A cab side wall drawing forming die

Abstract

The application discloses a drawing forming die for a side wall of a vehicle cab, relates to the technical field of drawing forming dies, and aims to solve the technical problem that the safety belt part lacks impact redundancy protection after B-column drawing forming. Through integrated forming, differential material pressing, self-adaptive temperature control, and multiple stable cooling layer-by-layer design, the finally formed B-column inner plate extrusion piece can realize controllable brittle fracture of a torsional fracture section, elastic bending of a bending plate, and redundancy protection actions of pressing safety belts during vehicle side collision, so that even if a safety belt retractor locking mechanism is disabled due to impact, the safety belts can still be forcibly restrained to avoid excessive displacement of drivers and passengers, and the problem of collision protection failure caused by structural defects of a traditional B-column safety belt mounting part is solved. The die endows the B-column inner plate with a collision redundancy protection function from the forming source, so that the formed B-column inner plate has both convenient assembly and high protection performance, and the collision safety level of the side wall of the vehicle cab is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of drawing forming die technology, and more specifically, to a drawing forming die for the side panel of an automobile cab. Background Technology

[0002] As a core load-bearing and protective component of the vehicle body, the side panel of the driver's cab is not only a key structure in the cab space but also plays a vital role in collision protection and supporting the rigidity of the vehicle body. Its molding quality directly affects the safety and comfort of the entire vehicle. To improve production efficiency and ensure structural integrity, modern automobile manufacturing generally adopts a one-piece drawing molding process to produce the side panel of the driver's cab. This process uses a special drawing mold to draw the sheet metal into shape in one step, achieving integrated connection of all parts of the side panel. Among them, the B-pillar, as the core reinforcing structure of the side panel, runs vertically through the side of the driver's cab and is a key barrier to resist side impacts and protect the safety of the occupants.

[0003] The B-pillar area requires the installation of core safety components such as seat belt retractors, and its structural design and molding precision are crucial to the reliability of the seat belt system. However, the B-pillars produced by existing automotive cab side panel drawing molds often feature a through-hole structure for the seat belt installation area. While this structure facilitates the assembly of the seat belt retractor, it poses a significant safety hazard. When the cab suffers a large side impact, the impact force acts directly on the B-pillar, causing plastic deformation. Because the through-hole structure weakens the structural strength and deformation resistance of this area, local collapse or misalignment can easily occur during deformation, directly impacting and compressing the seat belt retractor installed inside the through-hole. This impact can damage the internal mechanical structure of the retractor and cause the locking function to fail. Consequently, the seat belt cannot lock in time and effectively restrain the occupants during a collision, leading to excessive displacement due to inertia, increasing the risk of secondary collisions with vehicle interior components, severely weakening the side impact protection effect, and threatening the lives of occupants. Existing drawing dies, due to structural design limitations, cannot produce B-pillar structures that combine ease of assembly with high protective performance, making it difficult to meet the increasingly stringent side-impact safety requirements of the automotive industry. Therefore, we propose a drawing die for the side panel of an automotive driver's cab. Summary of the Invention

[0004] The purpose of this invention is to provide a drawing die for the side panel of an automobile driver's cab to solve the technical problem of lack of impact redundancy protection for the seat belt area after the B-pillar is drawn.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a drawing forming die for a side panel of an automobile cab, comprising a drawing die base composed of an upper pressing die and a lower pressing die, wherein a forming cavity is provided between the upper pressing die and the lower pressing die, and a guide post and a pressing hydraulic rod are also provided on the drawing die base, wherein a drawing template is provided in the central area of ​​the upper pressing die, a drawing hydraulic rod is fixed on the top of the drawing template, and a fixing seat is provided in the drawing template; An extension plate connects the fixed seat and the upper pressing die. The lower half of the fixed seat is provided with a bending pressing seat and two torsion pressing seats. The bending pressing seat and the torsion pressing seat are respectively adapted to the bending plate and the torsion section. The bending pressing seat and the torsion pressing seat are respectively limited and slidable with the fixed seat. A pressing hydraulic rod is connected to the top of the bending pressing seat. A pressing structure for torsion pressing force is provided between the outer periphery of the driving end of the pressing hydraulic rod and the torsion pressing seat. The lower pressing die is equipped with an adaptive cooling structure near the extrusion part area for slow cooling and rapid cooling of the bent plate and the torsion joint, respectively.

[0006] Preferably, the pressing structure includes a pressing ring, which is installed on the outer periphery of the pressing hydraulic rod. A pressing rocker plate is installed on the outer periphery of the pressing ring. One end of the pressing rocker plate is located below the pressing ring, and the other end of the pressing rocker plate is connected to the torsion pressing seat. A fixing sleeve is connected between the center of the pressing rocker plate and the inner wall of the fixing seat.

[0007] Preferably, the pressure rocker includes straight sections at both ends, and an arc segment connects the two straight sections. The arc segment is movably connected to the fixed sleeve.

[0008] Preferably, the adaptive cooling structure includes an outlet and two inlets, the inlets being connected to inlet pipes, the inlet pipes being connected to twisted cooling pipes, and the two twisted cooling pipes being connected by curved cooling pipes arranged at a distance.

[0009] Preferably, the curved cooling pipe has a diameter larger than that of the twisted cooling pipe to reduce flow rate, and the curved cooling pipe is connected to an outlet pipe connected to the outlet.

[0010] Preferably, the curved cooling pipe is connected to a plurality of deceleration sections for ensuring slow cooling, and the liquid inlet is connected to a side flow pipe for depressurization, the liquid outlet of the side flow pipe flowing into the liquid outlet pipe.

