A foundry sand box for producing large size mine mill high strength wear resistant castings

Abstract

This invention discloses a casting sand box for producing high-strength wear-resistant castings for large mining mills, relating to the field of metal casting technology. It includes a support frame, a movable slide table mounted on the support frame, a lifting platform mounted on the bottom of the movable slide table, and a magnetic clamp fixed to the lower end of the lifting platform. The magnetic clamp also includes a magnetic cover and a stationary iron core disposed inside the magnetic cover. This invention solves the problem that, to remove the lifting device, a clearance groove must be excavated in advance at the corresponding position in the sand trough. After the core mold is in place, the hook is manually removed, or the steel rope is tied, the clearance groove is backfilled with sand. However, the excavation and secondary backfilling of the clearance groove easily disrupt the original uniform compaction of the sand trough, leading to a decrease in local forming accuracy and uneven structural strength. This, in turn, increases the probability of quality problems such as sand erosion, box collapse, and dimensional deviations during casting, adversely affecting the forming quality and finished product qualification rate of the wear-resistant castings.

Description

Technical Field

[0001] This invention relates to the field of metal casting technology, specifically to a casting sand box for producing high-strength, wear-resistant castings for large mining mills. Background Technology

[0002] Casting is a metal processing method in which a substance that is liquid at room temperature but soon solidifies is poured into a mold of a specific shape and allowed to solidify. Casting is one of the earliest metal heat treatment processes mastered by mankind, with a history of about 6,000 years. The technology has reached a fairly high level. The material being cast is mostly metal that was originally solid but was heated to a liquid state, while the material of the mold can be sand, metal, or even ceramic. Depending on the requirements, the methods used will also be different. Casting is one of the basic processes of modern mechanical manufacturing industry. Therefore, the development of the casting industry marks a country's production strength.

[0003] For example, the casting box of the wear-resistant casting with publication number CN113020575A can be adjusted. The bidirectional adjustment can further improve the machining accuracy of the casting components on the wear-resistant casting. The connecting parts help improve the stability of the casting box during processing, thereby preventing the casting plate from shaking during processing. Furthermore, the setting of the vacuum adsorption tank can vacuum adsorb the wear-resistant casting to prevent it from shaking during the processing of the casting components, thereby improving the machining accuracy. However, the existing casting process for producing high-strength wear-resistant castings for large mining mills still has some shortcomings.

[0004] In the casting production process of high-strength wear-resistant castings for large mining mills, after the sand trough in the sand box is molded, a core mold made of pure iron or low-carbon steel needs to be accurately placed into the sand trough. Currently, the industry generally adopts the conventional method of lifting with hooks or binding with steel ropes for the hoisting operation of such large core molds: first, the core mold is hoisted to the top of the sand box with a lifting tool, and then slowly lowered into the sand trough. In order to remove the lifting tool, a relief groove for the lifting tool needs to be excavated in advance at the corresponding position of the sand trough. After the core mold is in place and the hooks are removed with manual assistance or the steel ropes are tied, the relief groove is backfilled with sand. However, the excavation and secondary backfilling of the relief groove can easily damage the original uniform compaction of the sand trough, resulting in a decrease in the local molding accuracy and uneven structural strength of the sand trough. This increases the probability of quality problems such as sand flushing, box collapse, and dimensional deviations during the casting process, which has an adverse effect on the molding quality and finished product qualification rate of the wear-resistant castings.

[0005] To address the aforementioned issues, there is an urgent need for innovative design of the existing casting sand box used for producing high-strength wear-resistant castings for large mining mills. Summary of the Invention

[0006] This invention addresses the problem of overly simplistic solutions in existing technologies by providing a significantly different approach. Specifically, the invention aims to provide a casting sand box for producing high-strength, wear-resistant castings for large-scale mining mills. This addresses the issue raised in the background technology where, to remove the lifting equipment, a clearance groove needs to be excavated in the corresponding location of the sand trough beforehand. After the core mold is in place and the lifting hook is manually removed or the steel rope is secured, the clearance groove is backfilled with sand. However, the excavation and secondary backfilling of the clearance groove easily disrupt the original uniform compaction of the sand trough, leading to a decrease in local molding accuracy and uneven structural strength. This, in turn, increases the probability of quality problems such as sand erosion, box collapse, and dimensional deviations during casting, adversely affecting the molding quality and finished product qualification rate of the wear-resistant castings.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a casting sand box for producing high-strength wear-resistant castings for large mining mills, comprising a support, a movable slide table mounted on the support, a lifting platform mounted on the bottom of the movable slide table, and a magnetic clamp fixed to the lower end of the lifting platform, wherein the magnetic clamp further comprises a magnetic cover;

