Foundry sand classifier and method of classifying

Abstract

The application provides a casting sand powder selecting machine and a powder selecting method, and belongs to the technical field of casting sand processing equipment. The casting sand powder selecting machine comprises a powder selecting cylinder, a feeding cylinder, a fine sand cylinder and a medium sand powder selecting assembly. The powder selecting cylinder is sequentially provided with a powder discharging cavity, a powder selecting cavity and a material guiding cavity from top to bottom. The upper end of the powder selecting cylinder is provided with a powder discharging port, and the powder discharging port is communicated with the powder discharging cavity. The lower end of the powder selecting cylinder is provided with a material guiding port, and the material guiding port is communicated with the material guiding cavity. The medium sand powder selecting assembly comprises a rotating cage arranged in the powder selecting cavity and a sand collecting cone. The sand collecting cone is arranged below the rotating cage and coaxially arranged with the rotating cage. The bottom of the sand collecting cone is extended out of the powder selecting cylinder through a medium sand discharging pipe. The rotating cage comprises an upper rotating cage and a lower rotating cage. The upper rotating cage and the lower rotating cage are coaxially arranged. The diameter of the lower rotating cage gradually increases from bottom to top. The casting sand powder selecting machine provided by the application solves the problem of easy clogging of the traditional rotating cage, realizes three-stage classification of the casting sand, and improves the grading accuracy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of foundry sand processing equipment, and more particularly to a foundry sand powder selecting machine and a powder selecting method. BACKGROUND

[0002] In the industrial fields of construction, casting, etc., the particle size grading precision and purity of sand and stone directly affect the quality of downstream products. Among them, machine-made sand has gradually replaced natural sand as the mainstream due to the depletion of natural river sand resources and environmental protection policy restrictions, but in the existing sand making process, the powder selecting equipment as the core device to control the particle size and remove the powder of sand and stone still has many technical defects, which is difficult to meet the high precision requirements of multiple fields, especially the production of foundry sand.

[0003] At present, in the foundry sand powder selecting machine, some equipment realizes sand and powder separation by using structures such as rotating cages through the upper and lower combined sand selecting mechanism and powder selecting mechanism, which can improve the utilization rate of the equipment to a certain extent, but such equipment is designed for the particle size range of conventional machine-made sand, and cannot adapt to the specific effective particle size requirements of foundry sand, so it is difficult to realize the accurate three-stage classification of coarse sand, medium sand and fine sand required by foundry sand. SUMMARY

[0004] The purpose of the present application is to provide a foundry sand powder selecting machine and a powder selecting method, which aims to improve the grading precision of foundry sand.

[0005] To achieve the above purpose, the technical solution adopted by the present application is to provide a foundry sand powder selecting machine and a powder selecting method, which comprises:

[0006] The powder selecting cylinder body is sequentially distributed with a powder outlet cavity, a powder selecting cavity and a material guiding cavity from top to bottom, the upper end of the powder selecting cylinder body is provided with a powder outlet, and the powder outlet communicates with the powder outlet cavity; the lower end of the powder selecting cylinder body is provided with a material guiding port, and the material guiding port communicates with the material guiding cavity;

[0007] The feed cylinder body is located on one side of the powder selecting cylinder body, the upper end of the feed cylinder body is provided with a feed port, the lower part of the feed cylinder body communicates with the material guiding port, the bottom of the feed cylinder body is provided with a coarse sand port, and the side of the feed cylinder body away from the material guiding port is communicated with a blowing pipe of a fan;

[0008] The fine sand cylinder body is located on the side of the powder selecting cylinder body, the upper part of the fine sand cylinder body communicates with the powder outlet, and the bottom of the fine sand cylinder body is provided with a fine sand port;

[0009] The medium sand selecting assembly comprises a rotating cage and a sand collecting cone arranged in the selecting cavity, the sand collecting cone is arranged below the rotating cage and coaxially with the rotating cage, the bottom of the sand collecting cone extends out of the selecting cylinder through a medium sand discharging pipe, the rotating cage comprises an upper rotating cage and a lower rotating cage, the upper rotating cage and the lower rotating cage are coaxially arranged, and the diameter of the lower rotating cage gradually increases from bottom to top.

[0010] As another embodiment of the present application, the blade spacing of the lower rotating cage is greater than the blade spacing of the upper rotating cage.

[0011] As another embodiment of the present application, the blade of the lower rotating cage is an arc-shaped concave blade, and the concave surface of the arc-shaped concave blade is inclined downward.

[0012] As another embodiment of the present application, the diameter of the upper rotating cage gradually decreases from bottom to top.

[0013] As another embodiment of the present application, at least one spiral guide vane is arranged on the outer side wall of the sand collecting cone, and the upper end of the spiral guide vane extends to the upper end surface of the sand collecting cone.

[0014] As another embodiment of the present application, the diameter of the selecting cavity gradually increases from top to bottom, and the diameter of the material guiding cavity gradually decreases from top to bottom.

