US3350933A - Weft-detecting method and apparatus - Google Patents

Weft-detecting method and apparatus Download PDF

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Publication number
US3350933A
US3350933A US468083A US46808365A US3350933A US 3350933 A US3350933 A US 3350933A US 468083 A US468083 A US 468083A US 46808365 A US46808365 A US 46808365A US 3350933 A US3350933 A US 3350933A
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United States
Prior art keywords
web
elements
longitudinal
weft
travel
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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.)
Expired - Lifetime
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US468083A
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English (en)
Inventor
Leo J Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mount Hope Machinery Co
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Mount Hope Machinery Co
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Filing date
Publication date
Priority to NL125706D priority Critical patent/NL125706C/xx
Application filed by Mount Hope Machinery Co filed Critical Mount Hope Machinery Co
Priority to US468083A priority patent/US3350933A/en
Priority to FR54110A priority patent/FR1471765A/fr
Priority to GB12437/66A priority patent/GB1110493A/en
Priority to BE678714D priority patent/BE678714A/xx
Priority to SE6536/66A priority patent/SE302283B/xx
Priority to DE19661635257 priority patent/DE1635257B2/de
Priority to NL6608687A priority patent/NL6608687A/xx
Application granted granted Critical
Publication of US3350933A publication Critical patent/US3350933A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06H—MARKING, INSPECTING, SEAMING OR SEVERING TEXTILE MATERIALS
    • D06H3/00—Inspecting textile materials
    • D06H3/12—Detecting or automatically correcting errors in the position of weft threads in woven fabrics
    • D06H3/125—Detecting errors in the position of weft threads

