Focal point determination method, system for laser cutting machine for cutting dental instruments

Abstract

The application discloses a kind of focal point determination method, system for cutting dental instrument laser cutting machine, the focal point determination method of the application is fixed on movement module to be cut piece, while setting initialization movement step and moving direction, and identify the figure cut under a round of movement, according to the figure of the thinnest line cut in this round determines the position closest to focal point in each cutting position, then according to the range before and after in this position moves, further determine whether there is more close position, then through cyclic repetition, automatically determine the position closest to focal point.Furthermore, by the way of reducing step length each round, the accuracy of the determined focal point can be effectively improved, and the step length is from large to small, and the stepping speed is from slow to fast, effectively speeding up the speed of the entire calibration process.It is simple to realize, high degree of automation, and fast, without special auxiliary instrument, low in cost, high in accuracy, and convenient for wide promotion.

Description

Technical Field

[0001] This invention belongs to the field of orthodontic technology, more specifically to the manufacturing technology of orthodontic appliances, and particularly to a focal point determination technology for a laser cutting machine used for cutting dental instruments. Background Technology

[0002] Shell-shaped orthodontic appliances are devices used to treat malocclusion. They are made of safe, elastic, and transparent polymer materials, allowing the treatment process to be completed almost imperceptibly. The production process includes mold preparation, molding, marking, cutting, and cleaning. In the molding process, a dental model is placed on a model carrier plate, and then the model carrier plate and the model are transported to the molding area for molding, forming the initial shell-shaped orthodontic appliance with the dental model. To accelerate the processing of the dental model and achieve mass production, the entire manufacturing process must be automated and efficient.

[0003] In existing manufacturing processes, the cutting step requires calibrating the relative distance between the cutting machine and the dental instrument being cut, ensuring that the cutting machine's focal point falls on the cutting surface of the instrument. This not only allows the cutting machine's power to be used more effectively in the cutting process but also produces smooth, even lines. During laser cutting machine installation, a calibration process is typically performed to determine the relative positions of the cutting machine objective and the workpiece. However, during processing, human-caused collisions, fixture installation deviations, and other factors can alter the relative positions of the cutting machine objective and the workpiece. Since dental instruments require high manufacturing precision and are made of transparent materials, it is difficult to directly restore their relative positions using physical calibration components. Therefore, a method for quickly confirming the focal point position is needed. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the defects in the prior art and provide a method and system for determining the focus of a laser cutting machine for cutting dental instruments, which enables the focus of the laser cutting machine to be quickly and automatically confirmed, is simple to implement, does not require special auxiliary instruments, and has high accuracy.

[0005] The technical solution provided by this invention includes at least the following: a method for determining the focus of a laser cutting machine for cutting dental instruments, comprising the following steps: S1: fixing the workpiece to be cut to a motion module, setting the initial movement step size and initial movement direction of the motion module, wherein the initial movement direction is the direction from the starting position to the focusing objective lens of the laser cutting machine; S2: the motion module drives the workpiece to be cut from a predetermined initial movement position to a predetermined final movement position, wherein after each step of the motion module according to the initial movement step size, the laser cutting machine cuts the workpiece to be cut once according to a predetermined path and pattern to form a cutting pattern; S3: identifying the line width of the cutting pattern formed on the workpiece to be cut after each step, and In this round of cutting patterns, the first focal pattern with the thinnest line width is identified, and the position of the motion module corresponding to the first focal pattern on the motion trajectory when it is cut is determined as the first focal position; the first front adjacent pattern and the first rear adjacent pattern that are adjacent to the first focal pattern in the stepping direction are determined; S4: the position of the motion module corresponding to the first front adjacent pattern when it is cut in this round on the motion trajectory is set as the initial position of the next round of movement, the position of the motion module corresponding to the first rear adjacent pattern when it is cut in this round on the motion trajectory is set as the termination position of the next round of movement, and the movement step size of the motion module in the next round is set, wherein the movement step size of the next round is smaller than the movement step size of the current round; S5: the motion module proceeds according to step S4. The motion module moves from the initial position set in step S4 to the termination position set in step S4, and after each step according to the motion step size set in step S4, the laser cutting machine cuts the workpiece to be cut once according to a predetermined path and pattern to form a cutting pattern; the line width of the outline of the cutting pattern formed on the workpiece to be cut after each step is identified, and the Nth focal point pattern with the thinnest outline line width is found among the cutting patterns in this round, and the position of the motion module on the motion trajectory corresponding to the Nth focal point pattern when it is cut is determined as the Nth focal point position; the Nth preceding adjacent pattern and the Nth following adjacent pattern that are adjacent to the Nth focal point pattern in the stepping direction are determined. Line width, where N is equal to the number of times step S4 is executed + 1; S6: Compare the line width of the Nth focal graphic with the line width of the (N-1)th focal graphic: If the line width of the Nth focal graphic is greater than the line width of the (N-1)th focal graphic, determine the (N-1)th focal position corresponding to the (N-1)th focal graphic as the focal position of the laser cutting machine; If the line width of the Nth focal graphic is less than or equal to the line width of the (N-1)th focal graphic, calculate the difference between the line width of the Nth focal graphic and the line widths of the Nth preceding adjacent graphic and the Nth following adjacent graphic respectively: If one or two of the line width differences fall within a predetermined first threshold range, determine the Nth focal position as the focal position of the laser cutting machine;If neither of the differences in linewidth falls within the first threshold range, then S4 to S6 are executed repeatedly.