[0015] As another embodiment of the present application, the feeding assembly is mounted on the feeding port, and the feeding assembly comprises:

[0016] a feeding buffer cavity fixedly connected with the feeding cylinder;

[0017] a feeding conveying cavity located below the feeding buffer cavity and in communication with the bottom of the feeding buffer cavity;

[0018] a feeding conveying assembly comprising a rotating shaft coaxial with the feeding conveying cavity and a spiral conveying vane annularly arranged on the outer periphery of the rotating shaft, and an end portion of the rotating shaft is connected with a driving motor.

[0019] As another embodiment of the present application, the feeding conveying cavity is arranged at an angle with the feeding buffer cavity, and the feeding conveying cavity faces the coarse sand port.

[0020] As another embodiment of the present application, the outlet end of the air supply pipe of the fan is provided with a shunt sieve plate, the shunt sieve plate is a multi-section structure, and the sieve hole density of the shunt sieve plate gradually increases from top to bottom.

[0021] The casting sand screening machine has the advantages that: compared with the prior art, the casting sand screening machine cooperates with the airflow field through the upper rotating cage and the lower rotating cage, the space below the lower rotating cage is narrow, and the airflow speed is relatively high, so that the material is pushed to move upward quickly; as the diameter of the rotating cage increases, the space expands, and the airflow speed tends to be stable, thereby providing a stable airflow environment for the 'fine screening' of the upper rotating cage; the lower part of the lower rotating cage has a small diameter and a relatively small centrifugal force, so that the small-diameter medium sand is prevented from being screened by mistake, and the upper part of the lower rotating cage has a large diameter and a relatively large centrifugal force, so that the large-diameter medium sand that is not screened by the lower part is effectively separated, and the large-diameter medium sand is prevented from entering the upper rotating cage upward to interfere with the separation of the small-diameter medium sand; the problem of easy blocking of the traditional rotating cage is solved, three-stage classification of the casting sand is realized, and the gradation accuracy is improved.

[0022] The application further provides a casting sand screening method, characterized by adopting the casting sand screening machine, and further comprising the following steps.

[0023] S1, the casting sand raw material is conveyed to the feeding cylinder body, and after being pre-dispersed by the airflow blown by the fan, the airflow disperses the casting sand raw material and carries the casting sand raw material to the screening cavity;

[0024] S2, the airflow carrying the casting sand raw material is subjected to first-stage classification by the lower rotating cage, and through the coordinated action of the centrifugal force of the lower rotating cage and the upward airflow, the first part of the medium sand is uniformly screened out through the inverted conical structure with gradually increasing diameters from bottom to top;

[0025] S3, the airflow carrying the medium sand and the fine sand is subjected to screening by the upper rotating cage, the second part of the medium sand is intercepted, the intercepted second part of the medium sand falls into the sand collecting cone, and then is discharged through the medium sand discharge pipe at the bottom of the sand collecting cone; and the remaining fine sand is discharged from the powder outlet to the fine sand cylinder body by means of the airflow;

[0026] S4, the fine sand in the fine sand cylinder body is subjected to airflow sedimentation in the fine sand cylinder body, so that the fine sand is discharged from the fine sand outlet at the bottom of the fine sand cylinder body to complete the collection.

[0027] The casting sand screening method has the advantages that: compared with the prior art, the casting sand screening method adopts the casting sand screening machine, and has all the advantages of the casting sand screening machine; and the coarse-diameter medium sand and the fine-diameter medium sand are subjected to segmented screening, so that the particle size range of the medium sand product is accurately controlled between the lower limit of the gap of the upper rotating cage and the upper limit of the gap of the lower rotating cage, the particle size gradation qualified rate is improved, and the demand of the casting process for the sand particle gradation is met. BRIEF DESCRIPTION OF DRAWINGS

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a side view of the foundry sand classifier provided in an embodiment of the present invention;

[0030] Figure 2 This is a longitudinal sectional view of the foundry sand classifier provided in the first embodiment of the present invention;

[0031] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0032] Figure 4 for Figure 2 Enlarged view of point B in the middle;

[0033] Figure 5 This is a longitudinal sectional view of the foundry sand classifier provided in the second embodiment of the present invention;

[0034] Figure 6 This is a partially enlarged view of the feeding and conveying cavity provided in the second embodiment of the present invention.

[0035] In the diagram: 100, fan; 101, air outlet screen plate; 102, screen holes;

[0036] 200. Feed cylinder; 201. Coarse sand discharge pipe; 202. First guide plate; 203. Second guide plate; 204. Feed buffer chamber; 205. Feed conveying chamber; 206. Spiral conveyor blades; 207. Rotating shaft; 208. Sleeve; 209. Crushing teeth;

[0037] 300. Powder separator cylinder; 301. Medium sand discharge pipe; 302. Rotary drum shaft; 303. Rotary drum motor; 304. Lower rotary drum; 305. Upper rotary drum; 306. Sand collecting cone; 307. Spiral guide vanes; 308. Medium sand inlet; 309. Material guide inlet;

[0038] 400. Fine sand cylinder; 401. Fine sand discharge pipe; 402. Powder outlet. Detailed Implementation

