Composition and application of the hottest transpo

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The composition and application of transportation packaging CAD system

the traditional packaging and transportation design is to obtain the brittleness value of the product according to the experiment, and then carry out the design of buffer liner, outer packaging container and carton structure optimization design according to the circulation conditions of the relevant formula, and also carry out verification and long-term practical inspection. Finally, the product can get a more ideal packaging. The traditional transportation packaging design method has a long history cycle, which requires direct testing of products to determine the brittleness value of products, and also relies on practical testing, so it will cause product waste; It is also easy to cause over packaging of products, resulting in the waste of packaging materials. Can we use certain theories, methods and technologies to complete this design process with the help of computers, know the product and circulation conditions, directly solve the product brittleness value, and design the required and economically feasible cushion liner and outer packaging container. The transportation packaging CAD system that the author wants to discuss can realize this requirement. Now it is introduced as follows

1. Software system composition

transportation packaging CAD system is mainly composed of four modules: product brittleness value solution module, buffer design and verification module, carton structure design and verification module, carton structure optimization design module and transportation packaging design scheme output module. Each modular pair completes certain functions independently, but restricts and depends on each other to jointly complete the design task of product transportation packaging

II. Functions of software modules and their implementation

1. Product brittleness value solution module

the main function of this module is to simulate the test conditions of

based on the known parameters of the product (size, elastic modulus E, Poisson's ratio, density, damping coefficient, etc.), and directly solve the product brittleness value by computer

the traditional methods to calculate the brittleness value mainly include: impact machine test method, buffer drop test method, etc. They all process the measured data to obtain the brittleness value of the product under certain transient impact until the product is damaged and loses its use value. The software simulation test to solve the brittleness value of products mainly solves the following problems:

(1) analyze the structural characteristics of products, and dissociate products into several substructures according to certain principles. The finite element method is used to analyze each substructure and establish their models respectively

(2) with the help of the displacement continuity condition of the connection point, the dynamic structure method is used to calculate the combination of each substructure and establish the system equation

(3) through the investigation, analysis and research of a large number of damage accidents of products, find the common damaged parts of products, classify them, analyze their vulnerability, and establish the damage judgment conditions of various parts

(4) simulate the test conditions to apply impact excitation to the product

(5) use the mode superposition method to solve the system equation, get the response of the node at each vulnerable part of the product to the excitation, and judge its damage

(6) if there is no damage of fragile parts, increase the impact excitation by a certain percentage, and repeat the above process until the damage of a part happens, then use the ratio of the last impact excitation to the gravitational acceleration as the product brittleness value; If a part is damaged and the excitation is applied for the first time, reduce the excitation by a large proportion until no part is damaged, and then increase the excitation to repeat the above process; If the excitation is not applied for the first time, you can directly ask for the brittleness value of the product

2. Buffer design and verification module

the main function of this module is to find the economic materials that meet the requirements from several buffer materials based on the product brittleness value and the stress characteristics in circulation

the design methods of buffer liner include buffer coefficient maximum static stress (C-M) method, buffer coefficient strain force curve (c-) method, etc. This system uses C-M curve method as an example

it is known that the product brittleness value meets the customer's high-quality demand g, product quality m, product length L, width W, height h, and seeks the most economical cushioning material and its size

solution process:

(1) obtain the drop height h from the circulation condition database according to the circulation conditions

(2) obtain the minimum buffer coefficient C and corresponding static stress of each suitable buffer material from the buffer material database

(3) get the bearing area a of each buffer liner from the formula a=w c/and this area should be less than the minimum bearing area of the product, otherwise cancel the buffer material and choose a larger material. Then the thickness t of each buffer liner is obtained from the formula t=c*h/g

(4) deflection check, so that a/(1.33t) ^2 1. Otherwise, take the smaller T and increase a

(5) corner drop check, increase L, W, h by 2T respectively, so that 3 (L w h)/(l^2 + w^2 + h^2) ^1/2 1 W. Otherwise, cancel the material

(6) anti vibration check. From the initial elasticity e, bearing area a, gravity acceleration g, weight W and thickness t of each buffer liner, the natural frequency f of the buffer liner can be obtained from the formula f= (e a g/(W T)) ^1/2 1/2, and the maximum transfer rate TM of each buffer material can be obtained from F (which can be obtained from the buffer material database). Then the acceleration p=tm a of the product can be obtained from the vibration acceleration a in the flow. To make PGG, otherwise increase a, take the smaller T, and continue to check until it is satisfied

