Foundry sand screening device

Abstract

The present invention provides a foundry sand screening device, comprising a horizontally arranged screening drum, both ends of the screening drum are rollingly supported by supporting wheels, the wheel core of the supporting wheel is in the same horizontal direction as the drum core of the screening drum, one end of the screening drum is connected to a power drive unit, the power drive unit drives the screening drum to rotate around the drum core, a middle section of the screening drum wall is provided with sand-passing holes for allowing small-size materials to pass through and retaining large-size materials, striking tooth units are arranged on the inner wall of the screening drum to avoid the sand-passing holes, the striking tooth units are arranged at intervals and form striking tooth rows along a spiral line, one end of the screening drum is a material receiving end for sand-containing mixture, and the other end is a discharge end, a screening drum is sleeved on the outside of the drum section where the sand-passing holes are arranged, the screening drum is provided with holes for allowing ash to pass through and retain sandy materials or for allowing small-size sand to pass through and retain large-size sand, and the sand discharge end of the screening drum and the casting discharge end of the screening drum are in the same direction.

Description

Technical Field

[0001] The invention relates to casting process equipment, in particular to equipment for screening and collecting ash or large and small sand or steel ball castings mixed in sand. Background Art

[0002] At present, in the workpiece casting process, there are landfill sand and molding sand in the casting sand box. In the coated sand casting and lost foam casting processes, there are coated sand molding sand or lost foam waste and ash. How to sort and recycle the effective sand in the sand box is extremely important. In addition, the castings are small particles such as steel balls. After the casting is completed, it is easy to cause the steel balls and sand to mix together, so it is necessary to separate the castings from the sand.

[0003] In the coated sand casting process, the coated sand shell is placed in the sand box and filled with external sand or insulation sand, and then the casting liquid is poured. After molding and cooling, the steel ball casting is separated and taken out, and the insulation sand is kept for backup. When picking up the steel balls manually, the sand box must be cooled to a temperature that the personnel can bear. This not only takes a long time to wait, but also has low sorting efficiency and may cause missed picking. The sand is constantly turned during the picking process, and dust cannot be avoided. To this end, the applicant has provided a corresponding solution, namely, a "sorting system" (application number 201910869685.6), wherein the casting and the sand separation screen are separated by a first and a second screen (20, 30) elastically supported on a frame (10) and having mesh sizes different from each other. Based on the plate screen structure adopted in the design, which occupies a large space and produces a certain amount of noise, the applicant has also designed a "screening device" (document number CN 111085420 A), which comprises a rotating shaft, on which at least one cylindrical or conical screen cylinder is sleeved, one end of the screen cylinder having a high bottom and the other end having a low bottom, the inner end of the connecting rod is connected to the rotating shaft, and the outer end is connected to the cylinder wall of the screen cylinder to form a detachable connection. It is difficult to increase the rotational torque when the rotating parts are arranged obliquely. At the same time, since the rotating shaft, as a torque transmission part, has to bear the additional bending moment of the load, the screening volume is limited, resulting in limited screening efficiency. In the early stage of screening, a large amount of material arrives in the screen drum. Due to the setting of the connecting rod, the flow of the material is blocked, and the screening efficiency is difficult to improve.

[0004] At present, the screening devices for sorting according to particle size are nothing more than the above two solutions, namely, screen type and screen drum type. The screen drum structure is selected, and the inclined arrangement of the rotating shaft is one solution. The other type is a solution in which the rotating shaft is horizontal and the screening drum is suspended, such as the name "multi-stage cylindrical screen" (document number CN 209061532 U). The screening section arranged in a suspended manner has not only limited screening volume, but also extremely limited load capacity. For screening steel castings and foundry sand, it cannot meet the requirements of large screening quantities. Summary of the invention

[0005] The purpose of the present invention is to provide a foundry sand screening device to improve the screening efficiency of castings and sand.

