Roll forming process for non-constant cross-section variable thickness members

Abstract

The application discloses a roll forming process of a non-equal-section variable-thickness part and relates to the technical field of roll forming processes, and comprises the following steps: S1, first, analyzing the classification of the variable-thickness part along the length direction; S2, second, analyzing the thickness change of the part wall when the part thickness varies along the length direction, the inner wall thickness varies and the outer wall is flat. The application analyzes the influence of the roll forming process caused by the setting of the inner and outer roll reference gaps according to the different thicknesses of the part, and obtains the following ways of supplementally controlling the shape accuracy: limiting the difference between the maximum wall thickness and the minimum wall thickness of the rollable forming part, modifying the profile curve of the lower roll and adding a subsequent shaping section, so as to avoid the part wrinkling problem caused by the setting of the inner and outer roll reference gaps based on the minimum wall thickness of the part, and the problem that the sheet metal and the die cannot be closely fitted and the part shape is difficult to accurately control caused by the setting of the inner and outer roll reference gaps based on the maximum wall thickness of the part.

Description

Technical Field

[0001] This invention relates to the field of roll forming technology, specifically to the roll forming process for non-uniform cross-section variable thickness parts. Background Technology

[0002] Roll forming is commonly used to produce parts with uniform cross-sectional shapes, and it is characterized by high efficiency, economy and good forming quality. However, for parts with non-uniform cross-sections, the production process needs to be improved. Common non-uniform cross-section parts include two types: one is where the wall thickness is equal but the cross-section changes along the length direction, and the other is where the neutral line of the cross-section remains unchanged along the length direction but the wall thickness changes.

[0003] Therefore, we proposed a roll forming process for non-uniform cross-section variable thickness parts. This invention mainly focuses on the roll forming process analysis of parts with variable thickness along the length direction, explores the influence of the reference gap setting of inner and outer rolls on the roll forming process of parts with variable thickness along the length direction, and finally derives a supplementary method for controlling shape accuracy in order to solve the problems of roll forming parts with variable thickness along the length direction. Summary of the Invention

[0004] The purpose of this invention is to provide a roll forming process for non-uniform cross-section variable thickness parts. The roll forming process is analyzed for parts with variable thickness along the length direction. The influence of the reference gap setting of the inner and outer rolls on the roll forming process of parts with variable thickness along the length direction is explored. Finally, a method for supplementing the control of shape accuracy is derived to solve the problems of roll forming parts with variable thickness along the length direction.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a roll forming process for non-uniform cross-section variable thickness parts, comprising the following steps:

[0006] S1. First, analyze the classification of parts with varying thickness along the length direction;

[0007] S2. Next, we analyze the changes in the wall thickness of the part when the thickness varies along the length direction, the inner wall varies in thickness, and the outer wall is straight.

[0008] S3. Analyze the influence of the reference gap between the inner and outer rolls on the roll forming process of non-uniform cross-section variable thickness parts.

[0009] Preferably, in step S1, the part with varying thickness along the length direction can be divided into three cases: the inner wall of the part has varying thickness and the outer wall is straight; the outer wall of the part has varying thickness and the inner wall is straight; and both the inner and outer walls of the part have varying thickness.

[0010] Preferably, in step S2, when the part has varying thickness along its length, with varying thickness on the inner wall and a straight outer wall, it can be divided into five segments along its length: the first segment has a wall thickness of a, the second segment is a transition zone, the third segment has a wall thickness of b, the fourth segment is a transition zone, and the fifth segment has a wall thickness of c.

[0011] Preferably, in step S3, when performing roll forming on a part with varying thickness along its length, varying inner wall thickness, and a straight outer wall, since the outer wall of the part is straight, the outer rollers of the part are the same as in the traditional roll forming process and are not changed. Since the inner wall of the part has varying thickness, the position of the inner rollers is set to change with the thickness during the roll forming process. The change in the position of the inner rollers causes the gap between the inner and outer rollers to change in order to adapt to the thickness variation of the part. Therefore, it is necessary to set a reference gap between the inner and outer rollers.

