I. Introduction

Film winding equipment has evolved through mechanical, CNC, microcomputer-controlled, and robotic winding. Current research on winding equipment focuses on multi-degree-of-freedom, multi-station, continuous winding, winding of complex and irregularly shaped parts, robotic winding, high-speed and high-precision winding, multi-process integration, and clean manufacturing. Auxiliary equipment in the winding process, such as rapid resin impregnation devices, multi-wire nozzles and modular guides, high-precision tension controllers, and internal heating and curing molds, has also been continuously improved.

II. Research Progress on Winding Processes

1. Winding Processes

Study on the effects of factors such as winding tension system, fiber volume content, fiber stacking, fiber overhead and cross-over, winding line shape, pattern distribution, and winding speed on the stress, strain, and stiffness properties of the molded product.

Winding line

Fiber overhead

Fiber accumulation

Tangent point distribution

2. Winding of Special-Shaped Parts

Twisting theory is now quite advanced, and winding software has been developed that can plan winding trajectories for various typical special-shaped parts. Currently, the main focus is on winding commonly used T-shaped pipes, elbows, and special-shaped rotating structures.

Ring pressure vessel

T-tube winding

Special-shaped parts winding

elbow winding

Concave cylindrical shell winding

3. Process Combination - Pultrusion/Filming/Weaving

▶ A combination of filament winding and pultrusion, referred to as pultrusion. Its working principle is to first pull to form a unidirectional inner layer; then circumferential winding to increase radial strength; and finally unidirectional pultrusion to form a smoother outer wall.

The pultrusion process offers the following advantages:

▶ Continuous production is possible;

▶ Both internal and external surfaces are smooth, eliminating the need for turning or grinding, reducing material consumption, labor intensity, and environmental pollution;

▶ The pultrusion process ensures orderly fiber arrangement, maximizing the performance of the reinforcing fibers and ensuring product stability;

▶ The FRP membrane shells produced by the pultrusion process have excellent wall thickness uniformity, with an average deviation of no more than 0.1mm, ensuring the dimensional accuracy of porous FRP membrane shells.

Principle of winding process

Pull-wound membrane shell

4. CAD/CAM

▶International research in filament winding CAD/CAM software has reached a high level.

This CAD/CAM software not only offers comprehensive capabilities for designing filament

winding profiles and trajectories for rotating objects, but also for designing filament winding

trajectories for special-shaped parts. For typical special-shaped parts like tees and elbows

, comprehensive CAD/CAM software has been developed to handle core mold design,

profile design, trajectory planning, and post-processing. It can also generate control codes

tailored to specific CNC systems. Examples include CADWIND from MATERIAL (Belgium)

, CADFIL from Crescent Consultants Ltd (UK), and SimWind from McClean Anderson (US.

s CAD/CAM software not only offers comprehensive capabilities for designing filament

winding profiles and trajectories for rotating objects, but also for designing filament

winding trajectories for special-shaped parts. For typical special-shaped parts like tees

and elbows, comprehensive CAD/CAM software has been developed to handle core

mold design, profile design, trajectory planning, and post-processing. It can also generate

control codes tailored to specific CNC systems. Examples include CADWIND from

MATERIAL (Belgium), CADFIL from Crescent Consultants Ltd (UK), and SimWind from

McClean Anderson (USA).

CADWIND winding software interface

CADFIL Winding Software Interface

5. Tape Winding - Pipe Fittings and Pressure Vessels

▶ Thermoplastic fiber tape winding has been a hot topic in recent years. Tape winding

offers improved designability, enhanced fiber-resin bonding, and superior molding

efficiency. Combined with laser- or infrared-assisted in-line curing processes, it enables

high-quality and efficient industrial mass production. Products are environmentally friendly,

fatigue-resistant, and impact-resistant. Pipe fittings, pressure vessels, and custom-shaped

parts manufactured using this process overcome the limitations of fiber yarn winding and

thermosetting resin systems, offering broad application prospects.

With winding pipe fittings

Wrapped pressure vessel

6. Filament-Wound Special-Shaped Connectors

▶ For filament-wound structural components and connectors, we utilize advanced winding

trajectory design methods, improved processes, and materials to significantly reduce weight

and increase structural strength. Typical applications include filament-wound structural

connectors, transmission components, and integral frame components.

▶ Core technologies include coreless winding and fixed-track winding to achieve weight

reduction and special-shaped winding.

Filament winding connection and transmission parts

Filament-wound monolithic frame (for construction)

7. Efficient Winding of Pressure Vessels

▶ RWTH Aachen University in Germany has developed a multi-filament wound pressure

vessel (MFV) capable of withstanding pressures up to 700 bar. This vessel can simultaneously

wind up to 180 strands of roving, winding one fiber layer at a time. Currently, this product

is used in automotive fuel cylinders.

▶ Molding efficiency is 50 times that of traditional wet winding;

▶ The filaments are crimp-free, significantly improving the mechanical properties of the

product;

▶ Efficiency advantages are achieved for molding large products.

Multi-strand filament wound pressure vessel

8. New Wrapped Products

The application areas of wrapping processes and products are constantly expanding, such

as:

▶ Plant fiber/tape wrapped composite materials offer advantages such as high specific

strength, lightweight, environmental friendliness, and low cost;

▶ Fiber-wrapped bicycle rims offer advantages such as improved production uniformity,

enhanced performance, and greater durability.

Bamboo strips and bamboo fiber wrapped composite pipes

Carbon fiber wrapped bicycle rims

9. Electromagnetic Induction Heating of Carbon Fiber

Corebon, Sweden, has developed a process for directly heating carbon fiber materials

using electromagnetic induction, along with a temperature data simulation platform. This

technology is applicable to a variety of processes, including resin transfer, molding,

curing ovens, pultrusion, and winding.

