Continuous Shot Blasting Machine for Stainless Steel Strips

Stainless steel strips are widely used in various industries such as food processing, medical equipment, automotive, electronics, and construction due to their excellent corrosion resistance, high temperature resistance, and good mechanical properties. However, during the production process of stainless steel strips (such as hot rolling, cold rolling, and annealing), the surface will inevitably generate oxide scale, oil stains, and other impurities. These impurities not only affect the surface finish and appearance quality of stainless steel strips but also reduce their corrosion resistance and affect the effect of subsequent processing (such as coating, printing, and stamping). Therefore, surface cleaning is a key link in the production of stainless steel strips. The continuous shot blasting machine for stainless steel strips is a specialized equipment designed for the surface cleaning of stainless steel strips. It has the advantages of continuous operation, high cleaning efficiency, and good surface quality, and has become an indispensable key equipment in the stainless steel strip production line.

The continuous shot blasting machine for stainless steel strips operates based on the principle of high-velocity shot impact. The machine uses a blast wheel to accelerate the shot to a high speed and project it onto the surface of the moving stainless steel strip. The impact force of the shot breaks and strips the oxide scale and oil stains on the surface of the stainless steel strip, thereby achieving the purpose of surface cleaning. At the same time, the impact of the shot also causes a certain degree of plastic deformation on the surface of the stainless steel strip, forming a compressive stress layer, which can improve the surface hardness, wear resistance, and fatigue resistance of the stainless steel strip. Compared with traditional surface cleaning methods such as pickling, electrolytic cleaning, and grinding, continuous shot blasting has the advantages of continuous operation, high efficiency, environmental protection, and no damage to the base material.

The structural design of the continuous shot blasting machine for stainless steel strips is highly specialized to adapt to the characteristics of stainless steel strips (such as thin thickness, wide width, continuous movement, and high surface quality requirements). The main components of the machine include the unwinding device, tension control device, shot blasting chamber, blast wheel system, shot recovery and separation system, dust removal system, winding device, and electrical control system. These components are closely connected to form a continuous production line, ensuring the continuous and stable operation of the stainless steel strip surface cleaning process.

The unwinding device is located at the entrance of the production line and is responsible for unwinding the coiled stainless steel strip. It is usually composed of an unwinding reel, a support frame, a hydraulic cylinder, and a brake device. The unwinding reel is used to fix the stainless steel coil, and the hydraulic cylinder drives the reel to expand to clamp the coil. The brake device is used to control the unwinding speed and prevent the stainless steel strip from being pulled too tightly or too loosely during the unwinding process. Some advanced unwinding devices are equipped with automatic centering devices to ensure that the stainless steel strip runs along the center line of the production line, avoiding deviation.

The tension control device is an important part of the continuous shot blasting machine, which is responsible for maintaining a stable tension of the stainless steel strip during the movement process. Stable tension is crucial to ensure the flatness of the stainless steel strip and the uniformity of the shot blasting effect. If the tension is too large, the stainless steel strip may be stretched or even broken; if the tension is too small, the stainless steel strip may wrinkle or deviate, affecting the shot blasting effect. The tension control device usually consists of tension rollers, pressure sensors, and a control system. The pressure sensor detects the tension of the stainless steel strip in real time and transmits the signal to the control system. The control system adjusts the speed of the unwinding device and the winding device according to the detected tension value to maintain the tension within the set range.

The shot blasting chamber is the core part of the machine where the surface cleaning operation is carried out. It is an enclosed space designed to prevent the shot and dust from splashing. The inner wall of the shot blasting chamber is lined with high-wear-resistant materials such as polyurethane plates or rubber plates to withstand the continuous impact of the shot. The shot blasting chamber is equipped with multiple blast wheels arranged above and below the stainless steel strip to ensure that both the upper and lower surfaces of the stainless steel strip can be fully shot blasted. The number and arrangement of the blast wheels are determined according to the width and thickness of the stainless steel strip and the required cleaning effect. For wide stainless steel strips (such as width greater than 2 meters), multiple blast wheels are usually arranged in parallel on each side to ensure uniform coverage of the entire width of the strip. The blast wheels are designed with a special structure to ensure that the shot is projected onto the surface of the stainless steel strip at a certain angle and speed, maximizing the cleaning effect.