[0011] Preferably, the deceleration section includes an oblique flow section inclined towards the liquid outlet direction and a side confluence section for merging into the main flow to slow down the flow velocity, the side confluence section being inclined in the opposite direction to the oblique flow section.

[0012] Preferably, a flow control valve is provided on the side flow pipe, and a valve sleeve is provided inside the flow control valve. The valve sleeve is made of a material that can be deformed in response to temperature. The valve sleeve includes a flow guide ring that communicates with the side flow pipe, and a corrugated ring extends from one side of the flow guide ring.

[0013] Preferably, the corrugated ring has an S-shaped curved structure, a limiting plate is connected to the crest of the corrugated ring, the limiting plate is slidably connected to the flow control valve, and a hinge rod is movably connected between the limiting plate and the flow guide ring.

[0014] Preferably, the surface of the forming cavity at the bending plate position is provided with multiple heat-insulating micro-protrusions, and the multiple heat-insulating micro-protrusions form a micron-level stepped gap with the drawn workpiece.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention designs a differentiated pressing structure in the drawing die, relying on the pressing hydraulic rod to drive the bending pressing seat to achieve strong pressing, and the pressing ring linkage pressing rocker moves the torsion breaking pressing seat upward to achieve no pressing. In a single drawing die closing, the strong pressing and large stretching of the bent plate and the free forming of the torsion breaking section without pressing are completed simultaneously. This allows the die to directly form the B-pillar inner panel extrusion with both high toughness of the bent plate and high brittleness of the torsion breaking section without secondary processing. This solves the problem that traditional dies cannot simultaneously form structures with different mechanical properties, greatly improving the forming efficiency of the B-pillar inner panel. At the same time, it ensures that the extrusion structure and the B-pillar inner panel are integrated, improving the overall structural strength and laying the structural foundation for the collision redundancy protection of the seat belt system.

[0016] 2. The present invention adds an adaptive cooling structure to the lower pressing die. Through the differentiated design of small-diameter close-range torsion cooling pipes and large-diameter far-range bending cooling pipes, the dual temperature control effect of rapid cooling of the torsion joint and slow cooling of the bending plate is achieved in a single cooling circuit. This works in conjunction with the die's differentiated pressing structure to precisely shape the different material properties of the bending plate and the torsion joint from the two dimensions of forming force and cooling speed. This ensures that the performance of each part of the extruded part is fully matched with the collision protection requirements. It solves the problem that traditional cooling methods are difficult to adapt to different forming temperature control requirements, improves the performance accuracy of the die forming, and ensures that the extruded part can achieve the "brittle fracture-bending" chain action during collision.

[0017] 3. This invention adds a deceleration section to the bending cooling pipe of the drawing die and connects the liquid inlet to the side flow pipe. Through the synergistic effect of upstream diversion and pressure reduction in the side flow pipe and downstream bidirectional flow counteraction of the deceleration section, the coolant flow is regulated from two dimensions: reducing the mainstream flow rate and reducing the local flow velocity. This further enhances the slow cooling effect in the bending plate area, avoids uneven cooling caused by fluctuations in coolant flow rate and pressure, ensures uniform toughness in all parts of the bending plate, and makes the cooling regulation of the die more stable. Even when the production line conditions change slightly, the cooling rate of the bending plate can still be precisely controlled, improving the adaptability of the die to complex production conditions and ensuring batch consistency of the B-pillar inner panel forming quality.

[0018] 4. This invention features a flow control valve with a temperature-sensitive deformation valve sleeve installed in the side flow pipe, and an insulating micro-protrusion on the corresponding cavity surface of the bending plate. The insulating micro-protrusion utilizes Fourier's law of heat conduction to create a physical thermal resistance, locking the cooling rate of the bending plate within the slow cooling range. Simultaneously, the flow control valve adaptively adjusts the diversion flow rate according to the coolant temperature, further reducing the coolant flow rate in the bending cooling pipe during the later stages of cooling. This counteracts the increased heat exchange efficiency caused by the low-temperature coolant, achieving stable control of the bending plate's cooling rate throughout the process. This solves the technical problem of temperature changes in the later stages of cooling disrupting the slow cooling effect, allowing the temperature control accuracy of the mold to reach a new level. It ensures that the performance difference between the high toughness of the bending plate and the high brittleness of the torsion joint remains stable, guaranteeing the reliability of the collision protection function of the extruded parts.

[0019] 5. This invention, through integrated molding, differentiated pressing, adaptive temperature control, and multiple stable cooling layer-by-layer design, enables the final B-pillar inner panel extrusion to achieve redundant protective actions during a side collision, including controllable brittle fracture of the torsion joint, elastic bending of the bending plate, and compression of the safety webbing. Even if the seat belt retractor locking mechanism fails due to the impact, it can still forcibly restrain the webbing to prevent excessive displacement of the occupants, solving the problem of collision protection failure caused by structural defects in the traditional B-pillar seat belt installation area. The mold endows the B-pillar inner panel with redundant collision protection function from the molding source, allowing the molded B-pillar inner panel to have both convenient assembly and high protective performance, significantly improving the collision safety level of the car's driver's cab side panel and meeting the stringent requirements of the automotive industry for side collision safety. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the B-pillar inner panel and the B-pillar outer panel after assembly according to the present invention; Figure 2 This is a schematic diagram of the structure of the inner B-pillar panel after removing the extruded parts and assembling it with the outer B-pillar panel in this invention; Figure 3 This is a schematic diagram of the extrusion component structure in this invention; Figure 4 For the present invention Figure 3 Enlarged view of the component at point S in the middle; Figure 5 This is a schematic diagram of the drawing die structure of the present invention; Figure 6 This is a schematic diagram of the upper pressure die in this invention; Figure 7 This is a half-sectional view of the fixing base in its normal state according to the present invention; Figure 8 For the present invention Figure 7 Enlarged view of component A in the middle; Figure 9 This is a half-sectional view of the fixed base in the pressing state in this invention; Figure 10 For the present invention Figure 9 Enlarged view of component B in the middle; Figure 11 This is a schematic diagram of the lower pressure die in this invention; Figure 12 This is a schematic diagram of the adaptive cooling structure in this invention; Figure 13 For the present invention Figure 12 Enlarged view of component C in the middle; Figure 14 This is a schematic diagram of the adaptive cooling structure from another perspective in this invention; Figure 15 This is a schematic diagram of the half-section structure of the flow control valve in the present invention when it is not deformed; Figure 16 This is a schematic diagram of the half-section structure of the flow control valve under deformation in this invention.

