Process for manufacturing light-weight battery frame by using ultra-high-strength rectangular steel tube

Abstract

The invention discloses a process for manufacturing a light-weight battery frame by using an ultrahigh-strength rectangular steel pipe, and relates to the field of manufacturing of electric automobile parts, and the process comprises the following steps: 01, material selection: selecting hot-rolled steel plates with chemical components specified in different specifications according to different strength requirements, and manufacturing the rectangular steel pipe with a specified section size by forming and welding production equipment; 02, heat treatment strengthening is conducted, specifically, the metallographic structure of the material subjected to electromagnetic induction heating quenching is converted into all quenched martensite or quenched martensite and a small amount of undissolved ferrite from pearlite in the original hot rolling state and ferrite; 03, a lightweight battery frame assembly is welded through a carbon dioxide arc welding technology, a plasma welding technology, a laser welding technology or a bolt connection technology; the battery frame is manufactured by the rectangular steel pipes which are used for controlling the material component range and are subjected to electromagnetic induction quenching strengthening, and due to high material strength, light-weight designs such as thinning and specification reduction can be realized, and the light weight of a frame assembly is realized.

Description

Technical Field

[0001] The invention relates to the field of electric vehicle parts manufacturing, and relates to a process for manufacturing a lightweight battery frame by using ultra-high-strength rectangular steel pipes. Background Art

[0002] The battery frame of electric commercial vehicles is large in size. The common battery frames on the market are made of hot-rolled plates such as Q235, Q345, and 510L, which are formed and welded into rectangular steel pipes. The common hot-rolled plates such as Q235, Q345, 16Mn, 510L and 750L on the market are made into steel pipes, which are used in the hot-rolled state and have low strength levels (tensile strength is below 1000MPa). As a result, the weight of the supported product assembly is relatively large. In order to meet the use requirements, the specifications with increased wall thickness and larger overall dimensions must be adopted, resulting in heavy weight and unable to meet the increasingly high standards of lightweight requirements for automobiles. Therefore, the development of lightweight technology has significant economic and social benefits. Summary of the invention

[0003] The present invention aims to overcome the deficiencies of the prior art and proposes a process for making lightweight battery frames using ultra-high-strength rectangular steel tubes. Through the invention, a series of ultra-high-strength rectangular steel tubes are produced for manufacturing battery frames for commercial vehicles. Ultra-high-strength rectangular steel tubes with smaller dimensions or thinner walls can be used to replace the original "ordinary strength", "higher strength" and "high strength" grade steel tubes, thereby achieving high-standard lightweighting of the battery frame and reducing the vehicle's own weight.

[0004] To achieve the above object, the technical solution adopted by the present invention is: a process for making a lightweight battery frame using ultra-high strength rectangular steel pipes, comprising the following steps:

[0005] The selection of raw materials stipulates that the carbon content of 0.08-0.20%, 0.21-0.30%, 0.31-0.38% of the chemical composition of the general carbon plate as the raw material;

[0006] 01. Material selection: Select hot-rolled steel plates with different specifications and chemical compositions according to different strength requirements, and make them into rectangular steel pipes with specified cross-sectional dimensions through forming and welding production equipment;

[0007] 02. Heat treatment strengthening: The electromagnetic induction heating quenching process is used for heat treatment strengthening. The formed rectangular steel pipe is induction heated on the induction quenching machine. The heating temperature is 870-900℃ and the heating rate is 50-100℃ / S. After reaching the temperature, the quenching liquid is sprayed for rapid cooling. The metallographic structure of the material after induction heating quenching is transformed from the original hot-rolled pearlite plus ferrite to all quenched martensite or quenched martensite plus a small amount of undissolved ferrite.

[0008] 03. According to the different carbon content of the selected materials, rectangular steel tubes with different strength levels can be obtained after heat treatment and strengthening. The material with a carbon content of 0.08-0.20% has a strength of 1000-1300MPa after quenching; the material with a carbon content of 0.21-0.30% has a strength of 1200-1500MPa after quenching; the material with a carbon content of 0.31-0.38% has a strength of 1400-1700MPa after quenching. Rectangular steel tubes with different strengths can meet the use requirements under different stress conditions.

[0009] 04. The rectangular steel pipe strengthened by electromagnetic induction heat treatment is cut into a certain length and structural shape according to the drawings, and assembled into a lightweight battery frame assembly by carbon dioxide shielded welding, plasma welding, laser welding or bolt connection.

[0010] Furthermore, the process form of electromagnetic induction heating quenching is a continuous scanning heating form. This heat treatment rectangular form is suitable for the heat treatment of slender parts. While scanning heating, scanning water spray quenching cooling is carried out.

[0011] Furthermore, continuous scanning rectangular heating is adopted, and the heating width depends on the length of the effective circle of the inductor. Appropriate optimization can be carried out in actual production, and the actual heating and quenching area can be controlled. By adjusting the heating and quenching area, the production efficiency and the deformation of the rectangular steel pipe can be optimized.

[0012] Furthermore, martensite has higher strength, and the rectangular steel tube is structurally strengthened after quenching.

