An online self-cleaning die device and method suitable for high-temperature extrusion production line

Abstract

The application discloses an online self-cleaning die device and method suitable for a high-temperature extrusion production line, which comprises a die main body, a high-temperature pyrolysis unit and a scraping unit. The die main body comprises an upper die lip and a lower die lip which are arranged in parallel and form a melt flow channel between the two, and the discharge end of the upper die lip and the lower die lip forms a lip opening. The high-temperature pyrolysis unit is used for blowing high-temperature nitrogen to the outer surface of the upper die lip and the lower die lip to carbonize the accumulated material. The scraping unit comprises a scraper and a driving assembly for driving the scraper to reciprocate along the width direction of the outer surface of the lip opening. The application can complete online cleaning under the normal production condition of high-temperature extrusion without speed reduction and temperature reduction, completely eliminates the production capacity interruption, raw material loss and waste of heating and cooling energy consumption caused by traditional shutdown cleaning, and significantly improves the comprehensive efficiency of the production line OEE and the annual effective production length.

Description

Technical Field

[0001] This invention relates to the field of high-temperature film extrusion technology, and in particular to an online self-cleaning die device and method suitable for high-temperature extrusion production lines. Background Technology

[0002] In the extrusion molding process of PEEK (polyether ether ketone), PEI (polyether imide), TPI (thermoplastic polyimide), PPSU (polyphenylene sulfone), and PPS (polyphenylene sulfide) films, the melt processing temperature is as high as 300-430℃. When the high-temperature melt flows through the die runner, the low molecular weight oligomers, thermal degradation products, and functional additives contained therein are very easy to precipitate, adhere, and continuously accumulate on the material exit surfaces of the upper and lower die lips, forming stubborn "die lip accumulation".

[0003] As production time increases, the material buildup on the die lip will gradually thicken, carbonize, and harden. If it cannot be removed in a timely and effective manner, the buildup will periodically fall off and get caught in the extruded film, or directly scratch the film surface, causing quality defects such as crystal points, black spots, particle protrusions, holes, and excessive thickness deviations in the product. This greatly reduces the film yield, limits the continuous production time of the production line, and increases the frequency of downtime maintenance and production costs.

[0004] Currently, the industry mainly uses three methods to clean up material buildup in extrusion dies, all of which have inherent technical flaws and cannot be adapted to high-precision, continuous, and high-temperature mass production conditions: One method is periodic shutdown and manual cleaning. This method requires stopping the production line and waiting for the die to cool down naturally before operators manually remove the accumulated material from the die lip using tools such as copper shovels and sandpaper. This method causes production interruptions, significant capacity losses, and serious waste of raw materials. Furthermore, the force of manual scraping is uncontrollable, which can easily scratch the high-precision mirror die lip and surface coating. Die lip repair and replacement are costly, seriously affecting production continuity and economy.

[0005] Secondly, there is the online manual passive wiping. A few production lines use high-temperature resistant cloths and asbestos sticks to manually wipe the die lip at close range. This operation is carried out at a high temperature of over 380°C, which is difficult to operate and has extremely high safety risks. At the same time, there are no collection measures for the accumulated dust that falls off during wiping, which is very easy to fall and adhere to the film surface and cooling roller surface, resulting in significant secondary pollution problems and poor cleaning effect, which cannot meet the requirements of high-end film production.

[0006] Thirdly, there is the method of cleaning with a single hot air purging. This method relies solely on high-temperature hot air to bake and melt the accumulated material. In practical applications, this method cannot remove stubborn accumulated material that has already been carbonized and hardened, resulting in incomplete cleaning. Furthermore, the open-air high-temperature hot air will disrupt the melt flow field and temperature field at the die exit, causing increased lateral thickness deviation and poor flatness of the film, which seriously affects product precision and makes industrial application impossible.

[0007] In summary, existing technologies generally suffer from numerous drawbacks, such as the need for machine shutdown for cleaning, damage to precision die lips, incomplete cleaning, easy generation of secondary pollution, disturbance of melt flow field, and lack of automated control capabilities. Currently, the industry lacks an online die self-cleaning technology solution that is suitable for ultra-high temperature extrusion conditions, can achieve continuous production without machine shutdown, has no die damage, no secondary pollution, and operates in a fully automated closed loop. Summary of the Invention

[0008] To address the technical problems in existing high-temperature extrusion die cleaning, such as the need for machine shutdown, damage to precision die lips, and incomplete cleaning, this invention provides an online self-cleaning die device and method suitable for high-temperature extrusion production lines to solve the above problems.

