GB1570553A - Creation of Inventions and Patents with Artificial Intelligence

GB1570553A – Tractor belts
– Google Patents

GB1570553A – Tractor belts
– Google Patents
Tractor belts

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Publication number
GB1570553A

GB1570553A
GB35763/77A
GB3576377A
GB1570553A
GB 1570553 A
GB1570553 A
GB 1570553A
GB 35763/77 A
GB35763/77 A
GB 35763/77A
GB 3576377 A
GB3576377 A
GB 3576377A
GB 1570553 A
GB1570553 A
GB 1570553A
Authority
GB
United Kingdom
Prior art keywords
belt
lugs
band
tractor
wire filament
Prior art date
1976-08-30
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Expired

Application number
GB35763/77A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Airborne Manufacturing Co

Original Assignee
Airborne Manufacturing Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1976-08-30
Filing date
1977-08-25
Publication date
1980-07-02

1977-08-25
Application filed by Airborne Manufacturing Co
filed
Critical
Airborne Manufacturing Co

1980-07-02
Publication of GB1570553A
publication
Critical
patent/GB1570553A/en

Status
Expired
legal-status
Critical
Current

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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL

B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS

B65G23/00—Driving gear for endless conveyors; Belt- or chain-tensioning arrangements

B65G23/02—Belt- or chain-engaging elements

B65G23/14—Endless driving elements extending parallel to belt or chain

B65G23/16—Endless driving elements extending parallel to belt or chain with dogs engaging abutments on belts or chains

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING

B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor

B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles

B29C39/026—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles characterised by the shape of the surface

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING

B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor

B29C39/028—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles having an axis of symmetry

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING

B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts

B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics

B29C70/28—Shaping operations therefor

B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core

B29C70/36—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and impregnating by casting, e.g. vacuum casting

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING

B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts

B29C70/88—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced

B29C70/887—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced locally reinforced, e.g. by fillers

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE

B29D29/00—Producing belts or bands

B—PERFORMING OPERATIONS; TRANSPORTING

B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL

B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE

B29D29/00—Producing belts or bands

B29D29/08—Toothed driving belts

B29D29/085—Double-toothed driving belts

F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL

F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR

F16G1/00—Driving-belts

F16G1/28—Driving-belts with a contact surface of special shape, e.g. toothed

G—PHYSICS

G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY

G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR

G03B1/00—Film strip handling

G03B1/18—Moving film strip by means which act on the film between the ends thereof

