CN109797606B - Method for compensating shrinkage coefficients of different parts of same product in pulp molding - Google Patents
Method for compensating shrinkage coefficients of different parts of same product in pulp molding Download PDFInfo
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Abstract
The invention discloses a method for compensating the shrinkage coefficients of different parts of the same product molded by paper pulp, wherein corresponding moulds are designed according to the product, the size of a forming mould is enlarged relative to the size of the final product, and the shrinkage coefficients of structures with different shapes are different at different positions of a mould cavity of the forming mould; the cavity shape, the cavity size and the cavity height are different, and the contraction coefficients are different. The invention ensures that the size of the product after shrinkage is matched with the size of the sizing die, reduces the phenomena of tension cracking and wrinkling of the product and improves the quality and the qualification rate of the product.
Description
Technical Field
The invention relates to the field of paper-plastic products, in particular to a method for compensating shrinkage coefficients of different parts of the same product in paper pulp molding.
Background
Pulp molding is a three-dimensional papermaking technique. It uses waste paper as raw material, and uses a special mould to mould a paper product with a certain form on the moulding machine. The pulp molding product is a novel packaging material which is rapid in recent years and is an excellent substitute for wood. The paper pulp molding product adopts: the manufacturing process comprises the steps of raw material pulping, proportioning, compression molding, drying and shaping.
Since a large amount of water remains on the workpiece after the press molding, and the water content of the final product is less than 10%, the water which is about half of the weight of the workpiece is removed in the drying process of the workpiece, and the water is removed into steam by heat absorption. The shrinkage ratio, i.e. the shrinkage coefficient (the ratio of the size of the forming die to the size of the final product) is mainly because the moisture content of the formed wet blank is about 70%, the wet blank is dried at a temperature of about 150 ℃ until the moisture content is less than 10%, and then the wet blank is shaped into the final product through a shaping die. During the drying process, water is evaporated, the fiber shrinks, and the overall size of the product shrinks less. However, the size of some position and shape structures is reduced in the drying process, and the size of some position and shape structures is greatly reduced. After being dried, the position and shape structure with small shrinkage has a size larger than the final size requirement, and is easy to generate wrinkles during shaping, and after being dried, the position and shape structure with large shrinkage has a size smaller than the final size requirement, and is easy to generate tension cracking during shaping; the wrinkles and the tensile cracks are waste products, and the qualification rate is reduced.
In the traditional paper pulp molding mold design process, particularly for products with complex structures, the mold cavities of the mold are designed to have the same shrinkage coefficient, so that the shrinkage of parts and shapes and sizes of the dried products is too large or too small, and then the products produced after shaping by a shaping mold have serious wrinkles and tensile cracks and low product percent of pass.
In addition, in the actual production process, sampling is often required, that is, whether a part of samples to be produced meet requirements is confirmed by a customer, but the sampling generally corresponds to a plurality of schemes, and the schemes correspond to a plurality of sets of dies, each set of die corresponds to at least 3 production dies, such as a slurry suction die, an extrusion die, a hot pressing upper die, a hot pressing lower die and a transfer die, each sample production process requires a large amount of time, and the manufacturing and production cost is increased.
Therefore, it is necessary to provide a method for compensating the shrinkage coefficients of different parts of the same product molded by pulp and a method for rapidly sampling the same product to solve the above problems.
Disclosure of Invention
The invention aims to provide a method for compensating shrinkage coefficients of different mold cavities of the same product of pulp molding and a method for rapidly sampling, wherein when the pulp molding mold is designed, the shrinkage ratios of different mold cavity designs are different, so that the size of the product after shrinkage is matched with the size of a sizing die, the phenomena of wrinkling and stretch cracking of the product are reduced, and the quality and the qualification rate of the product are improved; in addition, a method for fast sampling is provided to solve the problems in the background art.