(7) from the area a and thickness t of the buffer liner that meet the requirements, and the material price obtained from the buffer material database, the most economical buffer material that meets the above requirements can be found

finally, the module transmits the internal dimension (l+2t) * (w+2t) * (h+2t) to the carton structure design and verification module or output

3. Carton structure design and verification module

the calculation formulas of corrugated cartons include kellicutt, maltenfort, wolf, makee, etc. The system adopts kellicutt formula

known: obtain the height h, storage time t, and the shape and composition of corrugated paper from the circulation condition database

solution process:

(1) the compressive strength P (KGF) that the carton should have can be obtained from the formula p=kw (H-H)/h. Where: K is the safety factor, which can be obtained from the circulation condition database according to the storage environment and storage cycle t. W is the gross weight of the product. H is the height of the package

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(2) from the formula p=2.54px*f, the comprehensive ring crush strength PX (kgf/cm) per cm of corrugated paper can be obtained. Where f= (4 ax2/z) ^2/3 Z J, Z is the perimeter of the carton, AX2 is the corrugated constant, j is the carton constant, and different corrugated types have different AX2 and j, which can be obtained from the corrugated parameter database

(3) according to the formula px= (rn+ CI RM)/l, the actual ring compression strength PX of corrugated board can be obtained. Where: RN is the ring crush strength of the paper on the surface of the carton, the lining paper or the sandwich paperboard, CI is the corrugated shrinkage, RM is the ring crush strength of the corrugated core paper, l is the ring crush pattern test length, and the standard is 6inches. These parameters can be obtained from the corrugated parameter database, and the corrugated parameter database also contains the corresponding corrugated box composition and corrugated type. Therefore, the composition and shape of corrugated board are obtained when the comprehensive ring compression strength of corrugated board is obtained

(4) carton compressive strength check. Bring the compressive strength of the actual paperboard obtained in (3) into kellicutt formula, and get that the compressive strength of the corrugated box with

should be greater than the result in (1)

(5) carton edge pressure strength check. Bring the carton compressive strength P in (1) and (4) into the formula ect=p/2 (l+w), and the value of (4) should be greater than that of (1). Of course, (4) is established (4) is also established

this module can select the most ideal and economical one from many suitable schemes according to the carton market price obtained from the corrugated box database, and retrieve the corresponding carton diagram and size from the corrugated box database, which can be output by the output module

4. Carton structure optimization design module. The objective function of the optimization design is:

f= (k1s+k2v1/rv2)/n

, where f is the sum of the cost of packaging cartons and transportation costs for each commodity; K1 -- unit price of corrugated box used (yuan/m); S -- material area of a single corrugated box (m); K2 -- freight rate of containers used from the starting point to the terminal (yuan/container); V1 -- volume of a single corrugated box (m); V2 -- container volume (m); R -- space utilization rate of corrugated boxes in containers; N -- quantity of goods in a single carton. The independent variables of the objective function are determined by the number and mode of items and arrangement in the carton, the carton type, and the containerization mode of the carton in the container. These parameters such as construction and automobile industry can be obtained from corrugated box parameter database and container parameter database

constraints are the constraints set up to obtain a feasible design scheme, such as the restrictions on the overall dimensions of cartons by market, circulation links or ergonomic factors; Carton processing and cutting requirements, etc

from all reasonable cartons that meet the strength requirements obtained from the carton structure design module, find the value of the independent variable when the objective function meets the optimal value obtained under the constraint conditions, so as to find the type and size of the corrugated carton with the lowest carton cost and transportation cost

5. Other modules and their databases and software environment

the packaging scheme output module can output one or all of the result schemes in the product brittleness value solution module, buffer design and verification module, carton structure design and verification module and carton structure optimization design according to the requirements of users

the programming language used in this software is VC and its database development system. VC is a visual programming software based on c++ language, which is easy to use and flexible to develop Windows applications. With the help of ODBC, its database development system successfully combines the flexibility of c++ with the efficiency and security of the database. Combined with its visual programming characteristics, it provides a good interface for programmers to develop databases

III. use and overall structure of the software

in order to design the transportation packaging of products and obtain data from the database, the parameters that should be input when using the software are: (1) product parameters; (2) Circulation condition code. Combined with the above analysis, the overall structure block diagram of each part of the software is shown in Figure 3

IV. conclusion

this software starts from the product itself and directly obtains the product buffer design scheme under the condition of inputting various parameters. It changes the process of traditional packaging design, saves costs, improves efficiency, and has great application prospects

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