Preparation method of polyurethane pultrusion resin composite material

Abstract

The invention relates to the technical field of polyurethane pultrusion, in particular to a preparation method of a polyurethane pultrusion resin composite material, which comprises the following steps: drawing glass fiber into a glue dipping tank filled with polyurethane resin for dipping; heating the impregnated glass fiber in a pre-forming mold to obtain a pre-cured gel forming body; when it is judged that preparation of the pre-cured gel forming body does not meet the preset standard according to the scattering intensity standard deviation of the pre-cured gel forming body, preparation parameters are adjusted; the pre-cured gel forming body meeting the preset standard is put into a pultrusion mold for pultrusion, and a cured forming body is obtained; when it is judged that the preparation of the cured molded body does not meet a preset standard according to the average ripple amplitude, determining an adjustment strategy for the preparation of the cured molded body to do not meet the standard according to the curvature variance of the surface lines; and pulling and naturally cooling the cured molded body meeting the preset standard to obtain the polyurethane resin composite material. The preparation efficiency of the resin composite material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane pultrusion, and in particular to a method for preparing a polyurethane pultrusion resin composite material. Background Art

[0002] The pultrusion process is a method for continuously producing composite material profiles. It is an automated production process in which untwisted glass fiber roving and other continuous reinforcement materials, such as polyester surface felt, are impregnated with resin on a creel. Then, the pultruded products are passed through a forming mold that maintains a certain cross-sectional shape and cured in the mold before being continuously ejected from the mold.

[0003] Polyurethane is a polymer with a main chain containing urethane groups, synthesized from oligomeric polyols and isocyanates. Compared to traditional resins, polyurethane bonds better with reinforcing materials, resulting in superior impact resistance, mechanical properties, and weather resistance.

[0004] As an inorganic fiber with excellent performance, glass fiber is a brittle material with high elastic modulus, high tensile strength and low elongation at break. It has the advantage of designable mechanical properties and can flexibly design product structure according to needs to improve the overall performance of the product. It is widely used as a reinforcing material for resin-based composite materials.

[0005] High-performance polyurethane / glass fiber composite material is a high-strength, high-modulus, lightweight polymer composite material made of high-hardness polyurethane elastomer as the base material, reinforced with glass fiber, and refined through a continuous pultrusion process.

[0006] In the preparation process of high-performance polyurethane / glass fiber composite materials, temperature control during the curing stage directly affects the uniformity of the resin curing degree, avoiding surface defects or performance fluctuations caused by internal stress concentration.

[0007] Chinese patent application publication number: CN108943773A, discloses a method for preparing a pultruded polyurethane fiber-reinforced composite material, comprising the following steps: passing the heads of continuous fibers with a mass fraction of 50-85% through a mold, the mold having at least a glue injection and impregnation area, a preforming area, and a curing area; injecting a polyurethane resin synthesized in real time into the glue injection and impregnation area of ​​the mold at high pressure through a polyurethane resin injection system, so that the continuous fibers located in the glue injection and impregnation area are completely impregnated with the high-pressure polyurethane resin; the heads of the continuous fibers are moved under the traction of a traction device, so that the continuous fibers impregnated with the polyurethane resin are moved to the preforming area under the traction to be heated and gelled, thereby obtaining a preformed continuous fiber-reinforced composite material; with the continuous traction force generated by the traction device, the preformed continuous fiber-reinforced composite material is cured and formed in the curing area and then pulled out of the mold.

[0008] It can be seen that the above technical solution only mentions heating the gel of the continuous fiber in the preforming area, without considering the influence of the preforming heating temperature on the internal homogeneity of the continuous fiber, and without considering the correlation between the crack density and the curing temperature, which affects the curing effect and thus leads to the problem of low preparation efficiency. Summary of the Invention

[0009] To this end, the present invention provides a method for preparing a polyurethane pultrusion resin composite material, which is used to overcome the problem that the prior art only mentions heating the continuous fiber to gel in the preforming area, does not consider the influence of the preforming heating temperature on the internal homogeneity of the continuous fiber, and does not consider the relationship between crack density and curing temperature, which affects the curing effect and thus leads to low preparation efficiency.

