Bag opening exhaust device based on piezoelectric vibration, control method and system

Abstract

The invention relates to a bag opening exhaust device based on piezoelectric vibration and a control method and system, and belongs to the technical field of packaging equipment. A traditional bag opening exhaust device has the problems of low exhaust efficiency, material residues, dust pollution and the like. The exhaust device comprises two clamping plates (arranged on a packaging bag conveying and sealing path) capable of getting close to or getting away from each other, each clamping plate comprises a frame, a parallel spring set, a piezoelectric vibration assembly and a driving mechanism, the polarization direction of piezoelectric ceramic pieces is perpendicular to the axial direction of springs, and vibration exhaust and material vibration falling are achieved by applying an alternating electric field through a driving circuit. The control method and the circuit system are matched with the device to realize intelligent control, can be used for bag opening exhaust treatment of packaging bags for fertilizers, feeds and the like, and can effectively improve the packaging quality and the production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging equipment, and in particular relates to a bag mouth exhaust device based on piezoelectric vibration, a control method and a system. Background Art

[0002] In the automated packaging production process of granular materials such as fertilizers and feeds, bag mouth exhaust is a key link to ensure product sealing and packaging quality. Traditional packaging production lines usually use mechanical extrusion or natural exhaust methods, which have poor exhaust effects, causing the packaging bags to bulge and deform, affecting the subsequent sealing quality and product storage stability. Especially for materials with poor fluidity, the material particles remaining at the bag mouth will directly contaminate the sealing area, causing sealing failure.

[0003] The existing bag outlet exhaust device mainly has the following technical defects: Low exhaust efficiency: Mechanical extrusion devices directly press the bag mouth through the clamp, which easily leads to vortexes of air remaining in the bag, and the amount of residual air often exceeds 5%. For large-sized packaging bags above 10kg, a single exhaust needs to be repeated 3-5 times, which seriously affects production efficiency.

[0004] Serious material residue: Traditional vibration discharging devices mostly use eccentric wheels or cam structures, and the vibration frequency is usually lower than 20Hz, which cannot effectively shake off the fine particles adhering to the bag mouth. Experimental data shows that the residual rate of material particles with a diameter of less than 0.5mm is as high as 14%, which directly affects the sealing effect.

[0005] Dust pollution problem: During the open vibration discharge process, the dust generated by the friction between the material particles and the packaging bags will spread to the surrounding area. According to actual measurements, the dust concentration in the working area can reach 8mg / m³, far exceeding the occupational health standard (4mg / m³), and an expensive dust removal system needs to be configured.

[0006] Technical personnel in this field have tried to increase the vibration frequency to above 30Hz, but due to the lack of an effective vibration transmission structure, high-frequency vibrations can cause partial damage to the packaging bag. Although the use of flexible contact materials can reduce bag damage, it also causes a new problem of too fast vibration energy attenuation. These technical bottlenecks have caused traditional bag exhaust devices to be in a long-term contradiction between efficiency and reliability, making it difficult to meet the high-speed and high-precision requirements of modern packaging production lines. Summary of the invention

[0007] An object of the present invention is to address at least the above-mentioned disadvantages and to provide at least the advantages which will be described hereinafter.

[0008] The present invention provides a bag mouth exhaust device based on piezoelectric vibration. It uses a piezoelectric vibration component and controls the vibration of a piezoelectric ceramic sheet through a drive circuit, which can effectively exhaust the air in the bag, avoid the problem of residual air eddy caused by traditional mechanical extrusion devices, reduce the number of exhaust times, and improve production efficiency.

[0009] A bag mouth exhaust device based on piezoelectric vibration provided by the present invention includes two clamping plates that can approach or move away from each other. The clamping plates are arranged on the path of the conveying and sealing of the packaging bag. Each clamping plate includes a frame body, a parallel spring group, a piezoelectric vibration component, and a driving mechanism. The lower end of the frame body is open, and the top is a horizontally extending top plate. Two side plates extend downward from both sides of the top plate to form enclosing plates. The parallel spring group consists of multiple springs arranged in parallel between the two enclosing plates of the frame body, so that the facing surfaces of the two clamping plates both form elastic contact surfaces. The piezoelectric vibration component includes at least one piezoelectric ceramic sheet. The piezoelectric ceramic sheet is connected between the enclosing plate and the spring through an adhesive. Its polarization direction is perpendicular to the axial direction of the spring, and an alternating electric field is applied in the polarization direction through a drive circuit. The driving mechanism is used to drive the two clamping plates to approach or move away from each other. Wherein, the lower region of the elastic contact surface corresponds to the outer side of the bag mouth of the material, and the upper region corresponds to the outer side of the bag mouth without material. The piezoelectric ceramic sheet vibrates along the polarization direction under the control of the drive circuit.

[0010] Preferably, the drive circuit includes an electrical signal detection module and a frequency-voltage adjustment module. The electrical signal detection module detects the characteristic value of the charge signal generated by the piezoelectric ceramic sheet due to the pulling of the spring. The frequency-voltage adjustment module presets a signal characteristic threshold. When the detected value is less than the threshold, the piezoelectric ceramic sheet in the corresponding area vibrates at 50 - 100 Hz and a voltage of ±100 - 150 V is applied. When the detected value ≥ threshold, the piezoelectric ceramic sheet in the corresponding area does not start.

[0011] Preferably, several mounting seats are provided on the inner sides of the two enclosing plates of each clamping plate. One end of each piezoelectric ceramic sheet is connected to the inner side of the enclosing plate through an adhesive, and the other end is connected to the mounting seat through an adhesive. A second mounting hole is provided on the mounting seat, and both ends of the spring of the parallel spring group are respectively installed in the second mounting holes of the two enclosing plates, so that the piezoelectric ceramic sheet forms a vibration transmission structure with the spring through the mounting seat.

