Feeding device of pneumatic pipe conveyor and its application in furniture board production

Abstract

The present invention belongs to the field of furniture production and processing, and relates to a feeding device for a pneumatic pipe conveyor and its application in the production of furniture panels. The feeding device of the pneumatic pipe conveyor includes a hopper, a discharge pipe, and a spiral auger. The discharge pipe is externally sheathed with an annular upper piezoelectric ceramic block and an annular 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 greater than or equal to 55, and the resonant frequency of the lower piezoelectric ceramic block is 20-23kHz. The present invention installs an upper piezoelectric ceramic block and a lower piezoelectric ceramic block on the discharge pipe below the hopper, and the piezoelectric ceramics generate high-frequency vibrations of different frequencies. Based on the presence of spiral blades inside the discharge pipe, a dynamic seal can be formed between the discharge pipe and the spiral blades, which significantly improves the airtightness of the hopper during feeding while not affecting the hopper's feeding into the conveyor barrel.

Description

Technical Field

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

[0002] In the production and processing of furniture panels, particleboard and particleboard are common raw materials. Particleboard is made by mixing sawdust, wood chips, and other wood residues with an adhesive and pressing them under high temperature and high pressure. Particleboard is made by pressing sawdust with an adhesive and forming a board. The adhesive mix generally refers to a mixture of wood fiber materials such as sawdust and wood chips with an adhesive, and is typically transported using pneumatic pipe conveyors.

[0003] In the field of furniture board processing, the conveying air pressure of the mixed rubber is generally 0.5~1.3MPa. Since the viscosity of the mixed rubber of particleboard or particle board is very high, an auger is usually installed in the center of the feed hopper to assist in feeding. As the mixed rubber inside the hopper continues to decrease, the extrusion pressure on the mixed rubber in the hopper tube (used to connect the hopper and the conveyor barrel) will drop significantly, which will cause the compressed air in the conveyor barrel to overflow from the gap between the auger and the hopper tube, resulting in a significant decrease in the pneumatic feeding effect, and may also cause some aerosols and rubber particles to disperse near the pneumatic pipe conveyor, affecting the workshop environment; to avoid this situation, it is usually necessary to ensure that the volume of the mixed rubber in the hopper is at least 1 / 2 of the hopper volume or to reduce the conveying air pressure. For example, a volume of 0.8m 3 The air pressure in the conveyor barrel is 0.7 MPa, and the volume of the mixed rubber in the hopper is 0.4m 3 When the volume of the mixed rubber in the hopper drops to about 0.3m 3 When the volume of the mixed rubber in the hopper drops to about 0.2m 3 When the diameter of the bubbles on the surface of the liquid in the hopper increases to 3~5cm; if the air pressure in the conveyor barrel is below 0.63MPa, relying on the forced driving force of the auger, the minimum gap between the spiral blade of the auger and the hopper tube is designed to be 5mm, and the volume of the mixed rubber in the hopper is less than 0.1m 3 There was no air leakage problem before.

[0004] As the performance requirements of furniture boards such as particleboard and particleboard become higher and higher, the composition of the adhesive in the mixed rubber material becomes more and more complex, and the transportation of the mixed rubber material becomes more and more difficult. It is inevitable to use a larger pneumatic driving force, which will increase the risk of gas overflow from the mixed rubber material in the hopper.

[0005] Based on this, how to improve the air tightness of the hopper during feeding without affecting the feeding of the hopper into the conveyor barrel is an urgent problem to be solved in the present invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a feeding device for a pneumatic pipe conveyor and its application in the production of furniture panels. The technical solution is as follows:

[0007] 1. A feeding device for a pneumatic pipe conveyor, comprising a hopper, a discharge pipe mounted at the lower end of the hopper, and a spiral auger for feeding the material. The spiral auger comprises a spiral shaft and spiral blades, and the spiral blades are located within the discharge pipe. The discharge pipe is sheathed with an annular upper piezoelectric ceramic block and an annular 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 greater than or equal to 55, and the resonant frequency of the lower piezoelectric ceramic block is 20 to 23 kHz.

[0008] As a further solution 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.

