Spiral internal dredging anti-blocking device of sand mixer

Abstract

The utility model provides a kind of spiral internal dredging anti-blocking device of sand mixer, belong to sand mixer technical field, the spiral internal dredging anti-blocking device of this sand mixer includes dredging shaft and helical blade, dredging shaft is along the axial center line of sand mixer internal cylinder body arrangement, the both ends of dredging shaft are fixedly connected on the two end faces of sand mixer internal cylinder body respectively by bearing seat, helical blade is spirally wound in the outer circumferential surface of dredging shaft, wherein, the gap between the outer edge of helical blade and the inner wall of sand mixer internal cylinder body is formed, the helical blade axial helical angle of dredging shaft is 30~45 °, the cross section of helical blade is trapezoidal structure, when dredging shaft rotates, the outer edge of helical blade and the inner wall of sand mixer internal cylinder body form sustained relative motion, solve the problem that sand mixer is caused by lack of effective internal dredging device, leading to material in cylinder wall and central region long-term accumulation adhesion, form jamming layer and efficiency decline even shutdown.

Description

Technical Field

[0001] This utility model belongs to the technical field of sand mixers, specifically, it relates to a spiral internal unblocking and anti-clogging device for a sand mixer. Background Technology

[0002] As an important sand processing device in the foundry industry, the sand mixer is mainly used to uniformly mix molding sand with various additives to meet the requirements of the casting process. During actual operation, due to the viscosity of the molding sand and its interaction with moisture and binders during mixing, these materials tend to accumulate and adhere within the mixer's internal cylinder. This is especially true on the inner wall surface and near the central axis, where uneven centrifugal force and gravity settling gradually form a buildup layer. As this layer thickens, the effective working space of the sand mixer gradually decreases, significantly reducing mixing efficiency. In severe cases, it can even lead to complete blockage and prevent proper operation. Currently, the industry mainly solves this problem by periodically stopping the machine for cleaning. Operators need to open the maintenance door of the sand mixer to enter the internal cylinder for manual cleaning. This method is not only labor-intensive, but also requires a long downtime for cleaning, which seriously affects the continuity of production. Some sand mixers use methods such as increasing the size of the mixing blades or increasing the speed to enhance the flowability of materials. However, these methods can only delay the occurrence of blockage to a certain extent and cannot fundamentally solve the problem. Moreover, high-speed operation will increase the energy consumption and wear of the equipment. Therefore, there is an urgent need for a device that can continuously unclog the inside of the sand mixer during operation and effectively prevent material accumulation. Utility Model Content

[0003] In view of this, the present invention provides a spiral internal unblocking and anti-clogging device for a sand mixer, which solves the problem that the lack of an effective internal unblocking device in the sand mixer leads to long-term accumulation and adhesion of materials on the inner wall and central area of ​​the cylinder, forming a blockage layer, resulting in reduced efficiency or even shutdown.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a spiral internal unblocking and anti-clogging device for a sand mixer, which is installed in the internal cylinder of the sand mixer. It includes an unblocking shaft and spiral blades. The unblocking shaft is arranged along the axial centerline of the internal cylinder of the sand mixer. Both ends of the unblocking shaft are fixedly connected to the two end faces of the internal cylinder of the sand mixer via bearing seats. The spiral blades are spirally wound around the outer circumferential surface of the unblocking shaft. A gap is formed between the outer edge of the spiral blades and the inner wall of the internal cylinder of the sand mixer. This gap distance is the shortest radial distance from the outer edge of the spiral blades to the inner wall. The spiral helix angle of the spiral blades along the axial direction of the unblocking shaft is 30-45°. The cross-section of the spiral blades is a trapezoidal structure. The long side of the trapezoidal structure is fixedly connected to the outer circumferential surface of the unblocking shaft, and the short side of the trapezoidal structure serves as the outer edge of the spiral blades. When the unblocking shaft rotates, the outer edge of the spiral blades and the inner wall of the internal cylinder of the sand mixer form a continuous relative motion.

[0006] The technical effects of the spiral internal unblocking and anti-clogging device for a sand mixer provided by this utility model are as follows: By setting the unblocking shaft along the axial center line of the inner cylinder of the sand mixer and winding spiral blades around its outer circumference, a spiral unblocking structure is formed. When the unblocking shaft rotates, the spiral blades can continuously push and stir the material inside the sand mixer. The gap design between the outer edge of the spiral blades and the inner wall prevents the material from being excessively squeezed between the blades and the inner wall, thus preventing blockage. At the same time, the spiral helix angle and trapezoidal cross-section design allow the material to move orderly along the axial direction, effectively preventing the blockage caused by the accumulation of material inside the cylinder, and ensuring the continuous and stable operation of the sand mixer.

