WO2022247084A1 - 一种基于光固化的液面连续成型系统 - Google Patents

一种基于光固化的液面连续成型系统 Download PDF

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Publication number
WO2022247084A1
WO2022247084A1 PCT/CN2021/121155 CN2021121155W WO2022247084A1 WO 2022247084 A1 WO2022247084 A1 WO 2022247084A1 CN 2021121155 W CN2021121155 W CN 2021121155W WO 2022247084 A1 WO2022247084 A1 WO 2022247084A1
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Prior art keywords
motor
control
board
sensor
system based
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PCT/CN2021/121155
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English (en)
French (fr)
Inventor
王宜怀
施连敏
陈琳
叶柯阳
何双辰
朱轩
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苏州大学
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Publication of WO2022247084A1 publication Critical patent/WO2022247084A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
    • B29C64/129—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/386—Data acquisition or data processing for additive manufacturing
    • B29C64/393—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y50/00—Data acquisition or data processing for additive manufacturing
    • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes

Definitions

  • the invention relates to the technical field of intelligent rapid prototyping, in particular to a liquid surface continuous prototyping system based on photocuring.
  • the rapid prototyping technology based on light curing is to project ultraviolet light into the liquid photosensitive resin, so that the resin is continuously cured layer by layer.
  • Digital light processing (DLP) molding technology has problems such as limited molding size, high equipment price and lens distortion that restrict the development of this technology. Therefore, liquid crystal display (LCD) is used as an area selective light transmission device, which can be used to manufacture large and High precision parts.
  • LCD liquid crystal display
  • the difficult coordination between molding efficiency and molding quality is the main factor limiting the development of LCD molding technology, so it is necessary to find a reconciliation strategy for the two.
  • the invention provides a continuous liquid surface molding system based on photocuring, including:
  • the forming table is fixed on the liquid tank, and the sliding guide rail, roller screw, stepping motor, liquid tank, and UV lampshade are fixed on the main board;
  • the motor driver is connected to the stepping motor and the PCB control board respectively, and connected through terminal blocks. Raspberry Pi and control panel;
  • the LCD screen is located at the bottom of the liquid tank, and the UV ultraviolet light parallel light source is located in the UV lampshade;
  • the PCB control board includes a main controller, a DC power supply, a motor control module, a sensor and an LED light switch module, the main controller uses PWM to control the motor driver, and the motor driver controls the rotation of the motor; the main controller passes GPIO Control sensor and LED switch modules.
  • it further includes a heat dissipation aluminum sheet, and the heat dissipation aluminum sheet is located on the back of the UV lampshade.
  • it further includes a fan installed on the motor driver.
  • the roller screw can drive the forming table to lift and descend.
  • a release film is further included, installed at the bottom of the liquid tank and in a tight state.
  • the main controller includes a main control chip, a function board and a sensor board; the main control chip is used to receive instructions from the host computer and resolve them and send them to the function board and the sensor board, and the function board is used to control motor movement and UV lamps , the sensor board is used to control the limit switch of the forming table, and the sensor is installed on the sensor board.
  • a limit switch is further included, including an upper limit switch and a lower limit switch, for limiting the range of movement of the molding table.
  • an isolation circuit is further included, the isolation circuit includes a motor control isolation circuit and a sensor signal input isolation circuit; the motor control isolation circuit is between the main control chip and the stepping motor, and the sensor signal input isolation circuit is between the sensor and the main control chip.
  • the LED switch module is used to control the bright and dark states of the UV backlight panel, the signal end is connected to the GPIO pin of the main control chip for controlling the conduction state, the input end is connected to the power supply voltage, and the output end is connected to the UV lamp.
  • the present invention is a liquid surface continuous molding system based on photocuring, which has high positioning accuracy and high uniformity of LCD projected UV light.
  • Figure 1 shows a schematic structural view of a liquid surface continuous molding system based on photocuring according to an embodiment of the present invention.
  • Figure 2 shows a schematic view of the structure of the forming table according to the embodiment of the present invention.
