阅读说明：本技术 一种面曝光3d打印设备的断点续打方法 (Breakpoint continuous printing method of surface exposure 3D printing equipment ) 是由 郭文华 贺晨龙 马耀军 高嘉保 田艳彬 于 2020-11-06 设计创作，主要内容包括：本发明公开了一种面曝光3D打印设备的断点续打方法,该方法将断点续打方法集成至设备的控制方法中,根据上位机与下位机之间的交互逻辑关系,将实现断点续打所需操作加入整个系统的运行中。本发明针对面曝光技术实现了断点续打功能,实现方法简单、可靠。相比于不具有断点续打功能的面曝光打印设备,断点续打功能能够显著提高打印成功率,节约打印成本；使用上位机记录Z轴行程,针对每台设备的不同状况实现了个性化定制；针对中断层打印状态进行判断,根据打印中断时当前层的照射时间来判断是否需要对该层进行重新固化,提高了断点层的打印质量,降低了断点续打时发生错层的可能。(The invention discloses a breakpoint continuous printing method of a surface exposure 3D printing device. The invention realizes the breakpoint continuous printing function aiming at the surface exposure technology, and the realization method is simple and reliable. Compared with the surface exposure printing equipment without the breakpoint continuous printing function, the breakpoint continuous printing function can obviously improve the printing success rate and save the printing cost; the upper computer is used for recording the Z-axis stroke, and personalized customization is realized for different conditions of each device; the printing state of the interrupted layer is judged, whether the layer needs to be cured again or not is judged according to the irradiation time of the current layer when the printing is interrupted, the printing quality of the breakpoint layer is improved, and the possibility of wrong layers when the breakpoint continues to play is reduced.)

1. A breakpoint continuous printing method of a surface exposure 3D printing device is characterized in that the breakpoint continuous printing method is integrated into a control method of the device, and operations required for achieving breakpoint continuous printing are added into running of a whole system according to an interactive logic relationship between an upper computer and a lower computer.

2. The breakpoint continuous printing method of the surface exposure 3D printing device according to claim 1, wherein the specific operations executed by the device operation key steps are as follows:

step one, powering on a lower computer of the equipment, connecting a mobile end upper computer with the lower computer, and after the connection is successful, sending an upward movement instruction to the lower computer by the upper computer, wherein the format is ux and x, a first letter represents that the forming plate needs to be subjected to ascending movement, a second digit x represents the number of breakpoint layers of breakpoint continuous punching, and a third digit x, namely the first digit after comma separation represents the pulse number required by the movement Z-axis total stroke of the forming plate;

secondly, operating the upper computer of the mobile terminal by a user, clicking to start printing after a printing model is selected and printing parameters are set, and sending a downward movement instruction tx to the lower computer by the upper computer, wherein x is 1, 2, 3 and 4 which are multiples of a base layer thickness value of 0.05 respectively; the forming plate moves downwards to a lower limit position; at the moment, the lower computer returns to the upper computer to the hz, wherein the z represents the pulse number required by the stepping motor when the stepping motor runs from the upper limit position to the lower limit position; the upper computer stores the pulse number Z required by the Z-axis motion into a variable Z _ totl; and storing the variable in an upper computer; the movement stroke of the Z axis of the equipment is used for calculating the position of the forming plate when the break point continues to be beaten;

step three, the equipment starts printing, and the upper computer controls the light source to display the cutting picture of the current layer and stores the layer number of the current layer for restoring the printed layer number when the breakpoint continues printing; after each layer of sliced image is irradiated for a set curing time, the upper computer sends a control instruction f to the lower computer, and the lower computer controls the forming plate to move for a layer thickness distance to perform curing of the next layer; simultaneously, the upper computer records the actual curing time of the layer; after the last layer of the model is displayed, the upper computer sends an instruction u to the lower computer, and the forming plate moves upwards to the upper limit switch position;

step four, if the device is interrupted in the printing process, the upper computer records that the actual curing time of the layer is less than the curing time of each layer which is initially set; before the next printing is started, the upper computer prompts a user whether to continue printing from the current position at a breakpoint or to reprint the whole model; and if the breakpoint continuous printing is selected, judging whether the current breakpoint layer needs to be printed again according to whether the actual curing time of the current layer exceeds half of the set curing time.

3. The breakpoint continuous printing method of the surface exposure 3D printing device according to claim 2, wherein in the first step, the upper computer of the mobile terminal is connected with the lower computer through a Bluetooth protocol.

