Combined profile structure and forming method thereof

Abstract

The invention provides a forming method of a combined profile structure. The forming method comprises the following steps that S1, primary rolling is conducted, specifically, a primary roller press gradually changes the section of a material belt into a circular tube shape through a pre-pressing roller and a plurality of sets of forming rollers; s2, external welding, wherein the two aligned side edges of the material belt are welded through a welding machine; s3, secondary rolling is conducted, specifically, a secondary rolling machine gradually rolls the section shape of the material belt from a circular tube shape to a flat square tube shape through a plurality of sets of shaping rollers and shape righting rollers; s5, cutting off: cutting off the material belt according to a preset length through a cutting machine; s6, laser welding is conducted, specifically, at least two strip-shaped reinforcing ribs are inserted into an inner hole of the cut-off material strip, the reinforcing ribs are arranged in parallel to the axial direction of the material strip, and the multiple reinforcing ribs are inserted into the flat square tubular structure at intervals in the left-right direction; and then the upper ends and the lower ends of the reinforcing ribs are welded to the upper side wall and the lower side wall of the flat square tubular structure correspondingly through a laser welding machine. The invention further provides a combined profile structure.

Description

Technical Field

[0001] The present invention relates to the technical field of profile processing, and in particular to a combined profile structure and a forming method of the combined profile structure. Background Art

[0002] Existing new energy vehicles require multiple batteries to provide kinetic energy. In order to minimize the weight of the battery pack, a battery pack frame that is lightweight and has strong rigidity and compressive strength is needed for support.

[0003] At present, the materials commonly used in the market for battery pack frames are all made of aluminum alloy. In order to ensure rigidity and strength, the cross-sections of the frames, crossbeams, longitudinal beams, etc. of the battery pack frames are all complex cross-sections. Ultra-high-strength steel has advantages in performance, price, availability, life cycle emissions, recyclability, and maintainability. There are many difficulties in the traditional process of forming ultra-high-strength steel, such as low forming accuracy, severe springback, easy cracking of products, and high cost. To make up for the above defects, the first-generation process generally adopts the method of increasing the material thickness, which leads to increased product weight and increased costs. The second-generation process uses a Japanese cross-section, which improves the rigidity and strength of the product to a certain extent, but compared with complex aluminum alloy profiles, the strength-to-weight ratio (ratio of strength to weight) is still relatively weak. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the profiles made of ultra-high strength steel in the prior art are relatively weak in strength due to structural limitations.

[0005] In order to solve the above problems, the present invention provides a molding method of a combined profile structure, comprising the following steps:

[0006] S1. Primary rolling: The flat material strip is sent to a primary rolling machine, which is provided with at least one set of pre-pressing rollers and multiple sets of forming rollers along the direction of travel of the material strip, wherein the pre-pressing rollers are used to roll the two sides of the material strip in the width direction into an arc shape with the concave arc side upward, and at this time, the two sides of the material strip in the width direction are lower than the middle of the material strip, and then the material strip is rolled by the multiple sets of forming rollers, so that the two sides of the material strip in the width direction gradually deform upward, and the cross-section of the material strip gradually changes into a circular tubular structure, until the two sides of the material strip in the width direction are aligned with each other;

[0007] S2, external welding: welding the aligned two sides of the strip output from the primary roller press by a welding machine;

[0008] S3, secondary rolling: the material strip output from the welding machine is sent to the secondary rolling machine, and the secondary rolling machine is provided with multiple sets of shaping rollers and at least one set of corrective rollers along the direction of the material strip. The shaping rollers are used to gradually roll the cross-sectional shape of the material strip from a round tube to a flat square tube structure, and the corrective rollers are used to correct the material strip of the flat square tube structure to ensure that the upper side wall and the lower side wall of the material strip are parallel, and the left side wall and the right side wall are parallel;

[0009] S5, cutting: cutting the material strip output from the secondary roller press according to a preset length by a cutting machine;

[0010] S6. Laser welding: insert at least two strip-shaped reinforcing ribs into the inner hole of the cut material strip, the reinforcing ribs are arranged parallel to the axial direction of the material strip, and the upper and lower ends of the reinforcing ribs have bending portions, and multiple reinforcing ribs are inserted into the interior of the flat square tubular structure at intervals along the left and right directions, and then the material strip is conveyed to the laser welder, and the laser welder welds the upper and lower ends of the reinforcing ribs to the upper and lower side walls of the flat square tubular structure respectively.

