Insole preparation method based on hot pressing technology

Abstract

The invention relates to the technical field of insole preparation, in particular to an insole preparation method based on a hot-pressing technology, which comprises the following steps: providing a base layer material and a hot-pressing layer material; the base layer and the hot pressing layer are compounded and then placed in a hot press, and a shoe pad rough blank is formed through pressing under the preset hot pressing pressure and temperature; segmental exhausting is carried out in the hot pressing process so as to exhaust gas in the material; cooling the hot-pressed shoe pad rough blank, and demolding the cooled shoe pad rough blank from the mold; performing sampling visual inspection on the insole rough blank, obtaining a surface image of the insole rough blank, extracting bubble characteristics, and calculating a bubble density ratio; and judging whether the insole preparation process is qualified or not based on a comparison result of the bubble density ratio obtained by calculation and a preset bubble density ratio, and performing cutting and edge finishing on the qualified insole rough blank to obtain a finished insole. According to the method, the insole preparation efficiency and quality are improved by improving the analysis accuracy of unqualified reasons in the insole preparation process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insole preparation, and particularly relates to an insole preparation method based on hot-pressing technology. BACKGROUND

[0002] In the field of insole preparation, hot-pressing technology is widely used in the production of various functional insoles because it can efficiently realize the compounding and molding of materials. However, the existing insole preparation method based on hot-pressing technology still has many problems to be solved. During the hot-pressing process, due to the differences in the characteristics of EVA and TPU materials, especially the higher hot-pressing temperature and pressure required for TPU, bubbles are easily generated in the material due to the failure of timely gas discharge, which seriously affects the structural stability and service life of the insole. At the same time, the existing detection and adjustment mechanism is not perfect, and in most production processes, the appearance of the insole is only detected by manual sampling, which is difficult to accurately quantify the bubble characteristics, and for unqualified products, it is impossible to scientifically analyze the reasons based on the detection data and make targeted adjustments.

[0003] Chinese patent application No. CN116985323A discloses a hot-pressing insole preparation process, an insole and a shoe. The hot-pressing insole preparation process comprises the following steps: providing a mold, a first sheet and a second sheet for standby, the parting surface of the mold is provided with a shaping portion and an arc-shaped portion, the elastic modulus of the second sheet is different from that of the first sheet; the first sheet and the second sheet are placed in an overlapping manner on the parting surface of the mold; the mold is closed, the first sheet and the second sheet are hot-pressed and heat-insulated for a first time; the mold is opened to obtain an insole roughcast, the insole roughcast corresponds to the arc-shaped portion and the shaping portion to form a support sheet and a pad body respectively, and a folded edge is arranged at the connection between the support sheet and the pad body; the support sheet can be folded along the folded edge to form a support portion protruding towards the first sheet or the second sheet, and the prepared insole can realize left-right interchange and improve the fit with the human foot.

[0004] However, the existing technology still has the following problems:

[0005] The determination of equipment failure lacks clear basis, when the product is still unqualified after adjusting the parameters for many times, the equipment problem cannot be identified in time and a maintenance notice cannot be sent, which easily causes production delay and cost increase. SUMMARY

[0006] Therefore, the present application provides an insole preparation method based on hot-pressing technology to overcome the problems in the prior art that the determination of equipment failure lacks clear basis, when the product is still unqualified after adjusting the parameters for many times, the equipment problem cannot be identified in time and a maintenance notice cannot be sent, which easily causes production delay and cost increase.

[0007] To achieve the above object, the application provides a shoe insole preparation method based on hot-pressing technology.

[0008] Step S1, providing a base layer material and a hot-pressing layer material, the base layer material being EVA, and the hot-pressing layer material being TPU;

[0009] Step S2, after the base layer and the hot-pressing layer are compounded, placing them in a hot press to press under preset hot-pressing pressure and temperature to form a shoe insole roughcast;

[0010] Step S3, carrying out segmented degassing during the hot-pressing process to discharge gas in the material;

[0011] Step S4, cooling the hot-pressed shoe insole roughcast and demolding the cooled shoe insole roughcast from the mold;

[0012] Step S5, carrying out sampling visual inspection on the shoe insole roughcast, acquiring a surface image thereof and extracting bubble features, and calculating a bubble density ratio;

[0013] Step S6, judging whether the shoe insole preparation process is qualified based on a comparison result of the calculated bubble density ratio and a preset bubble density ratio, and adjusting the degassing amount of segmented degassing in the next preparation process based on a bubble density ratio difference and a thickness of the shoe insole roughcast, and determining repeated adjustment of the degassing amount when the shoe insole preparation process is still unqualified after the degassing amount adjustment is completed;

[0014] Step S7, carrying out cutting and edge finishing on the shoe insole roughcast judged to be qualified to obtain a finished shoe insole.

[0015] Further, judging whether the shoe insole preparation process is qualified based on the comparison result of the calculated bubble density ratio and the preset bubble density ratio comprises:

[0016] If the bubble density ratio is less than the preset bubble density ratio, it is judged that the shoe insole preparation process is qualified;

[0017] If the bubble density ratio is greater than or equal to the preset bubble density ratio, it is judged that the shoe insole preparation process is unqualified, and the degassing amount of segmented degassing in the next preparation process is adjusted.

