Grain cleaner

Abstract

The invention relates to the technical field of grain screening, and discloses a grain cleaning machine which comprises a cleaning device arranged at the bottom of a specific gravity screen, and the cleaning device comprises a linear moving mechanism, a moving plate, a pressure accumulation jarring mechanism and a screen hole dredging mechanism; the linear moving mechanism is arranged at the bottom of the specific gravity screen and provided with a moving end moving in the length direction of the screen face of the specific gravity screen. The movable plate comprises a first plate body and a second plate body, the first plate body is connected with the movable end, a sliding groove is formed in the top of the first plate body, the second plate body is slidably connected into the sliding groove, and a plurality of storage holes are formed in the top of the second plate body; the pressure accumulation jarring mechanism comprises a rotary driving part, an incomplete gear, a rack and an elastic reset piece; the telescopic column is slidably connected into the storage hole; according to the cleaning device, the blocked area on the specific gravity screen can be cleaned in the cleaning operation process, periodic jarring is conducted through the pressure accumulation jarring mechanism, static accumulation of wet grains is reduced, and the wet grains blocked in screen holes are ejected out through the arranged dredging mechanism for targeted cleaning.

Description

Technical Field

[0001] The present invention relates to the technical field of grain screening, and specifically to a grain cleaning machine. Background Art

[0002] Currently, when cleaning grains, it is generally carried out by cooperating a vibrating specific gravity screen and a winnowing machine. The grains that fall on the specific gravity screen rise and fall up and down due to vibration, and the winnowing machine is used to blow up the light impurities for separation from the heavy impurities.

[0003] Grains can be divided into dry grains and wet grains. Dry grains refer to grains with a moisture content lower than the safe storage threshold and can be directly stored or processed for a long time. Wet grains refer to grains with a moisture content exceeding the safe storage threshold and need to be dried or processed. Traditional grain cleaning machines are mainly used to clean dry grains. For some special wet grains, such as grains harvested in the rainy season, grains affected by moisture during storage, and grains with high natural moisture, when cleaning and removing impurities through a grain cleaning machine, the surface moisture of the mixed wet grains will cause the grains to adhere to each other, reducing the separation effect of the airflow on the impurities. When screening on the specific gravity screen, the wet grains are easily adhered to the screen surface or screen holes. When adhered to the screen surface, they will stack and adhere to form a mass, making it difficult for the winnowing to blow the impurities, affecting the winnowing accuracy. When adhered inside the screen holes, it will cause serious blockage, making it difficult for the airflow to pass through normally, affecting the operation of the winnowing.

[0004] Most of the current cleaning structures are cleaned by using a scraper that can move along the length direction of the specific gravity screen or a rotating brush roller. The scraper can usually only scrape the wet grains attached to the screen surface and it is difficult to reach and thoroughly clean the wet grains attached inside the screen holes. Moreover, the moving scraper will push the grains to one side of the specific gravity screen, affecting the process of flat winnowing and impurity removal. Although the brush roller can use the rotating brush heads to deeply clean the inside of the screen holes, the rotating brush heads will throw out all the grains and impurities in contact with them, thus affecting the screening accuracy. Therefore, the above cleaning structures are difficult to clean the different area positions where the wet grains adhere in a targeted manner, and can only be cleaned when the machine is stopped and cannot be cleaned during the cleaning and screening operation, and there will also be problems affecting the continuous operation of the cleaning machine. Summary of the Invention

[0005] The purpose of the present invention is to provide a grain cleaning machine to solve the problem that the existing grain cleaning machine has a cleaning device that is difficult to clean the different area positions where the wet grains adhere in a targeted manner during the cleaning and screening operation.

