Agriculture Reference
In-Depth Information
A combination of a thickness grader with sieve slot width smaller than the con-
ventional standard width and a color sorter can be used to increase sorting yield and
percentage of sound whole kernels, as well as to improve the grade of brown rice.
The new technique for fine sorting of brown rice by use of a combination of a thick-
ness grader and a color sorter has been in practical use and is spreading in Japan
(Kawamura et al., 2007).
14.3
GRADING FACILITY FOR FRUITS AND VEGETABLES
14.3.1 R
ECEPTION
AND
D
EPALLETIZING
O
PERATIONS
Operations in fruit grading facilities often start with the product being received on
the ground floor, which is similar to the grain elevator described above. Fruits and
vegetables packed in containers are delivered to the facility in trucks by farmers. A
forklift is used to unload the containers placed under one pallet and deliver them to
the depalletizer device that separates the containers automatically so that they are
fed one by one to a conveyor, which propels them on to another place where the main
inspection line is located. Packages of about 20 containers are put on a pallet by
producers. The depalletizer has a capacity of handling 1200 to 1400 pallets per hour.
14.3.2 D
UMPING
, P
REPROCESSING
,
AND
S
INGULATION
O
PERATION
After depalletization, the containers are moved to the dumper for handling fruits
online. The dumper is an automated machine that turns and empties the containers
gently and then spreads the fruits on a roller conveyor. Before inspection, prepro-
cessing operations are sometimes necessary: dusting, washing, and waxing. Dusting
by a brush-equipped device that removes dust and soil particles and washing by
clean water can help ensure a fair inspection of all fruits, because the outer surface of
fruits is made uniform through the standardized cleaning process. This is important
for presenting uniform products to the camera capturing section. The waxing opera-
tion can also improve the appearance of fruit. These operations are usually done
under main inspection lines by a two layer grading system. After the operations on
the bottom layer, fruits are not formed in lines but in large groups.
It is essential to singulate the fruits one by one in a line for inspection using
specialized rollers. Conveying fruits in groups by a belt conveyor, the special roller
pins perform fruit centering in a few meters. Then, the fruits are singulated when
the specialized roller conveyor sends them to another conveyor for inspecting and
sorting with higher conveyor speed (60 m/min).
14.3.3 M
ECHANICAL
F
RUIT
C
ONVEYING
AND
I
NSPECTION
S
YSTEMS
14.3.3.1 Fruit Conveyor
There are several types of conveyors for fruits and vegetables: piano-keyboard, roller
pin, round carrier, rectangle tray, flat conveyor, and others. As for small fruits such
as oranges and potatoes, RP (roller pin) and PK (piano-keyboard) conveyors are suit-
able for fruit handling. Figure 14.4 shows an inspection system on an RP conveyor