The blast wheel system is the power source of the shot blasting machine, consisting of blast wheels, motors, reducers, and shot feeding devices. The motors drive the blast wheels to rotate at a high speed (usually 2500-4000 rpm) through reducers. The shot feeding devices (such as screw conveyors or vibratory feeders) continuously feed the shot into the blast wheels. Under the action of centrifugal force, the shot is accelerated and projected onto the surface of the stainless steel strip. The blast wheels for stainless steel strip shot blasting machines are usually made of high-chromium alloy steel or wear-resistant ceramic materials to ensure wear resistance and service life. In addition, the shot feeding devices are equipped with adjustable flow valves to control the amount of shot fed into the blast wheels, thereby adjusting the impact force and cleaning effect.

The shot recovery and separation system is responsible for recycling the used shot and separating it from the oxide scale, oil stains, and other impurities. This system is crucial to reduce the consumption of shot and ensure the cleanliness of the working environment. The system usually consists of a hopper, a screw conveyor, a bucket elevator, a separator, and a storage silo. After the shot impacts the stainless steel strip, it falls into the hopper at the bottom of the shot blasting chamber along with the oxide scale and impurities. The screw conveyor transports the mixture to the bucket elevator, which lifts the mixture to the separator. The separator uses the principle of gravity and wind force to separate the shot (high density) from the impurities (low density). The separated clean shot is sent to the storage silo for reuse, while the oxide scale and impurities are discharged to the waste bin for centralized treatment. For the continuous shot blasting machine for stainless steel strips, the separator must have high separation efficiency to ensure that the recycled shot is clean and free of impurities, which avoids scratching the surface of the stainless steel strip.

The dust removal system is used to collect the dust and fine oxide scale particles generated during the shot blasting process. The dust generated during the cleaning of stainless steel strips contains a large amount of stainless steel dust and oxide scale dust, which is harmful to the health of operators and pollutes the environment. The dust removal system usually consists of a bag filter, a fan, a dust duct, and a dust hopper. The fan generates negative pressure in the shot blasting chamber, and the dust is sucked into the bag filter through the dust duct. The bag filter filters the dust, and the clean air is discharged into the atmosphere after reaching the national environmental protection standards. The collected dust is discharged into the dust hopper for centralized treatment. Some advanced dust removal systems are equipped with automatic ash cleaning devices to ensure the continuous and stable operation of the dust removal system.

The winding device is located at the exit of the production line and is responsible for winding the cleaned stainless steel strip into a coil. It is usually composed of a winding reel, a support frame, a hydraulic cylinder, and a drive motor. The drive motor drives the winding reel to rotate, and the hydraulic cylinder drives the reel to expand to clamp the coil. The winding speed is controlled by the tension control system to ensure that the tension of the stainless steel strip is stable during the winding process. Some winding devices are equipped with automatic leveling devices to ensure that the wound coil is flat and neat. In addition, the winding device is usually equipped with a cutting device to cut the stainless steel strip into the required length after the winding is completed.

The electrical control system is the core of the entire continuous shot blasting machine, responsible for controlling the operation of each component and ensuring the continuous and stable operation of the production line. The system is usually composed of a PLC, an HMI, sensors, and actuators. The PLC is responsible for processing the input signals from the sensors and sending control signals to the actuators to control the operation of the unwinding device, tension control device, blast wheel system, shot recovery system, dust removal system, and winding device. The HMI provides a human-machine interaction interface for operators to set parameters (such as the speed of the stainless steel strip, the rotating speed of the blast wheels, the amount of shot, and the tension), monitor the operation status of the machine, and handle faults. The sensors (such as tension sensors, speed sensors, and pressure sensors) detect the operating parameters of the machine in real time and transmit the signals to the PLC. The electrical control system is equipped with multiple safety protection devices, such as emergency stop buttons, safety door interlocks, and overload protection, to ensure the safety of operators and equipment.