[0011] Compared with the prior art, the above scheme firstly processes the material strip into a circular tubular structure by a single rolling process, wherein the pre-pressing roller first rolls the two side parts of the material strip in the width direction into an arc shape with a concave arc side upward, so that in the process of the subsequent forming roller rolling the material strip so that the cross section of the material strip gradually becomes a circular tubular shape, the two side parts of the material strip in the width direction will not be deformed too much and cause the strength to decrease; secondly, the aligned two side edges of the material strip output from the primary rolling machine are welded by a welding machine so that the material strip forms an integrated circular tubular structure, and then the material strip is gradually rolled into a flat square tubular structure by the shaping roller of the secondary rolling machine. The material strip is already an integrated circular tubular structure, and the weld is located in the middle of the upper side of the circular tubular structure of the material strip. Therefore, the deformation is more uniform and stable in the process of becoming a flat square tubular structure, and the molding quality is good. The flat square tubular structure of the material strip is further corrected by a corrective roller to ensure the final molding quality. Finally, the material strip with the formed flat square tubular structure is cut as needed, and at least two strip-shaped reinforcing ribs are inserted into the inner hole of the cut material strip. The upper side wall and the lower side wall of the flat square tubular structure of the material strip are connected and reinforced by the reinforcing ribs, thereby effectively improving the structural strength of the profile composed of the main body and the reinforcing ribs.

[0012] In an improved solution, the material of the strip is ultra-high strength steel with a yield strength ≥1000Mpa, a tensile strength ≥1200Mpa, and an elongation after fracture ≥9%. Ultra-high strength steel has a lower material cost than aluminum alloy, which is conducive to controlling overall costs.

[0013] In an improved solution, in step S6, the number of reinforcing ribs is three, thereby ensuring that the reinforcing ribs have a good reinforcement effect on the upper side walls and lower side walls of the main body of the flat square tubular structure without excessively increasing the processing difficulty, thereby achieving a good balance between the reinforcement effect and the processing difficulty.

[0014] In an improved solution, in step S2, the welding machine welds the aligned two side edges of the material strip by self-melting welding, so that the circular tubular structure formed by welding the aligned two side edges of the material strip by the welding machine has a better degree of integration, which is beneficial to the subsequent shaping during the secondary rolling.

[0015] The present invention also provides a combined profile structure, including a main body and at least two reinforcing ribs, the main body being formed by rolling a material strip to enclose a flat square tubular structure, the upper side wall and the lower side wall of the main body being the long sides, and the left side wall and the right side wall being the short sides; the two side edges of the material strip are aligned in the middle of the upper side of the flat square tubular structure and then connected to each other by welding, the reinforcing ribs being arranged parallel to the axial direction of the main body, and the upper and lower ends of the reinforcing ribs both having bending portions, a plurality of the reinforcing ribs being inserted into the interior of the main body at intervals along the left-right direction, and the upper and lower ends of the reinforcing ribs being respectively welded to the upper side wall and the lower side wall of the main body.

[0016] Compared with the prior art, the above scheme integrates the material strip into a flat square tubular structure main body by rolling, and arranges at least two reinforcing ribs inside the main body, and connects and reinforces the upper side wall and the lower side wall of the main body by the reinforcing ribs, thereby effectively improving the structural strength of the profile composed of the main body and the reinforcing ribs. Under the same weight, the stiffness and strength of the profile of the above scheme are better than those of the existing structure, so it can be made thinner and lighter, thereby achieving the lightweight of the battery pack frame on the basis of ensuring the structural strength.

[0017] In an improved solution, the material of the strip is ultra-high strength steel with a yield strength ≥1000Mpa, a tensile strength ≥1200Mpa, and an elongation after fracture ≥9%. Ultra-high strength steel has a lower material cost than aluminum alloy, which is conducive to controlling overall costs.

