US3407692A

US3407692A - Long ends detector

Info

Publication number: US3407692A
Application number: US362426A
Authority: US
Inventors: Jr James Henry Martin
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1964-04-24
Filing date: 1964-04-24
Publication date: 1968-10-29
Anticipated expiration: 1985-10-29
Also published as: NL6505233A

Description

CROSS REFEREE SEARCH ROOM BESQ QM A: B r

Oct. 29, w J. H. MARTIN, JR

LONG ENDS DETECTOR 3 Sheets-Sheet 1 Filed April 24, 1964 INVENTOR mobxmouh mmi asammm m m T w m A M Y R N E H? a M 9 J OR IN; B31522:

Oct. 29, 1968 j -rm, JR 3,407,692

LONG ENDS DETECTOR Filed April 24, 1964 3 Sheets-Sheet 2 40' INVENTOR JAMES HENRY MARTIN, JR.

ATTORNEY Oct. 29, 1968 J. H. MARTIN, JR 3,407,692

LONG ENDS DETECTOR Filed April 24, 1964 3 Sheets-Sheet 3 INVENTOR JAMES HENRY MARTIN, JR.

ATTORNEY United States Patent Office 3,407,692 Patented Oct. 29, 1968 3,407,692 LONG ENDS DETECTOR James Henry Martin, Jr., Waynesboro, Va., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Apr. 24, 1964, Ser. No. 362,426 2 Claims. (Cl. 83-522) ABSTRACT OF THE DISCLOSURE The presence of uncut or long ends of staple" fiber in cutters for converting continuous filaments tostaple or detected -by photoelectric recognition of long ends protruding above bundles of fiber in a staple fiber'cutter. The detection apparatus includes a light source focusing means, photocells, dust impermeable encasing to prevent fouling of operable parts of the apparatus, and accompanying electrical apparatus to visually register photocell output.

This invention relates to apparatus for the production of staple fibers of lengths suitable for conversion into yarn by conventional methods, and particularly to devices commonly known as staple fiber cutters" for converting continuous filament tow to staple.

The process of cutting tow into staple is frequently carried out with a rotating disk type of apparatus, commonly referred to as a Beria" cutter. This type of staple cutting machine comprises basically a revolving fly wheel into which tow is center fed by a tow' feed roll. Tow passes radially through the cutter fly wheel and extrudes} from the wheel circumference through a nozzle which passes a knife once per revolution. The extruded tow is cut off as it strikes the knife. Staple length is determined by the speed of the tow feed roll which speed is adjusted to give the required inches of tow feed per cutter wheel revolution.

Uniformity of the length of staple is of prime importance in the processing of staple into yarn. It is particularly important to eliminate fibers of greater than a prescribed length. These fibers are commonly called long ends. After the feed roll speed and disk speed have reached correct values, malfunction in cutting is the most common cause of the long ends. Improper cutting is most frequently due to a dull knife or to excess clearance between knife and nozzle. When defective cutting occurs, the cutting edges pinch and tear the tow rather than out it cleanly. When a filament fails to be cut after a given pass across the knife and is then cut on the subsequent pass, it becomes a double-length filament. In addition to these, three sometimes occurs malfunction in cutting which results merely in pulling out from the bundle or in stretching certain filaments a random length over-size.

Consequently, a rapid, reliable and economical method of detecting long ends is essential to the production of high-quality staple -by prompt correction of the conditions which cause malfunction of the cutter.

Several long-ends detector devices have been known in the art, but each suffers from some deficiency which may be in its method of operation, reliability, precision, or ease of maintenance. One of these employs feelers located adjacent the tow bundle extruding from the nozzle, in such a way that they may be struck by long ends and in turn cause operation of electric switches which regulate cutter operation (US. Patent 2,424,455). Another type.

of detector (U.S. Patent 3,062,081) discloses a photoelectric scanner which employs a beam of light reflected from long ends streaming out behind the end of tow extruding from the cutter nozzle. High-speed photographs, however, have shown that when long ends occur which are only 20-30% longer than the required staple length,

they protude essentially axially, and do not stream out behind the tow bundle, as they would have to in order to be detected by the device of said patent: Consequently, intermediate lengths of long ends would fail to be detected by said device.

The primary object of this invention is to provide an improved method and apparatus for detecting long ends with a high degree of precision and sensitivity.

Another object is to provide means for detection of long ends which protrude axially from a bundle of fibers while the bundle is being extruded from the nozzle of a Beria type cutter.