[0006] The technical solution provided by this invention further includes at least: a focus determination system for a laser cutting machine for cutting dental instruments, comprising: a laser cutting module, a motion module, a processing module, an identification module, and a central control module. The central control module controls the laser cutting module, motion module, processing module, and identification module to perform the following actions: the motion module moves the workpiece to be cut in steps according to a set initial movement step size and initial movement direction, wherein the initial movement direction is the direction from the starting position towards the focusing objective lens of the laser cutting module; after each step of the motion module according to the initial movement step size, the laser cutting module cuts the workpiece according to a predetermined path and pattern. The cutting process forms a cutting pattern; the identification module identifies the line width of the cutting pattern formed on the workpiece after each step, and compares the first focal point pattern with the thinnest line width among the cutting patterns in this round, and determines the position of the motion module corresponding to the first focal point pattern on the motion trajectory when the first focal point pattern is cut as the first focal point position; the first front adjacent pattern and the first rear adjacent pattern that are adjacent to the first focal point pattern in the stepping direction are determined; the processing module sets the position of the motion module corresponding to the first front adjacent pattern when it is cut in this round on the motion trajectory as the initial position of the next round of movement, and sets the position of the motion module corresponding to the first rear adjacent pattern when it is cut in this round on the motion trajectory. The motion module is set to the next round's ending position and a step size is set for the next round, which is smaller than the current round's step size. The motion module moves from the initial position set by the processing module to the ending position set by the processing module according to the step size set by the processing module. After each step by the motion module according to the step size set by the processing module, the laser cutting module cuts the workpiece to be cut along a predetermined path and pattern to form a cutting pattern. The processing module identifies the line width of the outline of the cutting pattern formed on the workpiece after each step and identifies the wheel among the cutting patterns in this round. The Nth focal point is defined as the Nth focal point position, which is the position of the motion module corresponding to the Nth focal point when it is cut. The linewidths of the Nth preceding and Nth following adjacent graphics in the stepping direction are determined, where N is equal to the number of times the processing module sets the initial position for the next round of movement + 1. The processing module compares the linewidth of the Nth focal point with the linewidth of the (N-1)th focal point: if the linewidth of the Nth focal point is greater than the linewidth of the (N-1)th focal point, the (N-1)th focal point position corresponding to the (N-1)th focal point is determined as the focal point position of the laser cutting module.When the linewidth of the Nth focal graphic is less than or equal to the linewidth of the (N-1)th focal graphic, the differences between the linewidth of the Nth focal graphic and the linewidths of the Nth preceding and Nth following adjacent graphics are calculated respectively. If one or two of the linewidth differences fall within a predetermined first threshold range, the Nth focal position is determined as the focal position of the laser cutting module. If neither of the linewidth differences falls within the first threshold range, the motion module is triggered.

[0007] This invention, by employing the above technical solution, possesses at least the following advantages and positive effects compared to existing technologies: The workpiece to be cut is fixed on the motion module, and an initial movement step size and direction are set. The pattern cut out in one round of movement is identified. Based on the pattern of the finest line cut in this round, the position closest to the focal point among each cutting position is determined. Then, by moving within a range before and after that position, it is further determined whether there is an even closer position. This process is repeated cyclically to automatically determine the position closest to the focal point. Furthermore, by using a decreasing step size in each round, the accuracy of the determined focal point can be effectively improved. Simultaneously, the step size decreases from large to small, and the stepping speed increases from slow to fast, effectively accelerating the entire calibration process. It is evident that since the closer to the focal point, the finer the cutting line. Determining the distance to the focal point based on the thickness of the cutting line is simple, highly automated, and fast. It requires no special auxiliary equipment, is low in cost, and has high accuracy, making it easy to widely promote.

[0008] Furthermore, the workpiece to be cut is a diaphragm used for processing transparent dental instruments, and the diaphragm is perpendicular to the laser beam emitted by the laser cutting machine. Using a transparent raw material diaphragm as the workpiece for the focus confirmation process makes the cutting effect closer to that of the actual product, better meeting the accuracy and precision requirements of product cutting.

[0009] Furthermore, the membrane material includes at least one of the following: PETG and TPU. A membrane material corresponding to the actual product material can be selected for the calibration process, ensuring that the calibration results better meet the actual needs of the product.

[0010] Furthermore, the line width is identified through the following steps: identifying two contour lines along the length direction of a line in the graphic; calculating the distance between the two contour lines, where the distance is the identified line width. This embodiment defines a method for confirming line width, making line width identification accurate and feasible.

[0011] Furthermore, if neither of the two differences in line width falls within a predetermined threshold range, then steps S4 to S6 are executed repeatedly. If neither of the two differences in line width falls within a predetermined threshold range, then the line smoothness in the Nth focal point graphic is identified. If the line smoothness in the Nth focal point graphic does not fall within a predetermined second threshold range, then steps S4 to S6 are executed repeatedly. In this embodiment of the invention, line smoothness is added as a basis for focal point determination. Since the closer to the focal point, the higher the line smoothness, the more accurate the focal point confirmation can be further increased by combining smoothness and line width in the determination.

[0012] Furthermore, the cutting pattern is a line segment. Using a line segment as the cutting pattern makes cutting simple and easy to identify.

[0013] Furthermore, the motion module includes a stepper motor, a three-dimensional guide rail, and a support. The workpiece to be cut is fixedly connected to the support. The stepper motor controls the movement of the support on the three-dimensional guide rail. The three-axis directions of the three-dimensional guide rail include: the initial movement direction, a direction perpendicular to the initial movement direction on a horizontal plane, and a vertical direction. This embodiment of the invention limits the structure of the motion module, employing a combination of a three-dimensional guide rail and a stepper motor, making implementation relatively simple and reducing hardware costs.

