US2954227A

US2954227A - Carton feeding device

Info

Publication number: US2954227A
Application number: US592139A
Authority: US
Inventors: Robert K Galloway
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1956-06-18
Filing date: 1956-06-18
Publication date: 1960-09-27
Anticipated expiration: 1977-09-27

Description

Sept. 27, 1960 R. K. GALLOWAY CARTON FEEDING, DEVICE 6 Sheets-Sheet 1 Filed June 18, 1956 mm mw m@ 6 an E INVENTOR ROBERT K. GALLOWAY AITO RN EY Sept. 1 1 R K. GALLQWAY 2,954,221

CARTON FEEDING DEVICE Filed June 18, 1956 6 Sheets-Sheet 2 INVENTOR ROBERT K.GALLOWAY ATTORNEY P 1960 R. K. GALLOWAY 2,954,227

CARTON FEEDING DEVICE 6 sheets sheet 4 Filed June 18, 1956 I INVENTOR v.

ROBERT K. GALLOWAY ATTORNEY Sept. 27, 1960 R. K. GALLOWAY CARTON FEEDING DEVICE Filed June 18, 1956 6 Sheets-Sheet 5 I Q I iNvEN-roR I. r )ROBERT K. GALLOWAY BY g;

ATTORNEY .Patented Sept. 27, 1960 CARTON FEEDING DEVICE Robert Galloway, Hoopestoin'IiL, assignor to Food Machinery and Chemical Corporation, San Jose, Calif., a corporation of Delaware Filed June 18, 1256, Ser. No. 592,139

Claims. (Cl. 271-34) In the packaging of frozen foods, a reduction in the cost of the packaging material is realized when the car- .tons used vare of lightweight construction or made of thinner material than is commonly used in frozen food packaging processes. However, such lightweight cartons are less rigid than the commonly used cartons, and when removed from a supply stack by conventional devices,

tend to separate from the stack two at a time. Further, such cartons are more fragile and, therefore, more susceptible to damage.

Accordingly, an object of the present invention is to provide a carton feeding device adaptable for use in the feeding of lightweight cartons.

Another object of the present invention is to provide an improved gate mechanism for a carton feeding device.

Another object is to provide a carton feeding device for lightweight cartons, which will feed cartons, one at a time, in succession to a carton'handling mechanism.

Another object of the present invention is to provide an improved feeder lug for a carton feeding device.

Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. l is a fragmentary plan of the carton feeding device embodying the present invention.

Fig. 2 is a fragmentary side elevation of the carton feeding device of Fig. l, with a stack of cartons shown in the supply magazine.

Fig. 3 is a fragmentary vertical section of a portion of Fig. 1 taken along lines 33 thereof.

Fig. 4 is a fragmentary horizontal section of the carton feeding device takenalong lines 44 of Fig. 2.

Fig. 5 is a fragmentary vertical section of Fig. 1 taken along lines 5 thereof.

Fig. 6 is a fragmentary vertical section of Fig. 2 taken along lines 6-6 thereof.

Fig. 7 is a fragmentary enlarged perspective of a movable gate mechanism used in the carton feeding device of the present invention.

Figs. 8, 9 and 10 are diagrammatic illustrations of the movable gate mechanism and carton feeder lugs used in the present feeding device, showing successive operating positions and the timed relationship between the gate mechanism and the lugs.

The present invention is an improvement over a device described and claimed in US. Patent No. 2,749,118 to Charles E. Kerr et al., in that the present device is adaptable for use in the feeding of lightweight cartons, as well as cartons of heavier construction. The carton feeding device disclosed herein is adaptable for use with a carton handling device of the type described in US. Patent No. 2,765,715 to Charles E. Kerr, which carton handling device is partly illustrated herein.

. The carton feeding device 20 of the present invention includes a magazine 21 on which collapsed cartons C (Fig. 2) are stacked in a horizontal column so that the plane of each carton C extends in a vertical direction transversely of the magazine 21. The column of collapsed cartons is urged forward on the magazine 21 by a stack advancing mechanism 19 to a carton removing mechanism 22. Included in the carton removing mechanism 22 are a series of spaced carton feeder lugs 23, each of which is mounted between two

parallel conveyor chains

24 and 25. The feeder lugs 23 remove the cartons from the stack, one at a time, in succession transversely of the magazine 21 and advance them laterally in succession to a pair of upper rollers 26 and 27 (Fig. 1) and a pair of lower rollers 26:: and 27a (Fig. 3). The

rollers

26 and 26a have toothed edges that engage and advance the removed cartons in succession to a carton opening machine 18.

