An automatic mechanism sand production device

Abstract

The application discloses an automatic mechanism sand production device and belongs to the technical field of mechanism sand production. The device comprises a sieve box, an exciting shaft, a rotating disc and a motor, a radial sliding slot is formed in the rotating disc, a counterweight block is slidably arranged in the sliding slot, and a return spring is arranged between the counterweight block and the bottom of the sliding slot. The centrifugal force received by the counterweight block when the exciting shaft rotates is balanced with the elastic force of the return spring. When the load change causes the rotating speed fluctuation, the counterweight block automatically slides in the radial direction to change the eccentric distance, so that the exciting force size is adjusted, and the rotating speed negative feedback stability mechanism is formed. The application can realize the self-adaptive adjustment of the exciting force with the load without a sensor and a controller, effectively reduces the starting current, stabilizes the screening efficiency, prolongs the service life of the equipment, and has the advantages of simple structure and high reliability.

Description

Technical Field

[0001] This invention relates to the field of manufactured sand production technology, specifically to an automated manufactured sand production device. Background Technology

[0002] Manufactured sand production equipment typically includes a crushing unit, a vibrating screen, and conveying equipment. The vibrating screen's exciter usually adopts a fixed eccentric block structure, with a constant excitation force.

[0003] In actual production, the feed rate fluctuates frequently. Under heavy load, insufficient excitation force can easily lead to material accumulation and decreased screening efficiency, while under light load, excessive excitation force can accelerate fatigue damage to the screen and bearings. To improve these problems, existing technologies have attempted to use frequency conversion regulation or adjustable eccentric structures. However, frequency conversion regulation has a slow response and high energy consumption, while adjustable eccentric structures often require manual adjustment during shutdown and cannot be adaptively adjusted online.

[0004] In view of this, the present invention proposes an automated manufactured sand production device, which solves the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] An automated manufactured sand production apparatus includes a screen box, a vibrating shaft, a turntable fixedly mounted on the vibrating shaft, and a motor for driving the vibrating shaft to rotate. It also includes: A radial groove is formed on the turntable; A counterweight block is slidably disposed in the radial groove, and the counterweight block reciprocates between the radial inner end and the radial outer end along the radial direction of the turntable; And a return spring disposed between the counterweight and the bottom of the radial groove, the return spring always applying a return force toward the radially inner end to the counterweight; The centrifugal force experienced by the counterweight when the excitation shaft rotates is balanced by the elastic force of the return spring. When the load increases and the speed of the excitation shaft decreases, the counterweight moves radially inward to reduce the excitation force, thereby reducing the motor load and suppressing further speed decrease. When the load decreases and the speed increases, the counterweight moves radially outward to increase the excitation force, thereby increasing the motor load and suppressing further speed increase, thus forming a speed negative feedback stabilization mechanism.

[0007] Preferably, the return spring is a nonlinear spring, whose stiffness coefficient K increases with the increase of compression x, satisfying: K(x) = K0·[1 + β·x], where K0 is the initial stiffness, β is the nonlinear coefficient, and the value of β is in the range of 0.5 mm. -1 ~2.0mm -1 .

[0008] Preferably, the nonlinear spring is a variable pitch helical spring, the wire diameter of the spring material is 4mm to 8mm, the effective number of turns is 5 to 10, and the ratio of free length to installation length is 1.5 to 2.5.

[0009] Preferably, a high-viscosity silicone grease layer is provided between the counterweight and the radial groove, the thickness of the silicone grease layer is 0.1 mm to 0.5 mm, and the dynamic viscosity of the silicone grease is 1000 mPa·s to 10000 mPa·s.

[0010] Preferably, the center of mass of the counterweight coincides with its geometric center in the radial direction, and the distance between its center of mass and the axis of the excitation shaft is a first eccentricity e1 when the counterweight is at the inner radial end and a second eccentricity e2 when it is at the outer radial end, with e2 = [1.8~3.0]·e1; the preload F0 of the return spring when the counterweight is at the inner radial end satisfies: F0 ∈ [m·e1·(0.65·ω n ) 2 ,m·e1·(0.7·ω n ) 2 ], where ω n The rated angular velocity of the excitation shaft is denoted by m, where m is the mass of the counterweight. This is such that the counterweight begins to slide outward from the radial inner end when the rotational speed reaches 65% to 70% of the rated speed.

