CN100468244C - Composite forming method of press bending and point heat source - Google Patents

Abstract

The invention discloses a bending point heat source composite forming method as follows: 1) Firstly, the blank is simulated and processed through a computing platform, and the local area that is difficult to form is pre-judged; 2) The processing parameters of the point heat source are obtained according to step 1). ; 3) during mechanical processing, according to the parameters in step 2) the compound processing is carried out by the computer control system control point heat source; 4) while step 3) is processing, the sensor for measuring the blank state feeds back the stress to the control system , strain and other real-time monitoring data. In the process of traditional mechanical forming of large parts, the present invention adopts point heat source to carry out composite forming of bending point heat source, and can handle the hard-to-deform places in the process of mechanical forming well, so it overcomes the possible problems caused by mechanical forming. The disadvantage of forming parts is damaged or even destroyed.

Description

Composite forming method of press bending and point heat source

technical field

The invention relates to a bending forming method of sheet metal structural parts, especially difficult-to-form sheet metal structural parts with large size and complex structure shape.

Background technique

There are such types of sheet metal parts in engineering, such as aircraft skin and overall (integrated skin and support ribs) panel parts, rocket integral fuel tank parts, ship side and deck parts, and car coverings, etc. , It needs to be formed by bending or rolling. Roll bending is another form of bending, which means that the formed part can rotate with the support roll while being bent.

Press bending or roll bending is the main method of forming wall panels at present. The method uses a three-point bending method to form the wall plate, the wall plate is supported by two supporting points, and the loading device controls the pressure head to load on the predetermined position on the wall plate. The siding undergoes plastic deformation under load to obtain the desired geometry. Press bending forming can be one-time forming or multiple or incremental forming (forming the blank through multiple, step-by-step loading methods). Load size and loading location, as well as loading sequence are issues that need to be considered in forming.

For aircraft skin and panel parts, due to their large size and complex structural shape, this method has small deformation, high forming difficulty, and cannot form parts with large local deformation and high ribs. Its main manifestations are: large deformation resistance, large springback, prone to deformation damage (such as rib wrinkling and cracking, etc.), and poor forming accuracy. In order to meet its size and shape accuracy requirements, such parts often need to be formed by a small amount of deformation and multiple annealing methods, and then it is necessary to use "manual hammering", "pimp whipping" or "shot blasting" according to experience. fine-tuning. However, "manual hammering" and "pimp whipping" often rely on the experience of the processor, and it is not easy to realize manufacturing automation. In addition, "manual hammering" and "pimp whipping" are likely to leave damage on the surface of the workpiece and become a safety hazard. "Manual hammering" and "pimp whipping" are absolutely not allowed on large civil aircraft.

Contents of the invention

Aiming at the above-mentioned problems, the present invention provides a composite forming method of press bending and point heat source, which eliminates human influence and dependence on operator experience in the forming process, thereby realizing the automation and intelligence of the forming process.

In order to achieve the above object, the present invention provides a composite forming method of bending point heat source, comprising the following steps: 1) establishing the relevant performance parameters of the mechanical properties and thermophysical properties of the formed material, the structure, size and shape database of the formed part, and the material in the The response law under the action of multi-physics fields, establish a computing platform and an expert system, and use the computing platform to virtual process the blank, pre-judge the position that is difficult to form, require point heat source processing, and point heat source processing parameters. The simulation of the process obtains the technical parameters of the point heat source, the area and trajectory that need to be processed by the point heat source, and the constraints of the blank during processing;

2) each condition in step 1) is converted into each process parameter of point heat source processing by computer control system;

3) During mechanical processing, according to the process parameters in step 2), the point heat source auxiliary processing is controlled by a computer control system to achieve the expected forming effect;

4) While processing in step 3), the sensor used to measure the state of the blank feeds back the real-time monitoring data during the deformation process to the control system, and the computer control system corrects the process parameters in time according to these data, thus forming a closed-loop control during the entire processing process .

Further, the process parameters of the point heat source processing in the step 2) include energy, time, space coordinates, speed, and trajectory.

The present invention uses a point heat source for processing in the process of traditional mechanical forming of large parts, and can handle the hard-to-deform places in the process of mechanical forming, so it overcomes the damage or even destruction of the formed parts that may be caused by mechanical forming The disadvantages mainly include the following two aspects: First, the interaction between the point heat source and the material reduces the deformation resistance of the local area of the formed part: due to the energy injection generated by the point heat source, the structure and organization of the material at high temperature change , the plastic flow ability of the material is enhanced, and the deformation resistance during the forming process is reduced, which is helpful for forming; second, the temperature gradient generated by the point heat source is used for local forming, and the material has different responses to different temperatures: generally speaking, forming During the process, the part of the material at high temperature deforms greatly, on the contrary, the part at low temperature deforms relatively small, and this difference is enough to cause the blank to bend, changing the action strength, action time and boundary conditions can control its bending direction and The degree of bending, and the blank has good shapeability after forming.

Description of drawings

Fig. 1 is a comparison effect diagram of the present invention for bending a titanium alloy plate.