4. The breakpoint continuous printing method of a surface exposure 3D printing device according to claim 2, wherein in the first step, the second digit and the third digit are both zero at the time of the first printing, so that the command is u0, 0; under the command, the Z axis drives the forming plate to move upwards to an upper limit position, the lower computer replies a command p to the upper computer at the moment, the command indicates that the forming plate moves upwards to the upper limit switch position, and at the moment, a variable Z _ total for recording the pulse number required by the Z axis stroke in the upper computer is set to be zero.

5. The breakpoint continuous printing method of the surface exposure 3D printing device according to claim 2, wherein in step three, if the printing process is not interrupted, the process is repeated all the time, and the curing time of each layer is counted again when the next layer is cured.

6. The breakpoint continuous printing method of the surface exposure 3D printing device according to claim 2, characterized in that in the fourth step, after the upper computer and the lower computer are successfully connected, the upper computer sends an upward movement instruction to the lower computer in a format of ux, x, wherein two digits after the instruction respectively represent a breakpoint layer number where interruption occurs and a total Z-axis stroke recorded in a variable Z _ total; and according to the two pieces of information and the judgment of whether the layer needs to be solidified again, the lower computer calculates the pulse number required by moving to the breakpoint and maintaining, and controls the light source to display the slice image of the breakpoint layer, thereby realizing breakpoint continuous striking.

Technical Field

The invention belongs to the technical field of 3D printing, and particularly relates to a breakpoint continuous printing method of surface exposure 3D printing equipment.

Background

The surface exposure technology is translated into Digital Light Processing (DLP), which is an additive manufacturing technology that irradiates a photosensitive resin material with a surface Light source to cause a photocuring reaction and then accumulates the photosensitive resin material layer by layer. First, a set of slice images consisting of cross-sectional images of the model is obtained using a series of parallel planes intersecting the printed model. Each slice is then converted into a two-dimensional mask image that is projected onto the photocurable liquid surface for curing the current layer of the layer. And finally, the forming platform moves for a distance of one slice thickness to continue curing the next layer, and the steps are repeated until the whole model is cured layer by layer.

Since the surface exposure printing technology needs to consume a long time, the printing is stopped and the printed piece is scrapped due to the possible occurrence of equipment power failure, control logic errors, material exhaustion or manual interruption in the curing process of each layer of slice image. For the area exposure technique, in order to be able to resume the printing process from the interrupted position, it is necessary to calculate the current position of the device Z-axis movement from the current number of print layers of the device and the layer thickness of the model slice. Conventionally, in order to acquire the current printing state of the apparatus, first, the user needs to manually measure the Z-axis movement distance when the interruption occurs. Then, the current number of printing layers is calculated according to the model slice layer thickness. Finally, the device redisplays the model slice from the middle slice by modifying the model slice file. Such an operation needs a user with experience to complete, and improper setting may cause the accuracy of the model at the break point to decrease or cause printing failure. Therefore, an intelligent breakpoint continuous printing function needs to be added to the device to ensure that the device can resume the printing process after the interruption occurs, so that the success rate of printing is improved, and the waste of time and materials is avoided.

The existing breakpoint continuous printing method is mainly implemented for Fused Deposition (FDM) technology. Since the model slice of the FDM equipment uses the G code common to the machine tool, and the code completely contains the current position coordinate information of the printing head of the equipment, the state of the equipment in the interruption can be found by measuring the Z-axis height of the equipment in the interruption and comparing the G code of the model slice file. When the printing is restarted, the apparatus can be caused to continue to start printing from the breakpoint by deleting the G code before the interruption occurred. On the basis of the manual operation method, automatic breakpoint continuous printing can be realized by recording the current state of the equipment [1 ]. Besides adding a breakpoint continuous printing software method into a control system of the equipment, a chip with a power-down storage function can be used for recording the current printing state, or a standby power supply is used for continuing the printing work after the equipment is powered off [2 ]. However, these methods increase the cost of the equipment, and cannot flexibly implement breakpoint continuous printing according to the requirements of users, such as feeding, secondary printing, etc., and the equipment needs to be manually paused.

The model slice file for the surface exposure technology only contains model layer number information, and a breakpoint continuous printing method for the FDM technology cannot be directly used.

Reference to the literature

[1]3D printer breakpoint continuous printing method and 3D printer

[2] 3D printer power-off continuous printing device and operation method

[3] The multifunctional desktop level 3D printer is constructed and actually measured [ J ] information technology, 2018(04) 23-26.

