CN106844815B - Laser heating programming and optimizing method - Google Patents
Laser heating programming and optimizing method Download PDFInfo
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- CN106844815B CN106844815B CN201610942026.7A CN201610942026A CN106844815B CN 106844815 B CN106844815 B CN 106844815B CN 201610942026 A CN201610942026 A CN 201610942026A CN 106844815 B CN106844815 B CN 106844815B
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Abstract
The invention discloses a laser heating programming method, which grasps the deformation condition of a blank in hot spinning forming, easily generates defects and distribution parts thereof in a numerical simulation mode; a heating strategy is formulated according to the above, and laser parameters corresponding to the heating strategy are selected, wherein the laser parameters comprise the position relation between a light spot and a contact area on the blank, the laser power, the size of the laser light spot and the like; mapping the track of the rotary wheel into a discrete track of the laser spot by means of a numerical simulation result according to the position relation between the spot and a contact area on the blank; and converting the discrete track of the laser spot into a control track of the laser head according to the position relation between the laser spot and the laser head, and converting the control track of the laser spot into a control program of the laser head by means of CAM software. The method for programming and optimizing the laser heating program lays a foundation for realizing laser heating spinning forming, provides a good method for accurately controlling the laser heating process, and reduces the dependence of the laser heating program on experience.
Description
Technical Field
The invention relates to the technical field of plastic forming, in particular to a programming and optimizing method based on a laser heating program.
Background
The spinning technology is used as an advanced near-net forming process and is widely applied to the processing of hollow revolving body parts. With the gradual maturity of the optical fiber laser technology, it becomes possible to apply high-energy-density laser to replace the conventional energy source to heat the spinning blank in an online manner. Laser heating involves a number of parameters, including not only laser parameters, but also spinning process parameters. The loading trajectory with the laser has the greatest influence on the shaping among the parameters. This is because the loading track of the laser on the spinning wheel blank determines whether the laser heating area can cover the local deformation area on the blank, i.e. whether the temperature of the material in the deformation area can reach the requirement of plastic deformation.
For conventional spin forming, the spinning wheel loading trajectory is generally generated in two ways: one is to record and return the experienced manual operation process, and the other is to adjust the track of the rotary wheel according to the technological parameters matched with the shape of the mould and then convert the track into a CNC program, which is proposed by the patent No. CN 102650863A. The above method is not suitable for laser spot loading since the loading of the laser spot is not only related to the spinning wheel trajectory but also to the deformation process of the spun blank. Based on the laser heating spinning process, in order to ensure the heating effect, laser spots need to be loaded on the spinning blank in front of the feeding direction of a contact area on the spinning blank, the area is a transition curved surface between an effective forming area and a free deformation area, the spatial position of the transition curved surface is related to the loading position of a spinning wheel, forming process parameters and material characteristics, and the spatial position of the transition curved surface can only be predicted by experience at present along with the continuous change of the loading of the spinning wheel.
How to generate the laser heating track so as to meet the heating requirement of forming is the basis for realizing laser heating spinning forming, and how to convert the laser loading track into a control program to realize automatic production is the problem which needs to be solved in the application process of the laser heating spinning technology.
Disclosure of Invention
Aiming at the existing problems, the invention provides a method for programming and optimizing a laser heating program, aiming at providing a reliable and feasible laser heating program programming method for spinning forming based on laser heating under the existing software and hardware conditions, and the method is used for realizing laser heating in the spinning process and further realizing the automation of production.