[0014] Furthermore, the motion module includes a robotic arm with a clamping part at its end. The workpiece to be cut is connected to the robotic arm through the clamping part, and the robotic arm maintains the cutting surface of the workpiece facing the same direction after each step. This embodiment of the invention defines another structure for the motion module, which is implemented using a robotic arm, resulting in high movement accuracy, compatibility with existing cutting systems, and easier promotion.

[0015] Furthermore, it also includes an air blowing module, which blows air to cover the cutting area of ​​the workpiece on the motion module. Since the cutting process may generate smoke and dust, which may cover the cut workpiece and affect the accuracy of graphic recognition, the air blowing module is added to disperse the smoke and dust generated during the cutting process, prevent the smoke and dust from covering the cut workpiece, and improve the accuracy of graphic recognition.

[0016] Furthermore, the air-blowing module is positioned adjacent to and relatively fixed to the laser cutting machine. This adjacent and relatively fixed arrangement facilitates the installation of the air-blowing module and the layout of each module.

[0017] Furthermore, it also includes a fume extraction module for removing the fumes generated during laser cutting. Adding a fume extraction module helps to remove the fumes generated during laser cutting, further preventing dust accumulation on the cut parts and improving the accuracy of pattern recognition. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for determining the focal point of a laser cutting machine for cutting dental instruments according to an embodiment of the present invention;

[0019] Figure 2 This is a flowchart of the line width identification step in the focal point determination method of a laser cutting machine for cutting dental instruments according to an embodiment of the present invention.

[0020] Figure 3 This is a flowchart of a method for determining the focal point of a laser cutting machine for cutting dental instruments, according to another embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the focal point determination system of a laser cutting machine for cutting dental instruments according to one embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the focal point determination system of a laser cutting machine for cutting dental instruments according to another embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the focus determination system of a laser cutting machine for cutting dental instruments according to another embodiment of the present invention. Detailed Implementation

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of the present invention. Without conflict, the embodiments and technical features in these embodiments can be combined with each other. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without creative effort.

[0025] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0026] One embodiment of the present invention provides a method for determining the focal point of a laser cutting machine for cutting dental instruments, the method flow is as follows: Figure 1 As shown, the specific steps include:

[0027] Step 101, Initialization Steps.

[0028] Specifically, in this step, the workpiece to be cut is fixed to the motion module, and then the initial movement step size and initial movement direction of the motion module are set. More specifically, in this embodiment, the initial movement direction is from the starting position towards the focusing lens of the laser cutting machine. The initial movement step size can be greater than 1mm, such as 1.5mm, 2mm, etc.

[0029] More specifically, this embodiment uses a diaphragm for processing transparent dental instruments as an example to illustrate the process. The diaphragm is essentially the raw material for the dental instrument. For instance, if the dental instrument is a transparent shell-shaped dental appliance, the corresponding raw material diaphragm can be square or round. The diaphragm can be a PETG (Poly(ethylene terephthalate co-1,4-cylclohexylenedimethylene terephthalate), a transparent, non-crystalline copolyester) diaphragm, a TPU (Thermoplastic polyurethanes) diaphragm, or a multilayer diaphragm. Diaphragm specifications can include 0.35mm, 0.5mm, 0.8mm, 1.0mm, etc. It is worth noting that in practical applications, different parameters of the laser cutting machine can be set according to the material and specifications of the diaphragm, as shown in the table below:

[0030] Diaphragm thickness (mm) Laser ratio laser power PETG, 0.75 32％ 41.2％ PETG, 0.85 31％ 42.0％ PETG, 0.5 30％ 33.7％

[0031] In practical applications, parameter settings can also be set based on the experience of technical personnel, which will not be listed here.

[0032] Step 102, the first round of cutting.

[0033] Specifically, the motion module moves the workpiece to be cut from a predetermined initial position to a predetermined final position. After each step of the motion module according to the initial movement step length, the laser cutting machine cuts the workpiece to be cut once according to the predetermined path and pattern to form a cutting pattern.

[0034] For example, if the movement step size is set to 1.5mm in step 101, then this step will proceed in 1.5mm increments each time. After each 1.5mm increment, the laser cutter will cut the film according to a predetermined path and pattern, from the predetermined initial movement position to the predetermined final movement position, cutting out a series of patterns in one cycle. The patterns can be line segments for easier identification. The predetermined initial and final movement positions can be determined by technicians based on experience.

[0035] Step 103, line width identification and comparison steps.

[0036] Specifically, this step identifies the line width of the cutting pattern formed on the workpiece to be cut after each step, and identifies the first focal point pattern with the thinnest line width among the cutting patterns in this round, and determines the position of the motion module corresponding to the first focal point pattern on the motion trajectory when the first focal point pattern is cut as the first focal point position. The first front adjacent pattern and the first rear adjacent pattern that are adjacent to the first focal point pattern in the stepping direction are determined.

[0037] More specifically, after completing one round of cutting, the line width can be confirmed using the outline-interval method, such as... Figure 2 As shown, it includes the following steps:

[0038] Step 1031: Identify the two contour lines of a line in the graphic along its length.

