Foundry sand powder selecting machine and powder selecting method

Abstract

The invention provides a foundry sand powder selecting machine and a powder selecting method, and belongs to the technical field of foundry sand processing equipment.The foundry sand powder selecting machine comprises a powder selecting barrel, a feeding barrel, a fine sand barrel and a medium sand powder selecting assembly; a powder outlet cavity, a powder selecting cavity and a material guiding cavity are sequentially distributed in the powder selecting barrel from top to bottom, and a powder outlet is formed in the upper end of the powder selecting barrel and communicates with the powder outlet cavity. A material guiding opening is formed in the lower end of the powder selecting barrel body and communicates with the material guiding cavity; the medium sand powder selecting assembly comprises a rotating cage and a sand collecting cone which are arranged in the powder selecting cavity, the sand collecting cone is located below the rotating cage, and the sand collecting cone and the rotating cage are coaxially arranged; the bottom of the sand collecting cone extends out of the powder selecting barrel through a medium sand discharging pipe; the rotating cage comprises an upper-layer rotating cage and a lower-layer rotating cage which are coaxially arranged, and the diameter of the lower-layer rotating cage is gradually increased from bottom to top. According to the foundry sand powder concentrator, the problem that a traditional rotating cage is prone to being blocked is solved, three-stage grading of foundry sand is achieved, and grading precision is improved.

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 and the like, 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 exhaustion 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 for controlling the particle size of sand and stone and removing powder 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 grading 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: A 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 is communicated with the powder outlet cavity; the lower end of the powder selecting cylinder body is provided with a material guiding opening, and the material guiding opening is communicated with the material guiding cavity; A feeding cylinder body is located on one side of the powder selecting cylinder body, the upper end of the feeding cylinder body is provided with a feeding opening, the lower part of the feeding cylinder body is communicated with the material guiding opening, the bottom of the feeding cylinder body is provided with a coarse sand opening, and the side of the feeding cylinder body away from the material guiding opening is communicated with a blast pipe of a fan; A fine sand cylinder body is located on the side of the powder selecting cylinder body, the upper part of the fine sand cylinder body is communicated with the powder outlet, and the bottom of the fine sand cylinder body is provided with a fine sand opening; A medium sand powder selecting assembly comprises a rotating cage and a sand collecting cone arranged in the powder selecting cavity, the sand collecting cone is located below the rotating cage and is coaxially arranged with the rotating cage; the bottom of the sand collecting cone extends out of the powder selecting cylinder body 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.

[0006] As another embodiment of the present application, the fan spacing of the lower rotary cage is greater than the fan spacing of the upper rotary cage.

[0007] As another embodiment of the present application, the fan of the lower rotary cage is an arc-shaped concave fan, and the concave surface of the arc-shaped concave fan is inclined downward.

[0008] As another embodiment of the present application, the diameter of the upper rotary cage gradually decreases from bottom to top.

[0009] As another embodiment of the present application, the outer sidewall of the sand collecting cone is provided with at least one spiral guide vane, and the upper end of the spiral guide vane extends to the upper end surface of the sand collecting cone.

[0010] As another embodiment of the present application, 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.

[0011] As another embodiment of the present application, the feeding port is provided with a feeding assembly, and the feeding assembly comprises: a feeding buffer cavity fixedly connected with the feeding cylinder body; a feeding conveying cavity located below the feeding buffer cavity and in communication with the bottom of the feeding buffer cavity; 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 a driving motor connected with the end of the rotating shaft.

[0012] 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.

[0013] 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, and the shunt sieve plate is of a multi-section structure, and the sieve hole density of the shunt sieve plate gradually increases from top to bottom.

[0014] The casting sand powder selecting machine provided by the present application has the following advantages: compared with the prior art, the casting sand powder selecting machine of the present application cooperates the upper rotary cage and the lower rotary cage to work together with the air flow field; the lower space of the lower rotary cage is narrow, and the air flow velocity is relatively high, so that the material can be pushed to move upward quickly; as the diameter of the rotary cage increases, the space expands, and the air flow velocity tends to be stable, thereby providing a stable air flow environment for the "fine screening" of the upper rotary cage; the lower part of the lower rotary cage has a small diameter, and the centrifugal force is relatively small, so that the small-diameter medium sand can be prevented from being screened by mistake; the upper part of the lower rotary cage has a large diameter, and the centrifugal force is relatively large, so that the large-diameter medium sand that is not screened by the lower part can be effectively separated, and the large-diameter medium sand can be prevented from entering the upper rotary cage upward to interfere with the separation of the small-diameter medium sand; the problem of easy blocking of the traditional rotary cage is solved, the three-stage classification of the casting sand is realized, and the gradation accuracy is improved.

