Track compensation method for mirror image additive manufacturing of composite material component

Abstract

A mirror image additive manufacturing track compensation method for a composite material component is characterized in that two material deposition heads are symmetrically distributed along the center face of the component and synchronously move, and materials are stacked towards the two sides of the center face at the same time. A distance sensor is arranged on each deposition head, and the actual position of the deposited component is measured in the normal direction of the center face. And the compensation amount of the next track point is calculated and corrected in real time by calculating the deviation between the actual position and the theoretical position, recording the historical deviation and combining the curvature of the track point, so that the G code track of the double deposition heads is adjusted in real time. According to the method, the deviation between the component shape and the theoretical model in the additive manufacturing process can be effectively reduced, and the deposition precision and the forming quality are improved. In addition, according to the distance measurement method, a combination mode of sound wave distance measurement, photoelectric distance measurement, laser radar and visual fusion distance measurement can be selected, and the accuracy of real-time compensation is ensured.

Description

Technical Field

[0001] The present invention relates to the field of motion control, in particular to a technology for compensating the motion trajectory of a mirror control curve in additive manufacturing, and specifically to a trajectory compensation method for mirror additive manufacturing of composite components. Background Art

[0002] Due to excellent properties such as light weight, high strength, and corrosion resistance, composite materials are widely used in high-tech fields such as aerospace, automobiles, and ships. However, the manufacturing process of composite materials is complex. Especially in the traditional process that relies on molds for manufacturing and does not use double-sided laying heads, the manufacturing cycle of the mold can account for half of the entire production cycle, and problems such as uneven stress distribution are difficult to solve. The mirror additive manufacturing proposed in the present invention uses double-sided deposition heads that are symmetric about the central plane, which can achieve mirroring of the temperature field, trajectory, and pressure on both sides of the deposited component, thus avoiding the dependence on the mold and improving the problem of uneven stress distribution on both sides.

[0003] The prerequisite for precise mirror additive manufacturing is to solve problems such as no support for laying, easy deformation when suspended, and inaccurate positioning. There are mainly two existing feasible solutions, namely the offline compensation and the online compensation methods. Offline compensation is to calculate the dimensional deviation of the component based on thermal and mechanical simulation before actual manufacturing, and obtain the compensated G-code through iterative optimization of the trajectory. For example, CN201810089034 provides a method for predicting the deformation of additive manufacturing parts with a short calculation time. However, this method is difficult to solve the random errors caused by material and process uncertainties during the additive manufacturing process. Online compensation is to measure the deformation of the component in real time through a position sensor, and then calculate the compensation amount in real time through a compensation algorithm, so as to ensure that the position deviation of the component during the manufacturing process is always in a small state. For example, CN202110000780 is based on the already mature real-time three-dimensional detection technology, and considering features such as the morphology of the substrate surface, the molten pool, and the newly formed surface, a double closed-loop control system is established to adjust the printing trajectory online. However, the existing compensation methods are all used for traditional additive manufacturing methods with single-sided mold reliance, single-sided heating, and single-direction stacking. For the mirror additive manufacturing scenario of the present invention, due to problems such as no mold for forming, no support for the structure, large self-weight of the structure, and severe thermal / phase change shrinkage, the deformation behavior and mode of the component have undergone fundamental and complex changes compared with the traditional method, and there is an urgent need to develop an online trajectory compensation method with dynamically adjustable parameters.

[0004] In the recent invention related to mirror additive manufacturing such as CN118544589A, a thermo-mechanical field with a "mirror" distribution is proposed to reduce stress. Thereby, the deformation of the additive manufacturing structure is significantly suppressed, and high-precision additive manufacturing is achieved.

[0005] The present invention aims to solve the problems of uneven stress distribution, long manufacturing cycle, and insufficient mirror trajectory accuracy in existing additive manufacturing devices, and proposes a trajectory compensation method for mirror additive manufacturing of composite components. Summary of the Invention

[0006] The object of the present invention is to address the issues that during the mirror additive manufacturing process of thermoplastic composite materials, the deposited components are affected by factors such as thermal expansion and contraction, structural self-weight, and phase change shrinkage. Especially in the process of mirror additive manufacturing with two deposition heads without a mold, thermal expansion and contraction and structural self-weight have a greater impact on the manufacturing process, and it is inevitable to produce deformation, resulting in uneven stress distribution and other problems in the finally manufactured components. The invention provides a trajectory compensation method for mirror additive manufacturing of composite components, which is a trajectory compensation method based on a component curvature variable parameter control algorithm. It breaks through the limitations of large deformation, uneven stress distribution, and inapplicability to curved surface parts in mirror additive manufacturing. Through curvature correction, a proportional / integral / differential parameter mapping relationship for curved surface additive manufacturing is established, thereby improving the adaptability of mirror additive manufacturing equipment to different curvature components. It provides a new feasible technical solution for the trajectory compensation of mirror additive manufacturing.

