A process for preparing a slush PVC skin based on a modified PVC material

Abstract

The application relates to the technical field of PVC material preparation, in particular to a preparation process of a slush molding PVC skin based on modified PVC material, which comprises the following steps: heating a slush molding mold, conveying a material box containing PVC slush molding powder to the lower side of the slush molding mold, and coupling the material box and the slush molding mold; turning the coupled material box and slush molding mold for several times, and the excess PVC slush molding powder falls into the material box; the material box and the slush molding mold are separated, the slush molding mold is cooled, demolded and used to output finished slush molding skins; the interval time length between the heating time and the cooling time is determined based on the average roughness of a sampling area in the finished slush molding skin; the first turning speed of the slush molding mold is determined based on the proportion of the number of defective products in the finished slush molding skin; and the second turning speed is determined based on the maximum thickness difference of the finished slush molding skin. The application realizes the improvement of the preparation accuracy of PVC materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of PVC material preparation, and particularly relates to a preparation process of a slush PVC skin based on modified PVC material. BACKGROUND

[0002] In the prior art, slush molding, also known as rotational molding, is a process for manufacturing hollow parts from thermoplastic and / or thermosetting resins. The products manufactured by this process can have various shapes and have a constant thickness ranging from 0.5-15 mm. During the manufacturing process of the product, the outer surface of the product depends on the shape of the inner surface of the mold. During the rotation process, the powder enters the mold, contacts the hot mold, melts and forms a sheet with uneven thickness on the inner wall of the mold.

[0003] Chinese Patent Publication No. CN105385071A discloses a slush PVC material for automotive interior skin and a preparation method thereof, including the following steps: 1) weighing each reaction substance according to the weight ratio; 2) mixing any three or four combinations of dioctyl sebacate, propylene glycol adipate, trioctyl trimellitate, tridecyl trimellitate, diacetyl epoxidized vegetable oil acid glyceride, and phosphite in a premixing tank for 5-20 minutes; 3) heating the material in the premixing tank to 50-70 DEG C, then adding pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and stirring until completely dissolved; 4) putting the suspension type polyvinyl chloride resin into a reaction kettle, stirring at a speed of 100-300 revolutions per minute, starting to heat to 50-70 DEG C, then sequentially adding zinc malleate, zinc stearate, calcium stearate, hydrotalcite, oleic acid amide, pentaerythritol, and inorganic pigments; 5) adding the material in the premixing tank to the reaction kettle by spraying; 6) then heating to 110-130 DEG C, and the powder in the reaction kettle is discharged to a cooling kettle by high-speed stirring and centrifugal action at 250-350 revolutions per minute, and the material is discharged after stirring and cooling. It can be seen that the slush PVC material for automotive interior skin and the preparation method thereof have the problem that the preparation precision of the modified PVC material decreases due to the fact that part of the PVC slush powder cannot be completely attached to the slush mold during the preparation process, resulting in uneven surface of the finished slush skin, and further resulting in increased surface roughness of the finished slush skin. SUMMARY

[0004] Therefore, the present application provides a preparation process of a slush PVC skin based on modified PVC material, which overcomes the problem that the preparation precision of the modified PVC material decreases due to the fact that part of the PVC slush powder cannot be completely attached to the slush mold during the preparation process in the prior art, resulting in uneven surface of the finished slush skin, and further resulting in increased surface roughness of the finished slush skin.

[0005] To achieve the above object, the application provides a kind of based on the preparation process of modified PVC material's slush PVC skin, comprising the following steps: heating to slush mold, the material box containing PVC slush powder is transported to the lower of the slush mold, the material box and slush mold are coupled;The material box and slush mold after coupling are turned over several times, and the excess PVC slush powder falls into the material box, and the material box and slush mold are separated, the slush mold is cooled and demoulded to output finished product slush skin;The interval length of heating time and cooling time is determined based on the average roughness of the sampling area in the finished product slush skin, or the number of defective products in several finished product slush skins and the total number of finished product slush skins are obtained respectively;The first overturning speed of the slush mold is determined based on the proportion of the number of defective products in the finished product slush skin, or the running rate of the material box is determined based on the proportion of the number of defective products in the finished product slush skin and the average weight of several finished product slush skins;The thickness of the finished product slush skin output after a single cycle according to the first overturning speed of the slush mold is obtained;The second overturning speed is determined based on the maximum thickness difference of the finished product slush skin;Wherein, the first overturning speed is less than the second overturning speed.

[0006] Further, the composition and mass fraction of the finished product slush skin are: 10 parts of PVC base material, 3 parts of plasticizer, 0.4 parts of stabilizer, 0.2 parts of colorant, 0.2 parts of drying agent, 0.05 parts of internal release agent.

[0007] Further, the step of determining the interval length of heating time and cooling time further comprises determining the preparation accuracy of modified PVC material based on the average roughness of the sampling area in the finished product slush skin.

[0008] Wherein, if the average roughness of the sampling area in the finished product slush skin meets the first roughness condition or the second roughness condition, it is determined that the preparation accuracy of modified PVC material is lower than the allowable range.

[0009] When the average roughness of the sampling area in the finished product slush skin meets the trigger condition for determining the interval length of heating time and cooling time, the slush mold is heated and cooled according to the determined interval length.

[0010] Wherein, the trigger condition is that the average roughness of the sampling area in the finished product slush skin only meets the second roughness condition, and the interval length of heating time and cooling time is determined by the difference between the average roughness of the sampling area in the finished product slush skin and the preset second roughness.

