AU608089B2

AU608089B2 - Mechanical drive

Info

Publication number: AU608089B2
Application number: AU24672/88A
Authority: AU
Inventors: Warren James Hancock
Original assignee: Johnson and Johnson
Current assignee: Johnson and Johnson
Priority date: 1987-11-10
Filing date: 1988-11-03
Publication date: 1991-03-21
Anticipated expiration: 2008-11-03
Also published as: AU2467288A

Description

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i COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Form S0 089 Short Title: Int. Cl: Application Number: Lodged: PI5333 10 November 1987 0 0 00 o 0 09 0so o000 0 0O 0 a o 00 o 6 so S00 0 00 t 4 0* Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT

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Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: JOHNSON JOHNSON One Johnson Johnson Plaza, New Brunswick, New Jersey, 08903-7001, United States of America WARREN JAMES HANCOCK GRIFFITH HACK CO.

71 YORK STREET SYDNEY NSW 2000

AUSTRALIA

Complete Specification for the invention entitled: MECHANICAL DRIVE The following statement is a full description of this invention, including the best method of performing it known to us:- 2303A/SD S s0033-2 0 r '1 r ~IYI .ll -i I iC;I This invention relates to mechanical drive means for conveyor belts and the like and more particularly relates to drive means for use in a class of material handling conveyors known as power and free conveyor systems.

Power and free conveyor systems are widely used for the collation and transfer of goods awaiting processing by the next element in a production line or prior to packaging.

Such conveyors are characterised in that the flow of driven components can be interrupted or disconnected temporarily from the driving member so as to allow accumulation or collation of separate driven elements. This type of motion is particularly important in a wide variety of material handling applications where counting and/or collating is critical for subsequent processing.

Typically such systems feature a loading point at which an independent mobile unit is loaded onto the conveyor "D o system. The mobile unit will then travel to a point where other similar units are waiting to be loaded prior to their return to the loading station. Commonly each of these 020 conveyor units is driven by independent mechanical connection to a drive system when they are required to move. Many mechanisms are available for the purpose but they suffer from over complication, poor reliability and t 9r t high cost.

The main disadvantage of such present methods is the it rigid connection made to the conveyor drive which is destructive during unexpected system stoppages. The nature of the rigid connection causes violent attachment of the 4 4 conveyor unit causing damage to both the drive element and the mobile unit. It also limits the speed at which these systems can operate and the range of mass inertias which can be addressed by this type of system.

Alternatively, many power and free systems systems rely either on complete decoupling from the drive system or power absorbing friction to effect the "free" state. The simplest examples of such conveyor systems are provided in the packaging industry where a powered roller conveyor carries 5408S/ls product up to a packaging station. When the movement of the product is interrupted or stopped, for example when it collides with some form of fixed abuttment, the rollers continue to rotate beneath the assembled product until the product is released when it begins to travel again. In such systems, where the roller continues to rotate beneath a stationary product, we have an example of a system employing power absorbing friction since there is frictional engagement between the driven rollers and the stationary product.

Another prior art approach, is provided where the conveyor elements such as rollers are mounted through a friction clutch to a sprocket which engages a drive chain.

The drive chain is continuously driven but when the product supported on the roller is held at a receiving station, the o friction in the clutch is insufficient to continue driving the roller and the clutch slips.

00 The present invention has been conceived out of the .00° 0 need to provide an effective system for high speed operation 0420 where high forces may be involved and high accelerations 0 required, for example, when the product is released after appropriate processing at a work station. What the invention seeks to provide is a simple, reliable recirculating conveyor drive overcoming the previously perceived problems.

According to the present invention, there is provided a drive system for use in conveying objects, the drive system 4( comprising an elongate drive member, means for mounting and driving the drive member to cause it to move in the elongate 30 direction relative to a conveying path, and a driven element for causing displacement of an object along said path, the driven element having means for applying a force transversely to the drive member and gripping the drive member whereby elastic deformation of either the drive member or the driven element is provided, the inter-engagement of the driven element and the drive member being such that when the load of the object on the driven 5408S/ls element is below a predetermined value the driven element and object are moved along with the drive member, and when the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element.

Preferably, there is provided a drive system for use in conveying objects, the drive system comprising an elongate elastically deformable drive member, means for mounting and driving the drive member to cause it to move in the elongate direction relative to a conveying path, and a driven element for causing displacement of an object along said path, the driven element having means for applying a force transversely to the drive member and gripping the drive member whereby elastic deformation thereof is provided, the inter-engagement of the driven element and the drive member o. being such that when the load of the object on the driven element is below a predetermined value the driven element and object are moved along with the drive member, and when ~the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element.