[0010] To achieve the above object, the present invention provides a method for preparing a polyurethane pultrusion resin composite material, comprising: Pulling the glass fiber into a dipping tank filled with polyurethane resin at a first preset pulling rate for dipping for a preset dipping time; heating the impregnated glass fiber in a preforming mold at a first preset heating temperature, a second preset heating temperature, and a third preset heating temperature in sequence at a second preset pulling rate to obtain a precured gel molded body, obtaining a scattering intensity graph of the precured gel molded body, and calculating a scattering intensity standard deviation of the precured gel molded body, wherein the first preset heating temperature is less than the second preset heating temperature and the second preset heating temperature is less than the third preset heating temperature; When it is determined based on the standard deviation of the scattering intensity of the pre-cured gel molded body that the preparation of the pre-cured gel molded body does not meet the preset standard, adjusting the preparation parameters, wherein the preparation parameters include the preset immersion time and the second preset pulling rate; Producing a pre-cured gel molded body that meets a preset standard to a pultrusion die at a third preset pulling rate, and pultruding the body at a fourth preset heating temperature to obtain a cured molded body, wherein the third preset heating temperature is lower than the fourth preset heating temperature; Obtaining a plurality of corrugation amplitudes on the surface of the solidified molded body and obtaining an average corrugation amplitude; When it is determined based on the average ripple amplitude on the surface of the solidified molded body that the preparation of the solidified molded body does not meet the preset standard, an adjustment strategy is implemented to determine that the preparation of the solidified molded body does not meet the preset standard based on the surface texture curvature variance of the solidified molded body, wherein the adjustment strategy includes simultaneously reducing the second preset heating temperature and the third preset heating temperature and issuing an early warning when uneven heating of the pultrusion die is determined; The solidified molded body that meets the preset standards is pulled and naturally cooled to obtain a polyurethane resin composite material.

[0011] Furthermore, whether the preparation of the pre-cured gel molded body meets the preset standard is determined based on the scattering intensity standard deviation of the pre-cured gel molded body, wherein: If the scattering intensity standard deviation is less than the first preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body meets the preset standard; If the scattering intensity standard deviation is greater than or equal to the first preset scattering intensity standard deviation and less than the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the preset immersion time is increased according to the ratio between the scattering intensity standard deviation and the first preset scattering intensity standard deviation; If the scattering intensity standard deviation is greater than or equal to the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the second preset traction rate is reduced according to the difference between the scattering intensity standard deviation and the second preset scattering intensity standard deviation.

[0012] Furthermore, the process of obtaining the scattering intensity standard deviation includes: emitting an incident light beam to the surface of the pre-cured gel molded body, receiving reflected scattered signals through the matrix-arranged photoelectric sensors, and generating a scattered intensity distribution matrix; Dividing the scattering intensity distribution matrix into a number of rectangular sub-regions, and extracting the scattering intensity values ​​of all pixels in each sub-region; Calculate the arithmetic mean of the scattering intensities of all pixels in each sub-region as the average scattering intensity of the sub-region; The standard deviation of the scattering intensity of the surface of the pre-cured gel molded body is calculated.

[0013] Furthermore, several time adjustment methods are provided for increasing the preset immersion time, and each time adjustment method increases the preset immersion time by a different amount.

[0014] Furthermore, it is determined that the preparation of the solidified molded body meets the preset standard based on the comparison result that the average corrugation amplitude on the surface of the solidified molded body is greater than or equal to the first preset corrugation amplitude and less than the second preset corrugation amplitude, and it is secondly determined whether the preparation of the solidified molded body meets the preset standard based on the crack density of the solidified molded body.

[0015] Furthermore, based on the comparison result that the average corrugation amplitude of the surface of the solidified molded body is greater than the second preset corrugation amplitude, it is determined that the preparation of the solidified molded body does not meet the preset standard, and based on the surface texture curvature variance of the solidified molded body, an adjustment strategy for determining that the preparation of the solidified molded body does not meet the preset standard is determined.

