US3830353A

US3830353A - Method and apparatus for effecting article transfer through the use of magnetic fields

Info

Publication number: US3830353A
Application number: US00220968A
Authority: US
Inventors: W Mojden
Original assignee: Fleetwood Systems Inc
Current assignee: Fleetwood Systems Inc
Priority date: 1971-03-01
Filing date: 1972-02-07
Publication date: 1974-08-20
Anticipated expiration: 1991-08-20

Abstract

Method and apparatus for effecting the transfer of articles from one traveling belt to another belt disposed transversely thereto, without the employment of guide rails, or the like to produce said transfer. The transfer operation is effected by the controlled application of magnetic forces.

Description

[ Aug. 20, 1974 United States Patent [191 Mojden [56] References Cited UNITED STATES PATENTS METHOD AND APPARATUS FOR EFFECTING ARTICLE TRANSFER 8 mu MUM 2 O Y me .m M u "m nnm 0U CBM 070 937 0099 HHH 500 0 2 640 93 472 23 w m a m m N H G n A e M m. F 0 0 M E S W U a E a H u a T w w U n o m R m Hm v TF .m

Primary Examiner-Richard A. Schacher Assistant Examiner-Douglas D. Watts [73] Assignee: Fleetwood Systems, Inc.,

Countryside, Ill.

Attorney, Agent, or Firm-Olson, Trexler, Wolters, Bushnell & Fosse, Ltd.

[22] Filed:

Feb. 7, 1972 21 Appl. No.: 220,968

[57] ABSTRACT Method and apparatus for effecting the transfer of ar- Related US. Application Data [63] Continuation of Ser. No. 119,506, March I,

abandoned [52] US. 198/20 R, 198/41 [51] Int. B65g 47/00 operation is effected by the controlled application of a w m m w a P D 9 5 m w m C C 8 r. m c H e n g a m 6 R 1 3 n 5 7 l 92 W O 2 2 1 4 0O 9 1 h m a e S f. 0 d l. e .1 F l. 00 5 METHOD AND APPARATUS FOR EFFECTING ARTICLE TRANSFER THROUGH THE USE OF MAGNETIC FIELDS REFERENCE TO RELATED APPLICATION This application is a continuation of application Ser. No. 119,506, filed Mar. 1, 1971 and entitled METHOD AND APPARATUS FOR EFFECTING ARTICLE TRANSFER, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to magnetic conveyor apparatus. More specifically, this invention is concerned with a novel transfer method and arrangement wherein the cans are transferred from one traveling belt to another belt, disposed transversely thereof,

using only magnetic forces.

Magnetic conveyors are in wide use today by can manufacturers and others utilizing can bodies as container mediums. In many instances, the cans used are of the type wherein the product trade dress is applied by a lithography process prior to filling and packaging. With lithographed cans, it is desirable to employ a conveyor system that is free of bends and sharp turns in order to insure against damage to the can surfaces. However, quite often the physical plant layout, as well as the nature of the operations to be performed, are such that the conveyor system cannot avoid abrupt changes in direction. Accordingly, it is not uncommon for a manufacturer to find numerous cans wherein the lithography has become scratched or otherwise marred after processing and transporting over the length of the conveyor system.

The primary cause or source of damage to the lithography is the manner in which the various turns and bends in the conveyor system are negotiated. More specifically, the the general construction of the apparatus in use today is such that curved guide rails are employed in conjunction with transversely oriented traveling belts. With this arrangement, the cans are forcibly moved through the turns and transferred from one belt to the other by the back pressure created from the downstream flow of can bodies. Accordingly, the cans are subject to damage from two sources; namely, engagement with each other and engagement with the guide rails.

With the present invention, the above-discussed disadvantages of the prior art systems are eliminated. That is to say, the various turns and changes in direction that must be undergone in a conveyor system are negotiated without the use of guide rails and without bunching or collecting of the can bodies at the transfer location and without the resulting employment of back pressure to effect movement of the cans to the receiving belt. In addition, the spacing between can bodies is maintained, which is often important and required by the machinery receiving the cans for the subsequent processing or packaging operation. Basically, these advantages are realized by utilization of a novel arrangement wherein a magnetic field is established at the transfer point which is effective to forcibly convey the can bodies from one traveling belt to the other without the employment of any side guides or the like. It should be noted however, that guide rails may be employed as a safety factor when the transfer is taking place at a location spaced above personnel, a walkway, or machinery which could be fouled by a can body. But even when guide rails are used, the cans will negotiate the turns without engaging the guide rails, under normal operating conditions.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a transfer location for a conveyor system constructed in accordance with the present invention;