More preferably the driven element of the above drive system has means for applying a force transversely which comprises a pinch roller arrangement for gripping and causing elastic deformation of the drive member. Rotation of the pinch rollers when the load exceeds the predetermined value substantially avoids friction between the drive member and the driven element. Preferably the pinch roller arrangement is spring loaded so that uniform pressure is maintained by the pinch rollers on the drive member depite any changes in the diameter of the drive member resulting from changes in tension of the member (eg when the drive member is under high tension it will be drawn out resulting in a reduced diameter).

Thus the invention provides a mechanical drive from a longitudinal member to a secondary, independently moving element which applies a transverse force to the longitudinal member.

5408S/ls Such longitudinal members may comprise closed loops of belting, steel wire or linearly moving strips or plates of material. The secondary driven element supplies a lateral force with one or two rollers or other linear bearing system. A force is generated between the longitudinal member and the driven element when a relative motion in the longitudinal direction is enforced. The force is produced by virtue of the hysteresis in the longitudinal material rather than as a consequence of directly friction related sources.

By restraining the driven element against the driving force, the longitudinal member will freely pass by, producing a steady force against the restraint. Removing the restraint will allow the driven element to travel with the longitudinal system.

010In the present invention the "free" state of the driven 0element occurs whilst the driven element is still coupled to the driving member but no rubbing friction is involved. In a preferred embodiment, drive instead is imparted to the driven element (work holder or trolley) via the pinch o. P rollers which create a standing "wave" in the drive member (belt). If the material of the drive belt were perfectly elastic the energy to deflect the belt would be returned 0. without loss as the material of the belt passes between the 0 04 .o 25 rollers.

In an imperfect material with losses (hysteresis) the difference in deflection energy of the drive belt from one o side of the pinch roller to the other provides the driving roo force to the work holder or trolley. Thus an internal ,30 energy loss provides the drive to the separate driven elements without rubbing friction.

This transmission therefore provides a reliable, consistent driving force for the motivation of individual conveyor units (trolleys or workholders). By restraining the conveyor units with a force greater than their driving force, they will maintain a constant pressure on the restraint until released.

5408S/ls

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In the alternate, there is provided a drive system for use in conveying objects, the drive system comprising an elongate drive member, means for mounting and driving the drive member to cause it to move in the elongate direction relative to a conveying path, and an elastically deformable driven element for causing displacement of an object along said path, the driven element having means for applying a force transversely to the drive member and gripping the drive member whereby elastic deformation thereof is provided, the inter-engagement of the driven element and the drive member being such that when the load of the object on the driven element is below a predetermined value the driven element and object are moved along with the drive member, and when the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element.

More preferably the driven element of this alternative system has means for applying a force transversely which comprises a pinch roller arrangement for gripping the drive member. However unlike the earlier embodiments such S gripping will cause elastic deformation of the pinch rolls themselves rather than the drive member. Again rotation of the pinch rollers when the load exceeds the predetermined value substantially avoids friction between the drive member %625 and the driven element. It will be appreciated that the size of the pinch rolls in this arrangement may be larger relative to the drive member than for the earlier described embodiments.

For illustrative purposes only an embodiment of the S 30 present invention will now be described with reference to the accompanying drawings of which: Figure 1 is a schematic representation of the main principle of the invention; Figure 2 is an overall perspective view of a material handling conveyor, comprising a mechanical drive means being an embodiment of the present invention; Figure 3 is a detail of a workholder used in the 5408S/ls c conveyor system of Figure 1; Figure 4 is a detailed side elevation of the workholder illustrated in Figure 3; Figure 5 is an end elevation of the same workholder in detail; Figure 6 illustrates the drive pulley portion of the material handling conveyor of Figure 2; and Figure 7 illustrates the mechanism for unloading the workholders illustrated in Figures 3 to The principle of the invention is illustrated in Figure 1. In ihis illustration the longitudinal drive member 1 is an elastomeric belt of circular cross-section. In normal operation the drive belt 1 runs around the pulleys 2 and 3 and carries the driven element 4 with it by virtue of the pinch rollers 26 and 27 exerting transverse forces (lateral Ssqueeze) which elastically deform the belt i. As a result 0 of driving the belt 1 by drive pulley 2, the belt 1 imparts 0. a longitudinal driving force to the pinch roller (driven o unit) unit 4. However, when the product supported on the 00-20 work holder attached to the driven unit 4 reaches an end .000 Vo 0 stop or the like (not illustrated), thc load exceeds the Svalue at which the belt will elastically deform and it slips through between the pinch rollers 26 and 27. The pinch rollers rotate thereby avoiding friction.

Co 25 Although the schematic drawing shows circular drive pulleys in fact the pulleys 2 and 3 are notched at regular intervals around the periphery to accommodate the lower of 4 the pair of pinch rollers 26 so that the work holder (not illustrated) on which the pinch roller unit 4 is mounted is moved with the pinch rollers 26 and 27 and moves around the periphery of the pulleys 2 and 3 during normal operation.