[0011] Further, the calculation formula of the average roughness of the sampling area in the finished product slush skin is:

[0012]

[0013] wherein G is the average roughness of the sampling region in the finished slush skin, K b is the roughness of the bth sampling region in the finished slush skin, u is the number of sampling regions, and u is a natural number greater than or equal to 1.

[0014] Further, the first roughness condition is that the average roughness of the sampling region in the finished slush skin is greater than a preset first roughness and less than or equal to a preset second roughness; and the second roughness condition is that the average roughness of the sampling region in the finished slush skin is greater than the preset second roughness.

[0015] Further, the step of determining the first flipping speed of the slush mold comprises:

[0016] The number of defective products in the finished slush skins and the total number of the finished slush skins in each preparation cycle are obtained respectively, and the proportion of the number of defective products in the finished slush skins is calculated.

[0017] The proportion of the number of defective products in the finished slush skins is compared with a preset first proportion and a preset second proportion respectively.

[0018] If the proportion of the number of defective products in the finished slush skins is greater than the preset first proportion and less than or equal to the preset second proportion, the slush mold is flipped at the first flipping speed.

[0019] Further, the first flipping speed of the slush mold is determined by the difference between the proportion of the number of defective products in the finished slush skins and the preset first proportion.

[0020] Further, if the proportion of the number of defective products in the finished slush skins is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling of the material box and the slush mold is lower than the allowable range.

[0021] Further, the step of determining the running rate of the material box further comprises secondarily determining the effectiveness of the coupling of the material box and the slush mold based on the average weight of the plurality of finished slush skins,

[0022] If the average weight of the plurality of finished slush skins is greater than a preset weight, it is secondarily determined that the effectiveness of the coupling of the material box and the slush mold is lower than the allowable range, and the material box is controlled to move at the running rate of the material box.

[0023] wherein the running rate of the material box is determined by the difference between the average weight of the plurality of finished slush skins and the preset weight.

[0024] Further, the step of determining the second flipping speed of the slush mold comprises:

[0025] The thickness of the finished product slush skin in a single operation cycle is acquired, and the maximum thickness difference of the finished product slush skin is calculated;

[0026] The maximum thickness difference of the finished product slush skin is compared with a preset difference;

[0027] If the maximum thickness difference of the finished product slush skin is greater than the preset difference, the slush mold is controlled to be flipped at the second flipping speed;

[0028] The second flipping speed of the slush mold is determined by the difference between the maximum thickness difference of the finished product slush skin and the preset difference.

[0029] Compared with the prior art, the process has the beneficial effects that the interval between the heating time and the cooling time is adjusted according to the average roughness of the sampling area in the finished product slush skin, because part of the PVC slush powder cannot be completely attached to the slush mold during preparation, resulting in uneven surface of the finished product slush skin, thus increasing the surface roughness of the finished product slush skin. By shortening the interval between the heating time and the cooling time, the temperature difference between the PVC slush powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and make the slush skin more closely attached to the mold surface, reducing the unevenness and roughness of the surface. The flipping speed of the slush mold is adjusted according to the proportion of defective products in the finished product slush skin. Because the gas heating method is used during heating of the slush mold, when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in too high temperature in the heating area, which makes part of the PVC slush powder melt and be more easily absorbed on the mold surface, thus causing unstable quality of the finished product slush skin and increasing the defective product rate. By reducing the flipping speed of the slush mold, the temperature rising speed in the heating area is slowed down, which helps to reduce the heat accumulation in the heating area and reduce the risk of local overheating, thus ensuring the uniformity and consistency of the slush skin and improving the surface quality stability of the finished product slush skin. The moving speed of the material box is adjusted according to the average weight of the finished product slush skin. Because the material aging of the moving structure of the material box causes the target position of the material box to be unable to stop in time, resulting in deviation, the coupling with the slush mold is not tight, causing part of the PVC slush powder to leak out and reducing the weight of the finished product slush skin. By reducing the moving speed of the material box, the accuracy of the movement of the material box is improved, so that the coupling is more tight. The first flipping speed of the slush mold is adjusted according to the maximum thickness difference of the finished product slush skin. Because the flipping speed is too slow, the thickness of the finished product slush skin is in a wave shape, resulting in too large thickness difference. By increasing the flipping speed, the roughness of the slush skin is reduced, and the preparation accuracy and environmental protection of the modified PVC are improved.