[0015] The application further provides a casting sand screening method, characterized in that the casting sand screening machine is used, and the method further comprises the following steps: S1, the casting sand raw material is conveyed to the feeding cylinder, and after being pre-dispersed by the airflow blown by the air blower, the airflow scatters the casting sand raw material and carries it to the screening cavity; S2, the airflow carrying the casting sand raw material is subjected to first classification by the lower rotating cage, and through the coordination of the centrifugal force of the lower rotating cage and the rising airflow, the first part of the medium sand is uniformly screened out by the inverted cone structure with gradually increasing diameters from bottom to top; 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 from 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 by the airflow; S4, the fine sand in the fine sand cylinder is subjected to airflow sedimentation, and the fine sand is discharged from the fine sand outlet at the bottom of the fine sand cylinder to complete the collection.

[0016] The casting sand screening method has the beneficial effects of the casting sand screening machine, and the medium sand product particle size range 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 grading qualified rate is improved, and the demand of the casting process for the sand particle size grading is met. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can be obtained without creative labor.

[0018] Figure 1 The side view of the casting sand screening machine provided by the embodiment of the application; Figure 2 The longitudinal sectional view of the casting sand screening machine provided by the first embodiment of the application; Figure 3 The longitudinal sectional view of the casting sand screening machine provided by the second embodiment of the application; Figure 2 The enlarged view of A in FIG. 4; Figure 4 The enlarged view of B in FIG. 4; Figure 2 The enlarged view of B in FIG. 4; Figure 5 The longitudinal sectional view of the casting sand screening machine provided by the second embodiment of the application; Figure 6 Partial enlarged view of the feeding conveying cavity provided by the second embodiment of the application.

[0019] In the figure: 100, fan; 101, air outlet screen; 102, screen hole; 200, feeding cylinder; 201, coarse sand discharging pipe; 202, first guide plate; 203, second guide plate; 204, feeding buffer cavity; 205, feeding conveying cavity; 206, spiral conveying blade; 207, rotating shaft; 208, sleeve; 209, crushing tooth; 300, powder selecting cylinder; 301, medium sand discharging pipe; 302, rotating cage shaft; 303, rotating cage motor; 304, lower layer rotating cage; 305, upper layer rotating cage; 306, sand collecting cone; 307, spiral guide blade; 308, medium sand outlet; 309, material guiding outlet; 400, fine sand cylinder; 401, fine sand discharging pipe; 402, powder outlet. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects of the application more clear and explicit, the application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0021] Please refer to Figures 1 to 6 The casting sand powder selecting machine provided by the application 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 outlet 402, and the powder outlet 402 is communicated with the powder discharging cavity. The lower end of the powder selecting cylinder 300 is provided with a material guiding outlet 309, and the material guiding outlet 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 inlet. The lower part of the feeding cylinder 200 is communicated with the material guiding outlet 309. The bottom of the feeding cylinder 200 is provided with a coarse sand outlet. The side of the feeding cylinder 200 away from the material guiding outlet 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 outlet 402. The bottom of the fine sand cylinder 400 is provided with a fine sand outlet. 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 the medium sand discharging pipe 301. The rotating cage comprises an upper layer rotating cage 305 and a lower layer rotating cage 304. The upper layer rotating cage 305 and the lower layer rotating cage 304 are coaxially arranged. The diameter of the lower layer rotating cage 304 gradually increases from bottom to top.

[0022] The casting sand selecting machine provided by the application can better meet the accurate three-stage classification requirements of coarse sand, medium sand and fine sand of the casting sand through the technical features of the layered arrangement of the selecting cylinder 300, the coaxial arrangement of the upper layer rotating cage 305 and the lower layer rotating cage 304 in the medium sand selecting assembly and the gradual increase of the diameter of the lower layer rotating cage 304 from bottom to top.

