A continuous sand mixer for steam turbine shell casting and a processing technology thereof

Abstract

The present application relates to steam turbine shell casting equipment technical field, and disclose a kind of steam turbine shell casting with continuous sand mixer and its processing technology, the steam turbine shell casting with continuous sand mixer includes sand mixing tank and raw sand tank, also includes airflow classification mechanism and sand mixing mechanism, sand mixing mechanism is set in sand mixing tank, the raw sand in raw sand tank is classified after being classified by airflow classification mechanism to granularity, first, coarse-grained raw sand is injected into sand mixing tank, then, fine-grained raw sand is injected into sand mixing tank, and classified sand mixing is carried out by sand mixing mechanism;Airflow classification mechanism includes classification cylinder;The steam turbine shell casting with continuous sand mixer and its processing technology, before raw sand is injected into sand mixing tank, coarse-grained raw sand and fine-grained raw sand are divided to raw sand by airflow classification, and the way of coarse-grained raw sand sand mixing first and then fine-grained raw sand sand mixing makes that sand mixing efficiency is improved and binder distribution is more uniform.

Description

Technical Field

[0001] This invention relates to the field of steam turbine casing casting equipment technology, specifically to a continuous sand mixer for steam turbine casing casting and its processing technology. Background Technology

[0002] A steam turbine, also known as a steam engine, is a rotary steam power unit. The turbine's structure includes a casing, main shaft, impeller, moving blades, and coupling. The turbine casing is typically cast using molding sand, and a continuous sand mixer is the device used for molding sand preparation. The continuous sand mixer ensures the uniform mixing of all components in the molding sand (including sand, binder, additives, and water) and effectively coats the sand grains with the binder. As a key piece of equipment in the turbine casing casting process, the continuous sand mixer is a crucial factor in controlling molding sand quality and cost. Continuous sand mixers include roller-type mixers, which primarily use rolling and rubbing actions; blade-type mixers, which primarily use mixing actions; and rotor-type mixers, which combine rubbing and mixing actions, etc.

[0003] Existing continuous sand mixers for turbine casing casting typically involve directly injecting filtered raw sand into the mixer for mixing. This processing method has the following drawbacks: Due to the significant difference in particle size among the raw sand particles, simultaneously injecting raw sand with large differences in particle size into the mixer results in inconsistent crushing progress between coarse and fine raw sand particles. The mixer needs to operate at a high power continuously, leading to reduced mixing efficiency. Furthermore, simultaneous mixing of coarse and fine raw sand particles causes the fine raw sand particles to complete crushing earlier, thus having more time to adhere to more liquid material, ultimately resulting in uneven distribution of binder within the molding sand.

[0004] Therefore, in order to solve the above-mentioned technical problems in the existing technology, a continuous sand mixer for casting steam turbine shell and its processing technology are proposed. Summary of the Invention

[0005] This invention provides a continuous sand mixer for casting steam turbine casings and its processing technology. It features the advantage of separating coarse and fine-grained raw sand through airflow classification before the raw sand is injected into the mixing tank, and improving mixing efficiency and achieving more uniform binder distribution by mixing the coarse-grained raw sand first and then the fine-grained raw sand. This solves the problems mentioned in the background art, where existing technologies simultaneously inject raw sand with large differences in particle size into the sand mixer, resulting in inconsistent crushing progress between coarse and fine-grained raw sand, requiring the sand mixer to operate at high power continuously, leading to reduced mixing efficiency and uneven binder distribution in the molding sand.

[0006] This invention provides the following technical solution: a continuous sand mixer for casting a steam turbine casing, comprising a sand mixing tank and a raw sand tank, and further comprising an airflow classification mechanism and a sand mixing mechanism. The sand mixing mechanism is disposed inside the sand mixing tank. The raw sand in the raw sand tank is classified by particle size by the airflow classification mechanism. First, coarse raw sand is injected into the sand mixing tank, and then fine raw sand is injected into the sand mixing tank. The sand is then classified and mixed by the sand mixing mechanism.

