OMAR ACUAAAOA
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`US 20050082147A1
`
`as) United States
`a2) Patent Application Publication (0) Pub. No.: US 2005/0082147 Al
`
` Mol (43) Pub. Date: Apr. 21, 2005
`
`
`(54) CONVEYOR BELT
`
`Publication Classification
`
`(76)
`
`Inventor: Edward T Mol, Marne, MI (US)
`
`Tint. C07 eeeeeeccecccceeeecceseeeeeeceeneseeenneeess B65G 15/42
`(SV)
`(52) US. Cd. ce ceceecccceeecsseecessnsecsnseeceneeecnnseesnnnseesnnsees 198/834
`
`Correspondence Address:
`MCGARRYBAIR PC
`171 MONROE AVENUE,N.W.
`SUITE 600
`GRAND RAPIDS, MI 49503 (US)
`
`.
`(21) Appl. No.:
`(22)
`PCTFiled:
`
`10/505,063
`Feb. 3, 2003
`
`(86) PCT No.:
`
`PCT/US03/03029
`
`(30)
`
`Foreign Application Priority Data
`
`Mar. 5, 2002
`
`(US). eeeccsssseesseesneesneeeeesees 60319133
`
`67)
`
`ABSTRACT
`
`A thermoplastic endless belt (100, 150) has a smooth outer
`surface (105) substantially free of discontinuities and an
`inner surface (108) with a plurality of teeth (108) at a given
`belt pitch (112). The teeth (108) are adapted to engage a
`sprocket (102, 152) with circumferentially spaced sheaves
`(104, 154) at a sprocket pitch (116) greater than the belt pitch
`(112). The belt (100, 150) is slightly stretchable so that the
`sprocket (102, 152) can drive the endless belt (100, 150)
`when engaging the teeth (108) within a range of load onthe
`belt (100, 150). The belt (100, 150) is preferred for use in
`conveyors in food processing industries where the smooth
`outer surface (105) can transport food items andis easier to
`clean and keep free of impurities.
`
`410
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`Weber EX1056
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`IPR2020-01557
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`Weber EX1056
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`IPR2020-01557
`
`

`

`Patent Application Publication Apr. 21,2005 Sheet 1 of 7
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`Patent Application Publication Apr. 21,2005 Sheet 2 of 7
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`Patent Application Publication Apr. 21,2005 Sheet 3 of 7
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`Patent Application Publication Apr. 21,2005 Sheet 4 of 7
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`Patent Application Publication Apr. 21,2005 Sheet 5 of 7
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`Patent Application Publication Apr. 21,2005 Sheet 7 of 7
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`US 2005/0082147 Al
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`Apr. 21, 2005
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`CONVEYOR BELT
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`[0001] This application claims the benefit of U.S. Appli-
`cation No. 60/319,133 filed Mar. 5, 2002.
`
`BACKGROUND OF THE INVENTION
`
`[0002]
`
`1. Field of the Invention
`
`[0003] This invention relates to endless belts for convey-
`ors and, more particularly,
`to thermoplastic endless belts
`driven by sprockets.
`
`[0004]
`
`2. Description of the Related Art
`
`[0005] Low tension, direct drive conveyor belts are typi-
`cally used in situations where hygiene and cleanliness are
`critically important. For example, in food processing plants
`such as those that process meat products for human con-
`sumption, low tension, direct drive belt conveyors are used
`to transport items. Sanitation is critically important and,
`therefore,
`the endless belts used in such conveyors are
`conventionally made of materials that can be hygienically
`cleaned, such as thermoplastics or stainless steel.
`
`[0006] Knownbelts are typically formed of interlocking
`links havingteeth that are adapted to engage drive sprockets.
`Oneof the problems with suchbelts is that food particles can
`become lodged in the joints of the interconnecting links.
`Consequently, cleaning the belts can be difficult and may
`require removing the belt from the conveyor system for
`special cleaning operations.
`
`under tension. There are some remaining problems, how-
`ever. Assembling a timing belt to a homogeneousbelt is
`costly and the bonding or adhering processiscritical. Failure
`of the bond increases the risk of contamination and totalbelt
`failure.