[0039] Specifically, the cut-out shape is composed of lines. An image of the cut-out shape can be obtained by capturing it with a camera module (such as a CCD) and then identified. A portion of the shape is arbitrarily selected as a sample line, and the two contour lines along the length of this sample line are identified. This can be done by taking points at the edges of the lines. Since the line widths are roughly the same, the selected edge points will converge into two lines, which are the contour lines to be identified.

[0040] Step 1032: Calculate the distance between the two contour lines, where the distance is the identified line width.

[0041] Specifically, the distance between two contour lines can be calculated using the coordinates of points on the contour lines. The specific method can be calculated based on existing coordinates, and will not be elaborated here.

[0042] It should also be noted that the cut patterns after each step can be the same or different. For example, each time a line segment is cut, the film is translated a preset distance in a direction perpendicular to the laser beam between two cuts, so that the cut patterns do not overlap. Alternatively, similar patterns can be cut from a center point, such as cutting circles, with the radius of the circle being set to be different each time, so that the cut patterns do not overlap.

[0043] Step 104, parameter adjustment steps.

[0044] Specifically, the position of the motion module corresponding to the first adjacent graphic in the current round when it is cut on the motion trajectory is set as the initial position of the next round of movement, and the position of the motion module corresponding to the first adjacent graphic in the current round when it is cut on the motion trajectory is set as the ending position of the next round of movement. The movement step size of the motion module in the next round is set, and the movement step size of the next round is smaller than the movement step size of the current round.

[0045] Step 105 involves further cutting, line width identification, and comparison.

[0046] The motion module moves from the initial position set in step 104 to the termination position set in step 104 according to the movement step length set in step 104. After each step, the laser cutting machine cuts the workpiece to be cut according to a predetermined path and pattern to form a cutting pattern. The line width of the outline of the cutting pattern formed on the workpiece to be cut after each step is identified. In the cutting patterns of this round, the Nth focal pattern with the thinnest outline line width is found and the position of the motion module on the motion trajectory corresponding to the Nth focal pattern when it is cut is determined as the Nth focal position. The line widths of the Nth front adjacent pattern and the Nth rear adjacent pattern that are adjacent to the Nth focal pattern in the stepping direction are determined.

[0047] Specifically, N is equal to the number of times step 104 is executed + 1. Since step 104 is a parameter adjustment step that is executed every time starting from the second round of cutting, the number of times this step is executed + 1 is the number of rounds of cutting.

[0048] More specifically, the line width identification in this step is similar to that in step 103.

[0049] Step 106, Focus Image Comparison Step.

[0050] Specifically, in this step, the line width of the Nth focal graphic is compared with the line width of the (N-1)th focal graphic; if the line width of the Nth focal graphic is greater than the line width of the (N-1)th focal graphic, step 107 is executed; if the line width of the Nth focal graphic is less than or equal to the line width of the (N-1)th focal graphic, step 108 is executed.

[0051] Specifically, after determining the line width and the finest line width in the new round of cutting in step 105, this step compares the finest line width in the new round of cutting with the finest line width in the previous round of cutting to confirm whether the finest line width in the new round of cutting can be finer than the finest line width in the previous round of cutting.

[0052] Step 107, First focus determination step.

[0053] Specifically, in this step, the N-1th focal position corresponding to the N-1th focal pattern is determined as the focal position of the laser cutting machine.

[0054] Specifically, in this step, after comparing the results in step 106 and finding that the line width of the focal graphic in the new round of cutting is greater than the line width of the focal graphic in the previous round of cutting, the focal graphic in the previous round of cutting, that is, the focal position corresponding to the graphic with the thinnest line width, is confirmed as the focal position of the laser cutting machine.

[0055] More specifically, when using a robot as a motion module, the coordinates of the robot at this position are recorded and used as the focus of the laser.

[0056] Step 108, adjacent line width comparison step.

[0057] Specifically, in this step, the line width of the Nth focal graphic is calculated as the difference between the line width of the Nth preceding adjacent graphic and the Nth following adjacent graphic. If one or two of the line width differences fall within a predetermined first threshold range, then step 109 is executed; if neither of the line width differences falls within the first threshold range, then step 104 is returned to be executed.

[0058] Specifically, this step is executed after the comparison result in step 106 shows that the line width of the focal graphic in the new round of cutting is less than or equal to the line width of the focal graphic in the previous round of cutting. In other words, the focal position corresponding to the focal graphic in the new round of cutting is closer to the actual focal position.

[0059] More specifically, this step continues to compare the line width of the current focus graphic with the line width of the adjacent graphics along the stepping direction. If the line width difference is very small, then it is determined to continue to step 109. If the line width is large, then it is determined to return to step 104, that is, to perform the next round of cutting.

[0060] Step 109, Second Focus Confirmation Step. The Nth focus position is determined as the focus position of the laser cutting machine.

[0061] Specifically, in this step, if the difference between the line width of the focal graphic and the line width of the adjacent graphics in the current round of cutting is very small, it is considered that the focal position has been found. It should be noted that, theoretically, the focal point can be confirmed infinitely close to the focal point; however, considering the effectiveness of the implementation method, this width difference is set to determine the focal position within a certain accuracy range, which is more conducive to the effective implementation of this application.

