CN103978686A - System for 3D printing of high-molecular material by using system using fiber coupling for outputting laser - Google Patents

Abstract

The invention provides a 3D printing polymer material system using optical fiber coupling to output laser, and the system is used to improve the quality of 3D printing parts of polymer materials. Using the optical fiber coupling method to shape the output spot of the laser source used in 3D printer processing to realize the redistribution of beam energy, that is, to change the original ring shape and the output spot whose intensity gradually weakens from the center to the outside into a spot with uniform intensity distribution, which can solve the problem of high Due to the poor heat resistance of molecular materials, molded parts are easy to warp and deform under an uneven temperature field. At the same time, with the help of the parameter control module, the system can obtain suitable processing parameters for different polymer materials, including laser power and laser scanning speed. Under the appropriate processing parameters, the energy absorbed by the polymer material can be matched with the required melting energy to prevent excessive processing from decomposing and gasifying the material.

Description

A 3D printing polymer material system using fiber-coupled output laser

technical field

The invention relates to the technical field of laser processing, in particular to a 3D printing polymer material system for optimizing the quality of 3D printed parts of polymer materials using optical fiber coupling to output laser light.

Background technique

Laser rapid prototyping with laser as processing energy is an important part of 3D technology, which integrates modern scientific and technological achievements such as CAD technology, numerical control technology, laser technology and material science. Different from traditional processing methods such as removal molding, joint molding and forced molding, Laser Rapid Prototyping (LRP) is based on the idea of accumulation molding to manufacture plastic, ceramic, metal and various composite material solid models. Laser rapid prototyping first uses CAD to generate a three-dimensional solid model, and then layers based on software to obtain two-dimensional data of each thin layer section, which is used to drive and control the laser beam to scan the powder layer. The thermal effect of the laser beam on the surface of the powder particles causes the surface of the powder particles to melt and adhere to each other, thereby processing a thin layer of the desired shape. Then lay another layer of powder and repeat the above process. The new layer and the previous layer are naturally sintered together, and the solid model is formed layer by layer. Finally, the unsintered powder is removed to obtain a molded part.

This method is applicable to a wide range of materials, among which polymer materials are one of the mainstream material types used. For polymer materials, the main problems of laser processing and molding are: the Gaussian distribution of laser energy will lead to large energy absorbed in the center of the irradiation area, rapid temperature rise, and large shrinkage; while the peripheral irradiation area absorbs energy, Slow temperature rise and small shrinkage. Such inconsistent shrinkage deformation will cause stress between powders and warpage. In addition, polymer materials in places where the local temperature is too high are easy to burn and vaporize. There have been many patents from the perspective of polymer material modification, through improving and optimizing the powder preparation process, in order to achieve the purpose of improving the quality of polymer material 3D printing parts. The present invention proposes a solution from the perspective of optimizing the laser used in 3D printing.

Contents of the invention

Aiming at the problem of warping and deformation of workpieces due to uneven heating during the processing of polymer materials, the present invention provides a 3D printing polymer material system that uses optical fiber coupling to output laser light. The system is based on improving the laser output energy distribution to achieve a uniform temperature field distribution in the polymer material processing area, thereby optimizing the quality of the workpiece. The method is to introduce a fiber-coupled module into the laser source for processing. The initially generated laser light is coupled into the optical fiber in different ways, then transmitted through the optical fiber, and finally output from the other end of the optical fiber. The function of the fiber coupling module is to change the output light spot in the shape of a ring, whose intensity gradually decreases from the center to the outside, into a light spot with uniform intensity distribution. Concrete invention content is as follows:

A 3D printing polymer material system using optical fiber coupled output laser. It includes a parameter control module, a control system, a laser system, and a scanning system. The parameter control module calculates the processing parameters of different types of polymer materials, and then transmits the parameter signals to the control system. The control system includes two control modules: a laser power controller and a scanning speed controller, which respectively receive corresponding parameter signals. The laser power controller transmits a power control signal to the laser system according to the laser power signal received by the parameter control module. The scanning speed control system transmits a scanning speed control signal to the scanning system according to the scanning speed signal received by the parameter control module. The laser drive power supply system in the laser system receives the power control signal and adjusts its output current to control the output power of the laser; the laser of the pulsed laser is output through the fiber coupling output module in the laser system. The bracket driving system in the scanning system receives the scanning speed control signal and adjusts the rotation speed of the central axis of the bracket equipped with the laser vibrating mirror to control the laser scanning speed.

The output spot intensity of the laser light source used in 3D printer processing is evenly distributed. Under the processing parameters given by the parameter control module, the energy absorbed by the polymer material can be matched with the required melting energy to prevent excessive processing from decomposing and gasifying the material. In this way, the quality of polymer materials 3D printing parts can be improved.