The work holder will have attached thereto a suitable structure for supporting product up to a station near the downstream one of the two pulleys 2 and 3 shown in the drawing.

Referring specifically to Figure 2 there is illustrated an embodiment of the present invention which is a conveyor 5408S/ls -7system 14 to convey product 11ii, in this case folded nappies, which are arriving at the output end of a manufacturing line to transport and collate them for transferral to a packing machine.

The loading station 13 comprises an indexing wheel 18 around the periphery of which are notches 19. On one side of the indexing wheel 18 are mounted rotatable pulleys which support the drive belt 21. Workholders 17 are attached to and demountable from the drive belt 21 by means of pulleys 26 and 27 (more fully illustrated in Figures 3 to Above the loading station 31 is a pair of belt conveyors 15 and 15' which feed product to the workholder 17 when appropriately indexed.

The drive belt 21 passes round the pulleys 22 and 23 and around drive wheel 24. Drive wheel 24 is provided with s notches 25 in the perimeter thereof to accommodate the lower pulley 26 of the workholder 17. This is more fully 9o illustrated in Figure 6 in which a drive wheel entry cam Poo. is located near the periphery of drive wheel 24 and is vp'20 driven by belt 42. An escapement wheel 40 is provided cro o o adjacent drive belt 21 having notches 43 to accommodate the lower pully 26 of workholder 17.

An unloading station 34 comprises a rotating belt 28 to t, which are attached paddles 29 (illustrated in detail in 25 Figure 7).

Referring to Figures 3 to 5 there is illustrated in detail the attachment of the workholder 17 to the drive belt ~21. The workholder 17 for product 11, is mounted on a pulley support bracket 38. Three guide pulleys 37 are mounted on the bracket 38 and engage with guide rails 35 to allow the work holder 17 to follow a set path. As shown in Figure 4 pulleys 26 and 27 apply a transverse force to drive belt 21. A quick release plunger 36 allows disengagement of the trolley from the belt 21 if necessary.

Referring again to Figure 4, when the trolley support bracket 38, is otherwise unrestrained, it will travel in the direction of arrow 40 by virtue of its engagement with the 5408S/ls Csurr~li; i I drive belt 21 provided by the pulleys 26 and 27 exerting a force thereon. Upon restraint of the support bracket 38, the pulleys 26 and 27 will cause deformation of the drive belt, producing a standing wave comprising relatively thickened compressed belt material at locations 39. This in turn will cause the pulleys 26 and 27 to rotate thereby allowing the belt 21 to pass through without rubbing friction.

Referring generally to all the Figures, in operation the drive belt 21 is driven by the drive wheel 24 which has a series of notches 25 to accommodate the lower pulley 26.

The pulleys 26 are fed into the continuously rotating drive wheel 24 by means of an escapement and timing cam system 40,41.

The escapement wheel 40 operates intermittently according to the presence of a pulley 26 and the appropriate ,0 position of the drive wheel 24. When actuated the escapement wheel 40 indexes, releasing one workholder 17 whilst restraining any following workholders.

t# i The released workholder 17 then enters into the region of the drive wheel entry cam 41, which is driven directly Sfrom the drive wheel 24 through a break-away clutch (not illustrated). The break-away clutch operates if any malfunction of the trolley or system timing causes a heavy interference. A brake causes the cam 41 to stop and a t 4I S sensor indicates that a failure has occurred should this take place.

The drive wheel entry cam 41 is designed to capture the workholder 17 and smoothly accelerate it to drive wheel speed prior to engaging the workholders with the corresponding notch 25 in the drive wheel 24.

Once the trolleys have passed the drive wheel 24 they return via the lower track to the loading station marshalling area 30 where workholders 17 accumulate prior to being positioned on the index wheel 18. The index wheel 18, which is driven independently of the drive belt 21, will pick up a trolley 17 each time a notch 19 is coincident with 5408S/ls -9i I i the lower pulley 26 of the workholder 17. The index wheel 18 will itself prevent further trolleys 17 from moving forwards unless there is a notch 19 available into which the lower pulley 26 of a work holder 17 can fit.

Restraint of the trolley 17, here provided by the absence of a notch 19 in index wheel 18, will cause the belt 21 to be pulled between the pinch rollers 26 and 27 thereby causing the pinch rollers to rotate. Once the trolley 17 is engaged with the index wheel 18, it will proceed to travel with the index wheel 18, until the index wheel itself is stopped at loading position 31. The continuously driven belt 21 will pull between the pinch rollers 26 and 27 when the index wheel 18 is stopped on reaching the loading position 31 where the trolley 17 will receive product 11 from the feed conveyors 15 and 15'. Product 11 arrives in the direction of arrow 12 from the output end of a o production unit (not illustrated), being transported to the "o loading station 13 of the conveyor system 14 by means of a pair of belt conveyors 15 and 15' between which is sandwiched the product 11. When the drive belts 15 and St are each caused to move in the direction of arrows 16 and 16', product 11 is fed to the workholder 17.

