Rapid prototyping method based on wood flour

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Rapid prototyping method based on wood flour

in the modern society with the high development of automation and information technology, people's demand for products is becoming more and more diversified, the competition for products to compete for the market is becoming more and more intense, and the renewal cycle is becoming shorter and shorter. This requires designers not only to design new products according to the requirements of the market, but also to manufacture prototypes in the shortest possible time, so as to carry out necessary performance tests, At the same time, make corresponding modifications on the basis of consulting users' opinions, and finally form finalized products that can be put on the market. In this way, in the fierce market, the second transmission mode can not guarantee the synchronization of transmission, take the lead in the competition, seize the opportunity and win customers. The traditional manufacturing method is to use the idea of material removal to produce the original, which is completed through a series of machining processes such as turning, milling, planing, grinding, etc. in this way, the original produced has high cost and long cycle, and can no longer adapt to the changing market. The rapid prototyping technology has essentially changed this traditional manufacturing idea. By using the processing method of adding materials, it has been liberated in the manufacturing idea. It is a new three-dimensional model manufacturing method. It only needs three-dimensional CAD system modeling, generates three-dimensional computer graphics of products, and then carries out layered processing. Through the control of the molding machine, extremely complex workpieces can be accurately manufactured, It is a new technology with strong vitality

1 current shortcomings of rapid prototyping technology

rapid prototyping has the advantages of rapidity, integration of design and manufacturing, free-form manufacturing, high flexibility, universality of materials, high integration of technology and so on. Like any new technology, it has to go through the process of gradual improvement. Rapid prototyping technology is currently in this critical stage, and there are some deficiencies. It mainly focuses on the following points:

1.1 high material cost

in terms of several existing rapid prototyping technologies, there is a common problem of high material cost. Among them, the materials for layered object manufacturing (LOM) are the cheapest, with a price of 9.63-17.08 US dollars/kg. The most expensive materials are three-dimensional flat panel printing equipment (SLA) and deposition molding (FDM), with a price of US dollars/kg. The materials for selective laser sintering (SLS) are in the middle

the low-temperature ice rapid prototyping method developed by Tsinghua University, which uses water as raw material, is cheap, and the accuracy of the molding components is good, but at the same time, it is limited by low temperature, and cannot be widely used in various fields

1.2 the equipment price and system operation cost are high

at present, a rapid prototyping equipment needs 300000-500000 dollars, which does not include the protective gas, hydropower, housing, spare parts and maintenance costs required for the operation of the system, as well as equipment depreciation costs. For RP system using laser as forming source, the guaranteed service life and maintenance price of laser must be considered emphatically. For example, the guaranteed service life of UV laser is 2000h, and the price of UV laser tube reaches tens of thousands of dollars. In addition, because of its strength, surface quality and other properties, the molded parts can not meet the requirements of application in some cases. In order to make up for some shortcomings of directly formed parts, we often invest a lot of manpower and material resources to carry out necessary post-treatment to improve the strength and surface smoothness of formed parts

based on the above problems of current rapid prototyping equipment and materials, we propose a new rapid prototyping method - rapid prototyping method based on wood flour. In terms of equipment, the following 8 methods are not used to protect the hardness tester, which is expensive and has a long service life: a short laser, but a mechanical nozzle with low price and long service life. The material is wood flour, which is widely used. Compared with other rapid prototyping materials, it has lower cost, more environmental protection and easier degradation. The appearance of the molded original is similar to that of wood. It has the characteristics of hardwood, high strength, not easy to deform, and simple post-treatment. It can completely replace the existing plastic and resin models in some occasions, and can be used as concept prototypes, prototypes for function tests, molds, and functional parts

2 rapid prototyping method based on wood flour

the maximum insurance rate is no more than 3%

2.1 principle of rapid prototyping machine based on wood flour

Figure 1 principle of rapid prototyping machine based on wood flour

the molding of various RP technologies is based on the basic idea of dispersion and accumulation. The following describes the forming principle of rapid prototyping based on wood flour in combination with figure 1. Under the control of microcomputer, the nozzle moves according to the shape of each layered section of the processed parts and works. This experiment began in March 2013. Spray liquid glue on the platform, and there is a powder feeding trolley on the left side. Spread wood powder on the surface with glue and compact it to form a solidified layer. When one layer is finished, the place not sprayed with glue is still powdery wood powder. Then, the lifting table drives the base plate to drop another layer of height, and then spray the second layer of glue. The newly solidified layer is firmly adhered to the previous layer, and this is repeated until the whole part is manufactured

2.2 the working process of the rapid prototyping machine based on wood flour

first, the surface or solid model is generated by CAD software, and then the CAD model is converted into STL file format. Using the preprocessing software, the plane information of layer by layer is obtained from the STL model. The layer thickness can be adjusted, and the layer information is used to drive the nozzle to complete the spraying of glue. Write down that the powder supply and powder spreading system of the rapid prototyping machine completes the actions of powder spreading and compaction. Prototype parts are produced in this cycle. Finally, in order to meet the actual situation and technical requirements, we need to carry out secondary curing and necessary trimming of the prototype

the working process of the rapid prototyping system based on wood flour is shown in Figure 2

Figure 2 the working process of the rapid prototyping system based on wood flour

2.3 the powder supply and powder laying system of the rapid prototyping machine based on wood flour

on the basis of completing the conceptual design of the prototype, computer CAD modeling, discretization of the slicing program, and conversion into the executable information of rapid prototyping, it is the action to be completed by the molding machine to start powder feeding and powder laying

2.3.1 composition of powder supply and spreading system

powder supply and spreading system is composed of bed, powder supply cylinder, forming cylinder, powder spreading roller, etc. The stepping motor of the powder supply cylinder drives the lead screw to move the piston of the powder supply cylinder up and down, and adjust the thickness of the wood powder layer to achieve the fixed value feed in the height direction. The feed rate is determined by the thickness of the layer. Each time a layer of molding is completed, the molding cylinder will drop one layer of height. At the same time, the piston of the powder feeding cylinder is raised by one layer. Figure 3

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