`
`SUMMARYOF THE INVENTION
`
`[0010] The invention solves these and other problems by
`providing a stretchable endless belt having an inner surface
`and a plurality of teeth extending therefrom at a given belt
`pitch. The teeth are adapted to engage a sprocket having
`sheaves spaced from each other at a given sprocket pitch.
`According to the invention, the belt pitch is less than the
`sprocket pitch so that the sprocket can drive the endless belt
`whenonly one tooth engages a sheave, and continueto drive
`the endless belt as it stretches under load by multiple teeth
`engaging multiple sheaves. Preferably, the endless belt is
`stretchable within a range of 0-3% ofits total length and the
`maximum width of a tooth is less than the maximum width
`of a sheave.
`
`‘Typically, each sheave is 11-15 percent wider than
`[0011]
`a corresponding tooth. Preferably, the belt is formed of a
`thermoplastic material and the teeth are formed integrally
`with the belt. Also, the teeth can be formed of urethane while
`the rest of the belt can be formed of copolyester. The outer
`surface will preferably be substantially free of discontinui-
`ties.
`
`In another aspect of the invention, a conveyor
`[0012]
`comprises an endless belt having inwardly facing teeth
`spaced at a belt pitch and a drive sprocket having sheaves
`circumferentially spaced about its perimeter at a sprocket
`pitch. The belt pitch is less than the sprocket pitch, the width
`of the teeth is slightly less than the width of the sheaves, and
`the belt is slightly stretchable. Thus, whenthe belt is under
`load, the teeth will continue to engage the sheaves enabling
`the belt to be driven by the sprocket. Preferably, the belt is
`stretchable within a range of 0-3% underloads of 0-18 Kg
`per cm of width. Also, the drive sprocket may typically have
`ten sheaves.
`
`[0007] One solution to this problem is the use of flexible
`thermoplastic belts without interlocking links such as that
`disclosed in U.S. Pat. No. 5,697,491. Such belts having a
`smooth continuous surface (sometimes called “homoge-
`neousbelts”) are driven by V-guides wherein a radial groove
`in a drive pulley engages a longitudinal nb on the underside
`of the belt. One of the problems with suchbelts is that grease
`and oil from the food items can migrate to the groove or to
`the rib, which causesaloss of friction between the pulley
`[0013]
`In yet a further aspect of the invention, a method of
`and the belt. Consequently the driving force becomes
`making a belt with integrally formed teeth includesthe steps
`unstable and unreliable. Moreover, such belts are under
`of extruding a flat ribbon of thermoplastic material; provid-
`tension to ensure that the pulley imparts enough driving
`ing a profile drum with a plurality of grooves in its outer
`force. This tensioning raises other issues beyond slippage
`surface; compressing the flat ribbon againstthe profile drum
`while the flat ribbon is still soft and malleable so that
`due to oils and contaminants. A thermoplastic belt under
`tension will stretch, which may require adjustment of the
`thermoplastic material flows into the grooves; withdrawing
`tension from time to time. In addition, there are additional
`the flat ribbon with formed teeth from the profile drum; and
`costs associated with ensuring that the conveyor frame be
`cooling the flat ribbon with the formed teeth.
`sufficiently strong enough to handle the normalstresses of
`the pretensioned belt plus additional stresses caused by
`loading the belt.
`
`It is known to provide a drive sprocket or drum
`[0008]
`with transverse grooves that are complementary in shape to
`teeth on a flexible conveyor belt, as shown for example in
`US. Pat. No. 4,170,281. However, the belt is formed from
`interlocking links and the belt is still under tension. The
`problemsassociated with interlocking links and pretension-
`ing remain.
`
`[0009] Another solution is disclosed in U.S. Pat. No.
