High-precision micro continuous powder feeding system

Abstract

The invention discloses a high-precision micro continuous powder feeding system, and belongs to experimental devices, the powder feeding system comprises an injection device, a driving device and a conveying device, the injection device comprises a cylinder, one end of the cylinder is inserted into a push rod, the top end of the push rod is a piston, the piston is in interference fit with the cylinder, the other end of the cylinder is a feeding port, and the feeding port is connected with the driving device. The feeding port is inserted into the conveying device, the driving device drives the push rod to stretch out and draw back, and the conveying device conveys through airflow. The problem that an existing powder feeding device is difficult to achieve trace, continuous and accurate powder feeding can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to an experimental device, in particular to a high-precision micro-continuous powder feeding system. BACKGROUND

[0002] With the continuous progress of industrial automation and fine manufacturing technology, various types of powder materials are increasingly widely used in manufacturing and processing processes, and micro-powder feeding devices also play an important role in many fields. When carrying out research on combustion, gasification and other research of coal powder or biomass powder in the laboratory environment, the powder conveying process requires precise control capability to achieve micro, quantitative and point feeding of fine powder to ensure the accuracy of experimental data and the repeatability of the process.

[0003] At present, the commonly used laboratory powder feeding device mainly includes bubble type, impeller type and roller type, such as CN110775659A, a variable pitch hollow screw micro powder feeding device and its design method, CN104061582B, a controllable micro-continuous powder feeding device, and CN201703867U, a hollow screw micro powder feeding device. Although there are many types of existing micro powder feeding devices, there are still several key technical problems to be solved. The bubble type powder feeding device transports the powder after being fluidized by gas. If the gas introduced causes the powder to absorb moisture and agglomerate, the flowability decreases, which can easily cause local accumulation and uneven bubbling, resulting in increased powder feeding fluctuations. The impeller type powder feeding device is prone to powder sticking between the blades when dealing with powders with high viscosity or easy to agglomerate, which can cause impeller jamming or a sharp decrease in powder feeding, and even cause blockage. The roller type powder feeding device relies on the extrusion action between the roller and the cavity to achieve powder feeding. If the powder density distribution is uneven, the pressure applied by the roller will cause unstable powder feeding, making it difficult to achieve continuous and uniform quantitative feeding.

[0004] Therefore, how to design a micro-continuous powder feeding device with high precision, high stability and easy maintenance to solve the above technical problems has become a key issue that needs to be overcome in the current technical field. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a high-precision micro-continuous powder feeding system, and the technical scheme is as follows.

[0006] A high-precision micro-continuous powder feeding system, the powder feeding system comprises an injection device, a driving device and a conveying device, the injection device comprises a cylinder, one end of the cylinder is inserted into a push rod, the top end of the push rod is a piston, the piston and the cylinder are interference fit, the other end of the cylinder is a feeding port, the feeding port is inserted into the conveying device, the driving device drives the push rod to extend and retract, and the conveying device is conveyed by airflow.

[0007] Further, the driving device comprises a stepping motor, a stepping motor driver and a stepping motor controller, the stepping motor controller generates a control signal, and the stepping motor driver receives the control signal and regulates the rotation speed, step distance, forward and reverse direction and start and stop of the stepping motor.

[0008] Further, the push rod is installed on the sliding table through a connecting plate, and the sliding table is embedded in the screw sliding rail, and the stepping motor drives the sliding table to move.

[0009] Further, the conveying device comprises a horizontal pipe, and the feeding port is inserted into the horizontal pipe.

[0010] Preferably, the end surface of the feeding port is low in the middle and high on both sides.

[0011] Further, the conveying device comprises a powder feeding bin, the feeding port is inserted into the vertical section of the powder feeding bin, and the bottom of the powder feeding bin is connected to the horizontal pipe.

[0012] Further, the included angle between the cylinder and the horizontal plane is 30-60 degrees.

[0013] Further, the system further comprises a vibrating device, and the vibrating device drives the injection device to vibrate.