[0007] Based on the above technical solution, the spiral internal unblocking and anti-clogging device for a sand mixer of this utility model can be further improved as follows:

[0008] The gap between the outer edge of the spiral blade and the inner wall of the inner cylinder of the sand mixer is less than one-fifth of the radius of the dredging shaft.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by limiting the gap distance between the outer edge of the spiral blade and the inner wall to less than one-fifth of the radius of the unclogging shaft, this dimensional relationship ensures that the spiral blade can fully approach the inner wall of the cylinder to form an effective pushing effect on the material, while preventing the material from being excessively squeezed between the blade and the inner wall due to the gap being too small, thus forming a hardened layer. The setting of this gap distance allows the material to flow smoothly under the push of the blade without accumulating at the edge, further improving the anti-clogging effect and reducing the rotational resistance of the unclogging shaft.

[0010] Furthermore, the length of the long side of the trapezoidal cross-section of the spiral blade is greater than twice the length of the short side, and the angle between the two hypotenuses of the trapezoidal cross-section and the long side is 60-75°.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: The trapezoidal cross-section design of the spiral blade, in which the length of the long side is greater than twice the length of the short side and the angle between the inclined side and the long side is 60 to 75 degrees, gives the spiral blade a shape that gradually narrows from the inside to the outside. This shape can generate a thrust on the material from the surface of the unblocking shaft to the inner wall of the cylinder when rotating, causing the material to diffuse outward and not accumulate near the unblocking shaft. At the same time, the design of the inclined side angle of the trapezoidal structure allows the material to slide along the inclined surface when it contacts the blade surface, reducing the adhesion of the material to the blade surface and effectively preventing the blockage problem caused by the agglomeration of material on the blade surface.

[0012] Furthermore, the outer circumferential surface of the unblocking shaft has multiple grooves extending axially, and the long side of the trapezoidal cross-section of the spiral blade is embedded in the groove and fixedly connected by welding.

[0013] The beneficial effects of the above-mentioned improvement scheme are as follows: A groove extending axially is opened on the outer circumferential surface of the unclogging shaft, and the long side of the spiral blade is embedded in the groove and fixed by welding. This connection method forms a strong mechanical and metallurgical connection between the spiral blade and the unclogging shaft. The axial extension design of the groove allows the spiral blade to distribute the stress evenly across the entire embedded length when it is subjected to the thrust of the material, avoiding the blade from breaking or loosening in a local position. At the same time, the presence of the groove also makes the installation position of the spiral blade more precise, ensuring the geometric accuracy of the spiral structure and the stability of the unclogging effect.

[0014] Furthermore, the outer edge of the helical blade has a wavy undulation shape, and the peaks and troughs of the wavy undulation are distributed alternately along the helical extension direction of the helical blade.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: The wavy design of the outer edge of the spiral blades enables the blades to periodically disturb the material near the inner wall of the cylinder during rotation. The crests can penetrate deeper into the area closer to the inner wall to scrape the material adhering to the inner wall, while the troughs provide more space for the material to flow. This wavy structure allows the spiral blades to clean the inner wall while pushing the material, effectively preventing the material from accumulating on the inner wall surface for a long time and forming a hardened layer, maintaining the cleanliness of the inner wall of the cylinder and improving the overall unblocking capacity of the sand mixer.

[0016] Furthermore, in the wavy undulation of the outer edge of the spiral blade, the distance between adjacent peaks is equal to 1 / 4 to 1 / 3 of the circumference of the outer circumference of the dredging shaft.

[0017] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by limiting the distance between adjacent peaks in the wave-like undulation to one-quarter to one-third of the circumference of the outer circumference of the dredging shaft, this spacing design allows the spiral blades to generate multiple disturbances in the same circumferential position on the inner wall of the cylinder during each rotation. The periodicity of the peaks ensures that every area of ​​the inner wall surface can be thoroughly cleaned. At the same time, this spacing range also avoids the increased material flow resistance caused by excessively dense peaks or the insufficient cleaning effect caused by excessively sparse peaks, thus achieving the best balance between cleaning effect and flow resistance.

