Abstract:
A method and apparatus for forming a steady state stream of machine tool chips in a chip takeaway system which includes a hopper having finger-like projections which extend toward the center of the hopper at or above the level of auger means to relieve packing forces on chips beneath the projections, and a clockwise/counter-clockwise, rotate/pause method of auger operation which further reduces the tendency for chips to pack.

Description:
This invention pertains generally to providing a steady state stream of discrete, non-uniformly shaped pieces of scrap materials so as to enable the pieces to be more conveniently and efficiently processed for further use or disposal. More specifically the invention pertains to a method and apparatus for providing a steady state stream of machine tool chips which are generated at intervals, usually irregular in terms of time, from point generation sources, such as lathes, milling machines and similar tools used in industrial machining operations. 
     BACKGROUND OF THE INVENTION 
     Literally millions of tons of machine tool chips and similar scrappage is generated each year in industrial machining operations including, primarily, machine shops. A machine tool chip is an irregularly shaped product in the sense that, though it may be a uniform few thousandths of an inch thick and wide, it may be anywhere from a fraction of an inch up to several inches in length, and the contour may be anywhere from straight (in an axial sense) to any twisted shape. Such chips must be rapidly removed from the immediate vicinity of their generation point, such as a lathe or a milling machine in a stand-alone or adjunct machine shop operation, and then conveyed to a collection point at which they may be further processed as by (1) dumping, (2) compacting and then dumping at a disposal site, or (3) assembled, with or without compacting or bundling, for recycling in a downstream industrial process, such as being remelted in a steel mill after leaving the steel mill&#39;s machine shop. The variations are nearly endless but common to all installations is the problem of ensuring that the volume of chips is maintained in a flowable condition at all times so that bunching or “hanging up” does not occur. When hanging up does occur the quantity of material moving per unit of time in the takeaway system is reduced or terminated and, worse yet, jamming of the system near the generation locations may force the generation locations, such as a machine tool, to shut down due to an inability to remove the chips. The problem of jamming or hanging up in hoppers which are downstream from the generation location, such as a lathe, is particularly troublesome in connection with machine tool chips since, no matter how regularly formed the chips may be, their sharp edges, projections and recesses inevitably cause them to interlock and agglomerate whenever two chips make contact with one another. The more hoppers in a chip takeaway system, the greater the problem. 
     SUMMARY OF THE INVENTION 
     The invention is an apparatus and a method of operating it which accepts machine tool chips at a temporary collecting location, usually a surge or collection hopper, and ensures that no matter how large or how small or how variable in size the chips or bulk material may be, there will be no jamming or hanging up in the hopper, and a steady state stream of chips—which are not agglomerated in bunches too large to be efficiently processed downstream—will continuously leave the hopper. Nearly all machine tool shops have a plurality of machine tools whose generated chips are fed into a hopper, and many machine tool shops have so many machine tools that a system comprising a plurality of hoppers must be employed, each having an associated takeaway conveyor. The present invention is applicable to both types of operation; i.e.: to single hopper or multiple hopper layouts, and to any hopper location within a system, including a hopper fed directly by a machine tool or a hopper fed by one or several upstream hoppers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is illustrated more or less diagrammatically in the accompanying drawing in which: 
     FIG. 1 is a schematic view of the chip processing system as it would be essentially applied to any hopper in a single or plural hopper system; 
     FIG. 2 is an end elevation of the hopper shown in FIG. 1 with parts shown in phantom for ease of understanding; and 
     FIG. 3 is a top plan view of the hopper of FIG.  2 . 
    
    
     DESCRIPTION OF THE INVENTION 
     Like reference numerals will be used to refer to like or similar parts from Figure to Figure in the drawing. 
     A regulating hopper conveyor is indicated generally at  10  in FIG.  1 . The conveyor  10  includes an upper or feed run  11  and a return run  12  with the direction of movement of the feed run being indicated at  13 . A collecting zone, here a regulating hopper, is indicated generally at  15 , the operation of which will be described hereafter. 
     The regulating hopper conveyor  10  discharges onto what may broadly be described as a chip processing hopper conveyor indicated generally at  17  which has a feed run  18  and a return run  19 . Chip processing hopper conveyor  17  receives chips discharged from the head end  20  of the regulating hopper conveyor  10  and transfers said chips, here, up an incline  21 , to a chip processor indicated generally at  23 . In this instance the chip processor is a chip crusher having an upwardly open maw, but it will be understood that any suitable processing equipment may be used. In this instance the chips on what may be more conveniently and specifically termed a crusher conveyor  17  are discharged only by gravity over the head end  24  of the crusher conveyor  17 . 
     After processing in the processor  23  the chips are discharged onto a disposal conveyor indicated generally at  26 . Conveyor  26  has a feed run  27  which discharges the processed chips  28  over the head end  29  into a takeaway container, here a chip box indicated generally at  30 , and a return run indicated at  31 . 