A further object is to provide a method and apparatus for detecting long ends with high photoelectric seaming efficiency by effecting a large light change at occurrence of long ends compared with average light received under ambient conditions. i

A still further object is to provide a long ends detector which is reliable, easily adjusted for different lengths of staple cutting, and is easily maintained.

Other objects and achievements of this invention will appear as the description proceeds.

Now, according to this invention a novel apparatus for detecting long ends is provided which is characterized particularly by comprising the following elements and mode of action:

The apparatus comprises a light source and a focusing lens which forms a beam of light converging to focus at an adjustable restricted location just off the end of the tuft of fibers extruding from the cutter nozzle (taking here, for example, a B'eria type cutter). The apparatus comprises further a solid light-pipe made of high-reflective-index material (for instance, Lucite acrylic polymer) and positioned so as to receive light reflected into its one end by the passage of a longend through said restricted location and to guide it toward the sensitive cathode of a photoelectric detector situated in proximity to the other end of the pipe. Said light pipe is of special geometrical design and, is coated with'black paint in selected portions whereby to suppress noise (reflected light from the walls of the apparatus or other undesirable locations) or to keep its effect minimal compared to the effect produced on the photoelectric detector by a passing long-end. Electronic circuitry is arranged beyond the photoelectric device to receive, amplify, and integrate said electric signal and to respond to it by v a monitoring action, such as the operation of a signal lamp or some audible warning device, the movement of a pointer on a meter, provision of a continuous data output, operation of equipment for automatically diverting the bundles which have long ends or for correcting the conditions which cause long ends, or, finally, effecting an automatic shutdown of the tow cutting machinery.

The novel apparatus contains further means whereby to shield the essential optical units against the accumulation of dust, lint or debris which are incidental to the chopping of the tow in practically any cutting apparatus. And, finally, the apparatus comprises means for testing the operative status of the entire system and for calibration of the signals.

The manner in which the invention is constituted and operates will be clear from the following detailed descriptions and associated drawings wherein FIGURE 1 is a schematic representation of the long-ends detector and a block diagram of associated circuitry. FIGURE 2 is a schematic representation of the light source, scanner, photoelectric device, and test lamp and their preferred positions relative to the cutter wheel and nozzle. FIGURE 3 is an isometric view showing a scanner position adjusting mechanism. FIGURE 4 is a plan view of the light pipe scanner. FIGURE 5 is a schematic view of an im- 3 proved testing device which may be associated with the apparatus of FIGS. 1 and 2.

In FIG. 1, the general assembly of a preferred embodiment of this invention is shown to consist of a light source 1 and a focusing system 2, a light pipe 3, and an enclosure 4 containing a photoelectric device, not shown. This assembly is shown in a location adjacent the cutter in such a way that long ends 5 are scanned as they protrude from the tuft of fibers 6 extending out of nozzle 7 as it rotates in fly wheel 8 of a Beria staple cutter. The electric signal from the photoelectric device is transmitted over cable 9 to a pre-amplifier 10, thence over line 11 to integrater 12, the output of which is sent over line 13 to a DC amplifier 14, the output from the latter being transmitted on cable 15 to a meter 17 and thence through cable 18 to a snap-circuit and power relay amplifier 19. The signal output of circuit 19 is fed through cables 20 to the long-ends indicator lamps 21 and 21 (at the extreme right end of the diagram and on top of the photoelectric housing, respectively). Supply AC power is furnished through line 22 to circuit 19 and to high voltage power supply 23. Circuit 23 furnishes the high voltage power for the photoelectric device in enclosure 4. Circuit 19 contains, in addition to the snap-circuit and power relay amplifier, a transformer and components necessary to furnish DC supply to regulating diode circuit 16 and through lines 27 to

circuits

10, 12 and 14; a low voltage AC power supply through line 28 to the light source 1; and DC power, optionally, through switch 24 over line to relaxation neon oscillator 26. A rotary switch and stepwise differing capacitors (not shown) may be included to provide light signals for calibration at varied levels of signal frequency.

With further reference to the electronic circuits indicated in FIGURE 1, the preamplifier 10 is a two-transistor amplifier of conventional design. The integrater circuit 12 is a typical circuit employing an integrating capacitor. Circuit 14 is a temperature-compensated single transistor DC amplifier. Circuit 19 is a commercially available photoelectric relay. Circuit 23 is a simple high voltage DC power supply to furnish plate voltage to the photomultiplier tube.