The method for calculating the processing parameters of the material by the parameter control module is as follows: input the physical characteristic parameters of various polymer materials in the parameter control module in advance, and the physical characteristic parameters include specific heat capacity, specific gravity, required preheating temperature, and required processing Temperature; and set a certain laser power and laser scanning speed in the parameter control module. The parameter control module calculates the energy absorbed by the unit volume of powder in one scan based on the diameter of the optical fiber coupling output spot and the powder coating thickness. The absorbed energy depends on Laser power and laser scanning speed; then calculate the melting energy required per unit volume of powder according to the specific heat capacity, preheating temperature and the processing temperature to be achieved; If there is a difference, the parameter control module automatically corrects the laser power and laser scanning speed, and then repeats the above calculation process until the energy of the two is equal, and then the best processing parameters are obtained.

The control system includes a laser power controller and a scanning speed controller. The role of the laser power controller is to receive the laser power required for polymer material processing given by the parameter control module. The function of the scanning speed controller is to receive the scanning speed required for the processing of polymer materials given by the parameter control module.

The laser system includes a laser drive power supply, a pulse laser and a fiber coupling output module. The drive power supply can receive instructions from the control system, set different working currents, and realize the adjustment of laser power. The pulse laser can be a fiber laser or a solid-state laser, the power of which can be continuously adjusted between 1-100W, and the laser is output through fiber coupling.

The scanning system includes a laser vibrating mirror, a bracket on which the vibrating mirror can be installed, an adjustable rotation speed, and a bracket driving system. The support driving system receives the command of the control system, changes the rotation speed of the central axis of the support, and realizes the adjustment of the scanning speed.

The polymer materials used in the system include nylon 6 (PA6), nylon 66 (PA66), nylon 12 (PA12), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), polyimide Amine (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), polyoxymethylene (POM), polycarbonate (PC), polyvinyl chloride (PVC), polyparaphenylene Butylene glycol dicarboxylate (PBT), polyphenylene ether (PPO), polylactic acid (PLA), polyether ether ketone (PEEK).

The laser in the laser system is output through optical fiber coupling, which can shape the output spot and achieve uniform distribution of intensity. The optical fiber used for coupling is an energy-transmitting silica optical fiber. It includes HCS (Hard Clad Silica) silica clad fiber, also known as hard clad silica fiber; PCS (Plastic Clad Silica) (plastic clad), also known as soft clad silica fiber; PCS-TECS (Technology Clad Silica ) Technology enhanced cladding, also known as hard polyfluorine cladding silica fiber.

The laser in the laser system is coupled out through the optical fiber, and the coupling methods between the optical fiber and the laser are direct coupling, single-lens coupling, and three-lens coupling. The fiber optic head can be processed into spade shape, hemispherical shape and cone shape.

The invention has the beneficial effects of irradiating the powder with uniformly distributed light spots output by the optical fiber coupling output module, which can achieve consistent heating and energy absorption of the powder in the irradiation area, thereby avoiding excessive local temperature rise, and has important industrial application value. Moreover, the laser power and laser scanning speed in this system are calculated by the parameter control module, which can realize that the energy absorbed by the polymer material is equal to the required energy within the laser irradiation time, so as to prevent excessive processing or even gasification decomposition. The required energy refers to the energy absorbed by the polymer material from the preheating temperature to the processing temperature.

Description of drawings

Figure 1 is an effect diagram of using a fiber-coupled module.

Fig. 2 is a schematic diagram of a 3D printing polymer material system using fiber-coupled output laser.

Figure 3 is a schematic diagram of the control system.

Figure 4 is a schematic diagram of the laser system.

Figure 5 is a schematic diagram of the scanning system.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Here is an overall description of the system in conjunction with accompanying drawing 2 .

The invention utilizes the parameter control module to manage and control the parameters. In this parameter control module, the physical characteristic parameters of various polymer materials are input in advance. These physical characteristic parameters include specific heat capacity, specific gravity, required preheating temperature, and required processing temperature. And set a certain laser power and laser scanning speed in the parameter control module. The parameter control module calculates the energy absorbed by the powder per unit volume in one scan based on the diameter of the optical fiber coupling output spot and the powder coating thickness. The absorbed energy depends on the set laser power and laser scanning speed. Then, according to the specific heat capacity, the preheating temperature and the processing temperature to be achieved, the melting energy required for the unit volume of powder is calculated. If there is a difference between the required melting energy and the energy that can be absorbed in a scanning process calculated earlier, the parameter control module automatically corrects the laser power and laser scanning speed, and then repeats the above calculation process until the energy of the two is equivalent, and then the final result is obtained. Optimum processing parameters, including laser power and laser scanning speed. The two parameters of laser power and laser scanning speed are then transmitted to the control system.

