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`BEDGEAR 1015
`IPR of U.S. Pat. No. 8,402,580
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`U.S. Patent
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`Oct. 26, 1993
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`Sheet 1 of 5
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`5,255,419
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`U.S. Patent
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`Oct. 26, 1993
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`Sheet 2 of 5
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`U.S. Patent
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`Oct. 26, 1993
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`Sheet 3 of 5
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`Sheet 4 of 5
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`U.S. Patent
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`Oct. 26, 1993
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`Sheet 5 of 5
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`5,255,419
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`1
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`TENTERING APPARATUS AND METHOD
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`BACKGROUND OF THE INVENTION
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`Laurie which provides a synchronizing shaft to me-
`chanically connect the motors for weft straightening. In
`U.S. Pat. No. 4,497,096 to Richter, both chains are
`mechanically driven in a single direction by a single
`motor at the exit end, though two motors are provided
`at the entrance end to remove slack in the tentering
`chains which occurs at the exit end, thereby avoiding
`the chattering of the tenter chains.
`During most finishing operations, the material must
`be held between the spacedrolls under extremely high
`tension to yield a product of high quality. By reason of
`such high tension, the medial portions of the rolls de-
`flect towards one another as the loop of material is
`moved in the machine direction at the speeds required
`for finishing. Thus, the circumference of the loop of
`material at the machine’s center line, i.e., near or at the.
`center of the fabric width, is less than the circumference
`at the edges of the fabric. This is particularly true where
`wide lengths of fabric are being run through the tenter--
`ing device. The result is that upon each revolution of
`the loop of material,
`the cross machine direction
`(CMD), i.e., those yarns running in the cross machine
`direction, near the machine’s center line will advance
`ahead of the CMD yams near the edges of the material.
`Thus, the material is bowed in the machine direction of
`movement. This is referred to as a leading bow of the
`warp yarn.
`One attempt to reduce or eliminate this leading bow
`has been to advance the speed of the tentering device
`with respect to the speed of the driving roll on which
`the material is held. However, doing so only affects on
`those portions of the material which are adjacent the
`edges. Thus, for wide materials, there is no compensa-
`tion for the lead bow in the center of the fabric. The
`result can be a “guIl” like appearance of the CMD yarns
`where the medial portion of the fabric has a leading
`bow flanked by lagging bows between the leading bow
`and the edges of the fabric.
`It is therefore desirable to provide a tentering appara-
`tus and method which can eliminate or reduce the lead-
`ing bow of the warp yarn without introducing a lagging
`bow or other infirmities which affect the integrity of the
`finished material. The present invention accomplishes
`these objectives, as well as several other objectives
`which will become apparent from the following.
`Another shortcoming in connection with the finish-
`ing of materials by tentering in conjunction with, for
`instance, heating, is the period of time it takes to cool
`the material. After heating a material, it is often desir-
`able to cool the material as rapidly as possible to im-
`prove. the quality and characteristics of the finished
`material. In conventional finishing machines, the tenter-
`ing device and ovens for heating are arranged closer to
`the head roll than to the tail roll, the tail roll being
`moveable depending upon the length of the material.
`Thus, there may be quite a distance between the ovens
`and the tail roll such that material moving from the
`head roll to the tail roll will cool only by exposure to
`the ambient temperature. Such cooling will occur at a
`relatively slow rate. The only options for more rapidly
`cooling material moving from the head roll to the tail
`roll using a conventional finishing machine would be to
`use external cooling apparatus. Of course, this can be
`expensive and difficult given the large size of the mate-
`rial and the structure and characteristics of finishing
`machines. The present invention addresses this short-
`coming as well.
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`The present invention relates generally to the tenter-
`ing of material, and more particularly to the tentering of
`a material which alternately and selectively moves in
`opposite directions through a tentering field.
`The tentering of materials relates to the securement
`of a material along its edges for drying and/or stretch-
`ing such material. In many cases, tentering is used to
`stretch the width of material to a predetermined width,
`maintain the width of the material, allow the width of
`the material to shrink to a predetermined width, or to
`simply prevent side to side movement of the material.