  • Fig. 3 shows a schematic structural diagram of a UV lampshade according to an embodiment of the present invention.
  • Fig. 4 shows a schematic structural diagram of a liquid tank according to an embodiment of the present invention.
  • Fig. 5 shows a schematic diagram of a hardware control system according to an embodiment of the present invention.
  • Fig. 6 shows a diagram of a motor control isolation circuit according to an embodiment of the present invention.
  • Fig. 7 shows a circuit diagram of a sensor signal input isolation circuit according to an embodiment of the present invention.
  • the present invention introduces the overall design of the machine and hardware platform in detail, and first provides the design principles of the key parts of the machine. Including the easy calibration of the molding table, the airtightness and heat dissipation of the UV lampshade, and the design points of the liquid tank. Then, the design method of the hardware control system and related hardware selection are expounded, which mainly includes the resource division and isolation circuit design of the main control chip, and the technical indicators of the hardware selection are introduced in detail.
  • the key parts of the mechanical structure require stable quality and high precision, so they are manufactured by CNC technology.
  • the machine as a whole is processed by aluminum parts, and only the hood is made of acrylic material that prevents UV ultraviolet light from overflowing.
  • the LCD screen is invisible at the bottom of the liquid tank, and the UV ultraviolet light parallel light source is invisible inside the UV lampshade. All other components are labeled.
  • the forming table is fixed on the liquid tank, the sliding guide rail, roller screw, stepping motor, liquid tank, and UV lampshade are fixed on the main board, and the heat dissipation aluminum sheet is located on the back of the UV lampshade;
  • the motor driver is connected to the stepping motor and PCB respectively.
  • the control board is connected to the Raspberry Pi and the control panel through terminal blocks; the fan is installed on the motor driver.
  • Each mechanical part needs to be designed according to the characteristics of LCD light curing.
  • the main parts that need attention are the molding table, UV lampshade, and liquid tank. This section focuses on the design points and functions of these components.
  • the calibration of the forming table is a tricky issue in light-curing rapid prototyping, and it is difficult for novices to use more professional tools for leveling when printing. Therefore, the forming table designed by the present invention adopts the hydraulic balance self-calibration technology, which can complete the calibration simply and conveniently, and is very friendly to novice users.
  • the rotation of the screw drives the lifting and lowering of the forming table.
  • the forming table is required to be parallel to the release film, and the distance is consistent with the thickness of the slice.
  • the release film is not parallel to the molding table, it will lead to problems such as uneven curing thickness of the photosensitive resin, failure to release the film, and inability to adhere to the molding table. Therefore, whether the molding table is parallel to the release film will directly affect whether the molding can be successful.
  • the molding table includes a disassembly handle, a hydraulic locking piston, a hydraulic chamber, a pressing piston, and a universal ball head. Loosen the screws before leveling, and tighten the screws when the forming table is lowered to the lower limit switch.
  • the UV ultraviolet lamp box module is used as the LCD imaging light source. As shown in Figure 3, the module includes three parts, namely the lamp box, UV lamp and heat-dissipating aluminum sheet.
  • the LCD liquid crystal screen is placed above the module to form a sealed space to prevent the leakage of ultraviolet light.
  • the interior of the light box is made of mirror stainless steel, which is conducive to the reflection of ultraviolet light. Since the UV lamp works for a long time, it will produce a lot of heat, so a heat dissipation aluminum sheet is installed at the bottom for heat dissipation.
  • the design principle of the liquid tank is to consider the size first. In order to save the photosensitive resin, the best size is slightly larger than the molding table. As shown in Figure 4, the release film is installed at the bottom of the liquid tank, and the release film is clamped with metal clips to prevent liquid leakage, and then installed on the liquid tank to keep the release film in a tight state.
  • Release film material is fluorinated ethylene propylene copolymer (Fluorinated Ethylene Propylene, FPE), this material has good light conductivity, and the UV light transmission rate reaches 95%, which can shorten the curing time; secondly, the material has good wear resistance, low friction coefficient, and is not easy to deform after repeated stripping.
