Sheet metal forming combination process for upper and lower brackets of chef

Abstract

The invention relates to the technical field of sheet metal processing, and discloses a chef upper and lower bracket sheet metal forming combination process, which comprises the following steps: S1, blanking and pretreatment; s2, preforming and bending the bracket and the connecting piece, independently feeding a connecting piece plate into a stamping die, stamping to form an n-shaped structure with a barb-shaped bulge, forming a stress release groove in a transition part of an elastic arm and a middle section, and then bending; s3, combining and assembling; s4, strengthening fixation and stress elimination; s5, carrying out size calibration; s6, surface treatment; and S7, final inspection. The connecting piece is arranged between the upper support and the lower support, annealing, carburizing, quenching and tempering and shot peening strengthening treatment are sequentially conducted on the connecting piece, and the stress releasing groove is formed in the transition position of the elastic arm and the middle section, so that the technical effect of remarkably improving the abrasion resistance and the fatigue resistance of the connecting piece is achieved; and the problem of easy looseness or fracture due to abrasion and stress concentration in long-term use is solved.

Description

TECHNICAL FIELD

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

[0002] In the overall structure of the chef machine, the upper and lower supports are core components that support the equipment and are key structures that ensure stability. The performance of the connecting piece, which serves as the connecting link between the upper and lower supports, directly determines the overall service life and safety and reliability of the chef machine. Currently, the industry uses traditional sheet metal processing methods for the processing of the upper and lower supports of the chef machine, that is, the support base material is first subjected to simple cutting and bending, and then a connecting piece is made from ordinary steel. The combination of the upper support and the lower support is achieved through welding or single bolt connection. However, there is a lack of targeted strengthening treatment, which leads to problems such as loose connection and structural deformation of the overall structure in a long-term high-frequency vibration environment, affecting the normal operation of the chef machine.

[0003] The existing technology generally has the problems of process simplification and insufficient performance control. Most schemes only perform basic cutting and forming on the upper and lower supports and then directly splice them together without optimizing the structure according to their working characteristics. As a result, the connection between the upper and lower supports is prone to wear and tear, elastic failure, or even breakage due to poor wear resistance and insufficient fatigue resistance when subjected to long-term alternating loads and friction, which shortens the service life of the connecting piece and significantly reduces the reliability and stability of the overall structure of the chef machine. SUMMARY

[0004] To address the deficiencies of the prior art, the present application provides a sheet metal forming combination process for the upper and lower supports of a chef machine, which solves the problem of loose connection or breakage due to long-term wear and stress concentration.

[0005] To achieve the above objectives, the present application is implemented by the following technical solution: a sheet metal forming combination process for the upper and lower supports of a chef machine, comprising the following steps:

[0006] S1, blanking and pretreatment: selecting a cold-rolled steel sheet as the base material for the upper and lower supports and a spring steel as the base material for the connecting piece, using laser cutting to obtain the initial plate material, grinding the edges of the support plate material to remove burrs, and annealing the connecting piece plate material, followed by surface carburizing treatment;

[0007] S2, pre-forming and bending of the support and the connecting piece: feeding the upper and lower support plate materials into the stamping equipment respectively, stamping T-shaped positioning grooves and stepped bosses, and then performing bending treatment, feeding the connecting piece plate material into the stamping die separately, stamping an n-shaped structure with barb-shaped protrusions and setting a stress relief groove at the transition between the elastic arm and the middle segment, and then performing bending treatment;

[0008] S3, combined assembly: after the upper support, the lower support and the connecting piece are completed, the barb-shaped protrusion of the connecting piece is aligned with the positioning groove of the lower support, the protrusion of the connecting piece is embedded into the groove of the lower support to form mechanical engagement, the positioning pin is inserted into the positioning hole of the boss of the connecting piece to realize the positioning of the connecting piece and the upper and lower supports;

[0009] S4, reinforcement and stress relief: reinforcement and fixation are performed at the engagement part of the connecting piece and the support, after the reinforcement and fixation is completed, aging treatment is performed, and then the elastic arm of the connecting piece is subjected to shot peening strengthening treatment;

[0010] S5, size calibration: the size of the overall assembly is detected by using a laser profiler;

[0011] S6, surface treatment: the overall assembly is subjected to phosphating treatment, the exposed area of the connecting piece is coated with an elastic coating, and the remaining area of the support is subjected to electrostatic spraying treatment;

[0012] S7, final inspection: the size of the formed assembly is detected, and vibration test, tension test, wear resistance test and fatigue test are performed.