[0018] Further, the degassing amount is increased according to the bubble density ratio difference, and the increase amount of the degassing amount is positively correlated with the bubble density ratio difference.

[0019] Further, in the step S6, the degassing amount is corrected according to the thickness of the shoe insole roughcast, and the correction amount of the degassing amount is positively correlated with the thickness of the shoe insole roughcast.

[0020] Further, in the step S6, based on the fact that the insole manufacturing process is still unqualified after the adjustment of the exhaust volume is completed, it is determined to repeat the adjustment of the exhaust volume, and when the exhaust volume in the next adjustment is greater than the preset exhaust volume or it is determined that the exhaust volume of the segmented exhaust in the next insole manufacturing process is greater than the preset exhaust volume, the reason for the unqualified insole manufacturing process is determined based on the bubble feature distribution density.

[0021] Further, in the step S6, the determination of the reason for the unqualified insole manufacturing process based on the bubble feature distribution density includes:

[0022] If the bubble feature distribution density is less than the preset distribution density, it is determined that the reason for the unqualification is the uneven heat distribution of the heat press machine;

[0023] If the bubble feature distribution density is greater than or equal to the preset distribution density, it is determined that the reason for the unqualification is the abnormal pressure fluctuation of the heat press machine;

[0024] The bubble feature distribution density is the average distribution distance of the bubbles in the image.

[0025] Further, in the step S6, when the reason for the unqualification is the uneven heat distribution of the heat press machine, the flow rate of the heating medium in the heat press plate is increased according to the difference in the bubble feature distribution density, and the increase in the flow rate of the heating medium is positively correlated with the difference in the bubble feature distribution density.

[0026] Further, in the step S6, during the increase in the flow rate of the heating medium in the heat press plate, the average temperature of the heat press plate after the adjustment of the flow rate of the heating medium is increased by a holding time, and the increase in the holding time is positively correlated with the average temperature.

[0027] Further, when the reason for the unqualification is the abnormal pressure fluctuation of the heat press machine, the pressure of the heat press machine is increased according to the density fluctuation ratio, and the increase in the pressure of the heat press machine is positively correlated with the density fluctuation ratio;

[0028] The density fluctuation ratio is the ratio of the bubble density ratio in this preparation to the bubble density ratio in the previous preparation.

[0029] Further, after the flow rate of the heating medium in the heat press plate, the holding time, and / or the pressure of the heat press machine are adjusted, if the insole manufacturing process is still unqualified, it is determined that the equipment is malfunctioning, and a maintenance notice is issued.

[0030] Compared with the prior art, the present application has the beneficial effects that, by taking the bubble density ratio as the core index, the traditional qualitative judgment relying on artificial vision is converted into quantifiable numerical comparison, avoiding the judgment deviation caused by human experience difference; the bubble is a typical defect in the insole compounding process, and its density directly reflects the heat pressing and exhaust effect. Taking the bubble density ratio as the qualified judgment basis, when the bubble density ratio exceeds the standard, the problem of insufficient gas exhaust can be solved by adjusting the exhaust amount, avoiding the waste of resources caused by blind adjustment of other parameters; too many bubbles will cause the insole structure to be loose, affecting its mechanical properties and use experience, and the potential defective products can be screened out in advance through bubble density ratio control, avoiding the unqualified products to flow into the subsequent process and reducing the waste of materials and working hours; the bubble content of the final product is ensured to be within a reasonable range, and the structural integrity and use reliability of the insole are ensured.

[0031] Further, the present application takes the bubble density ratio difference as the adjustment basis, and the exhaust amount to be increased can be directly calculated through the first proportion coefficient, the exhaust amount increase is distributed in proportion according to the material state of each stage of heat pressing, the exhaust amount is adjusted as needed, the exhaust in the initial stage of heat pressing is preferentially guaranteed, which has the highest gas content and the greatest influence on bubbles, the source of bubble formation can be quickly reduced, the exhaust amount is moderately adjusted in the middle stage, and the gas exhaust and material combination effect are balanced; the exhaust amount is less adjusted in the later stage, avoiding the structure defects such as insole depression caused by excessive exhaust, this targeted distribution greatly improves the exhaust efficiency, reduces the bubbles, and ensures the insole forming quality.

[0032] Further, the thickness of the insole is a key factor affecting the difficulty of gas exhaust in the present application, the path of gas diffusion from the inside to the exhaust passage is longer, and the total amount of material is more, so the total amount of gas released when heated is also larger; the gas exhaust path of the thinner insole is short, and the required exhaust amount is relatively less, through the design that the exhaust amount correction amount is positively correlated with the thickness, the exhaust demand of products with different thicknesses can be targeted matched, and the bubble density ratio of insoles with different thicknesses can be stably controlled within the qualified range, improving the quality consistency of all specifications of products.