[0007] The airflow classification mechanism includes a classification cylinder, a feed pipe connected to the original sand tank is provided at the central axis of the classification cylinder, a secondary airflow inlet is provided at the side wall of the classification cylinder, a first motor is provided at the top of the classification cylinder, and an impeller is connected to the output shaft of the first motor through a coupling, and the impeller is located on the upper side of the feed pipe.

[0008] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, the sand mixing tank is provided with two first inlets and a first outlet, the bottom of the classifying cylinder is provided with a coarse raw sand outlet, the top of the classifying cylinder is provided with a fine raw sand outlet, and the coarse raw sand outlet and the fine raw sand outlet are respectively connected to the two first inlets.

[0009] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, the sand mixing mechanism includes a rotating shaft disposed in the sand mixing tank, a rotor disposed on the rotating shaft, and a second motor disposed on the sand mixing tank, the second motor being used to drive the rotating shaft to rotate.

[0010] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, wherein: the rotating shaft and the rotor are both symmetrically arranged in two forms based on the central axis of the sand mixing tank;

[0011] The sand mixing mechanism also includes a turntable rotatably disposed inside the sand mixing tank, with two rotating shafts rotatably disposed on the turntable. The output shaft of the second motor is connected to the center of the turntable via a coupling. Gears are disposed on both rotating shafts, and a gear ring is disposed inside the sand mixing tank. Both gears mesh with the gear ring.

[0012] As an optional solution of the continuous sand mixer for casting a steam turbine shell according to the present invention, it further includes an adjustment mechanism, which includes two high-power sliding rheostats and a first test component. The two high-power sliding rheostats are respectively connected to the first motor and the second motor through wires, and the first test component is set in the original sand tank.

[0013] Before the raw sand is conveyed from the raw sand tank to the grading cylinder, the content of coarse and fine raw sand in the raw sand tank is tested by the first testing component, and the first motor and the second motor are controlled to operate at different power according to the test results.

[0014] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, the high-power sliding rheostat includes a ceramic casing, on which sliding plates are slidably disposed, and connecting rods are disposed on the two sliding plates.

[0015] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, the first test component includes a wheel, a hydraulic cylinder and a third motor. The wheel is rotatably disposed inside the original sand tank. The hydraulic cylinder is used to drive the wheel to descend, and the third motor is used to drive the wheel to rotate.

[0016] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, the first test component further includes a slide block slidably disposed in the original sand tank, the connecting rod is connected to the slide block, and the wheel is connected to the output shaft of the hydraulic cylinder;

[0017] A rotating seat is rotatably mounted on the slide block, and a sliding groove is formed on the rotating seat. The wheel is slidably mounted in the sliding groove, and the wheel is elastically connected to the rotating seat by a spring. A force sensor is installed in the sliding groove.

[0018] As an optional embodiment of the continuous sand mixer for casting a steam turbine casing according to the present invention, wherein: a second test component is provided inside the sand mixing tank, and the structure of the second test component is the same as that of the first test component.

[0019] This invention also provides the following technical solution: a processing technology for a continuous sand mixer for casting steam turbine casings, comprising the following steps:

[0020] S1. After the raw sand is continuously injected into the raw sand tank according to the rated mass, the hydraulic cylinder and the third motor drive the wheel to move downward in a spiral motion to flatten the raw sand in the raw sand tank. The hydraulic cylinder and the third motor stop running when the force sensor is triggered. Then the raw sand is injected into the classifying cylinder through the feed pipe. Air is blown into the classifying cylinder through the secondary air inlet, and the impeller is driven to rotate by the first motor, so that the raw sand is classified into coarse raw sand and fine raw sand under the centrifugal action.

[0021] Furthermore, as the content of coarse sand particles in the original sand increases and the gaps between the sand and gravel increase, the distance the wheel descends is relatively reduced. In turn, the resistance of the high-power sliding rheostat connected to the first motor is changed, which reduces the power of the first motor and causes the grading point to descend.