[0018] In an improved solution, the number of the reinforcing ribs is three, thereby ensuring that the reinforcing ribs have a good reinforcement effect on the upper side walls and lower side walls of the main body of the flat square tubular structure without excessively increasing the processing difficulty, thereby achieving a good balance between the reinforcement effect and the processing difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A thumbnail diagram of a processing production line for a molding method of a combined profile structure;

[0020] Figure 2 A schematic diagram of a one-step rolling process of a forming method for a combined profile structure Figure 1 ;

[0021] Figure 3 A schematic diagram of a one-step rolling process of a forming method for a combined profile structure Figure 2 ;

[0022] Figure 4 A schematic diagram of the secondary rolling process of a forming method for a combined profile structure Figure 1 ;

[0023] Figure 5 A schematic diagram of the secondary rolling process of a forming method for a combined profile structure Figure 2 ;

[0024] Figure 6 is a schematic cross-sectional view of a combined profile structure;

[0025] Figure 7 It is a reference diagram for strength analysis of aluminum alloy profiles;

[0026] Figure 8 This is the reference diagram for strength analysis of the Japanese-shaped profile;

[0027] Fig. 9 A strength analysis reference diagram of the combined profile of the present invention;

[0028] Fig.10 It is a reference diagram for the stiffness analysis of aluminum alloy profiles;

[0029] Fig.11 This is the reference diagram for the stiffness analysis of the Japanese-shaped profile;

[0030] Fig.12 This is a reference diagram for the stiffness analysis of the combined profile of the present invention.

[0031] Description of reference numerals:

[0032] a1, primary roller press; a2, welding machine; a3, secondary roller press; a4, cutting machine; a5, laser welder; a6, material rack; 1, main body; 2, reinforcing ribs; 21, bending part. DETAILED DESCRIPTION

[0033] It should be understood by those skilled in the art that the following embodiments are only used to explain the technical principles of the embodiments of the present application and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art may adjust them as needed to adapt to specific application scenarios.

[0034] In the description of the following embodiments, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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 an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0035] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] See also Figure 1-Figure 5 Embodiment 1 of the present invention provides a method for forming a combined profile structure, comprising the following steps:

[0038] S1, primary rolling: the rolled material strip is unrolled to a flush state by the material rack a6 and then sent to the primary rolling machine a1. The primary rolling machine a1 is provided with at least one set of pre-pressing rollers and multiple sets of forming rollers along the traveling direction of the material strip, wherein the pre-pressing rollers are used to roll the two sides of the width direction of the material strip into an arc shape with the concave arc side upward, and at this time, the two sides of the width direction of the material strip are lower than the middle part of the material strip, and then the material strip is rolled by the multiple sets of forming rollers, so that the two sides of the width direction of the material strip are gradually deformed upward, and the cross section of the material strip gradually becomes a circular tubular structure, until the two sides of the width direction of the material strip are aligned with each other;

[0039] S2, external welding: welding the aligned two sides of the strip output from the primary roller press a1 by the welding machine a2;

[0040] S3, secondary rolling: the material strip output from the welding machine a2 is sent to the secondary rolling machine a3, and the secondary rolling machine a3 is provided with multiple sets of shaping rollers and at least one set of corrective rollers along the moving direction of the material strip. The shaping rollers are used to gradually roll the cross-sectional shape of the material strip from a round tube to a flat square tube structure, and the corrective rollers are used to correct the material strip of the flat square tube structure to ensure that the upper side wall and the lower side wall of the material strip are parallel, and the left side wall and the right side wall are parallel;

[0041] S5, cutting: cutting the material strip output from the secondary roller press a3 into a preset length by the cutting machine a4;

[0042] S6, laser welding: insert at least two strip-shaped reinforcing ribs 2 into the inner hole of the cut material strip, the reinforcing ribs 2 are arranged parallel to the axial direction of the material strip, and the upper and lower ends of the reinforcing ribs 2 have bending portions 21, and multiple reinforcing ribs 2 are inserted into the interior of the flat square tubular structure at intervals along the left and right directions, and then the material strip is conveyed to the laser welder a5, and the laser welder a5 welds the upper and lower ends of the reinforcing ribs 2 to the upper and lower side walls of the flat square tubular structure respectively.

[0043] Figure 2 A schematic diagram of a one-step rolling process of a forming method for a combined profile structure Figure 1 ,in Figure 2 The upper left position is the initial state of the material strip, and the lower right position is the state where the cross section of the material strip changes to a circular tube; Figure 4 A schematic diagram of the secondary rolling process of a forming method for a combined profile structure Figure 1 ,in Figure 4 The upper left position shows that the cross section of the material strip has become a circular tube, and the lower right position shows that the cross section of the material strip has become a flat square tube.