[0033] Further, when the insole is still unqualified after the first adjustment of the exhaust volume, the exhaust volume is continuously increased through repeated adjustment mechanism. For the problem of insufficient exhaust volume caused by batch difference of materials, environmental humidity fluctuation, etc., the actual gas exhaust demand can be accurately matched through multiple fine tuning to avoid the problem of too large or too small single adjustment range; ensure that the exhaust volume does not reach the preset upper limit, fully utilize the adjustment space of the exhaust parameter to solve the bubble problem, maximize the value of parameter optimization; when the exhaust volume is about to exceed the preset value, stop blindly increasing the exhaust volume to avoid irreversible defects such as material shortage, depression, and delamination of the insole caused by excessive exhaust, and protect the product structure integrity; when the exhaust volume has reached or exceeded the preset value and there is still a bubble, switch to bubble feature distribution density analysis, and the sparse bubble distribution corresponds to uneven heat distribution of the hot press, which can be targeted to calibrate the temperature control module of the hot press; the dense bubble distribution corresponds to abnormal pressure fluctuation, which can focus on repairing the pressure valve or hydraulic system; such accurate positioning avoids blind troubleshooting of the equipment, and the bubble distribution analysis quickly locates the equipment failure, shortens the downtime, and reduces the resource consumption caused by continuous production of unqualified products.

[0034] Further, by comparing the bubble feature distribution density with the preset distribution density, the present application can directly distinguish between uneven heat distribution of the hot press and abnormal pressure fluctuation. When the bubble distribution is sparse, it is determined that the heat distribution is uneven (e.g., local low temperature makes it difficult for gas to be exhausted); when the bubble distribution is dense (the average distance is small, i.e., the feature distribution density is greater than or equal to the preset value), it is determined that the pressure fluctuation is abnormal (e.g., unstable pressure causes exhaust disorder), which quickly locates the reason for the unqualified insole preparation and adjusts accordingly, improving the accuracy of insole preparation process analysis and thus improving the insole preparation efficiency and quality.

[0035] Further, in the present application, the flow rate of the heating medium directly affects the heat transfer efficiency of the hot press plate. The higher the flow rate, the more uniform the heat distribution in the hot press plate. Through the design that the increase in the flow rate of the heating medium is positively correlated with the difference in the bubble feature distribution density, on-demand distribution of heat regulation can be achieved, and accurate flow rate control can control the temperature difference of each region of the hot press plate to a smaller range, thereby reducing the problem of bubble aggregation caused by local low temperature from the root.

[0036] Further, in the present application, when the flow rate of the heating medium increases, the average temperature of the hot press plate increases (especially the temperature of the low-temperature area increases), but the material needs sufficient time to realize heat penetration. The design that the increase amount of the holding time is positively correlated with the average temperature avoids the problem of surface melting and internal non-melting caused by sudden temperature rise but insufficient holding, ensures that the material from the surface to the deep layer reaches a stable melting state, and reduces the formation of implicit bubbles caused by insufficient melting; the adjustment of the flow rate of the heating medium may cause short-term fluctuations in the temperature of the hot press plate (such as local temperature rising too fast), and the increase of the holding time can buffer such fluctuations. Prolonging the holding time can make the temperature of each area of the hot press plate further tend to be uniform, and reduce the problem of local material overheating or under-melting caused by "instantaneous high temperature but uneven distribution"; at the same time, the stable holding process can allow the material to slowly solidify under the action of pressure, avoid structural stress concentration caused by rapid cooling (such as cracking of the edge of the insole and internal delamination), and improve the integrity of the structure of the finished product.

[0037] Further, the density fluctuation in the present application directly reflects the influence of pressure fluctuation on bubble generation. The larger the ratio is, the more serious the bubble problem caused by unstable pressure is. Through the design that the increase amplitude of the pressure is positively correlated with the density fluctuation ratio, dynamic calibration of the pressure can be realized. This targeted adjustment avoids the problem of excessive extrusion and loss of the material caused by "blindly increasing the basic pressure", and protects the thickness precision of the insole while stabilizing the pressure; when the parameters such as the flow rate of the heating medium, the holding time, and the pressure are adjusted and still not qualified, it is determined that the equipment is faulty and a maintenance notice is issued, avoiding the vicious cycle of "invalid parameter adjustment but continuous production", and timely preventing the generation of unqualified products in large quantities; the problems that can be solved by parameter optimization are clearly distinguished from equipment hardware faults, and safety hazards caused by neglecting equipment problems are prevented. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The flowchart of the insole preparation method based on the hot pressing technology of the present application;

[0039] Figure 2 The determination flowchart for determining whether the insole preparation process is qualified;

[0040] Figure 3 The determination flowchart for determining the reason why the insole preparation process is unqualified. DETAILED DESCRIPTION

[0041] In order to make the purpose and advantages of the present application more clear and explicit, the present application will be further described below in combination with examples; it should be understood that the specific examples described herein are only used to explain the present application, and do not limit the present application.

[0042] It should be noted that the data in the embodiment are obtained by comprehensive analysis and evaluation of the historical data and corresponding historical determination results in the past 6 months before the present determination according to the application. Those skilled in the art can understand that the determination method of the application for a single parameter can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, to use weighted summation to obtain the value as the preset standard parameter, to substitute each historical data into a specific formula and to obtain the value by using the formula as the preset standard parameter, or other selection methods, as long as the application can clearly define different specific situations in the single determination process by the obtained value.

[0043] The preferred embodiments of the application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the application, and are not intended to limit the protection scope of the application.

[0044] It should be noted that in the description of the application, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the direction or positional relationship terms based on the direction or positional relationship shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the application.

