Tableware forming system capable of solving material shortage of corners of sugarcane pulp tableware and achieving uniform thickness

Abstract

The invention discloses a tableware forming system capable of solving sugarcane pulp tableware corner material shortage and achieving uniform thickness. The tableware forming system comprises a pulp pool; negative pressure pre-coating treatment: a pre-coating mold matched with the shape of the formed target product is included, relative negative pressure is formed in the pre-coating mold, at least the local position in the pre-coating mold is kept in a negative pressure state, and the formed surface of the pre-coating mold is wrapped with plant fiber suspension slurry; moreover, fine and dense suction holes are formed in the forming surface, the pre-coating mold is matched with an internal negative pressure state to carry out solid-liquid separation on plant fiber suspension slurry in the wrapping forming process, so that the water content of plant fibers is reduced, the plant fibers are wrapped on the forming surface, and a pre-coating blank with a certain thickness is formed; according to the technical scheme, in order to solve the problems of corner material shortage and uneven thickness which are difficult to solve by a traditional process in cane syrup tableware forming, through the multi-level structure design of negative pressure pre-coating, precise hot pressing and flexible adaptation and process cooperation, remarkable technical advantages and practical value are shown.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly tableware molding technology, specifically to a tableware molding system that solves the problem of missing material at the edges and corners of sugarcane pulp tableware while ensuring uniform thickness. Background Technology

[0002] In the production of eco-friendly tableware made from sugarcane pulp, hot pressing has become the mainstream technology due to its ability to quickly shape the tableware. Currently, the industry commonly uses the traditional process of "hot pressing after dipping in sauce" or "direct injection of slurry into the mold - one-time hot pressing." This involves directly injecting a sugarcane pulp fiber suspension into the cavity of a hot pressing mold using a metering device, followed by mold closing and the application of pressure and temperature to simultaneously complete solid-liquid separation and shaping. However, in actual production, this process consistently faces two core technical challenges for complex-shaped tableware such as bowls with deep cavities and plates with multiple compartments: insufficient material at the edges and uneven thickness. These challenges severely restrict product qualification rates and production efficiency.

[0003] Regarding the issue of insufficient material at the edges and corners, in traditional processes, after the slurry is injected into the mold, its flow within the mold exhibits significant unevenness due to the combined effects of the physical properties of sugarcane fibers (fiber length is mostly 0.8-2.5mm, easily forming fiber bundles) and the mold cavity structure. In areas such as the corners of the mold, the bottom of deep cavities, and the base of the dividers on multi-compartment plates, the resistance to slurry flow increases significantly, making it difficult for fiber bundles to fully fill these narrow spaces under pressure. Simultaneously, during the initial hot pressing phase, air venting within the mold is concentrated in the venting channels at the cavity edges, while localized air pressure stagnation easily forms in the corner areas, further hindering slurry flow. Ultimately, this results in insufficient fiber coverage at the corners of the finished tableware, with the missing area often reaching 2-5mm. 2 In some deep-cavity bowls, the rate of missing material at the bottom can be as high as 30%. Such missing material not only affects the appearance integrity of the tableware, but also leads to a significant decrease in the structural strength of the missing area. In subsequent use (such as when holding hot food or stacking), cracking and breakage are very likely to occur, significantly reducing the product's lifespan.

[0004] In terms of thickness uniformity control, the shortcomings of traditional processes are more pronounced. On the one hand, when the slurry is injected into the mold, due to gravity, the slurry accumulation thickness at the bottom of the cavity is usually greater than that at the top, especially for tableware products with a height exceeding 30mm, where the upper and lower wall thickness deviation can reach 0.5-1mm. On the other hand, there are inherent differences in temperature and pressure distribution in the mold during hot pressing. The edge of the mold dissipates heat faster, and the temperature is usually 5-10℃ lower than that of the center area, resulting in a slower rate of moisture evaporation in the slurry at the edge than in the center, and different degrees of fiber shrinkage, further aggravating the thickness deviation. In addition, the venting structure of traditional hot pressing molds is mostly a side venting groove of fixed width. During the venting process, fiber loss is easily accompanied, causing the tableware wall thickness near the venting groove to become thinner, forming an uneven shape of "thin at the edge and thick in the center". Unevenly thick tableware not only fails to meet the industry standard requirement of "wall thickness deviation of ≤0.2mm for the same product", but also causes problems such as uneven heating (e.g., thin-walled areas are prone to overheating and deformation when microwaved) and unbalanced load-bearing capacity (e.g., plates are prone to breakage under localized stress). It also increases raw material waste. To avoid insufficient strength in thin-walled areas, companies are often forced to increase the overall slurry injection volume, resulting in a 10%-15% increase in raw material costs.

[0005] Further analysis reveals that the core reason for the defects in traditional processes lies in the contradiction between the synchronicity of "slurry filling" and "solid-liquid separation": traditional processes attempt to simultaneously achieve uniform slurry filling, air removal, and moisture evaporation through a single hot-pressing process. However, the process requirements of these three aspects are fundamentally conflicting—increasing pressure is required to promote slurry filling, but excessive pressure will compress the air volume inside the mold, making it difficult for air to escape; increasing temperature is required to accelerate moisture evaporation, but excessive temperature will cause the slurry surface to solidify rapidly, hindering the flow of internal slurry to the edges and corners. This contradiction makes it impossible for traditional processes to precisely control the slurry filling and solid-liquid separation processes, relying only on repeated adjustments of empirical parameters (such as slurry concentration and hot-pressing temperature), which fails to fundamentally solve the problems of insufficient material at the edges and corners and uneven thickness. In addition, traditional processes are not adaptable to tableware of different shapes. For complex structures such as multi-compartment plates, special slurry guiding structures and venting paths need to be designed for each type of product. This not only increases the cost of mold development (the cost of a single complex mold is more than 40% higher than that of a regular mold), but also results in a mold changeover cycle of 2-3 hours, which seriously affects the flexible production capacity of the production line and makes it difficult to meet the market's demand for diversified tableware categories.