In order to achieve the above object, according to one aspect of the present invention, there is provided a laser heating programming method including the steps of:
a laser heating programming method, comprising the steps of:
1) Obtaining blank geometric and material characteristic parameters, spinning tool geometric parameters and forming process parameters including blank thickness t 0 Diameter D, material properties (Young's modulus, yield strength, coefficient of thermal expansion and thermal conductivity, etc.), spindle speed n, feed rate f, spinning wheel diameter D r Fillet radius ρ r And/or angle of attack of spinning wheel
2) Generating a spinning wheel loading track according to a spinning forming process;
3) Establishing an integral heating spinning numerical simulation model by using numerical simulation analysis software according to the process parameters and the spinning wheel loading track obtained in the steps 1) and 2), and calculating;
4) Determining the action position of a laser heating area and the distribution condition of the temperature in the area in the spinning forming process, namely a heating strategy, according to the numerical simulation analysis result;
5) Determining laser heating parameters corresponding to different time points according to the heating strategy formulated in the step 4), wherein the laser heating parameters comprise the relative position relationship between a light spot and a contact area of the upper spinning wheel of the blank, the laser power P and/or the laser spot size d, and the relative position relationship between the light spot and the contact area of the upper spinning wheel of the blank comprises the axial distance delta between the light spot and the contact area and the circumferential included angle alpha between the light spot and the contact area;
6) Carrying out post-processing on the numerical simulation result, searching units with different time points meeting the position requirements on the surface of the spinning blank in the deformation process according to the relative position requirements of the light spot and a contact area on the blank, and establishing the corresponding relation between the time point and the Y and Z coordinates of the light spot by recording the Y and Z coordinates of the units so as to form a series of discrete points of which the light spot loading positions change along with time;
7) Converting discrete points of a light spot track into a series of position coordinates of the laser head in the heating process according to the offset distances of the laser light spot and the laser head in the Y direction and the Z direction;
8) Converting point coordinates of a series of laser head positions into motion track control codes by using CAM software;
9) And combining the laser head control track control code with the corresponding laser power P to generate a control program of the laser head.
Preferably, the spinning roller loading track is determined by a generating line of a spinning core die under the conditions of single-pass common spinning and conical piece shearing spinning forming, and the spinning roller loading track is designed according to the generating line of a spinning process piece under the condition of multi-pass common spinning.
Preferably, the laser spot size d is used for characterizing the size of the laser irradiation area.
Preferably, the circumferential angle α between the light spot and the contact area on the blank must be such as to ensure that the laser energy output by the laser head is directly incident on the surface of the blank.
Preferably, the track formed on the blank by the laser spot and the loading track of the spinning wheel do not need to maintain a one-to-one mapping relationship.
In order to achieve the above object, according to another aspect of the present invention, there is provided a laser heating program optimization method including the steps of:
1) Taking laser heating parameters as test factors including laser power P, spot size d, axial distance delta between a spot and a contact area on a blank and/or a circumferential included angle alpha, and determining the level of the factors;
2) Carrying out test scheme design based on laser heating spinning by using a test design method;
3) Generating a laser heating program by using a laser heating programming method according to the test scheme;
4) Carrying out a process test based on laser heating spinning according to the test scheme;
5) Analyzing the test result, and determining laser parameters suitable for forming according to the evaluation indexes;
6) And generating an optimized laser heating program by using the optimized laser heating parameters and a laser heating programming method.
Preferably, the laser heating program optimization method may be applied to a plurality of evaluation indexes for optimizing laser parameters.
Preferably, the process test may be a real process or a numerical simulation.
The invention provides a programming and optimizing method based on a laser heating program, which has the beneficial effects that: the generated laser heating track can realize the accurate control of the temperature of the heating area, can meet the heating requirement of forming, and enables the high-efficiency, energy-saving and environment-friendly spinning processing based on laser heating to be possible; the laser loading track is converted into a control program, so that the automatic production based on laser heating spinning forming is realized, and the labor intensity is reduced.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating the position of the contact area between the light spot and the blank according to the embodiment of the present invention;
FIG. 3 is a laser spot and spinning wheel trajectory curve of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example (b): AZ31 magnesium alloy plate formed by spin-forming based on laser heating
1) Thickness t of blank 2 0 Is 2mm, the diameter D is 155mm, and the fillet radius rho is selected r Is 12mm and the diameter D of the rotary wheel r A 200mm circular spinning wheel 5 is subjected to single-pass deep-drawing spinning forming, and the outer diameter D of the core mould 1 m 100mm, the spindle speed n during molding was 450r/min, and the feed rate f was 0.15mm/s.
2) By adopting single-pass deep drawing forming, the track of the spinning wheel 5 is consistent with the generatrix of the core mould 1, and no additional design is needed.
3) When the temperature of the material reaches 200-300 ℃, the AZ31 magnesium alloy can be smoothly formed, so that a commercial software MSC.Marc is applied to establish a numerical simulation model for spin forming of the AZ31 magnesium alloy with the material temperature of 250 ℃ by adopting the parameters in the step 1) and the tracks in the step 2), and operation is carried out.