[0022] S2. The coarse raw sand separated by the classifying cylinder is continuously injected into the mixing tank through the coarse raw sand outlet. At the same time, liquid material is injected into the mixing tank. The two rotors are driven by the second motor to mix the sand. As the coarse raw sand content increases, the resistance of the second motor is changed by the high-power sliding rheostat connected to the second motor, thereby increasing the power of the second motor.

[0023] S3. During step S2, when the gap between materials in the mixing tank is reduced to the rated threshold by the second test component, the fine raw sand separated by the classifier is continuously injected into the mixing tank through the fine raw sand outlet for mixing.

[0024] The present invention has the following beneficial effects:

[0025] 1. The continuous sand mixer for turbine casing casting and its processing technology involve classifying the raw sand into coarse and fine particles through airflow classification before injecting it into the mixing tank. Then, a graded sand mixing process is adopted: first, coarse raw sand and a portion of liquid material are injected for mixing, followed by fine raw sand and a portion of liquid material for further mixing. During the graded sand mixing process, the power of the mixing mechanism can be relatively reduced. On the one hand, this allows for reasonable power allocation, preventing excessive further crushing of fine raw sand after it has already been sufficiently crushed, thus improving mixing efficiency. On the other hand, uniform mixing after the coarse raw sand has been sufficiently crushed and is close to the fine raw sand ensures a more consistent particle size, resulting in consistent binder adhesion and a more uniform distribution of binder in the molding sand.

[0026] 2. The continuous sand mixer for turbine casing casting and its processing technology, considering the complex composition of raw materials and the large variation in raw sand particle size, also includes an adjustment mechanism based on the specific content of coarse and fine raw sand particles. Based on the measurement of the coarse and fine raw sand content in the raw sand tank by the first testing component, when there is a large amount of coarse raw sand, the grading point of the airflow grading mechanism will automatically decrease to separate more coarse raw sand. Simultaneously, the operating power of the sand mixing mechanism will automatically increase to better handle the influx of more coarse raw sand.

[0027] 3. The continuous sand mixer for casting the steam turbine casing and its processing technology, during the sand mixing process, the height of the original sand mixed with coarse raw sand can be monitored through the second test component, thereby determining whether the coarse raw sand has been crushed to a sufficient degree and selecting the node for injecting fine raw sand. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0029] Figure 2This is a schematic cross-sectional view of the overall structure of the present invention.

[0030] Figure 3 For the present invention Figure 2 A magnified view of a portion of point A in the middle.

[0031] Figure 4 This is a cross-sectional structural diagram of the original sand tank and airflow classification mechanism of the present invention.

[0032] Figure 5 For the present invention Figure 4 A magnified view of a portion of point B in the middle.

[0033] Figure 6 This is a schematic diagram of the structure of the sliding rheostat of the present invention.

[0034] Figure 7 This is an exploded structural diagram of the sand mixing mechanism of the present invention.

[0035] Figure 8 This is an exploded structural diagram of the adjusting mechanism of the present invention.

[0036] In the diagram: 100, mixing tank; 110, first feed inlet; 120, first discharge outlet; 130, first pneumatic conveyor; 140, first feed pipe; 150, second pneumatic conveyor; 160, second feed pipe; 170, second feed inlet; 200, raw sand tank; 210, third feed inlet; 220, third pneumatic conveyor; 230, third feed pipe; 300, air classifier; 310, classifier cylinder; 320, feed pipe; 330, secondary air inlet; 340, coarse raw sand outlet; 350, fine raw sand outlet; 360, first motor; 370 400. Impeller; 410. Sand mixing mechanism; 420. Rotor; 430. Second motor; 440. Turntable; 450. Gear; 460. Gear ring; 500. Adjustment mechanism; 510. High-power sliding rheostat; 511. Ceramic housing; 512. Sliding plate; 513. Terminal block; 514. Metal rod; 520. Connecting rod; 530. First test assembly; 531. Wheel; 532. Hydraulic cylinder; 533. Third motor; 534. Slide; 535. Rotary seat; 536. Slide groove; 537. Spring; 538. Force sensor; 600. Second test assembly. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] To achieve particle classification of raw sand, coarse raw sand is first crushed and mixed at a higher power in the mixing tank 100, and then fine raw sand is injected for mixing at a lower power. This allows for a reasonable distribution of the operating power of the mixing machine, improves efficiency, and makes the binder more evenly distributed in the molding sand. Example 1 is proposed.

