Method and system for manufacturing a hot stamped steel part

Abstract

The application discloses a kind of roll hot forming steel part manufacturing method, comprising the following steps: step S1, pretreatment;Step S2, preform selection;Step S3, adjustment;Step S4, heating furnace heating;Step S5, cooling;Step S6, hot roll forming;Step S7, blanking.Simultaneously discloses a kind of roll hot forming steel part production system.The application can be flexibly used cold roll and hot roll forming, by optimizing the forming capacity of distribution cold roll forming unit and hot roll forming unit realizes the free switching of direct hot forming process and indirect hot forming process, greatly improves production efficiency, reduces the cost of production, can simultaneously satisfy the demand of various steel parts manufacturing process of different steel plate substrate as raw material, and the performance of steel parts produced can satisfy production demand.

Description

Technical Field

[0001] This invention relates to a method and production system for manufacturing hot-formed steel parts by roll forming, belonging to the field of hot-formed steel parts manufacturing technology. Background Technology

[0002] Currently, hot-formed steel components have a strength exceeding 1500 MPa and account for over 35% of the body-in-white of passenger vehicles. They are crucial components for automotive safety and lightweighting. Raw materials include bare steel sheets, aluminum-silicon hot-formed steel, and galvanized hot-formed steel. Aluminum-silicon and galvanized coated hot-formed steels, due to their resistance to high-temperature oxidation and corrosion, are increasingly used in vehicle bodies; currently, commercially available coated hot-formed steel accounts for over 70% of the total hot-formed steel production. Hot-formed steel components are primarily used in the bodies, chassis, and engines of passenger cars and trucks.

[0003] In the existing technology, the manufacturing process of hot-formed steel parts mainly includes two types: direct hot forming process and indirect hot forming process. The direct hot forming process involves heating the steel sheet to the austenitizing temperature and holding it at that temperature for a certain time before directly transferring it to a mold with a cooling system for stamping and pressure quenching, as exemplified by the invention patent entitled "A Method and Apparatus for Hot Roll Forming of Ultra-High Strength Steel (Application No.: CN201510408552.0)". The indirect hot forming process involves first cold stamping the steel sheet to pre-form a certain amount (generally 90-95%), then heating it to the austenitizing temperature, holding it at that temperature for a certain time, and then transferring it to a mold with a cooling system for final forming and quenching, as exemplified by the invention patent entitled "A High Strength Steel Roll Hot Forming Process (Application No.: CN201210525220.7)".

[0004] Currently, the production of hot-formed steel parts generally requires two production lines: one for direct hot forming and one for indirect hot forming, to meet the production process requirements of different raw materials. This significantly increases production costs, and traditional production processes have limited daily output. Therefore, we propose a roll forming hot-formed steel parts manufacturing method and production system that can flexibly adopt cold roll forming and hot roll forming. By optimizing the allocation of cold roll forming and hot roll forming amounts, the manufacturing of direct hot-formed parts or indirect hot-formed parts can be achieved, realizing an integrated process of austenitizing heating, hot forming, and cooling. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing hot-formed steel parts by roll forming, and a method for manufacturing hot-formed steel parts by roll forming. This invention can simultaneously realize direct and indirect hot forming production processes and indirect hot forming production processes, and improves production efficiency and reduces production costs.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for manufacturing hot-formed steel parts by roll forming, comprising the following steps:

[0007] Step S1, Pre-processing: After uncoiling the steel plate substrate, it is conveyed to the next stage;

[0008] Step S2, Select preforming: Select the total preforming deformation amount according to the type of steel plate substrate material of hot-formed steel. The total preforming deformation amount is 0%-95% of the total deformation amount of the part.

[0009] Step S3, Adjustment: Adjust the pre-formed blank using a looper device;

[0010] Step S4: Heating in the furnace;

[0011] Step S5, cooling;

[0012] Step S6, hot roll forming;

[0013] Step S7, punching.