[0012] Preferably, a negative pressure suction pipe is installed on the top plate of one of the frames of the two clamping plates. Suction holes are provided on the lower side of the negative pressure suction pipe. The negative pressure suction pipe is connected to a blower through a switching valve. The suction holes are used to suck the scattered materials and dust during the exhaust process and convey them to a cyclone dust collector through a pipeline for cleaning.

[0013] Preferably, the negative pressure suction pipe is a rigid pipe body, and the negative pressure suction pipe abuts against the spring.

[0014] Preferably, it further includes a guiding assembly for restricting the relative movement path of the two clamping plates. The guiding assembly includes a guide rail fixed on the frame and two sliding brackets; the sliding brackets are slidably connected to the guide rail, and each sliding bracket is connected to the corresponding clamping plate through a support arm; the driving mechanism is connected to the two sliding brackets to drive the two sliding brackets to move relatively on the guide rail, so that the two clamping plates approach or separate from each other.

[0015] Preferably, it further includes two arc-shaped plates for straightening the packaging bag. The two arc-shaped plates are located on the two outer sides below the two clamping plates; the two arc-shaped plates are correspondingly connected to the two clamping plates, so that the two arc-shaped plates move synchronously with the two clamping plates, driving the jaws of the two arc-shaped plates to approach and separate from each other.

[0016] The present invention also provides a control method for a bag mouth exhaust device based on piezoelectric vibration, which is used to control the above-mentioned bag mouth exhaust device, including two clamping plates that can approach or separate from each other, a driving mechanism, negative pressure adsorption, a piezoelectric vibration assembly, an electrical signal detection module, and a frequency-voltage regulation module; The control method includes the following steps: a) Drive the two clamping plates close to the bag mouth, and the arc-shaped plates synchronously straighten the packaging bag until it contacts the frame; during this process, simultaneously start the negative pressure suction pipe to suck the scattered materials; b) Detect the charge signal of the piezoelectric ceramic sheet. When the detected value < the threshold value, start the piezoelectric ceramic sheet in the corresponding area to vibrate at 50 - 100 Hz and apply a voltage of ±100 - 150 V; when the detected value ≥ the threshold value, the piezoelectric ceramic sheet in the corresponding area stops vibrating; c) Continuously execute step b until the exhaust is completed, and drive the two clamping plates to separate and close the negative pressure suction pipe.

[0017] Specifically: At the start of exhaust, the driving mechanism drives the two clamping plates close to the bag mouth of the packaging bag, and the two arc-shaped plates move synchronously to straighten the packaging bag until the two frames abut; During the exhaust process, simultaneously suck the scattered materials and dust through the negative pressure suction pipe; The electrical signal detection module detects the charge signal characteristics generated by the piezoelectric ceramic sheet due to the spring pulling to obtain the detected value; The frequency-voltage regulation module compares the detected value with the preset threshold: if the detected value is less than the threshold, start the piezoelectric ceramic sheet in the corresponding area to vibrate at a frequency of 50 - 100 Hz and apply a voltage of ±100 - 150 V; if the detected value ≥ the threshold, the piezoelectric ceramic sheet in the corresponding area does not start vibrating; Continuously detect and control until the exhaust ends, and the driving mechanism moves the two clamping plates away and closes the negative pressure suction pipe.

[0018] Preferably, when the driving mechanism drives the two clamping plates to approach, the contact sensors arranged on the opposite surfaces of the frame body stop the driving action when the two frame bodies come into contact; During the exhaust process, the opening and suction of the negative pressure suction pipe are synchronously controlled; The control unit is communicatively connected to the driving mechanism, the switching valve of the negative pressure suction pipe, the electrical signal detection module, and the frequency-voltage regulation module, receives the detection value output by the electrical signal detection module, and compares it with a preset threshold: if the detection value < threshold, control the piezoelectric ceramic sheets in the corresponding area to vibrate at 50 - 100 Hz and apply ±100 - 150 V voltage; if the detection value ≥ threshold, control the corresponding area not to start vibrating; The control unit continuously monitors and controls the above process, and drives the clamping plates to separate and closes the negative pressure suction pipe after the exhaust is completed.

[0019] The present invention also provides a bag mouth exhaust control system for the above control method, including: A contact sensor circuit for detecting the contact state of the two clamping plate frames; An electrical signal detection module circuit including a charge amplifier and a filter, connected to the polarization direction electrodes of the piezoelectric ceramic sheets; A frequency-voltage regulation module circuit including a signal generator and a power amplifier, outputting an alternating voltage of 50 - 100 Hz and connected to the polarization direction electrodes of the piezoelectric ceramic sheets; An isolation circuit using an optocoupler to isolate the detection and regulation circuits; A control unit for performing the steps of the method as described in claim 8 and coordinating the driving mechanism, negative pressure suction, and vibration control.

[0020] Specifically, The contact sensor circuit is connected to the contact sensor, detects whether the two clamping plate frames come into contact, and transmits a switch signal to the control unit; The electrical signal detection module circuit is connected to the polarization direction of the piezoelectric ceramic sheets, including a charge amplifier and a low-pass filter, for detecting the charge signal characteristics generated by the piezoelectric ceramic sheets in the polarization direction due to spring pulling and transmitting the corresponding voltage signal; The driving mechanism control circuit receives the instruction from the control unit and drives the clamping plates and the arc-shaped plates to act; The frequency-voltage regulation module circuit includes a signal generator and a power amplifier, and controls the vibration of the piezoelectric ceramic sheets according to the instruction of the control unit; The negative pressure suction pipe control circuit controls the opening and closing of the negative pressure suction pipe according to the signal of the control unit; The isolation circuit uses an optocoupler and is arranged between the electrical signal detection module circuit and the frequency-voltage regulation module circuit; The control unit controls the driving mechanism and the negative pressure suction pipe to execute instructions according to a preset time, receives the switch signal of the contact sensor and the pulling force detection value of the electrical signal detection module, and after comparing and processing with a preset threshold value, issues corresponding control instructions to the frequency-voltage regulation module.

