Feeding device of pneumatic pipeline conveyor and application of feeding device in furniture board production

Abstract

The invention belongs to the field of furniture production and processing, and relates to a feeding device of a pneumatic pipeline conveyor and application of the feeding device in furniture board production.The feeding device of the pneumatic pipeline conveyor comprises a hopper, a discharging pipe and a spiral auger, and the discharging pipe is sleeved with a circular-ring-shaped upper piezoelectric ceramic block and a circular-ring-shaped lower piezoelectric ceramic block; the ratio of the resonant frequency of the upper piezoelectric ceramic block to the resonant frequency of the lower piezoelectric ceramic block is larger than or equal to 55, and the resonant frequency of the lower piezoelectric ceramic block is 20-23 kHz. The upper piezoelectric ceramic block and the lower piezoelectric ceramic block are additionally arranged outside the discharging pipe below the hopper, high-frequency vibration of different frequencies generated by piezoelectric ceramics is matched, and on the basis that the spiral blade exists in the discharging pipe, dynamic sealing can be formed between the discharging pipe and the spiral blade, so that the air tightness of the hopper during feeding can be remarkably improved; and meanwhile, the hopper is not influenced to feed materials into the machine barrel of the conveyor.

Description

Technical Field

[0001] The present invention relates to the technical field of furniture production and processing, specifically to the feeding device of a pneumatic pipeline conveyor and its application in the production of furniture boards. Background Art

[0002] In the field of furniture board production and processing, particle boards and granulated boards are common raw material boards for furniture boards. Particle boards are made by mixing sawdust, wood chips and other wood residues with adhesives and then pressing them into boards under high temperature and high pressure. Granulated boards are formed by adding adhesives to wood chips and then pressing them. The mixed glue material generally refers to the mixture formed by mixing wood fiber materials such as wood chips and sawdust with adhesives, and the mixed glue material is generally transported by a pneumatic pipeline conveyor.

[0003] In the field of furniture board processing, the conveying air pressure of the mixed glue material is usually between 0.5 and 1.3 MPa. For the mixed glue material of particle boards or granulated boards, due to its very high viscosity, a auger is usually installed in the center of the feeding hopper to assist in feeding. As the mixed glue material in the hopper continuously decreases, the extrusion pressure on the mixed glue material in the hopper pipe (used to connect the hopper and the conveyor barrel) will significantly decrease, which may cause the compressed air in the conveyor barrel to overflow from the gap between the auger and the hopper pipe, resulting in a significant decrease in the pneumatic feeding effect, and may also cause some aerosols and glue particles to disperse near the pneumatic pipeline conveyor, affecting the workshop environment; to avoid this situation, it is usually necessary to ensure that the volume of the mixed glue material in the hopper accounts for at least 1 / 2 of the hopper volume or reduce the conveying air pressure. For example, for a hopper with a volume of 0.8 m 3 , when the air pressure in the conveyor barrel is 0.7 MPa and the volume of the mixed glue material in the hopper is above 0.4 m 3 , no bubbles appear on the liquid surface in the hopper; when the volume of the mixed glue material in the hopper drops to about 0.3 m 3 , it will be found that fine small bubbles (with a diameter of about 1 - 2 cm) appear on the liquid surface in the hopper; when the volume of the mixed glue material in the hopper drops to about 0.2 m 3 , it will be found that the diameter of the bubbles appearing on the liquid surface in the hopper increases to 3 - 5 cm; if the air pressure in the conveyor barrel is below 0.63 MPa, relying on the forced driving force of the auger, the minimum gap between the spiral blades of the auger and the hopper pipe is designed to be 5 mm, and no air leakage problem will occur before the volume of the mixed glue material in the hopper is less than 0.1 m 3 .

[0004] However, as the performance requirements for furniture boards such as particle boards and granulated boards are getting higher and higher, the composition of the adhesives in the mixed glue material is becoming more and more complex, and the conveying difficulty of the mixed glue material is also getting higher and higher. It is necessary to use a greater pneumatic driving force, which will all lead to an increased risk of air leakage of the mixed glue material in the hopper.