[0008] A stationary iron core set inside the magnetic shield;

[0009] Multiple sets of excitation coils wound on a stationary iron core;

[0010] An energy storage piston cylinder fixed to the top of the magnetic shield;

[0011] A pressure rod that moves synchronously with the energy storage piston cylinder via a connecting piece;

[0012] A constant-pressure short-circuit assembly is set up one-to-one with each group of excitation coils;

[0013] The energy storage piston cylinder includes an auxiliary suction device fixed at its end, a piston rod slidably passing through the cylinder body, and a first return spring sleeved on the outside of the piston rod.

[0014] The atmospheric pressure short-circuit assembly includes a short-circuit plate connected in parallel with the excitation coil and an atmospheric pressure button arranged corresponding to the short-circuit plate. The bottom of the atmospheric pressure button is provided with a contact end that is electrically connected to the short-circuit plate.

[0015] Preferably, the movable slide is slidably mounted on the top crossbeam of the bracket, the fixed end of the lifting platform is fixedly connected to the lower end face of the movable slide, the top of the magnetic clamp is fixedly connected to a fixing buckle, and the telescopic end of the lifting platform is fixedly connected to the fixing buckle, so as to drive the magnetic clamp to drive the magnetically attracted core mold to complete the horizontal translation and vertical lifting and positioning.

[0016] Preferably, the short-circuit board is provided with a contact, the contact is electrically connected to the contact end, the bottom of the constant pressure button is fixed with a bidirectional butterfly block, a telescopic rod that slides through the housing is provided below the bidirectional butterfly block, and a second reset spring is also provided at the bottom of the constant pressure button.

[0017] Preferably, the multiple sets of excitation coils are connected in series with a series line. The input terminal of the first excitation coil is connected to the positive terminal of the power supply through a power line, and the output terminal of the last excitation coil is connected to the negative terminal of the power supply through a power line. The head and tail of each set of excitation coils are electrically connected to the corresponding short-circuit board through parallel jumpers.

[0018] Preferably, the end face of the piston rod facing the auxiliary attractor is a magnetic metal surface. When the auxiliary attractor is energized synchronously with the excitation coil, the auxiliary attractor attracts the piston rod and compresses the first return spring to complete energy storage.

[0019] Preferably, after the auxiliary suction device is independently de-energized, the first reset spring resets and pushes the piston rod to extend, which drives the pressure rod to move towards the normal pressure button through the connecting piece. The pressure rod sequentially presses and triggers each group of normal pressure buttons, making the corresponding short circuit board electrically connected to the normal pressure button, and short-circuiting the corresponding excitation coil segment by segment to achieve linear attenuation of magnetic force, so that the core mold falls smoothly into the sand trough with its own weight and the magnetic force dissipation.

[0020] Preferably, the end of the pressure rod facing the normal pressure button is a trapezoidal guide end, and its rear section is a rectangular limiting section. The trapezoidal guide end is in contact with the top surface of the normal pressure button to achieve a gradual and smooth compression triggering of the normal pressure button.

[0021] Preferably, when the pressure rod moves axially, it sequentially presses and triggers multiple sets of constant pressure buttons, and the pressing and triggering stroke of a single set of constant pressure buttons matches the short-circuit action stroke of the corresponding excitation coil one by one.

[0022] Preferably, the end of the stationary iron core is fixed with a pole piece, and the magnetic attraction working surface of the pole piece is flush with the end face of the magnetic shield to improve the magnetic attraction stability of the core mold after the excitation coil is energized.

[0023] Preferably, the multiple sets of excitation coils are arranged in an equidistant array along the axial direction of the stationary iron core. The constant pressure button and short-circuit plate corresponding to each set of excitation coils are arranged in a linear array on the moving path of the pressure rod to realize the sequential short circuit of the excitation coils. The excitation coils in the two magnetic clamps adopt a relative winding method, that is, the excitation coil in the left clamp is wound clockwise and the excitation coil in the right clamp is wound counterclockwise.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention uses electromagnetic attraction to lift and transport large core molds. The entire process does not require physical connection between the core mold and mechanical lifting tools such as hooks and steel ropes. It also eliminates the need to excavate a relief groove in the sand trough beforehand and the need for manual backfilling after removing the lifting tools. This fundamentally eliminates the damage to the original uniform compaction of the sand trough caused by the excavation of the relief groove and secondary backfilling. It avoids the problems of localized decrease in the forming accuracy and uneven structural strength of the sand trough, effectively reducing the probability of quality defects such as sand flushing, box collapse, and dimensional deviation during the casting process. It significantly improves the forming quality and finished product qualification rate of high-strength wear-resistant castings for large mining mills. At the same time, through the linear demagnetization design of multiple sets of series excitation coils short-circuited segment by segment, the core mold is smoothly placed as its own weight and magnetic force dissipate, avoiding damage to the sand trough structure caused by the impact of the core mold falling, and further ensuring the forming integrity of the sand trough.

