Patent Abstract:
A mechanical foreign object detector upstream from the feed roll of a carding machine faithfully detects minute hard objects in the lap which could damage the lickerin or other components of the card. Spring-loaded detector pins penetrate through the lap and contact foreign objects on an apertured plate beneath the lap. Such pins rise and contact a wire connected in a stop motion circuit which immediately stops the operation of the doffer and the feed roll before any damage can occur. A visual and/or audible indicator alerts the operator to the presence of a foreign object or objects which the operator removes by hand before restarting the card by operation of a key-operated reset switch in the circuit. The mechanical detector apparatus includes a power drive which is synchronized with the operation of the feed roll of the card.

Full Description:
BACKGROUND OF THE INVENTION 
     In the past, various types of metal detectors, magnets, microswitches and eddy current devices have been utilized to protect the carding machine from damage due to foreign objects being present in the lap being fed into the card. All of these devices have fallen far short of desired goals, and the use of some of the devices installed at or under the feed roll of the card have resulted in more costly damage than they prevent. Other devices will only detect metal and will not detect nonferrous metals or other hard materials capable of damaging the card. Such materials include glass, rock, wood, plastics, leather and the like. Damage from such foreign objects can necessitate costly repairs or rebuilding of the card, as is well known. 
     The object of this invention, therefore, is to provide a foreign object detector which can detect minute objects having a thickness of as little as 0.001 inch with a lateral dimension of about 3/32 inch, regardless of the material the hard object is made of. Furthermore, the mechanical detector can act twice or more on every advancing region of the lap before the lap enters the feed roll. Individual foreign object feeler pins compactly arranged in staggered relationship in multiple rows assure that no foreign objects in the lap will escape detection. When such an object, or objects are detected by the mechanism, the doffer and feed roll will be stopped automatically and cannot be restarted by the operator until the foreign object is removed from the lap, thus assuring complete protection of the card. An indicator is included in the device to alert the operator to the presence of foreign objects and a convenient viewing panel is provided through which the operator can directly observe which feeler pin have been elevated by contact with a foreign object. 
     The operational capability of the invention in protecting the card is far in excess of any known prior art system. 
     Other features and advantages of the invention will become apparent during the course of the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic side elevation of a card equipped with a foreign object detector in accordance with the invention. 
     FIG. 2 is a fragmentary transverse vertical section through the mechanical detector device taken on line 2--2 of FIG. 1. 
     FIG. 3 is a vertical section taken on line 3--3 of FIG. 2. 
     FIG. 4 is a similar section taken on line 4--4 of FIG. 2. 
     FIG. 5 is a similar section taken on line 5--5 of FIG. 2 and showing an uncompressed lap passing through the detector mechanism. 
     FIG. 6 is a fragmentary horizontal section taken on line 6--6 of FIG. 2. 
     FIG. 7 is a view similar to FIG. 5 showing the lap compressed during operation of the detector mechanism. 
     FIG. 8 is a similar view showing the feeler or detector pins penetrating the lap with at least one such pin contacting a foreign object and being elevated thereby. 
     FIG. 9 is a fragmentary schematic view of a control circuit. 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings in detail and referring first to FIG. 1, a conventional revolving-top flat card 20 is shown having a feed roll 21, lickerin 22, card cylinder 23 and doffer 24. The foreign object detector 25 forming the subject matter of the invention is positioned in FIG. 1 just upstream from the feed roll 21 to protect the feed roll, the lickerin and the entire card from foreign object damage which would occur with costly results if an effective detector means were not present. FIG. 1 also shows the coiled lap 26 and lap roll 27 ahead of the detector 25. While a lap feeding card has been illustrated, the invention is also applicable to chute feed cards merely by altering the mode of operation of two pneumatic cylinders which coordinate the operation of the detector with the operation of the card, as will be further discussed. 
     Continuing to refer to the drawings, the detector apparatus 25 comprises bottom spaced mounting blocks 28 which rest on a solid support surface. The spacing of these blocks is sufficient to accommodate the full width of the lap 26 which measures about 40 inches on a standard size card. Such lap, before compression, FIG. 5, is about 3 inches thick and when compressed in the detector apparatus, FIG. 7, is about 1 inch thick. The blocks 28 support vertical guide posts 29 arranged in fore and aft parallel pairs, FIG. 3, in turn supporting a top plate 30 at their upper ends to which are suitably attached two vertical axis pneumatic cylinders 31 having depending piston rods 32. 
     The piston rods 32 are suitably secured to a feeler pin carriage bar 33 having guide bushings 34 therein which slidably engage the parallel posts 29. The carriage bar has a top opening cavity 35 formed therein providing a relatively thin bottom wall portion 36 on the carriage bar having plural rows of parallel equidistantly spaced apertures 37 formed therethrough across the full width of the cavity 35. As shown in FIGS. 7 and 8, preferably five equidistantly spaced parallel rows of the apertures 37 are provided in the wall portion 36 and the apertures of adjacent parallel rows are staggered laterally relative to each other, as shown in FIG. 6, to provide a rather high density of apertures and of the feeler pins 38 which are slidably mounted therein on parallel vertical axes. 