As shown in Figs. 1 and 2, the carton feeding device 2% of the present invention comprises a structure 34- which may be supported by any suitable means at the desired level. The structure 34 includes a table 35, which serves as a support base for the carton magazine 21. The cartons are received for placement on the magazine in a collapsed condition and are placed on the magazine so that the plane of each carton, designated as C in Fig. 2, extends in a vertical direction transversely of the magazine 21. Y

The carton magazine 21 and the stack advancing mechanism 19 are completely disclosed in the above-mentioned Patent No. 2,749,118. In general, the magazine 21 includes a pair of spaced

upstanding side walls

40 and 41 removably secured to brackets 36 that are adjustably mounted on the base 35. By adjusting the

side walls

40 and 41 toward or away from each other, the lateral dimension of the cartons C can be accommodated. Secured to the inner surface of the

side walls

40 and 41, respectively, are inwardly disposed low-

friction liners

42 and 43. The lateral confinement of the cartons is effected by the close contact between the side edges of the cartons and the liners 42 and 4 3 of the

side walls

40 and 41.

The bottom edges of the cartons C rest upon

rods

44 and 45, which provide a lower wall for the magazine 21,

" so that substantially the entire weight of the cartons is carried by the

rods

44 and 45. Each rod isconstructed with a supporting foot 46, which extends through a clamp boss 47 and is secured therein for vertical adjustment by a setscrew 48. The rods 44 and can be clamped at a desired vertical height to accommodate the vertical dimension of the carton C. v

The stack advancing mechanism 19, which urges the cartons toward the carton discharge end of the magazine, includes a pair of carriages 50 and 51 (Figs. 1 and 2). For moving the

carriages

50 and 51 relative to the magazine 21, each of the

side walls

40 and 41 is provided with upper and lower tracks 52 and 53 (Fig. 5) formed on the outer surface thereof. The

tracks

52 and 53 are provided with

grooves

54 and 55, respectively, the upper groove 54 being arranged to receive a pair of longitudinally spaced rollers 56 and 57 (Fig. 2) while the lower groove is arranged to receive spaced rollers 58 and 59. The

rollers

56, 57, 58 and 59 are mounted on their respective carriage bodies 60 so that the

carriages

50 and 51 travel longitudinally along the magazine frame 21 on the

tracks

52 and 53 of the side walls 40 and 41in a rectilinear path. Each of the carriages is separately movable toward the carton discharge end of the magazine frame 21 either manually, by means of an upwardly extending handgrip 61, or automatically by means of a weight 64, which is secured to one end of a flexible cable 62. The cable 62, which is connected at the otherend thereof to a body portion 60 of the carriage, is trained over a groove pulley 63 pivotally mounted on the associated side wall.

In order to apply uniform pressure to the stack of cartons as it is advanced toward the discharge end of the magazine frame 21, upper and lower presser pawls 65 and 66 (Fig. are provided on each side of the magazine frame 21. Referring to Figs. 1 and 4, each presser pawl is pivotally mounted to swing into and out of the magazine frame 21 about the axis of a pivot bolt 67, which extends through an ear 68 of the associated carriage. The generally flat, vertically disposed body 60 of each carriage has upper and

lower springs

70 and 71, respectively, secured on its forward end (Fig. 2). These

springs

70 and 71 bear against the

presser pawls

65 and 66, respectively (Fig. 1), to urge the

pawls

65 and 66 toward the center of the magazine frame 21 to a position wherein the forward face of the pawls is arranged to contact the flat surface of the rearmost carton in the magazine frame 21.

The carton removing mechanism 22 (Figs. 1 and 2), which removes the collapsed cartons C from the end of a the column of cartons, comprises the previously mentioned vertically elongated feeder lugs 23, which are carried by the parallel endless conveyor chains 24 and and are spaced at equal intervals therearound. The leading carton of the stacked column of collapsed cartons is engaged by one of the series of feeder lugs 23, removed from the magazine, and advanced transversely of the magazine frame to the

rollers

26 and 27.

