Multi-pass flattening and gradient cooling composite strengthening production line and process for coil spring

Abstract

The invention relates to a multi-pass flattening and gradient cooling composite strengthening production line and process for a coil spring, and belongs to the technical field of machine manufacturing. The production line comprises a feeding device, a multi-pass flattening unit, a gradient cooling composite strengthening unit, an auxiliary function unit and a central control system. And through cooperative control of multi-pass progressive flattening and gradient cooling, precise forming of the cross section of the bar and optimization of the structure performance are achieved. The process comprises the steps of feeding, flattening, gradient cooling, cleaning, winding and the like. The problems that in a traditional technology, synergy is poor, cooling is uncontrollable, precision is low, and energy consumption is high are effectively solved, and the mechanical property, production efficiency and consistency of the coil spring are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of mechanical manufacturing technology, and more specifically, to a multi-pass flattening and gradient cooling composite strengthening production line and process for coil springs. Background Technology

[0002] As a core elastic load-bearing component, the mechanical properties of coil springs directly determine the operational safety and reliability of equipment. In the entire coil spring manufacturing process, the flattening pretreatment and cooling strengthening of the raw material bar are crucial steps. Flattening requires precisely machining the round bar into a flat cross-section to provide a reference end face for subsequent winding and forming, preventing coil spring end face distortion; cooling strengthening requires precise temperature control to suppress material decarburization and grain coarsening, thereby improving the overall mechanical properties of the coil spring.

[0003] Currently, the common processing technologies for coil spring raw materials mainly include the following three: Option 1: Single-pass high-strength flattening + natural cooling process; The bar stock is subjected to one-time high-pressure deformation using a single set of rolls, and then exposed to air for natural cooling (cooling rate <4℃ / s). This method has simple equipment, but the large deformation in a single pass can easily lead to residual stress inside the bar stock. The slow natural cooling rate can also cause coarse grains, resulting in a 15%-20% reduction in the fatigue life of the finished coil springs.

[0004] Option 2: Double-pass flattening + unified water cooling process; The bar cross-section is gradually reduced by two sets of rolls, and the bar is then fed into a water-cooling tank for cooling. Although this method improves the uniformity of deformation, the water-cooling tank is a single-rate cooling system (the cooling rate is fixed at 12-15℃ / s), which cannot match the optimal cooling requirements of coil spring raw materials (such as 60Si2MnA) in different temperature ranges (800℃-650℃ phase transformation zone, 650℃-450℃ martensitic transformation zone), and is prone to causing structural defects.

[0005] Option 3: Multi-pass flattening + manual air cooling process; The method employs a three-roll progressive flattening process, followed by air cooling via a fan. The cooling rate is controlled by adjusting the fan speed based on worker experience. While this method achieves progressive deformation, the precision of manual control is low (cooling rate fluctuation ±3℃ / s), and the flattening and cooling processes operate independently without coordinated control, resulting in low production efficiency (processing volume <220 pieces per hour) and difficulty in adapting to the needs of large-scale production.

[0006] In summary, the existing technology has the following core defects: 1. Poor coordination between flattening and cooling, lack of linkage control, and insufficient utilization of the hot window; 2. The cooling gradient is uncontrollable and cannot match the phase change requirements of different temperature ranges; 3. Insufficient production precision and consistency, large cross-sectional dimensional error (±0.25mm), reliance on manual transfer; 4. High energy consumption, low efficiency, requires multiple heating compensations, and serious process interruptions.

[0007] Therefore, we proposed a multi-pass flattening and gradient cooling composite reinforcement production line and process for coiled springs to solve the above problems. Summary of the Invention

[0008] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a multi-pass flattening and gradient cooling composite reinforcement production line and process for coil springs to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a multi-pass flattening and gradient cooling composite strengthening production line for coiled springs, comprising: Feeding device, used to feed bar stock into the flattening unit; A multi-pass flattening unit, including at least three flattening devices, is used for progressive flattening of bar stock; The gradient cooling composite strengthening unit includes an extrusion cooling device corresponding to each flattening device, which is used for gradient cooling in different temperature ranges. Auxiliary functional units include a cleaning device, a tension adjustment device, and a winding device; The central control system is used to monitor and adjust the parameters of each unit in real time to achieve coordinated control.

