Production method of TRB automobile door ring

Abstract

The invention discloses a TRB automobile door ring production method. The TRB automobile door ring production method comprises the following steps that door ring structural parts in different areas are obtained through TRB rolling; the door ring structural parts are sequentially in butt joint, and a TRB automobile door ring blank part is obtained through laser splicing; the TRB automobile door ring blank is placed between an upper die and a lower die of a heating device to be subjected to heat treatment through contact heating; and transferring to a stamping die for stamping forming, and quenching to obtain the TRB automobile door ring. Through contact heating, the heating time is shortened, the efficiency is improved, the energy consumption is reduced, and the production cost is saved; meanwhile, different heating powers and temperatures are set for areas with different thicknesses of the TRB automobile door ring blank, the problem that temperature distribution is not uniform during hot stamping due to different thicknesses of different parts of the TRB automobile door ring blank is solved through partition heat treatment, the structure property consistency of the different parts of the door ring is improved, hardness, strength and toughness are more stable and reliable, and the service life of the door ring is prolonged. And the door ring quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle parts preparation, and in particular to a production method of a TRB automobile door knocker. Background Art

[0002] TRB (continuous variable cross-section plate) rolling technology, as a plate production process for obtaining plates of unequal thickness by continuous variable cross-section rolling, has gradually been applied to the manufacture of automobile door rings to achieve lightweight while maintaining or improving the performance of parts. Its advantage is that the plate thickness can be adjusted according to the actual needs of different positions to achieve lean design and production. The thickness can be increased in places with high strength requirements, and the plate thickness can be reduced in places with low requirements, so as to be more in line with the original intention of the design, reduce redundancy, and save materials. At the same time, this production method also reduces the length of laser welding and the number of patch plates, further reducing weight and ensuring the overall performance of the door ring. This door ring not only meets the needs of lightweight design of automobiles, but also ensures the safety and structural strength of the vehicle.

[0003] However, in the existing TRB door ring hot stamping, the heating method is usually to use a box furnace or a roller hearth furnace for heating, relying on heat radiation and heat convection to transfer heat, with a slow heating rate and a long heating time. The heating element in the heating furnace generates heat, which heats up the air in the furnace to form hot air, and the hot air exchanges heat with the surface of the workpiece, and the heat is gradually transferred from the surface of the workpiece to the inside. This method has a long heat transfer path, and it takes a long time for the internal temperature of the workpiece to reach uniform distribution and complete austenitization. For example, under the same heating conditions, the time required for complete austenitization of 1 mm thick steel is usually set at 116s-194s, while the time required for complete austenitization of 2 mm thick steel is usually 232s-388s. In addition, for the door ring parts made of TRB differential thickness plates, the material thickness in different areas is inconsistent, the heating rate, and the heat dissipation rate after leaving the furnace are inconsistent. Whether it is a box furnace or a roller hearth furnace, it is impossible to heat the material in different areas according to the material thickness. After leaving the furnace, the temperature of the thin area often drops faster, and the die temperature is inconsistent during stamping, resulting in different organizational properties of different parts of the door ring. This not only affects the consistency of the overall strength of the door ring, but may also cause safety problems during use due to poor local performance. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for producing a TRB automobile door knocker, in which a TRB automobile door knocker blank is heated by a contact heating method to improve the heating efficiency, and different temperatures and heating powers are set for areas of different thicknesses to improve the consistency of the temperatures of each area during stamping into a mold, thereby improving the overall performance uniformity of the TRB automobile door knocker and avoiding the problem of large differences in tissue performance of door knockers of different thicknesses.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a method for producing a TRB automobile door knocker, comprising the following method:

[0006] S1, door ring structures in different regions are obtained by TRB rolling;

[0007] S2, docking the door knocker structural parts in sequence, and obtaining the TRB automobile door knocker blank parts by laser splicing;

[0008] S3, placing the TRB automobile door knocker blank between the upper die and the lower die of a heating device for heat treatment by contact heating;

[0009] Among them, for the thin area of ​​TRB automobile door knocker blank with thickness of 1mm≤d<2mm, the heat treatment temperature is 915℃<T≤950℃; for the thick area of ​​TRB automobile door knocker blank with thickness of 2mm≤d≤3mm, the heat treatment temperature is 880℃≤T≤915℃;

[0010] S4, transferring to a stamping die for stamping and forming, and obtaining the TRB automobile door knocker after quenching.

[0011] Furthermore, the upper mold and the lower mold match the shape of the TRB automobile door knocker blank, the lower mold is partitioned according to the thickness of the TRB automobile door knocker blank, the heating power of the corresponding area is adjusted by adjusting the number of heating rods embedded in the lower mold in each area, the lower mold is heated to the corresponding heat treatment temperature, and the TRB automobile door knocker blank is contact heated.