`5,911,307 where a timing belt is added to a homogeneous
`belt to engage a drive sprocket. As a result, reliance upon
`friction for motion is minimized, and the belt need not be
`
`[0014] Another method of forming a belt with integral
`teeth comprises the steps of providing a flat ribbon of
`thermoplastic material; molding teeth onto one surface of
`the flat ribbon; and curing the flat ribbon with the teeth. In
`this case, the molding step can comprise injection molding
`or friction molding.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0015]
`
`In the drawings:
`
`[0016] FIG. 1 is a perspective side view of a belt accord-
`ing to the invention installed between two sprockets;
`
`FIG.2 is an enlarged view in elevation of a portion
`(0017]
`of FIG. 1;
`
`

`

`US 2005/0082147 Al
`
`Apr. 21, 2005
`
`[0018] FIG. 3 is a view similar to FIG. 2 with the belt
`under load;
`
`FIG.4 isa side elevational view of a portion of the
`[0019]
`belt, partially in cross-section, shown in FIGS. 1-3;
`
`[0020] FIG. 5 is a perspective side view of a belt accord-
`ing to the invention installed between two sprockets of a
`different configuration than FIG.1;
`
`[0021]
`and
`
`FIG.6 is an enlarged view of a portion of FIG. 5;
`
`FIG.7 is diagrammatic view illustrating a method
`[0022]
`of making a belt according to the invention.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`[0023] An endless belt 100 according to the invention is
`seen in FIG.1 in a typical installation between two sprock-
`ets 102 and 103. The sprockets 102, 103 are conventional
`and they can be any of a numberof different forms andsizes.
`Onesprocket 102 is a drive sprocket, the other 103 being an
`idler or slave sprocket. In this configuration, the upper span
`105 of the belt will travel in the direction of arrow 107. Each
`sprocket 102 or 103 has a numberof transverse grooves or
`sheaves 104 spaced around its circumference. The belt 100
`has a plurality of teeth 106 equidistantly spaced from each
`other on the inside surface 108 of the belt. The teeth 106
`
`engage the sheaves 104 of each sprocket. It will be under-
`stood that any given installation may have one, two, or more
`sprockets for a single endless belt. Also, for any given
`installation, one or more of the sprockets may be a drive
`sprocket, as for example sprocket 102, with the other
`sprocket or sprockets being idler sprockets. It will be under-
`stood that there need only be enough tension on the endless
`belt 100 to keep at least one of its teeth 106 engaged in a
`sheave 104 of the drive sprocket 102.
`
`[0024] The belt 100 has an outside surface 110 that is
`fairly smooth andfree of discontinuities. Preferably, the belt
`100 is made of a thermoplastic material such as Pebax®
`resin, polyester or polyurethane. The outside surface 110 on
`the upper span 105 is the carrying surface for transport of
`items. Becauseit is smooth and free of discontinuities, there
`is no place for particles or contaminants to lodge. Moreover,
`the belt 100 can be cleaned in situ, without the need to
`removeit from the installation.
`
`[0025] Greater detail about the structure of the belt 100 is
`shownin FIGS. 2 and 3. A combination of material selec-
`tion and construction enables the belt to stretch within a
`range of 0-3% ofits total length under a load ranging from
`0-100 poundsper inch of width (nearly 18 Kg per cm). The
`belt 100 has a pitch 112 defined as the distance between the
`centerlines of adjacent
`teeth 106. The belt pitch 112 is
`measured along a belt pitch line 114, which corresponds to
`the neutral bending axis of the belt. As the belt 100 bends
`around the sprocket 102, the neutral bending axis is that
`imaginary plane on one side of which the belt material is
`under compression and on the other side of which the belt
`material is under tension.
`
`[0026] Similarly, the sprocket pitch 116 is the arc length
`between the centerlines of adjacent sheaves 104, measured
`along the sprocket’s pitch circle 118. The sprocket pitch
`circle 118 in this case correspondsto the belt pitch line 114
`
`as the belt 100 moves around the sprocket 102. In other
`words,
`the sprocket pitch circle 118 will have the same
`radius as the belt pitch line 114 as the belt goes around the
`sprocket. For a thermoplastic belt, the area of greatest stress
`on the belt 100 occurs at zone 120, and the area of least stress
`occurs at zone 122 just as thebelt is released from the drive
`sprocket 102.