FIG. 2 is a top, plan view of the transfer location of FIG. 1, illustrating in phantom, the positioning of magnetic means for the respective conveyor sections;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2, in the direction indicated;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2 in the direction indicated;

FIG. 5 is a partial, sectional view taken along the line 55 of FIG. 2 in the direction indicated;

FIG. 6 is a partial, sectional view of the incoming conveyor, taken along the line 66 of FIG. 2, and including a schematic graph of the magnetic field provided in the transfer area;

FIG. 7 is a top, plan view of an alternate form of magnetic arrangement for the receiving belt.

FIG. 8 is a sectional view of the'magnetic arrangement of FIG. 7, and including a graph of the magnetic field created by this arrangement; and

FIG. 9 is a sectional view taken along the line 9-9 of FIG. 8 in the direction indicated.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to the drawings, in FIG. 1 there is illustrated transfer apparatus constructed in accordance with the present invention, and designated generally 10. The transfer apparatus 10 is comprised of a pair of transversely disposed conveyor units 12 and 14. Conveyor unit 12 functions as the incoming section of the apparatus 10, in that the cans 16 are initially being transported by this section. Conveyor unit 14, on the other hand, is the receiving section of the apparatus 10, the cans 16 moving off of unit 12 onto unit 14, as shown, said movement being effected by the novel magnetic transfer arrangement of the present invention, which will be described in more detail hereinafter.

In the illustrated embodiment of this invention, both conveyor units 12 and 14 are of generally similar construction. As such, unit 12 will be described in detail with reference to FIG. 2. In order to avoid unnecessary structural recitation, the same reference characters primed are applied to the corresponding elements of conveyor unit 14.

More specifically, the unit 12 includes a nonmagnetic housing 20 having

guide rollers

22 and 24 at 1 opposite ends thereof. If desired, additional rollers may to one of the guide rollers, roller 22 in this instance, in

order to provide the necessary operating power. In addition, there is provided a stationary magnetic arrangement 34 which is disposed within housing 20 in underlying relation to the upper belt'reach 28 so as to establish a magnetic field of sufficient strength to maintain cans 16 in proper position on belt 26.

in 'FIG. 5. This magnetic arrangement 34 includes a number of sections or segments of ceramic, magnetic material 42 which are positioned in end-to-end relation to define an elongate assembly. Mounted in abutting relation tothe sides of the ceramic magnetic sections I 42 are a pair of spaced,

elongate pole plates

44 and 46, which are magn etizable metal and positioned to underlie closely the upper surface 30 of housing 20. These

pole plates

44 and 46 function as the south and north poles, respectively, of the magnetic arrangement 34 and are narrow in width, with respect to the width of the ceramic magnetic section 42. This construction provides a focusing effect for the field of flux lines 48 which comprise the magnetic field produced by the arrangement 34. Accordingly, as the belt 28 is traveling over the upper surface 30 of the housing, the magnetic field 48 will act upon the can bodies 16 to maintain them in proper position and to resist any tendency of the cans to topple or move transversely of the belt surface.

The magnetic arrangement 34', for the conveyor unit 14, is of a different construction from the arrangement 34 of conveyor unit 12. Primarily, the magnetic arrangement 34 is comprised of a first section 50 and a second section 52 spaced from the transfer zone 40 as illustrated in FIG. 2. The construction of the firstsection 50 is illustrated in FIGS. 3 and 4, and, as will be discussed hereinafter, this first section 50 extends at least to the edge of the transfer zone 40. It is the magnetic field created by the section 50 that produces the movement of the-can ends from belt 28 to the transversely disposed belt 28, as illustrated. A construction of the'second section 52 will be alluded to only briefly, and it should be noted that this section may be constructed in a manner similar to the magnetic arrangement 34, as described previously with reference to FIG.