[0011] Preferably, there are two turntables, symmetrically fixed at both ends of the excitation shaft; each turntable has one and only one radial groove; the radial grooves on the two turntables are 180° apart in the circumferential direction; the counterweights in the two turntables have the same mass and slide radially synchronously when the excitation shaft rotates, so that the centrifugal forces of the two counterweights are in opposite directions, forming an excitation couple.

[0012] Preferably, the device further includes a controller and a speed sensor disposed on the excitation shaft. The controller is electrically connected to the motor and the speed sensor. The controller is configured to receive the actual speed n detected by the speed sensor, compare it with the target speed n0, and adjust the frequency of the motor to make n approach n0, thereby indirectly controlling the radial position of the counterweight and realizing auxiliary adjustment of the excitation force.

[0013] Preferably, the controller is further configured to: acquire the real-time current value I of the motor, calculate its deviation Δi from the target current value I0; when |Δi| is greater than a preset threshold, the controller proportionally adjusts the frequency of the motor so that the speed change Δn = K. p ·Δi, where K p The proportional coefficient is used; changes in rotational speed cause changes in the radial position of the counterweight, thereby changing the excitation force and causing the motor current to return to the target value, thus forming load following control.

[0014] Preferably, the counterweight block is provided with a detachable counterweight adjustment plate. The counterweight adjustment plate is fixed to the counterweight block by screws. The number of counterweight adjustment plates can be increased or decreased by removing the plug on the turntable to change the total mass of the counterweight block, thereby adjusting the range of the excitation force.

[0015] Preferably, it also includes a frame, which is inclined; the screen box is installed on the frame by a number of vibration springs, and the screen box is inclined at the same angle as the frame; the higher end of the frame is provided with a feed inlet, and the manufactured sand enters the screen box from the feed inlet.

[0016] The beneficial effects of this invention are: The automated manufactured sand production device provided by this invention utilizes the radial sliding of a counterweight under the action of centrifugal force and the elastic force of a return spring to achieve instantaneous tracking of the excitation force in response to load changes: when the load increases and the rotational speed decreases, the counterweight slides inward to reduce the excitation force, thereby reducing the motor load and suppressing further speed decreases, while also preventing excessive excitation force from impacting the screen under heavy loads; when the load decreases, the counterweight slides outward to increase the excitation force, increasing the motor load to stabilize the rotational speed. The entire adjustment process is purely mechanical, with rapid response and no additional energy consumption. Combined with a nonlinear spring and a viscous damping layer, the excitation force output is stable, the screening efficiency is stable, the motor starting current is significantly reduced, and the bearing and screen lifespan is extended. Furthermore, the detachable counterweight adjustment plate and optional variable frequency electronic control further broaden the device's adaptability to various operating conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] in: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the connection structure at the bottom of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 A schematic diagram of the connection structure between the turntable and the excitation shaft; Figure 5 for Figure 4 Enlarged view at point B in the middle; Figure 6 A schematic diagram of the connection structure of the turntable, screen box and excitation shaft; Figure 7 for Figure 6 Enlarged view of point C in the middle.

[0019] In the picture: 1. Screen box; 2. Motor; 3. Vibration shaft; 4. Turntable; 41. Radial groove; 42. Counterweight; 43. Return spring; 44. Counterweight adjusting plate; 45. Plug; 5. Controller; 6. Speed ​​sensor; 7. Frame; 8. Vibration spring; 9. Feed inlet. Detailed Implementation

[0020] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example 1:

[0021] like Figure 1-7 As shown, this embodiment provides an automated manufactured sand production device, the overall structure of which is as follows: It includes a screen box 1, a vibrating shaft 3, a turntable 4 fixedly mounted on the vibrating shaft 3, and a motor 2 that drives the vibrating shaft 3 to rotate. The motor 2 is an industrial frequency asynchronous motor. A radial groove 41 is provided on the turntable 4, and a counterweight 42 is slidably disposed within the radial groove 41. The counterweight 42 can reciprocate between its radial inner end (near the axis) and radial outer end (away from the axis) along the radial direction of the turntable 4. A return spring 43 is provided between the counterweight 42 and the bottom of the radial groove 41, and the return spring 43 always applies a return force toward the radial inner end to the counterweight 42.

