A casting sand mixing device

Abstract

This invention provides a sand mixing device for foundry sand molds. The invention relates to the field of sand mixing technology and includes a support base. A mixing chamber is located at the upper end of the support base. A sand and gravel discharge channel and a resin discharge channel are located at the upper end of the mixing chamber. The mixing chamber includes a mixing shell, a mixing shaft disposed within the mixing shell, and mixing blades fixed to the surface of the mixing shaft. A discharge opening is located at the lower end of the mixing shell. A blocking blade is also fixed to the surface of the mixing shaft, positioned above the discharge opening. The inclination direction of the blocking blade is opposite to that of the mixing blades. An airtight device is provided between the mixing shaft and the mixing shell. The airtight device is located on the side of the blocking blades away from the mixing blades, forming an airtight channel between the airtight device and the mixing shaft. This invention, through a double-sealing structure design, can greatly improve the sealing effect on the bearing seat side, ensuring the normal and continuous rotation of the mixing shaft.

Description

Technical Field

[0001] This invention relates to the field of sand mixing technology, and more particularly to a sand mixing device for casting sand molds. Background Technology

[0002] Casting sand molds are the basic molds in casting processing. Casting sand molds consist of sand and resin materials and can form molds of a predetermined shape to meet the requirements of casting.

[0003] To meet the requirements of different casting materials, sand and gravel and different types of resin materials need to be mixed efficiently. In order to improve the mixing effect of different resins, the mixing chamber is lengthened to form a longer mixing path. During this process, a large amount of dust is generated. A large amount of dust enters the bearing housing of the rotating shaft, affecting the normal rotation of the bearing. It is difficult to maintain an effective seal with just the sealing ring, and the relevant structure needs to be replaced frequently, which reduces the mixing production efficiency and mixing effect. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a casting sand mold mixing device. This invention, through a double-sealing structure design, can greatly improve the sealing effect on one side of the bearing seat, ensuring that the mixing shaft can rotate normally and continuously.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A casting sand mixing device includes a support base, a mixing chamber at the upper end of the support base, a sand and gravel discharge channel and a resin discharge channel at the upper end of the mixing chamber, a mixing shell, a mixing shaft disposed within the mixing shell, and mixing blades fixed to the surface of the mixing shaft, a discharge opening at the lower end of the mixing shell, and a blocking blade fixed above the discharge opening on the surface of the mixing shaft, the blocking blades being inclined in the opposite direction to the mixing blades, an airtight device being disposed between the mixing shaft and the mixing shell, the airtight device being located on the side of the blocking blades away from the mixing blades, and an airtight channel being formed between the airtight device and the mixing shaft, wherein a protective gas is continuously ejected under positive pressure during the rotation of the mixing shaft.

[0007] Preferably, the airtight device includes a sealing ring fixed to the inner wall of the mixing housing, and an airtight channel is formed between the sealing ring and the mixing shaft. A pressurizing pipe communicating with the airtight channel is provided inside the mixing shaft, and a pumping device is connected to the outside of the pressurizing pipe.

[0008] Preferably, the air pumping device includes an air pumping pipe, which is connected to the pressurization pipe via a rotary seal.

[0009] Preferably, the pressurization pipeline includes a first pressurization pipeline arranged along the axis of the mixing shaft, and one side wall of the pressurization pipeline is connected to an airtight channel through a plurality of second pressurization pipelines.

[0010] Preferably, an elastic adjustment component is provided inside the first pressurization pipe, the elastic adjustment component is slidably connected to the inner wall of the first pressurization pipe, and the second pressurization pipe is located on the moving path of the elastic adjustment component.

[0011] Preferably, the barrier blade is detachably connected to the mixing shaft, and the barrier blade has different installation angles. A limiting component is provided between the barrier blade and the elastic adjustment component to adjust the extreme contraction position of the elastic adjustment component.

[0012] Preferably, the limiting component is a mechanical limiting rod, and the blocking blade has a limiting opening on its sidewall.

[0013] Preferably, the limiting component is a magnetic limiting rod, and a magnetic block is embedded inside the blocking blade.

[0014] Preferably, the barrier blade includes a columnar blade holder and a strip-shaped blade, and the columnar blade holder has a first limiting hole and a second limiting hole on its side wall.

[0015] Preferably, the side wall of the discharge opening is provided with a negative pressure channel with a built-in filter, and the negative pressure channel is linked and controlled with the airtight device.

