CN-121980819-A - Method and system for controlling angle and thinning rate of bent pipe

Abstract

The invention relates to the technical field of bend forming control, in particular to a bend angle and thinning rate control method and a system, wherein the angle pushing quantity value and the curvature rate value are constructed into continuous sequences according to step numbers, a time convolution network is introduced to carry out convolution calculation on the variation amplitude between adjacent steps, so that the angle variation and the curvature variation in the bending process are not judged as isolated parameters any more, but are combined and analyzed based on a time sequence association relation, and a near-end strategy optimization algorithm is introduced to execute proportion down-regulation on the bending speed value and the curvature change rate value corresponding to the current step, and the reverse angle offset is synchronously overlapped, so that parameter adjustment is limited in a near-end area near the current step, the large-range disturbance on the whole bending path is avoided, and meanwhile, parallel records of the original parameters and the correction parameters are reserved, so that the subsequent angle accumulation and correction process has a clear data basis.

Inventors

• PAN JINLIANG
• PAN XIN

Assignees

• 常州良旭车辆配件有限公司

Dates

Publication Date

20260505

Application Date

20260402

Claims (10)

1. 1. The method for controlling the angle and the thinning rate of the bent pipe is characterized by comprising the following steps of: S1, setting a target bending angle value, an angle error bandwidth, a thinning rate upper limit value and a bending step number upper limit value, inputting a bending die radius value, a clamping die pressure value, a core rod extension value, a bending speed value and an angle propulsion value, and grouping the values according to step numbers to obtain a bending plan parameter table; s2, based on the bending plan parameter table, splicing the angle propulsion magnitude and curvature change rate value sequences of each step, calculating adjacent step difference values and marking abrupt step numbers by adopting a time convolution network, and outputting a thinning risk level sequence and a recommended termination step number to obtain a stepping termination instruction; S3, based on the stepping termination instruction, gradually applying a clamping die pressure value, a mandrel extension value, a bending speed value, a curvature change rate value and an angle pushing value, calculating an outside thinning rate estimated value and comparing the outside thinning rate estimated value with a thinning rate upper limit value, adopting a proximal strategy optimization algorithm, and adjusting the speed and the curvature down to an overrun and applying reverse angle bias to obtain a bending execution track set; S4, based on the bending execution track set, accumulating angle propulsion values to obtain accumulated bending angle values, calculating a difference value between the accumulated bending angle values and a target bending angle value to obtain an angle deviation value, and equally dividing the deviation to the rest steps when the angle deviation value exceeds the target bending angle value to obtain an angle propulsion correction sequence; And S5, updating the angle propulsion value of the remaining steps and executing the bending based on the angle propulsion correction sequence and the bending execution track set, comparing the accumulated bending angle value of the last step with the target bending angle value, and fine-tuning the propulsion of the last step and re-executing the final step when the angle propulsion correction sequence and the bending execution track set exceed the target bending angle value to obtain a forming termination state.
2. 2. The method according to claim 1, wherein the bending schedule parameter table includes a step number, an angle advance value, a bending speed value, a curvature change rate value, a clamping die pressure value, a press bending die pressure value, a mandrel extension value, a boosting ratio value, the step termination instruction includes a termination step number, a termination step number source identifier, a termination step number validity identifier, the bending execution track set includes a step number, an angle advance value, a bending speed value, a curvature change rate value, a clamping die pressure value, a mandrel extension value, and an outside thinning rate estimation value, the angle advance correction sequence includes a remaining step number sequence, an angle compensation amount per step, and a corrected angle advance value, and the forming termination state includes a termination step number, a final step angle deviation determination identifier, a final step advance amount trimming amount, and a final step weight execution identifier.
3. 3. The method for controlling the angle of a bent pipe and the thinning rate according to claim 1, wherein the specific steps of generating the bending plan parameter table are as follows: Based on the set target bending angle value, angle error bandwidth, thinning rate upper limit value and bending step number upper limit value, checking the matching relation between the target bending angle value and the step number upper limit value item by item, checking the value range of the angle error bandwidth and the thinning rate upper limit value, recording the item number which is not satisfied and merging the item number into a constraint item, and generating a process constraint parameter set; Based on the process constraint parameter set, aligning the radius value, the clamping die pressure value, the core rod extension value, the bending speed value and the angle pushing value according to step numbers, supplementing missing step number fields and locking field sequences, writing step number corresponding rows and summarizing the step number corresponding rows into a table structure to obtain a bending plan parameter table.