The continuous shot blasting machine for stainless steel strips has a wide range of applications in the stainless steel industry. It is suitable for the surface cleaning of various types of stainless steel strips, such as austenitic stainless steel strips (304, 316L), ferritic stainless steel strips (430), and martensitic stainless steel strips (410). It is widely used in the production lines of cold-rolled stainless steel strips, hot-rolled stainless steel strips, and annealed stainless steel strips. For example, in the cold-rolled stainless steel strip production line, the continuous shot blasting machine is used to remove the oxide scale generated during the annealing process, improving the surface finish of the strip and preparing for subsequent processing such as pickling and polishing. In the hot-rolled stainless steel strip production line, the machine is used to remove the thick oxide scale generated during the hot rolling process, reducing the difficulty of subsequent processing. In addition, the continuous shot blasting machine is also used in the surface treatment of stainless steel strips for special purposes, such as the production of stainless steel strips for food packaging and medical equipment, which require high surface cleanliness.

Compared with traditional surface cleaning methods, the continuous shot blasting machine for stainless steel strips has many unique advantages. First, continuous operation. The machine can realize continuous cleaning of stainless steel strips, which is suitable for large-scale and high-speed production lines. The processing speed can reach 10-100 m/min, which is much higher than the discontinuous cleaning methods such as manual cleaning and batch shot blasting. Second, high cleaning efficiency and uniform effect. The multiple blast wheels arranged above and below the stainless steel strip ensure that both surfaces of the strip are fully shot blasted, and the cleaning effect is uniform. The surface of the cleaned stainless steel strip has a uniform matte finish, which improves the appearance quality. Third, environmental protection. Traditional pickling methods use strong acids to remove oxide scale, which generates a large amount of acid waste water and acid mist, causing serious pollution to the environment. Continuous shot blasting is a dry processing method that does not use any chemicals, and the generated dust and oxide scale can be collected and treated centrally, which meets the requirements of green production. Fourth, no damage to the base material. The shot used for stainless steel strip cleaning is usually made of soft materials such as glass bead or stainless steel shot with low hardness, which can remove oxide scale without scratching the surface of the stainless steel strip. This ensures the surface quality and mechanical properties of the stainless steel strip. Fifth, surface strengthening. The impact of the shot on the surface of the stainless steel strip forms a compressive stress layer, which improves the surface hardness, wear resistance, and fatigue resistance of the strip. This extends the service life of the stainless steel strip in practical applications.

During the operation of the continuous shot blasting machine for stainless steel strips, operators need to pay attention to the following key points to ensure the cleaning effect and operational safety. First, the selection of shot. The type, size, and hardness of the shot are crucial to the cleaning effect and surface quality of the stainless steel strip. For stainless steel strips that require a high surface finish (such as food packaging and medical equipment), glass bead or stainless steel shot with small size and low hardness is usually used. For stainless steel strips with thick oxide scale, steel shot with larger size and higher hardness can be used. The size of the shot should be selected according to the thickness of the oxide scale and the surface requirements of the strip. Second, the adjustment of processing parameters. The key processing parameters include the speed of the stainless steel strip, the rotating speed of the blast wheels, and the amount of shot. Operators need to adjust these parameters according to the type, thickness, and surface condition of the stainless steel strip. For example, for strips with thick oxide scale, the rotating speed of the blast wheels and the amount of shot should be increased, and the speed of the strip should be reduced to ensure sufficient impact time. For strips with high surface finish requirements, the rotating speed of the blast wheels and the amount of shot should be appropriately reduced to avoid damaging the surface. Third, the control of tension. Stable tension is crucial to ensure the flatness of the stainless steel strip. Operators should regularly check the tension control device, ensure that the tension sensor is accurate, and adjust the tension in time when deviations occur. Fourth, the inspection and maintenance of the machine. Before starting the machine, operators should check whether the blast wheels, blades, liners, and other components are worn or damaged, whether the shot recovery and separation system is unblocked, and whether the dust removal system is working normally. During the operation process, operators should monitor the operation status of the machine in real time, and stop the machine immediately to check and handle any abnormal phenomena (such as abnormal noise, vibration, or deviation of the strip). After the operation, operators should clean the machine, remove the residual shot and dust, and lubricate the moving parts. Fifth, safety protection. Operators must wear protective equipment such as safety helmets, goggles, earplugs, and protective clothing when operating the machine. They should not touch the moving parts of the machine or open the safety door of the shot blasting chamber during the operation process to avoid accidents.

