A chair leg forming process

Abstract

A chair leg forming process comprises sequentially a cutting process, a stamping forming process and a spraying process, a support inner bone is arranged in the support part, two ends of the support inner bone are fixedly connected with the shaft sleeve and the roller seat, when the chair leg bears, the support inner bone is used to replace the support part to bear the shearing force, the structural strength of the support inner bone is higher, thus the bending deformation or even cracking of the connecting part of the chair leg body can be avoided, the structural stability is improved, and the aesthetic appearance is ensured; the connecting lug is arranged on the support inner bone, after the support inner bone is connected between the shaft sleeve and the roller seat, the shearing force borne by the support inner bone is transmitted to the support part through the connecting lug, the burden of the support inner bone is reduced, the structural stability is further improved, meanwhile, the connecting lug on the two sides of the support inner bone can pull the two side edges of the support part from the inside, so that the support part can keep the structural integrity and deformation is avoided.

Description

Technical Field

[0001] This invention relates to the field of chair leg manufacturing technology, and more specifically to a chair leg forming process. Background Technology

[0002] The applicant previously filed and disclosed a Chinese invention patent for a molding process of an integrally molded chair leg, patent application number CN202211288191.7. This patent includes, in sequence, a sheet metal cutting process and a stamping process. The sheet metal cutting process involves processing and cutting a metal sheet using sheet metal cutting equipment to produce a first metal sheet. The stamping process includes a chair leg stamping process, in which the first metal sheet is stamped and bent using stamping equipment, forming the chair leg body. Composed of a fixed base, multiple legs distributed around the outer perimeter of the fixed base, and arc-shaped constrictions bent downwards at the ends of the legs, the fixed base, multiple legs, and arc-shaped constrictions are integrally formed. In the body of the chair legs, the cross-section of the multiple legs is a "∩" shaped structure, and there are reinforcing ribs bent inwards at the bottom edge of the structure. This structure can provide a certain support strength, improve the stability of the chair, and adopts an integral stamping process of stamping and bending a first metal plate to form the fixed base and multiple legs. It has the advantages of high production efficiency, good production quality, and low production cost, and is suitable for widespread promotion.

[0003] However, it was found during use that, due to the distance between the contact point on the outer side of the support leg and the connection point on the inner side of the chair base, when the chair base is under load, the connection point between the support leg and the chair base support will be subjected to a large shear force. After long-term use, this shear force will cause the connection point of the support leg and chair base to bend and deform, or even crack, thus affecting the appearance and normal use. Therefore, it is necessary to improve the structure of the chair base. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a chair leg molding process.

[0005] The technical solution adopted by this invention to solve its technical problem is: A chair leg forming process, including Step 1 - Cutting process: The cutting process uses a stamping machine to cut out a metal template in the shape of a chair leg. The metal template includes a center plate located in the middle and multiple extension plates extending to the periphery of the center plate. Step 2 - Stamping process: The stamping process uses a stamping machine to process the metal template into a chair base body. The chair base body includes a fixed part located at the center, multiple support parts extending around the fixed part, and an installation part located at the extended end of the support parts. The process includes a welding step, which involves welding structural components to the inside of the chair leg body to improve structural strength, resulting in a semi-finished chair leg. Step 3 - Spraying process, wherein the spraying process involves spraying an anti-rust layer onto the surface of the semi-finished chair legs to obtain the finished chair legs; The structural component includes a bushing welded to the center of the fixed part, a roller seat welded to the mounting part, and a support inner bone welded to the support part. The two sides of the support inner bone are connected to the inner side of the support part, and the two ends of the support inner bone are fixedly connected to the bushing and the roller seat, respectively.

[0006] In this invention, at least one set of outwardly folded connecting ears are provided on both sides of the inner supporting bone, and the inner supporting bone is connected to the inner side of the supporting part through the connecting ears.

[0007] Furthermore, the connecting ears on both sides of the supporting inner bone are symmetrical to each other; the fixing part, the supporting part and the mounting part are integrally formed.