[0014] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, in step S2, pre-forming is selected. When the raw material of the hot-formed steel plate substrate is bare hot-formed steel and the total deformation of the part is greater than 30%, or when the raw material of the hot-formed steel plate substrate is galvanized hot-formed steel and the total deformation of the part is greater than 20%, a cold forming roll forming unit is used for pre-forming. The total deformation of the pre-forming is greater than 0% of the total deformation of the part, and the total deformation of the pre-forming is less than or equal to 95% of the total deformation of the part.

[0015] When the raw material of the hot-formed steel plate is aluminum-based coated hot-formed steel, or the raw material of the hot-formed steel plate is bare hot-formed steel and the total deformation of the part is less than or equal to 30%, or the raw material of the hot-formed steel plate is galvanized hot-formed steel and the total deformation of the part is less than or equal to 20%, the roll gap of the cold forming roll press is raised, and pre-forming is not required. The total deformation of pre-forming is 0% of the total deformation of the part.

[0016] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, step S4 involves heating in a heating furnace, which employs one or more of the following methods: direct combustion heating, induction heating, and radiant tube heating.

[0017] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, when the heating furnace heats the pickled and cold-rolled hot-formed steel, the heating furnace adopts one or more of the following methods: direct-fired heating, radiant tube heating, and induction heating, and the furnace is filled with an inert protective atmosphere.

[0018] When heating aluminum-based coated hot-formed steel or galvanized hot-formed steel in the heating furnace, one or more of the following methods are used: direct combustion heating and radiant tube heating. The furnace is filled with air or an oxidizing atmosphere.

[0019] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, the cooling in step S5 employs one or a combination of air cooling, water mist cooling, or jet cooling.

[0020] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, in step S6, the hot roll forming uses a hot roll forming machine to form and quench the billet. The billet temperature in the first hot roll forming equipment of the hot roll forming machine is 450-800℃, and the billet temperature in the last hot roll forming equipment of the hot roll forming machine is less than or equal to 150℃.

[0021] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, the rolls of the hot roll forming unit have a built-in cooling water system, and a water spray system can be set on both sides of the roll gap to achieve roll quenching and cooling by controlling the water volume and flow rate.

[0022] The aforementioned method for manufacturing hot-formed steel parts by roll forming includes the following raw materials for the steel plate substrate: pickled bare hot-formed steel, cold-rolled bare hot-formed steel, galvanized hot-formed steel, aluminum-based coated hot-formed steel, duplex steel, and multiphase steel.

[0023] The zinc layer of the galvanized hot-formed steel is one of pure zinc, zinc-aluminum-magnesium, and zinc alloy coatings; the coating of the aluminum-silicon hot-formed steel is one of aluminum-silicon, aluminum-silicon-magnesium, and aluminum-silicon-copper coatings.

[0024] The thickness of the steel plate substrate is 0.8-5mm, and the tensile strength is 350-1000MPa.

[0025] In the aforementioned method for manufacturing hot-formed steel parts by roll forming, the composition of the steel substrate is as follows:

[0026] C: 0.15-0.40 wt%;

[0027] Si: 0.08-1.8 wt%;

[0028] Mn: 0.3-12.00wt%;

[0029] Al: 0.03-1.20 wt%;

[0030] Cr: 0.02-0.65 wt%;

[0031] Mo: 0.00-1.12 wt%;

[0032] Nb, V and Ti: 0.10-0.55 wt%;

[0033] B: 0.0001-0.005 wt%;

[0034] S: ≤0.012wt%;

[0035] P: ≤0.08wt%;

[0036] The remainder consists of Fe and unavoidable impurities.

[0037] A roll forming hot forming steel parts production system, wherein the production system is arranged in sequence according to the conveying direction of the substrate in the production of steel parts, including an uncoiling device, a cold roll forming unit, a looper device, a heating furnace, a cooling device, a hot roll forming unit, and a punching device.

[0038] The gap between the rollers in the roller pressing section of the cold roller press unit can be lifted;

[0039] The heating methods of the furnace include direct combustion heating, induction heating, and radiant tube heating;

[0040] An air-cooling section is provided between the heating furnace and the cooling device;

[0041] The cooling device employs water mist or jet cooling;

[0042] The hot roll press unit has a built-in cooling water system with controllable water volume in the rolls, and water spraying systems can be installed on both sides of the roll gap.