`
`[0027] Looking now also at FIG. 4, it can be seen that
`each tooth 106 extends upwardly from a surrounding inner
`surface 124 of the belt 100. Preferably, the belt 100 has a
`thickness between adjacent teeth 106 in a range of approxi-
`mately 3 to 4 mm,although it will be understood that the
`actual thickness will depend upon a given application. The
`invention is not limited to a particular thickness of the belt.
`For this embodiment, each tooth 106 stands approximately
`4 mm above the inner surface 124. Each tooth 106 has
`
`tapered sidewalls 126, each sidewall preferably tapering
`from the inner surface 124 at an angle of about 72.5 degrees.
`Each tooth will thus have a width at its base wider than that
`at the tip. Each sheave 104 on the sprocket 102 is wider than
`the corresponding tooth 106 on the belt 100, preferably on
`the order of 11 to 15 percent, and is tapered with drive walls
`128. Thus, for example, if the widest part of the tooth 106
`is 8 mm,the widest part of a sheave 104 might be 11.25 mm,
`permitting a belt stretch of up to 3% where the teeth 106 can
`still be received in the sheaves 104. If the widest part of a
`sheave is 10 mm,the widest part of a tooth can be 7 mm in
`order to permitbelt stretch of up to 3%. It is recognized that
`the belt will not stretch evenly, ie., it will stretch more
`between the teeth than including the teeth. This is because
`the belt
`is thinner between the teeth than at
`the teeth.
`Nevertheless, stretch here is measured overall, regardless of
`which portion of the belt is actually stretching under load.
`Also, the depth of each sheave 104 is greater than the height
`of each tooth 106 wherein each drive wall 128 is longer than
`a corresponding sidewall 126 so that the tooth will not
`bottom out in the sheave.
`
`Thebelt pitch 112 whenthe belt 100 is at rest is less
`[0028]
`than the sprocket pitch 116. Thus,as illustrated in FIG.2, a
`belt 100 under no load will effectively be driven in the stress
`zone 120 by the drive wall 128 of a single sheave 104 acting
`against sidewall 126 of a single tooth 106 received within
`the sheave. On the other hand,asillustrated in FIG.3, a belt
`100 under load P tends to stretch so that the belt pitch 112,
`especially within the stress zone 120, more nearly equals the
`sprocket pitch 116. In this case, more teeth 106 are engaged
`by corresponding sheaves 104. Under maximumstress, the
`belt pitch 112 will equal the sprocket pitch 116 as the belt
`100 is pulled around the sprocket 102. In the embodiment
`illustrated in FIG. 3 wherein the sprocket 102 has ten
`sheaves 104, the maximum number of sheaves that will
`drive a corresponding tooth, at least in whole or in part, is
`six. Since the teeth 106 are smaller than the sheaves 104, and
`since the belt pitch 112 is smaller than the sprocket pitch 116
`(below maximum load), the elasticity of the belt will permit
`anywhere from one to six teeth on the belt to be driven by
`the sprocket 102. The higher the load on the belt, the more
`teeth will be engaged by the sprocket.
`
`[0029] Looking now at FIGS. 5 and6, it can be seen that
`a belt 150 according to the invention can be used with
`existing sprockets. Here, the belt 150 is shown installed on
`sprockets 152 and 153 of the type that can be obtained from
`Intralox, Inc. Sprocket 152 may be a drive sprocket,
`in
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`US 2005/0082147 Al
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`Apr. 21, 2005
`
`which case sprocket 153 will be the slave sprocket. Each
`sprocket 152, 153 has a number of transverse grooves or
`sheaves 154 adapted to receive teeth 156 in driving engage-
`ment as described above. The relative dimensions of com-
`
`ponents in this embodiment will be as described above for
`the embodiment of FIGS. 2 and3. In addition, there may be
`tracking tabs 158 adapted to engage correspondingslots 160
`in the belt 150 to maintain proper alignmentofthe belt.