Definitions

  • This invention relates to an improved method and apparatus for detecting the angular relationship of weft or lateral elements to warp or longitudinal elements of a travelling web or sheet.
  • the tension applied transversely to the web stretches the weft elements and causes the warp elements to assume lateral curvatures; the slopes of these curves relative to the general direction of web movement, measured on the axis of applied tension, indicate the angular relationship between the warp and weft elements.
  • This method requires both a means for stretching the web laterally along a tensioning axis, and a separate means for tracking and detecting the slope of the warp elements at that axis.
  • I depress a member into the web normal to its surface, to distort the web into a local three-dimensional distortion; and detect the direction, in a plane parallel to the web surface, of movement of warp elements passing directly under the depressing element.
  • the depressing is performed by a member which also tracks or senses the local direction of movement of the warp elements which it engages, since this facilitates detection of that direction.
  • a caster wheel is well suited for this purpose.
  • the depression of a local region of the web stretches the warp and weft elements in the immediate vicinity into curves whose projections on the undistorted plane of the web are convex toward the depressing member; but the warp and weft elements directly engaged by the depressing member are affected in a different fashion. If the warp and weft elements are in normal perpendicular relationship, the projections of the curves of the warp elements directly engaged by the depressing member remain rectilinear, and these warp elements continue to travel in the direction of movement of the web as a whole. However, if there is a non-perpendicular relationship or skewed condition, the warp elements directly engaged by the depressing member assume a direction of travel at an angle to the overall direction of cloth movement.
  • the cause of this phenomenon appears to be that since the points of intersection or connection between the warp and weft elements remain the same; and since the existence of a skewed condition causes the peaks of the curves in warp elements on one side of the depressing member to fall upstream or downstream relative to the peaks of the curves in warp elements on the other side; the warp elements directly engaged by the depressing member must travel at an angle to continue to be equally spaced from the adjacent differently-curved warp elements.
  • the angular direction of movement of the depressed warp elements generally differs only slightly from the overall direction of movement of the web, depending somewhat upon the depth to which the web is depressed; therefore, it is desirable to use sensitive means for detecting this angular direction.
  • other transducer means of appropriate sensitivity may also be used to sense this deviation.
  • any number of depressing members may be applied to different local regions of the web, to determine abnormalities in as many places as may be desired. Detection of the weft condition in at least two locations spaced across the centerline of the web permits discrimination between the characteristic bow and skew elements of a compound abnormality. If the weft elements are bowed from end to end, the slopes of the tracked warp elements in regions on opposite sides of the centerline will be of opposite senses with respect to the direction of web travel; whereas a skew abnormality is reflected by angular deviations of the same sense in each of these regions. In a manner similar to that described in the aforementioned patent application Ser. No.
  • the signals of two or more detectors may be combined to provide separate output signals independently indicative of bow and skew distortions.
  • a compound distortion is a combination of these two characteristic types, which are corrected independently, according to these separate output signals.
  • the output signals are produced by algebraically adding and subtracting the detector signals simultaneously; the additive output signal indicates skew abnormality, and the subtractive output signal indicates how abnormality. These signals may be applied in a well-known manner to control conventional mechanisms for correcting any particular abnormality which arises.
  • FIG. 1 is a diagrammatic representation of a travelling woven web in which the weft elements are skewed, with their ends at the right-hand edge of the web leading their ends at the left-hand edge; and showing a distortion pattern produced according to the new method of detection;
  • FIG. 2 is a view similar to FIG. 1, but showing the distortion pattern produced when the weft elements are in proper right-angular relationship to the warp elements;
  • FIG. 3 is a view similar to FIG. 1, but showing the effect produced when the weft elements are skewed with their left-hand ends leading their ends at the right-hand edge;
  • FIG. 4 is a diagrammatic representation showing means for detecting a bow distortion, which is made up essentially of a skew distortion at the left-hand edge region similar to that of FIG. 1, and a skew distortion at the right-hand edge region similar to that of FIG. 3;
  • FIG. 5 is a sectional view in elevation of a preferred form of detector apparatus according to the invention.
  • FIG. 6 is a sectional view taken along line 66 in FIG. 5, looking in the direction of the arrows;
  • FIG. 7 is a wiring diagram showing the coupling of the transducers of two detectors to provide output signals separately indicating both how and skew distortions.
  • FIGS. 8 and 9 are diagrams showing the relative phases and magnitudes of the transducer signals in the circuit of FIG. 7, and the output signals which are produced when the weft elements are skewed and bowed, respectively.
  • a travelling woven web 10 comprises warp elements 12 extending in a direction of longitudinal web movement indicated by the arrow, and transverse weft elements 14.
  • FIGS. 4 and 5 the web 10 is shown passing over guide rolls 16, 18, which form a portion of apparatus winding the web in the direction shown by the arrow, and holding it under longitudinal tension, as is common in web manufacturing and treatment processes.
  • FIGS. 1 and 3 show small portions of a web surface having a pure skew distortion
  • FIG. 2 shows a similar portion with the warp and weft elements in a normal perpendicular relationship.
  • a condition of pure bow is suggested, in which the weft elements are curved from edge to edge of the web, with their central portions leading in the illustrated case.
  • normally-occurring distortions may be compounded of both skew and bow components.
  • FIGS. 1 and 3 may alternatively be regarded, for purposes of illustration, as representing regions at the left and right of the web of FIG. 4.
  • a member 20 is depressed in a normal direction into the surface of the web, to produce a local distortion pattern such as is represented in FIGS. 1-3.
  • the direction of travel of longitudinal warp elements directly engaged by this member, relative to the overall longitudinal direction of travel of the web, is tracked or sensed, and is a measure of the angular relationship between the warp and weft elements passing that region.
  • the depressing and tracking functions are conveniently performed in common by a member 20 comprising a swivelling caster wheel, whose depression of the web from its plane of normal travel is shown in FIG. 5.
  • the optimum range of the depth of this depression can be determined experimentally, and may vary with the type of web, the longitudinal tension, the sensitivity of detection, and other factors. It should not be so great that the caster wheel is constrained to ride at all times parallel to the diretcion of web travel, by vertically stretching adjacent portions of the web so that they constrain the wheel laterally; but should on the other hand be great enough to produce a substantial distortion pattern, for otherwise the degree of angular displacement of the wheel may be too small for accurate measurement by transducers of available sensitivity.
