Magnetized conveyor and chain links

A magnetic conveyor including chain links with article carrying portions having magnetized grommets or magnetic filler material dispersed throughout to impart magnetic properties to the conveyor chain for conveying ferro magnetic articles. Preferably, the chain links comprise a polymeric resin material with a magnetic filler material dispersed therein during the molding process. Magnetization to provide multiple poles allows a minimum amount of filler material to be used thereby resulting in a relatively small reduction in the strength of the chain.

BACKGROUND OF THE INVENTION 
The present invention relates to magnetic conveyor chain of the type used 
to convey articles in a path that may include inclines and more 
particularly to nonmetallic magnetized chain or roller chain having 
nonmetallic magnetized snap-on top plates used for these purposes. 
In many industrial applications it is often desirable to convey articles 
from one location to another by means of a travelling article carrying 
conveyor chain which supports the articles being conveyed. In situations 
requiring the transport of relatively tall articles it is often necessary 
to stabilize the products on the conveyor chain by using attachments to 
the chain which support the conveyed products and minimize the possibility 
of product tippage. Similarly, in situations requiring the transport of 
articles up or down an incline it is typically necessary to provide 
conveyor chain attachments of one type or another to prevent the conveyed 
products from slipping on the inclined portion of the conveyor. 
Products being conveyed may be of several different types and made of 
various materials. In those circumstances where products are made from 
ferro magnetic materials attempts have been made to provide some type of 
magnetic attraction between the products and the conveyor. Generally, 
prior attempts to provide this magnetic attraction have included mounting 
magnets beneath the conveyor chain to establish a magnetic field in the 
area above the conveyor chain where the transported products are located. 
While being relatively successful as far as improving the stability of the 
products of the conveyors in both horizontal and inclined situations, 
these previous attempts have several serious drawbacks. Provision of 
magnets beneath the conveyor chain results in the chain being pulled 
toward its wear strips by attraction of the product through the chain. 
This increases the frictional drag of the chain on the wear strips 
resulting in increased wear of the chain links and other conveyor members 
and increased power requirements to drive the chain. Also, pulsation of 
the conveyor has resulted in these systems. These prior attempts have also 
proved to be very expensive. 
Additionally, other attempts such as that shown in U.S. Pat. No. 3,871,510 
have included attachment of magnets to the article carrying portion of the 
conveyor links to impart magnetic properties to the links. These attemps 
suffer from the drawbacks of being time consuming and difficult to 
assemble and also require storage of many additional component parts. 
SUMMARY OF THE INVENTION 
The conveyor and chain link of the present invention overcome the drawbacks 
associated with presently known magnetic conveyors by including chain 
links with magnetized article carrying portions providing the requisite 
magnetic field to attract the conveyed products to the chain without 
increasing the frictional drag of the chain on the conveyor wear strips. 
According to the present invention a plurality of chain links are 
connected together in a conventional manner to form a conveyor. The links 
in which it is desired to produce a magnetic field for attracting conveyed 
products have magnetized particles or inserts in at least the article 
carrying portion of the conveyor. 
In one embodiment the relatively flat article carrying top portions of the 
selected links have at least one hole into which a magnetized grommet is 
placed to provide the required attractive force. The grommet can be made 
from a polymeric material that is injection molded to the appropriate size 
and shape to fit the hole in the chain link. Preferably, the grommet 
comprises a polymeric resin containing a ferro magnetic filler such as 
barium-ferrite in sufficient quantity to provide the desired magnetic 
characteristics. 
In another embodiment wherein the entire article carrying portion of the 
chain link itself is made of a polymeric material it may be more 
beneficial and advantageous from a manufacturing standpoint to include the 
ferro magnetic filler during the molding process of the article carrying 
portion itself to provide the necessary magnetic characteristics in a 
given individual application. It is also preferable to magnetize these 
particles in such a manner that a plurality of magnetic poles are 
established in the article carrying portion of the conveyor links to 
increase the magnetic field strength. Although one embodiment of the 
present invention can be used with metallic as well as nonmetallic links, 
nonmetallic links are preferred. Nonmetallic chain protects the conveyed 
articles from damage that can be caused by articles sliding along the 
chain during conveying. 