[0026] 2. This invention utilizes a purely mechanical linkage structure—using an auxiliary attractor in the energy storage piston cylinder and a first reset spring to drive the piston rod in conjunction with the pressure rod—to achieve sequential triggering of the atmospheric pressure short-circuit component and segmented short-circuiting of the corresponding excitation coil. The entire core mold demagnetization and placement process requires no additional power drive, complex electronic control programs, or manual assistance. The entire process, from magnetic fixation and transfer alignment to stable placement and magnetic release, is fully automated through mechanical linkage, significantly simplifying the hoisting process for large core molds, reducing manual operation intensity and on-site safety risks, and significantly improving the efficiency of casting production. Furthermore, the modular design of the series-connected segmented excitation coils allows for adjustment of the number of coil segments and winding turns to match the hoisting requirements of core molds of different weights and sizes. The opposing double-clamp structure achieves opposite magnetic pole arrangement through the coil winding direction design, maximizing the superimposed magnetic force and increasing scenario adaptability and production versatility. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the casting bracket of the present invention.

[0028] Figure 2 This is a schematic diagram of the casting bracket of the present invention from another angle.

[0029] Figure 3 This is a schematic diagram of the lifting platform of the present invention.

[0030] Figure 4 This is a schematic diagram of the lifting platform of the present invention from another angle.

[0031] Figure 5 This is a schematic diagram of the magnetic clamp of the present invention.

[0032] Figure 6 This is a schematic diagram of the internal components of the magnetic clamp of the present invention.

[0033] Figure 7This is an external sectional view of the magnetic clamp of the present invention.

[0034] Figure 8 This is a schematic diagram of the electromagnetic energy storage component of the present invention.

[0035] Figure 9 This is a schematic diagram of the atmospheric pressure short-circuit component of the present invention.

[0036] Figure 10 This is a schematic diagram of the internal structure of the constant pressure button of the present invention.

[0037] Figure 11 This is a schematic diagram of the segmented winding structure of the present invention.

[0038] In the diagram: 1. Bracket; 2. Movable slide; 3. Lifting platform; 4. Magnetic clamp; 5. Magnetic cover; 6. Electrode; 7. Fixing buckle; 8. Static iron core; 9. Energy storage piston cylinder; 901. Auxiliary attractor; 902. Piston rod; 903. First return spring; 10. Pressure rod; 11. Power cord; 12. Short circuit board; 1201. Contact; 13. Constant pressure button; 1301. Bidirectional butterfly block; 1302. Contact end; 14. Connector; 15. Housing; 16. Telescopic rod; 17. Second return spring; 18. Excitation coil; 19. Series wire; 20. Parallel jumper. Detailed Implementation

[0039] 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.

[0040] Please see Figures 1 to 11 The present invention provides a technical solution: a casting sand box for producing high-strength wear-resistant castings for large mining mills, comprising a support 1, a movable slide 2 set on the support 1, a lifting platform 3 assembled at the bottom of the movable slide 2, and a magnetic clamp 4 fixed at the lower end of the lifting platform 3, wherein the magnetic clamp 4 further comprises a magnetic cover 5.

[0041] The stationary iron core 8 is set inside the magnetic shield 5;

[0042] Multiple sets of excitation coils 18 are wound on the stationary iron core 8;

[0043] Energy storage piston cylinder 9 is fixed to the top of the magnetic shield 5;

[0044] The pressure rod 10 moves synchronously with the energy storage piston cylinder 9 via the connector 14;

[0045] A constant pressure short-circuit assembly is set up one-to-one with each group of excitation coils 18;

[0046] The energy storage piston cylinder 9 includes an auxiliary suction device 901 fixed at its end, a piston rod 902 slidably passing through the cylinder body, and a first return spring 903 sleeved on the outside of the piston rod 902.