[0010] In a preferred embodiment, the feeding device employs a servo-driven feeding roller assembly with a feeding speed of 0m / min-12m / min and a feeding deviation of ≤±0.1mm.

[0011] In a preferred embodiment, the multi-pass flattening unit includes a first flattening device, a second flattening device, and a third flattening device, which respectively realize roughing, intermediate rolling, and finishing rolling. The gap between each roll is adjustable and equipped with a displacement sensor and a servo drive system.

[0012] In a preferred embodiment, the gradient cooling composite strengthening unit includes: The first extrusion cooling device is used for high-pressure water mist cooling in the 800℃-650℃ range; The second extrusion cooling device is used for air-water atomization cooling in the 650℃-450℃ range; The third extrusion cooling device is used for forced air cooling in the 450℃-300℃ range.

[0013] In a preferred embodiment, each extrusion cooling device integrates extrusion shaping and cooling functions and is equipped with a temperature sensor and a flow regulating valve.

[0014] In a preferred embodiment, the auxiliary functional unit includes: Pneumatic cleaning and drying device for removing surface impurities; Tension adjustment roller assembly, tension range adjustable from 600N to 2000N, using closed-loop control; The positioning and winding device has an adjustable winding diameter of 500mm-800mm and is equipped with a position sensor.

[0015] In a preferred embodiment, a multi-pass flattening and gradient cooling composite strengthening process for coil springs, using the production line described above, includes the following steps: Step 1: Raw material feeding; Step 2: Multi-pass progressive flattening; Step 3: Gradient cooling composite strengthening; Step 4: Online cleaning and winding; Step 5: Full-process monitoring and adjustment.

[0016] In a preferred embodiment, step three employs different cooling methods and rates depending on the temperature range: High-pressure water mist cooling is used for temperatures ranging from 800℃ to 650℃, with a rate of 16℃ / s to 18℃ / s. Air-water atomization cooling is used for temperatures ranging from 650℃ to 450℃, with a rate of 9℃ / s to 11℃ / s. Forced air cooling is used for temperatures ranging from 450℃ to 300℃, with a cooling rate of 4℃ / s to 6℃ / s.

[0017] In a preferred embodiment, the raw material is bar stock, and the bar stock is made of spring steel, including 60Si2MnA or 50CrVA, with a diameter range of 8mm-20mm.

[0018] The technical effects and advantages of this invention are as follows: 1. Significantly improved material mechanical properties: gradient cooling precisely matches phase transformation requirements, decarburized layer thickness ≤0.02mm, grain size refined to 5μm-7μm, tensile strength increased to 1950MPa-2100MPa, fatigue life qualification rate reaches over 99%, and service life extended by 25%-30%.

[0019] 2. Optimization of flattening accuracy and consistency: cross-sectional dimension error ≤ ±0.05mm, accuracy improved by 80%; product dimension consistency reaches over 98%.

[0020] 3. Balance between production efficiency and energy consumption: The continuous production mode increases the processing capacity to 450-500 pieces per hour, improving efficiency by 100%-127%; gradient cooling reduces energy consumption by 22% and reduces the number of heating compensation cycles.