[0008] In this invention, the stamping process specifically includes the following steps: Step I - Stretching: The metal template is stamped and stretched according to the outline of the chair leg mold using a stamping press to obtain a chair leg blank. After stamping, the stamping press is held in the stamping state for 3-4 seconds. Step II - Edge trimming: Use a stamping machine to vertically cut off the excess sheet material at the edges of the fixed and supporting parts of the chair leg blank, retaining the sheet material at the extended end of the supporting part; Step III - Shaping: The sheet metal retained at the extended end of the support section is pressed down and shaped using a stamping press; Step IV - Side trimming ①: Trim and trim the skirt edges of the mounting and fixing parts on the chair leg blank using a stamping machine; Step V - Side trimming ②: Trim the skirt edge of the support part on the chair leg blank using a stamping machine; Step VI - Edge pressing: The burrs on the edge of the chair leg blank are pressed and flattened by stamping to obtain the semi-finished chair leg body. When the stamping machine presses down, a downward pressure of 300-450N is applied to the chair leg blank and lasts for 5-10 seconds.

[0009] Furthermore, the center plate has a central hole punched in the center, the center plate between two adjacent sets of extension plates on the metal template is stretched and bent downward to form the fixing part, the two sides of the extension plate are stretched and bent downward to form the supporting part; the plate material at the extension end of the extension plate is pressed down and shaped to form the mounting part.

[0010] Furthermore, the skirt of the support portion has an arc-shaped profile.

[0011] Furthermore, the cross-section of the support portion is a "∩" shaped structure.

[0012] Furthermore, in step VI - pressing step, the chair leg mold is provided with an extrusion groove for the skirt edge to extend into. The width of the extrusion groove is equal to the thickness of the skirt edge, and the skirt edge extends into the extrusion groove with its bottom surface abutting against the bottom of the extrusion groove.

[0013] In this invention, the spraying process specifically includes the following steps: Step I - Sanding: The semi-finished chair legs are sanded and repaired manually. Step II - Sandblasting: Place the semi-finished chair legs into the sandblasting room for sandblasting treatment; Step III - Spray Painting: The semi-finished chair legs are sprayed with electrostatic powder coating to obtain the finished chair legs.

[0014] The present invention has the following advantages and beneficial effects: An inner support frame is installed inside the support section. The two ends of the inner support frame are fixedly connected to the bushing and roller seat. When the chair leg is under load, the inner support frame replaces the support section in bearing the shear force. The inner support frame has higher structural strength, thus avoiding bending deformation or even cracking at the connection of the chair leg body, improving structural stability while ensuring aesthetics.

[0015] Connecting ears are provided on the inner support bone. After the inner support bone is connected between the bushing and the roller seat, a small part of the shear force borne by the inner support bone will be transferred to the support part through the connecting ears, reducing the burden on the inner support bone and further improving the structural stability. At the same time, the connecting ears on both sides of the inner support bone can pull the two sides of the support part from the inside, so that the support part can maintain the structural integrity and avoid deformation. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the metal template being processed into the chair base in this embodiment; Figure 2 This is a schematic diagram of the semi-finished chair legs in this embodiment; Figure 3 This is a schematic diagram of the installation of the structural components in this embodiment; Figure 4 This is a process flow diagram of the stamping process in this embodiment; Figure 5 This is a side view of the support portion of the semi-finished chair leg in this embodiment; Figure 6 for Figure 5 AA section view in the middle; Figure 7 This is a schematic diagram of the extrusion groove in this embodiment. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0018] like Figures 1 to 7 As shown, this embodiment discloses a chair leg forming process, including step one - the blanking process, in which a metal template 1 in the shape of a chair leg is punched out from a flattened steel coil by a stamping machine. The metal template 1 includes a central plate 10 located in the middle and a plurality of extension plates 11 extending to the periphery of the central plate 10. The process includes a stamping process, in which a metal template 1 in the shape of a chair leg is processed into a chair leg body 2 by a stamping machine. The chair leg body 2 includes a fixing part 20 located at the center, a plurality of supporting parts 21 extending around the fixing part 20, and an mounting part 22 located at the extended end of the supporting parts 21. The fixing part 20, the supporting parts 21 and the mounting part 22 are integrally formed. Step 2 - Welding process, which includes welding structural components 3 to improve structural strength inside the chair leg body 2 to obtain the chair leg semi-finished product 4; Step 3 - Spraying process, wherein the spraying process is to spray an anti-rust layer onto the surface of the chair leg semi-finished product 4 to obtain the finished chair leg; Specifically, the structural component 3 includes a bushing 30 welded to the center of the fixing part 20 for mounting a pneumatic rod, a roller seat 31 welded inside the mounting part 22 for inserting a roller, and a support inner bone 32 welded inside the support part 21 for improving the strength of the support part 21. The two sides of the support inner bone 32 are connected to the inner side of the support part 21, and the two ends of the support inner bone 32 are fixedly connected to the bushing 30 and the roller seat 31 respectively by welding. Preferably, the basic structure of the chair leg body 2 can refer to the chair leg body 2 mentioned in the applicant's previous application for a high-strength chair leg structure, patent application number CN202223214066.X. However, the difference is that in the chair leg body 2 described in this embodiment, at least one set of outwardly folded connecting ears 320 are provided on both sides of the inner support bone 32. In this embodiment, two sets are preferred. The inner support bone 32 is connected to the inner side of the support part 21 through the connecting ears 320. At the same time, the connecting ears 320 on both sides of the inner support bone 32 are symmetrical to each other. When the inner support bone 32 is connected between the bushing 30 and the roller seat 31, the shear force borne by the inner support bone 32 will be transferred to the support part 21 through the connecting ears 320, reducing the burden on the inner support bone 32 and improving structural stability. At the same time, the connecting ears 320 on both sides of the inner support bone 32 can pull the two sides of the support part 21 from the inside, so that the support part 21 can maintain structural stability and avoid deformation.