[0016] The beneficial effects of this invention are as follows:

[0017] Compared with existing technologies, the above structural design utilizes a combination of reverse blocking blades and an airtight device. The blocking blades apply a reverse thrust to the mixed sand and gravel material, preventing the material from accumulating inside the bearing housing and forming a mechanical barrier. The airtight device forms a gas protection barrier inside the bearing housing, preventing small dust particles from entering the bearing housing through the rotation gap. This double-sealing structure design greatly improves the sealing effect on one side of the bearing housing, ensuring that the mixing shaft can rotate normally and continuously. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the mixing hopper of the present invention.

[0020] Figure 3 For the present invention Figure 2 A magnified structural diagram at point A.

[0021] Figure 4 For the present invention Figure 3A magnified structural diagram at point B.

[0022] Figure 5 This is a schematic diagram of the barrier blade of the present invention.

[0023] In the diagram: 100, bearing base; 200, drive motor; 300, mixing hopper; 310, mixing housing; 320, discharge opening; 321, negative pressure channel; 330, mixing shaft; 331, mixing blade; 340, barrier blade; 341, strip blade; 342, columnar blade holder; 343, first limiting hole; 344, second limiting hole; 345, limiting opening; 400, resin discharge channel one; 500, resin discharge channel two; 600, sand and gravel discharge channel; 700, airtight device; 710, pump air pipe; 720, rotary seal; 730, sealing ring; 731, airtight channel; 740, sealing assembly; 741, pressurization pipe one; 742, elastic adjustment assembly; 743, pressurization pipe two. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] See attached document Figure 1 - Appendix Figure 5 A casting sand mixing device includes a support base 100, a mixing chamber 300 at the upper end of the support base 100, a sand and gravel feeding channel 600 and a resin feeding channel at the upper end of the mixing chamber 300, the resin feeding channel including resin feeding channel one 400 and resin feeding channel two 500, different types of resin can be added into the mixing chamber 300 for mixing according to the needs of sand mold production.

[0026] The mixing chamber 300 includes a mixing shell 310, a mixing shaft 330 disposed within the mixing shell 310, and mixing blades 331 fixed to the surface of the mixing shaft 330. The mixing shell 310 has a discharge opening 320 at its lower end. The mixing shaft 330 within the mixing shell 310 is controlled to rotate in a specific direction by a drive motor 200. During the process of the mixing shaft 330 driving the mixing blades 331 to rotate in a specific direction, efficient mixing of the discharged sand and resin is achieved. Furthermore, the mixing blades 331 are arranged at an angle, and during the rotation of the mixing blades 331, they can also directionally push the resin and sand, controlling the mixed resin and sand to be discharged from one side of the discharge opening 320.

[0027] A blocking blade 340 is also fixed on the surface of the mixing shaft 330, located above the discharge opening 320. The tilt direction of the blocking blade 340 is opposite to that of the mixing blade 331. The mixing shaft 330 drives the blocking blade 340 to rotate synchronously. Since the tilt direction of the blocking blade 340 is opposite to that of the mixing blade 331, the blocking blade 340 can apply a force in the opposite direction to the mixed sand and resin.

[0028] Furthermore, an airtight device 700 is provided between the mixing shaft 330 and the mixing housing 310. The airtight device 700 is located on the side of the barrier blade 340 away from the mixing blade 331. An airtight channel 731 is formed between the airtight device 700 and the mixing shaft 330. During the rotation of the mixing shaft 330, the airtight channel 731 is controlled to continuously spray protective gas under positive pressure. By controlling the airtight channel 731 to be continuously under positive pressure, dust can be prevented from continuously entering the bearing housing and causing damage to the bearing housing.

[0029] This device is suitable for resin sand mixing in the production of foundry sand molds. Its core objective is to achieve uniform mixing of sand and resin, while preventing sand and gravel dust from entering the outer bearing housing during the mixing process and affecting subsequent normal mixing.

[0030] The support base 100 is equipped with leveling feet at the bottom to ensure the stability of the device during operation; the mixing hopper 300 is a horizontally placed cylindrical shell, which is welded from wear-resistant steel plate and has a wear-resistant coating sprayed on the inner wall to extend its service life.