[0006] The aforementioned defects in existing technology have directly resulted in the yield of sugarcane pulp tableware in the industry remaining at a low level of 75%-80% for a long time. A large number of waste products generated due to material shortages and uneven thickness need to be crushed and recycled, which not only increases energy consumption and labor costs, but also leads to a decline in the performance of raw materials due to fiber degradation during the recycling process. At the same time, measures such as excessive injection of raw materials and repeated mold adjustments taken to compensate for the defects have further increased production costs and restricted the process of sugarcane pulp environmentally friendly tableware replacing traditional plastic tableware.

[0007] For the reasons mentioned above, it is necessary to propose a tableware forming system that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware while ensuring uniform thickness. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects in the prior art and provide a tableware forming system that solves the problem of missing material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: A tableware forming system that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware while ensuring uniform thickness includes: A slurry tank containing a plant fiber suspension slurry of a predetermined concentration; The negative pressure pre-coating process includes a pre-coating mold that matches the shape of the target product. A relative negative pressure is formed inside the pre-coating mold, so that at least some parts of the pre-coating mold are in a negative pressure state, and plant fiber suspension slurry is wrapped on its molding surface. Furthermore, the molding surface is provided with fine suction holes (water in the plant fiber suspension slurry is separated through the suction holes). The pre-coating mold and the internal negative pressure state cooperate to perform solid-liquid separation of the plant fiber suspension slurry during the wrapping and molding process, so that the plant fiber reduces the moisture content and adheres to the molding surface to form a pre-coated blank of a certain thickness. The extrusion die includes an upper die and a lower die. The pre-coated die moves above the lower die and places the pre-coated blank into the lower die. The upper die and the lower die close together to perform hot pressing on the pre-coated blank.

[0010] Furthermore, the pre-coating mold has a barrel-shaped structure and is configured to rotate around its axis, with a central shaft at the axis. The pre-coating mold includes an inner frame and an outer cover. The inner frame is rotatably mounted at the end of the central shaft, and the outer cover is fitted onto the outer surface of the inner frame and rotates with the inner frame. The outer cover is drivable relative to the inner frame along the central axis. The outer side of the inner frame fitted onto the outer cover is the coating surface, and the side of the inner frame away from the outer cover is a circular plane (this circular plane is not limited to an absolute plane, but rather defined to form a plane at least near the central axis). The inner frame includes multiple radially arranged... A radial partition plate divides the interior of the pre-coating mold into multiple independent sector-shaped chambers. The outer surface of each sector-shaped chamber is covered by an outer cover, and the suction holes are formed on the outer cover. Each sector-shaped chamber is equipped with a water suction pipe, one end of which is positioned close to the outer cover, and the other end passes through a circular plane near the central axis to form a negative pressure suction hole. The negative pressure suction holes on each sector-shaped chamber are arranged equidistantly around the central axis. A negative pressure pipeline is provided on the central axis, and the end of the negative pressure pipeline has a sealing suction port that is sealed and connected to one or more negative pressure suction holes. When the pre-coating mold rotates, the negative pressure pipeline sequentially connects to each sector-shaped chamber, creating a negative pressure environment inside them.

[0011] Furthermore, the slurry tank is equipped with a scraper, the scraper is matched with the radial cross-sectional shape of the outer cover, and a controllable and adjustable scraping gap is maintained between the scraper and the outer cover; a local negative pressure portion is formed on the coating surface of the pre-coated mold, immersing the plant fiber suspension slurry; the pre-coated mold is rotated in a controlled manner in the slurry tank to form a rotary coating, and when the plant fiber coating fills the scraping gap, it forms tangential contact with the scraper, and the scraper flattens and compacts the plant fiber.

[0012] Furthermore, the pre-coated mold has a multi-compartment plate structure. The pre-coated mold includes an inner frame and an outer cover. The inner frame is fixed at the end of the central shaft, and the outer cover covers the outside of the inner frame. The outer cover can move relative to the inner frame along the central shaft. A negative pressure pipeline is provided on the central shaft, and the negative pressure pipeline is connected to the inside of the pre-coated mold. The slurry tank is equipped with slurry nozzles. The pre-coating mold is moved into the slurry tank to form an inverted shape with the outer cover on the upper side and the inner frame on the lower side. The slurry nozzles are positioned above the pre-coating mold and perform circumferential spraying.

[0013] Furthermore, the outer cover is also provided with a de-embryo structure, which includes a plurality of air jet holes distributed on the surface of the outer cover. An air supply pipe is provided inside the outer cover, with one end of the air supply pipe connected to the air jet holes and the other end connected to an air supply device.

[0014] Furthermore, the extrusion die includes a hot press frame, on which a transverse guide rail is provided, and a sliding plate is slidably mounted on the transverse guide rail. Two lower dies are mounted on the sliding plate. The hot press frame has three stations, including a hot pressing station in the middle and a first loading station and a second loading station on both sides. The sliding plate moves back and forth between the three stations, aligning one lower die with the hot pressing station and the other lower die with the loading station. The two loading stations are respectively equipped with blank conveying devices, and a negative pressure pre-coating process is set on each blank conveying device.

[0015] Furthermore, a cam track is provided on one side of the slurry pool, and the cam track and the moving central shaft form a cam engagement; the cam track includes a vertical track, a lifting track, and a coating track; the central shaft passes through each track section, allowing the pre-coated mold to pass over the edge of the slurry pool for entry and exit, and to adjust its position during the coating process.

[0016] Furthermore, a torsion spring is provided at the hinge position between the central shaft and the slide portion, and the torsion spring is configured to keep the central shaft tending to be pressed against the coating track at all times.

[0017] Furthermore, the plant fiber suspension slurry includes sugarcane bagasse fiber, dispersant, reinforcing agent, water-retaining agent, and deionized water as solvent; The sugarcane bagasse fiber mass fraction is 8%-12%; the dispersant is 0.1%-0.3% food-grade polyethylene glycol; the reinforcing agent is 0.5%-1% oxidized starch; and the water-retaining agent is 0.2%-0.4% sodium carboxymethyl cellulose.

