US3490253A - Stop motions for warp knitting machines - Google Patents

Stop motions for warp knitting machines Download PDF

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Publication number
US3490253A
US3490253A US666065A US3490253DA US3490253A US 3490253 A US3490253 A US 3490253A US 666065 A US666065 A US 666065A US 3490253D A US3490253D A US 3490253DA US 3490253 A US3490253 A US 3490253A
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Prior art keywords
light
fabric
optical
angle
spot
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Expired - Lifetime
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US666065A
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English (en)
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Erwin Sick
Winfried Piepenbrink
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    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D51/00—Driving, starting, or stopping arrangements; Automatic stop motions
    • D03D51/18—Automatic stop motions
    • 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
    • D06H3/08—Inspecting textile materials by photo-electric or television means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8901—Optical details; Scanning details

Definitions

  • the invention relates to a warp knitting machine stop motion for the photo-electric spot scanning of knitted fabric.
  • the material on the knitting machine is inspected for defects immediately after the knitting operation, namely for the absence of a loop which would produce a gap in the knitted fabric. If this is the case, the warp knitting machine is shut down before substantial quantities of reject material are produced.
  • a known warp knitting machine stop motion this is done by means of a photo-electric scanning head which periodically traverses over the material.
  • the scanning head contains an optical illuminating system which produces a light spot on the scanned material.
  • the light which is diffusely reflected by the aforementioned light spot, is photo-electrically received.
  • a second light spot which may also be photo-electrically observed in the same manner, is produced in an adjacent position.
  • the diffusely reflected light diminishes in that light spot which just traverses the defective position while the other light spot, positioned on perfect material, is diffusely reflected in unchanged intensity.
  • An error signal is derived from the above described conditions.
  • the angles of light incidence and observation respectively in the known arrangement are extremely steep, that is to say they are at a small angle relative to the surface normal.
  • the perfect material also supplies a basic ripple in the diffusely reflected light flux, said ripple being undesirably close to a signal which occurs due to a defect, that is to say the defect signal exceeds that of the basic ripple only slightly, in particular if the defects are small.
  • the object of the invention is to provide a photoelectric warp knitting machine stop motion which will permit better differentiation between error signal and basic ripple and which is also suitable for striped or patterned fabric.
  • the knitted fabric is illuminated at a shallow angle and an error signal can be triggered by the transmitted light.
  • the prior art also discloses inspection apparatus for paper web or sheets in which the paper surface is illuminated at a shallow angle. This is done for the purpose of improving fold detection but not in order to utilise a covering effect as in the invention. In the system just described, observation takes place in the reflected light at an even smaller angle than that of the illumination.
  • FIGURE 1 is a first embodiment of the invention illustrating operation with an autocollimated optical path
  • FIGURE 2 illustrates a second embodiment using illumination from an elongated light source
  • FIGURE 3 shows a third embodiment of the invention in side elevation
  • FIGURE 4 is a path view thereof
  • FIGURES 5 and 6 illustrate modifications of the arrangement of FIGURE 1 with different reversing reflectors
  • FIGURE 7 shows an embodiment in which the light is transmitted to the photo-electric receiver by means of a light guide rod extending over the width of the knitted fabric
  • FIGURE 8 shows the transmitter and receiver part
  • FIGURE 9 shows the two scanning slides of a further embodiment of the invention, said slides being traversible over the Web to be monitored.
  • a light source 1 is provided from which a light beam is projected through an objective lens 2, said light beam falling at a shallow angle on to the knitted fabric 3 to be inspected and in whose plane it produces a light spot. If a knitting defect occurs at the location of the light spot, the light beam will pass as shown through the knitted material 3 to fall upon areflector 5 having surfaces disposed in a sawtooth pattern and being covered with .a reflecting emulsion or film. These surfaces are disposed substantially perpendicularly to the direction of the illuminating light beam so that adequate reversal reflection with low light losses is ensured despite the angle of incidence of the light.
  • the light beam is reflected into itself, condensed by the objective lens 2 and passes through a semi-reflecting mirror 6, inclined relative to the'optical path, onto a photo-electric receiver 7 where it triggers an error signal.
  • the entire unit comprising the lamp 1, the objective lens 2, the mirror 6 and the receiver 7 traverses across the knitted fabric 3 so that said fabric is scanned on a spot-by-spot basis.
  • the light strikes perfect material and neglecting dispersion and diffraction, no light will pass through the material because the individual filaments or threads conceal intermediate gaps in the direction of the light beam.
  • the gaps between the filaments cannot be seen at all.
  • the angle of light incidence must be so selected that the aforementioned covering effect occurs with perfect fabric while a gap resulting from a missing filament is seen, i.e., it permits the transmission of the light beam.
  • FIGURE 2 illustrates another method which does not involve the use of an autocollimated optical path.
  • a fluorescent tubular lamp 8 extending transversely across the material to be inspected, serves as light source.
  • the fluorescent lamp 8 has disposed in front of it a raster 8 comprising a plurality of diaphragms disposed in parallel to each other and at a shallow angle relative to the fabric 9 so that only that light which strikes at an angle will also strike the material 9.
