Water heater end cover stretching process and stretching equipment thereof

Abstract

The invention discloses a water heater end cover stretching process and stretching equipment thereof, and belongs to the technical field of stretching dies. The water heater end cover stretching process comprises the following steps that S1, a plate is pre-stretched so that the plate can be bent towards one side; and S2, the pre-stretched plate is sequentially stretched and formed in a segmented mode. According to the stretching process for the end cover of the water heater, the plate is pre-stretched, then the pre-stretched plate is subjected to segmented stretching, the feeding angle is changed, the flowing mode of the material in a die cavity is changed, the stress state of the top face shape of the material is reduced, and therefore the instability problems of cracking and wrinkling of the material in the stretching process are solved; and the mold stability and the product forming stability in the production process are guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of stretching dies, and in particular relates to a water heater end cover stretching process and a stretching device thereof. Background Art

[0002] In the prior art, a water heater is a widely used household appliance. The water heater uses various physical principles to increase the temperature of cold water into hot water within a certain period of time. The shell of the water heater is the external protective structure of the water heater, ensuring the user's peace of mind and comfort during use.

[0003] For the shell of the water heater, the stretch forming method is usually used, that is, the mold is used to apply tension on the surface of the workpiece to cause plastic deformation of the workpiece, thereby changing the shape and size of the workpiece. Due to the large stretching height and inconsistent forming surface of the water heater end cover, the product is prone to wrinkling and cracking during stretching. In order to ensure the yield and forming effect of the product, secondary stretching is often required. Secondary stretching refers to further stretching treatment of the material or workpiece on the basis of the initial stretching. The principle is that through secondary stretching, the material or workpiece can undergo a deeper plastic deformation, thereby improving its physical properties, appearance quality or achieving specific shape requirements. However, secondary stretching affects production efficiency and causes cost waste. Therefore, designing a process that can improve production efficiency while ensuring that wrinkles and cracks do not occur during the stretching process is an urgent problem to be solved.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art. The purpose is to provide a water heater end cover stretching process, which solves the instability problems of material cracking and wrinkling during the stretching process by pre-stretching the sheet and then stretching the pre-stretched sheet in sections, while improving production efficiency.

[0006] Another object is to provide a water heater end cover stretching device.

[0007] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0008] A water heater end cover stretching process comprises the following steps:

[0009] S1, pre-stretching the sheet material so that the sheet material is bent to one side;

[0010] S2, stretching and forming the pre-stretched sheet material in sections one by one.

[0011] Further, in step S2, different sections of the pre-stretched and stretched part are stretched in sequence.

[0012] Further, in step S1, the sheet material is partially stretched to form a partial recess to form a bent structure;

[0013] In step S2, each bending section of the bending structure is stretched and formed in sequence;

[0014] Preferably, in step S1, the sheet material is pre-stretched to have at most two bends.

[0015] Further, in step S1, in step S2, the bent structure formed after the pre-stretching is stretched at least twice;

[0016] Preferably, the bent structure formed after pre-stretching is stretched in different directions at least twice.

[0017] Further, in step S2, the pre-stretched sheet material is subjected to segmented stretching forming, including:

[0018] Vertical stretching, used for vertical stretching of any section of the pre-stretched bending structure

[0019] Transverse stretching is used to perform transverse stretching on any section of the pre-stretched bending structure.

[0020] Furthermore, the pre-stretched sheet material is divided into a first transverse section, a drawing section and a second transverse section in sequence, and the drawing section and the second transverse section are the bending structures after pre-stretching;

[0021] In step S2, the second transverse section is at least partially stretched vertically, and the drawing section is at least partially stretched transversely.

[0022] Further, in step S2, in the transverse stretching, the drawing section is transversely stretched so that the stretching section moves transversely toward the direction close to the first transverse section;

[0023] Preferably, during the transverse stretching process, the drawing section is moved transversely as a whole to stretch the length of the drawing section.

[0024] Further, in step S2, during the transverse stretching process, the drawing section is divided into a first section close to the first transverse section and a second section close to the second transverse section;

[0025] The first section moves laterally in a direction approaching the first transverse section, and the second section moves laterally in a direction away from the first transverse section.

[0026] Further, in step S2, during vertical stretching, the second transverse segment is stretched, and an end of the second transverse segment close to the drawing segment or an end away from the drawing segment forms a vertical surface.