[0012] Furthermore, a heat insulation plate is provided between adjacent areas in the lower mold to avoid mutual influence of temperatures in different areas.

[0013] The present invention heats the TRB automobile door knocker blank by contact with the lower mold, and transfers heat by directly contacting the heating source with the TRB automobile door knocker blank. The heat generated by the heating rod is directly transferred to the TRB automobile door knocker blank through the mold, and the heat transfer distance is short and the heat loss is small. Partition heating can quickly transfer heat to the thin and thick areas of the workpiece, especially for the thin area, the heat can be quickly replenished; for the thick area, the heat can also be more efficiently penetrated into the interior, reducing the loss and time delay of heat during the transfer process, so the workpiece can reach the target temperature as a whole in a shorter time, improving the heating efficiency and shortening the heating time.

[0014] Among them, the thickness of the thin zone is 1-2mm, with small heat capacity and limited heat storage capacity. After leaving the furnace, it dissipates heat in the air, and when it contacts the cold zone of the mold during stamping, it dissipates heat quickly. Increasing the heating power and controlling the target temperature at 915-950℃ can replenish this part of the lost heat, ensure that the thin zone material is fully austenitized, and obtain good organizational properties. The thickness of the thick zone is 2-3mm, with large heat capacity, and the heat transfer and heat dissipation rate is relatively slow. Compared with the thin zone, the heating power is reduced, and the target temperature is controlled at 880℃-915℃, which can avoid local overheating caused by excessive power in the thick zone, that is, the thick zone material can be austenitized to ensure performance, and the energy consumption can be balanced to avoid energy waste and possible material performance problems caused by excessive temperature.

[0015] The present invention places a TRB automobile door knocker blank on a lower die, fixes it with a positioning device, and heats it by closing the upper and lower dies. The lower die is provided with a heating rod arrangement with uneven density distribution. The heating rods in the thinner parts of the sheet are more densely distributed. The heating power of different areas is adjusted by controlling the number of heating rods used, and different heat treatment temperatures are set to improve the consistency of the temperature of each area when the TRB automobile door knocker blank is transferred to the stamping die, thereby improving the overall performance uniformity of the TRB automobile door knocker and avoiding the problem of large differences in tissue performance at different thickness parts of the door knocker.

[0016] Furthermore, in S1, the number of the door ring structural components is greater than four.

[0017] Furthermore, the steps between S2 and S3 also include grinding and cleaning steps of the TRB automobile door knocker blank.

[0018] Furthermore, before S3, the step also includes: preheating each area of ​​the heating device to a preset heat treatment temperature.

[0019] Furthermore, in S3, the temperature difference between the thin zone and the thick zone is 15°C ≤ Δ T≤35℃.

[0020] Furthermore, in S3, the heating power of the thin zone is 2-3 kW, and the heating power of the thick zone is 1-2 kW, and the heating power of different zones is achieved by the number of heating rods embedded in the lower mold of the corresponding zone.

[0021] Furthermore, in S3, the heat treatment time is 120-180s.

[0022] Furthermore, in S3, the temperature of each zone of the TRB automobile door knocker blank is monitored in real time by an infrared temperature sensor, and the heating power of each zone is dynamically adjusted within the range of ±10%.

[0023] Furthermore, in S4, the transfer time is 4-10s.

[0024] Furthermore, in S4, the stamping pressure is 900-1500T, and the holding time is 5-10s.

[0025] Beneficial effects of the present invention:

[0026] The present invention shortens the time required for heating, improves efficiency, reduces energy consumption, and saves production costs through contact heating. At the same time, different heating powers and temperatures are set for different thickness areas of the TRB automobile door knocker blank, and the problem of uneven temperature distribution during hot stamping caused by different thicknesses of different parts of the TRB automobile door knocker blank is solved through zoned heat treatment.

[0027] The temperature uniformity of the TRB automobile door knocker blank is high during stamping and forming, the consistency of the tissue performance of different parts of the prepared door knocker is improved, the hardness, strength and toughness are more stable and reliable, the quality of the door knocker is improved, and the safety risks caused by performance differences in different areas are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 1. It is a positional relationship diagram of a TRB automobile door knocker blank and an upper die and a lower die of the present invention;

[0030] Figure 2 It is a schematic diagram of splicing four door ring structural parts prepared by TRB rolling in Example 1 of the present invention;

[0031] Explanation of the numbers in the figure: 1. Upper mold, 2. Lower mold, 3. TRB automobile door knocker blank, 4. Heating rod, 5. Heat insulation board, 6. Locating pin, 7. A-pillar upper plate, 8. A-pillar lower plate, 9. Door sill plate, 10. B-pillar plate. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific 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.

