Concrete mixer with anti-clogging rotary scraper

Abstract

The present application relates to a kind of concrete mixer with anti-blocking rotary scraper, belong to concrete mixing technical field.It include mixing bin, stirring shaft, controller and stirring motor, the outer side wall of stirring shaft is equipped with multiple telescopic mechanisms, the telescopic end of each telescopic mechanism is connected with scraper blade, multiple telescopic mechanisms are installed on the outer side wall of stirring shaft and are distributed in spiral, controller real-time monitoring the load current of stirring motor, controller gradually adjusts the telescopic amount of telescopic mechanism according to the load current change of real-time monitoring, when load current is less than 80% of preset value, telescopic mechanism contracts and expands the gap between scraper blade and mixing bin inner wall to 8~10m, when load current exceeds 120% of preset value, telescopic mechanism extends and reduces the gap between scraper blade and mixing bin inner wall to 2~4mmm, the present application solves the problem of how to adjust scraper gap adaptively according to the dynamic change of material characteristics in mixing process to realize efficient anti-blocking.

Description

Technical Field

[0001] This invention belongs to the field of concrete mixing technology, specifically relating to a concrete mixer with an anti-clogging rotating scraper. Background Technology

[0002] As a key piece of equipment widely used in the construction engineering field, concrete mixers in modern construction practice are no longer limited to the preparation and processing of conventional concrete materials. They increasingly face the challenge of mixing highly adhesive or wet materials. Due to their unique physicochemical properties, these materials easily adhere to the inner wall of the mixing drum during mixing, gradually accumulating in the discharge area to form a dense agglomerate layer. This agglomerate layer not only significantly reduces discharge efficiency, but when the accumulation reaches a critical point, it can completely block the discharge channel, forcing the entire mixing operation to stop. At this point, the machine must be stopped, and operators must enter the mixing chamber for manual cleaning, which is not only inefficient but also poses significant safety hazards.

[0003] To address the aforementioned technical problems, a common improvement approach in existing technologies is to fix a scraper structure onto the mixing blades. The relative motion between the scraper and the inner wall of the mixing drum continuously scrapes away material remaining on the inner wall during mixing, thereby reducing the amount of material adhering to the inner wall. Alternatively, a cylinder can be used to drive the scraper, causing it to contact the inner wall of the mixing chamber and perform intermittent scraping. This design improves the material adhesion problem to a certain extent. Furthermore, by installing an adjustment device between the scraper and the support plate, the gap between the scraper and the inner wall of the mixing drum can be mechanically adjusted to adapt to the needs of different material properties.

[0004] However, the limitations of the scraper gap adjustment mechanism severely restrict the equipment's adaptability. Although existing technologies incorporate adjustment devices between the scraper and the support plate, these adjustments are mostly pre-shipment adaptations or achieve contact and separation control within a very limited range. They cannot adjust the scraping intensity in real time based on dynamic changes in the material's state during operation. When the viscosity or moisture content of the material fluctuates, a fixed or simply switching scraper gap cannot effectively match the material's characteristics. A gap that is too small will exacerbate wear between the scraper and the cylinder wall and may lead to jamming; a gap that is too large will fail to effectively remove adhering material.

[0005] Therefore, how to adaptively adjust the scraper gap according to the dynamically changing material characteristics during the mixing process to achieve efficient anti-clogging is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a concrete mixer with an anti-clogging rotary scraper, which solves the problem of how to adaptively adjust the scraper gap according to the dynamically changing material characteristics during the mixing process to achieve efficient anti-clogging.

[0007] The objective of this invention can be achieved through the following technical solution: A concrete mixer with an anti-clogging rotating scraper, comprising a mixing chamber, a mixing shaft, a controller, and a mixing motor, characterized in that: the outer wall of the mixing shaft is provided with multiple telescopic mechanisms, each of which has a scraper blade connected to its telescopic end; the multiple telescopic mechanisms are installed on the outer wall of the mixing shaft and arranged in a spiral shape; the controller monitors the load current of the mixing motor in real time during the mixing process; the controller gradually adjusts the telescopic amount of the telescopic mechanisms according to the real-time monitored load current changes; when the load current is lower than 80% of a preset value, the telescopic mechanism contracts to expand the gap between the scraper blade and the inner wall of the mixing chamber to 8-10 mm; when the load current exceeds 120% of the preset value, the telescopic mechanism extends to reduce the gap between the scraper blade and the inner wall of the mixing chamber to 2-4 mm.

