Abstract This paper introduces the composition and principle of the module of brittle-value solution, buffer design, corrugated paper box design and carton structure optimization design of transport packaging CAD system.
The traditional packaging and transportation design is based on the fragility of the product obtained from the experiment, the design of cushion liners, packaging containers and the optimization of the carton structure, and the verification and long-term practice tests. The final product can get the ideal packaging. The traditional method of transport packaging design has a long period of history. It is necessary to test the product directly to determine the fragility of the product, but also to use the practice test, so it will cause product waste; it will also easily lead to overpacking of the product, resulting in waste of packaging materials. Can we use a certain theory, methods and techniques to complete this design process by means of a computer, know the product and circulation conditions, directly solve the product's fragile value and design a cushioning liner and packaging container that meets the requirements and economic feasibility. The transport packaging CAD system that the author has to discuss can achieve this requirement. The introduction is as follows.
First, the composition of the software system
The transport packaging CAD system is mainly composed of four modules: the product fragility value solving module, the buffer design and verification module, the carton structural design and verification module, the carton structural optimization design module and the transport packaging design solution output module. Each module type completes certain functions independently, but restricts each other and depends on each other to complete the design task of product transport packaging. The relationship between its parts is shown in Figure 1.
Second, software module function and its realization
1, product fragility solution module
The main function of this module is to start from the known parameters (size, elastic modulus E, Poisson's ratio λ, density Ï, damping coefficient γ, etc.) of the product, simulate the test conditions, and use the computer to directly solve the product's fragility.
The traditional methods for determining brittleness include: impact test method and buffer drop test method. All of them are the product's fragile value when the product is subjected to a certain transient impact until the product is damaged and the use value is lost, and the measured data is processed. The software simulation test to solve the fragility of the product mainly solves the following problems:
(1) Analyze the structural characteristics of the product and disassemble the product into several sub-structures according to certain principles. Using the finite element method to analyze each sub-structure and establish their models.
(2) Using the dynamic structure method, by means of the continuity condition of the displacement of the joints, the sub-structures are combined and the system equations are established.
(3) Through investigation, analysis and research work on a large number of product damage accidents, find common product damaged parts, classify them, conduct vulnerability analysis on them, and establish conditions for determining various types of component damage.
(4) Simulated test conditions apply shock excitation to the product.
(5) Using the mode superposition method to solve the system equations, the response of the node at each vulnerable component of the product to the excitation is obtained, and the damage is judged.
(6) If there is no breakage of the fragile parts, increase the impact excitation by a percentage of a certain size, and repeat the above process until the damage of one part is just generated, then use the ratio of the size of the previous impact excitation and the gravity acceleration as The value of the product is fragile; if a component is damaged and the first time the excitation is applied, the excitation is reduced by a large proportion until no component is damaged, and then the process of repeating the above is repeated; if it is not the first time, the product may be directly called for assistance. The crisp value. The analysis chart is shown in Figure 2.
2, buffer design and check module
The main function of this module is to find the economic material that meets the requirements from a number of buffer materials by the crispness of the product and the stress characteristics in circulation.
The cushioning cushion design method includes a cushion factor, a maximum static stress (c-σm) method, and a cushion coefficient-strain curve (c-ε) method. The system uses the c-σm curve method as an example.
Known: product crispness G, product quality M, product length l wide w high h, seeking the most economical buffer material and its size.
Solution process:
(1) The drop height H is obtained from the circulation condition database according to the circulation conditions.
(2) Obtain the minimum buffer coefficient C and the corresponding static stress σ for each suitable buffer material from the buffer material database.
(3) The bearing area A of each cushion pad is obtained by the formula A = W · C/σ. This area should be smaller than the minimum bearing area of ​​the product, otherwise the buffer material is eliminated and the material with larger δ is selected. Again, the thickness t of each cushion pad is given by the formula t=C*H/G.
(4) Check the deflection so that A/(1.33t)^2>1. Otherwise t takes a small increase A.
(5) Check the angle drop and increase l, w and h respectively by 2t, making 3(l·w·h)/(l^2+w^2+h^2)^1/2>1·w . Otherwise cancel the material.
(6) Anti-vibration check. The initial elastic modulus E, the bearing area A, the gravitational acceleration g, the weight W, and the thickness t from each cushion pad are given by the formula f=(E·A·g/(W·t))^1/2·1/2π The natural frequency f of the cushion liner can be obtained, and the maximum transfer rate Tm of each buffer material can be obtained from f (which can be obtained from the buffer material database). The acceleration of the product, p=Tm·a, can be obtained from the vibrational acceleration a in circulation. To make pGg, otherwise increase A, t take small, continue to check until satisfied.