[0033] This embodiment provides a method for producing a TRB automobile door knocker, including the following method:

[0034] S1. A door ring structure having four or more different regions is obtained by TRB rolling;

[0035] S2, the door ring structural parts are connected in sequence, the thickness of the joints of two adjacent door ring structural parts is the same, and the TRB automobile door ring blank parts are obtained by laser splicing;

[0036] S3, placing the TRB automobile door knocker blank between the upper die and the lower die of a heating device for heat treatment by contact heating;

[0037] Among them, for the thin area of ​​TRB automobile door knocker blank with thickness of 1mm≤d<2mm, the heat treatment temperature is 915℃<T≤950℃; for the thick area of ​​TRB automobile door knocker blank with thickness of 2mm≤d≤3mm, the heat treatment temperature is 880℃≤T≤915℃;

[0038] S4, transferring to a stamping die for stamping and forming, and obtaining the TRB automobile door knocker after quenching.

[0039] Specifically, refer to Figure 1 The upper mold 1 and the lower mold 2 match the shape of the TRB automobile door knocker blank 3. The lower mold 2 is divided into zones according to the thickness of the TRB automobile door knocker blank 3. The heating power of the corresponding zone is adjusted by adjusting the number of heating rods 4 embedded in the lower mold in each zone, and the lower mold 2 is heated to the corresponding heat treatment temperature to perform contact heating on the TRB automobile door knocker blank 3. A heat insulation plate 5 is arranged between adjacent zones in the lower mold 2 to avoid mutual influence of temperatures in different zones, and the TRB automobile door knocker blank 3 is positioned by a positioning pin 6.

[0040] This embodiment heats the TRB automobile door knocker blank by contact with the lower mold, and transfers heat by direct contact between the heating source and the TRB automobile door knocker blank. The heat generated by the heating rod is directly transferred to the TRB automobile door knocker blank through the mold, and the heat transfer distance is short and the heat loss is small. Partition heating can quickly transfer heat to the thin and thick areas of the workpiece, especially for the thin area, which can quickly replenish heat; for the thick area, it can also more efficiently make the heat penetrate deep into the interior, reducing the loss and time delay of heat during the transfer process, so that the workpiece can reach the target temperature as a whole in a shorter time, improving the heating efficiency and shortening the heating time. The TRB automobile door knocker blank is placed on the lower die, fixed by positioning equipment, and heated by closing the upper and lower dies. The lower die is provided with a heating rod arrangement with uneven density distribution. The heating rods are denser in the thinner parts of the sheet. The heating power of different areas is adjusted by controlling the number of heating rods used, and different heat treatment temperatures are set to improve the consistency of temperature in each area when the TRB automobile door knocker blank is transferred to the stamping die, thereby improving the overall performance uniformity of the TRB automobile door knocker and avoiding the problem of large differences in tissue performance in different thickness parts of the door knocker.

[0041] As a preferred embodiment, the steps of grinding and cleaning the TRB automobile door knocker blank are also included between S2 and S3; and before S3, the steps of preheating each area of ​​the heating device to a preset heat treatment temperature are also included.

[0042] As a preferred embodiment, in S3, the temperature difference between the thin zone and the thick zone is 15°C≤ Δ T≤35℃; the heating power of the thin zone is 2-3kW, the heating power of the thick zone is 1-2kW, and the heat treatment time is 120-180s; the temperature of each zone of the TRB automobile door knocker blank is monitored in real time by an infrared temperature sensor, and the heating power of each zone is dynamically adjusted within the range of ±10%.

[0043] As a preferred embodiment, in S4, the transfer time is 4-10s; the stamping pressure is 900-1500T, and the holding time is 5-10s.

[0044] Example 1

[0045] This embodiment relates to a method for producing a TRB automobile door knocker, comprising the following steps:

[0046] (1) The raw material of the door ring is 22MnB5 aluminum-silicon coated plate. The material thickness of different areas is designed according to the strength requirements of different areas of the door ring. Four door ring structural parts are prepared by TRB rolling: A-pillar upper plate 7, A-pillar lower plate 8, B-pillar plate 10 and threshold plate 9. Figure 2 ;

[0047] (2) Four door ring structural parts are sequentially butted together and then laser welded to obtain a TRB automobile door ring blank;

[0048] (3) Clean and polish the surface of the welded TRB door ring blank to remove surface oil and burrs until the surface is clean and smooth;

[0049] (4) Preheat each area of ​​the contact heating device to the heat treatment temperature of the corresponding area; the cleaned door ring blank is transferred to the upper and lower dies within 10 seconds for contact heating to achieve complete austenitization of the steel, refer to Figure 2 , taking the B-pillar plate 10 as an example, the H area is a thick area, the material thickness is 2.8mm, the heating power is set to 1.0kw, and the heating temperature is set to 900℃; the G area is a thin area, the material thickness is 1.5mm, the heating power is set to 2.6kw, and the heating temperature is set to 920℃. The other door ring structural parts are heated in the same way. The parameters of the thin area (B, C, E) are the same as those of the G area, and the parameters of the thick area (A, D, F) are the same as those of the H area. The heating time is 150s;

[0050] (5) The heat-treated door ring blank is quickly transferred to the hot stamping die to complete stamping and quenching, and wait for subsequent processing operations. The holding pressure is 900T and the holding time is 10s.

