CA2047942A1 - Precreasing of paper tape - Google Patents
Precreasing of paper tapeInfo
- Publication number
- CA2047942A1 CA2047942A1 CA002047942A CA2047942A CA2047942A1 CA 2047942 A1 CA2047942 A1 CA 2047942A1 CA 002047942 A CA002047942 A CA 002047942A CA 2047942 A CA2047942 A CA 2047942A CA 2047942 A1 CA2047942 A1 CA 2047942A1
- Authority
- CA
- Canada
- Prior art keywords
- paper
- strip
- advancing
- machine
- gap
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 claims description 16
- 238000004049 embossing Methods 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 abstract 1
- 238000011282 treatment Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
Landscapes
- Folding Of Thin Sheet-Like Materials, Special Discharging Devices, And Others (AREA)
Abstract
ABSTRACT In the manufacture of wallboard joint tape, the narrow paper strip, with an embossed centerline, is folded along the centerline and, while folded, advanced at speeds up to 2,000 feet/minute through a gap, about three times the doubled paper thickness, between a pair of spaced parallel rollers, then unfolded, guided laterally by relatively rigid fingers and accumulated in rolls of desired lengths. This novel precreasing results in subsequent ease of consistent, accurate folding when desired for use in taping over wallboard corner joints.
Description
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PRECREASING OF PAPER TAPE
FIELD OF THE INVE:NTION
This invention relates to a method of and apparatus for forming a crease in an elongate strip of paper tape and more particularly to precreasing a two-inch wide strip of wallboard joint tape prior to forming a roll of wallboard joint tape to be sold to an applica-tor for subsequent application over the joints oE
w,allboard.
BACKGROUND OF THE INVENTION
Rolls of wallboard joint tape have been com-monly manufactured and sold, with the rolls consisting of 75-foot lengths, 250-foot lengths or 500-foot lengths.
One method employed in preparing these rolls involves progressive steps in a machine involving, first, unrol-:: :
~ ling a web of paper of about 24-3/4-inch width from a ;~ ~ 24-3/4-inch-wide roll of paper, passing this web of paper ~. : :
between a dozen pairs of rolls wnich emboss a dozen shallow grooves along what will become the centerlines oE
a dozen narrow strips of tape. The 24-3/4-inch-wide web is then slit into a dozen narrow strips of tape, about 2-l/16 inches wide.
These dozen narrow strips of paper tape were ;~ next passed through a precreaser trough which folded each narrow web along the longitudinally centered shallow groove to an internal angle of about 40. The dozen narrow strips were next passed over a flat roll which caused the paper tape to become flat again, and they were then rolled onto a dozen individual hollow rigid cores, .
accumulating either 75 feet, 250 feet or 500 feet oE tape OlltO each core.
These doæen narrow strips of tape are severed, when the total length of tape on each core is e~ual to the length desired, the dozen rolls are then removed ~rom the machine, a dozen new hollow cores are placed in the machine, the severed end of the dozen strips coming from the flat rolls are attached to the new dozen cores, and the process of embossing gYoOVeS~ slitting, folding and flattening is repeated, accumulating a desired length o~
paper tape on the new dozen cores.
In the time between attaching the dozen strips to the dozen new cores and the final accumulation of the desired length of paper tape on the dozen new cores, the advancement of the paper accelerates from zero to about 2,000 feet/minute and subseguently decelerates to ~ero.
Wallboard joint paper tape made by the above method and the above machine has been ~ound to be lacking in the ease with which it can be subsequently folded along the centerline, accurately, prior to being adhered ~ over a wallboard interior corner joint or a wallboard ;; ~ exterior corner joint.
