Fine grinding device for sandstone processing

Abstract

The utility model relates to sandstone processing technical field, and disclose a kind of fine grinding device for sandstone processing, including primary grinding box and secondary grinding box, the inside of primary grinding box is provided with first grinding mechanism, for the coarse grinding of sandstone, the inside of secondary grinding box is provided with second grinding mechanism, for the fine grinding of the sandstone of coarse grinding, the top of primary grinding box is communicated with feed hopper.The utility model integrates first grinding mechanism of coarse grinding and second grinding mechanism of fine grinding by one, through inverted V shape connecting pipe natural link, realizes the continuous automation production of sandstone from feeding, coarse crushing, fine grinding to discharge, greatly improves production efficiency, by connecting assembly, the initial position of upper grinding disc in circular table shape fine grinding cavity can be conveniently adjusted, thereby the final discharge granularity is accurately controlled, to satisfy the sandstone of different granularity ground.

Description

Technical Field

[0001] This utility model relates to the field of sand and gravel processing technology, and in particular to a fine grinding device for sand and gravel processing. Background Technology

[0002] Sand and gravel refer to a loose mixture of sand and gravel. In the construction, building materials and mining industries, sand and gravel need to be ground into powders of different fineness to meet various application requirements.

[0003] Existing sand and gravel grinding devices, such as ball mills and Raymond mills, are mostly single-stage grinding devices, which are difficult to process large pieces of sand and gravel into high-fineness powder in one go. If multiple devices are connected in series, it will lead to problems such as large footprint, complex system and high cost. Therefore, a fine grinding device for sand and gravel processing is proposed to solve the above problems. Utility Model Content

[0004] (a) Purpose of the utility model To address the technical problems existing in the background art, this utility model proposes a fine grinding device for sand and gravel processing. The first grinding mechanism can perform coarse grinding of sand and gravel, and the second grinding mechanism can perform fine grinding of the coarsely ground sand and gravel, which has the advantages of improving the grinding effect and grinding efficiency of sand and gravel.

[0005] (II) Technical Solution This utility model provides a fine grinding device for sand and gravel processing, including a primary grinding box and a secondary grinding box. The primary grinding box is equipped with a first grinding mechanism for coarse grinding of sand and gravel, and the secondary grinding box is equipped with a second grinding mechanism for fine grinding of the coarsely ground sand and gravel.

[0006] The top of the primary grinding box is connected to a feed funnel, and the bottom of the primary grinding box is connected to an inverted V-shaped connecting pipe. The bottom of the inverted V-shaped connecting pipe is connected to the top of the secondary grinding box.

[0007] The front of the secondary grinding box is hinged with a door. Inside the secondary grinding box is a feeding funnel located below the second grinding mechanism. The inner bottom wall of the feeding funnel is connected to a feeding pipe extending to the bottom of the secondary grinding box.

[0008] Preferably, the first grinding mechanism includes a drive box, two rotating rods, two grinding rollers, a first reduction motor, two gears, and two guide plates. The drive box is located outside the primary grinding box. The interiors of the two rotating rods are rotatably connected and extend into the interior of the primary grinding box. The two grinding rollers are respectively located outside the two rotating rods and inside the primary grinding box. The first reduction motor is located outside the drive box, and its output shaft is connected to one of the rotating rods. The two gears are respectively located outside the two rotating rods and mesh inside the drive box. The two guide plates are both located on the inner sidewall of the primary grinding box and are symmetrically distributed. The bottoms of the two guide plates correspond to the tops of the two grinding rollers.

[0009] Preferably, the second grinding mechanism includes a lower grinding disc, a fine grinding chamber, a second geared motor, a rotating shaft, a connecting assembly, a guide plate, and an upper grinding disc. The lower grinding disc is located inside the secondary grinding chamber. The fine grinding chamber is located at the top of the lower grinding disc and extends to its bottom. The fine grinding chamber is frustum-shaped. The second geared motor is located at the top of the secondary grinding chamber. The rotating shaft is located on the output shaft of the second geared motor and extends into the secondary grinding chamber. The connecting assembly is located at the bottom of the rotating shaft. The guide plate is located below the rotating shaft. The rotating shaft is connected to the guide plate through the connecting assembly. The upper grinding disc is located below the guide plate and is located inside the fine grinding chamber.