[0008] As a preferred embodiment of the present invention, the mixing chamber is equipped with a viscosity detector, which intermittently detects the viscosity of the material being mixed in the mixing chamber. The controller compares the detection result of the viscosity detector with the real-time monitored load current, and adjusts the mixing speed of the mixing shaft according to the comparison result.

[0009] As a preferred embodiment of the present invention, the scraper blade is connected to a telescopic mechanism via a universal joint and is equipped with a micro servo motor, which adjusts the angle of the scraper blade according to a preset stirring stage.

[0010] As a preferred embodiment of the present invention, the controller adjusts the rotational speed of the stirring shaft according to the adjustment angle of the micro servo motor.

[0011] As a preferred technical solution of the present invention, a concrete mixer with an anti-clogging rotating scraper according to claim 1 is characterized in that: the outer wall of the telescopic mechanism is provided with a quick-release bushing, the quick-release bushing can extend and retract accordingly with the extension and retraction of the telescopic mechanism, one end of the quick-release bushing is sleeved on the top surface of the telescopic end, and the other end is sleeved on the tail of the fixed end of the telescopic mechanism.

[0012] As a preferred embodiment of the present invention, an observation window is provided on the top surface of the mixing chamber.

[0013] As a preferred embodiment of the present invention, the mixing chamber is provided with a gearbox on one side of the mixing motor, the mixing shaft is meshed with the output end of the gearbox through a driven gear, and the output end of the mixing motor is drivenly connected to the input end of the gearbox.

[0014] As a preferred embodiment of the present invention, the top surface of the mixing chamber is provided with a feed inlet, and a feed funnel is provided above the feed inlet.

[0015] As a preferred embodiment of the present invention, the viscosity detector uses an ultrasonic detector to detect the viscosity of the stirred material.

[0016] The beneficial effects of this invention are as follows: by indirectly judging the viscosity of concrete by real-time monitoring of the motor load current, the automatic and dynamic adjustment of the scraper gap is realized, which not only effectively prevents material accumulation and blockage on the inner wall of the mixing chamber, but also avoids excessive wear of the scraper, extends the service life of the equipment, and solves the problem of how to adaptively adjust the scraper gap according to the dynamically changing material characteristics during the mixing process to achieve efficient anti-blocking. Attached Figure Description

