Sheet metal processing and forming process for lower bracket of chef machine

Abstract

The invention relates to the technical field of metal processing, and particularly discloses a sheet metal processing forming process of a lower bracket of a chef machine. The raw materials of the product comprise an SPCC cold-rolled steel sheet, argon and carbon dioxide mixed gas for welding, an electroplating solution, an alkaline degreasing solution, a sulfuric acid solution, a trivalent chromium passivator and a water-based acrylic resin sealing agent. The preparation method comprises the following steps: selecting raw materials, uncoiling and flattening, carrying out punch forming after laser cutting and blanking, carrying out bending forming and welding assembly for multiple times, removing welding slag and burrs, and sequentially carrying out surface treatment such as electrolytic degreasing, pickling and activating, electrogalvanizing, passivating and sealing. The lower support of the chef machine can be used for supporting the whole chef machine and has the advantages of being stable in structure and good in corrosion resistance. In addition, according to the preparation method, through cooperation of all working procedures, the machining stress is reduced, the machining precision is improved, and the preparation method has the advantages of being reasonable in process and controllable in operation.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal processing, in particular to a sheet metal processing forming process of a chef machine lower support. BACKGROUND

[0002] As a multifunctional kitchen equipment, the chef machine is widely used in kneading, stirring, sausage filling and other operations. When the machine runs, the high-speed rotation of the motor will generate continuous vibration and impact force. The chef machine lower support, as the bearing base of the whole machine, needs to stably connect the machine body and the workbench, disperse vibration energy, balance the equipment gravity center, and ensure that no inclination, displacement and other phenomena occur during operation, which is a key structural part to ensure the safe and stable operation of the chef machine.

[0003] In the prior art, the chef machine lower support is usually made of ordinary steel plate through cutting, bending and welding processes. Since the mechanical property adaptability of the plate material is not fully considered during raw material selection, the profile error of the blank is large due to insufficient precision control during cutting, and there is a lack of effective stress dispersion and release means during bending, so that a large amount of residual stress is easily accumulated in the support. After long-term bearing of vibration and load, these stresses will gradually release, resulting in deformation, joint loosening and even structure cracking of the support, which seriously affects the operation stability and service life of the chef machine. Therefore, how to reduce the stress accumulation in the processing of the support by optimizing the processing process and improve the structural stability has become a technical problem to be solved. SUMMARY

[0004] In order to solve the problem that the chef machine lower support in the prior art is prone to accumulate a large amount of residual stress in the processing process, thereby affecting the structural stability, and thus the structural stability of the support is not ideal, the application provides a sheet metal processing forming process of a chef machine lower support.

[0005] A sheet metal processing forming process of a chef machine lower support, comprising the following steps:

[0006] S1, raw material selection and pretreatment: select SPCC cold-rolled steel plate with a thickness of 0.8-1.5 mm as raw material, and perform uncoiling and flattening treatment, with a flattening accuracy of ≤0.5 mm / m;

[0007] S2, cutting and blanking: using a fiber laser cutting with a power of 2000-4000 W, the flattened steel plate is cut into a blank with a predetermined three-dimensional profile, the cutting path is assisted by nitrogen, and the cutting speed is controlled at 4-8 m / min;

[0008] S3, stamping forming: the blank is transferred to a continuous stamping die, and the positioning hole punching, outline cutting, reinforcing rib stamping and local flanging processes are sequentially completed at a stamping speed of 20-35 times / min;

[0009] S4, bending forming: at least three times of sequential bending to the stamping forming piece, the bending angle tolerance is controlled within ±0.5°, and the bending radius is strictly controlled between 1.0-1.8 times of the plate thickness;

[0010] S5, welding assembly: welding the bent assembly under the protection of carbon dioxide gas, the welding current is accurately controlled between 90-130A, and the welding speed is stabilized at 350-500mm / min;

[0011] S6, surface cleaning: removing the welding slag and burrs of the welded workpiece, and adopting the sand belt with the particle size gradient from 80 mesh to 180 mesh in the processing process, and the sand belt linear speed is maintained at 15-25m / min;

[0012] S7, surface treatment: sequentially performing electrolytic degreasing, pickling activation, and sulfate galvanizing treatment on the cleaned workpiece, the zinc ion concentration of the galvanizing liquid is maintained at 100-150g / L, the current density is controlled at 2-5A / dm2, and finally an uniform galvanizing layer with the thickness of 8-15μm is obtained, and then sequentially performing trivalent chromium passivation treatment and chromium-free sealing treatment.