[0010] The inner wall of the fine grinding chamber and the outer side of the upper grinding disc form a grinding area with a gradually decreasing gap from top to bottom.

[0011] Preferably, the connecting component includes a fixing block, a connecting groove, a connecting block, a driving module, and a guiding module. The fixing block is located at the bottom end of the rotating shaft, the connecting groove is opened at the bottom of the fixing block, the connecting block is slidably connected to the inside of the connecting groove, the driving module is located inside the connecting groove, the driving module is connected to the connecting block, and is used to adjust the height of the connecting block. The guiding module is located on the outside of the connecting block.

[0012] Preferably, the drive module includes a bidirectional threaded rod, two threaded blocks, two sets of limiting units, and two connecting rods. The bidirectional threaded rod is located on the outside of the fixed block and extends into the interior of the connecting groove. An adjusting handwheel is disposed on the outside of the fixed block. The two threaded blocks are respectively threaded to the two ends of the bidirectional threaded rod with opposite thread directions. The two sets of limiting units are respectively located on the top of the two threaded blocks. The two connecting rods are respectively hinged to the bottom of the two threaded blocks by pins. The bottom ends of the two connecting rods are both hinged to the top of the connecting block by pins.

[0013] Preferably, the guiding module includes two guide blocks and two guide grooves. The two guide grooves are respectively opened on the inner sidewall of the connecting groove and are symmetrically distributed. The two guide blocks are respectively located on the outer side of the connecting block, and the two guide blocks are respectively slidably connected to the inside of the two guide grooves.

[0014] Preferably, both sets of limiting units include limiting blocks and limiting grooves. The two limiting grooves are opened on the inner top wall of the connecting groove, and the two limiting blocks are respectively located on the top of the two threaded blocks. The two limiting blocks are slidably connected to the inside of the two limiting grooves.

[0015] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial technical effects: 1. This fine grinding device for sand and gravel processing integrates a first grinding mechanism for coarse grinding and a second grinding mechanism for fine grinding into one unit. They are naturally connected by an inverted V-shaped connecting pipe, realizing continuous automated production of sand and gravel from feeding, coarse crushing, fine grinding to discharge, which greatly improves production efficiency. The initial position of the upper grinding disc in the frustum-shaped fine grinding chamber can be easily adjusted through the connecting components, thereby accurately controlling the final discharge particle size to meet the requirements of grinding sand and gravel of different particle sizes.

[0016] 2. This fine grinding device for sand and gravel processing forms a gradually narrowing grinding channel through the frustum-shaped grinding chamber and the upper grinding disc. Under the action of gravity and centrifugal force, the material moves from top to bottom, and the particle size decreases from large to small. Qualified fine powder can be discharged from the bottom in time, avoiding qualified material from being retained in the grinding zone and being over-ground, thus ensuring that the product particle size distribution is uniform. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a fine grinding device for sand and gravel processing proposed in this utility model.

[0018] Figure 2 This is a cross-sectional view of the primary grinding box, the first grinding mechanism, the feed funnel, and the inverted V-shaped connecting pipe in a fine grinding device for sand and gravel processing proposed in this utility model.

[0019] Figure 3 This is a top cross-sectional view of the primary grinding box and the first grinding mechanism in a fine grinding device for sand and gravel processing proposed in this utility model.

[0020] Figure 4 This is a cross-sectional view of the secondary grinding box, the second grinding mechanism, the feeding funnel, and the feeding pipe in a fine grinding device for sand and gravel processing proposed in this utility model.

[0021] Figure 5This is a front sectional view of the secondary grinding box, the second grinding mechanism, the feeding funnel, and the feeding pipe in a fine grinding device for sand and gravel processing proposed in this utility model.

[0022] Figure 6 This is a front sectional view of the rotating shaft and connecting components of a fine grinding device for sand and gravel processing proposed in this utility model.

