Essence of the Equipment: The "Precise Cutting Center" for Fixed-length Processing of Steel Bars
The CNC steel bar shearing production line is a fully automated set of equipment integrating steel bar feeding, straightening, fixed-length detection, high-precision shearing, and finished product sorting. Its core function is to cut coiled bars or straight bars into standardized sections of preset lengths according to engineering requirements, providing precise billets for subsequent processes such as bending, threading, and welding. It overcomes the limitations of traditional single-machine shearing, such as large length errors, low efficiency, and the need for manual intervention.
Technical Core: Precise Cutting Logic through the Collaboration of Four Major Systems
The CNC steel bar shearing production line completes processing through the continuous sequence of "feeding and straightening – fixed-length detection – precise shearing – finished product output," relying on the seamless collaboration of four major systems: mechanical, electrical, sensing, and CNC. Its technical principle can be divided into two main aspects: core structure and working process.
- Core construction system
The modern CNC steel bar shearing production line is composed of five major functional modules. The connection accuracy of each module must be controlled within ±0.3mm to ensure stable cutting quality.
Intelligent feeding system: Divided into two types, wire rod feeding and straight bar feeding. Wire rod feeding uses a hydraulic wire release frame with a load capacity of 2 to 5 tons, with a tension adjustment mechanism to prevent steel bar entanglement. Straight bar feeding uses a chain conveyor frame, which can carry steel bars 6 to 12 meters in length. Automatic feeding is triggered by photoelectric sensors.
Multi-roller straightening system: Consisting of 8 to 12 sets of straightening rollers made of Cr12MoV alloy, with a surface hardness of HRC58–62 after quenching. Driven by servo motors, they achieve stepless speed regulation (30–120m/min).
Numerical control fixed-length system: Composed of high-precision encoders (resolution 0.01mm), servo feeding rollers, and positioning stop blocks. The encoder provides real-time feedback on the bar feed length, forming a closed-loop control with the PLC. Shearing length (500–12000mm) is set via the touch screen. The positioning stop block response speed is ≤0.1s to ensure length accuracy.
Precision cutting system: Usually adopts a hydraulically driven shearing tool rest. The blades are made of hard alloy, with edge hardness above HRC60, capable of withstanding a shearing force of 500–800 MPa. Shearing speed is automatically adjusted according to bar diameter (e.g. φ16 rebar: 0.2s, φ40 rebar: 0.5s). The verticality error of the cut is ≤0.3mm/m, with no burrs or collapsed corners.
Intelligent control system: Based on industrial-grade PLC, equipped with a 10–15 inch touch screen interface and over 300 built-in cutting parameter schemes. It supports importing CAD drawings to automatically generate cutting lists.
- Working principle and process breakdown
The processing procedure of the CNC steel bar shearing production line follows the closed-loop logic of "parameter preset – dynamic fixed-length – precise cutting," with each stage equipped with a sensor feedback mechanism.
Parameter setting and feeding: The operator inputs parameters such as bar diameter (e.g. φ25), shearing length (e.g. 3000mm), and cutting quantity (e.g. 500 pieces) through the touch screen. Coiled bars enter the straightening mechanism via the layout frame, while straight bars are placed on the chain conveyor. Once the photoelectric sensor detects the bar end, the feeding program is triggered.
Straightening and fixed-length feeding: The rollers straighten the bars according to preset pressure, while the servo feeding rollers drive them forward. The encoder collects real-time feed length data and sends it to the PLC. When the preset length reaches 90%, the feeding speed automatically decreases to 30% to ensure accurate positioning.
Precise shearing and quality control: After reaching the preset length, the hydraulic clamp secures the bar, and the shearing tool descends at the set speed to complete the cut. During shearing, the spray system applies coolant to reduce blade temperature.
Finished product sorting and counting: Cut sections are transferred to the finished product rack through an inclined conveyor trough.
Core Principles for Safe Operation
Pre-job preparation: The installation site must be reinforced (C30 concrete, thickness ≥150mm), grounding resistance ≤4Ω, with a 1.5m-wide safety passage around the equipment. Check that the emergency stop button is reset, protective covers are in place, hydraulic pressure is normal (10–15 MPa), and lubricating oil levels are sufficient.
Operating prohibitions: Do not cut bars exceeding the rated diameter. Do not operate the feeding system without protective gloves. Do not open the straightening cover while the equipment is running. Non-operating personnel must not approach the shearing area (safety distance ≥1m).
Special conditions: When cutting HRB500-grade bars, reduce feeding speed by 10% to ensure proper shearing. For bars longer than 6m, provide auxiliary supports to prevent flinging. In low-temperature environments, preheat the hydraulic system for 10 minutes (until oil temperature exceeds 15℃).
Emergency response: In case of jamming, press the emergency stop immediately. After the machine stops, clear the jam with special tools. If a blade breaks, stop the machine, replace the blade, and perform trial cuts (3–5 pieces) to check length accuracy.