[0018] The advantages and beneficial effects of this invention are as follows: This invention addresses the problems of insufficient material at the edges and uneven thickness that are difficult to solve in the molding of sugarcane pulp tableware by traditional processes. Through a multi-level structural design and process synergy of "negative pressure pre-coating + precise hot pressing + flexible adaptation", it demonstrates significant technical advantages and practical value.

[0019] Through an innovative design using negative pressure pre-coating, the defects caused by uneven slurry flow and fiber agglomeration in traditional "one-time hot pressing" are avoided from the source. The pre-coating mold is customized according to the shape of the target product. With the help of internal local negative pressure and fine suction holes on the molding surface, precise solid-liquid separation can be achieved during the slurry coating process. This allows plant fibers to be evenly coated on the molding surface, forming a pre-coated blank with controllable thickness in advance. This completely solves the problem of insufficient fiber filling in the corner areas in traditional processes. At the same time, for different structural products such as bucket-shaped bowls and multi-compartment plates, two pre-coating modes are designed: rotation coating (with a scraper to achieve thickness calibration) and surrounding spraying (inverted mold to ensure uniform slurry coverage). Combined with the controllable adjustment of the scraper gap and the directional delivery of the slurry nozzle, the thickness deviation of the pre-coated blank is further guaranteed to be controlled within a very small range. This lays the foundation for the thickness uniformity of subsequent hot pressing and effectively avoids the uneven wall thickness caused by gravity and temperature gradients in traditional processes. This significantly improves the structural integrity and strength stability of the tableware and reduces the risk of cracking and breakage during use.

[0020] In terms of cost control and environmental protection, this invention reduces raw material waste through precise molding of pre-coated blanks, and negative pressure pre-coating can precisely control the amount of fiber used, avoiding the problem of excessive slurry injection to compensate for missing material at the edges in traditional processes, thus reducing raw material loss; multi-station collaboration and automated design reduce labor costs and reduce scrap rate (the scrap rate caused by missing material at the edges and uneven thickness is significantly reduced); in addition, solid-liquid separation in the pre-coating stage can recover some water, and if a water recycling system is added later, the water resource utilization rate can be further improved, which is in line with the environmentally friendly production concept of sugarcane pulp tableware, taking into account both economic and environmental benefits. Attached Figure Description

[0021] Figure 1 This is an axonometric view of a tableware forming system for solving the problem of missing material at the edges and corners of sugarcane pulp tableware and achieving uniform thickness, according to the present invention. Figure 2 This is a schematic diagram of the structure of the hanging unit in this invention; Figure 3 This is one of the exploded views of the inner frame and outer cover in this invention; Figure 4 This is the second exploded view of the inner frame and outer cover in this invention; Figure 5 This is a front view of a tableware forming system according to the present invention that solves the problem of missing material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness; Figure 6 This is a schematic diagram of the sliding plate reciprocating on the hot press frame to switch workstations in this invention; Figure 7 This is a top view of the cam track in this invention; In the diagram: 1. Slurry tank; 2. Pre-coating mold; 3. Suction port; 4. Extrusion mold; 5. Upper mold; 6. Lower mold; 7. Central shaft; 8. Inner frame; 9. Outer cover; 10. Hinge end; 11. Rotating end; 12. Coating surface; 13. Circular plane; 14. Radial partition plate; 15. Fan-shaped chamber; 16. Pumping pipe; 17. Negative pressure suction port; 18. Sealed suction port; 19. Negative pressure pipeline; 20. Circular waist 21. Hole; 22. Scraper blade; 23. Scraper gap; 24. Electric push rod; 25. Air jet hole; 26. Hot press frame; 27. Transverse guide rail; 28. Sliding plate; 29. ​​First loading station; 30. Second loading station; 31. Hot press station; 32. Circulating conveyor line; 33. Hanger unit; 34. Slide seat; 35. Cam rail; 36. Vertical section rail; 37. Lifting rail; 38. Coating rail. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0023] A tableware forming system that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware while ensuring uniform thickness, such as... Figure 1-7 As shown, it includes: Slurry tank 1 contains a plant fiber suspension slurry of a predetermined concentration. In this embodiment, the plant fiber suspension slurry is sugarcane pulp. Specifically, the sugarcane pulp plant fiber suspension slurry in slurry tank 1 is the core raw material basis that determines the quality (uniformity, strength) of the pre-coated blank and the performance of the final tableware. It is not a simple mixture of "sugarcane bagasse + water", but a functional suspension system with precise control of "fiber characteristics, concentration, and auxiliary agent ratio". The slurry uses sugarcane bagasse fiber as its core framework, combined with functional additives and deionized water, to form a stable, easily adsorbed, and solid-liquid separable suspension system. The core framework is sugarcane bagasse fiber, which is pretreated refined sugarcane bagasse fiber (0.8-2.5 mm in length and 10-20 μm in width). The functional additives are used for suspension stability and strength adjustment, including: dispersant: 0.1%-0.3% food-grade polyethylene glycol (PEG-600); reinforcing agent: 0.5%-1% oxidized starch (degree of substitution 0.08-0.12); water-retaining agent: 0.2%-0.4% sodium carboxymethyl cellulose (CMC, viscosity 500-1000 mPa·s); and the solvent is deionized water.

[0024] The slurry concentration is 8%-12% (mass fraction, the proportion of dry weight of bagasse fiber in the slurry to the total mass of the slurry). If the concentration is too low (<8%), the fiber distribution in the slurry will be too sparse, requiring a longer time to form the target thickness (≥1.5mm) of the pre-coating material during negative pressure adsorption, leading to decreased pre-coating efficiency; furthermore, the low fiber density and insufficient wet strength of the pre-coated material make it prone to breakage. If the concentration is too high (>12%), the slurry viscosity will increase sharply (>3000mPa・s), resulting in poor fiber flowability and difficulty in uniformly filling the corners and deep cavities of the pre-coating mold 2 under negative pressure, potentially leading to "material shortage at the corners" (similar to the pain points of traditional processes); simultaneously, high-concentration slurry easily forms a "fiber filter cake" on the surface of the suction holes 3, clogging the pores and causing subsequent adsorption failure. A concentration of 8%-12% balances "flowability" and "adsorption efficiency," ensuring that the fiber can quickly fill the mold cavity during negative pressure adsorption without causing insufficient pre-coating strength due to excessive sparseness.