`[0030] Preferably, the teeth 106, 156 will be integral with
`the belt 100, 150. A method of making an endless belt
`according to the invention is shown in FIG. 7. An appro-
`priate thermoplastic material such as polyester or polyure-
`thane is placed in an extruder 170. Using conventional
`extrusion methods,a flat ribbon 172 of thermoplastic mate-
`rial is extruded from the extrusion nozzle 174. While the flat
`
`ribbon 172 is still soft and malleable, it is passed over a
`profile drum 176. The profile drum 176 has on its outer
`surface a plurality of grooves 178 corresponding in shape to
`the teeth 106, 156 to be formed. A compression drum orbelt
`180 presses against the flat ribbon 172, compressing the
`ribbon, and forcing a portion of the flow into the grooves
`178. Upon exiting the profile drum 176, the formed ribbon
`182 passes through a cooling station 184 where it hardens.
`The temperature of the flat ribbon 172, the pressure on the
`ribbon 172 between the compression drum 180 and the
`profile drum 176, and the cooling time are all established
`and determined to anticipate the final thickness of the belt,
`the dimensions of each tooth, and the belt pitch. In this
`respect, it will be understood that there is a predetermined
`amount of shrinkage of the formed ribbon 182 asit cools.
`Upon cooling, the formed belt is collected and stored until
`it is needed to form an endlessbelt.
`
`[0031] Another method of manufacturing the belt is to
`start with a homogeneous belt of approximately 7 to 8 mm
`in thickness, and machine away material between adjacent
`teeth 106, 156 to a depth of about 3 to 4 mm. This method
`necessarily generates scrap.
`[0032] Another method of manufacturing the belt is to
`start with a homogeneous belt approximately 3-4 mm in
`thickness, and injection mold teeth at an appropriate belt
`pitch onto one surface of the belt. In this method, the teeth
`can be different material. For example,
`the belt can be
`formed of polyester such as COPE, with the teeth being
`formed of a urethane.
`
`[0033] Another method of manufacturing the belt is to
`start with a homogeneous belt approximately 3-4 mm in
`thickness, and friction mold teeth at an appropriate belt pitch
`onto one surface of the belt. In this method, the teeth can be
`different material. For example, the belt can be formed of
`polyester such as COPE,with the teeth being formed of a
`urethane. It has been found that applying a 160 Hz orbital
`motion of a polyester tooth on a polyester belt for three
`secondscreates enough softening for the tooth to bond to the
`belt.
`
`It will be understood that certain variations and
`[0034]
`modifications can be made without departing from the scope
`of the invention. For example, the length of each tooth need
`not extend to the edge of the belt as illustrated. A narrow
`rank of teeth may be sufficient. Further, a narrow belt having
`a rank of teeth can be preformed and adhered or bonded to
`an inner surface of a larger belt. Moreover,
`if desired,
`coloring pigments and/or antibacterial agents can be added
`to the thermoplastic prior to extrusion.
`
`[0035] While the invention has been specifically described
`in connection with certain specific embodiments thereof, it
`is to be understood that this is by way ofillustration and not
`of limitation, and the scope of the appended claims should
`be construed as broadly as the prior art will permit.
`
`1. A stretchable endless belt having an inner surface and
`a plurality of teeth extending therefrom at a given belt pitch,
`wherein the teeth are adapted to engage a sprocket having
`sheaves spaced from each other at a given sprocket pitch,
`characterized by the sprocket pitch being greater than the
`belt pitch when the belt is at rest so that the sprocket can
`drive the endless belt when at least one tooth engages a
`sheave, and continue to drive the endless belt as it stretches
`under load by multiple teeth engaging multiple sheaves.
`2. Astretchable endless belt according to claim 1 wherein
`the endless belt is stretchable within a range of 0-3% of its
`total length.
`3. Astretchable endless belt according to claim 1 wherein
`the maximum width of a tooth is less than the maximum
`width of a sheave.
`
`4. Astretchable endless belt according to claim 3 wherein
`each sheave is 11-15 percent wider than a corresponding
`tooth.
`5. Astretchable endless belt according to claim 1 wherein
`the belt is formed of a thermoplastic material.
`6. Astretchable endless belt according to claim 1 wherein
`the teeth are formed integrally with the belt.
`7. Astretchable endless belt according to claim 1 wherein
`the teeth are formed of urethane and the rest of the belt is
`
`formed of copolyester.