[0044] In the above scheme, the material strip is first processed into a circular tubular structure by a single rolling process, wherein the pre-pressing roller first rolls the two side parts of the material strip in the width direction into an arc shape with the concave arc side upward, so that in the process of the subsequent forming roller rolling the material strip so that the cross-section of the material strip gradually becomes a circular tubular shape, the two side parts of the material strip in the width direction will not be deformed too much and cause the strength to decrease; secondly, the aligned two side edges of the material strip output from the primary rolling machine a1 are welded by the welding machine a2, so that the material strip forms an integrated circular tubular structure, and then the material strip is gradually rolled into a flat square tubular structure by the shaping roller of the secondary rolling machine a3. Since the material strip has been It is an integrated circular tubular structure, and the weld is located in the middle of the upper side of the circular tubular structure of the material strip. Therefore, the deformation of the material strip in the process of becoming a flat square tubular structure is more uniform and stable, and the molding quality is good. The flat square tubular structure of the material strip is further corrected by a corrective roller to ensure the final molding quality; finally, the material strip with the formed flat square tubular structure is cut according to needs, and at least two strip-shaped reinforcing ribs 2 are inserted into the inner hole of the cut material strip, and the upper side wall and the lower side wall of the flat square tubular structure of the material strip are connected and reinforced by the reinforcing ribs 2, thereby effectively improving the structural strength of the profile composed of the main body 1 and the reinforcing ribs 2.

[0045] In this embodiment, the material of the strip is preferably ultra-high strength steel, with a yield strength of ≥1000Mpa, a tensile strength of ≥1200Mpa, and an elongation after fracture of ≥9%; ultra-high strength steel has a lower material cost than aluminum alloy, which is conducive to controlling the overall cost. Of course, the material of the strip can also be replaced by aluminum alloy or other materials.

[0046] In step S6, the number of reinforcing ribs 2 is preferably three, thereby ensuring that the reinforcing ribs 2 have a good reinforcement effect on the upper side walls and lower side walls of the main body 1 of the flat square tubular structure without excessively increasing the processing difficulty, thereby achieving a good balance between the reinforcement effect and the processing difficulty; and the presence of the bending portion 21 can make the welding of the reinforcing ribs 2 and the upper side walls and lower side walls of the flat square tubular structure of the material strip more stable.

[0047] Furthermore, in step S2, the welding machine a2 welds the aligned two side edges of the material strip by self-melting welding, so that the circular tubular structure formed by welding the aligned two side edges of the material strip by the welding machine a2 has a better degree of integration, which is beneficial to the subsequent shaping during the secondary rolling.

[0048] Embodiment 2 of the present invention provides a combined profile structure, including a main body 1 and at least two reinforcing ribs 2. The main body 1 is formed by rolling a material strip to form a flat square tubular structure. The upper side wall and the lower side wall of the main body 1 are long sides, and the left side wall and the right side wall are short sides. The two side edges of the material strip are aligned in the middle of the upper side of the flat square tubular structure and then connected to each other by welding. The reinforcing ribs 2 are arranged parallel to the axial direction of the main body 1, and the upper and lower ends of the reinforcing ribs 2 have bending portions 21. Multiple reinforcing ribs 2 are inserted into the interior of the main body 1 at intervals along the left-right direction, and the upper and lower ends of the reinforcing ribs 2 are respectively welded to the upper side wall and the lower side wall of the main body 1.

[0049] The above scheme integrates the material strip into a main body 1 of a flat square tubular structure in the form of rolling, and arranges at least two reinforcing ribs 2 inside the main body 1, and connects and reinforces the upper side wall and the lower side wall of the main body 1 through the reinforcing ribs 2, thereby effectively improving the structural strength of the profile composed of the main body 1 and the reinforcing ribs 2. Under the same weight, the stiffness and strength of the profile of the above scheme are better than those of the existing structure, so it can be made thinner and lighter, thereby achieving the lightweight of the battery pack frame while ensuring the structural strength.

[0050] The number of reinforcing ribs 2 is preferably three, thereby ensuring that the reinforcing ribs 2 have a good reinforcement effect on the upper and lower side walls of the main body 1 of the flat square tubular structure without excessively increasing the processing difficulty, thereby achieving a good balance between the reinforcement effect and the processing difficulty; the material of the material strip is preferably ultra-high strength steel with a yield strength ≥1000Mpa, a tensile strength ≥1200Mpa, and an elongation after fracture ≥9%; the material cost of ultra-high strength steel is lower than that of aluminum alloy, which is conducive to controlling the overall cost.

