A nonlinear balance method for thickness and weight in single-sided machining of large plate-like components

Abstract

A nonlinear balance method for thickness and weight in single-sided machining of large plate components is disclosed, belonging to the technical field of single-sided machining of large plate components. This method first constructs an initial 3D model of the machining surface of the large plate component through photogrammetry; based on this model, digital layer-cutting simulation is used to calculate the optimal machining depth and generate a preliminary machining path; machining is performed along this path until halfway through, and ultrasonic thickness measurement and weighing are conducted. The actual nonlinear relationship model between "machining depth - remaining thickness - weight reduction" is calibrated and corrected using the measured data; based on the corrected model, the remaining machining depth is re-optimized, and the final machining path is determined according to the principle of prioritizing thickness safety, until completion. This invention solves the nonlinear balance problem between thickness and weight by reducing the number of weighing operations during machining and planning a machining scheme that ensures both weight and thickness meet standards.

Description

Technical Field

[0001] This invention relates to the field of single-sided machining technology for large plate components, and more particularly to a nonlinear balance method for thickness and weight in single-sided machining of large plate components. Background Technology

[0002] In the technical field of large plate components, there are situations where only single-sided machining is permitted. For example, large plate components with irregular deformations may have a complex array of protruding structures on one side that are difficult to fully map. Machining is only allowed on the non-protruding side to correct the deformation and meet overall weight and thickness requirements. After machining, the finished weight and thickness of critical areas must be controlled. This means the plate component can be divided into important and unimportant areas. The thickness of the important areas cannot be less than a thickness threshold. If the thickness of the important areas meets the standard, but the weight still exceeds the threshold, local cutting is allowed in unimportant areas to reduce the thickness to below the threshold, thus ensuring the weight of the plate component does not exceed the weight threshold. Therefore, single-sided machining of such large plate components presents the challenge of "non-linear constraints" on weight and thickness.

[0003] On the one hand, to control the total weight of the finished product within the limit, sufficient material removal must be planned; on the other hand, to ensure structural strength, the final wall thickness of critical areas cannot be lower than the safety threshold. Due to the irregular shape of the workpiece, uneven distribution of heat treatment deformation, and the fact that material removal is only done on one side, the impact of material removal on weight reduction and its impact on local thickness reduction are not simply linearly proportional. Traditional equal-allowance machining or trial cutting methods cannot quantitatively assess the combined impact of each cutting decision on these two indicators. They can only attempt to cut the entire surface first and continuously measure the weight as the thickness decreases, resulting in a highly discontinuous machining process interrupted by multiple weighings. Moreover, only after machining to the minimum thickness can it be found that the weight is still too high, requiring re-weighing before the final local machining can be planned. This is not only time-consuming and labor-intensive but also prone to insufficient wall thickness due to excessive cutting, becoming a bottleneck restricting the first-pass yield of plate components. Therefore, a more efficient and reasonable method is needed to achieve a non-linear balance between the thickness and weight of single-sided machining of plate components, reduce the number of weighings during the machining process, and plan a machining scheme that ensures both weight and thickness meet the standards. Summary of the Invention

[0004] The purpose of this invention is to provide a nonlinear balance method for thickness and weight in single-sided processing of large plate components, which reduces the number of weighing operations during processing and enables the planning of processing schemes that ensure both weight and thickness meet the requirements.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a nonlinear balance method for thickness and weight of large plate-like components processed on one side only. The plate-like component can be machined on only one side, and the surface of the machined side can be divided into important and unimportant regions. After processing, the thickness of the important region cannot be less than a thickness threshold, while the unimportant region is allowed to undergo local cutting to reduce its thickness to less than the thickness threshold, thereby ensuring that the weight of the plate-like component does not exceed the weight threshold. The method includes the following steps:

[0006] S1. Use a photogrammetry system to perform a full-area scan on the surface of the plate component blank to collect three-dimensional point cloud data of the surface to be processed and establish an initial surface feature model of the surface to be processed.

[0007] Based on 3D point cloud data, the overall flatness and deformation distribution of the surface to be processed are calculated, the workpiece orientation with the minimum processing amount is fitted, and the optimal processing reference plane is constructed accordingly.

