Balancing device and method for a screw pusher

Abstract

This invention proposes a balancing device for a screw feeder, which is achieved through the following technical solution: A dynamic balancing fixture is fabricated, and the screw feeder is separately mounted on the machine base using this fixture, ensuring that the bearings and other support conditions are essentially the same as during the overall machine assembly. A portable dynamic balancing instrument is used for data acquisition and analysis to adjust the calibration and testing quality until the vibration meets the acceptable standards.

Description

Technical Field

[0001] This invention relates to a balancing device and method for a screw feeder, specifically a balancing device and method, belonging to the field of engineering machinery technology. Background Technology

[0002] A horizontal screw press is a widely used processing equipment in solid-liquid separation applications. Its working principle involves a rotating drum and a screw conveyor rotating in the same direction at a certain differential speed. A fluid suspension composed of liquid and solids is continuously introduced into the screw conveyor through the feed pipe. After acceleration, it enters the rotating drum. Under centrifugal force, the heavier solids deposit on the drum wall, forming a sludge layer. The screw conveyor continuously pushes the deposited solids to the conical drum, where they are discharged through the sludge outlet. The resulting clear liquid flows to the other end of the drum and is discharged through the overflow outlet. Since the rotating drum and screw conveyor rotate at high speed in the same direction around the same axis, the vibration characteristics of the entire machine are a composite of their vibration responses. The maximum amplitude is typically required to be controlled within the smallest possible range to improve the overall quality and maintain the machine's reliability.

[0003] Currently, to ensure the overall machine vibration amplitude meets standards, the drum and screw feeder are individually dynamically balanced on a dynamic balancing machine before assembly to ensure that vibrations caused by imbalance meet standards. Assembly errors are controlled during final assembly, thus ensuring the overall machine vibration amplitude meets standards. However, during production, the vibration amplitude of some products (high-speed and large length-to-diameter ratio products) increases significantly with increasing speed, exceeding standards. Through elimination, it was found that the vibration amplitude usually meets requirements when the drum is running alone, indicating that the screw feeder's vibration amplitude is excessive. Since the dynamic balancing machine's maximum balancing speed is only 900 r / min, while the horizontal screw centrifuge's operating speed is generally 3000 r / min-5000 r / min, far exceeding the dynamic balancing machine's balancing speed, it can be determined that the screw feeder has bent and deformed at operating speeds, disrupting the balance at low speeds and causing increased vibration amplitude. Summary of the Invention

[0004] The purpose of this invention is to provide a balancing device and method for a screw feeder to solve the problem of excessive vibration amplitude during operation of a high-speed, large aspect ratio screw feeder.

[0005] A balancing device for a screw feeder is provided. The two ends of the screw feeder are rotatably mounted on a base via bearing assemblies. One end of the screw feeder is connected to a power output device, the speed of which is adjustable. A correction mass and a test mass are welded to the back of the blades. The selection of the test mass size and its position along the axial direction of the screw feeder should cause a change in the vibration vector at the first-order flexible balance speed. The correction mass is used to eliminate the influence of the unbalance at the first-order flexible balance speed.

[0006] The technical solution further defined in this invention is as follows:

[0007] Furthermore, the large end of the screw feeder is connected to the large end fixture via a fixing device, and the small end of the screw feeder is connected to the small end fixture via a fixing device. The large end fixture and the small end fixture are respectively installed and fixed on the machine base via bearing assemblies to form a simply supported beam structure.

[0008] Furthermore, the end of the large-end tooling is equipped with a pulley, which is connected to a motor assembly via a belt drive. The motor assembly is an adjustable-speed motor.

[0009] Furthermore, the surface roughness, dimensional tolerances, and geometric tolerances of the large-end tooling, small-end tooling, bearing assembly, and machine base mounting parts are the same as those of the entire screw feeder during assembly.

[0010] A balancing method for a screw feeder involves using a portable or other type of dynamic balancing instrument in conjunction with the aforementioned balancing device for the screw feeder to collect and analyze data. The support conditions for the new rotor are essentially the same as those during the assembly of the horizontal screw press. Dynamic balancing is then performed according to the following general steps:

[0011] S1 selects the balance correction surface, which is located at a position 20-30% of the length from both ends of the screw feeder. This can reduce the impact of the added counterweight on the flow of the liquid phase and the pushing of the solid phase.

[0012] S2 performs low-speed dynamic balancing on the screw feeder at 20% of its operating speed to eliminate rigid imbalance.

[0013] S3 accelerates the screw feeder to a preset safe speed close to the first-order critical speed, which is called the first-order flexible balance speed. It records the vibration reading under steady-state conditions. Before recording, it must be confirmed that the reading is repeatable.