  • Observation is by means of an objective lens 11 through which a spot and the material plane is projected on a photo-electric receiver 12 by means of a light beam extending at an angle relative to the plane of the material. If a knitting defect 10 occurs at the position of the projected spot, light will strike the receiver and trigger an error signal. In this case too, the objective lens 11 together with the receiver 12 is periodically traversed across the knitted fabric to be inspected.
  • a spot light source 13 (lamp filament) produces an illuminating beam by means of an objective lens 14, said beam once again striking the knitted fabric 15 to be monitored at a shallow angle and producing in the plane of said fabric a light spot traversing across the said knitted fabric.
  • the knitted fabric 15 is backed by a reflector 17 comprising a substantial number of concave mirrors 18.
  • the concave mirrors 18 are also disposed in sawtooth fashion, similar to the reflecting surfaces in FIGURE 1. Their optical axes are disposed substantially in one plane at the angle of incidence of the light relative to the knitted fabric 15 but are slightly twisted relative to the light incidence direction.
  • the concave mirrors 18 From the light beam passing through a knitting defect 16 the concave mirrors 18 produce a light spot upon the knitting defect 16 (FIGURE 4) but with slight lateral displacement relative to the illuminated light spot.
  • the light beam which thus passes to and fro through a knitting defect is condensed by a concave mirror 19 on a photo-electric receiver 20.
  • this optical path would be obtained only if the knitting defect 16 were disposed accurately in the plane containing the optical axis of the concave mirror 18 and being inclined at the light incidence angle relative to the knitted fabric 15 as indicated in FIGURE 3.
  • the first light spot produced by the objective lens 14 on the knitting defect 16 would not otherwise be projected by the concave mirror on the knitting defect 16 in the manner shown.
  • This difficulty is avoided by the reflector executing a pivoting motion in the scanning direction as indicated in FIGURE 3 by the double arrow.
  • the optical axis of the concave mirror will traverse at least once through the knitting defect 16 to generate a light flash on the receiver 20.
  • FIGURES 5 and 6 are modifications of the arrangement of FIGURE 1.
  • the scanning head which traverses over knitted fabric 19 or 21 respectively is constructed as indicated in FIGURE 1;
  • this embodiment provides for a series of individual optical reversing reflectors whose optical axes in each case coincide with the light incidence direction.
  • these elements are the convex lenses 20.
  • a light beam from a light source 23 is conducted at a shallow angle by means of the objective lens 24 on to the material 25 to produce a light spot thereon.
  • the scanning head with the objective lens 24 and the light source 23 is traversed in the paper plane across the knitted fabric 25.
  • a knitting defect 26 is detected the light passes through the material 25.
  • a light-conducting rod 27, provided at the top with saw-tooth light entry surfaces 28 whose surface normals coincide substantially with the light incidence direction, is disposed behind the material. The light-conducting rod conducts the transmited light to the right in FIGURE 2 where it emerges on the end face of the light-conducting rod.
  • the light-conducting rod 27 Since the light enters the light-conducting rod 27 at a defined angle, it also leaves the said light-conducting rod substantially at a defined angle (upwardly or downwardly, depending on the number of reflections) as indicated in FIGURE 7.
  • the emerging light is aligned substantially in parallel to the longitudinal axis of the light-conducting-rod 27 by means of a prism 29.
  • Thelight then strikes a concave mirror 30 in the focal point of which the photo-electric receiver 31 is disposed.
  • the apparatus may be so constructed that a pencil of light extending in parallel across the knitted fabric is produced by a stationary first optical collimator system, while an optical projection system is disposed in a first slide, traversable along the pencil light, so that the light is focused and ducted at a shallow angle upon the knitted fabric, and/ or that a second optical collimator system is disposed on asecond slide which is traversable on the other side of the knitted fabric in synchro-nism with the first slide, so that the light passing through the knitted fabric is parallelly directed upon a stationary optical condenser system. which collects the pencil of lightfor transmission to a photo-electricreceiver.
  • the active elements may be disposed stationarily and may be permanently wired at the edge of the knittted fabric to be scanned.
  • the slides contain only passive optical elements. The radiation energy is transferred without wire by the parallel light beams through the air to the moving slides and from these back to the stationary receiver.
  • the aperture of the first optical collimator system is made substantially larger than that of the optical projection system and the aperture of the aforementioned optical condenser system is constructed to be larger than that of the second optical collimator system.
  • the optical elements are appropriately so dimensioned that the ratio of light source diameter to focal length of the first optical collimator system is smaller than the ratio of the pupil diameter of the first optical collimator system, relative to the scanning width of the knitted fabric.
  • the light source which has a finite diameter, is projected by the first optical collimator system at infinity and at an angle determined by the ratio of light source diameter at focal length of the optical collimator system. If the first slide is moved away from the first optical collimator system, it being assumed that the optical projection system has at first an infinitely small aperture, so that the said optical collimator system is displayed at a progressively diminishing angle, this will result in vignetting and therefore lead to a reduction of the light flux if the optical collimator system appears at a smaller angle than the light source projected by the optical collimator at infinity (limiting distance). Light from all points of the light source will no longer pass through the pupil of the first optical collimator system to the point of observation.
  • the optical projection system may be of a spherical type. However, it is advantageous if the optical projection system is constructed from an optical cross-cylinder system.