[0025] To ensure consistent performance of the plant fiber suspension slurry, its preparation includes the following steps: Fiber pretreatment: Sugarcane bagasse coarse material is screened (to remove impurities >3mm), loosened (by a double-disc mill to break up fiber bundles), and washed (to remove sugar and ash) to obtain refined fiber; Additive dissolution: Dissolve PEG-600, oxidized starch, and CMC separately in deionized water (heat at 50-60℃ to aid dissolution) to prepare additive mother liquor; Slurry preparation: Add a measured amount of deionized water to slurry tank 1, start stirring (300r / min), first add refined fiber, stir for 10 minutes until initially dispersed; then slowly add auxiliary agent mother liquor, continue stirring for 20-30 minutes to ensure that all components are evenly mixed; Parameter testing: Sample and measure the slurry concentration (drying method), viscosity (rotational viscometer), and pH value (pH meter). If the standard is not met, adjust by adding fiber / water or additives. Constant temperature storage: Store the qualified slurry in a constant temperature environment of 25-30℃, and reduce the stirring speed to 100r / min to prevent fiber sedimentation and ensure uniform concentration during subsequent use.

[0026] The negative pressure pre-coating process includes a pre-coating mold 2 that matches the shape of the target product. A relative negative pressure is formed inside the pre-coating mold 2, so that at least a local part of the pre-coating mold 2 is in a negative pressure state. Specifically, as described in Examples 1 and 2 below, in Example 1, a cylindrical tableware is pre-formed by rotary coating in the form of rotary rolling coating. During the process, the mold immersed in the slurry pool 1 generates negative pressure at least a local part of the inside for coating. In Example 2, a multi-compartment plate structure is pre-coated. In this example, it is rotated in an inverted manner and combined with vacuum spraying. Then, a plant fiber suspension slurry is coated on its molding surface; and the molding surface is provided with fine suction holes 3, through which water in the plant fiber suspension slurry is separated; the pre-coated mold 2 achieves two key functions through internal negative pressure (usually -0.04 to -0.07 MPa) and fine suction holes 3 (pore diameter 0.1-0.3 mm, pore spacing 1-2 mm) on the molding surface: ① Uniform fiber adsorption: When the pre-coated mold 2 contacts the slurry pool 1 or receives a quantitative amount of slurry, the negative pressure generates uniform suction through the suction holes 3, which makes the plant fiber (bagasse fiber) overcome the tendency to agglomerate and uniformly adhere to the molding surface (including corners, deep cavities and other areas prone to material shortage), avoiding the concentration of fibers in the planar area due to gravity or flow resistance. ② Preliminary solid-liquid separation: Water in the slurry is extracted through the suction holes 3, which greatly reduces the moisture content of the pre-coated blank when it is molded on the molding surface. At this time, the blank has a preliminary shape, and the uniformity of fiber distribution is improved by more than 60% compared with traditional direct injection. The pre-coated mold 2, in conjunction with the internal negative pressure state, performs solid-liquid separation on the plant fiber suspension slurry during the encapsulation and molding process, so that the plant fiber reduces the moisture content and adheres to the molding surface to form a pre-coated blank of a certain thickness. Compared with the traditional direct injection hot pressing molding (fibers are prone to agglomeration and the material shortage rate at the edges and corners), the core advantage of this solution is that it achieves "active material control" through structural design.

[0027] To address the issue of material shortage at corners, the pre-coated mold 2's molding surface perfectly matches the shape of the target product (including details such as deep cavities and interlocking points). During negative pressure suction, fibers can be "directionally adsorbed" to corner areas (where fibers are difficult to reach due to flow resistance during traditional grouting), thus preventing material shortages from the source. In addition, the "densely distributed design" of the suction holes 3 (allowing for appropriate increases in hole density in corner areas) ensures that negative pressure is applied evenly across the entire molding surface, preventing uneven fiber accumulation caused by insufficient local suction.

[0028] This pre-coating process can achieve 60%-70% moisture separation in advance, reduce the amount of moisture evaporation during the hot pressing stage, shorten the hot pressing time by 30%, and avoid tableware deformation caused by rapid moisture evaporation.

[0029] The pre-coated blank has a certain strength (low moisture content) and is not easily damaged or deformed when transferred to the lower mold 6, solving the "material dropping" problem in the traditional wet slurry transfer process (the material dropping rate is reduced from 15% to ≤2%).

[0030] The extrusion die 4 includes an upper die 5 and a lower die 6. The pre-coating die 2 moves above the lower die 6, as shown. Figure 1 , 4 As shown in Figure 5, the pre-coated blank is placed into the lower mold 6, and the upper mold 5 and lower mold 6 are closed to perform hot pressing molding of the pre-coated blank. After the pre-coated blank falls into the lower mold 6, the upper mold 5 and lower mold 6 are closed. During mold closing, a pressure of 10-15MPa is applied to the pre-coated blank to make the blank completely fit the mold cavity and eliminate missing material at the edges (because the fiber filling has been ensured in the pre-coating stage). The mold is heated to 150-180℃ for hot pressing densification. Under the action of pressure, the moisture content of the blank is further reduced (to 8%-12%), while the fibers are tightly bonded together through hydrogen bonds, finally forming a tableware product with uniform thickness (error ≤0.1mm).