[0016] Furthermore, the process of obtaining the average corrugation amplitude of the surface of the solidified molded body includes: Acquiring continuous surface contour point cloud data of the solidified molded body by a laser scanner; Extract the vertical distance between adjacent peaks and troughs in the contour data as the single ripple amplitude value; The arithmetic mean of all single ripple amplitude values ​​is calculated and recorded as the average ripple amplitude.

[0017] Furthermore, when it is secondarily determined that the preparation of the solidified molded body does not meet the preset standard based on the comparison result that the crack density of the solidified molded body is greater than the preset crack density, the fourth preset heating temperature is reduced based on the difference between the crack density and the preset crack density; the crack density is the number of cracks per unit area on the surface of the solidified molded body.

[0018] Furthermore, the reduction amplitude of the fourth preset heating temperature is positively correlated with the crack density difference value, wherein the crack density difference value is the difference between the crack density and the preset crack density.

[0019] Furthermore, an adjustment strategy is determined based on the surface texture curvature variance of the solidified molded body to determine if the preparation of the solidified molded body does not meet the preset standard, wherein: If the surface texture curvature variance is less than a preset surface texture curvature variance, then synchronously reducing the second preset heating temperature and the third preset heating temperature according to a ratio of the preset surface texture curvature variance to the surface texture curvature variance; If the surface texture curvature variance is greater than or equal to the preset surface texture curvature variance, it is determined that the pultrusion die is heated unevenly and an early warning is issued; The surface texture curvature variance is the variance of the curvature of several detection areas of the surface profile of the cured molded body.

[0020] Compared with the prior art, the beneficial effects of the present invention lie in that the present invention quantitatively evaluates the resin and fiber impregnation homogeneity in real time based on the standard deviation of the scattering intensity of the pre-cured gel body, verifies the surface smoothness of the pre-cured gel molded body and dynamically controls the impregnation time and pulling rate; uses the surface corrugation amplitude to preliminarily screen the surface flatness of the prepared cured molded body, and introduces the crack density of the cured molded body for secondary judgment; combines the surface texture curvature variance to accurately distinguish the regular network texture caused by over-curing and the disordered texture caused by uneven mold heat, and triggers the synchronous cooling or equipment early warning strategy in a targeted manner, thereby improving the preparation efficiency of resin composite materials.

[0021] Furthermore, the present invention sets the scattering intensity standard deviation for comparison with the first and second preset scattering intensity standard deviations, and uses the scattering intensity standard deviation as the core indicator to replace the traditional empirical qualitative judgment, so that the impregnation uniformity and pre-curing state of the pre-cured gel molded body can be accurately quantified. When the comparison results have slight deviations, the preparation correction is carried out by optimizing the impregnation parameters. When the comparison results have serious deviations, the preparation effect is improved by adjusting the traction parameters, thereby avoiding over-adjustment or under-adjustment.

[0022] Furthermore, the present invention sets a three-stage heating temperature in the preforming mold. The core purpose is to control the temperature gradient. The gradual increase in temperature can adapt the resin from low viscosity to the surface for initial solidification, so that the resin can fully penetrate the fiber gaps while achieving surface pre-curing, which ensures that the resin fully infiltrates the fiber gaps at a lower temperature stage, avoids premature gelation of the resin due to a sudden temperature rise and hinders penetration, ensures the structural stability of the pre-cured gel molded body and reduces the subsequent interface adhesion with the pultrusion mold, thereby improving the fluency of the subsequent pultrusion process.

[0023] Furthermore, the present invention receives reflected scattered signals through matrix-arranged photoelectric sensors and generates a distribution matrix, which can cover the surface area of ​​the pre-cured gel molded body, avoid the one-sidedness of local single-point detection, and ensure that the collected scattering intensity data can reflect the overall surface state, thereby improving the reliability of the detection indicators.

