Spiral blades, also known as screw flights or auger flights, are essential components in various industries, particularly for material handling in conveyors, mixers, and agricultural machinery. Traditionally, these blades were often formed using hot forging or drawing methods. However, the “cold pressing” process offers significant advantages, including improved material properties, reduced energy consumption, and often, a simpler manufacturing setup, especially for continuous spiral blades.
This guide will detail the step-by-step process of manufacturing spiral blades through cold pressing, highlighting the precision and specialized machinery involved in transforming flat strip steel into robust helical forms.
The Helix Unveiled: A Step-by-Step Cold Pressing Spiral Blade Production Guide
The cold pressing process for spiral blades typically involves specialized machinery that continuously forms the helical shape from a flat metal strip at room temperature.
Step 1: Material Selection and Preparation
The choice and initial handling of the raw material are fundamental to the success of the cold pressing process.
- Material Specification: Select the appropriate metal type (e.g., mild steel (MS), stainless steel (SS), or other high-strength steel plate) based on the spiral blade’s intended application, required strength, corrosion resistance, and wear characteristics.
- Strip Dimensions: Ensure the metal strip has the precise width and thickness specified for the desired spiral blade dimensions (inner diameter, outer diameter, and pitch). The thickness can range from a few millimeters up to 12mm or more, depending on the machine’s capacity and blade application.
- Coil Acquisition: The material is typically acquired in large coils, which are ideal for continuous cold rolling processes.
- Cleaning and Inspection: The raw material coil should be clean and free from surface defects, rust, or contaminants that could affect the forming process or the quality of the finished blade.
Step 2: Machine Setup and Tooling Installation
The specialized cold rolling mill is the heart of this process; its setup is critical for accurate blade formation.
- Machine Selection: Utilize a dedicated spiral blade cold rolling mill, which typically features a robust welded structure, a hydraulic system, and a mold/roller device.
- Mold/Roller Installation: Install the appropriate conical rolls (molds) onto the machine’s mold seat. These rolls are precisely shaped to impart the helical form. A single set of rolls can often produce various sizes of spiral blades by adjustment.
- Roller Adjustment: Adjust the upper and lower positions of the molds/rolls according to the thickness of the processed strip steel.
- Guide Wheel Configuration: Adjust guide wheels and other guiding mechanisms to ensure the strip steel feeds smoothly and is precisely positioned between the conical rolls.
- Hydraulic System Activation: Turn on the hydraulic system, which powers the movement of the movable mold seats and provides the necessary rolling pressure.
- Cooling System Setup: Ensure the recycle cooling system for the rollers is active. This protects the rollers from wear and tear during continuous operation.
Step 3: Strip Feeding and Initial Positioning
Proper feeding ensures a continuous and consistent forming process.
- Load Strip Coil: Load the prepared metal strip coil onto the machine’s decoiler or feeding mechanism.
- Thread the Strip: Carefully thread the leading end of the strip steel between the conical rolls and through any initial guide components.
- Adjust Feeding Height: Adjust the feeding height to ensure the strip is centered and properly engaged with the rolls.
- Secure Initial End: For some processes, one end of the strip (or a pre-cut blank) might be fixed or clamped to initiate the spiral formation.
Step 4: Cold Rolling and Spiral Formation
This is the core process where the helical shape is continuously formed.
- Machine Start-Up: Initiate the cold rolling machine. The hydraulic system drives the conical rolls to rotate and apply continuous pressure to the strip steel.
- Continuous Forming: As the strip passes between the conical rolls, the pressure and the relative movement of the rolls cause the metal to deform plastically. The edges of the strip are typically thinned, and internal stresses are induced, causing the strip to naturally curve and form into a continuous spiral shape.
- Pitch and Diameter Control: The machine’s design allows for real-time adjustments to parameters such as roll offset, feeding height, and rolling pressure to control the inner diameter, outer diameter, and pitch of the continuously formed spiral blade.
- Monitoring: Operators continuously monitor the forming process to ensure the spiral blade is forming correctly, with uniform thickness and minimal size error.
Step 5: Cutting to Length
Once the desired length of the spiral blade is formed, it is cut.
- Length Measurement: The machine’s control system or an integrated sensor measures the length of the continuously formed spiral blade.
- Hydraulic Shearing: A hydraulic shear unit, typically positioned above the formed spiral blade, lifts up and cuts the blade to the required length. This allows for precise, automated cutting.
Step 6: Post-Forming Processes (Optional)
Further processing may be required depending on the application.
- Deburring: Although cold pressing generally produces smoother edges than some other methods, minor burrs may still be present. Deburring operations (e.g., grinding, sanding, tumbling) may be performed to achieve a clean, smooth edge.
- Welding to Shaft/Pipe: The individual spiral blade sections (or continuous flights) are often welded onto a central shaft or pipe to create a complete screw conveyor or auger.
- Surface Treatment: Depending on the application, the spiral blades may undergo surface treatments such as painting, powder coating, galvanizing, or polishing to enhance corrosion resistance, wear resistance, or aesthetics.
Step 7: Quality Control and Inspection
Rigorous inspection ensures the final blade meets specifications.
- Dimensional Checks: Measure the outer diameter, inner diameter, pitch, and thickness of the formed spiral blades to ensure they meet specified tolerances.
- Visual Inspection: Inspect for any defects such as cracks, unevenness, or deformities in the helical shape.
- Material Integrity: For critical applications, non-destructive testing (NDT) methods may be used to verify material integrity.
Step 8: Packaging and Storage
The final steps prepare the spiral blades for shipment or assembly.
- Protective Packaging: Package the finished spiral blades securely to prevent damage during transport and storage. This may involve bundling, wrapping, or crating.
- Labeling: Attach appropriate labels indicating dimensions, material, and quantity.
Conclusion
The cold pressing spiral blade manufacturing process is a testament to modern metal forming capabilities, enabling the efficient and precise production of helical components. By leveraging specialized cold rolling mills and meticulous control over material feeding and forming parameters, manufacturers can create high-quality, continuous spiral blades with excellent dimensional accuracy and material properties. This streamlined process plays a crucial role in supporting industries that rely on efficient material handling and conveying systems.