[0014] S4. Add a set of test masses to the screw feeder. The selection of the size of the test masses and their placement along the axial direction of the screw feeder should cause the vibration vector to change at the first-order flexible equilibrium speed. The test mass set consists of masses located at both ends of the screw feeder and at the center of mass, where the mass at the center of mass is M and the mass at both ends of the rotor is M / 2, so as not to disturb the low-speed balance.

[0015] S5 increases the speed of the screw feeder to the same speed as in S3 and records the new vibration readings under the same operating conditions;

[0016] S6 calculates the influence of the test mass group at first-order flexible balance by the vector change of the readings between S3 and S5, and then calculates the magnitude and phase of a set of correction masses to eliminate the influence of the unbalance at the first-order flexible balance speed, and adds this correction mass.

[0017] S7 Repeat steps S3-S6 until the vibration is acceptable.

[0018] This invention determines the position and weight values ​​of the test mass and correction mass through experimental data, effectively reducing rotor imbalance at high speeds and thus reducing vibration values.

[0019] The technical solution further defined in this invention is as follows:

[0020] Furthermore, at the end of S7, the screw feeder should be able to accelerate to pass the first critical speed and pass the vibration test. Otherwise, change the correction mass group or select a new equilibrium speed that is as close as possible to the first critical speed.

[0021] Furthermore, the calibration and testing quality are also welded to the back of the blades to reduce the amount of thermal deformation of the screw feeder and its disturbance effect on the material.

[0022] Furthermore, the preset safe speed is 80% of the first-order critical speed.

[0023] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0024] The device of this invention has a simple structure. By repeatedly balancing the screw feeder using this balancing method, the ideal balance state can be achieved after finally solving the force balance, torque balance, and vibration mode balance. This ensures that the vibration amplitude of the screw feeder meets the standard at all speeds within the working speed range. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the detection process.

[0027] Figure descriptions: 1. Machine base, 2. Bearing housing assembly, 3. Screw, 4. Small end fixture, 5. Screw feeder, 6. Screw, 7. Large end fixture, 8. Belt, 9. Pulley, 10. Screw, 11. Motor assembly Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0029] This embodiment proposes a balancing device and method for a screw feeder.

[0030] like Figure 1 The diagram shows the structure of the present invention. The two ends of the spiral feeder 5 are connected and installed to the small end tooling 4 and the large end tooling 7 by screws 3 and 6 respectively, and are connected and installed to the pulley 9 by screws 10 to form a new rotor. Then, it is installed and fixed on the machine base 1 by the bearing seat assembly 2 to form a simply supported beam structure.

[0031] The motor assembly 11 is fixed on the base 1 and drives the pulley 9 to rotate via the belt 8, which in turn drives the screw feeder 5 to rotate. The speed of the screw feeder 5 is changed by adjusting the motor speed to achieve the working speed. The support conditions of the new rotor are basically the same as those during the assembly of the horizontal screw press. Data acquisition and analysis are performed using a portable dynamic balancing instrument, and dynamic balancing is carried out according to the following general steps.

[0032] 1. Select the balance correction surface. Usually, select a position 20-30% away from both ends of the screw feeder 5, as shown in Figure A and C. Point A is the third blade from the small end, and point B is the third blade from the large end. This is to prevent the added counterweight from affecting the flow of the liquid phase and the pushing of the solid phase.

[0033] 2. Perform low-speed dynamic balancing on the screw feeder 5 at 20% of its operating speed to eliminate rigid imbalance.

[0034] Third, increase the speed of the screw feeder 5 to a safe speed close to the first-order critical speed (generally the maximum is 80% of the first-order critical speed). This is called the first-order flexible balance speed. Record the vibration reading under steady-state conditions. Before recording, it must be confirmed that the reading is repeatable.

[0035] IV. Add a set of test masses to the screw feeder 5. The size of the test masses and their position along the axial direction of the screw feeder 5 should cause a significant change in the vibration vector at the first-order flexible equilibrium speed. The test mass set typically consists of masses located at both ends and the center of mass of the screw feeder 5. The ends are located at points A and C, both at the third blade from the ends, and the center of mass is located at point B. The mass at point B is M, and the masses at points A and C are M / 2, ensuring that they do not disrupt the low-speed balance. The test masses are welded to the back of the blades to reduce the amount of thermal deformation of the screw feeder and its disturbance to the material.

[0036] 5. Increase the speed of the screw feeder 5 to the same speed as in step 3 and under the same operating conditions, and record the new vibration readings.