[0013] By adopting the above technical scheme, by selecting SPCC cold-rolled steel plate and carrying out uncoiling and flattening, the initial precision and performance stability of the raw material are ensured; by adopting fiber laser cutting and nitrogen auxiliary cutting, the blank is accurately cut and the cutting defects are reduced; after continuous stamping forming, the blank is given predetermined structural characteristics; the angle and radius are controlled during bending, the bending precision is ensured; welding is carried out under the protection of carbon dioxide gas, the welding defects are reduced; the surface is cleaned to remove welding slag burrs, the surface flatness of the workpiece is ensured; the surface treatment is carried out in sequence, including degreasing, pickling, galvanizing and passivation sealing, the protective layer is formed, and the machining quality of the chef machine lower support is improved; wherein the positioning hole punching is to punch a precise positioning hole at the preset position of the blank, these holes serve as the reference for subsequent processes, which can ensure the accurate position of the blank in the mold during subsequent processing, and avoid errors in processing size caused by positioning deviation; the outline cutting is to accurately cut the excess part of the blank according to the predetermined support contour, so that the blank preliminarily forms the outline structure of the chef machine lower support, and provides a basic form that meets the size requirements for subsequent bending, welding and other processes; the reinforcing rib stamping is to press the reinforcing rib of the preset shape on the surface of the blank through the mold, and the protruding rib can significantly improve the structural strength and rigidity of the support, so that the support is not easy to deform when bearing load, and the load bearing capacity is enhanced; the local flanging process is to fold the specific edge of the blank, the folded edge can increase the connection area of the support and other parts, which is convenient for welding or bolt connection during subsequent assembly, and can also improve the structural stability of the edge part to avoid bending damage of the edge under stress; this series of processes are closely linked, and gradually process the flat blank into a formed piece with preliminary structural characteristics and functional basis, laying a good foundation for subsequent bending, welding and other processes.

[0014] Preferably, in step S1, the tensile strength of the cold-rolled steel plate is 270-320 MPa, and the elongation is not less than 28%.

[0015] By adopting the above technical scheme, by limiting the tensile strength and elongation of the cold-rolled steel plate, a reasonable choice is made based on the processing process requirements and the performance of the final product. The tensile strength is in the range of 270-320 MPa, which can ensure that the steel plate has sufficient load bearing capacity during subsequent stamping, bending and other processes, and is not easy to break under stress, while the strength is not too high to increase the processing difficulty; the elongation is not less than 28%, which ensures that the steel plate has good plasticity and deformation ability, and can smoothly complete the predetermined shape change in processes such as stamping forming and bending, reducing the risk of cracks, damage and other defects caused by insufficient plasticity, and ensuring the stability of the processing process and the structural integrity of the final product.

[0016] Preferably, in step S2, the nitrogen gas used for laser cutting has a purity of not less than 99.95% and a pressure of 0.6-0.9 MPa.

[0017] By adopting the above technical solution, limiting the purity and pressure of nitrogen during laser cutting is key to ensuring cutting quality. A nitrogen purity of not less than 99.95% can reduce the interference of impurities in the gas on the cutting process, prevent impurities from reacting with the steel plate at high temperatures to form an oxide layer or inclusions, ensure a smooth and clean cut, and reduce the burden of subsequent cleaning processes. Setting the gas pressure within the range of 0.6-0.9MPa can effectively blow away the slag generated during the cutting process, prevent slag from adhering to the cut edge and forming burrs, and provide a stable protective atmosphere for the cutting area, balancing the energy concentration of laser cutting and the slag removal effect, and ensuring the coordination and unity of cutting accuracy and efficiency.

[0018] Preferably, in step S4, before the first bend, a pre-bending weakening treatment is performed at the bend line, with a pre-bending angle of 15°-25°.

[0019] The purpose of adopting the above technical solution is to disperse the internal stress of the material by applying a small-angle deformation to the bending part in advance, thereby reducing the stress concentration during the actual bending. This treatment allows the material to undergo more uniform plastic deformation during subsequent large-angle bending, reducing the risk of cracks or over-hardening at the bending line due to sudden stress changes, ensuring the structural integrity and dimensional accuracy of the bending part, and providing a stable foundation for subsequent bending processes.

[0020] Preferably, in step S4, after each bending process is completed, the workpiece is subjected to intermittent annealing treatment at a temperature of 550-600℃ and a holding time of 3-5 minutes.

[0021] By adopting the above technical solution, high temperature can be used to promote the diffusion and rearrangement of atoms inside the material, effectively releasing the internal stress accumulated during the bending process. This treatment can alleviate the hardening phenomenon caused by plastic deformation of the material, avoid workpiece cracking or deformation in subsequent use caused by stress concentration, and at the same time maintain the plasticity and structural stability of the material, providing a good performance foundation for the next bending process, and ensuring the dimensional accuracy and structural reliability of the final formed part.