[0013] Furthermore, the chemical composition and range are: silicon Si: 0.17-1.37%, manganese Mn: 0.35-0.657%, phosphorus P: 0.0357%, sulfur S: ≤0.037%, chromium Cr: ≤0.27%, nickel Ni: ≤0.37%, copper Cu: ≤0.257%.

[0014] The beneficial effects of the present invention are:

[0015] The invention uses a series of ultra-high-strength rectangular steel tubes for manufacturing commercial vehicle battery frames. Ultra-high-strength rectangular steel tubes with smaller dimensions or thinner walls can replace the original "normal strength", "higher strength" and "high strength" grade steel tubes, thereby achieving high-standard lightweighting of the battery frame and reducing the vehicle's own weight.

[0016] The present invention uses a rectangular steel tube with a controlled material composition range and strengthened by electromagnetic induction quenching to manufacture the battery frame. Due to the high strength of the material, lightweight designs such as thinning and reducing specifications can be achieved, thereby achieving lightweight frame assembly.

[0017] After electromagnetic induction heating and quenching, the metallographic structure of the material changes from the original pearlite plus ferrite to quenched martensite or quenched martensite plus a small amount of undissolved ferrite. Since martensite has a high strength, the rectangular steel tube is effectively strengthened after quenching. The steel material with the chemical composition formulated by the present invention obtains ultra-high strength after electromagnetic induction quenching, and the manufactured product assembly has a significant lightweight effect.

[0018] Electromagnetic induction heating quenching is the most common and effective process for strengthening steel, and is used in mechanical products. However, it is rarely used in the strengthening of rectangular steel pipes, and is partially used in cement pump pipes to improve their wear resistance.

[0019] The structural feature of the present invention is also that large-sized steel pipes are replaced by small-sized ones.

[0020] Depending on the carbon content of the material, rectangular steel tubes with different strength levels can be obtained.

[0021] 1. The strength of materials with a carbon content of 0.08-0.20% after quenching is 1000-1300MPa.

[0022] 2. The strength of materials with a carbon content of 0.21-0.38% after quenching is 1200-1500MPa.

[0023] 3. The strength of materials with a carbon content of 0.31-0.38% after quenching is 1400-1700MPa.

[0024] The invention has significant economic and social benefits. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] A process for making a lightweight battery frame using an ultra-high strength rectangular steel pipe comprises the following steps: selecting a carbon plate containing a chemical composition with a carbon content of 0.08-0.20%, 0.21-0.30%, or 0.31-0.38% as the raw material;

[0027] 01. Material selection: Select hot-rolled steel plates with different specifications and chemical compositions according to different strength requirements, and make them into rectangular steel pipes with specified cross-sectional dimensions through forming and welding production equipment;

[0028] 02. Heat treatment strengthening: The electromagnetic induction heating quenching process is used for heat treatment strengthening. The formed rectangular steel pipe is induction heated on the induction quenching machine. The heating temperature is 870-900℃ and the heating rate is 50-100℃ / S. After reaching the temperature, the quenching liquid is sprayed for rapid cooling. The metallographic structure of the material after electromagnetic induction heating quenching is transformed from the original hot-rolled pearlite plus ferrite to all quenched martensite or quenched martensite plus a small amount of undissolved ferrite.

[0029] 03. According to the different carbon content of the selected materials, rectangular steel tubes with different strength levels can be obtained after heat treatment and strengthening. The material with a carbon content of 0.08-0.20% has a strength of 1000-1300MPa after quenching; the material with a carbon content of 0.21-0.30% has a strength of 1200-1500MPa after quenching; the material with a carbon content of 0.31-0.38% has a strength of 1400-1700MPa after quenching. Rectangular steel tubes with different strengths can meet the use requirements under different stress conditions.

[0030] 04. The rectangular steel pipe strengthened by electromagnetic induction heat treatment is cut into a certain length and structural shape according to the drawings, and assembled into a lightweight battery frame assembly by carbon dioxide shielded welding, plasma welding, laser welding or bolt connection.

[0031] Preferably, the process form of electromagnetic induction heating quenching is a continuous scanning heating form. This heat treatment rectangular form is suitable for the heat treatment of slender parts. While scanning heating, scanning water spray quenching cooling is performed.

[0032] Preferably, continuous scanning rectangular heating is adopted, and the heating width depends on the length of the effective circle of the inductor. Appropriate optimization can be carried out in actual production, and the actual heating and quenching area can be controlled. By adjusting the heating and quenching area, the production efficiency and the deformation of the rectangular steel pipe can be optimized.

[0033] Preferably, martensite has higher strength, and the rectangular steel tube is structurally strengthened after quenching.

[0034] Preferably, the chemical composition and range are: silicon Si: 0.17-1.37%, manganese Mn: 0.35-0.657%, phosphorus P: 0.0357%, sulfur S: ≤0.037%, chromium Cr: ≤0.27%, nickel Ni: ≤0.37%, copper Cu: ≤0.257%.