[0031] The mixing shaft 330 is driven by a variable frequency motor with adjustable speed to meet the mixing requirements of different proportions of sand; the mixing blades 331 are spiral alloy steel blades, numbered 4-6, evenly arranged along the circumference of the shaft with an inclination angle of 30-45°. When rotating, they generate axial thrust, which drives the sand and resin to roll upward and mix, with a mixing uniformity of ≥95%.

[0032] The barrier blade 340 has an inclination angle of -30 to -45° (opposite to the mixing blade 331) and is located 50-80 mm above the side of the discharge opening 320. Its function is to slow down the flow rate of the mixing material into the discharge opening 320, prolong the mixing time, and at the same time reduce the rate and amount of material moving towards the outer bearing seat, reduce the amount of impurities entering the bearing seat, and reduce the impact on the bearing seat. The gap between the barrier blade 340 and the inner wall of the mixing housing 310 is 5-10 mm to avoid scratching the housing.

[0033] The protective gas ejected by the airtight device 700 is dry compressed air or nitrogen with a moisture content ≤0.01g / m³. This continuous ejection forms an air curtain, preventing dust generated during the mixing process from leaking through the gap between the shaft and the housing. This avoids dust entering the bearing housing and affecting the normal, continuous rotation of the mixing shaft 330, achieving a dust control efficiency ≥98%. The discharge opening 320 is a circular opening located at the bottom of the mixing housing 310 near the bearing housing. The mixed material is discharged from this opening to the subsequent sand molding equipment.

[0034] In summary, through the above structural design, the reverse blocking blade 340 and the airtight device 700 work together. The blocking blade 340 can apply a reverse thrust to the mixed sand and gravel material, preventing the sand and gravel material from accumulating on the inner side of the bearing seat and forming a mechanical barrier. The airtight device 700 can form a gas protection barrier on the inner side of the bearing seat, preventing small dust particles from entering the bearing seat through the rotation gap. Through the above double sealing structure design, the sealing effect on one side of the bearing seat can be greatly improved, ensuring that the mixing shaft 330 can rotate normally and continuously.

[0035] Specifically, the airtight device 700 includes a sealing ring 730 fixed to the inner wall of the mixing housing 310. An airtight channel 731 is formed between the sealing ring 730 and the mixing shaft 330. A pressurization pipe communicating with the airtight channel 731 is provided inside the mixing shaft 330. A pumping device is connected to the outside of the pressurization pipe, and the pumping device directionally pumps protective gas into the airtight channel 731. The protective gas can be directionally discharged from the inside of the airtight channel 731 to the outside. Figure 3 The dust is discharged in a directional annular pattern from the right to the left, preventing it from entering the annular airtight channel 731 and ultimately preventing it from entering the bearing housing, thus ensuring the normal and efficient continuous sand mixing operation of the entire equipment.

[0036] The sealing ring 730 is made of wear-resistant alloy and has a ring structure. Its inner diameter is 2-3 mm larger than the outer diameter of the mixing shaft 330. The width of the airtight channel 731 formed is 2-3 mm, which ensures that the protective gas can be sprayed out evenly to form an air curtain. The sealing ring 730 is fixed to the inner wall of the mixing shell 310 by bolts, and a high-temperature resistant sealing gasket is set at the connection to prevent gas leakage.

[0037] The pressurization pipe is an axial through hole opened inside the mixing shaft 330, which is connected to the airtight channel 731 and guides the gas delivered by the pumping device to the airtight channel; the pumping device can stably provide positive pressure protective gas to ensure that the pressure in the airtight channel 731 is constant.

[0038] Furthermore, the air pumping device includes an air pumping pipe 710, which is connected to a booster pipe via a rotary seal 720. The air pumping pipe 710 is a PU flexible hose, with one end connected to the outlet of the air pumping device and the other end connected to the booster pipe of the mixing shaft 330 via the rotary seal 720. The rotary seal 720 is a mechanical seal structure, adapted to the speed and pressure requirements of the mixing shaft 330, with a sealing leakage rate ≤0.1L / min, ensuring a reliable seal between the air pumping pipe 710 and the rotating booster pipe, preventing protective gas leakage, and not affecting the normal rotation of the mixing shaft 330. The rotary seal 720 is installed at the outer end of the mixing shaft 330, away from the dusty environment inside the mixing hopper 300, extending its service life.