In FIG. 2 is shown a more detailed drawing of the light source, the scanner and the test lamp as they are arranged relative to the long ends and the tow bundle protruding from the cutter wheel. In partial section, is shown the cutter housing 30 on one side of which the mounting plate 31 for the light source and scanner assembly is placed and, on the opposite side of which, beyond the cutter wheel, the test lamp 26 is attached. Enclosure 39 is removably attached to plate 31 to shield the detection apparatus from stray light. The mounting plate 31 is adjustably fastened to the cutter housing 30 by means of bolts 34 riding in slotted holes to provide for adjustment in a direction parallel to a radius of the cutter wheel 8. This adjustment is accomplished, as shown in FIG. 3, by means of adjusting screw 35, lock nut 36 and threaded boss 37. A scale 33 is mounted on the cutter housing so that an index mark on the mounting plate 31 shows the position of adjustment of the scanner assembly.

The light pipe, as already mentioned, is of a special geometrical structure comprising an initial (light-receiving) cylindrical section 40, a central conical section 41, and a terminal (light emitting) cylindrical section 42. The bases of the two end sections (401 and 421, respectively; FIG. 4) are smooth and clear. The curved surface of the terminal cylindrical section and the greater part (circumferentially) of the central conical portion are polished off to a scratch-free, mirror finish so as to refiect inwardly any light rays which strike the walls of said composite light pipe from the inside. The curved surface of the initial cylindrical section, however, and a strip of moderate width 43 along the side of the conical portion are given a rough finish which is then overpainted with black paint. The composite whole (lightpipe or rod 3) is mounted in such a way that it does not touch any portion of the supporting metal enclosure except at the two cylindrical end portions. The large end of this light pipe is located adjacent a photoelectric sensing device 32, which, in this case, is a photomultiplier tube.

In operation, the novel arrangement of the scanner provides maximum photoelectric scanning efficiency. When a long end is produced, a large light change compared with average light under ambient conditions is impressed on the photo-tube. Referring again to FIG. 2, the filament of the light source lamp 1 and the lens 2 are so located that the distance from the filament to the lens and the distance from the lens to the scanning zone are each equal to twice the focal length of the lens, thus giving the smallest size, most accurately defined, and brightly illuminated scanning zone. The curved surface of the cylindrical section 40 of the light pipe 3 (but not its face 401) is masked with fiat black paint which wets the surface of the Lucite material. Accordingly, the effective aperture of the scanning device is the cross section of the solid tube just at the base of the masked cylindrical area 40. This section is also the beginning of the conical middle portion 41 of light pipe 3. Practically all the light entering the collector window 45 is delivered to the sensitive cathode 46 of photomultiplier tube 32. But as an effect of the masking of cylindrical section 40 and strip 43 of light pipe 3, most of the light which enters the solid tube from illuminated spot 50 is absorbed by the masked surfaces. A good signal-to-noise ratio is therefore attained. the optimum location of the black-painted absorbing strip 43 for achieving said effect can be determined in situ, simply by rotating the tube 3 on its axis.

In ordinary practice, lint, dust and fiber debris float around in the air inside the chamber which houses the cutting assembly. These tend to collect on the surfaces of focusing lens 2, diminishing its effectiveness or rendering it inoperative altogether. To prevent this, a dust shield in the form of a tube composed of parts 51 and 52 (FIG. 2) is placed around the lens, the front portion of part 51 reaching closly to the circular path of the revolving tuft 6, and having its end covered by a transparent platelet or pane 53. This arrangement keeps lint from reaching lens 2, while pane 53 itself is kept essentially clean by the drafts resulting from circulating tuft 6.

If desired, pane 53 may be replaced by a structure as shown in FIG. 5. Here, the front portion 52 of the hollow tube is filled widthwise by a column of highly transparent material 54 (such as glass or Luciteacrylic polymer), which extends from the front of tube 52 inwards to a point very near to lens 2.

Restricted aperture disks

56 and 57 on both sides of lens 2 complete the assembly.

The front end 401 of light-pipe 3 is kept clean by the same factor, it being noted that end 401 and pane 53 are close to each other and close enough to the revolving tow to be affected by its draft. This, incidentally, is one of the outstanding advantages of selecting a plastic rod-like light-pipe in lieu of the lens suggested in said U.S. Patent 3,062,081. Other advantages are the decreased number of interfaces as compared to a lens arrangement, it being remembered that each interface tends to reflect part of the incident light. Finally, the scanner rod employed in this invention collimates the desired light-signal for improved phototube response and does not have a depth-of field problem normally found with an ordinary lens systern.

All the above factors cooperate in strengthening the light-signal transmitted to the detector, and with suppression of noise by the special mode of masking above discussed, it was found in actual practice that the signal-tonoise ratio in the apparatus of this invention can be as much as 40 times better than when a lens of equal light-' gathering power is used at the surface of the cutter housing in place of the light-pipe.