[0013] Preferably, in step S1, the annealing temperature of the connecting piece is 700-750℃, the holding time is 1h, the carburizing temperature is 900-930℃, the holding time is 4-6h, and the carburizing layer depth is 0.8-1.2mm.

[0014] Preferably, in step S2, the preparation process of the connecting piece includes the following steps:

[0015] Select spring steel raw materials for rolling, and perform surface cleaning to remove oxide scale after rolling;

[0016] The cleaned plate is subjected to laser cutting to obtain a connecting piece initial blank, the blank is subjected to first annealing at a temperature of 650-700℃ for 2-3h, and is cooled in the furnace to eliminate rolling stress;

[0017] Then, pre-forming is performed by stamping to form a preliminary n-shaped structure, the pre-formed piece is subjected to second annealing at a temperature of 700-750℃ for 1h to prepare for subsequent carburizing;

[0018] After carburizing treatment, quenching and low temperature tempering are performed, and then the tail slot stamping die is used for final forming.

[0019] Preferably, in step S2, the connecting piece is formed into an n-shaped structure by stamping, the length of the front flat section is consistent with the contact surface of the upper support and the lower support, the two ends are bent to form elastic arms, and the bottom of the connecting piece is provided with a protrusion limiting structure matched with the positioning groove of the lower support.

[0020] Preferably, in the step S2, the bending line avoids the subsequent connecting and positioning structure, the bending gap of the 1.5-2mm thick support is 1.2 times of the plate thickness, the pressure is 60-80MPa, the bending gap of the 2-3mm thick support is 1.5 times of the plate thickness, the pressure is 100-120MPa, the bending angle is 90°±0.2°, the connecting piece is subjected to liquid nitrogen cryogenic treatment after being bent, the treatment temperature is-180 to-160℃, and the holding time is 1-2h.

[0021] Preferably, in the step S3, the combined assembly is subjected to 5-8MPa pressure by a hydraulic pressure assembly machine to make the barbs embedded in the grooves, the holding time is 10-15s, the positioning pin has a diameter of 3-5mm and is plated with chromium, the plating layer has a thickness of 0.01-0.02mm, and the verticality error after positioning is ≤±0.1mm.

[0022] Preferably, in the step S4, the reinforcement and fixation are achieved by using rivets or screws, the rivet is an aluminum core-pulling rivet with a diameter of 3-5mm and a riveting force of 300-500N, the screw is a stainless steel cross slot screw with a diameter of 3-5mm and a tightening torque of 8-15N·m, the aging treatment temperature is 120-150℃, the holding time is 2h, the shot peening strengthening is achieved by using steel shots with a diameter of 0.2-0.3mm and a spraying pressure of 0.4-0.6MPa, and the coverage rate is 100%.

[0023] Preferably, in the step S5, the relative position error detected by the laser profilometer is ≤0.05mm, and the detection area includes the fitting surface of the connecting piece and the upper support, the occlusion of the connecting piece and the lower support, and the matching part of the positioning pin and the hole.

[0024] Preferably, in the step S6, the temperature of the phosphating tank solution is 50-60℃, the treatment time is 10-15min, the film thickness is 3-5μm, the elastic coating is polyurethane containing 10-15% silicon carbide particles and has a thickness of 0.1-0.15mm, the pre-baking temperature is 80-90℃, the pre-baking time is 10min, the electrostatic plastic spraying adopts epoxy resin powder and has a thickness of 0.15-0.2mm, and the curing temperature is 180-200℃ and the curing time is 15-20min.

[0025] Preferably, in the step S7, the vibration test frequency is 10-50Hz, the amplitude is 0.5mm, the duration is 24h, the tensile test applies an axial force of 500-800N and keeps for 30s, the wear resistance test load is 50-100N, the friction speed is 0.5-1m / s, the stroke is 1000m, the wear amount is ≤0.01g, and the fatigue test applies ±300N alternating load, the frequency is 10-20Hz, and the cycle is ≥10 6 times.

[0026] The present application provides a sheet metal forming combined process for the upper and lower supports of a chef machine.

[0027] 1. The present application sets a connecting piece between the upper support and the lower support, and sequentially carries out annealing, carburizing, quenching and tempering, and shot peening strengthening treatment on the connecting piece, and sets a stress release groove at the transition of the elastic arm and the middle section, so as to significantly improve the wear resistance and fatigue resistance of the connecting piece, and solve the problem of loosening or fracture due to wear and stress concentration during long-term use.

