Heavy metal cadmium low-accumulation wheat variety screening disc and use method

Abstract

The invention discloses a heavy metal cadmium low-accumulation wheat variety screening disc and a use method, and relates to the technical field of wheat screening. The device comprises a screening box, a screening barrel is rotationally installed in the screening box, filtering holes are formed in the screening barrel, a first gear is fixedly installed on the screening barrel, the first gear is meshed with a second gear, an output shaft of a driving motor is fixedly installed on the second gear, and a first transmission mechanism is arranged on the output shaft of the driving motor; the first transmission mechanism is used for driving the conveying shaft to rotate, and an output shaft of the driving motor is provided with a second transmission mechanism. According to the wheat seed screening device, the driving motor drives the screening barrel to rotate, meanwhile, wheat seeds are evenly scattered through the first transmission mechanism, the wheat seeds and the screening barrel rotate in the opposite direction, bran, dust and other impurities on the surfaces of the wheat seeds are effectively removed, and furthermore, a cam is driven by the second transmission mechanism to rotate, so that a first filter screen plate and a second filter screen plate vibrate; graded screening of the wheat seeds is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wheat screening, and in particular relates to a screening disc for wheat varieties with low accumulation of heavy metal cadmium and a use method thereof. Background Art

[0002] The screening tray for wheat varieties with low accumulation of heavy metal cadmium is a device specially designed for screening varieties with low heavy metal cadmium content in wheat seeds. This screening tray usually combines physical screening and possible biochemical or optical detection technology to identify and separate wheat seeds with lower absorption and accumulation capacity of heavy metal cadmium; specifically, the screening tray for wheat varieties with low accumulation of heavy metal cadmium may include the following key components and functions: physical screening part: through sieves or screening barrels of different sizes, preliminary screening is carried out according to the physical characteristics of wheat seeds such as size, shape and weight to remove impurities and seeds that do not meet the requirements; heavy metal detection part: using biochemical reagents, spectral analysis or X-ray fluorescence and other technologies to detect the heavy metal cadmium content in wheat seeds. These technologies can quickly and accurately identify wheat seeds with low cadmium content; automatic separation part: based on the test results, use robotic arms, airflow or other automatic separation technologies to separate wheat seeds with low heavy metal cadmium content from seeds with high content; data recording and analysis part: the screening tray may also be equipped with a data recording and analysis system to record the results of each screening and analyze the heavy metal cadmium accumulation characteristics of wheat seeds to provide data support for subsequent breeding and planting; it should be noted that the specific design and function of the screening tray for wheat varieties with low heavy metal cadmium accumulation may vary depending on the manufacturer and user needs. But in general, the goal of this screening tray is to improve the quality and safety of wheat seeds and reduce the potential risks of heavy metal cadmium to the environment and human health.

[0003] Currently, wheat will undergo preliminary screening after harvesting, but the screening is rough and the wheat seeds will carry a lot of dust and wheat bran, as well as large particles, which will affect the quality of the wheat. The traditional processing method is to scatter the wheat into the air and then use the gravity of the wheat to blow away the dust with the wind. Although this can remove impurities such as bran mixed in the wheat seeds, it is difficult to remove the soil and dust attached to the outer wall of the wheat seeds, resulting in insufficient clean wheat screening. Summary of the invention

[0004] In view of the problems in the related art, the present invention proposes a heavy metal cadmium low accumulation wheat variety screening plate and a use method to overcome the above-mentioned technical problems existing in the existing related technology.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] The present invention is a screening plate for wheat varieties with low accumulation of heavy metal cadmium, comprising a screening box, a screening barrel rotatably installed inside the screening box, the screening barrel being provided with filter holes, a first gear fixedly installed on the screening barrel, the first gear meshing with a second gear, the second gear fixedly installed with an output shaft of a driving motor, the output shaft of the driving motor being provided with a first transmission mechanism, the first transmission mechanism being used to drive a feeding shaft to rotate, the output shaft of the driving motor being provided with a second transmission mechanism, the second transmission mechanism being used to drive a first connecting shaft and a second connecting shaft to rotate, the first connecting shaft and the second connecting shaft being fixedly installed with cams, the protruding surfaces of the cams being in contact with a first filter screen plate and a second filter screen plate, the first filter screen plate and the second filter screen plate being rotatably installed inside the screening box.