  • the PCB control board includes the main controller MCU, DC power supply, motor control module, sensor control and LED light switch module, etc., as shown in Figure 5.
  • the Raspberry Pi replaces the PC as the host computer to control and interact with the MCU. It connects the slice display LCD screen through MicHDMI, and connects the control screen through DSI to realize offline molding.
  • the hardware control system uses two voltages for power supply, the UV lamp directly uses DC29.4V power supply, and other modules use DC power supply step-down 5V power supply.
  • the MCU uses PWM to control the motor drive, and the motor drive controls the rotation of the motor. Control the sensor and LED switch module through GPIO.
  • an optocoupler isolation circuit is designed to isolate the interference source from the easy-to-interference part, so as to achieve the purpose of isolating field interference.
  • the main method is to cut off the path of noise interference through isolation devices.
  • the hardware main control system adopts the separate design of each module, and then uses the cable to connect each module. This scheme design enables easy replacement or maintenance of equipment during experiments.
  • the hardware main control system includes main control chip, function board and sensor board.
  • the main control chip is used to receive instructions from the host computer and analyze them and send them to the function board and sensor board.
  • the function board is used to control the motor movement and UV lamp, and the sensor board is used to control the limit switch.
  • the present invention uses the KEAZ128 model micro-control chip of NXP, which is based on ARM-Cortex M0+ core, with a core frequency of 48MHz, is widely used in the field of automotive electronics, and the chip performance is stable. It is packaged in LQFP for easy soldering.
  • the specific performance of the chip is shown in Table 3-1.
  • the control system uses peripheral resources such as general-purpose input/output (GPIO), flexible timer (FTM), universal asynchronous transceiver transmitter (UART), keyboard interrupt (KBI) provided by KEA chip to realize sensor signal acquisition, information transmission and Control of each executive component.
  • peripheral resources such as general-purpose input/output (GPIO), flexible timer (FTM), universal asynchronous transceiver transmitter (UART), keyboard interrupt (KBI) provided by KEA chip to realize sensor signal acquisition, information transmission and Control of each executive component.
  • GPIO general-purpose input/output
  • FTM flexible timer
  • UART universal asynchronous transceiver transmitter
  • KBI keyboard interrupt
  • the isolation circuit includes a motor control isolation circuit and a sensor signal input isolation circuit.
  • the motor will generate a backlash current at the moment of braking and stopping, which will affect the signal output of the main control chip. Therefore, a motor control isolation circuit is designed between the main control chip and the motor. Also design a sensor signal input isolation circuit between the sensor and the main control chip to prevent signal interference.
  • the selected model is 6N137 optocoupler, its conversion rate is as high as 10Mbits/s, and the collector is open-circuit output.
  • the PWM frequency input by the main control chip is 8KHz, so this type of optocoupler is sufficient for use.
  • the motor control isolation circuit is shown.
  • PTC5 is the output PWM signal pin
  • PTD2 is the output motor rotation direction signal pin. Both signal pins are connected to input pin 3 of 6N137 and output from input pin 6. .
  • the upper and lower limit pins are set as GPIO and set as input.
  • the wiring method adopts normally open wiring, connect the power supply at the back end of the optocoupler to the power supply of the limit switch, and connect the signal pin to the normally open pin.
  • normally open is high level, the light is blocked and changes to low level.
  • the LCD screen of the Japanese brand JDI is TFTMD089030.
  • the LCD screen does not have a backlight panel at the factory, which is convenient for use in the light curing molding system. If you buy an LCD screen with a backlight panel, you need to remove the backlight panel.
  • the size of the LCD screen determines the molding area, but the larger the better, when using a larger size LCD screen, the difficulty of film removal and heat dissipation also increase accordingly.
  • Using an 8.9-inch screen can basically meet the requirements of most practical applications.
  • Another factor that needs to be considered is the working temperature range.
  • the currently used UV lamp panel is 120W, and the temperature reaches 60°C to 70°C under long-term working conditions. This temperature exceeds the normal operating temperature range of the LCD screen, resulting in a short service life of the LCD screen, so heat dissipation measures need to be added to improve the service life of the LCD screen.
