Combined winnowing sieve

Abstract

The utility model relates to a combined winnowing screen, a screening piece and an impurity shifting roller are arranged below a feeding port of the combined winnowing screen, grain materials enter the combined winnowing screen from the feeding port, and the grain materials and small impurities flow downwards from screen holes of the screening piece. Large impurities such as rope heads, paper scraps, plastic cloth fragments and woven bag fragments in grain materials obliquely flow downwards along the screening part and then are discharged under the shifting action of the impurity shifting roller, the large impurities entering the screen box of the combined winnowing screen can be effectively reduced, the large impurities such as the rope heads and broken stones can be effectively prevented from blocking meshes of screen grids in the screen box, and the screening efficiency is improved. Therefore, the screening efficiency and the quality of screened clean grains are effectively guaranteed.

Description

Technical Field

[0001] This utility model belongs to the technical field of grain screening equipment, specifically relating to a combined air separator for grain screening and impurity removal. Background Technology

[0002] During harvesting, grain materials inevitably become contaminated with impurities such as dust, chaff, straw, gravel, rope ends, paper scraps, plastic sheeting, and woven bag fragments. These impurities, when stored with grain, can easily cause the grain to overheat and mold, and can also obstruct the flow of grain in and out of the warehouse. This is especially true for large grain depots, which typically use tubular chain conveyors for grain handling. Impurities like rope ends, paper scraps, plastic sheeting, and woven bag fragments can easily become entangled in the conveyor chain, hindering grain flow. Grain and other impurities can also increase wear and tear on the equipment, affecting its lifespan. Therefore, grain must be screened and cleaned before storage to remove impurities and some dust, ensuring smooth grain handling and maintaining grain quality. Currently, there are various types of equipment on the market for screening and dust removal of grain materials, such as vibrating screens, flat rotary screens, and combined air classifiers. However, in the use of existing grain screening equipment, grain materials mixed with impurities enter through the feed inlet and are directly spread on the upper screen. The upper screen usually has a larger aperture, and larger impurities such as straw fragments and large-diameter gravel remain on the upper screen and are discharged through the large impurity outlet. Meanwhile, the grain materials and smaller impurities fall through the mesh of the upper screen to the lower screen for further screening. However, in actual use, larger impurities such as straw fragments, gravel, rope ends, paper scraps, plastic sheeting, and woven bag fragments often get stuck in the mesh of the upper screen, causing blockage. This results in some grain materials being discharged through the large impurity outlet, affecting the screening quality and efficiency. Utility Model Content

[0003] In summary, in order to overcome the shortcomings of the existing technology, this utility model provides a combined air classifier. The combined air classifier is equipped with a screening element and a debris-removing roller below the feed inlet. The screening element is used to screen out large impurities such as rope ends, paper pieces, plastic sheet pieces, and woven bag fragments from the grain material. The debris-removing roller is used to remove the screened large impurities and discharge them, thereby effectively removing large impurities from the grain material.

[0004] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows:

[0005] A combined air classifier, comprising:

[0006] The feeding component includes a feed inlet, a discharge outlet, and a feeding channel connecting the feed inlet and the discharge outlet. A large impurity outlet communicating with the feeding channel is located on one side of the feeding component. A screening component and a waste-removing roller are installed within the feeding channel.

[0007] A screening element has a hinged end and a free end opposite to the hinged end. The free end of the screening element passes through a large impurity outlet. The hinged end of the screening element is hinged to the opposite side of the large impurity outlet of the feed channel. The screening element is arranged inclined downwards along the direction from the hinged end to the free end. The screening element has a screening zone and a removal zone arranged sequentially along its inclined direction. The screening zone has densely arranged screen holes, and the removal zone has elongated gaps densely arranged in a direction perpendicular to the inclined direction.