[0005] Based on this, how to improve the airtightness of the hopper during feeding while not affecting the feeding of the hopper into the conveyor barrel is an urgent problem to be solved by the present invention. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a feeding device for a pneumatic pipeline conveyor and its application in the production of furniture boards. The technical solutions are as follows: 1. The feeding device of the pneumatic pipeline conveyor includes a hopper, a discharge pipe installed at the lower end of the hopper, and a spiral auger for feeding. The spiral auger includes a spiral shaft and spiral blades, and the spiral blades are located inside the discharge pipe; an annular upper piezoelectric ceramic block and an annular lower piezoelectric ceramic block are sleeved outside the discharge pipe. The ratio of the resonance frequency of the upper piezoelectric ceramic block to the resonance frequency of the lower piezoelectric ceramic block is greater than or equal to 55, and the resonance frequency of the lower piezoelectric ceramic block is 20 - 23 kHz.

[0007] As a further scheme of the present invention, the ratio of the resonance frequency of the upper piezoelectric ceramic block to the resonance frequency of the lower piezoelectric ceramic block is 58.

[0008] As a further scheme of the present invention, the minimum clearance between the spiral blades and the inner wall of the discharge pipe is 5 - 12 mm.

[0009] As a further scheme of the present invention, a shock-absorbing gasket is installed between the upper piezoelectric ceramic block and the lower end of the hopper.

[0010] 2. The pneumatic pipeline conveyor includes a conveyor barrel, a gas source for providing pneumatic driving force into the conveyor barrel, and the feeding device of the above pneumatic pipeline conveyor. The lower end of the discharge pipe is communicated with the inner cavity of the conveyor barrel.

[0011] As a further scheme of the present invention, the conveying air pressure of the gas source into the conveyor barrel is 0.7 - 1.8 MPa.

[0012] As a further scheme of the present invention, the application of the feeding device of the pneumatic pipeline conveyor in the production of furniture boards.

[0013] 3. The application of the feeding device of the pneumatic pipeline conveyor in the production of furniture boards. The feeding device of the pneumatic pipeline conveyor is used to feed the pneumatic pipeline conveyor, and the pneumatic pipeline conveyor is used to convey the mixed glue used in the production of furniture boards.

[0014] As a further solution of the present invention, when the furniture board is a particle board, when the conveying air pressure in the conveyor barrel by the air source is 0.7~1.5 MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started. The resonance frequency of the lower piezoelectric ceramic block is 20 kHz, the resonance frequency of the upper piezoelectric ceramic block is 1160 kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~9 mm.

[0015] As a further solution of the present invention, when the furniture board is a particle board, when the conveying air pressure in the conveyor barrel by the air source is 0.7~1.8 MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started. The resonance frequency of the lower piezoelectric ceramic block is 23 kHz, the resonance frequency of the upper piezoelectric ceramic block is 1334 kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~12 mm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By improving the hopper structure of the feeding part of the existing pneumatic pipeline conveyor, the upper piezoelectric ceramic block and the lower piezoelectric ceramic block are added outside the discharge pipe under the hopper. Through the cooperation of the high-frequency vibrations generated by the piezoelectric ceramics with different frequencies, on the basis that there is a spiral blade inside the discharge pipe, a dynamic seal can be formed between the discharge pipe and the spiral blade, which will significantly improve the airtightness of the hopper during feeding, and at the same time does not affect the feeding of the hopper into the conveyor barrel.

[0017] 2. Even if the gap between the discharge pipe and the spiral blade increases to 12 mm and the conveying air pressure in the conveyor barrel by the air source increases to 1.8 MPa, a good dynamic seal can still be maintained.