4. 4. The method for controlling the angle of the bent pipe and the thinning rate according to claim 1, wherein the specific step of generating the step termination instruction is: Based on the bending plan parameter table, extracting an angle propulsion magnitude value and a curvature change rate value according to a step number sequence, arranging parameters under the same step number in parallel, inserting a default occupation record into a missing step number, keeping the step sequence continuous, forming a step-by-step readable structure, and generating a step parameter sequence; based on the step parameter sequence, a time convolution network is adopted, the change amplitude of the angle propulsion and the change amplitude of the curvature of the adjacent steps are calculated gradually, the step number exceeding the preset change interval is marked, the marking result is written into a risk field according to the step number, a record corresponding to the step number one by one is formed, and a risk marking sequence is obtained; Based on the risk marking sequence, counting the occurrence positions of continuous risk marks, selecting the step number which meets continuous conditions earliest as a cut-off candidate value, comparing the cut-off candidate value with the upper limit value of the bending step number, confirming the effective number, and outputting the execution termination position to obtain the stepping termination instruction.
5. 5. The method of claim 1, wherein the time convolution network initializes the convolution layer group parameter, the normalization layer parameter, the activation layer parameter, the output layer parameter and loads the network weight file, reads the step parameter sequence and constructs the input tensor according to the step number sequence, the step number length of the dimension of the input tensor and the number of the characteristic channels, the characteristic channels take the angle propulsion value, the curvature change value, the angle propulsion adjacent difference value and the curvature change rate adjacent difference value and stack according to the fixed channel sequence, zero filling is carried out on input tensors, one-dimensional convolution is carried out according to a set convolution kernel length, convolution output sequentially passes through a normalization layer and an activation layer and enters an output layer after multi-layer convolution, the output layer generates a risk scoring sequence corresponding to each step and a mutation step number scoring sequence, the risk scoring sequence is mapped into a risk grade according to a threshold value and is written into a risk field according to a step number, the mutation step number scoring sequence is marked with a step number exceeding the threshold value according to a preset change interval threshold value and is written into a mutation marking field, and the risk grade field and the mutation marking field are aligned according to the step number and form a one-to-one record, so that the risk marking sequence is obtained.
6. 6. The method for controlling the angle and the thinning rate of the bent pipe according to claim 1, wherein the specific steps of generating the bending execution trajectory set are as follows: Based on the step termination instruction, calling a clamping die pressure value, a mandrel extension value, a bending speed value, a curvature change rate value and an angle pushing value according to a step number sequence, writing each parameter into a step-by-step execution list, and locking the sequence to generate an execution parameter sequence; Based on the execution parameter sequence, recording the outer wall thickness variation after each bending step is completed, converting the wall thickness variation into a corresponding thinning rate estimated value, gradually comparing the estimated value with the upper limit value of the thinning rate, and writing an overrun result into a corresponding step number field to obtain a thinning monitoring sequence; Based on the thinning monitoring sequence, a near-end strategy optimization algorithm is adopted, a bending speed value corresponding to the mark overrun step number and a curvature change rate value are adjusted down in proportion, reverse angle offset is overlapped under the same step number, an original value and a correction value comparison record are reserved, a continuous execution record is formed, and a bending execution track set is obtained.
7. 7. The method for controlling the angle of the bent pipe and the thinning rate according to claim 1, wherein the near-end policy optimization algorithm is characterized by firstly initializing policy network parameters, value network parameters, logarithmic probability buffer areas and track buffer areas, reading a thinning monitoring sequence and extracting an overrun step number set, constructing a state vector, the state vector taking the overrun step number to correspond to a bending speed value, a curvature change rate value, a reverse angle offset, a thinning rate estimated value and an thinning rate upper limit value difference and splicing according to a fixed sequence, outputting action distribution parameters and sampling action vectors for the state vector based on the policy network, taking a bending speed down-regulation proportion, a curvature change rate down-regulation proportion and a reverse angle offset increment for the action vector to execute upper and lower bound cutting, writing the state vector, the action logarithmic probability and the value network output value into the track buffer areas, calculating a return sequence and a dominance sequence based on a track buffer area, retrieving a difference value between the report sequence and an output value of a value network by the dominance sequence, recursively dividing the difference value by a discount coefficient and an attenuation coefficient, dividing the track