Scientific report: "The separation of the particles through the trough parts dam dam dam and several empty grain saving function" docx

J. Sci. Dev. 2009, 7 (Eng.Iss.1): 79 - 84 HA NOI UNIVERSITY OF AGRICULTURE
79
Grain separation by the concave and remaining grain of
a multiple cylinders threshing system
Sự tách hạt qua máng đập của bộ phận đập nhiều trống đập và hàm lưu hạt
Le Minh Lu and Nguyen Xuan Thiet
Faculty of Engineering, Hanoi University of Agriculture
TÓM TẮT
Đập và tách hạt là quá trình quan trọng trong việc thu hoạch lúa (lúa nước; lúa mì) và tốn nhiều
năng lượng. Đã có nhiều nghiên cứu về bộ phận đập nhiều trống đập để cải tiến máy gặt đập liên hợp
được giới thiệu trong nhiều năm gần đây. Nghiên cứu bộ phận đập hai trống đập kiểu tiếp tuyến với
hướng cấp liệu tiếp tuyến đã được thực hiện năm 2007 với mục đích: tăng khả năng tách hạt của bộ
phân đập, giảm chi phí năng lượng đập, giảm tác động làm vỡ hạt và rơm vụn. Kết quả nghiên cứu
cho thấy năng lượng đập đã giảm đi khi cấp liệu tiếp tuyến, vật liệu đập (rơm, hạt ) bị giập nát, gẫy
vụn ít hơn do đó tăng khả năng phân tách hạt qua máng đập. Sự sắp xếp hai trống đập liên tiếp thuận
theo hướng chuyển động của dòng nguyên liệu cũng làm tăng chiều dài của máng đập do đó làm
giảm đáng kể lượng hạt còn lưu lại theo rơm ra khỏi máng đập. Bài báo này cung cấp một số kết quả
nghiên cứu chính về sự tách hạt khỏi máng đập, lượng hạt lưu lại theo rơm sau bộ phận đập và phân
tích ảnh hưởng của một số thông số chính như góc cấp liệu và chiều dài máng đập. Mô hình toán học
về quá trình tách hạt khỏi bộ phân đập cũng được giới thiệu.
Từ khóa: Bộ phận đập nhiều trống đập, máy gặt đập liên hợp, sự tách hạt qua máng đập.
SUMMARY
Threshing and separation is one of the most important processes during harvesting of rice and
wheat, and consumes a large of engine power. A number of studies for improving combine harvester
with a multi-drum threshing system have recently been introduced.
Study on two-cylinder tangential threshing system with tangentially fed was done in 2007 with
purposes: to improve separation capacity, reduce fuel consumption and reduce the amount of broken
grain and straw damage. The research results showed that energy will be reduced with tangentially
fed. The threshing material have broken little thereby increasing the separation ability of the threshing
unit. The arrangement of both cylinders, one behind the other in the direction of the material-flow, are
also increase the length of the concave so reduce the remaining grain.

This paper presents some main research results of grain separation by the concave, remaining
grain and analyze the influence of the main parameters feeding angle and concave length. The
mathematical model of grain separation in threshing units are presented.
Key words: Combine, grain separation, multi-drum threshing system, threshing unit.
1. INTRODUCTION
Climbing The task of threshing system is the
removing the grains, i.e. extracting the grains from
the infructescence, like ears, panicle or caps, by
striking and rubbing as well as separating the grains
from the straw. For further grain separating the
cleaning unit is arranged next to the threshing unit,
which design depends partially on the structure of
the threshing system (Arnold, 1964; Huynh, 1982;
Wacker, 1995). It is necessary to improve the
threshing system to perform efficiently and also for
the machine is valid: increasing total throughput;
improving of the grain separation; lowering of the
grain losses.
In this paper, the results of lab tests on two-
cylinder tangential threshing system for the grain
separation and the remaining grain with different
feeding angle, concave clearance and specific
throughput are given.
A general and plain mathematical description of
this process would allow a theoretical prediction of
Grain separation by the concave and remaining grain of a multiple cylinders threshing system
80
the effect of the parameters variations involved,
comparing it with experimental results and obtaining
some ideas about the desired configuration of the

cylinder-concave set (Beck, 1999; Gieroba, 1992;
Kutzbach, 2000). Through analyzing the results of
lab tests with the help of the software Origin, two
mathematical functions have been found.
2. MATERIALS AND METHODS
The basic setup of the test stand is shown in
Fig. 1. The lab test was done with winter wheat
2006. The crop material is prepared on a storage
belt 1 and tangentially fed to the rasp bar cylinder
3 and 4 by means of a feeding mechanism1 and 2.