[0027] The present invention also provides a water heater end cover stretching device, which adopts the above-mentioned stretching process.

[0028] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0029] 1. The water heater end cover stretching process of the present invention pre-stretches the material and changes the feeding angle to solve the instability problem of material cracking and wrinkling during the stretching process, thereby ensuring the mold stability during the production process.

[0030] 2. The water heater end cover stretching process of the present invention pre-stretches the top surface, pre-deforms the material on the top surface, changes the flow pattern of the material in the mold cavity, reduces the stress state of the top surface shape, and ultimately solves the problems of stretching cracking and wrinkling.

[0031] 3. The water heater end cover stretching process of the present invention divides the forming process of the end cover into pre-stretching, vertical surface forming and final stretching forming. The stretching process forms a partially floating stretching forming structure, thereby improving the forming stability of the stretched product.

[0032] At the same time, the invention has a simple structure, a concise method, and a significant effect, and is suitable for popularization and use.

[0033] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are part of the present invention and 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, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0035] Figure 1 is a flow chart of the water heater end cover stretching process of the present invention;

[0036] Figure 2 It is a schematic diagram of the structure of the sheet material after pre-stretching of the present invention;

[0037] Figure 3 It is a schematic diagram of the structure of the sheet material after segmented stretching of the present invention;

[0038] Figure 4 It is a schematic diagram of the final forming result of the sheet material of the present invention;

[0039] Figure 5 It is a schematic diagram of the stretching device of the present invention in the mold opening state;

[0040] Figure 6is a schematic diagram of the stretching device of the present invention when pressing a sheet material;

[0041] Figure 7 is a schematic diagram of the stretching device of the present invention during pre-stretching;

[0042] Figure 8 is a schematic diagram of the stretching device of the present invention when stretching a vertical surface;

[0043] Fig. 9 It is a schematic diagram of the stretching equipment of the present invention during the final stretching forming.

[0044] In the figure: 1, sheet; 101, first transverse section; 102, drawing section; 1021, first section; 1022, second section; 103, second transverse section; 2, upper pressure ring; 3, lower pressure ring; 4, upper stripping plate; 5, movable lower template; 6, fixed lower template.

[0045] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0047] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0048] 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 an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The end cover of the water heater is a protective structure of the water heater, and is usually made of metal. Since the shapes of the end covers of the water heaters are different and the molding surfaces are inconsistent, a stretching molding method is usually used. In order to ensure the yield and molding effect of the product, secondary stretching is often required. However, the process method of secondary stretching affects the production efficiency. In order to solve the above problems, the present invention proposes a water heater end cover stretching process, which improves the production efficiency by adding pre-stretching during the stretching process, and at the same time can solve the instability problem of material cracking and wrinkling during the stretching process.

[0050] like Figures 1 to 9 As shown, the water heater end cover stretching process of the present invention comprises the following steps:

[0051] S1, pre-stretching the sheet material 1 so that the sheet material 1 is bent to one side;

[0052] S2, stretching and forming the pre-stretched sheet material 1 in sections one by one.

[0053] The sheet material 1 is pre-stretched to bend to one side, and then the pre-stretched sheet material 1 is stretched in sections in sequence to finally form the desired product. Pre-stretching occurs at the early stage of forming the sheet material 1. Pre-stretching reduces the deformation of the sheet material 1, changes the flow mode of the sheet material 1, increases the fluidity of the sheet material 1, makes the structure of the sheet material 1 more stable during the stretching process, and avoids the problem of cracking and wrinkling of the sheet material 1 during the stretching process. The number of sections can be determined according to the actual situation, which can be one, two or more times.

[0054] In this embodiment, in step S1, the sheet material 1 is partially stretched to form a partial recess to form a bending structure, thereby forming a cavity. During the stretching process, the sheet material 1 is partially stretched to bend a portion of the sheet material 1, thereby forming a cavity. After the pre-stretching, the sheet material 1 has the contour shape of the water heater end cover.

[0055] In step S2, the sheet material 1 is pre-stretched to bend at most twice to form a bending structure, and different sections of the stretched part after pre-stretching are stretched respectively. Specifically, each section of the bending structure formed after pre-stretching is stretched and formed in sequence. After pre-stretching, the bending structure is further stretched to a more specific and detailed structure, thereby realizing the forming of the product. The number of bends can be one or two.