[0009] As a further solution of the present invention, the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5-12 mm.

[0010] As a further solution of the present invention, a shock-absorbing washer is installed between the upper piezoelectric ceramic block and the lower end of the hopper.

[0011] 2. A pneumatic pipe conveyor, comprising a conveyor barrel, an air source for providing pneumatic driving force into the conveyor barrel, and a feeding device for the pneumatic pipe conveyor, wherein the lower end of the discharge pipe is connected to the inner cavity of the conveyor barrel.

[0012] As a further solution of the present invention, the air pressure conveyed by the air source into the conveyor barrel is 0.7-1.8 MPa.

[0013] As a further solution of the present invention, the feeding device of the pneumatic pipe conveyor is used in the production of furniture panels.

[0014] 3. Application of the feeding device of the pneumatic pipe conveyor in the production of furniture panels. The feeding device of the pneumatic pipe conveyor is used to feed the pneumatic pipe conveyor, and the pneumatic pipe conveyor is used to convey the mixed rubber used in the production of furniture panels.

[0015] As a further solution of the present invention, when the furniture board is a particle board, when the conveying air pressure of the air source into the conveyor barrel is 0.7~1.5MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started, the resonant frequency of the lower piezoelectric ceramic block is 20kHz, the resonant frequency of the upper piezoelectric ceramic block is 1160kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~9mm.

[0016] As a further solution of the present invention, when the furniture board is a particle board, when the air pressure of the air source into the conveyor barrel is 0.7~1.8MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started, the resonant frequency of the lower piezoelectric ceramic block is 23kHz, the resonant frequency of the upper piezoelectric ceramic block is 1334kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~12mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention improves the feeding hopper structure of the existing pneumatic pipe conveyor by installing upper and lower piezoelectric ceramic blocks outside the discharge pipe below the hopper. The piezoelectric ceramics generate high-frequency vibrations of different frequencies. On the basis of the spiral blades inside the discharge pipe, a dynamic seal can be formed between the discharge pipe and the spiral blades, which will significantly improve the airtightness of the hopper during feeding without affecting the feeding of the hopper into the conveyor barrel.

[0019] 2. Even if the distance between the discharge pipe and the spiral blade increases to 12mm and the air pressure from the air source to the conveyor barrel increases to 1.8MPa, it can still maintain a good dynamic seal.

[0020] 3. Under long-term high-frequency vibration environment, the inner wall of the discharge pipe is not easy to adhere to a large amount of difficult-to-clean residual glue scale, which is convenient for subsequent cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the feeding device of the pneumatic pipe conveyor;

[0022] Figure 2 This is a structural diagram of a pneumatic pipe conveyor. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to specific embodiments. The embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. Example 1

[0024] like Figure 1 As shown, the feeding device of the pneumatic pipe 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; the outside of the discharge pipe 11 is provided with an annular upper piezoelectric ceramic block 22 and an annular lower piezoelectric ceramic block 21, the ratio of the resonant frequency of the upper piezoelectric ceramic block 22 to the resonant frequency of the lower piezoelectric ceramic block 21 is greater than or equal to 55, and the resonant frequency of the lower piezoelectric ceramic block 21 is 20~23kHz.

[0025] In order to adapt to most specifications, the upper piezoelectric ceramic block 22 and the lower piezoelectric ceramic block 21 can adopt a plurality of cylindrical piezoelectric ceramic units arranged in a circular ring structure.

[0026] In this embodiment, the vibration generated by energizing the upper piezoelectric ceramic block 22 is megasonic vibration, and the vibration generated by energizing the lower piezoelectric ceramic block 21 is ultrasonic vibration. Through such different levels of high-frequency vibration, the mixed rubber material near the inner wall of the discharge pipe 11 is squeezed and densified, and the mixed rubber material between the spiral auger 13 and the inner wall of the discharge pipe 11 is used as a carrier to form a dynamic seal. Example 2

[0027] The feeding device of the pneumatic pipe conveyor in Example 1, one of the application examples, is applied to the pneumatic pipe conveyor, such as Figure 2 As shown, the pneumatic pipe conveyor includes a conveyor barrel 10, an air source for providing pneumatic driving force to the conveyor barrel 10, and a feeding device of the pneumatic pipe conveyor. The lower end of the discharge pipe 11 is connected to the inner cavity of the conveyor barrel 10.