[0043] Compared with the prior art, the present invention uses a cold forming roll press to preform the material, which solves the problem of cracking during the forming process and further improves the yield. When producing hot-formed steel strip raw materials with a tensile strength of 800-900MPa, the roll gap of the cold forming roll press can be lifted, and the steel plate substrate can pass directly through the cold forming roll press, avoiding the risk of stamping cracking that is easy to occur during preforming.

[0044] The heating furnace uses one or more of the following methods for heating: direct combustion heating, induction heating, and radiant tube heating. The heating furnace can select the heating method according to the material of the steel plate substrate. It adopts an online roll forming production method, which greatly reduces the wear of the furnace rollers and improves the production efficiency. In addition, since the contact position and area between the upper and lower surfaces of the plate and the furnace rollers are similar, the heating uniformity of the plate is improved.

[0045] The hot roll press unit has a built-in cooling water system on the rolls, which can control the water volume to achieve roll quenching cooling. By controlling the number and distribution of hot roll bending units with and without water supply, as well as the amount of cooling water, the hot roll bending deformation and quenching rate can be adjusted, thereby achieving effective control over the shape accuracy and mechanical properties of the parts. In addition, when producing complex cross-section or closed-end parts, in order to improve the uniformity of cooling, a water spray system is set on both sides of the roll gap, further improving the control capability of cooling speed and cooling uniformity.

[0046] This invention optimizes the allocation of cold and hot rolling forming amounts, enabling free selection between direct and indirect hot forming parts manufacturing processes. The two processes can be easily and quickly switched, greatly improving equipment utilization and production efficiency, reducing production costs, and realizing an integrated production process of austenitizing heating, hot forming, and cooling. It can simultaneously meet the manufacturing process requirements of various steel parts made from different steel plates and substrates, and the properties of the produced steel parts can meet production requirements. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the production system of the present invention.

[0048] Reference numerals: 1-Uncoiling device, 2-Cold roll press unit, 3-Looper device, 4-Heating furnace, 5-Cooling device, 6-Hot roll press unit, 7-Blanking device, 8-Air cooling section.

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0050] Embodiment 1 of the present invention: A method for manufacturing hot-formed steel parts by roll forming, comprising the following steps:

[0051] Step S1, Pre-processing: After uncoiling the steel plate substrate, it is conveyed to the next stage;

[0052] Step S2, Select preforming: Select the total deformation amount of preforming according to the type of steel plate substrate raw material of hot-formed steel. The total deformation amount of preforming is 0%-95% of the total deformation amount of the part. The total deformation amount of preforming is the total deformation amount of the steel plate substrate after preforming. The total deformation amount of the part is the total deformation amount of the steel plate substrate after processing into the part.

[0053] Step S3, Adjustment: Adjust the pre-formed blank using a looper device;

[0054] Step S4: Heating in the furnace;

[0055] Step S5, cooling;

[0056] Step S6, hot roll forming;

[0057] Step S7, punching.

[0058] Specifically, in step S2, preforming is selected. When the raw material of the hot-formed steel plate is bare hot-formed steel and the total deformation of the part is greater than 30%, or when the raw material of the hot-formed steel plate is galvanized hot-formed steel and the total deformation of the part is greater than 20%, a cold forming roll forming unit is used for preforming. The total deformation of the preforming is greater than 0% of the total deformation of the part, and the total deformation of the preforming is less than or equal to 95% of the total deformation of the part. The total deformation of the preforming is selected according to the actual needs of part production. When the raw material of the hot-formed steel plate is aluminum-based coated hot-formed steel, or when the raw material of the hot-formed steel plate is bare hot-formed steel and the total deformation of the part is less than or equal to 30%, or when the raw material of the hot-formed steel plate is galvanized hot-formed steel and the total deformation of the part is less than or equal to 20%, a cold forming roll forming unit is used for preforming. At 20%, the roll gap of the cold forming roll press is raised, and preforming is not required. The total deformation of the preforming is 0% of the total deformation of the part. The total deformation of the cold forming roll press can be reasonably designed according to the part structure, generally ≤95% of the total deformation, and the remaining at least 5% of the total deformation is shaped in the hot roll forming part. Using the roll forming method of the cold forming roll press for preforming solves the problem of cracking in the forming of raw materials and further improves the yield. When producing hot-formed steel strip raw materials with tensile strength usually reaching 800-900MPa, preforming is prone to stamping cracking, which greatly reduces the yield. The roll gap of the roll pressing stage of the cold forming roll press can be raised, and the steel plate substrate can be directly passed through the cold forming roll press, avoiding the risk of stamping cracking that is prone to occur in preforming.