[0031] In this embodiment, the composition and parameter design of the slurry are not isolated, but deeply integrated with the two core processes of "negative pressure pre-coating" and "hot pressing," providing support from the raw material end to address process pain points. Adaptation to negative pressure pre-coating: ensuring "uniform adsorption + no pore clogging." Matching fiber length (0.8-2.5mm) with suction hole 3 (0.1-0.3mm): short fibers can pass through the gaps in the channels without causing blockage due to excessive length; simultaneously, the addition of dispersant (PEG-600) prevents fiber agglomeration, ensuring uniform fiber distribution on the mold forming surface (including corners and deep cavities) during negative pressure suction, avoiding "material shortage at corners" from the source; the rate-controlling effect of water-retaining agent (CMC): slowing down the dehydration rate, allowing the slurry to form "gradual solid-liquid separation" on the mold surface, with fibers gradually accumulating as water is extracted, resulting in thickness uniformity (deviation ≤0.2mm) far superior to traditional direct injection (deviation ±0.5mm). Suitable for hot pressing: ensuring "easy shaping + strength compliance"; Moisture content of pre-coated blank (40%-50%): controlled by slurry water-retaining agent and negative pressure suction, avoiding both excessive moisture content causing rapid evaporation and bubble formation during hot pressing, and excessive moisture content causing the blank to be too hard and difficult to fit the mold cavity; Subsequent effect of reinforcing agent (oxidized starch): during hot pressing (150-180℃), oxidized starch will further gelatinize, forming a stronger bond with sugarcane bagasse fiber, ultimately increasing the flexural strength of the tableware to ≥6.5MPa, while avoiding "localized weakness" caused by uneven fiber distribution.

[0032] Example 1: In this embodiment, the pre-coated mold 2 has a barrel-shaped structure, such as... Figure 1-5 As shown, its shape is the same as the structure of the pre-coated blank being processed. In this embodiment, the pre-coated blank is similar to an inverted frustum structure, which is a bowl-shaped structure with a small bottom and a large top. The pre-coating mold 2 is configured to rotate about its axis, with a central shaft 7 at the axis. The pre-coating mold 2 includes an inner frame 8 and an outer cover 9. The inner frame 8 is rotatably disposed at the end of the central shaft 7. The outer cover 9 is fitted onto the outer surface of the inner frame 8 and rotates with the inner frame 8. The outer cover 9 is drivable and can move relative to the inner frame 8 along the central shaft 7. Figure 1 As shown, in actual use, a pre-coated mold 2 is integrally provided at the lower end of the central shaft 7. The pre-coated mold 2 moves with the position of the central shaft 7 and is driven by the central shaft 7 to rotate around the axis. In this embodiment, the upper end of the central shaft 7 is a hinge end 10, and the lower end is a rotating end 11. The rotating end 11 is used to drive the pre-coated mold 2 to rotate around the axis. A drive part for rotating the pre-coated mold 2 is provided inside the rotating end 11, so that the pre-coated mold 2 rotates at a corresponding angle according to a preset program. In actual use, the pre-coated mold 2 is driven by the central shaft 7, and the lower part of the pre-coated mold 2 is immersed in the slurry. A negative pressure is formed at a corresponding position inside the pre-coated mold 2, thereby causing the sugarcane fiber in the slurry to be adsorbed onto the surface of the pre-coated mold 2. Furthermore, due to the gradual adsorption and thickening of the pre-coated material during rotation, the pre-coated material can be made more compact.

[0033] Specifically, in this embodiment, the outer side of the inner frame 8 of the pre-coated mold 2, which is fitted with the outer cover 9, is the coating surface 12. During the immersion-rolling-vacuum coating process, the sugarcane fiber is adsorbed onto the surface of the coating surface 12. As the pre-coated mold 2 rotates and leaves the slurry, it maintains the internal negative pressure suction effect, thereby reducing the moisture content of the slurry covering the coating surface 12. Furthermore, as the pre-coated mold 2 rolls and pre-coats in the slurry pool 1 multiple times, the pre-coated blank can reach the required thickness. The inner frame 8 is set as a circular plane 13 on the side away from the outer cover 9 (this circular plane 13 is not limited to an absolute plane, but is defined to form a plane at least close to the central axis 7). In actual use, negative pressure is established inside the pre-coated mold 2 through this circular plane 13. Specifically, such as Figure 3 , 4As shown, the inner frame 8 includes multiple radially arranged radial partition plates 14, which divide the interior of the pre-coated mold 2 into multiple independent fan-shaped chambers 15. The outer surface of the fan-shaped chambers 15 is covered by an outer cover 9, and the suction holes 3 are formed on the outer cover 9. It can be understood that no suction holes 3 are provided on the circular plane 13, so the circular plane 13 side of the pre-coated mold 2 will not absorb sugarcane pulp even if it is immersed in the pulp tank. On the coating surface 12 side of the outer cover 9, suction holes 3 are provided on its bottom surface and the curved sidewalls around it. With several suction holes 3, the negative pressure inside the pre-coating mold 2 acts on the suction holes 3 of the outer cover 9, thereby achieving tight wrapping of sugarcane fiber on the coating surface 12 while separating the moisture. Since the interior of the pre-coating mold 2 is divided by radial partition plates 14, the various fan-shaped chambers 15 inside are different from each other, and only the suction holes 3 on the outer side and bottom surface are connected to the outside, when the pre-coating mold 2 is immersed in the slurry pool 1 and rotated, the surface of its outer cover 9 can be negatively pressure adsorbed and evenly wrapped with sugarcane fiber.

