3D printing device for large-scale additive manufacturing

Abstract

The embodiment of the invention discloses a 3D printing device for large-scale additive manufacturing and belongs to the technical field of 3D printing. The device comprises a material melt extrusionmechanism and a printing head; the printing head is connected with a molten material flow control mechanism; and the printing head is fixedly connected with the material melt extrusion mechanism. According to the material melt extrusion mechanism, an extrusion mode applying a counter-rotating conical double-screw structure is adopted; the double-screw extrusion mechanism is driven in a direct connection manner, and therefore, the integration level of a driving structure is improved, and an extruder with the counter-rotating conical double-screw structure can be applied to a 3D printer. In screw clearances, apart from exclusion mechanical pressure, the thermal expansion pressure component of a molten material is not controlled by screws, and therefore, the printing head at the tail end of the 3D printing device is improved; the printing head is connected with the molten material flow control mechanism, so that the printing head is of a variable-caliber structure and can perform throttling control over molten fluid; and therefore, control precision and real-time performance are improved, and the requirements of an efficient large-scale FDM 3D printing process can be met.

Description

technical field [0001] The embodiment of the present invention relates to the technical field of 3D printing, in particular to a 3D printing device for large-scale additive manufacturing. Background technique [0002] Manufacturing technology background of large-scale products: All products are produced and served for human life, and the size of an adult is generally one meter to two meters. Taking the human scale as the scale, the product size below one meter can be defined as a small size, and one to two meters is defined as a small size. Medium size, larger than two meters is defined as large size. [0003] From the basic point of view, there are only three kinds of industrial manufacturing methods at present, namely, subtractive manufacturing, equal material manufacturing, and additive manufacturing. [0004] Subtractive manufacturing: From the Stone Age, one stone was knocked with another stone to subtract the excess part to get the desired part, and it has been used u...

AI Technical Summary

Problems solved by technology

Disadvantages: waste of material, medium efficiency, tool interference, especially serious in large and complex structures

Disadvantages: high investment threshold, long process cycle, large temperature changes, phase transition, large stress, large deformation, low overall precision, especially in the case of large and complex structures

However, as mentioned above, it can be seen that material subtraction and equal material all involve the surface of the overall material, while 3D printing involves the interior of the material, cutting the interior into a surface that can be printed, which is much larger than the original surface area, so , at the same movement speed, the efficiency of 3D printing is much lower than the first two methods

Disadvantages: very low efficiency

In order to solve the problem of large-scale material powder, the original mechanical structure design and process of the SLS process will become very complicated, the total cost of materials is high, and the energy consumption will be very large.

[0015] The power of the laser used in the SLS process is closely related to the molding speed. The maximum power is generally between 0.4kw--1kw. According to the principle of proportional amplification, the volume of the product is enlarged by 1000 times. Theoretically, the maximum power of the SLS process is also enlarged by 1000 times. , otherwise it is equivalent to using a small light spot to describe a picture that has been enlarged by a thousand times, and the efficiency will be unacceptably low, or the maximum power of the matching laser needs to be 400kw to 1000kw. According to the current laser technology, the commonly used power is in the Below 6kw, 400kw may only be realized in the military field, so the large-scale SLS process is currently difficult to achieve

[0016] The printing layer height of SLS is also limited, because its principle is to sinter or melt the powder to form a solid state by using the focal spot of laser focus to generate high temperature, and heat conduction spontaneously diffuses to the surrounding powder. If you want to have a deeper Sintering thickness (layer height), thermal diffusion will lead to uncontrollable sintered line edges

Therefore, in terms of technical principles, economics, and practicality, it is not suitable for large-scale

[0017] 3. FDM process (Fused Deposition Modeling), also known as fused filament deposition, the existing small-scale FDM process mainly uses thermoplastic wires with a diameter of about 1mm-3mm as printing materials, and the print head (2) melts the wires to form each The shape of the layer, the technology required by the FDM process is the simplest of all 3D printing process types, except that the moving structure only needs a wire feeding mechanism and a heating head (print head). Compared with the SLS process and the DLP process, the FDM process has no Using expensive materials and not using expensive technology, the forming principle is relatively simple. In theory, as long as the printing line is ten times thicker, the volume increase can be increased by 100 times while the original motion speed remains unchanged. Although The surface accuracy is sacrificed, but in the field of large-scale additive manufacturing, accuracy is not the main problem. On the one hand, large-scale products such as furniture, houses, lamps, decorations, etc. do not require high overall dimensional accuracy. On the other hand, large-scale products require The surface finish is determined by the coating process, and the efficiency is the main problem when the size reaches the order of several meters. FDM can greatly improve the material flow rate, line width and layer height. The volumetric efficiency of molding, so there is a possibility of large-scale FDM process

However, the transmission chain of the existing conical counter-rotating twin-screw extruder is very long, and it is difficult to achieve precise transmission.

[0027] On the whole, the existing conical counter-rotating twin-screw extruders have important defects such as large volume and weight, too long drive chain, etc. Of course, they cannot be used alone in 3D printing systems, because hot-melt materials, in addition to extruding In addition to the driving force of the extruder, the pressure generated by thermal expansion is not controlled by the extruder, and end opening and closing and throttling control are required, which need to be improved according to the characteristics of the 3D printing process

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