[0039] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0040] Please refer to Figures 1 to 6 The casting sand powder selecting machine comprises a powder selecting cylinder 300, a feeding cylinder 200, a fine sand cylinder 400 and a medium sand powder selecting assembly. The powder selecting cylinder 300 is sequentially provided with a powder discharging cavity, a powder selecting cavity and a material guiding cavity from top to bottom. The upper end of the powder selecting cylinder 300 is provided with a powder discharging port 402, and the powder discharging port 402 is communicated with the powder discharging cavity. The lower end of the powder selecting cylinder 300 is provided with a material guiding port 309, and the material guiding port 309 is communicated with the material guiding cavity. The feeding cylinder 200 is located at one side of the powder selecting cylinder 300. The upper end of the feeding cylinder 200 is provided with a feeding port. The lower part of the feeding cylinder 200 is communicated with the material guiding port 309. The bottom of the feeding cylinder 200 is provided with a coarse sand port. The side of the feeding cylinder 200 away from the material guiding port 309 is communicated with a blowing pipe of a fan 100. The fine sand cylinder 400 is located at the side of the powder selecting cylinder 300. The upper part of the fine sand cylinder 400 is communicated with the powder discharging port 402. The bottom of the fine sand cylinder 400 is provided with a fine sand port. The medium sand powder selecting assembly comprises a rotating cage and a sand collecting cone 306 arranged in the powder selecting cavity. The sand collecting cone 306 is located below the rotating cage and coaxially arranged with the rotating cage. The bottom of the sand collecting cone 306 is extended out of the powder selecting cylinder 300 through a medium sand discharging pipe 301. The rotating cage comprises an upper rotating cage 305 and a lower rotating cage 304. The upper rotating cage 305 and the lower rotating cage 304 are coaxially arranged. The diameter of the lower rotating cage 304 gradually increases from bottom to top.

[0041] The casting sand powder selecting machine can better meet the accurate three-stage classification requirements of coarse sand, medium sand and fine sand of the casting sand through the layered arrangement of the powder selecting cylinder 300, the coaxial arrangement of the upper rotating cage 305 and the lower rotating cage 304 in the medium sand powder selecting assembly and the gradual increase of the diameter of the lower rotating cage 304 from bottom to top.

[0042] The feeding cylinder 200 is located at one side of the powder selecting cylinder 300. The feeding port at the upper end of the feeding cylinder 200 is used for feeding the casting sand material. The lower part of the feeding cylinder 200 is communicated with the material guiding port 309 of the powder selecting cylinder 300. The bottom of the feeding cylinder 200 is provided with a coarse sand port. The side of the feeding cylinder 200 away from the material guiding port 309 is communicated with the blowing pipe of the fan 100. The air flow provided by the blowing pipe of the fan 100 makes the casting sand material entering the feeding cylinder 200 move to the powder selecting cylinder 300 under the action of the air flow. At the same time, the coarse sand is directly discharged from the coarse sand port at the bottom of the feeding cylinder 200 under the action of gravity due to the large particle size and heavy mass. The medium sand, the fine sand and part of the coarse sand are driven by the air flow delivered by the blowing pipe of the fan 100 to move towards the material guiding port 309 and then enter the powder selecting cylinder 300 from the material guiding port 309.

[0043] The powder selection cylinder 300 is sequentially provided with a powder outlet cavity, a powder selection cavity and a material guiding cavity from top to bottom. After the material enters the material guiding cavity from the feeding cylinder 200, it will rise and enter the powder selection cavity. The rotating cage in the powder selection cavity rotates at high speed, and the casting sand particles are separated under the joint action of airflow and the rotating cage. The coarse sand is separated by the lower rotating cage 304 when entering the lower rotating cage 304, and the diameter of the lower rotating cage 304 gradually increases from bottom to top, so that all the casting sand particles pass through the lower rotating cage 304, and the separation efficiency of the lower rotating cage 304 is improved. The fine sand particles with smaller particle size will rise with the airflow, enter the powder outlet cavity, and then enter the fine sand cylinder 400 through the powder outlet 402. The lower rotating cage 304 and the upper rotating cage 305 are both installed on the rotating cage shaft 302, and the upper end of the rotating cage shaft 302 is connected with the rotating cage motor 303.

[0044] Specifically, when the casting sand particles flow upward from the material guiding cavity into the powder selection cavity, they first enter the coverage area of the lower rotating cage 304. Since the lower rotating cage 304 has a structure of “diameter increasing from bottom to top”, the radial space at the lower part is narrow, and the airflow speed is relatively low when the material just enters. The centrifugal force of the medium sand particles with larger particle size is significantly greater than the airflow carrying force due to their large mass.