Detailed ways

The present invention can be divided into two working schemes of forming and fine adjustment. The so-called forming scheme is to input a point heat source energy to the difficult-to-deform part of the part while bending (rolling) forming. When this method is used for forming, the thermal energy converted from the energy of the point heat source can not only reduce the deformation resistance of the material in the action area of the point heat source, but also assist the forming of the part through the non-uniform thermal stress field established in the thickness direction of the part, so it can significantly improve the above-mentioned The amount of bending forming of formed parts as well as forming efficiency and forming accuracy. Hard-to-deform parts can be obtained by computer simulation of formed parts. The so-called fine-tuning scheme is to input point heat source energy into the corresponding elastic internal energy concentration area for parts that are formed by bending or the above-mentioned bending point heat source composite method but whose forming accuracy has not reached the design requirements. Its fine-tuning function is achieved by using a point heat source to selectively heat the material in the action area, so that the elastic internal energy of the area is released in the form of plastic deformation due to the reduction of the deformation resistance of the material. Since the position of the elastic internal energy concentration area and the size, injection method and path of the point heat source energy required for fine adjustment can be determined by computer simulation and accurately realized by a manipulator, the adjustment accuracy of this method is significantly higher than that of the above-mentioned "manual hammering". , "pimp whipping" and "shot blasting" and other methods.

Large-scale structural parts will have places that are difficult to deform during the mechanical forming process, that is, if the material has a strong ability to resist deformation, and the local deformation requirements during forming are relatively large, then mechanical forming shows limitations in these places. If the load is continuously increased to meet the forming requirements, this may lead to damage or even destruction of the formed part. The compound forming of the bending point heat source in the present invention can realize the flexibility, automation, digitalization and intelligence of the forming process conveniently by utilizing the monochromaticity and stability of the point heat source, high energy density, no pollution, and high control precision. and other characteristics, using computer simulation and sensor feedback signals to monitor, track and composite form these difficult-to-form local areas. In this process, the point heat source plays a role in two aspects. First, the interaction between the point heat source and the material reduces the deformation resistance of the local area of the formed part: due to the energy injection generated by the point heat source, the deformation of the material at high temperature The structure and organization change, the plastic flow ability of the material is enhanced, and the deformation resistance during the forming process is reduced, which is helpful for forming. Second, the temperature gradient generated by the point heat source is used for local forming: materials have different responses to different temperatures. Generally speaking, during the forming process, the part of the material at high temperature deforms greatly, and on the contrary, the part at low temperature deforms Relatively small, and this difference is enough to cause the blank to bend, change the action strength, and the action time can control the bending direction and degree of bending, and the blank has better shape setting after forming.

The specific operation is as follows:

1) Establish relevant performance parameters such as mechanical properties and thermophysical properties of formed materials, as well as the structure, size and shape database of formed parts, as well as the response law of materials under the action of multi-physics fields (mechanical loads, thermal loads), and establish a computing platform and expert system. And through the virtual processing of the blank through this computing platform, pre-judgment is made on the positions that are difficult to form and require point heat source processing and the processing parameters of point heat source, that is, through the simulation of the processing process, the technical parameters of point heat source and the points that require point heat source processing are obtained. The area and trajectory of the blank, as well as the constraints of the blank during processing;

2) converting each condition in step 1) into process parameters such as energy, time, spatial coordinates, speed, and trajectory of point heat source processing by a computer control system;

3) During mechanical processing, according to the parameters in step 2), the point heat source auxiliary processing is controlled by the computer control system to achieve the desired forming effect;

4) While processing in step 3), the sensor used to measure the state of the blank feeds back real-time monitoring data such as stress and strain to the control system, and the computer control system corrects the process parameters in time according to these data, thereby forming a closed-loop control in the entire processing process .

5) For the fine-tuning work plan, first detect the difference between the shape and size of the parts to be fine-tuned and the design parts, and then determine the fine-tuning plan according to 1), 2), 3), and 4), including determining the point heat source energy that needs to be injected Parameters such as magnitude, location, method and trajectory. Fine-tuning can be repeated until the formed part meets the design requirements.

The heat effect of the point heat source can significantly improve the formability and shapeability of the material. When bending 4mm, the forming amount of the titanium alloy can be changed from 0 (no point heat source effect) to 2.4mm and 3.1mm. For other materials such as aluminum alloy, there is a maximum improvement of 43%, and for ST14 steel plates, there is a maximum improvement of 56%. As shown in Figure 1, 1 is the final form of the titanium alloy plate that has not been processed by a point heat source after bending 24mm, and it can be seen that the springback is relatively large, and 2 is that the titanium alloy plate is bent 24mm under the effect of the method of the present invention After the final state, it can be seen that the amount of rebound is significantly reduced. The length of the titanium alloy plate in the figure is 150 mm.

The above-mentioned point heat source can be laser, plasma beam, flame, induction heating or electron beam, etc.

Claims (2)

1, a kind of bending point heat source compound forming method is characterized in that, comprises the steps: 1) Establish the relevant performance parameters of the mechanical properties and thermophysical properties of the formed material, the structure, size and shape database of the formed parts, and the response law of the material under the action of multiple physical fields, establish a computing platform and an expert system, and through the computing platform For the virtual processing of the blank, pre-judgment is made on the difficult-to-form, locations that require point heat source processing, and point heat source processing parameters. Through the simulation of the processing process, the technical parameters of the point heat source, the area and trajectory that require point heat source processing, and Constraints of the blank during processing; 2) each condition in step 1) is converted into each process parameter of point heat source processing by computer control system; 3) During mechanical processing, according to the process parameters in step 2), the point heat source auxiliary processing is controlled by a computer control system to achieve the expected forming effect; 4) While processing in step 3), the sensor used to measure the state of the blank feeds back the real-time monitoring data during the deformation process to the control system, and the computer control system corrects the process parameters in time according to these data, thus forming a closed-loop control during the entire processing process . 2. The bending point heat source composite forming method according to claim 1, characterized in that the process parameters of the point heat source processing in step 2) include energy, time, space coordinates, speed, and trajectory.

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