Each feeder lug 23 is provided with a broad continuous body portion 72 (Fig. 2), which extends vertically between the

parallel chains

24 and 25. For engaging the side edge of the leading carton C of the collapsed cartons stacked on the magazine frame 21, the body portion of each feeder lug 23 (Fig. 8) is provided along its entire length with an angularly disposed carton engaging edge surface 73 which is inclined outwardly away from the

conveyor chains

24 and 25 so as to provide a camming surface. Rearwardly of the inclined surface 73, the lug body has a flat surface 74, which is adjacent to a rear shoulder 75. The shoulder 75 of each lug 23 extends outward from the body portion 72 and away from the

conveyor chains

24 and 25 at a predetermined distance so as to accommodate only one carton at a time. The shoulder 75 in conjunction with its adjacent fiat surface 74 provides a seat on which the trailing edge of the carton is disposed as it is removed from the stack and moved laterally from the magazine frame 21. In order to prevent excess dislodged wax, which may be deposited on the lug by the cartons C, from collecting on the shoulder 75, a suitable slot or Wax retrieving pocket 76 is provided in each lug 23 between the shoulder 75 and the flat surface 74.

For driving the endless

parallel conveyor chains

24 and 25 to advance the feeder lugs 23, a pair of sprockets 77 and 78 (Fig. 6) are provided. The

endless chains

24 and 25 are trained about the

sprockets

77 and 78, respectively, which are fixedly secured to a drive shaft 79. The shaft 79 is driven from the drive mechanism of the carton opening mechanism 18 by means of a gear (not shown) that is in mesh with a gear 82 keyed on the shaft 79. As shown in Figs. 2 and 6, the drive shaft 79 has an upper end portion arranged to rotate in a journal 80 formed on a bracket 81 extending from the side wall 41 and has a lower end portion arranged to rotate in a bearing formed in the base 34. The

endless chains

24 and 25 are also trained about idler sprockets 83 and-84,

which are rotatably mounted on an idler shaft 85. The shaft 85 has a pair of end portions 86 and 87 disposed within spaced upper and lower

bifurcated bearings

88 and 89 formed on a guide frame 90 (Fig. 1).

The frame 90 guides the leading carton as it is removed from the stack and advanced by the feeder lug 23. The guide frame 90 (Figs. 3 and 4) is a box-like member having a vertical, generally square, forward wall a that is substantially parallel to a plane extending transversely of the carton magazine. Along one side edge, the guide frame 90 has a pair of hubs 91 and 92 (Fig. 6) which receive the shaft 79 and mount the frame for adjusting pivotal movement. At the opposite edge, the guide frame 90 includes the

bifurcated bearings

88 and 89, which receive the end portions of the idler shaft 85. A stud 94 (Fig. 1) is threaded into the frame 90 near the upper bifurcated bearing 88 and is adjustably secured by lock nuts 95 in a clearance hole 96a of an upstanding plate 96, which is attached to the wall 40. By this arrangement, the guide frame 90 can be adjustably positioned by threading the stud 94 in or out of the frame 90, and pivoting the frame about the shaft 79. When the guide frame 90 is properly positioned, the stud 94 is locked in place by the nuts 95 to maintain the guide frame 90 in a fixed position. Since the drive sprockets are concentric with the mounting shaft 79 of the guide frame 90, the guide frame 90 can be adjusted without interfering with the drive mechanism.

In order to hold a carton in an upright flat position while the feeder lug 23 engages and seats it, the guide frame 90 includes a pair of

vacuum chambers

97 and 98. As shown in Figs. 3 and 4, the

vacuum chambers

97 and 98 are formed in the guide frame 90 above and below the level of the

conveyor chains

24 and 25. The

vacuum chambers

97 and 98 register with passages in an adapter 100 which is secured to the rear wall of the guide frame 90. The adapter bridge 100 extends over both

conveyor chains

24 and 25, and has coupled thereto a flexible hose 101 which is connected to a suitable source of subatmospheric pressure or vacuum, not shown. Grids 102 and 103 (Fig. 3) are secured to the forward wall of the guide frame in registry with the

vacuum chambers

97 and 98, respectively. The suction which is maintained in the

chambers

97 and 98 is strong enough to draw the fore most carton toward the guide frame 90 and hold it against the grids without holding the carton so securely that it cannot be moved laterally from the grids by the lug 23 on the

chains

24 and 25.