[0018] Furthermore, the spiral blades are arranged in a double-headed spiral on the unblocking shaft, with the starting ends of the two spiral blades located on opposite sides of the outer circumferential surface of the unblocking shaft, and the spiral directions of the two spiral blades on the unblocking shaft are the same.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: The design of the spiral blades being distributed in a double-headed spiral on the unblocking shaft with the starting ends of the two spiral blades located on opposite sides allows the unblocking shaft to generate two material pushing forces in the same axial position when rotating. The synergistic effect of the two spiral blades increases the material pushing efficiency by nearly 100%. At the same time, the double-headed spiral structure also allows the radial forces on the unblocking shaft to cancel each other out when rotating, reducing the unbalanced load on the bearing housing, reducing equipment vibration and wear, and improving the operational stability and service life of the device.

[0020] Furthermore, the unblocking shaft is made of stainless steel, and the spiral blades are made of manganese steel.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: using stainless steel to manufacture the unblocking shaft can effectively resist the corrosion of the shaft body by materials and moisture during the sand mixing process, maintaining the smoothness and dimensional accuracy of the shaft body surface. Using manganese steel to manufacture the spiral blades can provide excellent wear resistance and impact toughness, so that the blades can still maintain the complete geometric shape and unblocking function under long-term material impact and friction. The reasonable combination of the two materials not only ensures the durability of the device but also controls the manufacturing cost, achieving a good combination of performance and economy.

[0022] Furthermore, the thickness of the short side of the trapezoidal cross-section of the helical blade is greater than the thickness of the long side in the radial direction along the unblocking axis.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the design that the thickness of the short side of the trapezoidal cross section of the spiral blade is greater than that of the long side in the radial direction gives the outer edge of the blade greater structural strength. Since the outer edge is the part of the spiral blade that comes into contact with the material most frequently and bears the greatest impact force, increasing the thickness of this part can effectively prevent the outer edge from deforming or wearing during long-term use. At the same time, this thickness distribution also makes the center of gravity of the spiral blade biased to the outside, which can generate greater centrifugal thrust when rotating, and enhance the pushing effect of the material to the outside of the cylinder.

[0024] Furthermore, the bearing housing is connected to the end face of the inner cylinder of the sand mixer via a flange. Multiple bolt holes are evenly distributed on the flange. The unblocking shaft passes through the central hole of the bearing housing and forms a rotatable connection with the bearing housing through the bearing.

[0025] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the design of connecting the bearing housing to the end face of the inner cylinder of the sand mixer by flange and evenly distributing multiple bolt holes on the flange allows the bearing housing to be firmly fixed on the end face of the cylinder and bear the axial and radial forces generated when the unclogging shaft rotates. The unclogging shaft passes through the central hole of the bearing housing and forms a rotating connection structure through the bearing, ensuring that the unclogging shaft can operate stably with the axial center line of the cylinder as the rotation center. The multi-bolt distribution design of the flange makes the connection load evenly distributed, avoiding connection failure caused by local stress concentration, and ensuring the reliable operation of the entire device.

[0026] Compared with existing technologies, the beneficial effects of the spiral internal unblocking and anti-clogging device for a sand mixer provided by this utility model are as follows: This utility model constructs a device structure that can continuously push and unblock internal materials during the operation of the sand mixer by setting an unblocking shaft arranged along the axial center line in the inner cylinder of the sand mixer and winding spiral blades with a specific spiral helix angle and trapezoidal cross-section on its outer circumferential surface. The precise gap design between the outer edge of the spiral blade and the inner wall of the cylinder ensures that the material is not excessively squeezed and hardened during the pushing process, while the trapezoidal cross-section and wavy outer edge shape of the spiral blade allow the material to move along the inner wall. The device moves axially in an orderly manner and continuously cleans the inner wall. The double-headed spiral distribution further improves the unblocking efficiency and balances the force during rotation. The combination of stainless steel unblocking shaft and manganese steel spiral blades ensures long-term reliable operation of the device in corrosive and abrasive environments. The connection structure of flange and bearing seat realizes stable rotation of the unblocking shaft. The entire device, from structural design to material selection, revolves around the core goal of preventing material accumulation and adhesion, effectively solving the technical problem of internal blockage in sand mixers. Compared with existing technologies, it significantly improves the operational stability and production efficiency of sand mixers, reduces downtime and maintenance time caused by blockage, and lowers production costs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 An example diagram of a spiral internal unblocking and anti-clogging device for a sand mixer;

[0029] Figure 2 A diagram showing the unblocking shaft of a spiral internal unblocking and anti-clogging device for a sand mixer;