[0006] To achieve the above-mentioned purpose, the technical solution provided by the present invention is: a foundry sand screening device, characterized in that: it includes a horizontally arranged screening drum, both ends of the screening drum are rollingly supported by supporting wheels, the wheel core of the supporting wheel is in the same horizontal direction as the drum core of the screening drum, one end of the screening drum is connected to a power drive unit, the power drive unit drives the screening drum to rotate around the drum core, a middle section of the screening drum wall is provided with sand holes for allowing small-size materials to pass through and retaining large-size materials, a striking tooth unit is arranged on the inner wall of the screening drum to avoid the sand holes, the striking tooth units are arranged at intervals and form striking tooth rows along a spiral line, one end of the screening drum is a material receiving end for the sand-containing mixture, and the other end is a discharge end, a screening drum is sleeved on the outside of the drum section where the sand holes are arranged, the screening drum is provided with holes for allowing ash to pass through and retain sandy materials or for passing small-size sand and retaining large-size sand, and the sand discharge end of the screening drum and the casting discharge end of the screening drum are in the same direction.

[0007] The screening drum in the present invention is both the main component of the screening body and the bearing component. Due to its own tubular shape with simple supports at both ends, it has considerable bending resistance, so not only the diameter can be made larger but also the length can be selected to be longer. At the same time, due to the setting of the striking tooth unit, it provides a guarantee for the complete separation and thorough diversion of the casting and sand. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 , 2 is a three-dimensional structural diagram of a sorting system using the present invention;

[0009] Figure 3 It is a schematic diagram of the structure of the present invention;

[0010] Figure 4 , 5 6 Yes Figure 3 A local enlarged schematic diagram in FIG.

[0011] Figure 7 This is a front view of the receiving end of the screening cylinder. DETAILED DESCRIPTION

[0012] Combination Figure 1 , 2As an important part of the casting system, the separation process of castings and sand is very important. It is not only the closing operation of the previous casting process, but also the preparatory stage for the start of the next casting process. For example, the sand box tilting device 1 connected upstream of the screening device implements the sand box dumping operation, and the empty sand box is prepared for the next packing. The screening operation of castings and sand is started by this device. If the casting is a large piece, it should be taken out and then screened. If it is a micro-sphere or small granular casting, the casting and sand can be screened together.

[0013] The sand material screened by the device is transported and stored in the sand bin 2 to prepare for the next sand box packing and sand burying operation.

[0014] The foundry sand screening device provided by the present invention comprises a horizontally arranged screening drum 10, both ends of the screening drum 10 are supported by support wheels 20 for rolling, the wheel core of the support wheel 20 is in the same horizontal direction as the drum core of the screening drum 10, one end of the screening drum 10 is connected to a power drive unit, the power drive unit drives the screening drum 10 to rotate around the drum core, a sand passing hole 11 for passing small-size materials and intercepting large-size materials is arranged on the middle wall of the screening drum 10, and a sand passing hole 11 for passing small-size materials and intercepting large-size materials is arranged on the inner wall of the screening drum 10. The striking tooth units 121 that avoid each other through the sand holes 11 are arranged at intervals and form a striking tooth row 12 along the spiral line. One end of the screening drum 10 is the receiving end of the sand-containing mixture, and the other end is the discharge end. The outer part of the drum section where the sand holes 11 are arranged is covered with a screen drum 30. The screen drum 30 is arranged with holes for passing ash and intercepting sandy materials or passing small-sized sand and intercepting large-sized sand. The sand discharge end of the screen drum 30 is the same direction end as the casting discharge end of the screening drum 10. The outermost screen drum 30 is a waist drum shape with a large diameter in the middle section and small diameters at both ends.