[0023] The feeding cylinder 200 is located on one side of the selecting cylinder 300, the feeding port at the upper end thereof is used for feeding the casting sand material, the lower part is in communication with the material guide port 309 of the selecting cylinder 300, the bottom is provided with a coarse sand port, and the side away from the material guide port 309 is in communication with the air supply pipe of the fan 100. The air flow provided by the air supply pipe of the fan 100 makes the casting sand material entering the feeding cylinder 200 move to the 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 due to the large particle size and heavy mass under the action of gravity. The medium sand, fine sand and part of the coarse sand are driven by the air flow transported by the air supply pipe of the fan 100 to move towards the material guide port 309, and then enter the selecting cylinder 300 from the material guide port 309.

[0024] The selecting cylinder 300 is sequentially provided with a powder outlet cavity, a selecting cavity and a material guide cavity from top to bottom. After the material enters the material guide cavity from the feeding cylinder 200, it will rise into the selecting cavity. The rotating cage in the selecting cavity rotates at high speed, and the casting sand particles are separated under the joint action of the air flow and the rotating cage, wherein the coarse sand is separated by the lower layer rotating cage 304 when entering the lower layer rotating cage 304, and the diameter of the lower layer rotating cage 304 gradually increases from bottom to top, so as to ensure that all the casting sand particles pass through the lower layer rotating cage 304 and improve the separation efficiency of the lower layer rotating cage 304. The fine sand particles with small particle size will rise with the air flow, enter the powder outlet cavity, and then enter the fine sand cylinder 400 through the powder outlet port 402. The lower layer rotating cage 304 and the upper layer 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.

[0025] Specifically, when the casting sand particles flow upwards from the material guide cavity into the selecting cavity, they first enter the coverage area of the lower layer rotating cage 304. Since the lower layer rotating cage 304 has a structure of "diameter increasing from bottom to top", the radial space of the lower part is narrow, and the air flow speed is relatively low when the material just enters. The medium sand particles with large particle size have a large centrifugal force due to their large mass, which is significantly greater than the air flow carrying force.

[0026] Under the centrifugal effect of high-speed rotation of the lower rotating cage 304, the first part of the medium sand with large 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 lower sand collecting cone 306. The sand collecting cone 306 is a reverse conical structure in the form of a funnel. This structure can guide the medium sand particles to gather in the center and avoid scattering outward. At the same time, the lower rotating cage 304 is designed in a reverse conical shape, which 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, avoiding blockage due to the narrow space at the lower part, and ensuring smooth flow of the material.

[0027] 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 small particle size becomes the main screening target. Although the centrifugal force of the second part of the medium sand is smaller than that of the first part of the medium sand, it is still greater than the carrying force of the airflow, and in the case that the gap between the vanes 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 and falls into the sand collecting cone 306 through the rotating cage gap and the first part of the medium sand.

[0028] Optionally, the diameter of the upper rotating cage 305 is consistent along the vertical direction. Its coverage is wider. 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, avoiding the mis-screening of the second part of the medium sand due to the change of the radial space.

[0029] The mixed first part of the medium sand and the second part of the medium sand are discharged from the powder selecting cylinder 300 through the medium sand discharge pipe 301, completing the accurate separation of the medium sand; and the fine sand particles continue to rise with the airflow due to insufficient centrifugal force, enter the powder discharge chamber, and are finally collected by the fine sand cylinder 400.

[0030] Compared with the prior art, the casting sand powder selecting machine provided by the application cooperates with the airflow field in the manner of the upper rotating cage 305 and the lower rotating cage 304. The lower space of the lower rotating cage 304 is narrow, and the airflow speed 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 speed tends to be stable, providing a stable airflow environment for the fine screening of the upper rotating cage 305. The lower part of the lower rotating cage 304 has a small diameter and a relatively small centrifugal force, which can avoid the mis-screening of the small particle size medium sand. The upper part has a large diameter and a relatively large centrifugal force, which can ensure that the medium sand with large particle size that is not screened by the lower part is effectively separated, and avoid the medium sand with large particle size from entering the upper rotating cage 305 upward to interfere with the separation of the medium sand with small particle size. The problem of easy blockage of the traditional rotating cage is solved, and three-stage classification of the casting sand is realized, improving the grading accuracy.