[0056] Specifically, the pre-stretched sheet material 1 is divided into a first transverse section 101, a drawing section 102, and a second transverse section 103 in sequence, and the drawing section 102 and the second transverse section 103 are the bending structures after pre-stretching. During the pre-stretching process, part of the sheet material 1 is bent in the vertical direction to form the drawing section 102, and part of the drawing section 102 is then bent transversely at a certain angle to form the second transverse section 103. Of course, depending on the different forming surfaces of the product, the bending angles between the first transverse section 101 and the drawing section 102, and the bending angles between the second transverse section 103 and the drawing section 102 can be the same or different, and the corresponding bending angles can be adjusted according to actual conditions.

[0057] In this embodiment, by pre-stretching the sheet material 1, the sheet material 1 is divided into at least three sections, namely, the first transverse section 101, the drawing section 102 and the second transverse section 103, to form a stepped pre-molding structure, which changes the overall stress of the sheet material 1 and makes the stress more uniform. Then, according to the work requirements, each corresponding section is stretched again. Due to the existence of pre-stretching, the forming process of the sheet material 1 is a gradual process, the deformation amount changes less, and the feeding angle is changed, which improves the stability of the forming.

[0058] In this embodiment, the sheet material 1 is stretched to form the water heater end cover. During the forming process, the top of the water heater end cover is formed first, and then further stretched and formed, so that the resistance of the forming fillet of the top of the water heater end cover is the largest, resulting in the sheet material 1 at the top of the water heater end cover being easily torn by force. By adding pre-stretching, the sheet material 1 at the top of the water heater end cover is pre-stretched, so that the sheet material 1 at the top of the water heater end cover is pre-deformed, the flow mode of the sheet material 1 in the mold cavity is changed, and the stress state of the sheet material 1 at the top of the water heater end cover is reduced, thereby reducing the possibility of cracking and wrinkling of the sheet material 1.

[0059] In step S1, during the pre-stretching process, the sheet 1 is bent at most twice. During the pre-stretching process, the number of bends is reduced, and the stress on the sheet 1 is reduced while the sheet 1 is pre-deformed. Through pre-stretching, the sheet 1 is changed from a flat sheet 1 to a bent sheet 1. By reducing the number of bends from multiple times to at most two times (the bend between the first transverse section 101 and the drawing section 102, and the bend between the second transverse section 103 and the drawing section 102) at the initial stage of forming, the mold stability during the production process is improved. In this embodiment, the bending angle is different according to the different required product forming surfaces.

[0060] In this embodiment, the direction in which the first transverse section 101 moves toward the second transverse section 103 is defined as the direction from top to bottom, that is, the upper surface of the first transverse section 101 is the top surface of the water heater end cover. Since the sheet 1 is stretched from top to bottom, the force on the top surface is the greatest, especially the bend between the first transverse section 101 and the drawing section 102 is prone to cracking and other instability problems. Through pre-stretching, the sheet 1 at the top surface is pre-deformed to reduce the force on the top surface. In the subsequent stretching process, the fluidity of the material can be increased, and the resistance to the flow of the molding surface material is reduced, thereby reducing the possibility of cracking and other instability problems during the stretching process.

[0061] In this embodiment, in step S1, during the pre-stretching process, some sections of the sheet material 1 move inward to form a stepped structure, that is, the bending angle between the first transverse section 101 and the drawing section 102, and the bending angle between the drawing section 102 and the second transverse section 103. In this way, there is a gap between the first transverse section 101 and the second transverse section 103, and the flat sheet material 1 is stretched into a sheet material 1 with a certain width. Through pre-stretching, the first transverse section 101 forms the top surface of the water heater end cover, and the drawing section 102 and the second transverse section 103 form the side wall of the water heater end cover, which has a preliminary outline of the water heater end cover, and lays a good foundation for subsequent stretching.

[0062] In this embodiment, the bend between the first transverse section 101 and the drawing section 102 is preferably rounded, and the bend between the drawing section 102 and the second transverse section 103 is also preferably rounded to avoid vertical bending and protect the sheet 1. The rounded transition can reduce stress concentration, effectively disperse stress, and evenly distribute stress on the sheet 1, thereby reducing the risk of cracking. The rounded design can also increase the ductility of the parts, so that they can better adapt to various deformation and stretching requirements. The rounded transition can also make the material flow more evenly during the stretching process, reduce the occurrence of defects such as wrinkles and cracks, and improve processing quality and efficiency.