To assist in supporting the carton as it is advanced by the lug, a slide bar 104 (Fig. 3) is mounted on an adjustable support 105 so as to be substantially coplanar with the

rods

44 and 45 of the magazine. The lower edge of the carton rests on the bar 104 as the carton approaches and leaves the

grids

102 and 103.

When a carton is flattened against the

grids

102 and 103 and rests upon the slide bar 104, one of the feeder lugs 23 engages the side edge thereof. As the

conveyor chains

24 and 25 advance the feeder lugs 23, the engaging feeder lug overcomes the resistance caused by the vacuum and advances the removed carton laterally of the magazine. As soon as the advancing carton clears the

grids

102 and 103, there is a vacuum release of that carton, and thereupon the vacuum becomes effective to draw the succeeding carton into engagement with the grids on the magazine frame 21.

To permit only one carton at a time to be removed from the magazine frame 21 by the lug 23, a stationary gauge plate 106 (Fig. 7) is provided. The gauge plate 106 is secured by fastenings 106a to the forward end of the side wall 41. The gauge plate 106 is provided with oppositely extending

projections

107 and 108 spaced inwardly from the leading end thereof. Projection :107 forms a seat or shoulder 109 for receiving a stripper block 110, while the projection 108 forms a seat or shoulder 111 for receiving a stripper block 112. The stripper blocks and 112 are secured to the gauge plate 106 by suitable means such as silver solder and have fiat forward faces 115 and 116 which are disposed in a common vertical plane. These faces are spaced from the carton-guiding surfaces of the grids 102 and 103 a distance that is slightly greater than the thickness of one 'to a closed position.

carton. Accordingly, only one carton can pass through this fixed opening.

As seen in Fig. 7, the stripper blocks have inwardly

inclined surfaces

113 and 114 which offset the foremost carton, and preferably, a few of those immediately following, from the other folded cartons in the magazlne. The direction of such offsetting is opposite that in which the conveyor lugs '23 move across the end of the magazine. The degree of such offsetting of each carton becomes progressively greater as the carton approaches the end of the magazine, so that the foremost carton is offset most of all. Consequently, the edge of the foremost carton against which the feeder lug 23 will engage is isolated from the corresponding edges of the other car tons, which facilitates engagement of the feeder lugs with onlythe foremost carton C.

A movable gate 117 is provided to intercept the leading carton before it is seated on the removing feeder lug 23. The movable gate 117 is supported by a flat plate 118 (Fig. 7), which is secured in a fixed position to the wall 41 in a suitable manner, such as screws and nuts, not shown. The support plate 118 is provided with a pair of spaced ears 119 and 11% in which a shaft 120 is secured. The movable gate 117 has a vertically extending tube 121 rotatably supported on the shaft 120. Extending inwardly from the outer extremities of the tube 121 are a pair of

arms

122 and 123. The

arms

122 and 123 have hooked

end sections

124 and 125, respectively, which have flat end surfaces 126 and 127 for engaging the

grids

102 and 103. Included within the

hooked end sections

124 and 125 are

recesses

128 and 130, respectively, which receive the stripper blocks 110 and 112, respectively. Thus the gate 117 is mounted for pivotal movement on shaft 120 from the closed position of Fig. 8, with the hooked end sections of the arms disposed in contact with the grids, to the open position of Fig. 9 with the ends of the arms spaced from the grids.

The movable gate 117 is pivoted between open and closed positions in timed relation with the movement of the lugs 23, which remove the cartons C from the magazine. As shown in Fig. 7, the movable gate'117 also includes a lever arm 131, which is attached to the tube 121. The lever arm 131 is rigidly secured to a cam follower support 132, which carries a cam roller follower 133. The cam follower 133 is arranged to be engaged by a cam 134 (Fig. 8), which has a cylindrical hub 135 (Fig. 7) secured to a rotatable spindle 136. Accordingly, when the cam 134 engages the follower 133, the lever arm 132 pivots about an axis defined by the shaft 120 to open the gate 117. When the gate is open, the ends of the hooked

arms

122 and 123 are moved away from the

grids

102 and 103 to leave a passageway between the gauge plate 106 and the

grids

102 and 103 that is wide enough to accommodate only one carton. Hence, only the leading carton can be advanced by the lug 23. When the cam follower 133 disengages the cam 134, a suitable compression spring 137 disposed between the plate 118 and the arm 131 returns the movable gate 117 The compression spring 137 is secured to the plate 118 by suitable means, such as a threaded member 138.