(7) The area A and thickness t of the desired cushioning pad, and the price of the material obtained from the buffering material database, can be found among the most economical among the buffering materials satisfying the above requirements.
The last module transmits the inner dimensions (l+2t)*(w+2t)*(h+2t) to the carton structural design and checkout module or output.
3, carton structure design and calibration module
Corrugated box formulas include Kellicutt, Maltenfort, Wolf, Makee, and others. The system uses the Kellicutt formula.
It is known that the height H, the storage time T, and the type and composition of the corrugated paper are obtained from the circulation condition database.
Solution process:
(1) The compressive strength P (kgf) that the carton should have is given by the formula P=kW(Hh)/h. In the formula: k is the safety factor, which can be obtained from the circulation condition database according to the storage environment and the storage period T. W is the gross weight of the product. h is the height of the package.
(2) From the formula P=2.54Px*F, the total ring crush strength Px (kgf/cm) of corrugated paper per centimeter can be obtained. Where F=(4·aX2/Z)^2/3·Z·J, Z is the perimeter of the carton, aX2 is the corrugation constant, and J is the carton constant. Different types of 楞 have different aX2 and J, which can be from the corrugation parameters Get in the database.
(3) According to the formula Px=(ΣRn+ΣCi·Rm)/L, the actual ring pressure strength Px of the corrugated cardboard can be obtained. Where: Rn is the ring pressure strength of carton paper, paper or sandwich jam, Ci is the shrinkage of corrugated fiber, Rm is the ring pressure strength of corrugated medium paper, and L is the length of ring pressure test. The standard is 6 inches. These parameters can be obtained from the corrugated parameter database, and the corrugated parameter database also contains the corresponding corrugated box composition and type. As a result, the corrugated board has a composite ring pressure strength and the corrugated board composition and shape are obtained.
(4) Check the compressive strength of the carton. The compressive strength of the actual board obtained in (3) is brought into the Kellicutt formula, and the compressive strength of the corrugated box obtained should be greater than that in (1).
(5) Carton side pressure strength check. Carton compressive strength P in (1) and (4) is brought into the formula ECT=P/2(l+w), and (4) should be greater than (1). Of course, (4) establishment (4) also holds.
This module can select the most ideal and most economical from the carton market price obtained from the corrugated paper box database from many suitable solutions, and the corresponding box map and size can be retrieved from the corrugated paper box database and can be output by the output module.
4, carton structure optimization design module. The objective function for optimizing the design is:
F=(K1S+K2V1/RV2)/N
In the formula, F - the sum of the cost of the packaging carton and the transportation cost of each item; K1 - the unit price of the corrugated box used (RMB/m); S - the area of ​​the single corrugated box used (m); K2 --Ration rates of used containers from start to finish (RMB/container); Volume of V1-- single corrugated boxes (m); Volume of V2-- containers (m); Space utilization of corrugated boxes inside R--containers ;N--the number of items in a single carton. The independent variables of the objective function are determined by the contents and arrangement of the contents in the carton, the box type, and the container type of the carton in the container. These parameters can be obtained from the corrugated box parameter database and the container parameter database.
Constraints are restrictions that are established to obtain a viable design plan, such as restrictions on the dimensions of the carton in terms of market, circulation, or ergonomics; requirements for carton cutting at the time of processing.
From all the reasonable cartons that meet the strength requirements found in the carton structural design module, find the value of the independent variable when the objective function satisfies the optimal value obtained under the constraint conditions, so as to find the corrugated cartons with the lowest carton costs and transport costs. The box type and its size.
5, other modules and their database and software environment
The output module of the packaging scheme can output one or all of the results of the product crisp value calculation module, buffer design and verification module, carton structural design and verification module, and carton structural optimization design according to the user's requirements.
The programming language used by this software is VC and its database development system. VC is based on the C + + language, easy to use and flexible, the development of visual programming software for Windows applications. Its database development system uses ODBC to successfully combine the flexibility of C++ with the efficient security of the database. Combined with its visual programming features, it provides a good interface for programmers to develop databases.
Third, the use of software and overall structure
In order to design the product for transportation and packaging and to obtain data from the database, the parameters that should be entered when the software is used are: (1) product parameters; (2) circulation condition codes. Based on the above analysis, the overall block diagram of each part of the software is shown in Figure 3.
Fourth, the conclusion
The software starts from the product itself, and in the case of inputting various parameters, the product buffer design scheme is directly derived. It changed the traditional packaging design process, saved costs, increased efficiency, and has great application prospects.