Research finds that in order to ensure that the dried product conforms to the size of the final product, the size of the forming die needs to be enlarged, and the size of the forming die is 1.03 times of the size of the final product. However, as the quality requirement of the product is improved, the wet embryo is not shrunk to 1.0 in all positions and shapes and structural sizes after being dried if the whole size of the forming die is enlarged by 1.03 times. That is, the size of some position and shape structure is reduced in the drying process, and the size of some position and shape structure is greatly reduced. After being dried, the position and shape structure with small shrinkage has a size larger than the final size requirement, and is easy to generate wrinkles during shaping, and after being dried, the position and shape structure with large shrinkage has a size smaller than the final size requirement, and is easy to generate tension cracking during shaping; the wrinkles and the tensile cracks are waste products, and the qualification rate is reduced. Therefore, different shrinkage ratios are determined according to different positions and structures with different shapes, and forming dies are manufactured, wherein the shrinkage ratios are different, such as planes, side faces, cavity shapes, cavity sizes and cavity heights, so that the sizes are consistent with requirements after drying and shaping, and tensile cracks and wrinkles are avoided.
In order to achieve the purpose, the invention provides the following technical scheme: a method for compensating the shrinkage coefficients of different parts of the same product molded by paper pulp comprises the following steps:
(1) designing a mould, namely designing a corresponding mould according to a product, and enlarging the size of a forming mould relative to the size of a final product;
(2) pouring the pulp paste into a forming die, and performing die pressing operation to obtain a wet blank;
(3) and drying the wet blank, and shaping by a shaping die to obtain a final product.
The shrinkage coefficient of the forming die in the step (1) is 1.025-1.035, the shrinkage coefficient is the ratio of the size of the forming die to the size of the final product, and the enlarged size of the forming die is 1.025-1.035 times of the size of the final product.
Furthermore, the shrinkage coefficients of structures with different shapes are different at different positions of the forming die cavity; the cavity shape, the cavity size and the cavity height are different, and the contraction coefficients are different; for example, the flat face is typically provided with a shrinkage factor of 1.03, the side faces are typically provided with a shrinkage factor of 1.025-1.03, and the corners of the cavity or further cavities in the cavity are typically provided with a shrinkage factor of 1.03-1.035.
In the step (3), the wet embryo is dried until the moisture content of the wet embryo is about 70 percent, and the wet embryo is dried at the temperature of 140-.
The size of the sizing die is consistent with the required size of the product.
Further, the pulp paste was prepared by the following steps:
selecting paperboard, waste paper box paper, waste white edge paper and the like, and putting the paperboard, the waste paper box paper, the waste white edge paper and the like into a crusher for crushing to obtain a mixed material;
after the mixed material is subjected to sand removal operation, grinding the mixed material to obtain paper pulp fibers;
preparing a plurality of binders, auxiliaries and water, and mixing according to a weight ratio of 8:1:8 to obtain a mixed material;
adding the paper pulp fibers and the mixed materials into a stirrer according to the weight ratio of 3:1, and stirring to obtain a paste;
preferably, the rotating speed of the pulverizer is 100-180 r/min;
preferably, the grinding mesh number of the mixed material is 120-160 meshes;
preferably, the binder is one or a mixture of more than one of acrylic acid, polyurethane and organosilicon;
preferably, the forming die is a die cavity with a complex structure, the number of the die cavities is multiple, the shapes of the die cavities are multiple, and the shrinkage coefficients are different.
Preferably, the number of the forming die cavities is eighteen, the shrinkage ratios of the molded products in eighteen die cavities are different, and the shrinkage ratio ranges from 1.025 to 1.035.
The invention also claims a method for rapidly sampling the pulp molding, which is shown in figure 2 and comprises a pulp molding rapid sampling mold, wherein the mold comprises a hot-pressing upper mold and a hot-pressing lower mold, the hot-pressing lower mold comprises a lower mold plate and a pulp sucking and heating mold plate detachably connected with the upper surface of the lower mold plate, and the pulp sucking and heating mold plate is designed by a method for compensating shrinkage coefficients of different parts of the same product molded by the pulp. The slurry sucking and heating template is movably and slidably connected or detachably connected with the lower template, so that only the upper heating template and the corresponding slurry sucking and heating template need to be replaced when different mold shapes are replaced.