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a front view of the structure of the present invention; Figure 3 This is a partial structural diagram of the mixing chamber of the present invention; Explanation of key component markings: In the diagram: 1. Mixing chamber; 2. Mixing shaft; 3. Mixing motor; 4. Gearbox; 5. Telescopic mechanism; 6. Scraper blade; 7. Observation window; 8. Feed funnel; 9. Controller; 10. Universal joint. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0020] Please see Figures 1-3This embodiment provides a concrete mixer with an anti-clogging rotating scraper, including a mixing chamber 1, a mixing shaft 2, a controller 9, and a mixing motor 3. The outer wall of the mixing shaft 2 is equipped with multiple telescopic mechanisms 5, each with a scraper blade 6 connected to its telescopic end. These multiple telescopic mechanisms 5 are installed on the outer wall of the mixing shaft 2 and arranged in a spiral pattern. During concrete mixing, when mixing high-viscosity or low-slump (dry-hard) concrete, the material easily adheres to the inner wall of the mixing chamber 1, forming clumps, leading to decreased mixing efficiency, poor discharge, or even blockage. Traditional mixers have a fixed gap between the scraper and the inner wall, making it impossible to dynamically adjust the scraping intensity according to the viscosity of different materials. If the gap between the scraper and the inner wall is too small, scraper wear will be accelerated under high-flow material conditions. This is because when the scraper rotates at high speed, the concrete contains a large amount of free sand particles and cement paste. These sand-containing, high-flow pastes will continuously scour the scraper surface like sandpaper or abrasive water jets. Moreover, if the gap is too small, the flow velocity will increase sharply when the high-flow paste is forced through this narrow gap. The higher the flow velocity, the greater the impact kinetic energy of the abrasive particles on the scraper edge, causing the wear rate of the scraper blade 6 to increase exponentially. On the other hand, if the gap is too large, dry-hard concrete has extremely high yield stress, meaning that a sufficiently large force must be applied for it to begin to flow. When the gap between the scraper and the inner wall is too large, the scraper edge cannot effectively remove the material adhering to the inner wall. When sufficient normal compressive force is applied to the material layer, the scraper merely "slides" or "skims" across the surface of the material layer, unable to cut into the bottom of the material layer and remove it from the wall. Therefore, the scraper can only remove the protruding parts, but will leave a thin, dense residual layer on the inner wall surface. This residual layer is not removed, and during subsequent mixing, new material continuously adheres to this "base," causing the residual layer to become thicker and thicker. During the mixing and discharge process, the cement continues to undergo hydration reactions, and the surface moisture is absorbed or evaporated by the new material. The residue will quickly harden, forming a solid cement stone shell, eventually causing the discharge port to crust, become blocked, or even jam the scraper mechanism. This is why traditional fixed-gap mixers must be stopped periodically for manual cleaning with hammers.

[0021] Therefore, when the mixer starts, the mixing motor 3 drives the mixing shaft 2 to rotate, and the scraper blade 6 revolves with the mixing shaft 2 and scrapes the inner wall of the mixing chamber 1. The controller 9 continuously collects the load current signal of the mixing motor 3 at a set sampling frequency. When the controller 9 detects that the load current is lower than 80% of the rated value, it indicates that the concrete is in a high fluidity state and the mixing resistance is small. The controller 9 sends a contraction command to the telescopic mechanism 5 to expand the gap between the scraper blade 6 and the inner wall of the mixing chamber 1 to 8-10 mm to reduce the ineffective friction between the scraper and the inner wall and reduce wear. During the concrete mixing process, as the hydration reaction continues, free water is constantly consumed and new hydration products are generated. At the same time, the newly generated hydration products will cause the internal structure of the paste to tend to coagulate, leading to the mixing... As the viscosity of the concrete continues to increase, when the controller 9 detects a continuous rise in the load current of the mixing motor 3, it indicates that the concrete is becoming drier and thicker, increasing the risk of adhesion. The controller 9 then actively adjusts the extension of the telescopic mechanism 5 to reduce the gap between the scraper blade 6 and the mixing chamber 1, thereby increasing the scraping force. When the controller 9 detects that the load current exceeds 120% of the rated value, it indicates that the concrete is in a state of high adhesion and low slump (drier and thicker). At this time, the mixing resistance increases significantly. The controller 9 then issues an extension command to the telescopic mechanism 5, which pushes the scraper blade 6 towards the inner wall of the mixing chamber 1, reducing the gap between the scraper blade 6 and the inner wall of the mixing chamber 1 to 2-4 mm to enhance the scraping force and forcefully remove the concrete clumps adhering to the inner wall.

[0022] By indirectly judging the viscosity of concrete by real-time monitoring of motor load current, the automatic and dynamic adjustment of scraper gap is realized. This effectively prevents material accumulation and blockage on the inner wall of mixing chamber 1, avoids excessive wear of scrapers, extends equipment service life, and solves the problem of how to adaptively adjust scraper gap according to the dynamically changing material characteristics during mixing to achieve efficient anti-blocking.