[0030] Further, the process of the present application adjusts the interval between the heating time and the cooling time by setting the preset first roughness and the preset second roughness. Due to the fact that part of the PVC slush molding powder cannot be completely fitted with the slush mold during the preparation process, the surface of the finished slush skin is uneven, which increases the surface roughness of the finished slush skin. By shortening the interval between the heating time and the cooling time, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and makes the slush skin more closely adhere to the surface of the mold, reduces the unevenness and roughness of the surface, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0031] Further, the process of the present application adjusts the interval between the heating time and the cooling time by setting the preset first roughness and the preset second roughness. Due to the fact that part of the PVC slush molding powder cannot be completely fitted with the slush mold during the preparation process, the surface of the finished slush skin is uneven, which increases the surface roughness of the finished slush skin. By shortening the interval between the heating time and the cooling time, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and makes the slush skin more closely adhere to the surface of the mold, reduces the unevenness and roughness of the surface, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0032] Further, the process of the present application adjusts the interval between the heating time and the cooling time by setting the preset first roughness and the preset second roughness. Due to the fact that part of the PVC slush molding powder cannot be completely fitted with the slush mold during the preparation process, the surface of the finished slush skin is uneven, which increases the surface roughness of the finished slush skin. By shortening the interval between the heating time and the cooling time, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and makes the slush skin more closely adhere to the surface of the mold, reduces the unevenness and roughness of the surface, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0033] Further, the process of the present application adjusts the interval between the heating time and the cooling time by setting the preset first roughness and the preset second roughness. Due to the fact that part of the PVC slush molding powder cannot be completely fitted with the slush mold during the preparation process, the surface of the finished slush skin is uneven, which increases the surface roughness of the finished slush skin. By shortening the interval between the heating time and the cooling time, the temperature difference between the PVC slush molding powder and the mold and the stress caused by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and makes the slush skin more closely adhere to the surface of the mold, reduces the unevenness and roughness of the surface, and further improves the preparation accuracy and environmental protection of the modified PVC. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1The overall flow chart of the preparation process of the slush molding PVC skin based on the modified PVC material according to the embodiment of the present application is shown in the figure;

[0035] Figure 2 The specific flow chart of the process of determining the first turnover speed of the slush molding mold in the preparation process of the slush molding PVC skin based on the modified PVC material according to the embodiment of the present application is shown in the figure;

[0036] Figure 3 The specific flow chart of the process of determining the second turnover speed of the slush molding mold in the preparation process of the slush molding PVC skin based on the modified PVC material according to the embodiment of the present application is shown in the figure;

[0037] Figure 4 The structural schematic diagram of the rotating assembly in the preparation process of the slush molding PVC skin based on the modified PVC material according to the embodiment of the present application is shown in the figure;

[0038] The reference signs are as follows: 1 - material box, 2 - slush molding mold, 3 - clamping claw, 4 - rotating motor, 5 - rotating shaft, 6 - vertical rod, 7 - sliding rail, 8 - sliding plate, 9 - sliding rail motor. DETAILED DESCRIPTION

[0039] In order to make the objects and advantages of the present application clearer, the present application will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0040] The preferred embodiments of the present application will be 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 application and are not intended to limit the protection scope of the present application.

[0041] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description and does 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 on the present application.

[0042] In addition, it should also be noted that, in the description of the present 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 internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0043] It should be pointed out that the data in the embodiment are obtained according to historical data and corresponding data statistics in the detection process, test experiments and comprehensive analysis according to experimental results before the detection; the modified PVC material based slush PVC skin preparation process is used to accumulate statistics, detection and calculation of 1684 finished slush skins in 95 days before the detection, and the average roughness of the sampling area in the finished slush skin, the percentage of defective products in the finished slush skin, the average weight of a plurality of finished slush skins and the maximum thickness difference of the finished slush skin are determined, and the values of the preset parameter standards of the modified PVC material based slush PVC skin preparation process are comprehensively determined. Those skilled in the art can understand that the determination method of the modified PVC material based slush PVC skin preparation process according to the single parameter can be to select the value with the highest percentage according to the data distribution as the preset standard parameter, as long as the process of the application can be determined by the obtained value. Different specific conditions in the single determination process.

[0044] Please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 , which are respectively the overall flowchart of the modified PVC material based slush PVC skin preparation process of the embodiment of the application, the specific flowchart of the first turning speed process of the slush mold, the specific flowchart of the second turning speed process of the slush mold and the structure diagram of the rotating assembly. The modified PVC material based slush PVC skin preparation process of the embodiment of the application comprises the following steps:

[0045] Step S1, heating the slush mold, conveying the material box containing PVC slush powder to the lower side of the slush mold, and connecting and coupling the material box and the slush mold;

[0046] Step S2, turning the coupled material box and slush mold several times, and the excess PVC slush powder falls into the material box, and the material box and the slush mold are separated, the slush mold is cooled and demolded to output the finished slush skin;

[0047] Step S3, determining the interval time between the heating time and the cooling time based on the average roughness of the sampling area in the finished slush skin, or respectively obtaining the number of defective products in a plurality of finished slush skins and the total number of finished slush skins;

[0048] Step S4, determining the first turning speed of the slush mold based on the percentage of defective products in the finished slush skin, or determining the running rate of the material box based on the percentage of defective products in the finished slush skin and the average weight of a plurality of finished slush skins.

[0049] Step S5, obtaining the thickness of the finished slush skin output after a single cycle of operation according to the first turning speed of the slush mold;

[0050] Step S6, determining the second turning speed based on the maximum thickness difference of the finished slush skin;

[0051] Wherein, the first turning speed is less than the second turning speed.

[0052] Specifically, the calculation formula of the proportion of the number of defective products in the finished slush skin is:

[0053]

[0054] Wherein, P is the proportion of the number of defective products in the finished slush skin, Z1 is the number of defective products in the finished slush skin, and Z2 is the total number of finished slush skins.

[0055] Specifically, the defective product in the finished slush skin is the surface roughness of the finished slush skin greater than or equal to 15μm.

[0056] Specifically, the calculation formula of the average weight of the finished slush skin is:

[0057]

[0058] Wherein, T is the average weight of the finished slush skin, S d is the weight of the dth finished slush skin, c is the number of finished slush skins, and c is a natural number greater than or equal to 1.