[0008] S2. Based on the initial surface feature model obtained in S1, virtual processing simulation is performed using the material layer-cutting analysis method. The optimal processing reference plane is used for leveling. Starting from the thickest point of the surface to be processed, the material is removed layer by layer along the normal of the reference plane.

[0009] The processing depth of each layer is H. i The processing area S of the i-th layer is obtained through computer simulation. i Calculate the volume V of material removed from the newly added area of ​​each layer. i+ :

[0010] V i+ =(S i -S (i-1) )*H i / 2;

[0011] Calculate the volume V of all material removed from each layer. i :

[0012] V i =S (i-1) *H i +(S i -S (i-1) )*H i / 2;

[0013] Calculate the cumulative weight W removed from layers 1 to i based on the material density ρ. i :

[0014] W i = Σ(ρ * V i ) ;

[0015] Calculate the initial blank weight W0 and the cumulative removed weight Wi The weight difference is used to determine the initial processing scheme. When the weight difference reaches the weight threshold range, the theoretical total processing depth H corresponding to the first to i layers is retained, as well as the corresponding processing paths of each layer.

[0016] S3. Clamp and align the plate component blanks according to the initial processing plan, and then carry out actual processing. When the actual processing depth H1 reaches the predetermined proportion range of the theoretical total processing depth H, pause processing.

[0017] S4. Use an ultrasonic thickness gauge to scan and measure the thickness of all machined surfaces, and record the location corresponding to the minimum thickness.

[0018] S5. Weigh the plate-type components and obtain the actual removal weight W based on the difference between the initial blank weight and the real-time weight.

[0019] Based on the virtual machining simulation method of S2, the cumulative weight removed corresponding to the actual machining depth H1 is calculated and denoted as the theoretical weight removed W'.

[0020] Calculate the deviation ΔW = W - W';

[0021] S6. Based on the material density ρ, the cumulative weight W corresponding to the newly added area area removed from layers 1 to i is calculated. i+ The calculation formula is:

[0022] W i+ = Σ(ρ * V i+ );

[0023] The formula yields W corresponding to the theoretical total machining depth H. H+ Then calculate the correction factor K = ΔW / W H+ ;

[0024] S7. Calculate the cumulative removed weight W in S2. i The formula is replaced with:

[0025] W i = Σ(ρ * V i )+ W i+ *K;

[0026] The modified formula is used to perform virtual machining simulation again to obtain the secondary theoretical total machining depth H' that meets the weight threshold range, as well as the corresponding machining paths for each layer, thus forming a secondary machining scheme.

[0027] Based on the plate component model completed by the second virtual processing, the predicted thickness T corresponding to the minimum thickness position recorded in S4 is obtained;

[0028] S8. When the predicted thickness T meets the thickness threshold requirement, the plate component is further processed into a finished product according to the secondary processing plan.

[0029] When the predicted thickness T is less than the thickness threshold requirement, the secondary processing scheme is modified, and the plate component is processed into a finished product.

[0030] Preferably, in S3, machine tool alignment adjustment parameters or a virtual coordinate system are generated based on the optimal machining reference plane to facilitate the alignment and positioning of plate-type component blanks.

[0031] Preferably, in S3, the actual machining depth H1 is 40%-60% of the theoretical total machining depth H.

[0032] Preferably, the method for correcting the secondary processing scheme in S8 is to reduce the total theoretical secondary processing depth H' while retaining the processing paths of each layer, so as to ensure that the predicted thickness T' after correction and increase meets the thickness threshold requirement.

[0033] Calculate the weight of the plate component corresponding to the corrected theoretical total processing depth, and calculate the difference with the weight threshold to obtain the excess weight corresponding to the corrected theoretical total processing depth. Based on the excess weight, delineate the area and depth of local processing in non-critical areas to obtain the corrected secondary processing scheme.

[0034] According to the above technical solution, the beneficial effects of the present invention are:

[0035] 1. Solved the nonlinear balance problem between thickness and weight: This invention creatively integrates the control of two dimensions, weight (interval target) and thickness (lower limit target), and achieves one-time accurate target attainment through the process of "global measurement modeling - weight path planning - online calibration correction".