[0031] 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, which is communicated with a medium sand discharge pipe 301.

[0032] In some possible embodiments, referring to Figure 2 , Figure 3 and Figure 5 , the fan blade spacing of the lower layer rotating cage 304 is greater than the fan blade spacing of the upper layer rotating cage 305.

[0033] Optionally, the fan blade spacing of the lower layer rotating cage 304 is 0.3mm-0.6mm, and the fan blade 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 the medium sand is greater than 0.3mm, and the particle size range of the second part of the medium sand is 0.15mm-0.3mm.

[0034] The larger fan blade spacing of the lower layer rotating cage 304 allows the second part of the medium sand and the fine sand that meet the subsequent sorting requirements to smoothly go up along the airflow to the upper layer rotating cage 305, and will not be excessively intercepted in the lower layer, reducing the situation that the medium particles are mistakenly judged as coarse powder and returned to the mill. The larger fan blade spacing can also reduce the resistance of the airflow passing through the lower layer rotating cage 304, avoid the problem of fine sand settlement caused by airflow blockage, ensure the stable upward movement of the material and airflow, and reduce the generation of vortex.

[0035] The smaller fan blade spacing of the upper layer rotating cage 305 makes the blade have a better blocking effect on the airflow and particles, and the qualified fine sand can pass through the small spacing gap to ensure the purity of the finished product; and prevents the critical coarse particles from entering the powder outlet chamber along with the airflow, thereby ensuring the fine sand recovery rate and the accuracy of the finished product.

[0036] Optionally, the fan blades of the lower layer rotating cage 304 are arc-shaped concave fan blades, and the concave surfaces of the arc-shaped concave fan blades are inclined downward.

[0037] Due to the larger fan blade spacing of the lower layer rotating cage 304 and the downward inclination of the concave surfaces, when the medium sand and the fine sand enter the lower layer rotating cage 304, the first part of the medium sand with a larger 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 structure of the arc-shaped concave fan blades can make the stress more uniform under the same airflow and particle impact, reduce the wear of the fan blades, and prolong the service life of the rotating cage.

[0038] The design of the arc-shaped 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 more accurately classify the foundry sand and improve the classification efficiency and accuracy.

[0039] Correspondingly, the fan blades of the upper rotating cage 305 are planar fan blades.

[0040] In some possible embodiments, referring to Figure 5 The diameter of the upper rotating cage 305 gradually decreases from bottom to top.

[0041] The upper rotating cage 305 forms a conical 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 second part of the medium sand and the fine sand carried by the airflow from the lower part enter the lower part of the upper layer uniformly, ensuring uniform distribution of the airflow and the particles.

[0042] The upper rotating cage 305 rotates at high speed, and the second part of the medium sand has already started to be affected by the centrifugal force in the large-diameter area at the lower part due to its greater mass, and gradually approaches the inner wall of the fan blade, while the fine sand still maintains the upward movement trend due to its lighter 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 dual action of the centrifugal drag force and the centrifugal force thereof, and directly falls into the sand collecting cone 306 through the gap between the fan blades due to the gradually decreasing spacing between the fan blades of the upper layer.

[0043] In some possible embodiments, referring to Figure 2 and Figure 5 The outer side 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 surface of the sand collecting cone 306.

[0044] The shape and angle of the spiral guide vanes 307 are designed to enable the airflow entering the sand collecting cone 306 to make spiral motion along the surface of the vanes, so as to enhance the centrifugal force of the airflow.

[0045] After the foundry sand enters the material guiding cavity, it moves upward until it enters the guiding area formed by the spiral guide vanes 307; with the inclination angle of the vanes, the foundry sand carried by the airflow spirally moves upward along the guiding area, slowing down the material conveying speed, and at the same time, the spiral guide vanes 307 can make part of the coarse sand entering the powder selecting cylinder 300 slide along the surface of the vanes after colliding with the vanes, and then enter the feeding cylinder 200 through the material guiding port 309, and finally be discharged from the coarse sand port.

[0046] After the airflow carrying the foundry sand enters the material guiding cavity, it spirally flows upward along the gap between the spiral guide vanes 307, and the spiral guide vanes 307 guide the airflow to form an orderly spiral upward airflow, avoiding direct collision between the horizontal airflow and the vertical airflow to generate vortex.