U.S. Patent No. 3,880,057 discloses precreasing a single strip of wallboard joint tape, including the steps of embossing a small groove along its centerline, : advancing the tape through a folding device which is an elongated rigid sheet bent along its longitudinal axis, with the degree of bend increasing from substantially zero to "a substantial infoldment at the exit end". The tightness of the fold is regulated by "adjust ~eans"
located downstream, which consists of rods which can be moved toward or away from each other along an elongated slot in the base plate. ~fter the tape passes through the adjust means, it assumes its original flat, unfolded configuration and is wound into a roll. Frequent tearing of the tape can be expected if the tape is passed between two closely spaced rods at speeds of about 2,000 feet/minute. Patent No. 3,880,057 does not disclose closely spaced rods, and no mention is made of the speed of tape travel.
SUMMARY OF T~E INVENTION
~; The present invention consists of a method and apparatus whereby the strips of paper joint tape are each passed through a respective narrow gap between a pair of rollers. In the preferred form of the inventionr a plurality of strips of paper of about two-inch widthr each having an embossed groove along the centerline, are first passed through a respective plurality of troughs to fold the paper strips to an internal angle of about 40, and are then passed through a respective plurality of pairs of rollers~which fold the paper strips to an internal angle, along the cen-terline, of substantially 0, prior to being unfolded and passed over a flat roll.
With two-inch-wide tapes of paper which has, preferably, a thickness of about 0.01 inch, the rollers of each pair are spaced apart about 0.05 to 0.06 inch.
~ith the tape folded to double thickness as it passes between the rollers, it will be seen that the gap between the rollers is about three times the thickness of the folded tape passing therebetween. This amount of excess gap has been found to be necessary -to permit the commer-cially important speeds of up to 2,00~ feet/minute, while producing a crease in the paper which provides a markedly improved ease of Eolding, accurately, as the tape is about to be adhered over a wallboard interior corner joint or a wallboard exterior corner joint.
In the preferred form of the invention, a ten-inch heavy-gauge wire finger is mounted to extend between adjacent strips of paper, particularly at a point in the travel of the paper strips after being unfolded and passed over a flat roll. These wire fingers act to maintain constant alignment of the traveling strips of paper, eliminating a tendency of the paper strips to shift laterally slight amounts which shifting results in interweaving of the edges of the strips of tape into adjacent rolls of the paper tape being accumulated on the dozen cores. Adjacent rolls of tape accu~nulated under interweaving conditions become interlocked and very difficult to separate, a condition which is avoided by the heav~-gauge wire fingers.
It is an obiect of the invention to provide a method of forming an improved crease along the centerline of each of a plurality oE narrow strips of paper in a machine employing relatively high speed advancement of the strips of paper.
It is a further object of the invention to provide a novel apparatus for precreasing elongate narrow paper tape.
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BRIEF DESCRTPTION OF THE DRAWINGS
These and other obiects and advantages of the invention will be more readily apparent when considered in relation to the preferred embodiments as set forth in the specification and shown in the drawings in which:
Fig. 1 is a schematic side view of a machine for embossing, slitting, precreasing and rewinding paper for use as wallboard joint tape, all in accordance with the invention.
Fig. 2 is a front view of the precreaser section o the machine of Fig. 1, taken along line 2-2 of Fig. 1.
Fig. 3 is a top view of one of the pairs of rollers in the precreaser section, taken along line 3-3 of Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
ReEerring to Fig. 1, there is shown a machine 10 for converting a wide, large roll 12 of paper into a plurality of~narrow strips of joint tape in relatively short lengths in the form of small rolls 19. The paper is about 0.01 inch thick, preferably about 0.0085 to 0.0095 inch thick.
Machine 10 includes a stand 16 for supporting an axle 18 extending through the center of a large roll 12 o a 24-3/4-inch-wide paper web 20. The paper web 20 is shown being unwound from roll 12, and advancing into the bottom zone 22 of the paper treatment section 24 of ; machine 10. The paper web 20 extends under a first idler roller 26 and then around a second idler roller 28.
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The paper web 20 then extends upwardly to an embossing section 30. The embossing section 30 includes a backing roll 32 and a dozen embossing wheels 34; only the end embossing wheel 34 being shown in Fig. 1. The embossing wheels 39 have a narrow outer periphery 36, about 0.04-inch wide, and are urged, by an adiustable amount of air pressure, against the paper web 20 forming an embossed groove 38 along the centerline 39 of each of what will be a dozen separate strips 40 of paper tape.
