Title: Perforated linear belt produce sizer

Field of the invention

This invention relates to the process of sorting small items by assessment of the condition of size, particularly for small round fruit or vegetables.

Background of the invention

Produce is commonly selected into size-based groups to conform to consumer preferences, so as to maximise income returnable to the grower. The size distribution of any produce can normally be split at a point reflecting developmental characteristics, whereby small items can be correlated to customer preferences hence low value, so the average crop value can be increased by the removal of such items.

Mechanised produce sizers are a development of traditional manual gauging methods. They can use one or many gauging channels, and depend on the size relationship between a produce dimension, and the dimension of an opening such as a gap or hole in a barrier preventing induced produce movement. Those items which exceed the dimension cannot proceed through the hole or gap, and so are thereby selected into a group separate from produce items that are small enough to proceed unimpeded through the barrier. Commonly, gravity is utilised as a functional force in the sizing method, by arranging the barrier in a near-horizontal plane such that random or induced produce movement increases the probability of produce encountering a gap or hole so that the gauging process occurs.

These events typically create four groups of produce, being 1 that significantly larger than the barrier gap; 2 that significantly smaller than the barrier gap; 3 that which sticks in the barrier gap; and 4 that which both sticks in the gap and is later crushed in the mechanism.

The objective technical problem solved by this design is the unacceptable squash rate of gauging-hole sized fruit lodged in a gauging hole, caused by an effective acute angle of approach to the exit pulley creating a rupture force vector sufficient to compromise fruit integrity. The auxiliary lift belt reduces the angle of approach from ~60 degrees to

vertical to <5 degrees to vertical thereby greatly increasing the probability of dislodging without rupture a fruit resting in a gauging hole.

A secondary and related issue was the application in the invention of the design objective of fall height minimisation so as to minimise fruit impact damage by fall- induced bruising. For the largest hence highest value fruit carried forward down the grading line, this is principally determined by the exit pulley diameter, hence is minimised in this design. Minimising this necessarily maximised the said acute angle of approach, as in the limiting case the angle would tend to 90 degrees to the vertical, thereby exacerbating the angle of approach issue leading to fruit damage in the class of fruit which is lodged in a hole and thereby most susceptible to damage by squashing. Additionally, the fall of small items onto the diversionary conveyor is also minimised so both item streams are minimally susceptible to induced damage.

The fall-minimisation advantage of the present design is more marked in relation to perforated drum sizers, in which the fall distance of both size grades are typically larger hence less suitable to soft grades of fruit or vegetables.

It is a first object of the present invention to eliminate groups 3 and 4 by gently and automatically lifting any item out of its condition of resting in a belt gauging hole.

It is a second object to facilitate ease of use and hence machine productivity by implementing a simple and rapid technique of changing the gauge dimension.

It is a third object to minimise item damage by using a minimal fall distance for all item groups.

It is a fourth object to minimise removal of produce surface features such as skin bloom, by using a non-rotational sorting technique.

It is a fifth object to use a sizing technique relatively insensitive to item ovality, as in the case of an oval item consumer perceptions of size are more strongly influenced by major axis dimension than minor axis dimension, and a gap sizer admits the narrow dimension as well as the major dimension, which leads to a greater uncertainty of selection at the gauging size than a hole sizer.

US Patent 5,810,175 features a gap sizing technique created by a plurality of alternately spaced belts. Naturally this is sensitive to item ovality, hence creates imprecision of selection at the sizing value depending on item orientation at the gauging moment.

US Patent 5,125,515 is also a gap sizer which in this case also induces rotation of the item to be sized, and features relatively large item fall distances hence is more suited to robust items insensitive to surface scuffing. Advantages of the present invention are that it is both insensitive to ovality and does not induce rotation of the sized objects.

Brief description of the drawings

Figure 1 is a lateral view showing spatial relationships of the principal components. Included within this is illustrated the alternative item paths as determined by their size relationship to the gauging technique, but showing only one gauging lane.

Figures 2 and 3 show structural support components in their general form, and also the width typically occupied by multiple gauging lanes and as chosen in relation to the width of other equipment in the packing line.

Figure 4 is a view of the preferred embodiment viewed from the input end.

Detailed description of the invention

This size sorting apparatus consists of an external frame 6 supporting three pulley rollers 1,2,3 around which an endless conveyor belt 4 is driven. This conveyor belt is perforated with numerous holes 5 the diameter of which constitutes the produce sizing value of the machine.

The external frame 6 (the full extension of which is not shown for clarity) simultaneously functions as a safety barrier against inadvertent entrapment of user body parts as well as a dust cover. An internal structural frame member 7 between the rollers 1,2,3 transfers their weight to only one side which permits rapid conveyor belt replacement from the other side.

A second and auxiliary short belt 8 rotates inside the sizing belt 4 at the exit end of the conveyor and functions to lift items 9 of size just larger than gauge size out of the belt

holes so they easily fall with the rest of the retained items 10 off the drive roller end to 85 progress to the next grading or treatment stage of the packing line.

The items of size less than the gauge size 11 fall through the perforated belt holes 5 onto a transverse conveyor 12 hence are effectively diverted from the main flow of items.

A pneumatic ram 13 under direction and pressure control either lifts or lowers the lowest roller pulley 3 to either release the belt tension to enable belt 4 to be replaced by 90 one of different gauge size, or apply adjustable tension for correct operation. It is an advantage of this system that within ram movement limits, exact belt length and stretching during normal operation is both non-critical and easily accommodated.

Gauge size selection is therefore implemented by removing the presently installed belt and replacing it with another pre-punched endless belt, the hole dimension of which 95 may be chosen for a better match to the item size distribution and market requirements of the items.

The ram 13 moves the lowest roller in a short arc 15 on its pivotal mounting 14 permitting the complete belt exchange process to optimally occur in less than five minutes, thus minimising grading line productivity loss when adjusting the machine to 100 match new unsorted item characteristics.

The auxiliary lift belt 8 remains in place during this operation and is separately tensioned by fixed springs internal to the belt support mechanism. Its leading edge is height-adjustable 16 and to be optimally adjusted to just less than half the gauge hole diameter from the lower side of the perforated belt thereby minimising risk of crushing 105 items resting in the holes.

A v-section belt alignment ridge added to each inner surface on each side of the main belt also acts both to retain proper alignment of the lift belt by contributing lateral pressure to restore central position of both belt paths, and to strengthen the perforated belt against excessive stretch. Matching alignment retention grooves are therefore on 110 both sides of each main roller.

As mixed items 9,10,11 may be deposited onto the belt in multiple layers, item braking flexible membranes 17 suspended over the entry end of the conveyor belt are provided

to control item movement into a single layer thereby increasing the probability that every item will find its own gauge hole.

The described embodiments of the invention are intended to be merely exemplary and numerous variations and modifications will be apparent to those skilled in the art. AU such variations and modifications are intended to be within the scope of the present invention as defined in this description.