Disclosure of Invention

The invention aims to provide a breakpoint continuous printing method of a surface exposure 3D printing device, aiming at the defects of the existing surface exposure technology.

The invention is realized by adopting the following technical scheme:

a breakpoint continuous printing method of a surface exposure 3D printing device integrates the breakpoint continuous printing method into a control method of the device, and adds the operation required by breakpoint continuous printing into the operation of the whole system according to the interactive logic relationship between an upper computer and a lower computer.

The invention is further improved in that the specific operations executed in the key steps of equipment operation are as follows:

step one, powering on a lower computer of the equipment, connecting a mobile end upper computer with the lower computer, and after the connection is successful, sending an upward movement instruction to the lower computer by the upper computer, wherein the format is ux and x, a first letter represents that the forming plate needs to be subjected to ascending movement, a second digit x represents the number of breakpoint layers of breakpoint continuous punching, and a third digit x, namely the first digit after comma separation represents the pulse number required by the movement Z-axis total stroke of the forming plate;

secondly, operating the upper computer of the mobile terminal by a user, clicking to start printing after a printing model is selected and printing parameters are set, and sending a downward movement instruction tx to the lower computer by the upper computer, wherein x is 1, 2, 3 and 4 which are multiples of a base layer thickness value of 0.05 respectively; the forming plate moves downwards to a lower limit position; at the moment, the lower computer returns to the upper computer to the hz, wherein the z represents the pulse number required by the stepping motor when the stepping motor runs from the upper limit position to the lower limit position; the upper computer stores the pulse number Z required by the Z-axis motion into a variable Z _ totl; and storing the variable in an upper computer; the movement stroke of the Z axis of the equipment is used for calculating the position of the forming plate when the break point continues to be beaten;

step three, the equipment starts printing, and the upper computer controls the light source to display the cutting picture of the current layer and stores the layer number of the current layer for restoring the printed layer number when the breakpoint continues printing; after each layer of sliced image is irradiated for a set curing time, the upper computer sends a control instruction f to the lower computer, and the lower computer controls the forming plate to move for a layer thickness distance to perform curing of the next layer; simultaneously, the upper computer records the actual curing time of the layer; after the last layer of the model is displayed, the upper computer sends an instruction u to the lower computer, and the forming plate moves upwards to the upper limit switch position;

step four, if the device is interrupted in the printing process, the upper computer records that the actual curing time of the layer is less than the curing time of each layer which is initially set; before the next printing is started, the upper computer prompts a user whether to continue printing from the current position at a breakpoint or to reprint the whole model; and if the breakpoint continuous printing is selected, judging whether the current breakpoint layer needs to be printed again according to whether the actual curing time of the current layer exceeds half of the set curing time.

The invention has the further improvement that in the step one, the upper computer of the mobile terminal is connected with the lower computer through a Bluetooth protocol.

In a further development of the invention, in step one, at the time of the first printing, the second digit and the third digit are both zero, so that the command is u0, 0; under the command, the Z axis drives the forming plate to move upwards to an upper limit position, the lower computer replies a command p to the upper computer at the moment, the command indicates that the forming plate moves upwards to the upper limit switch position, and at the moment, a variable Z _ total for recording the pulse number required by the Z axis stroke in the upper computer is set to be zero.

A further improvement of the invention is that in step three, if the printing process is not interrupted, the process is repeated, and the curing time for each layer is re-counted as the next layer cures.

The further improvement of the invention is that in the fourth step, after the upper computer and the lower computer are successfully connected, the upper computer sends an upward movement instruction to the lower computer, the format is ux and x, wherein two digits after the instruction respectively represent the layer number of the interrupted breakpoint and the total stroke of the Z axis recorded in the variable Z _ total; and according to the two pieces of information and the judgment of whether the layer needs to be solidified again, the lower computer calculates the pulse number required by moving to the breakpoint and maintaining, and controls the light source to display the slice image of the breakpoint layer, thereby realizing breakpoint continuous striking.

The invention has at least the following beneficial technical effects:

according to the breakpoint continuous printing method of the surface exposure 3D printing equipment, provided by the invention, under the condition that the lower computer is powered off, has an operation error or is manually subjected to pause operation, according to the equipment operation state recorded by the upper computer when the interruption occurs, the equipment can be ensured to be continuously printed from the last interrupted position after being recovered to be normal again, the printing success rate is improved, and the working hours and the material cost are saved; in the initialization process of the equipment, the lower computer sends the Z-axis stroke value to the upper computer for storage in a communication mode, so that the problem of reduction of breakpoint continuous beating precision caused by change of the Z-axis stroke value along with the use of the equipment is avoided; the upper computer with the data storage function is used for recording breakpoint information instead of a special hardware chip, so that the hardware cost is saved; in the process of curing the current layer by the light source, the upper computer judges whether the current layer needs to be cured again when the equipment is recovered from the breakpoint to print by recording the curing time of the current layer when the interruption occurs, so that the curing effect of the breakpoint recovery layer is improved.