  • the slides may be magnetically coupled to each other via the knitted fabric.
  • the light flux which passes from a stationary light source to the first slide, as well as the light flux which passes from the second slide to a stationary receiver is transmitted'in the manner described here above by means of parallel pencils of light. It is of course also advantageous if one or the other procedure is adopted by itself, so that either light passes from a stationary light source to a moving slide by virtue of the transmission of a parallel pencil of light, or only a parallel pencil of light is transmitted from the second, that is to say, receiver side slide to the stationary receiver.
  • illumination could be obtained by means of a stationary parallel pencil of light directed on to the entire knitted fabric under test, while observation is performed, spot by spot, by means of a movable slide or head. Conversely, observation could be performed by means of a light-conducting rod, given spot by spot illumination with a movable slide or, head containing an optical illumination system.
  • FIGURES 8 and 9 Such an arrangement is illustrated in FIGURES 8 and 9.
  • the light emitted by lamp 31 is displayed via a condenser 32 on a chopper disk 33 in a diaphragm 34.
  • a first optical collimator system in the form of an objective lens 35, projects the chopped light spot infinity. Projection should be of high quality. Achromatic lenses were used in a practical embodiment.
  • An optical projection system in the form of a system of crossed cylindrical lenses is disposed on a first slide 36.
  • the system of crossed cylindrical lenses comprises a cylindrical lens 37 and a cylindrical concave mirror 38, disposed at right angles thereto.
  • the concave mirror 38 ducts the light under a shallow angle on to the knitted fabric.
  • the system of crossed cylindrical lenses obtains from the relatively large and substantially parallel light beam, a small zone 40 of, for example, 10 millimetre diameter.
  • the light source (diaphragm 34) appears in the optical system 37, 38 on the slide in the form of a star, which is seen at a finite angle and is disposed at infinity.
  • the light flux remains uniform, irrespective of the position of the slide 36, relative to the optical collimator system.
  • the returning parallel pencil of light is collected by an optical condenser system 44 and transferred to a photo-electric receiver 45.
  • the numerals 46 and 47 are deflecting mirrors of the transmitter and receiver part.
  • the pencil of light 1, emerging from the second optical collimator system 43, is substantially smaller than the aperture of the optical condenser system 44. Substantially the same conditions apply as those which refer to the optical collimator system 35 and the optical projection system 37, 38.
  • the mirrors 41 and 42 and the lens 43 are disposed on a second slide 48.
  • the two slides 36 are coupled to each other via the knitted fabric, by means of magnets 49.
  • One of the two slides is traversed across the width of the web to be scanned by means of a rope drive or the like. The other is driven by the magnets.
  • a stop motion apparatus for knitted fabrics having a plurality of generally parallel threads positioned in one direction with respect to the fabric with interstices between adjacent threads wherein the apparatus has a detection device including a light source with relative motion being provided between the device and the fabric so that the area of the fabric inspected continuously changes, the improvement in said device comprising:
  • said detection means for determining when said beam passes through said fabric, said detection means having at least a portion thereof positioned along said line and on the other side of said fabric from said light directing means to intercept the beam so passing through said fabric.
  • said detection means includes:
  • said portion an autocollimation reflector, said refiector being positioned to reflect the light fromsaid other side of said fabric back along said line; and means positioned on the same side of said fabric as 7 said light directing means to intercept said reflected "light, separate it from said beam and to produce an electricalsignal-as a resultof the light so reflected.
  • said detection means includes:
  • said light directing means includes a plurality of liaphragm means positioned between the source and the fabric, positioned adjacent and parallel to each other and positioned at said angle to the fabric for restricting the .ight striking the fabric to substantially said angle
  • said light detection means includes a photoelectric dezector at the other side of the fabric and optical means between the detector and the fabric with its optical axis Jeing inclined at said angle with respect to the fabric.
  • said light detection means includes:
  • a light conducting rod extending transversely of the fabric and having, on the side thereof adjacent the fabric, a plurality of light entry surfaces arranged in sawtooth fashion, said surfaces being approximately normal to said line, said rod having a light emitting end;
  • photoelectric means positioned at said end for receiving the emitted light and producing an electrical signal in response to the receipt of emitted light.
  • said light directing means includes:
  • stationaryoptical collimator means for producing a pencil of light extending across said fabric at right angles to said direction
  • first slide means movable along said pencil of light
  • said light detection means includes: J scond slide means positioned on the-oppositeside of thefa'bric'fror'n the first slide means, '-parallel r -'to 'the first slide means and intersecting said line, said second slide means'being movable in sync'hronis'rn with' said first slide r'neans', photoelectric means, i i second optical collimator means having" atleast a portion thereof on said-second slideme'a'ns for intercepting the-light passing through the fabbric and 'dir'ectingit to said photoelectricmeans.
  • said stationary optical collimator means has an aperture of a given size
  • said means ori' said first slide'means includes optical projectionrneans having an 'aperturesm'aller than said given size
  • 'saicl second'op'tical collimator means has an aperture smaller than said given size
  • optical projection means comprises"a*system of cylindrical cross lenses.
  • said first and second slide means each includes'magnetic ineans coupling the two slide 'means for movement in synchronisrn. *T I 10. In an apparatus assetforth in claim 6, including means to periodically chop s'aid pencil'of'light.
  • SIGNED AN SEALED sea-197g SEAL