[0021] 4. Enhanced process adaptability: It can be adapted to bars with different diameters from 8mm to 20mm and is compatible with various spring steel materials such as 60Si2MnA and 50CrVA to meet diverse production needs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall process flow in this invention; Figure 2 This is a schematic diagram of the pneumatic cleaning and drying process in this invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Reference Figure 1-2 The production line and process for multi-pass flattening and gradient cooling composite reinforcement of coiled springs includes two parts: production line structure design and process steps. The core structure of the production line can be seen in the attached diagram in the instruction manual. Figure 1 : The production line is laid out according to the entire process of "feeding-flattening-cooling-cleaning-winding", and its core components include: 1. Spring-loaded raw material feeding device: It adopts a servo-driven feeding roller group (feeding speed adjustable from 0-12m / min) and a guide positioning mechanism to ensure that the bar stock (diameter 8-20mm) enters the flattening unit accurately, with a feeding deviation ≤±0.1mm; 2. Multi-pass flattening unit: Includes three flattening devices (first flattening device, second flattening roller, and third flattening device), with roll gaps set in a gradient of "roughing-intermediate rolling-finishing". The first roll gap = bar diameter - 1.0 - 1.2 mm (section reduction of 25%). The gap between the second and third rolls is equal to the gap between the first and third rolls minus 0.8-1.0 mm (the cross-section is then reduced by 20%). The gap between the third and second rolls is equal to the gap between the second and third rolls minus 0.5-0.7 mm (the final cross-section is reduced by 15%). Each set of rolls is equipped with a displacement sensor (accuracy ±0.01mm) and a servo drive system to adjust the roll position in real time, ensuring that the error of the flat cross-section size after rolling is ≤±0.05mm; 3. Gradient Cooling Composite Strengthening Unit: Three extrusion cooling devices (first extrusion cooling device, second extrusion cooling device, and third extrusion cooling device) are set up corresponding to the three flattening devices. Each extrusion cooling device integrates the functions of "extrusion shaping + gradient cooling". The first extrusion cooling device (corresponding to a post-rolling temperature of 800℃-650℃): adopts high-pressure water mist cooling (pressure 0.9MPa-1.1MPa), with a cooling rate controlled at 16℃ / s-18℃ / s. At the same time, the extrusion rollers shape the rolled bar and eliminate surface wrinkles. The second extrusion cooling device (corresponding to a post-rolling temperature of 650℃-450℃): adopts air-water atomization cooling (air pressure 0.5MPa, water pressure 0.3MPa), with a cooling rate controlled at 9℃ / s-11℃ / s. The cross-sectional dimensions of the extrusion rolls are simultaneously fine-tuned to improve accuracy. The third extrusion cooling device (corresponding to a post-rolling temperature of 450℃-300℃): adopts forced air cooling (wind speed 6-8m / s), and the cooling rate is controlled at 4℃ / s-6℃ / s. The extrusion roll is finally shaped into a flat cross section, ensuring that the end face perpendicularity is ≤0.02mm. Each extrusion cooling unit is equipped with a temperature sensor (response time < 0.1s) and a flow regulating valve to achieve dynamic adjustment of cooling parameters; 4. Auxiliary functional units: including a surface pneumatic cleaning and drying device (compressed air pressure 0.6MPa-0.7MPa, airflow angle 45°, to remove residual water mist and impurities from the surface), a tension adjusting roller group (tension range 600N-2000N adjustable, using closed-loop control, tension fluctuation ≤±50N, to prevent bar stock deviation), and a positioning and winding device (winding diameter 500mm-800mm adjustable, equipped with a position sensor to ensure neat winding and easy access for subsequent processes); 5. Central Control System: Integrates PLC and touch screen to collect parameters such as roll gap, cooling temperature, and tension value in real time, realize the linkage control of multi-pass flattening and gradient cooling, and automatically alarm and adjust parameters when abnormal.

[0025] Core process steps: 1. Raw material feeding: The coil spring raw material bar (such as 60Si2MnA) is fed into the production line through the coil spring raw material feeding device, and after being guided and positioned, it enters the first flattening device; 2. Multi-pass progressive flattening: Start the three-pass flattening device and progressively roll the material in the order of "first pass rough rolling (section reduction of 25%) - second pass intermediate rolling (section reduction of another 20%) - third pass finish rolling (section reduction of a final 15%)". The central control system adjusts the roll gap in real time based on the feedback from the displacement sensor to ensure that the dimensional error of the flattened section after rolling is ≤ ±0.05mm. 3. Gradient cooling composite strengthening: The flattened bar stock simultaneously enters the corresponding extrusion cooling device, and the cooling parameters are dynamically adjusted according to the real-time temperature of the bar stock. First extrusion cooling: When the bar temperature is 800℃-650℃, high-pressure water mist cooling is turned on, maintaining a cooling rate of 16℃ / s-18℃ / s, while the extrusion rollers shape the cross section. Second extrusion cooling: When the bar temperature drops to 650℃-450℃, switch to air-water atomization cooling, adjust the rate to 9℃ / s-11℃ / s, and fine-tune the size of the extrusion rollers; The third stage of extrusion cooling: When the bar temperature drops to 450℃-300℃, forced air cooling is started, and the rate is controlled at 4℃ / s-6℃ / s. The extrusion rolls are then finally shaped. 4. Online cleaning and winding: After cooling, the bar stock is cleaned and dried by a pneumatic surface cleaning and drying device to remove surface impurities and water mist. Then, the tension is maintained by a tension adjusting roller group, and finally, the positioning winding device is wound into finished flat stock. 5. Full-process monitoring: During the production process, the central control system monitors the parameters of each process in real time, and automatically alarms and adjusts when abnormalities occur to ensure production stability.