Referring to fig. 2, the method for rapid sample extraction specifically includes:
(1) designing a pulp sucking and heating template by the method for compensating the shrinkage coefficients of different parts of the same product molded by the paper pulp;
(2) heating the template to suck the slurry by using the slurry;
(3) pushing the slurry sucking heating template after slurry sucking into a lower template, wherein the lower template and the slurry sucking heating template detachably connected with the upper surface of the lower template form a hot-pressing lower die;
(4) performing vacuum pumping and then die assembly;
(5) opening the mold and taking out the product;
(6) and drying the wet blank, and shaping by a shaping die to obtain a final product.
The invention discloses a slurry suction heating mould, which changes a slurry suction mode through design, adopts a male mould to suck slurry in the prior art, and adopts a female mould to suck slurry and directly uses the slurry suction heating mould of a female mould structure as a part of a hot-pressing lower mould.
The shrinkage coefficient of the pulp sucking and heating template in the step (1) is 1.025-1.035; the shrinkage coefficients of structures with different shapes are different at different positions of the die cavity of the slurry sucking and heating die plate; the cavity shape, the cavity size and the cavity height are different, and the contraction coefficients are different; for example, the flat face is typically provided with a shrinkage factor of 1.03, the side faces are typically provided with a shrinkage factor of 1.025-1.03, and the corners of the cavity or further cavities in the cavity are typically provided with a shrinkage factor of 1.03-1.035.
The invention has the technical effects and advantages that:
1. when the pulp mould is designed, the shrinkage coefficients of mould cavities at different positions and in different shapes are different, so that the size of a product after shrinkage is matched with the size of a sizing mould, the phenomena of tension cracking and wrinkling of the product are reduced, and the quality and the qualification rate of the product are improved;
2. the improvement of the mould structure greatly shortens the sampling time of a molded product, and can be quickly completed by only using two moulds on the mould manufacturing cost, thereby greatly improving the operation efficiency. The existing design mode is as follows: the sample outlet mould with ordinary speed needs 5 moulds of a slurry suction mould, an extrusion mould, a hot-pressing upper mould, a hot-pressing lower mould and a transfer mould, when each mould is used in the links of mould design, mould manufacture, mould transportation, assembly and Cutting/OQC, 2d, 5d, 1d and 0.5d are shared for 9.5d, a second medium-speed sample outlet mould needs a slurry suction mould, a hot-pressing upper mould and a hot-pressing lower mould for 3 moulds, when each mould is used for 1d, 3.5d, 1d and 0.5d and used for 7d respectively in the links of mould design, mould manufacture, mould transportation, assembly and Cutting/OQC, and the improved hot-pressing upper die is used, the hot-pressing lower die is respectively 1d, 2d, 1d and 0.5d when used in the links, and the total time is 5.5d, compared with the method, the whole use time of the method for quickly stripping the die is obviously reduced, and the corresponding cost is reduced by 40 percent.