[0009] This invention proposes an online self-cleaning die device suitable for high-temperature extrusion production lines, comprising a die body, a high-temperature pyrolysis unit, and a scraping unit. The die body includes an upper die lip and a lower die lip arranged relatively parallel to each other and forming a melt flow channel between them. The discharge ends of the upper and lower die lips form lip openings. The high-temperature pyrolysis unit is used to blow high-temperature nitrogen gas onto the outer surfaces of the upper and lower die lips to carbonize the accumulated material. The scraping unit includes a scraper and a drive assembly that drives the scraper to reciprocate along the width direction of the outer surface of the lip opening.

[0010] In an optional embodiment of the present invention, the high-temperature pyrolysis unit includes a high-temperature nitrogen generator and a gas supply pipe located inside the upper and lower mold lips and extending toward the end face of the lip opening, wherein the gas supply pipe forms a plurality of gas outlets at the end face of the lip opening.

[0011] In an optional embodiment of the present invention, each of the upper and lower die lips is provided with a scraping unit at its discharge end.

[0012] In an optional embodiment of the present invention, the driving assembly includes a guide rail and a drive motor fixed on the die body, and a base that slides with the guide rail. An elastic element is provided at one end of the base facing the die body, and the scraper is fixed on the elastic element.

[0013] In an optional embodiment of the present invention, the scraper is a DLC-coated beryllium copper sheet, and the hardness of the scraper is lower than the hardness of the coating on the surface of the die body.

[0014] In an optional embodiment of the invention, a negative pressure dust collection unit is also included for adsorbing the accumulated material scraped off by the scraping unit.

[0015] In an optional embodiment of the present invention, the negative pressure dust collection unit includes a negative pressure vacuum cleaner and a dust collection box located directly below the scraping unit.

[0016] This invention also proposes a cleaning method suitable for high-temperature extrusion production lines. The method employs the online self-cleaning die device described above for high-temperature extrusion production lines and includes the following steps: S1: Surface inspection. Check whether there is material accumulation on the outer end face of the lip. If the amount of material accumulation reaches the predetermined standard, proceed to step S2.

[0017] S2: High-temperature pyrolysis embrittlement. Start the high-temperature pyrolysis unit and spray high-temperature nitrogen into the material accumulation area for 10~20 seconds.

[0018] S3: Non-destructive scraping. Start the drive assembly to drive the scraper blade to reciprocate along the width of the lip, so that the scraper blade scrapes away the carbonized material.

[0019] In an optional embodiment of the present invention, the device further includes a laser displacement sensor fixed to the side of the lip, the laser displacement sensor being electrically connected to the controller.

[0020] In step S1, a laser displacement sensor is used to detect the material accumulation height on the outer end face of the lip. When the material accumulation height reaches the specified value, the process proceeds to step S2.

[0021] In an optional embodiment of the present invention, the temperature of the high-temperature nitrogen gas in step S2 is 600°C to 650°C.

[0022] The beneficial effects of this invention are: (1) Continuous production without stopping the machine, greatly improving capacity utilization. This invention can complete online cleaning under normal high-temperature extrusion production conditions without speed reduction or temperature reduction, completely eliminating the capacity interruption, raw material loss, and energy waste caused by traditional shutdown cleaning, and significantly improving the overall OEE efficiency and annual effective production time of the production line.

[0023] (2) Truly achieve zero-damage cleaning of mold lips and reduce maintenance costs. Abandoning the traditional metal hard scraper and hard wiping structure, the innovative idea of ​​"high temperature inert gas embrittlement and viscosity reduction + ultra-low stress flexible scraping" is adopted to avoid rigid contact damage in principle, perfectly protect the high-precision mold lip and surface coating, greatly extend the service life of the mold, and reduce the cost of mold repair and replacement.

[0024] (3) Undisturbed flow field and high product forming accuracy. The inert nitrogen gas gentle pyrolysis pretreatment is used, which is different from open hot air direct blowing. It will not disturb the temperature field and flow field distribution of the melt outlet, effectively ensuring the uniformity of the extruded film thickness and the surface flatness. The product accuracy is far superior to the single hot air cleaning solution. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1This is a front view of a specific embodiment of the online self-cleaning die device for high-temperature extrusion production lines described in this invention; Figure 2 yes Figure 1 The right view; Figure 3 This is a flowchart of the cleaning method applicable to high-temperature extrusion production lines according to the present invention.