[0035] Case 1: A light electric truck battery frame is made of rectangular steel tubes with a carbon content of 0.08-0.20% and a strength of 1000-1300MPa after quenching. The shape specification is 30*50*2.5, which replaces the "ordinary strength" rectangular steel tubes of 60*60*2.5 Q345 material. The lightweight effect is a 33% weight reduction. This is a weight reduction method using "smaller overall dimensions".

[0036] Case 2:

[0037] The medium-sized electric truck battery frame is made of rectangular steel tubes with a carbon content of 0.21-0.30% and a strength of 1200-1500MPa after quenching. The shape specification is 60*60*3.0, which replaces the "higher strength" rectangular steel tubes of 60*60*4.0 510L material. The lightweight effect is a 25% weight reduction. This is a weight reduction method using "thinner thickness".

[0038] Case 3: A heavy-duty electric truck battery frame is made of rectangular steel tubes with a carbon content of 0.31-0.38% and a strength of 1400-1700MPa after quenching. The shape specification is 50*70*3.5, which replaces the "high-strength" rectangular steel tubes of 60*80*4.0 made of 750L material. The lightweight effect is a 25% weight reduction. This is a comprehensive weight reduction method using "smaller overall dimensions" and "thinner thickness".

[0039] After electromagnetic induction heating and quenching, the metallographic structure of the material changes from the original pearlite plus ferrite to quenched martensite or quenched martensite plus a small amount of undissolved ferrite. Since martensite has a high strength, the rectangular steel tube is effectively strengthened after quenching. The steel material with the chemical composition formulated by the present invention obtains ultra-high strength after electromagnetic induction quenching, and the manufactured product assembly has a significant lightweight effect.

[0040] Electromagnetic induction heating quenching is the most common and effective process for strengthening steel, and is widely used in mechanical products; however, it is rarely used in the strengthening of rectangular steel pipes, and is partially used in cement pump pipes to improve their wear resistance.

[0041] The steel pipes made of hot-rolled plates such as Q235, Q345, 16Mn, 510L and 750L commonly seen in the market are all used in the hot-rolled state, and the strength level is not high (the tensile strength is all below 1000MPa), which makes the weight of the supported product assembly relatively large.

Claims

1. A process for making a lightweight battery frame using ultra-high strength rectangular steel pipes, characterized in that: The following steps are involved: The selection of raw materials stipulates that the carbon content of 0.08-0.20%, 0.21-0.30%, 0.31-0.38% of the chemical composition of the general carbon plate as the raw material; 01. Material selection: Select hot-rolled steel plates with different specifications and chemical compositions according to different strength requirements, and make them into rectangular steel pipes with specified cross-sectional dimensions through forming and welding production equipment; 02. Heat treatment strengthening: The electromagnetic induction heating quenching process is used for heat treatment strengthening. The formed rectangular steel pipe is induction heated on the induction quenching machine. The heating temperature is 870-900℃ and the heating rate is 50-100℃ / S. After reaching the temperature, the quenching liquid is sprayed for rapid cooling. The metallographic structure of the material after electromagnetic induction heating quenching is transformed from the original hot-rolled pearlite plus ferrite to all quenched martensite or quenched martensite plus a small amount of undissolved ferrite.

03. According to the different carbon content of the selected materials, rectangular steel tubes with different strength levels can be obtained after heat treatment and strengthening. The material with a carbon content of 0.08-0.20% has a strength of 1000-1300MPa after quenching; the material with a carbon content of 0.21-0.30% has a strength of 1200-1500MPa after quenching; the material with a carbon content of 0.31-0.38% has a strength of 1400-1700MPa after quenching. Rectangular steel tubes with different strengths can meet the use requirements under different stress conditions.

04. The rectangular steel tube strengthened by electromagnetic induction heat treatment is cut into a certain length and structural shape according to the drawing, and welded into a lightweight battery frame assembly by carbon dioxide shielded welding, plasma welding, laser welding or bolt connection process.

2. A process for making a lightweight battery frame using ultra-high strength rectangular steel pipe according to claim 1, characterized in that: The process mode of electromagnetic induction heating quenching is a continuous scanning heating mode. This heat treatment mode is suitable for the heat treatment of slender parts. While scanning heating, scanning water spray quenching cooling is carried out.

3. A process for making a lightweight battery frame using ultra-high strength rectangular steel pipe according to claim 2, characterized in that: Continuous scanning rectangular heating is adopted. The heating width depends on the length of the effective circle of the inductor. Appropriate optimization can be carried out in actual production to control the actual heating and quenching area. By adjusting the heating and quenching area, the production efficiency and the deformation of the rectangular steel pipe can be optimized.

4. A process for making a lightweight battery frame using ultra-high strength rectangular steel pipe according to claim 1, characterized in that: Martensite has higher strength, and the rectangular steel tube is structurally strengthened after quenching.

5. A process for making a lightweight battery frame using ultra-high strength rectangular steel pipe according to claim 1, characterized in that: The chemical composition and range are: silicon Si: 0.17~1.37%, manganese Mn: 0.35~0.657%, phosphorus P: 0.0357%, sulfur S: ≤0.037%, chromium Cr: ≤0.27%, nickel Ni: ≤0.37%, copper Cu: ≤0.257%.