Positive and negative rotation roll bending forming method for large-obtuse-angle unequal-thickness profile frame

Abstract

The invention provides a positive and negative rotation roll bending forming method for a large-obtuse-angle unequal-thickness profile frame. The positive and negative rotation roll bending forming method comprises the following steps that S1, the large-obtuse-angle unequal-thickness profile frame is clamped through a four-axis roll bending machine; s2, the angle and the flatness of the large-obtuse-angle unequal-thickness profile frame are corrected through a left-right feeding roll bending method and a positive-negative rotation roll bending method; and S3, a radian correction method is adopted for correcting the profile subjected to roll bending in the step S2. The method has the beneficial effects that the large-obtuse-angle unequal-thickness profile frame adopts a roll bending forming method, hard material roll bending forming can be directly carried out, the heat treatment procedure of stretch bending forming is omitted, the production cost is reduced, and the production period is shortened by 20%; a left-right feeding positive-negative rotating roll bending forming method is adopted for the large-obtuse-angle unequal-thickness profile frame, roll bending process parameters are reasonably designed, parts with qualified sizes can be formed in a roll bending mode, roll bending cannot be broken, and the product percent of pass is increased by 30%.

Description

Technical Field

[0001] The invention belongs to the field of carrier rocket profile frame forming, and in particular relates to a positive and negative rotation rolling forming method for a large obtuse-angle unequal-thickness profile frame. Background Art

[0002] There are many types of profile frames for launch vehicles, most of which are 90° right-angle profile frames, while acute-angle profile frames and obtuse-angle profile frames are less common. Most of them are small acute-angle and small obtuse-angle profile frames, and large obtuse-angle profiles are rarely used. A large obtuse-angle profile frame, made of 7A09 aluminum alloy, with an angle of 123°, a longer hypotenuse of 78mm, and unequal thickness of the hypotenuse. The thinnest part of the top is 2mm thick, the bottom is 42mm short, and the thickness is 6mm. It is bent into a semicircle with a radius of R1673mm, with the bottom facing outward and the hypotenuse facing the center of the circle. The bent parts are as follows: Figure 1 shown.

[0003] The large obtuse-angle profile frame is currently formed by a process of twice bending and quenching. Due to the large angle, large slope of the bevel, and unequal thickness of the bevel, the quenching deformation is large. The bevel formed by bending is unstable against the mold, and there is a gap between the mold and the bevel. The parts are easily broken by tensile stress during the bending process. The bottom edge is bent outward and the upper end is not fixed, so it is easy to warp. After the profile is bent from straight material, the gap between the bevel and the angle template is out of tolerance, and the gap between the bottom edge and the platform is out of tolerance. The bevel of the profile frame is connected to the skin assembly. The out-of-tolerance bevel angle directly affects the assembly accuracy. The part bending forming accuracy is poor, the manual trimming amount is large, and the scrap rate is high, resulting in poor part accuracy. The schematic diagram of the part out-of-tolerance is shown in the figure. Figure 2 As shown. After the profile is bent from straight material, there is a gap between the bevel and the angle template, the gap is 3mm (required ≤0.8mm), and there is a gap between the bottom and the platform, the gap is 3mm (required ≤1.5mm), which needs to be trimmed manually. It is difficult to trim the angle deviation manually. The bevel of the profile frame is connected to the skin assembly, and the bevel angle deviation directly affects the assembly accuracy.

[0004] If roll bending is used, due to the large obtuse-angled and unequally thick cross-section of the profile, the normal roll bending method will cause uneven force on the parts, which will twist the material to one side, causing the profile to twist and unable to be rolled.

[0005] In addition, there are three indicators for the profile frame surface accuracy, namely the contour radius value, the bottom flatness value, and the bevel angle value, and the three indicators are required to meet the requirements at the same time. For large obtuse angles and unequal thickness profile frames, whether they are formed by stretching or rolling, it is difficult to meet the requirements of radius, flatness, and angle at the same time. For stretching, the radius, flatness, and angle of the parts need to be manually trimmed. The three are related. After trimming the angle and flatness, and then trimming the arc, the angle and flatness will change; for rolling, if the flatness and angle values ​​meet the requirements after rolling, but the radius size is 1-3mm different, if it is rolled again, the angle and flatness values ​​will change, which may exceed the tolerance, resulting in low production efficiency due to repeated rolling.