buffer area into a plurality of batches of samples, circularly iterating and updating, calculating new strategy action logarithmic probability and calculating a ratio of the new strategy action logarithmic probability to the buffered action logarithmic probability to obtain a probability ratio, cutting the probability ratio according to a cutting coefficient, multiplying the probability ratio by an unclamped probability ratio by the dominance sequence, taking two smaller values to construct a strategy target item, simultaneously calculating a mean square error between the value target item and the output value of the value network, constructing a value error item, weighting and summing the strategy target item, the value error item and an entropy regularization item to obtain a total loss item, executing gradient back propagation on the total loss item, updating strategy network parameters and the value network parameters, calculating approximate divergence after updating, comparing the approximate divergence with a divergence threshold value, and stopping the current iteration round when overrun, outputting the updated motion vector, writing the bending speed value, the curvature change rate value and the reverse angle offset field corresponding to the overrun step number, and reserving the comparison record of the original value and the correction value.
8. 8. The method for controlling the angle of the bent pipe and the thinning rate according to claim 1, wherein the specific step of generating the angle propulsion correction sequence is: Based on the bending execution track set, extracting an angle propulsion magnitude sequence according to step numbers, sequentially accumulating and writing the angle propulsion magnitude sequence into each step of accumulated position, writing an accumulated bending angle value field into the last item, and reserving a step number mapping relation to generate an accumulated bending angle value; Based on the accumulated bending angle value, reading a target bending angle value, calculating a difference value, extracting the number of remaining steps, performing equal division on the difference value, and gradually overlapping the equal division result to the remaining step angle propulsion magnitude item to form a correction item arranged according to step numbers, thereby obtaining an angle propulsion correction sequence.
9. 9. The method for controlling the angle of the bent pipe and the thinning rate according to claim 1, wherein the specific step of generating the forming termination state is: Based on the angle propulsion correction sequence and the curved execution track set, matching the remaining step items according to step numbers, covering the corrected angle propulsion magnitude with the corresponding items, recording the coverage marks, summarizing the remaining step items and the executed step items to form a continuous step sequence, and generating an updated step parameter set; Based on the updated stepping parameter set, reading a final accumulated bending angle value and a target bending angle value, calculating a final difference value, when the final difference value exceeds an angle error bandwidth, overlapping the difference value to a final propulsion amount according to a symbol direction, updating the final propulsion amount, and writing a re-execution mark to obtain a forming termination state.
10. 10. A bend angle and thinning rate control system according to any of claims 1-9, the system comprising: the parameter planning module is used for setting a target bending angle value, an angle error bandwidth, a thinning rate upper limit value and a bending step number upper limit value, inputting a bending die radius value, a clamping die pressure value, a core rod extension value, a bending speed value and an angle propulsion value, and grouping the values according to step numbers to obtain a bending plan parameter table; The stepping evaluation module is used for splicing the angle advancing magnitude and curvature change rate value sequences of each step based on the bending plan parameter table, calculating the adjacent step difference value and marking the abrupt step number by adopting a time convolution network, outputting the thinning risk level sequence and the recommended termination step number, and obtaining a stepping termination instruction; the thinning regulation and control module is used for gradually applying a clamping die pressure value, a mandrel extension value, a bending speed value, a curvature change rate value and an angle pushing value based on the stepping termination instruction, calculating an outside thinning rate estimated value and comparing the outside thinning rate estimated value with a thinning rate upper limit value, adopting a near-end strategy optimization algorithm, and adjusting the speed and the curvature and applying reverse angle bias when exceeding the limit to obtain a bending execution track set; The angle correction module is used for accumulating the angle propulsion values to obtain accumulated bending angle values based on the bending execution track set, calculating the difference value between the accumulated bending angle values and the target bending angle values to obtain angle deviation values, and equally dividing the deviation values to the rest steps when the angle deviation values exceed the target bending angle values to obtain an angle propulsion correction sequence; and the forming termination module is used for updating the angle propulsion value of the remaining steps and executing the bending based on the angle propulsion correction sequence and the bending execution track set, comparing the accumulated bending angle value of the last step with the target bending angle value, and finely adjusting the propulsion of the last step and executing again when the angle propulsion correction sequence and the bending execution track set exceed the target bending angle value to obtain a forming termination state.