[0014] Preferably, the vibrating device comprises a vibrating motor and a vibrating motor controller.

[0015] Compared with the prior art, the present application has the following beneficial effects: (1) The micro continuous powder feeding device can solve the problem that the existing powder feeding device cannot realize micro, continuous and precise powder feeding.

[0016] (2) The linear motion control of the piston in the micro continuous powder feeding device can avoid powder blockage and accumulation, and is particularly suitable for continuous high-precision powder feeding of powder materials that are easy to absorb moisture, have poor flowability and are easy to agglomerate.

[0017] (3) The linear motion of the piston in the micro continuous powder feeding device has strong controllability of powder feeding rate and extremely small deviation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a front view of the high-precision inclined micro powder feeding device; Figure 2 is a view of the high-precision inclined micro powder feeding device from another angle; Figure 3 is a perspective view of the high-precision inclined micro powder feeding device; Figure 4 is an internal dissection view of the high-precision inclined micro powder feeding device; Figure 5 is a push rod sliding table connection diagram; Figure 6 This is a cross-sectional view of the push rod and piston connection; Figure 7 This is a magnified view of a portion of the powder container; Figure 8 This is a schematic diagram of the device according to Embodiment 1 of the present invention; Figure 9 This is a schematic diagram showing the changes in actual powder feeding rate and expected powder feeding rate with motor speed.

[0019] The components include: 1. Base; 2. Upper support panel; 3. Metal column; 4. Threaded fastener; 5. Micro stepper motor; 6. Screw-driven electric slide rail; 7. Slide table; 8. Connecting screw; 9. Acrylic adapter plate; 10. Push rod; 11. Fastening screw; 12. Rubber head piston; 13. Support plate locking bolt; 14. Acrylic support plate; 15. Needle-shaped cylinder; 16. Hex socket set screw; 17. Powder feeding hopper; 18. Hex lock nut; 19. Feeding assembly; 20. Mounting flange; 21. Flange fixing bolt; 22. Sealing top cover; 23. Fixing bolt; 24. Vibration motor; 25. T-pipe assembly; 26. Conveying straight pipe. Detailed Implementation

[0020] The technical solution of the present invention will be further explained below with reference to the accompanying drawings. Example

[0021] like Figure 8 As shown, a high-precision micro-volume continuous powder feeding system includes an injection device, a driving device, and a conveying device. The injection device includes a cylinder with a push rod inserted into one end. The top of the push rod is a piston, and the piston and the cylinder are interference-fitted. The other end of the cylinder is a feed port, which is inserted into the conveying device. The driving device drives the push rod to extend and retract, and the conveying device conveys the powder through airflow.

[0022] The drive unit includes a stepper motor, a stepper motor driver, and a stepper motor controller. The stepper motor controller generates control signals, and the stepper motor driver receives the control signals and regulates the stepper motor speed, step distance, forward and reverse direction, and start and stop.

[0023] The push rod is mounted on the slide table via a connecting plate. The slide table is fitted into the lead screw and slide rail, and the stepper motor drives the slide table to move.

[0024] The conveying device is a horizontal pipe, with the feed port inserted into it, and the cylinder is vertically positioned. The end face of the feed port is lower in the middle and higher on both sides, and can be U-shaped or V-shaped.

[0025] As an improvement, the system also includes a vibration device, all of which are mounted on a bracket and drive the injection device to vibrate. The vibration device includes a vibration motor and a vibration motor controller.

[0026] The linear electric slide rail 6 uses a lead screw-type linear slide table 7, equipped with a micro stepper motor 5. The system uses a push rod to connect the linear slide table 7 and the push rod 10 via an acrylic plate 9. One end of the push rod 10 is fixed to the acrylic plate 9, and the other end has an opening for mounting a piston rubber head. The diameter of the rubber head piston at the end of the push rod 10 is slightly larger than the inner diameter of the needle-shaped cylinder 15. After assembly, this prevents powder leakage to the rear and ensures that the push rod and piston assembly can slide smoothly along the inner wall of the cylinder. The base slide table and the needle-shaped cylinder 15 are fixed by an acrylic plate 14, ensuring that the cylinder axis is aligned with the push rod 15. After the cylinder axis is aligned with the push rod 15, the piston is squeezed by the cylinder wall, causing elastic deformation and forming an interference fit with the inner wall of the needle-shaped cylinder 15. This fit method effectively prevents complete coaxial assembly and allows the push rod-piston assembly to slide smoothly along the inner wall of the cylinder.