[0059] Specifically, in step S3, the looper is of one type: deep pit, vertical, or horizontal. The looper enhances the flexibility of online production, and the storage length can be selected according to the parts to be manufactured.

[0060] Specifically, in step S4, the heating furnace is used for heating. The heating furnace adopts one or more of the following methods: direct combustion heating, induction heating, and radiant tube heating. The heating furnace can select the heating method according to the material of the steel plate substrate. When heating pickled or cold-rolled hot-formed steel, the heating furnace adopts one or more of the following methods: direct combustion heating, radiant tube heating, and induction heating. The heating furnace is inert protective atmosphere, and nitrogen can be selected as the inert gas. When heating aluminum-based coated hot-formed steel or galvanized hot-formed steel, the heating furnace adopts one or more of the following methods: direct combustion heating and radiant tube heating. The heating furnace is in air or oxidizing atmosphere, wherein the oxygen volume content is greater than or equal to 15%, and the dew point temperature is between -20°C and 20°C.

[0061] Traditional hot forming processes typically employ a roller hearth furnace for heating, where sheet metal is conveyed by rolling furnace rollers. In the production of coated hot-formed steel, the high heating temperature and the corrosive nature of the coating, coupled with the large contact area between the furnace rollers and the sheet metal, make the rollers prone to corrosion, nodules, and damage, increasing production costs and reducing efficiency. Step 4 above utilizes an online rolling process where the coiled material inside the furnace is under tension. The sheet metal only needs to contact a small number of tension rollers, guide rollers, and support rollers within the furnace, significantly reducing furnace roller wear and improving production efficiency. Furthermore, because the contact positions and areas between the upper and lower surfaces of the sheet metal and the furnace rollers are roughly equal, the heating uniformity of the sheet metal is improved, achieving a temperature uniformity of ±3℃ across the upper surface, lower surface, and length direction.

[0062] Specifically, in step S5, cooling is achieved using one or a combination of air cooling, water mist cooling, or jet cooling, with a temperature drop of 50-300℃ for each part. An air cooling section is provided between the heating furnace and the cooling device, which uses water mist or jet cooling. Generally, pickled bare hot-formed steel, cold-rolled bare hot-formed steel, and some aluminum-based coated hot-formed steel parts with simple cross-sections are directly air-cooled after heating. For galvanized hot-formed steel and aluminum-based coated hot-formed steel with complex shapes, after air cooling is completed, they are further cooled by water mist or jet cooling using a cooling device.

[0063] Specifically, in step S6, hot roll forming uses a hot roll press unit to form and quench the billet. The billet temperature in the first hot roll press unit is 450-800℃, and the billet temperature in the last hot roll press unit is less than or equal to 150℃. The rolls of the hot roll press unit have a built-in cooling water system, and water spraying systems can be set on both sides of the roll gap. Roll quenching and cooling are achieved by controlling the water volume and flow rate.

[0064] When the cooling water channels of the built-in cooling water system of the hot roll press are not circulated, traditional hot roll bending can be achieved, and the cooling rate of the sheet metal is generally ≤20℃ / s. When the cooling water channels of the built-in cooling water system of the hot roll press are circulated, hot roll bending and roll quenching can be achieved, and the quenching cooling rate can reach more than 30℃ / s. By controlling the number and distribution of hot roll bending units with and without water, as well as the amount of cooling water, the hot roll bending deformation and quenching cooling rate can be adjusted, thereby achieving effective control over the shape accuracy and mechanical properties of the parts. The tensile strength of the parts produced after punching reaches 800-2100MPa, meeting the requirements of automotive parts, photovoltaics, construction and other fields.