[0007] Furthermore, the screening box is fixedly provided with a feed port, the feed port is communicated with the interior of the screening barrel, the screening barrel is rotatably mounted inside a fixed bracket, the fixed bracket is fixedly mounted on the inner top surface of the screening box, and the drive motor is fixedly mounted on the screening box.

[0008] Furthermore, the first transmission mechanism includes a third gear disposed on the driving motor, the third gear is connected to a fourth gear through a first gear belt transmission, and the fourth gear is fixedly mounted with a feed shaft.

[0009] Furthermore, the third gear and the fourth gear are both rotatably mounted on the screening box, and the feed shaft is rotatably mounted inside the screening barrel.

[0010] Furthermore, the second transmission mechanism includes a fifth gear disposed on the output shaft of the driving motor, the fifth gear is connected to a sixth gear through a second gear belt transmission, and the sixth gear is fixedly mounted with the first connecting shaft.

[0011] Further, the sixth gear is connected to the seventh gear through a third gear belt transmission, the seventh gear is fixedly mounted with a second connecting shaft, the first connecting shaft and the second connecting shaft are rotatably mounted inside the screening box, and the sixth gear and the seventh gear are both rotatably mounted on the screening box.

[0012] Furthermore, the first filter screen plate and the second filter screen plate are inclined, and the screening box is provided with a first discharge port and a second discharge port, and the first discharge port and the second discharge port are both fixedly installed with one end of a return spring, and the other end of the return spring is fixedly installed at the bottom of the first filter screen plate and the second filter screen plate, and the first discharge port and the second discharge port are matched with the inclination direction of the first filter screen plate and the second filter screen plate.

[0013] Furthermore, a sewage outlet is provided at the bottom of the screening box, and an air pump is fixedly installed at the top of the screening box, and the air pump is connected to the interior of the dust collecting box.

[0014] Furthermore, the dust collecting box is fixedly installed on the top of the screening box, a filter is movably installed inside the screening box, both ends of the dust collecting box are connected to one end of a dust suction pipe, the other end of the dust suction pipe passes through the screening box and is connected to a dust hood, and the dust hood is fixedly installed inside the screening box.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention drives the screening barrel to rotate by a driving motor, and at the same time utilizes the first transmission mechanism to evenly scatter the wheat seeds, which rotates in the opposite direction to the screening barrel, thereby effectively removing impurities such as bran and dust on the surface of the wheat seeds. Furthermore, the cam is driven to rotate by the second transmission mechanism, so that the first filter plate and the second filter plate vibrate, thereby realizing the graded screening of the wheat seeds. The larger wheat seeds are discharged through the first filter plate, and the smaller wheat seeds are discharged through the second filter plate, thereby significantly improving the screening efficiency and the grading accuracy.

[0017] 2. The present invention transmits the power of the driving motor to multiple key components through gear transmission and gear belt connection, realizing multi-functional integration such as screening, feeding and vibration. The entire screening disk has a compact structure, occupies a small space, and is easy to operate. The screening operation can be completed by starting the driving motor, which reduces the operating difficulty and labor cost.

[0018] 3. The present invention effectively absorbs dust and other impurities after screening through the design of the air pump and the dust collecting box, and prevents the air pump from being damaged by the filter, thereby achieving environmental protection and energy saving effects. At the same time, the working principle of the screening disk is clear, and the various components cooperate closely, which is conducive to realizing intelligent control. In the future, sensors and automatic control systems can be further introduced to realize real-time monitoring and automatic adjustment of the screening process, further improving the screening efficiency and accuracy.