[0045] In addition, it should also be noted that in the description of the application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between the two elements inside. Those skilled in the art can understand the specific meaning of the above terms in the application according to the specific circumstances.

[0046] Please refer to Figure 1 As shown in the flowchart of the shoe insole preparation method based on the hot pressing technology of the application.

[0047] The application provides a shoe insole preparation method based on hot pressing technology. It comprises:

[0048] Step S1, providing a base layer material and a hot pressing layer material, the base layer material is EVA, and the hot pressing layer material is TPU;

[0049] Step S2, after compounding the base layer and the hot pressing layer, placing them in a hot press to press to form a shoe insole rough blank under a preset hot pressing pressure and temperature;

[0050] Step S3, segmental exhaust during the hot pressing process to exhaust the gas in the material;

[0051] Step S4, cooling the insole rough cast after hot pressing, and demolding the insole rough cast after cooling from the mold;

[0052] Step S5, sampling visual inspection of the insole rough cast, obtaining its surface image and extracting bubble features, and calculating the bubble density ratio;

[0053] Step S6, determining whether the insole preparation process is qualified based on the comparison result of the calculated bubble density ratio and the preset bubble density ratio, and adjusting the exhaust amount of the segmented exhaust in the next preparation process based on the bubble density ratio difference and the thickness of the insole rough cast when the insole preparation process is determined to be unqualified, and determining to repeat adjusting the exhaust amount when the insole preparation process is still unqualified after adjusting the exhaust amount;

[0054] Step S7, cutting and edge finishing the insole rough cast determined to be qualified to obtain the finished insole.

[0055] In the embodiment of the application, the EVA is ethylene-vinyl acetate copolymer, the TPU is thermoplastic polyurethane elastomer, and the preset hot pressing pressure and temperature can be determined by the following method. From the material melting characteristics, the melting temperature of EVA is usually between 80-120℃, and the melting temperature of TPU is usually in the range of 150-200℃ due to the difference in type. In order to ensure that both materials can reach a molten state to achieve close combination during hot pressing, and to avoid material degradation or performance deterioration due to excessive temperature, the preset hot pressing temperature needs to be in the interval that makes TPU fully melt and EVA maintains good fluidity, which is generally set to 160-180℃ (preferably 170℃). This temperature range can ensure that the TPU molecular chain moves fully, while the EVA softens and fills into the microstructure of the TPU layer, enhancing the interlayer bonding force. In terms of hot pressing pressure, the density and exhaust effect of the material need to be considered. Too small pressure will cause gaps between the composite layers, which is easy to leave gas and form bubbles. Too large pressure may cause excessive extrusion of the material, affecting the thickness accuracy and structural integrity of the insole. Combined with the hardness and fluidity of the two materials after melting, the preset hot pressing pressure is usually set to 5-10MPa (preferably 7.5MPa). This pressure range can promote the full contact of EVA and TPU in a molten state, exclude air between the layers, and at the same time make the molecules of the two materials penetrate each other through the action of pressure, forming a stable bonding interface.

[0056] In the embodiment of the present application, the segmented exhaust is carried out during the hot pressing process. From the material state of the hot pressing stage, in the initial stage of hot pressing, the EVA and TPU in the composite layer are in the stage of softening under heat, and there are more free gases on the surface of the material and between the layers, and at this time, the material has not yet been completely attached, and the gas flowability is strong. Therefore, the first segment exhaust needs to use a larger exhaust amount, the purpose is to quickly exhaust a large amount of free gas, and to reduce the basis for bubble formation in the subsequent hot pressing process, and the exhaust amount accounts for 40%-50% of the total initial exhaust amount. For example, when the total initial exhaust amount is set to 3L / min (exhausted in 3 segments), the first segment exhaust amount can be set to 1.2-1.5L / min; in the middle stage of hot pressing, the material gradually melts and begins to penetrate each other, at this time, the released gas is mainly the gas adsorbed in the material and the trace gas generated in the melting process, and the gas release rate is slower than the initial stage. Therefore, the second segment exhaust amount needs to be appropriately reduced to avoid the molten material being excessively extracted due to excessive exhaust amount, which affects the bonding effect of the composite layer, and the exhaust amount is usually 30%-35% of the total initial exhaust amount, that is, the second segment exhaust amount can be set to 0.9-1.05L / min; in the later stage of hot pressing, the material has basically completed the composite molding, and only a small amount of deep gas is slowly released, at this time, the exhaust amount needs to be further reduced to ensure that the material is stably solidified under the action of pressure, and to prevent the insole from having defects such as depression after molding due to excessive exhaust. The exhaust amount in this stage is usually 15%-20% of the total initial exhaust amount, that is, the third segment exhaust amount can be set to 0.45-0.6L / min; the early stage of hot pressing refers to the stage from the beginning of the composite layer entering the hot press to the completion of the material softening under heat but not completely melting. The time of this stage accounts for 20%-30% of the total hot pressing time, the middle stage of hot pressing is the stage from the beginning of the material melting to the gradual realization of the interlayer penetration and combination, and the time accounts for 40%-50% of the total hot pressing time; the later stage of hot pressing is the stage from the completion of the penetration and combination to the realization of the stable solidification and molding of the material, and the time accounts for 20%-30% of the total hot pressing time.