`8. Astretchable endless belt according to claim 1 wherein
`the outer surface is substantially free of discontinuities
`9. Aconveyor comprising an endless belt having inwardly
`facing teeth spaced at a belt pitch and a drive sprocket
`having sheaves circumferentially spaced about its perimeter
`at a sprocket pitch, characterized by the sprocket pitch being
`greater than the belt pitch when the belt it at rest, the width
`of the teeth being slightly less than the width of the sheaves,
`and the belt being slightly stretchable, whereby when the
`belt is under load, teeth will continue to engage the sheaves
`enabling the belt to be driven by the sprocket.
`10. A conveyor according to claim 9 wherein the belt is
`stretchable within a range of 0-3% underloads of 0-18 Kg
`per cm of width.
`11. A conveyor according to claim 9 wherein the drive
`sprocket has ten sheaves.
`12. A method of making a belt with integrally formed
`teeth comprising the steps of:
`
`extruding a flat nbbon of thermoplastic material;
`
`providing a profile drum with a plurality of groovesin its
`outer surface;
`
`compressing the flat ribbon against the profile drum while
`the flat ribbon isstill soft and malleable so that ther-
`
`moplastic material flows into the grooves;
`
`withdrawing the flat mnbbon with formed teeth from the
`profile drum; and
`
`cooling the flat ribbon with the formed teeth.
`13. A method of forming a belt with integral
`comprising the steps of:
`
`teeth
`
`providing a flat ribbon of thermoplastic material;
`
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`

`US 2005/0082147 Al
`
`Apr. 21, 2005
`
`molding teeth onto one surface of the flat ribbon; and
`
`curing the flat ribbon with the teeth.
`14. The method of claim 13 wherein the molding step
`comprises injection molding.
`15. The method of claim 13 wherein the molding step
`comprises friction molding.
`16. Aconveyorbelt system comprising: (a) a drive pulley
`having a plurality of pulley teeth thereon, said drive pulley
`having an axis of rotation; and (b) a closed belt having a
`pulley side which faces said drive pulley, wherein:(i) said
`closed belt has a plurality of belt teeth and a plurality of
`recesses on said pulley side, each of said recesses having
`two sides and one base; (ii) said drive pulley is configured
`to rotate about said axis of rotation in order to propel said
`belt in a drive direction by at least one of said pulley teeth
`pushing a corresponding one of said sides of one of said
`recesses; and (iii) in a cross-sectional view of said drive
`pulley and said closed belt
`taken in a plane which is
`perpendicular to said axis of rotation, said one pulley tooth
`only partially fills said one recess.
`17. The conveyor belt system of claim 16, wherein: (a)
`each of said pulley teeth has a pulley tooth width; (b) each
`of said recesses has a recess width; and (c) said pulley tooth
`width is less than said recess width.
`18. The conveyor belt system of claim 16, wherein: (a)
`each of said pulley teeth has a pulley tooth height; (b) each
`
`of said belt teeth has a belt tooth height; and (c) said belt
`tooth height is less than said pulley tooth height.
`19. The conveyorbelt system of claim 16, wherein when
`said closed belt is not loaded, only one of said pulley teeth
`is in contact with one of said belt teeth.
`
`20. The conveyor belt system of claim 16, wherein:(a)
`said pulley teeth have a pulley pitch; (b) said belt teeth have
`a belt pitch measured when said closed belt is flat; and (c)
`when said closed belt is not loaded said pulley pitch is
`greater than said belt pitch.
`21. The conveyor belt system of claim 16, wherein said
`closed belt is made of a material having a low bacterial
`count.
`
`22. The conveyor belt system of claim 16, wherein said
`closed belt is made ofplastic.
`23. The conveyor belt system of claim 16, wherein said
`closed belt is made of non-reinforced plastic.
`24. A stretchable endless belt according to claim 1 where
`the teeth extend across the belt from one edge to the other.
`25. The method of claim 12 wherein the extruding step
`comprises extruding a flat ribbon of thermoplastic material
`having at least two different durometers.
`
`