[0039] Specifically, the pressurization pipeline includes a first pressurization pipeline 741 arranged along the axis of the mixing shaft 330. The sidewall of the first pressurization pipeline 741 is connected to the airtight channel 731 through multiple second pressurization pipelines 743. The first pressurization pipeline 741 is an axial through hole at the center of the mixing shaft 330, and the second pressurization pipelines 743 are radial through holes, numbering 4-6, evenly arranged around the circumference of the first pressurization pipeline 741. One end of each second pressurization pipeline 743 is connected to the first pressurization pipeline 741, and the other end extends through to the surface of the mixing shaft 330 and connects to the airtight channel 731. The design of multiple second pressurization pipelines 743 allows protective gas to enter the airtight channel 731 from different directions, ensuring uniform distribution of the air curtain and avoiding insufficient local gas pressure that could lead to seal failure. The outlet end of the second pressurization pipeline 743 is chamfered to prevent eddies from forming when the gas is ejected, which could affect the stability of the air curtain.

[0040] Furthermore, an elastic adjustment component 742 is provided inside the first pressurization pipe 741. The elastic adjustment component 742 is slidably connected to the inner wall of the first pressurization pipe 741, and the second pressurization pipe 743 is located on the moving path of the elastic adjustment component 742.

[0041] The elastic adjustment component 742 includes a piston and a compression component. A spring can be fitted on the outside of the rod. The piston is made of rubber and slides against the inner wall of the first pressurization pipe 741, allowing it to move axially along the first pressurization pipe. The compression spring is fitted on one side of the piston and, under normal conditions, pushes the piston to block part of the second pressurization pipe 743, achieving a bidirectional seal and preventing dust from entering the airtight channel 731 during shutdown.

[0042] When the output pressure of the pumping device changes, the elastic adjustment component 742 will move automatically: when the pressure increases, the piston compresses the spring, reducing the area of ​​the elastic adjustment component 742 blocking the second pressurization pipe 743, and increasing the gas flow rate; when the pressure decreases, the spring returns to its original position, increasing the area of ​​the second pressurization pipe 743, and maintaining the pressure stability in the airtight channel 731.

[0043] Furthermore, the barrier blade 340 is detachably connected to the mixing shaft 330, and the barrier blade 340 has different installation angles. A limiting component is provided between the barrier blade 340 and the elastic adjustment component 742 to adjust the extreme contraction position of the elastic adjustment component 742. By controlling the extreme contraction distance of the elastic adjustment component 742, the extreme movement position of the elastic adjustment component 742 can be adjusted, thereby adjusting the extreme ventilation volume at the pressurization pipe 743 and automatically controlling the gas flow.

[0044] When the mixture consists of large-sized resin, the barrier blade 340 is installed at a slightly larger angle, which can better disperse the large-sized resin and sand, promoting their mixing. At this time, the limit contraction position of the elastic adjustment component 742 is shorter. When the elastic adjustment component 742 is at its limit position, it partially blocks the pressurization pipe 743, automatically reducing the ventilation volume of the protective gas. This satisfies the positive pressure dust prevention requirement while avoiding interference with the mixing of large-sized resin and sand.

[0045] When the mixed resin is of small size, the installation angle of the barrier blade 340 is slightly smaller, which can achieve better dust prevention and enhance the sealing effect of the barrier blade 340. At this time, the limit contraction position of the elastic adjustment component 742 is longer, and the pressure boosting pipe 743 is in a completely open and unobstructed state. This can automatically increase the ventilation volume of the protective gas, prevent more small dust particles from passing through the airtight channel 731 and entering the bearing housing, and ensure the normal operation of the overall seal.

[0046] The barrier blade 340 and the mixing shaft 330 are detachably connected by a spring pin, which makes it easy to replace worn blades or adjust the installation angle. The barrier blades 340 with different installation angles (such as -30°, -35°, -40°, -45°) can be adapted to mixing materials with different flowability and different sizes. The smaller the installation angle, the stronger the barrier effect on the mixing and the longer the mixing time.

[0047] The function of the limiting component is to control the maximum opening degree of the pressurization pipe 743 by adjusting the limit contraction position of the elastic adjustment component 742, thereby adjusting the maximum flow rate of the protective gas, so that the gas flow rate is precisely matched with the dust volume of the mixture and the resin curing requirements. The limiting component is linked with the barrier blade 340. When the barrier blade 340 is replaced with a different angle, the limiting component can be automatically adjusted synchronously to achieve adaptive adjustment of the gas flow rate.