[0026] Cylindrical raw materials pass through a guide wheel assembly, then through a first flattening device, a first extrusion device, a second flattening wheel, a second extrusion device, a third flattening device, a third extrusion device, a surface pneumatic cleaning and drying device, a tension adjusting wheel assembly, and a positioning winding device, finally forming a flat material. Liquid cooling pipelines are installed in all three stages (first extrusion, second flattening wheel, second extrusion, third flattening device, and third extrusion device) to manage the heat generated during the flattening process.

[0027] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-pass flattening and gradient cooling composite strengthening production line for coiled springs, characterized in that, include: Feeding device, used to feed bar stock into the flattening unit; A multi-pass flattening unit, including at least three flattening devices, is used for progressive flattening of bar stock; The gradient cooling composite strengthening unit includes an extrusion cooling device corresponding to each flattening device, which is used for gradient cooling in different temperature ranges. Auxiliary functional units include a cleaning device, a tension adjustment device, and a winding device; The central control system is used to monitor and adjust the parameters of each unit in real time to achieve coordinated control.

2. The multi-pass flattening and gradient cooling composite strengthening production line for coiled springs according to claim 1, characterized in that: The feeding device adopts a servo-driven feeding roller assembly with a feeding speed of 0m / min-12m / min and a feeding deviation of ≤±0.1mm.

3. The multi-pass flattening and gradient cooling composite strengthening production line for coiled springs according to claim 1, characterized in that: The multi-pass flattening unit includes a first flattening device, a second flattening device, and a third flattening device, which respectively realize roughing, intermediate rolling, and finishing rolling. The gap between each roll is adjustable and equipped with a displacement sensor and a servo drive system.

4. The multi-pass flattening and gradient cooling composite strengthening production line for coiled springs according to claim 1, characterized in that: The gradient cooling composite strengthening unit includes: The first extrusion cooling device is used for high-pressure water mist cooling in the 800℃-650℃ range; The second extrusion cooling device is used for air-water atomization cooling in the 650℃-450℃ range; The third extrusion cooling device is used for forced air cooling in the 450℃-300℃ range.

5. The multi-pass flattening and gradient cooling composite strengthening production line and process for coiled springs according to claim 4, characterized in that: Each extrusion cooling unit integrates extrusion shaping and cooling functions, and is equipped with a temperature sensor and a flow regulating valve.

6. The multi-pass flattening and gradient cooling composite strengthening production line for coiled springs according to claim 1, characterized in that: The auxiliary function units include: Pneumatic cleaning and drying device for removing surface impurities; Tension adjustment roller assembly, tension range adjustable from 600N to 2000N, using closed-loop control; The positioning and winding device has an adjustable winding diameter of 500mm-800mm and is equipped with a position sensor.

7. A multi-pass flattening and gradient cooling composite strengthening process for coil springs, employing the production line described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Raw material feeding; Step 2: Multi-pass progressive flattening; Step 3: Gradient cooling composite strengthening; Step 4: Online cleaning and winding; Step 5: Full-process monitoring and adjustment.

8. The multi-pass flattening and gradient cooling composite strengthening process for coil springs according to claim 7, characterized in that: In step three, different cooling methods and rates are used depending on the temperature range: High-pressure water mist cooling is used for temperatures ranging from 800℃ to 650℃, with a rate of 16℃ / s to 18℃ / s. Air-water atomization cooling is used for temperatures ranging from 650℃ to 450℃, with a rate of 9℃ / s to 11℃ / s. Forced air cooling is used for temperatures ranging from 450℃ to 300℃, with a cooling rate of 4℃ / s to 6℃ / s.

9. The multi-pass flattening and gradient cooling composite strengthening process for coil springs according to claim 7, characterized in that: The raw material is bar stock, which is made of spring steel, including 60Si2MnA or 50CrVA, with a diameter range of 8mm-20mm.

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