The embossed groove 38 will preferably be about 0.04-inch wide and have a depth of between about 0.00025 inch and 0.00125 inch.
The embossed paper web 20 then extends upward to a slitting section 42 which slits the paper web. The slitting section 42 includes a backing roll 44 and eleven ~ circular rotary knives 46; only the end knife 46 being ; shown in Fig. 1. The rotary knives 46 slit the paper web 20 into a dozen separate strips 40 o~ paper tape, each 2-1/16-inch wide. A small 1-1/2-inch diameter roll 48 guides the dozen strips 40 into the precreaser section 50.
The precreaser section 50 includes a dozen wedges 52 which initiate a folding of the dozen strips 40 of paper tape. From the wedges 52, the dozen folded strips 40 progress through a dozen pairs o~ precreaser rolls 54. After passing through precreaser rolls 54, the ; dozen strips revert to a flat ~nfolded form and pass over a top idlex roll 56, thence down to a prewinder idler roll 58 ln the tape roll wind-up section 60.
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The tape roll wind-up section 60 includes, in addition to the idler roll 58, the main driven shaft 62 on which a dozen hollow cores 64 are mounted, to receive the dozen paper strips 40, and thus to form a dozen small rolls 1~ of the paper strips 40. Three idler rolls 66, 68, 70 are disposed around the rolls 14 to assist in accumulating the paper strips 40 into roll form.
Means (not shown) are also provided for driving the driven shaft 62 from a zero velocity at the time new hollow cores 64 are loaded into machine 10 up to a velocity which advances the paper through machine 10 at about 2,000 feet/minute and back to zero velocity at the time the desired length o~ paper tape strips ~0 have been accumulated onto the hollow cores 64. Also, brake means (not shown) are provided on the axle 18 to maintain a consis-tent slight tension on the paper web 20 coming off the large roll I2.
: oe particular importance in the present inven-tion are the precreaser rolls 54, shown more clearly in Figs. 2 and 3. In the preferred form of the invention, the dozen pairs of precreaser rolls 54 each consist of a pair of 0.35-inch diameter shafts 72. Each shaft 72 has a square head 74 at one end and 5/16-inch threaded portion 76 at the opposite end, with a cotter pin hole 7B
near the end. Six SKF #609-2RS1 ball bearings 80, manufactured by SKF Industries Inc., having a 0.35-inch inside diameter, are stacked on each shaft 72, held in place thereon by the square head 74. The threaded portion of each shaft 72 extends through a hole 82 in an elongate steel bar 84, mounted extending across the front 2~79~
86 of the paper trea-tment section 24. A thin washer 88 is disposed between the bar 84 and each stack of bearings 80. ~ hex nut gO is threaded onto the end of the threaded portion 76 with a lock washer 92 between the nut 90 and the bar 84. A cotter pin 94 is inserted through cotter pin hole 78, and bent to prevent removal.
The two shafts 72 of each pair of precreaser rolls 54 are spaced apart 1.004 inches, center to center.
The bearings 80 have an outside diameter of 0.945 inch.
Consequently a gap 96 is formed between the rolls 54 of 0.059 inch, or approximately 0.06 inch. The approxi-mately 0.009-inch-thick paper strips 40 when folded double are approximately 0.018-inch thick, whereby the gap 96 through which the paper travel.s, sometimes at ~,000 feet/minute, is approximately three times the total paper strip thickness, or about 0.04 inch greater than the total paper strip thickness. The gap 96 can be : varied from about two times to about four times the total paper strip thickness.
The pairs of precreaser rolls 5~ as herein descrihed permit high speed advancement o the folded paper strips ~0 therethrough while developing a permanent crease along the fold line having a high degree of memory, permitting subsequent folding by users of the paper strips as wallboard joint tape on building corners, with ease of consistent and accurate folding.