G03B1/20—Acting means

G03B1/24—Sprockets engaging holes in the film

Description

PATENT SPECIFICATION
( 11) 1570553 ( 21) Application No 35763/77 ( 22) Filed 25 Aug 1977 ( 31) Convention Application No 718 831 ( 19) ( 32) Filed 30 Aug 1976 in ( 33) United States of America (US) ( 44) Complete Specification published 2 July 1980 ( 51) INT CL 3 B 65 H 17/38; B 29 D 29/00 ( 52) Index at acceptance B 8 R 8 D 9 RW 4 B 5 A 1 R 214 A 1 R 314 C 5 1 R 410 20 T 3 Bil ( 72) Inventors SARABJIT S CHEEMA, BARTON F NORTON and CHARLES B SMALL ( 54) IMPROVEMENTS IN AND RELATING TO TRACTOR BELTS ( 71) We, AIRBORNE MFG CO, a Corporation organised under the laws of the State of Ohio, United States of America, of 711 Taylor Street, Elyria, Ohio 44035, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following method:The invention relates to improvements in means for advancing strip material in both directions along its length and particularly, strip material having holes or perforations spaced at intervals along its length, in one or both margins of the material Such means are utilised, for example, in machines for producing paper business forms and in the business machines, such as high speed printers, with which such forms are used Motion picture cameras and projectors also employ means of this kind in their film transport mechanisms.
An example of means of this kind is an endless mechanism including a toothed flexible belt trained on sprockets and carrying pins for engaging simultaneously a number of successive perforations in paper business forms.
Such means are sometimes referred to as tractor mechanisms and such belts, as tractor belts.
Specifically the invention relates to a belt for use in such strip advancing means and a method of making such a belt.
Applications utilising tractor mechanisms to advance and position continuous strip material typically involve stop and start motion and require exact control of the material being handled Accurate positioning of successive segments or lines of the material at predetermined stations is necessary, for example, when moving paper business forms through high speed printers to ensure correct placement of the printed material on the form Even more critical is the positioning of each successive frame of a motion picture film in the projection aperture or gate Failure to bring each frame to the same position results in undesirable “jump’ of the projected image In sophisticated applications such as scientific and medical projectors, projected images of successive frames of film on perceivably different spots on a viewing screen is unacceptable.
Other demands on tractor mechanisms and the like include the need to accelerate and decelerate the material at high rates when starting, moving, and stopping it to bring successive segments into registry with a predetermined station or position within a short interval of time Simultaneous engagement of a number of perforations in the material being moved by pins or the like of the tractor mechanism is helpful in distributing the high inertia loads involved in providing such motions over a length of material and a number of perforations and thereby avoiding damage to the perforations in it Mutilation and damage to the perforations is undesirable because it tends to prevent positive engagement of them by the tractor mechanism resulting in inaccurate control and movement of the material through its desired motion.
The foregoing problems involved in advancing perforated strip material dictate tractor mechanisms having pins or other means for engaging the perforations of the material that are accurately spaced at intervals corresponding closely to the spacing of the perforations, pins which fill the perforations without deleterious distortion of them to reduce play in their engagement with the pins, and pins which do not damage or degrade the perforations by wear and tear and which, in turn, are not themselves altered significantly by wear on the raterial being advanced.
Various endless belt, chain and band constructions have been utilised in the past They have shortcomings of one type or another, however Some fail to maintain a constant pitch diameter and resultant accurate pin spacing; others are difficult to fabricate consistently to the tolerances required for acceptm:
uis In lso 1,570,553 able operation or are so expensive as to be impractical, and others are subject to inaccuracy through wear inherent in their construction materials.
According to one aspect of the present invention there is provided an endless tractor belt for advancing a straight length of strip material having longitudinally spaced perforations adjacent one edge thereof, said belt comprising an endless flexible band of plastics material, having parallel side edges, and integral therewith a first set of substantially semi-cylindrical lugs projecting from the outer surface thereof and spaced apart longitudinally thereof for engagement in the spaced perforations in the strip material, each lug being spaced from one side edge of the bard, and a multistrand single steel wire filament reinforcement embedded in the inner surface of the band and exposed on the inner surface at least in a circumferentially continuous area thereof for sliding engagement with guide means therefor.
According to another aspect of the invention there is provided a tractor mechanism for advancing a straight length of strip material having longitudinally spaced perforations adjacent one edge thereof, the mechanism comprising a belt as described above, means about which the belt is entrained and for driving the belt, means for guiding strip material into contact with the outer surface of a linear part of the belt and into engagement with the lugs projecting therefrom, and backing guide means in contact with the circumferentially continuous area of the inner surface of the belt in the region of engagement of the strip material therewith.