[0057] Referring to Figure 2 as shown in the drawing, which is a determination flow chart for determining whether the insole preparation process is qualified.

[0058] Specifically, determining whether the insole preparation process is qualified based on the comparison result of the calculated bubble density ratio and the preset bubble density ratio includes:

[0059] If the bubble density ratio is less than the preset bubble density ratio, it is determined that the insole preparation process is qualified;

[0060] If the bubble density ratio is greater than or equal to the preset bubble density ratio, it is determined that the insole preparation process is unqualified, and the exhaust amount of the segmented exhaust in the next preparation process is adjusted.

[0061] The bubble density ratio in the embodiment of the present application is the ratio of the bubble characteristic area to the total area of the shoe pad roughcast, and the preset bubble density ratio is the average of the bubble density ratios of a plurality of qualified shoe pad samples, but the above values are not limited thereto, and a person skilled in the art can adjust them according to the actual situation.

[0062] The present application converts the traditional qualitative judgment relying on artificial vision into quantifiable numerical comparison by taking the bubble density ratio as the core index, avoiding the judgment deviation caused by human experience difference; the bubble is a typical defect in the shoe pad compounding process, and its density directly reflects the heat pressing and exhaust effect. Taking the bubble density ratio as the basis for qualification, when the bubble density ratio exceeds the standard, the problem of insufficient gas exhaust can be solved by adjusting the exhaust amount, avoiding the waste of resources caused by blind adjustment of other parameters; too many bubbles will cause the shoe pad structure to be loose, affecting its mechanical properties and use experience, and the potential defective products can be screened out in advance by controlling the bubble density ratio, avoiding the flow of unqualified products into the subsequent process and reducing the waste of materials and working hours; ensuring that the bubble content of the final product is within a reasonable range, and guaranteeing the structural integrity and use reliability of the shoe pad.

[0063] Specifically, the exhaust amount is increased according to the bubble density ratio difference, and the increase amount of the exhaust amount is positively correlated with the bubble density ratio difference.

[0064] The bubble density ratio difference in the embodiment of the present application is the difference between the actual bubble density ratio and the preset bubble density ratio, and the increase amount of the exhaust amount is the product of the first proportional coefficient and the bubble density ratio difference, and the first proportional coefficient can be determined by the following method: fixing the heat pressing temperature, pressure and total heat pressing time, adjusting only the proportion of the segmented exhaust amount, setting a control group, segmenting the exhaust according to the standard, setting an experimental group adjusting only the exhaust amount of a certain stage, and recording the change of the bubble density ratio; obtaining the bubble density ratio (actual value / preset value) of each shoe pad through a visual detection system; taking the bubble density ratio difference as the horizontal axis and the increase amount of the exhaust amount as the vertical axis, fitting the slope of the straight line to obtain the first proportional coefficient k; due to the differences in gas source and material state in the early, middle and late stages of heat pressing, the increase amount of the exhaust amount needs to be allocated differently according to the stage differences, and the characteristics of the priority stage are matched; the heat pressing early stage mainly exhausts the surface and interlayer free gas, which has the greatest impact on bubble formation, so the highest proportion of the adjustment amount is allocated, accounting for 50%-60% of the total increase amount; the heat pressing middle stage exhausts the adsorbed gas in the material and the trace gas generated by melting, and the proportion of the adjustment amount is 30%-35%; the heat pressing late stage only has a small amount of deep gas remaining, and excessive adjustment may cause material depression, so the proportion of the adjustment amount is 10%-15%; but the above values are not limited thereto, and a person skilled in the art can adjust them according to the actual situation.

[0065] The application takes the bubble density ratio difference as the adjustment basis, directly calculates the required exhaust volume through the first proportional coefficient, proportionally distributes the exhaust volume increase according to the material state of each stage of hot pressing, realizes on-demand adjustment, preferentially guarantees the exhaust in the initial stage of hot pressing which has the highest gas content and the greatest impact on bubbles, quickly reduces the source of bubble formation, moderately adjusts in the middle stage to balance the gas exhaust and material combination effect, and less adjusts in the later stage to avoid structural defects such as insole depression caused by excessive exhaust. This targeted distribution greatly improves the exhaust efficiency, reduces bubbles while guaranteeing the insole forming quality.

[0066] Specifically, in the step S6, the exhaust volume is corrected according to the thickness of the insole rough blank, and the correction amount of the exhaust volume is positively correlated with the thickness of the insole rough blank.

[0067] The correction amount of the exhaust volume in the embodiment of the application is the product of the second proportional coefficient and the thickness of the insole rough blank. The second proportional coefficient can be determined by the following method: fixing the hot pressing temperature, pressure, total hot pressing time and initial proportion of segmented exhaust, only changing the target thickness of the insole rough blank and adjusting the exhaust volume correction amount, setting a control group (using the standard exhaust volume, without thickness-related correction) and an experimental group (applying exhaust volume correction for different thicknesses); selecting a thickness gradient (such as 2mm, 4mm, 6mm, 8mm, etc.) covering the common range of actual production, for each thickness level, adjusting the exhaust volume correction amount, and recording the actual correction amount when the bubble density ratio reaches the preset value; taking the thickness of the insole rough blank as the horizontal axis and the corresponding exhaust volume correction amount as the vertical axis, linearly fitting the experimental data, and the slope of the obtained straight line is the second proportional coefficient; the distribution method of the correction amount of the exhaust volume is the same as the distribution method of the adjustment amount of the exhaust volume, but the above values are not limited thereto, and those skilled in the art can adjust them according to the actual situation.