[0062] In one embodiment, a motion module is used as a robotic arm, and the workpiece to be cut is used as a diaphragm. A suction cup fixture is installed at the end of the robotic arm, and the suction cup fixture is fixedly connected to the processed product. When the workpiece to be cut is fixed to the motion module, the robotic arm's posture during the initial motion is such that the diaphragm is perpendicular to the laser beam emitted by the laser cutting machine. In one embodiment, taking a six-axis robot as the robotic arm, a line segment as the cutting pattern, and a step length of 1mm as an example, the specific description for one round of cutting motion is as follows: 1. Place the robot and the laser device of the laser cutting machine on the machine frame. Use a level to test and adjust to ensure they are absolutely perpendicular. When the robot is in zero posture (i.e., all robot joints are at 0°), the distance between the plane of the six axes and the laser output port is 640-650mm (±10mm error). Then guide the robot forward to a position 300mm (±10mm error) from the laser output port, and place a product diaphragm to adhere to the robot fixture. 2. Record the current robot position and use this position as the initial point. Set the laser as the tool coordinate and make the robot perform linear motion (workpiece movement). Set five planning points and perform five cycles. During each cycle, the robot moves 1mm towards the laser from the initial point (the laser must maintain illumination during the movement) (i.e., the robotic arm steps forward 1mm along the laser direction). The operation method is as follows: the robot moves upward 25mm from the initial point, pauses for 0.2 seconds, then moves 1mm along the Y-axis, and then slowly moves downward 25mm to the first planning point. This is one cycle. During the second cycle, the robot moves 1mm towards the laser from the origin (i.e., the robotic arm steps forward 1mm along the laser direction again). The endpoint is the position with a 5mm step. Repeat this linear motion five times to complete one round of cutting, i.e., cutting five parallel lines on the product film. Continuing, 3. After the robot finishes its movement, turn off the laser and move the robot to the camera's imaging area. When taking pictures using a CCD camera, the cut lines will be illuminated by the light source, making the cut lines appear clearer in the CCD camera. The robot's end effector can be equipped with a light source (blue light) to perform exposure compensation on the image, making the picture appear clearer in the camera's field of view.

[0063] As can be seen, the focus determination method of the laser cutting machine for cutting dental instruments in this embodiment fixes the workpiece to be cut on the motion module, sets the initial movement step size and movement direction, and identifies the pattern cut in one round of movement. Based on the pattern of the finest line cut in this round, the position closest to the focus among each cutting position is determined. Then, by moving within a range before and after that position, it is further determined whether there is a closer position. This process is repeated cyclically to automatically determine the position closest to the focus. Furthermore, by using a decreasing step size in each round, the accuracy of the determined focus can be effectively improved. Simultaneously, the step size decreases from large to small, and the stepping speed increases from slow to fast, effectively speeding up the entire calibration process. It is evident that since the closer the distance to the focus, the finer the cutting line. Determining the distance to the focus based on the thickness of the cutting line is simple, highly automated, and fast. It requires no special auxiliary instruments, is low-cost, and has high accuracy, making it easy to widely promote. In addition, using an actual diaphragm as the workpiece makes the cutting effect similar to that of an actual product, better meeting the accuracy and precision requirements of product cutting.

[0064] Another embodiment of the present invention designs a focal point determination method for a laser cutting machine used for cutting dental instruments. This embodiment adds a smoothness judgment of the cutting line based on the first embodiment. The superimposed parameters used for judgment can improve the accuracy of focal point confirmation.

[0065] like Figure 3 As shown, it includes the following steps:

[0066] Steps 301 to 307 are similar to steps 101 to 107 in the previous embodiment, and will not be described again here.

[0067] Step 308, adjacent line width comparison step.

[0068] Specifically, in this step, the line width of the Nth focal graphic is calculated as the difference between the line width of the Nth preceding adjacent graphic and the Nth following adjacent graphic. If one or two of the line width differences fall within a predetermined first threshold range, then step 309 is executed; if neither of the line width differences falls within the first threshold range, then step 310 is executed.

[0069] Step 309 is similar to step 109 in the previous embodiment, and will not be described again here.

[0070] Step 310, Smoothness Recognition Step.

[0071] Specifically, this step identifies the line smoothness in the Nth focal graphic. If the line smoothness in the Nth focal graphic does not fall within a predetermined second threshold range, then the process returns to step 304. If the line smoothness in the Nth focal graphic falls within the predetermined second threshold range, then step 309 is executed.

[0072] It should be further explained that the line smoothness in this embodiment can be determined by fitting sampling points. Specifically, a line L is selected on the focal graphic, and S points are sampled on this line. The S points can be sampled at equal intervals. A curve fitting algorithm is applied to the sampled S points to obtain a fitted line L'. Then, the similarity between the fitted line L' and the selected line L is compared to determine the smoothness of the selected line L. In practical applications, other methods can also be used to determine line smoothness, which will not be listed here.

[0073] It should also be noted that in this step, the smoothness of the lines is further judged for focal graphics that do not meet the line width difference requirement. Since the lines cut at the focal point of the laser beam are smooth, the laser beam becomes unfocused and the laser energy is dispersed, resulting in burrs or uneven cutting in the cut lines. Therefore, in this embodiment, the smoothness judgment is superimposed to increase the accuracy of focal point confirmation and facilitates finding the focal point location more quickly.

[0074] It's important to further explain that during recognition, the camera captures and marks images of clear and smooth translucent patterns on the membrane. The CCD camera then compares the images of the cut lines; lines with burrs or rough edges will be omitted from the image marking. The process continues, capturing and comparing the next line until a smooth cut is selected. The actual cut line selected from this image represents the pattern cut at the optimal focal point. The coordinates of this position within the robot are recorded and used as the laser's focal point.

[0075] As can be seen, the implementation method adds line smoothness as a basis for focal point determination. Since the smoothness of the line is higher the closer it is to the focal point, the combination of smoothness and line width can further increase the accuracy of focal point confirmation.