The maintenance of the continuous shot blasting machine for stainless steel strips is essential to ensure its long-term stable operation and extend its service life. Daily maintenance work includes: checking the wear of the blast wheel blades, liners, and shot feeding devices, and replacing them in time when the wear exceeds the limit; checking the tension of the conveyor belt and chain, and adjusting and lubricating them in time; cleaning the shot recovery and separation system to prevent blockage of the hopper, screw conveyor, and separator; maintaining the dust removal system, such as cleaning the filter bag and checking the fan; checking the electrical system, such as the wiring, connectors, and sensors, to ensure the safety and reliability of the electrical components. Regular maintenance work includes: disassembling and inspecting the blast wheels, cleaning the internal components, and replacing the worn parts; inspecting and repairing the reducer, motor, and other transmission components; checking the thickness of the liner in the shot blasting chamber and replacing it if necessary; calibrating the sensors and instruments of the electrical control system to ensure the accuracy of the parameters; and inspecting the unwinding and winding devices, adjusting the hydraulic system, and replacing the seals if necessary.

With the continuous development of the stainless steel industry, the requirements for the surface quality and production efficiency of stainless steel strips are getting higher and higher, which promotes the continuous innovation and development of continuous shot blasting machines for stainless steel strips. The future development trends of such machines are mainly reflected in the following aspects: first, higher intelligence and automation. The integration of advanced technologies such as IIoT, AI, and machine vision makes the machine capable of real-time monitoring of the cleaning process, automatic identification of the surface condition of the stainless steel strip, and automatic adjustment of processing parameters. For example, machine vision technology can detect the surface cleanliness and finish of the stainless steel strip in real time, and the system can automatically adjust the rotating speed of the blast wheels, the amount of shot, and the speed of the strip according to the detection results to ensure the best cleaning effect. Second, higher processing speed and efficiency. The optimization of the blast wheel structure, the adoption of high-power motors, and the improvement of the shot recovery system can improve the processing speed of the machine, which is suitable for the high-speed production lines of stainless steel strips. Third, better surface quality. The development of new shot materials and blast wheel designs can further improve the cleaning effect and surface finish of the stainless steel strip, meeting the requirements of high-end applications. Fourth, environmental protection and energy saving. The adoption of more efficient dust removal and noise reduction technologies, the use of energy-saving motors and frequency conversion technology, and the recycling of shot and oxide scale can reduce the energy consumption and environmental impact of the machine. Fifth, modular design. The modular design of the machine makes it easier to install, maintain, and upgrade. Manufacturers can provide customized modules according to the specific needs of users, improving the flexibility and adaptability of the machine. Sixth, online detection and feedback. The integration of online detection equipment (such as surface roughness meters and cleanliness detectors) into the production line can realize real-time detection of the surface quality of the stainless steel strip, and the feedback signal can be used to adjust the processing parameters, ensuring the stability and consistency of the product quality.

In conclusion, the continuous shot blasting machine for stainless steel strips is a key equipment in the stainless steel strip production line, which plays an important role in improving the surface quality of stainless steel strips, improving production efficiency, protecting the environment, and reducing production costs. With the continuous progress of technology, the performance and function of the machine will be further improved, and it will better meet the development needs of the stainless steel industry. Enterprises engaged in the production of stainless steel strips should choose suitable continuous shot blasting machines according to their own production needs, strengthen the training of operators, do a good job in the operation and maintenance of the machines, and continuously improve the quality of their products to enhance their market competitiveness.