[0047] The atmospheric pressure short-circuit assembly includes a short-circuit plate 12 connected in parallel with the excitation coil 18 and an atmospheric pressure button 13 arranged corresponding to the short-circuit plate 12. The bottom of the atmospheric pressure button 13 is provided with a contact end 1302 that is electrically connected to the short-circuit plate 12.

[0048] In this embodiment, the support frame 1 is a gantry-type steel structure bearing body, serving as the foundation for the installation and operation of the entire equipment. It is horizontally erected above the casting workstation, providing stable structural support for the transfer and hoisting of the core mold. The movable slide 2 is slidably assembled to the top beam of the support frame 1 via a linear guide pair, allowing for horizontal reciprocating linear displacement along the beam axis, thus realizing the horizontal transfer of the core mold between the material handling station and the sand box workstation. The lifting platform 3 adopts an electro-hydraulic lifting structure, with its fixed end locked to the lower end face of the movable slide 2 by high-strength bolts. The vertical telescopic end of the lifting platform 3 is connected to the magnetic clamp 4. The top is fixedly connected to drive the magnetic clamp 4 to complete the vertical lifting action, realizing the precise vertical alignment between the core mold and the sand box. The magnetic cover 5 is a closed magnetically conductive steel cover, which constitutes the external protection of the magnetic clamp 4. The stationary iron core 8 is fixedly installed in the inner cavity of the magnetic cover 5 by positioning bolts. Multiple sets of excitation coils 18 are wound sequentially along the axial direction of the stationary iron core 8 to form the electromagnetic body of the magnetic attraction operation. The energy storage piston cylinder 9 is locked and fixed to the top outer wall of the magnetic cover 5 by the end flange. Its cylinder axis is parallel to the axial direction of the stationary iron core 8. The piston rod 902 slides through the inner cavity of the energy storage piston cylinder 9 to assist in attraction. The actuator 901 is fixedly installed at the end of the cylinder body of the energy storage piston cylinder 9 near the lifting platform 3. The first return spring 903 is sleeved on the outside of the piston rod 902, together forming the main body of the energy storage and reset drive of the equipment. The extended end of the piston rod 902 is fixedly connected to the end of the pressure rod 10 through the connector 14. The pressure rod 10 slides through the inner cavity of the magnetic cover 5, and its axis is consistent with the axis of the piston rod 902. It can move axially linearly in sync with the extension and retraction of the piston rod 902. The number of sets of atmospheric pressure short-circuit components corresponds one-to-one with the number of sets of excitation coils 18. Each set of atmospheric pressure short-circuit components moves along the moving path of the pressure rod 10. Arranged in a linear array, the short-circuit plate 12 is fixed to the inner wall of the magnetic cover 5 by insulating bolts, and forms a parallel circuit with the excitation coil 18 of the corresponding group through wires. The constant pressure button 13 is vertically movably mounted below the short-circuit plate 12, and its pressing surface corresponds vertically to the moving path position of the pressure rod 10. The bottom of the constant pressure button 13 is fixedly provided with a conductive contact end 1302, which corresponds vertically to the conductive surface of the short-circuit plate 12. When the constant pressure button 13 is pressed down, the contact end 1302 can fit with the short-circuit plate 12 to achieve electrical conduction, and complete the short-circuit operation of the corresponding excitation coil 18.

[0049] The movable slide 2 is slidably mounted on the top crossbeam of the bracket 1. The fixed end of the lifting platform 3 is fixedly connected to the lower end face of the movable slide 2. The top of the magnetic clamp 4 is fixedly connected to the fixing buckle 7. The telescopic end of the lifting platform 3 is fixedly connected to the fixing buckle 7 so as to drive the magnetic clamp 4 to drive the magnetically attracted core mold to complete the horizontal translation and vertical lifting and positioning.

[0050] In this embodiment, the movable slide table 2 is slidably mounted on the top crossbeam of the bracket 1 via a linear guide pair, and can move horizontally back and forth along the axis of the crossbeam. The lifting platform 3 adopts an electric hydraulic lifting platform, and its telescopic end can move vertically to drive the magnetic clamp 4 to drive the magnetically attracted core mold to complete the horizontal translation and vertical lifting and positioning, so as to realize the precise transfer of the core mold from the material picking position to the top of the sand box and sand trough.

[0051] The short circuit board 12 is provided with a contact 1201, which is electrically connected to the contact end 1302. The bottom of the constant pressure button 13 is fixed with a bidirectional butterfly block 1301. A telescopic rod 16 that slides through the housing 15 is provided below the bidirectional butterfly block 1301. The bottom of the constant pressure button 13 is also provided with a second reset spring 17.