  • the TFTMD089030 LCD screen has been bound with a driver IC with a model number of R69429.
  • the selected motor of the present invention is 42 stepper motors and motor drivers thereof.
  • the step angle of this stepper motor is 1.8°, that is, the motor driver can drive the stepper motor to rotate 1.8° after receiving a pulse.
  • the drive subdivision of the stepper motor driver can be selected as 2n (1 ⁇ n ⁇ 5), the drive subdivision selected in this project is 8, which can be described as the motor driver can drive the motor to rotate an angle of 1.8° after receiving a pulse, but this Then subdivide 1.8° into 8 equal parts, which is 0.225°.
  • the lead of the screw rod is 4mm, that is, the distance that the motor drives the screw rod to rotate one circle and the forming table moves is 4mm. From these necessary parameters, the pulse equivalent can be calculated according to the formula (3.1), that is, how many pulses are needed for every 1mm movement of the molding table.
  • ⁇ represents the pulse equivalent
  • ⁇ represents the step angle of the stepping motor
  • ⁇ represents the driving subdivision set by the motor driver
  • ⁇ represents the lead of the screw. It can be calculated that the pulse equivalent used in the present invention is 400 pulses/mm.
  • the limit switch includes an upper limit switch and a lower limit switch, which are used to limit the range of movement of the molding table.
  • the limit switch is selected as Omron lead-out type photoelectric switch EE-SX671-WR.
  • the limit switch adopts the normally open mode. When the stopper reaches the light groove, the limit switch detects a signal and sends it to the main control chip, which stops the motor. When installing the limit switch, you need to pay attention to the installation position of the lower limit switch. When the stopper touches the limit switch, the distance between the forming surface and the release film maintains a fixed value. This value is usually one slice. layer thickness.
  • the power supply voltage is DC29.4V, so the voltage needs to be reduced to DC5V for other components to use.