[0021] The present invention has at least the following beneficial effects: High exhaust efficiency: By adopting a piezoelectric vibration component and controlling the vibration of the piezoelectric ceramic sheet through a driving circuit, it can effectively exhaust the air in the bag, avoid the problem of residual air vortices caused by traditional mechanical extrusion devices, reduce the number of exhausts, and improve production efficiency.

[0022] Less material residue: The vibration frequency of the piezoelectric vibration component is relatively high, and by reasonably designing the vibration transmission structure (such as the connection between the mounting seat and the spring), the amplitude uniformity of the piezoelectric ceramic sheet is improved, which can effectively shake off the fine particles adhering to the bag mouth and reduce the material residue rate. Compared with traditional vibration discharging devices, the residue rate of material particles with a diameter of less than 0.5 mm can be significantly reduced.

[0023] Reduce dust pollution: By setting a negative pressure suction pipe, the scattered materials and dust are sucked during the exhaust process and transported to a cyclone dust collector for cleaning, effectively reducing the dust concentration in the working area. The negative pressure suction pipe is designed in coupling with the spring vibration, reducing the frequency of pipeline blockage, and the suction and vibration act synchronously, improving the suction efficiency for dispersed powder or dust, improving the working environment, reducing the harm to occupational health, and without the need to additionally configure an expensive dust removal system.

[0024] Avoid damage to the bag body: By adopting an elastic contact surface (constituted by a parallel spring group) and a flexible adhesive (such as epoxy resin adhesive, nano-composite adhesive), while ensuring the adhesion strength, the damage to the bag body is reduced, and the problem of local damage to the packaging bag caused by vibration is avoided.

[0025] High degree of automation: Through the communication connection between the control unit and each module (driving mechanism, switch valve of the negative pressure suction pipe, electrical signal detection module, frequency-voltage regulation module, etc.), full-process automatic control is realized, and the single-bag processing time is shortened to 1.4 seconds, with the efficiency increased by 2 times compared with the traditional manual intervention mode. The contact sensor precisely controls the closing stroke of the clamping plate to avoid the deformation of the bag mouth caused by excessive extrusion.

[0026] Ensure the exhaust effect: Set a guiding component to limit the relative movement path of the two clamping plates to ensure the stability of the exhaust action; set two arc-shaped plates to support and straighten the packaging bag, making the packaging bag in a vertical and stable state, reducing the perpendicularity deviation of the packaging bag (from ±5° to ±1°), avoiding the exhaust dead angle caused by inclination, and making the force distribution on the packaging bag uniform, reducing the bag body breakage rate.

[0027] Intelligent control of vibration: The electrical signal detection module and the frequency-voltage regulation module in the drive circuit can intelligently judge whether there is material at the bag mouth according to the characteristic values of the charge signals generated by the piezoelectric ceramic sheets due to the spring pulling, so as to control the vibration of the piezoelectric ceramic sheets in the corresponding area, start vibration exhaust at the bag mouth without material, and not start vibration at the bag mouth with material, which not only ensures the exhaust effect but also avoids unnecessary energy consumption and the impact on the material.

[0028] Other advantages, objectives and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of an implementation form of the bag mouth exhaust device based on piezoelectric vibration according to the present invention; Figure 2 It is a schematic structural diagram of a pair of clamping plates of the bag mouth exhaust device based on piezoelectric vibration according to the present invention; Figure 3 It is a schematic flow diagram of the control method of the bag mouth exhaust device based on piezoelectric vibration according to the present invention; Among them, guide rail 1; sliding bracket 2; support arm 3; double-acting telescopic cylinder 4; clamping plate 5; spring 6; arc plate 7; conveying platform 8; first mounting hole 9; frame 10; mounting seat 11; piezoelectric vibration assembly 12; negative pressure suction pipe 13; top plate 14; enclosing plate 15. Detailed Embodiments

[0030] The following further describes the present invention in detail with reference to the embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0031] It should be noted that the experimental methods described in the following implementation schemes are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified; in the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "setting" should be understood in a broad sense. For example, they can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. The orientation or positional relationship indicated by the terms "horizontal", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0032] Figures 1 - 2 shows an implementation form of a bag mouth exhaust device based on piezoelectric vibration, which includes two clamping plates 5 that can approach or move away from each other. The clamping plates 5 are arranged on the path of conveying and sealing the packaging bag. It is characterized in that each of the clamping plates 5 includes a frame body 10, a set of parallel springs 6, a piezoelectric vibration assembly 12, and a driving mechanism; the lower end of the frame body 10 is open, and the top is a horizontally extending top plate 14. Two side plates 15 extend downward from both sides of the top plate 14; the set of parallel springs 6 consists of multiple springs 6 arranged in parallel between the two side plates 15 of the frame body 10, so that the facing surfaces of the two clamping plates 5 both form elastic contact surfaces; the piezoelectric vibration assembly 12 includes at least one piezoelectric ceramic sheet. The piezoelectric ceramic sheet is connected between the side plate 15 and the spring 6 through an adhesive. Its polarization direction is perpendicular to the axial direction of the spring 6, and an alternating electric field is applied in the polarization direction through a driving circuit; the driving mechanism is used to drive the two clamping plates 5 to approach or move away from each other; wherein, the lower region of the elastic contact surface corresponds to the outer side of the bag mouth of the material, and the upper region corresponds to the outer side of the bag mouth without material. The piezoelectric ceramic sheet vibrates along the polarization direction under the control of the driving circuit to realize the functions of bag mouth exhaust and material vibration dropping.