`Tentering is often accomplished in conjunction with
`other finishing processes, such as heating; and thus the
`structure and arrangement of tentering devices must
`often accommodate the practice of such additional fm-
`ishing processes. In some cases, materials can be over
`five-hundred (500) inches in width. Therefore, when
`such material is finished on a finishing machine includ-
`ing, for instance, ovens to heat the material and tenters
`to tenter the material, the tentering device must be
`arranged with respect to the lower and upper ovens so
`that the ovens can be positioned as close to the material
`on either side thereof.
`The fabrics and materials which are tentered as part
`of an overall finishing process may include papermak-
`er’s clothing and textile materials such as woven and
`non-woven fabrics. Papermaker’s clothing encompasses
`forming fabrics used by paper manufacturers to form
`the surface of paper products, wet felt-base fabrics, and
`dryer fabrics such as heavy woven fabrics. The present
`invention relates to the tentering of all such fabrics and
`materials, though it finds particular application with
`respect to the tentering of papermaker’s clothing.
`Conventional tentering devices include spaced tenter
`rails which define a tentering area therebetween. A
`tenter chain having tenter pins, grippers, clips or the
`like to secure an edge of material is carried by each
`tenter rail. The chains and pins, grippers, clips or the
`like are driven in one direction only by a single motor
`which translates the power necessary to drive the ‘
`45
`chains by mechanical means, such as gears, pulleys, etc.
`In some cases, the tenter rail includes at one end a guide
`section which is coextensive with the remaining section
`of the respective tenter rail, but is pivotally attached
`thereto. Each guide section typically carries a portion
`of the respective chain and pins, grippers, clips or the
`like in order to guide material into the tentering device
`so that the material can be moved through the tentering
`area toward the opposite end of the tentering rail. The
`material to be tentered is moved into the guide sections
`by material feeding and take-up rolls arranged at either
`end of the tentering device. In the case an endless web
`of material, the material is loaded on and between a pair
`of spaced rolls (often referred to as the head roll and tail
`roll) to form a loop which is moved by rotation of the
`rolls so that either the top flight or bottom pass of the
`material is moved through the tentering area.
`Such conventional tentering devices are shown in
`« U.S. Pat. Nos. 1,732,089 to Honeyman, Jr.; 3,264,704 to
`Prottengeier; 3,430,310 to Richbourg; 3,932,919 to Hut-
`zenlaub; and 4,639,984 to Langer. Further, in at least
`one case, individual motor drives are provided for each
`tenter rail of a tentering system for driving the chains in
`a single direction, as shown in U.S. Pat. No. 2,580,233 to
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`to tentering devices ar-
`In addition, with respect
`ranged below the bottom pass of a continuous length of
`material looped on the head roll and tail roll, there is
`little clearance between the tenter pins, grippers or clips
`and the bottom pass of material. Therefore, care must be
`taken in loading and removing the continuous length of
`material on or from the rolls. Because of the large size
`of finishing machines and the structure of the mechani-
`cal drives used to drive the tenter chains, it is difficult to
`move the head roll and tail roll system and/or the tent-
`ering system with respect to one another. Heretofore,
`lower ovens arranged below the bottom pass of material
`have been elevated into position once the material is
`loaded, and lowered after completing the heating pro-
`cess. This allows the ambient air to cool all portions of
`the material, even the portions in the area of the oven.
`As stated above, such elevation of conventional tenter-
`ing devices is not possible or at least difficult because of
`the large and intricate mechanical drives which trans-
`late the power needed to drive the tenter chains. The
`present invention also addresses this problem.