[0018] 3. Under the long-term high-frequency vibration environment of the discharge pipe, its inner wall is not easy to adhere to a large amount of residual glue scale that is difficult to clean, which is convenient for subsequent cleaning. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the feeding device of the pneumatic pipeline conveyor; Figure 2 It is a schematic structural diagram of the pneumatic pipeline conveyor. Detailed Embodiments

[0020] The following describes the present invention in detail with specific embodiments. The following described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present invention. Embodiment 1

[0021] As Figure 1As shown in the figure, the feeding device of the pneumatic pipeline conveyor includes a hopper 12, a discharge pipe 11 installed at the lower end of the hopper 12, and a spiral auger 13 for feeding. The spiral auger 13 includes a spiral shaft and spiral blades, and the spiral blades are located inside the discharge pipe 11. An annular upper piezoelectric ceramic block 22 and an annular lower piezoelectric ceramic block 21 are sleeved outside the discharge pipe 11. The ratio of the resonance frequency of the upper piezoelectric ceramic block 22 to the resonance frequency of the lower piezoelectric ceramic block 21 is greater than or equal to 55, and the resonance frequency of the lower piezoelectric ceramic block 21 is 20 - 23 kHz.

[0022] Among them, to adapt to most specifications, the upper piezoelectric ceramic block 22 and the lower piezoelectric ceramic block 21 can be arranged in an annular structure by multiple cylindrical piezoelectric ceramic units.

[0023] In this embodiment, the vibration generated by the energization of the upper piezoelectric ceramic block 22 is megasonic vibration, and the vibration generated by the energization of the lower piezoelectric ceramic block 21 is ultrasonic vibration. Through such high-frequency vibrations at different levels, the mixed rubber near the inner wall of the discharge pipe 11 is compacted and densified, and a dynamic seal is formed with the mixed rubber between the spiral auger 13 and the inner wall of the discharge pipe 11 as the carrier. Embodiment 2

[0024] One application example of the feeding device of the pneumatic pipeline conveyor in Embodiment 1 is applied to the pneumatic pipeline conveyor, as Figure 2 As shown in the figure, the pneumatic pipeline conveyor includes a conveyor barrel 10, a gas source for providing pneumatic driving force to the inside of the conveyor barrel 10, and the feeding device of the pneumatic pipeline conveyor. The lower end of the discharge pipe 11 is communicated with the inner cavity of the conveyor barrel 10.

[0025] The gas source transports compressed air into the conveyor barrel 10, and the compressed air is used to provide the driving force for pneumatic transportation. When a dynamic seal is formed between the spiral auger 13 and the inner wall of the discharge pipe 11, the compressed air in the conveyor barrel 10 will not break through the gap between the spiral auger 13 and the inner wall of the discharge pipe 11 and leak.

[0026] The feeding device of the pneumatic pipeline conveyor is used to feed the pneumatic pipeline conveyor, and the pneumatic pipeline conveyor is used to transport the mixed rubber used in furniture board production. Embodiment 3

[0027] Leakage test During the actual operation of a pneumatic pipeline conveyor, if air leakage occurs, the pressure changes at the input and output ends of the conveyor barrel will be significantly less than the expected values. Specifically: Install a pressure sensor at the input end of the conveyor barrel (the end connected to the air source), which measures the input pressure P1 inside the conveyor barrel; for convenient measurement, the input pressure P1 is always a stable constant pressure; install another pressure sensor at the output end of the conveyor barrel (10 cm away from the discharge port), which measures the output pressure P2 inside the conveyor barrel, and ΔP = P1 - P2. Pour the mixed rubber material into the hopper until it is full. Before half of the remaining mixed rubber material in the hopper is left, record and calculate the initial ΔP, and record it as ΔP 标 ; Before the mixed rubber material in the hopper runs out, calculate ΔP in real time, take its minimum value, and record it as ΔP min ; η = 1 - ΔP min / ΔP 标 ; If η ≤ 0.05, it indicates that it is within a reasonable error range. But when η ≥ 0.1, it indicates that obvious air leakage has occurred.

