Method for controlling the bending deformation of a cavity aluminium profile

Abstract

The method for controlling the bending arc deformation of the cavity aluminum profile roll bending forming comprises the following steps: manufacturing a profiled steel strip of straight line segments and a plurality of profiled sheets according to the shape of the inner cavity of the profile to be roll-bent, the length of the profile to be bent, and the bending arc; before roll bending, loading the profile into a roll bending machine, determining the starting position of roll bending, and loading the profiled steel strip at one end, the profiled sheet, and the profiled steel strip at the other end into the inner cavity of the profile in sequence; loading the filled profile into the roll bending machine for roll bending; taking out the profiled steel strips and the profiled sheet at both ends of the completed roll-bent profile in sequence, loading the profiled steel strip and the profiled sheet into the inner cavity of another profile to be roll-bent, and repeating the roll bending work. The method can effectively solve the problems of low bending part contour forming precision and large cross section deformation of the bending section during the roll bending of large cross section profiles, and the inner side and the outer side of the bending section are smooth, and the transition between the straight line section and the bending section is smooth.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy processing technology, and more particularly to a method for controlling the bending deformation of cavity aluminum profiles during roll forming. Background Technology

[0002] Aluminum profiles, due to their superior mechanical properties, excellent formability, light weight, and excellent corrosion resistance, can be used in various aspects of industry and are widely used in transportation, including automobile manufacturing, rail transportation, equipment and machinery manufacturing, and durable consumer goods.

[0003] In the automotive and rail transportation manufacturing industries, originally straight aluminum profiles need to be bent into various arcs or angles to meet the streamlined curves or aesthetic requirements of vehicles. There are several forming methods for bending aluminum profiles, including pressure bending, folding, and roll bending. Due to the long length and large cross-section of automotive aluminum profiles, roll bending is often used. Roll bending of aluminum profiles mainly uses a roll bending machine. The motor of the roll bending machine drives several overlapping rollers to rotate. The aluminum profile gradually passes through the middle of the rollers from one end, being rolled and bent by the overlapping rollers, gradually shaping the aluminum profile into a certain arc from beginning to end. By controlling the position of the rollers, the arc of the aluminum profile can be adjusted, ultimately achieving the desired curved aluminum profile product.

[0004] During roll forming, if the bending radius is small, the cavity at the bending point is prone to wrinkling and deformation, severely affecting the profile's dimensional appearance and the integrity of the cavity. To solve this problem, engineers devised a method of filling the profile cavity with a filler to support the cavity cross-section and prevent deformation. For example:

[0005] 1. Profile Roll Bending Processing Method; Application No.: CN201310669273.0; Applicant: Longkou Conglin Zhongde Vehicle Body System Engineering Co., Ltd.; Abstract: A profile roll bending processing method, the forming device required by the method includes a bending machine and a stopper block; the forming method firstly, according to the inner cavity shape of the workpiece to be processed, a stopper block matching the inner cavity shape is made and fixed to one end of a screw, the other end of which is fixed to the right arm of the bending machine; secondly, the stopper block is inserted into the inner cavity of the workpiece, placed at the starting point of the arc of the workpiece, and the workpiece is fixed under the top block; finally, the rotating shaft is rotated counterclockwise, causing the left arm of the bending machine to rotate counterclockwise, driving the workpiece to roll and deform on the rolling die, thereby bending the workpiece to be processed into shape, and the stopper block is always in the bending position. Compared with the prior art, it has the following characteristics: it can process workpieces with different cavities, can make the workpiece subjected to uniform force, and the processed workpiece has high precision in terms of cross-sectional cut, workpiece concavity, twisting, and wrinkling.

[0006] 2. Improvement of the rolling process for profiles used in bus frames, "Bus Technology and Research", Issue 2, 2005, Li Zhaojie, Gao Hualing, Wei Ling, Zhengzhou Yutong Bus Co., Ltd.; referring to the "multi-section movable core structure".

[0007] While the above-mentioned published documents disclose some methods for filling the cavity with filler, the results are limited. The final profile bending surface still shows signs of deformation, and the transition in the bending area is not smooth and natural. Moreover, the movable insert structure in document 2 is complex in construction, has high manufacturing costs, and after deformation within the narrow aluminum profile cavity, the entire component is extremely difficult to remove, which greatly affects the continuity of the roll bending. Summary of the Invention

[0008] The purpose of this invention is to provide a method for controlling the bending deformation of aluminum profiles with cavities during roll bending. This method is applicable to rail transit profiles with small bending radii and short arc lengths, and is suitable for bending profiles with short arc lengths < 500 mm and bending radii R (100 < R < 1000 mm). It can effectively solve the problems of low profile forming accuracy and large cross-sectional deformation of the bending section during the roll bending process of large cross-section profiles. Both the inner and outer surfaces of the bending section are smooth, and the transition between the straight section and the bending section is natural and smooth.