[0027] In terms of electrical control and signal interaction, the miniature stepper motor 5, the stepper motor driver, and the stepper motor controller together constitute a complete stepper drive system, which requires a stepper drive power supply. The stepper motor controller is responsible for generating precise control signals based on a preset program or external input. These signals include pulse signals that determine the motor speed and step distance, direction signals that control the forward and reverse direction of the motor, and switching signals used to start and stop the motor drive. After receiving the instructions output by the controller, the stepper motor driver performs signal decoding and power amplification through its internal circuitry, converting the low-current signal into a high-current output sufficient to drive the miniature stepper motor 5. In the absence of pulse input, the motor has a self-locking capability to stably maintain its current position.

[0028] Meanwhile, the vibration motor 24 works in conjunction with a vibration motor controller and a vibration motor power supply. The vibration motor controller adjusts the vibration frequency of the vibration motor 24 to change the vibration intensity. To accommodate the different flowability differences of various powders, a suitable vibration parameter can be set and locked during the system debugging phase. Furthermore, a structural innovation of this invention lies in designing the feed port into a V-shaped, U-shaped, or arc-shaped shape with inclined surface self-guiding characteristics, which promotes powder convergence towards the central area, effectively reducing powder accumulation at the outlet compared to a flat opening structure.

[0029] The main structure of the device is based on a base 1 fixedly mounted on an optical platform. Three long-stroke vertical lifting slides are installed on the platform's guide rails. Each slide is equipped with adjusting screws for manual precision displacement adjustment, and its position is fixed by a locking device after debugging. In this design, the vibration motor 24 is fixed to the acrylic plate 14 of the cylinder. The excitation force generated by the vibration motor 24 is directly transmitted to the accumulated powder inside the needle-shaped cylinder 15, loosening the agglomerated material and reducing the contact and adhesion between the powder particles and the metal cylinder wall, preventing the material from hardening due to long-term static storage. During quantitative feeding, the vibration intensity remains constant to assist fluidization, ensuring that the volume pushed by the piston is strictly consistent with the actual output volume. A gas pipe 25 is connected to the end of the needle-shaped cylinder 15, used to transport the ejected powder to a designated position via an airflow perpendicular to the paper surface. Example

[0030] like Figures 1-7 As shown, this solution demonstrates a high-precision tilting micro-powder feeding device. The main body of the device adopts a vertical frame structure, with the base 1 serving as the basic support unit of the system. It is fastened to the optical experimental platform with hexagonal screws to ensure the mechanical stability of the bottom. Four precision-machined metal columns 3 are arranged in a vertical array between the upper support panel 2 and the base 1. Each connection node is rigidly locked with threaded fasteners 4, thus constructing a stable support frame. The power core of the system consists of a micro stepper motor 5 and its matching drive control unit. In the absence of pulse input, the motor 5 has a self-locking capability to stably maintain the current position. The linear motion module mainly consists of a lead screw electric slide rail 6 and a slide table 7. The slide table 7 of the module serves as the drive carrier, and its mounting surface is connected and fixed to a customized acrylic adapter plate 9 by two connecting screws 8. The function of the adapter plate 9 is to provide precise interface conversion. Precision positioning holes are pre-drilled on the base plate 9 according to the geometry of the push rod 10. One end of the push rod 10 is inserted into these positioning holes and then rigidly anchored to the adapter base plate 9 by additional fastening screws 11. This design ensures that the motion axes of the push rod 10 and the slide table 7 are highly coaxial and guarantees zero relative displacement of the connection interface when the push rod 10 is in motion, maintaining the transmission accuracy of the entire linear actuator. The other end of the push rod 10 is designed with a special protruding groove structure for mounting a rubber head piston 12. The diameter of this piston is slightly larger than the inner diameter of the needle-shaped cylinder 15. The protrusion at the end of the push rod 10 tightly engages and squeezes the inner wall of the piston, relying mainly on the elasticity and high friction of the material to achieve a stable connection.