A control system, as shown in Figure 3. It includes laser power controller, scanning speed controller. A laser power controller collects the laser power corresponding to the polymer material required by the parameter control module, which is used to control the driving power in the laser system and realize the adjustment of the laser power. A scanning speed controller acquires the laser scanning speed corresponding to the polymer material required by the parameter control module, which is used to control the laser vibrating mirror in the scanning system to realize the adjustment of the rotating speed of the vibrating mirror.

A laser system, as shown in Figure 4. It includes a laser drive power supply, a pulsed laser, and a fiber-coupled output module. The pulse laser can be a fiber laser or a solid-state laser, and its power is continuously adjustable between 1-100W, and the laser is output through a fiber coupling output module. The optical fiber coupling output module is used to shape the spot of the output laser and achieve the purpose of homogenizing the spot. The effect is shown in Figure 1. Among them, the coupling modes of optical fiber and pulsed laser are direct coupling, single-lens coupling, and three-lens coupling. The optical fiber for coupling is an energy-transmitting silica optical fiber, and its fiber head can be processed into spade-shaped, hemispherical, tapered, etc. to improve coupling efficiency. The laser driving power is connected with the laser power controller in the control system. The drive power supply has a memory storage function, which records the corresponding relationship between current and laser power. The laser drive power supply automatically sets the corresponding input current according to the laser power signal given by the laser power controller, and controls the output power of the pulse laser.

A scanning system, as shown in FIG. 5 . It includes a laser galvanometer, a galvanometer-mountable stand with adjustable rotation speed, and a stand drive system. The carriage driving system is connected with the scanning speed controller in the control system. The support changes the rotation speed of the central axis of the support according to the scanning speed signal given by the support drive system to realize the adjustment of the laser scanning speed.

The implementation method of the 3D printing system is as follows: firstly, the physical characteristic parameters of the polymer material powder to be processed are set in the parameter control module, and the laser power and laser scanning speed are preset. The appropriate laser power and laser scanning speed are calculated by the parameter control module according to the above method. The laser power parameters and laser scanning speed parameters are transmitted to the control system. The corresponding signals are respectively received by the laser power controller and the scanning speed controller in the control system, and transmitted to the corresponding system. The laser drive power supply in the laser system receives the laser power signal and sets the corresponding working current. The output power of the laser under the operating current matches the appropriate laser power calculated by the parameter control module. Simultaneously, the support driving system in the scanner receives the scanning speed signal, and sets the rotation speed of the central axis of the support. The rotation speed of the support is matched with the appropriate scanning speed calculated by the parameter control module. After the output laser is homogenized by the energy transmission fiber, it is incident on the vibrating mirror, and then reflected by the vibrating mirror to the powder on the workbench to achieve the ideal 3D printing effect.

Example 1

The 3D printing polymer material system using fiber-coupled output laser shown in Figure 2 is applied. In this embodiment, a solid-state pulsed laser is used to perform 3D printing processing on PS (polystyrene) polymer materials. Select "PS (polystyrene)" in the parameter control module. The laser output is coupled into a quartz fiber with a flat end face of 1 mm in diameter, and the intensity of the output spot is approximately flat-topped, and the spot diameter is about 1 mm.

The PS (polystyrene) polymer material has a specific heat fusion of 0.5kJ/(kg*K), a specific gravity of 1.0g/cm ³ , a powder coating thickness of 0.1mm, and a powder preheating temperature of 115°C. The processing temperature to be achieved is 200°C. Select laser power 20W. The volume of powder irradiated by a spot with a diameter of 1mm is 0.08mm3. Based on the uniform energy distribution of the spot, the energy absorbed per unit volume per unit time is 250J/(mm ³ *S). If the laser scanning speed is 1400mm/s, the energy absorbed by the powder per unit volume is 0.18J for one scan. The powder rises from 115°C to 200°C, and a temperature rise of 358K is required. According to the specific heat capacity, the powder per unit volume (mm ³ ) needs to absorb 0.18J of energy to heat up to 358K under laser irradiation. The laser output power of 20W and the scanning speed of 1400mm/s are respectively transmitted to the corresponding controller in the control system as processing parameter signals, and the controller controls the laser power drive system and the bracket drive system to ensure that the laser power is 20W and the laser scanning speed is 20W. It is 1400mm/s.

Example 2

In this embodiment, a solid-state pulsed laser is used to 3D print the ABS (acrylonitrile-butadiene-styrene) polymer material. Select "ABS (acrylonitrile-butadiene-styrene)" in the parameter control module. The laser output is coupled into a quartz fiber with a flat end face of 1 mm in diameter, and the intensity of the output spot is approximately flat-topped, and the spot diameter is about 1 mm.