In order to establish a timed relation between the lugs 23 and the opening of the movable gate 117, the spindle 136, which carries the earn 134, is constantly driven by a gear 139 (Fig. 6) that is keyed to the spindle 136 and is in mesh with the gear 82 which is secured to the shaft 79, which drives the

endless chains

24 and 25. The movable gate 117 is held in closed position until a lug 23 engages a carton C, as shown in Fig. 8. As the lug 23 seats the carton C, the gate 117 opens (Fig. 9) and remains open for a short period of time. Upon closing, the gate 117 engages the side face of the advancing carton C, as shown in Fig. 10, and remains in engagement therewith until the gate 117 slides 011 the trailing edge of the advancing carton. After the gate 117 slides off the side r 6 face of the advancing carton C, it again assumes its carton-intercepting position until the succeeding carton is engaged by a succeeding feeder lug 23.

The cartons C are advanced by the lugs 23 in succes sion to the

rollers

26 and 27, which receive the advancing cartons therebetween. The pair of rotatable guide rollers 26 are carried by the spindle 136 (Fig. 5), which is in constant rotation. Cooperating with the rollers 26 is the pair of rotatable guide rollers 27 (Fig. 6). Each of the guide rollers 2'7 is carried in one of a pair of forked lever arms 140. Each fork arm 140 has a pin 141 extending through spaced end portions 142 for rotatably mounting the roller 27 on the arm 140. The fork arms 140 are secured by pins 143 between spaced ears 144 (Fig. 6), which project from the

hubs

91 and 92 of the guide frame 90.

To provide variable spacing between the

rollers

26 and 27 so as to accommodate minor irregularities in the cartons being advanced, each lever arm 140 is provided with an extension 145 (Fig. 4), which bears against a suitable spring 146. The spring 146 is seated against a projection 147 extending from the guide frame 90.

The

rollers

26 and 27 carry the cartons C, initially advanced by the lugs 23, in succession toward a rotary wheel 148 (Fig. 1) of the carton opening machine 18. The wheel 148 has a plurality of carton holders 149 thereon and is rotated by a suitable drive mechanism, not shown, which drives the conveyor drive gear 82 and also serves as a source of driving power for the carton opening mechanism 18, described in the above referred to Patent No. 2,765,715 entitled Carton Opening Mechanism. Thus, the movement of the lugs 23 is not only synchronized with the opening of the movable gate 117, but also with the rotation of the adjacent carton receiving wheel 148 through the drive gears 82 and 139.

When the machine is placed in operation, each lug 23 is advanced by the

endless chains

24 and 25 to bring the beveled surface of the lug in engagement with the foremost carton in the stack which is being held in the discharge zone between the guide frame 90 and the magazine in a flattened condition against the

grids

102 and 103. While the edge of the carton slides up the beveled surface toward the seat provided by the flat surface 74 and the shoulder 75, the movable gate 117 is held in closed position, preventing the cartons from being moved laterally. When the edge of the carton is seated, the carton is moved toward the gate 117 which opens to let it pass through the passageway defined between the forward faces of the stripper blocks 112 and 113 and the

grids

102 and 103. While the carton is passing through these passageways, the gate 117 is urged toward closed position, bringing the ends of the gate arms into engagement with the side face of the advancing carton. Before the carton passes out of contact with the gate arms, it is gripped by the

rollers

26 and 27 which deliver the carton to the carton erecting mechanism so that the plane of each carton extends in a vertical direction transversely to the magazine frame 21.

