A multi-station integrated molding process for lightweight tinplate containers

Abstract

This invention discloses a multi-station integrated molding process for lightweight tinplate containers, comprising the following steps: Step 1: Raw material screening, employing automated visual inspection and a dual-parameter screening system for thickness and hardness, to inspect surface defects, thickness tolerances, and Vickers hardness of the raw materials for lightweight tinplate. The beneficial effects are: This invention integrates five major stages—material selection, pretreatment, molding, inspection, and storage—into a single production line, eliminating material transfer between equipment. Through closed-loop chemical station linkage, surface scratches and oxidation during transfer are avoided, significantly improving the pass rate of the finished lightweight tinplate containers. Simultaneously, after the molding station, laser ranging, ultrasonic stress detection, and visual defect identification enable full inspection of the finished products, rather than traditional offline sampling, avoiding missed inspections. Furthermore, the system automatically records the raw material parameters, molding parameters, and inspection data for each batch of finished products, allowing for rapid identification of the cause of quality problems.

Description

Technical Field

[0001] This invention relates to the field of lightweight tinplate container manufacturing technology, and in particular to a multi-station integrated molding process for lightweight tinplate containers. Background Technology

[0002] The molding process of lightweight tinplate containers mainly involves processing tinplate (also known as tin-plated steel sheet) material into containers with lightweight, durable and good sealing performance through a series of processes. Common lightweight tinplate containers include food cans, beverage cans and cosmetic bottles.

[0003] Existing lightweight tinplate containers have the following drawbacks during molding and processing:

[0004] 1. During the molding process, multiple machines are required to process the material in steps. Material transfer can easily lead to surface scratches and dimensional deviations. The parameters of each machine are not coordinated, resulting in large fluctuations in the quality of the finished product.

[0005] 2. Relying on manual experience to adjust process parameters, without a raw material and process matching mechanism, it is prone to tensile tearing, springback deformation, and lack of real-time monitoring of the molding process. Parameter deviations cannot be corrected in time, resulting in a high risk of defective products being released.

[0006] 3. Offline sampling inspection cannot cover all finished products, and hidden defects (such as internal stress concentration) are easily missed; without complete parameter records, it is difficult to locate quality problems and the rectification efficiency is low. Summary of the Invention

[0007] The purpose of this invention is to provide a lightweight tinplate container multi-station integrated molding process to solve the above-mentioned problems.

[0008] The present invention achieves the above objectives through the following technical solutions:

[0009] A multi-station integrated molding process for lightweight tinplate containers includes the following steps:

[0010] Step 1: Raw material screening. An automated visual inspection system and a dual-parameter screening system for thickness and hardness are used to screen lightweight tinplate. The system detects surface defects, thickness tolerances and Vickers hardness of the raw materials. Unqualified raw materials are automatically rejected to avoid subsequent molding defects caused by differences in raw materials.

[0011] Step 2: Raw material pretreatment. The raw materials are placed in a closed pretreatment chamber and first cleaned by spraying with a weakly alkaline degreasing solution at 15-20℃ to remove surface oil. Then, they are rinsed with high-pressure pure water and then placed in a passivation tank to form a protective film. The entire process is continuous. After pretreatment, the raw materials are dried with hot air to prevent oxidation caused by exposure to air. At the same time, food-grade lubricant is evenly applied to the tinplate surface using electrostatic spraying. The coating thickness is controlled at 5-10μm, and infrared detection is used to ensure the uniformity of the coating.

[0012] Step 3: Multi-station forming process. First, a hydraulically driven die-punch combination is used. The stretching force is dynamically adjusted according to the thickness of the raw material to stretch the tinplate to the semi-finished product outline. The stretching speed is 50-80mm / s to avoid material tearing caused by high-speed stretching. Then, the punch stroke accuracy is controlled by a servo motor to complete the final stretching and forming. At the same time, a rotating cutter is linked to trim the edges to ensure the flatness of the finished product edges. Next, an elastic die is used for shaping to eliminate residual stress after stretching. Then, low-temperature aging treatment is carried out to improve the structural stability of the finished product and reduce the risk of subsequent deformation.

[0013] Step 4: Quality Inspection and Sorting. First, the diameter, height, and wall thickness of the finished product are detected by a laser rangefinder and automatically judged as qualified by comparing with the design values. Then, a vision inspection system is used to identify defects such as surface scratches, dents, and coating damage. Next, ultrasonic testing is used to detect the internal stress distribution to avoid hidden cracks. After inspection, qualified finished products enter the next stage through the conveyor line, while unqualified products are automatically diverted to the waste bin. At the same time, the system records the defect type and corresponding process parameters to provide data support for subsequent process optimization.