[0033] The adhesive can be selected from epoxy resin adhesives, nano-composite adhesives (bonding strength reaching more than 35 Mpa) to improve the adhesion strength, flexibility and elasticity, and there is no peeling after 1 million fatigue tests. For the convenience of installation, a first installation hole 9 can be provided on the outer side of the top plate 14 to facilitate the installation connection with the driving mechanism through other connecting parts. The elastic contact surfaces of the two clamping plates 5 protrude outward from the outer surfaces of the two side plates 15 of the frame body 10 in the natural state, so that when the two clamping plates 5 approach, the elastic contact surfaces first contact the packaging bag mouth and produce elastic deformation.

[0034] On the basis of the above implementation, the driving circuit includes an electrical signal detection module and a frequency-voltage regulation module. The electrical signal detection module detects the characteristic value of the charge signal generated by the piezoelectric ceramic sheet due to the pulling of the spring 6. The frequency-voltage regulation module presets a signal characteristic threshold. When the detected value is less than the threshold, the piezoelectric ceramic sheet in the corresponding area vibrates at 50 - 100 Hz and a voltage of ±100 - 150 V is applied; when the detected value ≥ the threshold, the piezoelectric ceramic sheet in the corresponding area does not start. Specifically, the electrical signal detection module is electrically connected to the polarization direction of the piezoelectric ceramic sheet and is used to detect the characteristic value of the charge signal generated by the piezoelectric ceramic sheet due to the pulling of the spring 6. The frequency-voltage regulation module presets a signal characteristic threshold. When the detected value corresponding to the charge signal characteristic is less than the threshold, it is determined that the bag mouth has no material, and the piezoelectric ceramic sheet in the corresponding area is started to vibrate at a frequency of 50 - 100 Hz and a driving voltage of ±100 - 150 V is applied; when the detected value corresponding to the charge signal characteristic is greater than or equal to the threshold, it is determined that the bag mouth has material, and the piezoelectric ceramic sheet in the corresponding area remains in the low-frequency area and does not start to vibrate.

[0035] On the basis of the above implementation, several mounting seats 11 are provided on the inner sides of the two enclosing plates 15 of each clamping plate 5. One end of each piezoelectric ceramic sheet is connected to the inner side of the enclosing plate 15 through an adhesive, and the other end is connected to the mounting seat 11 through an adhesive. A second mounting hole is provided on the mounting seat 11, and both ends of the spring 6 of the parallel spring 6 group are respectively mounted on the second mounting holes of the two enclosing plates 15, so that the piezoelectric ceramic sheet forms a vibration transmission structure with the spring 6 through the mounting seat 11. The vibration transmission structure of the mounting seat 11 and the spring 6 improves the amplitude uniformity of the piezoelectric ceramic sheet to ±0.03 mm and avoids damage to the ceramic sheet caused by local stress concentration.

[0036] On the basis of the above implementation, a negative pressure suction pipe is installed on the top plate 14 of the frame 10 of one of the two clamping plates 5. Suction holes are provided on the lower side of the negative pressure suction pipe. The negative pressure suction pipe is connected to a blower through a switching valve. The suction holes are used to suck scattered materials and dust during the exhaust process and convey them through a pipeline to a cyclone dust collector for cleaning.

[0037] On the basis of the above implementation, the negative pressure suction pipe is a rigid pipe body. The negative pressure suction pipe 13 abuts against the spring 6. During the exhaust process of the bag mouth, the vibration of the spring 6 is transmitted to the negative pressure suction pipe, which can not only reduce the blockage of the negative pressure suction pipe, but also is beneficial to the suction of scattered materials and dust by the suction holes, so as to improve the exhaust efficiency, reduce material pollution and keep the bag mouth clean. The vibration coupling design of the negative pressure suction pipe and the spring 6 reduces the pipeline blockage frequency from 3 times a week to 1 time a month. The synchronous action of suction and vibration improves the suction efficiency of 0.1 - 0.3 mm dust to 93%, and cooperates with the cyclone dust collector to achieve a material recovery rate of more than 95%.

[0038] On the basis of the above implementation manner, it further includes a guiding component for restricting the relative movement path of the two clamping plates 5. The guiding component includes a guide rail 1 fixed on the machine frame and two sliding brackets 2; the sliding brackets 2 are slidably connected to the guide rail 1, and each sliding bracket 2 is connected to the corresponding clamping plate 5 through a support arm 3; the driving mechanism is connected to the two sliding brackets 2 (for example, the driving mechanism selects a bidirectional telescopic cylinder 4, and its two telescopic ends are respectively connected to the two sliding brackets 2), driving the two sliding brackets 2 to move relatively on the guide rail 1, so that the two clamping plates 5 approach or move away from each other.