[0028] The air source delivers compressed air into the conveyor barrel 10, which is used to provide the driving force for pneumatic conveying. When the auger 13 and the inner wall of the discharge pipe 11 form a dynamic seal, the compressed air in the conveyor barrel 10 will not break through the gap between the auger 13 and the inner wall of the discharge pipe 11 and cause gas leakage.

[0029] The feeding device of the pneumatic pipe conveyor is used to feed the pneumatic pipe conveyor, and the pneumatic pipe conveyor is used to convey the mixed rubber used in the production of furniture boards. Example 3

[0030] Gas overflow test

[0031] During the actual operation of the pneumatic pipe conveyor, if air overflow occurs, the pressure changes at the input and output ends of the conveyor barrel will be significantly smaller than the expected value. Specifically: a pressure sensor is installed at the input end of the conveyor barrel (the end connected to the air source), which measures the input pressure P1 in the conveyor barrel; for the convenience of measurement, the input pressure P1 is always a stable constant pressure; another pressure sensor is installed at the output end of the conveyor barrel (10 cm away from the discharge port), which measures the output pressure P2 in the conveyor barrel, ΔP=P1-P2. Fill the hopper with mixed rubber, and before 1 / 2 of the mixed rubber remains in the hopper, record and calculate the initial ΔP, recorded as ΔP 标 Before the mixed rubber in the hopper is exhausted, calculate ΔP in real time and take the minimum value, which is recorded as ΔP min ;η=1-ΔP min / ΔP 标 If η≤0.05, it means it is within a reasonable error range. However, when η≥0.1, it means that obvious gas overflow has occurred.

[0032] Characterization test of self-cleaning performance of inner wall of discharge pipe

[0033] After the pneumatic pipe conveyor had been running for a cumulative 100 hours, 100°C steam was introduced into the hopper to heat the residual rubber adhering to the inner wall of the discharge pipe for 10 minutes. Heating solidifies the remaining mixed rubber to a certain extent, thereby improving the bond between the residual rubber and the inner wall of the discharge pipe. This simulates the accumulation of difficult-to-remove residual rubber scale on the inner wall of the discharge pipe over time. Therefore, under different operating conditions, the self-cleaning performance of the discharge pipe inner wall can be characterized by scraping off the residual rubber scale that cannot be removed after 30 minutes of acetone cleaning with a scraper, drying it, and weighing it (the result is the dry weight of the residual rubber scale). The greater the dry weight of the residual rubber scale, the poorer the self-cleaning performance of the discharge pipe inner wall and the greater the tendency for the discharge pipe inner wall to adhere to a large amount of difficult-to-clean residual rubber scale.

[0034] The sizes of solid particles inside particleboard and particleboard are different, so the corresponding test results have certain differences.

[0035] When the furniture panel is particleboard, the resonant frequency of the lower piezoelectric ceramic block 21 is 20 kHz, and the resonant frequency of the upper piezoelectric ceramic block 22 is 1160 kHz. The minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm. When the air pressure into the conveyor barrel 10 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, and 1.5 MPa, η is less than 0.05, indicating no outgassing. However, when the air pressure into the conveyor barrel 10 is 1.6 MPa, η is 0.37, indicating outgassing. When the air pressure is maintained at 1.5 MPa for long-term operation, the residual adhesive scale is tested according to the "Characterization Test of the Self-Cleaning Performance of the Discharge Pipe Inner Wall" and the dry weight is 205 g.

[0036] When the furniture panel is particle board, the resonant frequency of the lower piezoelectric ceramic block 21 is 23kHz, and the resonant frequency of the upper piezoelectric ceramic block 22 is 1334kHz. The minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 12mm. When the air pressure into the conveyor barrel 10 is 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, 1.6MPa, 1.7MPa, and 1.8MPa, η is less than 0.05, indicating no outgassing. However, when the air pressure into the conveyor barrel 10 is 1.9MPa, η is 0.45, indicating outgassing. When the air pressure is maintained at 1.5MPa for long-term operation, the residual adhesive scale is tested according to the "Characterization Test of the Self-Cleaning Performance of the Discharge Pipe Inner Wall" and the dry weight is 186g.