[0006] The technical solution of the present invention is as follows:

[0007] A grain cleaning machine includes a cleaning device arranged at the bottom of a specific gravity sieve. The cleaning device includes a linear movement mechanism, a moving plate, a pressure accumulation shock mechanism, and a dredging mechanism. The linear movement mechanism is arranged at the bottom of the specific gravity sieve and has a moving end that moves along the length direction of the sieve surface of the specific gravity sieve. The moving plate is arranged perpendicular to the moving direction of the linear movement mechanism. The moving plate includes a first plate body and a second plate body that are vertically stacked. The first plate body is connected to the moving end. A vertically arranged chute is formed at the top of the first plate body. The second plate body is slidably connected in the chute. A plurality of storage holes are arranged at the top of the second plate body along the width direction of the sieve surface of the specific gravity sieve. The pressure accumulation shock mechanism includes: a rotary driving part connected to the side wall of the first plate body; an incomplete gear connected to the output end of the rotary driving part; a rack arranged vertically, one side of the rack is connected to the side wall of the second plate body, and the other side of the rack is engaged with the incomplete gear; an elastic resetting part connected between the first plate body and the second plate body for driving the rack to reset after the incomplete gear disengages from the rack. The dredging mechanism includes a plurality of telescopic columns arranged in the plurality of storage holes one by one. The telescopic columns can telescopically move in the storage holes to eject the blockage in the sieve holes.

[0008] Preferably, as a further improvement of the present invention, the telescopic column includes a column body and a first spring. The column body is slidably connected in the storage hole and has a diameter smaller than the diameter of the sieve holes of the specific gravity sieve. The first spring is connected between the bottom of the column body and the bottom of the storage groove. The top of the column body is hemispherical.

[0009] Preferably, as a further improvement of the present invention, the first plate body is a first U-shaped rod with an upward opening, and chutes are arranged at the ends of the two side walls of the opening of the first U-shaped rod. The second plate body is a second U-shaped rod with a downward opening, and the two side walls of the opening of the second U-shaped rod are slidably connected in the two chutes.

[0010] Preferably, as a further improvement of the present invention, a first support plate is fixed on the side wall of the first plate body, the rotary driving part is arranged on the top of the first support plate, a second support plate is fixed on the side wall of the second plate body, the rack is fixed at the bottom of the second support plate, a guiding block is fixed on the top of the first support plate, a guiding groove is formed on the side wall of the guiding block facing the incomplete gear, and the rack is slidably connected in the guiding groove.

[0011] Preferably, as a further improvement of the present invention, mounting seats are fixed at both ends of the bottom of the specific gravity sieve. First sliding rods are provided on both sides of the first plate body. The first sliding rods are horizontally installed and fixed between the two mounting seats, and the side wall of the first plate body is slidably connected to the first sliding rods through first clamping members. Second sliding rods are provided on both sides of the second plate body, and the side wall of the second plate body is slidably connected to the second sliding rods through second clamping members. Two groups of vertically arranged strip-shaped notches are symmetrically formed on the opposite side walls of the two mounting seats, and both ends of each second sliding rod are respectively slidably connected in a group of strip-shaped notches.

[0012] Preferably, as a further improvement of the present invention, the elastic resetting member includes four second springs. Each second spring is respectively arranged in each strip-shaped notch, and both ends of the second spring are respectively connected to the bottom of the second sliding rod and the notch wall of the strip-shaped notch.

[0013] Preferably, as a further improvement of the present invention, there are multiple moving plates, and they are evenly arranged along the first direction of the specific gravity sieve. Each moving plate is connected to the moving end of the linear moving mechanism.

[0014] Preferably, as a further improvement of the present invention, the linear moving mechanism includes a telescopic cylinder and multiple groups of folding rod assemblies; the cylinder body of the telescopic cylinder is hinged to one of the mounting seats; multiple groups of folding rod assemblies are evenly arranged along the first direction of the specific gravity sieve. The number of folding rod assemblies is the same as the number of moving plates. The folding rod assembly includes a first connecting rod, a second connecting rod, and a transmission structure. One end of the first connecting rod and one end of the second connecting rod are hinged to each other. The transmission structure includes a connecting plate and two gear shafts. The connecting plate is fixed to the side wall of the first plate body. One end of the two gear shafts is rotatably connected to the first plate body, and the two gear shafts are meshed with each other. The other end of the second connecting rod is fixed to the side wall of one of the gear shafts. One end of the first connecting rod in the folding rod assembly close to the telescopic cylinder is hinged to the lower end of the first sliding rod, and the side wall of the first connecting rod is hinged to the piston rod end of the telescopic cylinder. The first connecting rod in the remaining folding rod assemblies is fixed to the side wall of another gear shaft in the adjacent front folding rod assembly.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. By integrally arranging the cleaning structure at the bottom of the specific gravity sieve, it can follow the specific gravity sieve for the air separation operation.