[0019] In this embodiment, the stamping process specifically includes the following steps: Step I - Stretching: The metal template 1, shaped like a chair leg, is placed on a stamping machine. The stamping machine is equipped with a chair leg shape mold. During stamping, the metal template 1 is stamped and stretched according to the outline of the chair leg shape mold to obtain a chair leg blank. Specifically, the center plate 10 between two adjacent sets of extension plates 11 on the metal template 1 is stretched and bent downward to form the fixing part 20. After being stretched and bent, the center plate 10 forms an inverted bowl-shaped structure. At the same time, a center hole is punched in the center of the center plate 10 for inserting a gas spring. During stamping, the two sides of the extension plates 11 are also stretched and bent downward to form the support part 21. The cross-section of the support part 21 is a "∩" shaped structure. In addition, during stamping and stretching, the metal template 1 is stretched, which will generate internal friction and deformation energy. This energy will be converted into heat energy, causing the temperature of the metal template 1 to rise. This temperature rise will cause stress deformation in the metal template 1, which will affect the shape and structure of the chair leg blank. In order to avoid this phenomenon, the stamping machine needs to maintain the stamping state for 3-4 seconds after stamping so that the stretched chair leg blank can maintain the stretched state. After cooling, a chair leg blank with a stable structure can be obtained. Stretch forming can improve the consistency of the chair leg body 2 and ensure the integrity of the structure. Step II - Edge Trimming: In the stretching step described above, after the center plate 10 and the extension plate 11 are stretched and bent, the remaining sheet material will be exposed. At this time, it is necessary to retain the useful sheet material and cut off the useless sheet material. Specifically, the excess sheet material at the edges of the fixed part 20 and the support part 21 in the chair leg blank is cut vertically downwards using a stamping machine, while the sheet material at the extension end of the support part 21 is retained. In addition, while cutting vertically downwards, the chair leg blank also needs to be shaped and corrected according to the outline of the chair leg to avoid stress deformation after the excess sheet material is cut off. Step III - Shaping: This step mainly involves pressing down and shaping the sheet material retained at the extended end edge of the support part 21 in Step II. After pressing down and shaping, the sheet material in this part extends vertically downward to form the mounting part 22. Similarly, during the pressing down and shaping process, the shape of the chair leg blank needs to be corrected and shaped to ensure the integrity of the chair leg blank. Step IV - Side Trimming ①: This step mainly involves trimming the skirt edges of the mounting part 22 and the fixing part 20 on the chair leg blank using a stamping machine. Specifically, a pre-designed chair leg shape mold is installed on the stamping machine, and then the chair leg blank is placed on the chair leg shape mold. During stamping, the pressure head above the stamping machine presses the chair leg blank downward and fastens it onto the chair leg shape mold. Then, the cutter set on the stamping machine performs horizontal cutting on the skirt edges of the mounting part 22 and the fixing part 20 according to the outline of the chair leg shape mold. Inverting the chair leg blank onto the chair leg shape mold can shape the outline of the chair leg blank to a certain extent, and can also avoid deformation during cutting, ensuring the structural integrity of the chair leg blank. Step V - Side Trimming ②: Since two sets of cutting blades for cutting the mounting part 22 and the fixing part 20 have been installed on the stamping machine in Step III, and the two sets of cutting blades are installed close to each other, in order to avoid interference, an additional cutting blade for cutting the support part 21 is required. Therefore, this step mainly trims the skirt of the support part 21 on the chair leg blank by using the stamping machine. Specifically, a designed chair leg shape mold is installed on the stamping machine, and then the chair leg blank is placed on the chair leg shape mold. During stamping, the pressure head above the stamping presses the chair leg blank downward and fastens it to the chair leg shape mold. Then, the cutting blade set on the stamping machine horizontally cuts the skirt of the support part 21 according to the outline of the chair leg shape mold. Preferably, the cutting blade in this step has a certain curvature. After cutting, the support part 21 of the chair leg blank has a curved skirt, which increases the aesthetics. Step VI - Edge Pressing: After the edge trimming in Steps IV and V, burrs will be generated at the edges of the skirts of the fixing part 20, the support part 21, and the mounting part 22. These burrs will affect subsequent processing and therefore need to be removed. This step mainly uses extrusion to flatten the burrs at the edges of the chair leg blank to obtain the semi-finished chair leg body 2. Specifically, a designed chair leg shape mold is installed on a stamping machine. The chair leg shape mold is provided with an extrusion groove 5 for the skirt to extend into. The width of the extrusion groove 5 is equal to the skirt thickness of the chair leg blank. During stamping, the stamping machine presses the chair leg blank downward and fastens it onto the chair leg shape mold. At the same time, the skirt on the chair leg blank extends into the extrusion groove 5 and the bottom surface of the skirt abuts against the extrusion groove 5. At the bottom of the groove 5, during the continuous pressing of the chair leg blank by the stamping machine, the burrs on the skirt edge are squeezed and flattened in one go. When the stamping machine presses down, it applies a downward pressure of 300-450N to the chair leg blank for 5-10 seconds. In this embodiment, it is preferably 400N for 10 seconds. This downward pressure mainly acts on the support part 21 of the "∩" shaped structure and the fixing part 20 of the inverted bowl-shaped structure. If the downward pressure is too small, the burrs cannot be completely flattened, resulting in poor edge pressing effect. If the pressure is too large, it will affect the overall thickness of the chair leg blank or even cause the chair leg blank to deform. This method of removing burrs by squeezing and flattening is faster and more convenient than the method of removing burrs by grinding, which improves production efficiency.