[0023] Reference numerals: 1. Primary grinding box; 2. Secondary grinding box; 3. First grinding mechanism; 31. Drive box; 32. Rotating rod; 33. Grinding roller; 34. First geared motor; 35. Gear; 36. Guide plate; 4. Second grinding mechanism; 41. Lower grinding disc; 42. Fine grinding chamber; 43. Second geared motor; 44. Rotating shaft; 45. Connecting assembly; 451. Fixing block; 452. Connecting groove; 453. Connecting block; 454. Drive module; 4541. Bidirectional threaded rod; 4542. Threaded block; 4543. Limiting unit; 4544. Connecting rod; 455. Guide module; 46. Guide plate; 47. Upper grinding disc; 5. Feed funnel; 6. Inverted V-shaped connecting pipe; 7. Box door; 8. Discharge funnel; 9. Discharge pipe. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model.

[0025] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, such as welding, riveting, or bonding; it can also be a detachable connection, such as threaded connection, keyed connection, or pin connection; or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] like Figure 1-6 As shown, the present invention proposes a fine grinding device for sand and gravel processing, including a primary grinding box 1 and a secondary grinding box 2. The primary grinding box 1 is equipped with a first grinding mechanism 3 for coarse grinding of sand and gravel, and the secondary grinding box 2 is equipped with a second grinding mechanism 4 for fine grinding of the coarsely ground sand and gravel. The primary grinding box 1 and the first grinding mechanism 3 can perform one coarse grinding of sand and gravel, and the secondary grinding box 2 and the second grinding mechanism 4 can perform fine grinding of the coarsely ground sand and gravel. The primary grinding box 1 is a square box, and the secondary grinding box 2 is a round box.

[0028] The top of the primary grinding box 1 is connected to a feed funnel 5, and the bottom of the primary grinding box 1 is connected to an inverted V-shaped connecting pipe 6. The bottom of the inverted V-shaped connecting pipe 6 is connected to the top of the secondary grinding box 2. The sand and gravel to be ground can be fed into the interior of the primary grinding box 1 through the feed funnel 5, while the sand and gravel coarsened by the first grinding mechanism 3 will enter the interior of the secondary grinding box 2 through the inverted V-shaped connecting pipe 6.

[0029] In Embodiment 1, the first grinding mechanism 3 includes a drive box 31, two rotating rods 32, two grinding rollers 33, a first reduction motor 34, two gears 35, and two guide inclined plates 36. The drive box 31 is located outside the first-stage grinding box 1. The interiors of the two rotating rods 32 are rotatably connected and extend into the interior of the first-stage grinding box 1. The two grinding rollers 33 are respectively located outside the two rotating rods 32 and inside the first-stage grinding box 1. The first reduction motor 34 is located outside the drive box 31, and the output shaft of the first reduction motor 34 is connected to one of the rotating rods 32. The two gears 35 are respectively located outside the two rotating rods 32 and are meshed inside the drive box 31. The two guide inclined plates 36 are both located on the inner sidewall of the first-stage grinding box 1 and are symmetrically distributed. The bottoms of the two guide inclined plates 36 correspond to the tops of the two grinding rollers 33.

[0030] By starting the first reduction motor 34, the output shaft of the first reduction motor 34 will drive one of the rotating rods 32 to rotate. Under the meshing action of the two gears 35, the other rotating rod 32 will be driven to rotate synchronously in opposite directions, so that the two grinding rollers 33 will rotate synchronously to their opposite sides. When the sand and gravel to be ground can be fed into the interior of the first-stage grinding box 1 through the feed funnel 5, under the action of the two guide inclined plates 36, the sand and gravel to be ground enters between the opposite sides of the two grinding rollers 33. The two grinding rollers 33 can perform coarse grinding on the sand and gravel to be ground.

[0031] In embodiment 2, the second grinding mechanism 4 includes a lower grinding disc 41, a fine grinding chamber 42, a second reduction motor 43, a rotating shaft 44, a connecting assembly 45, a guide plate 46, and an upper grinding disc 47. The lower grinding disc 41 is located inside the secondary grinding chamber 2. The fine grinding chamber 42 is located at the top of the lower grinding disc 41 and extends to its bottom. The fine grinding chamber 42 is frustum-shaped. The second reduction motor 43 is located at the top of the secondary grinding chamber 2. The rotating shaft 44 is located on the output shaft of the second reduction motor 43 and extends into the secondary grinding chamber 2. The connecting assembly 45 is located at the bottom of the rotating shaft 44. The guide plate 46 is located below the rotating shaft 44. The rotating shaft 44 is connected to the guide plate 46 through the connecting assembly 45. The upper grinding disc 47 is located below the guide plate 46 and is located inside the fine grinding chamber 42.