`Further, some tentering systems provide one move-
`able tenter rail so that the width between the tenter rails
`can be adjusted for materials of different widths and,
`equally important, for adjusting the cross machine ten-
`sion on material being moved through the tentering
`area. To adjust the width or tension, however, the en-
`tire moveable tenter rail must be moved such that the
`width at the first end is always equal to the width at the
`second end. While this may be acceptable for adjusting
`the system for materials of different widths, it may not
`be acceptable for adjusting the tension while material is
`moving through the tentering area. In the latter case,
`the tension on the material at the entrance of the tenter
`rails due to the sagging of the material, etc., may be less
`than the tension on the material at the exit. In any event,
`it may be desirable for other reasons to provide different
`tensions at different points on material as it is moved
`through the tentering area. The present invention also
`contemplates the introduction of different tensions on
`material moving through a tentering area, at least for a
`period of time.
`Lastly, when the power to the tenter drive motors of
`conventional tentering devices fails, or the motor itself
`malfunctions, the tentering chains carrying the pins,
`grippers, clips or the like will stop moving because of
`the mechanical connections between the chains and/or
`motor which drive the chains. However, since the head
`roll is driven by a separate drive motor, thematerial
`may continue to rotate, whereby the material may be
`damaged along its ends where it is secured by the pins,
`grippers, clips or the like. The present invention also
`provides a safety feature so that the product being tent-
`ered is not destroyed should the motor malfunction.
`SUMMARY OF THE INVENTION
`
`The present invention relates to a tentering system
`having a pair of spaced tenter rails which define a first
`end, a second end and a tentering path, moveable se-
`curement means carried by the tenter rails, first material
`guiding means at the first end of the tenter rails for
`guiding material into the tentering path from the first
`end so that the material can be moved in a first direction
`from the first end to the second end, second material
`guiding means at the second end of the tentering rails
`for guiding material into the tentering path from the
`second end so that material can be moved in a second
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`direction from the second end, and drive means for
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`alternately and selectively driving the securement
`means in the first direction and the second direction,
`whereby the first material guiding means is operative to
`guide material into the tentering path at least when the
`drive means is driving the securement means in the first
`direction, and the second material guiding means is
`operative to guide material into the tentering path at
`least when the drive means is driving the securement
`means in the second direction. The material guiding
`means are adapted to vary the width at the respective
`first and second ends so as to follow the material edges,
`and may comprise pivotally moveable material guiding
`sections.
`The present invention also relates to a tentering sys-
`tem having a pair of spaced tenter rails to define a first
`end, a second end and a tentering path, a pair of move-
`able securement means carried by the tenter rails, a first
`pair of direct drive motors at the first end of the tenter
`rails, such that there is a direct drive motor associated
`with each of the pair of securement means for driving
`the respective securement means in a second direction
`from the second end to the first end, and a second pair
`of direct drive motors at the second end of the tenter
`rails such that there is a direct drive motor associated
`with each of the pair of securement means for driving
`the respective securement means in a first direction
`from the first end to the second end, whereby the first
`pair of direct drive motors is adapted to remain idle
`while the second pair of direct drive motors are oper-
`ated to drive the securement means in the first direction,
`and the second pair of direct drive motors is adapted to
`remain idle while the first pair of direct drive motors are
`operative to drive the securement means in the second
`direction.
`In addition, the present invention relates to a tenter-
`ing system having a pair of spaced tenter rails defining
`a first end, a second end and a tentering path, moveable
`securement means carried by the tenter rails, and a first
`pair of direct drive motors at the first end of the tenter
`rails such that there is a direct drive motor associated
`with each of the pair of securement means for driving
`such securement means, each direct drive motor includ-
`ing a clutch moveable between a drive position
`whereby the respective direct drive motor drives the
`respective securement means and a neutral position
`whereby the securement means are moveable indepen-
`dently of the direct drive motors, the clutch normally
`being in the neutral position, and clutch actuating means
`for selectively and positively moving the clutch from
`the neutral position into the drive position. The clutch
`actuating means are constructed and arranged to release
`the clutch from the drive position to the neutral position
`when there is a loss of power or the direct drive motor.