[0022] After the device is started, the excitation shaft 3 rotates, and the counterweight 42 is subjected to centrifugal force. At low speeds, the centrifugal force is less than the spring force of the return spring 43, and the counterweight 42 remains at the radial inner end. At this time, the eccentricity is minimal, and the excitation force is only a small proportion of the rated value. Therefore, the starting current of the motor 2 is significantly reduced, and it can start smoothly without a soft starter, thus reducing the impact on the power grid.

[0023] When the rotational speed increases to about two-thirds of the rated speed, the centrifugal force and the spring force reach equilibrium, and the counterweight 42 begins to slide outward. When the rotational speed continues to increase to the rated value, the counterweight 42 slides to the radial outer end, the eccentricity reaches the maximum value, the excitation force reaches the rated value, and the screen box 1 generates stable vibration to screen the material.

[0024] When the feed rate suddenly increases (load increases), the speed of motor 2 decreases due to the increased load torque. This decrease in speed reduces the centrifugal force on counterweight 42, causing the spring force of the return spring 43 to exceed the centrifugal force. The counterweight 42 then moves radially inward, reducing the eccentricity and consequently the excitation force. This reduced excitation force lowers the driving power required by the vibrating screen, decreasing the load torque on motor 2 and thus suppressing further speed decreases. This prevents excessive excitation force under heavy loads from causing screen fatigue and breakage, while simultaneously maintaining a relatively stable motor speed and significantly reducing the fluctuation range of screening efficiency.

[0025] When the feed rate suddenly decreases, the speed of motor 2 increases, the centrifugal force increases, the counterweight 42 slides outward, the excitation force increases, the load on motor 2 increases, and the speed is suppressed from further increasing. This prevents the screen box 1 from vibrating under light load, which could impact the bearings and springs and extend the equipment's lifespan. Example 2:

[0026] like Figure 4-7 As shown, based on Example 1, the return spring 43 is a nonlinear spring, specifically a variable pitch helical spring. Its stiffness coefficient K increases with the increase of compression x, satisfying the formula: K(x) = K0·[1 + β·x], where K0 is the initial stiffness and β is the nonlinear coefficient, with a value range of 0.5 mm. -1 ~2.0mm -1 .

[0027] The spring parameters satisfy the following: when the counterweight 42 is at the radial inner end, the spring has an initial compression; when the counterweight 42 slides outward to the radial outer end, the spring compression increases and the stiffness increases accordingly.

[0028] By employing a nonlinear spring, the spring force on the counterweight 42 increases nonlinearly during sliding. In the lower speed range, the spring stiffness is lower, making it easier for the counterweight 42 to begin sliding, thus improving adjustment sensitivity. In the higher speed range, the spring stiffness increases, reducing the sensitivity of the counterweight 42's displacement to speed changes and preventing frequent vibrations caused by minute speed fluctuations. This results in a more stable excitation force output, reduced vibration acceleration fluctuations in the screen box 1, and improved screening accuracy.

[0029] The specific structure of the variable pitch helical spring is as follows: the pitch at both ends of the spring is smaller, and the pitch in the middle is larger, so that the spring has lower stiffness in the initial stage of compression and higher stiffness in the later stage, matching the square relationship between centrifugal force and rotational speed. Through the synergistic design of the nonlinear spring and centrifugal force, smooth adjustment of the excitation force is achieved over a wide range of rotational speeds. Example 3:

[0030] like Figure 4-7 As shown, based on embodiment 1 or 2, a high-viscosity silicone grease layer is provided between the counterweight 42 and the radial groove 41. The silicone grease layer is attached to the inner wall of the radial groove 41 and the outer wall of the counterweight 42 by coating, and the counterweight 42 can still slide freely in the groove.

[0031] When the speed of motor 2 fluctuates at a high frequency due to fluctuations in grid voltage or slight changes in load, the centrifugal force on counterweight 42 also fluctuates accordingly. Without damping, counterweight 42 will vibrate slightly radially at the same frequency as the speed fluctuation, causing high-frequency shaking of the excitation force, which in turn makes the screen box 1 vibrate unstable and affects the material movement trajectory. The high-viscosity silicone grease layer generates shear viscous resistance when counterweight 42 slides. This resistance is proportional to the sliding speed and can effectively absorb the high-frequency vibration energy of counterweight 42, making it respond only to slow changes in speed (such as speed drift caused by load) and insensitive to high-frequency fluctuations. The high-frequency noise component of the vibration of screen box 1 is reduced, the material movement trajectory on the screen surface is more regular, the screening efficiency is improved, and fatigue cracks of the screen caused by vibration impact are reduced.