With the shats 72 of each pair of precreaser rolls 54 being spaced, center to center, about 1.004 inches, and with the bearings 80 being about 0.945-inch diameter, each pair of precreaser rolls has a width of about 1.949 inches. The dozen paper strips being advanced side by side through the paper treatment section 2~ are each 2-1/16 inches widet leaving about 0.1135 inch between each adjacent pair oE precreaser rolls.
In the preferred form of the invention, a dozen wedges 52 are located below the precreaser rolls 5~.
Wedges 52 initiate a folding of the dozen paper strips 40 along centerline grooves 38, causing the paper strips 40 to fold to an internal angle of about 40. Wedges 52 consist essentially of a pair of sheet metal tabs 98 extending angularly into the path of the paper strips 40 to cause a folding oE the strips 40 along the centerline grooves 38.
Also, in the preferred form of the invention, eleven heavy-gauge, relatively rigid wire fingers 130 are affixed under one of the square heads 74 of each of ~ ~ eleven pairs of precreaser rolls 54, as shown in Fig. 2.
; Each wire finger 100 has an upper end 102 formed into an eye 104 of about 0.35-inch inside diameter for insertion of a shaft 72 therethrough, whereby the eye 102 is firmly ~; ~ held between a stack of ball bearings 80 and a square head 74.
The eleven wire fingers 100 are about 0.15-inch in diameter and about ten inches long, and are disposed, as shown in Figs 1 and 2~ between each pair of adjacent strips 40, extending downwardly and rearwardly to about two inches above the idler roll 58. Accordingly~ the wire fingers extend between the upwardly traveling strips 2 ~ 2 40, between the wedges 52, and also between the down-; wardly traveling strips 40 at a point about two inches above the idler roll 58.
The eleven wire fingers 100 engage the paper strips 90 at their side edges 106, where the paper was slit by the eleven knives 46, preventing lateral weaving ~ of the rapidly moving strips 90.
: In one modified form of the invention it is contemplated that the stack of bearings 80 on each shaft could be replaced by a single rotatable cylindrical roller mounted on suitable bearings.
It has been found that passing the paper strips 40 between the precreaser rolls 54 produces a markedly improved crease along the paper strip centerline 39, such that when the rolls 14 are sold and subsequently used, the creased tape has an improved memory, whereby folding the tape for use on corners is made much easier and more assuredly along the centerline than tape precreased with only the groove 38 and the wedges 52.
~: ~ 20 Having completed a detailed description of the ~: pre~erred embodiments of our invention so that those skilled in the art may practice the same, we contemplate that variations may be made without departing from the essence of the invention.
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PRECREASING OF PAPER TAPE
FIELD OF THE INVE:NTION
This invention relates to a method of and apparatus for forming a crease in an elongate strip of paper tape and more particularly to precreasing a two-inch wide strip of wallboard joint tape prior to forming a roll of wallboard joint tape to be sold to an applica-tor for subsequent application over the joints oE
w,allboard.
BACKGROUND OF THE INVENTION
Rolls of wallboard joint tape have been com-monly manufactured and sold, with the rolls consisting of 75-foot lengths, 250-foot lengths or 500-foot lengths.
One method employed in preparing these rolls involves progressive steps in a machine involving, first, unrol-:: :
~ ling a web of paper of about 24-3/4-inch width from a ;~ ~ 24-3/4-inch-wide roll of paper, passing this web of paper ~. : :
between a dozen pairs of rolls wnich emboss a dozen shallow grooves along what will become the centerlines oE
a dozen narrow strips of tape. The 24-3/4-inch-wide web is then slit into a dozen narrow strips of tape, about 2-l/16 inches wide.
These dozen narrow strips of paper tape were ;~ next passed through a precreaser trough which folded each narrow web along the longitudinally centered shallow groove to an internal angle of about 40. The dozen narrow strips were next passed over a flat roll which caused the paper tape to become flat again, and they were then rolled onto a dozen individual hollow rigid cores, .
accumulating either 75 feet, 250 feet or 500 feet oE tape OlltO each core.