[0009] The technical solution of this invention is implemented as follows:

[0010] 1. A method for controlling the bending deformation of a cavity aluminum profile during roll bending, comprising the following steps:

[0011] (1) Based on the inner cavity shape of the profile to be bent, the length of the profile to be bent, and the curvature of the bend, manufacture straight section imitation steel strips and several imitation thin sheets.

[0012] (2) Before rolling, load the profile into the rolling machine, determine the starting position of rolling, and load the profile with a steel strip, a thin sheet and a steel strip at one end and the other end in sequence into the inner cavity of the profile.

[0013] (3) The filled profile is put into the roll bending machine for roll bending;

[0014] (4) Take out the profiles with the following characteristics in sequence: the steel strips and thin sheets at both ends of the profiles that have been rolled. Insert the steel strips and thin sheets into the inner cavity of another profile to be rolled and repeat the rolling process.

[0015] The thickness d of the profile sheet ranges from 5mm to 35mm, and the calculation formula is d=R / 50+2t+C, where R is the bending radius of the profile (mm), t is the radial wall thickness of the profile in the bending arc (mm), and C is an empirical correction value, ranging from 0 to 3. The correction value is related to the shape of the profile's inner cavity cross-section, the bending arc length, and whether the value is rounded up or down. When the inner cavity cross-section shape is more complex, the correction value decreases, and vice versa for simpler shapes. The longer the bending arc length, the higher the correction value, and vice versa. When the result value has multiple decimal places, the decimal places are padded to obtain an integer.

[0016] The curved surface and the curved side of the profile correspond to the two sides of the contour sheet, and the two sides of the contour sheet are arc surfaces.

[0017] The arc surface on the side of the contoured sheet has a radius of radius R = 1 / 2 of the sheet thickness in mm.

[0018] The gaps between the conforming steel strips and conforming sheets and the inner cavity of the profile section are as follows: the gap with the top surface of the inner cavity is 1-2mm, and the total fitting gap with both sides of the inner cavity is 0.1-0.2mm.

[0019] The stacked length of the contour sheet is located in the middle of the profile bending section, and its length is 20-30mm shorter than the length of the profile bending section.

[0020] The end face of the profiled steel strip that is in contact with the profiled sheet is a bevel, and the direction of the bevel is consistent with the direction in which the profile is to be bent; the corners of the end face are all rounded with R5-R10.

[0021] The specific calculation value of the inclination angle of the end face where the conforming steel strip and the conforming sheet are in contact is β=arctan [(παA) / (760B)]+t, where α is the central angle of the bending arc length in degrees, A is the radial cavity height of the bending arc + the profile wall thickness in mm, B is the radial cavity height of the bending arc in mm, and t is an empirical value, determined according to the springback of the profile after bending, and is taken as 5-10°. When the profile material springs back severely, the empirical value t is taken as the upper limit, and vice versa when the profile material springs back lightly.

[0022] When the profile has multiple cavities, the cavities are filled with corresponding shaped steel strips and thin sheets, and the roll forming can be completed by following the same steps.

[0023] It can also be applied to bending and pressing of aluminum profiles with cavities.

[0024] Advantages of this invention:

[0025] 1. This invention enables the roll bending of large aluminum profiles with small radii; the resulting profile has a continuous and natural bending arc, a smooth bending surface, and is convenient and quick for operators to operate. There are no scratches on the inner cavity surface of the profile, thus maximizing the protection of the smoothness of the inner cavity surface.

[0026] 2. The forming control method of the present invention can also be extended to bending and pressing of cavity profiles, and the specific preliminary operation steps are the same as those for roll bending.

[0027] 3. After the conforming sheet of the present invention is rolled, the sheet can be laid down and removed one by one, so it is not easy for the sheet to get stuck at the bend and cannot be removed, thus improving the continuity of rolling and increasing production efficiency. Attached image description:

[0028] Figure 1 This is a schematic diagram of the positional relationship of each component in Example 1 (in an unbent state);

[0029] Figure 2 This is a schematic diagram of the positional relationship of each component in Example 1 (bending completed state);

[0030] Figure 3 This is the profile cross-sectional dimension drawing for Example 1;

[0031] Figure 4 yes Figure 1 Schematic diagram of the AA section structure;

[0032] Figure 5 yes Figure 4 Schematic diagram of the BB section structure;

[0033] Figure 6 This is the profile cross-sectional dimension drawing for Example 2;

[0034] The labels in the diagram are: 1. Aluminum profile; 2. Contour steel strip; 3. Contour sheet. Detailed Implementation

[0035] Example 1

[0036] Taking the 6005A-T5 rail transit door column aluminum profile as an example, the requirements are that the gap between it and the conformal inspection tool is <1mm, the transition at the bend is smooth, there are no visible wrinkles, and the cross-sectional deformation is <0.5mm.