[0040] Please see Figures 1-4 A continuous sand mixer for casting steam turbine casing includes a sand mixing tank 100 and a raw sand tank 200, as well as an airflow classification mechanism 300 and a sand mixing mechanism 400. The sand mixing mechanism 400 is disposed inside the sand mixing tank 100. After the raw sand in the raw sand tank 200 is classified by the airflow classification mechanism 300, coarse raw sand is first injected into the sand mixing tank 100, and then fine raw sand is injected into the sand mixing tank 100. The sand is then classified and mixed by the sand mixing mechanism 400.

[0041] The airflow classification mechanism 300 includes a classification cylinder 310, a feed pipe 320 connected to the original sand tank 200 is provided at the central axis of the classification cylinder 310, a secondary airflow inlet 330 is provided at the side wall of the classification cylinder 310, a first motor 360 is provided at the top of the classification cylinder 310, and the output shaft of the first motor 360 is connected to an impeller 370 through a coupling, and the impeller 370 is located on the upper side of the feed pipe 320.

[0042] The sand mixing tank 100 is provided with two first feed inlets 110 and first discharge outlets 120. The bottom of the classifying cylinder 310 is provided with a coarse raw sand outlet 340, and the top of the classifying cylinder 310 is provided with a fine raw sand outlet 350. The coarse raw sand outlet 340 and the fine raw sand outlet 350 are respectively connected to the two first feed inlets 110.

[0043] Specifically, the mixing tank 100 is provided with a second feed inlet 170, the raw sand tank 200 is provided with a third feed inlet 210 and a third pneumatic conveyor 220, the third pneumatic conveyor 220 is connected to the feed pipe 320 through the third feed pipe 230, the coarse raw sand outlet 340 is provided with a first pneumatic conveyor 130, the first pneumatic conveyor 130 is connected to one of the first feed inlets 110 through the first feed pipe 140, and the fine raw sand outlet 350 is provided with a second pneumatic conveyor 150, the second pneumatic conveyor 150 is connected to another first feed inlet 110 through the second feed pipe 160.

[0044] In this embodiment: at the lower outlet of the raw sand tank 200, the raw sand is pneumatically conveyed through the third feed pipe 230 into the feed pipe 320 via the operation of the third pneumatic conveyor 220, and then sprayed from the feed pipe 320 into the classifying cylinder 310. The feed pipe 320 is distributed along the central axis of the classifying cylinder 310. After the raw sand is sprayed out, on the one hand, airflow can be blown in through the secondary airflow inlet 330, which is at an angle to the circular tangent of the classifying cylinder 310, connected to the air pump; on the other hand, the first motor 360 drives the impeller 370 to rotate at high speed.

[0045] Impeller 370 is a compound bidirectional centrifugal impeller. As it rotates, a negative pressure zone is created at the bottom. Air enters through the bottom of impeller 370 and exits through fine-particle raw sand outlet 350. The airflow rotates upwards, exhibiting velocity components in both the axial and circumferential directions. The centrifugal force of the airflow classification mechanism 300 causes coarse-particle raw sand to fall through coarse-particle raw sand outlet 340, while fine-particle raw sand is ejected through fine-particle raw sand outlet 350, carried by the airflow. The specific working principle of the airflow classification mechanism 300 is explained using conventional technical means and will not be elaborated upon here.

[0046] Then, the first pneumatic conveyor 130 pneumatically conveys coarse raw sand through the first feed pipe 140 and the first feed port 110 on the right side into the mixing tank 100 for mixing. The second feed port 170 is used to inject liquid material composed of binder, additives, and water. A valve can be installed at the first discharge port 120. After the second motor 430 drives the mixing for a certain period of time, the second pneumatic conveyor 150 pneumatically conveys fine raw sand through the second feed pipe 160 and the first feed port 110 on the left side into the mixing tank 100 for continued mixing. At this time, the power of the second motor 430 can be reduced.