By virtue of the fineness of the focusing and accurate positioning of the beam of light in the scanning area 44, the critical length at which long ends can be detected can be precisely adjusted. This positioning is done by means of the mechanism shown in FIG. 3, which along with the scale, permits setting the scanner arrangement for the minimum length of long ends that it is desired to detect.

When one or more ends pass through the illuminated section 44, a pulse of reflected light is picked up by the light pipe 3 and transmitted to the photomultiplier tu'be'which, in turn, sends electric pulses through the electric circuit arrangements which amplify, clip and integrate the pulse, and others which subsequently occur, to provide a DC voltage proportional to the amplitude, duration and frequency of the pulse signals. The accumulator capacitance of the integrater circuit and the time constant are so arranged that the output of the circuit provides for a signal essentially proportional to the number of long ends occurring per second which can, of course, be converted to long ends per gram of staple being cut.

When the detected and integrated signal current passes through cable 15, meter 17 and cable 18 of FIGURE 1 into circuit 19, the machine operators attention is attracted to the cutting machine by'one of the long-ends indicator lamps 21 and 21' if a sufiicient number of long ends per second is detected. The meter 17 gives a visual indication of the approximate number of long ends occurring per second at all times.

The relay in circuit 19 is maintained closed for 3 to 5 seconds and longer if the long ends persist. Malfunction of the cutting machine may then be corrected either automatically or manually. Shutdown of the cutting machine can be made automatic by the provision of interlocking control relays, not shown in this embodiment.

The long ends detector as described is capable of detecting and responding to signals emanating from single long end filaments; therefore, very few long ends should be produced before correction of the condition or shutdown of the machine is made, because the occurrence of long ends normally begins with the appearance of one or a very small number of filaments per revolution of the cutter wheel.

As ;a further useful feature of the apparatus of this invention, I have provided means for testing for proper all-argund operation, prior to using the detector for product 'rin purposes. Thus, by pressing switch 24 (FIG. 1), the operator introduces flashing, low level light pulses of calibrated intensity and frequency, from neon lamp 26, into the scanner pickup light pipe 3, and this causes meter 17 and long-ends indicator lamps 21 and 21' to operate. This meter signal and the response of relay circuit -19 assures proper operating conditions and calibrated output of the detector.

As a further quick testing means, the apparatus of FIG. 2 may be modified to include the auxiliary means shown in FIG. 5. An auxiliary light-pipe of high-refractive-index material and consisting of two longitudinally aligned

plastic rods

71 and 72 is positioned to intercept a portion of reflected illumination coming through column 54 and to impinge it upon the cathode 46 of photoelectric detector 32. The adjacent ends of

rods

71 and 72 are spaced apart just sufficiently to permit the edge portion of opaque disk 75 to pass between them. The disk has a light-transmitting radially disposed slit, and is mounted for rotation on an axis through its center when driven by motor 76. Wiring (not shown) connects the motor to a source of power and contains a push button or key by which the motor'may be activated. When an operator desires to test the long-end detecting apparatus, he presses the push button. If lamp 1 is functioning properly, rotation of disk 75 will cause a flash of illumination to be transmitted to cathode 46 each time the slit in the disk passes in the gap between the two

sections

71 and 72 of the light-pipe. By observing meter 17 or signal lamps 21 and 21', the operator can judge whether all the elements along the line are functioning as they should.

In view of the simple design and the fact that most of the electronic circuit elements contain solid state devices, the operation of the device is found to be reliable and easily maintained. Furthermore, since the locations of the scanner and light beam are easily adjustable, the

long-ends detector can be used to detect long ends for "ditferent lengths of staple cutting with a suflicient precision to enable the operator to quickly adjust the cutter to eliminate conditions causing long ends or to provide for automatic shutdown of the cutter should long ends condition persist. In addition, by circuitry within the common experience of a person skilled in the art, it is easily possible to provide means for continuously recording the long ends level in order to monitor the quality of productionby the cutter.

Although the invention is described in terms of a particular operating embodiment, it will be apparent that this invention can be modified in numerous respects within the skill of those engaged in this art.