[0052] In this embodiment, a contact 1201 is fixedly provided on the short-circuit plate 12, and the contact 1201 and the contact end 1302 are positioned one-to-one. After being pressed and fitted, they can achieve stable electrical conduction. A bidirectional butterfly block 1301 is fixedly provided at the bottom of the constant pressure button 13. A telescopic rod 16 is provided below the bidirectional butterfly block 1301 and slides through the housing 15. The housing 15 is fixed to the inner wall of the magnetic cover 5, providing limiting support for the vertical sliding of the constant pressure button 13. A second reset spring 17 is also provided at the bottom of the constant pressure button 13. One end of the second reset spring 17 abuts against the bottom of the inner cavity of the housing 15, and the other end abuts against the lower end face of the bidirectional butterfly block 1301, providing a stable elastic driving force for the upward reset of the constant pressure button 13.

[0053] Multiple sets of excitation coils 18 are connected in series via a series line 19. The input terminal of the first excitation coil 18 is connected to the positive terminal of the power supply via a power line 11, and the output terminal of the last excitation coil 18 is connected to the negative terminal of the power supply via a power line 11. The head and tail of each set of excitation coils 18 are electrically connected to the corresponding short-circuit board 12 via a parallel jumper 20.

[0054] In this embodiment, multiple sets of excitation coils 18 are connected in series via a series line 19. In two adjacent sets of excitation coils 18, the tail end of the first set of excitation coils 18 is electrically connected to the head end of the second set of excitation coils 18 via the series line 19, forming a continuous series main circuit. The head end of the first excitation coil 18 is connected to the positive terminal of the power supply via a power line 11, and the tail end of the last excitation coil 18 is connected to the negative terminal of the power supply via a power line 11. The head and tail of each set of excitation coils 18 are electrically connected to the corresponding short-circuit board 12 via a parallel jumper 20, so that the short-circuit board 12 and the corresponding excitation coil 18 form an independent parallel circuit, ensuring that when a single short-circuit board 12 is conducting, it only short-circuits the corresponding excitation coil 18 and does not affect the normal operation of other coils.

[0055] The end face of the piston rod 902 facing the auxiliary attractor 901 is a magnetic metal surface. When the auxiliary attractor 901 is energized synchronously with the excitation coil 18, the auxiliary attractor 901 attracts the piston rod 902 and compresses the first return spring 903 to complete energy storage.

[0056] In this embodiment, the end face of the piston rod 902 facing the auxiliary attractor 901 is a high-permeability low-carbon steel metal surface. The auxiliary attractor 901 is a DC electromagnetic attractor, and its power supply circuit is designed in parallel with the power supply circuit of the excitation coil 18, so that it can be synchronously energized with the excitation coil 18. When the auxiliary attractor 901 is synchronously energized with the excitation coil 18, the electromagnetic attraction generated by the auxiliary attractor 901 attracts the magnetic metal end face of the piston rod 902, causing the piston rod 902 to contract along the cylinder axis and compress the first return spring 903 to complete the energy storage operation of elastic potential energy.

[0057] After the auxiliary actuator 901 is independently de-energized, the first reset spring 903 resets and pushes the piston rod 902 to extend. Through the connector 14, it drives the pressure rod 10 to move towards the constant pressure button 13. The pressure rod 10 sequentially presses and triggers each group of constant pressure buttons 13, making the corresponding short circuit board 12 electrically connected to the constant pressure button 13, and short-circuiting the corresponding excitation coil 18 segment by segment, realizing the linear decay of magnetic force, so that the core mold falls smoothly into the sand trough with its own weight and the magnetic force dissipation.

[0058] In this embodiment, the auxiliary attractor 901 is equipped with an independent power-off control switch, which can realize independent power-off operation of the excitation coil 18. After the auxiliary attractor 901 is independently powered off, its electromagnetic attraction completely disappears. The elastic restoring force of the first reset spring 903 drives the piston rod 902 to extend and reset along the cylinder axial direction. Through the connector 14, the pressure rod 10 moves axially horizontally towards the constant pressure button 13. During the movement of the pressure rod 10, it sequentially presses and triggers each group of constant pressure buttons 13, so that the contact end 1302 of the corresponding short circuit plate 12 and the constant pressure button 13 is electrically connected, and the corresponding excitation coil 18 is short-circuited segment by segment, so that the effective number of turns of the excitation coil 18 is linearly reduced segment by segment, so that the magnetic force is linearly attenuated, and the core mold falls smoothly into the sand trough with its own weight and the magnetic force dissipation.