[0032] By combining viscous damping with centrifugal force-spring force adaptive adjustment, this device can both respond quickly to load changes and suppress high-frequency interference. Example 4:

[0033] like Figure 4-7 As shown, this embodiment presents the parameter design relationships. The counterweight 42 is made of high-density alloy, and its center of mass coincides with its geometric center. At the radially inner end, the distance from the center of mass of the counterweight 42 to the axis of the excitation shaft 3 is the first eccentricity e1; at the radially outer end, it is the second eccentricity e2, and e2 is an appropriate multiple of e1 (1.8 to 3.0 times). The rated angular velocity of the excitation shaft 3 is denoted as ω. n .

[0034] The preload force F0 of the return spring 43 when the counterweight 42 is at the radial inner end satisfies the following relationship: F0 is between m·e1·(0.65·ω n ) 2 With m·e1·(0.7·ω n ) 2 The preload is between [a value] and [a value], where m is the mass of the counterweight 42. This preload is achieved by adjusting the installation compression of the return spring 43.

[0035] When the speed of the excitation shaft 3 increases from zero, before reaching approximately two-thirds of the rated speed, the centrifugal force is less than the preload, and the counterweight 42 remains at the inner end, resulting in a smaller excitation force and facilitating the start-up of the motor 2. Once the speed exceeds this threshold, the centrifugal force becomes greater than the preload, and the counterweight 42 begins to slide outwards, gradually increasing the eccentricity. The excitation force increases smoothly with the increase in speed. During the start-up phase, the peak current of the motor 2 is significantly reduced, and the impact experienced by traditional adjustable eccentric vibrators when the speed crosses zero is avoided. Simultaneously, due to the preload matching, the counterweight 42 will not slide back to the inner end due to minor speed fluctuations during normal operation, ensuring the stability of the excitation force. Example 5:

[0036] like Figure 6 and Figure 7 As shown, in this embodiment, there are two turntables 4, symmetrically fixed at both ends of the excitation shaft 3. Each turntable 4 has one and only one radial groove 41. The radial grooves 41 on the two turntables 4 are at an angle of 180° in the circumferential direction. The counterweights 42 in the two turntables 4 have the same mass and slide radially synchronously when the excitation shaft 3 rotates (i.e., they move inward or outward simultaneously).

[0037] When the excitation shaft 3 rotates, the centrifugal force generated by the counterweight 42 on the left turntable 4 is in the opposite direction to that generated by the counterweight 42 on the right turntable 4 (because the two are 180° out of phase). These two centrifugal forces of equal magnitude and opposite direction form a couple, which acts on the excitation shaft 3, causing the excitation shaft 3 to generate torsional vibration around its axis, and is transmitted to the screen box 1 through the bearing, driving the screen box 1 to generate linear vibration. Effects: Compared with the existing technology that uses a single-sided counterweight 42 or symmetrical but unidirectional counterweights 42, this arrangement eliminates the net radial force acting on the bearing, significantly extending bearing life; at the same time, the couple-driven method makes the vibration amplitude of each point in the screen box 1 more uniform, improving screening efficiency. Furthermore, because the two counterweights 42 slide synchronously, the magnitude of the excitation couple automatically adjusts with the load, always maintaining the optimal vibration intensity. Example 6:

[0038] like Figure 1 and Figure 2As shown, this embodiment is a further improvement based on any one of the aforementioned embodiments 1 to 5, and is particularly suitable for applications requiring higher speed stability. Motor 2 is replaced with a variable frequency motor, and a controller 5 and a speed sensor 6 are added. The controller 5 is a programmable logic controller, and the speed sensor 6 is mounted at the end of the excitation shaft 3. The controller 5 is electrically connected to the motor 2 (which is a variable frequency motor) and the speed sensor 6.