  • the weft elements 14 and warp elements 12 are stretched into three-dimensional curves by the depression of the web, and the projections of all these curves on the plane of web travel are convex toward the caster wheel 20.
  • elements directly contacted by the caster wheel which are illustrated as a single warp element 22 and weft element 24, are not curved in this fashion. Because the points of connection between the warp and weft elements remain stable, the contacted elements 22 and 24 are equally spaced between the adjacent oppositelycurved elements, and follow an avei age path between the two.
  • the projections of the elements 22 and 24 on the plane of web travel appear as straight lines.
  • the caster wheel 20 is then aligned with the indicated direction of travel.
  • the contacted warp element 22 assumes a slight transverse curvature and passes under the caster wheel at an angle to the direction of web movement.
  • the magnitude and direction of this angle depends upon the degree and sense of the skew condition, and therefore is a measure of the skew abnormality.
  • the greatest transverse tension applied by the caster wheel occurs in the weft element 24 which it directly engages, so that the peaks of the curvatures of the warp elements to the right or left occur along this particular weft element. Since in FIG.
  • the peaks of the warp curves to the right of the caster wheel are slightly downstream of the peaks of the curves of warp elements to the left. Since the points of connection between the warp and weft elements remain the same, the engaged warp element 22 must remain equally spaced between the two adjacent non-engaged warp elements; and must therefore be pulled to the right upstream of the caster wheel, and slightly to the left downstream. A curvature is thus induced in the engaged warp element whose slope relative to the direction of web travel, measured under the caster wheel, reflects the skew condition. It will be understood that the converse situation exists in FIG. 3, where the skew leads at the left edge, and the curve of the warp element 22 is sloped to the right.
  • the measured angular positions of both caster wheels may be combined in a manner to discriminate between components of bow and skew distortion, which commonly occur together in a compound abnormality. Additional caster wheels may be applied at any point on the web surface to determine local conditions, as desired.
  • a transducer is provided to detect and signal the angular position of each caster wheel 20, and these elements are incorporated in a detector assembly, of which a preferred embodiment is shown in FIGS. 5 and 6.
  • a mounting arm 30 is provided to support the assembly with the wheel 20 depressed to a selected degree into the web, by means of transverse supports or the like (not shown). Provision for varying the depth of depression, and for lateral and longitudinal re-location, may be made if desired.
  • a base casting 32 is attached to the mounting arm by means of screws 34, and has a cover 36 to protect the interior parts. Electrical connections are made by leads 37 through the arm 30, and thence through an opening 38 and holes 40 in the base casting.
  • the caster wheel 20 is supported rotatably on an arm 42, which is pivotally mounted in the base casting by means of a shaft 44, attached to the arm by a Woodrufr' key 46.
  • the shaft 44 is supported rotatably in bearing units 48, which are in turn mounted in an annular bearing housing 50.
  • the caster wheel is thus free to swivel about an axis normal to the plane of travel of the web.
  • a shutter 52 is carried by an arm 54, received in transverse openings through the shaft and shutter, and secured in an adjusted relation by means of set screws 56.
  • the shutter block partially obscures each of a pair of photocells 58 transversely spaced in the base casting 32, and having suitable connecting leads 37 passing through the openings 40 and 38 to external means (not shown) for indicating the weft condition, and/ or controlling it.
  • a lamp 60 is mounted in the bracket 62 within the cover 36, and distributes light of variable intensity between the two photocells, depending upon the angular position of the shutter block and the connected caster wheel 20.
  • the shutter In the neutral position shown, with the wheel aligned with the direction of web travel, the shutter obscures each photocell equally; but if the wheel turns in either angular direction, an unbalanced condition results.
  • the ph-otocells are connected in a bridge circuit (FIG. 7) in a conventional manner, so that a signal is produced whose magnitude reflects angular dis placement of the caster wheel, and whose phase reflects the sense of the displacement.
  • a transducer of the photoelectric type is particularly sensitive to slight variations in the caster wheel angle, and is therefore well adapted to this application.
  • other transducer means for detecting the angle of the caster wheel, or other tracking element, and converting the measurement to a usable output signal may also be utilized.
  • a variable inductance device such as is illustrated in the aforementioned patent application Ser. No. 429,192 may be used, if it is made sufficiently sensitive.
  • the signals of two or more detector units may be combined in a manner concurrently to produce output signals indicating separately the skew and bow components of any compound distortion. This is particularly useful in the control of weft straightening devices which employ different means for correcting bow and skew components of distortion.
  • the production of concurrent signals may be performed by a circuit as shown in FIG. 7, in which the output signals of the transducers A, B of two detector assemblies are algebraically added and subtracted simultaneously.
  • the output coils 68 of the transducers form the primaries of transformers each having a pair of equivalent secondary windings 70 and 72.
  • the pair of windings 70 is connected in series-aiding relation, and provides an output voltage which represents an algebraic addition of the inputs from the individual transducers, i.e., a skew signal.
  • the pair of windings 72 are connected in series-opposing relation, and afford an output voltage which represents the algebraic difference between the transducer inputs, i.e., a bow signal.
  • FIGS. 8 and 9 Examples of the process of addition and subtraction of the transducer voltages are graphically illustrated in FIGS. 8 and 9.
  • the transducers produce no output signal.
  • Signals indicating a skewed condition are illustrated in FIG. 8, such as are produced when the caster wheels of two detector units are displaced in the same angular sense; these signal voltages are in phase with one another. Therefore, their summation provides a positive measurement of the degree of a skew condition, whose sense is indicated by the phase of the output signal.
  • the magnitudes of the two transducer signals are substantially equal and no subtractive or low signal is produced.
  • the two transducer signals are of substantially equal magnitude, but the opposite directions of angular displacement of the two caster wheels cause these signals to be relatively reversed in phase. Therefore, a summation of the signals produces a null skew signal, but the algebraic subtraction provides a signal whose amplitude measures the degree of a bow abnormality, and whose phase indicates the sense of the bow, i.e. whether the edges of the Weft elements are leading or trailing their centers.