[0076] Another embodiment of the present invention provides a focus determination system for a laser cutting machine used for cutting dental instruments. The focus determination system in this embodiment is as follows: Figure 4 As shown, it includes: a laser cutting module 10, a motion module 50, a processing module 60, a recognition module 40, and a central control module 100. The central control module 100 controls the laser cutting module 10, the motion module 50, the processing module 60, and the recognition module 40 to perform the following actions:

[0077] The motion module 50 moves the workpiece to be cut step by step according to the set initial moving step size and initial moving direction, wherein the initial moving direction is the direction from the starting position to the focusing lens of the laser cutting module 10.

[0078] After the motion module 50 moves according to the initial step size, the laser cutting module 10 cuts the workpiece to be cut once according to a predetermined path and pattern to form a cutting pattern.

[0079] The identification module 40 identifies the line width of the cutting pattern formed on the workpiece to be cut after each step, and compares the first focal pattern with the thinnest line width among the cutting patterns in this round and determines the position of the motion module 50 on the motion trajectory when the first focal pattern is cut as the first focal position; and determines the first front adjacent pattern and the first rear adjacent pattern that are adjacent to the first focal pattern in the stepping direction.

[0080] The processing module 60 sets the position of the motion module 50 on the motion trajectory when the first adjacent graphic in the current round is cut as the initial position of the next round of movement, sets the position of the motion module 50 on the motion trajectory when the first adjacent graphic in the current round is cut as the termination position of the next round of movement, and sets the movement step size of the motion module 50 in the next round, wherein the movement step size of the next round is smaller than the movement step size of the current round.

[0081] The motion module 50 moves from the initial position set by the processing module 60 to the termination position set by the processing module 60 according to the movement step size set by the processing module 60.

[0082] The laser cutting module 10 cuts the workpiece to be cut once according to a predetermined path and pattern after the motion module 50 moves each step according to the movement step size set by the processing module 60.

[0083] The processing module 60 identifies the line width of the outline of the cutting pattern formed on the workpiece to be cut after each step, and finds the Nth focal pattern with the thinnest outline among the cutting patterns in this round and determines the position of the motion module 50 on the motion trajectory when the Nth focal pattern is cut as the Nth focal position; determines the line width of the Nth preceding adjacent pattern and the Nth following adjacent pattern that are adjacent to the Nth focal pattern in the stepping direction, wherein N is equal to the number of times the processing module 60 sets the initial position of the next round of movement + 1.

[0084] The processing module 60 compares the linewidth of the Nth focal graphic with the linewidth of the (N-1)th focal graphic: when the linewidth of the Nth focal graphic is greater than the linewidth of the (N-1)th focal graphic, the (N-1)th focal position corresponding to the (N-1)th focal graphic is determined as the focal position of the laser cutting module 10; when the linewidth of the Nth focal graphic is less than or equal to the linewidth of the (N-1)th focal graphic, the difference between the linewidth of the Nth focal graphic and the linewidths of the Nth preceding adjacent graphic and the Nth following adjacent graphic is calculated respectively: when one or two of the linewidth differences fall within a predetermined first threshold range, the Nth focal position is determined as the focal position of the laser cutting module 10; when neither of the linewidth differences falls within the first threshold range, the motion module 50 is triggered.

[0085] The aforementioned preset parameters, threshold ranges, cutting paths, and other information can be stored in the storage module 200. The main control module 100 and the storage module 200 can be connected to the bus 300 respectively. The bus 300 is connected to the laser cutting module 10, the motion module 50, the recognition module 40, and the processing module 60 respectively through the peripheral device interface 400.

[0086] It should be noted that the moving module 20 in this embodiment includes a robotic arm, and the motion module 50 includes a driver corresponding to the robotic arm. The end of the robotic arm is provided with a clamping part, which in this embodiment can be a suction cup fixture. The workpiece to be cut is connected to the robotic arm through the clamping part. The motion module 50 controls the robotic arm to keep the cutting surface of the workpiece facing the same direction after each step.

[0087] More specifically, in this embodiment, the movable directions of the moving module 20 include: the initial moving direction and its opposite direction, as well as a direction perpendicular to the initial moving direction. Each step includes one step in the initial moving direction or its opposite direction, and one step perpendicular to the initial moving direction. This provides multiple movable directions, making movement more flexible. Furthermore, the addition of a step in the vertical direction ensures that the cut graphics do not overlap, facilitating graphic comparison.

[0088] As can be seen, this embodiment employs a combination of a laser cutting module, a motion module, a processing module, and a recognition module to perform multiple rounds of cutting and recognition. Based on the shape of the finest line cut in each round, the position closest to the focal point is determined among each cutting position. Then, by moving within a range before and after that position, it is further determined whether there is an even closer position. This process is repeated cyclically to automatically determine the position closest to the focal point. Furthermore, by using a decreasing step size in each round, the accuracy of the determined focal point can be effectively improved. Simultaneously, the step size decreases from large to small, and the stepping speed increases from slow to fast, effectively speeding up the entire calibration process. It is evident that since the closer to the focal point, the finer the cutting line. Determining the distance to the focal point based on the thickness of the cutting line achieves a simple, highly automated, and fast process, requiring no special auxiliary equipment, resulting in low cost, high accuracy, and easy widespread adoption.