[0028] Characterization test of the self-cleaning performance of the inner wall of the discharge pipe After the pneumatic pipeline conveyor has run for 100 hours, heat the residual rubber material adhering to the inner wall of the discharge pipe by introducing 100°C steam into the hopper for 10 minutes. Heating can cause a certain degree of curing of the residual mixed rubber material, so that the residual rubber material adheres better to the inner wall of the discharge pipe, which is used to simulate the formation of residual rubber scale that is difficult to remove after years of accumulation on the inner wall of the discharge pipe. Therefore, under different operating environments, the self-cleaning performance of the inner wall of the discharge pipe can be characterized by scraping off the residual rubber scale that cannot be removed after cleaning with acetone for 30 minutes with a scraper, drying it, and weighing it (the result obtained is the dry weight of the residual rubber scale); the greater the dry weight of the residual rubber scale, the worse the self-cleaning performance of the inner wall of the discharge pipe, and the easier it is to adhere to a large amount of difficult-to-clean residual rubber scale.

[0029] The sizes of the solid particles inside the particle board and the chipboard are different, so the corresponding test effects have certain differences.

[0030] When the furniture board is a particle board, the resonance frequency of the lower piezoelectric ceramic block 21 is 20 kHz, the resonance frequency of the upper piezoelectric ceramic block 22 is 1160 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm; when the conveying air pressure in the conveyor barrel 10 by the air source is 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa respectively, η is less than 0.05, indicating that no air leakage occurs; however, when the conveying air pressure in the conveyor barrel 10 is 1.6 MPa, η = 0.37, indicating that air leakage occurs. When the conveying air pressure is maintained at 1.5 MPa for long-term operation and tested according to the "Test for Characterizing the Self-Cleaning Performance of the Inner Wall of the Discharge Pipe", finally, the dry weight of the residual glue scale = 205 g.

[0031] When the furniture board is a particle board, the resonance frequency of the lower piezoelectric ceramic block 21 is 23 kHz, the resonance frequency of the upper piezoelectric ceramic block 22 is 1334 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm; when the conveying air pressure in the conveyor barrel 10 by the air source is 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa respectively, η is less than 0.05, indicating that no air leakage occurs; however, when the conveying air pressure in the conveyor barrel 10 is 1.9 MPa, η = 0.45, indicating that air leakage occurs. When the conveying air pressure is maintained at 1.5 MPa for long-term operation and tested according to the "Test for Characterizing the Self-Cleaning Performance of the Inner Wall of the Discharge Pipe", finally, the dry weight of the residual glue scale = 186 g.

[0032] When the furniture board is a particle board, the resonance frequency of the lower piezoelectric ceramic block 21 is 23 kHz, the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm, and when the conveying air pressure in the conveyor barrel 10 by the air source is 1.8 MPa, when the resonance frequencies of the upper piezoelectric ceramic block 22 are 1150 kHz, 1173 kHz, 1196 kHz, 1219 kHz, 1242 kHz, 1265 kHz, 1288 kHz, 1311 kHz, 1334 kHz, 1357 kHz, 1380 kHz respectively, the corresponding η values are 0.336, 0.41, 0.305, 0.247, 0.177, 0.042, 0.034, 0.026, 0.015, 0.036, 0.02.

[0033] When the furniture board is a particle board, the resonance frequency of the lower piezoelectric ceramic block 21 is 20 kHz, the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm, and when the conveying air pressure of the air source into the conveyor barrel 10 is 1.5 MPa, the resonance frequencies of the upper piezoelectric ceramic block 22 are 1000 kHz, 1020 kHz, 1040 kHz, 1060 kHz, 1080 kHz, 1100 kHz, 1120 kHz, 1140 kHz, 1160 kHz, 1180 kHz, 1200 kHz respectively, and the corresponding η values are 0.446, 0.208, 0.195, 0.306, 0.119, 0.049, 0.045, 0.039, 0.011, 0.102, 0.227.