[0068] In the application, the thickness of the insole is a key factor affecting the difficulty of gas exhaust. The path of gas diffusion from the inside to the exhaust passage is longer, and the total amount of material is more, so the total amount of gas released when heated is also larger. The gas exhaust path of a thinner insole is short, and the required exhaust volume is relatively small. Through the design of positively correlating the exhaust volume correction amount with the thickness, the exhaust demand of products of different thicknesses can be targetedly matched, and the bubble density ratio of insoles of different thicknesses can be stably controlled within the qualified range, thereby improving the quality consistency of products of all specifications.

[0069] Specifically, in the step S6, based on the fact that the insole preparation process is still unqualified after the exhaust volume adjustment is completed, the exhaust volume is repeatedly adjusted, and when the exhaust volume in the next adjustment is greater than the preset exhaust volume or it is determined that the exhaust volume of the segmented exhaust in the next insole preparation process is greater than the preset exhaust volume, the reason why the insole preparation process is unqualified is determined based on the bubble feature distribution density.

[0070] The preset exhaust volume in the embodiment of the present application is not more than the critical value causing excessive material loss (to avoid the loss of control of the thickness accuracy of the insole and the structural defects) and not more than the critical value causing defects such as concave and wrinkle in the material curing process. The critical value can be determined by the following method: fixing the heat pressing temperature, pressure and total heat pressing time, taking the standard segmented exhaust proportion (50% in the early stage, 35% in the middle stage and 15% in the late stage) as the benchmark, gradually increasing the total initial exhaust volume (for example, starting from 3L / min, increasing by 0.5L / min each time), and performing multiple experiments; detecting the insole rough cast of each experiment and recording the exhaust volume corresponding to the following critical state. When the exhaust volume increases to a certain value, the insole edge appears obvious material loss and the thickness deviation exceeds the allowable range (for example, ±5% of the designed thickness), and the exhaust volume at this time is the critical value of material loss. When the exhaust volume increases to a certain value, the insole surface appears concave, the inside appears layered or wrinkled, and the exhaust volume at this time is the critical value of structural defects. The preset exhaust volume is the minimum value that meets the above two conditions, but the above values are not limited thereto, and the person skilled in the art can adjust them according to the actual situation.

[0071] It can be understood that the main cause of the bubbles in the insole is that the gas is not fully discharged during the heat pressing process, and the exhaust volume is a key parameter directly affecting the gas discharge effect. If the insole is still unqualified after the exhaust volume is adjusted for the first time, it is highly probable that the increase amplitude of the exhaust volume does not meet the requirement of eliminating bubbles. At this time, the exhaust volume is repeatedly adjusted by gradually increasing the exhaust volume until the bubble density ratio meets the standard. When the exhaust volume is large enough but there are still bubbles, it indicates that the root cause is not the insufficient exhaust volume, but other key parameters of the heat pressing system are abnormal. The distribution density of the bubbles can directly reflect these abnormalities. If the bubbles are sparsely distributed, it indicates that the gas in the local area is difficult to discharge, and the heat distribution is uneven. If the bubbles are densely distributed, it indicates that the gas discharge process is disorderly, and the pressure fluctuation is abnormal.

[0072] When the shoe pad is still unqualified after the first adjustment of the exhaust volume, the exhaust volume is continuously increased through repeated adjustment mechanism, and for the problem of insufficient exhaust volume caused by batch difference of materials, environmental humidity fluctuation and the like, the actual gas exhaust demand can be accurately matched through multiple fine adjustment to avoid the problem of too large or too small single adjustment range; before the exhaust volume reaches the preset upper limit, the adjustment space of the exhaust parameter is fully utilized to solve the bubble problem, and the value of parameter optimization is maximized; when the exhaust volume is about to exceed the preset value, the exhaust volume is stopped from being blindly increased to avoid irreversible defects such as material shortage, depression and delamination of the shoe pad caused by excessive exhaust, and the structural integrity of the product is protected; when the exhaust volume has reached or exceeded the preset value and there is still a bubble, the bubble feature distribution density analysis is switched to, the bubble distribution is sparse, the heat distribution of the hot press is uneven, the temperature control module of the hot press can be calibrated accordingly; the bubble distribution is dense, the pressure fluctuation is abnormal, and the pressure valve or hydraulic system can be focused on for repair; such accurate positioning avoids blind troubleshooting of the equipment, the equipment fault is quickly located through bubble distribution analysis, the downtime is shortened, and the resource consumption caused by continuous production of unqualified products is reduced.

[0073] Referring to Figure 3 As shown in the flow chart of determining the unqualified reason of the shoe pad preparation process.

[0074] Specifically, in the step S6, the determination of the unqualified reason of the shoe pad preparation process based on the bubble feature distribution density comprises:

[0075] If the bubble feature distribution density is less than the preset distribution density, it is determined that the unqualified reason is uneven heat distribution of the hot press;

[0076] If the bubble feature distribution density is greater than or equal to the preset distribution density, it is determined that the unqualified reason is abnormal pressure fluctuation of the hot press.