[0012] Preferably, in step S3, the reference gap between the inner and outer rolls can be set in three ways: based on the minimum wall thickness of the part, that is, the minimum value of a, b, and c is set as the reference gap between the inner and outer rolls; based on the maximum wall thickness of the part, that is, the maximum value of a, b, and c is set as the reference gap between the inner and outer rolls; and the reference gap between the inner and outer rolls is between the maximum wall thickness and the minimum wall thickness.

[0013] Preferably, in step S3, when setting the reference gap between the inner and outer rolls based on the minimum wall thickness of the part, the analysis of the influence of the reference gap between the inner and outer rolls on the roll forming process of the part includes:

[0014] S31. When rolling the minimum wall thickness section, the process is the same as the ordinary rolling process. The difference is that when rolling the larger wall thickness section, due to the increase in the wall thickness of the part, the inner roll needs to move upward to ensure that the inner and outer rolls are in close contact with the part during the rolling process. However, during the movement of the inner roll, due to the limitation of the geometric shape, the gap between the inner and outer rolls does not change uniformly.

[0015] S32. Assuming the change in part wall thickness is m, theoretically the inner roller needs to move upward by m, that is, the upward offset distance of the inner roller is m.

[0016] S33. In the horizontal section, the inner roller offset distance is consistent with the change in the part wall thickness. In the inclined section, since the inner roller offset is in the vertical upward direction, while the change in the part wall thickness is in the direction perpendicular to the normal surface of the part, the actual offset of the inner roller will result in the gap between the inner and outer rollers being only h, and the difference between the inner and outer rollers and the actual wall thickness is k.

[0017] S34. Assuming the inclination angle of the inclined section is α, the difference between the inner and outer roller gap and the actual wall thickness can be calculated through geometric relationships, k = m(1-cosα). For example, when the inclination angle α is 60°, the wall thickness change is 2mm, then k = 1mm.

[0018] S35. Because the gap between the inner and outer rolls in the inclined section is less than the wall thickness, more sheet material enters the smaller rolling space. The sheet material will be squeezed and moved to the side perpendicular to the rolling direction. However, due to the limitation of the friction of the rolls, only a small part of the material extends to the side perpendicular to the rolling direction.

[0019] Preferably, in step S34, according to the principle of equal volume in metal forming process, more material is extended along the rolling direction, causing wrinkling of the part. Since wrinkling is an unacceptable defect in most sheet metal parts, the reference gap between the inner and outer rolls is set based on the minimum wall thickness of the part, which can only be used for the production of a few parts where the requirements for wrinkling are not strict.

[0020] Preferably, in step S3, when setting the reference gap between the inner and outer rolls based on the maximum wall thickness of the part, the analysis method for the influence of the reference gap between the inner and outer rolls on the roll forming process of the part is similar to that described above. When rolling the maximum wall thickness section, it is consistent with the ordinary rolling process, and when rolling the smaller wall thickness section, the inner roll needs to be moved downward.

[0021] Preferably, when the reference gap between the inner and outer rollers is set based on the maximum wall thickness of the part, in the horizontal section, the offset distance of the inner roller is consistent with the change in the wall thickness of the part. In the inclined section, the gap h between the inner and outer rollers is greater than the actual wall thickness, which will cause the sheet metal and the mold to not fit tightly and make it difficult to accurately control the shape of the part.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] In the roll forming process of non-uniform cross-section variable thickness parts of the present invention, when only the inner wall of the part changes thickness, the outer roll is set in the same way as the traditional roll forming process, the position of the inner roll changes with the thickness, and the reference gap between the inner and outer rolls is set between the minimum and maximum wall thickness of the part; when only the outer wall of the part changes thickness, the inner roll is set in the same way as the traditional roll forming process, the position of the outer roll changes with the thickness, and the reference gap between the inner and outer rolls is set based on the maximum wall thickness of the part; when both the inner and outer walls of the part change thickness, the positions of both the inner and outer rolls change with the thickness, and the reference gap between the inner and outer rolls is set based on the maximum wall thickness of the part.