[0008] The impurity-removing roller has a roller shaft that is rotatably connected to the feed member. The free end of the screening member overlaps on the roller shaft. The roller shaft is provided with an impurity-removing component. The impurity-removing component corresponds to the elongated gap of the impurity removal zone of the screening member. As the roller shaft rotates, the impurity-removing component passes through the elongated gap of the impurity removal zone.

[0009] Preferably, the impurity removal component is at least one row of impurity removal rods arranged on the roller shaft. Multiple rows of impurity removal rods are arranged circumferentially along the roller shaft. Each row of impurity removal rods includes multiple impurity removal rods. The multiple impurity removal rods are arranged along the axial direction of the roller shaft. The length direction of the impurity removal rods is perpendicular to the axis of the roller shaft. The impurity removal rods correspond to the elongated gaps in the impurity removal area of ​​the screening element.

[0010] Preferably, at least one rod is connected to the roller shaft, the axis of the rod is arranged parallel to the axis of the roller shaft, and the plurality of rods are evenly arranged along the circumference of the roller shaft. The rotating roller shaft and rods cause the screening element to swing around the hinge end of the screening element.

[0011] Preferably, the screening component includes a sieve plate and multiple grate bars. One end of the sieve plate is the hinge end of the screening component, and the end of the sieve plate opposite to the hinge end is the connecting end. The multiple grate bars are connected to the connecting end of the sieve plate, and the multiple grate bars are arranged in a direction perpendicular to the inclination direction of the screening component. The gap is the space between two adjacent grate bars.

[0012] Preferably, one end of the grate bar is fixedly connected to the connecting end of the sieve plate, and the other end of the grate bar has a downward bend. The end of the grate bar opposite to the bend is fixedly connected to the bottom surface of the connecting end of the sieve plate. The free end of the screening component is the end where the bend is located. The grate bar overlaps on the roller shaft of the impurity removal roller, and its overlap position is close to the bend.

[0013] Preferably, the device also includes a screen box, which is suspended from the frame via a suspension rod. The upper end of the suspension rod is hinged to the frame, the lower end of the suspension rod is connected to the screen box, and the upper end of the suspension rod is connected to the frame. The screen box has a feed inlet, a clean grain outlet, and a waste outlet. The feed inlet of the screen box is connected to the discharge outlet of the feed unit via a flexible connecting pipe. The screening power device is connected to the screen box and drives the screen box to perform planar rotary motion.

[0014] Preferably, a magnetic separator is installed inside the clean grain outlet of the sieve box.

[0015] Preferably, the device further includes an air classifier, which is mounted on a frame. The feeder is disposed inside the air classifier, dividing the inner cavity of the air classifier into an air distribution chamber and an induced draft settling chamber. The air distribution chamber and the induced draft settling chamber are located on opposite sides of the feeder. A purification air inlet, connecting the air distribution chamber to the feed channel, is provided on the side of the feeder adjacent to the air distribution chamber. The purification air inlet is located below the screening element.

[0016] The aforementioned induced draft settling chamber is equipped with a partition that divides the inner cavity of the induced draft settling chamber into a large miscellaneous settling chamber and a small miscellaneous settling chamber. The partition is also equipped with an air passage connecting the large miscellaneous settling chamber and the small miscellaneous settling chamber.

[0017] The large impurity outlet of the feed unit is connected to the feed channel and the large impurity settling chamber.

[0018] The air separator is provided with a return air duct on its outer side. One end of the return air duct is connected to the air distribution chamber, and the other end of the return air duct is connected to the air outlet of the ventilator.

[0019] The air separator is equipped with a large impurity pipe connected to the large impurity settling chamber and a small impurity pipe connected to the small impurity settling chamber on its outer side. Both the large and small impurity pipes have impurity outlets.

[0020] The small impurity settling chamber is equipped with a light impurity separation cylinder. The air inlet of the light impurity separation cylinder is connected to the inner cavity of the small impurity settling chamber, and the air outlet of the light impurity separation cylinder is connected to the air inlet of the ventilator. The air inlet of the ventilator is also connected to the upper end of the vertical air suction channel, and the lower end of the vertical air suction channel is connected to the atmosphere.