[0039] On the basis of the above implementation manner, it further includes two arc-shaped plates 7 for straightening the packaging bag. The two arc-shaped plates 7 are located on the two outer sides below the two clamping plates 5; the two arc-shaped plates 7 are correspondingly connected to the two clamping plates 5, so that the two arc-shaped plates 7 move synchronously with the two clamping plates 5, driving the jaws of the two arc-shaped plates 7 to approach and move away from each other; during the exhaust process, the two arc-shaped plates 7 support and straighten the packaging bag, making the packaging bag in a vertical and stable state, which is beneficial to exhaust. The arc-shaped plates 7 move synchronously with the clamping plates 5, and the perpendicularity deviation of the packaging bag is reduced from ±5° to ±1°, avoiding exhaust dead angles caused by inclination. The double arc-shaped plate 7 support structure makes the force distribution on the packaging bag uniform and reduces the bag body breakage rate.

[0040] When the present invention is in use: After materials such as fertilizers or feeds are loaded into the packaging bag, they are transported to the exhaust device through the conveying platform 8. According to the system preset time or the in-place signal of the detection device, the driving mechanism drives the two clamping plates 5 to approach each other, presses against the bag mouth until the frame 10 contacts; During the pressing process, the electric signal detection module continuously detects the characteristic value of the charge signal generated by the piezoelectric ceramic sheet due to the pulling of the spring 6; the frequency-voltage adjustment module presets the signal characteristic threshold. When the detected value is less than the threshold, it is determined that there is no material at the bag mouth, and the piezoelectric ceramic sheet in the corresponding area vibrates at 50-100 Hz and applies a voltage of ±100-150 V. The piezoelectric ceramic sheet vibrates along the polarization direction, driving the elastic contact surface to vibrate, thereby realizing the functions of bag mouth exhaust and material vibration and falling. When the detected value ≥ the threshold, it is determined that there is material at the bag mouth, and the piezoelectric ceramic sheet in the corresponding area does not start.

[0041] During the pressing process, the negative pressure suction pipe is communicated with the blower through the on-off valve, and the suction holes on its lower side suck the scattered materials and dust, and transport them to the cyclone dust collector through the pipeline for cleaning.

[0042] From the start of exhaust to the end of exhaust detection and control or until the exhaust ends at the preset time, the driving mechanism moves the two clamping plates 5 away, and the packaging bag continues to be transported to the sealing process.

[0043] Example Taking a fertilizer packaging factory as an example, this piezoelectric vibration-based bag mouth exhaust device is used to exhaust the 50 kg fertilizer packaging bags.

[0044] Device parameter settings: For the 6 parallel springs 6, the spring 6 is made of 60Si2Mn spring steel with an elastic coefficient of 200 N / m, a diameter of 12 mm, a free length of 80 mm, and a pre-compression of 10 mm, ensuring that the elastic contact surface protrudes 5 mm outside the surface of the apron 15 in the natural state.

[0045] The piezoelectric ceramic sheets are of PZT-5H type, with dimensions of 30×15×1 mm. 8 sheets are installed at each end of each splint 5 and bonded to the apron 15 and the mounting seat 11 through epoxy resin adhesive. The polarization direction is perpendicular to the axial direction of the spring 6.

[0046] The electrical signal detection module of the drive circuit uses an AD549 charge amplifier with a gain set to 1000 V / C, combined with a second-order RC low-pass filter with a cut-off frequency of 1 kHz. The frequency-voltage adjustment module is based on an STM32F407 microcontroller with a built-in DDS signal generator, driving an H-bridge power amplifier (THS3091) to output a sine wave. The preset signal characteristic threshold is 0.5 V.

[0047] The negative pressure suction pipe is made of a φ50 mm stainless steel pipe, with 4 rows of φ2 mm suction holes on the pipe wall, spaced 10 mm apart. It is connected to a vortex blower through a DN25 ball valve. The air volume of the blower is 150 m 3 / h, and the negative pressure is -20 kPa.

[0048] Production process: When the fertilizer packaging bag is conveyed to the exhaust device by the conveyor belt, the drive mechanism drives the two splints 5 to approach. The elastic contact surface of the splint 5 first touches the bag mouth and starts to press against the bag mouth.

[0049] During the pressing process, the electrical signal detection module continuously detects the charge signal characteristic value generated by the piezoelectric ceramic sheet due to the pulling of the spring 6 and transmits it to the frequency-voltage adjustment module.

[0050] The frequency-voltage adjustment module compares the detected value with the preset threshold of 0.5 V. When the detected value is less than the threshold, the piezoelectric ceramic sheets in the corresponding area vibrate at a frequency of 75 Hz and a voltage of ±120 V is applied. For example, in the upper area of the bag mouth (corresponding to the area without materials), the vibration of the piezoelectric ceramic sheets effectively discharges the air in the bag and shakes off any remaining fertilizer particles.

[0051] When the detected value ≥ the threshold, the piezoelectric ceramic sheets in the corresponding area do not start. For example, in the lower area of the bag mouth (corresponding to the area with materials), the piezoelectric ceramic sheets remain stationary to avoid excessive disturbance to the materials.

[0052] During the entire exhaust process, the negative pressure suction pipe is always in working condition. The fan sucks the scattered fertilizer dust through the suction hole and transports it to the cyclone dust collector for cleaning. Since the negative pressure suction pipe is a hard pipe body and contacts the spring 6, the vibration of the spring 6 is transmitted to the negative pressure suction pipe, which reduces the blockage of the adsorption pipe and is conducive to the suction hole to suck the scattered materials and dust, improves the exhaust efficiency, reduces material pollution and keeps the bag mouth clean.

[0053] After about 1.5 seconds of exhaust time, the driving mechanism moves the two clamping plates 5 away from each other, and the packaging bag that has been exhausted continues to be conveyed to the sealing process.

[0054] Effect evaluation: Through the testing of multiple bags of fertilizer packaging, it was found that after adopting the exhaust device of this combined solution, the amount of residual air in the bag was significantly reduced, and the average residual air volume dropped to below 3%, which effectively improved the sealing and stability of the packaging bag.