[0047] Optionally, the rotation direction of the spiral ascending airflow is consistent with the rotation direction of the powder selection cavity rotating cage (e.g., both clockwise), and the airflow can cooperate with the centrifugal force of the rotating cage after entering the powder selection cavity, thereby enhancing the separation force on the medium sand.

[0048] Optionally, the width of the spiral guide vane 307 gradually decreases from bottom to top along the longitudinal direction to adapt to the diameter change of the material guide cavity.

[0049] In some possible embodiments, referring to Figure 2 , the diameter of the powder selection cavity gradually increases from top to bottom, and the diameter of the material guide cavity gradually decreases from top to bottom.

[0050] The coarse sand particles have large mass, and after the coarse sand enters the material guide cavity, due to the decreasing diameter of the cavity from top to bottom, the coarse sand is more easily attached to the inner wall of the material guide cavity and slides downward under the action of gravity and centrifugal force, and is discharged from the material guide port 309 to the bottom of the feeding cylinder 200, and finally discharged from the coarse sand port.

[0051] 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, and the diameter of the powder selection 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 wall of the powder selection cavity.

[0052] The large diameter at the lower end and the small diameter at the upper end of the powder selection cavity can provide sufficient space for the lower rotating cage 304, and there is enough space in the large diameter area to be thrown to the inner wall of the rotating cage fan blade, and the large gap of the lower rotating cage 304 can quickly pass the coarse and 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 rotating cage 304 will cause the gap between the rotating cage and the cavity wall to be narrow, and the coarse and medium sand will be easily accumulated on the cavity wall after passing through the rotating cage gap, causing blockage. The small diameter compresses the airflow channel, and the airflow velocity increases with the decrease of the cavity diameter. The accelerated airflow can push the fine and medium sand to the fan blades of the upper rotating cage 305. In addition, the accelerated airflow can completely capture the fine and medium sand before reaching the powder outlet cavity, thereby improving the classification accuracy.

[0053] In some possible embodiments, referring to Figure 2 and Figure 5 , the feeding port is provided with a feeding assembly, and the feeding assembly includes a feeding buffer cavity 204, a feeding conveying cavity 205, and a feeding conveying assembly; the feeding buffer cavity 204 is fixedly connected with the feeding cylinder 200; the feeding conveying cavity 205 is located below the feeding buffer cavity 204 and is in communication with the bottom of the feeding buffer cavity 204; the feeding conveying assembly includes a rotating shaft 207 and a spiral conveying vane 206, the rotating shaft 207 is coaxial with the feeding conveying cavity 205, and the spiral conveying vane 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 provided with a sleeve 208, and the sleeve 208 is located above the spiral conveying vane 206.

[0054] The casting sand first enters the feeding buffer cavity 204 when entering the feeding assembly, gradually moves to the feeding conveying cavity 205 through the feeding buffer cavity 204, and is discharged into the feeding cylinder 200 by means of the feeding conveying assembly.

[0055] The feeding buffer cavity 204 is used to receive external materials to avoid that a large amount of casting sand is suddenly impacted on the feeding cylinder 200, causing uneven discharge and affecting the powder selection precision. Since the feeding conveying cavity 205 is in communication with the bottom of the feeding buffer cavity 204, the casting sand in the feeding buffer cavity 204 enters the feeding 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 precision or waste of efficiency caused by uneven feeding.

[0056] Moreover, the spiral conveying blade 206 can break the slightly caked materials, that is, the edges of the spiral conveying blade 206 can scatter small caked sand particles when rotating, avoiding that the agglomerated sand particles are stuck in the feeding port.

[0057] The traditional feeding port is mostly open or semi-open, and the problem of material caking and blocking easily occurs. In the feeding conveying cavity 205 in the present scheme, the breaking teeth 209 can be added to the inner side wall of the feeding conveying cavity 205, and the breaking teeth 209 are in the form of a sharp structure or a spiral tooth structure. 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 materials are pushed to the breaking teeth 209 by the spiral blade during the conveying process.

[0058] When the breaking teeth 209 are in the form of a sharp structure, the sharp 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 blade continuously applies a pushing force, so that the caked material is further torn into small particles by the relative friction with the sharp teeth.