[0034] As can be seen from the above, the ratio of the resonance frequency of the upper piezoelectric ceramic block 22 to the resonance frequency of the lower piezoelectric ceramic block 21 can be greater than or equal to 55, but the most preferred is 58.

[0035] In the present invention, the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 can be greater than 5 mm. The larger the minimum clearance, the smaller the resistance of the spiral auger 13 during operation, thus saving more electricity; however, the larger the minimum clearance, the greater the risk of air leakage; the maximum value of the minimum clearance in the present invention is 12 mm.

[0036] In the present invention, the greater the conveying air pressure of the air source into the conveyor barrel 10, the better the conveying effect on the mixed glue material with complex composition and high conveying difficulty. However, the greater the conveying air pressure, the greater the risk of air leakage; the maximum value of the conveying air pressure is 1.8 MPa. In actual use, if the conveying air pressure does not exceed 0.7 MPa, the upper piezoelectric ceramic block 22 and the lower piezoelectric ceramic block 21 can not be started, and the use requirements can also be met.

[0037] Therefore, the conveying air pressure of the air source into the conveyor barrel 10 can be 0.7 - 1.8 MPa.

[0038] It was found during the test process that taking the particle board as an example, if the resonance frequencies of the upper piezoelectric ceramic block 22 and the lower piezoelectric ceramic block 21 are both 23 kHz, the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm, and the conveying air pressure of the air source into the conveyor barrel 10 is 1.5 MPa, finally it was found that η = 0.51, indicating air leakage. Similarly, if the resonance frequency of the lower piezoelectric ceramic block 21 is 1334 kHz, the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm, and the conveying air pressure of the air source into the conveyor barrel 10 is 1.5 MPa, finally it was found that η = 0.33, indicating air leakage.

[0039] As can be seen from the above, relying solely on the same - frequency ultrasonic or megasonic vibration, it is impossible to form an effective dynamic seal.

[0040] During the test, it was found that taking particle board as an example, if the resonance frequency of the lower piezoelectric ceramic block 21 is 1334 kHz, the resonance frequency of the upper piezoelectric ceramic block 22 is 23 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm; when the conveying air pressure in the conveyor barrel 10 by the air source is 1.8 MPa, η = 0.037, indicating that no air leakage occurred. According to the "Test for Characterizing the Self-Cleaning Performance of the Inner Wall of the Discharge Pipe" for testing, finally, the dry weight of the residual glue scale = 2053 g, which is significantly higher than that of the present invention.

[0041] During the test, it was found that taking particleboard as an example, if the resonance frequency of the lower piezoelectric ceramic block 21 is 1160 kHz, the resonance frequency of the upper piezoelectric ceramic block 22 is 20 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm; when the conveying air pressure in the conveyor barrel 10 by the air source is 1.2 MPa, η = 0.047, indicating that no air leakage occurred; according to the "Test for Characterizing the Self-Cleaning Performance of the Inner Wall of the Discharge Pipe" for testing, finally, the dry weight of the residual glue scale = 1169 g, which is significantly higher than that of the present invention. When the conveying air pressure in the conveyor barrel 10 is 1.3 MPa, η = 0.22, indicating that air leakage occurred.

[0042] From the above, it can be seen that for the vertically arranged discharge pipe 11, the lower piezoelectric ceramic block 21 generates ultrasonic vibrations with large amplitude and low frequency, and the upper piezoelectric ceramic block 22 generates megasonic vibrations with small amplitude and high frequency. The superposition of these two types of vibrations and the change of their vertical position relationship have little impact on generating dynamic sealing; but it has a great impact on the degree of particle compaction and adhesion to the inner wall of the discharge pipe 11. It must be that the ultrasonic vibrations are below and the megasonic vibrations are above, otherwise a relatively dense and difficult-to-remove residual glue scale will adhere to the inner wall of the discharge pipe 11, which greatly affects the subsequent cleaning inside the discharge pipe 11.