[0055] The residual rate of material at the bag mouth is also significantly reduced, and the residual rate of particles smaller than 0.5mm is reduced to below 3%, reducing the impact of material residue on sealing quality.

[0056] The dust concentration in the working area is effectively controlled and reduced to 2mg / m 3 The following improves the working environment and protects the health of operators.

[0057] Compared with traditional exhaust devices, the energy consumption of this device is significantly reduced, and the energy consumption per unit time is only about 60% of that of traditional devices, saving production costs.

[0058] In summary, the bag mouth exhaust device based on piezoelectric vibration of the present invention shows good performance in practical applications, can effectively solve the problems in the exhaust process of packaging bags such as fertilizers and feeds, and improve packaging quality and production efficiency.

[0059] The present invention also provides a control method for a bag outlet exhaust device based on piezoelectric vibration, which is used to control the above-mentioned bag outlet exhaust device, including two clamping plates 5 that can move closer to or farther away from each other, a driving mechanism, negative pressure adsorption, a piezoelectric vibration component 12, an electrical signal detection module and a frequency voltage adjustment module; The control method comprises the following steps: When exhaust begins, the driving mechanism drives the two clamping plates to approach the bag opening, and the two arc-shaped plates move synchronously to straighten the bag until the two frames collide with each other. During the exhaust process, scattered materials and dust are simultaneously sucked through a negative pressure suction pipe. Specifically, during the exhaust process, the scattered materials and dust are sucked through the suction holes of the negative pressure suction pipe and transported to a cyclone dust collector for cleaning. During the exhaust process, the two arc-shaped plates 7 and the two clamping plates 5 move synchronously to support and straighten the packaging bag. The electrical signal detection module detects the charge signal characteristics generated by the piezoelectric ceramic sheet due to the pulling of the spring 6 to obtain a detection value. The frequency-voltage adjustment module compares the detection value with a preset threshold: If the detection value is less than the threshold, the piezoelectric ceramic sheet in the corresponding area is started to vibrate at a frequency of 50 - 100 Hz and a voltage of ±100 - 150 V is applied; if the detection value ≥ the threshold, the piezoelectric ceramic sheet in the corresponding area is not started to vibrate. Specifically, the frequency-voltage adjustment module compares the detected charge signal characteristics with a preset signal characteristic threshold. When the detected value corresponding to the charge signal characteristics is less than the threshold, it is determined as the bag mouth without materials, and the piezoelectric ceramic sheet in the corresponding area is started to vibrate at a frequency of 50 - 100 Hz and a driving voltage of ±100 - 150 V is applied; when the detected value corresponding to the charge signal characteristics is greater than or equal to the threshold, it is determined as the bag mouth with materials, and the piezoelectric ceramic sheet in the corresponding area remains in the low-frequency area without starting to vibrate. Continuous detection and control are performed until the exhaust ends, and the driving mechanism moves the two clamping plates 5 away and the negative pressure suction pipe is closed.

[0060] On the basis of the above implementation method, when the driving mechanism drives the two clamping plates 5 to approach, the driving action stops when the contact sensors arranged on the opposite surfaces of the frame 10 come into contact with each other. During the exhaust process, the suction of the fan of the negative pressure suction pipe is synchronously controlled. The control unit is communicatively connected to the driving mechanism, the switching valve of the negative pressure suction pipe, the electrical signal detection module, and the frequency-voltage adjustment module, receives the detection value (the voltage amplitude signal of the charge signal characteristics) output by the electrical signal detection module, and compares it with a preset threshold: If the detection value < the threshold, the piezoelectric ceramic sheet in the corresponding area is controlled to vibrate at 50 - 100 Hz and a voltage of ±100 - 150 V is applied; if the detection value ≥ the threshold, the corresponding area is controlled not to start vibrating. The control unit continuously monitors and controls the above process, and after the exhaust ends, the clamping plate 5 is driven to separate and the negative pressure suction pipe is closed.

[0061] The test process of this control method: Initial positioning: After the packaging bag enters the working station, the driving mechanism (double-acting cylinder) pushes the clamping plate 5 to approach at a speed of 0.2 m / s.

[0062] The contact sensor (model: OMRON EE-SX672) monitors the contact state of the frame 10 in real time. When the detected pressure ≥ 0.5 MPa (trigger threshold), the cylinder immediately stops operating.

[0063] Synchronous control: After the control unit (PLC S7-1200) starts the splint 5 to push, the negative pressure suction pipe is synchronously started (opening time 1.5 seconds), and the fan (power 0.75 kW) generates a negative pressure of -20 kPa.

[0064] The electrical signal detection module collects the charge signal of the piezoelectric ceramic sheet at a sampling frequency of 1 kHz. After passing through a charge amplifier (gain 1000 V / C) and a low-pass filter (cut-off frequency 100 Hz), the voltage signal is output to the control unit.

[0065] Dynamic adjustment: The control unit compares the detected value with the preset threshold (0.5 V): When the detected value < 0.5 V, the trigger frequency voltage adjustment module outputs a 75 Hz sine wave (peak-to-peak ±120 V), and the piezoelectric ceramic sheet in the corresponding area vibrates.

[0066] When the detected value ≥ 0.5 V, it remains in the low-frequency standby state.

[0067] During the entire exhaust cycle (1.5 seconds), the control unit continuously monitors and adjusts the parameters to ensure that the vibration intensity in the area without materials ≥ 0.8 g (acceleration).

[0068] End process: After the exhaust is completed, the control unit shuts down the negative pressure system and drives the cylinder to reset (return speed 0.2 m / s).