[0021] Explanation of the labels in the diagram: 1. B-pillar inner panel; 2. Extension; 3. Pressure plate; 4. Extruded component; 41. Bending plate; 411. Arc plate; 412. Side pressure plate; 42. Torsion joint; 421. Tapered joint; 43. Compensating plate; 5. Seat belt mounting point; 6. Drawing die base; 61. Upper blank holder die; 62. Lower blank holder die; 63. Guide column; 64. Forming cavity; 65. Blank holder hydraulic rod; 66. Drawing template; 67. Drawing hydraulic rod; 7. Fixed seat; 8. Extension connecting plate; 91. Bending pressure seat; 92. Torsion pressure seat; 93. Material pressing hydraulic rod; 10. Material pressing structure ; 11. Adaptive cooling structure; 12. Side flow pipe; 13. Flow control valve; 14. Valve sleeve; 101. Pressure ring; 102. Pressure rocker; 1021. Straight section; 1022. Arc section; 103. Fixed connecting sleeve; 111. Liquid outlet; 112. Liquid inlet; 113. Liquid inlet pipe; 114. Twisted cooling pipe; 115. Bent cooling pipe; 116. Liquid outlet pipe; 117. Deceleration joint; 1171. Oblique flow section; 1172. Side confluence section; 141. Flow guide ring; 142. Corrugated ring; 143. Limiting plate; 144. Hinge rod; 81. B-pillar outer panel. Detailed Implementation

[0022] like Figures 1 to 4 As shown, this invention relates to a drawing die for a side panel of an automobile driver's cab. Specifically, it is a drawing die designed for the B-pillar, primarily used to produce a novel inner B-pillar panel 1. The inner B-pillar panel 1 has positioning holes, and an outer B-pillar panel 81 is provided on one side of the inner B-pillar panel 1. The entire B-pillar is formed by combining the inner and outer panels (e.g., ...). Figure 1 - Figure 2 As shown), both the upper and lower ends of the inner panel 1 of the B-pillar are welded edges. An extension 2 extends from one side of the seat belt assembly area of ​​the inner panel 1 of the B-pillar. A seat belt mounting point 5 for fixing the seat belt is installed in the seat belt assembly area of ​​the inner panel 1 of the B-pillar. A pressure plate 3 is integrally formed on the other side of the seat belt assembly area. An extrusion member 4 is provided between the pressure plate 3 and the extension 2.

[0023] The extruded part 4 includes a bending plate 41, one end of which is connected to the extension 2. The bending plate 41 is a tough structure made by strong pressure and large tensile deformation. The bending plate 41 includes an arc plate 411 and a side pressure plate 412. After being subjected to impact force, the side pressure plate 412 can overlap with the pressure plate 3 to press the safety webbing. Both sides of the bending plate 41 near the extension 2 are connected to a torsion joint 42. The torsion joint 42 is a highly brittle structure made by free forming without pressure. A compensation plate 43 is connected between the torsion joint 42 and the extension 2. The torsion joint 42 has an overall S-shaped structure. The periphery of the torsion joint 42 has a gradually decreasing thickness node 421 towards the crest. There is a gap between the bending plate 41 and the pressure plate 3. The gap can be opened after drawing or formed by the design of the drawing die. This is a use of existing technology, so it will not be described in detail.

[0024] The extruded component 4 of the inner panel 1 of the B-pillar provides passive redundancy protection for the seat belt system in the side collision scenario. Relying on the high toughness of the bending plate 41 and the high brittleness of the torsion joint 42, it completes the chain action of "brittle fracture-bending-clamping" under the impact force, avoiding the uncontrolled elongation of the webbing after the failure of the traditional seat belt locking mechanism, and realizing secondary restraint for the occupants.

[0025] When a vehicle suffers a large side impact, the impact force is transmitted through the side of the vehicle body to the seat belt assembly area of ​​the B-pillar inner panel 1. The impact force acts directly on the extruded part 4. The torsion joint 42 is a highly brittle structure that is freely formed without pressure material and is S-shaped with tapered nodes 421 whose thickness gradually decreases from the periphery to the crest. This structural design causes the impact force to be concentrated in the weak area of ​​the tapered nodes 421. The impact force exceeding the threshold directly causes the controlled brittle fracture of the torsion joint 42, releasing the movement space for the elastic bending of the subsequent bending plate 41. At the same time, it absorbs some impact energy during the fracture process, reducing the rigid impact of the force on the bending plate 41.

