Low-thermal-stress laser precision cutting process suitable for thin-wall hardware

Abstract

The invention relates to the technical field of intelligent welding systems, and provides a low-thermal-stress laser precision cutting process suitable for thin-wall hardware, which comprises the following steps: establishing a three-dimensional model of the thin-wall hardware, and extracting a cutting path of each cutting area of the three-dimensional model; evaluating the sensitive degree of the cutting area to thermal stress, and constructing the heat capacity rigidity ratio of the cutting area; evaluating the significance degree of the thermal interaction influence of the cut area on the cut area, and constructing the accumulated heat conduction influence degree of the cut area; and deformation factors of the cutting areas are determined, the cutting sequence of all the cutting areas of the thin-wall hardware is determined in combination with the heat capacity rigidity ratio, and laser precision cutting of the thin-wall hardware is completed according to the cutting sequence. The method aims at determining the cutting sequence of the thin-wall hardware, and plastic deformation, caused by the heat accumulation effect, of the thin-wall hardware in the cutting process is avoided.

Description

Technical Field

[0001] This application relates to the field of intelligent welding system technology, specifically to a low thermal stress laser precision cutting process suitable for thin-walled hardware parts. Background Technology

[0002] Thin-walled hardware refers to hardware parts made of metal materials such as steel, aluminum, copper, and stainless steel, whose wall thickness is much smaller than their length, width, or diameter, making them lightweight metal components. Low-thermal-stress laser precision cutting is a high-precision cutting process that addresses the easily deformable characteristics of thin-walled hardware by using a high-energy-density, narrow-pulse-width laser beam combined with precision motion control technology to achieve low-heat input and low-stress.

[0003] In the process of low thermal stress laser precision cutting of thin-walled hardware parts, a fixed geometric sequence is generally used for cutting. The heat accumulation effect is not considered, which can easily cause heat to continuously accumulate in local areas, forming an uneven thermal stress field. This can easily lead to uncontrollable bending, warping and other plastic deformations in thin-walled hardware parts. Summary of the Invention

[0004] This application provides a low-thermal-stress laser precision cutting process suitable for thin-walled hardware parts, in order to solve the problem that the low-thermal-stress laser precision cutting process does not consider the heat accumulation effect, which easily leads to uncontrollable plastic deformation of thin-walled hardware parts. The specific technical solution adopted is as follows: One embodiment of this application provides a low thermal stress laser precision cutting process suitable for thin-walled hardware parts, the process including the following steps: Create a 3D model of the thin-walled hardware and extract the cutting path of each cutting area of ​​the 3D model; The shape of the cutting region and the length of the cutting path in the cutting region are analyzed to construct the thermal capacity stiffness ratio of the cutting region. The thermal capacity stiffness ratio is used to characterize the sensitivity of the cutting region to thermal stress. By analyzing the distance between different cutting regions and the length of the cutting path within each region, the cumulative heat conduction influence of the cutting regions is constructed. This cumulative heat conduction influence is used to characterize the degree to which the cutting regions are significantly affected by the thermal interaction with the already cut regions. By combining the thermal capacity-stiffness ratio and the degree of influence of cumulative heat conduction, the deformation factor of the cutting area is determined. By combining the thermal capacity-stiffness ratio, the cutting sequence of all cutting areas of the thin-walled hardware is determined, and the laser precision cutting of the thin-walled hardware is completed according to the cutting sequence.

[0005] Furthermore, the shape of the cutting region is used to determine the area-to-perimeter ratio of the cutting region.

[0006] Furthermore, the thermal capacity stiffness ratio of the cutting region is positively correlated with the cross-sectional narrowness coefficient of the cutting region and negatively correlated with the area-to-perimeter ratio of the cutting region. The cross-sectional narrowness coefficient of the cutting region is used to characterize the strength of the thermal accumulation effect of the cutting region.