[0024] By analyzing the impact of different wall thicknesses of parts on the roll forming process caused by setting the reference gap between the inner and outer rolls, the following methods were found to supplement the control of shape accuracy: limiting the difference between the maximum and minimum wall thickness of roll-formable parts, adjusting the contour curve of the lower roll, and adding subsequent shaping sections. This avoids the problem of part wrinkling caused by setting the reference gap between the inner and outer rolls based on the minimum wall thickness of the part, and the problem of the sheet metal and mold not being able to fit tightly and making it difficult to accurately control the shape of the part when setting the reference gap between the inner and outer rolls based on the maximum wall thickness of the part. Attached Figure Description

[0025] Figure 1 This is a flowchart of the roll forming process for the non-uniform cross-section variable thickness part of the present invention;

[0026] Figure 2 This is a process analysis diagram showing the setting of the reference gap between the inner and outer rolls based on the minimum wall thickness of the part in the roll forming process of the non-uniform cross-section variable thickness part of the present invention.

[0027] Figure 3 This is a process analysis diagram showing the setting of the reference gap between the inner and outer rolls based on the maximum wall thickness of the part in the roll forming process of the non-uniform cross-section variable thickness part of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Please see Figure 1-3 This invention provides a technical solution: a roll forming process for non-uniform cross-section variable thickness parts, comprising the following steps:

[0030] Step 1: First, analyze the classification of parts with varying thickness along the length direction. Parts with varying thickness along the length direction can be divided into three cases: the inner wall of the part has varying thickness and the outer wall is flat; the outer wall of the part has varying thickness and the inner wall is flat; and both the inner and outer walls of the part have varying thickness.

[0031] Step 2: Next, analyze the changes in the part's wall thickness when the thickness varies along the length direction, the inner wall thickness varies, and the outer wall is flat. When the part's thickness varies along the length direction, the inner wall thickness varies, and the outer wall is flat, it can be divided into five segments along the length direction. The first segment has a wall thickness of a, the second segment is a transition zone, the third segment has a wall thickness of b, the fourth segment is a transition zone, and the fifth segment has a wall thickness of c.

[0032] Step 3: Analyze the influence of the reference gap between the inner and outer rolls on the roll forming process of non-uniform cross-section variable thickness parts. When roll forming parts with variable thickness along the length direction, variable inner wall thickness, and straight outer wall, the outer rolls are the same as in the traditional roll forming process and are not changed because the outer wall of the part is straight. However, due to the variable thickness of the inner wall of the part, the position of the inner rolls is set to change with the thickness during the roll forming process. The change in the position of the inner rolls leads to a change in the gap between the inner and outer rolls to adapt to the thickness change of the part. Therefore, it is necessary to set the reference gap between the inner and outer rolls. The reference gap between the inner and outer rolls can be set in three ways: based on the minimum wall thickness of the part, that is, the minimum value of a, b, and c is set as the reference gap between the inner and outer rolls; based on the maximum wall thickness of the part, that is, the maximum value of a, b, and c is set as the reference gap between the inner and outer rolls; and the reference gap between the inner and outer rolls is between the maximum wall thickness and the minimum wall thickness.

[0033] When the reference gap between the inner and outer rolls is set based on the minimum wall thickness of the part, the analysis of the influence of the reference gap between the inner and outer rolls on the roll forming process of the part includes:

[0034] 31) When rolling the minimum wall thickness section, the process is the same as that of ordinary rolling. The difference is that when rolling the larger wall thickness section, due to the increase in the wall thickness of the part, the inner roll needs to move upward to ensure that the inner and outer rolls are in close contact with the part during the rolling process. However, during the movement of the inner roll, due to the limitation of the geometric shape, the gap between the inner and outer rolls does not change uniformly.

[0035] 32) Assuming the change in part wall thickness is m, theoretically the inner roller needs to move upward by m, that is, the upward offset distance of the inner roller is m;

[0036] 33) In the horizontal section, the inner roller offset distance is consistent with the change in the part wall thickness. In the inclined section, since the inner roller offset is in the vertical upward direction, while the change in the part wall thickness is in the direction perpendicular to the normal surface of the part, the actual offset of the inner roller will result in the gap between the inner and outer rollers being only h, which is k compared to the actual wall thickness.