[0006] In view of the structural characteristics of large obtuse-angle profile frames, the present invention proposes a two-way feeding positive and negative rotation rolling and bending forming method to correct the profile angle distortion and bottom edge warping, and combines the arc bending correction method to form high-precision parts. Summary of the invention

[0007] In view of this, the present invention aims to propose a positive and negative rotation rolling forming method for large obtuse angle and unequal thickness profile frames, so as to solve the problems that large obtuse angle and unequal thickness profile frames adopt existing stretch bending forming process, the bevel angle is out of tolerance, the bottom edge is warped, the forming precision is low, the qualified rate is low, the normal rolling forming process cannot be used for forming, and the three indicators of profile size radius, flatness and angle are difficult to meet the requirements at the same time. The profile frame adopts the two-way feeding positive and negative rotation rolling forming method and combines the curvature correction method to design the rolling forming process parameters that meet the profile frame, design the internal and external curvature correction tooling, and roll the profile frame parts with high dimensional accuracy.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A positive and negative rotation rolling forming method for a large obtuse angle and unequal thickness profile frame comprises the following steps:

[0010] S1. Use a four-axis rolling machine to clamp the large obtuse angle and unequal thickness profile frame;

[0011] S2. Use left and right feeding rolling bending method and positive and negative rotation rolling bending method to correct the angle and flatness of the large obtuse angle and unequal thickness profile frame;

[0012] S3, using the arc correction method to correct the profile after rolling in step S2.

[0013] Further, in step S1, the four-axis rolling bending machine includes a left roller, a rear roller, a right roller, a left pressure roller, a front roller and a right pressure roller. The left side of the large obtuse-angle unequal-thickness profile frame is respectively provided with a left roller and a left pressure roller, the right side of the large obtuse-angle unequal-thickness profile frame is respectively provided with a right roller and a right pressure roller, and the front and rear sides of the large obtuse-angle unequal-thickness profile frame are respectively provided with front rollers and rear rollers.

[0014] Further, in step S2, the left and right feeding rolling bending method includes:

[0015] The large obtuse angle and unequal thickness profile frame adopts the left and right alternating feeding scheme to correct the flatness of the bottom edge;

[0016] Positive and negative rotational rolling methods include:

[0017] The rolling process parameters are set, and the scheme of inconsistent rolling rotation angles of the left and right rollers in each pass is adopted, and one end rotates clockwise and the other end rotates counterclockwise to correct the angle deviation of the profile and obtain the profile after rolling.

[0018] Furthermore, in step S2, the rolling process parameters are set, specifically including:

[0019] Set the number of rolling bends, left and right roller movement values, left roller rotation value, right roller rotation value and feeding method.

[0020] Further, in step S2, the range value of the number of rolling bending times is 6-20 times.

[0021] Furthermore, in step S2, the number of rolling bending is 12 times.

[0022] Further, in step S2, the range of the movement value of the left and right rollers is 2 mm-9 mm.

[0023] Further, in step S2, the left roller rotation value ranges from 3 mm to 9.7 mm.

[0024] Further, in step S2, the range of the right roller rotation value is -3 mm to 10.3 mm.

[0025] Further, in step S3, the arc correction method includes:

[0026] The top bed is used to press and bend the contour of the rolled profile from one end to the other end every 500mm. Since the vertical side of the rolled profile is a beveled side, the top bed cannot apply force to the beveled side. Therefore, an ejector fixing tool is designed. The material of the fixing tool is PVC hard plastic. The profile of the tooling fixing block of the ejector fixing tool is consistent with the profile profile after rolling. The ejector fixing tool includes an upper cover area and a lower base area, which can fix the upper and lower ends of the rolled profile. The tooling fixing block includes 3 inner fixing blocks and 3 outer fixing blocks. Semi-cylindrical recessed areas are designed on the sides of the tooling fixing blocks on both sides to facilitate contact with the cylindrical guide column. The middle tooling fixing block is in contact with the ejector rod. Under the action of the ejector, the radius of the rolled profile is increased or decreased.