[0077] The bubble feature distribution density is the average distribution distance of the bubbles in the image.

[0078] The preset distribution density in the embodiment of the present application is the average value of the bubble feature distribution densities of a plurality of qualified shoe pad samples, but the above-mentioned value is not limited thereto, and a person skilled in the art can adjust it according to the actual situation.

[0079] By comparing the bubble feature distribution density with the preset distribution density, the uneven heat distribution of the hot press and the abnormal pressure fluctuation can be directly distinguished, when the bubble distribution is sparse, it is determined that the heat distribution is uneven (for example, local temperature is too low to cause difficulty in gas exhaust); when the bubble distribution is dense (the average distance is small, that is, the feature distribution density is greater than or equal to the preset value), it is determined that the pressure fluctuation is abnormal (for example, unstable pressure causes exhaust disorder), the unqualified reason of the shoe pad preparation is quickly located through the above-mentioned method and then adjusted accordingly, the accuracy of the shoe pad preparation process analysis is improved, and the shoe pad preparation efficiency and quality are improved.

[0080] Specifically, in the step S6, when the unqualified reason is the uneven heat distribution of the hot press, the flow rate of the heating medium in the hot press plate is increased according to the difference between the preset distribution density and the bubble feature distribution density, and the increase amount of the flow rate of the heating medium is positively correlated with the difference between the bubble feature distribution density.

[0081] In the embodiment of the present application, the difference between the bubble feature distribution density and the preset distribution density is the difference between the bubble feature distribution density and the preset distribution density, and the increase amount of the flow rate of the heating medium is the product of the third proportional coefficient and the difference between the bubble feature distribution density, and the determination method of the third proportional coefficient is the same as that of the first proportional coefficient and the second proportional coefficient, which will not be described here.

[0082] In the present application, the flow rate of the heating medium directly affects the heat transfer efficiency of the hot press plate, the higher the flow rate, the more uniform the heat distribution in the hot press plate, and through the design that the increase amount of the flow rate of the heating medium is positively correlated with the difference between the bubble feature distribution density, the on-demand distribution of heat regulation can be realized, and accurate flow rate control can control the temperature difference of each region of the hot press plate to a smaller range, thereby reducing the problem of bubble aggregation caused by local low temperature from the root.

[0083] Specifically, in the step S6, after the flow rate of the heating medium in the hot press plate is increased, the average temperature of the hot press plate is increased based on the flow rate of the heating medium, and the increase amount of the holding time is positively correlated with the average temperature.

[0084] In the embodiment of the present application, the increase amount of the holding time is the product of the fourth proportional coefficient and the average temperature of the hot press plate after the flow rate of the heating medium is adjusted, and the determination method of the fourth proportional coefficient is the same as that of the first proportional coefficient and the second proportional coefficient, which will not be described here.

[0085] In the present application, after the flow rate of the heating medium is increased, the average temperature of the hot press plate is increased (especially the temperature of the low temperature region is increased), but the material needs sufficient time to realize heat penetration, and through the design that the increase amount of the holding time is positively correlated with the average temperature, the problems of surface melting and internal unmelted caused by sudden temperature rise but insufficient holding time are avoided, so that the material from the surface to the deep layer can reach a stable melting state, and the hidden bubbles caused by insufficient melting are reduced; the adjustment of the flow rate of the heating medium may cause short-term fluctuations of the temperature of the hot press plate (such as local temperature rising too fast), and the increase of the holding time can buffer such fluctuations, and the extension of the holding time can make the temperature of each region of the hot press plate further tend to be uniform, thereby reducing the local material overheating or under-melting caused by “instantaneous high temperature but uneven distribution”; at the same time, the stable holding process can allow the material to slowly solidify under the action of pressure, thereby avoiding the structural stress concentration caused by rapid cooling (such as cracking of the edge of the insole and internal delamination), and improving the integrity of the structure of the finished product.

[0086] Specifically, when the unqualified reason is that the hot press pressure fluctuation is abnormal, the hot press pressure is increased according to the density fluctuation ratio, and the increase range of the hot press pressure is positively correlated with the density fluctuation ratio.

[0087] The density fluctuation ratio is the ratio of the bubble density ratio in this preparation to the bubble density ratio in the previous preparation.

[0088] The increase range of the hot press pressure in the embodiment of the application is the product of the fifth proportional coefficient and the density fluctuation ratio, and the determination method of the fifth proportional coefficient is the same as that of the first proportional coefficient and the second proportional coefficient, which will not be described here.

[0089] Specifically, after adjusting the heating medium flow rate in the hot press plate, the holding time and / or the hot press pressure, if the insole preparation process is still unqualified, it is determined that the equipment is faulty, and a maintenance notice is issued.

[0090] The density fluctuation ratio directly reflects the influence degree of pressure fluctuation on bubble generation in the application. The greater the ratio, the more serious the bubble problem caused by unstable pressure. Through the design that the increase range of the pressure is positively correlated with the density fluctuation ratio, dynamic calibration of the pressure can be realized. This targeted adjustment avoids the excessive extrusion and loss of materials caused by "blindly increasing the basic pressure", and protects the thickness accuracy of the insole while stabilizing the pressure. When the parameters such as the heating medium flow rate, the holding time and the pressure are still unqualified after adjustment, it is determined that the equipment is faulty, and a maintenance notice is issued, which avoids the vicious cycle of "ineffective parameter adjustment but continuous production" and prevents the timely prevention of the generation of large quantities of unqualified products. It is clear to distinguish the problems that can be solved by parameter optimization and equipment hardware failure, and to prevent safety hazards caused by neglecting equipment problems.