[0036] 2. Achieving a process transformation from "experience-driven" to "data-driven": Photogrammetry replaces manual marking, enabling rapid, global, and accurate alignment; "weighing + 3D model" predicts weight removal, transforming weight control from macroscopic estimation to microscopic calculation, significantly improving the first-piece success rate.

[0037] 3. A dynamic calibration and closed-loop control mechanism for the processing was established: The ultrasonic thickness measurement and weighing verification introduced midway not only verified the early planning, but also calibrated the material removal model online through feedback data, making subsequent predictions more accurate, and enabling proactive intervention and path correction, fundamentally preventing the risk of thickness deviation and accurately controlling the weight of the finished product.

[0038] 4. Significantly improves processing efficiency: This method systematically solves the problems of slow alignment and processing uncertainty, reduces trial cutting, repeated measurement and scrap, improves the processing efficiency of such workpieces by about 20%, maximizes material utilization and significantly reduces production costs.

[0039] In summary, compared with the existing processing method of cutting and weighing repeatedly, the present invention achieves non-linear balance of thickness and weight of single-sided processing of plate-type components in a more efficient and reasonable way, reduces the number of weighings during processing, and can plan a processing scheme that ensures that both weight and thickness meet the standards. Only one pause in processing for weighing is required to ensure the first-pass yield of the finished product processed according to the final scheme. Detailed Implementation

[0040] A nonlinear balance method for thickness and weight of large plate-like components during single-sided machining is provided. The plate-like components can only be machined on one side. The surface of the machined side can be divided into important and unimportant areas. After machining, the thickness of the important area cannot be less than a thickness threshold. The unimportant areas are allowed to be locally cut so that their thickness is less than the thickness threshold, thereby ensuring that the weight of the plate-like components does not exceed the weight threshold.

[0041] The method includes the following steps:

[0042] S1. Use a photogrammetry system to perform a full-area scan on the surface of the plate component blank to collect three-dimensional point cloud data of the surface to be processed and establish an initial surface feature model of the surface to be processed.

[0043] Based on 3D point cloud data, the overall flatness and deformation distribution of the surface to be processed are calculated, the workpiece orientation with the minimum processing amount is fitted, and the optimal processing reference plane is constructed accordingly.

[0044] S2. Based on the initial surface feature model obtained in S1, virtual processing simulation is performed using the material layer-by-layer analysis method. The optimal processing reference plane is used for leveling. Starting from the thickest point of the surface to be processed, the material is removed layer by layer along the normal of the reference plane.

[0045] The processing depth of each layer is H. i The processing area S of the i-th layer is obtained through computer simulation. i Calculate the volume V of material removed from the newly added area of ​​each layer. i+ :

[0046] V i+ =(S i -S (i-1) )*H i / 2.

[0047] Calculate the volume V of all material removed from each layer. i :

[0048] V i =S (i-1) *H i +(S i -S(i-1) )*H i / 2.

[0049] Calculate the cumulative weight W removed from layers 1 to i based on the material density ρ. i :

[0050] W i = Σ(ρ * V i ) .

[0051] Calculate the initial blank weight W0 and the cumulative removed weight W i The weight difference is calculated, and when the weight difference reaches the weight threshold range, the theoretical total processing depth H corresponding to the first to i layers is retained, as well as the corresponding processing paths of each layer, to form an initial processing scheme.

[0052] S3. Generate machine tool alignment adjustment parameters or virtual coordinate system based on the optimal machining reference plane, clamp the plate component blank according to the initial machining plan, and align it through the machine tool alignment adjustment parameters or virtual coordinate system. Then carry out actual machining. When the actual machining depth H1 reaches 40%-60% of the theoretical total machining depth H, pause machining.

[0053] S4. Use an ultrasonic thickness gauge to scan and measure the thickness of all machined surfaces, and record the location corresponding to the minimum thickness.

[0054] S5. Weigh the plate-type components and obtain the actual removal weight W based on the difference between the initial blank weight and the real-time weight.

[0055] Based on the virtual machining simulation method of S2, the cumulative weight removed corresponding to the actual machining depth H1 is calculated and denoted as the theoretical weight removed W'.

[0056] Calculate the deviation ΔW = W - W'.

[0057] S6. Based on the material density ρ, the cumulative weight W corresponding to the newly added area area removed from layers 1 to i is calculated. i+ The calculation formula is:

[0058] W i+ = Σ(ρ * V i+ ).