[0030] Figure 3 for Figure 2 Enlarged view of section A in the middle;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 10. Internal cylinder of the sand mixer; 20. Unblocking shaft; 21. Groove; 30. Spiral blade. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figures 1-3 The diagram shown is an example of a spiral internal unblocking and anti-clogging device for a sand mixer provided by this utility model. It is installed inside the inner cylinder of the sand mixer and includes an unblocking shaft 20 and spiral blades 30. The unblocking shaft 20 is arranged along the axial centerline of the inner cylinder 10 of the sand mixer. Both ends of the unblocking shaft 20 are fixedly connected to the two end faces of the inner cylinder 10 of the sand mixer via bearing seats. The spiral blades 30 are spirally wound around the outer circumferential surface of the unblocking shaft 20, wherein the outer edge of the spiral blades 30 is flush with the inner surface of the sand mixer. A gap is formed between the inner walls of the cylinder 10. This gap is the shortest radial distance from the outer edge of the spiral blade 30 to the inner wall. The spiral helix angle of the spiral blade 30 along the axial direction of the unblocking shaft 20 is 30 to 45°. The cross-section of the spiral blade 30 is a trapezoidal structure. The long side of the trapezoidal structure is fixedly connected to the outer circumferential surface of the unblocking shaft 20. The short side of the trapezoidal structure serves as the outer edge of the spiral blade 30. When the unblocking shaft 20 rotates, the outer edge of the spiral blade 30 forms a continuous relative motion with the inner wall of the cylinder 10 inside the sand mixer.

[0035] The specific operation or usage method is as follows: First, fix both ends of the unclogging shaft to the two end faces of the inner cylinder of the sand mixer using bearing seats, ensuring that the axis of the unclogging shaft coincides with the axial center line of the cylinder. Securely fix the bearing seats to the end faces of the cylinder using bolts on the flange. Then, connect the unclogging shaft to the power system of the sand mixer via a coupling. The power system is usually a motor-driven reducer, which can provide continuous and stable rotational power to the unclogging shaft. When the sand mixer starts working, as the material is fed into the cylinder, the rotation of the unclogging shaft starts synchronously. The speed of the unclogging shaft should be matched and set according to the working speed of the sand mixer and the characteristics of the material, usually 0.5 times the speed of the main mixing shaft of the sand mixer. The spiral blades, with a speed of 0.8 to 1.2 times, continuously push and stir the material inside the cylinder during the rotation of the dredging shaft, keeping the material in a flowing state and moving orderly along the axial direction. Throughout the entire working cycle of the sand mixer, the dredging shaft should continue to operate continuously to ensure the continuity of the dredging effect. When the sand mixer completes a working cycle and needs to unload, the dredging shaft should continue to operate until the material inside the cylinder is basically emptied, and then stop rotating. In daily maintenance, the connection status between the dredging shaft and the bearing seat and the wear condition of the spiral blades should be checked regularly. If the outer edge of the spiral blade is found to be severely worn or the gap between it and the inner wall exceeds the design range, the blades should be replaced in time to maintain the dredging effect of the device.

[0036] In the above technical solution, the gap between the outer edge of the spiral blade 30 and the inner wall of the inner cylinder 10 of the sand mixer is less than one-fifth of the radius of the unblocking shaft 20.

[0037] Furthermore, in the above technical solution, the length of the long side of the trapezoidal cross-section of the spiral blade 30 is more than twice the length of the short side, and the angle between the two hypotenuses of the trapezoidal cross-section and the long side is 60-75°.

[0038] Furthermore, in the above technical solution, multiple axially extending grooves 21 are formed on the outer circumferential surface of the unblocking shaft 20, and the long side of the trapezoidal cross-section of the spiral blade 30 is embedded in the grooves 21 and fixedly connected by welding.

[0039] Furthermore, in the above technical solution, the outer edge of the helical blade 30 has a wavy undulating shape, and the peaks and troughs of the wavy undulation are distributed alternately along the helical extension direction of the helical blade 30.

[0040] Furthermore, in the above technical solution, in the wavy undulation of the outer edge of the spiral blade 30, the distance between adjacent wave crests is equal to 1 / 4 to 1 / 3 of the circumference of the outer circumference surface of the dredging shaft 20.

[0041] Furthermore, in the above technical solution, the spiral blades 30 are arranged in a double-headed spiral on the unblocking shaft 20, with the starting ends of the two spiral blades 30 located on opposite sides of the outer circumferential surface of the unblocking shaft 20, and the spiral directions of the two spiral blades 30 on the unblocking shaft 20 are the same.