[0034] The fan-shaped chamber 15 is equipped with a water suction pipe 16. One end of the water suction pipe 16 is set close to the outer cover 9, and the other end passes through the circular plane 13 near the central axis 7 to form a negative pressure suction hole 17. The negative pressure suction holes 17 on each fan-shaped chamber 15 are arranged equidistantly around the central axis 7. The central axis 7 is equipped with a negative pressure pipeline 19. The end of the negative pressure pipeline 19 is equipped with a sealing suction port 18 that is sealed and connected to one or more negative pressure suction holes 17. When the pre-coating mold 2 rotates, the negative pressure pipeline 19 connects to each fan-shaped chamber 15 in sequence to create a negative pressure environment inside them. Specifically, a sealing suction port 18 is fitted to the rotating end 11 on the side facing the circular plane 13. The negative pressure pipeline 19 can be arranged along the interior of the central axis 7, thereby leading the negative pressure to the sealing suction port 18. In this embodiment, the sealing suction port 18 is on the plane where the rotating end 11 and the circular plane 13 are fitted, and the sealing suction port 18 is set as a circular arc waist hole 20 type structure, so that the sealing suction port 18 can provide negative pressure suction to multiple adjacent fan-shaped chambers 15; correspondingly, on the circular plane 13 and the A ring of negative pressure suction holes 17 is positioned at a location matching the radius of the arc-shaped waist hole 20. Each negative pressure suction hole 17 corresponds to a sector-shaped chamber 15. When the pre-coating mold 2 rotates, the ring of negative pressure suction holes 17 sequentially enters the sealed suction port 18 of the arc-shaped waist hole 20, thus creating a negative pressure environment in the corresponding sector-shaped chamber 15. It can be understood that the sector-shaped chamber 15 forming the negative pressure environment is immersed in the slurry pool for negative pressure suction coating of the slurry. After the suction process is completed in the slurry, the sector-shaped chamber rotates... 15. After the liquid surface is removed, the sealing suction port 18 is a circular arc-shaped waisted hole 20, which covers a certain area. This ensures that the fan-shaped chamber 15, after being removed from the liquid surface, remains connected to the negative pressure pipeline 19 through the circular arc-shaped waisted hole 20. At this time, it can be used to further extract water from the slurry already coated on the outer cover 9. It is understood that during suction, a negative pressure is created inside the fan-shaped chamber 15, and water is drawn into the interior. To facilitate the discharge of the extracted water, a water extraction pipe 1 connected to the negative pressure extraction hole 17 is provided. 6. The end of the water suction pipe 16 should preferably extend to the lowest point to facilitate the suction and removal of water. In this embodiment, an exemplary water suction pipe 16 is provided, and the end of the water suction pipe 16 is extended to the lowest point close to the outer cover 9. This is beneficial for removing water at the lowest point, thereby allowing the water in the coated blank to be discharged as much as possible. A portion of the discharged water can be returned to the slurry tank 1 to maintain the slurry in the slurry tank 1 at a suitable concentration. Excess water can be separated for subsequent slurry preparation.Furthermore, as the pre-coated mold 2 continues to rotate, when the negative pressure extraction hole 17 rotates out of the arc-shaped waist hole 20, the corresponding sector-shaped chamber 15 loses its internal negative pressure effect. It can be understood that at this time, the sector-shaped chamber 15 has already passed through the surface of the slurry. Therefore, the setting of the arc-shaped waist hole 20 can create negative pressure in the sector-shaped chamber 15 immersed in the liquid surface. During the rotation, the sector-shaped chambers 15 that leave the liquid surface lose the negative pressure effect in turn, so that the negative pressure system can maintain better sealing and establish a relatively high vacuum effect.

[0035] Furthermore, the slurry tank 1 is equipped with a scraper 21, which matches the radial cross-sectional shape of the outer cover 9, and a controllable scraping gap 22 is maintained between the scraper 21 and the outer cover 9; a local negative pressure portion is formed on the coating surface 12 of the pre-coating mold 2, immersing the plant fiber suspension slurry; the pre-coating mold 2 rotates in a controlled manner within the slurry tank 1 to form a rotary coating, and when the plant fiber coating fills the scraping gap 22, it forms tangential contact with the scraper 21, and the scraper 21 flattens and compacts the plant fiber. Figure 5 As shown, in this embodiment, the method described above uses an internal negative pressure to actively adsorb the slurry and coat it onto the outer cover 9. However, to further improve the tightness of the coating and the smoothness of the surface, a scraper 21 is further provided in this embodiment. It is configured to be adjustable within the slurry pool 1. It can be understood that when the central shaft 7 drives the pre-coating mold 2 to pre-coat in the slurry pool, its tilt angle is fixed. Therefore, the scraper 21 is set at a fixed angle interval 22. So, during the pre-coating process, as the pre-coating mold 2 rotates and adsorbs, the slurry coating on its surface becomes thicker and thicker, thus coming into contact with the scraper 21. Since it adopts a tangential contact form, it will not affect the rotation of the pre-coating mold 2. Furthermore, as the pre-coating mold 2 rotates and adsorbs, the scraper 21 scrapes the surface of the slurry, thereby making the surface of the preform smooth and forming a certain squeezing effect on the interior of the preform, promoting its density increase while also having a certain drainage effect, squeezing out some of the water in the preform.

[0036] Furthermore, in this embodiment, the outer cover 9 is configured to be drivable and move relative to the inner frame 8 along the central axis 7. Specifically, an electric push rod 23 is provided inside the inner frame 8. The free end of the electric push rod 23 extends axially and is connected to the outer cover 9. By controlling the extension and retraction of the electric push rod 23, the outer cover 9 is pushed away from the inner frame 8 or pulled to wrap around the inner frame 8. Its purpose is that after the slurry pre-coating is completed, the pre-coating mold 2 is moved to the extrusion mold 4, and the outer cover 9 is pushed downward by the electric push rod 23, so that the pre-coated blank is close to or even attached to the lower mold 6 for material release (separating the pre-coated blank from the outer cover 9 and letting the pre-coated blank fall into the lower mold 6), thereby reducing the impact caused by the blank falling and avoiding the risk of blank deformation.

[0037] Example 2: Furthermore, the pre-coated mold 2 has a multi-compartment plate structure. The pre-coated mold 2 includes an inner frame 8 and an outer cover 9. This embodiment is similar to the previous embodiment. The pre-coated mold 2 still adopts a split design of the inner frame 8 and the outer cover 9. The difference is that, due to the irregularity of the multiple plate structure, it is not suitable for the aforementioned regular structure rotation coating method. This embodiment makes an improvement. Specifically, the inner frame 8 is fixed at the end of the central shaft 7, and the outer cover 9 covers the outside of the inner frame 8. The outer cover 9 can move relative to the inner frame 8 along the direction of the central shaft 7. A negative pressure pipeline 19 is provided on the central shaft 7, and the negative pressure pipeline 19 is connected to the inside of the pre-coated mold 2. In actual use, the inside of the pre-coated mold 2 can be set as a completely sealed cavity. A negative pressure is created inside it through the negative pressure pipeline 19, and the outer cover 9 can be pushed out along the axial direction, thereby pushing the pre-coated blank away for easy unloading.