The grain and material other than grain (MOG)
separated underneath the concave during the test
are collected in classes 1… 5 (m
k1
…m
k5
). The
remaining material that is discharged from the
second cylinder is post - processed using
classical straw walkers to separate grain m
k6
that
is still contained within the MOG (class 6). The
feeding angle () is varied in three steps from 50°
through 60° to 70°. Fig. 2 shows the test stand in
the lab.
The concave clearance at the primary cylinder
(DT1) is defined with the dimensions S

1
, S
2
, S
3
and
S
4
. The concave clearance can be modified by
changing the length of the connections L
1
through
L
5
of the concave support (Fig. 3).













Fig. 1. Test stand Fig. 2. Test stand in the lab

Fig. 3. Layout of primary cylinder and concave
Le Minh Lu, Nguyen Xuan Thiet
81
3. RESULTS AND DISCUSSION
For the evaluation of the concave length the
integral of grain separation (S
Ki
) and remaining
grain (R
Ki
) as defined in Eq. (1) and Fig. 4 was
derived out of the measured grain masses gathered
at the different classes.
100
1
1






i
j
k
i
j
kj
jKjKi
m
m
lAS
%;
R
Ki
= (1 - S
Ki
)*100%;
100*
jk
kj
kj
lm
m
A



% (1)
The tests have shown that very few grains
are separated at the first class (Fig. 5). This is typical


behavior of a tangential threshing unit, since
kernels have to be removed from ears first. At the
end of the second class approx. 50% of the grain is
separated. Less than 5.5% grain is kept in the straw
after leaving the second cylinder at a specific MOG
throughput of 9 kg/(s.m) as seen in Fig. 5.
Through analysis of experiment with help of
statistical software Origin, the function of integral
of grain separation and remaining grain can be
fitted by the following equations:
S
K1
= (1- a*b
l
)*100%
R
K1
= a*b
l
*100% (2)
or by S
K2
= (1 – A
1
e

-l/t1
)*100%
R
K2
= A
1
e
-l/t1
*100% (3)
a, b, A
1
, t
1
are coefficients, which depend on the
structural parameters of threshing unit (thresh gap,
specific total throughput, feeding angle) (Tab. 1).












Fig. 4. Definition of the grain masses in the classes 1 to 3

Fig. 5. Integral of grain separation of lab tests

Grain separation by the concave and remaining grain of a multiple cylinders threshing system
82
Table 1. Coefficients of functions (S
K1
, R
K1
, S
K2
, R
K2
) and the R-squared value

Fig. 6. Coefficient a as a function of the total throughput with different concave clearance
a)  = 50°; b)  = 60°;
c)  = 70°; d) Average value of the coefficient a as a function of total throughput
170
175
180
185
190
195
200
205
210
5 6 7 8 9 10
specific grain and MOG throughput q
[kg/(s.m)]
Coefficient a [%]
20-14-10-8
20-16-12-8
22-18-14-10
sE/sA: DT1(mm)
a)

175
180
185
190
195
200
205
210
5 6 7 8 9 10
Specific grain and MOG throughput
q [kg/(s.m)]
Coefficient a [%]
20-14-10-8
20-16-12-8
22-18-14-10
sE/sA:
DT1(mm)
b)

c)

d)

180

185

190

195

200

205

210

5

6

7

8

9

10

Specific grain and MOG throughput q
[kg/(s.m)]

Co
effi
cie
nt
a
[%

20-14-10-

8

20-16-12-
8

22-18-14-
10

sE/sA:
DT1(mm
)


a = -5,11*(s.m/kg)*q + 228,26 [%]

180

185

190

195

200

205

210

5

6

7

8

9

10

Specific grain and MOG throughput q
[kg/(s.m)]

Co
effi
cie
nt
a
[%]

Le Minh Lu, Nguyen Xuan Thiet
83

Fig.7. Average value of the coefficient as a function of total throughput: a)-A
1
, b)-t
1