[0024] Furthermore, the present invention performs a secondary judgment based on crack density when the average corrugation amplitude is within the qualified range, thereby ensuring that the surface morphology meets the standards and screening for hidden crack defects, preventing products with qualified surfaces but structural hazards from flowing into subsequent links, and improving product quality. For the case where the average corrugation amplitude exceeds the standard, the surface texture curvature variance is introduced to distinguish the causes of the defects and achieve accurate traceability, so that the adjustment strategy can specifically solve the problems of improper pre-curing parameters or mold abnormalities, avoid blind adjustments, and thus improve detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for preparing a polyurethane pultrusion resin composite material according to an embodiment of the present invention; Figure 2 This is a flow chart for determining whether the preparation of the pre-cured gel molded body meets preset standards according to an embodiment of the present invention; Figure 3 This is a flow chart of an embodiment of the present invention for determining whether the preparation of the solidified molded body meets a preset standard based on the average corrugation amplitude on the surface of the solidified molded body; Figure 4 This is a flow chart of an adjustment strategy for determining if the preparation of the solidified molded body does not meet preset standards according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be pointed out that the data in this embodiment are all obtained by comprehensive analysis and evaluation of the historical test data of the present invention in the three months before this test and the corresponding historical test results. Those skilled in the art can understand that the method of determining the above-mentioned single parameter of the method of the present invention can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, use weighted summation to use the obtained value as the preset standard parameter, substitute each historical data into a specific formula and use the value obtained by the formula as the preset standard parameter or other selection methods, as long as the method of the present invention can clearly define the different specific situations in the single determination process through the obtained value.

[0029] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown, they are respectively a flow chart of a method for preparing a polyurethane pultrusion resin composite material according to an embodiment of the present invention; a flow chart of determining whether the preparation of the pre-cured gel molded body meets the preset standard according to an embodiment of the present invention; a flow chart of determining whether the preparation of the cured molded body meets the preset standard based on the average corrugation amplitude on the surface of the cured molded body according to an embodiment of the present invention; a flow chart of an adjustment strategy for determining whether the preparation of the cured molded body does not meet the preset standard according to an embodiment of the present invention.

[0030] An embodiment of the present invention provides a method for preparing a polyurethane pultrusion resin composite material, comprising: Step S1, pulling the glass fiber into a dipping tank filled with polyurethane resin at a first preset pulling speed of 1.5 m / min for a preset dipping time of 30 s for dipping; Step S2: heating the impregnated glass fiber in a preforming mold at a first preset heating temperature of 90° C., a second preset heating temperature of 120° C., and a third preset heating temperature of 150° C. in sequence at a second preset pulling rate of 0.9 m / min to obtain a precured gel molded body, obtaining a scattering intensity graph of the precured gel molded body, and calculating a scattering intensity standard deviation of the precured gel molded body, wherein the first preset heating temperature is less than the second preset heating temperature and the second preset heating temperature is less than the third preset heating temperature; Step S3, when it is determined based on the standard deviation of the scattering intensity of the pre-cured gel molded body that the preparation of the pre-cured gel molded body does not meet the preset standard, adjusting the preparation parameters, wherein the preparation parameters include the preset immersion time and the second preset pulling rate; Step S4, pulling the pre-cured gel molded body that meets the preset standards to a pultrusion die at a third preset pulling rate of 2.0 m / min, and pultruding it at a fourth preset heating temperature of 180° C. to obtain a cured molded body, wherein the third preset heating temperature is lower than the fourth preset heating temperature; Step S5, obtaining a plurality of corrugation amplitudes on the surface of the solidified molded body and calculating an average corrugation amplitude; Step S6, when it is determined based on the average ripple amplitude on the surface of the solidified molded body that the preparation of the solidified molded body does not meet the preset standard, determining an adjustment strategy for determining that the preparation of the solidified molded body does not meet the preset standard based on the surface texture curvature variance of the solidified molded body, wherein the adjustment strategy includes simultaneously reducing the second preset heating temperature and the third preset heating temperature and issuing a warning when it is determined that the pultrusion die is heated unevenly; Step S7: The solidified molded body that meets the preset standards is towed and naturally cooled, towed to room temperature, and left to cool for 30 minutes to obtain a polyurethane resin composite material.