[0037] 6. Calculate the influence of the test mass group at first-order flexible equilibrium based on the vector change of readings between 3 and 5. Then, calculate the magnitude and phase of a set of corrective masses to eliminate the influence of unbalance at the first-order flexible equilibrium speed. Add this corrective mass to A and C. The corrective mass and the test mass are also welded to the back of the blade.

[0038] At this point, the screw feeder 5 should be able to accelerate to pass the first critical speed and achieve the required vibration. Otherwise, change the calibration mass group, or select a new equilibrium speed that is as close as possible to the first critical speed, and repeat steps three through six.

[0039] By repeatedly balancing the screw feeder 5 using the balancing device and method of this invention, the ideal balance state can be achieved after finally solving the force balance, torque balance, and vibration mode balance, so that the vibration amplitude of the screw feeder 5 meets the standard at all speeds within the working speed range. Using the balancing device and method of this invention to perform high-speed dynamic balancing on the screw feeder of the LW450 model, before balancing, the vibration of the whole machine was 5 mm / s at 3000 r / min and 6 mm / s at 3300 r / min; after balancing, the vibration of the whole machine was 3.5 mm / s at 3000 r / min and 4 mm / s at 3300 r / min, meeting the company standard of 4.5 mm / s.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any transformations or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A balancing method for a screw feeder, characterized in that, Data acquisition and analysis are performed using a dynamic balancing instrument in conjunction with the balancing device of the screw feeder. The two ends of the screw feeder are rotatably mounted on the base via bearing assemblies. One end of the screw feeder is connected to a power output device, the speed of which is adjustable. The correction mass and the test mass are welded to the back of the blade. The selection of the test mass size and its position along the axial direction of the screw feeder should cause a change in the vibration vector at the first-order flexible balance speed. The correction mass is used to eliminate the influence of the unbalance at the first-order flexible balance speed. Dynamic balancing is performed according to the following general steps: S1 Select the balance correction surface. Select a position 20-30% of the length from both ends of the screw feeder to reduce the impact of the added counterweight on the flow of the liquid phase and the pushing of the solid phase. S2 performs low-speed dynamic balancing on the screw feeder at 20% of its operating speed to eliminate rigid imbalance. S3 accelerates the screw feeder to a preset safe speed close to the first-order critical speed, which is called the first-order flexible balance speed. It records the vibration reading under steady-state conditions. Before recording, it must be confirmed that the reading is repeatable. S4. Add a set of test masses to the screw feeder. The selection of the size of the test masses and their placement along the axial direction of the screw feeder should cause the vibration vector to change at the first-order flexible equilibrium speed. The test mass set consists of masses located at both ends of the screw feeder and at the center of mass, where the mass at the center of mass is M and the mass at both ends of the rotor is M / 2, so as not to disturb the low-speed balance. S5 increases the speed of the screw feeder to the same speed as in S3 and records the new vibration readings under the same operating conditions; S6 calculates the influence of the test mass group at first-order flexible balance by the vector change of the readings between S3 and S5, and then calculates the magnitude and phase of a set of correction masses to eliminate the influence of the unbalance at the first-order flexible balance speed, and adds this correction mass. S7 Repeat steps S3-S6 until the vibration is acceptable.

2. The balancing method for the screw feeder according to claim 1, characterized in that: The large end of the screw feeder is connected to the large end fixture through a fixing device, and the small end of the screw feeder is connected to the small end fixture through a fixing device. The large end fixture and the small end fixture are respectively installed and fixed on the machine base through bearing assemblies to form a simply supported beam structure.

3. The balancing method for the screw feeder according to claim 1, characterized in that: Both the large-end and small-end tooling are hollow shaft structures.

4. The balancing method for the screw feeder according to claim 1, characterized in that: The end of the large-end tooling is equipped with a pulley, which is connected to a motor assembly via a belt drive. The motor assembly is an adjustable speed motor.

5. The balancing method for the screw feeder according to claim 1, characterized in that: The roughness, dimensional tolerances, and geometric tolerances of the large-end tooling, small-end tooling, bearing assembly, and machine base mounting parts are the same as those of the entire screw feeder during assembly.

6. The balancing method for the screw feeder according to claim 1, characterized in that, At the end of S7, the screw feeder should be able to accelerate to pass the first critical speed and pass the vibration test. Otherwise, change the correction mass group or select a new equilibrium speed close to the first critical speed.

7. The balancing method for the screw feeder according to claim 1, characterized in that, The calibration and testing quality are also welded to the back of the blades to reduce the amount of thermal deformation of the screw feeder and the disturbance to the material.

8. The balancing method for the screw feeder according to claim 1, characterized in that, The preset safe speed is 80% of the first-order critical speed.

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