[0043] It was also found in the test that the material passing through the discharge pipe 11 must contain a large amount of solid particles (such as wood chips). For example, if the water-soluble alkyd resin paint is conveyed in the hopper 12, even if the resonance frequency of the lower piezoelectric ceramic block 21 is 20 - 25 kHz and the resonance frequency of the upper piezoelectric ceramic block 22 is 1160 - 1450 kHz, it is found that η is always greater than 0.26, indicating that air leakage occurred. Example 4

[0044] In Example 1, to ensure the stability of installation and considering that the vibration is concentrated at the discharge pipe, a shock-absorbing washer 50 is installed between the upper piezoelectric ceramic block 22 and the lower end of the hopper 12.

[0045] In addition, it should be understood that those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. The feeding device of a pneumatic pipeline conveyor, comprising a hopper, a discharge pipe installed at the lower end of the hopper, and a spiral auger for feeding. The spiral auger includes a spiral shaft and spiral blades, and the spiral blades are located inside the discharge pipe. It is characterized in that: An annular upper piezoelectric ceramic block and an annular lower piezoelectric ceramic block are sleeved outside the discharge pipe. The ratio of the resonance frequency of the upper piezoelectric ceramic block to the resonance frequency of the lower piezoelectric ceramic block is greater than or equal to 55, and the resonance frequency of the lower piezoelectric ceramic block is 20 - 23 kHz.

2. The feeding device of the pneumatic pipeline conveyor according to claim 1, characterized in that: The ratio of the resonance frequency of the upper piezoelectric ceramic block to the resonance frequency of the lower piezoelectric ceramic block is 58.

3. The feeding device of the pneumatic pipeline conveyor according to claim 1, wherein: The minimum clearance between the spiral blade and the inner wall of the discharge pipe is 5 - 12 mm.

4. The feeding device of the pneumatic pipeline conveyor according to claim 1, characterized in that: A shock-absorbing washer is installed between the upper piezoelectric ceramic block and the lower end of the hopper.

5. Pneumatic pipeline conveyor, including a conveyor barrel and a gas source used to provide pneumatic driving force into the conveyor barrel, characterized in that: It further includes a feeding device of the pneumatic pipeline conveyor according to any one of claims 1 - 4, and the lower end of the discharge pipe is communicated with the inner cavity of the conveyor barrel.

6. The pneumatic pipeline conveyor according to claim 5, wherein: The conveying air pressure from the air source into the conveyor barrel is 0.7 - 1.8 MPa.

7. Application of the feeding device of the pneumatic pipeline conveyor according to any one of claims 1 - 4 in the production of furniture boards.

8. The application of the feeding device of the pneumatic pipeline conveyor according to claim 7 in the production of furniture boards, characterized in that: The feeding device of the pneumatic pipeline conveyor is used to feed the pneumatic pipeline conveyor, and the pneumatic pipeline conveyor is used to convey the mixed adhesive used in the production of furniture boards.

9. Use of the feeding device of the pneumatic pipeline conveyor according to claim 8 in the production of furniture boards, characterized in that: When the furniture board is a particle board, when the conveying air pressure from the air source into the conveyor barrel is 0.7 - 1.5 MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started. The resonance frequency of the lower piezoelectric ceramic block is 20 kHz, the resonance frequency of the upper piezoelectric ceramic block is 1160 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe is 5 - 9 mm.

10. The application of the feeding device of the pneumatic pipeline conveyor according to claim 8 in the production of furniture boards, characterized in that: When the furniture board is a particle board, when the conveying air pressure from the air source into the conveyor barrel is 0.7 - 1.8 MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started. The resonance frequency of the lower piezoelectric ceramic block is 23 kHz, the resonance frequency of the upper piezoelectric ceramic block is 1334 kHz, and the minimum clearance between the spiral blade and the inner wall of the discharge pipe is 5 - 12 mm.

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