Directing attention to FIGS. 2 and 6, it can be seen that the

pole plates

44 and 46, for the magnetic arrangement 34, terminate at approximately the edge of zone 40, the ceramic magnetic elements 42 being spaced a distance from said zone. The first portion 50 of the magnetic arrangement 34', on the other hand,

extends into this zone 40. This arrangement represents a preferred form of the invention, and one found to work well in practice; however, it is envisioned that alternate constructions may be employed to attain the desired operation, such as that shown ln FIGS. 7-9, to be discussed hereinafter. I

Basically, in conveying can bodies, it is desirable to maintain the can bodies under the influence of a magnetic field at all times in order to prevent toppling or transverse movement of the bodies. In order to effect transfer of the cans 16 from the traveling belt 26 to the belt 26", without the use of guide rails and while maintaining the cans under the influence of a magnetic field, it is necessary that the strength of the magnetic field, created by the first section of arrangement 34', be stronger than the magnetic field produced by arrangement 34 in the zone 40. It is also desirable to have the strength of the magneticfield 34 diminish in the zone 40. In addition, the magnetic field produced by arrangement 34', must be of a control form so as to attain the desired transfer action without producing toppling of the can bodies 16. With this in mind, attention is now invited first to FIG. 6 and then to FIGS. 3 and 4 wherein preferred constructions of the magnetic arrangement 34 and first magnetic section 50 for arrangement 34 are illustrated.

As can be seen from FIG. 6, the end of the ceramic magnetic element 42 is spaced from the non-metallic conveyor housing 20 and, correspondingly, is spaced a distance from the'transfer zone 40. The

respective pole plates

44 and 46, however, extend beyond the end of the magnet means 42 to approximately the edge of the transfer zone 40, note FIG. 1. As a result of this construction, the strength of effectiveness of magnetic field 48, represented by the dashed-line graph of FIG. 6, will diminish in a direction towards the zone 40. This particular arrangement is preferred to facilitate the transfer operation. That is to say, the decreasing strength of field 48 enables the field produced by the hereinafter to be discussed magnetic section 50, to effect the transfer operation smoothly and without mishap.

Considering FIG. 3 next, there is illustrated a transverse, sectional view of the aforementioned first section 50, and it can be seen that the general arrangement is somewhat similar to that described with reference to FIG. 5. More specifically, the first section 50, of the magnetic arrangement 34, is comprised of two series or stacks of ceramic, magnetic elements 54. The respective stacks 54 are mounted within a U-shaped, non-magnetic housing 55 and rest upon a back plate 56 formed of steel or some other magnetic material. The back plate 56 forms a segment of the magnetic circuit linking the stacks 54. In addition, the stacks 54 are separated by a central spacer 58 which also rests upon the back plate 56 and is constructed of wood or some other non-magnetic material. The entire assemblage is held in place by a bolt arrangement 60, as illustrated, said arrangement 60 also being constructed of a nonmagnetic material or otherwise properly shielded so as not to interfere with the magnetic circuit existing between the stacks of ceramic, magnetic elements 54. As such, the individual stacks of magnetic elements 54 and back plate 56 function and may be viewed as a U- shaped magnet.

In order to focus, and otherwise control the magnetic field thus produced by the stacked magnetic elements 54, a pair of

elongate pole plates

62 and 64 are used, one being mounted atop each stack, as illustrated.

Respective pole plates

62 and 64 are disposed between the upper surface of the ceramic, magnetic elements 54 and the surface 30' of the non-magnetic housing 20'. Accordingly, there is produced a magnetic field designated generally 66 which extends between the

respective pole plates

62 and 64, and intersects the can bodies 16 being carried by the belt 28' to maintain these bodies in position thereon.

Turning now to FIG. 4, and keeping in mind the general construction of the magnetic section 50 as discussed above, this figure illustrates a longitudinal, sectional view of said section 50. Accordingly, in conjunction with FIG. 4, the transfer operation and the function of the section 50 of the magnetic arrangement 34 in this operation will now be discussed. FIG. 4 is a view taken through the transfer zone 40 which, it will be recalled, is the location wherein the upper reaches 28 and 28' of the respective traveling

belts

26 and 26 overlap. When a can first enters the zone 40, it will be under the influence of the magnetic field 48 created by the magnetic arrangement 34 of conveyor 12. However, as can 16 progresses into the zone, the effect of field 48 lessens as illustrated in FIG. 6, and the can commences to be influenced by the field 66 produced by section 50 of the magnetic arrangement 34. Continued advancement increases the force exerted on the can by field 66 causing the can body to move transversely toward the edge of the belt 28. This movement of the can 16 off belt 28 is realized due to the increased strength of the field 66, in conjunction with the decrease in the strength of field 48. Accordingly, once the magnetic field 66 overcomes the effect of field 48, the cans will be forcibly moved off of the traveling belt 26 and onto the upper reach 28' of the belt 26.