[0059] Specifically, the calculation formula of the maximum thickness difference of the finished slush skin is:

[0060] F = E1-E2

[0061] Wherein, F is the maximum thickness difference of the finished slush skin, E1 is the maximum thickness of the same finished slush skin, and E2 is the minimum thickness of the same finished slush skin.

[0062] Specifically, the interval between the heating time and the cooling time means the interval between the time when the slush mold starts heating and the time when the cooling starts.

[0063] Specifically, the composition of PVC slush powder includes PVC resin, plasticizer, stabilizer and filler.

[0064] Optionally, the preferred embodiment of the plasticizer is diethylhexyl phthalate, the preferred embodiment of the stabilizer is calcium zinc stabilizer, and the preferred embodiment of the filler is talc powder.

[0065] Specifically, the PVC resin is in the form of particles with a particle size of 200 μm, the diethylhexyl phthalate is in the form of an oily liquid, the calcium-zinc stabilizer is in the form of a powder with a particle size of 80 μm, and the talc is in the form of a powder with a particle size of 30 μm.

[0066] Specifically, the step of obtaining the roughness of the sampling area of the finished slush skin includes dividing the surface of the finished slush skin into a plurality of equidistant sampling areas and detecting the roughness of the plurality of equidistant sampling areas using a laser sensor.

[0067] Specifically, the rotating assembly for coupling the material box and the slush mold includes:

[0068] The material box 1 is used to store PVC slush powder.

[0069] The sliding plate 8 is connected to the material box 1 and is used to support the material box 1.

[0070] The sliding rail 7 is connected to the sliding plate 8 and is used to provide a movement path for the sliding plate 8.

[0071] The sliding rail motor 9 is connected to the sliding rail 7 and is used to provide movement power for the material box 1.

[0072] The slush mold 2 is arranged above the material box 1 and is used to shape the PVC slush powder.

[0073] The clamping jaw 3 is connected to the slush mold 2 and is used to couple the material box 1 and the slush mold 2.

[0074] The rotating shaft 5 is connected to the clamping jaw 3 and is used to rotate the coupled material box 1 and slush mold 2.

[0075] The rotating motor 4 is connected to the rotating shaft 5 and is used to provide rotation power.

[0076] The vertical rod 6 is connected to the rotating shaft 5 and is used to provide a movement path for the rotating shaft 5 in the vertical direction.

[0077] Specifically, the running speed of the material box is adjusted by changing the speed of the sliding rail motor.

[0078] Specifically, the flipping speed of the slush mold is adjusted by changing the speed of the rotating motor.

[0079] Specifically, the weight of the finished slush skin is detected by a weight sensor.

[0080] Specifically, the thickness of the finished slush skin is detected by a thickness sensor.

[0081] In the implementation, the process disclosed by the application adjusts the interval length between the heating time and the cooling time according to the average roughness of the sampling area in the finished cast skin. Due to the fact that part of the PVC cast powder cannot be completely attached to the cast mold during the preparation process, the surface of the finished cast skin is uneven, which leads to the increase of the surface roughness of the finished cast skin. By shortening the interval length between the heating time and the cooling time, the temperature difference between the PVC cast powder and the mold and the stress generated by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion and makes the cast skin more closely attached to the surface of the mold, thereby reducing the unevenness and roughness of the surface. By adjusting the turning speed of the cast mold according to the proportion of the number of defective products in the finished cast skin, since the gas heating method is used during the heating process of the cast mold, when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, which leads to the fact that the temperature of the heating area is too high, causing part of the PVC cast powder to melt and be more easily absorbed on the surface of the mold, thereby leading to the instability of the quality of the finished cast skin and increasing the defective product rate of the product. By reducing the turning speed of the cast mold, the temperature rising speed of the heating area can be slowed down, which helps to reduce the heat accumulation in the heating area and reduce the risk of local overheating, thereby ensuring the uniformity and consistency of the cast skin and improving the surface quality stability of the finished cast skin. By adjusting the running speed of the hopper according to the average weight of a plurality of finished cast skins, since the material aging of the moving structure of the hopper occurs, the hopper cannot stop in time when it reaches the target position of the hopper, which leads to deviation, so that the coupling with the cast mold cannot be tightly coupled, causing part of the PVC cast powder to leak out, which reduces the weight of the finished cast skin. By reducing the moving speed of the hopper, the accuracy of the movement of the hopper is improved, so that the coupling is more tightly coupled. By adjusting the first turning speed of the cast mold according to the maximum thickness difference of the finished cast skin, since the turning speed is too slow, the thickness of the finished cast skin is in a wavy shape, which leads to a large thickness difference. By increasing the turning speed, the roughness of the cast skin is reduced, and the preparation accuracy and environmental protection of the modified PVC are improved.

[0082] Specifically, the composition and quality parts of the finished cast skin are as follows: 10 parts of PVC base material, 3 parts of plasticizer, 0.4 parts of stabilizer, 0.2 parts of colorant, 0.2 parts of drying agent, 0.05 parts of internal release agent.

[0083] Specifically, the step of determining the interval length between the heating time and the cooling time further comprises determining the preparation accuracy of the modified PVC material based on the average roughness of the sampling area in the finished cast skin.

[0084] If the average roughness of the sampling area in the finished cast skin meets the first roughness condition or the second roughness condition, it is determined that the preparation accuracy of the modified PVC material is lower than the allowable range.