[0014] Step 5: Post-processing of finished products. The softener and dust on the surface of the sorted lightweight tinplate containers are blown away, and the formed lightweight tinplate containers are packaged in sections to complete the forming process of lightweight tinplate containers.

[0015] Furthermore, in step 1, while screening raw materials, it is also necessary to call the corresponding molding parameters through the database according to the raw material specifications and finished product size, and input them into the central control system of the multi-station equipment to realize one-click matching of raw materials and processes, replacing traditional manual debugging.

[0016] Furthermore, in step 2, the concentration of the weakly alkaline degreasing solution is 2%-3%, the water pressure during high-pressure pure water rinsing is 0.3-0.5MPa, the passivation tank treatment chamber uses chromate or chromium-free passivating agent, the temperature is 30-40℃, the treatment time is 10-15s, the temperature during hot air drying is 60-80℃, and the wind speed is 1.5-2m / s, wherein the food-grade lubricant includes polytetrafluoroethylene emulsion.

[0017] Furthermore, in step 3, the relationship between tensile force and raw material thickness is as follows: 0.15 mm thickness corresponds to tensile force of 8-10 kN, and 0.3 mm thickness corresponds to tensile force of 15-18 kN; the temperature for low-temperature aging treatment is 120-150℃, and the time is 5-8 min.

[0018] Furthermore, in step 3, pressure sensors, displacement sensors, and vision inspection modules need to be installed at each forming station to monitor tensile force, punch stroke, and finished product dimensions in real time. The data is transmitted to the central control system. If parameter deviations occur (such as tensile force fluctuations of ±5%), the system automatically adjusts the equipment operating parameters to form a closed-loop control.

[0019] Furthermore, in step 4, the accuracy of measuring the diameter, height, and wall thickness of the finished product is ±0.003mm, and the accuracy of monitoring surface scratches on the finished product is ≥0.1mm.

[0020] Furthermore, in step 5, the purified high-pressure airflow is used to purge the finished product.

[0021] Furthermore, in step 1, during raw material screening, the tensile force gradient must be strictly controlled (the increase ratio of pre-stretching to fine stretching force ≤ 30%) to avoid local stress concentration leading to tearing. After passivation treatment, the integrity of the surface protective film must be ensured, and contact with sharp objects must be prohibited, otherwise the coating may easily peel off during molding.

[0022] Furthermore, the concentration of the weakly alkaline degreasing solution in step 2 and the passivating agent in the passivation tank needs to be checked regularly, preferably once every 8 hours, and replenished or replaced in a timely manner to ensure the pretreatment effect.

[0023] Furthermore, in step 3, during multi-station forming processing, the stretching path can be optimized for different finished product shapes (such as round cans and irregularly shaped lids). Circular parts are stretched symmetrically, while irregularly shaped parts are stretched in segments to avoid uneven material flow in certain areas. If the finished product exhibits springback deformation, the forming pressure can be appropriately increased or the low-temperature aging time can be extended until the springback amount is controlled within the design allowable range.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention integrates the five major processes of material selection, pretreatment, molding, testing, and storage into a single production line, eliminating the need for material transfer between equipment. Through the linkage of closed chemical stations, it avoids surface scratches and oxidation during transfer, thereby significantly improving the pass rate of lightweight tinplate containers.

[0026] 2. This invention achieves full inspection of finished products by using laser ranging, ultrasonic stress detection, and visual defect recognition after the molding station, instead of traditional offline sampling inspection, thus avoiding the phenomenon of missed inspections.

[0027] 3. This invention automatically records the raw material parameters, molding parameters, and test data of each batch of finished products, and can quickly locate the cause when quality problems occur. Attached Figure Description

[0028] Figure 1This is a flowchart of a multi-station integrated molding process for lightweight tinplate containers according to the present invention. Detailed Implementation

[0029] A multi-station integrated molding process for lightweight tinplate containers includes the following steps:

[0030] Step 1: Raw material screening. An automated visual inspection system and a dual-parameter screening system for thickness and hardness are used to screen lightweight tinplate. The system detects surface defects, thickness tolerances and Vickers hardness of the raw materials. Unqualified raw materials are automatically rejected to avoid subsequent molding defects caused by differences in raw materials.

[0031] Step 2: Raw material pretreatment. The raw materials are placed in a closed pretreatment chamber and first cleaned by spraying with a weakly alkaline degreasing solution at 15-20℃ to remove surface oil. Then, they are rinsed with high-pressure pure water and then placed in a passivation tank to form a protective film. The entire process is continuous. After pretreatment, the raw materials are dried with hot air to prevent oxidation caused by exposure to air. At the same time, food-grade lubricant is evenly applied to the tinplate surface using electrostatic spraying. The coating thickness is controlled at 5-10μm, and infrared detection is used to ensure the uniformity of the coating.