     Referring now to FIGS. 2 and 3 it will be seen that the regulating hopper  15  is conventionally constructed having a front wall  34 , a rear wall  35 , a left side wall  36 , and a right side wall  37 . As can be best visualized from FIGS. 1 and 2 the front and rear walls  34  and  35  are of a generally inverted trapezoidal shape. Left wall  36  inclines inwardly toward the feed run  11  of conveyor  10  from its upper end to the open bottom of the hopper indicated at  38 . In this instance, right wall  37  inclines inwardly toward the feed run  11  of conveyor  10  at a more acute angle than does wall  36 , all as best seen in FIG.  2 . 
     A plurality of retaining projections extend from the inside surface of left and right walls  36  and  37  towards the center of the hopper  15 . In this instance one projection  40  extends from left wall  36 , and three projections,  41 ,  42 , and  43 , extend from right wall  37 . It will be noted that in this instance projection  41  is at a higher elevation relative to conveyor  10  than projections  42  and  43 . The projections may, within rather wide limits, be of a variety of cross-sections. In this instance the projections are simply round bars and this is the preferred shape. A square cross-section could also be utilized. It is preferred however that in any event the upper half of the cross-section be so shaped that machine tool chips can slide downwardly over them without hanging up—as would be the case if upturned angle irons were used. Diameters of about ½ inch have been found to be quite effective. 
     An auger is indicated generally at  45  which includes a spiral blade  46  and a shaft  47 . The auger is powered by a reversing motor  48 . From FIG. 3 it will be noted that the auger extends substantially the full length of open bottom  38  and this is the preferred mode. By suitable gearing and timers, the auger  45  rotates alternatively clockwise and counter-clockwise. 
     The use and operation of the invention is as follows. 
     When the system is powered, the regulating hopper conveyor  10 , crusher conveyor  17  and chip disposal conveyor  26  continuously operate in the direction of the arrows associated with each. Chips, such as lathe chips  50 , fall into the open upper end of regulating hopper  15  which can also be described as a collecting or surge hopper. Said chips may have slid down a chute, not shown, whose upper receiving end is arranged below the cutting head of a machine tool and whose lower discharge end is paced above and over the upper open end of surge hopper  15 . Alternatively, chips from several machine tools will feed into surge hopper  15  and this condition will be assumed. 
     In normal operation there will be periods of time when a greater weight and volume of chips will flow into surge hopper  15  than can be moved out by the auger  45 . During these periods the chips will pile up in the hopper  15  and the weight and volume of the chips together with their interlocking tendency and the tapering configuration of the hopper walls will cause the chips to pack together and become resistant to gravity flow. Once chips begin to hang up the condition quickly worsens since the effect of continuously admitting new chips to the open upper end of the hopper  15  will cause the already clogged chips to pack more tightly together. It is this condition which this invention eliminates. 
     The first aspect of the invention which contributes to the desired steady state condition is the projections  40 - 43 . The effect of each projection, and all projections taken together, is to relieve the tendency of chips to pack around the auger and form a hollow tube in which the auger rotates but does not move any chips. In other words, each projection supports a column of chips above it, thereby reducing the tendency of the chips in the supported columns from exerting a packing force on chips beneath the level of the projections. A second aspect of the invention is the provision of the projections at different levels. Here, three projections,  40 ,  42  and  43 , are at the same elevation whereas projection  41  is at an elevated position as best seen in FIG.  2 . This particular deployment may be very effective when there is a tendency for the chips to pack more densely near the rear wall  35  of the hopper  15 . By locating projection  41  a short distance upwardly relative to projections  42  and  43  the tendency of the chips to pack in the rear region can be eliminated since the modulating effect of the projection  41  is deployed at a time when the packing force of the column of chips above it has not become too pronounced. 
     A third aspect of the invention is the operation of the conveyor in a specific cycle which tends to iron out incipient tendencies for the chips to pack no matter where the projections are placed. In one embodiment having chips from lathes and which were generally 3-4 inches long (with some longer and some shorter) and having approximately a 5 to 1 reduction, the following cycle very effectively caused a steady, uniform stream of chips to be discharged through open bottom  38  of a 10′×7′ hopper  15  without the development of any hang-ups: 
     1. One rotation clockwise (towards processing conveyor  17 )—about 10 seconds 
     2. No rotation—ten minutes 
     3. Two rotations—counter clockwise about 20 seconds 
     4. No rotation—ten minutes 
     5. Repeat 1-4. 
     It will be understood however that the operating principle is the correlation of the frequency of rotation, and its direction and duration of rotation, with the physical parameters of the system; i.e.: the volume and configuration of the surge hopper  15  and the interlocking tendency of the specific chips being handled. 
     It will be understood that parameters which apply to all chip generation operations cannot be set out because of the very wide differences in each of the above described components of the system which exist in industry. Accordingly, it is intended that the above description be taken as a representation of the invention in a broad sense along with a description of a specific embodiment, and that the scope of the invention not be limited by the foregoing description but rather solely by the appended claims when interpreted in view of the relevant prior art.