[0015] Combination Figure 1 , 23. The sand box A arrives at the sand box tilting device 1 and is tilted by the sand box tilting device 1. The castings and sand arrive at the receiving end of the screening drum 10 in a mixed state. The power drive unit drives the screening drum 10 to rotate around the drum core. The agglomerated or connected castings and sand, runner parts and microballs and sand groups collide with each other and are also struck by the striking tooth unit 121. The castings, sand, runners, microballs and sand groups will be completely dispersed, and then the castings, sand and dust particles will be separated through the sand holes 11 in turn. The sand and dust particles that arrive in the screening drum 30 will be screened again through the holes on the screening drum 30. In the present invention, the screening drum 10 is both a bearing component and a screening body. Its cylindrical shape ensures that it has a reliable bending bearing capacity, and its cylinder cavity has enough space to accommodate materials, which ensures a significant improvement in screening efficiency. As for the screening cylinder 10, since it has reliable bending resistance, a thicker wall thickness can be selected to ensure its wear resistance to increase its service life. The increase in wall thickness is more conducive to improving its bending strength, which is also more conducive to the fixation of the externally mounted screening cylinder 30.

[0016] The power drive unit includes a motor, which can drive the screening drum 10 to rotate by meshing the gear 16 with the gear ring 17 arranged on the screening drum 10. The motor is not shown in the figure, and the support wheel 20 can also be driven to rotate to drive the screening drum 10 to rotate.

[0017] It should be briefly explained that the above-mentioned solution of horizontal arrangement of the screening drum 10 includes the following situations:

[0018] The screening drum 10 can be a conical cylinder. In this case, the horizontal arrangement of the cylinder core can also realize the pushing of materials from the receiving end to the discharging end. The screening drum 10 can also be a cylindrical cylinder. In this case, the cylinder core can be arranged horizontally or inclined at a small angle. It goes without saying that the inclined arrangement is convenient for the discharge of materials. When arranged horizontally, the striking tooth unit 121 set on the cylinder wall can be used to push the casting to the discharging end. When a cylindrical cylinder is selected and the cylinder core is arranged horizontally, it is simplest to cooperate with the rolling support of the roller support wheel 20. Of course, when the screening drum 10 is a cylindrical cylinder and the cylinder core is arranged at a small angle, the offset of axial force should be considered. In addition, when the screening drum 10 is a cylindrical drum and the drum core is horizontal, a built-in annular baffle 15 is provided at the port of the material receiving end of the screening drum 10, and the middle hole of the annular baffle 15 is a feed port, which is connected to the quicksand trough 1A of the sand box tilting device 1, so as to prevent the material that has just entered the screening drum 10 and is too close to the drum mouth from being discharged from the drum mouth.

[0019] As a preferred solution, a ferrule 13 is provided at the position near both ends of the screening drum 10, and the outer peripheral surface of the ferrule 13 is in rolling cooperation with the wheel surface of the supporting wheel 20, and axial limiting rollers 20A and 20B are provided on the end surface side of the ferrule 13. This solution completely solves the axial displacement problem of the screening drum 10 and the external screening drum 30, not only including the axial stringing when the drum core is arranged horizontally, but also solves the problem of axial displacement of the drum core of the screening drum 10 arranged obliquely at a small angle, which is extremely important when the amount of screening material is large. It should be noted that, in specific implementation, it is ideal to arrange the axial limiting rollers 20A and 20B at the lowest position of the ferrule 13, and the wheel core of the axial limiting rollers 20A and 20B can be located in the plumb direction, under the cooperation of the axial limiting rollers 20A and 20B and the axial end surface of the ferrule 13, that is, the wheel surface of the axial limiting rollers 20A and 20B and the ferrule 13 form a rolling cooperation, and the axial displacement of the screening drum 30 is limited.

[0020] In order to implement the ideal solution that the screening drum 10 is a cylindrical drum with a horizontally arranged drum core, and at the same time ensure timely and efficient discharge of the castings, the striking tooth units 121 are arranged at intervals and along the spiral line to form a striking tooth row 12. The spiral line of the striking tooth row 12 is arranged in a consistent direction, which not only plays a role in supporting the material to achieve the function of throwing and dispersing, but also has the function of pushing the material to the discharge end. In addition, it also improves the rigidity and strength of the screening drum 10.

[0021] As a preferred solution, the spiral inclination angle of the striking tooth row 12 arranged in the middle section where the sand-passing hole 11 is located is smaller than the spiral inclination angle of the striking tooth row 12 on the smooth wall section of the rear section.