[0017] 2. The cleaning structure, through the cooperation of the pressure accumulator shock mechanism and the moving plate, can drive the incomplete gear to rotate by the rotary drive part when the specific gravity sieve is performing screening work. Since some teeth on the incomplete gear remain engaged with the rack, as the incomplete gear rotates, it will drive the rack and the second plate body to move downward and compress the elastic reset part for energy storage. When the incomplete gear continues to rotate until the teeth on it no longer engage with the rack, under the elastic force of the elastic reset part, it will drive the rack and the second plate body to move upward rapidly, and through the top of the second plate body, periodic mechanical shock and vibration energy release are carried out on the lower side of the sieve surface of the specific gravity sieve. By means of shock, the adhesion interface of wet grains is broken, the contact time between wet grains and the sieve plate is reduced, and the vibration energy makes the wet grain particles produce jumping movement, reducing the phenomenon of blockage caused by the static accumulation of wet grains on the sieve surface of the specific gravity sieve.

[0018] 3. The cleaning structure, through the arranged dredging mechanism and linear movement mechanism, can adjust the position of the telescopic column, and use the telescopic column to extend out of the receiving hole to eject the wet grains blocked in the sieve holes, so as to carry out targeted cleaning on the positions inside the sieve holes that are difficult to clean. Brief Description of the Drawings

[0019] Figure 1 It is a schematic connection diagram of the specific gravity sieve and the cleaning device in a grain cleaning machine of the present invention.

[0020] Figure 2 It is a three-dimensional structure schematic diagram of the cleaning device in a grain cleaning machine of the present invention.

[0021] Figure 3 For the present invention Figure 2 Partial enlarged schematic diagram at A in it.

[0022] Figure 4 For the present invention Figure 2 Partial enlarged schematic diagram at B in it.

[0023] Figure 5 It is a top view structure schematic diagram of the cleaning device in a grain cleaning machine of the present invention.

[0024] Figure 6 For the present invention Figure 5 Cross-sectional structure schematic diagram at C-C in it.

[0025] Figure 7 For the present invention Figure 6 Partial enlarged schematic diagram at D in it.

[0026] Figure 8 It is a schematic diagram of the overall structure of a grain cleaning machine of the present invention.

[0027] Figure 9This is a schematic diagram showing the installation positions of the cleaning device and the air separation mechanism in a grain cleaning machine of the present invention.

[0028] Figure 10 This is a schematic diagram of the structure of the air separation mechanism in a grain cleaning machine of the present invention. Detailed implementation manners

[0029] The following Figures 1 to 10 , the detailed implementation manners of the present invention will be described in detail. In the description of the invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0030] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features; in the description of the invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0031] Embodiment

[0032] As Figures 1 to 7As shown in the figure, an embodiment of the present invention provides a grain cleaning machine, which includes a cleaning device arranged at the bottom of a specific gravity sieve 1. The cleaning device includes a linear movement mechanism, a moving plate 2, a pressure accumulation shock mechanism, and a dredging mechanism. The linear movement mechanism is arranged at the bottom of the specific gravity sieve 1. The linear movement mechanism has a moving end that moves along the length direction of the sieve surface of the specific gravity sieve 1. The moving plate 2 is arranged perpendicular to the moving direction of the linear movement mechanism. The moving plate 2 includes a first plate body 21 and a second plate body 22 that are vertically stacked. The first plate body 21 is connected to the moving end. A vertically arranged chute is opened at the top of the first plate body 21. The second plate body 22 is slidably connected in the chute. A plurality of storage holes 221 are arranged at the top of the second plate body 22 along the width direction of the sieve surface of the specific gravity sieve 1. The pressure accumulation shock mechanism 3 includes: a rotary drive part 31, which is a motor and is connected to the side wall of the first plate body 21; an incomplete gear 32, which is connected to the output end of the rotary drive part 31; a rack 33, which is vertically arranged. One side of the rack 33 is connected to the side wall of the second plate body 22, and the other side of the rack 33 meshes with the incomplete gear 32; an elastic reset part 34, which is connected between the first plate body 21 and the second plate body 22 and is used to drive the rack 33 to reset after the incomplete gear 32 disengages from the rack 33. The dredging mechanism includes a plurality of telescopic columns 5 arranged in the plurality of storage holes 221 in a one-to-one correspondence. The telescopic columns 5 can telescopically move in the storage holes 221 to eject the clogging objects in the sieve holes.