The specific heat of the ABS (acrylonitrile-butadiene-styrene) polymer material is 1.47kJ/(kg*K), the specific gravity is 1.05g/cm ³ , the powder coating thickness is 0.1mm, and the powder preheating temperature is 100 °C, the processing temperature to be achieved is 210 °C. Choose laser power 72W. The volume of powder irradiated by a spot with a diameter of 1mm is 0.08mm ³ . Based on the uniform energy distribution of the spot, the energy absorbed per unit volume per unit time is 900J/(mm ³ *S). If the laser scanning speed is 1500mm/s, the energy absorbed by the powder per unit volume is 0.6J for one scan. The powder rises from 100°C to 210°C and needs to reach a temperature rise of 383K. According to the specific heat capacity, the powder per unit volume (mm ³ ) needs to absorb 0.6J of energy to heat up to 358K under laser irradiation. Then the laser output power of 72W and the scanning speed of 1500mm/s are transmitted as processing parameter signals to the corresponding controller in the control system, and the controller controls the laser power drive system and the bracket drive system to ensure that the laser power is 72W and the laser scanning speed It is 1500mm/s.

This method achieves that the absorbed energy in the irradiated area is equivalent to the required melting energy. Through the homogenization spot technology, the processing conditions are the same and the progress is the same, thereby suppressing the warping and deformation of the processed workpiece. And by selecting appropriate working parameters, avoid over-processing.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are Should be included within the protection scope of the present invention. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them.

Claims (6)

1. A 3D printing polymer material system using optical fiber coupling output laser, characterized in that the system includes: a parameter control module, a control system, a laser system, a scanning system; the parameter control module calculates the processing of different types of polymer materials Parameters, which include laser power and laser scanning speed; then transmit the laser power and laser scanning speed signals to the control system; the control system includes two control modules: laser power controller and scanning speed controller, both receive corresponding The parameter signal; the laser power controller transmits the power control signal to the laser system according to the laser power signal received from the parameter control module; the scanning speed controller transmits the scanning speed control signal to the scanning system according to the scanning speed signal received from the parameter control module ; The laser drive power supply in the laser system receives the power control signal and adjusts its output current to control the output power of the pulse laser in the laser system; the laser of the pulse laser is output through the fiber coupling output module in the laser system; The bracket driving system receives the scanning speed control signal, and adjusts the rotation speed of the central axis of the bracket equipped with the laser vibrating mirror to control the laser scanning speed. 2. system according to claim 1, it is characterized in that, the method that parameter control module calculates the processing parameter of this material is: input the physical property parameter of various polymer materials in advance in this parameter control module, physical property parameter comprises Specific heat capacity, specific gravity, required preheating temperature, and processing temperature to be achieved; and set a certain laser power and laser scanning speed in the parameter control module. The parameter control module calculates the unit volume of powder based on the diameter of the optical fiber coupling output spot and the thickness of the powder The energy absorbed in one scan depends on the laser power and laser scanning speed; then calculate the melting energy per unit volume of powder according to the specific heat capacity, preheating temperature and the processing temperature to be achieved; if the required If there is a difference between the melting energy and the energy that can be absorbed in a scanning process calculated earlier, the parameter control module automatically corrects the laser power and laser scanning speed, and then repeats the above calculation process until the energy of the two is equal, and then the best processing parameters are obtained. 3. The system according to claim 1 or 2, wherein the pulsed laser can be a fiber laser or a solid-state laser, and its power is continuously adjustable between 1-100W. 4. The system according to any one of claims 1 to 3, characterized in that the polymer materials used in the system include nylon 6 (PA6), nylon 66 (PA66), nylon 12 (PA12), polystyrene Polyethylene (PS), Acrylonitrile-Butadiene-Styrene (ABS), Polyimide (PI), Polymethylmethacrylate (PMMA), Polyethylene (PE), Polypropylene (PP), Polyoxymethylene (POM), polycarbonate (PC), polyvinyl chloride (PVC), polybutylene terephthalate (PBT), polyphenylene ether (PPO), polylactic acid (PLA), polyether ether ketone (PEEK ). 5. The system according to any one of claims 1 to 4, wherein the optical fiber used for coupling is an energy-transmitting silica optical fiber, which includes HCS (Hard Clad Silica) silica-clad optical fiber, PCS (Plastic Clad Silica ) plastic clad fiber, PCS-TECS (Technology Clad Silica) technology enhanced clad fiber. 6. The system according to any one of claims 1 to 5, wherein the laser in the laser system is coupled out through an optical fiber, and the coupling mode between the optical fiber and the laser is direct coupling, single-lens coupling, or three-lens coupling; The fiber optic head can be processed into spade shape, hemispherical shape and cone shape.