[0063] In this embodiment, the first transverse section 101 serves as the top surface of the water heater end cover. The top surface of the water heater end cover varies according to different products. The stretched shape of the first transverse section 101 can be adjusted, and can be a plane, an arc, or other shapes. When the top surface is non-planar, further stretching is performed according to actual conditions. Of course, other operations such as drilling can also be performed.

[0064] Further, in step S2, the bent structure formed after pre-stretching is stretched at least twice. More preferably, the bent structure formed after pre-stretching is stretched at least twice in different directions.

[0065] Specifically, the pre-stretched sheet material 1 is subjected to segmented stretching and forming, including:

[0066] Transverse stretching is used to transversely stretch any section of the pre-stretched bending structure;

[0067] Vertical stretching is used to vertically stretch any section of the pre-stretched bending structure.

[0068] After the pre-stretching is completed, the pre-stretched sheet 1 is stretched in sections to further solve the instability problem of material cracking and wrinkling during the stretching process and ensure the stability of the mold during the production process. Among them, any section is determined according to the product structure, and the specific structure determines which specific section needs to be stretched horizontally or vertically.

[0069] In this embodiment, at least part of the second transverse section 103 is vertically stretched, and at least part of the drawing section 102 is transversely stretched. According to work requirements, the second transverse section 103 and the drawing section 102 are stretched respectively, so that the sheet material 1 changes both in the transverse direction and in the vertical direction to achieve final forming.

[0070] In this embodiment, in step S2, during the vertical stretching, the second transverse section 103 is stretched, and a vertical surface is formed at one end of the second transverse section close to the drawing section or at one end away from the drawing section. According to actual conditions, the second transverse section 103 can be stretched into a vertical surface in its entirety or in part, specifically, at one end close to the drawing section 102 or at one end away from the drawing section 102.

[0071] In this embodiment, taking the end cover of the water heater as an example, after the pre-stretching is completed, the first transverse section 101 as the top surface of the end cover is no longer stretched, and the drawing section 102 and the second transverse section 103 are further stretched. On the basis of the pre-stretching, the second transverse section 103 is stretched, and a vertical surface is formed on the basis of the drawing section 102, thereby further increasing the width of the end cover of the water heater.

[0072] Specifically, the second transverse section 103 rotates around the bending point of the drawing section 102 and the second transverse section 103 until the second transverse section 103 becomes vertical, and according to the actual situation, the appropriate vertical surface length is determined, and the second transverse section 103 is bent again, so that part of the second transverse section 103 changes from the vertical state to the transverse state again, that is, the second transverse section 103 is divided into two parts, one part is a vertical section, and the other part is a transverse section, and a certain bending angle is formed between the vertical section and the transverse section. According to different forming surfaces, the second transverse section 103 can be stretched multiple times to form multiple bending angles.

[0073] In this embodiment, during the transverse stretching process, the drawing section 102 is stretched to move the drawing section 102 transversely toward the side close to the unstretched sheet material 1. During the transverse stretching process, the drawing section 102 is moved transversely as a whole to stretch the length of the drawing section 102.

[0074] In this embodiment, during the transverse stretching process, the drawing section 102 is divided into a first section 1021 and a second section 1022, the first section 1021 is close to the first transverse section 101, and the second section 1022 is close to the second transverse section 103; the first section 1021 moves laterally in a direction close to the first transverse section 101, and the second section 1022 moves laterally in a direction away from the first transverse section 101.

[0075] The part of the sheet material 1 near one end of the drawing section 102 of the second transverse section 103 is moved in a direction away from the first transverse section 101, so that the drawing section 102 becomes longer. By transversely stretching the drawing section 102, the drawing section 102 moves from the first position to the second position. Specifically, there is a certain distance between the drawing section 102 after pre-stretching and the drawing section 102 after transverse stretching. Through transverse stretching, the drawing section 102 moves inward, the sheet material 1 at the drawing section 102 is retracted, and the tensile stress of the drawing section 102 is reduced, so that the drawing section 102 can be stretched later.

[0076] By stretching the drawing section 102 and the second transverse section 103 respectively, the transverse and vertical working requirements are met. In this embodiment, there is no limitation on the order of transverse stretching and vertical stretching, and the order of transverse stretching and vertical stretching is determined according to actual conditions. Of course, in some special cases, only one of transverse stretching and vertical stretching needs to be selected.