Therefore, the invention realizes the breakpoint continuous printing function aiming at the surface exposure technology, and the realization method is simple and reliable. Compared with the surface exposure printing equipment without the breakpoint continuous printing function, the breakpoint continuous printing function can obviously improve the printing success rate and save the printing cost; the upper computer is used for recording the Z-axis stroke, and personalized customization is realized for different conditions of each device; the printing state of the interrupted layer is judged, whether the layer needs to be cured again or not is judged according to the irradiation time of the current layer when the printing is interrupted, the printing quality of the breakpoint layer is improved, and the possibility of wrong layers when the breakpoint continues to play is reduced.

Drawings

Fig. 1 is an interactive logic diagram of an upper computer and a lower computer of the device.

Fig. 2 is a flowchart of a breakpoint continuous printing method of a surface exposure 3D printing apparatus according to the present invention.

Detailed Description

The invention is further described below with reference to the following figures and examples.

The invention is described for a downward-irradiation type surface exposure device, a device light source is arranged at the lower part of the device, the bottom of a resin tank is irradiated upwards from the lower part of the resin tank, and a forming plate is driven by a Z axis to move upwards to carry out layer-by-layer curing. For the upward-lighting type equipment, only the Z-axis movement direction and the positions of the upper limit switch and the lower limit switch need to be changed. The upper computer is a mobile device with a Bluetooth communication module and is responsible for controlling a light source to display a slicing image, sending a motion instruction to control the lower computer to move and obtaining the motion state information of the lower computer required by realizing a breakpoint continuous beating function in a communication mode. The lower computer is an embedded system with a Bluetooth communication module and is responsible for converting a motion instruction sent by the upper computer into a motion code of the equipment stepping motor and acquiring the current motion state of the equipment. The interruption of the printing process of the equipment is caused by the breakpoint or fault of the lower computer, and the running state of the equipment needs to be sent to the upper computer for storage by means of communication because the lower computer does not have the function of storing the current state.

Since the printing process state of the surface exposure technology only comprises the layer number of the model slices and the movement position of the Z-axis driven forming plate, the breakpoint continuous printing method needs to record the two states in real time in the printing process of the equipment. When the printing process is interrupted, the moving distance of the equipment forming plate at the breakpoint and the display layer number of the model slices are calculated according to the current state, so that the printing state of the equipment can be recovered. The basic principle is that the movement distance required by the forming plate to move from the upper limit position to the breakpoint position is calculated by subtracting the total Z-axis movement stroke of the equipment and the distance which the Z-axis has moved when the interruption occurs. And simultaneously, recording the number of layers displayed by the model slice image when the breakpoint occurs. When the equipment resumes printing from the breakpoint position, the forming plate moves downwards to the breakpoint position from the upper limit position and starts to display from the model layer cutting diagram at the breakpoint position in cooperation with the light source, so that the function of resuming the printing process from the breakpoint occurrence position of the equipment is realized. In the invention, the movement position of the forming plate is represented by the pulse number required by the movement of the stepping motor, and the pulse number required by the movement to the breakpoint is calculated according to the number of layers of the interruption.

The invention provides a breakpoint continuous printing method of a surface exposure 3D printing device, which integrates the breakpoint continuous printing method into a control method of the device, and adds the operation required for realizing breakpoint continuous printing into an operation flow chart of the whole system according to the interactive logic relationship between an upper computer and a lower computer, as shown in figure 1, and as shown in figure 2, the specific operation explanation executed by the key steps of device operation is as follows:

the method comprises the following steps that firstly, a lower computer of the device is electrified, a mobile end upper computer is connected with the lower computer through a Bluetooth protocol, after the connection is successful, the upper computer sends an upward movement instruction to the lower computer, the format is ux and x, wherein a first letter indicates that a forming plate needs to be lifted, a second digit x indicates the number of break points of break point continuous punching, and a third digit x, namely the first digit after comma separation, indicates the number of pulses required by the movement Z-axis total stroke of the forming plate. On the first print, the second digit and third digit are both zero, so the command is u0, 0. Under the command, the Z axis drives the forming plate to move upwards to an upper limit position, the lower computer replies a command p to the upper computer at the moment, the forming plate moves upwards to the upper limit switch position, and a variable Z _ total for recording the pulse number required by the Z axis stroke in the upper computer is set to be zero at the moment;