[0023] Although the viscosity of concrete can be determined by monitoring the load current of the mixing motor 3, an increase in current may be due to the material thickening, excessive feeding, blade wear, changes in bearing resistance, or other factors. A single signal source cannot distinguish between these situations and may lead to misjudgment. Therefore, to avoid misjudgment that may be caused by a single signal source and to improve the reliability of the system, in this embodiment, a viscosity detector is installed in the mixing chamber 1. The viscosity detector intermittently detects the viscosity of the material being mixed in the mixing chamber 1. The controller 9 compares the detection result of the viscosity detector with the real-time monitored load current. Based on the comparison result, the controller 9 adjusts the mixing speed of the mixing shaft 2. During the operation of the mixer, the controller 9 continuously collects the motor load current as the main control signal. Meanwhile, the viscosity detector starts its detection program at set intervals to collect the viscosity data of the material. The controller 9 compares the detection result of the viscosity detector with the motor load current at the same time. If both indicate high viscosity, the controller 9 confirms that the material is indeed in a high-adhesion state and maintains the instruction to reduce the gap. If the current indicates high viscosity but the viscosity detection value is normal, the controller 9 determines that the current increase may be due to equipment malfunction, issues an equipment status malfunction alarm signal, and temporarily suspends gap adjustment. If both indicate low viscosity, the controller 9 confirms that the material is in a high-flowability state and maintains the instruction to expand the gap. At the same time, when the material viscosity is high, the rotation speed is appropriately increased to enhance the stirring effect; when the material flowability is good, the rotation speed is appropriately reduced to save energy. By providing continuous and real-time monitoring of the current signal and the viscosity detector providing an independent verification signal, the two complement each other. Through comparison and verification, misjudgment that may be caused by a single signal source is effectively avoided, ensuring both the real-time performance of the control and improving the reliability of the system.

[0024] During concrete mixing, various materials need to be thoroughly mixed. Unevenly mixed concrete has poor workability, and coarse aggregates are prone to separating from cement paste, resulting in segregation and bleeding. Segregated concrete has poor density after pouring, while bleeding increases the water-cement ratio and reduces strength. The scraper blade 6 needs a large angle (angle with the cylinder wall) to efficiently scrape away the material adhering to the inner wall of the mixing chamber 1, thus solving the problems of incomplete discharge and blockage. From a mechanical decomposition perspective, the cutting force of the scraper on the material can be decomposed into two directions: normal force (perpendicular to the cylinder wall), which presses the scraper against the cylinder wall; and tangential force (parallel to the cylinder wall / rotation direction), which propels the material forward. Therefore, the larger the angle, i.e., when the scraper is closer to 90°, the greater the normal force. According to the friction formula: friction force = coefficient of friction × normal force, the greater the normal force, the stronger the scraper's ability to cut into the adhering layer. For dry-hard concrete with high yield stress, only sufficient normal force can break through its surface tension and scrape off the hardened layer firmly attached to the wall. When the inclination angle is smaller, the horizontal orientation provides the greatest tangential thrust, driving the material to rotate at high speed in the horizontal plane, generating a strong shear flow, thereby breaking up cement clumps and achieving microscopic uniform mixing. Furthermore, the axial reaction force on the scraper is small in the horizontal orientation, minimizing the impact on the telescopic mechanism 5 and the universal joint 10. Therefore, to assist in turning the material during the mixing stage to improve mixing quality, and to strengthen wall scraping during the discharge stage to ensure thorough discharge, in this embodiment, the scraper blade 6 is connected to the telescopic mechanism 5 via the universal joint 10 and is equipped with a micro servo motor. The micro servo motor adjusts the angle of the scraper blade 6 according to the preset mixing stage. During the feeding stage, the controller 9 instructs the micro servo motor to move the scraper blade 6... With the tilt angle adjusted to 5°–10°, the scraper assists in the even dispersion of newly added material within the mixing chamber 1 at a relatively small angle, preventing material accumulation near the feed inlet. During the mixing phase, the controller 9 instructs the micro servo motor to adjust the scraper blade 6 tilt angle to 15°–20°. While cleaning the inner wall, the scraper applies a tumbling force to the material at a moderate angle, turning the material at the bottom upwards and assisting the mixing blades in achieving more thorough mixing. When mixing is complete and discharge is initiated, the controller 9 instructs the micro servo motor to adjust the scraper blade 6 tilt angle to 50°–60°. The scraper then uses a large tilt angle to forcefully scrape the material towards the discharge outlet, ensuring that the material in the chamber is discharged as completely as possible. By automatically switching the scraper tilt angle at different mixing stages, the mixing and scraping functions are integrated, allowing the mixing phase to assist in turning the material to improve mixing quality, and the discharge phase to strengthen the scraping of the wall to ensure thorough discharge.