These doæen narrow strips of tape are severed, when the total length of tape on each core is e~ual to the length desired, the dozen rolls are then removed ~rom the machine, a dozen new hollow cores are placed in the machine, the severed end of the dozen strips coming from the flat rolls are attached to the new dozen cores, and the process of embossing gYoOVeS~ slitting, folding and flattening is repeated, accumulating a desired length o~
paper tape on the new dozen cores.
In the time between attaching the dozen strips to the dozen new cores and the final accumulation of the desired length of paper tape on the dozen new cores, the advancement of the paper accelerates from zero to about 2,000 feet/minute and subseguently decelerates to ~ero.
Wallboard joint paper tape made by the above method and the above machine has been ~ound to be lacking in the ease with which it can be subsequently folded along the centerline, accurately, prior to being adhered ~ over a wallboard interior corner joint or a wallboard ;; ~ exterior corner joint.
U.S. Patent No. 3,880,057 discloses precreasing a single strip of wallboard joint tape, including the steps of embossing a small groove along its centerline, : advancing the tape through a folding device which is an elongated rigid sheet bent along its longitudinal axis, with the degree of bend increasing from substantially zero to "a substantial infoldment at the exit end". The tightness of the fold is regulated by "adjust ~eans"
located downstream, which consists of rods which can be moved toward or away from each other along an elongated slot in the base plate. ~fter the tape passes through the adjust means, it assumes its original flat, unfolded configuration and is wound into a roll. Frequent tearing of the tape can be expected if the tape is passed between two closely spaced rods at speeds of about 2,000 feet/minute. Patent No. 3,880,057 does not disclose closely spaced rods, and no mention is made of the speed of tape travel.
SUMMARY OF T~E INVENTION
~; The present invention consists of a method and apparatus whereby the strips of paper joint tape are each passed through a respective narrow gap between a pair of rollers. In the preferred form of the inventionr a plurality of strips of paper of about two-inch widthr each having an embossed groove along the centerline, are first passed through a respective plurality of troughs to fold the paper strips to an internal angle of about 40, and are then passed through a respective plurality of pairs of rollers~which fold the paper strips to an internal angle, along the cen-terline, of substantially 0, prior to being unfolded and passed over a flat roll.
With two-inch-wide tapes of paper which has, preferably, a thickness of about 0.01 inch, the rollers of each pair are spaced apart about 0.05 to 0.06 inch.
~ith the tape folded to double thickness as it passes between the rollers, it will be seen that the gap between the rollers is about three times the thickness of the folded tape passing therebetween. This amount of excess gap has been found to be necessary -to permit the commer-cially important speeds of up to 2,00~ feet/minute, while producing a crease in the paper which provides a markedly improved ease of Eolding, accurately, as the tape is about to be adhered over a wallboard interior corner joint or a wallboard exterior corner joint.
In the preferred form of the invention, a ten-inch heavy-gauge wire finger is mounted to extend between adjacent strips of paper, particularly at a point in the travel of the paper strips after being unfolded and passed over a flat roll. These wire fingers act to maintain constant alignment of the traveling strips of paper, eliminating a tendency of the paper strips to shift laterally slight amounts which shifting results in interweaving of the edges of the strips of tape into adjacent rolls of the paper tape being accumulated on the dozen cores. Adjacent rolls of tape accu~nulated under interweaving conditions become interlocked and very difficult to separate, a condition which is avoided by the heav~-gauge wire fingers.
It is an obiect of the invention to provide a method of forming an improved crease along the centerline of each of a plurality oE narrow strips of paper in a machine employing relatively high speed advancement of the strips of paper.
It is a further object of the invention to provide a novel apparatus for precreasing elongate narrow paper tape.
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BRIEF DESCRTPTION OF THE DRAWINGS
These and other obiects and advantages of the invention will be more readily apparent when considered in relation to the preferred embodiments as set forth in the specification and shown in the drawings in which:
Fig. 1 is a schematic side view of a machine for embossing, slitting, precreasing and rewinding paper for use as wallboard joint tape, all in accordance with the invention.