[0047] Finally, the first discharge port 120 is opened to discharge the mixed molding sand.

[0048] Example 2

[0049] To improve the traditional sand mixing method of rotor 420, and to mix raw sand and liquid materials in sand mixing tank 100, Example 2 is proposed.

[0050] This embodiment is an improvement upon Embodiment 1. For details, please refer to [link / reference]. Figures 1-7 The sand mixing mechanism 400 includes a rotating shaft 410 disposed in the sand mixing tank 100, a rotor 420 disposed on the rotating shaft 410, and a second motor 430 disposed on the sand mixing tank 100, the second motor 430 being used to drive the rotating shaft 410 to rotate.

[0051] Both the rotating shaft 410 and the rotor 420 are symmetrically arranged based on the central axis of the sand mixing tank 100.

[0052] The sand mixing mechanism 400 also includes a turntable 440 rotatably disposed inside the sand mixing tank 100. Two rotating shafts 410 are rotatably disposed on the turntable 440. The output shaft of the second motor 430 is connected to the center of the turntable 440 through a coupling. Gears 450 are disposed on both rotating shafts 410. A gear ring 460 is disposed inside the sand mixing tank 100. Both gears 450 mesh with the gear ring 460.

[0053] In this embodiment, rotor 420 has a grinding and mixing function, and two rotors 420 are provided to improve the sand mixing efficiency. The operation of the second motor 430 drives the turntable 440 to rotate, causing the two shafts 410 and the two rotors 420 to perform circular motion for sand mixing. Simultaneously, because the two gears 450 mounted on the two shafts 410 mesh with the gear ring 460, the two gears 450 also drive the two shafts 410 and the two rotors 420 to rotate. This further improves the sand mixing effect.

[0054] Example 3

[0055] Since the raw sand used for casting the outer shell of the steam turbine is composed of complex materials with large particle size differences, in order to further improve the effect of graded sand mixing, it is necessary to adjust the grading point of the airflow grading mechanism 300 and the initial power of the second motor 430 according to the amount of coarse and fine raw sand in the raw sand. Therefore, Example 3 is proposed.

[0056] This embodiment is an improvement upon Embodiment 2. For details, please refer to [link / reference]. Figures 1-6 It also includes an adjustment mechanism 500, which includes two high-power sliding rheostats 510 and a first test component 530. The two high-power sliding rheostats 510 are respectively connected to the first motor 360 and the second motor 430 through wires. The first test component 530 is set inside the original sand tank 200.

[0057] Before the raw sand is conveyed from the raw sand tank 200 to the grading cylinder 310, the content of coarse and fine raw sand in the raw sand tank 200 is tested by the first test component 530, and the first motor 360 and the second motor 430 are controlled to operate at different power according to the test results.

[0058] The high-power sliding rheostat 510 includes a ceramic housing 511, a slider 512 slidably disposed on the ceramic housing 511, and a connecting rod 520 disposed on the two sliders 512;

[0059] Specifically, the ceramic housing 511 is also provided with a terminal block 513 and a metal rod 514, and an insulating wire is sleeved on the terminal block 513.

[0060] In this embodiment: Besides controlling their gear positions, the power of the first motor 360 and the second motor 430 is affected by the current at their rated gear positions. After a rated mass of raw sand is injected into the raw sand tank 200 through the third feed port 210, according to the function of the first testing component 530, the more coarse-grained raw sand there is, the lower the power of the first motor 360 becomes, the weaker the centrifugal effect, the lower the grading point, and the more coarse-grained raw sand and fewer fine-grained raw sand are separated. Conversely, the power of the second motor 430 increases to cope with the injection of more coarse-grained raw sand.