It will be understood that modifications and variations of the embodiment of the invention disclosed herein may be resorted to without departing from the scope of the novel concepts of the invention.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

l. A carton feeding device comprising a magazine adapted to support a supply of upright folded cartons and having an open discharge end, a guide frame arranged transversely of the magazine in spaced relation with the discharge end of the magazine to define a discharge zone between the frame and the magazine, a conveyor having a lug adapted to engage an edge of the foremost folded carton in said supply laterally from the magazine, vacuum chambers mounted in fixed relation with said frame disposed above and below said conveyor, an adapter bridge having a passage communieating with said chambers and bridging said conveyor, and suction means communicating with said bridge passage for causing the foremost carton in said supply to be pressed flat against said guide frame in sliding engagement therewith to permit said conveyor lug to move the foremost carton completely from the magazine.

2. A carton feeding device comprising a magazine adapted to support a supply of upright folded cartons and having an open discharge end, a conveyor movable across the open discharge end of said magazine, a feeder lug on said conveyor arranged to remove the leading carton from said supply of cartons, said feeder lug having a carton engaging shoulder for abutting an edge of a carton and a surface angled away from said conveyor and toward said shoulder to contact and guide said -edge of the carton into engagement with said shoulder, a gauge plate on said magazine having oppositely extending shoulders disposed adjacent the discharge end of said magazine, and a stripper block seated on each of said shoulders, each of said stripper blocks having a surface inclined inwardly of the magazine for engaging cartons in the discharge end of said magazine and positioning the cartons in a laterally offset relationship to permit positive engagement of a carton by said lug.

3. A carton feeding device comprising a magazine having an open discharge end and adapted to support a supply of cartons, a guide member disposed in spaced relation with the discharge end of said magazine to define a discharge zone between said guide member and said magazine, a feeder lug arranged to separate the leading carton from said supply of cartons, said feeder lug including a shoulder and a surface angled away from said guide member and toward said shoulder to contact and guide said leading carton into engagement with said shoulder to enable said shoulder to advance the leading carton through said discharge zone, means connected to said magazine for offsetting the foremost carton of the supply of cartons in the direction opposite the direction of advancement of said lug as it approaches the carton, a conveyor for advancing said feeder lug through said discharge zone, means for driving said conveyor, a movable gate disposed in the path of the leading carton to be engaged thereby for seating the leading carton on said shoulder, and means coupled to said conveyor drive means and connected to said movable gate for moving said movable gate from the path of the leading carton as the leading carton is seated on said shoulder to enable said feeder lug to continue the advance of the leading carton through said discharge zone.

4. A carton feeding device comprising a magazine having an open discharge end and adapted to support a supply of cartons, a guide member disposed in spaced relation with the discharge end of said magazine to define a discharge zone between said guide member and said magazine, a conveyor having a path of travel through said discharge zone, means for driving said conveyor, a feeder lug carried by said conveyor through said discharge zone, said feeder lug including a shoulder disposed at the trailing edge thereof for seating thereon the leading carton of said supply of cartons to advance the leading carton through said discharge zone and an angularly disposed surface on the leading edge of said feeder lug to guide the leading carton toward said shoulder, a movable gate disposed in the path of the leading carton to be engaged thereby when the leading carton is guided by said angularly disposed surface, and means coupled to said conveyor drive means and connected to said movable gate for moving said movable gate from the path of the leading carton as the leading carton is seated on said shoulder to permit said feeder lug to continue the advance of the leading carton through said discharge zone.

5. A carton feeding device comprising a magazine adapted to support a generally horizontal column of upright folded cartons and having an open discharge end, a guide frame arranged transversely of the magazine in spaced relation with the discharge end of the magazine to define a discharge zone between the frame and the magazine, a conveyor having a plurality of lugs arranged to successively move the foremost carton of the column of cartons laterally from the magazine and through said discharge zone, each of said lugs having a carton engaging shoulder for abutting an edge of a carton and having a surface angled away from said conveyor and toward said shoulder to contact and guide said edge of the carton into engagement With said shoulder, a gauge plate on said magazine having oppositely extending shoulders adjacent the discharge end of said zone, and a stripper block on each of said shoulders spaced from said guide frame a distance greater than the thickness of one of the cartons but less than the thickness of two of the cartons to permit only one carton at a time to be discharged laterally from the magazine through said zone, each of said stripper blocks having a surface inclined inwardly of said magazine and away from the discharge end of said zone for engaging cartons in the discharge 'end of said magazine and positioning the cartons in a laterally offset relationship to promote positive engagement of only the foremost carton by the shoulder of one of said lugs.

References Cited in the file of this patent UNITED STATES PATENTS