The traditional packaging and transportation design is based on the fragility of the product obtained from the experiment, the design of cushion liners, packaging containers and the optimization of the carton structure, and the verification and long-term practice tests. The final product can get the ideal packaging. The traditional method of transport packaging design has a long period of history. It is necessary to test the product directly to determine the fragility of the product, but also to use the practice test, so it will cause product waste; it will also easily lead to overpacking of the product, resulting in waste of packaging materials. Can we use a certain theory, methods and techniques to complete this design process by means of a computer, know the product and circulation conditions, directly solve the product's fragile value and design a cushioning liner and packaging container that meets the requirements and economic feasibility. The transport packaging CAD system that the author has to discuss can achieve this requirement. The introduction is as follows.
First, the composition of the software system
The transport packaging CAD system is mainly composed of four modules: the product fragility value solving module, the buffer design and verification module, the carton structural design and verification module, the carton structural optimization design module and the transport packaging design solution output module. Each module type completes certain functions independently, but restricts each other and depends on each other to complete the design task of product transport packaging. The relationship between its parts is shown in Figure 1.
Second, software module function and its realization
1, product fragility solution module
The main function of this module is to start from the known parameters (size, elastic modulus E, Poisson's ratio λ, density Ï, damping coefficient γ, etc.) of the product, simulate the test conditions, and use the computer to directly solve the product's fragility.
The traditional methods for determining brittleness include: impact test method and buffer drop test method. All of them are the product's fragile value when the product is subjected to a certain transient impact until the product is damaged and the use value is lost, and the measured data is processed. The software simulation test to solve the fragility of the product mainly solves the following problems:
(1) Analyze the structural characteristics of the product and disassemble the product into several sub-structures according to certain principles. Using the finite element method to analyze each sub-structure and establish their models.
(2) Using the dynamic structure method, by means of the continuity condition of the displacement of the joints, the sub-structures are combined and the system equations are established.
(3) Through investigation, analysis and research work on a large number of product damage accidents, find common product damaged parts, classify them, conduct vulnerability analysis on them, and establish conditions for determining various types of component damage.
(4) Simulated test conditions apply shock excitation to the product.
(5) Using the mode superposition method to solve the system equations, the response of the node at each vulnerable component of the product to the excitation is obtained, and the damage is judged.
(6) If there is no breakage of the fragile parts, increase the impact excitation by a percentage of a certain size, and repeat the above process until the damage of one part is just generated, then use the ratio of the size of the previous impact excitation and the gravity acceleration as The value of the product is fragile; if a component is damaged and the first time the excitation is applied, the excitation is reduced by a large proportion until no component is damaged, and then the process of repeating the above is repeated; if it is not the first time, the product may be directly called for assistance. The crisp value. The analysis chart is shown in Figure 2.
2, buffer design and check module
The main function of this module is to find the economic material that meets the requirements from a number of buffer materials by the crispness of the product and the stress characteristics in circulation.
The cushioning cushion design method includes a cushion factor, a maximum static stress (c-σm) method, and a cushion coefficient-strain curve (c-ε) method. The system uses the c-σm curve method as an example.
Known: product crispness G, product quality M, product length l wide w high h, seeking the most economical buffer material and its size.
Solution process:
(1) The drop height H is obtained from the circulation condition database according to the circulation conditions.
(2) Obtain the minimum buffer coefficient C and the corresponding static stress σ for each suitable buffer material from the buffer material database.
(3) The bearing area A of each cushion pad is obtained by the formula A = W · C/σ. This area should be smaller than the minimum bearing area of ​​the product, otherwise the buffer material is eliminated and the material with larger δ is selected. Again, the thickness t of each cushion pad is given by the formula t=C*H/G.
(4) Check the deflection so that A/(1.33t)^2>1. Otherwise t takes a small increase A.
(5) Check the angle drop and increase l, w and h respectively by 2t, making 3(l·w·h)/(l^2+w^2+h^2)^1/2>1·w . Otherwise cancel the material.
(6) Anti-vibration check. The initial elastic modulus E, the bearing area A, the gravitational acceleration g, the weight W, and the thickness t from each cushion pad are given by the formula f=(E·A·g/(W·t))^1/2·1/2π The natural frequency f of the cushion liner can be obtained, and the maximum transfer rate Tm of each buffer material can be obtained from f (which can be obtained from the buffer material database). The acceleration of the product, p=Tm·a, can be obtained from the vibrational acceleration a in circulation. To make pGg, otherwise increase A, t take small, continue to check until satisfied.