[0031] The bottom of the lead screw electric slide rail 6 has a dedicated threaded mounting hole. A bolt 13 is used to lock it in place by passing it from bottom to top through a custom-made acrylic support plate 14. The acrylic support plate 14 has an axial through hole at its center that matches the outer diameter of the needle-shaped cylinder 15, and the cylinder 15 passes through this through hole. The top of the support plate 14 has a radial threaded hole into which a hexagonal set screw 16 is screwed. When the set screw 16 is tightened, its end generates radial pressure and presses against the outer wall of the cylinder, thereby locking the cylinder 15 through friction. The front end of the piston-push rod is coaxially inserted into the inner hole of the needle-shaped cylinder 15. The elastic sealing ring on the outer edge of the piston 12 forms an interference fit sliding seal with the inner wall of the cylinder. A dedicated access interface is provided on the side wall of the powder feeding chamber 17. The needle-shaped cylinder 15, as a lateral insertion element, passes through this interface and extends into the interior of the powder feeding chamber 17. To ensure the stability and sealing of the connection, a hexagonal lock nut 18 is used to fix the joint between the cylinder 15 and the powder feeding bin 17 wall, so that the port of the cylinder 15 can be accurately aligned with the central axis position inside the bin.

[0032] The feeding assembly 19 at the bottom of the powder hopper 17 is typically designed with a V-shaped or U-shaped structure. To ensure a stable connection between this assembly and the horizontal support panel, the top of the feeding assembly 19 is designed with an outwardly extending mounting flange 20. A through hole is pre-drilled in the center of the support panel 2, forming a stepped limiting structure that allows the feeding assembly 19 to pass through from top to bottom. Once the assembly is in place, the lower surface of the flange 20 directly abuts against the upper surface of the support panel 2. Mounting holes are pre-drilled at the four corners of the flange 20, and flange fixing bolts 21 are threaded through these holes and locked to the support panel 2 below. To construct a closed feeding chamber and maintain system pressure balance, a sealing top cover 22 is screwed onto the top port of the powder hopper 17. This assembly, through thread, locks onto the top of the powder hopper 17, forming a reliable static seal interface. This effectively blocks the upward escape path of the gas-solid mixture caused by bottom pneumatic conveying, ensuring the unidirectional stability of the powder conveying flow field and environmental safety. In addition, a vibration motor 24 is fixed to the outer wall of the powder feeding hopper 17 by fixing bolts 23. This motor can set and lock a suitable vibration parameter during the system debugging stage to take into account the differences in the flowability of different powders. The excitation force generated by the motor can effectively break the adhesion between powders and ensure the continuity of powder flow. Under the action of gravity and vibration, the powder is rectified through the discharge port 19 and finally falls into the three-way pipe assembly 25 located at the bottom. The vertical port of the three-way pipe is tightly connected to the discharge port 19. The interface adopts a double-clamping precision pipe joint structure. By tightening the nut, the internal metal clamp is driven to undergo elastic deformation and firmly bite into the discharge pipe wall. The horizontal port of the three-way pipe 25 also adopts a double-clamping connection assembly. One end is connected to the air source and the other end is connected to the conveying straight pipe 26. The horizontally flowing pressurized gas is used to spray and guide the powder material, so that the powder material is suspended in the airflow and pneumatically conveyed to the predetermined position along the conveying straight pipe 26.

[0033] By precisely controlling the rotation of the stepper motor to drive the push rod, which in turn pushes the piston to extrude powder at a constant speed, the following mathematical model is established.

