US 2866538 A
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Description (OCR text may contain errors)
United States Patent CONVEYOR WEAR STRIP- Nathaniel D. Goldberg,jChicago, lll. Application June 5, 1957, Serial No. 663,751
Claims. (Cl. A198--189) 'I'his invention relates to improvements in conveyor apparatus; to a novel means whereby conveyor friction losses are kept minimal; and more particularly to a unique thermoplastic wear strip construction intended to provide a track over which conveyor structure travels with ease, reducing the drag on the conveyor drive, while wear between'the engaging parts is reduced to a minimum without Ithe use of lubricants. The strip further is characterized by a novel joint construction which accommodates strip expansion and facilitates and simplifies strip attachment to the conveyor apparatus. Y
The present invention is primarily designed and arranged for use with a generally horizontally travelling single strand endless conveyor of the type including interconnected platform sections, each of which is pivotally connected with the sections adjacent thereto and has its opposed lateral ends overlying side by side rails upon which the conveyor travels. The conveyor is particularly intended to carry food and beverage containers in single line fashion between the different stages of container sterilizing, filling, sealing and packaging. The rails are made of metal and because of the continuous travel of the conveyor sections thereon, lubricants generally are employed to lessen friction and consequently reduce wear and the load on the conveyor drive apparatus.
*In' the past, the type of lubricant generally used has `been water mixed with soap, grease or some form of alkali, any of which has a tendency to adhere to and accumulate on the containers. Moreover, care must be taken that the lubricant does not contaminate the foods or beverages being conveyed, and sterilization of the filled and sealed containers often is necessary to, remove accumulations of the lubricant vand any other foreign matter thereon.
In view of the foregoing, the present invention contemplates the provision of a novel wear strip construction for use with said conveyor and rails, whichl wear strip eliminates the use of lubricants while still maintaining friction losses at a minimum.
In its preferred embodiment, the wear strip is made from a thermoplastic material and includes a plurality of interconnected sections, each of which has a leg arranged for setting into a suitable rail aperture to facilitate wear strip mounting. Each section further at the respective ends thereof has a unique joint constructed to accommodate material expansion between sections caused by the weight of the conveyor traveling thereover. The section joints further are nestingly fitted together whereby the end of yone section is arranged to maintain the end of the ad-` fice ing additional special features; the wear strip may be em^V The foregoing and other objects, advantages and feal tures of construction will become more apparent from a consideration of the following description together with the accompanying drawing.
In the drawing:
Figure l is a perspective view of the present invention installed on a single strand conveyor; t
Figure la is a fragmentary elevation view of a portion of the conveyor shown in Figure 1;
vFigure 2 is a plan View of the wear strip sections as installed on one of the conveyor rails;
Figure 3 is an elevation view taken on line 3 3 in Figure 2;
Figure 4 is a cross-sectional elevation view taken on line 4 4 in Figure 2; v
Figure 5 is a cross-sectional view taken on line 5--5 in Figure 4; and i Figure 6 is a cross-sectional view taken on line 6-'6 in Figure 4. v
Referring to the drawings, one type of conveyor apparatus with which the present invention may be employed includes an endless carrier 11 comprising a plurality of connected sections 12. Each `section 12 includes a flat tray portion 13 adapted to carry containers C thereon, and linkage structure 14 including paired lobes 15 and 16. The lobes 15 are separated by a distance less than that separating the lobes 16, whereby the lobes 15 of one section nestingly lit between the lobes 16 of the conveyor section adjacent thereto, while adjacent Isections 12 are pivotally connected by means of an appropriate pin 17 passing through the nestingly arranged lobes 15, 16. The tray portion 13 of each section 12 extends laterally beyond the linkage structure 14 and is adapted to ride over spaced parallel extending rails 18'-18, while the linkage structure is dependingly carried therebetween. The rails 18-18 may be provided as part of the conveyor frame 19 which is supported by legs 20 suitably attached thereto. Guides 21-21 may be provided on the frame at each side of the path of carrier travel to prevent the containers from falling. i y
As seen in Figure l, the wear strips 22--22 of the present invention are mounted atop the rails 18-18 `so that the bottom surface of said trayportions 13 slides thereover. Each wear strip 22 includes a plurality of connected track sections 23, each of which preferably is approximately one foot in length, for reasons hereinafter more fully explained.