[0061] Specifically, such as Figure 6 As shown, each of the two ceramic housings 511 has four connection points: a, b, c, and d. For the high-power sliding rheostat 510 on the left, the negative terminal of the power supply is connected to b, and c is connected to the first motor 360 through a wire. The first motor 360 is then connected to the positive terminal of the power supply (the wire is not shown in the figure). As the distance of the slider 512 on the left decreases with the descent of the connecting rod 520, it is equivalent to the slider 512 moving upwards relatively, which will relatively weaken the current passing through the first motor 360 and reduce the power.

[0062] For the high-power sliding rheostat 510 on the right, the negative terminal of the power supply is connected to a, and d is connected to the second motor 430 through a wire. The second motor 430 is then connected to the negative terminal of the power supply (the wire is not shown in the figure). As the distance of the sliding plate 512 on the right decreases with the descent of the connecting rod 520, it is equivalent to the sliding plate 512 moving upwards relatively, which will increase the current and power of the first motor 360.

[0063] Example 4

[0064] To control the relative decrease in the descent distance of the connecting rod 520 due to the increase in coarse-grained raw sand of the rated mass, Example 4 is proposed;

[0065] This embodiment is an improvement upon embodiment three. For details, please refer to [link / reference]. Figures 1-8 The first test component 530 includes a wheel 531, a hydraulic cylinder 532 and a third motor 533. The wheel 531 is rotatably set inside the original sand tank 200. The hydraulic cylinder 532 is used to drive the wheel 531 to descend, and the third motor 533 is used to drive the wheel 531 to rotate.

[0066] The first test component 530 also includes a slide block 534 that is slidably disposed inside the original sand jar 200, a connecting rod 520 connected to the slide block 534, and a wheel 531 connected to the output shaft of the hydraulic cylinder 532;

[0067] A rotating seat 535 is rotatably mounted on the slide seat 534. A groove 536 is provided on the rotating seat 535. A wheel 531 is slidably mounted in the groove 536. The wheel 531 is elastically connected to the rotating seat 535 by a spring 537. A force sensor 538 is provided in the groove 536.

[0068] In this embodiment: after the rated mass of raw sand is injected into the raw sand tank 200, the hydraulic cylinder 532 moves the slide 534 down as a whole, and the third motor 533 moves the rotating seat 535 and the wheel 531 to rotate, so that the wheel 531 slowly spirals down, spreading the raw sand in the raw sand tank 200 and then continuing to apply pressure until the wheel 531 is subjected to the reaction force and rises against the elastic force of the spring 537 and touches the force sensor 538. The force sensor 538 can transmit signals through an external PLC controller or other means to control the hydraulic cylinder 532 and the third motor 533 to stop running.

[0069] The specific distance that the slide 534 descends depends on the amount of raw sand at the rated mass. The more coarse raw sand there is, the larger the gap will be. When the wheel 531 finally stops, the greater the height of the raw sand on the lower side, the less the relative distance that the slide 534 descends.

[0070] Example 5

[0071] To enable the mixing tank 100 to intelligently control the timing of fine-particle raw sand injection based on the decrease in the height of the raw sand during coarse-particle mixing, Example 5 is proposed.

[0072] This embodiment is an improvement upon embodiment four. For details, please refer to [link / reference]. Figures 1-8 The mixing tank 100 is equipped with a second test component 600, the structure of which is the same as that of the first test component 530.

[0073] In this embodiment, the second test component 600 operates on the same principle as the first test component 530, although the parameter settings may differ. After the coarse raw sand and corresponding liquid are injected, they stop on the surface of the raw sand through a structure identical to that of the wheel 531. During the sand mixing process, when the coarse raw sand is broken to a certain extent, the overall height decreases. At this time, the structure corresponding to the force sensor 538 detects the loss of contact, which indicates that fine raw sand has been injected.

[0074] The structure corresponding to the force sensor 538 here can also be a distance sensor, which can be used as a more accurate basis for judgment by judging the height of the structure corresponding to the wheel 531.