[0022] Preferably, in step S5, the protective gas used in the carbon dioxide gas shielded welding is a mixed gas, wherein argon accounts for 75-85%, carbon dioxide accounts for 15-25%, and the gas flow rate is 15-20 L / min.

[0023] By adopting the above technical solution, this ratio and flow rate setting can leverage the synergistic effect of the two gases. Argon has excellent inert protective properties, reducing the contact between the weld area and air and preventing oxidation. Carbon dioxide improves arc stability and molten pool fluidity, enhancing weld formation quality. A suitable gas flow rate can form a stable protective gas layer, isolating external air, while avoiding turbulence caused by excessive flow that could affect the protective effect. This ensures stable welding, reduces defects such as porosity and slag inclusions, and enhances weld bonding strength.

[0024] Preferably, in step S5, the weld area is subjected to vibration aging treatment immediately after the welding is completed, with a vibration frequency of 80-120Hz and a treatment time of 8-12min.

[0025] By employing the above technical solution, microscopic plastic deformation is induced in the weld and surrounding area through vibration at a specific frequency, thereby releasing the residual stress accumulated during the welding process. This treatment can alleviate stress concentration, prevent the weld from cracking or deforming due to stress, and simultaneously enhance the bonding tightness between the weld and the base material, improving the overall structural stability and ensuring that the support can stably bear the load during long-term use.

[0026] Preferably, in step S7, the electrolytic degreasing uses an alkaline degreasing solution, the temperature is 60-70℃, the current density is 3-6A / dm2, and the processing time is 1-2min.

[0027] By adopting the above technical solution, the alkaline degreasing solution can decompose grease through saponification reaction, while a suitable temperature can enhance the activity of the solution and accelerate the reaction rate; a certain current density can generate bubbles through electrolysis, peel off the oil stains and promote their emulsification. Combined with a reasonable treatment time, the oil stains can be thoroughly removed without causing excessive corrosion to the workpiece substrate, creating clean surface conditions for subsequent pickling activation and coating adhesion.

[0028] Preferably, in step S7, the sealing agent used in the chromium-free sealing treatment is mainly composed of water-based acrylic resin, the treatment temperature is 40-50℃, and the soaking time is 1-3 minutes.

[0029] By adopting the above technical solution, the role of the sealant can be fully utilized. Among them, water-based acrylic resin has good film-forming and permeability, which can deeply fill the micropores of the trivalent chromium passivation film. The appropriate temperature can improve the resin fluidity and enhance its bonding force with the passivation film. The reasonable soaking time ensures that the sealant fully adheres and forms a complete film, thereby strengthening the density of the passivation layer, reducing the penetration of corrosive media, and further improving the corrosion resistance of the stent.

[0030] Preferably, in step S7, the acid washing activation uses a sulfuric acid solution with a concentration of 180-220 g / L, a solution temperature of 25-35°C, and a soaking time of 90-150 s.

[0031] By adopting the above technical solution, the pickling effect can be effectively utilized. The sulfuric acid solution can dissolve the oxide film, rust and other impurities remaining on the workpiece surface after electrolytic degreasing. The appropriate concentration can ensure the dissolution efficiency while avoiding excessive corrosion of the substrate. The temperature of 25-35℃ can enhance the activity of the solution and accelerate the reaction rate. The immersion time of 90-150s can ensure the thorough removal of surface contaminants, while forming a uniform micro-rough structure on the workpiece surface, creating favorable conditions for the uniform adhesion and firm bonding of the zinc layer during the subsequent sulfate electroplating zinc treatment.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. Since this application uses SPCC cold-rolled steel sheet as raw material and performs uncoiling and leveling treatment, obtains the predetermined contour blank through fiber laser cutting, and performs pre-bending weakening and intermittent annealing treatment during bending, the raw material characteristics are suitable for processing and the coordination of each process reduces the stress influence during processing, thus achieving a stable support structure.

[0034] 2. In this application, a mixed shielding gas is preferably used for carbon dioxide gas shielded welding. After welding, the weld area is subjected to vibration aging treatment. Since the shielding gas improves the welding environment, the vibration aging treatment helps to alleviate the residual stress in the weld and achieves a good weld bonding effect.

[0035] 3. The method of this application involves sequentially performing electrolytic degreasing, pickling activation, and sulfate electroplating zinc treatment, followed by trivalent chromium passivation and chromium-free sealing treatment. The various surface treatment processes work together to form a complete protective system, thus achieving good corrosion resistance of the bracket. Attached Figure Description

[0036] Figure 1 This is a flowchart of the sheet metal processing and forming process for the lower support of a food processor provided in this application;

[0037] Figure 2 This is a three-dimensional schematic diagram of a food processor provided in this application;

[0038] Figure 3 This is a three-dimensional schematic diagram of a lower support for a food processor provided in this application. Detailed Implementation

[0039] The present application will be further described in detail below with reference to the accompanying drawings, embodiments and comparative examples.