and step two, the user operates the upper computer of the mobile terminal, the printing model is selected, the printing parameter is set and then the user clicks to start printing, the upper computer sends a downward movement instruction tx to the lower computer, wherein x is 1, 2, 3 and 4 which are multiples of the thickness value of the basic layer of 0.05 respectively. The forming plate moves downwards to a lower limit position; at the moment, the lower computer returns to the upper computer to the hz, wherein the z represents the pulse number required by the stepping motor when the stepping motor runs from the upper limit position to the lower limit position; the upper computer stores the pulse number Z required by the Z-axis motion into a variable Z _ totl; and storing the variable in an upper computer; the movement stroke of the Z axis of the equipment is used for calculating the position of the forming plate when the break point continues to be beaten;

step three, the equipment starts printing, and the upper computer controls the light source to display the cutting picture of the current layer and stores the layer number of the current layer for restoring the printed layer number when the breakpoint continues printing; after each layer of sliced image is irradiated for a set curing time, the upper computer sends a control instruction f to the lower computer, and the lower computer controls the forming plate to move for a layer thickness distance to perform curing of the next layer; simultaneously, the upper computer records the actual curing time of the layer; after the last layer of the model is displayed, the upper computer sends an instruction u to the lower computer, and the forming plate moves upwards to the upper limit switch position;

step four, if the device is interrupted in the printing process, the upper computer records that the actual curing time of the layer is less than the curing time of each layer which is initially set; before the next printing is started, the upper computer prompts a user whether to continue printing from the current position at a breakpoint or to reprint the whole model; if the breakpoint is selected for continuous printing, judging whether the current breakpoint layer needs to be printed again according to whether the actual curing time of the current layer exceeds half of the set curing time; after the Bluetooth connection between the upper computer and the lower computer is successful, the upper computer sends an upward movement instruction to the lower computer in a format of ux and x, wherein two digits after the instruction respectively represent a breakpoint layer number of an interruption and a Z-axis total stroke recorded in a variable Z _ total. And according to the two pieces of information and the judgment of whether the layer needs to be solidified again, the lower computer calculates the pulse number required by moving to the breakpoint and maintaining, and controls the light source to display the slice image of the breakpoint layer, thereby realizing breakpoint continuous striking.

The operation flow chart of the surface exposure equipment with the breakpoint continuous playing function is shown in fig. 2, and breakpoint variable judgment and recording are added on the basis of the original control flow.

The invention is practically applied to a portable surface exposure 3D printer, the upper computer of the device is mobile equipment such as a mobile phone, and the lower computer is a singlechip control panel. The upper computer and the lower computer communicate with each other by controlling the communication between the instructions and the state information through a Bluetooth 4.0 protocol. The user selects a model to be printed on the upper computer to print for the first time, and the upper computer and the lower computer are connected through Bluetooth. After the connection is successful, the forming plate moves upwards to an upper limit position on the top of the equipment to wait for the next operation of the user. When the user clicks the print start button, the device begins to cure the model slice layer by layer.

If an abnormality occurs in the printing process, the printing is terminated. And at the moment, the upper computer mobile equipment is opened again to select the same model for printing, and the upper computer judges whether the printing is breakpoint continuous printing according to whether the breakpoint variable is zero or not. If the printing is judged to be the breakpoint continuous printing, the user is inquired to select the breakpoint continuous printing or the printing from the beginning, and the current printing layer number is prompted to the user. After the user selects the breakpoint to continue to make the connection, the upper computer starts to be connected with the lower computer in a Bluetooth mode. And after the connection is successful, controlling the forming plate to move upwards to the upper limit position of the equipment. And when the upper computer occurs according to the breakpoint, judging whether the layer needs to be cured again according to the curing time of the layer, and if so, subtracting 1 from the number of recorded breakpoint layers. And sending the calculated number of the interruption layers to a lower computer, calculating the pulse number required by the lower computer to move to the breakpoint according to the value, and after a user clicks a 'print start' button, starting the movement of the equipment to the position of the forming plate when the breakpoint occurs to continue the model printing process. And (4) until the model printing is finished, the upper computer clears and records the value of the breakpoint state variable, and the whole printing process is finished.