[0028] 2. The present application completes preforming and bending of the upper support, the lower support and the connecting piece respectively, and then combines them through mechanical occlusion and rivet or screw reinforcement, so as to ensure the assembly precision and connection stability, compared with the prior art which usually assembles first and then bends or relies on a single fixing method, the problem of insufficient assembly precision and connection strength due to bending stress is solved.

[0029] 3. The present application carries out phosphating treatment on the whole assembly to improve the basic protection capability, and at the same time, coats an elastic coating on the exposed area of the connecting piece, and electrostatically sprays plastic on the surface area of the upper support and the lower support, so as to meet the corrosion resistance of the assembly and the special protection requirement of the exposed part of the connecting piece, compared with the prior art which usually adopts a single surface treatment method, the problem of difficult to meet the protection requirement of different parts and easy to fail due to wear of the exposed area of the connecting piece is solved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The process flow chart of the sheet metal forming and combining process of the upper and lower supports of the chef machine of the present application;

[0031] Figure 2 The overall three-dimensional schematic diagram of the upper and lower supports of the sheet metal forming and combining process of the upper and lower supports of the chef machine of the present application;

[0032] Figure 3 The overall side view schematic diagram of the upper and lower supports of the sheet metal forming and combining process of the upper and lower supports of the chef machine of the present application;

[0033] Figure 4 The connecting piece schematic diagram of the sheet metal forming and combining process of the upper and lower supports of the chef machine of the present application. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0035] Please refer to the drawings of the present application Figure 1 - the drawings of the present application Figure 4The embodiment of the present application provides a sheet metal forming combined process of an upper and lower support of a chef machine, comprising the following steps:

[0036] S1, blanking and pretreatment: selecting a cold-rolled steel plate as a base material of the upper support and the lower support, and a spring steel as a connecting piece base material, adopting laser cutting to obtain an initial plate, polishing the edges of the support plate to remove burrs, annealing the connecting piece plate, and then performing surface carburizing treatment;

[0037] S2, support and connecting piece pre-forming and bending: respectively feeding the upper support and the lower support plate into a stamping equipment, stamping to form a T-shaped positioning groove and a stepped boss, and then performing bending treatment, separately feeding the connecting piece plate into a stamping die, stamping to form an n-shaped structure with a barb-shaped protrusion and setting a stress release groove at the transition between the elastic arm and the middle section, and then performing bending treatment;

[0038] S3, combined assembly: after the upper support, the lower support and the connecting piece are all completed bending forming, aligning the barb-shaped protrusion of the connecting piece with the positioning groove of the lower support, embedding the protrusion of the connecting piece into the groove of the lower support to form mechanical engagement, and inserting a positioning pin into the positioning hole of the protrusion of the connecting piece to realize the positioning of the connecting piece and the upper and lower supports;

[0039] S4, reinforcement and stress relief: reinforcing and fixing the engagement part of the connecting piece and the support, performing aging treatment after the reinforcement and fixing is completed, and then performing shot peening strengthening treatment on the elastic arm of the connecting piece;

[0040] S5, size calibration: detecting the size of the overall combination by using a laser contour instrument;

[0041] S6, surface treatment: performing phosphating treatment on the overall assembly, coating an elastic coating on the exposed area of the connecting piece, and performing electrostatic spraying treatment on the remaining area of the support;

[0042] S7, final inspection: performing size detection on the formed assembly, and simultaneously performing vibration test, tensile test, wear resistance test and fatigue test.

[0043] Specifically, the annealing treatment can eliminate the rolling internal stress of the connecting piece, avoid subsequent processing deformation, the carburizing can control the depth of the carburized layer, improve the surface hardness and wear resistance of the connecting piece, and solve the problem of short service life caused by insufficient strength and easy wear of the connecting piece in the traditional process;

[0044] Step-by-step rolling, annealing and forming can avoid structural defects caused by one-time processing of the connecting piece, and the two annealings can respectively eliminate the rolling stress and the pre-forming stress, and the quenching and tempering can further strengthen the mechanical properties, solving the problems of poor forming quality and unstable performance of the connecting piece in the traditional process;

[0045] The n-shaped structure is matched with the length of the contact surface, ensuring that the connecting piece and the bracket are tightly attached, the protruding limiting structure is precisely matched with the positioning groove, displacement after assembly is avoided, and the poor adaptability and easy loosening of the upper bracket and the lower bracket after direct connection in traditional assembly are solved.

[0046] In step S1, the annealing temperature of the connecting piece is 700-750 DEG C, the holding time is 1h, the carburizing temperature is 900-930 DEG C, the holding time is 4-6h, and the carburizing layer depth is 0.8-1.2mm.