[0037] 34) Assuming the inclination angle of the inclined section is α, the difference between the inner and outer roller gap and the actual wall thickness can be calculated through geometric relationships, k = m(1-cosα). For example, when the inclination angle α is 60°, the wall thickness change is 2mm, then k = 1mm.

[0038] 35) Because the gap between the inner and outer rolls in the inclined section is less than the wall thickness, more sheet material enters the smaller rolling space. The sheet material will be squeezed to move towards the side perpendicular to the rolling direction. However, due to the limitation of the friction of the rolls, only a small part of the material extends towards the side perpendicular to the rolling direction. According to the principle of equal volume in metal forming process, more material extends along the rolling direction, causing wrinkling of the part. Since wrinkling is an unacceptable defect in most sheet metal parts, the reference gap between the inner and outer rolls is set based on the minimum wall thickness of the part. It can only be used for the production of a few parts where the requirements for wrinkling are not strict.

[0039] When setting the reference gap between the inner and outer rolls based on the maximum wall thickness of the part, the analysis method for the influence of the reference gap between the inner and outer rolls on the roll forming process of the part is similar to that described above. When rolling the maximum wall thickness section, it is consistent with the ordinary rolling process. When rolling the smaller wall thickness section, the inner roll needs to move downward. In the horizontal section, the offset distance of the inner roll is consistent with the change in the wall thickness of the part. In the inclined section, the gap h between the inner and outer rolls is greater than the actual wall thickness, which will cause the sheet and the mold to not fit tightly together, making it difficult to accurately control the shape of the part.

[0040] In this invention, the roll forming process for non-uniform cross-section variable thickness parts focuses on parts with varying thickness along their length, varying inner wall thickness, and a straight outer wall. The roll forming process is analyzed by considering the reference gap between the inner and outer rolls for different wall thicknesses. Since the outer wall is straight, the outer rolls are handled identically to those in traditional roll forming processes without modification. However, due to the varying inner wall thickness, the position of the inner rolls changes with the thickness during forming. This change in the inner roll position alters the gap between the inner and outer rolls to accommodate the varying thickness of the part.

[0041] When setting the reference gap between the inner and outer rolls based on the minimum wall thickness of the part, when rolling a larger wall thickness section, the inner roll needs to move upwards due to the increase in part wall thickness to ensure that the inner and outer rolls are in close contact with the part during the rolling process. However, during the movement of the inner roll, due to geometric limitations, the gap between the inner and outer rolls does not change uniformly, such as... Figure 2 As shown, in the horizontal section, the inner roller offset distance is consistent with the change in part wall thickness. In the inclined section, since the inner roller offset is in the vertical upward direction, while the change in part wall thickness is in the direction perpendicular to the normal surface of the part, there will be a difference between the gap between the inner and outer rollers and the actual wall thickness after the inner roller is offset. Since the gap between the inner and outer rollers is smaller than the wall thickness in the inclined section, more sheet material enters the smaller rolling space. The sheet material will be squeezed to move towards the side perpendicular to the rolling direction. However, due to the limitation of the roller friction, only a small part of the material extends towards the side perpendicular to the rolling direction. According to the principle of equal volume in metal forming process, more material extends along the rolling direction, causing wrinkling of the part. Since wrinkling is an unacceptable defect in most sheet metal parts, the reference gap between the inner and outer rollers is set based on the minimum wall thickness of the part. This can only be used for the production of a few parts where the requirements for wrinkling are not strict.

[0042] When setting the reference gap between the inner and outer rolls based on the maximum wall thickness of the part, the analysis method is similar to that described above. The rolling process for the maximum wall thickness section is consistent with ordinary rolling technology. When rolling the smaller wall thickness section, the inner roll needs to move downwards. Figure 3 As shown, in the horizontal section, the offset distance of the inner roller is consistent with the change in the wall thickness of the part. In the inclined section, the gap between the inner and outer rollers is greater than the actual wall thickness, which will cause the sheet metal and the mold to not fit tightly, making it difficult to accurately control the shape of the part.

