60x60 ERW Square Tube Mill

The 60x60 ERW square tube mill is a specialized high-frequency Electric Resistance Welding (ERW) equipment line engineered to manufacture continuous square steel tubing with cross-sectional dimensions up to 60mm x 60mm. As a precision manufacturing solution designed and built by Yangzhou SINOFORM Machinery Co., Ltd., this machinery integrates cold-forming, high-frequency welding, sizing, and cutting processes into an automated production workflow. Equipped with dedicated roll tooling and advanced drive systems, the 60x60 square tube mill serves as a critical asset for producing structural, decorative, and industrial tubing from steel strip coils.

Working Principle and Core Components

The ERW tube mill process begins with continuous strip feeding and forming. Structural steel strip is uncoiled, leveled, and guided into the forming mill, where sequential pass rolls gradually bend the flat strip into an open round tube profile. High-frequency electrical current (typically 200–500 kHz) is then concentrated at the strip edges, heating them to forging temperature before squeeze rolls press the molten edges together to form a solid weld seam without filler metal. After internal and external weld bead removal, the tube passes through a cooling section into the sizing and squarifying mill, where Turk's head rolls precisely shape the round cross-section into a uniform 60x60mm square profile before online cutting.

Key structural components of the 60x60 ERW square tube mill line include:

• Uncoiler and Shear Welder: Provides continuous strip supply by joining the trailing and leading ends of consecutive coils.
• Accumulator: Stores strip material to permit uninterrupted mill operation during coil end joining.
• Forming and Sizing Mill Stands: Heavy-duty horizontal and vertical stands equipped with precision-machined rolling mill molds.
• High-Frequency Solid-State Welder: Delivers controlled electrical power to ensure consistent weld penetration.
• Flying Cut-off Saw: Synchronizes with line speed to cut finished tubes into exact required lengths.

Forming Process Classifications

In the production of 60x60 ERW square tubing, two primary cold-forming methodologies are utilized based on structural requirements and mill configuration:

1. Direct-to-Square Forming

In direct-to-square forming, the strip is bent directly into a square profile prior to welding. This approach reduces overall roll set tooling inventory and eliminates the need for round-to-square sizing passes. However, it requires precise edge alignment during the welding stage to maintain edge heating efficiency and square corner radii consistency.

2. Round-to-Square Forming

Round-to-square forming shapes the strip into a standard round tube first, completes the high-frequency ERW welding and seam trimming, and then deforms the circular profile into a 60x60mm square section using sizing stands and Turk's head passes. This process provides highly stable welding conditions, uniform wall thickness distribution, and tighter dimensional tolerances across corner radii.

Industrial Applications

Tubing manufactured via 60x60 ERW square tube mills meets rigorous international standards, including ASTM A500, EN 10219, and JIS G3466. Key application sectors include:

• Structural Engineering and Construction: Building frameworks, roof trusses, staging, scaffolding, and architectural support columns.
• Automotive and Transport: Commercial vehicle chassis frames, agricultural machinery structures, trailer frames, and protective guardrails.
• Industrial Equipment Manufacturing: Storage racking systems, material handling equipment frames, conveyor stands, and machinery bases.
• Furniture and Hardware: Heavy-duty commercial furniture, shelving units, outdoor enclosures, and modular steel structures.

Manufacturing Methods Comparison

To assist in operational decision-making, the table below outlines the structural and performance differences between high-frequency ERW square tube production and seamless square tube manufacturing methods for 60x60 profiles.

Quality Standards and Manufacturing Engineering

Precision manufacturing of ERW square tube equipment relies on rigorous quality management frameworks. Operating under an ISO9001 certified quality system and CE compliance standards, Yangzhou SINOFORM Machinery Co., Ltd. applies integrated scientific research, mechanical engineering, and precision tooling manufacturing to produce reliable welded pipe lines. Advanced machining equipment ensures that the forming stands and rolling mill molds meet exact geometric tolerances, minimizing profile distortion and stress concentration along tube corners.

Frequently Asked Questions (FAQ)

Q1: What wall thickness range can a standard 60x60 ERW square tube mill produce?

A standard 60x60 ERW square tube mill typically handles wall thicknesses ranging from 1.0mm to 4.5mm, depending on the yield strength of the steel strip coil and the specific motor power configuration of the forming mill stands.

Q2: What is the purpose of the weld seam heat treatment in ERW tube production?

High-frequency resistance welding creates localized thermal stress along the longitudinal joint. Online weld seam annealing restores the grain structure in the heat-affected zone (HAZ), eliminating residual stress and ensuring uniform mechanical strength across the square profile.

Q3: How are roll tooling molds maintained to prevent surface defects?

Rolling mill molds are manufactured from high-grade alloy tool steel, subjected to precision heat treatment, and inspected regularly for wear. Proper lubrication during continuous tube forming reduces surface abrasion on both the steel strip and the roll surfaces.