According to a further aspect of the present invention there is provided a method of making a flexible endless belt as described above of predetermined length and having a multistrand single steel wire filament reinforcement and a set of lugs integral therewith, projecting from the outer surface thereof and distributed at a predetermined pitch along its length, the method comprising the following steps:
( 1) providing a multistrand single steel wire filament reinforcement about an external wall of a central mandrel mold element having a circumference related to said predetermined length and corresponding to and for providing the inner surface of the belt, ( 2) surrounding the mandrel and the reinforcement with an annular outer ring mould element in a predetermined molding relationship, said ring mold element having an internal endless wall corresponding to and for providing the outer surface of the belt and having substantially semi-cylindrical pockets therein distributed along its length at intervals corresponding to the desired predetermined pitch of said set of lugs, each of said pockets providing an integrally formed lug projecting from said outer surface at the desired predetermined pitch and position, and said ring mold element internal wall and said mandrel mold element external wall being spaced apart when said mold elements are assembled in a molding relationship a distance corresponding to the 70 desired thickness of the belt exclusive of projecting lugs and together forming a mold cavity, and ( 3) filling said mold cavity with plastics material 75 The invention will be more fully understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: 80 Figure 1 is a side elevational view of an embodiment of a tractor belt in accordance with this invention; Figures 2 and 3 are enlarged perspective views of a portion of the belt of Figure 1 85 showing particularly the radially outer and inner sides of the belt, respectively; Figures 4, 5 and 6 are enlarged plan, sectional, and side elevation views, respectively, of a portion of the belt of Figure 1; 90 Figure 7 is a diagrammatic view in perspective of a tractor mechanism including the belt of Figure 1 trained around sprockets in driving engagement with a number of perforations in the margin of a strip of motion picture film; 95 Figure 8 is a sectional view in enlarged scale of the belt, backing guide, and film shown in Figure 7; Figure 9 is a sectional view of a portion of the belt as shown in Figures 5 and 8, for 100 example, but in even greater enlargement; Figure 10 is a perspective view of an assembled three-part mold used to make the belt of Figure 1; Figure 11 is a sectional view on enlarged 105 scale through the assembled mold of Figure taken on the line 11-11 of Figure 10; Figure 12 is a portion of the sectional view of Figure 11 indicated in Figure 11 by broken outline and shown on an enlarged scale; 110 Figures 13 and 14 are two perspective views showing portions of elements of the mold of Figure 10; and Figure 15 is a plan view of an alternative tractor mechanism to that shown in Figure 7 115 including a modified embodiment in accordance with this invention.
A tractor belt 10 shown in Figures 1 to 9 comprises an endless, flexible and generally flat thin band 11 having a set of strip engaging 120 lugs 12 projecting from the outer surface 14 and another set of sprocket or cog engaging lugs 15 projecting from the inner surface 16 of band 11 Embedded in band 11 and exposed at inner surface 16 are multiple strands or 125 turns of fine wire or wire filament 17 (Figure 9).Belt 10 as shown and described is intended for use in a tractor mechanism of a motion picture projector (shown in part and diagram 130 1,570,553 matically in Figure 7) for projecting coronary arteriography films, for example, at selected speeds from one to sixty frames per second in both directions and without any apparent motion from one projected image to the next except for that provided by the filmed subject.
In other words, belt 10, when driven and controlled with the desired motions with respect to time and distance, must be able to continuously engage, advance and release successive lengths of film in a way that accurately controls the film position at all times so that it faithfully imparts to the film only the motions desired.
A tractor mechanism for doing this is shown diagrammatically in Figure 7 and comprises the belt 10 trained about a drive sprocket 18 and an idler sprocket 19 Each sprocket is supported on a shaft for rotation The shaft supporting drive sprocket 18 is driven by drive means 20 Lugs 15 engage cavities 21 provided in the peripheries of the sprockets at intervals corresponding to the spacing of lugs 15.
Along the straight line path of belt 10 between sprockets 18 and 19 side 16 of band 11 is guided and supported in the path of travel of film F by backing guide 22 This, with other film guides (not shown), helps to guide the film through and correctly position it at the projection station of the projector where light is directed through one frame of the film at a time and into and through the projection lens.
Lugs 15 preferably correspond closely in size to or otherwise positively engage their mating sprocket cavities 21 Also, as noted above the spacing of lugs 15 matches the spacing of sprocket cavities 21 driving and supporting the belt Similarly, lugs 12 must be spaced on the belt at intervals corresponding closely to the spacing of the perforations in the film to be transported In addition, each lug 12 must be large enough to fill a perforation in the film so that the engagement is positive and admits of no lost motion or back lash; at the same time, primarily by their shape, lugs 12 must be capable of free and smooth entry and withdrawal from the film perforations.