     The feeler pins 38 have heads 39 adapted to rest on the upper surface of plate portion 36 under influence of downwardly biasing springs 40 which surround reduced upper stems 41 of the feeler pins 38 and engage slidably through apertures 42 of a spring tension plate 43 suitably fixed in the cavity 35 above and parallel to the wall portion 36. 
     A lap compression plate and feeler pin cleaner 44 disposed substantially below the feeler pin carriage bar 33 in parallel relation thereto is supported by two pairs of parallel rods 45 near opposite ends thereof, such rods extending upwardly through guide bushings 46 fixed within openings of the carriage bar 33. The lap compression plate 44 is biased donwardly by lap compression springs 47 which surround the rods 45 and have their lower ends bearing on the plate 44 and their upper ends engaging the bushings 46 within spring receptor cavities 48 of carriage bar 33. 
     The top of cavity 35 is covered by a transparent cover plate 49 which enables the operator to have a clear view of the tops of the detector or feeler pins so that he can determine exactly where a detected foreign object 50 or objects, in the lap 26, is located, FIG. 8. 
     Below the lap compression plate and feeler pin cleaner 44 in parallel relationship thereto is a stationary ramp plate 51 over which the lap 26 passes, as shown in the drawings. This ramp plate has rows of apertures 52 formed therethrough which are coaxially aligned with apertures 53 of the lap compression plate and with the pointed pins 38. The ramp plate 51 is attached fixedly to the support surface on which the blocks 28 are based. 
     The apparatus further comprises an electrical grounding wire 54 lying in a horizontal plane near and above the tops of feeler pin extensions 41, FIG. 2. This wire is laced back and forth between two lacing bars 55 formed of electrical insulating material held in grooves 56 provided in the carriage bar 33. The continuous wire 54 is bodily supported on the insulating bars 55 and thus electrically isolated from the metal carriage bar 33. It comprises spaced parallel branches 57 with one such branch extending directly above and along each row of the feeler pin extensions 41. Hence, whenever one or more of the pins 38 in any row of pins rises due to contact with a foreign object 50, FIG. 8, the extension 41 or extensions will engage one of the strands or branches 57 of grounding stop motion wire 54. 
     As shown schematically in FIG. 9, the wire 54 is connected with a suitable circuit interrupter 58 forming a component of a conventional stop motion circuit 59. Whenever contact between the wire 54 and one or more of the pin extensions 51 occurs, the stop motion circuit will be broken and the operation of the card feed roll 21 and doffer 24 will be stopped. When stopped, the operator can observe through the transparent plate 49 which feeler pin or pins are elevated due to contact with an object 50 and the operator will then manually handle the lap 26 and remove the foreign object before restarting the card by utilizing a preferably key-operated reset switch in the stop motion circuit. 
     The exact configuration of the circuitry can vary considerably within the state of the art, and the details of circuitry are believed to be unimportant and unnecessary to disclose for a proper understanding of this invention. For example, the circuit may include an indicator light bulb and/or an audible signal to alert the operator to the detection of foreign objects. It may also include a burned out light bulb sensor and other state of the art components. 
     In the case of a lap feeding card 20, as shown in FIG. 1, the pneumatic cylinders 31 are single reverse-acting gravity extending cylinders. When the invention is applied to a chute feed card, the two cylinders are of the double-acting type. State of the art controls for the cylinders 31, not shown, synchronize their operation with the operation of the card. Preferably, the feeler pin carriage bar 33 reciprocates two or more times to push the pins 38 through the lap at each area of the lap spanned by the detector mechanism. Each penetration of the lap and compression thereof by the plate 44 is momentary, for about 1/10 of a second. The lap has its fibers loosely arranged and is slowly moving and therefore the repeated penetrations of the lap by the feeler pins does not effect the lap movement or the normal operation of the card. 
     Each time the carriage bar 33 descends, the compression plate 44 will compress the lap 26 to a thickness of approximately 1 inch and the springs 47 will yield to prevent further compression. The multiple pins 38 will now penetrate entirely through the lap and will enter the apertures 52 of the fixed ramp plate 51, as shown in FIG. 8. This assures detection of any foreign object at the very bottom of the lap. On the rise of the carriage bar 33 as pins 38 leave the top of the lap, they are stripped clean by the apertures 53 while the compression plate 44 is held down by the springs 47, following which the plate 44 will rise with the bar 33 and the parts ultimately return to their relative positions shown in FIGS. 2 and 5. 
     The apertures 52 of ramp plate 51 are sized to prevent passage therethrough of the smallest foreign objects 50 which are necessary to detect, namely, objects having a width measurement horizontally of about 3/32 inch. As shown in FIG. 5, the apertures 52 will also center and stabilize objects 50 on the ramp plate so that they will not escape detection by the feeler pins. The arrangement is such that the device is capable of detecting almost all potentially damaging foreign objects in the lap to protect the card and without interfering with its normal operation. 
     Other state of the art features not shown can and are preferably included in the device. Such features include a flow control valve in the pneumatic circuit of cylinders 31 to regulate the gravitational fall of carriage bar 33 when one-way pneumatic cylinders are employed with lap feed cards. A manual two position valve can also be provided to enable the operator to manually raise the carriage bar in preparation for removing foreign objects by hand from the lap after they have been detected. 
     The numerous advantages of the invention over the prior art should be readily apparent to those skilled in the art. 
     It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or scope of the subjoined claims.

Technology Classification (CPC): 3