Fig. 2 is a front view of the precreaser section o the machine of Fig. 1, taken along line 2-2 of Fig. 1.
Fig. 3 is a top view of one of the pairs of rollers in the precreaser section, taken along line 3-3 of Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
ReEerring to Fig. 1, there is shown a machine 10 for converting a wide, large roll 12 of paper into a plurality of~narrow strips of joint tape in relatively short lengths in the form of small rolls 19. The paper is about 0.01 inch thick, preferably about 0.0085 to 0.0095 inch thick.
Machine 10 includes a stand 16 for supporting an axle 18 extending through the center of a large roll 12 o a 24-3/4-inch-wide paper web 20. The paper web 20 is shown being unwound from roll 12, and advancing into the bottom zone 22 of the paper treatment section 24 of ; machine 10. The paper web 20 extends under a first idler roller 26 and then around a second idler roller 28.
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The paper web 20 then extends upwardly to an embossing section 30. The embossing section 30 includes a backing roll 32 and a dozen embossing wheels 34; only the end embossing wheel 34 being shown in Fig. 1. The embossing wheels 39 have a narrow outer periphery 36, about 0.04-inch wide, and are urged, by an adiustable amount of air pressure, against the paper web 20 forming an embossed groove 38 along the centerline 39 of each of what will be a dozen separate strips 40 of paper tape.
The embossed groove 38 will preferably be about 0.04-inch wide and have a depth of between about 0.00025 inch and 0.00125 inch.
The embossed paper web 20 then extends upward to a slitting section 42 which slits the paper web. The slitting section 42 includes a backing roll 44 and eleven ~ circular rotary knives 46; only the end knife 46 being ; shown in Fig. 1. The rotary knives 46 slit the paper web 20 into a dozen separate strips 40 o~ paper tape, each 2-1/16-inch wide. A small 1-1/2-inch diameter roll 48 guides the dozen strips 40 into the precreaser section 50.
The precreaser section 50 includes a dozen wedges 52 which initiate a folding of the dozen strips 40 of paper tape. From the wedges 52, the dozen folded strips 40 progress through a dozen pairs o~ precreaser rolls 54. After passing through precreaser rolls 54, the ; dozen strips revert to a flat ~nfolded form and pass over a top idlex roll 56, thence down to a prewinder idler roll 58 ln the tape roll wind-up section 60.
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The tape roll wind-up section 60 includes, in addition to the idler roll 58, the main driven shaft 62 on which a dozen hollow cores 64 are mounted, to receive the dozen paper strips 40, and thus to form a dozen small rolls 1~ of the paper strips 40. Three idler rolls 66, 68, 70 are disposed around the rolls 14 to assist in accumulating the paper strips 40 into roll form.
Means (not shown) are also provided for driving the driven shaft 62 from a zero velocity at the time new hollow cores 64 are loaded into machine 10 up to a velocity which advances the paper through machine 10 at about 2,000 feet/minute and back to zero velocity at the time the desired length o~ paper tape strips ~0 have been accumulated onto the hollow cores 64. Also, brake means (not shown) are provided on the axle 18 to maintain a consis-tent slight tension on the paper web 20 coming off the large roll I2.
: oe particular importance in the present inven-tion are the precreaser rolls 54, shown more clearly in Figs. 2 and 3. In the preferred form of the invention, the dozen pairs of precreaser rolls 54 each consist of a pair of 0.35-inch diameter shafts 72. Each shaft 72 has a square head 74 at one end and 5/16-inch threaded portion 76 at the opposite end, with a cotter pin hole 7B
near the end. Six SKF #609-2RS1 ball bearings 80, manufactured by SKF Industries Inc., having a 0.35-inch inside diameter, are stacked on each shaft 72, held in place thereon by the square head 74. The threaded portion of each shaft 72 extends through a hole 82 in an elongate steel bar 84, mounted extending across the front 2~79~
86 of the paper trea-tment section 24. A thin washer 88 is disposed between the bar 84 and each stack of bearings 80. ~ hex nut gO is threaded onto the end of the threaded portion 76 with a lock washer 92 between the nut 90 and the bar 84. A cotter pin 94 is inserted through cotter pin hole 78, and bent to prevent removal.