[0075] Example 6

[0076] Please see Figures 1-8A processing technology for a continuous sand mixer used in the casting of steam turbine casings includes the following steps:

[0077] S1. After the raw sand is continuously injected into the raw sand tank 200 according to the rated mass, the hydraulic cylinder 532 and the third motor 533 drive the wheel 531 to move downward in a spiral motion to flatten the raw sand in the raw sand tank 200. The hydraulic cylinder 532 and the third motor 533 stop running when the force sensor 538 is triggered. Then the raw sand is injected into the classifying cylinder 310 through the feed pipe 320. Air is blown into the classifying cylinder 310 through the secondary air inlet 330, and the impeller 370 is driven to rotate by the first motor 360, so that the raw sand is classified into coarse raw sand and fine raw sand under the centrifugal action.

[0078] Furthermore, as the content of coarse sand particles in the original sand increases and the gaps between the sand and gravel increase, the distance that the wheel 531 descends is relatively reduced. In turn, the resistance of the high-power sliding rheostat 510 connected to the first motor 360 is changed, thereby reducing the power of the first motor 360 and causing the grading point to descend.

[0079] S2. The coarse raw sand particles classified by the classifying cylinder 310 are continuously injected into the mixing tank 100 through the coarse raw sand particle outlet 340. At the same time, liquid material is injected into the mixing tank 100. The two rotors 420 are driven by the second motor 430 to mix the sand. As the coarse raw sand particle content increases, the resistance of the high-power sliding rheostat 510 connected to the second motor 430 is changed to increase the power of the second motor 430.

[0080] S3. During step S2, when the gap between materials in the mixing tank 100 is reduced to the rated threshold by the second test component 600, the fine raw sand separated by the classifier 310 is continuously injected into the mixing tank 100 through the fine raw sand outlet 350 for mixing.

[0081] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A continuous sand mixer for casting a steam turbine shell, comprising a sand mixing tank (100) and a raw sand tank (200), characterized in that: It also includes an airflow classification mechanism (300) and a sand mixing mechanism (400). The sand mixing mechanism (400) is disposed in the sand mixing tank (100). After the raw sand in the raw sand tank (200) is classified by the airflow classification mechanism (300), coarse raw sand is first injected into the sand mixing tank (100), and then fine raw sand is injected into the sand mixing tank (100). The sand is then classified and mixed by the sand mixing mechanism (400). The airflow classification mechanism (300) includes a classification cylinder (310), a feed pipe (320) connected to the original sand tank (200) is provided at the central axis of the classification cylinder (310), a secondary airflow inlet (330) is provided at the side wall of the classification cylinder (310), a first motor (360) is provided at the top of the classification cylinder (310), the output shaft of the first motor (360) is connected to an impeller (370) through a coupling, and the impeller (370) is located on the upper side of the feed pipe (320).

2. A continuous sand mixer for casting a steam turbine shell according to claim 1, characterized in that: The mixing tank (100) is provided with two first feed inlets (110) and a first discharge outlet (120). The bottom of the classifying cylinder (310) is provided with a coarse raw sand outlet (340), and the top of the classifying cylinder (310) is provided with a fine raw sand outlet (350). The coarse raw sand outlet (340) and the fine raw sand outlet (350) are respectively connected to the two first feed inlets (110).

3. A continuous sand mixer for casting a steam turbine shell according to claim 2, wherein: The sand mixing mechanism (400) includes a rotating shaft (410) disposed in the sand mixing tank (100), a rotor (420) disposed on the rotating shaft (410), and a second motor (430) disposed on the sand mixing tank (100), the second motor (430) being used to drive the rotating shaft (410) to rotate.

4. A continuous sand mixer for casting a steam turbine shell according to claim 3, wherein: Both the rotating shaft (410) and the rotor (420) are symmetrically arranged in two places based on the central axis of the sand mixing tank (100); The sand mixing mechanism (400) further includes a turntable (440) rotatably disposed inside the sand mixing tank (100), and two rotating shafts (410) rotatably disposed on the turntable (440). The output shaft of the second motor (430) is connected to the center of the turntable (440) through a coupling. Gears (450) are provided on both rotating shafts (410), and a gear ring (460) is provided inside the sand mixing tank (100). Both gears (450) mesh with the gear ring (460).