[0022] A more preferred solution is that the spiral inclination angle of the striking tooth row 12 arranged in the middle section where the sand passing hole 11 is located is smaller than the spiral inclination angle of the striking tooth row 12 on the smooth wall section of the rear section, and the spiral inclination angle of the striking tooth row 12 in the front section of the middle section where the sand passing hole 11 is located is smaller than the spiral inclination angle of the striking tooth row 12 on the smooth wall section of the rear section.

[0023] It can be seen from the above technical solution that when the striking tooth row 12 is arranged along the length of the inner wall of the screening cylinder 10, the striking tooth row 12 can be divided into three sections. The middle section corresponds to the cylinder section with the sand hole 11, the front section is the cylinder section between the material receiving end and the middle section, and the rear section is the downstream section of the cylinder section where the sand hole 11 is located. The striking tooth row 12 in the front section has the functions of striking and dispersing the material and pushing the material to the middle section at an appropriate speed. The striking tooth row 12 in the middle section ensures that all materials are thoroughly dispersed and all materials larger than the aperture of the sand hole 11 are intercepted by the sand hole 11. At the same time, all materials smaller than the aperture of the sand hole 11 leave the screening cylinder 10 and arrive at the outside of the screening cylinder 10, and further screening is carried out. The large particle materials intercepted by the sand hole 11 arrive at the discharge end in time and are discharged under the rapid rotation and pushing action of the striking tooth row 12 in the rear section, thereby significantly improving the screening efficiency.

[0024] In order to realize the material receiving and discharging of the screen drum 30, the first solution is that the screen drum 30 is a conical drum, and the end with the lower bottom of the drum is the sand discharge end. The taper does not need to be too large, and 3 to 5 degrees or slightly larger is fine; the second solution is that the screen drum 30 is a cylindrical drum, and a sand discharge guide plate 33 is provided on the inner wall of the drum.

[0025] In specific implementation, the sand discharge guide blades 33 can be arranged in a manner of standing on the cylinder wall, and the length of the blades is in the shape of a spiral blade. The sand discharge guide blades 33 can be arranged in a dispersed manner and their rotation directions are consistent with each other. In this scheme, the sand discharge guide blades 33 are arranged in the shape of a spiral blade, which is conducive to the discharge of sand to the end of the screen cylinder 30 when the screen cylinder 30 is a cylindrical cylinder and the cylinder core is horizontal. The sand discharge guide blades 33 also have a flipping effect on the material, which is beneficial to the separation of sand and ash or the rapid separation of fine sand and coarse sand. In addition, since the wall thickness of the screen cylinder 30 does not need to be too thick, the arrangement of the sand discharge guide blades 33 can also increase the rigidity and strength of the screen cylinder 30.

[0026] It has been explained in the foregoing that the screening drum 10 has an excellent load-bearing capacity, which provides a reliable connection basis for fixing the external screening drum 30. The specific preferred solution is:

[0027] The sieve drum 30 includes a primary sieve drum 31 and a secondary sieve drum 32 sleeved on the outside of the primary sieve drum 31. The primary sieve drum 31 has primary sieve drum holes 311 for allowing small-sized sand to pass through and retaining large-sized sand. The secondary sieve drum 32 has secondary sieve drum holes 321 for allowing ash particles to pass through and retaining small-sized sand. The sand outlet end of the primary sieve drum 31 extends to the outside of the sand outlet end of the secondary sieve drum 32.

[0028] The purpose of setting the primary sieve drum 31 and the secondary sieve drum 32 is to screen out sands of different particle sizes. Since the present invention is applicable to coated sand casting, the particle size of the coated sand as molding sand is smaller than that of ordinary external insulation sand. In order to screen and utilize it in a graded manner, the primary sieve drum 31 can intercept ordinary external sand and allow the coated sand molding sand to pass through, and then the secondary sieve drum 32 can intercept the coated sand molding sand and collect it for utilization. The aperture of the secondary sieve drum through hole 321 of the secondary sieve drum 32 is smaller than the particle size of the coated sand molding sand, and the casting ash particles continue to pass through the secondary sieve drum through hole 321 and are then collected by the ash hopper. The above-mentioned first-level screen drum 31 is inside the second-level screen drum 32, so the sand discharge end of the first-level screen drum 31 should be the end of the cylinder on its downstream side. An appropriate distance is reserved between the sand discharge ends of the first-level screen drum 31 and the second-level screen drum 32, which provides a leisurely arrangement space for arranging the quicksand guide groove 50 at the ends of the first-level screen drum 31 and the second-level screen drum 32, so as to realize the connection between the sand discharge end of the screen drum 30 and one end of the quicksand guide groove 50. When there is no need to screen ordinary shape sand and coated sand, the screen drum 30 can be provided with only one first-level screen drum 31.

