What the entry section includes, and the short answer
The entry section of a tube mill is the group of machines between the coil and the forming section: uncoiler (with coil car where needed) → leveling machine → shear & butt welder → flat support stand and adjustable twist stands → feeder → spiral accumulator → high turnover stand, then into the mill. It pays off and flattens the strip, joins each new coil to the previous one, and stores strip in the accumulator so the mill keeps running during coil changes.
Short answer: choose a complete entry section for a new line, or when strip width, thickness, material strength or coil weight changes so much that several existing machines no longer fit. Choose a single-machine replacement or add-on when most of the existing entry equipment still fits and only one step limits the line, provided the interfaces with the existing equipment are checked first. InGen MillTek specializes in the entry section of ERW tube mills: our uncoilers, leveling machines, shear & butt welders and spiral accumulators are built in-house and supplied as a complete section or as single machines, and we can also deliver complete HF ERW tube mill lines.
What each machine does and what decides its size
- Uncoiler: holds and expands the coil, pays off strip and applies back tension through a brake. It is selected by full coil weight and strip width. A double-head hydraulic uncoiler has two mandrels back to back and rotates 180° so that one coil runs while the next is loaded; a single-head hydraulic uncoiler with hydraulic coil car handles heavier coils; double-cone uncoilers can be supplied for wide, heavy coils. See the Uncoilers page.
- Leveling machine: flattens the strip head during threading and feeds it to the welder. The tube mill entry has its own non-driven leveling rolls, so small mills running ordinary strip usually do without a separate leveler; our engineers decide based on material strength, thickness and strip flatness. See the Leveling Machines page.
- Shear & butt welder: trims and joins the strip ends. It is offered in three grades, Integrated Shear & Manual Welder, Semi-automatic Shear & Welder and Fully Automatic Shear & Welder, chosen by strip width, thickness, material strength and joining requirements. See the Shear & Butt Welders page.
- Flat support stand, adjustable twist stands, feeder and high turnover stand: the accumulator's entry and exit equipment. They turn the strip on edge and feed it into the accumulator, then turn it back to flat for the mill.
- Spiral accumulator: InGen MillTek's flagship product, available as a horizontal spiral accumulator or a floor type spiral accumulator and configured according to strip width, thickness and line speed (catalogue range: horizontal type 2–6.5 m in diameter, floor type 4–20 m). Storage is checked by length: it must cover the mill line speed over the whole coil change and joining cycle, with a margin. See the Spiral Accumulators page.
- Hydraulics and controls: a hydraulic power unit drives mandrel expansion, the coil car, shearing and clamping; the accumulator's storage and feeding drives use variable-frequency speed control; motors and controls are built for your local supply voltage and frequency.
When a complete entry section makes sense
For a complete section, the selection logic is: strip width sets the width class of every entry machine; coil weight sets the uncoiler capacity and type; thickness and material strength decide whether a separate leveler is needed and which welder grade to use; strip width, maximum thickness and material strength set the accumulator type and diameter, and line speed and coil change time are then used to check the storage length. When thickness or strength moves up a class, the leveler and welder are sized up one class, and high-strength strip may also need a larger accumulator, depending on its strength grade; grades of 980 MPa and above are considered separately.
- A new tube mill line, or an additional line in an existing plant
- New products whose strip width, thickness, strength or coil weight exceed the capacity of several existing entry machines
- You want the uncoiler, leveler, welder and accumulator selected from one set of strip data so that no single machine becomes the bottleneck
- You want the entry-section layout and foundation drawings issued from a single source, with strip center height, line direction and control interfaces aligned
When a single machine or add-on makes sense
Single-machine replacement works when the remaining machines still match the new strip width, thickness and line speed. If changing one machine forces changes to several others, a complete entry section is usually the easier way to keep everything matched. Typical cases:
- The mill must stop for every coil change: add a spiral accumulator together with its feeder and entry and exit stands for non-stop coil change.
- Coils have become heavier or larger: replace the uncoiler, sized for the new full coil weight and coil diameters. Whether a pit can be dug in the floor affects the type of coil car.