[0033] In this embodiment, during the process of cleaning grains by the specific gravity sieve 1, the pressure accumulation shock mechanism 3 is used to drive the second plate body 22 in the moving plate 2 to perform a pressure accumulation shock on the sieve surface of the specific gravity sieve 1, which can effectively reduce adhesion. When hitting, the rotary drive part 31 is controlled to drive the incomplete gear 32 to rotate. Since some teeth on the incomplete gear 32 remain meshed with the rack 33, as the incomplete gear 32 rotates, the rack 33 and the second plate body 22 will be driven to move downward and compress the elastic reset part 34 for energy storage. When the incomplete gear 32 continues to rotate until the teeth on it no longer mesh with the rack 33, under the elastic force of the elastic reset part 34, the rack 33 and the second plate body 22 will be driven to move upward quickly, and the top of the second plate body 22 will perform a shock on the sieve surface of the specific gravity sieve 1.

[0034] When a certain sieve hole area of the specific gravity sieve 1 is severely blocked, first control the rotation drive unit 31 to keep the incomplete gear 32 in a meshed state with the rack 33, so as to fix and support the second plate body 22. Then, drive the first plate body 21 to move along the length direction of the specific gravity sieve 1 through the linear movement mechanism, approaching the blocked sieve hole area. Then, perform telescopic movement through multiple telescopic columns 5 arranged in the receiving holes 221 at the top of the second plate body 22, and use the telescopic telescopic columns 5 to push out the wet grains blocked in the sieve holes. By controlling the movement position of the second plate body 22 driven by the linear movement mechanism, each row of sieve holes can be cleaned in sequence by the dredging mechanism.

[0035] In another embodiment of the present invention, as Figure 2 , Figure 5 , Figure 6 and Figure 7 shown, the telescopic column 5 includes a column body 41 and a first spring 42. The column body 41 is slidably connected in the receiving hole 221 and has a diameter smaller than the diameter of the sieve holes of the specific gravity sieve 1. The first spring 42 is connected between the bottom of the column body 41 and the bottom of the receiving groove 321. The top of the column body 41 is hemispherical.

[0036] In this embodiment, by setting the top of the column body 41 as hemispherical and cooperating with the first spring 42, when the second plate body 22 is driven to move along the length direction of the specific gravity sieve through the linear movement mechanism, the sieve surface of the specific gravity sieve without sieve holes will squeeze the top of the column body 41, causing it to contract in the receiving hole 221 and compress the first spring 42. When moving past the sieve hole, under the elastic force of the first spring 42, the column body 41 is driven to extend into the sieve hole to push out the wet grains blocked in the sieve hole. As the linear movement mechanism continues to move, since the top of the column body 41 is hemispherical, the arc surface can be squeezed by the sieve hole, causing it to automatically move downward and withdraw from the sieve hole.

[0037] Furthermore, the first plate body 21 is a first U-shaped rod with its opening facing upward, and sliding grooves are provided at the ends of the two side walls of the opening of the first U-shaped rod. The second plate body 22 is a second U-shaped rod with its opening facing downward, and the two side walls of the opening of the second U-shaped rod are slidably connected in the two sliding grooves.

[0038] Through the above settings, the overall weight of the first plate body 21 and the second plate body 22 can be effectively reduced, so that the linear movement mechanism can drive the first plate body 21 to translate, and the pressure accumulation shock mechanism can drive the second plate body 22 to move vertically for shock.

[0039] Further, a first support plate 51 is fixed on the side wall of the first plate body 21, the rotary driving part 31 is arranged on the top of the first support plate 51, a second support plate 52 is fixed on the side wall of the second plate body 22, a rack 33 is fixed on the bottom of the second support plate 52, a guide block 53 is fixed on the top of the first support plate 51, a guide groove 451 is formed in the side wall of the guide block 53 facing the incomplete gear 32, and the rack 33 is slidably connected in the guide groove 451.