[0032] When the second geared motor 43 is started, the output shaft of the second geared motor 43 will drive the rotating shaft 44 to rotate. Under the action of the connecting component 45, the rotating shaft 44 will drive the guide plate 46 and the upper grinding plate 47 to rotate.

[0033] The inner wall of the fine grinding chamber 42 and the outer side of the upper grinding disc 47 form a grinding area with a gradually decreasing gap from top to bottom. When the coarse grinding abrasive enters the secondary grinding box 2 through the inverted V-shaped connecting pipe 6, the coarse grinding abrasive will fall directly onto the top of the guide plate 46. Under the centrifugal force generated by the rotation of the guide plate 46, it will be thrown to all sides, causing the coarse grinding abrasive to fall into the grinding area. Through the rotation of the upper grinding disc 47 and the cooperation between the lower grinding disc 41 and the fine grinding chamber 42, the coarse grinding abrasive can be finely ground.

[0034] During the grinding process, as the gap between the grinding zones gradually decreases from top to bottom, the coarsely ground sand and gravel are subjected to increasing grinding pressure in this area during the fine grinding process and are rapidly ground into finer particles. The finely ground sand and gravel with qualified particle size will fall through the bottom of the fine grinding chamber 42.

[0035] Before grinding the sand and gravel, the height of the guide plate 46 and the upper grinding plate 47 can be adjusted by the connecting component 45, thereby changing the gap between the upper grinding plate 47 and the grinding area at the bottom of the fine grinding chamber 42. When the gap is reduced, the output material is finer, and when the gap is increased, the output material becomes coarser.

[0036] In embodiment 3, the connecting component 45 includes a fixing block 451, a connecting groove 452, a connecting block 453, a driving module 454, and a guiding module 455. The fixing block 451 is located at the bottom end of the rotating shaft 44. The connecting groove 452 is opened at the bottom of the fixing block 451. The connecting block 453 is slidably connected to the inside of the connecting groove 452. The driving module 454 is located inside the connecting groove 452 and is connected to the connecting block 453 for adjusting the height of the connecting block 453. The guiding module 455 is located on the outside of the connecting block 453.

[0037] The drive module 454 can drive the connecting block 453 to move up or down. The connecting block 453 will drive the guide plate 46 and the upper grinding plate 47 to move up or down. The fixing block 451, the connecting groove 452 and the guide module 455 can guide the connecting block 453 to ensure the stability of the movement of the connecting block 453, and further ensure the stability of the movement of the guide plate 46 and the upper grinding plate 47.

[0038] Meanwhile, when the rotating shaft 44 rotates, the rotating shaft 44 will drive the fixed block 451 to rotate. Through the connecting groove 452 and the guide module 455, the fixed block 451 can stably drive the connecting block 453 to rotate, which further enables the guide plate 46 and the upper grinding plate 47 to rotate stably.

[0039] In embodiment four, the drive module 454 includes a bidirectional threaded rod 4541, two threaded blocks 4542, two sets of limiting units 4543, and two connecting rods 4544. The bidirectional threaded rod 4541 is located on the outside of the fixed block 451 and extends into the inside of the connecting groove 452. An adjusting handwheel is provided on the outside of the fixed block 451. The two threaded blocks 4542 are respectively threaded to the two ends of the bidirectional threaded rod 4541 with opposite thread directions. The two sets of limiting units 4543 are respectively located on the top of the two threaded blocks 4542. The two connecting rods 4544 are respectively hinged to the bottom of the two threaded blocks 4542 by pins. The bottom ends of the two connecting rods 4544 are both hinged to the top of the connecting block 453 by pins.

[0040] Rotating the adjusting handwheel at the end of the bidirectional threaded rod 4541 causes the two threaded blocks 4542 to move towards or away from each other under the constraint of the limiting unit 4543. Through the two hinged connecting rods 4544, the connecting block 453 is pushed or pulled. Under the constraint of the guide module 455, the connecting block 453 drives the guide plate 46 and the upper grinding plate 47 to move vertically as a whole, thereby changing the final gap between the upper grinding plate 47 and the bottom of the fine grinding chamber 42.