  • the module adopts the chip LM2596S, the conversion efficiency reaches 92%, and the working frequency is 65KHz.
  • the input terminal of the module is connected to the positive and negative poles of the DC29.4V power supply, and the output voltage is DC5V connected to the terminal for use by other modules.
  • the LED switch module is used to control the light and dark state of the UV backlight panel, and the signal terminal is connected to the GPIO pin of the main control chip to control the conduction state.
  • the input terminal is connected to the power supply voltage, the output terminal is connected to the UV lamp, and the controllable power is up to 400W.
  • the power of the UV backlight panel designed by the present invention is 120W, so this module is sufficient for use.
  • the ultraviolet light parallel backlight module includes a bottom plate and ultraviolet LED lamp beads.
  • the LED lamp beads adopt Seoul 3535 quartz lens lamp beads, the wavelength is 405nm, and the light emitting angle of the lens is 30 degrees. In order to ensure a good molding effect, it should be noted that the ultraviolet light needs to be evenly distributed on the LCD screen when projected on it.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
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  • Optics & Photonics (AREA)
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  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)

Abstract

本发明提供了一种基于光固化的液面连续成型系统，包括：滑动导轨；滚柱丝杆；成型台面；步进电机；PCB控制板；液槽；UV灯罩；树莓派及控制屏；电机驱动器；接线端子；LCD屏幕；UV紫外光平行光源；其中，成型台面固定于液槽上，滑动导轨、滚柱丝杆、步进电机、液槽、UV灯罩固定于主体板上；电机驱动器分别连接步进电机、PCB控制板，并通过接线端子连接树莓派及控制屏；所述LCD屏幕位于液槽底部，UV紫外光平行光源位于UV灯罩内。本发明定位精度高、LCD投射UV光的均匀度高。

Description

一种基于光固化的液面连续成型系统 技术领域
本发明涉及智能快速成型技术领域，具体涉及一种基于光固化的液面连续成型系统。
 背景技术
基于光固化的快速成型技术是将紫外光投射到液态光敏树脂中，从而使树脂逐层连续固化。数字光处理（DLP）成型技术的成型尺寸有限、设备价格高和镜头畸变等问题制约该技术的发展，因此采用液晶显示屏（LCD）作为区域选择型透光设备，可用于制造尺寸较大且精度较高的零件。但成型效率与成型质量难以协调是限制LCD成型技术发展的主要因素，因此需要寻找二者的调和策略。
 技术解决方案
本发明的目的是通过以下技术方案实现的。
本发明提供了一种基于光固化的液面连续成型系统，包括：
滑动导轨；滚柱丝杆；成型台面；步进电机；PCB控制板；液槽；UV灯罩；树莓派及控制屏；电机驱动器；接线端子；LCD屏幕；UV紫外光平行光源；