[0027] In the figure, 1. Die body, 101. Upper die lip, 102. Lower die lip, 2. Lip opening, 3. Melt flow channel, 4. High-temperature nitrogen generator, 5. Gas supply pipe, 501. Gas outlet, 6. Scraper, 7. Guide rail, 8. Drive motor, 9. Base, 10. Elastic component, 11. Negative pressure vacuum cleaner, 12. Dust collection box, 13. Laser displacement sensor. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0029] An online self-cleaning die device suitable for high-temperature extrusion production lines includes a die body 1, a high-temperature pyrolysis unit, and a scraping unit. The die body 1 includes an upper die lip 101 and a lower die lip 102 arranged relatively parallel to each other and forming a melt flow channel between them. The discharge ends of the upper die lip 101 and the lower die lip 102 form a lip 2. Figure 1 As shown, a flat melt flow channel is formed between the upper die lip 101 and the lower die lip 102 to allow the high-temperature melt to be extruded and molded uniformly. Figure 1 The horizontal direction in the diagram represents the flow direction of the melt. The left end of the melt channel is the melt inlet, and the right end is the outlet. Therefore, the opening at the right end is the lip 2. The device described in this invention is used to clean the accumulated material at the end of the lip 2. The upper die lip 101 and the lower die lip 102 are typically made of high-temperature resistant austenitic stainless steel. The working surfaces are precision polished and coated with a diamond-like carbon (DLC) wear-resistant and corrosion-resistant coating. The surface roughness Ra≤0.05μm meets the long-term high-temperature resistance requirement of 400℃, reduces the probability of low molecular weight component adhesion, and ensures the flatness and thickness accuracy of the extruded film.

[0030] The high-temperature pyrolysis unit is used to purge high-temperature nitrogen gas onto the outer surfaces of the upper die lip 101 and the lower die lip 102 to carbonize the deposited material. The inert high-temperature nitrogen gas can isolate oxygen in the air, preventing the deposited material from continuous thermal and oxidative aging and hardening. At the same time, it rapidly pyrolyzes, embrittles, and de-adheses the already accumulated deposited material layer, destroying the bonding force between the deposited material and the coating surface of the lip 2, and changing the hard carbonized deposited material from a high-strength adhesion state to a loose and easily peelable state. Moreover, the inert gas purges gently without disturbing the central melt flow field, completely avoiding the flow field disturbance defects of traditional hot air.

[0031] The scraping unit includes a scraper 6 and a drive assembly that drives the scraper 6 to reciprocate along the width direction of the outer surface of the lip 2. The drive assembly drives the scraper 6 to reciprocate on the outer end face of the lip 2, peeling off and gently sweeping away the brittle accumulated material layer as a whole. The entire process is free of rigid impact and hard scraping, achieving zero-damage cleaning of the mold lip. A scraping unit is provided at the discharge end of both the upper mold lip 101 and the lower mold lip 102.

[0032] High-temperature pyrolysis unit: The high-temperature pyrolysis unit includes a high-temperature nitrogen generator 4 and a gas supply pipe 5 located within the upper mold lip 101 and the lower mold lip 102 and extending towards the end face of the lip 2. The gas supply pipe 5 forms a plurality of gas outlets 501 at the end face of the lip 2. The gas outlets 501 are preferably arranged in an array along the width direction of the ends of the upper mold lip 101 and the lower mold lip 102 (e.g., ...). Figure 2 (As shown). The high-temperature nitrogen generator 4 produces 600°C high-temperature inert nitrogen gas, which is injected through the outlet 501 to form a full-coverage nitrogen gas knife.

[0033] Driver components: The driving assembly includes a guide rail 7 fixed to the die body 1, a drive motor 8, and a base 9 slidably engaged with the guide rail 7. An elastic element 10 is provided at one end of the base 9 facing the die body 1, and a scraper 6 is fixed to the elastic element 10. The drive motor 8 drives the base 9 to perform reciprocating linear motion. The elastic element 10 allows the scraper 6 to float on the base 9, and the distance between the scraper 6 and the die lip end face can be adaptively adjusted, enabling the scraper 6 to conform to the minute curves and deformations of the die lip end face. The drive motor 8 can be a linear motor, directly driving the base 9 to move, or it can be a rotary motor, driving the base 9 to perform linear motion through intermediate connecting parts such as a lead screw.