[0042] Furthermore, in the above technical solution, the unblocking shaft 20 is made of stainless steel, and the spiral blade 30 is made of manganese steel.

[0043] Furthermore, in the above technical solution, the thickness of the short side of the trapezoidal cross-section of the spiral blade 30 is greater than the thickness of the long side along the radial direction of the unblocking shaft 20.

[0044] Furthermore, in the above technical solution, the bearing housing and the end face of the inner cylinder 10 of the sand mixer are connected by a flange. Multiple bolt holes are evenly distributed on the flange. The unblocking shaft 20 passes through the central hole of the bearing housing and forms a rotating connection with the bearing housing through the bearing.

[0045] In specific embodiment 1, the internal cylinder of the sand mixer is a cylindrical structure with an inner diameter of 1200mm and an axial length of 2000mm. The unblocking shaft is made of 304 stainless steel round bar with a diameter of 80mm. Each end of the unblocking shaft has a journal portion with a diameter of 60mm and a length of 150mm for mounting bearings. The bearing housing is made of cast iron and contains two deep groove ball bearings to support the rotation of the unblocking shaft. The bearing housing is fixed to the end face of the cylinder by a 15mm thick stainless steel flange. The flange is circular with a diameter of 300mm, and has evenly distributed circumferential lines on it. Eight 18mm diameter bolt holes are used to connect the flange to the cylinder end face with M16 stainless steel bolts. The spiral blade is made of 8mm thick manganese steel sheet through cutting and bending processes. The cross-section of the spiral blade is trapezoidal, with the long side of the trapezoid being 120mm long and contacting the outer circumference of the drain shaft. The short side of the trapezoid, i.e., the outer edge of the spiral blade, is 50mm long. The angle between the two hypotenuses and the long side of the trapezoid is 68 degrees. A rectangular groove with a width of 10mm and a depth of 6mm is axially formed on the outer circumference of the drain shaft. The long side of the spiral blade is embedded in the groove and fully welded and fixed by argon arc welding. The weld seams are ground to ensure a smooth surface. The spiral blades are arranged in a double-headed spiral along the unclogging shaft, with the starting ends of the two spiral blades located at 0 degrees and 180 degrees circumferentially on the unclogging shaft, respectively. The spiral helix angle is 38 degrees. The spiral blades extend from one end of the unclogging shaft to the other, forming a continuous spiral structure. The radial clearance between the outer edge of the spiral blade and the inner wall of the cylinder is 8 mm. The outer edge of the spiral blade is machined into a wavy undulating shape, with the radial height of the crest being 3 mm higher than that of the trough. The circumferential distance between adjacent crests is 70 mm, approximately 0.28 times the outer circumference of the unclogging shaft. One end of the unclogging shaft is connected to the reducer via a flexible pin coupling. The output shaft is connected, and the reducer is driven by a 7.5kW three-phase asynchronous motor. The output speed of the reducer is 60 revolutions per minute. At this speed, the spiral blades can push the material axially by about 800mm after one rotation of the unblocking shaft, ensuring that the material maintains a continuous flow state in the cylinder. The spiral internal unblocking and anti-clogging device in this embodiment has been running continuously on the sand mixer of a foundry for 6 months. During this period, there was no obvious material accumulation inside the sand mixer, and the inner wall of the cylinder remained clean. Compared with before the installation of the device, the frequency of shutdown for cleaning was reduced from twice a week to once a month, which effectively improved production efficiency and reduced maintenance costs.

[0046] In specific embodiment 2, based on embodiment 1, the material of the spiral blade is changed from manganese steel to ordinary steel plate with a hard alloy layer welded to its surface. The hard alloy layer is made of tungsten-cobalt alloy material with a thickness of 2mm. This hard alloy layer has extremely high wear resistance and can maintain the geometric shape of the outer edge of the spiral blade when processing materials containing high hardness such as quartz sand. At the same time, the amplitude of the wave-like undulation of the outer edge of the spiral blade is increased, the radial height of the wave crest is 5mm higher than the wave trough, and the circumferential distance between adjacent wave crests is adjusted to 55mm. This improvement makes the cleaning effect of the spiral blade on the inner wall of the cylinder stronger, especially suitable for materials with high viscosity. In practical applications, this improvement scheme further improves the cleanliness of the inner wall of the cylinder, and reduces the amount of material residue on the inner wall by about 40%.