`Further, the present invention relates to a tentering
`system having a pair of spaced tenter rails to define a
`first end, a second end and a tentering path, the tenter-
`ing path having a tentering width between the tenter
`rails, moveable securement means carried by the tenter
`rails, one of said tenter rails being moveable relative to
`the other tenter rail to vary the tentering width and
`maintain the desired cross machine tension on material
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`moving through the tentering area, first tension adjust-
`ing means associated with the moveable tenter rail at
`the first end for selectively adjusting the tension on
`material secured between the tenter rails at the first end,
`second tension adjusting means associated with the
`moveable tenter rail at the second end for selectively
`adjusting the tension on material secured between the
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`tenter rails at the second end, the first and second ten-
`sion adjusting means being operative independent of
`one another, and drive means associated with the se-
`curement means for driving the securement means.
`Still further, the present invention relates to a method
`of tentering material on a finishing machine which in-
`cludes a pair of spaced tenter rails defining a first end, a
`second end and a tentering path, securement means on
`each of the tenter rails, a first material roll arranged
`adjacent the first end and a second material roll ar-
`ranged adjacent the second end, the method including
`the steps of loading an endless web of material on and
`between the first and second rolls, arranging the mate-
`rial such that a portion thereof is engaged and held by
`the securement means in the tentering path, moving the
`material such that
`the engaged portion of material
`moves in a first direction from the first end to the sec-
`ond end while simultaneously driving the securement
`means in the first direction, stopping the movement of 20
`the material, and moving the material such that the
`engaged portion of material moves in a second direction
`from the second end to the first end and simultaneously
`driving the securement means in the second direction.
`Accordingly, it is an object of the present invention
`to provide a tentering device having material secure-
`ment means which,
`together with material secured
`thereby, can be moved in opposite machine directions,
`whereby a material which developed (or may develop)
`a leading bow from being run in a first machine direc-
`tion can be run in the opposite second machine direction
`to reduce or eliminate such leading bow, and whereby
`a heated material can be moved in the opposite machine
`direction to use, for instance, a steel head roll as a heat
`sink.
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`FIG. 1 is a schematical top plan representation of a
`finishing machine which includes a tentering system in
`accordance with the present invention;
`FIG. 2 is a right side elevational view of a finishing
`machine which includes a tentering system in accor-
`dance with the present invention, showing the tentering
`system and lower oven positioned substantially below
`ground level;
`FIG. 3 is atop view of the tentering system shown in
`FIG. 2;
`FIG. 4 is a front view of the tentering system shown
`in FIG. 2; and
`FIG. 5 is a partially broken away side view of a tenter
`chain motor and motor housing, as provided at each end
`of each tenter rail.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Referring to the figures, FIGS. 1 and 2 illustrate the
`primary elements of a finishing machine for the treat-'
`ment of a continuous length of material, such finishing
`machine being generally designated as 10. The finishing
`machine 10 includes a material moving system generally
`designated as 12 and a tentering system generally desig-
`nated as l4. The finishing machine 10 is particularly
`adapted to subject a length of material to a heating
`process simultaneously with the tentering process,
`though it is noted that the tentering system 14 can be
`used in connection with finishing machines of any type.
`For instance, the tentering system 14 can be used to
`facilitate the tentering of endless webs or finite lengths
`of a textile material. For the purposes of heating a mate-
`rial, a lower oven 16 is carried by frame support 18 and
`an upper oven 20 is carried by cantilever beams 22a &
`22b.
`Material moving system 12 includes a head roll 24
`and a tail roll 26 which are arranged substantially per-
`pendicular to the rails of the tentering system 14 in
`order to hold and move an endless web or loop of mate-
`rial 28 such that the bottom pass of material can pass
`between the ovens 16 & 20 and through the tentering
`area defined by the rails of the tentering system 14. In
`this regard, the head roll 24 is rotated by a motor 30,
`shown as a black box in FIG. 1. It is noted that upper
`oven 20 is supported by cantilever beams 22a and 22b so
`the material 28 can be loaded onto and between the rolls
`24 & 26 from the right side of the finishing machine 10.