[0026] The bending plate 41 is a high-toughness structure made of high-pressure material with large tensile deformation, and the whole is in the shape of a curved arc. After the torsion joint 42 breaks, the bending plate 41 loses the rigid limiting constraint on both sides. Under the continuous action of the remaining impact force, it undergoes elastic bending deformation along its own curvature. The bending direction is towards the side of the pressure plate 3 that is in contact with the safety webbing, realizing the structural posture transformation from "static support" to "dynamic compression". During the elastic bending process, the curved surface of the bending plate 41 will continue to approach and eventually fit with the safety webbing, pressing the safety webbing tightly against the contact surface of the pressure plate 3, forming a mechanical clamping structure, which directly restricts the tensile displacement of the safety webbing. Even if the seat belt's own retractor locking mechanism fails due to the impact, this clamping action can still forcibly restrain the webbing, preventing the occupants from excessive inertial displacement due to the uncontrolled elongation of the webbing, eliminating secondary collisions with the vehicle's internal components, and realizing redundant protection of the seat belt system.

[0027] like Figures 5 to 16 A drawing die body for a side panel of an automobile cab includes a drawing die base 6, which is composed of an upper pressing die 61 and a lower pressing die 62. A guide post 63 for guiding is provided between the upper pressing die 61 and the lower pressing die 62. A forming cavity 64 is provided between the upper pressing die 61 and the lower pressing die 62. A cooling channel is provided inside the upper pressing die 61. A pressing hydraulic rod 65 is installed on the side area of ​​the upper pressing die 61. A drawing template 66 is provided in the central area of ​​the upper pressing die 61. A drawing hydraulic rod 67 is fixed on the top of the drawing template 66. A fixing seat 7 is provided in the drawing template 66. A connecting plate 8 is connected between the fixed seat 7 and the upper pressing die 61. The lower half of the fixed seat 7 is provided with a bending pressing seat 91 and two torsion pressing seats 92. The bending pressing seat 91 and the torsion pressing seat 92 are respectively adapted to the bending plate 41 and the torsion section 42. The bending pressing seat 91 and the torsion pressing seat 92 are respectively limited and slidable with the fixed seat 7. The top of the bending pressing seat 91 is connected to a pressing hydraulic rod 93. A pressing structure 10 for torsion pressing force is provided between the outer periphery of the driving end of the pressing hydraulic rod 93 and the torsion pressing seat 92. The pressing structure 10 includes a pressing ring 101, which is installed on the outer periphery of the pressing hydraulic rod 93. A pressing rocker plate 102 is installed on the outer periphery of the pressing ring 101. One end of the pressing rocker plate 102 is located below the pressing ring 101, and the other end of the pressing rocker plate 102 is connected to the torsion pressure seat 92. A fixing sleeve 103 is connected between the center of the pressing rocker plate 102 and the inner wall of the fixing seat 7. The pressing rocker plate 102 includes straight sections 1021 at both ends, and an arc section 1022 is connected between the two straight sections 1021. The arc section 1022 is movably connected to the fixing sleeve 103.

[0028] It should be noted that the strong clamping force applied by the clamping hydraulic rod 93 is 120-150kN, corresponding to a pressure of 18-22MPa. This is the critical clamping value for the large tensile deformation of DP780 / DP980 duplex steel. It can not only limit the wrinkling and slippage of the sheet during the drawing process, but also force the sheet to undergo plastic tensile deformation (strain rate ≥15%) through sufficient clamping force. The toughness of the bending plate 41 is improved through strain strengthening (yield strength increased to ≥800MPa, elongation ≥18%). The no clamping force of the torsion clamp 92 refers to the clamping force ≤5kN (only offsetting the self-weight of the sheet and slight springback). During actual forming, the torsion clamp 92 moves upward along the fixed seat 7, forming a small gap with the sheet. The sheet is completely in a "free forming" state, without tensile strain caused by additional clamping force, thus preserving the original high brittleness of the material (brittleness is further strengthened by subsequent chilling).

[0029] Working principle: When the upper pressing die 61 moves downward, the pressing hydraulic rod 65 on its side first presses and fixes the edge of the plate placed on the lower pressing die 62, so as to prevent the plate from slipping or wrinkling during the subsequent drawing process, and ensure that the plate in the forming cavity 64 is subjected to uniform force during drawing, thus providing a basic guarantee for the overall forming accuracy.

[0030] After the plate edge is pressed, the drawing hydraulic rod 67 drives the drawing template 66 to press downward, driving the fixed seat 7 and the bottom bending pressure seat 91 and torsion pressure seat 92 to move downward simultaneously. The plate is drawn as a whole in the forming cavity 64, initially shaping the basic surface of the B-pillar inner plate 1 and the extruded part 4, realizing the overall plastic deformation of the plate. At the same time as the overall drawing, the pressure hydraulic rod 93 simultaneously drives the bending pressure seat 91 to apply downward pressure, applying strong pressure to the forming area of ​​the bent plate 41, forcing the plate in that area to undergo large tensile deformation. Through the strain strengthening effect of plastic deformation, the bent plate 41 forms a high-toughness structural characteristic, meeting the requirements for elastic bending during subsequent collisions.

[0031] During the downward pressing of the drawing template 66, the outer ring 101 of the template moves downward, pushing the straight section 1021 of one end of the pressing rocker 102 downward. Since the arc section 1022 of the pressing rocker 102 is movably connected to the fixed sleeve 103, forming a rotatable fulcrum, the downward pressure of the straight section 1021 is redirected and transmitted through the bending action of the arc section 1022, driving the straight section 1021 of the other end of the pressing rocker 102 to move upward, thereby pulling the torsion pressure seat 92 to move upward along the fixed seat 7. After the torsion pressure seat 92 moves upward, there is no pressing force in the forming area corresponding to the torsion joint 42, and the plate is in a free forming state without additional tensile strain reinforcement, ultimately forming a highly brittle structural characteristic. Moreover, the limiting sliding design of the torsion pressure seat 92 ensures that it only rises in the vertical direction and does not deviate from the forming position of the torsion joint 42.