[0065] Specifically, the raw materials for the steel plate substrate in this invention include pickled bare hot-formed steel, cold-rolled bare hot-formed steel, galvanized hot-formed steel, aluminum-based coated hot-formed steel, duplex steel, and multiphase steel.

[0066] The zinc layer of galvanized hot-formed steel is one of pure zinc, zinc-aluminum-magnesium, or zinc alloy coating; the coating of aluminum-silicon hot-formed steel is one of aluminum-silicon, aluminum-silicon-magnesium, or aluminum-silicon-copper coating.

[0067] The thickness of the steel plate substrate is 0.8-5mm, and the tensile strength is 350-1000MPa.

[0068] The composition of the steel plate substrate is as follows:

[0069] C: 0.15-0.40 wt%;

[0070] Si: 0.08-1.8 wt%;

[0071] Mn: 0.3-12.00wt%;

[0072] Al: 0.03-1.20 wt%;

[0073] Cr: 0.02-0.65 wt%;

[0074] Mo: 0.00-1.12 wt%;

[0075] Nb, V and Ti: 0.10-0.55 wt%;

[0076] B: 0.0001-0.005 wt%;

[0077] S: ≤0.012wt%;

[0078] P: ≤0.08wt%;

[0079] The remainder consists of Fe and unavoidable impurities.

[0080] In actual production, based on different steel plate substrate materials and coating types, nine experimental groups were set up using the production process of this invention, and compared with control groups using traditional direct thermoforming or indirect thermoforming production processes, as detailed below:

[0081] Table 1: Comparison of Materials, Overall Process Steps, and Production Capacity between Experimental and Control Groups

[0082]

[0083] As shown in Table 1, the experimental group adopted the production process of the present invention, while the control group adopted the traditional direct thermoforming production process or indirect thermoforming production process. The experimental group adopted a continuous production method and achieved an hourly capacity of 1600 pieces / h, which was significantly higher than the hourly capacity of 240 pieces / h of the control group.

[0084] Table 2: Comparison Table of Loop Length and Cold Roll Pressing Process Parameters

[0085]

[0086]

[0087] As shown in Table 2, the present invention can flexibly adopt direct thermoforming and indirect thermoforming. When using indirect thermoforming, cold roll forming is used for preforming, and the forming speed is as high as 30m / min. It can also make the yield of high-strength steel base materials 22MnB and 34MnB5 reach 98%, which meets the production requirements. At the same time, compared with the yield of 95% when using traditional cold stamping forming in control group 2, it can be seen that when the present invention implements the indirect thermoforming process, it improves the efficiency and material utilization rate.

[0088] Table 3: Comparison of Austenitizing Heating Process Parameters and Furnace Atmosphere

[0089]

[0090] As shown in Table 3, the raw material strip of the steel plate substrate of the present invention is subjected to tension in the furnace. The upper and lower surfaces of the strip have the same heating area and the heat transfer mode is consistent. The strip can be heated uniformly, and the temperature uniformity is controlled between ±1 and ±4℃. In the conventional process of the control group, the parts are placed in the roller hearth furnace or box furnace roller or furnace chamber, and it is difficult to heat evenly. The temperature uniformity is generally controlled within ±5 to ±8℃.

[0091] Table 4: Comparison Table of Cooling Process Parameters

[0092]

[0093] As shown in Table 4, the production process of this invention adopts a fully continuous production method. When pre-cooling is carried out before hot roller bending, there is no need to add a robot arm for loading and unloading. It can achieve the required temperature drop of 50-300℃, and greatly improves production efficiency and reduces production investment.

[0094] Table 5: Comparison Table of Hot Roll Bending Process Parameters

[0095]

[0096]

[0097] As shown in Table 5, the production process of the present invention uses cooling water built into the hot roll bending roll for cooling. The cooling rate of the experimental group is comparable to that of the control group, and both can meet the requirements of the critical cooling rate of hot forming steel.