[0045] Under the centrifugal action of the high-speed rotation of the lower rotating cage 304, the first part of the medium sand with larger particle size is quickly thrown to the inner wall of the rotating cage, and directly passes through the rotating cage gap and falls into the sand collecting cone 306 below. The sand collecting cone 306 has a structure of inverted cone and is in the shape of a funnel. This structure can guide the medium sand particles to gather towards the center and avoid scattering outward. At the same time, the design of the lower rotating cage 304 in the shape of inverted cone can avoid the accumulation of medium sand with large particle size at the lower part. As the diameter of the rotating cage increases, the radial space expands, and the particles that are not immediately screened can flow upward to the upper rotating cage 305, so that the material flow is smooth and unblocked.

[0046] After being screened by the lower rotating cage 304, the small particle size medium sand, fine sand and the like continue to flow upward and enter the coverage area of the upper rotating cage 305: at this time, the airflow speed tends to be stable after passing through the lower rotating cage 304, and the second part of the medium sand with smaller particle size becomes the main screening target. The centrifugal force of the second part of the medium sand is smaller than that of the first part of the medium sand, but it is still greater than the airflow carrying force. Under the condition that the leaf gap of the upper rotating cage 305 is smaller, the second part of the medium sand is thrown to the inner wall of the upper rotating cage 305, passes through the rotating cage gap, and is collected with the first part of the medium sand and falls into the sand collecting cone 306.

[0047] Optionally, the diameter of the upper rotating cage 305 is consistent along the vertical direction. Its coverage is wider, and the uniform diameter design of the upper rotating cage 305 ensures the consistency of screening. The distribution of the rotating cage gap and the centrifugal field is uniform, which avoids the mis-screening of the second part of the medium sand due to the change of the radial space.

[0048] The mixed first part of medium sand and the second part of medium sand are discharged from the powder selecting cylinder 300 through the medium sand discharge pipe 301, and the accurate separation of the medium sand is completed; and the fine sand particles continue to rise with the airflow due to insufficient centrifugal force, enter the powder discharge cavity, and are finally collected by the fine sand cylinder 400.

[0049] Compared with the prior art, the casting sand powder selecting machine provided by the application cooperates with the airflow field in the mode that the upper layer rotating cage 305 and the lower layer rotating cage 304 cooperate, the space below the lower layer rotating cage 304 is narrow, and the airflow flow rate is relatively high, which can push the material to move upward quickly; as the diameter of the rotating cage increases, the space expands, and the airflow flow rate tends to be stable, which provides a stable airflow environment for the fine screening of the upper layer rotating cage 305; and the lower part of the lower layer rotating cage 304 has a small diameter, and the centrifugal force is relatively small, which can avoid the mis-screening of the small particle size medium sand; the upper part has a large diameter, and the centrifugal force is relatively large, which can ensure that the large particle size medium sand that is not screened by the lower part is effectively separated, and the large particle size medium sand is prevented from entering the upper layer rotating cage 305 upward to interfere with the separation of the small particle size medium sand; the problem of easy blocking of the traditional rotating cage is solved, three-stage classification of the casting sand is realized, and the gradation accuracy is improved.

[0050] Correspondingly, the coarse sand outlet is communicated with a coarse sand discharge pipe 201, and the fine sand outlet is communicated with a fine sand discharge pipe 401. The bottom of the sand collecting cone 306 is provided with a medium sand outlet 308, and the medium sand outlet 308 is communicated with the medium sand discharge pipe 301.

[0051] In some possible embodiments, referring to Figure 2 , Figure 3 and Figure 5 , the leaf spacing of the lower layer rotating cage 304 is greater than the leaf spacing of the upper layer rotating cage 305.

[0052] Optionally, the leaf spacing of the lower layer rotating cage 304 is 0.3mm-0.6mm, and the leaf spacing of the upper layer rotating cage 305 is 0.15mm-0.3mm. At this time, the particle size range of the first part of medium sand is greater than 0.3mm, and the particle size range of the second part of medium sand is 0.15mm-0.3mm.

[0053] The larger leaf spacing of the lower layer rotating cage 304 makes the second part of medium sand and the fine sand that meet the subsequent selection requirements successfully rise to the upper layer rotating cage 305 along with the airflow, and will not be excessively intercepted in the lower layer, reducing the situation that the medium particles are misjudged as coarse powder and returned to the mill. In addition, the lower layer rotating cage 304 needs to receive a large amount of material and airflow from below, and the large spacing can reduce the resistance of the airflow passing through the lower layer rotating cage 304, avoid the problem of fine sand settling caused by airflow blockage, ensure that the material and the airflow stably rise upward, and reduce the generation of vortex.

[0054] The fan blades of the upper rotating cage 305 have a small interval, which makes the blades have a better blocking effect on the airflow and particles, and the qualified fine sand can pass through the small interval gap to ensure the purity of the finished product; and prevents the critical coarse particles from entering the powder outlet cavity with the airflow to ensure the fine sand recovery rate and the finished product accuracy.

[0055] Optionally, the fan blades of the lower rotating cage 304 are arc concave fan blades, and the concave surface of the arc concave fan blades is inclined downward.