[0085] If the average roughness of the sampling area in the finished slush skin only meets the preset first roughness condition, it is preliminarily determined that the contact effectiveness of the PVC slush powder and the mold is lower than the allowable range, and the contact effectiveness of the PVC slush powder and the mold is determined again based on the proportion of defective products in the finished slush skin.

[0086] Specifically, the first roughness condition is that the average roughness of the sampling area in the finished slush skin is greater than the preset first roughness and less than or equal to the preset second roughness; and the second roughness condition is that the average roughness of the sampling area in the finished slush skin is greater than the preset second roughness.

[0087] It can be understood that the three intervals corresponding to the preset first roughness Q1 and the preset second roughness Q2 correspond to three situations, respectively. The first interval is Q≤Q1, which corresponds to the case that the preparation accuracy of the modified PVC material is within the allowable range. The second interval is Q1<Q≤Q2, which corresponds to the case that the gas heating method is used in the heating process of the slush mold, and when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in that the temperature of the heating area is too high to cause part of the PVC slush powder to melt and be more easily adsorbed on the surface of the mold. The third interval is Q>Q2, which corresponds to the case that part of the PVC slush powder cannot be completely attached to the slush mold during preparation, resulting in that the surface of the finished slush skin is uneven. In practice, Q1 is generally selected in the range of [13μm, 17μm], and Q2 is generally selected in the range of [18μm, 22μm].

[0088] Preferably, the preferred embodiment of the preset first roughness Q1 is 15μm, and the preferred embodiment of the preset second roughness Q2 is 20μm.

[0089] Specifically, the average roughness of the sampling area in the finished slush skin is denoted as Q.

[0090] In implementation, the process of the present application determines the preparation accuracy of the modified PVC material by setting the preset first roughness and the preset second roughness, reduces the influence of inaccurate determination of the preparation accuracy of the modified PVC material on the environmental friendliness of the preparation of the modified PVC material, and further improves the preparation accuracy and environmental friendliness of the modified PVC.

[0091] Specifically, when the average roughness of the sampling area in the finished slush skin meets the trigger condition of determining the interval length between the heating time and the cooling time, the slush mold is heated and cooled according to the determined interval length.

[0092] The trigger condition is that the average roughness of the sampling area in the finished slush skin only meets the second roughness condition, and the interval length between the heating time and the cooling time is determined by the difference between the average roughness of the sampling area in the finished slush skin and the preset second roughness.

[0093] Specifically, the interval length between the heating time and the cooling time is reduced by the difference between the average roughness of the sampling area in the finished slush skin and the preset second roughness, and the calculation formula of the interval length between the heating time and the cooling time after reduction is:

[0094]

[0095] wherein V' is the interval length between the heating time and the cooling time after reduction, V is the interval length between the current heating time and the cooling time, A is the minimum unit roughness for adjusting the interval length between the heating time and the cooling time, and v is the interval length between the heating time and the cooling time when the average roughness of the sampling area in the finished slush skin is the minimum unit roughness.

[0096] In implementation, the value of A is generally 23-27 μm, and preferably, the preferred embodiment of A is 25 μm.

[0097] In implementation, the value of v can be selected in the range of [2 min, 4 min], and preferably, when the interval length between the heating time and the cooling time is greater than 3 min, it can cause the surface of the finished slush skin to be uneven, and therefore the preferred embodiment of v is 3 min.

[0098] For example, the PVC material is prepared by using a slush PVC skin preparation process based on modified PVC material, wherein V=4 min and Q=30 μm, and it is calculated that

[0099] In implementation, the process adjusts the interval length between the heating time and the cooling time by setting the preset first roughness and the preset second roughness. Since part of the PVC slush powder cannot be completely attached to the slush mold during preparation, the surface of the finished slush skin is uneven, thereby increasing the surface roughness of the finished slush skin. By shortening the interval length between the heating time and the cooling time, the temperature difference between the PVC slush powder and the mold and the stress generated by thermal expansion and contraction are reduced as much as possible, which helps to improve the adhesion, so that the slush skin is more closely attached to the surface of the mold, reduces the unevenness and roughness of the surface, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0100] Specifically, the calculation formula of the average roughness of the sampling area in the finished slush skin is:

[0101]

[0102] wherein G is the average roughness of the sampling region in the finished slush skin, K b is the roughness of the b-th sampling region in the finished slush skin, u is the number of sampling regions, and u is a natural number greater than or equal to 1.

[0103] Specifically, the step of determining the first overturning speed of the slush mold comprises:

[0104] The number of defective products in the finished slush skins and the total number of the finished slush skins in each preparation cycle are obtained respectively, and the proportion of the number of defective products in the finished slush skins is calculated.

[0105] The proportion of the number of defective products in the finished slush skins is compared with the preset first proportion and the preset second proportion respectively.

[0106] If the proportion of the number of defective products in the finished slush skins is greater than the preset first proportion, it is determined that the contact effectiveness of the PVC slush powder and the mold is lower than the allowable range.

[0107] If the proportion of the number of defective products in the finished slush skins is greater than the preset first proportion and less than or equal to the preset second proportion, the slush mold is controlled to overturn at the first overturning speed.