[0047] Specifically, the principle of this invention is as follows: A clearing shaft is installed at the axial centerline of the inner cylinder of the sand mixer, and spiral blades are mounted on its outer circumference. The rotation of the clearing shaft drives the spiral blades to continuously push and stir the material inside the cylinder. The spiral distribution of the spiral blades along the clearing shaft ensures that the material moves not only circumferentially but also axially under the push of the blades. This spiral pushing action effectively breaks the static state of the material, preventing it from accumulating in one position for a long time. The precise gap design between the outer edge of the spiral blades and the inner wall of the cylinder is key to preventing blockage. The gap distance must be small enough to ensure that the blades can push the material close to the inner wall, and large enough to prevent the material from accumulating on the blades. The excessive compression between the blades and the inner wall forms a hardened layer. The trapezoidal cross-section of the spiral blades allows the material to slide along the inclined plane when it comes into contact with the blades without adhering to the blade surface, reducing the accumulation of material on the blades. The wavy outer edge shape allows the spiral blades to periodically scrape the inner wall of the cylinder during rotation, which can promptly remove the adhering material on the inner wall and keep the inner wall clean. The double-headed spiral distribution design allows the two spiral blades to form a synergistic pushing effect in the same axial position, improving the unblocking efficiency and balancing the force during rotation to reduce equipment vibration. The entire device achieves continuous unblocking and anti-clogging effects inside the sand mixer through the synergistic effect of multiple mechanisms such as spiral pushing, gap control, surface sliding, and periodic cleaning.

Claims

1. A spiral-type internal unblocking and anti-clogging device for a sand mixer, for installation in the internal cylinder of the sand mixer, comprising an unblocking shaft and spiral blades, wherein the unblocking shaft is arranged along the axial centerline of the internal cylinder of the sand mixer, and both ends of the unblocking shaft are respectively fixedly connected to the two end faces of the internal cylinder of the sand mixer via bearing seats, and the spiral blades are spirally wound around the outer circumferential surface of the unblocking shaft, characterized in that... The outer edge of the spiral blade forms a gap with the inner wall of the inner cylinder of the sand mixer. This gap is the shortest radial distance from the outer edge of the spiral blade to the inner wall. The spiral helix angle of the spiral blade along the dredging shaft is 30-45°. The cross-section of the spiral blade is a trapezoidal structure. The long side of the trapezoidal structure is fixedly connected to the outer circumferential surface of the dredging shaft, and the short side of the trapezoidal structure serves as the outer edge of the spiral blade. When the dredging shaft rotates, the outer edge of the spiral blade and the inner wall of the inner cylinder of the sand mixer form a continuous relative motion.

2. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 1, characterized in that, The gap between the outer edge of the spiral blade and the inner wall of the inner cylinder of the sand mixer is less than one-fifth of the radius of the dredging shaft.

3. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 2, characterized in that, The length of the long side of the trapezoidal cross-section of the spiral blade is more than twice the length of the short side, and the angle between the two hypotenuses of the trapezoidal cross-section and the long side is 60-75°.

4. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 3, characterized in that, The outer circumferential surface of the unblocking shaft has multiple grooves extending axially, and the long side of the trapezoidal cross-section of the spiral blade is embedded in the groove and fixedly connected by welding.

5. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 4, characterized in that, The outer edge of the helical blade has a wavy undulation shape, and the peaks and troughs of the wavy undulation are distributed alternately along the helical extension direction of the helical blade.

6. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 5, characterized in that, In the wavy undulation of the outer edge of the spiral blade, the distance between adjacent peaks is equal to 1 / 4 to 1 / 3 of the circumference of the outer circumference of the dredging shaft.

7. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 6, characterized in that, The spiral blades are arranged in a double-headed spiral on the unblocking shaft. The starting ends of the two spiral blades are located on opposite sides of the outer circumferential surface of the unblocking shaft, and the spiral directions of the two spiral blades on the unblocking shaft are the same.

8. The spiral internal unblocking and anti-clogging device for a sand mixer according to claim 7, characterized in that, The unblocking shaft is made of stainless steel, and the spiral blades are made of manganese steel.

9. A spiral-type internal unblocking and anti-clogging device for a sand mixer according to claim 8, characterized in that, The thickness of the short side of the trapezoidal cross-section of the spiral blade is greater than the thickness of the long side in the radial direction along the unblocking axis.

10. A spiral-type internal unblocking and anti-clogging device for a sand mixer according to claim 9, characterized in that, The bearing housing is connected to the end face of the inner cylinder of the sand mixer via a flange. Multiple bolt holes are evenly distributed on the flange. The unblocking shaft passes through the central hole of the bearing housing and forms a rotatable connection with the bearing housing through the bearing.

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