`The tentering system 14, shown most clearly in
`FIGS. 2, 3 and 4, includes tenter rails 32 and 34 which
`are mounted on frame support 18. The rails 32 and 34
`are carried by cross screws 36 and 38 which enable the
`rails 32 and 34 to be moved toward and away from one
`another. Thus, the rails 32 and 34 define an adjustable
`tentering area therebetween.
`The tenter rails 32 and 34 each include pivotally
`moveable guide sections at each end, such guide sec-
`tions being provided to vary the width between the
`tenter rails 32 and 34, or to selectively and indepen-
`dently vary, at either end of the tentering system 14, the
`tension on material being moved through the tentering
`area. More specifically, tenter rail 32 includes a pivotal
`guide section 32a adjacent the tail roll 26 and pivotal
`guide section 32b adjacent the head roll 24. Similarly,
`tenter rail 24 includes guide section 34a adjacent the tail
`roll 26 and guide section 34b adjacent the head roll 24.
`In FIG. 3, the guide sections 320 and 34a are shown in
`aslightly inward pivoted position with respect to the
`remaining portions of the respective tenter rails 32 and
`
`It is another object of the present invention to pro-
`vide a tentering device having four individual direct
`drive motors for driving the chain and associated pins,
`grippers, clips or the like, one motor at each end of each
`tentering rail, such that the set of motors at one end of 40
`the tentering device remain idle while the set of motors
`at the other end of the tentering device drive the respec-
`tive chains, and vise-versa.
`It is a further object of the present invention to pro-
`vide a tentering device having guide means at either end
`thereof for guiding material into the tentering area de-
`fined by the opposing tentering rails.
`It is still a further object of the present invention to
`provide direct drive motors for driving each tentering
`chain, each direct drive motor having a clutch which
`must be positively engaged to drive the tentering
`chains, and which is adapted to release the respective
`chains to be freely moveable upon the loss of power to
`the respective motor or the failure of the respective
`motor.
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`It is another object of the present invention to pro-
`vide a tentering device which is adapted to be lowered
`and raised with respect to the rolls, and thus the mate-
`rial, of a finishing machine.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other objects, advantages, charac-
`teristics and features of the present invention will be-
`come apparent, as will a better understanding of the
`concepts underlying the present invention, with refer-
`ence to the description which follows and refers to the
`accompanying drawings in which:
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`34. In the inwardly pivoted position, the respective
`guide sections can follow the incoming material edges
`which can be more narrow than material which is al-
`ready pinned or clipped. This occurs because there is
`less tension at the entrance and the material often sags 5
`prior to being fully received in the pinning area. Al-
`though only guide sections 32a and 34a are shown in
`pivoted positions, it is preferable, though not required in
`accordance with the broad concepts underlying the
`present invention, that all guide sections be operative to 10
`follow the edges of the material 28 at either end of the
`system, regardless of the direction in which the material
`is being moved. In this manner, the system is always
`adapted to change the direction of movement of the
`material. It is further noted, however, that the guide
`sections can, depending on the particular application, be
`pivoted outwardly as well.
`‘
`.
`The pivotal movement of each guide section is actu-
`ated by independently operable pivot drives, each of
`which comprises a piston and cylinder arrangement 20
`fixed between the frame support 18 and the respective
`guide section. Thus, pivot drives 40a and 42a are ar-
`ranged to pivotally move guide sections 32a and 34a,
`respectively; and pivot drives 40b and 42b are arranged
`to drive guide sections 32b and 34b, respectively.
`The tenter rails 32 and 34 further include tenter
`chains carrying pin plates 48 which have mounted
`thereon a plurality of pins for securing the marginal
`edges of the material 28 as it is moved through the
`tentering area. As can be seen in FIG. 3, the chains, and 30
`thus the pin plates 48, extend around the periphery of
`each tenter rail, including around the respective guide
`sections of each tenter rail. Although not shown, pin
`plates 48 are provided around the entire periphery of
`each tenter rail.