[0059] The end of the pressure rod 10 facing the constant pressure button 13 is a trapezoidal guide end, and its rear section is a rectangular limiting section. The trapezoidal guide end is in contact with the top surface of the constant pressure button 13 to achieve a gradual and smooth compression triggering of the constant pressure button 13.

[0060] In this embodiment, the end of the pressure rod 10 facing the constant pressure button 13 is a trapezoidal guide end, and its rear section is a rectangular limiting section. The inclined surface of the trapezoidal guide end smoothly fits the top surface of the constant pressure button 13. During the axial movement of the pressure rod 10, the constant pressure button 13 can be gradually and smoothly pressed and triggered by the inclined surface of the trapezoidal guide end, avoiding the switching shock and magnetic force change caused by instantaneous pressing, and ensuring the stability of the short circuit process of the excitation coil 18.

[0061] When the pressure rod 10 moves axially, it sequentially presses and triggers multiple sets of constant pressure buttons 13. The pressing and triggering stroke of a single set of constant pressure buttons 13 is matched one by one with the short-circuit action stroke of the corresponding excitation coil 18.

[0062] In this embodiment, when the pressure rod 10 moves axially, it sequentially presses and triggers multiple sets of constant pressure buttons 13 arranged in a linear array through the trapezoidal guide end. The pressing and triggering stroke of a single set of constant pressure buttons 13 is matched one by one with the short-circuit action stroke of the corresponding excitation coil 18, ensuring that a set of excitation coils 18 can be short-circuited every fixed stroke of the pressure rod 10, thereby realizing the gradual linear reduction of the effective number of turns of the excitation coil 18, and thus realizing the linear and stable attenuation of the electromagnetic attraction force.

[0063] The end of the stationary iron core 8 is fixed with a pole piece 6. The magnetic attraction working surface of the pole piece 6 is flush with the end face of the magnetic cover 5 to improve the magnetic attraction stability of the core mold after the excitation coil 18 is energized.

[0064] In this embodiment, the electrode 6 is made of high-permeability pure iron material. The magnetic working surface of the electrode 6 is flush with the end face of the magnetic cover 5, which can maximize the conduction of the magnetic flux generated after the excitation coil 18 is energized, increase the magnetic induction intensity of the magnetic working surface, improve the magnetic attraction stability of the pure iron or low carbon steel core mold, and avoid the risk of the core mold falling off during transportation.

[0065] Multiple sets of excitation coils 18 are arranged in an equidistant array along the axial direction of the stationary iron core 8. The constant pressure button 13 and short circuit board 12 corresponding to each set of excitation coils 18 are arranged in a linear array on the moving path of the pressure rod 10 to realize the sequential short circuit of the excitation coils 18 segment by segment. The excitation coils 18 in the two magnetic clamps 4 adopt a relative winding method, that is, the excitation coil 18 in the left clamp is wound clockwise, and the excitation coil 18 in the right clamp is wound counterclockwise.

[0066] In this embodiment, multiple sets of excitation coils 18 are arranged in an equidistant array along the axial direction of the stationary iron core 8. The constant pressure buttons 13 and short-circuit plates 12 corresponding to each set of excitation coils 18 are arranged in a linear array on the moving path of the pressure rod 10. The spacing of the constant pressure buttons 13 corresponds one-to-one with the spacing of the excitation coils 18, thus achieving sequential short-circuiting of the excitation coils 18 segment by segment. (The core principle of this invention's magnetic attraction is based on the inherent magnetization characteristics of ferromagnetic materials: pure iron, low-carbon steel, and other ferromagnetic metals are spontaneously magnetized when near a magnetic field. The end near the electromagnet's magnetic pole automatically forms a polarity opposite to that pole, achieving stable adsorption through the attraction of opposite magnetic poles. Therefore, regardless of whether the electromagnet outputs an N pole or a S pole, it can effectively attract the ferromagnetic core mold, without any problem of magnetic pole compatibility failure. The direction of the electromagnet's magnetic poles is determined by both the current direction and the coil winding direction, and can be accurately determined using the right-hand screw rule (Ampere's rule): right-hand...) Hold the excitation coil 18 with your four fingers bent in the same direction as the current in the coil. The end pointed to by your thumb is the N pole (north pole) of the coil, and the other end is the S pole (south pole). When the present invention adopts the opposing double magnetic clamp 4 arrangement design, the excitation coils 18 in the two magnetic clamps 4 adopt a relative winding method, that is, the excitation coil 18 in the left clamp is wound clockwise, and the excitation coil 18 in the right clamp is wound counterclockwise. Under the premise that the coils are supplied with current in the same direction, through this winding direction matching, the right end of the left coil and the left end of the right coil can form opposite magnetic poles (left S, right N), realizing the opposite magnetic poles are arranged in opposite directions, so that the magnetic lines of force can completely pass through the ferromagnetic core mold to form a closed magnetic circuit. This completely avoids the problems of magnetic lines of force repulsion, difficulty in passing through the core mold, and significant attenuation of attraction caused by the opposite magnetic poles (left N, right N / left S, right S), maximizes the superimposed magnetic attraction force, and improves the stability of the core mold adsorption clamping.