Each track section 23, in plan, is generally rectangular in shape and includes at one end thereof an open end cutout portion 24, also generally rectangular in shape, which cut-out 24 together with the extensions 2 5- 25 at either side thereof serves as the female portion of a connecting joint 26 between adjacent track sections. At its other end, each track section 23 has a male connector prong 27 extending longitudinally therefrom and providing the other half of the connecting joint 26.
As best seen in Figure 5, the opposed faces of the extensions 25-25 are directed downwardly and divergingly from each other. Correspondingly, the opposite faces of the prong 27 are directed downwardly and divergingly from each other, whereby the end of a track section Patented Dec. 3o, 195sv need ntbe planar and that theiniportant` feature is"`,tl1'at the surfaces va'recso arranged as 'tof maintain"prong,27 fomrising` 'I'heen'gagernentfof aprongf27within a cut-out portion 24'is` such, however, yas to permit rela#y tive longitudinal `sliding movement between the extensions 2S--25and the 'prong `27 `therebetween, ,for reasons more fully explainedhereinafterl Spaced'preferably approximately oneinch from the end wall 28"`of each cutfoutfportion-Zi,eachtrack,section 23 has dependinglymountedfrom it`s"bottom surface a.` fastener in the,form]ofia generally,cylindrical'protrusion 29V providedwith an annular'shoulder 3-0. Each protrusion 29 adaptedl` to' pass through an opening 31' drilled in the frame rail 18' and'to` receivethere'on `a Timmerman nut 32 which maintains the respectivesection 23 mounted atop the rail 18. With the endt'of the section 23 whereat the protrusion 2`9vand cut-out portion 24V are located firmly mounted'atop'` th'e rail 18, it wilLbe evident that the extensions p25-25 also thereat are'able to maintain thepronged` end of the section` adjacent thereto in position against risi1'1gas`seen` in FigureS. Only one fastener assembly tliusis needed for eachjtraek' section 23 "adjacent one end thereof, since the cooperable joint engagementbetween adjacent sections serves `to maintain the remaining portion of the section firmly atop' the rail 18 and also to preventlateral movement between adjacent sections 23.
At the end of the carrier flight, each wear strip; 22 further includes a track section 23a, similar'to thesections 23, but having two protrusions29, .29, spaced .apart from each other by `approximately two inches. While there is no structural; connection at` the other ,end of section 23a, still the cooperable engagement by thefastener protrusions 29, 29 with rail 18`prevents anylateral movement of the track section.
The track sections 23 and23a further may beprovided with a series of longitudinal ribs. or ridges'33 which' elevate the carrier tray portions 13` above-the body of the wear strip 22, and thereby appreciably reduceJthe area of contact between the wear strips 22 and the carrier 11 traveling, thereon. ln this manner frictional losses between the carrier 11` and thewear strips arekept toa minimum. t
The wear strips are made from a plastic material since the same generallyI is non-toxic, inexpensive and `easy to form to shape. The strips 22 in the preferred ernbodiment thereof, preferably are made from a thermoplastic, such as nylon, which desirably also has a low coefficient of friction, is easy to keep clean, and is long wearing; although, it should be understood that' other thermoplastic materials also may be employedto' form the wear strips 22.
Experience has demonstrated, however, that thermo.- plastic materials, such as nylon, generally tend to expand under the load of the carrier traveling thereon. As' a consequence, the strips 22`if anchored firmly to the rails 18, buckle,` break, and otherwise work themselves loose from their mountings. In one exemplication of the ma terial used tests have shown that nylon strip, sections of approximately eighteen inches in length expand as much as from .4 to .42 inchwith use. The explanation generally given for this phenomena is that it is due to a combination of the absorption of water within the material, together with the pressure and the heat to which the material is subjected.
In any event, failure ofthe'track sections, due to the aforesaid buckling, cracking, and breaking made it evident that the wear strips 22` and their individualtrack sections 23 could not be completely anchored to. the rails 18. As a resultafter much experimentation, it it was` found that the best results were obtainable with 4 track sections 23 as hereinbefore described; namely, with only one portion of each track section 23l anchoredto the rail 18, and using the joint 26, also as hereinbefore described, wherein relative sliding movement is permitted between adjacent sections while one section further serves to maintain the free end of the section adjacent thereto firmly atop the rail 18. Experimentation further rei vealed, moreover, that aftracksection 23 or 23a of approximately one foot in `length worked ideally. That is, too great an expansion was not experienced by the section, and, consequently thejoint 26l couldbe made sufticiently small that it would not be a deposit for dirt and other foreign'matter.'