[0089] As can be seen, this embodiment is a system implementation corresponding to the first embodiment, and this embodiment can be implemented in conjunction with the first embodiment. The relevant technical details mentioned in the first embodiment remain valid in this embodiment, and will not be repeated here to avoid repetition. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the first embodiment.

[0090] Another embodiment of the present invention provides a focus determination system for a laser cutting machine for cutting dental instruments. The main improvement of this embodiment compared to the previous embodiment is the addition of an air blowing module, the blown airflow covering the cutting area of ​​the workpiece 30 on the moving module 20.

[0091] like Figure 5 As shown, in this embodiment, the air blowing module 70 and the laser cutting module 10 are arranged adjacent to each other and relatively fixed, which facilitates the installation of the air blowing module 70 and the layout of each module. Specifically, the air blowing nozzle of the air blowing module 70 and the laser 11 of the cutting machine can be set 30mm apart, specifically, it can be installed above the laser 11. Since the dust and smoke generally diffuse upwards when the laser 11 is cutting, the air blowing nozzle set above can make the blown airflow better disperse the dust and smoke.

[0092] Specifically, the air blowing module 70 includes an air outlet, such as an air blowing pipe, and a compressed gas device connected to the air blowing pipe. The compressed gas is blown towards the workpiece being cut through the air blowing pipe. When the laser cutting module is working, i.e., cutting a pattern, the air blowing module is controlled to blow air to disperse the dust and smoke generated during the cutting of the workpiece.

[0093] In practical applications, a smoke exhaust module can be further added to exhaust the smoke and dust generated during the laser cutting module. This allows for better collection of waste gas generated during cutting, ensuring proper waste disposal and preventing environmental pollution. Further details will not be elaborated here.

[0094] As can be seen, the cutting process may generate smoke and dust, which may cover the cut part. In this embodiment, the cut part is a transparent film, so being covered by smoke and dust will greatly affect the accuracy of the cut pattern recognition. Therefore, an air blowing module is added to blow away the smoke and dust generated during the cutting process, prevent the smoke and dust from covering the cut part, and improve the accuracy of the pattern recognition.

[0095] Another embodiment of the present invention provides a focus determination system for a laser cutting machine used for cutting dental instruments. The main difference between this embodiment and the previous embodiment is that the moving module in the previous embodiment was implemented using a robotic arm, while in this embodiment it is implemented using a stepper motor, a three-dimensional guide rail, and a support, which helps to reduce hardware costs.

[0096] Specifically, such as Figure 6 As shown, the motion module 50 in this embodiment includes a stepper motor (not shown), a three-dimensional guide rail 21, and a support 22. A machined component (such as a diaphragm) is fixedly connected to the support. The stepper motor controls the movement of the support on the three-dimensional guide rail. The three axes of the three-dimensional guide rail include: the initial movement direction, a direction perpendicular to the initial movement direction on a horizontal plane, and a vertical direction. This embodiment of the invention limits the structure of the motion module 50, employing a combination of a three-dimensional guide rail and a stepper motor, making implementation relatively simple and reducing hardware costs.

[0097] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A method for determining the focal point of a laser cutting machine for cutting transparent dental instruments, characterized in that, Includes the following steps: S1: Fix the workpiece to be cut to the motion module, and set the initial moving step size and initial moving direction of the motion module. The initial moving direction is the direction from the starting position to the focusing lens of the laser cutting machine. S2: The motion module drives the workpiece to be cut from a predetermined initial position to a predetermined final position. After each step of the motion module according to the initial movement step length, the laser cutting machine cuts the workpiece to be cut once according to the predetermined path and pattern to form a cutting pattern. S3: Identify the line width of the cutting pattern formed on the workpiece to be cut after each step, and find the first focal pattern with the thinnest line width among the cutting patterns in this round and determine the position of the motion module corresponding to the first focal pattern on the motion trajectory when the first focal pattern is cut as the first focal position. Determine the first front adjacent graphic and the first rear adjacent graphic that are adjacent to the first focal graphic in the stepping direction; S4: Set the position of the motion module corresponding to the first adjacent graphic in this round when it is cut on the motion trajectory as the initial position of the next round of movement, set the position of the motion module corresponding to the first adjacent graphic in this round when it is cut on the motion trajectory as the ending position of the next round of movement, and set the movement step size of the motion module in the next round, wherein the movement step size of the next round is smaller than the movement step size of the current round. S5: The motion module moves from the initial position set in step S4 to the termination position set in step S4 according to the movement step length set in step S4. After each step of the motion module according to the movement step length set in step S4, the laser cutting machine cuts the workpiece to be cut once according to the predetermined path and pattern to form a cutting pattern. Identify the line width of the outline of the cutting pattern formed on the workpiece to be cut after each step, and find the Nth focal point pattern with the thinnest outline line width among the cutting patterns in this round and determine the position of the motion module corresponding to the Nth focal point pattern on the motion trajectory when the Nth focal point pattern is cut as the Nth focal point position. Determine the line widths of the Nth preceding adjacent graphic and the Nth following adjacent graphic that are adjacent to the Nth focal graphic in the stepping direction, wherein N is equal to the number of times step S4 is executed + 1; S6: Compare the line width of the Nth focal graphic with the line width of the (N-1)th focal graphic: If the line width of the Nth focal graphic is greater than the line width of the (N-1)th focal graphic, determine the (N-1)th focal position corresponding to the (N-1)th focal graphic as the focal position of the laser cutting machine; If the line width of the Nth focal graphic is less than or equal to the line width of the (N-1)th focal graphic, calculate the difference between the line width of the Nth focal graphic and the line widths of the Nth preceding adjacent graphic and the Nth following adjacent graphic respectively: If one or both of the line width differences fall within a predetermined first threshold range, determine the Nth focal position as the focal position of the laser cutting machine; If neither of the line width differences falls within the first threshold range, repeat steps S4 to S6.