[0040] In this embodiment, through the arranged guide block 53, during the shock process of the pressure accumulation shock mechanism, the position of the movement of the rack 33 can be limited and guided by the guide groove 451, so that it can move along the vertical direction and can be engaged with the incomplete gear 32.

[0041] In another embodiment of the present invention, as Figure 1 and Figure 2 shown, mounting seats 61 are fixed at both ends of the bottom of the specific gravity sieve 1, first sliding rods 62 are arranged on both sides of the first plate body 21, the first sliding rods 62 are horizontally fixed between the two mounting seats 61, and the side wall of the first plate body 21 is slidably connected with the first sliding rods 62 through a first clamping member 63. Second sliding rods 64 are arranged on both sides of the second plate body 22, and the side wall of the second plate body 22 is slidably connected with the second sliding rods 64 through a second clamping member 65. Two groups of vertically arranged strip-shaped notches 611 are symmetrically formed on the opposite side walls of the two mounting seats 61, and both ends of each second sliding rod 64 are respectively slidably connected in a group of strip-shaped notches 611.

[0042] In this embodiment, through the above arrangement, during the process of the linear movement mechanism driving the moving plate 2 to move, the first plate body 21 and the second plate body 22 can be guided and supported by the first sliding rods 62 and the second sliding rods 64 respectively.

[0043] Among them, the structures of the first clamping member 63 and the second clamping member 65 are the same, and both include a C-shaped chuck and a fixing rod. One end of the fixing rod is used for fixing with the side wall of the first plate body 21 or the second plate body 22, the other end of the fixing rod is fixed with the back side of the opening of the C-shaped chuck, and the C-shaped chuck is slidably clamped on the first sliding rod 62 or the second sliding rod 64. The purpose of setting the C-shaped chuck is to avoid the first support plate 51 and the second support plate 52 during sliding.

[0044] Specifically, the elastic reset member 34 includes four second springs, each second spring is respectively arranged in each strip-shaped notch 611, and both ends of the second spring are respectively connected with the bottom of the second sliding rod 64 and the groove wall of the strip-shaped notch 611.

[0045] In another embodiment of the present invention, as Figure 2As shown, there are multiple moving plates 2, which are evenly arranged along the first direction of the specific gravity sieve 1. Each moving plate 2 is connected to the moving end of the linear moving mechanism. By setting the moving plates 2 in multiple numbers, the number of times of cleaning the sieve holes can be increased, thereby improving the cleaning degree.

[0046] Specifically, as Figure 1 , Figure 2 , Figure 5 and Figure 6 shown, the linear moving mechanism includes a telescopic cylinder 71 and multiple sets of folding rod assemblies; the cylinder body of the telescopic cylinder 71 is hinged to one of the mounting seats 61; multiple sets of folding rod assemblies are evenly arranged along the first direction of the specific gravity sieve 1, and the number of folding rod assemblies is the same as the number of moving plates 2. The folding rod assembly includes a first connecting rod 72, a second connecting rod 73 and a transmission structure. One end of the first connecting rod 72 and one end of the second connecting rod 73 are hinged to each other. The transmission structure includes a connecting plate 74 and two gear shafts 75. The connecting plate 74 is fixed to the side wall of the first plate body 21. One end of the two gear shafts 75 is rotatably connected to the first plate body 21, and the two gear shafts 75 mesh with each other. The other end of the second connecting rod 73 is fixed to the side wall of one of the gear shafts 75. One end of the first connecting rod 72 in the folding rod assembly close to the telescopic cylinder 71 is hinged to the lower end of the first sliding rod 62, and the side wall of the first connecting rod 72 is hinged to the piston rod end of the telescopic cylinder 71. The first connecting rod 72 in the remaining folding rod assemblies is fixed to the side wall of another gear shaft 75 in the adjacent front folding rod assembly.