Accordingly the spaced apart lugs 12 are supported, project from and are integral with the endless band, and are approximately semicylindrical and oriented with their flat ends 23 parallel to side edges 24 of band 11 and belt 10, and therefore also parallel to the direction of travel of the belt and film carried by it The cross sectional dimension of each lug 12 in the direction of travel and at surface 14 of band 11 from which it projects matches the corresponding dimension of the perforations it is to engage so that when a lug has fully entered a perforation the lug completely fills the opening in: at least the direction of path of travel and the belt and film move together as one.
Lugs 12 are preferably located with one end 23 flush with one edge 24 of the belt as seen clearly in Figures 2, 4 and 5 to keep the band away from interference with the image area of the film They may be spaced to engage every perforation in the film to be transported, or to engage less than every one.
There must be simultaneous engagement between a plurality of lugs 12 and perforations of the transported film to achieve the full benefits of this invention including distribution of the inertia loads and minimization, if not elimination, of an accumulation of spacing error encountered when engagement is only by successive single lugs or pins conventional pin sprockets or claw mechanisms.
Lugs 15 as shown are also approximately semi-cylindrical, flat ended, and dimensioned to fill a corresponding cavity in sprocket drive and idler wheels It will be noted that each lug 15 is shorter than the width of band 11 and is spaced from both edges 24 The reason for this is discussed below.
Lugs 12 and 15 as well as band 11 formed integrally with the lugs are preferably molded of a plastics material having good elasticity, flexibility and a high resistance to cutting, tearing and abrasion These properties ensure a “handling” of the film or other strip material to be advanced by the belt that will not cause undesirable damage or distortion of the perforations This advantage is not available with metal perforation-engaging pins or lugs, for example The elastic quality of the material aids in filling each perforation with the lug engaging it, while minimizing wear and alteration of the lug size and shape by strip material having sharp, hard edges such as motion picture film.
Preferably the belt 10 is molded as described below of urethane polymer such as Adiprene (Trade Mark) and a curing agent such as Moca (Trade Mark), both made by E I.
du Pont de Nemours & Co, Inc.
The multiple turns of fine wire 17 are embedded in band 10 to provide the tensile strength necessary for an endless belt of fixed predetermined length and having lugs 12 for example, held to their originally established pitch The wire is preferably fine and of a diameter of only a fraction of the thickness of band 11 In a preferred embodiment, 5 mil tempered stainless steel wire is used in a band approximately 040 ” thick and 160 ” wide.
Such a fine wire provides the requisite tensile strength and resultant dimensional stability and permits sufficient flexibility to allow many passes around small diameter sprockets without fatigue failure.
A single length of wire 17 is preferred, wound in multiple turns in a single layer from edge to edge of band 11 Adjacent turns are 1,570,553 advantageously spaced from each other to ensure their being completely embedded in the band material as shown particularly in Figure 9 It is also clear in Figure 8, showing a section through backing guide 22, that the wires 17 are embedded in band 11 close to surface 16 so that the outside diameter of each wire 17 is at least tangent with and exposed on surface 16 between the lugs 15 and in circumferentially continuous areas to each end of the lugs 15 and at the side edges of the band This feature provides the belt with a low friction, hard wear surface for sliding engagement with backing guide 22 Backing guide 22, of course, is provided with a groove to permit the free passage of driving ‘ugs 15 as shown.
The high tensile strength fine wire 17 co-operates in an advantageous and unexpected way with, and to overcome the shortcomings and preserve the advantages of, band 11 and its integral lugs 12 and 15 to provide a belt of fixed pitch length having a wear resistant surface in the desired place to fulfil the objects of the tractor mechanism.
It should be noted that lugs 12 and 15 may be located along the length of band 11 in a staggered fashion as shown in the drawings or they may be positioned opposite each other or be unequal in number without losing the advantages of this belt Also, other lug shapes than the approximately semi-cylindrical ones shown may be used for the lugs 15 so long as they permit clean and easy entry and withdrawal from the cavities they are intended to engage and fill or otherwise positively engage them for accurate control of the transported strip material.
The above described belt may be molded in a circle in a three part mold, the parts of which are shown assembled in Figures 10 and 11.
The mold comprises a two part central mandrel element consisting of a base 25 and an inner ring 26, and an outside element consisting of an outer ring 27 Inner ring 26 has a cylindrical shoulder 28 corresponding to and for providing surface 16 of band 11 Shoulder 28 extends between one face of inner ring 26 and an annular surface 29 which corresponds to and defines an edge 24 of band 11 Pockets are provided in the bottom of shoulder 28 corresponding to and for forming lugs 15.