[0051] After actual testing, see Figure 7-9 , which are strength analysis diagrams of aluminum alloy profiles, Japanese-shaped profiles and the combined profile of the present invention; Figure 10-12 , which are stiffness analysis diagrams of aluminum alloy profiles, Japanese-shaped profiles and the combined profile of the present invention, respectively. It can be seen that the combined profile of the present invention is stronger than the aluminum alloy profile and the Japanese-shaped profile in terms of both strength and stiffness. In addition, the strength-to-weight ratio of the combined profile structure of Example 2 is significantly improved compared with conventional aluminum alloy or Japanese-shaped steel profiles, as shown in the table below.

[0052]

[0053]

[0054] It should be noted that, in the description of the present application, the terms "inside", "outside", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application. All directional indications (such as up, down, left, right, front, back, inside, and outside) are only used to explain the relative positional relationship, movement, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0055] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0056] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for forming a combined profile structure, characterized in that: The following steps are involved: S1. One-time rolling: the flat material strip is sent to a one-time rolling machine (a1), and the one-time rolling machine (a1) is provided with at least one set of pre-pressing rollers and multiple sets of forming rollers along the traveling direction of the material strip, wherein the pre-pressing rollers are used to roll the two sides of the material strip in the width direction into an arc shape with the concave arc side upward, and at this time, the two sides of the material strip in the width direction are lower than the middle of the material strip, and then the material strip is rolled by the multiple sets of forming rollers, so that the two sides of the material strip in the width direction are gradually deformed upward, and the cross-section of the material strip gradually becomes a circular tubular structure, until the two sides of the material strip in the width direction are aligned with each other; S2, external welding: welding the aligned two sides of the strip output from the primary roller press (a1) by means of a welding machine (a2); S3, secondary rolling: the material strip output from the welding machine (a2) is sent to the secondary rolling machine (a3), and the secondary rolling machine (a3) ​​is provided with a plurality of sets of shaping rollers and at least one set of correcting rollers along the moving direction of the material strip. The shaping rollers are used to gradually roll the cross-sectional shape of the material strip from a circular tube to a flat square tube structure, and the correcting rollers are used to correct the material strip of the flat square tube structure to ensure that the upper side wall and the lower side wall of the material strip are parallel, and the left side wall and the right side wall are parallel; S5, cutting: cutting the material strip output from the secondary roller press (a3) ​​into a preset length by a cutting machine (a4); S6, laser welding: insert at least two strip-shaped reinforcing ribs (2) into the inner hole of the cut material strip, the reinforcing ribs (2) are arranged parallel to the axial direction of the material strip, and the upper and lower ends of the reinforcing ribs (2) have bending parts (21), and multiple reinforcing ribs (2) are inserted into the interior of the flat square tubular structure at intervals along the left and right directions, and then the material strip is conveyed to the laser welder (a5), and the laser welder (a5) welds the upper and lower ends of the reinforcing ribs (2) to the upper side wall and the lower side wall of the flat square tubular structure respectively.

2. A forming method of a combined profile structure according to claim 1, characterized in that: The material of the material strip is ultra-high strength steel with a yield strength of ≥1000Mpa, a tensile strength of ≥1200Mpa, and an elongation after fracture of ≥9%.

3. A forming method of a combined profile structure according to claim 1 or 2, characterized in that: In step S6, the number of reinforcing ribs (2) is three.

4. The forming method of a combined profile structure according to claim 1, characterized in that: In step S2, the welding machine (a2) welds the aligned two sides of the material strip in the form of autogenous welding.

5. A combined profile structure, characterized in that: The invention comprises a main body (1) and at least two reinforcing ribs (2), wherein the main body (1) is formed by rolling a material strip to enclose a flat square tubular structure, wherein the upper side wall and the lower side wall of the flat square tubular structure are long sides, and the left side wall and the right side wall are short sides; the two side sides of the material strip are aligned in the middle of the upper side of the flat square tubular structure and then connected to each other by welding; the reinforcing ribs (2) are arranged parallel to the axial direction of the main body (1), and the upper and lower ends of the reinforcing ribs (2) both have a bending portion (21); a plurality of the reinforcing ribs (2) are inserted into the interior of the flat square tubular structure at intervals along the left-right direction, and the upper and lower ends of the reinforcing ribs (2) are respectively welded to the upper and lower side walls of the flat square tubular structure.

6. The combined profile structure according to claim 5, characterized in that: The material of the material strip is ultra-high strength steel with a yield strength of ≥1000Mpa, a tensile strength of ≥1200Mpa, and an elongation after fracture of ≥9%.

7. The combined profile structure according to claim 5 or 6, characterized in that: The number of the reinforcing ribs (2) is three.

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