[0037] When the furniture board is a particle board, the resonant frequency of the lower piezoelectric ceramic block 21 is 23kHz, the minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 12mm, and the conveying air pressure of the air source to the conveyor barrel 10 is 1.8MPa, when the resonant frequencies of the upper piezoelectric ceramic block 22 are 1150kHz, 1173kHz, 1196kHz, 1219kHz, 1242kHz, 1265kHz, 1288kHz, 1311kHz, 1334kHz, 1357kHz, and 1380kHz, respectively, the corresponding η are 0.336, 0.41, 0.305, 0.247, 0.177, 0.042, 0.034, 0.026, 0.015, 0.036, and 0.02, respectively.

[0038] When the furniture board is a particle board, the resonant frequency of the lower piezoelectric ceramic block 21 is 20 kHz, the minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm, and the conveying air pressure of the air source into the conveyor barrel 10 is 1.5 MPa, the resonant 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, and 1200 kHz, and the corresponding η are 0.446, 0.208, 0.195, 0.306, 0.119, 0.049, 0.045, 0.039, 0.011, 0.102, and 0.227, respectively.

[0039] As can be seen from the above, the ratio of the resonant frequency of the upper piezoelectric ceramic block 22 to the resonant frequency of the lower piezoelectric ceramic block 21 can be greater than or equal to 55, but is most preferably 58.

[0040] In the present invention, the minimum gap between the spiral blade and the inner wall of the discharge pipe 11 can be greater than 5 mm. The larger the minimum gap, the smaller the resistance of the spiral auger 13 during operation, thereby saving more electricity; but the larger the minimum gap, the greater the risk of air overflow; the maximum value of the minimum gap of the present invention is 12 mm.

[0041] In the present invention, a higher pressure from the air source into the conveyor barrel 10 improves the conveying efficiency for complex, challenging mixed rubber materials. However, this higher pressure also increases the risk of gas overflow. The maximum pressure is 1.8 MPa. In actual use, if the pressure does not exceed 0.7 MPa, the upper and lower piezoelectric ceramic blocks 22 and 21 can be deactivated, which still satisfies operational requirements.

[0042] Therefore, the conveying air pressure of the air source into the conveyor barrel 10 can be 0.7~1.8MPa.

[0043] During testing, using particle board as an example, if the resonant frequency of the upper and lower piezoelectric ceramic blocks 22 and 21 were both 23 kHz, the minimum gap between the spiral blades and the inner wall of the discharge tube 11 was 12 mm, and the air pressure delivered to the conveyor barrel 10 was 1.5 MPa, η was found to be 0.51, indicating outgassing. Similarly, if the resonant frequency of the lower piezoelectric ceramic block 21 was also 1334 kHz, the minimum gap between the spiral blades and the inner wall of the discharge tube 11 was 12 mm, and the air pressure delivered to the conveyor barrel 10 was 1.5 MPa, η was found to be 0.33, indicating outgassing.

[0044] From the above, it can be seen that it is impossible to form an effective dynamic seal by relying solely on ultrasound or megasonic vibration of the same frequency.

[0045] During testing, it was found that, using particle board as an example, if the resonant frequency of the lower piezoelectric ceramic block 21 is 1334 kHz and the resonant frequency of the upper piezoelectric ceramic block 22 is 23 kHz, the minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 12 mm. When the air pressure delivered to the conveyor barrel 10 is 1.8 MPa, η = 0.037, indicating no outgassing. Testing according to the "Characterization Test of the Self-Cleaning Performance of the Discharge Pipe Inner Wall" revealed a dry weight of residual adhesive scale of 2053 g, significantly higher than that of the present invention.