[0019] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on the following drawings without creative work.

[0021] Figure 1 It is a three-dimensional structural diagram of the present invention;

[0022] Figure 2 is a side view of the present invention;

[0023] Figure 3 It is an enlarged view of point A of the present invention;

[0024] Figure 4 An exploded view of the present invention;

[0025] Figure 5 The internal structure of the present invention Figure 1 ;

[0026] Figure 6 The internal structure of the present invention Figure 2 ;

[0027] Figure 7 It is a cross-sectional view of a dust collecting box of the present invention.

[0028] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0029] 1. Screening box; 2. Screening barrel; 3. Filter hole; 4. First gear; 5. Second gear; 6. Driving motor; 7. Feeding shaft; 8. First connecting shaft; 9. Cam; 10. First filter screen; 11. Feed inlet; 12. Fixed bracket; 13. Third gear; 14. First gear belt; 15. Fourth gear; 16. Fifth gear; 17. Second gear belt; 18. Sixth gear; 19. Second connecting shaft; 20. Second filter screen; 21. Third gear belt; 22. Seventh gear; 23. First discharge port; 24. Second discharge port; 25. Reset spring; 26. Drain port; 27. Air pump; 28. Dust box; 29. ​​Filter; 30. Dust pipe; 31. Dust hood. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the invention to clearly and completely describe the technical solutions in the embodiments of the invention. Obviously, the described embodiments are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0031] In the description of the present invention, it is necessary to understand that the terms "opening", "upper", "lower", "top", "middle", "inside" and the like indicating orientation or positional relationship are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the invention.

[0032] See also Figure 1-Figure 7As shown, the present invention is a screening plate for wheat varieties with low accumulation of heavy metal cadmium, comprising a screening box 1, a screening barrel 2 is rotatably installed inside the screening box 1, the screening barrel 2 is provided with filter holes 3, a first gear 4 is fixedly installed on the screening barrel 2, the first gear 4 is meshed with a second gear 5, the second gear 5 is fixedly installed with an output shaft of a driving motor 6, the output shaft of the driving motor 6 is provided with a first transmission mechanism, the first transmission mechanism is used to drive the feeding shaft 7 to rotate, the output shaft of the driving motor 6 is provided with a second transmission mechanism, the second transmission mechanism is used to drive the first connecting shaft 8 and the second connecting shaft 19 to rotate, the first connecting shaft 8 and the second connecting shaft 19 are both fixedly installed with a cam 9, the protruding surface of the cam 9 is in contact with the first filter screen plate 10 and the second filter screen plate 20, and the first filter screen plate 10 and the second filter screen plate 20 are rotatably installed inside the screening box 1.

[0033] The working principle of the heavy metal cadmium low accumulation wheat variety screening plate proposed in the present invention is to first add the collected wheat seeds into the interior of the screening barrel 2, and then start the driving motor 6 to drive the second gear 5 to rotate, and then drive the first gear 4 to rotate, thereby driving the screening barrel 2 to rotate.

[0034] It is worth noting that when the driving motor 6 is started, it drives the feed shaft 7 to rotate through the first transmission mechanism, so that the added wheat seeds can be evenly scattered. At this time, the feed shaft 7 and the screening barrel 2 rotate in opposite directions, and the wheat seeds can be filtered and screened, so that impurities such as bran and dust attached to the surface of the wheat seeds can be removed. The wheat seeds after removal pass through the filter holes 3 and fall onto the first filter mesh plate 10.

[0035] Furthermore, by starting the driving motor 6, the second transmission mechanism is synchronously driven to move, thereby driving the first connecting shaft 8 to rotate, thereby driving the cam 9 to rotate, and then causing the first filter plate 10 to vibrate, so that the wheat seeds move along the inclination direction of the first filter plate 10, thereby completing the preliminary screening.