  • the method of detecting the angular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension comprises the steps of: depressing a member into a region of the web normal to its surface to produce a local distortion pattern, and detecting the direction of travel of longitudinal elements of the web engaged by said member, relative to the longitudinal direction of travel of the web, as a measure of the undistorted relationship between transverse and longitudinal elements passing through said region.
  • the method of detecting the angular relationship between transverse and longitudinal elements of a web travelling longitudinally under tension, by means of a depressing member capable of tracking and sensing the local direction of movement of longitudinal elements engaged thereby comprises the steps of: depressing said member into the web to stretch the web normal to its surface and thereby locally distort a region of the web adjacent to said member, whereby longitudinal elements directly engaged by said member and whose local direction of movement is tracked by said member, travel in a direction determined by the angular relation between the transverse and longitudinal elements when undistorted; and detecting the direction of movement tracked by said member, as a measure of the undistorted relationship between the transverse and longitudinal elements passing through said region.
  • the method of detecting the angular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension, by means of a rotatable detector wheel supported for swivelling to track the direction of travel of relatively-moving elements engaged thereby comprises the steps off: depressing the detector Wheel into a region of the web normal to its surface to produce a local distortion pattern, and detecting the angular relation assumed by the detector wheel relative to the longitudinal direction of travel of the web, as a measure of the undistorted relationship between transverse and longitudinal web elements passing through said region.
  • the method of detecting the angular relationship between transverse and longitudinal elements of a Web which comprises the steps of: feeding the web in a longitudinal direction under tension, depressing a region of the web normal to its surface to produce a local distortion pattern, and detecting, in the depressed region, the angular relation of longitudinal elements of the web to the overall-direction of travel of the web, as a measure of the undistorted relationship between transverse and longitudinal web elements passing through said region.
  • the method of simultaneously detecting bow and skew components of an abnormal non-perpendicular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension comprises the steps of:
  • Apparatus for detecting the angular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension comprising a depressing member, means for depressing said member into a region of the web normal to its surface to produce a local distortion pattern, and means constructed and arranged for detecting the direction of travel of longitudinal elements of the web engaged by said member, relative to the longitudinal direction of travel of the web, as a measure of the undistorted relationship between transverse and longitudinal elements passing through said region.
  • Apparatus for detecting the angular relationship between transverse and longitudinal elements of a web travelling longitudinally under tension comprising a depressing member constructed and arranged for angular movement to track the local direction of movement of longitudinal elements engaged thereby; means for depressing said member into the web to stretch the web normal to its surface and thereby locally distort a region of the web adjacent to said member, whereby longitudinal elements directly engaged by said member and whose local direction of movement is tracked by said member, travel in a direction determined by the angular relation between the transverse and longitudinal elements when undistorted; and means constructed and arranged for detecting the direction of movement tracked by said member, as a measure of the undistorted relationship between the transverse and longitudinal elements passing through said region.
  • said detecting means comprises a shutter member drivingly connected with said depressing member for displacement according to the angular tracking direction assumed by said depressing member, photoelectric cell means operatively related to said shutter member for variable shading thereby according to the displacement thereof, and circuit means incorporating said photoelectric cell means for producing a signal indicative of said angular tracking direction.
  • said cell means comprises a pair of photoelectric cells constructed and arranged for unequal shading by said shutter member in positions assumed thereby when the tracking direction of said depressing member is at an angle to the direction of web travel.
  • Apparatus for detecting the angular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension comprising a caster wheel; means supporting said wheel for swivelling movement to track the local direction of travel of relativelymoving elements engaged thereby, said supporting means depressing the caster wheel into a region of the web normal to its surface to produce a local distortion pattern, and means constructed and arranged for detecting the angular relation assumed by said wheel relative to the longitudinal direction of travel of the web, as a measure of the undistorted relationship between transverse and longitudinal web elements passing through said region.
  • Apparatus for simultaneously detecting bow and skew components of an abnormal non-perpendicular relationship between transverse and longitudinal elements of a web travelling under longitudinal tension comprising: a pair of members each constructed and arranged to track a local direction of movement of longitudinal elements engaged thereby; means for depressing said tracking members into the web at two locations equally spaced on opposite sides of the centerline thereof to stretch the web normal to its surface and thereby locally distort regions of said web adjacent to said members, whereby longitudinal elements directly engaged by said members and whose local direction of movement is tracked by said members, travel in directions determined by the angular relation between the transverse and longitudinal elements when undistorted; a pair of transducers each constructed and arranged to produce a signal responsive to the angular direction of tracking of one of said sensing members, relative to the direction of web travel; and circuit means connected for simultaneously adding and substracting the algebraic values of the signals of said transducers to produce output signals independently indicating skew and bow abnormalities in the relationship between the transverse and longitudinal elements.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Textile Engineering (AREA)
  • Treatment Of Fiber Materials (AREA)
US468083A 1965-06-29 1965-06-29 Weft-detecting method and apparatus Expired - Lifetime US3350933A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
NL125706D NL125706C (es) 1965-06-29
US468083A US3350933A (en) 1965-06-29 1965-06-29 Weft-detecting method and apparatus
FR54110A FR1471765A (fr) 1965-06-29 1966-03-18 Procédé et appareil pour détecter la relation angulaire entre des éléments latéraux ou de trame et des éléments longitudinaux ou de chaîne dans une nappe mobile de tissu
GB12437/66A GB1110493A (en) 1965-06-29 1966-03-22 Weft-detecting method and apparatus
BE678714D BE678714A (es) 1965-06-29 1966-03-30
SE6536/66A SE302283B (es) 1965-06-29 1966-05-12
DE19661635257 DE1635257B2 (de) 1965-06-29 1966-06-15 Verfahren und vorrichtung zur messung des schussfadenverzuges einer unter laengsspannung in laengsrichtung bewegten gewebe bahn
NL6608687A NL6608687A (es) 1965-06-29 1966-06-22