[0059] When the breaking teeth 209 are in the form of a spiral tooth structure, the tooth surface of the spiral tooth and the edge of the spiral blade form a shearing gap, and the caked material is sheared into small pieces during the pushing process. At the same time, the spiral trajectories of the adjacent breaking teeth 209 are consistent with the movement direction of the material, so that the small caked material can be ground again, ensuring that the finally output material has no obvious caking.

[0060] The conveying port is arranged at the bottom of the feeding conveying cavity 205, and the spiral conveying blade 206 drives the sand particles to the conveying port and then discharges them from the conveying port, and the direction of the conveying port is perpendicular to the axial direction of the rotating shaft 207. The spiral conveying blade 206 in the rotating state makes the direction of the discharged sand particles uniformly point to the tangential direction of the rotating shaft 207. The sand particles move forward along the spiral blade, and reach the position of the conveying port at the bottom. Since the conveying port is arranged at the bottom of the cavity, the sand particles are separated from the blade under the double actions of the continuous pushing of the spiral blade and the gravity of the sand particles, and start to move along the tangent direction of the blade under the action of the tangential force of the blade.

[0061] The uniformly dispersed sand particles enter the feeding cylinder 200 and are impacted by the airflow, and the medium sand and fine sand are carried by the airflow to 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 arranged in the feeding cylinder 200, and the guide plates are divided into two groups and 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 plate 202 is located on the side close to the air outlet of the fan 100, and the side close to the coarse sand port of the first guide plate 202 is inclined downward, and the first guide plate 202 is used for guiding the air direction while receiving the sand particles. The second guide plate 203 is located on the side close to the material guiding port 309, and the side close to the coarse sand port of the second guide plate 203 is inclined downward. The second guide plate 203 is used for changing the air direction while receiving the sand particles, and the included angle between the second guide plate 203 and the air direction is used to improve the screening efficiency of the coarse sand.

[0062] In some possible embodiments, referring to Figure 5 , 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.

[0063] 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 move forward, thereby reducing the material falling resistance. The feeding conveying cavity 205 corresponds to the coarse sand port, so that the axial direction of the rotating shaft 207 faces the coarse sand port. After the sand particles enter the cylinder in the tangential direction of the rotating shaft 207, the coarse sand quickly falls into the coarse sand port under the impact of the airflow and the interception of the first guide plate 202 and the second guide plate 203.

[0064] 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 fluctuation of the material falling efficiency caused by the vertical material falling of the feeding buffer cavity.

[0065] Optionally, an air outlet screen 101 is arranged at the air outlet of the fan 100, and 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. Through the gradient change of the number of screen holes 102, the air flow passing rate at different heights is controlled, and then an air flow field with increasing wind speed from top to bottom is formed.

[0066] A casting sand screening method is also provided, which uses the casting sand screening machine, and further includes the following steps: S1, the casting sand raw material is transported to the feeding cylinder 200, and after the air flow blown by the air supply pipe of the fan 100 pre-disperses the feeding cylinder 200, the air flow disperses the casting sand raw material and carries it to the screening 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 upward air flow, the first part of the medium sand is uniformly screened out by the inverted cone structure with gradually increasing diameter from bottom to top. S3, the air flow carrying the medium sand and fine sand is screened by the upper rotating cage 305, the second part of the medium sand is intercepted, and the intercepted second part of the medium sand falls into the sand collecting cone 306 and is then 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 outlet at the bottom of the fine sand cylinder to complete the collection.

[0067] In the S1 step, the casting sand raw material is pre-dispersed by the air flow blown by the air supply pipe of the fan 100 in the feeding cylinder 200, which can preliminarily disperse the casting sand raw material before it enters the screening cavity, avoid the influence of the agglomeration of the raw material on the screening effect in the screening cavity, and provide a good basis for subsequent classification and screening.

[0068] In addition, by installing a rotating shaft 207 and a spiral conveying blade 206 in the feeding conveying cavity 205, the crushing and tangential feeding of the feeding can be realized, the sand particles can be uniformly spread outward along the radial direction of the rotating shaft 207, the uniformity of the discharge and the uniformity of the contact with the air flow can be improved, and the interference of the agglomerated blocks with the classification can be avoided.