[0021] Preferably, the cross-sectional shape of both the large impurity settling chamber and the small impurity settling chamber is V-shaped. A large impurity auger is installed in the large impurity settling chamber, and a small impurity auger is installed in the small impurity settling chamber. Both the large and small impurity augers are connected to the impurity removal power device, which is also connected to the roller shaft of the impurity removal roller.

[0022] Preferably, the vertical air intake channel is provided with an air intake adjustment mechanism, which includes an air intake adjustment plate disposed in the vertical air intake channel and hinged to the side wall of the vertical air intake channel, and an operating handle for driving the air intake adjustment plate to swing is provided on the outside of the vertical air intake channel.

[0023] Preferably, the air passage is provided with an air passage adjustment mechanism, which includes an air regulating plate installed in the air passage and hinged to the air separator box, and an operating handle for rotating the air regulating plate is provided on the outside of the air separator box.

[0024] Preferably, it further includes a leveling hopper connected to the feed inlet of the feeding channel. The leveling hopper has an upper opening, a lower opening, and a leveling channel connecting the upper opening and the lower opening. The lower opening of the leveling hopper is connected to the feed inlet of the feeding component. An adjusting plate is provided in the leveling channel and is hinged to the leveling hopper. A material passage gap is provided between the adjusting plate and the side plate of the leveling hopper. An adjusting handle for adjusting the material passage gap is provided on the outside of the leveling hopper. The adjusting handle is connected to the hinge shaft between the adjusting plate and the leveling hopper.

[0025] The beneficial effects of this utility model are as follows:

[0026] 1. This utility model features a screening element and a debris-removing roller installed below the feed inlet of a combined air classifier. Grain material enters the combined air classifier through the feed inlet, and the grain material and small impurities flow downward through the screen holes of the screening element. Large impurities such as rope ends, paper pieces, plastic sheet pieces, and woven bag fragments in the grain material flow downward along the inclined screen element and are then discharged under the action of the debris-removing roller. This effectively reduces the amount of large impurities entering the screen box of the combined air classifier and effectively prevents large impurities such as rope ends, paper pieces, plastic sheet pieces, and woven bag fragments from clogging the mesh of the screen grid in the screen box, thereby effectively ensuring screening efficiency and the quality of clean grain after screening.

[0027] 2. The impurity-removing roller of this utility model has a rod connected to its roller shaft. The free end of the screening component overlaps with the roller shaft and contacts the rod. The rod rotates with the impurity-removing roller, which enables the screening component to swing up and down around its hinge end, allowing grain materials and small impurities to pass smoothly through the screen holes, improving the screening efficiency of the screening component and reducing screen hole blockage.

[0028] 3. The air separation device of this utility model's combined air separation screen, under the action of a blower, allows the airflow entering the uniform air chamber to pass through the impurity removal inlet into the feeding channel within the feeding component, and then flow out from the large impurity outlet. The path of the airflow from the impurity removal inlet to the large impurity outlet within the feeding channel is the impurity removal channel. After the grain material is cleaned of large impurities by the screening component and the impurity removal roller, it flows downward along the feeding channel. Light and fine impurities such as straw and dust in the grain material are carried by the airflow and enter the large impurity settling chamber through the large impurity outlet. Due to the settling of large impurities... The internal dimensions of the chamber are much larger than the dimensions of the impurity removal channel. After the airflow enters the large impurity settling chamber, the large impurities carried in the airflow settle and are discharged by the large impurity auger. Then, the airflow enters the small impurity settling chamber along the air passage. Some of the small impurities carried in the airflow settle in the small impurity settling chamber. The airflow after impurity removal enters the light impurity separation cylinder. Under the action of the light impurity separation cylinder, dust and other light and fine impurities are removed. Then, under the action of the fans located on both sides of the light impurity separation cylinder, the airflow re-enters the uniform air chamber through the return air passages on both sides of the air separator, realizing the circulation of airflow.