[0039] The speed sensor 6 detects the actual speed n of the excitation shaft 3 in real time and sends it to the controller 5. The controller 5 has a preset target speed n0. When the actual speed n deviates from n0, the controller 5 adjusts the frequency of the motor 2 to make n approach n0. For example, when the feed rate increases and the speed decreases, the controller 5 appropriately increases the frequency of the motor 2 to restore the speed to the target value. During this process, due to the increase in speed, the centrifugal force on the counterweight 42 increases, causing it to slide outward, and the excitation force increases accordingly, which helps the material pass through the screen. Compared with the pure mechanical adaptive scheme, after adding frequency conversion control, the speed can be accurately maintained at the set value, the vibration frequency of the screen box 1 is constant, and the particle size of the material is more uniform. At the same time, the frequency conversion adjustment and mechanical adaptation work together, and the frequency converter only needs to fine-tune the frequency, which reduces energy consumption compared with pure frequency conversion adjustment.

[0040] The controller 5 also acquires the real-time current value I of motor 2 and calculates its deviation Δi from the target current value I0. The target current value I0 corresponds to the current of motor 2 under the optimal feed rate. When |Δi| exceeds a preset threshold, the controller 5 proportionally adjusts the frequency of motor 2 so that the speed change Δn is proportional to Δi (with an appropriate proportionality coefficient). The speed change causes the radial position of the counterweight 42 to change, thereby changing the excitation force and causing the current of motor 2 to return to the target value.

[0041] The target current I0 is set to a reasonable value corresponding to full load. When the feed rate suddenly increases and the current of motor 2 rises above the threshold, the controller 5 proportionally increases the frequency of motor 2, the speed increases slightly, the counterweight 42 slides outward, the excitation force increases, the material passes through the screen faster, the material layer on the screen surface becomes thinner, and the current of motor 2 gradually decreases to near the target value. This load-following control allows the device to automatically adapt to changes in the feed rate, maintain optimal screening efficiency, and avoid motor 2 stalling due to overload. Compared with traditional PID control, this scheme uses mechanical self-adaptation to undertake most of the adjustment task. The controller 5 only needs to output a small adjustment signal, resulting in fast response and no overshoot.

[0042] The mechanical ring is responsible for quickly suppressing speed fluctuations, while the electronic control ring is responsible for accurately maintaining the set operating point; the two complement each other. Example 7:

[0043] like Figure 6 and Figure 7As shown, this embodiment provides a function for manually adjusting the excitation force range. A detachable counterweight adjustment plate 44 is provided on the counterweight block 42. The counterweight adjustment plate 44 is thin and made of the same material as the counterweight block 42. The counterweight adjustment plate 44 is fixed to the side of the counterweight block 42 by screws. A process hole is provided on the turntable 4, which is normally sealed by a plug 45.

[0044] When it is necessary to change the adjustment range of the excitation force (e.g., switching from fine sand production to coarse sand production, or a change in raw material density), the operator first stops the machine, then removes the plug 45 on the turntable 4 to expose the process hole. The number of counterweight adjustment pieces 44 is increased or decreased as needed, and the plug 45 is then reinstalled. By increasing or decreasing the number of counterweight adjustment pieces 44, the total mass of the counterweight block 42 can be adjusted within a certain range, correspondingly expanding the excitation force adjustment range by approximately 1.5 times. The same unit can adapt to different materials and production requirements without replacing any major components, significantly improving equipment versatility. Example 8:

[0045] like Figure 1 As shown, this embodiment describes the overall support and feeding structure of the device. It also includes a frame 7, which is welded from structural steel and is inclined at an appropriate angle (e.g., 10° to 20°). The screen box 1 is mounted on the frame 7 via several sets of vibration springs 8. Each set of vibration springs 8 includes two rubber-metal composite springs, one upper and one lower. The screen box 1 is inclined at the same angle as the frame 7. A feed inlet 9 is located at the higher end (upper end) of the frame 7. The feed inlet 9 is funnel-shaped, and its outlet faces the feed end of the screen box 1.

[0046] The manufactured sand raw material falls into the feed end of the screen box 1 through the feed inlet 9. Due to the inclination of the frame 7 and the screen box 1, the material moves towards the lower end under its own weight under vibration, while being screened simultaneously. The vibration spring 8 isolates the vibration of the screen box 1 from the frame 7, reducing the dynamic load transmitted to the foundation. Effects: The inclined arrangement ensures a moderate material conveying speed, sufficient screening time, and improved fine particle penetration; the vibration spring 8 effectively reduces vibration, and the foundation vibration meets environmental protection requirements. Simultaneously, the feed inlet 9 is located at the higher end, preventing direct impact of the material on the screen and extending the screen's lifespan.