[0040] Among them, the appendix Figure 2and attached Figure 3 This is merely an illustrative illustration and is not limited to this shape.

[0041] Technical concept:

[0042] In the sheet metal fabrication of the lower support of a food processor, existing technologies often suffer from insufficient structural stability. This is mainly because the mechanical properties of the sheet metal and the matching degree of the processing technology are not fully considered when selecting raw materials. Ordinary steel plates are prone to generating large internal stresses during cutting and bending. Insufficient precision control in the cutting process leads to large errors in the blank contour, resulting in uneven stress distribution during subsequent processing. The bending process lacks effective stress dispersion and release measures, causing internal stress to accumulate continuously. Over long-term use, the support is prone to deformation and cracking due to stress release, seriously affecting the overall structural stability.

[0043] This technical solution addresses the aforementioned issues by comprehensively optimizing everything from raw material selection to each processing step. It selects performance-compatible SPCC cold-rolled steel sheets and ensures raw material precision through uncoiling and leveling; employs fiber laser cutting to ensure accurate billet contours and reduce initial stress; adds pre-bending weakening treatment during bending to disperse stress, and combines this with intermittent annealing to release internal stress. The synergistic effect of these processes effectively reduces stress accumulation during processing, thereby improving the structural stability of the lower support of the food processor.

[0044] Raw material description:

[0045] The water-based acrylic resin sealant was purchased from Jiangsu Dasheng Technology Co., Ltd., and its brand name is DS-829 chromium-free acrylic sealant.

[0046] Example 1

[0047] This application provides a sheet metal fabrication process for the lower support of a food processor, including the following steps:

[0048] S1. Raw material selection and pretreatment: SPCC cold-rolled steel sheet with a thickness of 1.2mm is selected as raw material, and it is uncoiled and leveled with a leveling accuracy of ≤0.5mm / m; the tensile strength of the cold-rolled steel sheet is 295MPa and the elongation is not less than 28%.

[0049] S2. Cutting and blanking: A 3000W fiber laser is used to cut the leveled steel plate into blanks with a predetermined three-dimensional contour. The cutting path is assisted by nitrogen, with a nitrogen purity of not less than 99.95% and a gas pressure of 0.75MPa. The cutting speed is controlled at 6m / min.

[0050] S3. Stamping: The blank is transferred to a continuous stamping die, and the positioning hole punching, the outer shape precision cutting, the reinforcing rib stamping and the partial flanging process are completed in sequence at a stamping speed of 27 times / min.

[0051] S4. Bending Forming: The stamped part is bent at least three times in sequence. Before the first bend, a pre-bending weakening treatment is performed at the bending line with a pre-bending angle of 20°. After each bending process, the workpiece is intermittently annealed at a temperature of 575°C for 4 minutes. The bending angle tolerance is controlled within ±0.5°, and the bending radius is strictly controlled within 1.4 times the plate thickness.

[0052] S5. Welding Assembly: Weld the bent components under the protection of carbon dioxide gas. The welding current is precisely controlled within 110A, and the welding speed is stable at 425mm / min. The shielding gas used for carbon dioxide gas shielded welding is a mixed gas, with argon accounting for 80% and carbon dioxide accounting for 20%, and the gas flow rate is 17L / min. Immediately after welding, the weld area is subjected to vibration aging treatment at a vibration frequency of 100Hz for 10min.

[0053] S6. Surface cleaning: Remove welding slag and burrs from the welded workpiece. During the process, use abrasive belts with a particle size gradient from 80 mesh to 180 mesh, and maintain the abrasive belt linear speed at 20 m / min.

[0054] S7. Surface Treatment: The cleaned workpiece is subjected to electrolytic degreasing, pickling activation, and sulfate electroplating zinc treatment in sequence. Electrolytic degreasing uses an alkaline degreasing solution at a temperature of 65℃, a current density of 4.5A / dm2, and a treatment time of 1.5min. Pickling activation uses a sulfuric acid solution with a concentration of 200g / L at a solution temperature of 30℃ and an immersion time of 120s. The zinc ion concentration in the electroplating solution is maintained at 125g / L, and the current density is controlled at 3.5A / dm2, finally obtaining a uniform zinc plating layer with a thickness of 11.5μm. Subsequently, trivalent chromium passivation treatment and chromium-free sealing treatment are performed in sequence. The sealing agent used in the chromium-free sealing treatment is mainly composed of water-based acrylic resin, the treatment temperature is 45℃, and the immersion time is 2min.