[0077] The water heater end cover stretching process of the present invention pre-stretches the sheet material 1 and then stretches the pre-stretched sheet material 1 in sections, thereby solving the instability problem of material cracking and wrinkling during the stretching process, ensuring the mold stability during the production process, and improving production efficiency.

[0078] The present invention also provides a water heater end cover stretching device, which adopts the above-mentioned stretching process. The water heater end cover stretching device can be a stretching hydraulic press. In this embodiment, the stretching hydraulic press is used as an example to further explain the stretching forming process of the water heater end cover.

[0079] The hydraulic stretching press mainly includes hydraulic drive components, hydraulic control system and stretching die.

[0080] The hydraulic drive parts include hydraulic cylinders and hydraulic pumps. The hydraulic cylinder is one of the core components of the stretching hydraulic press. It is responsible for converting hydraulic energy into mechanical energy to generate stretching force. The hydraulic pump provides high-pressure hydraulic oil to the hydraulic cylinder and is the power source of the hydraulic transmission system. The performance of the hydraulic pump directly affects the stretching capacity and stability of the stretching machine.

[0081] The hydraulic control system is responsible for controlling the flow direction and pressure of the hydraulic oil, thereby achieving precise control of the stretching process. The hydraulic control system includes various valves, pipes, sensors and other components to ensure that the hydraulic oil can flow and be distributed according to the predetermined program.

[0082] The drawing die is a part of the hydraulic drawing press used to form the workpiece. It is designed according to the shape and size of the workpiece to ensure that the workpiece obtains the required shape and accuracy during the drawing process. The drawing die is usually made of high-strength and high-hardness materials to withstand the high stress and friction generated during the drawing process.

[0083] The stretching hydraulic press also includes an upper edge pressing ring 2 and a lower edge pressing ring 3. When the film is closed, the upper edge pressing ring 2 and the lower edge pressing ring 3 press the sheet material 1 from the upper side and the lower side respectively to play a fixing role.

[0084] Furthermore, the drawing die usually includes an upper die, a lower die and a tie rod, wherein the upper die is located above the die and is used to apply pressure to pull the sheet 1 into the die. The lower die is located below the die and is used to support the sheet 1 and provide the shape required for drawing. The tie rod is used to connect the upper die and the lower die to ensure the stability of the die during the drawing process.

[0085] The upper die comprises a die handle, an upper die plate, an upper stripping plate 4, a punch fixing plate and a punch.

[0086] The die handle is a key component connecting the upper die and the hydraulic drive component. The die handle bears the weight of the entire upper die and the impact force generated during the stretching process.

[0087] The upper mold plate is the base of the upper mold, which is used to install and fix other components, such as punch fixing plate, punch, etc. The upper mold plate has sufficient rigidity and strength to support these components and ensure that they are not deformed during the stamping process.

[0088] The punch fixing plate is used to install and fix the punch to ensure the stability and accuracy of the punch during the stamping process.

[0089] The punch is one of the core components of the drawing die, and its shape determines the outer contour of the stamped part. During the stamping process, it descends into the die, causing the material to undergo plastic deformation, thus obtaining a product of the desired shape.

[0090] The main function of the upper stripping plate 4 is to smoothly remove the product from the mold cavity after stamping or stretching. This ensures the integrity and dimensional accuracy of the product and also helps with the maintenance and care of the mold.

[0091] The lower die mainly includes a lower die base, a lower mold plate and a concave die.

[0092] The lower die base is the basic supporting part of the lower die and is usually a solid base used to install and support other lower die components.

[0093] The die is the most important part of the die, used to shape the stamping material. The shape and size of the die determine the shape and size of the final product.

[0094] The lower mold plate is divided into two types: a fixed lower mold plate 6 and a movable lower mold plate 5. The fixed lower mold plate 6 is a relatively static part of the mold and is usually installed on the lower mold base. The fixed lower mold plate 6 is usually made of high-strength material and can withstand large punching or injection pressure to ensure the durability and reliability of the mold. The fixed lower mold plate 6 provides a stable support and positioning reference to ensure that the mold maintains a precise position and shape during the punching or injection process.

[0095] The movable lower template 5 is a movable part in the mold, which is usually connected to a hydraulic drive component and has high flexibility and can adapt to different production requirements and product specifications.