[0029] The screening drum 10 is provided with radially arranged support rods 40, the outer ends of the support rods 40 are nut tubes or screws, and the screws or nut tubes matching the nut tubes or screws at the outer ends of the support rods 40 fasten the screening drum 30 at the joint between the two.

[0030] More specific implementation methods are as follows Figure 5 As shown, a scheme of a sieve cylinder 30 consisting of a primary sieve cylinder 31 and a secondary sieve cylinder 32 is provided, and a primary support rod 41 is radially arranged on the screening cylinder 10, and the outer end of the primary support rod 41 is a nut tube or a screw, and the screw or nut tube at the inner end of the secondary support rod 42 that cooperates with the nut tube or screw at the outer end of the primary support rod 41 fastens the primary sieve cylinder 31 to the junction of the primary support rod 41 and the secondary support rod 42, and the outer end of the secondary support rod 42 is a nut tube or a screw that cooperates with a nut or a bolt 43 and fixes the secondary sieve cylinder 32 at the connection between the two.

[0031] Figure 5In the embodiment, the inner end of the primary support rod 41 is welded and fixed on the screening drum 10, the rod length direction of the primary support rod 41 is consistent with the radial direction of the screening drum 10, the outer end of the primary support rod 41 is set to be nut-shaped, and a boss 411 can be added at the end to increase the end area and facilitate the opening of a threaded hole with a larger aperture, and the screw at the inner end of the secondary support rod 42 can be screwed into the nut hole at the outer end of the primary support rod 41. The rod length of the primary support rod 41 is consistent with the radius difference between the primary screen drum 31 and the screening drum 10, so the primary screen drum 31 can be reliably fixed on the screening drum 10 in the form of a cylindrical drum. The outer periphery of the sub-drum 10 and the setting of the boss 411 provide a suitable supporting area for supporting the inner wall of the primary sieve drum 31, which can avoid deformation of the primary sieve drum 31; in addition, the inner end of the secondary support rod 42 has been screwed to the primary support rod 41 and fixed, and the outer end of the secondary support rod 42 is the same as the outer end of the primary support rod 41. At this time, bolts are used to connect the outer end of the secondary support rod 42 to firmly fix the wall of the secondary sieve drum 32. The length of the secondary support rod 42 is determined with reference to the length of the primary support rod 41 to maintain the cylindrical shape of the secondary sieve drum 32.

[0032] Since the material in the sand box contains a large amount of dust components, serious dust will inevitably occur during the dumping and screening process. If effective treatment is not applied, it is difficult to meet environmental protection requirements. For this reason, the present invention has made a corresponding design, that is, the middle section of the screening cylinder 10 with sand holes 11 and the screening cylinder 30 are placed in the box body 60, the upper part of the box body 60 is connected to the dust removal pipeline, and the box body 60 has a hole on the box wall corresponding to the cylinder end for the screening cylinder 10 to pass through, and the power drive mechanism, the support wheel 20, and the axial limiting rollers 20A and 20B are located outside the box body 60.

[0033] The above scheme is to impose constraints on the ash source part and implement collection for treatment, while the power, transmission and mechanical matching components are placed outside the box 60. The advantage of adding the box 60 is that it can not only realize the collection and treatment of dust, but also effectively reduce the noise in the workplace. In addition, it also protects the operation safety of the power, transmission and mechanical matching components. It should be noted that the hole part of the box 60 corresponding to the box wall of the cylinder end for the screening cylinder 10 and the screening cylinder 10 can be matched with a small gap, and it is sufficient to ensure frictionless rotation between the screening cylinder 10 and the box 60 to prevent smoke and dust from overflowing.