[0067] Working principle: When using the casting sand box for producing high-strength wear-resistant castings for large mining mills, first place the casting sand box directly below the support 1, start the equipment to energize the excitation coil 18 and the auxiliary attractor 901 synchronously. After the excitation coil 18 is energized, it generates a directional magnetic field, which firmly magnetically attracts the core mold made of pure iron or low carbon steel through the stationary iron core 8 and the pole piece 6.

[0068] In this invention, multiple sets of excitation coils 18 are arranged in series at equal intervals along the axial direction of the stationary iron core 8. Adjacent excitation coils 18 within a single clamp are designed to be wound in the same direction and have the same current direction in series, ensuring that the magnetic pole directions of all excitation coils 18 are completely unified. After the magnetic fields are superimposed, a stable directional magnetic circuit is formed, further strengthening the magnetic attraction force. At the same time, the auxiliary attractor 901 is energized to generate electromagnetic attraction force, attracting the magnetic metal end face of the piston rod 902, causing the piston rod 902 to contract and compress the first return spring 903 to complete energy storage. Then, through the horizontal movement of the moving slide 2, the magnetic clamp 4 with the magnetically attracted core mold is transferred to the top of the sand box. Then, through the vertical descent of the lifting platform 3, the core mold is moved to a preset position directly above the sand trough. Afterward, the auxiliary attractor 901 is independently de-energized, while the excitation coils 18 remain energized.

[0069] After the auxiliary magnetic actuator 901 is de-energized, the electromagnetic attraction disappears. The elastic restoring force of the first return spring 903 drives the piston rod 902 to extend and return to its original position along the cylinder axial direction. Through the connecting piece 14, it drives the pressure rod 10 to move axially towards the constant pressure button 13. During the movement of the pressure rod 10, its trapezoidal guide end sequentially presses and triggers each group of constant pressure buttons 13. The constant pressure buttons 13 are pressed downward and move downward, pushing the telescopic rod 16 to retract through the bidirectional butterfly block 1301. At the same time, the contact end 1302 at the bottom of the constant pressure button 13 is also affected. The contact 1201 of the corresponding short-circuit plate 12 is connected, and the corresponding excitation coil 18 is short-circuited segment by segment, so that the effective number of turns of the excitation coil 18 is reduced segment by segment. The magnetic flux decreases linearly with the effective number of turns, and the electromagnetic attraction decreases synchronously and steadily. As the core mold gradually dissipates due to its own weight and magnetic force, it slowly and steadily falls into the sand trough. There is no need to excavate the hoisting avoidance groove throughout the process, and the original compaction and forming structure of the sand trough will not be damaged. This avoids the problems of uneven sand mold strength and casting quality defects caused by the excavation and backfilling of the avoidance groove from the root.

[0070] After the core mold is positioned, the excitation coil 18 is de-energized, the magnetic field disappears, and the magnetization state of the core mold dissipates simultaneously, completing the core mold hoisting and positioning operation. Subsequently, the lifting platform 3 rises and resets, the moving slide 2 returns to the material picking position, and the constant pressure button 13 resets upward under the action of the second reset spring 17, disconnecting the contact 1201 from the contact end 1302, preparing for the next core mold hoisting operation.