[0029] 4. The combined air classifier of this utility model has an air intake regulating mechanism in the vertical air intake channel of the air classifier box and an air passage regulating mechanism in the air passage of the air classifier box. The air volume can be adjusted by the air intake regulating mechanism and the air passage regulating mechanism.

[0030] 5. The combined air classifier of this utility model has a uniform hopper connected to the feed inlet of the feed component. An adjusting plate is provided in the uniform channel. After the grain material enters from the feed end of the uniform hopper, the grain material is evenly dispersed under the action of the adjusting plate, so that the grain material can enter the feed component evenly, and then enter the screen box for screening through the feed channel in the feed component.

[0031] 6. The combined air classifier of this utility model is equipped with a magnetic separator in the clean grain outlet of the screen box. Iron filings and impurities in the clean grain after being screened and impurity removed by the screen grid in the screen box are adsorbed and removed by the magnetic separator, which can effectively remove iron filings and impurities in the grain material and ensure the quality of the clean grain after screening and impurity removal. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the structure of this utility model;

[0033] Figure 2 shows the present invention. Figure 1 A schematic diagram of the left-side view structure;

[0034] Figure 3 is a schematic diagram of the working principle of this utility model;

[0035] Figure 4 is a schematic diagram of the structure of the screening component and the impurity removal roller of this utility model;

[0036] Figure 5 shows the present invention. Figure 4 A schematic diagram of the structure along direction A. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings.

[0038] As shown in Figures 1, 2, and 3, a combined air classifier includes: a frame 5, a screen box 7, a screening power unit 8, an air classifier box 12, a screening component 1, and a debris-removing roller 2. The frame 5 is suspended and connected to the screen box 7 via a suspension rod 6. The upper end of the suspension rod 6 is connected to the frame 5, and the lower end of the suspension rod 6 is connected to the screen box 7. The screen box 7 is provided with multiple layers of screens. The screen box 7 has a feed inlet, a clean grain outlet, and a debris outlet. A magnetic separator 17 is provided in the clean grain outlet of the screen box 7. The feed inlet of the screen box 7 is connected to the outlet of the feed component 9 via a flexible connecting pipe 11. The screening power unit 8 is connected to the screen box 7 and drives the screen box 7 to perform planar rotary motion.The frame 5 is equipped with an air separator 12 at its upper end. The feeder 9 is disposed inside the air separator 12, and the feeder 9 divides the inner cavity of the air separator 12 into a uniform air chamber 121 and an induced draft settling chamber. The uniform air chamber 121 and the induced draft settling chamber are located on opposite sides of the feeder 9. A purification air inlet 903 is provided on the side of the feeder 9 adjacent to the uniform air chamber 121, connecting the uniform air chamber 121 and the feed channel 901. The purification air inlet 903 is located below the screening element 1. A partition 124 is provided inside the induced draft settling chamber. The inner cavity of the induced draft settling chamber is divided into a large impurity settling chamber 122 and a small impurity settling chamber 123. An air passage 125 is provided on the partition 124, connecting the large impurity settling chamber 122 and the small impurity settling chamber 123. An air passage regulating mechanism 129 is provided within the air passage 125. The air passage regulating mechanism 129 includes an air regulating plate disposed within the air passage 125 and hinged to the air separator box 12. An operating handle for rotating the air regulating plate is provided on the outside of the air separator box 12. The cross-sectional shape of both the large impurity settling chamber 122 and the small impurity settling chamber 123 is V. The air separator 12 is provided with a large impurity pipe communicating with a large impurity settling chamber 122 and a small impurity pipe communicating with a small impurity settling chamber 123 on its outer side. Both the large and small impurity pipes have impurity outlets. A large impurity auger 126 is provided inside the large impurity settling chamber 122, and a small impurity auger 127 is provided inside the small impurity settling chamber 123. Both the large and small impurity augers 126 and 127 are connected to a power device 128 for removing impurities. The power device 128 is also connected to the roller shaft 201 of the impurity removal roller 2. A return air supply is provided on the outer side of the air separator 12. The return air duct 15 is connected at one end to the uniform air chamber 121 and at the other end to the air outlet of the ventilator. The small impurity settling chamber 123 is equipped with a light impurity separation cylinder. The air inlet of the light impurity separation cylinder is connected to the inner cavity of the small impurity settling chamber 123, and the air outlet of the light impurity separation cylinder is connected to the air inlet of the ventilator. The air inlet of the ventilator is also connected to the upper end of the vertical suction duct 14, and the lower end of the vertical suction duct 14 is connected to the atmosphere. The vertical suction duct 14 is equipped with an air intake adjustment mechanism 16. The air intake adjustment mechanism 16 includes an air intake adjustment plate installed in the vertical suction duct 14 and hinged to the side wall of the vertical suction duct 14. An operating handle that drives the air intake adjustment plate to swing is installed on the outside of the vertical suction duct 14.