[0034] like Figure 1 , 2 As shown in , 3, the opening and closing cylinder door 14 is arranged in an empty cover type at the discharge end of the casting of the screening cylinder 10, and a casting outlet is arranged between the opening and closing cylinder door 14 and the lower end edge of the cylinder mouth of the screening cylinder 10. The so-called empty cover type arrangement means that the opening and closing cylinder door 14 and the screening cylinder 10 are not directly connected, but there is a gap between them to ensure the normal rotation of the screening cylinder 10, and the opening and closing cylinder door 14 is only covered at the cylinder port of the screening cylinder 10 to prevent dust from overflowing.

[0035] like Figure 1 As shown, a maintenance observation window 61 is provided on the side of the box body 60 corresponding to the position of the screen drum 30 , and an operation opening 62 for transferring the ash box 70 is provided at the lower part of the box body 60 .

[0036] Figure 2 , 3 As shown, the first and second quicksand guide grooves 51 and 52 corresponding to the first screen drum 31 and the second screen drum 32 are led out from the opening 63 on the box body 60, and a dust blocking curtain is set at the opening 63. The second quicksand guide groove 52 directly guides the outer shape sand to the elevator 3 set at the side, and the elevator 3 lifts and transports it to the sand bin 2.

[0037] The screening device provided by the present invention can effectively separate castings and sand, and collect dust in time. In addition, the sand box does not need to be cooled to a temperature that employees can tolerate during screening. According to actual measurements, the temperature of the screened sand when it reaches the primary and secondary sand guide grooves 51 and 52 is still 300°C. It can be seen that the screening timing is significantly earlier than manual operation, and the screening process effectively cools the material.

Claims

1. A foundry sand screening device, characterized in that: The invention comprises a horizontally arranged screening drum (10), wherein both ends of the screening drum (10) are rollingly supported by support wheels (20), the wheel core of the support wheel (20) and the horizontal direction of the drum core of the screening drum (10) are consistent, one end of the screening drum (10) is connected to a power drive unit, the power drive unit drives the screening drum (10) to rotate around the drum core, a sand hole (11) for passing small-size materials and intercepting large-size materials is arranged on the middle wall of the screening drum (10), and a sand hole (11) is arranged on the inner wall of the screening drum (10) The striking tooth units (121) are arranged at intervals and along a spiral line to form a striking tooth row (12); one end of the screening cylinder (10) is a material receiving end for the sand-containing mixture, and the other end is a discharge end; a screening cylinder (30) is sleeved on the outside of the cylinder section where the sand holes (11) are arranged; the screening cylinder (30) is provided with holes for allowing ash to pass through and retaining sandy materials or for allowing small-sized sand to pass through and retaining large-sized sand; the sand discharge end of the screening cylinder (30) and the casting discharge end of the screening cylinder (10) are in the same direction; The screening drum (10) is provided with a ring (13) at a position close to both ends, the outer peripheral surface of the ring (13) is in rolling cooperation with the wheel surface of the supporting wheel (20), and axial limiting rollers (20A, 20B) are provided on the end surface side of the ring (13); The middle section of the screening cylinder (10) on which the sand holes (11) are arranged and the screening cylinder (30) are placed in a box (60); the upper part of the box (60) is connected to the dust removal pipeline; a hole is provided on the wall of the box (60) corresponding to the cylinder end for the screening cylinder (10) to pass through; and a power drive mechanism, a supporting roller (20), and axial limiting rollers (20A, 20B) are located outside the box (60); The axial limiting rollers (20A, 20B) are arranged at the lowest position of the ferrule (13); the wheel cores of the axial limiting rollers (20A, 20B) are located in the plumb direction; and the wheel surfaces of the axial limiting rollers (20A, 20B) form a rolling fit with the ferrule (13); All striking tooth rows (12) are arranged in the same direction, or the spiral inclination angle of the striking tooth row (12) arranged in the middle section where the sand hole (11) is located is smaller than the spiral inclination angle of the striking tooth row (12) on the smooth wall section of the rear section, and the spiral inclination angle of the striking tooth row (12) in the front section is smaller than the spiral inclination angle of the striking tooth row (12) on the smooth wall section of the rear section.