[0036] It is particularly emphasized that, since the mesh diameter of the first filter screen plate 10 is larger than the mesh diameter of the second filter screen plate 20, the larger wheat seeds are discharged along the tilt direction of the first filter screen plate 10, and the smaller wheat seeds continue to fall to the surface of the second filter screen plate 20. At this time, the second connecting shaft 19 also drives the cam 9 to rotate, so that the smaller wheat seeds are discharged along the tilt direction of the second filter screen plate 20, thereby realizing the graded screening of wheat. This improves work efficiency.

[0037] In one embodiment, for the above-mentioned screening box 1, the screening box 1 is fixedly installed with a feed port 11, the feed port 11 is connected to the interior of the screening barrel 2, the screening barrel 2 is rotatably installed inside the fixed bracket 12, the fixed bracket 12 is fixedly installed on the internal top surface of the screening box 1, and the drive motor 6 is fixedly installed on the screening box 1.

[0038] In one embodiment, for the first transmission mechanism, the first transmission mechanism includes a third gear 13 disposed on the driving motor 6 , the third gear 13 is connected to a fourth gear 15 via a first gear belt 14 , and the fourth gear 15 is fixedly mounted with the feed shaft 7 .

[0039] In one embodiment, for the third gear 13 , the third gear 13 and the fourth gear 15 are both rotatably mounted on the screening box 1 , and the feed shaft 7 is rotatably mounted inside the screening barrel 2 .

[0040] The working principle of the heavy metal cadmium low accumulation wheat variety screening disk proposed by the present invention is to start the driving motor 6 to drive the third gear 13 to rotate, and then drive the fourth gear 15 to rotate through the first gear belt 14, thereby driving the feed shaft 7 to rotate, and then evenly scatter the wheat seeds inside the screening barrel 2.

[0041] In one embodiment, for the above-mentioned second transmission mechanism, the second transmission mechanism includes a fifth gear 16 arranged on the output shaft of the driving motor 6, the fifth gear 16 is connected to the sixth gear 18 through the second gear belt 17, and the sixth gear 18 is fixedly installed with the first connecting shaft 8.

[0042] In one embodiment, for the sixth gear 18, the sixth gear 18 is connected to the seventh gear 22 through the third gear belt 21, the seventh gear 22 is fixedly mounted with the second connecting shaft 19, the first connecting shaft 8 and the second connecting shaft 19 are rotatably mounted inside the screening box 1, and the sixth gear 18 and the seventh gear 22 are both rotatably mounted on the screening box 1.

[0043] The working principle of the heavy metal cadmium low accumulation wheat variety screening disk proposed by the present invention is to start the driving motor 6 to drive the fifth gear 16 to rotate, and then drive the sixth gear 18 to rotate through the second gear belt 17, thereby driving the first connecting shaft 8 to rotate.

[0044] It is worth noting that the sixth gear 18 drives the seventh gear 22 to rotate through the third gear belt 21, thereby driving the second connecting shaft 19 to rotate.

[0045] In one embodiment, for the above-mentioned first filter screen plate 10, the first filter screen plate 10 and the second filter screen plate 20 are inclined, and the screening box 1 is provided with a first discharge port 23 and a second discharge port 24. The first discharge port 23 and the second discharge port 24 are both fixedly installed with one end of a return spring 25, and the other end of the return spring 25 is fixedly installed at the bottom of the first filter screen plate 10 and the second filter screen plate 20. The first discharge port 23 and the second discharge port 24 are matched with the inclination direction of the first filter screen plate 10 and the second filter screen plate 20.

[0046] The working principle of the wheat variety screening plate with low accumulation of heavy metal cadmium proposed in the present invention is that the cam 9 is driven to rotate by the first connecting shaft 8 and the second connecting shaft 19, thereby driving the first filter plate 10 and the second filter plate 20 to rotate, and then utilizing the repeated action of the reset spring 25 to accelerate the vibration frequency of the first filter plate 10 and the second filter plate 20, thereby accelerating the grading and screening of wheat.