[0039] The air separator 12 is provided with a material leveling hopper 10. The material leveling hopper 10 has an upper opening, a lower opening, and a material leveling channel 1001 connecting the upper opening and the lower opening. The lower opening of the material leveling hopper 10 is connected to the feed inlet of the feed member 9. An adjusting plate 1002 is provided in the material leveling channel 1001 and is hinged to the material leveling hopper 10. A material passage gap 103 is provided between the adjusting plate 1002 and the side plate of the material leveling hopper 10. An adjusting handle for adjusting the material passage gap 103 is provided on the outside of the material leveling hopper 10. The adjusting handle is connected to the hinge shaft of the adjusting plate 1002 and the material leveling hopper 10.

[0040] like Figure 4 , Figure 5 As shown, the feeding component 9 is provided with a feed inlet, a discharge outlet, and a feeding channel 901 connecting the feed inlet and the discharge outlet. A large impurity outlet 902 is provided on the side of the feeding component 9 adjacent to the large impurity settling chamber 122. The large impurity outlet 902 connects the feeding channel 901 and the large impurity settling chamber 122. A screening component 1 and a screen are provided inside the feeding channel 901.

[0041] The screening component 1 has a hinged end 3 and a free end opposite to the hinged end 3. The free end of the screening component 1 passes through the large impurity outlet 902. The hinged end 3 of the screening component 1 is hinged to the other side opposite to the large impurity outlet 902 of the feed channel 901. The screening component 1 is arranged inclined downwards along the direction from the hinged end 3 to the free end. The screening component 1 is arranged with a screening area 101 and a removal area 102 in sequence along its inclined direction. The screening area 101 has densely arranged screen holes. The removal area 102 has densely arranged elongated gaps 103 in a direction perpendicular to the inclined direction. The impurity removal roller 2 has a roller shaft 201 rotatably connected to the feed component 9. The free end of the screening component 1 overlaps on the roller shaft 201. The roller shaft 201 is provided with A debriding component 202 is provided, corresponding to the elongated gap 103 in the impurity removal zone 102 of the screening component 1. During rotation of the roller shaft 201, the debriding component 202 passes through the elongated gap 103. In this embodiment, the debriding component 202 consists of four rows of debriding rods 203 arranged on the roller shaft 201. The four rows of debriding rods 203 are evenly arranged along the circumference of the roller shaft 201. Each row of debriding rods 203 includes multiple debriding rods 203, which are spaced apart along the axial direction of the roller shaft 201. The debriding component 202 corresponds to the elongated gap 103 in the impurity removal zone 102 of the screening component 1, and during rotation of the roller shaft 201, the debriding component 202 passes through the elongated gap 103 in the impurity removal zone 102. The length direction of the debriding rod 203 is perpendicular to the axis of the roller shaft 201. Four rods 204 are fixedly connected to the roller shaft 201. The axes of the rods 204 are arranged parallel to the axis of the roller shaft 201. The four rods 204 are evenly arranged along the circumference of the roller shaft 201. The rotating roller shaft 201 and the rods 204 drive the screening element 1 to swing around the hinge end 3 of the screening element 1.