[0055] Example 2

[0056] This application provides a sheet metal fabrication process for the lower support of a food processor, including the following steps:

[0057] S1. Raw material selection and pretreatment: SPCC cold-rolled steel sheet with a thickness of 0.8mm is selected as raw material, and it is uncoiled and leveled with a leveling accuracy of ≤0.5mm / m; the tensile strength of the cold-rolled steel sheet is 270MPa and the elongation is not less than 28%.

[0058] S2. Cutting and blanking: A 2000W fiber laser is used to cut the leveled steel plate into blanks with a predetermined three-dimensional contour. The cutting path is assisted by nitrogen, with a nitrogen purity of not less than 99.95% and a gas pressure of 0.6MPa. The cutting speed is controlled at 4m / min.

[0059] S3. Stamping: The blank is transferred to a continuous stamping die, and the positioning hole punching, the outer shape precision cutting, the reinforcing rib stamping and the partial flanging process are completed in sequence at a stamping speed of 20 times / min.

[0060] S4. Bending Forming: The stamped part is bent sequentially at least three times. Before the first bend, a pre-bending weakening treatment is performed at the bending line with a pre-bending angle of 15°. After each bending process, the workpiece is intermittently annealed at a temperature of 550°C for 3 minutes. The bending angle tolerance is controlled within ±0.5°, and the bending radius is strictly controlled within 1.0 times the plate thickness.

[0061] S5. Welding Assembly: Weld the bent components under the protection of carbon dioxide gas. The welding current is precisely controlled within 90A, and the welding speed is stable at 350mm / min. The shielding gas used for carbon dioxide gas shielded welding is a mixed gas, with argon accounting for 75% and carbon dioxide accounting for 25%, and the gas flow rate is 15L / min. Immediately after welding, the weld area is subjected to vibration aging treatment at a vibration frequency of 80Hz for a treatment time of 8min.

[0062] S6. Surface cleaning: Remove welding slag and burrs from the welded workpiece. During the process, use abrasive belts with a particle size gradient from 80 mesh to 180 mesh, and maintain the abrasive belt linear speed at 15 m / min.

[0063] S7. Surface Treatment: The cleaned workpiece is subjected to electrolytic degreasing, pickling activation, and sulfate electroplating zinc treatment in sequence. Electrolytic degreasing uses an alkaline degreasing solution at a temperature of 60℃, a current density of 3A / dm2, and a treatment time of 1min. Pickling activation uses a sulfuric acid solution with a concentration of 180g / L at a solution temperature of 25℃ and an immersion time of 90s. The zinc ion concentration in the electroplating solution is maintained at 100g / L, and the current density is controlled at 2A / dm2 to obtain a uniform zinc plating layer with a thickness of 8μm. Subsequently, trivalent chromium passivation treatment and chromium-free sealing treatment are performed in sequence. The sealing agent used in the chromium-free sealing treatment is mainly composed of water-based acrylic resin, the treatment temperature is 40℃, and the immersion time is 1min.

[0064] Example 3

[0065] This application provides a sheet metal fabrication process for the lower support of a food processor, including the following steps:

[0066] S1. Raw material selection and pretreatment: SPCC cold-rolled steel sheet with a thickness of 1.5mm is selected as raw material, and it is uncoiled and leveled with a leveling accuracy of ≤0.5mm / m; the tensile strength of the cold-rolled steel sheet is 320MPa and the elongation is not less than 28%.

[0067] S2. Cutting and blanking: A 4000W fiber laser is used to cut the leveled steel plate into blanks with a predetermined three-dimensional contour. The cutting path is assisted by nitrogen, with a nitrogen purity of not less than 99.95% and a gas pressure of 0.9MPa. The cutting speed is controlled at 8m / min.

[0068] S3. Stamping: The blank is transferred to a continuous stamping die, and the positioning hole punching, the outer shape precision cutting, the reinforcing rib stamping and the partial flanging process are completed in sequence at a stamping speed of 35 times / min.

[0069] S4. Bending Forming: The stamped part is bent sequentially at least three times. Before the first bend, a pre-bending weakening treatment is performed at the bending line with a pre-bending angle of 25°. After each bending process, the workpiece is intermittently annealed at a temperature of 600°C for 5 minutes. The bending angle tolerance is controlled within ±0.5°, and the bending radius is strictly controlled within 1.8 times the plate thickness.

[0070] S5. Welding Assembly: Weld the bent components under the protection of carbon dioxide gas. The welding current is precisely controlled within 130A, and the welding speed is stable at 500mm / min. The shielding gas used for carbon dioxide gas shielded welding is a mixed gas, with argon accounting for 85% and carbon dioxide accounting for 15%, and the gas flow rate is 20L / min. Immediately after welding, the weld area is subjected to vibration aging treatment at a vibration frequency of 120Hz for 12min.