[0034] The linear motion velocity function v(t) of the push rod and the motor control parameters satisfy a specific mathematical relationship, which can be expressed as:

[0035] In the formula, n is the motor speed, r / s; f is the motor speed pulse frequency, Hz (pulses / s); N is the number of pulses per motor revolution, i.e., the total number of pulses that the motor needs to receive for one revolution; p is the lead of the lead screw (i.e., the linear displacement of the slide table per revolution of the lead screw), mm / revolution.

[0036] Based on the above velocity model, the stepper motor drives the powder inside the cylinder to be discharged at a volumetric rate per second. The volumetric discharge can be estimated using the inner diameter of the powder storage pipe. Assuming the cylinder cross-section is completely filled and leak-free during piston movement, the formula for calculating this volumetric discharge is as follows:

[0037] In the formula, d is the inner diameter of the powder storage tube, in mm.

[0038] Furthermore, in order to achieve precise control over the feed quality, the bulk density of the powder is considered. This allows us to determine the mass discharge rate per second of powder pushed by the stepper motor inside the cylinder. Based on the physical relationship that mass discharge equals volume discharge multiplied by powder density, substituting and rearranging the aforementioned volumetric calculation formula, this formula intuitively reflects the direct linear control relationship between pulse frequency and mass flow rate, as shown below:

[0039] This model shows that, given a fixed set of mechanical parameters, high-precision control of the powder feeding rate can be achieved in the device simply by adjusting the pulse frequency output by the stepper motor.

[0040] The difference from Embodiment 1 is that the angle between the cylinder and the horizontal plane is 30 to 60 degrees. The conveying device also includes a powder feeding hopper, with the feed port inserted into the vertical section of the powder feeding hopper, and the bottom of the powder feeding hopper connected to a horizontal pipe.

[0041] The system's vibration device is installed on the powder feeding hopper, and the vibration of the powder feeding hopper indirectly drives the injection device to vibrate.

[0042] The tilt angle of the cylinder overcomes the problem that when the cylinder is vertical, the packing pressure of the powder increases, resulting in a larger packing density of the powder, which makes it easy for the powder to agglomerate unevenly and affect the accuracy.

[0043] When the cylinder is tilted, to further address the tendency of powder to bridging, the vibrating motor 24 is fixed to the side wall of the powder feeding hopper 17. High-frequency vibration actively breaks up material bridging, ensuring a continuous and uniform feeding process. The powder material settles from the powder feeding hopper 17 into the vertical inlet of the three-way pipe assembly 25 by gravity. The horizontal channel of the three-way pipe assembly 25 is connected to an air source, using horizontally flowing pressurized gas to spray, guide, and carry the powder material, suspending it in the airflow and pneumatically conveying it to the predetermined position along the conveying pipe 26. Example

[0044] The apparatus of Implementation 2 was selected, and the following specific parameters and experiments were set to verify the effectiveness of the apparatus.

[0045] 1. Component composition and parameters The linear electric slide rail uses a lead screw-type linear slide table with a lead screw diameter of 6mm, a pitch of 1mm, and an effective stroke of 300mm. It is equipped with a 28-type stepper motor with 800 pulses per revolution. An acrylic plate connects the linear slide table and the push rod. The push rod is made of stainless steel, with an outer diameter of 4.3mm and a length of 300mm. One end is fixed to an adapter plate, and the other end has an opening for mounting a piston rubber head. The stainless steel cylinder has an inner diameter of 5mm, an outer diameter of 6mm, and a length of 300mm, with open ends. The slide rail is fixed to the stainless steel cylinder via an acrylic plate, ensuring that the cylinder axis is completely coaxial with the push rod and that the push rod-piston assembly can slide smoothly along the inner wall of the cylinder. A miniature DC brushless vibration motor is used, fixed to the side of the powder feeding hopper. Both the vibration motor and the stepper motor are started simultaneously. The experiment is equipped with a high-precision electronic balance with an accuracy of 0.001g for accurate weighing of trace amounts of powder. The test material is pine wood powder with a density of 0.327 g / cm3 and a particle size of 120-200 mesh. It is dried at 105℃ for 12 hours before use to remove moisture and prevent clumping.