5. A continuous sand mixer for casting a steam turbine casing according to claim 4, characterized in that: It also includes an adjustment mechanism (500), which includes two high-power sliding rheostats (510) and a first test component (530). The two high-power sliding rheostats (510) are respectively connected to the first motor (360) and the second motor (430) via wires. The first test component (530) is disposed inside the original sand tank (200). Before the raw sand is conveyed from the raw sand tank (200) to the grading cylinder (310), the content of coarse and fine raw sand in the raw sand tank (200) is tested by the first test component (530), and the first motor (360) and the second motor (430) are controlled to operate at different power according to the test results.

6. A continuous sand mixer for casting a steam turbine casing according to claim 5, characterized in that: The high-power sliding rheostat (510) includes a ceramic housing (511), on which a sliding plate (512) is slidably disposed, and a connecting rod (520) is disposed on the two sliding plates (512).

7. A continuous sand mixer for casting a steam turbine casing according to claim 6, characterized in that: The first test component (530) includes a wheel (531), a hydraulic cylinder (532) and a third motor (533). The wheel (531) is rotatably disposed inside the original sand tank (200). The hydraulic cylinder (532) is used to drive the wheel (531) to descend, and the third motor (533) is used to drive the wheel (531) to rotate.

8. A continuous sand mixer for casting a steam turbine casing according to claim 7, characterized in that: The first test assembly (530) further includes a slide block (534) slidably disposed in the original sand tank (200), the connecting rod (520) is connected to the slide block (534), and the wheel (531) is connected to the output shaft of the hydraulic cylinder (532); A rotating seat (535) is rotatably mounted on the slide (534). A groove (536) is provided on the rotating seat (535). The wheel (531) is slidably mounted in the groove (536). The wheel (531) is elastically connected to the rotating seat (535) by a spring (537). A force sensor (538) is provided in the groove (536).

9. A continuous sand mixer for casting a steam turbine casing according to claim 8, characterized in that: The mixing tank (100) is equipped with a second test component (600), the structure of which is the same as that of the first test component (530).

10. The processing technology of a continuous sand mixer for casting a steam turbine casing according to claim 9, characterized in that, Includes the following steps: S1. After continuously injecting raw sand into the raw sand tank (200) according to the rated mass, the hydraulic cylinder (532) and the third motor (533) drive the wheel (531) to make a downward spiral motion to flatten the raw sand in the raw sand tank (200) until the force sensor (538) is triggered and the hydraulic cylinder (532) and the third motor (533) stop running. Then, the raw sand is injected into the classifying cylinder (310) through the feed pipe (320). Airflow is blown into the classifying cylinder (310) through the secondary airflow inlet (330), and the impeller (370) is driven to rotate by the first motor (360) so that the raw sand is classified into coarse raw sand and fine raw sand under centrifugal action. Furthermore, as the content of coarse sand particles in the original sand increases and the gaps between the sand and gravel increase, the distance that the wheel (531) descends is relatively reduced. In turn, the resistance of the high-power sliding rheostat (510) connected to the first motor (360) is changed, which weakens the power of the first motor (360) and causes the grading point to decrease. S2. The coarse raw sand separated by the classifying cylinder (310) is continuously injected into the mixing tank (100) through the coarse raw sand outlet (340). At the same time, liquid material is injected into the mixing tank (100). The two rotors (420) are driven by the second motor (430) to mix the sand. As the coarse raw sand content in the raw sand increases, the resistance of the second motor (430) is changed by the high-power sliding rheostat (510) connected to the second motor (430) to increase the power of the second motor (430). S3. During step S2, when the gap between materials in the mixing tank (100) is reduced to the rated threshold by the second test component (600), the fine raw sand separated by the classifier (310) is continuously injected into the mixing tank (100) through the fine raw sand outlet (350) for mixing.

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