2. The focal point determination method for a laser cutting machine for cutting transparent dental instruments according to claim 1, characterized in that, The part to be cut is a diaphragm used for processing transparent dental instruments.

3. The method for determining the focal point of a laser cutting machine for cutting transparent dental instruments according to claim 2, characterized in that, The membrane material includes at least one of PETG and TPU.

4. The method for determining the focal point of a laser cutting machine for cutting transparent dental instruments according to claim 1, characterized in that, Identify line width using the following steps: Identify the two outlines of a line along its length in a graphic; Calculate the distance between the two contour lines, where the distance is the identified line width.

5. The method for determining the focal point of a laser cutting machine for cutting transparent dental instruments according to claim 1, characterized in that, In step S6, if neither of the differences in line width falls within the predetermined threshold range, then steps S4 to S6 are executed cyclically: If neither of the differences in line width falls within a predetermined threshold range, then the line smoothness in the Nth focal graphic is identified. If the line smoothness in the Nth focal graphic does not fall within a predetermined second threshold range, then S4~S6 are executed repeatedly.

6. The method for determining the focal point of a laser cutting machine for cutting transparent dental instruments according to claim 1, characterized in that, The cutting pattern is a line segment.

7. A focus determination system for a laser cutting module used for cutting transparent dental instruments, characterized in that, include: The system includes a laser cutting module, a motion module, a processing module, a recognition module, and a central control module. The central control module controls the laser cutting module, motion module, processing module, and recognition module to perform the following actions: The motion module moves the workpiece to be cut step by step according to the set initial movement step size and initial movement direction, wherein the initial movement direction is the direction from the starting position to the focusing lens of the laser cutting module; After the motion module moves according to the initial step size, the laser cutting module cuts the workpiece to be cut once according to the predetermined path and pattern to form a cutting pattern. The identification module identifies the line width of the cutting pattern formed on the workpiece to be cut after each step, and compares the first focal pattern with the thinnest line width among the cutting patterns in this round and determines the position of the motion module on the motion trajectory when the first focal pattern is cut as the first focal position; and determines the first front adjacent pattern and the first rear adjacent pattern that are adjacent to the first focal pattern in the stepping direction. The processing module sets the position of the motion module corresponding to the first adjacent graphic in the current round when it is cut on the motion trajectory as the initial position of the next round of movement, sets the position of the motion module corresponding to the first adjacent graphic in the current round when it is cut on the motion trajectory as the termination position of the next round of movement, and sets the movement step size of the motion module in the next round, wherein the movement step size of the next round is smaller than the movement step size of the current round. The motion module moves from the initial position set by the processing module to the final position set by the processing module according to the movement step size set by the processing module. The laser cutting module cuts the workpiece to be cut once according to a predetermined path and pattern after the motion module moves each step according to the movement step size set by the processing module. The processing module identifies the line width of the outline of the cutting pattern formed on the workpiece to be cut after each step, and finds the Nth focal pattern with the thinnest outline among the cutting patterns in this round and determines the position of the motion module on the motion trajectory when the Nth focal pattern is cut as the Nth focal position; it determines the line width of the Nth preceding adjacent pattern and the Nth following adjacent pattern that are adjacent to the Nth focal pattern in the stepping direction, wherein N is equal to the number of times the processing module sets the initial position of the next round of movement + 1; The processing module compares the linewidth of the Nth focal graphic with the linewidth of the (N-1)th focal graphic: when the linewidth of the Nth focal graphic is greater than the linewidth of the (N-1)th focal graphic, the (N-1)th focal position corresponding to the (N-1)th focal graphic is determined as the focal position of the laser cutting module; when the linewidth of the Nth focal graphic is less than or equal to the linewidth of the (N-1)th focal graphic, the difference between the linewidth of the Nth focal graphic and the linewidths of the Nth preceding adjacent graphic and the Nth following adjacent graphic is calculated respectively; when one or two of the linewidth differences fall within a predetermined first threshold range, the Nth focal position is determined as the focal position of the laser cutting module; when neither of the linewidth differences falls within the first threshold range, the motion module is triggered.

8. The focus determination system for a laser cutting module for cutting transparent dental instruments according to claim 7, characterized in that, Also includes: The air blowing module blows air that covers the cutting area of ​​the workpiece to be cut on the motion module.

9. The focus determination system for a laser cutting machine for cutting transparent dental instruments according to claim 8, characterized in that, The air blowing module is located adjacent to and fixed relative to the laser cutting machine.

10. The focus determination system for a laser cutting machine for cutting transparent dental instruments according to claim 7, characterized in that, The motion module includes a stepper motor, a three-dimensional guide rail, and a bracket. The workpiece to be cut is fixedly connected to the bracket. The stepper motor controls the bracket to move on the three-dimensional guide rail. The three-axis directions of the three-dimensional guide rail include: the initial movement direction, a direction perpendicular to the initial movement direction on the horizontal plane, and a vertical direction.

11. The focus determination system for a laser cutting machine for cutting transparent dental instruments according to claim 7, characterized in that, The motion module includes a robotic arm with a clamping part at its end. The workpiece to be cut is connected to the robotic arm through the clamping part, and the robotic arm keeps the cutting surface of the workpiece facing the same direction after each step.

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