[0071] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A casting sand box for producing high-strength wear-resistant castings for large mining mills, comprising a support (1), a movable slide (2) mounted on the support (1), a lifting platform (3) assembled at the bottom of the movable slide (2), and a magnetic clamp (4) fixed at the lower end of the lifting platform (3), characterized in that: The magnetic clamp (4) also includes a magnetic cover (5); A stationary iron core (8) is set inside the magnetic shield (5); Multiple sets of excitation coils (18) are wound on the stationary iron core (8); Energy storage piston cylinder (9) fixed on top of magnetic shield (5); The pressure rod (10) moves synchronously with the energy storage piston cylinder (9) via the connector (14). A constant pressure short-circuit assembly is set up one-to-one with each group of excitation coils (18); The energy storage piston cylinder (9) includes an auxiliary suction device (901) fixed at its end, a piston rod (902) slidably passing through the cylinder body, and a first return spring (903) sleeved on the outside of the piston rod (902). The atmospheric pressure short-circuit assembly includes a short-circuit plate (12) arranged in parallel with the excitation coil (18) and an atmospheric pressure button (13) arranged corresponding to the short-circuit plate (12). The bottom of the atmospheric pressure button (13) is provided with a contact end (1302) that is electrically connected to the short-circuit plate (12).

2. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: The movable slide (2) is slidably mounted on the top beam of the bracket (1). The fixed end of the lifting platform (3) is fixedly connected to the lower end face of the movable slide (2). The top of the magnetic clamp (4) is fixedly connected to a fixing buckle (7). The telescopic end of the lifting platform (3) is fixedly connected to the fixing buckle (7) so as to drive the magnetic clamp (4) to drive the magnetic core mold to complete the horizontal translation and vertical lifting alignment.

3. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: The short circuit board (12) is provided with a contact (1201), which is electrically connected to the contact end (1302). The bottom of the constant pressure button (13) is fixed with a bidirectional butterfly block (1301). A telescopic rod (16) that slides through the housing (15) is provided below the bidirectional butterfly block (1301). The bottom of the constant pressure button (13) is also provided with a second reset spring (17).

4. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: Multiple sets of excitation coils (18) are connected in series via a series line (19). The input end of the first excitation coil (18) is connected to the positive terminal of the power supply via a power line (11), and the output end of the last excitation coil (18) is connected to the negative terminal of the power supply via a power line (11). The head and tail of each set of excitation coils (18) are electrically connected to the corresponding short-circuit board (12) via a parallel jumper (20).

5. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: The end face of the piston rod (902) facing the auxiliary attractor (901) is a magnetic metal surface. When the auxiliary attractor (901) and the excitation coil (18) are energized synchronously, the auxiliary attractor (901) attracts the piston rod (902) and compresses the first return spring (903) to complete energy storage.

6. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 5, characterized in that: After the auxiliary suction device (901) is independently de-energized, the first reset spring (903) resets and pushes the piston rod (902) to extend. Through the connector (14), it drives the pressure rod (10) to move towards the normal pressure button (13). The pressure rod (10) sequentially squeezes and triggers each group of normal pressure buttons (13), so that the corresponding short circuit board (12) and the normal pressure button (13) are electrically connected, and the corresponding excitation coil (18) is short-circuited segment by segment to achieve linear decay of magnetic force, so that the core mold falls smoothly into the sand trough with its own weight and the magnetic force dissipation.

7. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: The end of the pressure rod (10) facing the normal pressure button (13) is a trapezoidal guide end, and its rear section is a rectangular limiting section. The trapezoidal guide end is in contact with the top surface of the normal pressure button (13) to achieve a gradual and smooth squeezing trigger of the normal pressure button (13).

8. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 7, characterized in that: When the pressure rod (10) moves along the axial direction, it sequentially presses and triggers multiple sets of constant pressure buttons (13). The pressing and triggering stroke of a single set of constant pressure buttons (13) is matched one by one with the short-circuit action stroke of the corresponding excitation coil (18).

9. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: The end of the static iron core (8) is fixed with a pole piece (6), and the magnetic attraction working surface of the pole piece (6) is flush with the end face of the magnetic cover (5) to improve the magnetic attraction stability of the core mold after the excitation coil (18) is energized.

10. A casting sand box for producing high-strength wear-resistant castings for large mining mills according to claim 1, characterized in that: Multiple sets of excitation coils (18) are arranged in an equidistant array along the axial direction of the stationary iron core (8). The constant pressure button (13) and short circuit board (12) corresponding to each set of excitation coils (18) are arranged in a linear array on the moving path of the pressure rod (10) to realize the sequential short circuit of the excitation coils (18). The excitation coils (18) in the two magnetic clamps (4) adopt a relative winding method, that is, the excitation coil (18) in the left clamp is wound clockwise, and the excitation coil (18) in the right clamp is wound counterclockwise.

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