[0048] As an optional implementation, the limiting component is a mechanical limiting rod, and a limiting opening 345 is opened on the side wall of the blocking blade 340. The limiting opening 345 can limit the maximum stroke of the mechanical limiting rod, thereby limiting the maximum movement path of the elastic adjustment component 742 fixedly connected to the mechanical limiting rod.

[0049] The mechanical limiting rod can be made of stainless steel. One end is fixedly connected to the piston of the elastic adjustment component 742, and the other end extends to the outside of the mixing shaft 330, engaging with the limiting opening 345 on the side wall of the barrier blade 340. The limiting opening 345 is a slit formed on the cylindrical blade holder 342 of the barrier blade 340, and the end of the mechanical limiting rod is embedded in the limiting opening 345. When the barrier blade 340 is replaced with one of different installation angles, the position of the limiting opening 345 changes synchronously, thereby limiting the travel of the mechanical limiting rod and adjusting the limit retraction position of the elastic adjustment component 742.

[0050] For example, when the blocking blade 340 is installed at an angle of -30°, the limiting opening 345 is positioned outward, the mechanical limiting rod has a large travel distance, and the elastic adjustment component 742 can open a larger ventilation area for the booster pipe 2 743; when the installation angle is -45°, the limiting opening 345 is positioned inward, the mechanical limiting rod has a small travel distance, and the ventilation area of ​​the booster pipe 2 743 is reduced.

[0051] As another optional implementation, the limiting component is a magnetic limiting rod. The blocking blade 340 is embedded with a magnetic block, which can limit the movement path of the magnetic separation limiting rod by the action of different magnetic blocks, so as to attract the magnetic separation limiting rod to move to a fully open state, or repel the magnetic separation limiting rod to drive the elastic adjustment component 742 to a partially blocked state. It should be noted that when the magnetic method is selected, the mixing shaft 330 and related materials need to be selected as non-magnetic materials to avoid magnetic influence.

[0052] The magnetic limiting rod is a stainless steel rod with a built-in permanent magnet, which is fixedly connected to the piston of the elastic adjustment component 742; the magnetic block is a neodymium iron boron permanent magnet, which is embedded in the cylindrical blade holder 342 of the blocking blade 340 and corresponds to the magnetic limiting rod.

[0053] The magnetic attraction between the magnetic limiting rod and the magnetic block limits the extreme contraction position of the elastic adjustment component 742. When the blocking blade 340 is replaced with one at a different installation angle, the position of the magnetic block changes, and the magnitude and direction of the magnetic attraction force are adjusted accordingly, thereby changing the maximum contraction amount of the elastic adjustment component. This magnetic separation structure requires no mechanical contact, has low wear, is suitable for mixed sand environments with high dust levels, and offers precise adjustment and rapid response.

[0054] Furthermore, the barrier blade 340 includes a columnar blade holder 342 and a strip blade 341. The columnar blade holder 342 has a first limiting hole 343 and a second limiting hole 344 on its side wall. The first limiting hole 343 and the second limiting hole 344 intersect each other.

[0055] The columnar cutter holder 342 is fixed to the mixing shaft 330 by bolts or spring pins. The first limiting hole 343 and the second limiting hole 344 on its side wall can be threaded holes for installing limiting bolts, further fixing the position of the strip-shaped blade 341 and preventing the blade from loosening during sand mixing. The strip-shaped blade 341 is made of wear-resistant alloy steel and is connected to the columnar cutter holder 342 by welding or bolts. The blade surface is hardened to extend its wear life. The tilt angle of the strip-shaped blade 341 is adjusted by the installation angle between the columnar cutter holder 342 and the mixing shaft 330. The design of the first limiting hole 343 and the second limiting hole 344 allows for precise positioning of the blade's installation angle. By rotating the columnar cutter holder 342 to different angles and controlling the first limiting hole 343 or the second limiting hole 344 to the installation position, the overall tilt angle of the blocking blade 340 can be adjusted.

[0056] A negative pressure channel 321 with a built-in filter is provided on the side wall of the feeding opening 320. The negative pressure channel 321 is linked to the airtight device 700 for control. The negative pressure channel 321 can absorb most of the dust generated during the mixing process, preventing excessive dust from being discharged into the workshop and affecting the production environment. At the same time, it can work with the blown protective gas to form a directional collection airflow, achieving efficient directional collection of dust.