[0031] It should be noted that the data in this embodiment are all obtained through preliminary experimental verification using the method described in the present invention before this test. The preset values ​​can be adjusted according to specific usage conditions, as long as the method described in the present invention can clearly define the different specific situations in the single determination process through the obtained values. The preset values ​​set in this embodiment are all obtained based on preliminary experiments, including the various correction coefficients, which were also selected through experimental verification.

[0032] Specifically, the value range of the first preset heating temperature is (80℃, 100℃), the value range of the second preset heating temperature is (110℃, 130℃), and the value range of the third preset heating temperature is (140℃, 160℃). Preferably, the first preset heating temperature is selected as 90℃, the second preset heating temperature is selected as 120℃, and the third preset heating temperature is selected as 150℃.

[0033] Specifically, the cross-sectional shape of the cavity of the preforming mold is geometrically similar to that of the final product, and its cross-sectional area is 105%-120% of the cross-sectional area of ​​the cavity of the pultrusion mold.

[0034] Specifically, after the impregnated glass fibers are heated in three stages within the preform mold, the polyurethane resin begins to undergo a cross-linking reaction, forming a preliminary gel network. This gel network imparts structural stability and shape retention to the pre-cured gel mold, enabling it to maintain its initial shape under traction and prevent loss of shape due to gravity or flow.

[0035] Specifically, whether the preparation of the pre-cured gel molded body meets the preset standard is determined based on the standard deviation of the scattering intensity of the pre-cured gel molded body, wherein: If the scattering intensity standard deviation is less than the first preset scattering intensity standard deviation of 1.8, it is determined that the preparation of the pre-cured gel molded body meets the preset standard; If the scattering intensity standard deviation is greater than or equal to the first preset scattering intensity standard deviation and less than 4.5 of the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the preset immersion time is increased according to the ratio between the scattering intensity standard deviation and the first preset scattering intensity standard deviation; If the scattering intensity standard deviation is greater than or equal to the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the second preset traction rate is reduced according to the difference between the scattering intensity standard deviation and the second preset scattering intensity standard deviation.

[0036] Specifically, the method for determining the standard deviation of scattering intensity of pre-cured gel molds utilizes the spatial distribution heterogeneity of the optical scattering signal (quantified by the standard deviation) to assess the surface preparation quality of the material. A scattering intensity standard deviation less than the first preset scattering intensity standard deviation indicates that the scattering intensity of each sub-region is very close to the average. This indicates that the surface and near-surface structure of the molded object are highly uniform across the entire measurement area. This reflects good surface smoothness, sufficient resin impregnation, uniform fiber distribution, and a consistent initial curing state. A moderate scattering intensity standard deviation indicates that the scattering intensity of each sub-region fluctuates. This indicates localized heterogeneity. This heterogeneity arises from insufficient or uneven resin impregnation of the glass fiber bundles, resulting in localized dry fibers, tiny bubbles, or resin-rich areas, which in turn affect the surface condition. Extending the impregnation time allows the resin more time to fully impregnate and penetrate the fibers. A scattering intensity standard deviation greater than the second preset scattering intensity standard deviation indicates that the scattering intensity of the pre-cured gel mold surface varies significantly, indicating severe heterogeneity.

[0037] Specifically, the first preset scattering intensity standard deviation is selected as 1.8, and the second preset scattering intensity standard deviation is selected as 4.5, but the above values ​​are not limited thereto, and those skilled in the art may adjust the above values ​​according to actual needs.

[0038] Specifically, the process of obtaining the scattering intensity standard deviation includes: emitting an incident light beam to the surface of the pre-cured gel molded body, receiving reflected scattered signals through the matrix-arranged photoelectric sensors, and generating a scattered intensity distribution matrix; Dividing the scattering intensity distribution matrix into a number of rectangular sub-regions, and extracting the scattering intensity values ​​of all pixels in each sub-region; Calculate the arithmetic mean of the scattering intensities of all pixels in each sub-region as the average scattering intensity of the sub-region; The standard deviation of the scattering intensity of the surface of the pre-cured gel molded body is calculated.