[0032] Step 3: Multi-station forming process. First, a hydraulically driven die-punch combination is used. The stretching force is dynamically adjusted according to the thickness of the raw material to stretch the tinplate to the semi-finished product outline. The stretching speed is 50-80mm / s to avoid material tearing caused by high-speed stretching. Then, the punch stroke accuracy is controlled by a servo motor to complete the final stretching and forming. At the same time, a rotating cutter is linked to trim the edges to ensure the flatness of the finished product edges. Next, an elastic die is used for shaping to eliminate residual stress after stretching. Then, low-temperature aging treatment is carried out to improve the structural stability of the finished product and reduce the risk of subsequent deformation.

[0033] Step 4: Quality Inspection and Sorting. First, the diameter, height, and wall thickness of the finished product are detected by a laser rangefinder and automatically judged as qualified by comparing with the design values. Then, a vision inspection system is used to identify defects such as surface scratches, dents, and coating damage. Next, ultrasonic testing is used to detect the internal stress distribution to avoid hidden cracks. After inspection, qualified finished products enter the next stage through the conveyor line, while unqualified products are automatically diverted to the waste bin. At the same time, the system records the defect type and corresponding process parameters to provide data support for subsequent process optimization.

[0034] Step 5: Post-processing of finished products. The softener and dust on the surface of the sorted lightweight tinplate containers are blown away, and the formed lightweight tinplate containers are packaged in sections to complete the forming process of lightweight tinplate containers.

[0035] In this embodiment, in step 1, while screening raw materials, it is also necessary to call the corresponding molding parameters through the database according to the raw material specifications and finished product size, and input them into the central control system of the multi-station equipment to realize one-click matching of raw materials and processes, replacing the traditional manual debugging.

[0036] In this embodiment, the concentration of the weakly alkaline degreasing solution in step 2 is 2%-3%, the water pressure during high-pressure pure water rinsing is 0.3-0.5MPa, the passivation tank treatment chamber uses chromate or chromium-free passivating agent, the temperature is 30-40℃, the treatment time is 10-15s, the temperature during hot air drying is 60-80℃, and the wind speed is 1.5-2m / s. The food-grade lubricant includes polytetrafluoroethylene emulsion.

[0037] In this embodiment, the relationship between tensile force and raw material thickness in step 3 is as follows: 0.15 mm thickness corresponds to tensile force of 8-10 kN, and 0.3 mm thickness corresponds to tensile force of 15-18 kN; the temperature for low-temperature aging treatment is 120-150℃, and the time is 5-8 min.

[0038] In this embodiment, in step 3, pressure sensors, displacement sensors, and vision inspection modules are also installed at each forming station to monitor tensile force, punch stroke, and finished product dimensions in real time. The data is transmitted to the central control system. If parameter deviations occur (such as tensile force fluctuations of ±5%), the system automatically adjusts the equipment operating parameters to form a closed-loop control.

[0039] In this embodiment, the accuracy of measuring the diameter, height, and wall thickness of the finished product in step 4 is ±0.003mm, and the accuracy of monitoring surface scratches on the finished product is ≥0.1mm.

[0040] In this embodiment, when purging the finished product in step 5, a purified high-pressure airflow is used for purging.

[0041] In this embodiment, during the raw material screening in step 1, the tensile force gradient must be strictly controlled (the increase ratio of pre-stretching to fine stretching force ≤ 30%) to avoid local stress concentration leading to tearing. After passivation treatment, the integrity of the surface protective film must be ensured, and contact with sharp objects must be prohibited, otherwise the coating may easily peel off during molding.

[0042] In this embodiment, the concentration of the weakly alkaline degreasing solution in step 2 and the passivating agent in the passivation tank needs to be checked regularly, preferably once every 8 hours, and replenished or replaced in a timely manner to ensure the pretreatment effect.

[0043] In this embodiment, during the multi-station forming process in step 3, the stretching path can be optimized for different finished product shapes (such as round cans and irregular lids). Circular parts are stretched symmetrically, while irregular parts are stretched in segments to avoid uneven material flow in certain areas. If the finished product exhibits springback deformation, the forming pressure can be appropriately increased or the low-temperature aging time can be extended until the springback amount is controlled within the design allowable range.