[0042] In this embodiment, the screening component 1 includes a sieve plate 104 and a plurality of grate bars 105. One end of the sieve plate 104 is the hinge end 3 of the screening component 1, and the other end of the sieve plate 104 opposite to the hinge end 3 is the connecting end 106. The plurality of grate bars 105 are connected to the connecting end 106 of the sieve plate 104, and the plurality of grate bars 105 are arranged in a direction perpendicular to the inclination direction of the screening component 1. The gap 103 is the gap between two adjacent grate bars 105. One end of the grate bar 105 is fixedly connected to the connecting end 106 of the sieve plate 104, and the other end of the grate bar 105 has a downward bending portion 4. The end of the grate bar 105 opposite to the bending portion 4 is fixedly connected to the bottom surface of the connecting end 106 of the sieve plate 104. The free end of the screening component 1 is the end where the bending portion 4 is located. The grate bar 105 overlaps on the roller shaft 201 of the impurity removal roller 2, and its overlapping position is close to the bending portion 4.

[0043] When screening grain materials, the impurity removal power device 128 and the blower 13 are started. The grain materials to be screened enter from the upper opening of the uniform hopper 10. The grain materials to be screened flow along the uniform channel 1001 in the uniform hopper 10 and flow through the material passage gap between the adjusting plate 1002 and the side plate of the uniform hopper 10. By operating the adjusting handle, the adjusting plate 1002 can be rotated relative to the uniform hopper 10, and the size of the material passage gap can be adjusted. The feeding of grain materials can be adjusted. Increasing the material passage gap can increase the amount of material entering the screen box 7, and decreasing the material passage gap can reduce the amount of material entering the screen box 7.

[0044] Grain material flows out from the lower opening of the uniform hopper 10 and into the feeder 9, flowing downwards along the feed channel 901 inside the feeder 9. The impurity removal power device 128 drives the roller shaft 201 of the impurity removal roller 2 to rotate, and the free end 4 of the screening component 1 overlaps with the impurity removal roller.

[0045] On the roller 201 of 2, under the action of the rotating roller 201 and the rod 204 fixedly connected to the roller 201, the screening element 1 swings up and down around its hinge end 3. When the grain material flows through the screening zone 101 of the screening element 1, the grain material and impurities with a particle size smaller than the sieve aperture of the screening zone 101 flow downward through the sieve aperture. Large impurities such as rope ends, paper pieces, plastic sheet pieces, and woven bag fragments with a particle size larger than the sieve aperture flow downward along the inclined screening element 1. When flowing through the impurity removal zone 102, under the action of the impurity removal element 202 set on the roller 201, the large impurities such as rope ends, paper pieces, plastic sheet pieces, and woven bag fragments remaining on the screening element 1 enter the large impurity settling chamber 122, thereby achieving the removal of large impurities.