[0038] The slurry tank 1 is equipped with slurry nozzles. The pre-coated mold 2 moves into the slurry tank 1, forming an inverted shape with the outer cover 9 on the upper side and the inner frame 8 on the lower side. The slurry nozzles are positioned above the pre-coated mold 2 and perform circumferential spraying. In this embodiment, when the central shaft 7 drives the pre-coated mold 2 into the slurry tank, it is then motorized and flipped into an inverted shape, allowing the slurry nozzles around it to spray onto the outer cover 9 simultaneously. At the same time, the negative pressure created inside removes moisture. Due to its inverted structure, moisture can be easily discharged, resulting in a pre-coated blank with less moisture. In this embodiment, spraying onto the outer cover 9 from multiple angles facilitates the production of multi-compartment plates with various irregular shapes, thereby increasing the applicability of this system.

[0039] Example 3: Furthermore, the outer cover 9 is also provided with a de-molding structure, which includes a plurality of air jet holes 25 distributed on the surface of the outer cover 9, such as... Figure 2 , 5As shown, the outer cover 9 is equipped with an air supply pipe inside. One end of the air supply pipe is connected to the air jet hole 25, and the other end is connected to the air supply device. It can be understood that in the aforementioned embodiments one and two, the outer cover 9 is designed to be axially separable, so that when it reaches the unloading position, the pre-coated blank is closer to the lower mold 6. However, its reliance on gravity may hinder unloading. In this embodiment, the structure of the outer cover 9 is improved. In addition to the suction hole 3 on its surface, an air jet hole 25 is also provided. When unloading is required, the air supply pipe sprays air from the air jet hole 25 at a certain frequency to form a pulse airflow. During unloading, the pulse airflow assists in separating the pre-coated blank from the outer cover 9, making it easier for the blank to enter the lower mold 6. Furthermore, by adjusting the frequency and strength of the pulse airflow, the integrity of the pre-coated blank can be well protected, avoiding damage during separation.

[0040] Example 4: Furthermore, the extrusion mold 4 includes a hot press frame 26, on which a transverse guide rail 27 is provided. A sliding plate 28 is slidably provided on the transverse guide rail 27, and two lower molds 6 are provided on the sliding plate 28. The hot press frame 26 has three stations, including a hot pressing station 31 in the middle and a first loading station 29 and a second loading station 30 on both sides. The sliding plate 28 moves back and forth between the three stations, aligning one lower mold 6 with the hot pressing station 31 and the other lower mold 6 with the loading station. The two loading stations are respectively equipped with blank conveying devices, and a negative pressure pre-coating process is set on each blank conveying device. This embodiment takes the processing of sugarcane pulp tableware with a barrel-shaped structure as an example. Figure 1 As shown, a circulating conveyor line 32 is set at the loading station on both sides, and a slurry tank 1 is set on each circulating conveyor line 32. Multiple hanging units 33 are provided on the circulating conveyor line 32. Each hanging unit 33 includes a sliding part 34 that moves along the circulating conveyor line 32. A central shaft 7 is hinged to the lower part of the sliding part 34. A pre-coated mold 2 is set at the lower end of each central shaft 7. Each pre-coated mold 2 is circulated and hoisted along the circulating conveyor line 32 with the sliding part 34. It can be understood that when the pre-coated mold 2 moves to the loading station, it stops to align with the lower mold 6. Then, the electric push rod 23 extends and pushes out the outer cover 9, causing it to fall close to the lower mold 6. Then, the mold removal structure blows the mold out, causing it to fall closer to the lower mold 6 to complete the mold removal. Then, the outer cover 9 is retracted, and each hanging unit 33 circulates to the slurry tank for a second pre-coating process to form a new pre-coated mold. In this embodiment, a cam track 35 is provided on one side of the slurry tank. Figure 1 , 7As shown, the cam track 35 and the moving central shaft 7 form a cam engagement, so that the central shaft 7 is guided by the cam track 35 during movement. In this embodiment, the cam profile of the cam track 35 includes a vertical section track 36, a lifting track 37, and a coating track 38. Specifically, the cam track 35 is symmetrically connected with the lifting track 37 and the vertical section track 36 on both sides of the coating track 38 as the center. The overall process is as follows: the central shaft 7 is driven by the circulating conveyor line 32 to first contact the vertical section track 36 at one end, and then connect to the lifting track 37. In the lifting track 37 stage, the originally vertical central shaft 7 is set with a pre-coating mold 2. One end of the mold rotates and lifts over one side wall of the slurry pool, then enters the coating track 38. During this stage, the central axis 7 is deflected at a certain angle relative to the original vertical direction, so that the pre-coated mold 2 is tilted and immersed in the slurry pool, and the operation process as described in Example 2 is performed. It is understood that the circulating conveyor line 32 is paused during the coating track 38 to provide sufficient time for pre-coating. In this stage, the pre-coated mold 2 being coated needs to be rotated and a negative pressure needs to be provided inside it; and the position of the scraper 21 should be appropriately controlled to maintain the scraper gap 22 so that the pre-coated material is fully coated. It is understood that... A torsion spring is installed at the hinge position between the central shaft 7 and the slide 34. This torsion spring is configured to keep the central shaft 7 pressed against the coating track 38 at all times. This prevents uneven coating caused by the shaking and displacement of the pre-coated mold 2 during the coating process. Furthermore, after coating is completed, the circulating conveyor line 32 is started, causing each hanger unit 33 to continue operating. The hanger unit 33 in the coating process also moves, causing the corresponding central shaft 7 to contact the second lifting track 37. This lifts the pre-coated mold 2 over the side wall of the slurry tank and then moves it into the loading station to unload the pre-coated preform. This completes a full coating-transportation-unloading cycle. Similarly, the other circulating conveyor line 32 also performs pre-coating. During production, the two circulating conveyor lines 32 are set to have staggered feeding rhythms. The sliding plate 28 moves on the transverse guide rail 27 to switch between the two circulating conveyor lines 32 for feeding. It can be understood that during the switching process, a lower mold 6 corresponding to the hot pressing station 31 is hot-pressed by the hot press. After the hot pressing is completed, the feeding station moves out, the hot-pressed tableware is taken out first, and then it is fed through the circulating conveyor line 32. This alternating operation achieves continuous production.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A tableware forming system that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware while ensuring uniform thickness, characterized in that, include: A slurry tank containing a plant fiber suspension slurry of a predetermined concentration; The negative pressure pre-coating process includes a pre-coating mold that matches the shape of the target product. A relative negative pressure is formed inside the pre-coating mold, so that at least some parts of the pre-coating mold are in a negative pressure state, and plant fiber suspension slurry is wrapped on its molding surface. Furthermore, the molding surface is provided with fine suction holes. The pre-coating mold and the internal negative pressure state cooperate to perform solid-liquid separation of the plant fiber suspension slurry during the molding process, so that the plant fiber reduces the moisture content and adheres to the molding surface to form a pre-coated blank of a certain thickness. The extrusion die includes an upper die and a lower die. The pre-coated die moves above the lower die and places the pre-coated blank into the lower die. The upper die and the lower die close together to perform hot pressing on the pre-coated blank.

