Apparatus for sorting spherical products according to weight

An apparatus for sorting spherical products, comprising an endless conveyor equipped with bearing rollers (2), with a product lifting element (10) arranged between each pair of successive bearing rollers (2), this product lifting element (10) being capable of assuming a first, lowermost position wherein the product (16) is clear of the lifting element (10) and rests on the bearing rollers (2), while in a second, higher position the product (16) is clear of the bearing rollers (2) and rests on the lifting element (10) to be subjected to another operation, for instance a weighing step or another physical evaluation.

This invention relates to an apparatus for sorting spherical products, 
comprising an endless conveyor capable of being driven by at least one 
chain for conveying the products to be sorted in individually supported 
manner, while along the path of movement of the conveyor a weighing means 
is present for weighing each individual product. 
Such an apparatus is known from U.S. Pat. No. 4,583,636. The endless 
conveyor of this known apparatus consists of two parallel chains 
interconnected by pins, provided at a fixed pitch distance, extending 
transversely to the direction of conveyance. Pivotally mounted on each of 
these pins is a U-shaped support bracket and in this bracket a product 
receiving member is likewise pivotally supported. 
Although this known apparatus functions excellently in practice and yields 
accurate weighing results, it still exhibits some disadvantages 
susceptible to improvement, such as: 
Owing to the presence of a supporting bracket with product receiving member 
between each pair of successive transverse pins, the pitch distance 
between those transverse pins is considerably greater than the diameter of 
the product to be sorted. A reduction of this pitch distance would yield 
an increase of the processing capacity of the apparatus. 
The combination supporting bracket/product receiving member is a rather 
complicated construction, which, moreover, has a relatively great 
deadweight compared with the product to be weighed. A reduction of this 
deadweight could yield increased accuracy. 
The products to be sorted must in some manner or other be individualized 
and placed in a product receiving member and discharged therefrom after 
weighing. It has been found to be troublesome to fill the product 
receiving members directly from a supply device supplying the products in 
bulk. 
The object of the invention is to provide an apparatus of the 
above-described type wherein these drawbacks have been obviated. To that 
end, the apparatus according to the invention is characterized in that the 
conveyor is a roller conveyor comprising bearing rollers, with a product 
lifting element arranged between each pair of successive bearing rollers, 
this product lifting element being normally in a first, lowermost position 
wherein the product is clear of the lifting element and rests on two 
adjacent bearing rollers, while the lifting element can further be brought 
into at least a second, higher position wherein the product is clear of 
the bearing rollers and rests on the lifting element, in which second 
position the weighing of the product can take place. 
In this manner, a separation of functions has been obtained. During 
conveyance, the products to be sorted are supported by the bearing 
rollers, which can be arranged at a pitch distance that is related to the 
average diameter of the product to be sorted and therefore is smaller than 
the pitch distance of the transverse pins in the known apparatus. During 
weighing, the products are lifted off the bearing rollers by means of the 
product lifting element, which has a smaller deadweight than the known 
combination supporting bracket/product receiving member, so that the 
weighing accuracy increases. Filling the conveyor equipped with bearing 
rollers is simpler than filling the conveyor equipped with product 
receiving members. 
Preferably, each bearing roller is connected to the drive chain of the 
roller conveyor by means of a roller carrying element while each lifting 
element is mounted on a corresponding roller carrying element by means of 
a rod parallelogram. Thus, one drive chain for the conveyor will suffice, 
while at the same time a possibility of properly mounting the lifting 
element is obtained. 
The product lifting element can assume various positions, for instance a 
conveyance position, a weighing position and a discharge position. To that 
end, each lifting element comprises at the lower end thereof a guide 
roller capable of cooperating with a guideway which slopes upwards 
upstream of the weighing means and extends horizontally at the location of 
the weighing means. 
For supporting the product for instance in the weighing position or the 
discharge position, each lifting element comprises at the top thereof 
carrying forks, which, in the first, lowermost position of the lifting 
element, can be received in annular recesses of the adjacent bearing 
rollers. For discharging a product in lateral direction, the carrying 
forks are pivotable about a shaft of the lifting element in a direction 
transverse to the direction of movement of the roller conveyor. 
To enable centred support of the product in a direction transverse to the 
direction of conveyance as well, the bearing rollers have a substantially 
hyperboloid shape and a bearing surface of concave configuration, while on 
opposite sides of the central part, transition parts are arranged whose 
diameter is smaller than that of the central part.