[0046] Under the action of the fan 13, the airflow enters the uniform air chamber 121 of the air classifier 12 through the vertical suction channel 14, and then enters the feed channel 901 through the impurity removal inlet 903, and then flows out through the large impurity outlet 902. During the flow, the airflow meets the grain material flowing downward along the feed channel 901. The light and fine impurities such as straw and dust in the grain material are carried by the airflow and flow with the airflow. The airflow carrying the light and fine impurities enters the large impurity settling chamber 122. Since the internal space of the large impurity settling chamber 122 is much larger than the space of the impurity removal channel, the airflow enters the large space from the small space, the flow pressure of the airflow decreases, the flow velocity decreases, and the slightly larger impurities in the light and fine impurities in the airflow settle in the large impurity settling chamber 122, thus realizing the removal of large impurities. After the large impurities settle, the airflow enters the small impurity settling chamber 123 through the air passage 125. Since the internal space of the small impurity settling chamber 123 is larger than that of the air passage 125, the light and fine impurities in the airflow settle again. Then, the airflow enters through the inlet of the light impurity separator 131. As it flows through the pores of the light impurity separator 131, the remaining impurities in the airflow are filtered and settle into the small impurity settling chamber 123. The filtered airflow flows along the inner cavity of the light impurity separator 131, moving from the center of the inner cavity to both sides and entering the inlet of the blower 13. Then, it flows out from the outlet of the blower 13 and returns to the uniform air chamber 121 through the return air passage 15. The airflow circulates along the above flow process. This achieves air separation during the grain material flow process, removing light and fine impurities from the grain material.

[0047] After the light and fine impurities are removed by air separation, the grain material flows out from the discharge port at the lower end of the feed unit 9 and enters the screen box 7 through the feed port. The screen box 7 rotates in a plane under the action of the screening power device 8. The grain material entering the screen box 7 is screened and impurities are removed by the screening action of the screen grids arranged from top to bottom in the screen box 7. The clean grain after impurity removal flows out from the clean grain outlet of the screen box 7, and then passes through the magnetic separator 17 to remove iron filings from the grain. This completes the impurity removal and screening of the grain material.

[0048] It should be noted that the above-described embodiments are illustrative of the technical solution of this utility model and not limiting. Equivalent substitutions or other modifications made by those skilled in the art based on the prior art, as long as they do not exceed the concept and scope of the technical solution of this utility model, should be included within the scope of the claims of this utility model.

Claims

1. A combination air screen, characterized in that: The utility model relates to a grain screening device, including: a feeding part provided with a feeding port, a discharging port and a feeding channel connecting the feeding port and the discharging port, one side of the feeding part being provided with a large impurity outlet communicating with the feeding channel, a screening part provided with a hinged end and a free end opposite to the hinged end, the free end of the screening part passing through the large impurity outlet, the hinged end of the screening part being hingedly connected to the other side of the feeding channel opposite to the side where the large impurity outlet is located, the screening part being arranged downwardly and obliquely along the direction from the hinged end to the free end, the screening part being provided with a screening area and a large impurity removing area along the oblique direction in sequence, the screening area being provided with densely arranged screening holes, and the large impurity removing area being provided with long strip-shaped gaps densely arranged along the direction perpendicular to the oblique direction, a large impurity removing roller provided with a roller shaft rotatably connected to the feeding part, the free end of the screening part being overlapped on the roller shaft, the roller shaft being provided with a large impurity removing member corresponding to the long strip-shaped gaps of the large impurity removing area of the screening part, the large impurity removing member passing through the long strip-shaped gaps of the large impurity removing area during the rotation of the roller shaft.

2. A combination air screen according to claim 1 wherein: The roller shaft is connected with at least one rod member, the axis of the rod member being arranged in parallel with the axis of the roller shaft, the plurality of rod members being uniformly arranged along the circumferential direction of the roller shaft, and the roller shaft and the rod member driving the screening part to swing around the hinged end of the screening part.

3. A combination air screen according to claim 1 wherein: The large impurity removing member is at least one row of large impurity removing rods arranged on the roller shaft, the plurality of rows of large impurity removing rods being arranged along the circumferential direction of the roller shaft, each row of large impurity removing rods including a plurality of large impurity removing rods arranged along the axis direction of the roller shaft, the length direction of the large impurity removing rod being perpendicular to the axis of the roller shaft, and the large impurity removing rod corresponding to the long strip-shaped gaps of the large impurity removing area of the screening part.

