HG325 Tube mill line by share Roller

1. Overview

The HG325 Tube Mill Line is a high-frequency welded pipe production system engineered to manufacture steel tubes with an outer diameter up to 325 mm. The designation "by Share Roller" refers to a tooling configuration in which a single set of forming and sizing rolls is shared across a defined range of tube sizes, rather than requiring a dedicated roll set for each individual diameter. This approach is widely adopted in facilities where product diversity and tooling cost management are primary operational considerations.

Yangzhou SINOFORM Machinery Co., Ltd., established in 2010 and located in Yangzhou, Jiangsu Province, manufactures tube mill lines and rolling mill molds as core products. The HG325 line with shared roller tooling is one of the representative configurations in the product range, designed for producers requiring flexible production capability within a broad diameter spectrum.

2. Key Technical Parameters

The following table outlines the general technical scope of an HG325 tube mill line operating with a shared roller system. Actual values may vary according to specific customer requirements and raw material conditions.

3. The Share Roller Concept Explained

In a conventional tube mill line, each pipe size requires its own dedicated roller set for forming, welding squeeze, and sizing passes. As the product range expands, the required tooling inventory grows significantly, increasing both capital expenditure and storage requirements.

The Share Roller approach groups pipe sizes into defined diameter ranges. A single roller profile is engineered so that it can form and size all diameters within each group by adjusting roll gap, pass spacing, and related process parameters. This is achieved through:

• Profiled roll geometry that accommodates variations in strip width and tube diameter within the group.
• Adjustable roll stands with horizontal and vertical positioning mechanisms to adapt to different forming requirements.
• Standardized shaft and bearing dimensions across the group, so the same mechanical interface is used for all shared rolls.

It is important to note that shared rollers do not eliminate tooling changeover entirely. Operators must still reset stand positions and verify process parameters when switching between sizes within the group. The benefit is a significant reduction in the number of distinct roll sets that must be procured, maintained, and stored.

4. Dedicated Roller vs. Share Roller: Comparison

5. Main Sections of the HG325 Line

5.1 Uncoiling and Strip Feeding

A hydraulic uncoiler holds the raw steel strip coil and feeds it into the line at a controlled tension. An accumulator or looping pit may be incorporated to allow continuous production during coil changeover, minimizing downtime.

5.2 Forming Section

The flat strip passes through a series of forming roll stands that progressively bend the strip into an open tube profile. In the share roller configuration, the forming rolls in this section are designed to accommodate the full diameter group range. The number of forming passes depends on the strip thickness and the target tube diameter.

5.3 High-Frequency Welding Unit

The open tube passes through an HF induction coil or contact welding system. The strip edges are heated to welding temperature and then pressed together by squeeze rolls, forming a continuous longitudinal weld seam. The weld bead is subsequently removed by an internal and external scarfing tool to meet surface quality requirements.

5.4 Sizing and Straightening Section

After welding, the tube passes through sizing roll stands that bring the outer diameter and roundness to final dimensional tolerance. The shared sizing rolls are adjusted to match each diameter within the group. A straightening unit corrects any longitudinal bow before the tube proceeds to cutting.

5.5 Flying Saw Cutting

A flying saw or rotary cut-off machine cuts the continuous tube to the required length without stopping the mill. The cut-to-length tolerance is controlled by an encoder-based measurement and servo-driven saw carriage.

6. Application Fields

Steel tubes produced on the HG325 line with shared roller tooling are used across multiple industry sectors:

• Construction and structural engineering: hollow section columns, scaffolding, and framework tubes.
• Furniture and display systems: round and shaped tubes for frames, shelving, and fittings.
• Mechanical and agricultural equipment: conveyor rollers, machinery guard tubes, and irrigation pipes.
• Automotive and transportation: structural hollow sections used in vehicle chassis and trailer components.
• General fluid conveyance: low-pressure fluid and gas transport where HFW tube standards apply.

7. Rolling Mill Molds and Tooling Supply

SINOFORM manufactures both the tube mill line and the associated rolling mill molds in-house. This dual capability allows dimensional consistency between machine interfaces and roll profiles, which is particularly relevant in a share roller configuration where roll geometry must be precisely calculated to serve multiple diameters.

Roll materials are selected based on tube material grade, production speed, and expected campaign length. Common tooling materials include high-chromium cast iron, forged alloy steel, and carbide-tipped variants for abrasive strip materials. Replacement and spare roll sets for the HG325 share roller groups are available as part of the after-sales tooling supply.

8. Frequently Asked Questions