Base 25 has a cylindrical shoulder 31 reaching to its upper face that is narrower in axial extent, but corresponds to and matches in diameter, cylindrical shoulder 28 in inner ring 26 Annular surface 32 meets shoulder 31 and corresponds to and defines the other edge 24 of band 11.
Base 25 is provided with dowel pins 33 so that the base 25 and inner ring 26 may be put together in a fixed relationship with shoulders 28 and 31 aligned and a single cylindrical surface formed corresponding to the full width of band 11, with pockets 30 spaced between surfaces 29 and 32 This relationship is shown clearly in Figure 12.
Outer ring 27 is an annular element that surrounds the central mandrel element comprising base 25 and inner ring 26, and rests on annular surface 32 of base 25 When inner ring 26 is in place on base 25 and the outer ring 27 is located coaxially with the central mandrel by engagement of interfitting cylindrical shoulders 34 and 35 on base 25 and outer ring 27, respectively, an inner cylindrical shoulder 36 of ring 27, corresponding to and providing surface 14 of band 11, is opposite, but spaced radially from, shoulders 28 and 31 by a distance equal to the desired thickness of band 11 Inner cylindrical shoulder 36 is provided with open-ended pockets 37 corresponding to and for forming lugs 12 integrally with band 11.
Machine screws 38 hold outer ring 27 in place on base 25 The upper and radially adjacent corners of rings 26 and 27 are chamfered or otherwise relieved to make a Vshaped annular trough 39 opening into the mold cavity formed between the central and outer elements of the mold.
In use of the apparatus described above, base and inner ring mold parts 25 and 26 are assembled together as shown in the drawings.
Fine wire 17 is wrapped in successive turns preferably spaced a distance less than the wire’s diameter apart and in a single layer extending between surfaces 29 and 32 of shoulders 28 and 31, respectively One end of wire 17 may be held for winding by inserting it into a passage (not shown) in surface 29 or 32, for example A slight tension on the wire of at least 1/10, and preferably from 1/4 to 1/2, pound is preferred during the winding operation When wound, the other end of the wire may be inserted in another opening (not shown) in the other annular surface to hold the wrapped wire in place The wire preferably is coated with a priming agent such as Ecco prime PR-1 (Trade Mark) to increase the adhesion of the urethane polymer to it.
Next, outer ring 27 is located in its assembled position enclosing and coaxial with the central mandrel and fastened in place with machine screws 38 The mold elements will then be related as shown variously in Figures 11, 12 and 13 and with wire 17 in place as shown in Figure 14.
The preferred method of filling the mold cavity comprises placing the entire mold assembled as described above and with the multiple turns of wire in place in an evacuated chamber and then pouring the material to be molded into trough 39 The material flows from all around the trough into the mold cavity through the opening between inner ring 26 and outer ring 27 Because the mold is evacuated no air need be displaced from the cavity by the material flowing into it.
1 1,7,5 It is also possible to fill, and some useful belts have been made by filling, trough 39 of the assembled mold in a normal atmosphere and by then drawing a vacuum on the mold cavity once it is essentially filled.
A modified form of tractor belt is shown in Figure 15 The tractor mechanism shown includes a pair of idler sprockets 40 and 41 and a drive sprocket 42 A tractor belt 43 is trained over and around the sprockets so that lugs 44 thereon which engage perforations in film F also engage cavities or pockets in drive sprocket 42 Thus, the lugs that engage the perforations and control the mc ion of film F also provide a driving connection between belt 43 and its driving means, drive sprocket 42.
This embodiment of the invention enjoys all the advantages described above as well as the additional advantage of not involving the problem of spacing relationships between the lugs on one side of the belt and those on the other side of the belt.
In further modification the drive lugs 15 of belt 10 may be reversed or exchanged with pockets or openings on the drive sprocket.
Lugs 15 of the same character and quality as described above could be provided on the outer periphery of a drive sprocket, such as sprocket 18 in the mechanism of Figure 7, for engagement with pockets or openings in belt 10 similarly related and corresponding to pockets or cavities 21 in sprockets 18 and 19.
In this embodiment the wire core in the belt could be arranged and located to provide a space between adjacent strands to accommodate the openings.
Also the spacing and location of lugs 12 and laterally and longitudinally on each side of band 10 of belt 11 and relative to each other may be varied for varying the distribution of the loads applied to band 10 by the lugs without losing the advantages and benefits of the belt Further the belt may have two or more parallel sets of lugs for engaging and transporting the perforated strip material.
There is thus provided a belt which can be manufactured relatively easily with consistently high precision; i e, accurate pitch diameter, lug size and lug spacing It is designed to maintain its pitch diameter in spite of long operation trained over small radius sprockets and involving repeated stops and starts The lugs for engaging the perforations in the material to be advanced are especially adapted to resist wear by motion picture safety film without deleterious distortion or damage to the perforations therein.