[0051] Example 2

[0052] The difference between this embodiment and embodiment 1 is that the thick zone heating power is set to 1.3 kW, and other parameters and steps remain unchanged.

[0053] Example 3

[0054] The difference between this embodiment and embodiment 1 is that the thick zone heating power is set to 1.5 kW, and other parameters and steps remain unchanged.

[0055] Example 4

[0056] The difference between this embodiment and embodiment 1 is that the thick zone heating power is set to 1.6 kW, and other parameters and steps remain unchanged.

[0057] Example 5

[0058] The difference between this embodiment and embodiment 1 is that the thick zone heating power is set to 1.8 kW, and other parameters and steps remain unchanged.

[0059] Example 6

[0060] The difference between this embodiment and embodiment 1 is that the thick zone heating power is set to 2.0 kW, and other parameters and steps remain unchanged.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 is that the heating power of the thick zone is 0.9 kW, and other parameters and steps remain unchanged.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that the heating power of the thick zone is 2.1 kW, and other parameters and steps remain unchanged.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 1 is that the heating power of the thin zone is the same as that of the thick zone, both being 1.5 kW, and other parameters and steps remain unchanged.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 1 is that the temperature of the thick zone is the same as that of the thin zone, which is 920° C., and other parameters and steps remain unchanged.

[0069] Comparative Example 4

[0070] The difference between this comparative example and Example 1 is that the temperature of the thin zone is the same as that of the thick zone, which is 900° C., and other parameters and steps remain unchanged.

[0071] The mechanical properties of the formed door knocker are tested, and the test results are shown in Table 1. The results show that the performance of each part of the door knocker prepared in the embodiment meets the standard requirements, and the performance of each area tends to be stable with small differences, while the performance of each part of the door knocker prepared in the comparative example has large differences, and there are cases where the performance of some areas does not meet the standard requirements, posing a safety hazard.

[0072] Table 1 Mechanical properties test results (standard requirements: tensile strength: 1300-1700MPa, yield strength: 950-1250MPa, elongation: A50≥5%)

[0073]

[0074] In summary, the present invention shortens the time required for heating, improves efficiency, reduces energy consumption, and saves production costs through contact heating. At the same time, different heating powers and temperatures are set for different thickness areas of TRB automobile door knocker blanks. Through zoned heat treatment, the problem of uneven temperature distribution during hot stamping caused by different thicknesses of different parts of TRB automobile door knocker blanks is controlled and solved; the temperature uniformity during stamping is high, the consistency of the organizational performance of different parts of the prepared door knocker is improved, the hardness, strength, and toughness are more stable and reliable, the quality of the door knocker is improved, and the safety risks caused by performance differences in different areas are reduced.

[0075] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for producing a TRB automobile door knocker, characterized in that: The following methods are included: S1, door ring structures in different regions are obtained by TRB rolling; S2, docking the door knocker structural parts in sequence, and obtaining the TRB automobile door knocker blank parts by laser splicing; S3, placing the TRB automobile door knocker blank between the upper die and the lower die of a heating device for heat treatment by contact heating; Among them, for the thin area of ​​TRB automobile door knocker blank with thickness of 1mm≤d<2mm, the heat treatment temperature is 915℃<T≤950℃; for the thick area of ​​TRB automobile door knocker blank with thickness of 2mm≤d≤3mm, the heat treatment temperature is 880℃≤T≤915℃; S4, transferring to a stamping die for stamping and forming, and obtaining the TRB automobile door knocker after quenching.

2. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S1, the number of the door ring structural members is four or more.

3. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: The steps between S2 and S3 also include grinding and cleaning of the TRB automobile door knocker blank.

4. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: Before S3, the process also includes: preheating each area of ​​the heating device to a preset heat treatment temperature.

5. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S3, the temperature difference between the thin zone and the thick zone is 15°C≤ Δ T≤35℃.

6. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S3, the heating power of the thin zone is 2-3 kW, and the heating power of the thick zone is 1-2 kW.

7. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S3, the heat treatment time is 120-180s.

8. The method for producing a TRB automobile door knocker according to claim 6, characterized in that: In S3, the temperature of each zone of the TRB automobile door knocker blank is monitored in real time by an infrared temperature sensor, and the heating power of each zone is dynamically adjusted within the range of ±10%.

9. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S4, the transfer time is 4-10s.

10. The method for producing a TRB automobile door knocker according to claim 1, characterized in that: In S4, the stamping pressure is 900-1500T, and the holding time is 5-10s.

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