[0025] To ensure uniform mixing during the stirring stage and thorough discharge during the discharging stage, in this embodiment, the controller 9 adjusts the rotation speed of the stirring shaft 2 according to the adjustment angle of the micro servo motor. While adjusting the scraper tilt angle to 15° to 20°, the controller 9 maintains the rotation speed of the stirring shaft 2 at 40 to 60 rpm to ensure that the stirring blades have sufficient linear velocity to fully mix the material. At the same time, the scraper assists in turning the material at a moderate angle and moderate speed. When the scraper tilt angle is adjusted to 50° to 60°, the controller 9 reduces the rotation speed of the stirring shaft 2 to 25 to 35 rpm. By allowing the scraper to scrape along the inner wall at a lower linear velocity and a larger tilt angle, it ensures that every part of the inner wall is fully scraped, improving scraping accuracy and smooth discharge.

[0026] Since the telescopic mechanism 5 comes into direct contact with highly abrasive concrete slurry during operation, in order to prevent cement slurry from seeping into the gaps of the telescopic mechanism 5 and causing it to solidify and jam, in this embodiment, a quick-release bushing is provided on the outer wall of the telescopic mechanism 5. One end of the quick-release bushing is fitted onto the top surface of the telescopic end, and the other end is fitted onto the tail of the fixed end of the telescopic mechanism 5. The sealing effect of the quick-release bushing protects the body of the telescopic mechanism 5, thereby preventing cement slurry from seeping into the gaps of the telescopic mechanism 5 and affecting the telescopic movement. This effectively prevents cement slurry from seeping into the interior of the telescopic mechanism 5 and causing jamming, thus reducing the number of maintenance operations.

[0027] The mixing chamber 1 is in a closed state during the mixing process, and operators cannot directly observe the mixing status of the materials inside the chamber or the working condition of the scraper. When problems such as abnormal material clumping, scraper jamming, or uneven mixing occur, operators find it difficult to detect them in time. Often, they only realize there is a problem when discharging the material, resulting in material waste and project delays. Therefore, in order to facilitate timely detection and intervention by operators, in this embodiment, an observation window 7 is provided on the top surface of the mixing chamber 1. During the operation of the mixer, operators can directly observe the mixing status inside the mixing chamber 1 through the transparent window of the observation chamber. This allows operators to observe the internal condition of the mixing chamber 1 in real time without stopping the machine and opening the cover, reducing equipment failures and material waste caused by blind operation.

[0028] To improve mixing efficiency and meet the high torque requirements of mixing operations, in this embodiment, a gearbox 4 is provided on one side of the mixing motor 3 in the mixing chamber 1. The mixing shaft 2 is connected to the output end of the gearbox 4 via a driven gear. The output end of the mixing motor 3 is connected to the input end of the gearbox 4. After the mixing motor 3 is started, the output shaft of the motor drives the input shaft of the gearbox 4 to rotate. The driving gear on the input shaft drives the driven gear that meshes with it to rotate. The driven gear drives the mixing shaft 2 to rotate. The mixing shaft 2 drives the telescopic mechanism 5 and the scraper blade 6 on it to rotate in the mixing chamber 1 to mix and scrape the material. By reducing the high speed and low torque output of the motor through the gear, it becomes a low speed and high torque output, which meets the high torque requirements of the mixing operation. At the same time, the gear transmission has high efficiency and strong load-bearing capacity, making it suitable for heavy-duty conditions in concrete mixing.