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`tenter drive motor 50:: for directly driving sprocket 46a
`and tenter drive motor 50b for directly driving sprocket
`46b. It is noted that the guide sections carry the sprock-
`ets and respective tenter drive motors even when piv-
`oted by the respective pivot drives.
`FIG. 5 specifically shows the manner in which each
`individual
`tenter drive motor drives its respective
`sprocket. Thus, tenter drive motor 501:
`is shown in
`assembled position on a clutch and speed reduction
`housing 56. Within the housing 56 is the clutch 58 and
`gearing (not shown) for reducing the speed of the motor
`50b. The clutch 58 is shown in the drive-position (or
`engaged position), that is, in positive engagement with
`gear 60 which, in turn, translates the power from the
`motor 50b to the sprocket 46b. The neutral position (or
`disengaged position) of clutch 58 is shown in phantom,
`out of engagement with the gear 60. The clutch 58 is.
`normally held in the neutral position by springs (not
`shown), against which actuation means must work to
`shift the clutch into the drive position. When the clutch-
`58 is in the neutral position, the sprocket 46b, and thus
`the tenter chains associated therewith, are freely move-
`able. The actuation of the clutch 58 is preferably accom-
`plished pneumatically by means of a compressor 62, but
`can be accomplished by any other suitable means, such
`as hydraulically or electronically, for positively engag-
`ing the clutch 58 with the gear 60.
`A solenoid valve is provided to facilitate the pneu-
`matic and positive movement of the clutch 58 into the
`drive position when the respective tenter drive motor is
`energized to drive the securement means. Also pro-
`vided is a fault circuit having a fault contact which, in
`its positively closed position, permits the clutch 58 to be
`in the drive position. The fault circuit is associated not
`only with the respective tenter drive motor, but also the
`other tenter drive motors, the head roll motor, or any
`other motor or device, such that the operation of such
`motors or devices can be monitored by computer or
`otherwise. In particular, the fault circuit is adapted to
`detect any malfunction, including loss of power, of such
`motors and devices so that the fault contact can be
`automatically opened to thereby cause the solenoid
`valve to open, whereupon the clutch 58 would release
`to the neutral position.
`Thus, as indicated above, the tenter chains and pin
`plates 48 can move independently of the respective
`tenter drive motor when the clutch is in the neutral
`position. Therefore, should a given tenter drive motor
`(or any other motor or device) malfunction or power
`should be lost, the clutch will automatically release
`from its positive engagement so that material moving
`under the influence of the head roll drive will not be
`damaged at its pinned edges. Rather, the head roll drive
`or the momentum after such drive has been terminated
`will continue to move the tenter chains. This is contrary
`to what would occur with a mechanical drive system.
`With a mechanical drive system, the gearing and con-
`nections required to transmit the power from a single
`motor prevent the chains from being freely moveable.
`Such mechanical drives cannot, therefore, use a positive
`engagement feature as herein.
`It is particularly noted that the set of tenter drive
`motors adjacent the head roll, i.e., motors 50b and 54b,
`are provided to drive the bottom pass of material 28
`from the tail roll to the head roll. As those skilled in the
`art will readily appreciate, it is preferable to provide the
`drive motors at the exit end of the tenter rails. In this
`manner, the motor is used more efficiently, and the
`
`45
`
`To facilitate the pinning of the material 28 to the pins
`on the pin plates 48, pinning devices are provided at
`each end of each tenter rail. Pinning devices 440 and
`44b are shown in FIG. 2 for tenter rail 34. These pinning
`devices are conventional and, when, for instance, pneu-
`matically actuated, they force the fabric on the bottom
`pass onto the pins of the pin plates 48 so that the mar-
`ginal edges of the material 28 are secured throughout
`the tentering area. Though the pinning devices for the
`tenter rail 32 are not shown, they operate in the same
`manner. Of course, only the set of pinning devices at the
`receiving end of the tenter rails, that is, the end which
`receives the fabric and moves toward the other end,
`will be operative to pin the material 28 to the pins of the
`pin plates 48; the other set of pinning devices being
`positioned in a normally open position away from the
`material as it exits the tenter rails. For example, pinning
`device 44a (and its counterpart on rail 32) will be pneu-
`matically actuated when the bottom pass of the material
`is moving from the tail roll 26 to the head roll 24 55
`(counter clockwise rotation of the material 28); while
`the pinning device 44b (and its counterpart on rail 32)
`remain in their normally open position, as shown in
`FIG. 2.