A graph of the strength of the field 66 produced by the magnetic arrangement 34' is illustrated in FIG. 4 and designated generally 70. It should be noted, that this graph is schematic, and is divided up into four separate sections labeled A-D" which may also be viewed as corresponding to the underlying zones or areas of the transfer apparatus.

In the area of section A, there exists a flux gradient for the magnetic field 66, in that said field is not at its ultimate strength, which is not attained until some point within section B of the graph. This gradient under section A, is achieved due to the fact that the

pole plates

62 and 64 extend beyond the ends of the magnetic section 50, as shown in FIG. 4.

Accordingly, as the cans 16 come under the influence of the magnetic field 66 in zone 40, the transversely disposed orientation of this field exerts a pulling force on the can bodies, moving them across the belt reach 28 toward the edge thereof. This effect of the magnetic field 66 gradually increases as the can bodies 16 progress into the zone 40, until the effect of the magnetic field 48 is completely overcome. At this time, the flux gradient existing in zone A forcibly will move the can bodies 16 toward the area of higher flux strength, corresponding to the section B of the graph 70. When an equalized state is reached, the can 16 will be in zone B with its base resting entirely upon the upper reach 28' of belt 26' or, alternately, the cans will have been moved to a position wherein a significant portion of their bases rest on the belt 28. In both instances, the frictional forces created by engagement of the can bodies with the traveling upper reach 28' will facilitate, if not complete, the transfer operation.

It should be noted, that this transfer operation is attained entirely with the controlled application of magnetic forces, there being no guide rail, or the like, used which could engage and damage the lithograph material on the can body.

Once the can body is properly positioned on the traveling belt reach 28, there is no longer any need for the increased strength of the magnetic field 66 which corresponds to the section B of graph 70. Accordingly, it is contemplated that the strength of this field 66 is to be reduced and that this reduction is to take place gradually as indicated by section C of said graph. The final value to which the strength of field 66 is to be reduced is represented by section D of the graph and is of sufficient strength to maintain the can bodies in position. In the illustrated embodiment, the magnetic field represented by section D of the graph, is attained by the aforementioned second section 52 of the magnetic-arrangement 34'.

In order to attain the gradual reduction in the strength of the field 66, as discussed above, the nonmagnetic housing 55 is provided with a tapered end wall 72, and the individual ceramic, magnetic elements 54 are positioned as illustrated in FIG. 4. In this regard, a non-magnetic spacer 74 is employed in conjunction with the lowermost ceramic elements 54. The

pole plates

62 and 64 may extend from the stacked ceramic, magnetic elements 54 of the first section 50 to the second section 52, wherein they overlie a ceramic magnet 76 which provides a magnetic field of considerably less strength than the stacked arrangement of section 50.

In summary, the method of transfer employed by the present invention may best be characterized as follows:

the can bodies 16 are initially handled by the conveyor unit 12 with proper positioning being maintained by the field 48 of the magnetic arrangement 34; next, as the cans 16 enter the transfer zone 40, the influence of field 48 is reduced, such that said cans will be subjected to the magnetic field 66; this field 66 is of a strength greater than the field 48 and of a controlled form or shape wherein a flux gradient is created that forcibly moves the can bodies 16 transversely of the belt 26 and off said belt onto the upper reach 28 of the traveling belt 26'; once on belt 26, that portion of field 66, created by section 52 of magnetic arrangement 34, maintains the cans in position.

FIGS. 7-9 illustrate an alternate construction for the initially magnetic segment of the receiving conveyor. This arrangement may be employed in place of the previously discussed magnetic portion 50, and is designed to provide a more controlled and defined flux distribution.

The magnetic section of FIGS. 7-9 is designated generally 80, and includes a number of ceramic magnetic elements 82, upon which are mounted

pole plates

84 and 86. The ceramic magnetic elements 82 are disposed within a nonmagnetic housing 88 which includes a truncated, rearward portion, discussed more fully hereinafter.

Abutting the rearward, truncated portion of the housing 88, is a magnetic section 90 identical in construction to the previously discussed section 52, shown in FIG. 5. That is, section 90 includes a ceramic magnetic element 92 having

pole plates

94 and 96 engaged against the sides thereof.