[0027] Compared with the prior art, the positive and negative rotation rolling forming method of a large obtuse angle unequal thickness profile frame described in the present invention has the following advantages:

[0028] (1) The present invention discloses a positive and negative rotation rolling forming method for a large obtuse angle and unequal thickness profile frame. The large obtuse angle and unequal thickness profile frame adopts a rolling forming method, which can directly roll and form hard materials, save the heat treatment process of stretching and bending, reduce production costs, and shorten the production cycle by 20%.

[0029] (2) The present invention discloses a positive and negative rotation rolling bending method for a large obtuse-angle and unequal-thickness profile frame. The large obtuse-angle and unequal-thickness profile frame adopts a positive and negative rotation rolling bending method with left and right feeding. The rolling process parameters are reasonably designed to roll and bend parts with qualified dimensions. The parts will not break during rolling, thereby improving the product qualification rate by 30%.

[0030] (3) The present invention discloses a method for positive and negative rotational rolling bending of a large obtuse-angled and unequal-thickness profile frame, which adopts an arc bending correction method and reasonably designs a bending die, and can effectively correct the radius size of the profile frame, ensuring that the three indicators of the profile frame rolling bending forming radius, flatness, and angle meet the requirements at the same time, thereby reducing the amount of manual trimming and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a schematic diagram of parts in the prior art;

[0033] Figure 2 It is a schematic diagram of part deformation in the prior art;

[0034] Figure 3 A schematic top view of the rolling bending according to an embodiment of the present invention;

[0035] Figure 4 It is a cross-sectional schematic diagram of the front and rear rollers according to an embodiment of the present invention;

[0036] Figure 5 It is a cross-sectional schematic diagram of the left and right rollers according to an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the intermediate tooling fixing block according to an embodiment of the present invention;

[0038] Figure 7 A schematic diagram of the curvature bending correction according to an embodiment of the present invention;

[0039] Figure 8 It is a schematic flow chart of the forming method described in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] like Figures 3 to 8 As shown, a positive and negative rotation rolling forming method for a large obtuse angle and unequal thickness profile frame comprises the following steps:

[0045] S1. Use a four-axis rolling machine to clamp large obtuse angle and unequal thickness profile frames (parts);

[0046] S2. Use left and right feeding rolling bending method and positive and negative rotation rolling bending method to correct the angle and flatness of the large obtuse angle and unequal thickness profile frame;

[0047] S3, using the arc correction method to correct the profile after rolling in step S2.

[0048] Advantages of the present invention:

[0049] (1) The large obtuse angle and unequal thickness profile frame is formed by rolling bending, which can directly roll and bend the hard material, saving the heat treatment process of stretch bending, reducing production costs, and reducing production cycle by 20%.

[0050] (2) The large obtuse angle and unequal thickness profile frame adopts the left and right feeding positive and negative rotation rolling forming method. The rolling process parameters are reasonably designed to roll and form parts with qualified dimensions. The rolling will not break, and the product qualification rate is increased by 30%.

[0051] (3) The arc bending correction method is adopted and the bending die is reasonably designed to effectively correct the radius size of the profile frame, ensure that the three indicators of the profile frame rolling forming radius, flatness and angle meet the requirements at the same time, reduce the amount of manual trimming, and improve production efficiency.

[0052] The large obtuse angle and unequal thickness profile frame is formed by roll bending. It is necessary to prevent the profile from twisting and warping, ensure the consistency of the overall length and angle of the profile, and meet the tolerance requirements. The large obtuse angle and unequal thickness profile frame adopts a four-axis roll bending machine. The two middle rollers clamp the profile. The horizontal movement of the left and right rollers can adjust the profile rolling radius. The left and right rollers plus the left and right pressure wheels can drive the profile section to rotate up and down a certain angle to correct the profile distortion. However, the process parameters of the rotation angle are difficult to control and must comply with the characteristics of the profile section. The rotation amount of the left and right rollers in each pass must meet a certain ratio. The roll bending diagram is as follows Figures 3 to 5 shown.

[0053] Specific rolling plan:

[0054] (1) Left and right feeding rolling method

[0055] Normal profile rolling forming is fed from one end, but the large obtuse angle and unequal thickness profile frame is fed from one end, and the tail end of the part is warped, and the flatness of the bottom edge of the tail end is poor. In order to ensure the flatness of the bottom edge and the small gap between the platform within the entire length of the profile, the left and right alternating feeding scheme is adopted to correct the flatness of the bottom edge.