[0091] The technical solutions of the application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the application, and the technical solutions after the changes or replacements will fall within the protection scope of the application.

[0092] The above description is only the preferred embodiments of the application and is not used to limit the application; for those skilled in the art, the application can have various changes and variations, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing shoe insoles based on hot pressing technology, characterized in that, include: Step S1: Provide a base material and a hot-pressed layer material, wherein the base material is EVA and the hot-pressed layer material is TPU; Step S2: After the base layer and the hot-pressed layer are combined, they are placed in a hot press and pressed under a preset hot-pressing pressure and temperature to form a shoe insole blank; Step S3: During the hot pressing process, segmented venting is performed to remove gas from the material; Step S4: Cool the hot-pressed insole blank and demold the cooled insole blank from the mold; Step S5: Perform visual inspection on the sampled insole blank, obtain its surface image and extract bubble features, and calculate the bubble density ratio; Step S6: Based on the comparison between the calculated bubble density ratio and the preset bubble density ratio, determine whether the insole preparation process is qualified. If the insole preparation process is determined to be unqualified, adjust the exhaust volume of the segmented exhaust in the next preparation process based on the difference in bubble density ratio and the thickness of the insole blank. If the insole preparation process is still unqualified after the exhaust volume adjustment, determine to repeat the adjustment of the exhaust volume. Step S7: Cut and trim the edges of the qualified insole blank to obtain the finished insole.

2. The method for preparing insoles based on hot-pressing technology according to claim 1, characterized in that, In step S6, determining whether the insole manufacturing process is qualified based on the comparison between the calculated bubble density ratio and the preset bubble density ratio includes: If the bubble density ratio is less than the preset bubble density ratio, the insole manufacturing process is deemed qualified. If the bubble density ratio is greater than or equal to the preset bubble density ratio, the insole preparation process is deemed unqualified, and the exhaust volume of the segmented exhaust in the next preparation process is adjusted.

3. The method for preparing insoles based on hot-pressing technology according to claim 2, characterized in that, In step S6, the exhaust volume is increased according to the difference in bubble density ratio, and the increase in exhaust volume is positively correlated with the difference in bubble density ratio.

4. The method for preparing insoles based on hot-pressing technology according to claim 3, characterized in that, In step S6, the air release volume is adjusted according to the thickness of the insole blank, and the adjustment amount of the air release volume is positively correlated with the thickness of the insole blank.

5. The method for preparing insoles based on hot-pressing technology according to claim 4, characterized in that, In step S6, if the insole preparation process is still unqualified after the exhaust volume adjustment, it is determined to repeatedly adjust the exhaust volume. If the exhaust volume during the next adjustment is greater than the preset exhaust volume or the exhaust volume of the segmented exhaust volume during the next insole preparation process is greater than the preset exhaust volume, the reason for the unqualified insole preparation process is determined based on the characteristic distribution density of the bubbles.

6. The method for preparing insoles based on hot-pressing technology according to claim 5, characterized in that, In step S6, determining the reasons for non-compliance in the insole manufacturing process based on the characteristic distribution density of air bubbles includes: If the bubble characteristic distribution density is less than the preset distribution density, the reason for non-compliance is determined to be uneven heat distribution in the hot press. If the bubble characteristic distribution density is greater than or equal to the preset distribution density, the reason for non-compliance is determined to be abnormal pressure fluctuation of the hot press. Wherein, the bubble feature distribution density is the average distribution distance of bubbles in the image.

7. The method for preparing insoles based on hot-pressing technology according to claim 6, characterized in that, In step S6, when the reason for non-compliance is uneven heat distribution in the hot press, the flow rate of the heating medium in the hot press plate is increased according to the difference in bubble characteristic distribution density. The increase in the flow rate of the heating medium is positively correlated with the difference in bubble characteristic distribution density.

8. The method for preparing insoles based on hot-pressing technology according to claim 7, characterized in that, In step S6, during the process of increasing the flow rate of the heating medium in the hot press plate, the heat preservation time is increased based on the average temperature of the hot press plate after the flow rate of the heating medium is adjusted, and the increase in heat preservation time is positively correlated with the average temperature.

9. The method for preparing insoles based on hot-pressing technology according to claim 8, characterized in that, When the reason for non-compliance is abnormal pressure fluctuation of the hot press, the pressure of the hot press is increased according to the density fluctuation ratio, and the increase in the pressure of the hot press is positively correlated with the density fluctuation ratio. The density fluctuation ratio is the ratio of the bubble density ratio in this preparation to the bubble density ratio in the previous preparation.

10. The method for preparing insoles based on hot-pressing technology according to claim 9, characterized in that, In step S6, if the insole preparation process is still unqualified after adjusting the flow rate of the heating medium in the hot press plate, the heat preservation time and / or the pressure of the hot press, it is determined to be an equipment failure and a maintenance notice is issued.

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