[0007] Furthermore, the cross-sectional narrowness coefficient of the cutting region is negatively correlated with the area of ​​the cutting region and positively correlated with the length of the cutting path in the cutting region.

[0008] Furthermore, the distance between the different cutting regions is the distance between the geometric centers of the different cutting regions.

[0009] Furthermore, the cumulative thermal conduction influence of the cutting area is the sum of the thermal conduction influence of the cutting area and all other different cutting areas.

[0010] Furthermore, the method for determining the degree of thermal conduction influence between the cut area and all other cut areas is as follows: The product of the thermal conductivity attenuation factor of the cut region and other different cut regions and the length of the cut path in the cut region is denoted as the degree of thermal conductivity influence between the target cut region and the comparison cut region. This thermal conductivity attenuation factor is used to characterize the rate of thermal conductivity attenuation between the cut region and other cut regions.

[0011] Furthermore, the thermal conductivity attenuation factor of the cut area compared to other different cut areas is the result of negative correlation processing of the distance between the cut area and other different cut areas.

[0012] Furthermore, the deformation factor of the cutting region is the product of the thermal capacity stiffness ratio of the cutting region and the degree of cumulative heat conduction influence.

[0013] Furthermore, the specific process for determining the cutting sequence of all cutting areas of the thin-walled hardware is as follows: Select the area with the highest heat capacity-stiffness ratio as the first area to be cut, and complete the cutting. Cut the uncut area corresponding to the largest cumulative heat conduction influence, and repeat the process of selecting and cutting the remaining uncut areas corresponding to the largest cumulative heat conduction influence until all areas have been cut.

[0014] The beneficial effects of this application are: This application considers two core factors influencing the deformation risk of thin-walled hardware: first, the thermal stress sensitivity determined by the shape of the cutting area itself; and second, the cumulative thermal effect of the cut area on the area to be cut. First, based on the shape of the cutting area and the length of the cutting path, the sensitivity of the cutting area to thermal stress is evaluated, and the thermal capacity-stiffness ratio of the cutting area is obtained. Then, the characteristics of heat conduction from the cut area to the area to be cut through the thin-walled hardware body are analyzed. Since a greater thermal interaction influence leads to a higher risk of deformation in the area to be cut, the significance of the thermal interaction influence of the cut area on the cut area is evaluated, and the cumulative thermal conduction influence of the cutting area is obtained. A greater cumulative thermal conduction influence in the cutting area indicates a higher risk of deformation. The more significant the thermal interaction between the cutting area and all other cutting areas, the more significant the cumulative thermal impact of the already cut areas on the cutting area. Finally, considering the sensitivity of each cutting area to its own thermal stress and the cumulative effect of thermal conduction between the cut and uncut areas, the cutting sequence of all cutting areas of the thin-walled hardware is determined. The cutting areas with higher sensitivity to thermal stress and less cumulative thermal effect from the already cut areas are prioritized to reduce the risk of deformation of the thin-walled hardware due to surface heat accumulation during the cutting process. This completes the laser precision cutting of the thin-walled hardware and solves the problem that the low thermal stress laser precision cutting process does not consider the heat accumulation effect, which easily leads to uncontrollable plastic deformation of the thin-walled hardware. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a low-thermal-stress laser precision cutting process for thin-walled hardware parts, provided as an embodiment of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Please see Figure 1It illustrates a flow chart of a low-thermal-stress laser precision cutting process for thin-walled hardware parts according to an embodiment of this application. The process includes the following steps: Step S001: Establish a three-dimensional model of the thin-walled hardware and extract the cutting path of each cutting area of ​​the three-dimensional model.

[0019] Import the design drawings of the thin-walled hardware parts to be cut into CAD design software to obtain a 3D model of the thin-walled hardware parts. Use the CGAL computational geometry algorithm library to calculate the line segment Voronoi diagram of the cutting path of the 3D model and obtain the cutting path for each Voronoi cell.

[0020] Understandably, the cutting path and outline boundary of thin-walled hardware can be determined by using the 3D model and design drawings of the thin-walled hardware; one Voronoi cell is one cutting area.