[0071] S6. Surface cleaning: Remove welding slag and burrs from the welded workpiece. During the process, use abrasive belts with a particle size gradient from 80 mesh to 180 mesh, and maintain the abrasive belt linear speed at 25 m / min.

[0072] S7. Surface Treatment: The cleaned workpiece is subjected to electrolytic degreasing, pickling activation, and sulfate electroplating zinc treatment in sequence. Electrolytic degreasing uses an alkaline degreasing solution at a temperature of 70℃, a current density of 6A / dm2, and a treatment time of 2min. Pickling activation uses a sulfuric acid solution with a concentration of 220g / L at a solution temperature of 35℃ and an immersion time of 150s. The zinc ion concentration in the electroplating solution is maintained at 150g / L, and the current density is controlled at 5A / dm2 to obtain a uniform zinc plating layer with a thickness of 15μm. Subsequently, trivalent chromium passivation treatment and chromium-free sealing treatment are performed in sequence. The sealing agent used in the chromium-free sealing treatment is mainly composed of water-based acrylic resin, the treatment temperature is 50℃, and the immersion time is 3min.

[0073] Comparative Example 1

[0074] The only difference between this comparative example and Example 1 is that in step S1, a Q235B hot-rolled steel plate with a thickness of 1.2 mm is selected as the raw material to replace the SPCC cold-rolled steel plate; the remaining steps and parameters are exactly the same as in Example 1.

[0075] Comparative Example 2

[0076] The only difference between this comparative example and Example 1 is that in step S4, the step of performing a pre-bending weakening treatment at the bending line before the first bending is omitted, and three sequential bending is performed directly; the remaining steps and parameters are exactly the same as in Example 1.

[0077] Comparative Example 3

[0078] The only difference between this comparative example and Example 1 is that in step S4, the step of intermittently annealing the workpiece after each bending process is omitted, and only three sequential bending processes are performed; the remaining steps and parameters are exactly the same as in Example 1.

[0079] Comparative Example 4

[0080] The only difference between this comparative example and Example 1 is that in step S5, the step of immediately performing vibration aging treatment on the weld area after welding is omitted, and the process proceeds directly to step S6 after welding is completed; the remaining steps and parameters are exactly the same as in Example 1.

[0081] Comparative Example 5

[0082] The only difference between this comparative example and Example 1 is that in step S7, the pickling and activation process is omitted, and sulfate electroplating is performed directly after electrolytic degreasing; the remaining steps and parameters are exactly the same as in Example 1.

[0083] Comparative Example 6

[0084] The difference between this comparative example and Example 1 is only that: in step S7, the process of sulfate electro-galvanizing is cancelled, and after pickling and activation, trivalent chromium passivation treatment and chromium-free sealing treatment are directly carried out on the workpiece. The remaining steps and parameters are exactly the same as those in Example 1.

[0085] Comparative Example 7

[0086] The difference between this comparative example and Example 1 is only that: in step S7, the process of chromium-free sealing treatment is cancelled, and after the trivalent chromium passivation treatment is completed, the final workpiece is obtained; the remaining steps and parameters are exactly the same as those in Example 1.

[0087] Test Item 1: Structural Strength Test

[0088] The test purpose is to detect the structural stability of the lower bracket of the food processor after different process treatments when bearing the rated load, and to reflect the influence of raw material selection, bending and welding processes on the mechanical properties of the product. The test samples are 3 pieces of the lower brackets of the food processors prepared in Examples 1-3 and Comparative Examples 1-7 respectively. The test equipment includes a universal material testing machine, a displacement sensor, and a data acquisition system.

[0089] Test steps: Fix the sample horizontally on the test platform of the universal material testing machine, apply a vertical downward static load at the center position of the top of the bracket, the load size is set to 1.5 times the rated working load of the food processor, continuously load for 30 minutes, and use the displacement sensor to monitor the maximum deformation of the bracket in real time. At the same time, observe whether there are any damages such as cracks and fractures, and the data acquisition system records the load and deformation data during the whole process. Judgment criterion: If the maximum deformation of the sample does not exceed 0.5 mm and there is no damage, the structural strength is qualified, and the smaller the deformation, the better the structural strength.

[0090] Test Item 2: Corrosion Resistance Test

[0091] The test purpose is to evaluate the effect of the surface treatment process of the bracket, reflect the influence of electroplating, passivation and sealing treatments on the corrosion resistance of the product, and is associated with the structural strength test because corrosion will weaken the structural strength. The test samples are 3 pieces of the lower brackets of the food processors prepared in Examples 1-3 and Comparative Examples 1-7 respectively, and 3 test areas of 10 mm × 10 mm are selected in the non-welded area of each sample. The test equipment uses a salt spray test chamber and a caliper with an accuracy of 0.01 mm.