[0029] To reduce dust emission and material spillage during the feeding process, in this embodiment, the top surface of the mixing chamber 1 is also provided with a feed inlet, and a feed funnel 8 is provided above the feed inlet. The conical guide structure of the feed funnel 8 reduces dust emission and material spillage during the feeding process, and at the same time, it can better control the feeding speed, so that the material enters the mixing chamber 1 evenly, avoiding motor overload and uneven mixing caused by feeding too fast.

[0030] Traditional invasive viscosity detectors require direct contact with concrete materials, and the probe surface is prone to concrete slurry adhesion and solidification, leading to detection failure or even probe damage. Furthermore, invasive probes are subject to impact and wear during mixing, resulting in high maintenance costs. Therefore, to avoid sensor blockage and wear caused by solidified concrete, this embodiment uses an ultrasonic detector to measure the viscosity of the mixed material. When viscosity measurement is required, the controller 9 sends a detection command to the ultrasonic detector. The ultrasonic transmitting probe emits ultrasonic pulses of a specific frequency into the concrete material in the mixing chamber 1. As the ultrasonic waves pass through the concrete material, their propagation speed, attenuation, and reflection characteristics change depending on the material's viscosity. The more viscous the material, the greater the sound wave attenuation and the slower the propagation speed. The ultrasonic receiving probe receives the sound wave signal that has passed through or been reflected back from the material, converts it into an electrical signal, and sends it to the controller 9. The controller 9 calculates the current viscosity of the concrete material by analyzing parameters such as the sound wave propagation time and amplitude attenuation. Throughout the entire detection process, the ultrasonic detector probe does not have any physical contact with the concrete material, fundamentally avoiding the problems of sensor blockage and wear caused by solidified concrete.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A concrete mixer with an anti-clogging rotating scraper, comprising a mixing chamber, a mixing shaft, a controller, and a mixing motor, characterized in that: The outer wall of the stirring shaft is provided with multiple telescopic mechanisms. Each telescopic mechanism is connected to a scraper blade at its telescopic end. The multiple telescopic mechanisms are installed on the outer wall of the stirring shaft and are distributed in a spiral shape. The controller monitors the load current of the stirring motor in real time during the stirring process. The controller gradually adjusts the telescopic amount of the telescopic mechanism according to the real-time monitored load current changes. When the load current is lower than 80% of the preset value, the telescopic mechanism retracts to expand the gap between the scraper blade and the inner wall of the stirring chamber to 8~10 mm. When the load current exceeds 120% of the preset value, the telescopic mechanism extends to reduce the gap between the scraper blade and the inner wall of the stirring chamber to 2~4 mm.

2. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The mixing chamber is equipped with a viscosity detector, which intermittently detects the viscosity of the material being mixed in the mixing chamber. The controller compares the detection result of the viscosity detector with the real-time monitored load current, and adjusts the mixing speed of the mixing shaft according to the comparison result.

3. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The scraper blade is connected to a telescopic mechanism via a universal joint and is equipped with a micro servo motor. The micro servo motor adjusts the angle of the scraper blade according to a preset stirring stage.

4. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The controller adjusts the rotational speed of the stirring shaft based on the adjustment angle of the micro servo motor.

5. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The outer wall of the telescopic mechanism is fitted with a quick-release bushing, which can extend and retract accordingly with the telescopic mechanism. One end of the quick-release bushing is fitted on the top surface of the telescopic end, and the other end is fitted on the tail of the fixed end of the telescopic mechanism.

6. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: An observation window is provided on the top surface of the mixing chamber.

7. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The mixing chamber is equipped with a gearbox on one side of the mixing motor. The mixing shaft is meshed with the output end of the gearbox via a driven gear. The output end of the mixing motor is connected to the input end of the gearbox.

8. A concrete mixer with an anti-clogging rotating scraper according to claim 1, characterized in that: The top surface of the mixing chamber is also provided with a feed inlet, and a feed funnel is provided above the feed inlet.

9. A concrete mixer with an anti-clogging rotating scraper according to claim 2, characterized in that: The viscosity detector uses an ultrasonic detector to detect the viscosity of the stirred material.

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