[0007] The technical solution of the present invention is as follows:

[0008] A trajectory compensation method for mirror additive manufacturing of composite components, characterized in that two material deposition heads are symmetrically distributed along the central plane of the component, move synchronously, and synchronously stack materials on both sides of the central plane; distance sensors are respectively arranged on the two deposition heads to measure the actual position of the deposited component along the normal direction of the central plane; calculate the deviation δ between the actual position and the current trajectory point of the theoretical position of the component i , and at the same time record the historical deviation δ of the historical trajectory point i-1 , δ i-2 ……, according to the above deviation values, considering the curvature λ of the trajectory point where it is located i calculate the compensation amount C of the next trajectory point in real time i+1 , and use this compensation amount to modify the G code of the running trajectory of the two deposition heads in real time.

[0009] The real-time calculation method adopts a proportional / integral / differential method with parameter real-time calibration; the parameters are real-time calibrated according to the curvature λ of the current trajectory point i , so that the deposited structure maintains a small deviation from the theoretical shape. The formula of the calculation method is as follows:

[0010] C(λ i ,i + 1) = P(λ i ) * δ i + I(λ i ) * δ intergral + D(λ i ) * Δδ

[0011] Among them

[0012] The meanings of the parameters in the formula are as follows: P is a function of the proportional coefficient with respect to curvature, I is a function of the integral coefficient with respect to curvature, and D is a function of the differential coefficient with respect to curvature.

[0013] In the above calculation, the laying heads on both sides are controlled separately, but through calculation, their real-time position deviation can be obtained, so that they can quickly converge on the theoretical trajectory. At the same time, considering the applicability to equipment with different curvature components, dynamic parameters are introduced, so that the equipment has better adaptability to curved surface parts with more complex shapes, and the parameters have a wider scope of application; finally, the present invention predicts the next deviation based on historical deviations, with faster system response, more timely distance adjustment, and higher precision, which is the integration of physical prior knowledge and machine learning algorithms.

[0014] For the method of calibrating the proportional, integral, and differential parameters in real time through curvature, the function can adopt the following formula:

[0015]

[0016] The meanings of the parameters in the formula are as follows: P is a function of the proportional coefficient with respect to curvature, I is a function of the integral coefficient with respect to curvature, and D is a function of the differential coefficient with respect to curvature. p is the initial proportional coefficient, i is the initial integral coefficient, and d is the initial differential coefficient.

[0017] In the above calculation, when the curvature is large, the motion control of the system needs to respond faster to adapt to the adjustment of the center plane. Reduce the damping ratio of the adjustment at this time.

[0018] The distance measurement of the present invention can adopt various schemes, including a combination of one or two of acoustic ranging, optoelectronic ranging, lidar and vision fusion ranging.

[0019] The beneficial effects of the present invention are:

[0020] Through the method of the present invention, during the mirror additive manufacturing of composite materials, the trajectories of the deposition heads on both sides can be compensated. Realize real-time correction and high-precision control on both sides. Thereby improving the quality control level during the manufacturing process. At the same time, this method greatly improves the adaptability of the equipment to deposition structures with different curvatures, and has high practical value and broad application prospects. Description of the Drawings

[0021] Figure 1 It is a schematic diagram for building a correction model in an embodiment of the present invention. Detailed Embodiments

[0022] The present invention will be further described below with reference to the drawings and embodiments.

[0023] A trajectory compensation method for mirror additive manufacturing of composite components can implement an adjusted mirror trajectory under the condition of no die support to ensure the position accuracy of the components during the additive manufacturing process. The method specifically includes the following steps:

[0024] Step 1: Sensor arrangement.

[0025] Adopt a spatial mirror machine tool structure, aiming to optimize the stability and accuracy of the deposition process through symmetric design. In this structure, the two deposition heads are mirror-symmetric to each other, located on both sides of the machine tool respectively, and symmetric operation is achieved through the mirror pressure and mirror temperature control systems. The distance sensors also maintain a mirror state while keeping close to the deposition heads.

[0026] Step 2: Collect and solve data.