[0047] In step S2, the preparation process of the connecting piece includes the following steps:

[0048] The spring steel raw material is selected for rolling, and the surface is cleaned after rolling to remove the oxide skin;

[0049] The cleaned plate is laser cut to obtain the initial blank of the connecting piece, the blank is annealed for the first time, the temperature is 650-700 DEG C, the holding time is 2-3h, and the furnace cooling is used to eliminate the rolling stress;

[0050] Then, the stamping preforming is carried out to form the preliminary n-shaped structure, the preformed part is annealed for the second time, the temperature is 700-750 DEG C, and the holding time is 1h, which prepares for the subsequent carburizing;

[0051] After the carburizing treatment, quenching and low temperature tempering are carried out, and then the tail slot stamping die is used for final forming.

[0052] In step S2, the connecting piece is formed into an n-shaped structure, the length of the front plane section is consistent with the contact surface of the upper bracket and the lower bracket, the two ends are bent to form elastic arms, and the bottom of the connecting piece is provided with a protruding limiting structure matched with the positioning groove of the lower bracket.

[0053] In step S2, the bending line avoids the subsequent connection and positioning structure, the bending gap of the 1.5-2mm thick bracket is 1.2 times of the plate thickness, the pressure is 60-80MPa, the bending gap of the 2-3mm thick bracket is 1.5 times of the plate thickness, the pressure is 100-120MPa, the bending angle is 90 DEG ± 0.2 DEG, and the connecting piece is treated by liquid nitrogen deep cooling after bending, the treatment temperature is-180 to-160 DEG C, the holding time is 1-2h.

[0054] In step S3, the combined assembly is embedded into the groove by applying 5-8MPa pressure to the barb through the hydraulic press, the pressure is maintained for 10-15s, the positioning pin has a diameter of 3-5mm, the surface is plated with chromium, the plating layer has a thickness of 0.01-0.02mm, and the verticality error after positioning is ≤±0.1mm.

[0055] In step S4, the reinforcement and fixation are performed by using rivets or screws. The rivets are aluminum blind rivets with a diameter of 3-5 mm and a riveting force of 300-500 N. The screws are stainless steel cross slot screws with a diameter of 3-5 mm and a tightening torque of 8-15 N·m. The screws are subjected to aging treatment at a temperature of 120-150 ℃ for 2 h. The shot peening is performed by using steel shots with a diameter of 0.2-0.3 mm at a spraying pressure of 0.4-0.6 MPa with a coverage of 100%.

[0056] In step S5, the relative position error detected by the laser profiler is less than or equal to 0.05 mm. The detection area includes the fitting surface of the connecting piece and the upper bracket, the occlusion of the connecting piece and the lower bracket, and the matching part of the positioning pin and the hole.

[0057] In step S6, the phosphating tank solution has a temperature of 50-60 ℃ and the treatment time is 10-15 min. The film thickness is 3-5 μm. The elastic coating is polyurethane containing 10-15% silicon carbide particles with a thickness of 0.1-0.15 mm. The coating is pre-baked at 80-90 ℃ for 10 min. The electrostatic spraying is performed by using epoxy resin powder with a thickness of 0.15-0.2 mm and a curing temperature of 180-200 ℃ for 15-20 min.

[0058] In step S7, the vibration test is performed at a frequency of 10-50 Hz and an amplitude of 0.5 mm for 24 h. The tensile test is performed by applying an axial force of 500-800 N for 30 s. The wear test is performed under a load of 50-100 N at a friction speed of 0.5-1 m / s for a stroke of 1000 m with a wear amount of less than or equal to 0.01 g. The fatigue test is performed by applying an alternating load of ±300 N at a frequency of 10-20 Hz for more than 10 cycles. 6

[0059] The specific embodiments are described below:

[0060] Embodiment 1

[0061] A sheet metal forming combined process for the upper and lower brackets of a chef machine includes the following steps:

[0062] S1, blanking and pretreatment: cold-rolled steel plates are selected as the base materials of the upper and lower brackets, and spring steel is selected as the base material of the connecting piece. The initial plate is obtained by laser cutting. The edges of the bracket plate are polished to remove burrs. The connecting piece plate is annealed at a temperature of 700 ℃ for 1 h, and then subjected to surface carburizing treatment at a temperature of 900 ℃ for 4 h with a carburized layer depth of 0.8 mm.