[0108] It can be understood that the three intervals corresponding to the preset first proportion P1 and the preset second proportion P2 correspond to three situations respectively. The first interval is P≤P1, which corresponds to the case that the contact effectiveness of the PVC slush powder and the mold is within the allowable range. The second interval is P1<P≤P2, which corresponds to the case that the gas heating method is used in the heating process of the slush mold, and when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, resulting in that the temperature of the heating area is too high to cause part of the PVC slush powder to melt and be more easily adsorbed on the surface of the mold. The third interval is P>P2, which corresponds to the case that the moving structure of the material bin is aged, so that the material bin cannot stop in time when reaching the target position, resulting in that part of the PVC slush powder leaks. In practice, P1 is generally selected in the range of [0.03, 0.05], and P2 is generally selected in the range of [0.05, 0.07].

[0109] Preferably, the preferred embodiment of the preset first proportion P1 is 0.04, and the preferred embodiment of the preset second proportion P2 is 0.06.

[0110] Specifically, the proportion of the number of defective products in the finished slush skins is denoted as P.

[0111] In the implementation, the process described in the application sets the preset first proportion and the preset second proportion. Since the proportion of the number of defective products in the finished slush skin can represent the contact effectiveness of the PVC slush powder and the mold, the secondary determination of the contact effectiveness of the PVC slush powder and the mold reduces the influence of the secondary determination of the contact effectiveness of the PVC slush powder and the mold on the preparation accuracy of the modified PVC material, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0112] Specifically, the first turning speed of the slush mold is determined by the difference between the proportion of the number of defective products in the finished slush skin and the preset first proportion.

[0113] Specifically, the turning speed of the slush mold is reduced by the difference between the proportion of the number of defective products in the finished slush skin and the preset first proportion. The calculation formula of the first turning speed of the slush mold after reduction is:

[0114]

[0115] Where H' is the first turning speed of the slush mold, H is the current turning speed of the slush mold, B is the minimum unit proportion for adjusting the turning speed of the slush mold, and h is the turning speed of the slush mold when the proportion of the number of defective products in the finished slush skin is the minimum unit proportion.

[0116] In the implementation, the value of B is generally 0.07-0.09, and preferably, the preferred embodiment of B is 0.08.

[0117] In the implementation, the value of h can be selected in the range of [25 revolutions / minute, 35 revolutions / minute], and preferably, when the turning speed of the slush mold is greater than 30 revolutions / minute, it may cause some PVC slush powder to melt and be more easily adsorbed on the surface of the mold. Therefore, the preferred embodiment of h is 30 revolutions / minute.

[0118] For example, the slush PVC skin preparation process based on the modified PVC material is used to prepare the PVC material, wherein H=35 revolutions / minute, P=0.08, and the calculation result is revolutions / minute.

[0119] In the implementation, the process disclosed by the application adjusts the overturning speed of the slush mold by setting the preset first proportion and the preset second proportion. Since the gas heating method is used in the heating process of the slush mold, when the heating temperature reaches the predetermined temperature, the heat is not easy to dissipate, which causes the temperature of the heating area to be too high, and part of the PVC slush powder melts and is more easily adsorbed on the surface of the mold, thereby causing the quality of the finished slush skin to be unstable and increasing the product rejection rate. By reducing the overturning speed of the slush mold, the temperature rising speed of the heating area can be slowed down, which helps to reduce the heat accumulation in the heating area, reduce the risk of local overheating, and help to ensure the uniformity and consistency of the slush skin, thereby improving the surface quality stability of the finished slush skin and further improving the preparation accuracy and environmental friendliness of the modified PVC.

[0120] Specifically, if the proportion of the number of defective products in the finished slush skin is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling of the material box and the slush mold is lower than the allowable range.

[0121] Specifically, the step of determining the running rate of the material box further includes a second determination of the effectiveness of the coupling of the material box and the slush mold based on the average weight of the plurality of finished slush skins.

[0122] If the average weight of the plurality of finished slush skins is greater than the preset weight, it is secondly determined that the effectiveness of the coupling of the material box and the slush mold is lower than the allowable range, and the material box is controlled to move at the running rate of the material box.

[0123] It can be understood that the two intervals corresponding to the preset weight Y0 correspond to two situations, respectively. The first interval is Y≤Y0, which corresponds to the case that the effectiveness of the coupling of the material box and the slush mold is within the allowable range. The second interval is Y>Y0, which corresponds to the case that the moving structure of the material box is aged, causing the material box to fail to stop in time when reaching the target position, thereby causing part of the PVC slush powder to leak out. In practice, Y0 is generally selected in the range of [0.3kg, 0.7kg].

[0124] Preferably, the preferred embodiment of the preset weight Y0 is Y0=0.5kg.

[0125] Specifically, the average weight of the plurality of finished slush skins is denoted as Y.

[0126] In the implementation, the process disclosed by the application secondly determines the effectiveness of the coupling of the material box and the slush mold by setting the preset weight, which reduces the influence of inaccurate second determination of the effectiveness of the coupling of the material box and the slush mold on the environmental friendliness of the preparation of the modified PVC material, and further improves the preparation accuracy and environmental friendliness of the modified PVC.

[0127] Specifically, the running rate of the hopper is determined by the difference between the average weight of the finished cast skin and the preset weight.

[0128] Specifically, the running rate of the hopper is reduced by the difference between the average weight of the finished cast skin and the preset weight, and the calculation formula of the reduced running rate of the hopper is:

[0129]

[0130] wherein L' is the reduced running rate of the hopper, L is the current running rate of the hopper, C is the minimum unit weight for adjusting the running rate of the hopper, and l is the running rate of the hopper when the average weight of the finished cast skin is the minimum unit weight.