[0021] In this embodiment, the lower left corner of the thin-walled hardware is taken as the origin of the coordinate system of the three-dimensional model of the thin-walled hardware. The X-axis is along the length of the thin-walled hardware, the Y-axis is along the width of the thin-walled hardware, and the Z-axis is along the vertical upward direction.

[0022] The use of the CGAL computational geometry algorithm library to obtain the Voronoi diagram of line segments is a well-known technique and will not be elaborated further.

[0023] At this point, the cutting paths of each cutting area in the 3D model of the thin-walled hardware part have been obtained.

[0024] Step S002: Analyze the shape of the cutting area and the length of the cutting path in the cutting area, and construct the thermal capacity stiffness ratio of the cutting area. The thermal capacity stiffness ratio is used to characterize the sensitivity of the cutting area to thermal stress.

[0025] Thin-walled hardware has extremely thin walls, and its structural rigidity is much lower than that of thick-walled parts. During laser cutting, the high-energy laser beam causes the material of thin-walled hardware to heat up and expand rapidly in localized areas, while the temperature of the surrounding cutting area remains lower, creating an uneven thermal stress field. Since the thin-walled structure of the hardware itself lacks sufficient rigidity, it is difficult to resist the stress abrupt changes caused by sudden temperature changes, making it prone to material deformation, which ultimately manifests as overall bending, twisting, and other geometric deformations.

[0026] Under the premise of consistent cutting parameters, there are two core factors affecting the deformation risk of thin-walled hardware parts: first, the thermal stress sensitivity determined by the shape of the cutting area itself; and second, the cumulative thermal effect of the already cut area on the area to be cut. Among these, the higher the thermal stress sensitivity of the cutting area and the greater the cumulative thermal effect of the already cut area, the higher the probability of deformation during cutting.

[0027] Therefore, it is necessary to comprehensively consider the sensitivity of each cutting area of ​​thin-walled hardware to its own thermal stress, as well as the cumulative effect of thermal conduction between the cut and uncut areas. Priority should be given to cutting areas that are "more sensitive to their own thermal stress and have a smaller cumulative effect of thermal effects from the cut areas" to reduce the risk of deformation of thin-walled hardware caused by surface heat accumulation during the cutting process.

[0028] When cutting different areas of a thin-walled metal part with uniform thickness, the geometric characteristics of these areas differ. Even when using the same set of laser cutting parameters, the sensitivity of different areas to deformation caused by the thermal effect of cutting varies. Cutting areas with higher thermal sensitivity are more likely to deform during the cutting process. Therefore, it is necessary to first evaluate the deformation sensitivity of each cutting area of ​​the thin-walled metal part to thermal effects.

[0029] Calculate the area-to-perimeter ratio of the cut region.

[0030] Preferably, as an embodiment of this application, the area-to-perimeter ratio of the cut region is the ratio of the area to the perimeter of the cut region.

[0031] When calculating the ratio, the perimeter of the cut region cannot be 0. Therefore, the formula for calculating the ratio of the area to the perimeter of the cut region is meaningful.

[0032] The area-to-perimeter ratio of the cut region is used to evaluate the compactness of the cut region. The larger the area-to-perimeter ratio, the closer the shape of the cut region is to a circle or square. Thermal stress can be transferred more evenly to the periphery through the material, making it less prone to local instability or excessive deformation. The cut region exhibits lower thermal sensitivity and stronger inherent structural stiffness.

[0033] The cross-sectional narrowness coefficient of the cutting area is calculated based on the area of ​​the cutting area and the length of the cutting path in the cutting area. The cross-sectional narrowness coefficient of the cutting area is negatively correlated with the area of ​​the cutting area and positively correlated with the length of the cutting path in the cutting area.

