, a sharpening device comprising a peripherally threaded hollow shaft, a circular tube positioned coaxially outside said threaded shaft, a follower secured to said tube and engaging the threads on said threaded shaft, a housing removably attached to said machine and enclosing said tube, said housing and said tube enclosing the peripheral surface of said threaded shaft, means for rotatably supporting said threaded shaft in said housing, power transmission means between said motor and said shaft, a noncircular drive shaft inside said threaded shaft, a guide member fixed to said threaded shaft having an opening complementary to said drive shaft through which said drive shaft reciproeates, a grinder-head housing secured to the lower end of said tube enclosing the bottom of said tube and said drive shaft, rotatable circular knife-grinding means mounted below said tube and separated from said tube and said shaft by said grinder-head housing, said knife-grinding means positioned to contact the knife blade so that their axes of rotation are inclined at an angle from the horizontal and having an included angle of 156 to when projected on a horizontal plane, and power transmission means between said drive shaft and said grinding means.

3. In a cloth cutting machine having a reciprocating knife blade and a motor for moving said blade, a sharpening device comprising a peripherally threaded hollow shaft, a circular tube positioned coaxially outside said threaded shaft, a follower secured to said tube and engaging the threads on said threaded shaft, a housing removably attached to said machine and enclosing said tube, said housing and said tube enclosing the peripheral surface of said threaded shaft, means for 'rotatably supporting said threaded shaft in said housing, power transmission means between said motor and said shaft, a noncircular drive shaft inside said threaded shaft, a guide member fixed to said threaded shaft having an opening complementary to said drive shaft through which said drive shaft reciprocates, a grinder-head housing secured to the lower end of said tube enclosing the bottom of said tube and said drive shaft, rotatable circular knife-grinding means mounted below said tube and separated from said tube and said shaft by said grinder-head housing, said knifegrinding means positioned to contact the knife blade so that their axes of rotation are inclined at an angle of 10 from the horizontal and having an included angle of 156 to 170 when projected on a horizontal plane, and power transmission means between said drive shaft and said grinding means.

References Cited in the file of this patent UNITED STATES PATENTS 1,815,017 Wagner July 14, 1931 1,815,018 Wagner July 14, 1931 1,884,924 Van Berkel Oct..25, 1932 2,060,197 Greenbaum Nov. 10, 1936 2,282,918 Zawistowski May 12, 1942 2,423,570 Steiner July 8, 1947 2,444,909 Bangser July 13, 1948v 2,450,473 Goldie Oct. 5, 1948 2,480,278 Zawistowski Aug. 30, 1949 2,529,441 Zawistowski Nov. 7, 1950

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