[0032] The above-mentioned pressing, drawing, strong pressing and no pressing actions are completed simultaneously and the mold is closed in one go. After the mold is opened, the finished B-pillar inner panel 1, which has both the high toughness of the bending plate 41 and the high brittleness of the torsion joint 42, is directly obtained. The entire extruded part 4 and the B-pillar inner panel 1 are integrally formed without the need for subsequent secondary pressing, shaping and processing, thus achieving one-time molding.

[0033] The pressing structure 10 adopts a mechanical hard linkage design of "pressing ring 101 - pressing rocker plate 102 - torsion block 92". The pressing hydraulic rod 93 and the drawing hydraulic rod 67 are linked and coordinated. The downward pressing of the bending block 91 and the upward movement of the torsion block 92 are triggered and completed synchronously, ensuring that the pressing force state of the bending plate 41 and the torsion block 42 is completely consistent during each drawing process, effectively avoiding batch-to-batch forming differences and improving the product qualification rate.

[0034] The arc segment 1022 of the pressure rocker 102 is movably connected to the fixed sleeve 103, forming a flexible rotation fulcrum. Compared with a rigid connection, this ensures that the downward pressure of the pressure ring 101 can be efficiently and losslessly transmitted to the torsion pressure seat 92, achieving precise force transmission. It can also buffer mechanical vibration and stress impact during the molding process, avoiding wear and deformation of the mold due to stress concentration in certain areas, and extending the service life of the mold.

[0035] Both the bending pressure seat 91 and the torsion pressure seat 92 are connected to the fixed seat 7 by a limiting sliding connection, which limits the only direction of movement of the pressure seat, avoids the pressure seat from shifting or shaking during the forming process, ensures that the bending pressure seat 91 and the bending plate 41, and the torsion pressure seat 92 and the torsion joint 42 are precisely fitted, effectively controls the forming dimensional accuracy of the extruded part 4, and avoids problems such as part surface deviation and uneven thickness caused by misalignment of the pressure seat.

[0036] This structure integrates edge pressing, overall drawing, bending plate pressing, and twisted section 42 forming without pressing into a single drawing and mold closing action. It eliminates the need for additional pressing and shaping processes after drawing, reducing the number of parts loading and unloading and mold changes, significantly shortening the overall production cycle of the B-pillar inner panel 1, improving the efficiency of the production line, and better meeting the needs of high-volume, high-paced production in automobile manufacturing.

[0037] Furthermore, the brittleness and toughness of the material can be controlled by different pressing forces, but the cooling conditions are different during molding. Existing cooling methods cannot use two cooling modes. To address this, the lower pressing die 62 is provided with an adaptive cooling structure 11 near the extruded part 4 to perform slow cooling and rapid cooling on the bent plate 41 and the torn section 42, respectively.

[0038] The adaptive cooling structure 11 includes an outlet 111 and two inlets 112. The inlets 112 are connected to inlet pipes 113, which are connected to twisted cooling pipes 114. Two twisted cooling pipes 114 are connected to curved cooling pipes 115 arranged at a greater distance (meaning they are farther away from the bending plate 41). The twisted cooling pipes 114 are arranged closer to the twisted joint 42 to increase their cooling rate. The curved cooling pipes 115 are designed to reduce flow rate with a diameter larger than that of the twisted cooling pipes 114. The curved cooling pipes 115 are connected to an outlet pipe 116 connected to the outlet 111.

[0039] Working principle: The cooling medium enters simultaneously through the two inlets 112 of the lower pressing mold 62, is precisely guided through the inlet pipe 113 to the twisted cooling pipe 114, then flows into the bent cooling pipe 115, and finally is discharged through the outlet pipe 116 and outlet 111, forming a continuous cooling loop of "inlet - rapid cooling - slow cooling - outlet". The temperature control effect is achieved through the flow channel structure design throughout the process, without the need to adjust the external parameters such as medium temperature and flow rate.

[0040] The twisted cooling pipe 114 adopts a small diameter design and is arranged in close proximity to the forming area of ​​the twisted section 42. When the coolant flows in the small diameter channel, the flow rate naturally increases, which greatly improves the heat exchange efficiency with the mold cavity. At the same time, the close proximity arrangement allows the heat in the forming area of ​​the twisted section 42 to be quickly conducted to the cooling medium, achieving a rapid cooling effect. This promotes the formation of high hardness and high brittleness in the material of this area, matching the brittleness requirements of the twisted section 42 without pressure molding.

[0041] The curved cooling pipe 115 adopts a large-diameter, low-flow-rate design and is arranged at a distance from the forming area of ​​the curved plate 41. After the coolant enters the large-diameter curved cooling pipe 115 from the twisted cooling pipe 114, the cross-sectional area of ​​the flow channel increases and the flow rate decreases significantly. The heat exchange efficiency with the mold cavity is weakened accordingly. At the same time, the far-distance arrangement increases the heat conduction path in the forming area of ​​the curved plate 41, and the heat release rate is effectively slowed down, achieving a slow cooling effect. Combined with the strong pressing and large tensile deformation of the curved plate 41, it promotes the formation of high toughness and elastic bending properties of the material in this area.