[0057] The negative pressure channel 321 is a circular channel opened on the side wall of the discharge opening 320, with a built-in stainless steel filter screen, used to filter out sand, gravel and resin that may overflow from the discharge opening 320 during the mixing process.

[0058] The negative pressure channel 321 and the airtight device 700 are linked and controlled by a PLC control system: when the protective gas pressure of the airtight device 700 is lower than the set threshold, the negative pressure fan of the negative pressure channel 321 automatically increases its power to improve the dust collection effect and compensate for the inadequacy of the air curtain seal; when the protective gas pressure returns to normal, the negative pressure fan returns to its normal power, achieving energy-saving operation. This linkage design ensures dust control effectiveness, avoids energy waste, and prevents excessive negative pressure from causing excessive suction of mixed materials, which would affect the material feeding efficiency.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sand mixing device for casting sand molds, comprising a support base (100), a mixing chamber (300) being provided at the upper end of the support base (100), and a sand and gravel discharge channel (600) and a resin discharge channel being provided at the upper end of the mixing chamber (300), characterized in that: The mixing chamber (300) includes a mixing shell (310), a mixing shaft (330) disposed inside the mixing shell (310), and a mixing blade (331) fixed to the surface of the mixing shaft (330). The mixing shell (310) has a discharge opening (320) at its lower end. The mixing shaft (330) also has a blocking blade (340) fixed to the surface above the discharge opening (320). The inclination direction of the blocking blade (340) is opposite to that of the mixing blade (331). An airtight device (700) is provided between the mixing shaft (330) and the mixing shell (310). The airtight device (700) is located on the side of the barrier blade (340) away from the mixing blade (331). An airtight channel (731) is formed between the airtight device (700) and the mixing shaft (330). During the rotation of the mixing shaft (330), the airtight channel (731) is controlled to continuously spray protective gas under positive pressure.

2. The casting sand mold mixing device according to claim 1, characterized in that, The airtight device (700) includes a sealing ring (730) fixed to the inner wall of the mixing housing (310), and an airtight channel (731) is formed between the sealing ring (730) and the mixing shaft (330). A pressurizing pipe communicating with the airtight channel (731) is provided inside the mixing shaft (330), and a pumping device is connected to the outside of the pressurizing pipe.

3. The casting sand mold mixing device according to claim 2, characterized in that, The air pumping device includes an air pumping pipe (710), which is connected to a booster pipe via a rotary seal (720).

4. A sand mixing device for casting sand molds according to claim 2, characterized in that, The pressurization pipeline includes a pressurization pipeline 1 (741) arranged along the axis of the mixing shaft (330), and the side wall of the pressurization pipeline 1 (741) is connected to the airtight channel (731) through multiple pressurization pipelines 2 (743).

5. A sand mixing device for casting sand molds according to claim 4, characterized in that, An elastic adjustment component (742) is provided inside the first pressurization pipe (741). The elastic adjustment component (742) is slidably connected to the inner wall of the first pressurization pipe (741), and the second pressurization pipe (743) is located on the moving path of the elastic adjustment component (743).

6. A sand mixing device for casting sand molds according to claim 5, characterized in that, The barrier blade (340) is detachably connected to the mixing shaft (330), and the barrier blade (340) has different installation angles. A limiting component is provided between the barrier blade (340) and the elastic adjustment component (742) to adjust the extreme contraction position of the elastic adjustment component (742).

7. A sand mixing device for casting sand molds according to claim 6, characterized in that, The limiting component is a mechanical limiting rod, and the blocking blade (340) has a limiting opening (345) on its side wall.

8. A sand mixing device for casting sand molds according to claim 6, characterized in that, The limiting component is a magnetic limiting rod, and a magnetic block is embedded inside the blocking blade (340).

9. A sand mixing device for casting sand molds according to claim 1, characterized in that, The barrier blade (340) includes a columnar blade holder (342) and a strip blade (341). The columnar blade holder (342) has a first limiting hole (343) and a second limiting hole (344) on its side wall.

10. A sand mixing device for casting sand molds according to claim 1, characterized in that, The side wall of the discharge opening (320) is provided with a negative pressure channel (321) with a built-in filter, and the negative pressure channel (321) is linked and controlled with the airtight device (700).

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