[0063] S2, bracket and connecting piece pre-forming and bending: the upper bracket and lower bracket plates are respectively sent into the stamping equipment. After the T-shaped positioning groove and stepped boss are formed by stamping, bending treatment is performed. The connecting piece plate is separately sent into the stamping die. The n-shaped structure with barb-shaped protrusions is formed by stamping, and a stress release groove is arranged at the transition between the elastic arm and the middle segment. Subsequently, bending treatment is performed.​

[0064] The preparation process of the connecting piece is as follows: selecting spring steel raw material for rolling, cleaning the surface after rolling to remove the oxide skin, laser cutting the cleaned plate to obtain the connecting piece initial blank, first annealing the blank at a temperature of 650 DEG C for 2 h, cooling in the furnace to eliminate rolling stress, then preforming by stamping to form a preliminary n-shaped structure, second annealing the preformed piece at a temperature of 700 DEG C for 1 h to prepare for subsequent carburizing, quenching and low temperature tempering after carburizing, and then finally forming by sending into a tail bolt slot stamping die, avoiding the subsequent connection and positioning structure, the bending line of the 1.5 mm thick support is 1.2 times the plate thickness, the pressure is 60 MPa, the bending angle is 90 DEG -0.2 DEG, the connecting piece is treated by liquid nitrogen deep cooling after bending, the treatment temperature is-180 DEG C, and the holding time is 1 h;

[0065] S3, combined assembly: after the upper support, the lower support and the connecting piece are all bent and formed, the barb-shaped protrusion of the connecting piece is aligned with the positioning groove of the lower support, the protrusion of the connecting piece is embedded into the groove of the lower support to form mechanical engagement, the positioning pin is inserted into the positioning hole of the boss of the connecting piece to realize the positioning of the connecting piece and the upper and lower supports, the combined assembly is embedded into the groove by applying a pressure of 5 MPa by a hydraulic press, and the pressure is maintained for 10 s, the diameter of the positioning pin is 3 mm, the surface is plated with chromium, the plating layer is 0.01 mm thick, and the perpendicularity error after positioning is ≤±0.1 mm;

[0066] S4, strengthening and fixing and stress relief: aluminum core-pulling rivets are used for strengthening and fixing at the engaged parts of the connecting piece and the support, the diameter of the rivet is 3 mm, the riveting force is 300 N, after the strengthening and fixing is completed, aging treatment is carried out, the aging treatment temperature is 120 DEG C, the holding time is 2 h, and then the elastic arm of the connecting piece is subjected to shot peening strengthening treatment, the diameter of the steel shot is 0.2 mm, the jet pressure is 0.4 MPa, and the coverage is 100%;

[0067] S5, size calibration: the size of the overall combination is detected by a laser profiler, the relative position error is ≤±0.05 mm, and the detection area includes the bonding surface of the connecting piece and the upper support, the engaged part of the connecting piece and the lower support, and the matching part of the positioning pin and the hole;

[0068] S6, surface treatment: the overall assembly is subjected to phosphating treatment, the phosphating tank liquid temperature is 50 DEG C, the treatment time is 10 min, the film thickness is 3 μm, the exposed area of the connecting piece is coated with a polyurethane elastic coating containing 10% silicon carbide particles, the thickness is 0.1 mm, the pre-baking temperature is 80 DEG C, and the pre-baking time is 10 min, the remaining area of the support is subjected to electrostatic spraying treatment, an epoxy resin powder is used, the thickness is 0.15 mm, and the curing temperature is 180 DEG C, and the curing time is 15 min;

[0069] S7, final inspection: the size of the formed assembly is detected, and vibration test, tension test, wear resistance test and fatigue test are carried out at the same time, the vibration test frequency is 10 Hz, the amplitude is 0.5 mm, the duration is 24 h, the tension test applies 500 N axial force, keeps for 30 s, the wear resistance test load is 50 N, the friction speed is 0.5 m / s, the stroke is 1000 m, the wear loss is less than or equal to 0.01 g, the fatigue test applies ± 300 N alternating load, the frequency is 10 Hz, and the cycle is greater than or equal to 10 6 .

[0070] Example 2

[0071] A sheet metal forming combined process of an upper and lower support of a chef machine, comprising the following steps:

[0072] S1, blanking and pretreatment: cold-rolled steel plate is selected as the base material of the upper support and the lower support, spring steel is selected as the base material of the connecting piece, laser cutting is adopted to obtain the initial plate, the edges of the support plate are polished to remove burrs, the connecting piece plate is annealed at a temperature of 725 DEG C for 1 h, and then surface carburizing treatment is carried out at a temperature of 915 DEG C for 5 h, and the carburizing layer depth is 1.0 mm;