2. The foundry sand screening device according to claim 1, characterized in that: When the screening cylinder (10) is a cylindrical cylinder and the cylinder core is horizontal, a built-in annular baffle (15) is provided at the port of the material receiving end of the screening cylinder (10), and the middle hole of the annular baffle (15) is a material feed port.

3. The foundry sand screening device according to claim 1, characterized in that: The screen cylinder (30) is a conical cylinder, and the lower end of the cylinder bottom is the sand discharge end.

4. The foundry sand screening device according to claim 1, characterized in that: When the screen drum (30) is a cylindrical body and lies horizontally, sand discharge guide plates (33) are arranged on the inner wall of the screen drum (30). The sand discharge guide plates (33) are arranged at intervals and along a spiral line. The spiral line direction of the sand discharge guide plates (33) is consistent with the spiral line direction of the striking tooth row (12).

5. The foundry sand screening device according to claim 1, characterized in that: The outermost screen drum (30) is in the shape of a waist drum with a large diameter in the middle section and small diameters at both ends.

6. The foundry sand screening device according to claim 1, 2, 3 or 4, characterized in that: The sieve drum (30) comprises a primary sieve drum (31) and a secondary sieve drum (32) sleeved on the outside of the primary sieve drum (31); the primary sieve drum (31) has primary sieve drum holes (311) for allowing small-sized sand to pass through and retaining large-sized sand; the secondary sieve drum (32) has secondary sieve drum holes (321) for allowing ash particles to pass through and retaining small-sized sand; and a sand outlet end of the primary sieve drum (31) extends to the outside of the sand outlet end of the secondary sieve drum (32).

7. The foundry sand screening device according to claim 1, 2, 3 or 4, characterized in that: The screening cylinder (10) has radially arranged support rods (40), the outer ends of the support rods (40) are nut tubes or screws, and the screws or nut tubes that match the nut tubes or screws at the outer ends of the support rods (40) fasten the screening cylinder (30) at the joint between the two.

8. The foundry sand screening device according to claim 1, 2, 3 or 4, characterized in that: The sand outlet end of the screen drum (30) is connected to one end of the quicksand guide groove (50).

9. The foundry sand screening device according to claim 1, characterized in that: The screening cylinder (10) is provided with a radially arranged primary support rod (41), the outer end of the primary support rod (41) is a nut tube or a screw, the screw or nut tube at the inner end of the secondary support rod (42) matched with the nut tube or the screw at the outer end of the primary support rod (41) fastens the primary screening cylinder (31) to the joint of the primary support rod (41) and the secondary support rod (42), the nut tube or the screw at the outer end of the secondary support rod (42) cooperates with a nut or a bolt (43) to fix the secondary screening cylinder (32) at the joint between the primary support rod (41) and the secondary support rod (42).

10. The foundry sand screening device according to claim 1, 2, 3 or 4, characterized in that: The casting discharge end of the screening cylinder (10) is provided with an openable and closeable cylinder door (14) in an empty cover type, and a casting outlet is provided between the openable and closeable cylinder door (14) and the lower end edge of the cylinder mouth of the screening cylinder (10).

11. The foundry sand screening device according to claim 8, characterized in that: A maintenance observation window (61) is provided on the side of the box body (60) at a position corresponding to the location of the screen drum (30), and an operation opening (62) for transferring and receiving an ash box is provided at the bottom of the box body (60).

12. The foundry sand screening device according to claim 6, characterized in that: The first and second quicksand guide grooves (51, 52) corresponding to the first-stage screen drum (31) and the second-stage screen drum (32) are led out from an opening (63) provided on the box body (60), and a dust blocking curtain is provided at the opening (63).

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