As was the case with the

sections

50 and 52 previously discussed, the strength of the field produced by section 90 is less than the maximum strength produced by magnetic section 80. Also, with the construction of section there is attained zones of varying flux strength similar to those previously discussed. As such, a graph of flux strength is included in FIG. 8 and identified as 100. This graph, like that employed in FIG. 4, includes four zones; i.e., zone A representing an increasing flux gradient employed in the initial stages of the transfer operation; zone B, the zone of maximum flux strength; zone C, a transition zone; and zone. D,

representative of the strength of the magnetic field employed to maintain the cans on the conveyor belt after transfer is completed.

As a practical matter, the construction of the magnetic section 80 is such as to minimize the problems encountered in moving a can body from a zone of high magnetic strength, zone B, to a zone of lower magnetic strength, zone C. If this transition is too abrupt, opposing forces are created which tend to hinder can movement. That is, the bottom of the can is being engaged by the traveling belt 26', while the prevailing magnetic flux tends to prevent movement of the can out of the zone of maximum strength.

To attain the aforementioned gradual transition, several innovative changes are utilized. More specifically, the forward portion of section 80 is comprised of two stacks, 102 and 104, of ceramic, magnetic elements 82, as shown in FIG. 9. Interposed between said

stacks

102 and 104 is a non-magnetic spacer 106, while the spacer 106 and said stacks rest on a magnetizable back plate 108. This back plate 108 completes the magnetic circuit between the respective stacks, and in conjunction with spacer 106, produces what may be considered a U-shaped or horseshoe magnet effect.

As can be seen from FIG. .8, the rearwardmost portion of section 80 is comprised of a reduced number of magnetic-elements 82, a pair of spaced elements 82 being shown in the illustrated embodiment. The rearwardmost elements 82 are also provided with an edge 109 out on a bias, which configuration facilitates the desired gradual reduction in magnetic strength from zone B to zone D. In addition, a magnetized back plate 110 is employed with this rearward portion. However, to prevent a shunting of the respective magnetic circuits, a nonmagnetic spacer element 112 is interposed between said plate 110 and the

stacks

102 and 104. Also, a rear spacer element 114 is used for a similar purpose with regard to magnetic element 92 of section 90. Further, it should be noted that the

pole plates

84 and 86 also are cut on a bias, such that they narrow in the area of engagement with the magnetic element or elements of said rearward portion. This narrowing of the

pole plate

84 and 86 and the rearward magnetic element 82, in conjunction with the employment of a reduced number of said elements 82 in said rearward portion, permits the attainment of a gradually reducing flux gradient represented by zone C. Accordingly, the

It is to be understood, that the specific arrangement, construction and method of operation of the embodiments illustrated in FIGS. l-9, represent but perferred forms of the present invention. As such, those skilled in the art, equipped with the present disclosure, may readily devise alternate arrangements to perform the same function as the present invention. For example, in place of the illustrated arrangement wherein the disposition of the north and south poles of the respective

magnetic arrangements

34 and 34, with regard to the path of travel, remains constant after transfer is completed. It is envisioned that it will be possible to employ an alternate construction wherein the disposition of the north and south poles for the arrangement 34' are reversed. In this regard, both arrangements 34 and 34' would extend into the transfer zone. This alternate embodiment is but one of many variations that may be employed, said variations being too numerous to elaborate upon. However, insofar as any alternate embodiments or variations fall within the spirit and scope of the present invention, as defined by the claims appended hereto, they are contemplated.

What is claimed is:.

1. Transfer apparatus for a magnetic conveyor system for articles, or the like, wherein the direction in which articles are traveling is to be altered, said apparatus including first conveyor means upon which the articles are initially to be conveyed, and second conveyor means to which the articles are to be transferred disposed transversely to and intersecting the path of travel of said first conveyor means, said first and second conveyor means including, respectively, first and second traveling endless belts upon which the articles can be supported, the upper reach of said first belt closely overlying the upper reach of said second belt, the area of overlap of said upper belt reaches defining a transfer transition from zone B to zone D can be made smoothly and without disruption of can movement.

area, and magnetic means disposed beneath the upper reach of said second belt and extending in a direction from said transfer area along the path of travel of said second belt, said magnetic means producing a magnetic flux distribution that is effective to cause articles to move off said first traveling belt and on to said second traveling belt.