`In addition, the tenter rails 32 and 34 include tenter 60
`drive motors at each end to facilitate the direct driving
`of the tenter chains and the pin plates 48. More specifi-
`cally, the tenter drive motors are associated with the
`sprockets at
`the respective ends of the tenter rails,
`which in turn, drive the chains. Thus, tenter rail 34 65
`includes tenter drive motor 54a for directly driving
`sprocket 52a and tenter drive motor 54b for directly
`driving sprocket 52b. Likewise, tenter rail 32 includes
`
`50
`
`000010
`
`000010
`
`

`
`9
`chains will not kink during movement. Thus, in FIG. 2,
`tenter drive motors 500 (not shown) and 54a remain idle
`(clutch in neutral mode), while tenter drive motors and
`50b (not shown) and 54b drive the loop of material 28 in
`a counterclockwise direction so that the bottom pass of
`such material moves from the tail roll to the head roll.
`It is noted once again that pinning device 44b is in its
`normally open position while pinning device 44a is in its
`pinning position to pin the material 28 to the pins on the
`plates 48 as the material 28 enters the tenter rails. Of
`course, when reversing the direction of the bottom pass
`of material 28, i.e., rotating the loop of material 28 in the
`clockwise direction as shown in FIG. 2, the tenter drive
`motors 50b and 54b would be idle while the tenter drive
`motors 50a and 54a would be operative to drive the
`chain and pin plates 48 from the head roll to the tail roll.
`Likewise, the pinning device 44b would beimoved into
`the pinning position while the pinning device 44a would
`be released to its normally open position.
`With respect to the guide sections, the guide sections
`on the selected entrance end of the tenter rails would be
`operable to guide the material 28 into the tentering area,
`that is, follow the material edges. The set of guide sec-
`tions at the selected exit end of the tenter rails are pref-
`erably energized as well to follow the material edges as
`the material exits the rails. In the alternative, the exit
`guide sections can remain coextensive with the central
`portions of the rails. However, the exit guide sections
`will not be arranged for reversing the movement of the
`material, and must be energized prior to reversing the
`material movement More specifically, when the tenter
`drive motors 50b and 54b are driving the chains from
`the tail roll to the head roll, as in FIG. 2, the guide
`sections 32a and 340, must be operable to follow the
`material edges into the tentering area, while the guide
`sections 32b and 34b are preferably operable. It is noted
`that in FIG. 3, the guide sections 320 and 340 are piv-
`oted slightly inward to accommodate a material which
`is more narrow at the entrance due to sagging. The
`guide sections can, however, be pivoted outwardly or
`inwardly depending on the material edge location.
`The frame support 18 further includes four lifting
`jacks to raise and lower the tentering system 14 and the
`lower oven 16. Such lifting jacks, generally designated
`as 64a, 64b and 66a (66b not being shown), can be of any
`conventional type capable of elevating the weight of
`the frame support 18, tentering system 14 and lower
`oven 16. As noted above, such lifting jacks enable the
`operator to lower the tentering system 14 as well as the
`lower oven 16 so that the material 28 can be removed
`from the head roll 24 and the tail roll 26 without damag-
`ing the same on the pins of the pin plates 48. It was
`heretofore difficult to employ such lifting jacks to lift
`the tentering system 14 as well as the lower oven 16
`since the tentering system 14 was extremely heavy and
`not compact as it included mechanical means for trans-
`lating power to the tenter chains.
`Referring to FIG. 3, it can be seen that the tenter rail
`34 is provided with a width adjusting motor and load
`cell at each end thereof. Each mo