[0044] 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-station integrated molding process for lightweight tinplate containers, characterized in that: It includes the following steps: Step 1: Raw material screening. An automated visual inspection system and a dual-parameter screening system for thickness and hardness are used to screen lightweight tinplate. The system detects surface defects, thickness tolerances and Vickers hardness of the raw materials. Unqualified raw materials are automatically rejected to avoid subsequent molding defects caused by differences in raw materials. Step 2: Raw material pretreatment. The raw materials are placed in a closed pretreatment chamber and first cleaned by spraying with a weakly alkaline degreasing solution at 15-20℃ to remove surface oil. Then, they are rinsed with high-pressure pure water and then placed in a passivation tank to form a protective film. The entire process is continuous. After pretreatment, the raw materials are dried with hot air to prevent oxidation caused by exposure to air. At the same time, food-grade lubricant is evenly applied to the tinplate surface using electrostatic spraying. The coating thickness is controlled at 5-10μm, and infrared detection is used to ensure the uniformity of the coating. Step 3: Multi-station forming process. First, a hydraulically driven die-punch combination is used. The stretching force is dynamically adjusted according to the thickness of the raw material to stretch the tinplate to the semi-finished product outline. The stretching speed is 50-80mm / s to avoid material tearing caused by high-speed stretching. Then, the punch stroke accuracy is controlled by a servo motor to complete the final stretching and forming. At the same time, a rotating cutter is linked to trim the edges to ensure the flatness of the finished product edges. Next, an elastic die is used for shaping to eliminate residual stress after stretching. Then, low-temperature aging treatment is carried out to improve the structural stability of the finished product and reduce the risk of subsequent deformation. Step 4: Quality Inspection and Sorting. First, the diameter, height, and wall thickness of the finished product are detected by a laser rangefinder and automatically judged as qualified by comparing with the design values. Then, a vision inspection system is used to identify defects such as surface scratches, dents, and coating damage. Next, ultrasonic testing is used to detect the internal stress distribution to avoid hidden cracks. After inspection, qualified finished products enter the next stage through the conveyor line, while unqualified products are automatically diverted to the waste bin. At the same time, the system records the defect type and corresponding process parameters to provide data support for subsequent process optimization. Step 5: Post-processing of finished products. The softener and dust on the surface of the sorted lightweight tinplate containers are blown away, and the formed lightweight tinplate containers are packaged in sections to complete the forming process of lightweight tinplate containers.

2. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 1, while screening raw materials, it is also necessary to call the corresponding molding parameters from the database according to the raw material specifications and finished product size, and input them into the central control system of the multi-station equipment to achieve one-click matching of raw materials and processes, replacing traditional manual debugging.

3. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 2, the concentration of the weakly alkaline degreasing solution is 2%-3%, the water pressure during high-pressure pure water rinsing is 0.3-0.5MPa, the passivation tank treatment chamber uses chromate or chromium-free passivating agent, the temperature is 30-40℃, the treatment time is 10-15s, the temperature during hot air drying is 60-80℃, and the wind speed is 1.5-2m / s. The food-grade lubricant includes polytetrafluoroethylene emulsion.

4. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 3, the relationship between tensile force and raw material thickness is as follows: 0.15 mm thickness corresponds to tensile force of 8-10 kN, and 0.3 mm thickness corresponds to tensile force of 15-18 kN; the temperature for low-temperature aging treatment is 120-150℃, and the time is 5-8 min.

5. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 3, pressure sensors, displacement sensors, and vision inspection modules need to be installed at each forming station to monitor tensile force, punch stroke, and finished product dimensions in real time. The data is transmitted to the central control system. If parameter deviations occur (such as tensile force fluctuations of ±5%), the system automatically adjusts the equipment operating parameters to form a closed-loop control.

6. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 4, the accuracy of measuring the diameter, height, and wall thickness of the finished product is ±0.003mm, and the accuracy of monitoring surface scratches on the finished product is ≥0.1mm.

7. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 5, the finished product is purged using purified high-pressure airflow.

8. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 1, during raw material screening, the tensile force gradient must be strictly controlled (the increase ratio of pre-stretching to fine stretching force ≤ 30%) to avoid local stress concentration leading to tearing. After passivation treatment, the integrity of the surface protective film must be ensured, and contact with sharp objects must be prohibited, otherwise the coating may easily peel off during molding.

9. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: The concentration of the weakly alkaline degreasing solution in step 2 and the passivating agent in the passivation tank needs to be checked regularly, preferably once every 8 hours, and replenished or replaced in a timely manner to ensure the pretreatment effect.

10. The lightweight tinplate container multi-station integrated molding process according to claim 1, characterized in that: In step 3, during multi-station forming, the stretching path can be optimized for different finished product shapes (such as round cans and irregular lids). Round parts are stretched symmetrically, while irregular parts are stretched in segments to avoid uneven material flow in certain areas. If the finished product exhibits springback deformation, the forming pressure can be appropriately increased or the low-temperature aging time can be extended until the springback amount is controlled within the design allowable range.

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