[0034] The scraper 6 is preferably made of DLC-coated beryllium copper sheet, which has the characteristics of high temperature resistance, friction resistance and excellent toughness. The hardness of the scraper 6 is lower than that of the surface coating of the die body 1, which can prevent the scraper 6 from damaging the surface coating of the die lip.

[0035] In a further design, the device of the present invention also includes a negative pressure dust collection unit for adsorbing the accumulated material scraped off by the scraping unit. The negative pressure suction action starts and ends synchronously with the scraping operation, which can instantly capture all the peeled carbonized material dust and debris, completely preventing dust from scattering and falling back onto the film surface or the die lip and cooling roller surface, eliminating secondary pollution at the source, and ensuring a clean production environment after cleaning.

[0036] The negative pressure dust collection unit includes a negative pressure vacuum cleaner 11 and a dust collection box 12 located directly below the scraping unit. The length of the dust collection box 12 matches the width of the die lip discharge end. The dust collection box 12 is connected to the negative pressure vacuum cleaner 11 through a high-temperature resistant explosion-proof hose and maintains a constant negative pressure of -5kPa during operation.

[0037] This invention also proposes a cleaning method suitable for high-temperature extrusion production lines, wherein the method employs the online self-cleaning die device for high-temperature extrusion production lines described above, such as... Figure 3 As shown, it includes the following steps: S1: Surface inspection. Check for material accumulation on the outer end face of the lip 2. If the accumulation reaches a predetermined standard, proceed to step S2. This can be done manually or by fixing a laser displacement sensor 13 to the side of the lip 2. The laser displacement sensor 13 is electrically connected to the controller. The laser displacement sensor 13 detects the material accumulation height on the outer end face of the lip 2. When the material accumulation height reaches a specified value, proceed to step S2. The laser displacement sensor 13 continuously monitors during production. Assuming a preset material accumulation height threshold of 0.3mm, if the material accumulation height threshold is not exceeded, the laser displacement sensor 13 continues monitoring; if the material accumulation height threshold is exceeded, an automatic cleaning program is initiated.

[0038] S2: High-temperature pyrolysis embrittlement. The high-temperature pyrolysis unit is started, and high-temperature nitrogen gas is injected into the material accumulation area for 10~20 seconds. The temperature range of the high-temperature nitrogen gas is 600℃~650℃.

[0039] S3: Non-destructive scraping. Start the drive assembly to drive the scraper 6 to reciprocate along the width direction of the lip 2, so that the scraper 6 scrapes away the carbonized material.

[0040] When a negative pressure dust collection unit is installed, the negative pressure vacuum cleaner 11 is turned on simultaneously during the non-destructive scraping process, and all accumulated dust and debris are sucked up under constant negative pressure.

[0041] After cleaning, the laser displacement sensor 13 detects the surface condition of the mold lip. Once it confirms that there is no material accumulation or stains, all functional units automatically reset, the equipment returns to the monitoring standby state, and the production line continues to produce without interruption.

[0042] The cleaning method of the present invention is described below with reference to a specific embodiment. This embodiment is applied to a 1350mm wide PEEK film extrusion production line. The die body 1 is set to a working temperature of 380℃ and a film extrusion speed of 3m / min, which is the standard mass production condition in the industry.

[0043] After the production line has been running continuously and stably for 2 hours, the laser displacement sensor 13 detected that the material accumulation height at the end of the lip 2 reached 0.5mm, exceeding the system's preset trigger threshold of 0.3mm. The equipment then automatically started the fully automatic online cleaning process. The first step, high-temperature pyrolysis pretreatment: The high-temperature nitrogen generator 4 is started, and 600°C high-temperature inert nitrogen gas is uniformly sprayed into the die lip accumulation area through the arrayed gas outlets 501 for 15 seconds. The low molecular weight components inside the accumulation material rapidly pyrolyze and carbonize, and the structure becomes loose and brittle. The adhesion between the accumulation material and the die lip coating surface is completely lost, achieving a pre-peeling effect. Moreover, the process does not cause any disturbance to the central melt flow field, and the film extrusion state is stable.

[0044] The second step is flexible and non-destructive scraping: After the pretreatment is completed, the drive motor 8 drives the scraper 6 to start. Under the action of the elastic element 10, the scraper 6 closely adheres to the end face of the mold lip and moves smoothly from one end of the lip 2 to the other end at a uniform speed of 5mm / s. The working pressure of the scraper 6 is stably controlled at 0.4N / cm², and the embrittled material layer is swept off smoothly as a whole with ultra-low stress. There is no jamming, squeezing, or scratches during the scraping process.