[0041] The inner side of the secondary grinding box 2 is equipped with a scale. By observing the height of the upper grinding disc 47 and the corresponding scale value, the particle fineness of the sand and gravel material being finely ground can be determined.

[0042] In embodiment 5, the guide module 455 includes two guide blocks and two guide grooves. The two guide grooves are respectively opened on the inner sidewall of the connecting groove 452 and are symmetrically distributed. The two guide blocks are respectively located on the outer side of the connecting block 453, and the two guide blocks are respectively slidably connected to the inside of the two guide grooves.

[0043] The connecting block 453 can be guided by two guide blocks and two guide grooves to ensure the stability of the movement of the connecting block 453, and also to ensure that the fixed block 451 can drive the connecting block 453 to rotate stably.

[0044] In embodiment six, both sets of limiting units 4543 include limiting blocks and limiting grooves. The two limiting grooves are opened on the inner top wall of the connecting groove 452. The two limiting blocks are respectively located on the top of the two threaded blocks 4542. The two limiting blocks are slidably connected to the inside of the two limiting grooves.

[0045] The threaded block 4542 can be limited and guided by the limiting block and the limiting groove, so as to prevent the threaded block 4542 from rotating and to ensure the stability of the movement of the threaded block 4542.

[0046] In Example 7, the bottom of the secondary grinding box 2 is provided with four evenly distributed bases to support the secondary grinding box 2 and ensure the stability of the grinding device. A controller is provided on the outside of the secondary grinding box 2. The first reduction motor 34 and the second reduction motor 43 are electrically connected to the controller, and the controller can control the first reduction motor 34 and the second reduction motor 43.

[0047] Working principle: In operation, this fine grinding device for sand and gravel processing first opens the chamber door 7 according to the required particle size of the sand and gravel, and rotates the adjusting handwheel at the end of the bidirectional threaded rod 4541. This causes the guide plate 46 and the upper grinding plate 47 to move vertically as a whole, thereby changing the final gap between the upper grinding plate 47 and the bottom of the fine grinding chamber 42. Then, the chamber door 7 is closed, and the sand and gravel raw material is fed into the primary grinding chamber 1 from the feed funnel 5. Guided by two symmetrical guide plates 36, it falls evenly between the two grinding rollers 33. The first reduction motor 34 is started, and through one of the rotating rods 32 and a pair of meshing gears 35, it drives the two grinding rollers 33 to rotate in opposite directions, causing the material to fall into the chamber. The material is subjected to strong compression and shearing, and is initially crushed into coarse particles. Under the action of gravity, the crushed material enters the secondary grinding box 2 through the inverted V-shaped connecting pipe 6. The coarsely ground sand and gravel first falls on the rotating guide plate 46, and is thrown to all sides under the action of centrifugal force, and falls into the gradually narrowing grinding area formed by the fine grinding chamber 42 of the upper grinding plate 47 and the lower grinding plate 41. The second reduction motor 43 drives the guide plate 46 and the upper grinding plate 47 to rotate at high speed through the rotating shaft 44. The coarsely ground sand and gravel is subjected to increasing grinding pressure in this area and is rapidly ground. The qualified fine powder finally falls into the feeding funnel 8 through the gap at the bottom and is collected through the feeding pipe 9.

[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fine grinding device for processing sand and gravel, characterized in that, It includes a primary grinding box (1) and a secondary grinding box (2). The primary grinding box (1) is equipped with a first grinding mechanism (3) for coarse grinding of sand and gravel. The secondary grinding box (2) is equipped with a second grinding mechanism (4) for fine grinding of coarsely ground sand and gravel. The top of the primary grinding box (1) is connected to a feed funnel (5), and the bottom of the primary grinding box (1) is connected to an inverted V-shaped connecting pipe (6). The bottom of the inverted V-shaped connecting pipe (6) is connected to the top of the secondary grinding box (2). The front of the secondary grinding box (2) is hinged with a door (7). Inside the secondary grinding box (2) is a feeding funnel (8) located below the second grinding mechanism (4). The inner bottom wall of the feeding funnel (8) is connected to a feeding pipe (9) extending to the bottom of the secondary grinding box (2).