4) From the simulation results, the maximum reduction of wall thickness was measured at a distance of 8.3mm from the bottom of the spun part. Spinning belongs to a continuous local plastic forming technology, and not only the contact area of the spinning wheel 5 and the blank 2 generates plastic deformation in the forming process, but also the contact area D and the periphery thereof also deform; when the laser is used for local heating, when the maximum thinning part is positioned at the rear side of the contact region D, the laser heating region A not only needs to cover the contact region D, but also needs to cover the part with the maximum thinning rate at the rear side of the contact region D, so that the material at the part is prevented from cracking due to too low plasticity. Therefore, with the aim of preventing the wall thickness from being excessively reduced, leading to the appearance of cracks in the part, a heating strategy is developed: when the rotating wheel 5 is not contacted with the blank 2, preheating the undeformed blank by adopting laser to enable the blank 2 to have initial temperature; when the forming is started, the laser heating power P and the laser spot size D are properly increased, and the axial distance delta between the spot and the contact section on the blank 2 is reduced, so that the heating area A can cover the rear side of the contact area D to the maximum extent, and the material at the maximum thinning part in the forming process has enough plasticity.
5) Completing the setting of laser parameters according to the heating strategy formulated in the step 4): in the preheating stage, the laser power P is 1200W, the laser spot size d is 4mm, and the axial distance delta between the spot and the contact area is 0 (the rotary wheel does not contact the blank); in the heating stage, the range of laser heating parameters is given, the laser power P is 1200-1800W, the laser spot size d is 4-8mm, and the axial distance delta between the contact area of the laser spot and the blank is 2-6mm. In the forming process, the laser head 3 is clamped at the tail end of the six-degree-of-freedom robot 4, so that the robot 4 is prevented from interfering with spinning equipment, and meanwhile, in order to ensure the laser heating effect, a uniform circumferential included angle alpha between a light spot and a contact area on a blank is selected and used in the whole forming process, and the value of the included angle alpha is 90 degrees (as shown in figure 2).
6) And writing a post-processing program, and extracting unit coordinates from the numerical simulation result through an interface according to a given position relation (namely the axial distance delta between the light spot and the contact area and the circumferential angle alpha), so as to obtain a loading track of the light spot on the surface of the spinning blank in the deformation process.
7) And taking laser parameters selected in the heating stage as test factors, and determining the level of each factor, wherein the axial distance delta between a light spot and a contact area is respectively 2mm, 4mm and 6mm, the laser power P is respectively 1200W, 1500W and 1800W, and the light spot size d is respectively 4mm, 6mm and 8mm.
8) And designing a three-factor three-level orthogonal test for completing optimization of laser heating parameters.
9) And (4) respectively generating coordinate values of the discrete points of the laser spot loading track by using the post-processing program compiled in the step 6).
10 The coordinate values of the light spot track points generated in the step 9) are offset, the offset coordinates are related to the size of the laser light spot, for example, the offset coordinates corresponding to the size d of the light spot of 6mm are (+ 43.3, -25), the offset coordinates are converted into the coordinate values required by the six-degree-of-freedom robot 4 to control, the processing track is generated, and a control program is generated in a WorkVisual.
11 According to the test protocol, a process test based on laser heating spinning is carried out.
12 The test results showed that some of the spun pieces were broken and were not smoothly formed, and it was found that the heating strategy used in the test was appropriate and it was necessary to use the maximum reduction ratio of the spun pieces as an optimum evaluation index. The detection result shows that: the maximum thinning rate of the spinning piece can be controlled within 10% by the aid of the two groups of laser parameters. These two sets of parameters are: the laser power P is 1500W, the laser spot size d is 4mm, and the axial distance delta between the spot and the contact area is 4mm; the laser power P is 1800W, the laser spot size d is 4mm, and the axial distance delta between the spot and the contact area is 6mm. Temperature measurements taken near the contact area during formation showed that the error from the temperature used for numerical simulation was 12.3% for a laser power P of 1500W, which is closer to the simulated temperature, so the first set of data was chosen as the optimum.
13 Using optimized laser heating parameters: the laser power P is 1500W, the laser spot size d is 4mm, the axial distance delta between the spot and the contact area is 4mm, and the steps 6), 9) and 10) are repeated to generate an optimized laser heating program.