[0020] In this embodiment, after obtaining the semi-finished chair leg 4 through the welding process, it enters the spraying process. However, during the welding process, the chair leg body 2 will undergo local deformation due to welding, especially at the mounting part 22. Since the chair leg body 2 after the welding process has internal structural components 3, it cannot be corrected and shaped by molds as in the stamping process. Therefore, the chair leg body 2 can only be polished by grinding. The spraying process specifically includes the following steps: Step I - Polishing: The chair leg semi-finished product 4 is polished and repaired manually to make the outline of the chair leg semi-finished product 4 smoother and improve its appearance. Step II - Sandblasting: The semi-finished chair leg 4 is placed in the sandblasting room for sandblasting treatment to remove dirt, rust, coating and other attachments on the surface of the semi-finished chair leg 4. At the same time, it increases the surface roughness of the semi-finished chair leg 4 and increases the adhesion. Sandblasting can also clean the micro burrs on the semi-finished chair leg 4. Step III - Spray painting: The semi-finished chair legs 4 are sprayed with electrostatic powder coating. The painted chair legs can be isolated from contact with air, thus achieving a rust-proof effect. After spraying, the finished chair legs are obtained.

[0021] The above description in this specification is merely illustrative of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the content of this specification or exceed the scope defined in the claims, they should all fall within the protection scope of this invention.