[0039] Specifically, there are several time adjustment methods for increasing the preset immersion time, among which: If the scattering intensity standard deviation ratio is less than the first preset scattering intensity standard deviation ratio of 1.25, the preset immersion time is increased to a corresponding value using the first time adjustment coefficient of 1.02; If the scattering intensity standard deviation ratio is greater than or equal to the first preset scattering intensity standard deviation ratio and less than the second preset scattering intensity standard deviation ratio of 1.75, then the preset immersion time is increased to the corresponding value using the second time adjustment coefficient of 1.04; If the scattering intensity standard deviation ratio is greater than or equal to the second preset scattering intensity standard deviation ratio, the preset immersion time is increased to a corresponding value using a third time adjustment coefficient of 1.06; The scattering intensity standard deviation ratio is a ratio between the scattering intensity standard deviation and the first preset scattering intensity standard deviation.

[0040] Specifically, whether the preparation of the solidified molded body meets the preset standard is determined based on the average corrugation amplitude of the surface of the solidified molded body, wherein: If the average corrugation amplitude is less than the first preset corrugation amplitude of 0.10 mm, it is determined that the preparation of the solidified molded body meets the preset standard; If the average corrugation amplitude is greater than or equal to the first preset corrugation amplitude and less than the second preset corrugation amplitude of 0.35 mm, it is determined that the preparation of the solidified molded body meets the preset standard, and a secondary determination is made as to whether the preparation of the solidified molded body meets the preset standard based on the crack density of the solidified molded body; If the average ripple amplitude is greater than or equal to the second preset scattering intensity standard deviation ratio, it is determined that the preparation of the solidified molded body does not meet the preset standard, and an adjustment strategy for the preparation of the solidified molded body not meeting the preset standard is determined based on the surface texture curvature variance of the solidified molded body.

[0041] Specifically, the value range of the first preset corrugation amplitude is (0.09mm, 0.299mm), and the value range of the second preset corrugation amplitude is (0.30mm, 0.50mm). Preferably, the first preset corrugation amplitude is selected as 0.10mm, and the second preset corrugation amplitude is selected as 0.35mm.

[0042] Specifically, the surface waviness of a solidified molded object reflects its surface flatness. A smaller waviness amplitude indicates a smooth surface with minimal fluctuations, while a larger waviness amplitude indicates significant surface undulations.

[0043] Specifically, the process of obtaining the average corrugation amplitude of the surface of the solidified molded body includes: Acquiring continuous surface contour point cloud data of the solidified molded body by a laser scanner; Extract the vertical distance between adjacent peaks and troughs in the contour data as the single ripple amplitude value; The arithmetic mean of all single ripple amplitude values ​​is calculated and recorded as the average ripple amplitude.

[0044] Specifically, the crack density of the solidified body is greater than the preset crack density of 0.3 cracks / cm 2 When the comparison result determines for the second time that the preparation of the solidified molded body does not meet the preset standard, the fourth preset heating temperature is reduced according to the difference between the crack density and the preset crack density; the crack density is the number of cracks per unit area on the surface of the solidified molded body.

[0045] Specifically, a camera is used to capture images of the surface of the cured molded body, and image analysis software is used to identify and count the number of cracks per unit area.

[0046] Specifically, the preset crack density is selected as 0.3 / cm 2 However, the above values ​​are not limited thereto, and those skilled in the art can adjust the above values ​​according to actual needs.

[0047] Specifically, crack density is used to measure the surface quality and internal structural integrity of the material. The presence of cracks will reduce the mechanical properties of the material, while also increasing the permeability of the material and reducing its weather resistance and corrosion resistance.

[0048] Specifically, the reduction amplitude of the fourth preset heating temperature is positively correlated with the crack density difference value, wherein the positive correlation is, for example, a linear positive correlation or a nonlinear positive correlation, and the linear slope of the linear positive correlation is not specifically limited. It can be understood that the larger the crack density difference value is, the greater the reduction amplitude of the fourth preset heating temperature is; the crack density difference value is the difference between the crack density and the preset crack density.