[0047] In one embodiment, for the screening box 1 , a sewage outlet 26 is provided at the bottom of the screening box 1 , and an air pump 27 is fixedly installed on the top of the screening box 1 , and the air pump 27 is connected to the inside of the dust collecting box 28 .

[0048] In one embodiment, for the above-mentioned dust box 28, the dust box 28 is fixedly installed on the top of the screening box 1, and a filter screen 29 is movably installed inside the screening box 1. Both ends of the dust box 28 are connected to one end of a dust suction pipe 30, and the other end of the dust suction pipe 30 passes through the screening box 1 and is connected to a dust cover 31, and the dust cover 31 is fixedly installed inside the screening box 1.

[0049] The working principle of the heavy metal cadmium low accumulation wheat variety screening plate proposed by the present invention is that by starting the air pump 27, impurities such as dust after screening can be absorbed, and the design of the filter 29 can prevent the air pump 27 from being damaged.

[0050] It is worth noting that the suction force generated by the air pump 27 is only enough to absorb impurities such as dust, but not enough to absorb wheat seeds, and the dust and other impurities that have not been completely absorbed can be discharged through the sewage outlet 26.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The preferred embodiments of the invention disclosed above are only used to help illustrate the invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the content of this specification. This specification selects and specifically describes the embodiments in order to better explain the principles and practical applications of the invention, so that those skilled in the art can better understand and use the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A heavy metal cadmium low accumulation wheat variety screening plate, comprising a screening box (1), characterized in that: A screening barrel (2) is rotatably mounted inside the screening box (1), the screening barrel (2) is provided with a filter hole (3), a first gear (4) is fixedly mounted on the screening barrel (2), the first gear (4) is meshed with a second gear (5), the second gear (5) is fixedly mounted with an output shaft of a driving motor (6), the output shaft of the driving motor (6) is provided with a first transmission mechanism, the first transmission mechanism is used to drive the feeding shaft (7) to rotate, the output shaft of the driving motor (6) is provided with a second transmission mechanism, the second transmission mechanism is used to drive the first connecting shaft (8) and the second connecting shaft (19) to rotate, the first connecting shaft (8) and the second connecting shaft (19) are both fixedly mounted with a cam (9), the protruding surface of the cam (9) is in contact with the first filter screen plate (10) and the second filter screen plate (20), the first filter screen plate (10) and the second filter screen plate (20) are rotatably mounted inside the screening box (1); After wheat seeds are added to the screening barrel (2), the drive motor (6) is started to drive the gears to rotate so that the screening barrel (2) rotates, and at the same time the first transmission mechanism is driven to make the feed shaft (7) and the screening barrel (2) rotate in opposite directions, so that the wheat is evenly spread and impurities are screened. The screened wheat falls on the first filter screen plate (10). The drive motor (6) also synchronously drives the second transmission mechanism to drive the cam (9) to vibrate the first filter screen plate (10), so that the wheat moves in an inclined direction for preliminary screening, large seeds are discharged through the first filter screen plate (10), and small seeds continue to fall to the second filter screen plate (20) and are vibrated and discharged again by the cam (9), thereby achieving graded screening.

2. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 1, characterized in that: The screening box (1) is fixedly provided with a feed inlet (11), the feed inlet (11) being connected to the interior of the screening barrel (2), the screening barrel (2) being rotatably mounted inside a fixed bracket (12), the fixed bracket (12) being fixedly mounted on the internal top surface of the screening box (1), and the drive motor (6) being fixedly mounted on the screening box (1).

3. A heavy metal cadmium low accumulation wheat variety screening plate according to claim 2, characterized in that: The first transmission mechanism comprises a third gear (13) arranged on the driving motor (6); the third gear (13) is connected to a fourth gear (15) via a first gear belt (14); and the fourth gear (15) is fixedly mounted with a feed shaft (7).

4. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 3, characterized in that: The third gear (13) and the fourth gear (15) are both rotatably mounted on the screening box (1), and the feed shaft (7) is rotatably mounted inside the screening barrel (2).

5. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 4, characterized in that: The second transmission mechanism comprises a fifth gear (16) arranged on the output shaft of the driving motor (6), the fifth gear (16) being transmission-connected to a sixth gear (18) via a second gear belt (17), and the sixth gear (18) being fixedly mounted to the first connecting shaft (8).

6. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 5, characterized in that: The sixth gear (18) is connected to the seventh gear (22) via a third gear belt (21); the seventh gear (22) is fixedly mounted with a second connecting shaft (19); the first connecting shaft (8) and the second connecting shaft (19) are rotatably mounted inside the screening box (1); and the sixth gear (18) and the seventh gear (22) are both rotatably mounted on the screening box (1).

7. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 1, characterized in that: The first filter screen plate (10) and the second filter screen plate (20) are inclined, the screening box (1) is provided with a first discharge port (23) and a second discharge port (24), the first discharge port (23) and the second discharge port (24) are both fixedly mounted with one end of a return spring (25), the other end of the return spring (25) is fixedly mounted at the bottom of the first filter screen plate (10) and the second filter screen plate (20), the first discharge port (23) and the second discharge port (24) are matched with the inclination direction of the first filter screen plate (10) and the second filter screen plate (20).

8. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 7, characterized in that: The bottom of the screening box (1) is provided with a sewage outlet (26), and the top of the screening box (1) is fixedly mounted with an air pump (27), and the air pump (27) is connected to the interior of the dust collecting box (28).

9. The heavy metal cadmium low accumulation wheat variety screening plate according to claim 8, characterized in that: The dust collecting box (28) is fixedly mounted on the top of the screening box (1); a filter screen (29) is movably mounted inside the screening box (1); both ends of the dust collecting box (28) are connected to one end of a dust suction pipe (30); the other end of the dust suction pipe (30) passes through the screening box (1) and is connected to a dust suction cover (31); and the dust suction cover (31) is fixedly mounted inside the screening box (1).

10. The method for using the heavy metal cadmium low accumulation wheat variety screening plate according to claim 1, characterized in that: The following steps are involved: Step 1: Adding wheat seeds: First, add the collected wheat seeds into the screening barrel (2); Step 2: Start the drive motor: Then start the drive motor (6) to drive the second gear (5) to rotate; Step 3: Rotate the screening barrel: The rotation of the second gear (5) drives the first gear (4) to rotate, and drives the screening barrel (2) to rotate; Step 4: Evenly spread the wheat seeds: When the driving motor (6) is started, the feeding shaft (7) is driven to rotate through the first transmission mechanism to evenly spread the added wheat seeds; Step 5: Filtering and screening the wheat seeds: At this time, the feed shaft (7) and the screening barrel (2) rotate in opposite directions to filter and screen the wheat seeds, and remove impurities such as bran and dust attached to the surface of the wheat seeds; Step 6: The wheat seeds fall onto the first filter screen: the wheat seeds fall onto the first filter screen (10) through the filter holes (3) of the screening barrel (2); Step 7: vibrating the first filter screen: by starting the driving motor (6), the second transmission mechanism is synchronously driven to move, the first connecting shaft (8) is driven to rotate, and the cam (9) is driven to rotate, so that the first filter screen (10) vibrates; Step 8: Preliminary screening of wheat seeds: The vibrating first filter screen plate (10) causes the wheat seeds to move along the direction of its inclination, thereby completing preliminary screening; Step 9: Grading and screening wheat seeds: Since the mesh diameter of the first filter screen (10) is larger than the mesh diameter of the second filter screen (20), the larger wheat seeds will be discharged along the inclination direction of the first filter screen (10), while the smaller wheat seeds will continue to fall onto the surface of the second filter screen (20). At this time, the second connecting shaft (19) also drives the cam (9) to rotate, and the smaller wheat seeds are discharged along the inclination direction of the second filter screen (20), thereby achieving graded screening of the wheat.

Images