[0047] In this embodiment, it can drive multiple moving plates 2 to perform folding telescopic movement along the first sliding rod 62 and the second sliding rod 64. When performing cleaning movement, by controlling the telescopic cylinder 71 to extend, the piston rod end of the telescopic cylinder 71 will push the first connecting rod 72 connected to it to rotate around the hinge point of the first sliding rod 62. Due to the existence of the transmission structure, the adjacent folding rod assemblies are sequentially unfolded under the meshing action of the two gear shafts 75. After unfolding, as Figure 5 shown, thereby driving multiple moving plates 2 to slide in sequence, and the farther away they are, the faster the unfolding sliding speed. In one unfolding process, multiple moving plates 2 are used in cooperation with the dredging mechanism to dredge the sieve holes of the specific gravity sieve multiple times, improving the dredging efficiency. After the cleaning is completed, control the telescopic cylinder 71 to contract, and contract multiple moving plates 2 to one side to avoid blocking the screening process of the sieve holes of the specific gravity sieve.

[0048] Among them, as Figure 2 , Figure 5 and Figure 6As shown, in order to limit the folded state of the folding rod assembly and the moving plate 2 to avoid creating a dead zone for the movement of the telescopic cylinder 71 after contraction, a limiting bracket 76 is connected to the side wall of the mounting seat 61 on the side close to the telescopic cylinder 71. One end of the first connecting rod 72 in the folding rod assembly close to the telescopic cylinder 71 is hinged to the bottom of the limiting bracket 76. The limiting bracket 76 can limit the positions of the multiple moving plates 2 in the contracted and folded state.

[0049] In another embodiment of the present invention, as Figures 8 to 10 shown, the specific gravity sieve 1 and the cleaning device at the bottom of the specific gravity sieve 1 are both provided on the grain cleaning machine 8. The specific gravity sieve 1 is connected to the vibration driving structure on the grain cleaning machine 8. A winnowing mechanism is provided below the specific gravity sieve 1. By adjusting the air flow rate of the winnowing mechanism 9 and setting a reasonable blowing angle, the phenomenon of wet grains adhering can be further reduced.

[0050] Specifically, the winnowing mechanism 9 includes three air boxes 91 evenly distributed along the length direction of the specific gravity sieve 1, which are erected and fixed on the frame of the grain cleaning machine 8. An air outlet is opened at the top of the air box 91, and the air outlet is located directly below the specific gravity table 4. An air equalizing plate 92 is inclined at the air outlet, and the included angle between the air equalizing plate 92 and the horizontal plane is 4° - 5°. A plurality of inclined air holes are provided on the air equalizing plate 92, and the included angle between each air hole and the horizontal plane is 15°. Two sets of impeller groups 93 are provided in each air box 91. The rotating shafts of adjacent impeller groups 93 are connected by a belt drive structure 94. The impeller groups 93 are driven to rotate by using a variable frequency motor 95 to drive the belt drive mechanism to realize the winnowing operation.

[0051] The above discloses only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A grain cleaning machine, comprising a cleaning device arranged at the bottom of a specific gravity screen (1), characterized in that: The cleaning device comprises: A linear moving mechanism is arranged at the bottom of the specific gravity screen (1), and the linear moving mechanism has a moving end that moves along the length direction of the screen surface of the specific gravity screen (1); A movable plate (2) is arranged perpendicularly to the moving direction of the linear moving mechanism, the movable plate (2) comprises a first plate body (21) and a second plate body (22) which are arranged vertically and stacked up and down, the first plate body (21) is connected to the movable end, a vertically arranged slide groove is provided on the top of the first plate body (21), the second plate body (22) is slidably connected in the slide groove, and a plurality of receiving holes (221) are provided on the top of the second plate body (22) along the width direction of the screen surface of the specific gravity screen (1); The pressure-accumulating shock mechanism (3) comprises: a rotating driving part (31) connected to the side wall of the first plate body (21); an incomplete gear (32) connected to the output end of the rotating driving part (31); a rack (33) arranged vertically, one side of the rack (33) connected to the side wall of the second plate body (22), and the other side of the rack (33) meshing with the incomplete gear (32); and an elastic reset member (34) connected between the first plate body (21) and the second plate body (22) and used for driving the rack (33) to reset after the incomplete gear (32) and the rack (33) are separated. The dredging mechanism comprises a plurality of telescopic columns (4) which are arranged in a one-to-one correspondence in the plurality of receiving holes (221); the telescopic columns (4) can be telescopically moved in the receiving holes (221) to push out the blockages in the sieve holes.