[0049] Specifically, an adjustment strategy is determined based on the surface texture curvature variance of the solidified molded body to determine whether the preparation of the solidified molded body does not meet the preset standard, wherein: If the surface texture curvature variance is less than the preset surface texture curvature variance of 0.13mm -2 , then the second preset heating temperature and the third preset heating temperature are synchronously reduced according to the ratio of the preset surface texture curvature variance to the surface texture curvature variance; If the surface texture curvature variance is greater than or equal to the preset surface texture curvature variance, it is determined that the pultrusion die is heated unevenly and an early warning is issued.

[0050] Specifically, the process of obtaining the surface texture curvature variance includes: A non-contact laser scanner is used to collect three-dimensional point cloud data on the surface of the solidified molding; Divide the scan data into several detection areas along the fiber pulling direction; For each detection area, the quadratic surface equation is fitted by the least squares method to calculate the curvature value; The arithmetic mean of the curvature of all regions is calculated and the variance is calculated, which is recorded as the surface texture curvature variance.

[0051] In this embodiment, the preset surface texture curvature variance is selected to be 0.13 mm. -2 However, the above values ​​are not limited thereto, and those skilled in the art can adjust the above values ​​according to actual needs.

[0052] Specifically, when the surface texture curvature variance falls below a preset threshold, it indicates a pre-cured layer that is too thick. Excessive temperatures during the pre-curing stage can lead to excessive cross-linking of the polyurethane resin, causing the surface layer to harden and thicken. This hardened surface loses fluidity, hindering the resin from fully filling the mold cavity during the subsequent pultrusion process, resulting in a large, uniform, wavy morphology. These waves manifest as long, low-steep, continuous undulations, resulting in a gentle change in surface curvature and a reduced curvature variance.

[0053] When the surface texture curvature variance reaches or exceeds a preset threshold, it indicates a mold heating system failure. Failure in the pultrusion die's temperature control can lead to localized temperature differences exceeding the specified range, triggering a sudden change in the resin's curing rate. The non-uniform curing process causes an imbalance in the shrinkage stress distribution, resulting in localized sharp peak-valley defects. These defects manifest as short-wavelength, high-steepness abrupt morphologies, causing dramatic fluctuations in surface curvature and increased curvature variance.

[0054] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0055] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a polyurethane pultrusion resin composite material, characterized in that: include: Pulling the glass fiber into a dipping tank filled with polyurethane resin at a first preset pulling rate for dipping for a preset dipping time; heating the impregnated glass fiber in a preforming mold at a first preset heating temperature, a second preset heating temperature, and a third preset heating temperature in sequence at a second preset pulling rate to obtain a precured gel molded body, obtaining a scattering intensity graph of the precured gel molded body, and calculating a scattering intensity standard deviation of the precured gel molded body, wherein the first preset heating temperature is less than the second preset heating temperature and the second preset heating temperature is less than the third preset heating temperature; When it is determined based on the standard deviation of the scattering intensity of the pre-cured gel molded body that the preparation of the pre-cured gel molded body does not meet the preset standard, adjusting the preparation parameters, wherein the preparation parameters include the preset immersion time and the second preset pulling rate; Producing a pre-cured gel molded body that meets a preset standard to a pultrusion die at a third preset pulling rate, and pultruding the body at a fourth preset heating temperature to obtain a cured molded body, wherein the third preset heating temperature is lower than the fourth preset heating temperature; Obtaining a plurality of corrugation amplitudes on the surface of the solidified molded body and obtaining an average corrugation amplitude; When it is determined based on the average ripple amplitude on the surface of the solidified molded body that the preparation of the solidified molded body does not meet the preset standard, an adjustment strategy is implemented to determine that the preparation of the solidified molded body does not meet the preset standard based on the surface texture curvature variance of the solidified molded body, wherein the adjustment strategy includes simultaneously reducing the second preset heating temperature and the third preset heating temperature and issuing an early warning when uneven heating of the pultrusion die is determined; The solidified molded body that meets the preset standards is pulled and naturally cooled to obtain a polyurethane resin composite material.