Drawings
FIG. 1 is a schematic view of a mold cavity of a forming mold of the present invention;
reference numerals: 1 forming a die and 2 forming a cavity;
fig. 2 is a schematic flow chart of the rapid sample discharging method of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A technical method for compensating different cavity shrinkage coefficients of the same product molded by paper pulp specifically comprises the following steps:
firstly, selecting paperboard, waste paper box paper, waste white edge paper and the like, and putting the paperboard, the waste paper box paper, the waste white edge paper and the like into a crusher with the rotation speed of 100-;
step two, after the mixed material is subjected to sand removal operation, grinding the mixed material, wherein the grinding mesh number is 120-160 meshes, and obtaining paper pulp fibers;
step three, preparing a plurality of binders, auxiliaries and water, and mixing according to a weight ratio of 8:1:8 to obtain a mixed material; the binder is one or a mixture of more than one of acrylic acid, polyurethane and organic silicon;
step four, adding the paper pulp fibers and the mixed materials into a stirrer according to the weight ratio of 3:1, and stirring to obtain a paste;
step five, designing a mould, wherein the shrinkage coefficient of a forming mould is 1.025-1.035, the plane shrinkage coefficient is set to be 1.03, the side shrinkage coefficient is set to be 1.025-1.03, and the shrinkage coefficient of the corner of the mould cavity or the further cavity in the mould cavity is set to be 1.03-1.035 as the shrinkage coefficient of the cavity 2 in the figure 1, so that the size of the product after shrinkage is matched with the size of the shaping mould;
pouring the pulp paste into the interior of the mold designed in the fifth step, performing mold pressing operation, and forming to obtain a wet blank;
and step seven, drying the wet blank with the water content of about 70% at the temperature of 140-.
Example 2
As shown in fig. 1, in the present embodiment, the forming die 1 is provided with cavities 2, which have eighteen cavities 2 in total, wherein the plane shrinkage coefficient is set to 1.03, the side shrinkage coefficient is set to 1.025, and the shrinkage coefficients of the cavity corners and the cavities 2 in the cavity are set to 1.035, so as to ensure that the size of the product after shrinkage is matched with the size of the forming die, reduce the phenomena of pulling crack and wrinkle of the product, and improve the quality and the qualification rate of the product;
when the concrete production is carried out, the method comprises the following steps of firstly, selecting paperboard, waste paper box paper, waste white edge paper and the like, placing the paperboard, the waste paper box paper, the waste white edge paper and the like into a crusher with the rotating speed of 100 revolutions per minute for crushing to obtain a mixed material, and secondly, after the sand removal operation is carried out on the mixed material, grinding the mixed material with the grinding mesh number of 120 meshes to obtain paper pulp fibers; step three, mixing acrylic acid, an auxiliary agent and water according to a weight ratio of 8:1:8 to obtain a mixed material; step four, adding the paper pulp fibers and the mixed materials into a stirrer according to the weight ratio of 3:1, and stirring to obtain a paste; step five, designing a mold to ensure that the size of the product after shrinkage is matched with the size of the sizing die; and step seven, drying the wet blank with the water content of about 70% at the temperature of 150 ℃ until the water content is less than 10%, and shaping the wet blank into a final product through a shaping die.
The product has no phenomena of pulling crack and wrinkle.
Example 3
The method of designing the suction heating template and the preparation of the pulp paste were the same as in example 2.
Referring to fig. 2, the method for rapid sample extraction specifically includes:
(1) designing a pulp sucking and heating template by the method for compensating the shrinkage coefficients of different parts of the same product molded by the paper pulp;
(2) heating the template to suck the slurry by using the slurry;
(3) pushing the slurry sucking heating template after slurry sucking into a lower template, wherein the lower template and the slurry sucking heating template detachably connected with the upper surface of the lower template form a hot-pressing lower die;
(4) performing vacuum pumping and then die assembly;
(5) opening the mold and taking out the product;
(6) and drying the wet blank at the temperature of 180 ℃ until the water content is less than 10%, and shaping the wet blank by a shaping die to obtain a final product.
The product has no phenomena of pulling crack and wrinkle; the time spent in the links of mold design, mold manufacturing, mold conveying, assembly and Cutting/OQC are respectively 1d, 2d, 1d and 0.5d, and the time spent in the links is 5.5 d.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.