[0027] In this process, high-precision distance sensors are used to monitor the deposition heads on both sides in real time, collect and solve the deviation amounts of the deposition heads on both sides. These data are fed back to the central control system in real time through the sensor system for subsequent processing. By solving the collected data, any possible position deviations of the deposition heads on both sides can be accurately predicted. At the same time, these sensors can also provide the curvature information of the current position, that is, the bending degree of the current deposition path. These curvature data are crucial for subsequent deposition control because they directly affect the fluidity of the deposited material, the stacking order, and the final formed geometry. By continuously analyzing and recording the deviation amounts and curvature information, the system can identify potential problems in advance and make advance calibration for the next operation to ensure the smooth progress of the deposition process.

[0028] Step 3: Compensation prediction.

[0029] Based on the curvature information collected in Step 2, the system will calculate the value of the calibration parameter through an algorithm. The algorithm is: calculate the deviation δ between the actual position and the current trajectory point of the theoretical position of the component i , and at the same time record the historical deviation δ of the historical trajectory point i-1 , δ i-2 ……. According to the above deviation values, considering the curvature λ of the trajectory point where it is located i calculate the compensation amount C of the next trajectory point in real time i+1 , and modify the G code of the running trajectory of the double deposition heads in real time with this compensation amount. The real-time calculation method adopts the proportional / integral / differential method of parameter real-time calibration; the parameters are calibrated in real time according to the curvature λ of the current trajectory point i so that the deposited structure has a small deviation from the theoretical shape. The formula of the calculation method is as follows:

[0030] C(λ i, i + 1) = P(λ i ) * δ i + I(λ i ) * δ intergral + D(λ i ) * Δδ

[0031] where

[0032] The meanings of the parameters in the formula are as follows: P is a function of the proportional coefficient with respect to curvature, I is a function of the integral coefficient with respect to curvature, and D is a function of the differential coefficient with respect to curvature. For the method of calibrating the proportional, integral, and differential parameters in real time through curvature, the function can adopt the following formula:

[0033]

[0034]

[0035] The meanings of the parameters in the formula are as follows: P is a function of the proportional coefficient with respect to curvature, I is a function of the integral coefficient with respect to curvature, and D is a function of the differential coefficient with respect to curvature. p is the initial proportional coefficient, i is the initial integral coefficient, and d is the initial differential coefficient. This process includes combining historical data with real-time data to predict the deviation of the next deposition position. The prediction result can provide an accurate basis for parameter adjustment of the control system to ensure that the deposition head can accurately reach the target position in subsequent operations. Specifically, the system will analyze historical data and combine the current curvature information to set the compensation amount for the next deposition position. These compensation amounts will be dynamically adjusted according to the previous deviation trend to ensure that each layer of deposition can be accurately matched to the previously laid material, avoiding forming defects caused by position deviation. During the compensation prediction process, the possible impacts of external environmental factors such as temperature and humidity on the deposition process will also be considered to further improve the accuracy of compensation. Finally, these compensation parameters will be fed back to the machine tool control system to ensure that the next deposition operation can be carried out in the best state, reducing errors and improving the overall processing accuracy.

[0036] Through continuous cycling and optimization of these steps, the entire deposition process can continue on the basis of high precision and high efficiency, and finally obtain an ideal forming result.

[0037] The parts not involved in the present invention are the same as the prior art and are implemented using the prior art.

Claims

1. A trajectory compensation method for mirror-image additive manufacturing of composite material components, characterized in that: The two material deposition heads are symmetrically distributed along the center plane of the component, move synchronously, and synchronously stack materials on both sides of the center plane; Distance sensors are respectively arranged on the two deposition heads to measure the actual position of the deposited components along the normal direction of the center plane; Calculate the deviation δ between the actual position and the current trajectory point of the component theoretical position i , and record the historical deviation δ of the historical trajectory points i-1 , δ i-2 ......, according to the above deviation value, consider the curvature λ of the trajectory point i Calculate the compensation amount C of the next trajectory point in real time i+1 The G code of the running trajectory of the dual deposition head is modified in real time with the compensation amount.

2. The method according to claim 1, characterized in that The real-time calculation method adopts a proportional / integral / differential method of real-time parameter calibration; The parameter is based on the curvature λ of the current trajectory point i Real-time calibration is performed to minimize the deviation between the deposited structure and the theoretical shape. The calculation method is as follows: C(λ i ,i+1)=P(λ i )*d i +I(λ i )*d intergral +D(λ i )*Dd among them Δδ=δ i -d i-1 P(λ), I(λ) are positively correlated with λ, and D(λ) is negatively correlated with λ.

3. The method according to claim 1, characterized in that The distance measurement method is one or a combination of sonic ranging, photoelectric ranging, laser radar and visual fusion ranging.

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