[0073] S2, support and connecting piece preforming and bending: the upper support and the lower support plate are sent into the stamping equipment respectively, the T-shaped positioning groove and the stepped boss are formed by stamping, and then bending treatment is carried out, the connecting piece plate is sent into the stamping die separately, the n-shaped structure with barb-shaped protrusions is formed by stamping, and a stress release groove is arranged at the transition between the elastic arm and the middle section, and then bending treatment is carried out;

[0074] The preparation process of the connecting piece is as follows: the spring steel raw material is selected for rolling, the oxide scale is removed after surface cleaning, the cleaned plate is laser cut to obtain the connecting piece initial blank, the first annealing is carried out on the blank at a temperature of 675 DEG C for 2.5 h, and the rolling stress is eliminated by furnace cooling, then the stamping preforming is carried out to form the preliminary n-shaped structure, the second annealing is carried out on the preformed piece at a temperature of 725 DEG C for 1 h to prepare for subsequent carburizing, and then quenching and low temperature tempering are carried out after carburizing, and then the tail bolt groove stamping die is used for final forming, the bending line avoids subsequent connection and positioning structure, the bending clearance of the 1.8 mm thick support is 1.2 times of the plate thickness, the pressure is 70 MPa, the bending angle is 90 DEG, and the connecting piece is treated by liquid nitrogen deep cooling after bending, the treatment temperature is-170 DEG C, and the insulation time is 1.5 h;

[0075] S3, assembly: after the upper support, the lower support and the connecting piece are completed, the barb-shaped protrusion of the connecting piece is aligned with the positioning groove of the lower support, the protrusion of the connecting piece is embedded into the groove of the lower support to form mechanical engagement, the positioning pin is inserted into the positioning hole of the protrusion of the connecting piece to realize the positioning of the connecting piece and the upper and lower supports, the assembly is subjected to 6.5 MPa pressure by a hydraulic press to embed the barb into the groove, the pressure is maintained for 12.5 s, the diameter of the positioning pin is 4 mm, the surface is plated with chromium, the plating thickness is 0.015 mm, and the verticality error after positioning is ≤±0.1 mm;

[0076] S4, reinforcement and stress relief: stainless steel cross slot screws are used to reinforce and fix the engagement part of the connecting piece and the support, the screw diameter is 4 mm, the tightening torque is 11.5 N·m, after the reinforcement and fixation are completed, the aging treatment is performed, the aging treatment temperature is 135℃, the holding time is 2 h, and then the elastic arm of the connecting piece is subjected to shot peening strengthening treatment, the steel shot diameter is 0.25 mm, the spraying pressure is 0.5 MPa, and the coverage is 100%;

[0077] S5, size calibration: the size of the overall assembly is detected by a laser profiler, the relative position error is ≤±0.05 mm, and the detection area includes the bonding surface of the connecting piece and the upper support, the engagement part of the connecting piece and the lower support, and the matching part of the positioning pin and the hole;

[0078] S6, surface treatment: the overall assembly is subjected to phosphating treatment, the phosphating tank temperature is 55℃, the treatment time is 12.5 min, the film thickness is 4 μm, the exposed area of the connecting piece is coated with a polyurethane elastic coating containing 12.5% silicon carbide particles, the thickness is 0.125 mm, the pre-baking temperature is 85℃, the pre-baking time is 10 min, the remaining area of the support is subjected to electrostatic spraying treatment, an epoxy resin powder is used, the thickness is 0.175 mm, and the curing temperature is 190℃, the curing time is 17.5 min;

[0079] S7, final inspection: the size of the formed assembly is detected, and vibration test, tension test, wear resistance test and fatigue test are simultaneously performed, the vibration test frequency is 30 Hz, the amplitude is 0.5 mm, the duration is 24 h, the tension test applies 650 N axial force for 30 s, the wear resistance test load is 75 N, the friction speed is 0.75 m / s, the stroke is 1000 m, and the wear loss is ≤0.01 g, the fatigue test applies ±300 N alternating load, the frequency is 15 Hz, and the cycle is ≥10 6 times.

[0080] Example 3

[0081] A sheet metal forming assembly process for the upper and lower supports of a chef machine includes the following steps:

[0082] S1, blanking and pretreatment: select cold-rolled steel plate as the base material of the upper support and the lower support, and spring steel as the base material of the connecting piece, use laser cutting to obtain the initial plate, polish the edges of the support plate to remove burrs, and anneal the connecting piece plate, annealing temperature 750℃, holding time 1h, then perform surface carburizing treatment, carburizing temperature 930℃, holding time 6h, carburizing layer depth 1.2mm;

