Case study of orthogonal experimental design

Case: Rice planter hole tray seeding device

1. Experimental design of rice planter hole tray seeding device With the continuous updating of cultivation technology, the efficient, cost-saving, high-yield seedling cultivation method has been rapidly developed and popularized. In order to improve the original seeding device in the eye roller structure, we developed a successful cavity tray seeding device, which not only solves the manual operation of seedling cultivation of labor intensity, low efficiency and other problems, and can greatly improve the stability of the seeding amount and the uniformity of seeding, so that the rice seeding machinery is more practical and perfect.

(1) The purpose of the test to consider the main factors affecting the sowing performance of the rice seeding machine hole tray seedling cultivation sowing device sowing performance of the degree of influence, in order to achieve the optimization of the design parameters.

(2) test conditions seed variety: hybrid rice (Xieyou 46)

seed condition: after de-awning, soaking, catalytic dew, remove impurities

Tray specifications: 600mm × 340mm, 561 holes

seed thousand kernel weight: 26.9g

number of test trays: 100 trays

tray operating The speed is strictly consistent with the speed of the seed discharge tape line.

(3) Test factors

Three variable factors were selected:

Productivity (trays/hour), seeding volume (grains/hole), seeding height (mm).

A. Variable Factors

B. Variable LevelsThe number of levels for each factor was taken as three levels

C. Experimental Factors and Levels

In order to study the effects of productivity, seeding volume and seeding height on sowing performance, orthogonal tests with three levels for the three factors were arranged, and the experimental factors and levels are shown in the table below.

2. Orthogonal test program and analysis of test results (1) orthogonal test program and test results L9 (34) orthogonal table was selected for the experimental design, the test program and test results are shown in the table below. The data collection method is as follows: under the conditions of each working condition (each test number), 3 trays are randomly sampled for determination, and 100 holes are randomly and continuously sampled for each tray when determining the seeding pass rate. Finally, the average of the three measurements of the data recorded in the test results.

(2) The results of the test are analyzed as shown in the following table

Note:

(1) T is the sum of the results of the factor test, such as T1 = 93.0 + 91.0 + 89.0 = 273.0.

(2) t is the mean value of the sum of the results of the factor test, such as.

(3) R is the major-minor number in the t-value.

(4) Sowing pass rate: 100 randomly determined holes per plate, of which the percentage of holes with a qualified number of seed grains (the range of qualified number of seed grains is: hybrid rice (1-3 grains/hole, conventional rice 3-6 grains/hole).

(5) Sowing coefficient of variation V

x - amount of seed sown per disk;

- average disk seeding (g); n - test number of trays, s - standard deviation.

(6) Empty hole rate: 100 randomly determined holes per disk, of which the percentage of the number of empty holes.

From the above two tables, the primary and secondary factors and better levels affecting the three indexes are: sowing qualification rate C1A1B3; sowing coefficient of variation C1B3A1; and empty hole rate C1B3A2.

Considering the actual needs of rice sowing, the better level combinations of each experimental factor were selected as follows after a comprehensive analysis: A1B3C1, A2B3C1, and A1B3C1. Because A1B3C1 as well as A2B3C1 did not appear in the above orthogonal test, for this reason, a special arrangement of single-factor (production) three-level test, the test results are shown in the following table.

From the above table, it can be seen that the best combination is A2B3C1, with a seeding pass rate of 96.0%, a seeding coefficient of variation of 1.9%, and an empty hole rate of 0.5%.

3. Test conclusions (1) 400 trays / hour is the seeding device hybrid rice seeding critical productivity, higher than this value, the performance indicators are significantly affected.

(2) The larger the sowing volume, the better the performance indicators.

(3) The effect of seeding height on seeding quality is very significant, the lower the seeding height, the better the seeding quality.