Claims

1. A chair foot forming process characterized by: include Step 1 - Cutting process, the cutting process is to punch out a metal template (1) in the shape of a chair leg by a stamping machine. The metal template (1) includes a center plate (10) located in the middle and a plurality of extension plates (11) extending to the center plate (10) around the center plate (10). Step 2 - Stamping process, wherein the stamping process uses a stamping machine to process the metal template (1) into a chair body (2), the chair body (2) includes a fixed part (20) located at the center, a plurality of support parts (21) extending to the periphery of the fixed part (20), and an installation part (22) located at the extended end of the support part (21). The stamping process specifically includes the following steps: Step I - Stretching: The metal template (1) is stamped and stretched according to the outline of the chair leg mold by a stamping press to obtain a chair leg blank. After stamping, the stamping press is held in the stamping state for 3-4 seconds. Step II - Edge trimming: Use a stamping machine to vertically cut off the excess sheet material at the edges of the fixed part (20) and the support part (21) in the chair leg blank, leaving the sheet material at the extended end of the support part (21); Step III - Shaping: The sheet metal retained at the extended end of the support part (21) is pressed down and shaped using a stamping press; Step IV - Side trimming ①: Trim the edges of the skirts of the mounting part (22) and the fixing part (20) on the chair leg blank using a stamping machine; Step V - Side trimming ②: Trim the skirt edge of the support part (21) on the chair leg blank using a stamping machine; Step VI - Pressing the edge: The burrs at the edge of the chair leg blank are pressed and flattened by punching to obtain the semi-finished chair leg body (2). When the punching machine presses down, a downward pressure of 300-450N is applied to the chair leg blank and lasts for 5-10 seconds. In step VI - pressing step, a designed chair leg shape mold is installed on the stamping machine. The chair leg shape mold is provided with an extrusion groove (5) for the skirt to extend into. The width of the extrusion groove (5) is equal to the skirt thickness of the chair leg blank. During stamping, the stamping machine presses the chair leg blank downward and fastens it onto the chair leg shape mold. At the same time, the skirt on the chair leg blank extends into the extrusion groove (5) and the bottom surface of the skirt abuts against the bottom of the extrusion groove (5). Step 3 - Welding process, which includes welding structural components (3) to improve structural strength inside the chair leg body (2) to obtain a semi-finished chair leg (4); It also includes a spraying process, which involves spraying an anti-rust layer onto the surface of the chair leg semi-finished product (4) to obtain the finished chair leg; The structural component (3) includes a bushing (30) fixed at the center of the fixing part (20), a roller seat (31) welded in the mounting part (22), and a support inner bone (32) fixed in the support part (21). The two sides of the support inner bone (32) are connected to the inner side of the support part (21), and the two ends of the support inner bone (32) are fixedly connected to the bushing (30) and the roller seat (31) respectively.

2. A chair foot forming process according to claim 1, wherein: The inner support bone (32) has at least one set of outwardly folded connecting ears (320) on both sides, and the inner support bone (32) is connected to the inner side of the support part (21) through the connecting ears (320).

3. The chair leg forming process according to claim 2, characterized in that: The connecting ears (320) on both sides of the supporting inner bone (32) are symmetrical to each other; the fixing part (20), the supporting part (21) and the mounting part (22) are integrally formed.

4. The chair leg forming process according to claim 1, characterized in that: The center plate (10) has a central hole punched in the center. The center plate (10) between two adjacent sets of extension plates (11) on the metal template (1) is stretched and bent downward to form the fixing part (20). The two sides of the extension plate (11) are stretched and bent downward to form the supporting part (21). The plate material at the extension end of the extension plate (11) is pressed down and shaped to form the mounting part (22).

5. The chair leg forming process according to claim 4, characterized in that: The skirt of the support part (21) has an arc-shaped profile.

6. The chair leg forming process according to claim 4, characterized in that: The cross-section of the support part (21) is a "∩" shaped structure.

7. The chair leg forming process according to claim 1, characterized in that: The spraying process specifically includes the following steps: Step I - Grinding: The semi-finished chair legs (4) are partially ground and repaired by manual grinding. Step II - Sandblasting: Place the semi-finished chair legs (4) into the sandblasting room for sandblasting treatment; Step III - Spray painting: The semi-finished chair legs (4) are sprayed with electrostatic powder coating to obtain the finished chair legs.

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