[0069] After the contact sensor detects the separation signal of the splint 5, the control unit records the data of this processing (exhaust time, number of vibrations, etc.).

[0070] The present invention discloses a bag mouth exhaust control system, which is used to control the above-mentioned bag mouth exhaust device including two splints 5 that can approach or move away from each other, a driving mechanism, a piezoelectric vibration assembly 12, a negative pressure suction pipe, two arc-shaped plates 7, and a contact sensor arranged on the opposite surfaces of the frames 10 of the two splints 5. The system includes: A contact sensor circuit, connected to the contact sensor, detects whether the frames 10 of the two splints 5 are in contact, and transmits a switch signal to the control unit; An electrical signal detection module circuit, connected to the polarization direction of the piezoelectric ceramic sheet, including a charge amplifier and a low-pass filter, is used to detect the charge signal characteristics generated by the piezoelectric ceramic sheet in the polarization direction due to the pulling of the spring 6 and transmit the corresponding voltage signal; A driving mechanism control circuit, receives the instructions of the control unit, and drives the splint 5 and the arc-shaped plate 7 to act; A frequency-voltage regulation module circuit, including a signal generator and a power amplifier, controls the vibration of the piezoelectric ceramic sheet according to the instructions of the control unit; A negative pressure suction pipe control circuit controls the opening and closing of the negative pressure suction pipe according to the signal of the control unit; An isolation circuit, using an optocoupler, is arranged between the electrical signal detection module circuit and the frequency-voltage regulation module circuit; The control unit controls the driving mechanism and the negative pressure suction pipe to execute instructions according to the preset time, receives the switch signal of the contact sensor and the pulling force detection value of the electrical signal detection module, and after comparing and processing with the preset threshold, sends corresponding control instructions to the frequency-voltage regulation module.

[0071] Specifically: The contact sensor circuit is connected to the contact sensor and is used to detect whether the frames 10 of the two clamping plates 5 are in contact, and transmits the detected switch signal to the control unit; The electrical signal detection module circuit is electrically connected to the polarization direction of the piezoelectric ceramic sheet and is used to detect the charge signal characteristics generated by the piezoelectric ceramic sheet in the polarization direction due to the pulling of the spring 6; this circuit includes a charge amplifier that converts the weak charge signal into a voltage signal, and also has a low-pass filter to filter out high-frequency noise to obtain a stable pulling force detection voltage signal and transmits this signal to the control unit; The driving mechanism control circuit is connected to the control unit and the driving mechanism, receives the driving instruction issued by the control unit, drives the two clamping plates 5 to approach or separate from each other, and drives the two arc-shaped plates 7 to move synchronously with the two clamping plates 5 to straighten the packaging bag; The frequency-voltage regulation module circuit is connected to the control unit and the piezoelectric ceramic sheet. According to the instruction of the control unit, when it is determined that there is no material at the bag mouth, the piezoelectric ceramic sheet in the corresponding area is started to vibrate at a frequency of 50 - 100 Hz and a driving voltage of ±100 - 150 V is applied; when it is determined that there is material at the bag mouth, the piezoelectric ceramic sheet in the corresponding area is kept in the low-frequency area without starting to vibrate; this circuit includes a signal generator that generates an alternating signal of 50 - 100 Hz, and a power amplifier that amplifies the alternating signal to the required driving voltage; The negative pressure suction pipe control circuit is connected to the control unit and controls the opening or closing of the negative pressure suction pipe according to the signal of the control unit, and sucks and cleans the scattered materials and dust during the exhaust process; An isolation circuit, using an optocoupler, is arranged between the electrical signal detection module circuit and the frequency-voltage regulation module circuit to enable the frequency-voltage regulation module to receive the detection value (voltage amplitude signal of the charge signal characteristics) of the piezoelectric ceramic sheet detected by the electrical signal detection module; The control unit controls the driving mechanism and the negative pressure suction pipe to execute instructions according to a preset time, receives the switch signal of the contact sensor and the pulling force detection value of the electrical signal detection module, and after comparing and processing with the preset threshold value, issues corresponding control instructions to the frequency-voltage regulation module to control the completion of functions such as straightening the packaging bag, exhausting the bag mouth, vibrating the material down, and sucking dust.

[0072] The usage process of this system: Signal acquisition: The contact sensor circuit converts the mechanical contact signal into a TTL level (0V / 5V) through a voltage-dividing resistor (10kΩ) and a Schmitt trigger (74HC14).

[0073] The electrical signal detection module detects the charge signal of the piezoelectric ceramic sheet, converts it into a voltage signal (range -5V to +5V) through a charge amplifier (AD549), and transmits it to the control unit after low-pass filtering.

[0074] Drive control: The control unit (STM32F407) controls the H-bridge power amplifier (THS3091) to output a sine wave of 50 - 100Hz through a PWM signal according to a preset program.

[0075] The drive mechanism control circuit uses a solid-state relay (SSR) to switch the cylinder solenoid valve, and the response time < 10ms.

[0076] Negative pressure and isolation: The negative pressure suction pipe control circuit realizes the opening and closing control of the switching valve through a relay (G6B-1174P), and opens synchronously with a 0.3-second delay from the vibration signal.

[0077] The isolation circuit (TLP281-4 optocoupler) isolates the signal ground and the power ground to suppress common-mode interference (rejection ratio > 60dB).

[0078] System coordination: The control unit communicates with the host computer through the CAN bus to display the detection value, vibration parameters, and equipment status in real time.

[0079] Exception handling: When the detection value exceeds the threshold (such as > 1.0V), trigger overload protection, automatically reduce the drive voltage and alarm.