- You are moving to thicker or high-strength strip: the welder's shear cylinder and clamps must be sized up, and a separate leveler may be needed.
- You want flatter welds and less manual work at each joint: upgrade from a manual welder to a semi-automatic or fully automatic shear & butt welder.
- Worn equipment or missing functions: existing machines can be modified component by component, with each item quoted separately.
Interfaces to check before replacing a single machine
- Strip center height and mill pass line: the height difference between the entry section and the mill is bridged by the high turnover stand, with a two-roll pinch unit added after it where needed. Send us the mill center height or pass line height first.
- Direction: feed direction (left-hand or right-hand) and operator side. The welder's direction must match the line layout.
- Upper limits of strip width, thickness, strength and coil weight: size the new machine for the upper limits of the products you plan to make, not for the nameplate of the old machine.
- Line speed: accumulator storage must cover the whole coil change and joining cycle, and the feeder must run faster than the mill so that the accumulator can refill after each joint.
- Floor space: entry-section length (uncoiler center to high turnover stand), the lateral offset caused by the accumulator, whether pits can be dug, and crane capacity.
- Hydraulics and controls: state whether the hydraulic power unit and control cabinet are included, and send your supply voltage, frequency and electrical specification.
- Actual site condition: an old drawing alone does not prove compatibility; final dimensions are confirmed against the equipment on site.
Entry-section length and layout drawings
Entry-section length is normally measured from the uncoiler center to the high turnover stand. It depends mainly on the accumulator type and diameter: a floor type accumulator usually gives a longer entry section than a horizontal one, and adding a leveling machine or using a single-head hydraulic uncoiler with coil car also adds length. InGen MillTek can prepare an entry-section layout and foundation drawing for your workshop and existing mill; final drawings are issued as agreed in the contract. For the full-line sequence and a method for estimating length, see our guide on ERW tube mill line layout.
What to send with your inquiry
Entry-section equipment is configured to order and quoted individually, with each machine listed as a separate item. For the shear & butt welder we can quote more than one grade so that you can compare.
- Project type: new complete line, complete entry section, or single-machine replacement or modification
- Finished tube sizes (outside diameter or side length × wall thickness), or strip width and thickness range
- Material grade, yield strength and tensile strength
- Coil weight, coil inside and outside diameter
- Target line speed
- Existing mill model, center height or pass line height, feed direction (left-hand or right-hand) and available floor length
- Whether pits can be dug, and crane capacity
- Supply voltage and frequency (for example 380 V/50 Hz, 415 V/50 Hz, 440 V/60 Hz, 460 V/60 Hz or 480 V/60 Hz), whether a neutral line is available, and any required electrical brands, PLC and operator-panel language
Frequently asked questions
- Q: Can I buy only a spiral accumulator? A: Yes. A stand-alone accumulator normally includes the flat support stand, adjustable twist stand, feeder, accumulator body, high turnover stand and electrical control cabinet.
- Q: Can a new entry section work with my existing tube mill? A: Yes, once the interfaces are checked. Send the mill center height or pass line height, line speed, strip width and thickness, and feed direction, and our engineers will confirm how the two connect.
- Q: Do I need a separate leveling machine? A: Not always. Small mills running ordinary strip usually do not; for high-strength or heavy-gauge strip our engineers assess the need.
- Q: Can InGen MillTek supply the complete tube mill line? A: Yes. We deliver complete HF ERW tube mill lines in a model range up to YJ-273. The standard series has six models: YJ-32, YJ-50, YJ-76, YJ-89, YJ-114 and YJ-165. The larger-diameter YJ-219, YJ-254 and YJ-273 mills are designed and built to order: our engineers design each one for the specific order. The HF welder, cold saw and similar items are configured to suit each project.
- Q: How is the price calculated? A: Complete entry sections and single machines are both configured to order and quoted individually, item by item.
About this article
YinJiang (InGen MillTek) has focused on strip processing equipment since 1997. Prepared by the InGen Engineering Team, this guide describes general configuration practice; it is not a specification or performance guarantee for any project. The final configuration is set in the agreed technical proposal and technical agreement.