[0056] Since the fan blades of the lower rotating cage 304 have a large interval and the concave surface is inclined downward, when the medium sand and fine sand enter the lower rotating cage 304, the first part of the medium sand with a large particle size is more likely to slide downward along the concave surface under the joint action of gravity and airflow, and is discharged through the medium sand discharge pipe 301, thereby realizing the preliminary separation of coarse sand, medium sand and fine sand. Compared with the flat fan blades, the arc concave fan blades have a more uniform stress under the same airflow and particle impact, which can reduce the wear of the fan blades and prolong the service life of the rotating cage.

[0057] The design of the arc concave fan blades can ensure that the flow lines of the airflow in the channel between the rotating cage blades coincide with the profile lines of the rotating cage blades, reduce the impact of the rotating cage blades on the airflow and powder, inhibit the formation of airflow vortex between the rotating cage blades, improve the stability of the flow field between the rotating cage blades, and help to more accurately classify the foundry sand and improve the classification efficiency and accuracy.

[0058] Correspondingly, the fan blades of the upper rotating cage 305 are flat fan blades.

[0059] In some possible embodiments, please refer to Figure 5 The diameter of the upper rotating cage 305 gradually decreases from bottom to top.

[0060] The upper rotating cage 305 forms a tapered structure by virtue of the gradually decreasing width of the fan blades thereof; wherein the lower part of the upper rotating cage 305 directly abuts the upper outlet of the lower rotating cage 304, so that the airflow carrying the second part of the medium sand and fine sand from the lower part enters the lower part of the upper part uniformly, ensuring uniform distribution of the airflow and particles.

[0061] The upper rotating cage 305 rotates at a high speed, and the second part of the medium sand starts to be affected by the centrifugal force in the large-diameter area of the lower part due to its mass being greater than that of the fine sand, and gradually moves close to the inner wall of the fan blade, while the fine sand still tends to move upward with the airflow due to its light mass. When the material moves upward, the radius of rotation of the material decreases, the distance between the particles and the inner wall of the fan blade shortens, and the centrifugal drag force of the fan blade on the particles increases. The second part of the medium sand is attached to the inner wall of the fan blade under the double actions of the centrifugal drag force and the centrifugal force of the second part of the medium sand, and since the interval between the fan blades of the upper part gradually decreases, the attached second part of the medium sand directly passes through the gap between the fan blades and falls into the sand collecting cone 306.

[0062] In some possible embodiments, please refer to Figure 2 andFigure 5 The outer side wall of the sand collecting cone 306 is provided with at least one spiral guide vane 307, and the upper end of the spiral guide vane 307 extends to the upper end surface of the sand collecting cone 306.

[0063] The shape and angle of the spiral guide vane 307 are designed to enable the air flow entering the sand collecting cone 306 to perform a spiral motion along the surface of the vane, thereby enhancing the centrifugal force of the air flow.

[0064] After the casting sand enters the material guiding cavity, it moves upward until it enters the guiding area formed by the spiral guide vane 307; as the inclination angle of the vane, the air flow drives the medium sand and fine sand of the casting sand to move upward along the guiding area in a spiral manner, thereby slowing down the material conveying speed, and at the same time, the spiral guide vane 307 enables part of the coarse sand entering the powder selecting cylinder 300 to slide along the surface of the vane after colliding with the wall, and then enter the feeding cylinder 200 through the material guiding port 309, and finally be discharged from the coarse sand port.

[0065] After the air flow drives the casting sand to enter the material guiding cavity, it flows upward in a spiral manner through the gap of the spiral guide vane 307, and the spiral guide vane 307 guides the air flow to form an orderly spiral upward air flow, thereby avoiding the direct collision of horizontal air flow and vertical air flow to generate vortex.

[0066] Optionally, the rotation direction of the spiral upward air flow is consistent with the rotation direction of the powder selecting cavity rotating cage (e.g., both clockwise), and the air flow can cooperate with the centrifugal force of the rotating cage after entering the powder selecting cavity, thereby enhancing the separation force on the medium sand.

[0067] Optionally, the width of the spiral guide vane 307 gradually decreases from bottom to top along the longitudinal direction, so as to adapt to the diameter change of the material guiding cavity.

[0068] In some possible embodiments, referring to Figure 2 The diameter of the powder selecting cavity gradually increases from top to bottom, and the diameter of the material guiding cavity gradually decreases from top to bottom.

[0069] The coarse sand particles have large mass, and after the coarse sand enters the material guiding cavity, due to the decrease of the cavity diameter from top to bottom, the coarse sand is more easily attached to the inner wall of the material guiding cavity and slides downward, and is discharged from the material guiding port 309 to the bottom of the feeding cylinder 200, and finally discharged from the coarse sand port.

[0070] The lower rotating cage 304 and the upper rotating cage 305 cooperate to form a segmented structure with the diameter of the lower rotating cage 304 increasing and the diameter of the upper rotating cage 305 decreasing; the diameter of the powder selecting cavity gradually increases from top to bottom, which can cooperate with the segmented structure of the rotating cage to reduce the gap between the rotating cage and the inner side wall of the powder selecting cavity.