[0034] It is understood that the positive and negative correlations in this application refer to the relationship between the independent and dependent variables. A positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive or multiplicative relationship. A negative correlation means that the dependent variable decreases (increases) as the independent variable increases (decreases), and can be an inverse relationship or a subtractive relationship.

[0035] Preferably, as an embodiment of this application, the ratio of the area of ​​the cutting region to the length of the cutting path in the cutting region is denoted as the average width of the cutting region, and the ratio of the length of the cutting path in the cutting region to the average width of the cutting region is denoted as the cross-sectional narrowness coefficient of the cutting region.

[0036] The length of the cutting path in the cutting area can be extracted using CAD design software through the 3D model of the thin-walled hardware.

[0037] When calculating the ratio, the length of the cutting path and the area of ​​the cutting region cannot be 0. Therefore, the formula for calculating the cross-sectional narrowness coefficient of the cutting region is meaningful.

[0038] The cross-sectional narrowness coefficient of the cutting area is used to evaluate the strength of the heat accumulation effect in the cutting area. The larger the cross-sectional narrowness coefficient of the cutting area, the more difficult it is for the heat generated by laser cutting to dissipate. That is, the more easily the heat accumulates locally during cutting, and the higher the risk of thermal deformation in the cutting area.

[0039] The thermal capacity stiffness ratio of the cut region is calculated based on the cross-sectional narrowness coefficient and the area-to-perimeter ratio of the cut region. The thermal capacity stiffness ratio of the cut region is positively correlated with the cross-sectional narrowness coefficient and negatively correlated with the area-to-perimeter ratio of the cut region.

[0040] Preferably, as an embodiment of this application, the ratio of the cross-sectional narrowness coefficient of the cutting region to the area perimeter ratio is denoted as the thermal stiffness ratio of the cutting region.

[0041] When calculating the ratio, the area-to-perimeter ratio of the cut region cannot be 0. Therefore, the formula for calculating the thermal capacity-to-stiffness ratio of the cut region is meaningful.

[0042] The thermal stiffness ratio of the cut region is used to evaluate the sensitivity of the cut region to thermal stress.

[0043] At this point, the thermal stiffness ratio of all cut regions has been obtained.

[0044] Step S003: Analyze the distance between different cutting regions and the length of the cutting path in the cutting region to construct the cumulative heat conduction influence of the cutting region. The cumulative heat conduction influence is used to characterize the significance of the thermal interaction influence of the cutting region on the already cut region.

[0045] In actual laser cutting, even if cutting parameters such as laser intensity and cutting frequency remain consistent, the heat transfer effect generated in the already cut area will still affect the current cutting process. Heat from the already cut area will be conducted to the area to be cut through the thin-walled metal component. The greater this heat transfer effect, the higher the risk of deformation in the area to be cut. The core factors affecting the cumulative heat transfer amount include cutting time and the distance between the cutting areas.

[0046] To quantify the thermal interaction between the cut regions and the regions to be cut, it is necessary to analyze the cutting time of each region.

[0047] In the previous cuts of the same thin-walled metal part, the cumulative heat conduction effect of the previous cuts on the current cut mainly depends on the cutting time. Specifically, since the laser cutting parameters are consistent, the longer the cutting time, the stronger the cumulative heat effect and the greater the interference with subsequent cuts. At the same time, because the cutting parameters are fixed, the cutting time of each cutting area is directly determined by the length of its cutting path. Specifically, the longer the cutting path, the longer the required cutting time, and the greater the cumulative heat effect generated by that cut.

[0048] The length of the cutting path in the cutting region is denoted as the heat accumulation factor of the cutting region.

[0049] The heat accumulation factor of the cutting area is used to evaluate the amount of heat generated in the cutting area during cutting.

[0050] Analyzing the thermal interaction between the cut areas and the area to be cut also requires considering the distances between all cut areas and the area to be cut. The heat generated by laser cutting diffuses outwards along the surface of the thin-walled hardware. The closer the cut areas are to the geometric center of the area to be cut, the smaller the attenuation of the thermal effect, and the greater the impact on the current cutting.