I claim as my invention:

1. Apparatus for detecting long ends in the cut section of anopaque tow which has just passed through a cutting knife in an arrangement for chopping tow into tufts of staple fiber, said apparatus comprising in combination with a rotating disc type staple fiber cutter, (a) a source of light, (b) focusing means for focusing said light in a'restricted region in the path which said cut section of the tow traverses as it moves away from the cutter whereby a zone of concentrated illumination is produced in said region ready to strongly illuminate a long end passing through said region, (c) capturing means for capturing a portion of the scattered light reflected at an acute angle relative to said light source from any long end passing through said zone of concentrated illumination and for transmitting the same to a photoelectric detector, (d) electrical means for producing a monitoring action in response to actuation of said photoelectric detector, (e) first encasing means to shield said restricted region against light coming from sources other than said source of light, said capturing means being a light pipe constituted by a surface-polished, oblong, solid rod of high refractive index material, said rod extending from said photoelectric detector on the outside of said first encasing means, through an aperture in said first encasing means and up to a point in the immediate vicinity of said zone of concentrated illumination, the circumferential end portion of the said rod adjacent said zone of concentrated illumination being masked to limit the effective aperture of the said rod to the polished end face adjacent said zone, said rcd partially masked along its length to shie d it from stray light from said source of light, (f) said focusing means being surrounded by an oblong shield of dust impermeable material extending through the said first encasing means up to a point in the immediate vicinity of said zone of concentrated illumination and capped at said point with a transparent platelet whereby the tendency of dust particles and debris to sett'e upon said focusing means is diminished and (g) a second encasing means removably attached to said first encasing means to shield said light source and said photoelectric detector from stray light.

2. Apparatus for detecting long ends in the cut section of an opaque tow which has just passed through a cutting knife in an arrangement for chopping tow into tufts of staple fiber, said apparatus comprising in combination with a rotating disc type staple fiber cutter, (a) a source of light, (b) focusing means for foe-using said light in a restricted region in the path which said cut section of the tow traverses as it moves away from the cutter whereby a zone of concentrated illumination is produced in said region ready to strongly illuminate a long end passing though said region, (c) capturing means for capturing a portion of the scattered light reflected at an acute angle relative to said light source from any long end passing through said zone of concentrated illumination and for transmitting the same to a photoelectric detector, (d) electrical means for producing a monitoring action in response to actuation of said photoelectric detector, (e) first encasing means to shield said restricted region against light coming from sources other than said source of light, said capturing means being a first light pipe constituted by a surface-polished, oblong, solid rod of high refractive index material, said rod extending from said photoelectric detector on the outside of said first encasing means, through an aperture in said first encasing means and up to a point in the immediate vicinity of said zone of concentrated illumination, the circumferential end portion of the said rod adjacent said zone of concentrated illumination being masked to limit the effective aperture of the said rod to the polished end face adjacent said zone, said rod partially masked along its length to shield it from stray light from said source of light, (f) a second encasing means removably attached to said first encasing means to shield said light source and said photoelectric detector from stray light, (g) said focusing means being surrounded by an oblong shield of dust impermeable material extending through the said first encasing means up to a point in the immediate vicinity of said zone of concentrated illumination and including second light pipe means interposed between said focusing means and said zone of concentrated illumination for retarding deposition of dust on said focusing means, (h) a third light pipe made up of two longitudinally aligned solid rods of high refractive index material, said solid rods having their adjacent ends spaced apart by a gap just sufficient to permit free passage of a disc element therebetween, one of said solid rods having is free end located in said sec- 0nd light pipe means to intercept internally reflected light from the beam that emerges from said focusing means, whereby to pick up a part of said internally reflected light and transmit it along the length of said one solid rod and across said gap into the other 0 fsaid solid rods, and said other solid rod terminating in proximity to the sensitive cathode of the photoelectric detector, (i) a disc element of opaque material having a radial light-transmitting slit, said disc being disposed to cut the beam of light in the gap of said third light pipe, and (j) means for rotating said disc on a perpendicular axis through its center whereby to pass said slit periodically through said gap, whereby when said source of light is energized and said means for rotating is actuated to rotate said disc, periodic flashes of illumination will be intercepted from said second light pipe and transmitted through said third light pipe into said photoelectrc detector.

References Cited UNITED STATES PATENTS 2,810,316 10/1957 Snyder. 2,877,453 3/1959 Mendenhall. 3,069,964 12/ 1962 Simon. 3,127,464 3/ 1964 Gustavson. 3,062,081 11/1962 Bond et a1. e 83-358 X 3,065,665 11/1962 Akhtar et al. 3,163,080 12/1964 Miller 350-96 X 3,163,700 12/1964 Williamson 350--96 X 3,177,760 4/ 1965 Albert. 3,312,140 4/1967 Dokoupil 350-96 X JEWELL H. PEDERSEN, Primary Examiner.

W. A. SKLAR, Assistant Examiner.