4. A combination air screen according to claim 1 wherein: The screening part includes a screen plate and a plurality of grate bars, one end of the screen plate being the hinged end of the screening part, the other end of the screen plate opposite to the hinged end being a connecting end, the plurality of grate bars being connected to the connecting end of the screen plate and arranged along the direction perpendicular to the oblique direction of the screening part, and the gap being the gap between two adjacent grate bars.

5. A combination air separator screen according to claim 4, wherein: One end of the grate bar is fixedly connected to the connecting end of the screen plate, the other end of the grate bar having a downwardly bent portion, the end of the grate bar opposite to the bent portion being fixedly connected to the bottom surface of the connecting end of the screen plate, the free end of the screening part being the end where the bent portion is located, and the grate bar being overlapped on the roller shaft of the large impurity removing roller, the overlapped position of the grate bar being close to the bent portion.

6. A combined air separator according to any one of claims 1 to 5, characterized in that: The utility model further includes a screen box, the screen box being suspendedly connected to a rack through a hanger rod, the upper end of the hanger rod being connected to the rack, the lower end of the hanger rod being connected to the screen box, at least one layer of screen grids being arranged in the screen box, the screen box being provided with a feeding port, a clean grain outlet and an impurity outlet, the feeding port of the screen box being communicated with the discharging port of the feeding part through a flexible connecting pipe, a screening power device being connected to the screen box, and the screening power device driving the screen box to make planar rotary motion.

7. A combined air separator according to claim 6, characterized in that: A magnetic separator is arranged in the clean grain outlet of the screen box.

8. A combination air separator screen according to any one of claims 1 to 5, wherein: The air separation box is arranged on the frame, the feeding member is arranged in the air separation box, and the feeding member divides the inner cavity of the air separation box into an air uniformizing chamber and an air guiding and settling chamber. The air guiding and settling chamber is divided into a large impurity settling chamber and a small impurity settling chamber by a partition plate. The large impurity outlet of the feeding member is communicated with the feeding channel and the large impurity settling chamber. The air separation box is provided with a return air channel on the outside thereof, one end of the return air channel is communicated with the air uniformizing chamber, and the other end of the return air channel is communicated with the air outlet of the fan. The air separation box is provided with a large impurity pipe communicated with the large impurity settling chamber and a small impurity pipe communicated with the small impurity settling chamber on the outside thereof. The small impurity settling chamber is provided with a light impurity separation cylinder, the air inlet of the light impurity separation cylinder is communicated with the inner cavity of the small impurity settling chamber, the air outlet of the light impurity separation cylinder is communicated with the air inlet of the fan, the air inlet of the fan is also communicated with the upper end of the vertical air suction channel, and the lower end of the vertical air suction channel is communicated with the atmosphere.

9. A combination air screen according to claim 8, wherein: The cross section of the large impurity settling chamber and the small impurity settling chamber is V-shaped, the large impurity settling chamber is provided with a large impurity auger, the small impurity settling chamber is provided with a small impurity auger, the large impurity auger and the small impurity auger are connected with the impurity removing power device, and the impurity removing power device is also connected with the roller shaft of the impurity removing roller.

10. A combination air separator screen according to any one of claims 1 to 5, wherein: The uniformizing hopper is communicated with the feeding port of the feeding channel, the uniformizing hopper has an upper end opening, a lower end opening and a uniformizing channel communicated with the upper end opening and the lower end opening, the lower end opening of the uniformizing hopper is communicated with the feeding port of the feeding member, the uniformizing channel is provided with an adjusting plate hingedly connected with the uniformizing hopper, a material passing gap is arranged between the adjusting plate and the side plate of the uniformizing hopper, the outside of the uniformizing hopper is provided with an adjusting handle for adjusting the material passing gap, and the adjusting handle is connected with the hinged shaft of the adjusting plate and the uniformizing hopper.

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