[0037] (1) Determine the thickness of the profile sheet, where the bending radius R of the profile is 400mm, the profile wall thickness t is 3mm, and the empirical correction value C is 1;

[0038] Calculate d = R / 50 + 2t + C = 400 / 50 + 6 + 1 = 15mm.

[0039] (2) Determine the inclination angle of the end face of the profiled steel strip, where the central angle α corresponding to the bending arc length is 65°, the cavity height of the bending arc radially + the profile wall thickness A is 138mm, B is the cavity height of the bending arc radially 132mm, and the empirical value t is 7°.

[0040] β=arctan [(παA) / (760°B)]+t= arctan [(3.14*65°*138) / (360°*132)]+7°=arctan 0.5942+7°=37.7°

[0041] (3) Determine the radius of the arc surface of the contour sheet. The value R is calculated above: 15mm; therefore, R = 1 / 2d = 7.5mm

[0042] After production, the bending effect is as follows, as shown in the comparison data table:

[0043]

[0044] As can be seen from the above, before implementing the method of the present invention, it is not possible to obtain a fully qualified roll bending profile, mainly due to the failure caused by the deformation of the inner cavity of the profile.

[0045] Example 2

[0046] Taking 6082-T6 square aluminum profile as an example, the required gap between the profile and the conformal inspection tool is <2mm, the transition at the bend is smooth, there are no visible wrinkles, and the cross-sectional deformation is <1mm.

[0047] (1) Determine the thickness of the profile sheet, where the bending radius R of the profile is 600mm, the profile wall thickness t is 5mm, and the empirical correction value C is 1;

[0048] Calculate d = R / 50 + 2t + C = 600 / 50 + 10 + 1 = 23 mm.

[0049] (2) Determine the inclination angle of the end face of the profiled steel strip, where the central angle α corresponding to the bending arc length is 30°, the cavity height of the bending arc radially + the profile wall thickness A is 80mm, B is the cavity height of the bending arc radially 70mm, and the empirical value t is 10°.

[0050] β=arctan [(παA) / (760°B)]+t= arctan [(3.14*30°*80) / (360°*70)]+10°=arctan0.2990+10°=26.6°

[0051] (3) Determine the radius of the arc surface of the contour sheet. The value R is calculated above: 23mm; therefore, R = 1 / 2d = 11.5mm

[0052] After production, the bending effect is as follows, as shown in the comparison data table:

[0053]

Claims

1. A method for controlling the bending deformation of cavity aluminum profiles during roll forming, characterized in that: It includes the following steps: (1) Based on the inner cavity shape of the profile to be bent, the length of the profile to be bent, and the curvature of the bend, manufacture straight section imitation steel strips and several imitation thin sheets. (2) Before rolling, load the profile into the rolling machine, determine the starting position of rolling, and load the profile with a steel strip, a thin sheet and a steel strip at one end and the other end in sequence into the inner cavity of the profile. (3) The filled profile is put into the roll bending machine for roll bending; (4) Take out the two end strips and the thin sheet of the profile that has been rolled and bend in sequence. Insert the strips and the thin sheet into the inner cavity of another profile to be rolled and bend, and repeat the rolling and bending work. The thickness d of the profile sheet is in the range of 5mm-35mm, and the calculation formula is d=R / 50+2t+C, where R is the bending radius of the profile in mm, t is the radial thickness of the profile wall in mm, and C is an empirical correction value, which is 0-3. The curved surface and the curved side of the profile correspond to the two sides of the contour sheet, and the two sides of the contour sheet are arc surfaces; The arc radius of the side surface of the contoured sheet is calculated as R = 1 / 2 sheet thickness (mm). The end face where the conforming steel strip and the conforming sheet are in contact is an inclined surface, and the inclination direction is consistent with the direction in which the profile is to be bent. The specific calculation value of the inclination angle of the end face of the conforming steel strip and the conforming sheet is β=arctan [(παA) / (760B)]+t, where α is the central angle of the bending arc length in °, A is the radial cavity height of the bending arc + the profile wall thickness in mm, B is the radial cavity height of the bending arc in mm, and t is an empirical value, determined according to the springback of the profile after bending, and is taken as 5-10°.

2. The method for controlling the bending deformation of cavity aluminum profiles during roll forming according to claim 1, characterized in that: The gaps between the conforming steel strips and conforming sheets and the inner cavity of the profile section are as follows: the gap with the top surface of the inner cavity is 1-2mm, and the total fitting gap with both sides of the inner cavity is 0.1-0.2mm.

3. The method for controlling the bending deformation of cavity aluminum profiles during roll forming according to claim 1, characterized in that: The stacked length of the contour sheet is located in the middle of the profile bending section, and its length is 20-30mm shorter than the length of the profile bending section.

4. The method for controlling the bending deformation of cavity aluminum profiles during roll forming according to claim 1, characterized in that: When the profile has multiple cavities, the cavities are filled with corresponding shaped steel strips and thin sheets, and the roll forming can be completed by following the same steps.

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