[0043] For parts with varying outer wall thickness, flat inner wall, or varying thickness along the length of both inner and outer walls, the design principle of the roll forming process is similar to that of parts with varying inner wall thickness and flat outer wall. When only the outer wall thickness varies, the inner rolls are set in the same way as in the traditional roll forming process, while the position of the outer rolls changes with the thickness. The reference gap between the inner and outer rolls is set based on the maximum wall thickness of the part. When both the inner and outer walls of the part have varying thickness, the positions of both the inner and outer rolls change with the thickness, and the reference gap between the inner and outer rolls is set based on the maximum wall thickness of the part. The control of the roll position needs to ensure sufficient accuracy and response speed, so a servo electric cylinder is used instead of a hydraulic cylinder due to the accuracy limitations of hydraulic valves.

[0044] By analyzing the impact of different wall thicknesses of parts on the roll forming process caused by setting the reference gap between the inner and outer rolls, the following methods were found to supplement the control of shape accuracy: limiting the difference between the maximum and minimum wall thickness of roll-formable parts, adjusting the contour curve of the lower roll, and adding subsequent shaping sections. This avoids the problem that setting the reference gap between the inner and outer rolls based on the minimum wall thickness of the part can easily cause wrinkling of the part, and setting the reference gap between the inner and outer rolls based on the maximum wall thickness of the part can cause the sheet metal and the mold to not fit tightly, making it difficult to accurately control the shape of the part.

[0045] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A roll forming process for non-uniform cross-section variable thickness parts, characterized in that, Includes the following steps: S1. Analyze and classify parts with varying thickness along their length. S2. Analyze the changes in the wall thickness of the part when the thickness varies along the length direction, the inner wall varies in thickness, and the outer wall is flat. In step S2, when the thickness varies along the length direction, the inner wall varies in thickness, and the outer wall is flat, it can be divided into five segments along the length direction. The wall thickness of the first segment is a, the second segment is a transition zone, the wall thickness of the third segment is b, the fourth segment is a transition zone, and the wall thickness of the fifth segment is c. S3. Analyze the influence of the reference gap between the inner and outer rolls on the roll forming process of non-uniform cross-section variable thickness parts; wherein, when the reference gap between the inner and outer rolls is set based on the minimum wall thickness of the part, the analysis of the influence of the reference gap between the inner and outer rolls on the roll forming process of the part includes: In step S3, when performing roll forming on a part with varying thickness along its length, varying inner wall thickness, and a straight outer wall, since the outer wall of the part is straight, the outer rollers of the part are the same as in the traditional roll forming process and are not changed. Since the inner wall of the part varies in thickness, the position of the inner rollers is set to change with the thickness during the roll forming process. The change in the position of the inner rollers causes the gap between the inner and outer rollers to change in order to adapt to the thickness variation of the part. The minimum wall thickness of the part is set, that is, the minimum value of a, b, and c is set as the reference gap between the inner and outer rollers. S31. When rolling the minimum wall thickness section, the process is the same as the ordinary rolling process. The difference is that when rolling the larger wall thickness section, due to the increase in the wall thickness of the part, the inner roll needs to move upward to ensure that the inner and outer rolls are in close contact with the part during the rolling process. However, during the movement of the inner roll, due to the limitation of the geometric shape, the gap between the inner and outer rolls does not change uniformly. S32. The wall thickness of the part changes by m. The inner roller needs to move upward by m. That is, the upward offset distance of the inner roller is m. A is the wall thickness change line, B is the upper roller offset line, C is the lower roller reference line, and D is the upper roller reference line. S33. In the horizontal section, the inner roller offset distance is consistent with the change in the part wall thickness. In the inclined section, since the inner roller offset is in the vertical upward direction, while the change in the part wall thickness is in the direction perpendicular to the normal surface of the part, the actual offset of the inner roller will result in the gap between the inner and outer rollers being only h, and the difference between the inner and outer rollers and the actual wall thickness is k. S34, the inclination angle of the inclined segment is The difference between the gap between the inner and outer rollers and the actual wall thickness can be calculated using geometric relationships. .

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