[0071] The setting of the lower end of the powder selection cavity with a large cavity diameter and the upper end with a small cavity diameter can provide sufficient space for the lower layer of the rotating cage 304 in the large cavity diameter area, and there is enough space to be thrown to the inner wall of the rotating cage fan blade, and the large gap of the lower layer of the rotating cage 304 can quickly pass the coarse medium sand to fall into the sand collecting cone 306. If the cavity diameter here is too small, the large diameter structure of the lower layer of the rotating cage 304 will cause the gap between the rotating cage and the cavity wall to be narrow, and the coarse medium sand passing through the rotating cage gap is easy to accumulate on the cavity wall, forming a blockage. The small cavity diameter compresses the air flow channel, and the air flow velocity increases with the decrease of the cavity diameter. The accelerated air flow can push the fine sand and medium sand to the fan blade of the upper layer of the rotating cage 305. In addition, the accelerated air flow can completely capture the fine medium sand before it reaches the powder outlet cavity, improving the classification accuracy.

[0072] In some possible embodiments, referring to Figure 2 and Figure 5 , the feed inlet is provided with a feed assembly, which includes a feed buffer cavity 204, a feed conveying cavity 205, and a feed conveying assembly; the feed buffer cavity 204 is fixedly connected with the feed cylinder body 200; the feed conveying cavity 205 is located below the feed buffer cavity 204 and is in communication with the bottom of the feed buffer cavity 204; the feed conveying assembly includes a rotating shaft 207 and a spiral conveying blade 206; the rotating shaft 207 is coaxial with the feed conveying cavity 205, and the spiral conveying blade 206 is annularly arranged on the outer periphery of the rotating shaft 207; the end of the rotating shaft 207 is connected with a driving motor. The outer side of the rotating shaft 207 is sleeved with a sleeve 208, and the sleeve 208 is located above the spiral conveying blade 206.

[0073] When the foundry sand enters the feed assembly, it first enters the feed buffer cavity 204, gradually moves to the feed conveying cavity 205 through the feed buffer cavity 204, and is then discharged into the feed cylinder body 200 by means of the feed conveying assembly.

[0074] The feed buffer cavity 204 is used to receive external feed to avoid the impact of a large amount of foundry sand on the feed cylinder body 200 at a moment, causing uneven discharge and affecting the powder selection accuracy. Since the feed conveying cavity 205 is in communication with the bottom of the feed buffer cavity 204, the foundry sand in the feed buffer cavity 204 enters the feed conveying cavity 205 at a uniform speed through the communication hole. The driving motor drives the rotating shaft 207 and the spiral blade to rotate at a uniform speed, and the spiral conveying blade 206 can accurately control the material conveying amount per unit time, avoiding the decrease of classification accuracy or the waste of efficiency caused by uneven feeding.

[0075] In addition, the spiral conveying blade 206 can crush slightly caked materials, that is, the edges of the spiral conveying blade 206 can break small caked sand particles when the spiral conveying blade 206 rotates, avoiding the agglomerated sand particles from being stuck in the feed inlet.

[0076] The traditional feeding port is open or semi-open, and the material is easy to block due to caking. In the present scheme, the inner side wall of the feeding conveying cavity 205 can be provided with breaking teeth 209, which are in the form of sharp spikes or spiral teeth. The breaking teeth 209 are located in the gap between the adjacent two layers of spiral conveying blades 206 and are fixed to the cavity wall. The material is pushed by the spiral blades to the breaking teeth 209 during conveying.

[0077] When the breaking teeth 209 are in the form of sharp spikes, the sharp spike-shaped breaking teeth 209 directly pierce into the inside of the caked material, destroying the structural integrity of the caked material. At the same time, the spiral blades continuously exert a pushing force, causing the caked material to rub against the spikes, further tearing the caked material into small particles.

[0078] When the breaking teeth 209 are in the form of spiral teeth, the tooth surface of the spiral teeth and the edge of the spiral blade form a shearing gap. The caked material is sheared into small pieces during the pushing process. At the same time, the spiral trajectories of adjacent breaking teeth 209 are consistent with the direction of movement of the material, which can further grind the small caked material, ensuring that the final output material has no obvious caking.

[0079] A conveying port is provided at the bottom of the feeding conveying cavity 205. The spiral conveying blades 206 drive the sand particles to the conveying port and then discharge them from the conveying port. The direction of the conveying port is perpendicular to the axial direction of the rotating shaft 207. The spiral conveying blades 206 in the rotating state make the direction of the discharged material uniformly toward the tangential direction of the rotating shaft 207. The sand particles move forward with the spiral blades and reach the position of the conveying port at the bottom. Since the conveying port is located at the bottom of the cavity, the sand particles will be separated from the blades under the combined action of the continuous pushing of the spiral blades and their own gravity, and will start to move along the tangent direction of the blades under the action of the tangential force of the blades.