Fig. 8. Remaining grain as a function of specific Fig. 9. Remaining grain as a function of
throughput at different feeding angles at concave throughput at different feeding
clearance sE/sA_DT1_20-14-10-8; DT2_12/8
With the change of the adjusted parameters
and the change of the throughput the coefficient b

hardly changes. The coefficient a becomes smaller
with constant feeding angles (50°, 60° and 70°)
with more largely becoming concave clearance,
Fig. 6. For the computation suggests computing an
average value from all tests for the individual
throughput. The following diagram, Fig. 6d) results
for a.
The coefficients A
1
, t
1
of the equations hangs
on the test series of (, sE/sA, q). With bigger
throughput the coefficient A
1
decreases, while the
coefficient t
1
rises. In fig. 7a) and fig. 7b) are
represented the average values of the coefficients
A
1
and t
1
from all tests for the individual
throughput.
Fig. 8 and Fig. 9 show remaining grain that
was not separated through the concaves as a
function of the specific total throughput at different
feeding angles. The remaining grain increases as

expected with larger concave clearance and at
higher throughput.
It becomes clear that feeding angle and
concave clearance mutually affect each other.
Different feeding angles have low influence at the
smallest concave clearance (Fig. 8). However, the
a)
b)

A

1

= -4,9906q + 237,63

190

192

194

196

198

200

202

204

206

208

210

5

6

7

8

9

10

Cpecific grain and MOG throughput q [kg/(s.m)]

Co
effi
cie
nt
A

1

[%]


t1 = 16,091q +
253,18

340

350

360

370

380

390

400

410

5

6

7

8

9

10

Specific grain and MOG throughput q
[kg/(s.m)]

Co
effi
cie
nt
t1



Grain separation by the concave and remaining grain of a multiple cylinders threshing system
84
largest concave clearance causes recognizable
differences in grain separation for the individual
feeding angles (Fig. 9). The feeding angle  = 70°
delivers the highest efficiency, which results in the
conclusion that the feeding angle 70° causing
nearly tangential feeding is very advantageous.
There is still more than 94% of the grain separated
at the concaves with large concave clearance and a
specific grain and MOG throughput of 9 kg/(s•m).
4. CONCLUSION
The new threshing system consists of two
tangential rasp-bar cylinders, where the 1st rasp-bar
cylinder is tangentially fed from a chain conveyer.

Both cylinders are arranged one behind the other in
the direction of the material-flow. For this
arrangement the following advantages are proven in
lab tests:
With this threshing system the material is only
tangentially accelerated. The crop experiences
smaller forces of the rasp bars compared to
conventional threshing systems. Broken grain and
straw damage decreases.
The first cylinder accelerates the material flow
for the second cylinder, which causes higher grain
separation in the second cylinder.
The dwelling time of the material in the
threshing system and the total separation surface of
concaves increases compared to a conventional
system resulting in an improvement of grain
separation.
The integral of grain separation and the
remaining grain function depend at most of the
structural parameters of the rasp-bar cylinders,
concave length, feeding angles, concave clearance
and specific total throughput. The integral of grain
separation and the remaining grain function can be
described with simple functions (2, 3). These
functions approach the test results very well.
Based on the tests we can conclude that such a
threshing system contributes to the further increases
in output, however, the concept of presents
combines would have to be changed. It is an
alternative to the hybrid system, since the specific

power demand and the straw damage can be
reduced.
REFERENCES
Arnold, R.E. and J.R. Lake (1964). Experiments
with rasp bar threshing drums - Comparison of
open and closed concaves - J.Agric.Engng.Res.
9 (3): pp 250-251.
Beck, F.(1999). Simulation der Trennprozesse im
Mähdrescher, Fortschritt- Berichte VDI- Reihe
14, Nr. 92, Dissertation Stuttgart Gieroba, J. and
K. Dreszer (1992) Grain Separation in a
Multidrum set for threshing and Separating -
Riv.di Ing.Agr. XXII (1): pp 45-53.
Huynh, V.M.; T. Powell, and J.N. Siddall (1982).
Threshing and Separating Process - A
Mathematical Model -Trans. of the ASAE 25
(1): pp 65-73.
Kutzbach, H.D.(2000). Ansätze zur Simulation der
Dresch- und Trennprozesse im Mähdrescher,
Tangung Landtechnik 2000, S. 17-22.
Wacker, P. (1995). Untersuchungen zum Dresch-
und Trennvorgang von Getreide in einem
Axialdreschwerk, Forschungsbericht
Argrartechnik der Max- Eyth – Gesellschaft
(MEG) Nr. 117, Dissertation.