[0051] The geometric center of each cut region is determined, and the distance between the geometric centers of different cut regions is denoted as the distance between different cut regions. The negative correlation result of the distances between different cut regions is denoted as the heat conduction attenuation factor of different cut regions.

[0052] Preferably, as an embodiment of this application, the reciprocal of the product of the distance between different cutting regions and a preset attenuation coefficient is denoted as the heat conduction attenuation factor of different cutting regions.

[0053] To avoid the denominator being zero during the reciprocal calculation, a preset value needs to be added to the denominator; in this example, the preset value is 1. The attenuation coefficient is a preset parameter, and its value is determined based on the thermal diffusivity of the material of the thin-walled hardware corresponding to the cutting area; in this embodiment, the attenuation coefficient is set to 0.05. .

[0054] The thermal conductivity attenuation factor of the cut region. It is used to characterize the rate of thermal conductivity attenuation between different cut regions. The larger the thermal conductivity attenuation factor of different cut regions, the faster the thermal conductivity attenuation between different cut regions.

[0055] Designate any one of the cut regions as the target cut region, and another cut region different from the target cut region as the comparison cut region. The positive correlation between the heat conduction attenuation factor of the target cut region and the heat accumulation factor of the comparison cut region, and the heat conduction influence of the target cut region and the comparison cut region, is recorded as the degree of heat conduction influence between the target cut region and the comparison cut region. The same method can be used to obtain the degree of heat conduction influence between any two different cut regions. The sum of the heat conduction influence degrees of the target cut region and all other cut regions is recorded as the cumulative heat conduction influence degree of the target cut region.

[0056] Preferably, as an embodiment of this application, the product of the thermal conduction attenuation factor of the target cutting region and the comparison cutting region and the thermal accumulation factor of the target cutting region is recorded as the degree of thermal conduction influence between the target cutting region and the comparison cutting region.

[0057] The greater the degree of thermal conduction influence between the target cutting area and the comparison cutting area, the more significant the thermal interaction between the target cutting area and the comparison cutting area. The greater the cumulative thermal conduction influence of the target cutting area, the more significant the thermal interaction between the target cutting area and all other cutting areas, and the more significant the cumulative thermal influence of the target cutting area on the already cut areas.

[0058] The cumulative heat conduction effect of any cut region can be obtained using the same method.

[0059] At this point, the cumulative thermal conduction impact of all cut areas is obtained.

[0060] Step S004: Combine the thermal capacity stiffness ratio and the degree of influence of cumulative heat conduction to determine the deformation factor of the cutting area. Combine the thermal capacity stiffness ratio to determine the cutting sequence of all cutting areas of the thin-walled hardware. Complete the laser precision cutting of the thin-walled hardware according to the cutting sequence.

[0061] The result of the positive correlation between the thermal capacity stiffness ratio of the cut region and the degree of cumulative heat conduction influence is denoted as the deformation factor of the cut region.

[0062] Preferably, as an embodiment of this application, the product of the thermal capacity stiffness ratio of the cut region and the cumulative thermal conduction influence is denoted as the deformation factor of the cut region.

[0063] The larger the deformation factor of the cutting area, the greater the possibility and risk of deformation in the cutting area during the cutting process.

[0064] When thin-walled hardware parts are not cut, there is no corresponding degree of thermal conduction influence and deformation factor for each cut area. The cut area with the largest thermal capacity stiffness ratio is selected as the first cut area. After the first cut area is completed, a cumulative thermal conduction influence matrix is ​​established based on the cumulative thermal conduction influence of all cut areas. Cutting is performed on the uncut areas corresponding to the largest cumulative thermal conduction influence in the cumulative thermal conduction influence matrix. After each cut area is completed, the cumulative thermal conduction influence matrix is ​​updated, and cutting continues on the uncut areas corresponding to the largest cumulative thermal conduction influence in the cumulative thermal conduction influence matrix until all cut areas are completed.