[0092] Test Procedure: Place the sample in a salt spray chamber and conduct a neutral salt spray test according to GB / T10125-2021 standard. The test temperature is 35℃, the salt solution concentration is 5% sodium chloride solution, and the pH value is between 6.5 and 7.2. After continuous spraying for 48 hours, remove the sample, rinse the surface with clean water to remove salt, and allow it to air dry for 24 hours. Observe the corrosion in the test area and measure the percentage of rusted area using calipers. Judgment Criteria: If the percentage of rusted area does not exceed 5%, the corrosion resistance is qualified; the smaller the percentage, the better the corrosion resistance.

[0093] Test Item 3: Welding Strength Test

[0094] The purpose of the test was to verify the influence of welding process and vibration aging treatment on weld strength, which is related to structural strength testing, as weld strength is an important component of overall structural strength. The test samples were three lower supports for each of the food processors prepared in Examples 1-3 and Comparative Examples 1-7. A specimen containing a complete weld was cut from each sample, with specimen dimensions of 50mm × 20mm × plate thickness. The testing equipment included a universal testing machine and a special fixture for weld strength.

[0095] Test Procedure: Fix the specimen on a universal testing machine using a special fixture. Apply a tensile load perpendicular to the weld at a speed of 5 mm / min until the specimen breaks. Record the maximum load at fracture and calculate the tensile strength of the weld. Simultaneously observe whether the fracture location is at the weld. Judgment Criteria: If the tensile strength of the weld is not less than 80% of the tensile strength of the raw material and the fracture location is not at the weld, the weld strength is qualified. The higher the tensile strength, the better the weld quality. The calculation is as follows: First, measure the actual tensile strength of the SPCC cold-rolled steel plate. Then, measure the tensile strength of the weld joint according to GB / T2651-2008 standard. Finally, calculate the strength ratio using the formula "weld tensile strength / raw material tensile strength × 100%" to evaluate the efficiency of the weld joint.

[0096] The results of the key performance tests of Examples 1-3 and Comparative Examples 1-7 are shown in Table 1.

[0097] Table 1:

[0098]

[0099]

[0100] 1. The standard for testing deformation is: GB / T228.1-2021 "Metallic materials, tensile testing - Part 1: Test at room temperature";

[0101] 2. The test standard for the percentage of rusted area is: GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test";

[0102] 3. The standard for testing tensile strength is GB / T2651-2008 "Tension Test Method for Welded Joints";

[0103] 4. The test standard for the ratio of strength to raw material strength is as follows: This index is a calculated value, and its test basis follows GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature".

[0104] As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, the type of raw material has a significant impact on product performance. After replacing SPCC cold-rolled steel plate with Q235B hot-rolled steel plate, the deformation of the bracket increased to 1.85mm, and the rust area ratio increased to 45.2%. This is because SPCC cold-rolled steel plate has a smoother surface and more uniform mechanical properties after cold rolling, which can better bear the load and reduce the adhesion of corrosive media. In contrast, hot-rolled steel plate has relatively poor surface quality and mechanical stability, resulting in a decrease in structural stability and corrosion resistance.

[0105] As can be seen from Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, the pre-bending weakening treatment has a significant impact on the structural stability of the support after bending. In Comparative Example 2, after omitting this step, the deformation increased to 2.10 mm, while other performance indicators remained similar to those of Examples 1-3. This is because the pre-bending weakening treatment can disperse the stress at the bending line before the formal bending, reducing stress concentration during bending. Direct bending, on the other hand, makes stress concentration more pronounced, leading to increased deformation of the support under load.

[0106] As can be seen from Examples 1-3 and Comparative Example 3, and in conjunction with Table 1, intermittent annealing is crucial for alleviating the internal stress generated during bending. In Comparative Example 3, after omitting this step, the deformation increased to 3.50 mm, and the percentage of rusted area also slightly increased. This is because internal stress is generated in the material during bending. Annealing can release this stress by rearranging atoms through heating. Accumulated internal stress can lead to greater deformation of the support under load, and in the long term, it may also affect material stability, indirectly increasing the risk of corrosion.

[0107] As can be seen from Examples 1-3 and Comparative Example 4, and in conjunction with Table 1, the vibration aging treatment after welding has a significant impact on the weld strength. In Comparative Example 4, after this step was omitted, the tensile strength decreased to 205 MPa, the ratio to the strength of the raw material decreased to 69.5%, and the deformation also increased to 0.95 mm. This is because there is residual stress in the weld area after welding. Vibration aging can gradually release the stress through vibration, enhancing the bond between the weld and the base material. However, the residual stress weakens the weld strength, leading to a decrease in the overall structural load-bearing capacity.