2. Transfer apparatus according to claim 1 wherein said first conveyor means also includes magnetic means for retaining articles in position thereon.

3. Transfer apparatus according to claim 2 wherein said magnetic means for said second belt include a first segment and a second segment, said first segment having a portion thereof extending beneath said transfer area, and producing a stronger magnetic field than said second segment and the magnetic means for said first conveyor means.

4. Transfer apparatus for a magnetic conveyor system for can bodies or the like, wherein the direction in which can bodies are traveling is to be altered, said apparatus including a first conveyor assembly upon which the cans are initially being conveyed, and a second conveyor assembly to which the cans are to be transferred, said conveyor assemblies including, respectively, first and second driven endless belts upon which the can bodies are supported, the upper reach of said first endless belt closely overlying the upper reach of saidsecond endless belt, and being disposed transversely to said second belt, the area of overlap of said belts defining a transfer area; and magnetic means disposed beneath portions of the upper reaches of said belts to maintain the can bodies in position thereon, with the magnetic means for the second belt underlying said second belt in the vicinity of said transfer area and extending from said transfer area along said second belt, with said magnetic means for said second belt producing a magnetic field extending into said transfer area, and having a flux gradient increasing in the direction of travel of said second belt, at least for a portion thereof, to cause the can bodies to move off said first belt and on to said second belt.

5. Transfer apparatus as defined in claim 4 wherein said magnetic means for said second conveyor assembly include a first segment and a second segment, said first segment having a portion thereof extending beneath said, transfer area, and producing a stronger magnetic field than said second segment and the magnetic means for said first conveyor assembly.

means, with respect to the direction of belt travel, are identical.

8. Transfer apparatus as defined in claim 4, said magnetic means comprising one or more ceramic magnetic elements and a pair of elongate, spaced pole plates mounted thereon in underlying relation to the respective traveling belts, one said plate providing a north pole and the other a south pole.

Claims

1. Transfer apparatus for a magnetic conveyor system for articles, or the like, wherein the direction in which articles are traveling is to be altered, said apparatus including first conveyor means upon which the articles are initially to be conveyed, and second conveyor means to which the articles are to be transferred disposed transversely to and intersecting the path of travel of said first conveyor means, said first and second conveyor means including, respectively, first and second traveling endless belts upon which the articles can be supported, the upper reach of said first belt closely overlying the upper reach of said second belt, the area of overlap of said upper belt reaches defining a transfer area, and magnetic means disposed beneath the upper reach of said second belt and extending in a direction from said transfer area along the path of travel of said second belt, said magnetic means producing a magnetic flux distribution that is effective to cause articles to move off said first traveling belt and on to said second traveling belt.

4. Transfer apparatus for a magnetic conveyor system for can bodies or the like, wherein the direction in which can bodies are traveling is to be altered, said apparatus including a first conveyor assembly upon which the cans are initially being conveyed, and a second conveyor assembly to which the cans are to be transferred, said conveyor assemblies including, respectively, first and second driven endless belts upon which the can bodies are supported, the upper reach of said first endless belt closely overlying the upper reach of said second endless belt, and being disposed transversely to said second belt, the area of overlap of said belts defining a transfer area; and magnetic means disposed beneath portions of the upper reaches of said belts to maintain the can bodies in position thereon, with the magnetic means for the second belt underlying said second belt in the vicinity of said transfer area and extending from said transfer area along said second belt, with said magnetic means for said second belt producing a magnetic field extending into said transfer area, and having a flux gradient increasing in the direction of travel of said second belt, at least for a portion thereof, to cause the can bodies to move off said first belt and On to said second belt.

5. Transfer apparatus as defined in claim 4 wherein said magnetic means for said second conveyor assembly include a first segment and a second segment, said first segment having a portion thereof extending beneath said transfer area, and producing a stronger magnetic field than said second segment and the magnetic means for said first conveyor assembly.

6. Transfer apparatus as defined in claim 4 wherein the magnetic means for the first conveyor assembly is constructed so as to produce a magnetic field of lesser strength than that of said magnetic means for said second conveyor assembly.

7. Transfer apparatus as defined in claim 4 wherein said magnetic means for the first and second conveyor assemblies are constructed and arranged such that the disposition of the magnetic poles of both magnetic means, with respect to the direction of belt travel, are identical.