The two shafts 72 of each pair of precreaser rolls 54 are spaced apart 1.004 inches, center to center.
The bearings 80 have an outside diameter of 0.945 inch.
Consequently a gap 96 is formed between the rolls 54 of 0.059 inch, or approximately 0.06 inch. The approxi-mately 0.009-inch-thick paper strips 40 when folded double are approximately 0.018-inch thick, whereby the gap 96 through which the paper travel.s, sometimes at ~,000 feet/minute, is approximately three times the total paper strip thickness, or about 0.04 inch greater than the total paper strip thickness. The gap 96 can be : varied from about two times to about four times the total paper strip thickness.
The pairs of precreaser rolls 5~ as herein descrihed permit high speed advancement o the folded paper strips ~0 therethrough while developing a permanent crease along the fold line having a high degree of memory, permitting subsequent folding by users of the paper strips as wallboard joint tape on building corners, with ease of consistent and accurate folding.
With the shats 72 of each pair of precreaser rolls 54 being spaced, center to center, about 1.004 inches, and with the bearings 80 being about 0.945-inch diameter, each pair of precreaser rolls has a width of about 1.949 inches. The dozen paper strips being advanced side by side through the paper treatment section 2~ are each 2-1/16 inches widet leaving about 0.1135 inch between each adjacent pair oE precreaser rolls.
In the preferred form of the invention, a dozen wedges 52 are located below the precreaser rolls 5~.
Wedges 52 initiate a folding of the dozen paper strips 40 along centerline grooves 38, causing the paper strips 40 to fold to an internal angle of about 40. Wedges 52 consist essentially of a pair of sheet metal tabs 98 extending angularly into the path of the paper strips 40 to cause a folding oE the strips 40 along the centerline grooves 38.
Also, in the preferred form of the invention, eleven heavy-gauge, relatively rigid wire fingers 130 are affixed under one of the square heads 74 of each of ~ ~ eleven pairs of precreaser rolls 54, as shown in Fig. 2.
; Each wire finger 100 has an upper end 102 formed into an eye 104 of about 0.35-inch inside diameter for insertion of a shaft 72 therethrough, whereby the eye 102 is firmly ~; ~ held between a stack of ball bearings 80 and a square head 74.
The eleven wire fingers 100 are about 0.15-inch in diameter and about ten inches long, and are disposed, as shown in Figs 1 and 2~ between each pair of adjacent strips 40, extending downwardly and rearwardly to about two inches above the idler roll 58. Accordingly~ the wire fingers extend between the upwardly traveling strips 2 ~ 2 40, between the wedges 52, and also between the down-; wardly traveling strips 40 at a point about two inches above the idler roll 58.
The eleven wire fingers 100 engage the paper strips 90 at their side edges 106, where the paper was slit by the eleven knives 46, preventing lateral weaving ~ of the rapidly moving strips 90.
: In one modified form of the invention it is contemplated that the stack of bearings 80 on each shaft could be replaced by a single rotatable cylindrical roller mounted on suitable bearings.
It has been found that passing the paper strips 40 between the precreaser rolls 54 produces a markedly improved crease along the paper strip centerline 39, such that when the rolls 14 are sold and subsequently used, the creased tape has an improved memory, whereby folding the tape for use on corners is made much easier and more assuredly along the centerline than tape precreased with only the groove 38 and the wedges 52.
~: ~ 20 Having completed a detailed description of the ~: pre~erred embodiments of our invention so that those skilled in the art may practice the same, we contemplate that variations may be made without departing from the essence of the invention.
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Claims (20)
We claim
1. The method of precreasing a narrow elongate strip of paper comprising the steps of folding a narrow elongate strip of paper along a straight longitudinally extending fold line and advancing said folded strip of paper through a narrow gap between a pair of spaced parallel rollers at a relatively high rate of speed, subsequently unfolding said strip of paper and accumulat-ing a desired length of said unfolded strip of paper in a roll form, thereby forming a permanent crease having a high degree of memory along said fold line.