[0108] As can be seen from Examples 1-3 and Comparative Example 5, and Table 1, the pickling activation process has a significant impact on the surface treatment effect. In Comparative Example 5, after omitting this step, the rust area ratio surged to 98.0%, while other performance indicators remained basically unchanged. This is because after electrolytic degreasing, the workpiece surface may still have residual oxide film or impurities. Pickling activation can dissolve these substances through sulfuric acid solution, making it easier for the subsequent zinc plating layer to adhere. Without this step, the zinc plating layer will not adhere firmly, is prone to peeling, and lose its anti-corrosion effect.

[0109] As can be seen from Examples 1-3 and Comparative Example 6, and Table 1, sulfate electroplating is a key process for ensuring corrosion resistance. In Comparative Example 6, after omitting this step, the rusted area increased to 95.5%. This is because the zinc plating layer protects the base metal through sacrificial anode action, preventing it from directly contacting the corrosive medium. Without the zinc plating layer, the base metal is directly exposed to the salt spray environment, leading to rapid corrosion.

[0110] As can be seen from Examples 1-3 and Comparative Example 7, and Table 1, the chromium-free sealing treatment enhances the protective effect of the passivation layer. In Comparative Example 7, after omitting this step, the rust area increased to 15.7%. This is because the passivation film formed by trivalent chromium passivation has micropores, which the chromium-free sealant can fill, forming a denser protective layer and reducing the penetration of corrosive media. The lack of sealing treatment reduces the protective properties of the passivation film, leading to an increase in the rust area.

[0111] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A sheet metal forming process for the lower support of a food processor, characterized in that: Includes the following steps: S1. Raw material selection and pretreatment: SPCC cold-rolled steel sheets with a thickness of 0.8mm to 1.5mm are selected as raw materials and uncoiled and leveled, with a leveling accuracy of ≤0.5mm / m; S2. Cutting and blanking: Using a fiber laser with a power of 2000-4000W, the leveled steel plate is cut into blanks with a predetermined three-dimensional contour. The cutting path is assisted by nitrogen, and the cutting speed is controlled at 4-8m / min. S3, Stamping: The blank is transferred to a continuous stamping die, and the positioning hole punching, the outer shape precision cutting, the reinforcing rib stamping and the partial flanging process are completed in sequence at a stamping speed of 20-35 times / min. S4. Bending and forming: The stamped parts are bent at least three times in sequence, with the bending angle tolerance controlled within ±0.5° and the bending radius strictly controlled between 1.0 and 1.8 times the plate thickness. S5. Welding Assembly: Weld the bent components under the protection of carbon dioxide gas. The welding current is precisely controlled between 90-130A, and the welding speed is stable at 350-500mm / min. S6. Surface cleaning: Remove welding slag and burrs from the welded workpiece. During the process, use abrasive belts with a particle size gradient from 80 mesh to 180 mesh, and maintain the abrasive belt linear speed at 15-25 m / min. S7. Surface treatment: After cleaning, the workpiece is subjected to electrolytic degreasing, pickling activation, and sulfate electroplating zinc treatment in sequence. The zinc ion concentration of the electroplating solution is maintained at 100-150g / L, and the current density is controlled at 2-5A / dm2. Finally, a uniform zinc plating layer with a thickness of 8-15μm is obtained. Then, trivalent chromium passivation treatment and chromium-free sealing treatment are performed in sequence.

2. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S1, the tensile strength of the cold-rolled steel sheet is 270-320 MPa, and the elongation is not less than 28%.

3. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S2, the nitrogen gas used for laser cutting has a purity of not less than 99.95% and a pressure of 0.6-0.9 MPa.

4. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S4, before the first bend, a pre-bend weakening treatment is performed at the bend line, with a pre-bend angle of 15°-25°.

5. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S4, after each bending process, the workpiece is subjected to intermittent annealing treatment at a temperature of 550-600℃ and a holding time of 3-5 minutes.

6. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S5, the protective gas used in the carbon dioxide gas shielded welding is a mixed gas, in which argon accounts for 75-85%, carbon dioxide accounts for 15-25%, and the gas flow rate is 15-20L / min.

7. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S5, the weld area is subjected to vibration aging treatment immediately after the welding is completed. The vibration frequency is 80-120Hz and the treatment time is 8-12min.

8. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S7, the electrolytic degreasing uses an alkaline degreasing solution, the temperature is 60-70℃, the current density is 3-6A / dm2, and the processing time is 1-2min.

9. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S7, the sealing agent used in the chromium-free sealing treatment is mainly composed of water-based acrylic resin, the treatment temperature is 40-50℃, and the soaking time is 1-3 minutes.

10. The sheet metal forming process for the lower support of a food processor according to claim 1, characterized in that: In step S7, the acid washing and activation uses a sulfuric acid solution with a concentration of 180-220 g / L, a solution temperature of 25-35℃, and a soaking time of 90-150 s.

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