[0042] The twisted cooling pipe 114 and the bent cooling pipe 115 are designed to be connected in sequence. After the coolant completes the rapid cooling of the twisted section 42 area, it naturally flows into the bent cooling pipe 115 to slowly cool the bent plate 41 area. There are no eddies or stagnation in the flow channel, and the cooling medium flows smoothly. Moreover, the two twisted cooling pipes 114 are symmetrically arranged and then connected to a single bent cooling pipe 115 to ensure that the rapid cooling effect on both sides of the twisted section 42 is consistent and the overall slow cooling of the bent plate 41 is uniform, avoiding material performance deviations caused by uneven temperature control.

[0043] The entire adaptive cooling structure 11 relies on the physical characteristics that the flow rate is determined by the flow channel diameter and the heat exchange efficiency is determined by the arrangement spacing. It simultaneously realizes two temperature control modes, rapid cooling and slow cooling, in a single cooling loop. In conjunction with the differentiated pressing structure of the mold, it accurately shapes the different material properties of the bending plate 41 and the torsion joint 42 from the two dimensions of forming force and cooling speed. This ensures that the structural performance of the extruded part 4 fully matches the requirements of collision protection. At the same time, it simplifies the design of the mold cooling system and reduces manufacturing costs and maintenance difficulty.

[0044] Furthermore, to ensure the effect of slow cooling, multiple deceleration sections 117 for ensuring slow cooling are extended from the curved cooling pipe 115. A side flow pipe 12 for depressurization is connected to the liquid inlet 112. The liquid outlet end of the side flow pipe 12 merges into the liquid outlet pipe 116. When the input and output rates of the input coolant are large, the side flow pipe 12 plays an auxiliary role in drainage. The deceleration section 117 includes a diagonal flow section 1171 inclined towards the liquid outlet direction, and a side confluence section 1172 for merging into the mainstream and slowing down the flow rate. The side confluence section 1172 is inclined in the opposite direction to the diagonal flow section 1171.

[0045] Working principle: After the coolant enters the inlet pipe 113 from the inlet 112, part of it flows along the main stream to the twisted cooling pipe 114, and the other part directly enters the side flow pipe 12 and flows into the outlet pipe 116. The diversion effect of the side flow pipe 12 directly reduces the flow rate of the main coolant entering the twisted cooling pipe 114 and the bent cooling pipe 115, realizing the initial pressure reduction and speed reduction, laying the foundation for further slow flow in the bent cooling pipe 115, and at the same time avoiding the heat exchange efficiency of the bent plate 41 area from being too large due to the main flow rate.

[0046] Multiple deceleration sections 117 extending from the curved cooling pipe 115, through the reverse tilting design of the oblique flow section 1171 and the side confluence section 1172, allow the coolant to form a bidirectional flow countercurrent within the flow channel. The mainstream coolant flows smoothly along the oblique flow section 1171 towards the outlet direction, while some coolant forms a backflow within the flow channel, merging into the mainstream along the side confluence section 1172, which is in the opposite tilting direction to the oblique flow section 1171. This creates a conflicting and mutually obstructing effect with the forward-flowing coolant. This bidirectional flow countercurrent directly and significantly reduces the overall flow velocity of the coolant within the curved cooling pipe 115, extending the contact time between the coolant and the mold cavity, further weakening the heat exchange efficiency, achieving secondary precise slow flow, and ensuring that the cooling rate in the area of ​​the curved plate 41 is always within the slow cooling range.

[0047] Multiple deceleration sections 117 work continuously to ensure uniform slow cooling: Multiple deceleration sections 117 are evenly arranged along the entire length of the curved cooling pipe 115, so that the coolant is always in a low-speed flow state in the entire flow channel corresponding to the forming area of ​​the curved plate 41, avoiding the problem of uneven cooling caused by excessive local flow rate, ensuring that the cooling rate of each part of the curved plate 41 is consistent, and the overall toughness is uniform after forming, without local brittleness and easy breakage performance defects.

[0048] The combined effect of diversion and counter-current flow ensures a dual guarantee of slow cooling effect: the upstream diversion pressure reduction of the side flow pipe 12 and the downstream flow channel counter-current of the deceleration section 117 work together to regulate the flow of coolant in the curved cooling pipe 115 from two dimensions: "reducing the mainstream flow rate" and "reducing the local flow velocity". Compared with the single channel diameter enlargement design, the slow cooling effect is more stable and controllable. Even if the inlet water pressure of the cooling system fluctuates slightly, the slow cooling effect in the area of ​​the curved plate 41 can be guaranteed not to deviate through the adaptive adjustment of diversion and counter-current flow.

[0049] Furthermore, during the later stages of cooling, the remaining parts are all cooled, so the temperature of the cooling medium entering the curved cooling pipe 115 will be relatively lower, further affecting the slow cooling effect. To address this, a flow control valve 13 is provided on the side flow pipe 12. The flow control valve 13 has a valve sleeve 14 inside. The valve sleeve 14 is made of a material that can be deformed in response to temperature. The valve sleeve 14 includes a flow guide ring 141 that communicates with the side flow pipe 12, and a corrugated ring 142 extends from one side of the flow guide ring 141.

[0050] The corrugated ring 142 has an S-shaped bend. The crest of the corrugated ring 142 is connected to the limiting plate 143. The limiting plate 143 slides and limits the flow control valve 13. The limiting plate 143 and the guide ring 141 are movably connected by a hinge rod 144. The limiting plate 143 and the hinge rod 144 are not made of deformable material. The lower pressing die 62 has heat-insulating micro-protrusions on the cavity surface of the bending plate 41. By forming an air insulation layer of fixed thickness, the cooling rate is physically limited from the principle of heat conduction, thus preventing the cooling rate from exceeding the standard. Moreover, this limitation is not affected by the temperature and flow rate of the coolant.