(7) The area A and thickness t of the desired cushioning pad, and the price of the material obtained from the buffering material database, can be found among the most economical among the buffering materials satisfying the above requirements.
The last module transmits the inner dimensions (l+2t)*(w+2t)*(h+2t) to the carton structural design and checkout module or output.
3, carton structure design and calibration module
Corrugated box formulas include Kellicutt, Maltenfort, Wolf, Makee, and others. The system uses the Kellicutt formula.
It is known that the height H, the storage time T, and the type and composition of the corrugated paper are obtained from the circulation condition database.
Solution process:
(1) The compressive strength P (kgf) that the carton should have is given by the formula P=kW(Hh)/h. In the formula: k is the safety factor, which can be obtained from the circulation condition database according to the storage environment and the storage period T. W is the gross weight of the product. h is the height of the package.
(2) From the formula P=2.54Px*F, the total ring crush strength Px (kgf/cm) of corrugated paper per centimeter can be obtained. Where F=(4·aX2/Z)^2/3·Z·J, Z is the perimeter of the carton, aX2 is the corrugation constant, and J is the carton constant. Different types of 楞 have different aX2 and J, which can be from the corrugation parameters Get in the database.
(3) According to the formula Px=(ΣRn+ΣCi·Rm)/L, the actual ring pressure strength Px of the corrugated cardboard can be obtained. Where: Rn is the ring pressure strength of carton paper, paper or sandwich jam, Ci is the shrinkage of corrugated fiber, Rm is the ring pressure strength of corrugated medium paper, and L is the length of ring pressure test. The standard is 6 inches. These parameters can be obtained from the corrugated parameter database, and the corrugated parameter database also contains the corresponding corrugated box composition and type. As a result, the corrugated board has a composite ring pressure strength and the corrugated board composition and shape are obtained.
(4) Check the compressive strength of the carton. The compressive strength of the actual board obtained in (3) is brought into the Kellicutt formula, and the compressive strength of the corrugated box obtained should be greater than that in (1).
(5) Carton side pressure strength check. Carton compressive strength P in (1) and (4) is brought into the formula ECT=P/2(l+w), and (4) should be greater than (1). Of course, (4) establishment (4) also holds.
This module can select the most ideal and most economical from the carton market price obtained from the corrugated paper box database from many suitable solutions, and the corresponding box map and size can be retrieved from the corrugated paper box database and can be output by the output module.
4, carton structure optimization design module. The objective function for optimizing the design is:
F=(K1S+K2V1/RV2)/N
In the formula, F - the sum of the cost of the packaging carton and the transportation cost of each item; K1 - the unit price of the corrugated box used (RMB/m); S - the area of ​​the single corrugated box used (m); K2 --Ration rates of used containers from start to finish (RMB/container); Volume of V1-- single corrugated boxes (m); Volume of V2-- containers (m); Space utilization of corrugated boxes inside R--containers ;N--the number of items in a single carton. The independent variables of the objective function are determined by the contents and arrangement of the contents in the carton, the box type, and the container type of the carton in the container. These parameters can be obtained from the corrugated box parameter database and the container parameter database.
Constraints are restrictions that are established to obtain a viable design plan, such as restrictions on the dimensions of the carton in terms of market, circulation, or ergonomics; requirements for carton cutting at the time of processing.
From all the reasonable cartons that meet the strength requirements found in the carton structural design module, find the value of the independent variable when the objective function satisfies the optimal value obtained under the constraint conditions, so as to find the corrugated cartons with the lowest carton costs and transport costs. The box type and its size.
5, other modules and their database and software environment
The output module of the packaging scheme can output one or all of the results of the product crisp value calculation module, buffer design and verification module, carton structural design and verification module, and carton structural optimization design according to the user's requirements.
The programming language used by this software is VC and its database development system. VC is based on the C + + language, easy to use and flexible, the development of visual programming software for Windows applications. Its database development system uses ODBC to successfully combine the flexibility of C++ with the efficient security of the database. Combined with its visual programming features, it provides a good interface for programmers to develop databases.
Third, the use of software and overall structure
In order to design the product for transportation and packaging and to obtain data from the database, the parameters that should be entered when the software is used are: (1) product parameters; (2) circulation condition codes. Based on the above analysis, the overall block diagram of each part of the software is shown in Figure 3.
Fourth, the conclusion
The software starts from the product itself, and in the case of inputting various parameters, the product buffer design scheme is directly derived. It changed the traditional packaging design process, saved costs, increased efficiency, and has great application prospects.
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