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US468083A US3350933A (en) 1965-06-29 1965-06-29 Weft-detecting method and apparatus

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US3350933A true US3350933A (en) 1967-11-07

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US468083A Expired - Lifetime US3350933A (en) 1965-06-29 1965-06-29 Weft-detecting method and apparatus

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US (1) US3350933A (es)
BE (1) BE678714A (es)
DE (1) DE1635257B2 (es)
GB (1) GB1110493A (es)
NL (2) NL6608687A (es)
SE (1) SE302283B (es)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4378161A (en) * 1980-08-01 1983-03-29 Sw Industries, Inc. Optical sensing system for determining the angular orientation of weft threads
US4656360A (en) * 1984-10-19 1987-04-07 Sw Industries, Inc. Optical sensing system for determining the orientation of weft threads in a wide variety of fabrics
US5943746A (en) * 1997-09-15 1999-08-31 Jet Sew Technologies, Inc. Method and apparatus for weft correction

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3716579C1 (es) * 1987-05-18 1989-02-02 Mahlo Gmbh & Co Kg, 8424 Saal, De
DE102005043985B3 (de) * 2005-09-14 2006-12-07 Cts Fahrzeug-Dachsysteme Gmbh Verfahren zur Bestimmung der Spannungsverhältnisse

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2795029A (en) * 1954-06-25 1957-06-11 Robertson Co H H Skew detecting method and apparatus
CA707954A (en) * 1965-04-20 O. Gibb Robert Weft-detecting method and apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA707954A (en) * 1965-04-20 O. Gibb Robert Weft-detecting method and apparatus
US2795029A (en) * 1954-06-25 1957-06-11 Robertson Co H H Skew detecting method and apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4378161A (en) * 1980-08-01 1983-03-29 Sw Industries, Inc. Optical sensing system for determining the angular orientation of weft threads
US4656360A (en) * 1984-10-19 1987-04-07 Sw Industries, Inc. Optical sensing system for determining the orientation of weft threads in a wide variety of fabrics
US5943746A (en) * 1997-09-15 1999-08-31 Jet Sew Technologies, Inc. Method and apparatus for weft correction

Also Published As

Publication number Publication date
NL6608687A (es) 1966-12-30
BE678714A (es) 1966-09-01
SE302283B (es) 1968-07-15
GB1110493A (en) 1968-04-18
DE1635257B2 (de) 1971-12-09
DE1635257A1 (de) 1971-02-11
NL125706C (es)

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