[0051] According to Fourier's law of heat conduction, the formula for calculating the heat conduction rate Φ (unit: W, which determines the cooling rate of the sheet metal) between the mold and the sheet metal is as follows: .

[0052] in: λ: Thermal conductivity of the heat transfer medium (the thermal conductivity of air is much smaller than that of mold steel); S: Effective heat transfer area (only the contact area between the micro-protrusions and the plate, which is significantly reduced); ΔT: Temperature difference between the mold and the sheet metal; δ: Thickness of the heat transfer medium (height of the micro-protrusion, i.e., the thickness of the air insulation layer, which is fixed at 0.03-0.06 mm).

[0053] Speed ​​control principle: The insulated micro-protrusions create a micron-level air step gap between the sheet metal and the mold cavity. The heat transfer medium changes from direct contact between the original mold steel to air + micro-protrusion steel body. The effective heat transfer area S is greatly reduced, and air gaps with low thermal conductivity are added to the heat transfer path. Ultimately, the heat conduction rate Φ is forcibly reduced, and the cooling rate of the sheet metal is physically locked in the slow cooling range of ≤20℃ / s. Even if the coolant temperature decreases in the later stage of cooling and the temperature difference ΔT between the mold and the sheet metal increases, the heat conduction rate will not exceed the upper limit, thus ensuring the slow cooling effect in principle.

[0054] Working principle: The flow control valve 13 has a built-in valve sleeve 14 made of temperature-sensitive deformation material (bimetallic strip / shape memory alloy). The valve sleeve 14 is triggered to deform by the change of coolant temperature, and the flow rate of the side flow pipe 12 is adaptively adjusted. When the coolant temperature drops in the later stage of cooling, the mainstream flow rate entering the curved cooling pipe 115 is further reduced, the flow rate is reduced, and the heat exchange efficiency is increased due to the decrease of coolant temperature.

[0055] In the early and middle stages of cooling: the temperature of the coolant entering the side flow pipe 12 is in the relatively high range of 30~45℃. The corrugated ring 142 of the valve sleeve 14 remains in its initial S-shaped undeformed state. The flow passage formed by the guide ring 141 and the inner wall of the flow control valve 13 is small, allowing only a small portion of the coolant to be diverted from the side flow pipe 12 to the outlet pipe 116. Most of the coolant still flows along the main stream into the twisted cooling pipe 114 and the bent cooling pipe 115. At this time, the flow rate and flow rate in the bent cooling pipe 115 match the slow cooling requirements of the high temperature of the plate in the early stage, and the heat exchange efficiency is moderate.

[0056] In the later stage of cooling: the torsion joint 42 and other areas of the inner plate 1 of the B-pillar have been cooled. The heat absorbed by the coolant has decreased, and the temperature has dropped below 28°C. The temperature-sensitive valve sleeve 14 is triggered by the low temperature to undergo directional deformation: the S-shaped structure of the corrugated ring 142 expands and slides along the inner wall of the flow control valve 13 through the limiting plate 143 connected by the crest. At the same time, the hinge rod 144 swings adaptively with the deformation of the corrugated ring 142, which ultimately greatly increases the diameter of the flow passage between the guide ring 141 and the inner wall of the flow control valve 13. After the flow passage is expanded, more coolant is directly diverted from the side flow pipe 12 to the outlet pipe 116. The flow rate of the mainstream coolant entering the curved cooling pipe 115 is further reduced, and the flow velocity is reduced again. This effectively offsets the problem of increased heat exchange efficiency caused by the decrease in coolant temperature, ensuring that the heat exchange efficiency in the curved cooling pipe 115 is always in the low-efficiency range required for slow cooling, and avoiding over-cooling of the plate.

[0057] The deformation of the valve sleeve 14 is triggered entirely by the change in coolant temperature. It does not require electronic control, sensors or external power sources. It is a purely mechanical passive adjustment with precise response and high reliability. At the same time, the limiting sliding design of the limit plate 143 and the movable connection of the hinge rod 144 ensure that the valve sleeve 14 deforms only in the set direction, avoids the flow diversion failure caused by uncontrolled deformation, and ensures the stability of the flow diversion adjustment in the later stage of cooling.

[0058] Valve sleeve 14 is preferably made of bimetallic strip (thermal bimetal), compatible with models 5J1480A / 5J1580 (manganese-nickel-copper + nickel-chromium composite bimetal), a grade specifically for automotive temperature control components, perfectly matching the temperature trigger range of this mold. The bimetallic strip is made of high manganese-nickel-copper alloy (active layer, thermal expansion coefficient α1≈18×10). -6 / ℃) and nickel-chromium alloy (passive layer, thermal expansion coefficient α2≈8×10) -6 The bimetallic sheet is formed by composite rolling at / ℃. When the temperature decreases, the shrinkage of the active layer is much greater than that of the passive layer, causing the bimetallic sheet to stretch and deform towards the active layer side, which drives the corrugated ring 142 to open and expand. When the temperature increases, it shrinks in the opposite direction and restores the initial S-shaped structure.

[0059] Core compatibility and precise temperature deformation range: This grade of bimetallic strip achieves directional bending / expansion deformation at 28-45℃. In the later stage of cooling, when the coolant temperature is ≤28℃, the 142S-shaped structure of the corrugated ring naturally expands, widening the flow channel; in the early and middle stage, at 30~45℃, it contracts and resets, and the small channel diverts the flow, which is completely consistent with the designed temperature control logic.