[0056] (2) Positive and negative rotation rolling method

[0057] In normal profile rolling and bending, the rotation angle values ​​of the left and right rollers are consistent, but the angle of the large obtuse-angle unequal-thickness profile frame after rolling is out of tolerance, and the angle is uneven within the length range, with poor consistency. The rolling and bending forming of the present invention adopts a scheme in which the rotation angles of the left and right rollers in each pass are inconsistent, and one end rotates clockwise and the other end rotates counterclockwise to correct the profile angle deviation.

[0058] (3) Rolling process parameter setting

[0059] According to the positive and negative rotation rolling method, the process parameters are set as shown in Table 1.

[0060] Table 1 Large obtuse angle and unequal thickness profile frame rolling bending process parameters

[0061]

[0062] As can be seen from the table, there are 12 rolling bends in total. The first 4 rolling bends are fed from the left end. Driven by the roller, the parts are rolled back and forth four times. Then the parts are taken out, and the parts are fed from the right end, and rolled back and forth four times. Then the parts are fed from the left end, and rolled back and forth twice. The parts are taken out, and the parts are fed from the right end, and rolled back and forth twice. The 12 rolling bends are completed. Each two rolling bends are one reciprocating left and right, and the same values ​​are set to stabilize the parameters, maintain pressure, and improve precision.

[0063] The movement values ​​of the left and right rollers gradually increase, causing the radius of the profile to gradually decrease. The radius increases by 2mm every two times in the first 8 rolling bends, and increases by 0.5mm every two times in the last 4 rolling bends.

[0064] The rotation values ​​of the left and right rollers increase gradually to correct the profile angle. The rotation value of the left roller is clockwise, and the rotation value of the right roller is counterclockwise. In the first 8 rolling bends, the rotation values ​​of the left and right rollers increase by 2mm every two rolling bends, and the clockwise rotation value of the left roller and the counterclockwise rotation value of the right roller are the same. In the last 4 rolling bends, the rotation values ​​of the left and right rollers decrease gradually, and the clockwise rotation value of the left roller is 1° smaller than the counterclockwise rotation value of the right roller, which plays a role in angle correction.

[0065] The process parameters are obtained according to the above rules based on the test. After multiple tests, the curing process parameters are shown in Table 1. Then, the rolling program is formed according to this process parameter and saved in the rolling machine. In subsequent production, the program is called out to roll the part.

[0066] By using the left and right feeding plus positive and negative rotation rolling method, the angle and flatness of the large obtuse angle and unequal thickness profile frame can be effectively corrected. After 12 times of rolling, the angle and flatness gap of the profile gradually decreases. Finally, the gap between the bevel and the angle template is 0.5mm (required ≤0.8mm), and the gap between the bottom edge and the platform is 0.5mm (required ≤1.5mm), which meets the requirements of the drawing.

[0067] (4) Arc correction method

[0068] The three indicators of radius, flatness and angle must meet the requirements at the same time. The present invention proposes a curvature bending correction method, which uses a top bed to gradually bend the profile from one end to the other every 500mm. Since the vertical side of the large obtuse-angled and unequal-thickness profile frame is a beveled side, the top bed cannot apply force to the beveled side. Therefore, a ejection fixing tool is designed. The material is PVC hard plastic. The profile of the tool fixing block is consistent with the profile surface, and the upper cover plate area and the lower base area are designed to fix the upper and lower ends of the profile. The tool fixing block is designed with 3 inner shape fixing blocks and 3 outer shape fixing blocks. The side surfaces of the tool fixing blocks on both sides are designed with semi-cylindrical recessed areas to facilitate contact with the cylindrical guide pillars. The middle tool fixing block (such as Figure 6 As shown in the figure, it contacts with the ejector pin. Under the action of the ejector, the radius of the part is increased or decreased, and the arc is bent and corrected as shown in the figure. Figure 7 shown.

[0069] The ejection displacement of the ejector bed is different for parts with different radius differences, and the ejection process parameters are shown in Table 2.