The apparatus according to the invention comprises a roller conveyor 1 
equipped with bearing rollers 2. The bearing rollers 2 are each mounted 
for free rotation on a shaft 3 (see FIG. 3), which is mounted on a 
carrying element 19 which in turn is connected to a drive chain 9. The 
chain 9 is confined in a guide rail 25. 
Disposed between each pair of adjacent rollers is a product lifting element 
10 which comprises, at the upper end thereof, carrying forks 11 and, at 
the lower end thereof, a guiding roller 12 capable of cooperating with a 
guideway 13. Each product lifting element 10 is connected to the 
corresponding carrying element 19 by means of a rod parallelogram 17. The 
arm 18 of the rod parallelogram that is connected to the carrying element 
19 extends parallel to the lifting element 10, so that this lifting 
element 10 can be displaced parallel to itself in vertical direction. 
FIG. 1 shows three lifting elements 10, each in a different vertical 
position. The left-hand lifting element 10 is in the conveyance position 
wherein the product 16 rests on the bearing rollers 2 while the carrying 
forks 11 of the lifting element are located below the bearing surface of 
the bearing rollers 2. In this position, the rod parallelogram 17 rests on 
a stop 26 mounted on the carrying element 19. The central lifting element 
10 is disposed in the weighing position above the weighing station 15. In 
this weighing position, the carrying forks 11 reach above the bearing 
surface of the bearing rollers 2. The lifting element 10 is brought from 
the conveyance position into the weighing position by means of the 
guideway 13, which slopes upward upstream of the weighing station 15 and 
extends horizontally at the location of the weighing station 15. The 
guideway portion 14 above the weighing station of course forms a separate 
part of the guideway 13. It is preferred that in the weighing position of 
the lifting element 10 the laterally extending rods of the rod 
parallelogram 17 extend horizontally so as to increase weighing accuracy. 
The right-hand lifting element 10 is shown in the discharge position 
wherein the lifting element 10 has been displaced by means of the guideway 
13 so as to extend above the weighing position. The product 16 is 
discharged transversely to the direction of conveyance. To that end, the 
carrying forks 11 are pivotally mounted on a shaft 23 (see FIG. 2). The 
carrying forks are pivoted with the aid of a lever 21, which, by means of 
an ejection element (not shown), can be brought from the position 
indicated by solid lines into the discharge position indicated by broken 
lines, wherein a product 16 can be discharged over the lateral edge of the 
bearing rollers 2 and delivered via a chute 22 to a discharge conveyor for 
the desired product sorting class. 
To provide for centred support of the product in a direction transverse to 
the direction of conveyance as well, the bearing rollers 2 have a 
hyperboloid shape and a concave bearing surface. To that end, each bearing 
roller 2 may be composed of three discs 4, 5, 6, of which the outer discs 
4, 6 have a greater diameter than the central disc 5. Arranged on opposite 
sides of the central disc 5 are spacer rings 7, 8 whose diameter is 
smaller than that of the central disc 5. The spacer rings 7, 8 form 
interruptions in the product bearing surface of a bearing roller 2, which 
interruptions are capable of accommodating the carrying forks 11 of a 
lifting element 10 that is in the conveyance position. The bearing roller 
2 may also be designed as a one-piece part having a stepped diameter 
corresponding to the diameters of the above-described discs 4, 5, 6 and 
spacer rings 7, 8. 
The outer discs 4, 6 have a smooth circumferential surface, with the disc 6 
being supported and capable of being driven by a supporting rail 24 (FIG. 
2). The central disc 5 has a circumferential surface that has a 
considerably higher coefficient of friction than the circumferential 
surface of the outer discs 4, 6. The drive of the bearing rollers 2 via 
the supporting rail 24 gives the conveyor 1 self-loading properties, i.e., 
the conveyor 1 can have an upwardly sloping portion thereof arranged in a 
product reservoir containing a stock of products to be sorted, so that the 
conveyor is quickly and efficiently filled with individualized products 
that are correctly centred and oriented. The higher coefficient of 
friction of the circumferential surface of the central disc 5, which 
surface is in contact with the largest diameter of the product, provides 
for calm product behaviour in the position where it is supported by the 
bearing rollers 2, thereby preventing the product from spinning about an 
axis perpendicular to the surface of conveyance in that slip occurs at the 
location of the outer discs 4, 6, which have a greater diameter and engage 
the product at a smaller diameter.