2. The grain cleaning machine according to claim 1, characterized in that: The telescopic column (4) comprises a column (41) and a first spring (42); the column (41) is slidably connected in the receiving hole (221) and has a diameter smaller than the diameter of the mesh of the specific gravity screen (1); the first spring (42) is connected between the bottom of the column (41) and the bottom of the receiving groove (321); and the top of the column (41) is hemispherical.

3. The grain cleaning machine according to claim 1, characterized in that: The first plate body (21) is a first U-shaped rod, the opening of the first U-shaped rod is arranged upward, and the two side wall ends of the opening of the first U-shaped tube are provided with the sliding grooves, and the second plate body (22) is a second U-shaped rod, the opening of the second U-shaped rod is arranged downward, and the two side walls of the opening of the second U-shaped rod are slidably connected in the two sliding grooves.

4. The grain cleaning machine according to claim 3, characterized in that: A first support plate (51) is connected to the side wall of the first plate body (21), the rotation driving part (31) is arranged on the top of the first support plate (51), a second support plate (52) is connected to the side wall of the second plate body (22), the rack (33) is fixed to the bottom of the second support plate (52), a guide block (53) is fixed to the top of the first support plate (51), a guide groove (451) is provided on the side wall of the guide block (53) facing the incomplete gear (32), and the rack (33) is slidably connected in the guide groove (451).

5. The grain cleaning machine according to claim 1, characterized in that: Mounting seats (61) are fixed at both ends of the bottom of the specific gravity screen (1), first slide bars (62) are provided on both sides of the first plate body (21), the first slide bars (62) are horizontally erected and fixed between the two mounting seats (61), and the side walls of the first plate body (21) are slidably connected to the first slide bars (62) through first clamping members (63), second slide bars (64) are provided on both sides of the second plate body (22), and the side walls of the second plate body (22) are slidably connected to the second slide bars (64) through second clamping members (65), and two groups of vertically arranged strip notches (611) are symmetrically provided on the side walls directly facing the two mounting seats (61), and the two ends of each second slide bar (64) are slidably connected in a group of strip notches (611).

6. The grain cleaning machine according to claim 5, characterized in that: The elastic return member (34) comprises four second springs, each of which is arranged in each strip-shaped slot (611), and the two ends of the second spring are respectively connected to the bottom of the second sliding rod (64) and the slot wall of the strip-shaped slot (611).

7. The grain cleaning machine according to claim 5, characterized in that: There are a plurality of movable plates (2), which are evenly distributed and movable along the first direction of the specific gravity screen (1), and each movable plate (2) is connected to the movable end of the linear moving mechanism.

8. The grain cleaning machine according to claim 7, characterized in that: The linear motion mechanism comprises: A telescopic cylinder (71), the cylinder body of which is hingedly connected to one of the mounting seats (61); A plurality of folding rod assemblies are evenly arranged along the first direction of the specific gravity screen (1), the number of the folding rod assemblies is the same as the number of the movable plate (2), the folding rod assemblies include a first connecting rod (72), a second connecting rod (73) and a transmission structure, one end of the first connecting rod (72) and one end of the second connecting rod (73) are hinged to each other, the transmission structure includes a connecting plate (74) and two gear shafts (75), the connecting plate (74) is fixed to the side wall of the first plate body (21), one end of the two gear shafts (75) is connected to the first plate body (21), and one end of the two gear shafts (75) is connected to the first plate body (21). The first plate body (21) is rotatably connected, and the two gear shafts (75) are meshed with each other, the other end of the second connecting rod (73) is fixed to the side wall of one of the gear shafts (75), one end of the first connecting rod (72) in the folding rod assembly close to the telescopic cylinder (71) is hinged to the lower end of the first sliding rod (62), and the side wall of the first connecting rod (72) is hinged to the piston rod end of the telescopic cylinder (71), and the first connecting rod (72) in the remaining folding rod assemblies is fixed to the side wall of another gear shaft (75) in the adjacent front folding rod assembly.

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