[0060] Strong deformation stability: Under repeated temperature cycles (early, middle and late stages of cooling), the deformation accuracy decay rate is ≤3%. The flow regulation effect of valve sleeve 14 does not drift during long-term use of the mold, ensuring the consistency of slow cooling control. Purely mechanical passive deformation: No electrical control or external power is required. Deformation is triggered only by the difference in thermal expansion coefficients of its own metal layer, which is highly matched with the design requirements of "temperature sensing self-regulation" of valve sleeve 14. Excellent working condition tolerance: It is resistant to corrosion from industrial coolant (ethylene glycol aqueous solution, a common cooling medium for molds), without oxidation or swelling, and has high mechanical strength. It can withstand the impact force of coolant flow (0.2~0.4MPa). It can stably seal when not deformed and will not be washed away by water flow. Good formability: It can be made into an integrated valve sleeve structure of S-shaped corrugated ring 142 + guide ring 141 through stamping and bending processes, and can be firmly connected with limit plate 143 and hinge rod 144, making mold processing difficult.

[0061] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A drawing die for a side panel of an automobile cab, characterized in that, The drawing die base (6) includes an upper pressing die (61) and a lower pressing die (62). A forming cavity (64) is provided between the upper pressing die (61) and the lower pressing die (62). The drawing die base (6) is also provided with a guide post (63) and a pressing hydraulic rod (65). A drawing template (66) is provided in the central area of ​​the upper pressing die (61). A drawing hydraulic rod (67) is fixed on the top of the drawing template (66). A fixing seat (7) is provided in the drawing template (66). The fixed seat (7) is connected to the upper pressing mold (61) by an extension plate (8). The lower half of the fixed seat (7) is provided with a bending pressing seat (91) and two torsion pressing seats (92). The bending pressing seat (91) and the torsion pressing seat (92) are respectively adapted to the bending plate (41) and the torsion section (42). The bending pressing seat (91) and the torsion pressing seat (92) are respectively limited and slidable with the fixed seat (7). The top of the bending pressing seat (91) is connected to a pressing hydraulic rod (93). A pressing structure (10) for torsion pressing force is provided between the outer periphery of the driving end of the pressing hydraulic rod (93) and the torsion pressing seat (92). The lower pressing die (62) is provided with an adaptive cooling structure (11) near the extrusion part (4) for slow cooling and rapid cooling of the bent plate (41) and the torsion joint (42) respectively.

2. The automobile cab side panel drawing die according to claim 1, characterized in that, The pressing structure (10) includes a pressing ring (101), which is installed on the outer periphery of the pressing hydraulic rod (93). A pressing rocker plate (102) is installed on the outer periphery of the pressing ring (101). One end of the pressing rocker plate (102) is located below the pressing ring (101), and the other end of the pressing rocker plate (102) is connected to the torsion pressure seat (92). A fixing sleeve (103) is connected between the center of the pressing rocker plate (102) and the inner wall of the fixing seat (7).

3. The automobile cab side panel drawing die according to claim 2, characterized in that, The pressure rocker (102) includes straight sections (1021) at both ends, and an arc section (1022) is connected between the two straight sections (1021). The arc section (1022) is movably connected to the fixed sleeve (103).

4. The automobile cab side panel drawing die according to claim 3, characterized in that, The adaptive cooling structure (11) includes an outlet (111) and two inlets (112). The inlets (112) are connected to an inlet pipe (113). The inlet pipe (113) is connected to a twisted cooling pipe (114). Two twisted cooling pipes (114) are connected to a curved cooling pipe (115) arranged at a distance.

5. The automobile cab side panel drawing die according to claim 4, characterized in that, The curved cooling pipe (115) is designed to reduce flow rate with a diameter larger than that of the twisted cooling pipe (114), and the curved cooling pipe (115) is connected to an outlet pipe (116) connected to the outlet (111).

6. The automobile cab side panel drawing die according to claim 5, characterized in that, The curved cooling pipe (115) is connected to a plurality of deceleration sections (117) for ensuring slow cooling. The liquid inlet (112) is connected to a side flow pipe (12) for depressurization. The liquid outlet end of the side flow pipe (12) flows into the liquid outlet pipe (116).

7. The automobile cab side panel drawing die according to claim 6, characterized in that, The deceleration section (117) includes a diagonal flow section (1171) inclined toward the liquid outlet direction, and a side confluence section (1172) for merging into the main flow to slow down the flow rate. The side confluence section (1172) is inclined in the opposite direction to the diagonal flow section (1171).

8. The automobile cab side panel drawing die according to claim 7, characterized in that, A flow control valve (13) is provided on the side flow pipe (12). A valve sleeve (14) is provided inside the flow control valve (13). The valve sleeve (14) is made of a material that can be deformed by sensing temperature. The valve sleeve (14) includes a flow guide ring (141) that communicates with the side flow pipe (12). A corrugated ring (142) extends from one side of the flow guide ring (141).

9. The automobile cab side panel drawing die according to claim 8, characterized in that, The corrugated ring (142) has an S-shaped curved structure. A limiting plate (143) is connected to the crest of the corrugated ring (142). The limiting plate (143) is connected to the flow control valve (13) for limiting sliding. A hinge rod (144) is movably connected between the limiting plate (143) and the flow guide ring (141).

10. The automobile cab side panel drawing die according to claim 9, characterized in that, The surface of the forming cavity (64) located at the position of the bending plate (41) is provided with multiple heat-insulating micro-protrusions, and the multiple heat-insulating micro-protrusions form a micron-level stepped gap with the drawn workpiece.

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