[0045] The third step is synchronous negative pressure dust collection: the negative pressure dust collection unit is turned on at the same time as the scraper blade 6 starts. The negative pressure vacuum cleaner 11 maintains a constant negative pressure of -5kPa. All the carbonized material debris and dust scraped off are instantly and completely sucked into the dust collection bucket. There is no dust dispersion or secondary residue throughout the process.

[0046] The fourth step is automatic re-inspection and reset: The entire cleaning process takes 90 seconds. After cleaning, the laser displacement sensor 13 automatically scans the mold lip end face. After confirming that there is no material accumulation, scratches, or residual stains on the surface, the high-temperature pyrolysis unit, scraping unit, and negative pressure dust collection unit automatically reset in sequence. The equipment returns to the real-time monitoring standby state, and the production line continues to produce stably without any shutdown or speed reduction operations.

[0047] Verification by examples shows that this device cleans thoroughly, causes no mold damage, and eliminates secondary pollution. After cleaning, the number of thin film crystal points and black spot defects decreases by more than 95%, the continuous production time of the production line increases by more than 3 times, the frequency of mold maintenance is greatly reduced, and the industrialization benefits are significant.

[0048] In this specification, the illustrative expressions of the terms do not necessarily refer to the same embodiments. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0049] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An online self-cleaning die device suitable for high-temperature extrusion production lines, characterized in that, include: The die body includes an upper die lip and a lower die lip that are arranged relatively parallel to each other and form a melt flow channel between them, and the discharge ends of the upper die lip and the lower die lip form a lip opening; The high-temperature pyrolysis unit is used to purge high-temperature nitrogen gas onto the outer surfaces of the upper and lower die lips to carbonize the deposited material. The scraping unit includes a scraper and a drive assembly that drives the scraper to reciprocate along the width direction of the outer surface of the lip.

2. The online self-cleaning die device for high-temperature extrusion production lines according to claim 1, characterized in that: The high-temperature pyrolysis unit includes a high-temperature nitrogen generator and a gas supply pipe located inside the upper and lower mold lips and extending toward the end face of the lip opening. The gas supply pipe forms several gas outlets at the end face of the lip opening.

3. The online self-cleaning die device for high-temperature extrusion production lines according to claim 1, characterized in that: Each of the upper and lower die lips is equipped with a scraping unit at its discharge end.

4. The online self-cleaning die device suitable for high-temperature extrusion production lines according to claim 3, characterized in that: The drive assembly includes a guide rail and a drive motor fixed to the die body, and a base that slides with the guide rail. An elastic element is provided at one end of the base facing the die body, and the scraper is fixed on the elastic element.

5. The online self-cleaning die device for high-temperature extrusion production lines according to claim 1, characterized in that: The scraper is made of DLC-coated beryllium copper sheet, and the hardness of the scraper is lower than that of the coating on the surface of the die body.

6. The online self-cleaning die device for high-temperature extrusion production lines according to claim 1, characterized in that: It also includes a negative pressure dust collection unit for adsorbing and scraping the accumulated material removed by the scraping unit.

7. The online self-cleaning die device for high-temperature extrusion production lines according to claim 6, characterized in that: The negative pressure dust collection unit includes a negative pressure vacuum cleaner and a dust collection box located directly below the scraping unit.

8. A cleaning method suitable for high-temperature extrusion production lines, characterized in that, The method employs the online self-cleaning die device suitable for high-temperature extrusion production lines as described in any one of claims 1-7, and includes the following steps: S1: Surface inspection. Check whether there is material accumulation on the outer end face of the lip. If the amount of material accumulation reaches the predetermined standard, proceed to step S2. S2: High-temperature pyrolysis embrittlement. Start the high-temperature pyrolysis unit and spray high-temperature nitrogen into the material accumulation area for 10~20 seconds. S3: Non-destructive scraping. Start the drive assembly to drive the scraper blade to reciprocate along the width of the lip, so that the scraper blade scrapes away the carbonized material.

9. The cleaning method for a high-temperature extrusion production line according to claim 8, characterized in that: The device also includes a laser displacement sensor fixed to the side of the lip, and the laser displacement sensor is electrically connected to the controller; In step S1, a laser displacement sensor is used to detect the material accumulation height on the outer end face of the lip. When the material accumulation height reaches the specified value, the process proceeds to step S2.

10. The cleaning method for a high-temperature extrusion production line according to claim 8, characterized in that: In step S2, the temperature of the high-temperature nitrogen gas is 600℃~650℃.

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