其中，成型台面固定于液槽上，滑动导轨、滚柱丝杆、步进电机、液槽、UV灯罩固定于主体板上；电机驱动器分别连接步进电机、PCB控制板，并通过接线端子连接树莓派及控制屏；
所述LCD屏幕位于液槽底部，UV紫外光平行光源位于UV灯罩内；
所述PCB控制板包括主控制器、DC电源、电机控制模块、传感器和LED灯开关模块，所述主控制器使用PWM控制所述电机驱动器，电机驱动器控制电机转动；所述主控制器通过GPIO控制传感器和LED开关模块。
优选地，进一步包括散热铝片，所述散热铝片位于UV灯罩背面。
优选地，进一步包括风扇，所述风扇安装于电机驱动器上。
优选地，所述滚柱丝杆能够带动成型台面上抬与下降。
优选地，进一步包括离型膜，安装在液槽底部并处于紧绷状态。
优选地，所述主控制器包括主控芯片、功能板和传感器板；所述主控芯片用于接收上位机指令并解析发送给功能板和传感器板，功能板用于控制电机运动和UV灯，传感器板用于控制成型台面的限位开关，所述传感器安装于所述传感器板上。
优选地，进一步包括限位开关，包括上限位开关与下限位开关，用于限制成型台面运动范围。
优选地，进一步包括隔离电路，所述隔离电路包括电机控制隔离电路与传感器信号输入隔离电路；所述电机控制隔离电路在主控芯片与步进电机之间，传感器信号输入隔离电路在传感器与主控芯片之间。
优选地，所述LED开关模块用于控制UV背光板的亮暗状态，信号端连接主控芯片GPIO引脚，用于控制导通状态，输入端接电源电压，输出端接UV灯。
 有益效果
本发明的优点在于：本发明一种基于光固化的液面连续成型系统，定位精度高、LCD投射UV光的均匀度高。
 附图说明
通过阅读下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本发明的限制。而且在整个附图中，用相同的参考符号表示相同的部件。在附图中：
附图1示出了根据本发明实施方式的一种基于光固化的液面连续成型系统结构示意图。
附图2示出了根据本发明实施方式的成型台面结构示意图。
附图3示出了根据本发明实施方式的UV灯罩结构示意图。
附图4示出了根据本发明实施方式的液槽结构示意图。
附图5示出了根据本发明实施方式的硬件控制系统示意图。
附图6示出了根据本发明实施方式的电机控制隔离电路图。
附图7示出了根据本发明实施方式的传感器信号输入隔离电路图。
 本发明的实施方式
下面将参照附图更详细地描述本公开的示例性实施方式。虽然附图中显示了本公开的示例性实施方式，然而应当理解，可以以各种形式实现本公开而不应被这里阐述的实施方式所限制。相反，提供这些实施方式是为了能够更透彻地理解本公开，并且能够将本公开的范围完整的传达给本领域的技术人员。
本发明对机械及硬件平台的整体设计进行了详细介绍，首先给出了机械关键部件的设计原则。包括成型台面的易校准、UV灯罩的密闭性与散热性和液槽的设计要点。接着阐述了硬件控制系统的设计方法与相关硬件选型，其中主要包括主控芯片的资源划分与隔离电路设计，详细介绍了硬件选型的技术指标。
1 机械部结构设计
机械结构的关键部件要求质量稳定、精度高，因此采用CNC工艺制造。机械整体采用铝件加工，仅有遮光罩采用防UV紫外光外溢的亚克力材料。如图1所示，LCD屏幕在液槽底部不可见，UV紫外光平行光源在UV灯罩内不可见。其他各部件均已标记出来。
1-滑动导轨；2-滚柱丝杆；3-成型台面；4-步进电机；5-散热铝片；6-PCB控制板；7-液槽；8-UV灯罩；9-树莓派及控制屏；10-风扇；11-电机驱动器；12-接线端子。
其中，成型台面固定于液槽上，滑动导轨、滚柱丝杆、步进电机、液槽、UV灯罩固定于主体板上，散热铝片位于UV灯罩背面；电机驱动器分别连接步进电机、PCB控制板，并通过接线端子连接树莓派及控制屏；风扇安装于电机驱动器上。
1.1 机械关键部件设计原则
机械各个部件需要根据LCD光固化特点来设计。主要需关注的部件是成型台面、UV灯罩、液槽。本节针对这几个部件着重分析其设计要点与作用。
1.成型台面
成型台面的校准是光固化快速成型中较为棘手的问题，对于新手在打印时很难使用较为专业的工具调平。因此本发明设计的成型台面采用液压平衡自校准技术，能够简单方便的完成校准，对新手用户十分友好。
丝杆转动带动成型台面上抬与下降，成型台面要求与离型膜之间保持平行，其距离与切片的厚度保持一致。成型过程中，如果离型膜与成型台面不平行，则会导致光敏树脂固化厚度不均匀、脱膜失败、无法粘接在成型台面等问题。因此成型台面与离型膜是否平行会直接影响成型是否能够成功。
另外成型台面是需要经常拆卸，所以就需要经常调平，调平方式的设计需要满足操作简单、精度高的特点。如图2所示，成型台面包括拆装手柄、液压锁紧活塞、液压腔、压紧活塞、万向球头。调平前松开螺丝，待成型台面下降到下限位开关处拧紧螺丝即可。
2.UV灯罩