On further rotation of the index wheel 18, the trolley *ooO, 17 will be free to travel away with the continuously driven 0: 25 belt 21 towards the marshalling area 32. A mechanical stop, Snot shown, at marshalling station 32 causes the trolleys 17 to stop, thereby allowing the driven belt 21 to again be Sdrawn through the pinch rollers 26 and 27. When sufficient O trolleys 17 have been accummulated the mechanical stop is %le 30 released and the trolleys 17 are free once again to travel with the belt 21 in a grouped formation. The group of trolleys 17 proceed to the transfer station 34 where they are again mechanically stopped (not shown), the belt 21 being pulled between the pinch rollers 26 and 27 causing them to rotate. The unloading belt 28 is caused to rotate allowing paddles 29 to knock product 11 out of the workholders 17 into a suitable chute (not shown) where they 5408S/ls -i0- 06002 4 0 00 0 00i 0 0 0000 os 0 020O 1 4 4 t 44t 1 44 4t 4 4. 44( are received by the packaging machine, not illustrated.

The advantages of the present system, particularly as illustrated, are: low cost of manufacture, very quiet operation, provides versatility for detailed design, the drive is unaffected by dirt or oil on the belt since the drive force is derived from internal material properties capable of change of direction of the belt including moving round pulleys which are disposed in a horizontal plane, smooth and uniform operation with regard to a workpiece, and the ability to generate high acceleration forces when the workpiece is released.

This concept can be employed with a variety of materials in many applications. Particularly it is possible to employ the same principal in different configurations. A hydrostatic bearing squeezing a steel plate would provide a drive under this principle. It is equally valid for the transverse force to be tensile as in the case of rollers stretching an elastomeric tube from the inside.

It will be readily understood by a person skilled in the field that the invention is not limited to the embodiments described above but many other arrangements will fall within the scope of the invention.

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Claims

1. A drive system for use in conveying objects, the drive system comprising an elongate drive member, means for mounting and driving the drive member to cause it to move in the elongate direction relative to a conveying path, and a driven element for causing displacement of an object along said path, the driven element having means for applying a force transversely to the drive member and gripping the drive member whereby elastic deformation of either the drive member or the driven element is provided, the inter-engagement of the driven element and the drive member being such that when the load of the object on the driven element is below a predetermined value the driven element and object are moved along with the drive member, and when the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element.

S2. A drive system for use in conveying objects, the drive system comprising an elongate elastically deformable drive member, means for mounting and driving the drive member to cause it to move in the elongate direction 4 1 relative to a conveying path, and a driven element for causing displacement of an object along said path, the driven element having means for applying a force 4 44 transversely to the drive member and gripping the drive member whereby elastic deformation thereof is provided, the inter-engagement of the driven element and the drive member being such that when the load of the object on the driven element is below a predetermined value the driven element and object are moved along with the drive member, and when the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element.

3. A drive system according to claim 2 in which the means for applying a force transversely to the drive member comprises a pinch roller arrangement for gripping and causing elastic deformation of the drive member, whereby 5408S/ls -12- rotation of the pinch rollers when the load exceeds the predetermined value substantially avoids friction between the drive member and the driven element.

4. A drive system according to claim 3 in which the pinch roller arrangement is spring loaded so that uniform pressure is maintained by the pinch rollers on the drive member depite any changes in the diameter of the drive member resulting from changes in tension of the member.

A drive system for use in conveying objects, the drive system comprising an elongate drive member, means for mounting and driving the drive member to cause it to move in the elongate direction relative to a conveying path, and an elastically deformable driven element for causing displacement of an object along said path, the driven element having means for applying a force transversely to the drive member and gripping the drive member whereby elastic deformation thereof is provided, the inter-engagement of the driven element and the drive member ,being such that when the load of the object on the driven element is below a predetermined value the driven element t and object are moved along with the drive member, and when the load exceeds a predetermined value the drive member moves along in the direction of said path relative to said driven element. 4

6. A drive system according to claim 5 in which the means for applying a force transversely to the drive member comprises a pinch roller arrangement for gripping the drive S member, such that gripping will cause elastic deformation of the pinch rollers themselves rather than the drive member, whereby rotation of the pinch rollers when the load exceeds the predetermined value substantially avoids friction between the drive member and the driven element.

7. A drive system for use in conveying objects substantially as disclosed herein in conjunction with the drawings. DATED 2nd day of November, 1988 JOHNSON JOHNSON By Their Patent Attorneys GRIFFITH HACK CO. 5408S/ls -13-