[0047] Work process: When this automated manufactured sand production device is started, motor 2 drives the excitation shaft 3 to rotate, and turntable 4 rotates accordingly. At the lower speed stage, the centrifugal force on the counterweight 42 is less than the elastic force of the return spring 43, and the counterweight 42 is held at the radial inner end of the radial groove 41. At this time, the center of mass of the counterweight 42 is closest to the axis of the excitation shaft 3, and the excitation force is minimal. Therefore, the starting current of motor 2 is small, and it can start smoothly without soft start.

[0048] As the speed of motor 2 gradually increases to about two-thirds of its rated speed, the centrifugal force increases to balance the elastic force of the return spring 43, and the counterweight 42 begins to slide outward along the radial groove 41. When the speed continues to increase to the rated value, the counterweight 42 slides to the radial outer end, the eccentricity reaches its maximum, the excitation force reaches the rated value, and the screen box 1 generates stable vibration. The manufactured sand raw material falls into the screen box 1 from the feed port 9 at the high end of the frame 7. Under the combined action of the inclined screen box 1 and the vibration spring 8, the material moves along the screen surface to the lower end and completes the screening.

[0049] When the feed rate suddenly increases, leading to an increased load, the speed of motor 2 decreases due to the increased load torque. This decrease in speed reduces the centrifugal force on counterweight 42, and the spring force of the return spring 43 exceeds the centrifugal force, causing counterweight 42 to move radially inward, reducing the eccentricity and consequently the excitation force. This reduced excitation force lowers the required driving power for the vibrating screen, decreasing the load torque on motor 2 and thus suppressing further speed decreases while protecting the screen from excessive excitation force impact. Conversely, when the feed rate suddenly decreases, the speed of motor 2 increases, the centrifugal force increases, counterweight 42 slides outward, the excitation force increases, the load on motor 2 increases, and further speed increases are suppressed. The entire process requires no sensor or controller intervention; pure mechanical means achieves speed negative feedback stabilization.

[0050] During the sliding process of the counterweight 42, the high-viscosity silicone grease layer between the inner wall of the radial groove 41 and the outer wall of the counterweight 42 generates viscous damping, which absorbs the high-frequency vibration of the counterweight 42 caused by the slight fluctuation of the rotation speed, so that the excitation force output is stable.

[0051] If it is necessary to change the excitation force adjustment range, the plug 45 on the turntable 4 can be removed after the machine is stopped, and the number of counterweight adjustment pieces 44 on the counterweight block 42 can be increased or decreased through the process hole to change the total mass of the counterweight block 42, thereby adjusting the excitation force range.

[0052] For the improved device equipped with controller 5 and speed sensor 6, speed sensor 6 detects the actual speed of excitation shaft 3 in real time and feeds it back to controller 5. Controller 5 compares the actual speed with the target speed and adjusts the frequency of motor 2 to make the speed approach the target value, thus achieving precise speed maintenance. At the same time, controller 5 monitors the current of motor 2. When the current deviates from the target value, it adjusts the frequency proportionally to change the radial position of counterweight 42, and the excitation force changes accordingly. The current of motor 2 returns to the target value, forming load following control. At this time, pure mechanical negative feedback and electronic control assistance work together. The mechanical loop quickly suppresses speed fluctuations, and the electronic control loop accurately maintains the set operating point.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An automated manufactured sand production apparatus, comprising a screen box (1), a vibrating shaft (3), a turntable (4) fixedly mounted on the vibrating shaft (3), and a motor (2) for driving the vibrating shaft (3) to rotate, characterized in that, Also includes: A radial groove (41) is formed on the turntable (4). A counterweight (42) is slidably disposed in the radial groove (41), and the counterweight (42) slides back and forth between the radial inner end and the radial outer end along the radial direction of the turntable (4); And a return spring (43) disposed between the counterweight (42) and the bottom of the radial groove (41), the return spring (43) always applying a return force toward the radially inner end to the counterweight (42); The centrifugal force experienced by the counterweight (42) when the excitation shaft (3) rotates is balanced by the elastic force of the return spring (43); when the load increases and the speed of the excitation shaft (3) decreases, the counterweight (42) moves to the radial inner end to reduce the excitation force, thereby reducing the load on the motor (2) and suppressing the speed from decreasing further; when the load decreases and the speed increases, the counterweight (42) moves to the radial outer end to increase the excitation force, thereby increasing the load on the motor (2) and suppressing the speed from increasing further; thus forming a speed negative feedback stabilization mechanism.