UV紫外光灯盒模块作为LCD成像光源，如图3所示，该模块包括三部分，分别是灯盒、UV灯和散热铝片。LCD液晶屏幕置于该模块上方，组成一个密封空间，防止紫外光外泄。灯盒内部采用镜面不锈钢，有利于紫外光反射。由于UV灯长时间工作会产品大量的热量，因此在底部安装散热铝片用于散热。
3.液槽设计
液槽的设计原则首先是考虑尺寸问题，为了节省光敏树脂最佳的尺寸是稍大于成型台面即可。如图所示4所示，离型膜安装在液槽底部，使用金属夹片夹住离型膜，防止漏液，然后安装在液槽上，使离型膜处于紧绷状态。离型膜材质为氟化乙烯丙烯共聚物（Fluorinated Ethylene Propylene，FPE），该材料导光性好，UV光通过率达到95%，可使固化时间更短；其次该材料耐磨性好，摩擦系数低，反复脱膜不易产生形变。
2 硬件控制系统设计
PCB控制板包括主控制器MCU、DC电源、电机控制模块、传感器控制和LED灯开关模块等，如图5所示。树莓派代替PC作为上位机控制与MCU交互，通过MicHDMI连接切片显示LCD屏，通过DSI连接控制屏可以实现脱机成型。
硬件控制系统采用两种电压供电，分别是UV灯直接使用DC29.4V电源，其他模块均使用DC电源降压的5V电源。MCU使用PWM控制电机驱动，电机驱动控制电机转动。通过GPIO控制传感器和LED开关模块。为达到精准控制，设计光耦隔离电路把干扰源与易干扰部分隔离开来，从而达到隔离现场干扰的目的，主要的手段是通过隔离器件把噪声干扰的路径切断。
2.1 主控制器硬件系统设计
硬件主控制系统采用各个模块分离设计，再使用排线连接各个模块。这种方案设计能够在实验中易于更换或维修设备。硬件主控制系统包括主控芯片、功能板和传感器板。主控芯片用于接收上位机指令并解析发送给功能板和传感器板，功能板用于控制电机运动和UV灯，传感器板用于控制限位开关。
由于微控制器的种类及其繁杂，不同的公司有不同芯片，即使同一家的公司的芯片也会有不同的种类和系列。因此，为整个控制系统选择核心处理芯片是一项重要大的工作。要求主控芯片易调试，并且具有良好的拓展性。经过选型，本发明使用恩智浦公司的KEAZ128型号微控制芯片，该芯片基于ARM-Cortex M0+内核，内核频率为48MHz，在汽车电子领域广泛使用，芯片性能稳定。采用LQFP封装，便于焊接。芯片具体性能如表3-1所示。
Figure dest_path_image001
1.主控芯片引脚分配
控制系统使用KEA芯片提供的通用输入/输出（GPIO）、弹性定时器（FTM）、通用异步收发传输器（UART）、键盘中断（KBI）等外设资源，实现了传感器信号采集、信息传递以及对各执行部件的控制。根据各个执行部件需要，设计主控芯片引脚资源的分配，如表3-2所示。
Figure dest_path_image003
2.隔离电路设计
隔离电路包括电机控制隔离电路与传感器信号输入隔离电路。电机在制动和停止瞬间会产生反噬电流，影响主控芯片信号输出，因此在主控芯片与电机之间设计电机控制隔离电路。同样在传感器与主控芯片之间设计传感器信号输入隔离电路防止信号干扰。
在本发明中，选用型号为6N137光耦合器，其转换速率高达10Mbits/s，集电极开路输出。主控芯片输入的PWM频率为8KHz，因此该型号光耦合器足够满足使用。如图6所示为电机控制隔离电路，PTC5为输出PWM信号引脚，PTD2为输出电机转动方向信号引脚，这两个信号引脚都连接6N137的输入引脚3并由输入引脚6输出。
上下限位引脚设置为GPIO，并且设置为输入。如图7所示，接线方式采用常开接线，将光耦合器后端的电源与限位开关的电源相连，信号引脚与常开引脚相连，在限位开关未被触发，常开为高电平，光线受到阻挡转变为低电平。
2.3 硬件模块选型
根据机械执行部件任务需要，需要选择适合的硬件模块。本节针对主要的硬件模块做进一步阐述，其中包括LCD液晶屏幕、步进电机、限位开关、降压稳压模块、LED开关模块和紫外光平行背光源。
1. LCD液晶屏幕
LCD液晶屏选择日本品牌JDI型号为TFTMD089030，该液晶屏幕出厂没有背光板，方便在光固化成型系统中使用，如果购买到带背光板的液晶屏幕，还需要拆卸背光板。
液晶屏幕的尺寸大小决定了成型面积，但并不是越大越好，当使用更大尺寸液晶屏幕时，脱膜难度与散热难度也随着相应地增加。使用8.9寸屏幕基本可以满足大多实际应用的要求。另外一点需要考虑的因素是工作温度范围，当前使用的UV灯盘为120W，在长时间工作情况下温度达到60℃～70℃。该温度超出了液晶屏幕的正常工作温度范围，导致液晶屏幕的使用寿命短，因此需要增加散热措施来提高液晶屏幕的使用寿命。
为了保护液晶屏幕表面不易损伤，需要在屏幕表面贴上钢化保护玻璃，该钢化保护玻璃需要满足高透光性、高强度和丝印区域不易透光等特点。另外需要选择一款适应的液晶屏幕驱动板，TFTMD089030型号的液晶屏幕已经绑定了型号为R69429的驱动IC。
2.步进电机选择