[0080] The uniformly dispersed sand particles enter the feeding cylinder 200 and are impacted by the airflow. The medium sand and fine sand are carried by the airflow into the powder selecting cylinder 300, and the coarse sand moves downward until it is discharged from the coarse sand port. A plurality of guide plates are provided in the feeding cylinder 200. The guide plates are divided into two groups, which are alternately arranged on both sides along the axial direction of the rotating shaft 207. The two groups of guide plates include a plurality of first guide plates 202 arranged in parallel and a plurality of second guide plates 203 arranged in parallel. The first guide plates 202 are located on the side close to the air inlet of the fan 100, and the side close to the coarse sand port of the first guide plates 202 is inclined downward. The first guide plates 202 guide the airflow while receiving the sand particles. The second guide plates 203 are located on the side close to the material guiding port 309, and the side close to the coarse sand port of the second guide plates 203 is inclined downward. The second guide plates 203 change the direction of the airflow while receiving the sand particles, and use the included angle between the second guide plates 203 and the airflow to improve the screening efficiency of the coarse sand.

[0081] In some possible embodiments, please refer to Figure 5The feeding conveying cavity 205 is arranged at an angle with the feeding buffer cavity 204, and the feeding conveying cavity 205 faces the coarse sand outlet.

[0082] The angle design makes the casting sand slide downward along the inclined inner wall of the conveying cavity under the action of its own gravity, and the spiral conveying blade 206 can drive the casting sand to advance, thereby reducing the material falling resistance. The feeding conveying cavity 205 corresponds to the coarse sand outlet, so that the axial direction of the rotating shaft 207 faces the coarse sand outlet. After the sand particles enter the cylinder tangentially to the rotating shaft 207, under the impact of the airflow and the interception of the first guide plate 202 and the second guide plate 203, the coarse sand quickly falls into the coarse sand outlet.

[0083] The feeding conveying cavity 205 and the feeding buffer cavity 204 arranged at an angle make the material falling in the feeding conveying cavity 205 uniform, and reduce the material falling efficiency fluctuation caused by the vertical material falling of the feeding buffer cavity.

[0084] Optionally, an air outlet screen 101 is arranged at the air outlet of the fan 100, the air outlet screen 101 is a multi-section structure, and the number of screen holes 102 of the multi-section air outlet screen 101 gradually increases from top to bottom. The design of the multi-section air outlet screen 101 controls the airflow passing rate at different heights through the gradient change of the number of screen holes 102, thereby forming an airflow field with increasing wind speed from top to bottom.

[0085] A casting sand screening method is also provided, which adopts the casting sand screening machine and further includes the following steps:

[0086] S1, the casting sand raw material is conveyed to the feeding cylinder 200, and after the air flow blown into the feeding cylinder 200 by the air supply pipe of the fan 100 is pre-dispersed, the air flow disperses and carries the casting sand raw material to the screening cavity;

[0087] S2, the air flow carrying the casting sand raw material is subjected to first classification by the lower rotary cage 304, and through the coordinated action of the centrifugal force of the lower rotary cage 304 and the rising air flow, the first part of the medium sand is uniformly screened out by the inverted conical structure with gradually increasing diameter from bottom to top;

[0088] S3, the air flow carrying the medium sand and fine sand is screened by the upper rotary cage 305, the second part of the medium sand is intercepted, the intercepted second part of the medium sand falls into the sand collecting cone 306, and then is discharged through the medium sand discharge pipe 301 at the bottom of the sand collecting cone 306; the remaining fine sand is discharged from the powder outlet 402 to the fine sand cylinder 400 by means of the air flow;

[0089] S4, the fine sand in the fine sand cylinder 400 is subjected to air flow sedimentation in the fine sand cylinder 400, so that the fine sand is discharged from the fine sand outlet at the bottom of the fine sand cylinder to complete the collection.

[0090] In the S1 step, the foundry sand raw material is pre-dispersed in the airflow blown into the feeding cylinder 200 by the air supply pipe of the fan 100, which can make the foundry sand raw material be preliminarily scattered before entering the powder selecting chamber, avoid affecting the powder selecting effect due to agglomeration in the powder selecting chamber, and provide a good foundation for subsequent classification screening.

[0091] In addition, by installing the rotating shaft 207, the spiral conveying blade 206 and the like in the feeding conveying chamber 205, the crushing and tangential feeding of the feeding can be realized, the sand particles can be uniformly spread out along the radial direction of the rotating shaft 207, the uniformity of the discharging and the uniformity of the contact with the airflow can be improved, and the interference of the agglomerated blocks on the classification can be avoided.

[0092] The S2 step is the coarse screening of the medium sand classification, and the medium sand close to the critical value of the coarse sand is screened out by relying on the balance of the reverse conical structure of the lower layer rotating cage 304 and the centrifugal force, i.e., the first part of the medium sand.

[0093] The S3 step is the fine screening of the medium sand classification, and the medium sand close to the critical value of the fine sand is screened out.

[0094] In the S4 step, the airflow carrying the fine sand enters the fine sand cylinder 400 from the powder outlet 402, the space is suddenly expanded, the airflow speed is reduced, and the airflow carrying force is greatly reduced.