Regardless of the method used to impart the magnetic properties to the 
chain links, the resulting conveyor offers substantial advantages. As 
previously mentioned, frictional drag of the conveyor links against the 
conveyor wear strips is not increased because no additional forces are 
exerted on the links. Additionally, means for selectively neutralizing the 
magnetic field around the links as they pass a transfer point along the 
conveyor may be provided to more easily strip the products from the 
conveyor. However, stripping of products from the conveyor can also be 
accomplished without neutralizing the magnetic field because less force is 
required to slide the product off the conveyor than is required to lift 
the product from the conveyor. 
Another benefit possible in a conveyor constructed of chain links having 
magnetic inserts is to convey articles up and down relatively steep 
inclines without the use of special attachments of the chain links. In 
such applications the conveyor chain has a tendency to raise as it makes 
the transition from its horizontal to inclined path. To counteract this 
tendency the portions of the wear strip at the junction where the conveyor 
chain tends to raise may comprise a ferro magnetic strip to attract the 
chain to the strip thereby reducing the tendency of the chain to raise 
from its track.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, there is shown a chain link 10 of known 
configuration employing the principles of the present invention. The chain 
link 10 includes an article carrying portion 12 and two legs 14, 
integrally depending therefrom, connecting the eyes 15 of the link. The 
two holes 15 at the leading edge and one eye 16 at the trailing edge of 
the link 10 are formed so that the trailing eye 16 of one link 10 fits 
between the two eyes 15 on the leading edge of an adjacent link 10 to form 
a conveyor chain by connecting adjacent links 10 with chain pins in a 
conventional manner. The depending legs 14 preferably have outwardly 
extending projections or tabs 17 to engage wear strips on which the chain 
is supported in the conveying operation. 
The material from which the chain links 10 are made varies depending upon 
the environment in which the conveyor will operate. In many applications, 
metallic links are preferable while in other applications nonmetallic or 
polymeric links are preferred. The present invention maybe utilized with 
either type of link material. Additionally, snap-on top plates for 
attachment to a conventional roller chain may be magnetized in accordance 
with the principles of the present invention. 
The chain link 10 of FIG. 1 is shown as having two holes 19 in its article 
carrying portion 12. In each aperture 19 there is a magnetized grommet 20. 
The apertures 19 have a varying internal diameter. The grommets 20 are 
constructed with a varying outside diameter which permits the grommets to 
be placed in the holes 19 and locked in place. In the embodiment shown 
each grommet includes a large top surface, a smaller diameter central 
portion, and a sectioned tab portion 21 that is larger than the smallest 
internal diameter of aperture 19. When the grommet 20 is inserted into 
aperture 19, the tab portion 21 is radially compressed until it passes 
through the smallest internal diameter portion of aperture 19. When the 
large diameter bottom portion 21 of the grommet 20 has passed through the 
smallest part of hole 19, the tabs 21 return to their normal position. 
Thus, the grommet 20 is secured in position by its large top and bottom 
portions, both of which are larger than the smallest diameter portion of 
aperture 19. While the link 10 shown has two grommets 20, any desired 
number may be used. 
The holes 19 in the article carrying portion 12 of the links 10 are 
recessed near the upper surface of the link 10 so that the grommets 20 
when positioned in the holes 19 will be flush with that surface. 
In accordance with known techniques, the magnetized grommet 20 comprises a 
polymeric resin material such as a polyester or polyurethane with a 
magnetic filler material such as barium ferrite interspersed in the resin 
during the molding process. The magnetic filler material may be magnetized 
either during the molding process to produce a relatively high energy 
magnet or after the molding process to produce a relatively lower energy 
magnet. While high energy magnets may be desirable in some situations, it 
is believed that low energy magnets will suffice in most cases resulting 
in less expensive equipment being required to mold the magnetized grommets 
20. 
The size and quantity of magnetic grommets 20 required will vary depending 
upon the size, shape and weight of the articles being conveyed. In the 
present embodiment a variety of magnetic grommets 20 can be stocked and 
selectively supplied with the base chain links 10 according to the 
requirements of a particular conveying application. 
It should be apparent that the particular shape of the magnetized grommets 
20 may vary without departing from the scope of the present invention. For 
example, the link can be magnetized over its entire surface, or 
substantial sections of its surface. One embodiment of such a link 
utilizes magnetized steel and is made according to the design of FIG. 3. 