[0065] Specifically, the method for establishing the cumulative heat conduction influence matrix is ​​as follows: arrange the cumulative heat conduction influence of all cut regions according to the position of the cut regions, obtain the cumulative heat conduction influence matrix, and fill the empty positions in the cumulative heat conduction influence matrix with 0.

[0066] This determines the cutting sequence for all cutting areas of the thin-walled hardware.

[0067] It is important to note that during the cutting of thin-walled hardware, if the local deformation of the hardware exceeds 5% of its thickness, the cutting parameters need to be adjusted to suppress heat accumulation. These cutting parameters include laser power and cutting speed.

[0068] This completes the low-thermal-stress laser precision cutting of thin-walled hardware parts.

[0069] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A low-thermal-stress laser precision cutting process suitable for thin-walled hardware parts, characterized in that, The process includes the following steps: Create a 3D model of the thin-walled hardware and extract the cutting path of each cutting area of ​​the 3D model; The shape of the cutting region and the length of the cutting path in the cutting region are analyzed to construct the thermal capacity stiffness ratio of the cutting region. The thermal capacity stiffness ratio is used to characterize the sensitivity of the cutting region to thermal stress. By analyzing the distance between different cutting regions and the length of the cutting path within each region, the cumulative heat conduction influence of the cutting regions is constructed. This cumulative heat conduction influence is used to characterize the degree to which the cutting regions are significantly affected by the thermal interaction with the already cut regions. By combining the thermal capacity-stiffness ratio and the degree of influence of cumulative heat conduction, the deformation factor of the cutting area is determined. By combining the thermal capacity-stiffness ratio, the cutting sequence of all cutting areas of the thin-walled hardware is determined, and the laser precision cutting of the thin-walled hardware is completed according to the cutting sequence.

2. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 1, characterized in that, The shape of the cutting region is used to determine the area-to-perimeter ratio of the cutting region.

3. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 2, characterized in that, The thermal capacity stiffness ratio of the cut region is positively correlated with the cross-sectional narrowness coefficient of the cut region and negatively correlated with the area-to-perimeter ratio of the cut region. The cross-sectional narrowness coefficient of the cut region is used to characterize the strength of the thermal accumulation effect of the cut region.

4. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 3, characterized in that, The cross-sectional narrowness coefficient of the cutting region is negatively correlated with the area of ​​the cutting region and positively correlated with the length of the cutting path in the cutting region.

5. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 1, characterized in that, The distance between the different cutting regions is the distance between the geometric centers of the different cutting regions.

6. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 1, characterized in that, The cumulative thermal conductivity effect of the cut area is the sum of the thermal conductivity effects of the cut area and all other different cut areas.

7. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 6, characterized in that, The method for determining the degree of thermal conduction influence between the cut area and all other cut areas is as follows: The product of the thermal conductivity attenuation factor of the cut area and other different cut areas and the length of the cut path in the cut area is denoted as the degree of thermal conductivity influence between the target cut area and the comparison cut area. The thermal conductivity attenuation factor of the cut area is used to characterize the rate of thermal conductivity attenuation between the cut area and other cut areas.

8. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 7, characterized in that, The thermal conductivity attenuation factor of the cut area compared to other different cut areas is the result of negative correlation processing of the distance between the cut area and other different cut areas.

9. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 1, characterized in that, The deformation factor of the cut region is the product of the thermal capacity stiffness ratio of the cut region and the degree of cumulative heat conduction influence.

10. The low thermal stress laser precision cutting process for thin-walled hardware parts according to claim 1, characterized in that, The specific process for determining the cutting sequence of all cutting areas of the thin-walled hardware is as follows: Select the area with the highest heat capacity-stiffness ratio as the first area to be cut, and complete the cutting. Cut the uncut area corresponding to the largest cumulative heat conduction influence, and repeat the process of selecting and cutting the remaining uncut areas corresponding to the largest cumulative heat conduction influence until all areas have been cut.

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