[0095] The foundry sand powder selecting method provided by the present application has all the beneficial effects of the foundry sand powder selecting machine, and the coarse-grained medium sand and the fine-grained medium sand are selected in sections, the particle size range of the medium sand product is accurately controlled between the lower limit of the gap of the upper layer rotating cage 305 and the upper limit of the gap of the lower layer rotating cage 304, the qualified rate of the particle size gradation is improved, and the demand of the casting process for the sand particle gradation is met.

[0096] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A casting sand screening machine, characterized by, include: The powder classifier cylinder (300) has a powder outlet chamber, a powder classifier chamber, and a material guide chamber arranged sequentially from top to bottom. The powder classifier cylinder (300) has a powder outlet (402) at its upper end, which is connected to the powder outlet chamber. The powder classifier cylinder (300) has a material guide port (309) at its lower end, which is connected to the material guide chamber. The feed cylinder (200) is located on one side of the powder classifier cylinder (300). The upper end of the feed cylinder (200) is provided with a feed inlet. The lower part of the feed cylinder (200) is connected to the guide port (309). The bottom of the feed cylinder (200) is provided with a coarse sand inlet. The side of the feed cylinder (200) away from the guide port (309) is connected to the air supply pipe of the blower (100). A fine sand cylinder (400) is located on the side of the powder selection cylinder (300). The upper part of the fine sand cylinder (400) is connected to the powder outlet (402), and a fine sand outlet is provided at the bottom of the fine sand cylinder (400). The medium sand classifier assembly includes a rotating cage and a sand collecting cone (306) disposed within the classifier chamber. The sand collecting cone (306) is located below the rotating cage and is coaxially arranged with the rotating cage. The bottom of the sand collecting cone (306) extends out of the classifier cylinder (300) through a medium sand discharge pipe (301). The rotating cage includes an upper rotating cage (305) and a lower rotating cage (304), which are coaxially arranged. The diameter of the lower rotating cage (304) gradually increases from bottom to top, while the diameter of the upper rotating cage (305) gradually decreases from bottom to top. The outlet end of the air supply pipe of the fan (100) is provided with a diversion screen plate. The diversion screen plate has a multi-segment structure, and the density of the screen holes (102) of the diversion screen plate gradually increases from top to bottom.

2. The casting sand aspirator according to claim 1, wherein The blade spacing of the lower rotating cage (304) is greater than the blade spacing of the upper rotating cage (305).

3. The foundry sand reclaimer as defined by claim 1, wherein The fan blades of the lower rotating cage (304) are arc-shaped concave fan blades, and the concave surface of the arc-shaped concave fan blades is inclined downward.

4. The foundry sand reclaimer as defined by claim 1, wherein The outer wall of the sand collecting cone (306) is provided with at least one ring of spiral guide vanes (307), and the upper end of the spiral guide vanes (307) extends to the upper end face of the sand collecting cone (306).

5. The foundry sand reclaimer as defined by claim 1, wherein The diameter of the powder selection chamber gradually increases from top to bottom, while the diameter of the material guiding chamber gradually decreases from top to bottom.

6. The foundry sand reclaimer as defined by claim 1, wherein The feed inlet is equipped with a feed assembly, which includes: The feed buffer chamber (204) is fixedly connected to the feed cylinder (200); The feeding conveying chamber (205) is located below the feeding buffer chamber (204) and is connected to the bottom of the feeding buffer chamber (204); The feeding and conveying assembly includes a rotating shaft (207) and a spiral conveying blade (206). The rotating shaft (207) is coaxial with the feeding and conveying chamber (205), and the spiral conveying blade (206) is arranged around the outer periphery of the rotating shaft (207). A drive motor is connected to the end of the rotating shaft (207).

7. The foundry sand reclaimer as defined by claim 6, wherein The feeding conveying cavity (205) is arranged at an angle with the feeding buffer cavity (204), and the feeding conveying cavity (205) faces the coarse sand port.

8. A method for selecting a casting sand, characterized by, The casting sand selecting machine as claimed in any one of claims 1-7 further comprises the following steps: S1, the casting sand raw material is conveyed to the feeding cylinder (200), and after being pre-dispersed by the air flow blown by the air supply pipe of the fan (100), the air flow scatters and carries the casting sand raw material to the selecting cavity; S2, the air flow carrying the casting sand raw material is subjected to first classification by the lower rotating cage (304), and through the coordinated action of the centrifugal force of the lower rotating cage (304) and the rising air flow, the first part of the medium sand is uniformly screened out by the inverted conical structure with gradually increasing diameter from bottom to top; S3, the air flow carrying the medium sand and fine sand is subjected to screening by the upper rotating cage (305), the second part of the medium sand is intercepted, the intercepted second part of the medium sand falls into the sand collecting cone (306), and then is discharged through the medium sand discharge pipe (301) at the bottom of the sand collecting cone (306); the remaining fine sand is discharged from the powder outlet (402) to the fine sand cylinder (400) by means of the air flow; S4, the fine sand entering the fine sand cylinder (400) is subjected to air flow sedimentation in the fine sand cylinder (400), and the fine sand is discharged from the fine sand port at the bottom of the fine sand cylinder to complete collection.

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