本发明所选择的电机为42步进电机及其电机驱动器。该款步进电机的步进角为1.8°，即电机驱动器接收到一个脉冲可以驱动步进电机转动1.8°。步进电机驱动器的驱动细分可选为2n (1≤n≤5)，本项目中选择的驱动细分为8，可以描述为电机驱动器接收到一个脉冲可以驱动电机转动1.8°角度，但此时再将1.8°细分8等分，即为0.225°。丝杆的导程为4mm，即电机带动丝杆转动一圈成型台面移动的距离为4mm。由这些必要的参数可以根据公式(3.1)计算出脉冲当量，即成型台面每移动1mm需要多少个脉冲。
Figure dest_path_image004
其中δ表示脉冲当量，α表示步进电机的步进角，η表示电机驱动器设置的驱动细分，ρ表示丝杆的导程。可以计算出本发明使用的脉冲当量为400脉冲/mm。
3.限位开关
限位开关包括上限位开关与下限位开关，用于限制成型台面运动范围。限位开关选型为欧姆龙导线引出型光电开关EE-SX671-WR。限位开关采用常开模式，当挡片到达光槽处，限位开关监测到信号发给主控芯片，主控芯片使电机停止。安装限位开关需要注意下限位开关的安装位置，要保证挡片触碰到限位开关时，此时成形态面与离型膜之间的距离保持一个定值，这个定值通常是切片一层厚度。
4.降压稳压模块
电源电压为DC29.4V，因此需要将电压降到DC5V以供其他部件使用。该模块采用芯片LM2596S，转换效率达92%，工作频率为65KHz。该模块输入端接DC29.4V电源正负极，输出电压为DC5V接到接线端子处，以供其他模块使用。
5.LED开关模块
LED开关模块用于控制UV背光板的亮暗状态，信号端连接主控芯片GPIO引脚，用于控制导通状态。输入端接电源电压，输出端接UV灯，可控功率达400W。本发明设计的UV背光板的功率为120W，所以该模块足够满足使用。
6.紫外光平行背光源
紫外光平行背光源模组包括底板和紫外光LED灯珠。LED灯珠采用首尔3535石英透镜灯珠，波长为405nm，透镜的发光角度为30度。为了保证良好的成型效果，需要注意的是，紫外光投射到LCD液晶屏幕上需要光强分布均匀。
 
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (9)

  1. 一种基于光固化的液面连续成型系统，其特征在于，包括：滑动导轨；滚柱丝杆；成型台面；步进电机；PCB控制板；液槽；UV灯罩；树莓派及控制屏；电机驱动器；接线端子；LCD屏幕；UV紫外光平行光源；其中，成型台面固定于液槽上，滑动导轨、滚柱丝杆、步进电机、液槽、UV灯罩固定于主体板上；电机驱动器分别连接步进电机、PCB控制板，并通过接线端子连接树莓派及控制屏；所述LCD屏幕位于液槽底部，UV紫外光平行光源位于UV灯罩内；所述PCB控制板包括主控制器、DC电源、电机控制模块、传感器和LED灯开关模块，所述主控制器使用PWM控制所述电机驱动器，电机驱动器控制电机转动；所述主控制器通过GPIO控制传感器和LED开关模块。
  2. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，进一步包括散热铝片，所述散热铝片位于UV灯罩背面。
  3. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，进一步包括风扇，所述风扇安装于电机驱动器上。
  4. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，所述滚柱丝杆能够带动成型台面上抬与下降。
  5. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，进一步包括离型膜，安装在液槽底部并处于紧绷状态。
  6. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，所述主控制器包括主控芯片、功能板和传感器板；所述主控芯片用于接收上位机指令并解析发送给功能板和传感器板，功能板用于控制电机运动和UV灯，传感器板用于控制成型台面的限位开关，所述传感器安装于所述传感器板上。
  7. 根据权利要求1所述的一种基于光固化的液面连续成型系统，其特征在于，进一步包括限位开关，包括上限位开关与下限位开关，用于限制成型台面运动范围。
  8. 根据权利要求6所述的一种基于光固化的液面连续成型系统，其特征在于，进一步包括隔离电路，所述隔离电路包括电机控制隔离电路与传感器信号输入隔离电路；所述电机控制隔离电路在主控芯片与步进电机之间，传感器信号输入隔离电路在传感器与主控芯片之间。
  9. 根据权利要求6所述的一种基于光固化的液面连续成型系统，其特征在于，所述LED开关模块用于控制UV背光板的亮暗状态，信号端连接主控芯片GPIO引脚，用于控制导通状态，输入端接电源电压，输出端接UV灯。
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