Similarly, the present embodiment can also be used with nonmetallic chain 
links with the magnetic filler material 31 interspersed throughout the 
link 30 as shown in FIG. 3 rather than using grommets 20. 
In this embodiment of the invention, the magnetic filler material 31 is 
added to the polymeric resin during the conventional molding process of 
the link 30. Again, the filler material may be magnetized during or after 
the link 30 is molded resulting in different magnetic strengths of the 
molded links 30. Preferably the link 30 is magnetized to provide multiple 
poles therein. The maximum field thus produced allows a minimum amount of 
filler material 31 to be used thereby reducing the reduction of strength 
of the links caused by adding the filler 31. Having thus provided the 
chain links 10, 30 according to the present invention, the links 10, 30 
may be assembled to provide a conveyor for ferro magnetic articles. 
Instead of being made of a polymer with magnetic fillers, the link 30 
shown in FIG. 3 could be made of magnetized steel. 
As shown in FIGS. 4 and 5 a conveyor 50 comprising a plurality of 
interconnected chain links 10, 30 in conveying ferro magnetic articles 51 
such as metal containers. The conveyor shown includes a transfer area 58 
where articles 51 are guided from a first section of conveyor 45 to a 
second 46 by guide rails 52. A first set of two sprockets 53, 54 provides 
the drive means for the first conveyor section while a second set of two 
sprockets 55, 56 provides the drive means for the second conveyor section. 
At an intermediate overlapping area of the two conveyor sections guide 
rails 52 are provided to transfer the articles 51. As previously stated, 
neutralization of the magnetic field is normally not required to transfer 
the products 51. 
The transfer of articles 51 may be eased by neutralizing the magnetic 
attraction of the chain links 10, 30 at the transfer area 58. Those same 
links will then regain their magnetic attraction after they pass the 
transfer area. The neutralizing is accomplished by providing a magnetizing 
coil 57 at the transfer area 58. 
As shown in the drawing a neutralizing coil 57 is positioned in the first 
conveyor section 45 before the transfer area 58. This coil 57 is 
electrically connected to produce a magnetic field having a polarity 
opposite to that of the magnetized chain links 10, 30 as they pass through 
the coil 57. The coil 57 has a neutralizing effect on the magnetic field 
of the links 10, 30 thereby allowing the conveyed articles 51 to more 
easily transfer from the first 45 to second 46 conveyor section. The links 
10, 30 then regain their magnetic attraction after passing the transfer 
area 58. 
Referring now to FIG. 6, there is shown an inclined conveyor section 70 
employing chain links 10, 30 constructed according to the principles of 
the present invention. The chain links 10, 30 are supported by and travel 
on nonmetallic low friction wear strips 71 and are driven in a 
conventional manner by a set of sprockets 73, 74. 
As the conveyed articles 51 proceed along with the magnetized links 10, 30 
of the conveyor 70 the inclined portion 75 is encountered. At the 
transition point 76 experience has demonstrated that the conveyor chain 
links 10, 30 tend to raise up from the wear strips 71. In accordance with 
the principles of the present invention this tendency can be counteracted 
by providing a ferro magnetic portion of wear strip 78 at the transition 
section of the conveyor between the horizontal 77 and inclined 75 portions 
of the conveyor 70. The attraction between the magnetized chain links 10, 
30 and the ferro magnetic wear strips 78 counteracts the tendency of the 
conveyor chain to raise. 
In another embodiment of the present invention shown in FIGS. 7-9, a plate 
top conveyor chain 100 comprises a conventional roller chain 101 including 
some extended chain pins 102. The plate top attachment 103 includes an 
article carrying portion 104 with depending legs 105 having holes 106 
therein for receiving the extended portions 102 of the pins thereby 
connecting the attachment 103 to the roller chain 101. As previously 
described, the article carrying portion 104 may include either a 
magnetized grommet 110 which fits into a hole 112 in the attachment 103 or 
in the case of a nonmetallic attachment 200 as shown in FIG. 9, there may 
be a magnetic filler material 201 dispersed throughout the nonmetallic 
resin to impart magnetic properties to the attachment 200. In operation 
this embodiment of the plate top conveyor chain is identical to the 
conveyors previously described except that the conveyor is driven by 
sprockets designed for roller chain.