Claims (1)

WHAT WE CLAIM IS:-
1 An endless tractor belt for advancing a straight length of strip material having longitudinally spaced perforations adjacent one edge thereof, said belt comprising an endless flexible band of plastics material having parallel side edges, and integral therewith a first set of substantially semi-cylindrical lugs pro 65 jecting from the outer surface thereof and spaced apart longitudinally thereof for engagement in the spaced perforations in the strip material, each lug being spaced from one side edge of the band, and a multistrand single 70 steel wire filament reinforcement embedded in the inner surface of the band and exposed on the inner surface at least in a circumferentially continuous area thereof for sliding engagement with guide means therefor 75 2 A tractor belt according to claim 1, in which said multiple strands of wire filament are provided by a single length of wire filamentwound in a single layer across the width of said band and whose ends terminate in the 80 edges of said band.
3 A tractor belt according to either claim 1 or claim 2, in which said wire filament is made of stainless steel and is about 5 mils in diameter 85 4 A tractor belt according to any one of claims 1 to 3, including a second set of lugs each projecting from the inner surface of the band and spaced apart longitudinally thereof for engagement with a sprocket in a tractor 90 mechanism, the lugs of the second set being spaced from both the side edges of the band to provide a circumferentially continuous area, in which the wire filament reinforcement is exposed, along both side edges of the band 95 A tractor belt according to claim 4, wherein each of the lugs of the second set of lugs is substantially semi-cylindrical.
6 A tractor belt according to any one of claims 1 to 5, wherein said band is flat and 100 is molded of plastics material, the or each set of lugs being molded integrally therewith so as to be highly resistant to wear, and said wire filament is wound in a single layer across the width of said band and supports and carries 105 said band and lugs molded integrally therewith and maintains substantially constant the spacing between said lugs and the length of said band.
7 A tractor belt according to any of claims 110 1 to 6, in which said band and the or each set of lugs are made of urethane polymer.
8 A tractor mechanism for advancing a straight length of strip material having longitudinally spaced perforations adjacent one edge 115 thereof, the mechanism comprising a belt according to any one of claims 1 to 7, means about which the belt is entrained and for driving the belt, means for guiding strip material into contact with the outer surface of 120 a linear part of the belt and into engagement with the lugs projecting therefrom, and backing guide means in contact with the circumferentially continuous area of the inner surface of the belt in the region of engagement of the 125 strip material therewith.
9 A tractor mechanism according to claim 8, wherein the belt includes a second set of lugs each projecting from the inner surface of the 1,570,553 z 1,570,553 band and spaced apart longitudinally thereof for engagement with a sprocket in a tractor mechanism, the lugs of the second set being spaced from both the side edges of the band to provide a circumferentially continuous area, in which the wire filament reinforcement is exposed, along both side edges of the band, and the means about which the belt is entrained comprise sprockets engaging the inner surface of the belt and with which the lugs of the second set of lugs are engaged, one of the sprockets being connected to the drive means for driving the belt.
A tractor mechanism according to claim 8, wherein the means about which the belt is entrained comprise sprockets engagirg the inner surface of the belt and the drive means is connected to a sprocket engaging the lugs of the first set of lugs.
11 A method of making a flexible endless belt according to claim 1 of predetermined length and having a multistrand single steel wire filament reinforcement and a set of lugs integral therewith, projecting from the outer surface thereof and distributed at a predetermined pitch along its length, the method comprising the following steps:
( 1) providing a multistrand single steel wire filament reinforcement about an external wall of a central mandrel mold element having a circumference related to said predetermined length and corresponding to and for providing the inner surface of the belt.
( 2) surrounding the mandrel and the reinforcement with an annular outer ring mold element in a predetermined molding relationship, said ring mold element having an internal endless wall corresponding to and for providing the outer surface of the belt and having substantially semi-ylindrical pockets therein distributed along its length at intervals corresponding to the, desired predetermined pitch of said set of lugs, each of said pockets providing an integrally formed lug projecting from said outer surface at the desired predetermined pitch and position, and said ring mold element internal wall and said mandrel mold element external wall being spaced apart when said mold elements are assembled in a molding relationship a distance corresponding to the desired thickness of the belt exclusive of projecting lugs and together forming a mold cavity, and ( 3) filling the mold cavity with plastics material.
12 A method according to claim 11, wherein the reinforcement is provided on said central mandrel mold element by winding a number of turns of wire filament about said external wall of the central mandrel mold element.
13 A method according to claim 12, in which said wire filament is wound on said mandrel with a tension of at least 0 1 pound.
14 A method according to either claim 12 or claim 13, in which said wire filament is wound in a single layer across substantially the entire width of said belt.
A method according to any one of claims 11 to 14, in which step 3 is carried out in an evacuated chamber.
16 A method according to any of claims 12 to 15, in which said mold is filled with urethane polymer and the wire filament is coated with a primer for improving its adhesion with the urethane polymer.
17 A tractor belt substantially as herein described, with reference to the accompanying drawings.
18 A tractor mechanism substantially as herein described with reference to the accompanying drawings.
19 A method of making a tractor belt substantially as herein described with reference to the accompanying drawings.
A A THORNTON & CO Northumberland House, 303-306 High Holborn, London, WC 1 Printed for Her Majesty’s Stationery Office by the Courier Press, Leamington Spa, 1980.
Published by the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