[0096] In this embodiment, the whole process of processing the sheet material 1 by the stretching hydraulic press is further described.

[0097] The first step is to adjust the water heater end cover stretching equipment to the mold opening state. In the mold opening state, each template is reset to facilitate the placement of the sheet 1.

[0098] In the second step, the mold moves downward, and the upper pressure ring 2 of the water heater end cover stretching equipment and the lower pressure ring 3 of the water heater end cover stretching equipment press the sheet material 1 from the upper side and the lower side respectively.

[0099] In the third step, the mold moves downward, and the upper stripping plate 4 of the water heater end cover stretching equipment contacts the movable lower template 5 of the water heater end cover stretching equipment for pre-stretching.

[0100] In the fourth step, the mold moves downward, the upper stripping plate 4 of the water heater end cover stretching device is reset, and the upper mold of the water heater end cover stretching device is adjusted to the limit position, that is, the vertical surface is stretched. The limit position refers to the upper mold descending to fit closely with the lower mold.

[0101] In the fifth step, the mold moves downward, the upper stripping plate 4 of the water heater end cover stretching equipment contacts the fixed lower template 6 of the water heater end cover stretching equipment to stretch out the top shape, the movable lower template 5 of the water heater end cover stretching equipment is reset, the mold is closed, and finally the desired product is stretched and formed.

[0102] The water heater end cover stretching process of the present invention pre-stretches the sheet material 1, then stretches the pre-stretched sheet material 1 in sections, and finally forms it through transverse stretching and vertical stretching, thereby solving the instability problem of material cracking and wrinkling during the stretching process, ensuring the mold stability during the production process, and improving production efficiency.

[0103] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. A water heater end cover stretching process, characterized in that: The following steps are involved: S1, pre-stretching the sheet material (1) so that the sheet material (1) is bent toward one side; S2, stretching and forming the pre-stretched sheet material (1) in sections one by one.

2. The water heater end cover stretching process according to claim 1, characterized in that: In step S2, different sections of the pre-stretched and stretched part are stretched in sequence.

3. The water heater end cover stretching process according to any one of claims 1-2, characterized in that: In step S1, the sheet material (1) is partially stretched to form a partial recess to form a bent structure; In step S2, each bending section of the bending structure is stretched and formed in sequence; Preferably, in step S1, the sheet material (1) is pre-stretched to allow at most two bends to occur.

4. The water heater end cover stretching process according to claim 3, characterized in that: In step S2, the bent structure formed after pre-stretching is stretched at least twice; Preferably, the bent structure formed after pre-stretching is stretched in different directions at least twice.

5. The water heater end cover stretching process according to any one of claims 3-4, characterized in that: In step S2, the pre-stretched sheet material (1) is subjected to segmented stretching forming, including: Vertical stretching, used for vertical stretching of any section of the pre-stretched bending structure Transverse stretching is used to perform transverse stretching on any section of the pre-stretched bending structure.

6. The water heater end cover stretching process according to claim 5, characterized in that: The pre-stretched sheet material (1) is divided into a first transverse section (101), a drawing section (102) and a second transverse section (103) in sequence, and the drawing section (102) and the second transverse section (103) are pre-stretched bending structures; In step S2, the second transverse section (103) is at least partially stretched vertically, and the drawing section (102) is at least partially stretched transversely.

7. The water heater end cover stretching process according to claim 6, characterized in that: In step S2, during transverse stretching, the drawing section (102) is transversely stretched so that the drawing section (102) moves transversely in a direction close to the first transverse section (101); Preferably, during the transverse stretching process, the drawing section (102) is moved transversely as a whole to stretch the length of the drawing section (102).

8. The water heater end cover stretching process according to any one of claims 6-7, characterized in that: In step S2, during the transverse stretching process, the drawing section (102) is divided into a first section (1021) close to the first transverse section (101) and a second section (1022) close to the second transverse section (103); The first section (1021) moves laterally in a direction approaching the first transverse section (101), and the second section (1022) moves laterally in a direction away from the first transverse section (101).

9. The water heater end cover stretching process according to any one of claims 6 to 8, characterized in that: In step S2, during vertical stretching, the second transverse section (103) is stretched, and an end of the second transverse section close to the drawing section (102) or an end away from the drawing section (102) forms a vertical surface.

10. A water heater end cover stretching device, characterized in that: The stretching process according to any one of claims 1 to 9 is adopted.

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