[0070] Table 2 Process parameters of ejection amount with different radius difference

[0071] Radius clearance value 1mm 2mm 3mm Ejector displacement 3mm 5mm 7mm

[0072] According to this parameter, the correction arc is ejected, and the profile radius size and the sample gap size are 0.6mm (required ≤1.5mm), which meets the requirements of the drawing. The arc bending correction method can reduce the amount of manual trimming, improve the forming accuracy of parts, and improve the surface quality of parts.

[0073] The large obtuse-angle unequal-thickness profile frame rolling forming scheme of the present invention includes a left-right feeding rolling forming method and a positive-negative rotation rolling forming method, which can effectively correct the profile rolling distortion, roll-form parts with high dimensional accuracy, and improve the product qualification rate.

[0074] The method for bending and shaping a large obtuse-angle unequal-thickness profile frame of the present invention, combined with the bending and shaping tooling for the inner and outer surfaces of the profile and the process parameters of the ejection amount with different radius differences, can ensure that the three indicators of the profile frame rolling bending forming radius, flatness and angle meet the requirements at the same time, reduce the amount of manual trimming and improve production efficiency.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for positive and negative rotational rolling bending of large obtuse angle and unequal thickness profile frames, characterized in that: The following steps are involved: S1. Use a four-axis rolling machine to clamp the large obtuse angle and unequal thickness profile frame; S2. Use left and right feeding rolling bending method and positive and negative rotation rolling bending method to correct the angle and flatness of the large obtuse angle and unequal thickness profile frame; S3, using the arc correction method to correct the profile after rolling in step S2.

2. According to claim 1, a positive and negative rotation rolling forming method for a large obtuse angle and unequal thickness profile frame, characterized in that: In step S1, the four-axis rolling bending machine includes a left roller, a rear roller, a right roller, a left pressure roller, a front roller and a right pressure roller. The left side of the large obtuse-angle unequal-thickness profile frame is respectively provided with a left roller and a left pressure roller, the right side of the large obtuse-angle unequal-thickness profile frame is respectively provided with a right roller and a right pressure roller, and the front and rear sides of the large obtuse-angle unequal-thickness profile frame are respectively provided with a front roller and a rear roller.

3. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 1 is characterized in that: In step S2, the left and right feeding rolling bending method includes: The large obtuse angle and unequal thickness profile frame adopts the left and right alternating feeding scheme to correct the flatness of the bottom edge; Positive and negative rotational rolling methods include: The rolling process parameters are set, and the scheme of inconsistent rolling rotation angles of the left and right rollers in each pass is adopted, and one end rotates clockwise and the other end rotates counterclockwise to correct the angle deviation of the profile and obtain the profile after rolling.

4. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 3 is characterized in that: In step S2, the rolling process parameters are set, specifically including: Set the number of rolling bends, left and right roller movement values, left roller rotation value, right roller rotation value and feeding method.

5. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 4 is characterized in that: In step S2, the range of the number of rolling bending times is 6-20 times.

6. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 4, characterized in that: In step S2, the number of rolling bending is 12 times.

7. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 6, characterized in that: In step S2, the range of the left and right roller movement values ​​is 2 mm-9 mm.

8. The method for positive and negative rotational rolling forming of a large obtuse angle and unequal thickness profile frame according to claim 6, characterized in that: In step S2, the left roller rotation value ranges from 3 mm to 9.7 mm.

9. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 6, characterized in that: In step S2, the range of the right roller rotation value is -3 mm to 10.3 mm.

10. The method for positive and negative rotational rolling bending of a large obtuse angle and unequal thickness profile frame according to claim 6, characterized in that: In step S3, the arc correction method includes: The top bed is used to press and bend the contour of the rolled profile from one end to the other end every 500mm. Since the vertical side of the rolled profile is a beveled side, the top bed cannot apply force to the beveled side. Therefore, an ejector fixing tool is designed. The material of the fixing tool is PVC hard plastic. The profile of the tooling fixing block of the ejector fixing tool is consistent with the profile profile after rolling. The ejector fixing tool includes an upper cover area and a lower base area, which can fix the upper and lower ends of the rolled profile. The tooling fixing block includes 3 inner fixing blocks and 3 outer fixing blocks. Semi-cylindrical recessed areas are designed on the sides of the tooling fixing blocks on both sides to facilitate contact with the cylindrical guide column. The middle tooling fixing block is in contact with the ejector rod. Under the action of the ejector, the radius of the rolled profile is increased or decreased.

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