2. The automated manufactured sand production apparatus according to claim 1, characterized in that, The reset spring (43) is a nonlinear spring, and its stiffness coefficient K increases with the increase of compression x, satisfying: K(x)=K0·[1+β·x], where K0 is the initial stiffness, β is the nonlinear coefficient, and the value of β is 0.5mm. -1 ~2.0mm -1 .

3. The automated manufactured sand production apparatus according to claim 2, characterized in that, The nonlinear spring is a variable pitch helical spring, with a wire diameter of 4mm to 8mm, an effective number of coils of 5 to 10, and a free length to installation length ratio of 1.5 to 2.

5.

4. The automated manufactured sand production apparatus according to claim 1, characterized in that, A high-viscosity silicone grease layer is provided between the counterweight (42) and the radial groove (41). The thickness of the silicone grease layer is 0.1 mm to 0.5 mm, and the dynamic viscosity of the silicone grease is 1000 mPa·s to 10000 mPa·s.

5. The automated manufactured sand production apparatus according to claim 1, characterized in that, The center of mass of the counterweight (42) in the radial direction coincides with the geometric center of the counterweight (42), and the distance between the center of mass of the counterweight (42) and the axis of the excitation shaft (3) is the first eccentricity e1 when the counterweight (42) is at the inner radial end, and the distance is the second eccentricity e2 when the counterweight (42) is at the outer radial end, and e2 = [1.8~3.0]·e1; the preload force F0 of the return spring (43) when the counterweight is at the inner radial end satisfies: F0 ∈ [m·e1·(0.65·ω n ) 2 ,m·e1·(0.7·ω n ) 2 ], where ω n The rated angular velocity of the excitation shaft (3) is given by m, where m is the mass of the counterweight (42). This causes the counterweight (42) to begin sliding outward from the radial inner end when the rotational speed reaches 65% to 70% of the rated speed.

6. The automated manufactured sand production apparatus according to claim 1, characterized in that, There are two turntables (4), which are symmetrically fixed at both ends of the excitation shaft (3). Each turntable (4) is provided with one and only one radial groove (41). The radial grooves (41) on the two turntables (4) are 180° apart in the circumferential direction. The counterweights (42) in the two turntables (4) have the same mass and slide radially synchronously when the excitation shaft (3) rotates, so that the centrifugal forces of the two counterweights (42) are opposite in direction, forming an excitation couple.

7. The automated manufactured sand production apparatus according to claim 1, characterized in that, It also includes a controller (5) and a speed sensor (6) disposed on the excitation shaft (3). The controller (5) is electrically connected to the motor (2) and the speed sensor (6). The controller (5) is configured to receive the actual speed n detected by the speed sensor (6), compare it with the target speed n0, adjust the frequency of the motor (2) to make n approach n0, thereby indirectly controlling the radial position of the counterweight (42) and realizing the auxiliary adjustment of the excitation force.

8. The automated manufactured sand production apparatus according to claim 7, characterized in that, The controller (5) is further configured to: acquire the real-time current value I of the motor (2), calculate the deviation Δi between it and the target current value I0; when |Δi| is greater than a preset threshold, the controller (5) adjusts the frequency of the motor (2) proportionally, so that the speed change Δn = K p ·Δi, where K p The proportional coefficient is used; the change in rotational speed causes the radial position of the counterweight (42) to change, thereby changing the excitation force, so that the current of the motor (2) returns to the target value, forming load following control.

9. The automated manufactured sand production apparatus according to claim 1, characterized in that, The counterweight block (42) is provided with a detachable counterweight adjustment piece (44). The counterweight adjustment piece (44) is fixed to the counterweight block (42) by screws. The number of counterweight adjustment pieces (44) can be increased or decreased by removing the plug (45) on the turntable (4) to change the total mass of the counterweight block (42) and thus adjust the range of vibration force.

10. The automated manufactured sand production apparatus according to claim 1, characterized in that, It also includes a frame (7), which is inclined; the screen box (1) is installed on the frame (7) by a number of vibration springs (8), and the screen box (1) is inclined at the same angle as the frame (7); the higher end of the frame (7) is provided with a feed inlet (9), and the manufactured sand enters the screen box (1) from the feed inlet (9).

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