[0059] The formula yields W corresponding to the theoretical total machining depth H. H+ Then calculate the correction factor K = ΔW / W H+ .

[0060] S7. Calculate the cumulative removed weight W in S2. i The formula is replaced with:

[0061] W i= Σ(ρ * V i )+ W i+ *K.

[0062] The modified formula is used to perform virtual machining simulation again to obtain the secondary theoretical total machining depth H' that meets the weight threshold range, as well as the corresponding machining paths for each layer, thus forming a secondary machining scheme.

[0063] Based on the plate component model completed by the secondary virtual processing, the predicted thickness T corresponding to the minimum thickness position recorded in S4 is obtained.

[0064] S8、(1)When the predicted thickness T meets the thickness threshold requirement, the plate component is further processed into a finished product according to the secondary processing scheme.

[0065] (2) When the predicted thickness T is greater than the thickness threshold requirement, it means that the weight of the component has been processed to the required level, but the thickness is still too large, that is, there is still too much material in the component. This situation indicates that the design size and design volume of the component do not correspond to the design weight. It is a design error rather than a problem that needs to be solved in the processing process. Therefore, this situation does not need to be considered when designing the processing method.

[0066] (3) When the predicted thickness T is less than the thickness threshold requirement, the secondary processing scheme is modified. While retaining the processing paths of each layer, the total theoretical secondary processing depth H' is reduced to ensure that the predicted thickness T' after modification meets the thickness threshold requirement.

[0067] Calculate the weight of the plate component corresponding to the corrected theoretical total machining depth, and calculate the difference between the weight and the weight threshold to obtain the excess weight corresponding to the corrected theoretical total machining depth.

[0068] Based on the excess weight, the area and depth of local processing are defined in non-critical areas to obtain a revised secondary processing plan, and the plate components are further processed to the finished product.

[0069] Example: Single-sided machining of large circular plates:

[0070] This part is machined on only one side, and the final product must meet both weight and thickness specifications: ① Thickness in the central area ≥ T mm; ② Total weight not exceeding W tons. Due to the complex irregular deformation of the workpiece, and the presence of protrusions of varying depths pressed into the center of the non-machined surface, the initial grinding point measurement thickness allowance is approximately 25-35 mm.

[0071] Step 1: On the workpiece's end face to be machined, draw concentric circles with the center as the origin, spaced 850mm apart, and divide each circle into 16 equal parts. A total of 80 measurement markers (divided into five groups: A, B, C, D, and E) are affixed at the intersections. A high-precision industrial photogrammetry system is used to perform a full-area scan, acquiring the three-dimensional coordinates of all markers to establish an initial surface feature model of the machined surface. The initial weight W0 is then determined.

[0072] Step 2: Iterative solution for machining depth under dual nonlinear constraints of weight and thickness. Through layer-by-layer cutting simulation combined with iterative calculation, an optimal machining depth is determined for the total weight removal. Using high-point tool setting and a machining depth of 25mm, the final weight removal ensures that the weight does not exceed the limit.

[0073] Step 3: Nonlinear relationship calibration and model correction during processing. Processing is paused when approximately 60% of the planned total depth (approximately 20mm, 87% of the workpiece area exposed to light). Ultrasonic thickness measurement revealed that the thinnest area actually had a thickness margin of 6mm. Weighing results showed that the weight was removed, and the measurement results matched the prediction.

[0074] Step 4: Replan the remaining machining depth-weight machining path. Continue machining until the thinnest area has a thickness allowance of 1mm, which is expected to control the target weight. Continue machining according to the planned path to the finished product.

[0075] Results: Center thickness: Ultrasonic multi-point testing showed the thinnest area thickness was T+1mm, meeting the requirements. Weight: The finished product weight was within 0.5 tons of the target weight.