[0083] S2, support and connecting piece preforming and bending: the upper support and lower support plate materials are respectively sent into the stamping equipment, and after the T-shaped positioning groove and stepped boss are formed by stamping, bending treatment is performed, the connecting piece plate material is separately sent into the stamping die, and after the n-shaped structure with barb-shaped protrusions is formed, a stress release groove is arranged at the transition between the elastic arm and the middle section, and then bending treatment is performed;

[0084] The preparation process of the connecting piece is as follows: select spring steel raw material for rolling, remove the oxide skin after surface cleaning, and then perform laser cutting on the cleaned plate to obtain the connecting piece initial blank, perform first annealing on the blank, temperature 700℃, holding time 3h, and cooling in the furnace to eliminate rolling stress, then perform stamping preforming to form a preliminary n-shaped structure, perform second annealing on the preformed piece, temperature 750℃, holding time 1h, prepare for subsequent carburizing, and then perform quenching and low-temperature tempering after carburizing, and then send it into the tail bolt groove stamping die for final forming, avoid the bending line from the subsequent connection and positioning structure, the bending gap of the 3mm thick support is 1.5 times the thickness of the plate, the pressure is 120MPa, the bending angle is 90°+0.2°, and the connecting piece is treated by liquid nitrogen deep cooling after bending, the treatment temperature is-160℃, and the holding time is 2h;

[0085] S3, assembly: after the upper support, lower support and connecting piece are all bent and formed, the barb-shaped protrusions of the connecting piece are aligned with the positioning groove of the lower support, the protrusions of the connecting piece are embedded in the groove of the lower support to form mechanical engagement, the positioning pin is inserted into the positioning hole of the boss of the connecting piece to realize the positioning of the connecting piece and the upper and lower supports, the assembly is embedded in the groove by applying 8MPa pressure by the hydraulic press, and the barb is kept for 15s, the diameter of the positioning pin is 5mm, the surface is plated with chromium, and the plating thickness is 0.02mm; the verticality error after positioning is ≤±0.1mm;

[0086] S4, reinforcement and stress relief: aluminum core-pulling rivets are used to reinforce and fix the engagement parts of the connecting piece and the support, the diameter of the rivet is 5mm, the riveting force is 500N, and after the reinforcement and fixation are completed, aging treatment is performed, the aging treatment temperature is 150℃, and the holding time is 2h, then the elastic arm of the connecting piece is treated by shot peening, the diameter of the steel shot is 0.3mm, the jet pressure is 0.6MPa, and the coverage is 100%;

[0087] S5, size calibration: the size of the overall combination is detected by a laser profiler, the relative position error is ≤±0.05mm, the detection area includes the fitting surface of the connecting piece and the upper support, the occlusion of the connecting piece and the lower support, and the matching part of the positioning pin and the hole;

[0088] S6, surface treatment: the overall assembly is phosphating treated, the phosphating tank liquid temperature is 60℃, the treatment time is 15min, the film thickness is 5μm, the exposed area of the connecting piece is coated with a polyurethane elastic coating containing 15% silicon carbide particles, the thickness is 0.15mm, 90℃ pre-baking for 10min, the remaining area of the support is electrostatically sprayed with epoxy resin powder, the thickness is 0.2mm, 200℃ curing for 20min;

[0089] S7, final inspection: the size of the formed assembly is detected, at the same time, vibration test, tension test, wear resistance test and fatigue test are carried out, the vibration test frequency is 50Hz, the amplitude is 0.5mm, the duration is 24h, the tension test applies 800N axial force, keeps for 30s, the wear resistance test load is 100N, the friction speed is 1m / s, the stroke is 1000m, the wear loss is ≤0.01g, the fatigue test applies ±300N alternating load, the frequency is 20Hz, the cycle is ≥10 6 times.

[0090] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sheet metal forming assembly process for the upper and lower supports of a food processor, characterized in that, Includes the following steps: S1. Blanking and pretreatment: Cold-rolled steel plate is selected as the base material for the upper and lower supports, and spring steel is selected as the base material for the connectors. The initial plate material is obtained by laser cutting. The edges of the support plate material are ground to remove burrs. The connector plate material is annealed and then surface carburized. S2. Pre-forming and bending of brackets and connectors: The upper and lower bracket plates are fed into the stamping equipment, and after stamping to form T-shaped positioning grooves and stepped bosses, they are bent. The connector plates are fed into the stamping die separately, and an n-shaped structure with barbed protrusions is formed. A stress relief groove is set at the transition between the elastic arm and the middle section, and then it is bent. S3. Assembly: After the upper bracket, lower bracket and connector are bent and formed, align the barbed protrusion of the connector with the positioning groove of the lower bracket, so that the protrusion of the connector is embedded in the groove of the lower bracket to form a mechanical engagement. The positioning pin is inserted into the positioning hole of the boss of the connector to realize the positioning of the connector and the upper and lower brackets. S4. Strengthening and Stress Relief: Strengthen and fix the interlocking parts of the connector and the bracket. After the reinforcement and fixation are completed, perform aging treatment, and then perform shot peening to strengthen the elastic arm of the connector. S5. Dimensional calibration: The dimensions of the assembled system are measured using a laser profilometer. S6. Surface treatment: Phosphate the entire component, apply an elastic coating to the exposed areas of the connectors, and perform electrostatic powder coating on the remaining areas of the bracket. S7. Final Inspection: Dimensional inspection of the molded components, as well as vibration testing, tensile testing, wear resistance testing, and fatigue testing.

2. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S1, the annealing temperature of the connector is 700-750℃, and the holding time is 1 hour; the carburizing temperature is 900-930℃, and the holding time is 4-6 hours; the depth of the carburized layer is 0.8-1.2 mm.

3. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S2, the manufacturing process of the connector includes the following steps: Spring steel raw materials are selected and rolled, and the surface is cleaned to remove oxide scale after rolling. The cleaned sheet metal is laser-cut to obtain the initial blank of the connector. The blank is then annealed for the first time at a temperature of 650-700℃ for 2-3 hours and then cooled in the furnace to eliminate rolling stress. Then, the part is pre-formed by stamping to form a preliminary n-shaped structure. The pre-formed part is then annealed for the second time at a temperature of 700-750℃ for 1 hour to prepare for subsequent carburizing. After carburizing, the material undergoes quenching and low-temperature tempering, and is then fed into the tail end slot stamping die for final shaping.

4. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S2, the connector is stamped to form an n-shaped structure, the length of its front flat section is consistent with the contact surface of the upper and lower brackets, the two ends are bent to form elastic arms, and the bottom of the connector is provided with a protruding limiting structure that is adapted to the positioning groove of the lower bracket.

5. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S2, the bending line avoids subsequent connection and positioning structures. The bending gap of the 1.5-2mm thick bracket is 1.2 times the plate thickness, and the pressure is 60-80MPa. The bending gap of the 2-3mm thick bracket is 1.5 times the plate thickness, and the pressure is 100-120MPa. The bending angle is 90°±0.2°. After the connector is bent, it is subjected to liquid nitrogen cryogenic treatment at a temperature of -180 to -160℃ for 1-2 hours.

6. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S3, the assembly is performed by applying a pressure of 5-8 MPa using a hydraulic press to embed the barbs into the groove and hold for 10-15 seconds. The positioning pin has a diameter of 3-5 mm, is chrome-plated, and has a plating thickness of 0.01-0.02 mm. After positioning, the perpendicularity error is ≤ ±0.1 mm.

7. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S4, the reinforcement and fixing are carried out using rivets or screws. The rivets are aluminum blind rivets with a diameter of 3-5mm and a riveting force of 300-500N. The screws are stainless steel Phillips head screws with a diameter of 3-5mm and a tightening torque of 8-15N·m. The aging treatment temperature is 120-150℃ and the heat treatment is maintained for 2 hours. The shot peening strengthening uses steel shot with a diameter of 0.2-0.3mm, a blasting pressure of 0.4-0.6MPa, and a coverage rate of 100%.

8. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S5, the relative position error detected by the laser profilometer is ≤0.05mm, and the detection area includes the mating surface of the connector and the upper bracket, the biting point of the connector and the lower bracket, and the mating part of the positioning pin and the hole.

9. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S6, the phosphating bath temperature is 50-60℃, the treatment time is 10-15 min, the film thickness is 3-5 μm, the elastic coating is polyurethane containing 10-15% silicon carbide particles, the thickness is 0.1-0.15 mm, the pre-baking time is 80-90℃ for 10 min, the electrostatic powder coating uses epoxy resin powder, the thickness is 0.15-0.2 mm, and the curing time is 180-200℃ for 15-20 min.

10. The sheet metal forming assembly process for the upper and lower supports of a food processor according to claim 1, characterized in that: In step S7, the vibration test frequency is 10-50Hz, the amplitude is 0.5mm, and the duration is 24h; the tensile test applies an axial force of 500-800N and holds for 30s; the wear resistance test load is 50-100N, the friction speed is 0.5-1m / s, the stroke is 1000m, and the wear amount is ≤0.01g; the fatigue test applies an alternating load of ±300N, the frequency is 10-20Hz, and the cycle is ≥10. 6 Second-rate.

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