Description

Method and system for controlling angle and thinning rate of bent pipe Technical Field The invention relates to the technical field of bend forming control, in particular to a method and a system for controlling a bend angle and a thinning rate. Background The technical field of bend forming control aims at restraining a bending path, a stress state and a forming termination condition in the plastic bending deformation process of a metal pipe so that the bending angle of the pipe meets the preset geometric requirement, and intensively controlling the wall thickness reduction, the section distortion and the strain generated in the bending process within a set range to obtain a bend forming part with consistent geometric dimension and wall thickness distribution meeting the use requirement The method for controlling the angle of the bent pipe and the thinning rate aims at controlling bending forming parameters and deformation termination conditions in the bending forming process of the metal pipe, so that the bending angle of the formed pipe reaches a preset angle value, the thinning rate of the pipe wall at the outer side of the bending is limited within a preset threshold range, and the problems of insufficient forming precision and reduced bearing performance caused by bending angle deviation or overlarge wall thickness thinning are avoided. The existing bend forming control mode is usually focused on carrying out result verification on bending angles and thinning rates at the bending end stage, the whole bending operation is carried out in an actual execution process by more depending on fixed process parameters or experience setting parameters, a continuous monitoring mechanism for state change among steps in the bending process is lacked, in the actual operation, when bending speed, curvature change or stress state deviate in the middle, the bending speed, curvature change or stress state cannot be recognized in early stages, the problem of angle deviation or outer wall thickness overrun can only be found through measurement after bending is finished, in addition, in the prior art, a single compensation or end correction mode is mostly adopted in angle control, when the accumulated error is gradually amplified in the bending process, the end one-time correction easily causes local strain concentration, aggravates the phenomenon of section distortion or wall thickness unevenness, in the thinning control aspect only takes the thinning rate as a final evaluation index, even if obvious thinning trend occurs in the bending process, the irreversible damage is easily formed in a specific step, in the prior art, the judgment of forming termination conditions is mostly based on a single angle threshold, the dynamic evolution characteristic in the stepping process is ignored, in the bending process is easy, the condition that the angle deviation or the bending termination condition easily reaches the standard, the angle is easily reached in the complex bending path or the bending scene, the condition is not distributed in the multiple steps, the condition is not suitable for the condition of the existing pipe is limited in the bending process, and the problem is especially stable, and the problem is remarkably limited in the bending condition or is severe, and is more stable, and is suitable for the bending condition. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a method and a system for controlling the angle and the thinning rate of an elbow. In order to achieve the purpose, the invention adopts the following technical scheme that the method for controlling the angle of the bent pipe and the thinning rate comprises the following steps: S1, setting a target bending angle value, an angle error bandwidth, a thinning rate upper limit value and a bending step number upper limit value, inputting a bending die radius value, a clamping die pressure value, a core rod extension value, a bending speed value and an angle propulsion value, and grouping the values according to step numbers to obtain a bending plan parameter table; s2, based on the bending plan parameter table, splicing the angle propulsion magnitude and curvature change rate value sequences of each step, calculating adjacent step difference values and marking abrupt step numbers by adopting a time convolution network, and outputting a thinning risk level sequence and a recommended termination step number to obtain a stepping termination instruction; S3, based on the stepping termination instruction, gradually applying a clamping die pressure value, a mandrel extension value, a bending speed value, a curvature change rate value and an angle pushing value, calculating an outside thinning rate estimated value and comparing the outside thinning rate estimated value with a thinning rate upper limit value, adopting a proximal strategy optimization algorithm, and adjusting the speed and the curvature down to an overr