Claims

1. A method for balancing the thickness and weight of a large plate member in one-sided machining, wherein the plate member is capable of being machined only on one side, the machined side can be divided into an important area and a non-important area, the thickness of the important area after machining cannot be less than a thickness threshold, and the non-important area is allowed to be partially machined so that its thickness is less than the thickness threshold, thereby ensuring that the weight of the plate member does not exceed a weight threshold; characterized in that, The method comprises the following steps: S1, using a photogrammetry system to scan the entire surface of the plate component blank to be processed, collecting three-dimensional point cloud data of the surface to be processed, and establishing an initial surface feature model of the surface to be processed; Based on the three-dimensional point cloud data, the overall flatness and deformation distribution of the surface to be processed are calculated, the minimum processing amount of the visible flat workpiece orientation is fitted, and the optimal processing reference plane is constructed; S2, based on the initial surface feature model obtained in S1, a virtual machining simulation is performed using a material layer cutting analysis method, and the optimal processing reference plane is used for leveling, starting from the thickest point of the surface to be processed, and removing the material layer by layer along the normal direction of the reference plane; The machining depth of each layer is H i , the machining area S i of the i-th layer is obtained through computer simulation, and the volume V i+ of the material removed by the newly added area of each layer is calculated. V i+ = (S i - S (i-1) )*H i / 2; Calculate the volume V of all removed material per layer i : V i =S (i-1) *H i +(S i -S (i-1) )*H i / 2; According to the material density p, the cumulative removal weight W of the 1st to i-th layers is calculated i : W i = Σ(ρ * V i ) ; calculating a weight difference between the initial blank weight W0 and the cumulative removal weight W i When the weight difference reaches the weight threshold range, the theoretical total machining depth H corresponding to the first i layers and the corresponding machining path of each layer are retained to form an initial machining scheme. S3, according to the initial machining scheme, the plate component blank is clamped and aligned, and then actual machining is performed, and when the actual machining depth H1 reaches a predetermined proportion of the theoretical total machining depth H, the machining is paused; S4, using an ultrasonic thickness gauge to scan and measure the thickness of the entire machined surface, and recording the position corresponding to the minimum thickness; S5, weighing the plate component, and obtaining the actual removed weight W according to the difference between the initial blank weight and the real-time weight; According to the virtual machining simulation method of S2, the cumulative removed weight corresponding to the actual machining depth H1 is calculated, denoted as the theoretical removed weight W'; Calculate the deviation ΔW = W - W'; S6、According to the material density p, the corresponding weight W of the cumulative removal of the newly added area of the first i layer i+ The calculation formula is: W i+ = Σ(ρ * V i+ ) According to the formula, the W corresponding to the theoretical total machining depth H is obtained H+ Then, the correction coefficient K = AW / W is calculated H+ ; S7, replace the formula of S2 with the following formula: i S7, replace the formula of S2 with the following formula: W i = Σ(ρ * V i )+ W i+ *K; Using the corrected formula to perform virtual machining simulation again, obtain the secondary theoretical total machining depth H' that meets the weight threshold range, and the corresponding layer machining path, form the secondary machining scheme; According to the plate component model completed by the secondary virtual machining, the predicted thickness T corresponding to the minimum thickness position recorded in S4 is obtained; S8, when the predicted thickness T meets the thickness threshold requirement, continue to machine the plate component to the finished product according to the secondary machining scheme; When the predicted thickness T is less than the thickness threshold requirement, correct the secondary machining scheme, and continue to machine the plate component to the finished product.

2. A method for non-linear balancing of thickness and weight in single-sided processing of large plate members according to claim 1, characterized in that: In S3, the optimal processing reference plane is used to generate machine tool alignment adjustment parameters or a virtual coordinate system to facilitate the alignment and positioning of the plate component blank.

3. A method for non-linear balancing of thickness and weight in single-sided processing of large plate members according to claim 1, characterized in that: In S3, the actual machining depth H1 is 40%-60% of the theoretical total machining depth H.

4. A method of non-linear balancing of thickness and weight for single-sided processing of large plate members according to claim 1, characterized in that: In S8, the method for correcting the secondary machining scheme is to reduce the secondary theoretical total machining depth H' while keeping the layer machining path, and ensure that the corrected predicted thickness T' meets the thickness threshold requirement; Calculate the weight of the plate component corresponding to the corrected theoretical total machining depth, and calculate the difference with the weight threshold to obtain the excess weight corresponding to the corrected theoretical total machining depth, and according to the excess weight, the area and depth of local machining in the non-important area are determined to obtain the corrected secondary machining scheme.