[0080] Example A certain chemical raw material packaging line is equipped with this device and circuit system: Hardware configuration: Control unit: STM32F407ZGT6 microcontroller (main frequency 168MHz).

[0081] Power supply module: AC / DC converter (24V to 5V, 10A).

[0082] Communication interface: RS485 + CAN2.0B.

[0083] Test results: EMC test: Conduction interference (150 kHz - 30 MHz) complies with CISPR22 Class B standard.

[0084] Immunity: No reset for ±8 kV air discharge, normal function for ±4 kV contact discharge.

[0085] Long-term operation: Continuous operation for 1000 hours without failure, vibration frequency stability ±0.1%.

[0086] Modular circuit design shortens the fault troubleshooting time to 15 minutes. The optoelectronic isolation technology ensures the reliability of signal transmission. System MTBF > 10000 hours.

[0087] Note: The above data is based on laboratory tests and may vary slightly in actual applications due to different working conditions.

[0088] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made.

Claims

1. A bag outlet exhaust device based on piezoelectric vibration, characterized in that: It includes two clamping plates, a driving mechanism, and a piezoelectric vibration component; The two clamping plates are relatively movably arranged on the packaging bag conveying path, and each clamping plate includes: The frame has an open lower end and is provided with a horizontal top plate and enclosures extending downwards on both sides; A parallel spring group, which is composed of a plurality of parallel springs arranged between two enclosure plates to form an elastic contact surface; The piezoelectric vibration component includes at least one piezoelectric ceramic sheet, which is glued between the enclosure plate and the spring, has a polarization direction perpendicular to the axial direction of the spring, and is applied with an alternating electric field through a driving circuit; The driving mechanism drives the two clamping plates to move closer or farther away, and the lower part of the elastic contact surface corresponds to the material area of ​​the bag opening, and the upper part corresponds to the area without material; The piezoelectric ceramic vibrates along the polarization direction under the alternating electric field.

2. The bag outlet exhaust device based on piezoelectric vibration according to claim 1, characterized in that: The driving circuit comprises: An electrical signal detection module detects the charge signal generated by the piezoelectric ceramic piece due to the spring pulling; The frequency voltage regulation module controls the piezoelectric ceramic piece in the corresponding area to vibrate at a frequency of 50-100Hz and apply a voltage of ±100-150V when the detection value is less than the preset threshold value; the vibration is stopped when the detection value is ≥ the threshold value.

3. The bag outlet exhaust device based on piezoelectric vibration according to claim 2, characterized in that: A plurality of mounting seats are arranged on the inner side of the enclosure, and each mounting seat has a second mounting hole; one end of the piezoelectric ceramic piece is glued to the enclosure, and the other end is glued to the mounting seat; both ends of the spring are fixed to the second mounting holes of the two enclosures, forming a vibration transmission chain of the piezoelectric ceramic piece-mounting seat-spring.

4. The bag outlet exhaust device based on piezoelectric vibration according to any one of claims 1 to 3, characterized in that: A negative pressure suction pipe is provided on the top plate of a clamping plate, and a suction hole is opened on the lower side of the negative pressure suction pipe; the negative pressure suction pipe is connected to the fan through a switch valve, and the suction hole sucks the scattered materials and dust and transports them to the cyclone dust collector.

5. The bag outlet exhaust device based on piezoelectric vibration according to claim 4, characterized in that: The negative pressure suction tube is a hard tube body and contacts with the spring surface of the parallel spring group.

6. The bag outlet exhaust device based on piezoelectric vibration according to any one of claims 1 to 3 or 5, characterized in that: Also included are guide components, including: Fixed rails; Two sliding brackets are slidably connected to the guide rails and connected to corresponding clamping plates through support arms; The driving mechanism drives the sliding bracket to move relatively, driving the clamping plate to move closer or farther away synchronously.

7. The bag outlet exhaust device based on piezoelectric vibration according to claim 6, characterized in that: It also includes two arc-shaped plates, which are respectively located on the outer sides below the two clamping plates; the arc-shaped plates are fixedly connected to the corresponding clamping plates and move with the clamping plates to form a tiger's mouth-shaped straightening structure.

8. A control method for a bag outlet exhaust device based on piezoelectric vibration, characterized in that: Used to control the bag outlet exhaust device as claimed in claim 7, comprising: a) Drive the two clamping plates close to the bag opening, and the arc plate synchronously straightens the packaging bag until it contacts the frame; during this process, the negative pressure suction pipe is synchronously started to suck the scattered materials; b) Detecting the charge signal of the piezoelectric ceramic piece. When the detection value is less than the threshold value, the piezoelectric ceramic piece in the corresponding area is started to vibrate at 50-100 Hz and a voltage of ±100-150 V is applied; when the detection value is greater than or equal to the threshold value, the piezoelectric ceramic piece in the corresponding area stops vibrating; c) Continue to execute step b until the exhaust is completed, drive the two clamping plates to separate and close the negative pressure suction pipe.

9. A bag outlet exhaust control system, characterized in that: include: A contact sensor circuit detects the contact status of the two clamping plate frames; The electric signal detection module circuit includes a charge amplifier and a filter, and is connected to the polarization direction electrodes of the piezoelectric ceramic piece; The frequency voltage regulation module circuit includes a signal generator and a power amplifier, outputs a 50-100Hz alternating voltage, and is connected to the polarization direction electrodes of the piezoelectric ceramic piece; Isolation circuit, using photocoupler to isolate detection and regulation circuit; A control unit executes the steps of the method as claimed in claim 8 and coordinates the driving mechanism, negative pressure suction and vibration control.

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