2. The method of claim 1 wherein said fold line extends along a centerline of said paper strip.
3. The method of claim 1 wherein a groove is formed in said paper strip, along said fold line, prior to said folding of said paper strip.
4. The method of claim 1 wherein said folding of said paper strip is aided by advancing said paper strip between a pair of angled wedges causing said paper strip to become folded along said fold line to an internal angle of about 40° prior to the paper strip entering said narrow gap between spaced rollers.
5. The method of claim 1 wherein substantially rigid fingers are disposed between a plurality of strips of paper all of which are being simultaneously pre-creased.
6. The method of claim 1 wherein said narrow gap is about two times to about four times the thickness of said folded paper strip.
7. The method of claim 6 wherein said paper has a thickness of about 0.01 inch.
8. The method of claim 1 wherein said folded paper strip is advanced through said narrow gay at speeds of about 2,000 feet/minute.
9. The method of claim 8 wherein said paper is about 0.01-inch thick and said narrow gap is about two times to about four times the thickness of said folded paper strip.
10. The method of claim 9 wherein said fold line extends along a centerline of said paper strip and a groove is formed in said paper strip along said fold line prior to said folding of said paper strip.
11. A machine for forming a longitudinal crease in an elongate strip of paper of about 0.01-inch thick-ness comprising a pair of spaced parallel rollers having a gap therebetween of from about 0.04 to about 0.06 inches, means for advancing said 0.01-inch thick elongate strip of paper in folded form through said gap at a relatively high rate of speed and means for accumulating said precreased elongate strip of paper in unfolded roll form.
12. A machine as defined in claim 11 wherein said pair or rollers consists essentially of a pair of spaced parallel shafts, each of said shafts having a plurality of bearings rotatably mounted thereon.
13. A machine as defined in claim 11 wherein said pair of rollers consists essentially of a pair of spaced parallel shafts, each of said shafts having a single cylindrical roller rotatably mounted thereon.
14. A machine as defined in claim 11, said machine further comprising means for embossing a groove longitudinally in said strip of paper for defining a fold line prior to advancing said strip of paper through said gap.
15. A machine as defined in claim 14, further comprising means for folding said strip of paper to a form having about a 40° internal angle prior to advancing said strip of paper through said gap.
16. A machine as defined in claim 15 wherein said means for advancing said strip of paper through said gap has means for said advancing at a velocity of about 2,000 feet/minute.
17. A machine as defined in claim 11, compris-ing a plurality of pairs of spaced parallel rollers having said about .04 to about 0.06-inch gap, means for advancing a plurality of said 0.01-inch-thick strips of paper at relatively high speed, and means for accumulat-ing a plurality of said precreased strips in unfolded roll form.
18. A machine as defined in claim 17, further comprising means for supporting a large roll of a wide web of paper, means for advancing said wide web of paper to a plurality of knives, means for guiding said wide web of paper for slitting said wide web of paper with said plurality of knives, and a plurality of relatively rigid fingers disposed between adjacent precreased strips prior to being accumulated in unfolded roll form.
19. A machine as defined in claim 18, further comprising means for embossing a groove longitudinally in each said strip of paper for defining a fold line prior to advancing said strips of paper through said gaps.
20. A machine as defined in claim 19, further comprising means for folding said strip of paper to a farm having an internal angle of about 40° prior to advancing said strip of paper through said gap, and wherein said means for advancing said strip of paper through said gap has means for said advancing at a velocity of about 2,000 feet/minute.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70751191A | 1991-05-30 | 1991-05-30 | |
| US07/707,511 | 1991-05-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2047942A1 true CA2047942A1 (en) | 1992-12-01 |
Family
ID=24842005
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002047942A Abandoned CA2047942A1 (en) | 1991-05-30 | 1991-07-26 | Precreasing of paper tape |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2047942A1 (en) |
-
1991
- 1991-07-26 CA CA002047942A patent/CA2047942A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 19960126 |