As best seen in Figure 2, the stripsZZgwhen mounted atop the rails 18, are preferably arranged to have the outermost end of each prong 27 spaced from the end wall 28` of the cut-out 24 wherein it is seated by a distance of` from` one-quarter to three-eighth of an inch. This provides `suiiicientroom to accommodate the expansion which each strip experiences.
When mounting the track sections 23A and-23 `to, the rails 18,- templates may be employed to measure and mark oif"tl1`edistance between'the holes 31 in the rails 18 inpreparation for mounting the tracks thereto. It is preferredtliat the tracksections be made'V by injection moldingI processes well known to persons skilled in such art. Y
It' thus' is seen'tliat the present invention provides` a conveyorl wear strip construction which is easy and economical to manufacture, readily installable, and which greatly enhances the operationaluse of `known conveyor structures'. Thewear strip track sections moreover are novelljl constructed and arranged to accommodate stress and expansion normally experienced in materials from which the track sections are made, each section being actually anchored at only one location on the frame on which it is placed, while unique joint construction betweenvsections accommodate track section expansiontand maintain the section firmly atop the frame.
Although what has been shown and described are preferred embodiments of the invention, it is to be understood that these are not intended to be exhaustive nor limitingt'the invention, but instead are given for the purpose of illustration so that the invention may be better understood, and that others skilled in the artmay be able to modify and adjust the invention without departing `from the spirit thereof, the scope of which is defined in the appendedclaims.
What is claimed is:
1. The combination with a pair of spaced horizontal andparallel extending rails `over which rides an endless conveyor of the type having platform sections extending over said rails for` support therefrom, of wear strips mounted atop eachlrail, arranged to have said platform sections travel thereover, and including a. plurality of track sections, each track section comprising an elongated thermoplastic body having a fiat bottom surface adaptedtolie atopa rail, a protrusion extending from saidbottom surface, adjacent one end. of said body, and insertablewithin an opening in said rail, lock` means engageablewithtsaid protrusion for maintaining the same within said'opening, an open end cut-out portion at said oneend of said body and extending longitudinally into said? body, a' prong extending longitudinally from` the i opposed end of said body, said prong and saidY cut-out portion each` having downward and divcrgingly extending opposed surfaces whereby the prong oflone section is nestingly insertable within the cut-out portion of the track secon adjacent thereto and' maintainedin position by the, same. y
2. The` combination described'in claim l wherein each track section includes at its' upper surfaceat least, one longitudinally extendingnarrow ridge for elevating` said conveyor from said body, thereby minimizingthe area. of
contact between said track sections and the conveyor ltravelling thereover.
3. The combination described in claim 1 wherein the end track section on each rail adjacent the end of carrier flight includes a second protrusion on said bottom surface insertable within another rail opening, spaced from said protrusion and cooperable therewith to maintain said end track section against lateral movement.
4. A conveyor rail wear strip comprised of plastic track sections arranged for mounting to a rail in end-to-end fashion for the travel of a conveyor thereover, each track section having means adjacent a first end thereof for anchoring the same atop the rail, each track section further including a cut-out portion extending longitudinally into one end thereof and a prong portion projecting longitudinally from the other end thereof, said cut-out portion and said prong portion of each track section including opposite facing downwardly diverging surfaces, whereby the prong portion of one track section is slidingly and nestingly insertable within the cut-out portion of the track section adjacent thereto and maintained in position by the same atop the rail.
5. The combination with spaced generally parallel extending conveyor rails, of a plurality of plastic wear strip track sections mounted on said rails in end-to-end fashion, 25
arranged to have a conveyor pass thereover, and characterized by a construction at the ends of said track sections providing means for maintaining the track sections on said rails while permitting expansion and contraction between track sections without disturbing track section continuity and maintenance on said rails, each track section having means adjacent a first end thereof for securing the same atop a rail, each track section further having at one end thereof an open end longitudinal extending receptacle and at the opposed end thereof a longitudinally projecting prong slidingly engageable within the receptacle of the track section adjacent thereto, each receptacle having opposed walls downwardly diverging from each other and engageable with the prong of the track section adjacent thereto to maintain the same in said receptacle, the prong of each track section being normally spaced from the inner end wall of the receptacle wherein it is held thereby to permit expansion between adjacent track sections.
References Cited in the le of this patent UNITED STATES PATENTS 762,373 Allendorf June 14, 1904 2,747,725 Hatch et al May 29, 1956 FOREIGN PATENTS 576,627 Germany May 13, 1933