2. The fine grinding device for sand and gravel processing according to claim 1, characterized in that, The first grinding mechanism (3) includes a drive box (31), two rotating rods (32), two grinding rollers (33), a first reduction motor (34), two gears (35), and two guide plates (36). The drive box (31) is located outside the first-stage grinding box (1). The interiors of the two rotating rods (32) are rotatably connected and extend into the interior of the first-stage grinding box (1). The two grinding rollers (33) are respectively located outside the two rotating rods (32) and are located in the first-stage grinding box (1). Inside the drive box (31), the first geared motor (34) is located on the outside of the drive box (31). The output shaft of the first geared motor (34) is connected to one of the rotating rods (32). The two gears (35) are located on the outside of the two rotating rods (32) and are meshed inside the drive box (31). The two guide plates (36) are located on the inner side wall of the first-stage grinding box (1) and are symmetrically distributed. The bottom of the two guide plates (36) corresponds to the top of the two grinding rollers (33).

3. The fine grinding device for sand and gravel processing according to claim 1, characterized in that, The second grinding mechanism (4) includes a lower grinding disc (41), a fine grinding chamber (42), a second geared motor (43), a rotating shaft (44), a connecting assembly (45), a guide disc (46), and an upper grinding disc (47). The lower grinding disc (41) is located inside the secondary grinding box (2). The fine grinding chamber (42) is located at the top of the lower grinding disc (41) and extends to its bottom. The fine grinding chamber (42) is frustum-shaped. The second geared motor (43) is located in the secondary grinding box. (2) At the top, the rotating shaft (44) is located on the output shaft of the second geared motor (43) and extends into the interior of the secondary grinding box (2). The connecting component (45) is located at the bottom end of the rotating shaft (44). The guide plate (46) is located below the rotating shaft (44). The rotating shaft (44) is connected to the guide plate (46) through the connecting component (45). The upper grinding plate (47) is located below the guide plate (46) and is located inside the fine grinding chamber (42). The inner wall of the fine grinding chamber (42) and the outer side of the upper grinding disc (47) form a grinding area with a gradually decreasing gap from top to bottom.

4. The fine grinding device for sand and gravel processing according to claim 3, characterized in that, The connecting component (45) includes a fixing block (451), a connecting groove (452), a connecting block (453), a driving module (454), and a guiding module (455). The fixing block (451) is located at the bottom of the rotating shaft (44). The connecting groove (452) is opened at the bottom of the fixing block (451). The connecting block (453) is slidably connected to the inside of the connecting groove (452). The driving module (454) is located inside the connecting groove (452) and is connected to the connecting block (453) for adjusting the height of the connecting block (453). The guiding module (455) is located on the outside of the connecting block (453).

5. The fine grinding device for sand and gravel processing according to claim 4, characterized in that, The drive module (454) includes a bidirectional threaded rod (4541), two threaded blocks (4542), two sets of limiting units (4543), and two connecting rods (4544). The bidirectional threaded rod (4541) is located on the outside of the fixed block (451) and extends into the inside of the connecting groove (452). An adjusting handwheel is provided on the outside of the fixed block (451). The two threaded blocks (4542) are respectively threaded to the two ends of the bidirectional threaded rod (4541) with opposite thread directions. The two sets of limiting units (4543) are respectively located on the top of the two threaded blocks (4542). The two connecting rods (4544) are respectively hinged to the bottom of the two threaded blocks (4542) by pins. The bottom ends of the two connecting rods (4544) are both hinged to the top of the connecting block (453) by pins.

6. The fine grinding device for sand and gravel processing according to claim 4, characterized in that, The guide module (455) includes two guide blocks and two guide grooves. The two guide grooves are respectively opened on the inner sidewall of the connecting groove (452) and are symmetrically distributed. The two guide blocks are respectively located on the outer side of the connecting block (453) and are slidably connected to the inside of the two guide grooves.

7. A fine grinding device for sand and gravel processing according to claim 5, characterized in that, Both sets of limiting units (4543) include limiting blocks and limiting grooves. The two limiting grooves are opened on the inner top wall of the connecting groove (452). The two limiting blocks are respectively located on the top of the two threaded blocks (4542). The two limiting blocks are slidably connected to the inside of the two limiting grooves.

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