[0069] 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, i.e., the first part of the medium sand, is screened out by balancing the inverted cone structure of the lower rotating cage 304 and the centrifugal force.

[0070] 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.

[0071] The airflow carrying fine sand in the S4 step enters the fine sand cylinder 400 from the powder outlet 402, the space suddenly expands, the airflow speed decreases, and the airflow carrying capacity decreases significantly.

[0072] The casting sand screening method provided by the application has all the beneficial effects of the casting sand screening machine, and the coarse and fine medium sand is screened in sections, the particle size range of the medium sand product is accurately controlled between the lower limit of the gap of the upper rotating cage 305 and the upper limit of the gap of the lower rotating cage 304, the qualified rate of the particle size grading is improved, and the demand of the casting process for the sand particle size grading is met.

[0073] The above only describes the preferred embodiments of the application and is not intended to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A casting sand screening machine, characterized by, The application relates to a sand screening device, which comprises the following components: a powder selecting cylinder (300) sequentially provided with a powder discharging cavity, a powder selecting cavity and a material guiding cavity from top to bottom, wherein the upper end of the powder selecting cylinder (300) is provided with a powder discharging port (402) which is communicated with the powder discharging cavity; the lower end of the powder selecting cylinder (300) is provided with a material guiding port (309) which is communicated with the material guiding cavity; a feeding cylinder (200) located at one side of the powder selecting cylinder (300), wherein 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, and the side of the feeding cylinder (200) away from the material guiding port (309) is communicated with a blowing pipe of a fan (100); a fine sand cylinder (400) located at the side of the powder selecting cylinder (300), wherein the upper part of the fine sand cylinder (400) is communicated with the powder discharging port (402), and the bottom of the fine sand cylinder (400) is provided with a fine sand port; a medium sand powder selecting assembly, which comprises a rotating cage and a sand collecting cone (306) arranged in the powder selecting cavity, wherein 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), wherein the upper rotating cage (305) and the lower rotating cage (304) are coaxially arranged, and the diameter of the lower rotating cage (304) gradually increases from bottom to top.

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

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

4. The foundry sand reclaimer as defined by claim 1, wherein The diameter of the upper rotating cage (305) gradually decreases from bottom to top.

5. The foundry sand reclaimer as defined by claim 1, wherein At least one spiral flow guide vane (307) is arranged on the outer side wall of the sand collecting cone (306), and the upper end of the spiral flow guide vane (307) extends to the upper end surface of the sand collecting cone (306).

6. The foundry sand reclaimer as defined by claim 1, wherein 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.

7. The foundry sand reclaimer as defined by claim 1, wherein The feeding port is provided with a feeding assembly, which comprises: a feeding buffer cavity (204) fixedly connected with the feeding cylinder (200); a feeding conveying cavity (205) located below the feeding buffer cavity (204) and communicated with the bottom of the feeding buffer cavity (204); a feeding conveying assembly, which comprises a rotating shaft (207) and spiral conveying vanes (206), wherein the rotating shaft (207) is coaxial with the feeding conveying cavity (205), the spiral conveying vanes (206) are annularly arranged on the outer periphery of the rotating shaft (207), and the end of the rotating shaft (207) is connected with a driving motor.

8. The foundry sand reclaimer as defined by claim 7, 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.

9. The foundry sand reclaimer as defined by claim 1, wherein, The outlet end of the air supply pipe of the fan (100) is provided with a shunt sieve plate, the shunt sieve plate is a multi-section structure, and the sieve hole (102) density of the shunt sieve plate gradually increases from top to bottom.

10. A method for selecting a casting sand, characterized by, The casting sand selecting machine as claimed in any one of claims 1-9 is also used, and 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 airflow blown by the air supply pipe of the fan (100), the airflow scatters and carries the casting sand raw material to the selecting cavity; S2, the airflow 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 airflow, the first part of the medium sand is uniformly screened out by the inverted cone structure with gradually increasing diameter from bottom to top; S3, the airflow carrying the medium sand and fine sand is screened 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 through the airflow from the powder outlet (402) to the fine sand cylinder (400); S4, the fine sand entering the fine sand cylinder (400) is subjected to airflow sedimentation in the fine sand cylinder (400), and the fine sand is discharged from the fine sand outlet at the bottom of the fine sand cylinder to complete collection.

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