[0098] Table 6: Comparison Table of Mechanical Properties of Parts

[0099]

[0100] As shown in Table 6, the production process of the present invention uses hot roll bending to produce pickled, cold-rolled, galvanized and aluminum-silicon coated hot-formed steel, as well as cold-rolled ultra-high-strength steel. This production method can significantly reduce the brittleness of liquid metal, that is, reduce the chance of liquid or gaseous surface coating metal forming in the enclosed space of the mold and sheet and penetrating into the coating gaps and entering the substrate material, thereby improving the elongation of the parts.

[0101] In summary, this invention optimizes the allocation of cold and hot rolling forming amounts, enabling free selection between direct and indirect hot forming parts manufacturing processes. The two processes can be easily and quickly switched, greatly improving equipment utilization and production efficiency, reducing production costs, and realizing an integrated production process of austenitizing heating, hot forming, and cooling. This process can simultaneously meet the manufacturing needs of various steel parts made from different steel plates, and the properties of the produced steel parts all meet production requirements.

[0102] Embodiment 2 of the present invention: A roll forming hot forming steel parts production system, wherein the production system is arranged in sequence according to the conveying direction of the substrate in the production of steel parts, including an uncoiling device 1, a cold roll forming unit 2, a looper device 3, a heating furnace 4, a cooling device 5, a hot roll forming unit 6, and a blanking device 7; the roll gap of the cold roll forming unit 2 can be lifted; the heating method of the heating furnace 4 includes direct combustion heating, induction heating, and radiant tube heating; an air cooling section 8 is provided between the heating furnace 4 and the cooling device 5; the cooling device 5 adopts water mist or air jet cooling; the rolls of the hot roll forming unit 6 are equipped with a cooling water system with controllable water volume, and a water spray system can be set on both sides of the roll gap.

[0103] When direct hot forming of parts is required during production, the roll gap of the cold roll press 2 is raised, the steel plate is uncoiled, and it passes through the cold roll press 2 and looper 3 online. After being heated to a temperature higher than the austenitizing temperature and held at that temperature in the heating furnace 4, it enters the cooling device 5 after a period of air cooling in the air cooling section 8. The use of the cooling device 5 for cooling can be selected according to the requirements. The hot roll press 6 with built-in cooling water system directly hot rolls the parts and then completes the production through the punching device 7.

[0104] When the indirect hot forming method is required for manufacturing parts during the production process, the steel plate is first uncoiled and then cold-formed into a certain shape by the cold roll press 2. After passing through the looper 3, it is heated to a temperature higher than the austenitizing temperature by the heating furnace 4. After a period of air cooling in the air cooling section 8, it enters the cooling device 5. The use of the cooling device 5 for cooling can be selected according to the requirements. After heat preservation, it is hot-stamped or hot-formed into parts by the hot roll press 6 with a built-in cooling water system. The production is completed by the blanking device 7.

[0105] The working principle of one embodiment of the present invention is as follows: The present invention can flexibly adopt cold roll forming and hot roll forming. By optimizing the forming volume of the cold roll forming unit and the hot roll forming unit, the direct hot forming process and the indirect hot forming process can be freely switched, realizing the integrated process of austenitizing heating, hot forming and cooling. At the same time, the production method of online roll forming is adopted. The coil in the heating furnace is under tension. The sheet only needs to contact a small number of tension rollers, guide rollers and support rollers in the furnace, which greatly reduces furnace roller wear and improves production efficiency. In addition, since the contact position and area between the upper and lower surfaces of the sheet and the furnace rollers are similar, the heating uniformity of the sheet is improved. Moreover, the rolls of the hot roll forming unit have a built-in cooling water system, which can control the water volume to achieve roll quenching and cooling. The present invention greatly improves production efficiency, reduces production costs, and can simultaneously meet the manufacturing process requirements of various steel parts made of different steel plate substrates. The various properties of the produced steel parts can meet the production requirements.