In conclusion, the deformation condition of the blank in the hot-spinning forming process, the defects and the distribution parts of the defects are mastered in a numerical simulation mode; a heating strategy is formulated according to the above, and laser parameters corresponding to the heating strategy are selected, wherein the laser parameters comprise the position relation between a light spot and a contact area on a blank, the laser power, the size of the laser light spot and the like; secondly, mapping the track of the rotary wheel into a discrete track of the laser spot by means of a numerical simulation result according to the position relation between the spot and a contact area on the blank; and finally, converting the laser spot into a control track of the laser head according to the position relation between the laser spot and the laser head, and converting the control track into a control program of the laser head by means of CAM software. Meanwhile, the invention also provides a method for optimizing laser heating parameters by adopting a test design method so as to realize optimization of a laser heating program. The method for programming and optimizing the laser heating program lays a foundation for realizing laser heating spinning forming, provides a good method for accurately controlling the laser heating process, and reduces the dependence of the laser heating program on experience.
It should be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (8)
1. A laser heating programming method, comprising the steps of:
1) Obtaining blank geometric and material characteristic parameters, spinning tool geometric parameters and forming process parameters including blank thickness t 0 Diameter D, material properties, spindle speed n, feed rate f, spinning wheel diameter D r Fillet radius rho r And/or angle of attack of spinning wheel
2) Generating a spinning wheel loading track according to a spinning forming process;
3) Establishing an integral heating spinning numerical simulation model by using numerical simulation analysis software according to the process parameters and the spinning wheel loading track obtained in the steps 1) and 2), and calculating;
4) Determining the action position of a laser heating area and the distribution condition of the temperature in the area in the spinning forming process, namely a heating strategy, according to the numerical simulation analysis result;
5) Determining laser heating parameters corresponding to different time points according to the heating strategy formulated in the step 4), wherein the laser heating parameters comprise the relative position relationship between a light spot and a contact area of the upper spinning wheel of the blank, the laser power P and/or the laser spot size d, and the relative position relationship between the light spot and the contact area of the upper spinning wheel of the blank comprises the axial distance delta between the light spot and the contact area and the circumferential included angle alpha between the light spot and the contact area;
6) Carrying out post-processing on the numerical simulation result, searching units with different time points meeting the position requirements on the surface of the spinning blank in the deformation process according to the relative position requirements of the light spot and a contact area on the blank, and establishing the corresponding relation between the time point and the Y and Z coordinates of the light spot by recording the Y and Z coordinates of the units so as to form a series of discrete points of which the light spot loading positions change along with time;
7) Converting discrete points of a light spot track into a series of position coordinates of the laser head in the heating process according to the offset distance between the laser light spot and the laser head in the Y direction and the Z direction;
8) Converting point coordinates of a series of laser head positions into motion track control codes by using CAM software; 9) And combining the laser head control track control code with the corresponding laser power P to generate a control program of the laser head.
2. The laser heating programming method according to claim 1, wherein in the case of single-pass normal spinning and the shearing spinning forming of the conical member, the loading trajectory of the spinning roller is determined by a generatrix of the spinning core mold, and in the case of multi-pass normal spinning, the loading trajectory of the spinning roller is designed according to the generatrix of the spinning process member.
3. The laser heating programming method according to claim 1, wherein the laser spot size d is used to characterize a size of a laser irradiation area.
4. The laser heating programming method of claim 1, wherein the angle α between the spot and the circumference of the contact area on the blank is selected to ensure that the laser can be directly irradiated on the surface of the blank in addition to the heating effect.
5. The laser heating programming method of claim 1, wherein the locus of the laser spot formed on the blank does not need to maintain a one-to-one mapping with the spinning wheel loading locus.
6. A method for optimizing a laser heating program, comprising the steps of:
1) Taking laser heating parameters as test factors including laser power P, spot size d, axial distance delta between a spot and a contact area on a blank and/or a circumferential included angle alpha, and determining the level of the factors;
2) Carrying out test scheme design based on laser heating spinning by using a test design method;
3) Generating a laser heating program by using a laser heating programming method according to the test scheme;
4) Carrying out a process test based on laser heating spinning according to the test scheme;
5) Analyzing the test result, and determining laser parameters suitable for forming according to the evaluation indexes;
6) And generating an optimized laser heating program by using the optimized laser heating parameters and a laser heating programming method.
7. The method of claim 6, wherein the optimization is performed to improve the molding quality, and the number of evaluation indexes is 1 or more, which is designed as needed.
8. The method of claim 6, wherein the process test is real machining or numerical simulation.
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DE4425033A1 (en) * | 1994-07-15 | 1996-01-18 | Fraunhofer Ges Forschung | Method and device for press forming workpieces |
CN102650863A (en) * | 2011-02-24 | 2012-08-29 | 鑫港企业有限公司 | Method for generating CNC (computerized numerical control) program code for spinning lathe by feeding CAD (computer-aided design) file |
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