[0046] During testing, it was found that, using particleboard as an example, if the resonant frequency of the lower piezoelectric ceramic block 21 is 1160 kHz and the resonant frequency of the upper piezoelectric ceramic block 22 is 20 kHz, the minimum gap between the spiral blade and the inner wall of the discharge pipe 11 is 9 mm. When the air pressure delivered to the conveyor barrel 10 is 1.2 MPa, η = 0.047, indicating no outgassing. Following the "Characterization Test of the Self-Cleaning Performance of the Discharge Pipe Inner Wall," the dry weight of residual adhesive scale was 1169 g, significantly higher than that of the present invention. When the air pressure delivered to the conveyor barrel 10 is 1.3 MPa, η = 0.22, indicating outgassing.

[0047] 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 in their upper and lower positional relationship do not have much effect on the generation of dynamic sealing; but they have a great impact on the degree to which the particles are compacted and adhere to the inner wall of the discharge pipe 11. The ultrasonic vibrations must be at the bottom and the megasonic vibrations must be at the top, otherwise a relatively dense and difficult-to-remove layer of residual glue scale will be attached to the inner wall of the discharge pipe 11, which will greatly affect the subsequent cleaning of the inside of the discharge pipe 11.

[0048] The experiments also revealed 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 material conveyed by the hopper 12 is water-soluble alkyd resin paint, even if the resonant frequency of the lower piezoelectric ceramic block 21 is 20-25 kHz and the resonant frequency of the upper piezoelectric ceramic block 22 is 1160-1450 kHz, it was found that η is always greater than 0.26, indicating that gas overflow has occurred. Example 4

[0049] In Example 1, to ensure the stability of the 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 .

[0050] In addition, it should be understood that those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A feeding device for a pneumatic pipe conveyor, comprising a hopper, a discharge pipe mounted at the lower end of the hopper, and a spiral auger for feeding the material. The spiral auger comprises a spiral shaft and spiral blades, and the spiral blades are located inside the discharge pipe. The device is characterized by: The outer sleeve of the discharge pipe is provided with an annular upper piezoelectric ceramic block and an annular lower piezoelectric ceramic block, and the resonant frequency of the lower piezoelectric ceramic block is 20-23kHz; The ratio of the resonant frequency of the upper piezoelectric ceramic block to the resonant frequency of the lower piezoelectric ceramic block is 58; The minimum gap between the spiral blade and the inner wall of the discharge pipe is 5-12 mm; The lower end of the discharge pipe is communicated with the inner cavity of the conveyor barrel, and the pneumatic pipe conveyor is used to convey the mixed rubber used in the production of furniture boards.

2. The feeding device of the pneumatic pipe 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.

3. A pneumatic pipe conveyor comprising a conveyor barrel and an air source for providing a pneumatic driving force within the conveyor barrel, characterized in that: It also includes a feeding device for the pneumatic tube conveyor as claimed in claim 1 or 2.

4. The pneumatic tube conveyor according to claim 3, characterized in that: The air pressure conveyed by the air source into the conveyor barrel is 0.7~1.8MPa.

5. Use of the feeding device of the pneumatic pipe conveyor as claimed in claim 1 or 2 in the production of furniture panels.

6. Application of the feeding device of the pneumatic pipe conveyor according to claim 5 in the production of furniture panels, characterized in that: The feeding device of the pneumatic tube conveyor is used to feed the pneumatic tube conveyor.

7. Application of the feeding device of the pneumatic pipe conveyor according to claim 6 in the production of furniture panels, characterized in that: When the furniture board is a particle board, when the air pressure of the air source into the conveyor barrel is 0.7~1.5MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started, the resonant frequency of the lower piezoelectric ceramic block is 20kHz, the resonant frequency of the upper piezoelectric ceramic block is 1160kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~9mm.

8. Application of the feeding device of the pneumatic pipe conveyor according to claim 6 in the production of furniture panels, characterized in that: When the furniture board is a particle board, when the air pressure conveyed by the air source into the conveyor barrel is 0.7~1.8MPa, the lower piezoelectric ceramic block and the upper piezoelectric ceramic block are started, the resonant frequency of the lower piezoelectric ceramic block is 23kHz, the resonant frequency of the upper piezoelectric ceramic block is 1334kHz, and the minimum gap between the spiral blade and the inner wall of the discharge pipe is 5~12mm.

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