Claims

1. A method for manufacturing hot-formed steel parts by roll forming, characterized in that, Includes the following steps: Step S1, Pre-processing: After uncoiling the steel plate substrate, it is conveyed to the next stage; Step S2, Select preforming: Select the total preforming deformation amount according to the type of steel plate substrate material of hot-formed steel. The total preforming deformation amount is 0%-95% of the total deformation amount of the part; Step S3, Adjustment: Adjust the pre-formed blank using a looper device; Step S4: Heating in the furnace; Step S5, cooling; Step S6, hot roll forming; Step S7, punching; In step S2, preforming is selected. When the raw material of the hot-formed steel plate substrate is bare hot-formed steel and the total deformation of the part is greater than 30%, or when the raw material of the hot-formed steel plate substrate is galvanized hot-formed steel and the total deformation of the part is greater than 20%, a cold forming roll forming unit is used for preforming. The total deformation of the preforming is greater than 0% of the total deformation of the part, and the total deformation of the preforming is less than or equal to 95% of the total deformation of the part. When the raw material of the hot-formed steel plate substrate is aluminum-based coated hot-formed steel, or when the raw material of the hot-formed steel plate substrate is bare hot-formed steel and the total deformation of the part is less than or equal to 30%, or when the raw material of the hot-formed steel plate substrate is galvanized hot-formed steel and the total deformation of the part is less than or equal to 20%, the roll gap of the cold forming roll press unit is raised, and pre-forming is not required. The total deformation of pre-forming is 0% of the total deformation of the part.

2. The method for manufacturing hot-formed steel parts by roll forming according to claim 1, characterized in that, In step S4, the heating furnace is used for heating, and the heating furnace adopts one or more of the following methods: direct combustion heating, induction heating, and radiant tube heating.

3. The method for manufacturing hot-formed steel parts by roll forming according to claim 2, characterized in that, When the heating furnace heats pickled and cold-rolled hot-formed steel, the heating furnace adopts one or more of the following methods: direct-fired heating, radiant tube heating, and induction heating. The furnace is filled with an inert protective atmosphere. When heating aluminum-based coated hot-formed steel or galvanized hot-formed steel in the heating furnace, one or more of the following methods are used: direct combustion heating and radiant tube heating. The furnace is filled with air or an oxidizing atmosphere.

4. The method for manufacturing hot-formed steel parts by roll forming according to claim 1, characterized in that, The cooling process in step S5 employs one or a combination of two cooling methods: air cooling, water mist cooling, or jet cooling.

5. The method for manufacturing hot-formed steel parts by roll forming according to claim 1, characterized in that, In step S6, the hot roll forming uses a hot roll press to form and quench the billet. The rolls of the hot roll press are equipped with a cooling water system that can control the amount of water. The billet temperature in the first hot roll pressing equipment of the hot roll press is 450-800℃, and the billet temperature in the last hot roll pressing equipment of the hot roll press is less than or equal to 150℃.

6. The method for manufacturing hot-formed steel parts by roll forming according to claim 5, characterized in that, The hot roll press unit has a built-in cooling water system for the rolls, and water spray systems can be installed on both sides of the roll gap to achieve roll quenching and cooling by controlling the water volume and flow rate.

7. The method for manufacturing hot-formed steel parts by roll forming according to claim 1, characterized in that, The raw material of the steel plate substrate is one of pickled bare hot-formed steel, cold-rolled bare hot-formed steel, galvanized hot-formed steel, aluminum-based coated hot-formed steel, duplex steel, or multiphase steel. The zinc layer of the galvanized hot-formed steel is one of pure zinc, zinc-aluminum-magnesium, or zinc alloy coating, and the coating of the aluminum-based coated hot-formed steel is one of aluminum-silicon, aluminum-silicon-magnesium, or aluminum-silicon-copper coating. The thickness of the steel plate substrate is 0.8-5mm, and the tensile strength is 350-1000MPa.

8. The method for manufacturing hot-formed steel parts by roll forming according to claim 7, characterized in that, The steel plate substrate has the following composition: C: 0.15-0.40wt% Si: 0.08-1.8wt% Mn: 0.3-12.00wt% Al: 0.03-1.20 wt% Cr: 0.02-0.65 wt% Mo: 0.00-1.12 wt% Nb, V and Ti: 0.10-0.55 wt%; B: 0.0001-0.005wt%; S: ≤0.012wt% P: ≤0.08wt% The remainder consists of Fe and unavoidable impurities.

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