GB35763/77A
1976-08-30
1977-08-25
Tractor belts

Expired

GB1570553A
(en)

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

US05/718,831

US4079633A
(en)

1976-08-30
1976-08-30
Tractor belt

Publications (1)

Publication Number
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GB1570553A
true

GB1570553A
(en)

1980-07-02

Family
ID=24887736
Family Applications (1)

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Title
Priority Date
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GB35763/77A
Expired

GB1570553A
(en)

1976-08-30
1977-08-25
Tractor belts

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US
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US4079633A
(en)

JP
(1)

JPS5330579A
(en)

CA
(1)

CA1065906A
(en)

DE
(1)

DE2738324A1
(en)

GB
(1)

GB1570553A
(en)

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1984-05-30
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1976

1976-08-30
US
US05/718,831
patent/US4079633A/en
not_active
Expired – Lifetime

1977

1977-08-25
GB
GB35763/77A
patent/GB1570553A/en
not_active
Expired

1977-08-25
CA
CA285,506A
patent/CA1065906A/en
not_active
Expired

1977-08-25
DE
DE19772738324
patent/DE2738324A1/en
active
Granted

1977-08-30
JP
JP10414977A
patent/JPS5330579A/en
active
Pending

Also Published As

Publication number
Publication date

US4079633A
(en)

1978-03-21

DE2738324C2
(en)

1988-03-03

JPS5330579A
(en)

1978-03-22

CA1065906A
(en)

1979-11-06

DE2738324A1
(en)

1978-03-02

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