2. The method for preparing a polyurethane pultrusion resin composite material according to claim 1, wherein: Determining whether the preparation of the pre-cured gel molded body meets the preset standard according to the standard deviation of the scattering intensity of the pre-cured gel molded body, wherein: If the scattering intensity standard deviation is less than the first preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body meets the preset standard; If the scattering intensity standard deviation is greater than or equal to the first preset scattering intensity standard deviation and less than the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the preset immersion time is increased according to the ratio between the scattering intensity standard deviation and the first preset scattering intensity standard deviation; If the scattering intensity standard deviation is greater than or equal to the second preset scattering intensity standard deviation, it is determined that the preparation of the pre-cured gel molded body does not meet the preset standard, and the second preset traction rate is reduced according to the difference between the scattering intensity standard deviation and the second preset scattering intensity standard deviation.

3. The method for preparing a polyurethane pultrusion resin composite material according to claim 2, wherein: The process of obtaining the scattering intensity standard deviation includes: emitting an incident light beam to the surface of the pre-cured gel molded body, receiving reflected scattered signals through the matrix-arranged photoelectric sensors, and generating a scattered intensity distribution matrix; Dividing the scattering intensity distribution matrix into a number of rectangular sub-regions, and extracting the scattering intensity values ​​of all pixels in each sub-region; Calculate the arithmetic mean of the scattering intensities of all pixels in each sub-region as the average scattering intensity of the sub-region; The standard deviation of the scattering intensity of the surface of the pre-cured gel molded body is calculated.

4. The method for preparing a polyurethane pultrusion resin composite material according to claim 3, characterized in that: Several time adjustment methods are provided for increasing the preset immersion time, and each time adjustment method increases the preset immersion time by a different amount.

5. The method for preparing a polyurethane pultrusion resin composite material according to claim 4, characterized in that: The preparation of the solidified molded body is judged to meet the preset standard based on the comparison result that the average corrugation amplitude of the surface of the solidified molded body is greater than or equal to the first preset corrugation amplitude and less than the second preset corrugation amplitude, and the preparation of the solidified molded body is secondarily judged to meet the preset standard based on the crack density of the solidified molded body.

6. The method for preparing a polyurethane pultrusion resin composite material according to claim 5, characterized in that: According to the comparison result that the average corrugation amplitude of the surface of the solidified molded body is greater than the second preset corrugation amplitude, it is determined that the preparation of the solidified molded body does not meet the preset standard, and according to the surface texture curvature variance of the solidified molded body, an adjustment strategy is determined that the preparation of the solidified molded body does not meet the preset standard.

7. The method for preparing a polyurethane pultrusion resin composite material according to claim 6, characterized in that: The process of obtaining the average corrugation amplitude of the surface of the solidified molded body includes: Acquiring continuous surface contour point cloud data of the solidified molded body by a laser scanner; Extract the vertical distance between adjacent peaks and troughs in the contour data as the single ripple amplitude value; The arithmetic mean of all single ripple amplitude values ​​is calculated and recorded as the average ripple amplitude.

8. The method for preparing a polyurethane pultrusion resin composite material according to claim 7, characterized in that: When it is secondarily determined that the preparation of the solidified molded body does not meet the preset standard based on the comparison result that the crack density of the solidified molded body is greater than the preset crack density, the fourth preset heating temperature is reduced based on the difference between the crack density and the preset crack density; the crack density is the number of cracks per unit area on the surface of the solidified molded body.

9. The method for preparing a polyurethane pultrusion resin composite material according to claim 8, wherein: The reduction range of the fourth preset heating temperature is positively correlated with the crack density difference value, wherein the crack density difference value is the difference between the crack density and the preset crack density.

10. The method for preparing a polyurethane pultrusion resin composite material according to claim 9, characterized in that: An adjustment strategy is determined based on the surface texture curvature variance of the solidified molded body to determine whether the preparation of the solidified molded body does not meet the preset standard, wherein: If the surface texture curvature variance is less than a preset surface texture curvature variance, then synchronously reducing the second preset heating temperature and the third preset heating temperature according to a ratio of the preset surface texture curvature variance to the surface texture curvature variance; If the surface texture curvature variance is greater than or equal to the preset surface texture curvature variance, it is determined that the pultrusion die is heated unevenly and an early warning is issued; The surface texture curvature variance is the variance of the curvature of several detection areas of the surface profile of the cured molded body.

Images