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Materials Engineering (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Knitting Machines (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
US666065A 1966-09-10 1967-09-07 Stop motions for warp knitting machines Expired - Lifetime US3490253A (en)

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Application Number Priority Date Filing Date Title
DES0105802 1966-09-10
DES0106453 1966-10-12

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US (1) US3490253A (de)
CH (1) CH491232A (de)
DE (1) DE1585349A1 (de)
FR (1) FR1538773A (de)
GB (1) GB1195897A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937038A (en) * 1972-06-15 1976-02-10 Firma Erwin Sick Optik-Elektronik Device for the continuous monitoring of the condition of the needle heads on a circular knitting machine
EP0148288A1 (de) * 1983-12-22 1985-07-17 Leglertex S.P.A. Apparat zum Feststellung von Fehlern bei der Herstellung von Kordsamt
US4701985A (en) * 1983-12-22 1987-10-27 Leglertex S.R.L. Apparatus for detecting anomalies in corduroy preparation
US4702597A (en) * 1986-03-31 1987-10-27 Milliken Research Corporation Pile lay measurement system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61221063A (ja) * 1985-03-25 1986-10-01 Kanai Gakuen 整列糸の糸切れ探知方法，および同方法に用いるフイ−ラ
BE902741A (nl) * 1985-06-26 1985-12-30 Picanol Nv Werkwijze om in een weverij een optische kontrole op de gefabriceerde weefsels uit te oefenen en kontrole-inrichting hierbij aangewend.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2859603A (en) * 1956-06-12 1958-11-11 Photobell Company Stop motion device for fabric producing machines
US3001080A (en) * 1956-01-11 1961-09-19 Special Instr Lab Inc Inspection apparatus
US3055200A (en) * 1960-08-25 1962-09-25 Meiners Carl Otto Fault finders
US3116621A (en) * 1960-09-02 1964-01-07 Fabric Res Lab Inc Fabric flaw detector

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3001080A (en) * 1956-01-11 1961-09-19 Special Instr Lab Inc Inspection apparatus
US2859603A (en) * 1956-06-12 1958-11-11 Photobell Company Stop motion device for fabric producing machines
US3055200A (en) * 1960-08-25 1962-09-25 Meiners Carl Otto Fault finders
US3116621A (en) * 1960-09-02 1964-01-07 Fabric Res Lab Inc Fabric flaw detector

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937038A (en) * 1972-06-15 1976-02-10 Firma Erwin Sick Optik-Elektronik Device for the continuous monitoring of the condition of the needle heads on a circular knitting machine
EP0148288A1 (de) * 1983-12-22 1985-07-17 Leglertex S.P.A. Apparat zum Feststellung von Fehlern bei der Herstellung von Kordsamt
US4701985A (en) * 1983-12-22 1987-10-27 Leglertex S.R.L. Apparatus for detecting anomalies in corduroy preparation
US4870727A (en) * 1983-12-22 1989-10-03 Leglertex S.R.L. Method for detecting anomalies in corduroy preparation
US4702597A (en) * 1986-03-31 1987-10-27 Milliken Research Corporation Pile lay measurement system

Also Published As

Publication number Publication date
FR1538773A (fr) 1968-09-06
DE1585349A1 (de) 1971-04-22
GB1195897A (en) 1970-06-24
DE1585348A1 (de) 1971-01-14
DE1585348B2 (de) 1975-11-20
CH491232A (de) 1970-05-31

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