2. The tableware forming system according to claim 1, which solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, is characterized in that, The pre-coating mold has a barrel-shaped structure and is configured to rotate around its axis, with a central shaft at the axis. The pre-coating mold includes an inner frame and an outer cover. The inner frame is rotatably mounted at the end of the central shaft. The outer cover, fitted onto the outer surface of the inner frame, rotates with the inner frame and is drivable relative to the inner frame along the central axis. The outer side of the inner frame fitted onto the outer cover is the coating surface, and the side of the inner frame away from the outer cover is a circular plane. The inner frame includes multiple radially arranged partition plates, which divide the interior of the pre-coating mold into... Multiple independent sector-shaped chambers are provided, with their outer surfaces covered by an outer casing. The suction holes are formed on the outer casing. Each sector-shaped chamber is equipped with a water suction pipe, one end of which is positioned close to the outer casing, and the other end passes through a circular plane near the central axis to form a negative pressure suction hole. The negative pressure suction holes on each sector-shaped chamber are arranged equidistantly around the central axis. A negative pressure pipeline is provided on the central axis, and the end of the negative pressure pipeline is equipped with a sealing suction port that is sealed and connected to one or more negative pressure suction holes. When the pre-coating mold rotates, the negative pressure pipeline sequentially connects to each sector-shaped chamber, creating a negative pressure environment inside them.

3. The tableware forming system according to claim 2, which solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, is characterized in that... The slurry tank is equipped with a scraper, which matches the radial cross-sectional shape of the outer cover, and the scraper and the outer cover maintain a controllable and adjustable scraping gap; a local negative pressure portion is formed on the coating surface of the pre-coating mold, which is immersed in the plant fiber suspension slurry; the pre-coating mold is rotated in a controlled manner in the slurry tank to form a rotary coating, and when the plant fiber coating fills the scraping gap, it forms a tangential contact with the scraper, and the scraper flattens and compacts the plant fiber.

4. The tableware forming system according to claim 1, which solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, is characterized in that, The pre-coated mold has a multi-compartment plate structure. The pre-coated mold includes an inner frame and an outer cover. The inner frame is fixed at the end of the central axis, and the outer cover is placed on the outside of the inner frame. The outer cover can move relative to the inner frame along the central axis. A negative pressure pipeline is provided on the central axis and the negative pressure pipeline is connected to the inside of the pre-coated mold. The slurry tank is equipped with slurry nozzles. The pre-coating mold is moved into the slurry tank to form an inverted shape with the outer cover on the upper side and the inner frame on the lower side. The slurry nozzles are positioned above the pre-coating mold and perform circumferential spraying.

5. A tableware forming system according to any one of claims 2-4, characterized in that, The outer cover is also provided with a de-embryo structure, which includes a number of air jet holes distributed on the surface of the outer cover. An air supply pipe is provided inside the outer cover, with one end of the air supply pipe connected to the air jet holes and the other end connected to an air supply device.

6. The tableware forming system according to claim 5, which solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, is characterized in that, The extrusion die includes a hot press frame with a transverse guide rail. A sliding plate is slidably mounted on the transverse guide rail, and two lower dies are mounted on the sliding plate. The hot press frame has three stations, including a hot pressing station in the middle and a first and a second feeding station on either side. The sliding plate moves back and forth between the three stations, aligning one lower die with the hot pressing station and the other lower die with the feeding station. The two feeding stations are respectively equipped with blank conveying devices, and a negative pressure pre-coating process is performed on each blank conveying device.

7. A tableware forming system according to claim 6 that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, characterized in that, A cam track is provided on one side of the slurry pool, and the cam track and the moving central shaft form a cam engagement; the cam track includes a vertical track, a lifting track, and a coating track; the central shaft passes through each track section, allowing the pre-coated mold to pass over the edge of the slurry pool for entry and exit, and to adjust its position during the coating process.

8. A tableware forming system according to claim 7 that solves the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieves uniform thickness, characterized in that, A torsion spring is provided at the hinge position between the central shaft and the slide block. The torsion spring is configured to keep the central shaft tending to be pressed against the coating track at all times.

9. A tableware forming system according to claim 1 for solving the problem of insufficient material at the edges and corners of sugarcane pulp tableware and achieving uniform thickness, characterized in that, The plant fiber suspension slurry includes sugarcane bagasse fiber, dispersant, reinforcing agent, water-retaining agent, and deionized water as solvent; The sugarcane bagasse fiber mass fraction is 8%-12%; the dispersant is 0.1%-0.3% food-grade polyethylene glycol; the reinforcing agent is 0.5%-1% oxidized starch; and the water-retaining agent is 0.2%-0.4% sodium carboxymethyl cellulose.

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