Claims (7)
1. A method for compensating the shrinkage coefficients of different parts of the same product molded by paper pulp comprises the following steps:
(1) designing a mould, namely designing a corresponding mould according to a product, and enlarging the size of a forming mould relative to the size of a final product;
(2) pouring the pulp paste into a forming die, and performing die pressing operation to obtain a wet blank;
the manufacturing method of the pulp paste comprises the following steps: selecting paperboard, waste paper box paper and waste white edge paper, placing the paperboard, the waste paper box paper and the waste white edge paper in a crusher at the rotating speed of 100-180 revolutions per minute for crushing to obtain a mixed material, and grinding the mixed material after sand removal operation is carried out on the mixed material to obtain paper pulp fibers; preparing a plurality of binders, auxiliaries and water, and mixing according to a weight ratio of 8:1:8 to obtain a mixed material; the binder is one or a mixture of more than one of acrylic acid, polyurethane and organic silicon; adding the paper pulp fibers and the mixed materials into a stirrer according to the weight ratio of 3:1, and stirring to obtain paper pulp paste;
(3) drying the wet blank, and shaping the wet blank into a final product through a shaping die;
the shrinkage coefficient of the forming die in the step (1) is 1.025-1.035; shrinkage coefficients of structures with different shapes are different at different positions of a forming die cavity; the cavity shape, the cavity size and the cavity height are different, and the contraction coefficients are different; wherein the plane is typically given a shrinkage factor of 1.03, the side faces are typically given a shrinkage factor of 1.025-1.03, and the corners of the mould cavity or further cavities in the mould cavity are typically given a shrinkage factor of 1.03-1.035.
2. The method of claim 1, wherein: and (3) drying the wet embryo until the moisture content of the wet embryo is about 70 percent and drying the wet embryo at the temperature of 140 ℃ and 180 ℃ until the moisture content is less than 10 percent.
3. The method of claim 2, wherein: the wet embryo moisture content is about 70 percent, and the wet embryo moisture content is dried at the temperature of 150 ℃ until the moisture content is less than 10 percent.
4. The method of claim 1, wherein: in the step (3), the size of the sizing die is consistent with the required size of the product.
5. The method according to any one of claims 1-4, wherein: the molding die has a cavity of a complicated structure.
6. The utility model provides a method of pulp molding is appearance out fast, uses pulp molding to go out appearance mould appearance fast, the mould includes hot pressing mould and hot pressing lower mould, and the hot pressing lower mould has lower bolster and the thick liquid heating template of inhaling that can dismantle the connection with the lower bolster upper surface, its characterized in that: the pulp sucking and heating template is designed by a method for compensating the shrinkage coefficient of different parts of the same pulp molded product according to any one of claims 1 to 5.
7. The method according to claim 5, characterized in that it comprises in particular the steps of:
(1) designing a slurry sucking and heating template by a compensation method;
(2) heating the template to suck the slurry by using the slurry;
(3) pushing the slurry sucking heating template after slurry sucking into a lower template, wherein the lower template and the slurry sucking heating template detachably connected with the upper surface of the lower template form a hot-pressing lower die;
(4) performing vacuum pumping and then die assembly;
(5) opening the mold and taking out the product;
(6) and drying the wet blank, and shaping by a shaping die to obtain a final product.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3755911A (en) * | 1962-08-27 | 1973-09-04 | R Candor | Liquid removing apparatus and method |
| CN2495681Y (en) * | 2001-06-13 | 2002-06-19 | 谭延笑 | Single formation and wet-pressing drying type fibre pulp moulding machine |
| CN109235146A (en) * | 2018-09-07 | 2019-01-18 | 青岛永发模塑有限公司 | A kind of method and molding die for eliminating paper pulp moulding product bending cracking |
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2019
- 2019-04-10 CN CN201910286426.0A patent/CN109797606B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3755911A (en) * | 1962-08-27 | 1973-09-04 | R Candor | Liquid removing apparatus and method |
| CN2495681Y (en) * | 2001-06-13 | 2002-06-19 | 谭延笑 | Single formation and wet-pressing drying type fibre pulp moulding machine |
| CN109235146A (en) * | 2018-09-07 | 2019-01-18 | 青岛永发模塑有限公司 | A kind of method and molding die for eliminating paper pulp moulding product bending cracking |
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