[0131] In implementation, the value of C is generally 0.5kg-0.7kg, and preferably, the preferred embodiment of C is 0.6kg.

[0132] In implementation, the value of l can be selected in the range of [3kg / min, 5kg / min], and when the running rate of the hopper is greater than 4kg / min, some PVC cast powder may leak out, so the preferred embodiment of l is 4kg / min.

[0133] For example, using a cast PVC skin preparation process based on modified PVC material to prepare PVC material, wherein L=5kg / min, Y=0.8kg, and the calculation result is

[0134] In implementation, the process of the present application adjusts the running rate of the hopper by setting a preset weight. Due to material aging of the moving structure of the hopper, the hopper cannot stop in time when reaching the target position, resulting in deviation, so that the coupling with the cast mold cannot be tightly coupled, causing some PVC cast powder to leak out, reducing the weight of the finished cast skin. By reducing the moving speed of the hopper, the accuracy of the hopper movement is improved, so that the coupling is more tightly coupled, further improving the preparation accuracy and environmental protection of the modified PVC.

[0135] Specifically, the step of determining the second flipping speed of the cast mold comprises:

[0136] The thickness of the finished cast skin in a single running cycle is obtained, and the maximum thickness difference of the finished cast skin is calculated;

[0137] The maximum thickness difference of the finished cast skin is compared with a preset difference;

[0138] If the maximum thickness difference of the finished slush skin is greater than the preset difference, it is determined that the uniformity of the slush mold turning is lower than the allowable range, and the slush mold is turned according to the second turning speed.

[0139] It can be understood that the two intervals corresponding to the preset difference R0 correspond to two cases respectively. The first interval is R≤R0, which corresponds to the case that the uniformity of the slush mold turning is within the allowable range. The second interval is R>R0, which corresponds to the case that the turning speed is too slow, resulting in the thickness of the finished slush skin in a wave shape, and the thickness difference is too large. In practice, R0 is generally selected in the range of [4mm, 6mm].

[0140] Preferably, the preferred embodiment of the preset difference R0 is R0=5mm.

[0141] Specifically, the maximum thickness difference of the finished slush skin is denoted as R.

[0142] In implementation, the process of the present application determines the uniformity of the slush mold turning by setting the preset difference, which reduces the influence of the inaccurate determination of the uniformity of the slush mold turning on the preparation accuracy of the modified PVC material, and further improves the preparation accuracy and environmental protection of the modified PVC.

[0143] Specifically, the second turning speed of the slush mold is determined by the difference between the maximum thickness difference of the finished slush skin and the preset difference.

[0144] Specifically, the first turning speed of the slush mold is increased by the difference between the maximum thickness difference of the finished slush skin and the preset difference, and the calculation formula of the second turning speed of the slush mold after the increase is:

[0145]

[0146] Wherein, H" is the second turning speed of the slush mold, H' is the first turning speed of the slush mold, D is the minimum unit difference for adjusting the first turning speed of the slush mold, and h' is the first turning speed of the slush mold when the maximum thickness difference of the finished slush skin is the minimum unit difference.

[0147] In implementation, the value of D is generally 7mm-9mm, and preferably the preferred embodiment of D is 8mm.

[0148] In implementation, the value of h' can be selected in the range of [13rpm, 23rpm]. When the first turning speed of the slush mold is less than 18rpm, it may cause the thickness difference to be too large. Therefore, the preferred embodiment of h' is 18rpm.

[0149] For example, the PVC material is prepared by using a slush PVC skin preparation process based on a modified PVC material, wherein H'= 15 revolutions per minute and R = 9 mm, revolutions per minute.

[0150] In the implementation, the process described in the application adjusts the first turning speed of the slush mold by setting a preset difference amount. If the turning speed is too slow, the thickness of the finished slush skin will be wavy, resulting in a large thickness difference. By increasing the turning speed, the roughness of the slush skin is reduced, and the preparation accuracy and environmental protection of the modified PVC are further improved.

[0151] So far, 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 deviating from the principles of the application, and the technical solutions after these changes or replacements will fall within the protection scope of the application.

Claims

1. A process for preparing slush-molded PVC skin based on modified PVC material, characterized in that, Includes the following steps: The slush molding mold is heated, and a hopper containing PVC slush molding powder is transported to the bottom of the slush molding mold, and the hopper and the slush molding mold are connected and coupled. The coupled hopper and slush mold are flipped several times. After the excess PVC slush powder falls into the hopper, the hopper and slush mold are separated. After the slush mold is cooled, it is demolded to output the finished slush skin. The interval between heating and cooling times is determined based on the average roughness of the sampling area in the finished slush molding skin. Obtain the thickness of the finished slush molded surface after running a single cycle at the first flipping speed of the slush mold; The second turning speed is determined based on the maximum thickness difference of the finished slush-molded skin; Wherein, the first flipping speed is less than the second flipping speed; The interval between heating and cooling refers to the time between the start of heating and the start of cooling of the slush mold. The interval between heating and cooling times is reduced by the difference between the average roughness of the sampling area in the finished slush molding surface and the preset second roughness. The formula for calculating the reduced interval between heating and cooling times is as follows: ; Where V' is the reduced interval between heating and cooling times, V is the current interval between heating and cooling times, A is the minimum unit roughness for adjusting the interval between heating and cooling times, v is the interval between heating and cooling times when the average roughness of the sampling area in the finished slush-molded skin is the minimum unit roughness, the average roughness of the sampling area in the finished slush-molded skin is denoted as Q, and the preset second roughness is denoted as Q2.

2. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 1, characterized in that, Obtain the number of defective products and the total number of finished slush molded skins from several finished slush molded skins respectively; The first turning speed of the slush molding mold is determined based on the percentage of defective products in the finished slush molding skin. The turning speed of the slush molding mold is reduced by the difference between the percentage of defective products in the finished slush molding surface and a preset first percentage. The formula for calculating the first turning speed of the slush molding mold after the reduction is as follows: ; Where H' is the first turning speed of the slush mold, H is the current turning speed of the slush mold, B is the minimum unit percentage for adjusting the turning speed of the slush mold, h is the turning speed of the slush mold when the percentage of defective products in the finished slush molded skin is the minimum unit percentage, the percentage of defective products in the finished slush molded skin is denoted as P, and the preset first percentage is denoted as P1.

3. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 1, characterized in that, The running speed of the material box is determined based on the proportion of defective products in the finished slush molding skin and the average weight of several finished slush molding skins. The operating speed of the hopper is reduced by the difference between the average weight of several finished slush-molded skins and a preset weight. The formula for calculating the reduced operating speed of the hopper is as follows: ; Where L' is the reduced running speed of the hopper, L is the current running speed of the hopper, C is the minimum unit weight for adjusting the running speed of the hopper, l is the running speed of the hopper when the average weight of several finished slush-molded skins is the minimum unit weight, the average weight of several finished slush-molded skins is denoted as Y, and the preset weight is denoted as Y0.

4. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 1, characterized in that, The finished slush-molded skin is composed of the following components and parts by weight: 10 parts PVC base material, 3 parts plasticizer, 0.4 parts stabilizer, 0.2 parts colorant, 0.2 parts desiccant, and 0.05 parts internal release agent.

5. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 1, characterized in that, The step of determining the interval between the heating and cooling times also includes judging the preparation accuracy of the modified PVC material based on the average roughness of the sampling area in the finished slush plastic skin; If the average roughness of the sampling area in the finished PVC skin meets the first roughness condition or the second roughness condition, then the preparation accuracy of the modified PVC material is determined to be lower than the allowable range. When the average roughness of the sampling area in the finished slush molded skin meets the triggering condition for determining the interval between the heating and cooling times, the slush mold is heated and cooled according to the determined interval. The triggering condition is that the average roughness of the sampling area in the finished slush molding skin only meets the second roughness condition, and the interval between the heating time and the cooling time is determined by the difference between the average roughness of the sampling area in the finished slush molding skin and the preset second roughness.

6. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 5, characterized in that, The formula for calculating the average roughness of the sampling area in the finished slush-molded skin is as follows: ; Where G is the average roughness of the sampled area in the finished slush-molded skin, and K b Let be the roughness of the b-th sampling region in the finished slush molding skin, and u be the number of sampling regions, where u is a natural number greater than or equal to 1.

7. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 6, characterized in that, The first roughness condition is that the average roughness of the sampling area in the finished slush-molded skin is greater than a preset first roughness and less than or equal to a preset second roughness; the second roughness condition is that the average roughness of the sampling area in the finished slush-molded skin is greater than a preset second roughness.

8. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 7, characterized in that, The steps for determining the first flipping speed of the slush mold include: The number of defective products in several finished slush molding skins and the total number of finished slush molding skins in a single preparation cycle are obtained respectively, and the proportion of defective products in the finished slush molding skins is calculated. The percentage of defective products in the finished slush molding skin is compared with the preset first percentage and the preset second percentage, respectively. If the proportion of defective products in the finished slush molding surface is greater than the preset first proportion and less than or equal to the preset second proportion, then the slush molding mold is controlled to be flipped according to the first flipping speed.

9. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 8, characterized in that, The first flipping speed of the slush molding mold is determined by the difference between the percentage of defective products in the finished slush molding skin and a preset first percentage.

10. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 9, characterized in that, If the proportion of defective products in the finished slush molding skin is greater than the preset second proportion, it is preliminarily determined that the effectiveness of the coupling between the material box and the slush molding mold is lower than the allowable range.

11. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 10, characterized in that, The step of determining the running speed of the material box further includes a secondary determination of the effectiveness of the coupling between the material box and the slush molding mold based on the average weight of the several finished slush molding skins. If the average weight of the several finished slush molded skins is greater than the preset weight, the effectiveness of the coupling between the material box and the slush mold is determined to be lower than the allowable range, and the material box is controlled to move according to the running speed of the material box. The running speed of the material box is determined by the difference between the average weight of several finished slush plastic skins and a preset weight.

12. The process for preparing slush-molded PVC skin based on modified PVC material according to claim 11, characterized in that, The step of determining the second flipping speed of the slush mold includes: The thickness of the finished slush molding skin within a single operating cycle is obtained, and the maximum thickness difference of the finished slush molding skin is calculated. The maximum thickness difference of the finished slush-molded skin is compared with the preset difference. If the maximum thickness difference of the finished slush molded skin is greater than the preset difference, then the slush mold is controlled to be flipped according to the second flipping speed; The second flipping speed of the slush mold is determined by the difference between the maximum thickness difference of the finished slush skin and a preset difference.

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