[0046] 2. Testing Process Slowly pour the pretreated pine powder into the stainless steel cylinder, gently tapping the outer wall of the cylinder during filling to ensure a uniform initial buildup. Turn on the stepper motor controller and set the speed pulse frequency to 1000Hz, at which point the stepper motor speed is 1.25 r / s. Start the vibration motor controller to synchronize the vibration motor and stepper motor. Feed powder at preset times of 20s, 30s, 40s, 50s, and 60s. After each feeding, collect the powder falling from the outlet using the pretreated weighing boat, immediately weigh it with an electronic balance, record the data, empty the weighing boat, and proceed to the next test.

[0047] Following the steps above, the speed pulse frequency was adjusted sequentially to 250Hz, 500Hz, 750Hz, and 1250Hz, corresponding to stepper motor speeds of 0.3125r / s, 0.625r / s, 0.9375r / s, and 1.5625r / s, respectively. The tests at all time points were repeated. The powder feeding rate for each test group was calculated, i.e., the powder feeding rate is equal to the powder mass divided by the powder feeding time. The average value and standard deviation of the powder feeding rate at different powder feeding times under the same motor speed were taken. At the same time, the expected powder feeding rate corresponding to different motor speeds was calculated according to formula (3), and the relative error was calculated by comparing it with the average value of the actual powder feeding rate. The comparison results are as follows: Figure 9 As shown.

[0048] 3. Results Analysis The actual average powder feeding rate closely matches the predicted value, with deviations all ≤ 0.00016 g / s. Furthermore, the deviation increases strictly linearly with increasing motor speed, demonstrating the strong controllability of the powder feeding rate. The standard deviation of the actual powder feeding rate at each speed is ≤ 2.51 × 10⁻⁴ g / s, indicating that the device maintains continuous and stable powder feeding under different operating conditions, without powder interruption, powder accumulation, or sudden changes in flow rate. Based on the actual and predicted values, the relative errors at each speed are 4.65%, 2.90%, 1.93%, 0.94%, and 1.41%, respectively, with a maximum relative error of 4.65%. The overall error is controlled within 5%, fully demonstrating the device's precise powder feeding capability.

Claims

1. A high-precision micro-volume continuous powder feeding system, characterized in that, The powder feeding system includes an injection device, a driving device, and a conveying device. The injection device includes a cylinder with a push rod inserted into one end. The top of the push rod is a piston, and the piston and the cylinder are interference-fitted. The other end of the cylinder is a feed port, which is inserted into the conveying device. The driving device drives the push rod to extend and retract, and the conveying device conveys the powder through airflow.

2. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The driving device includes a stepper motor, a stepper motor driver, and a stepper motor controller. The stepper motor controller generates control signals, and the stepper motor driver receives the control signals and adjusts the stepper motor speed, step distance, forward and reverse direction, and start and stop.

3. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The push rod is mounted on the slide table via a connecting plate. The slide table is fitted into the lead screw and slide rail, and the stepper motor drives the slide table to move.

4. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The conveying device includes a horizontal pipe, and the feed port is inserted into the horizontal pipe.

5. The high-precision micro-volume continuous powder feeding system according to claim 4, characterized in that, The end face of the feed port is lower in the middle and higher on both sides.

6. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The conveying device includes a powder feeding hopper, a feed port inserted into the vertical section of the powder feeding hopper, and a horizontal pipe connected to the bottom of the powder feeding hopper.

7. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The angle between the cylinder and the horizontal plane is 30 to 60 degrees.

8. The high-precision micro-volume continuous powder feeding system according to claim 1, characterized in that, The system also includes a vibration device that drives the injection device to vibrate.

9. The high-precision micro-volume continuous powder feeding system according to claim 8, characterized in that, The vibration device includes a vibration motor and a vibration motor controller.

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