▶ It can reduce heating time by up to 10 times;

▶ It can directly heat the product, or use carbon fiber materials as molds;

▶ It is energy-efficient;

▶ It can display 3D temperature data;

▶ It provides a new method for rapid in-line curing of CFRP materials.

Electromagnetic induction direct heating of carbon fiber

III. Research Progress in Filament Winding Equipment

1. Multi-Degrees of Freedom/Multi-Station

After half a century of development, my country's filament winding technology has reached

a mature stage. Filament winding equipment has essentially achieved full microcomputer

servo control. The manufacturing technology and winding processes for two-, three-, and

four-axis microcomputer-controlled filament winding machines are mature and have played

an important role in the winding of pipelines, storage tanks, various pressure vessels,

electrical insulation products, and sports and leisure products. Six-axis microcomputer-controlled

filament winding machines are already used in the development and production of composite

materials.

Multi-spindle winding machine

Four-axis winding machine

Five-axis controlled four-axis linkage winding machine

Six-axis winding machine

2. Continuous Winding - Thermoset Fiber-Reinforced Pipes

The core technology behind the continuous winding process for thermoset fiber-reinforced pipes

is the use of a cam plate to continuously rotate a steel belt to form an inner core mold for

pipe winding. The steel belt circulates back and forth, continuously completing the glass

fiber winding, lamination, sanding, and curing processes on the moving inner core mold.

▶Internationally, several companies in Europe and the United States have independently

developed continuous winding lines for FRP pipes that feature high automation, low labor

intensity, a wide range of specifications, and low energy consumption.

▶In China, companies such as Qingdao Langtong Machinery Co., Ltd. and Lianyungang

Weide Composite Materials Equipment Co., Ltd. have independently developed equipment

and production technology for continuous winding lines for sand-filled FRP pipes.

Continuous winding production line and pipe products

3. Continuous Winding - Thermoplastic Fiber-Reinforced Pipes

Fiber-reinforced thermoplastic pipes are composed of multiple layers, with the middle layer

serving as the fiber reinforcement.

▶Internationally, companies such as Ridyway Machines Ltd. (UK) offer continuous

fiber-reinforced thermoplastic production lines. Companies such as Flexpipe Systems

(Canada), TherCoil (US), Airborne (Netherlands), DeepFlex (US), Magma Global (UK),

and Composite Fluid Transfer (CFT) (US) all utilize continuous winding technology and

production lines to produce and apply continuous fiber-reinforced thermoplastic pipes.

▶In China, companies such as Nanjing Chenguang Oupa Composite Pipe Engineering

Co., Ltd., Guangzhou Lijin, and Shanghai Jinwei are conducting related technology

research and development and production line development.

Fiber reinforced thermoplastic pipe production line and products

4. Robotic Winding

Research on winding robots started relatively early and has matured abroad. MFTech, a

French company, pioneered the research and commercialization of robotic winding. The

company's robotic winding equipment leverages the flexibility of the robot to perform

composite winding molding using both mold gripping and wire guides.

MF Tech Pitbull

MF Tech FOX System

Multi-station container wrapping

Compositum, a Canadian company, has developed a fully automatic winding system compatible with robots and CNC systems from various brands, including ABB and KUKA. Taniq, a Dutch company, has developed the Scorpo robot, equipped with proprietary process design software, for winding fibers and rubber belts for fiber-reinforced rubber products.

Composite container products made by Compositum's robotic wrapping machine

Taniq's Scorpo robot

5. Automated 3D Winding Machine

Cygnet Texkimp and the University of Manchester have jointly developed a groundbreaking

nine-axis 3D winding technology for lightweight automotive and aircraft components. This

first 3D winding machine is capable of automatically winding complex components with

curved centerlines, such as fuel lines, inclined rails, and aircraft wing spars.

Cygnet Texkimp 3D wrapping technology

6. Tension Control System

During the winding process, winding tension is closely related to the strength and fatigue

resistance of the product, significantly impacting its performance. Therefore, the tension

controller is the most important auxiliary equipment for winding molding.

▶Internationally, companies such as INFRANOR, Entec, Warner Electric, and Dover

Flexo Electronics (DFE) in the United States, ABB in Switzerland, and Pultrex in the

United Kingdom are all dedicated to the research and continuous innovation of tension

control systems, currently achieving the highest accuracy within 2%.

▶In China, Harbin Composite Materials Equipment Company, Harbin Institute of

Technology, and Harbin University of Science and Technology have developed precision

tension control systems. Tianjin Nuclear Power Plant No. 3, Wuhan University of

Technology, and the 703rd Research Institute of the First Academy of Aerospace Science

and Technology are jointly developing a high-tension winding system for carbon fibers.

Tension control system

7. Prepreg/Fiber Winding Systems

To improve production efficiency and product quality, both domestic and international

research is underway on prepreg/filament winding systems, yarn guides, in-situ heating

and curing systems, and high-precision resin dipping tanks.

Prepreg winding system

Yarn ring guide

Internally heated HPTE core and induction coil

High-precision dipping tank

8. Fully Automated Winding Production Line

Composite pipes and containers, the most widely used products, have now been manufactured

on a large-scale automated, integrated production line, significantly improving production

efficiency and product quality.

Fully automatic gas cylinder winding production line

IV. Development Trends in Winding

1. Demand and Overall Goals

2. Development Focus

3. Key technologies and equipment

V. Molding process and equipment developed by the research team 1. Research on key technologies of new structure and molding process of dry fiber wound pressure vessel The dry fiber winding mode has important scientific significance and application value in significantly improving the impact resistance of fiber reinforced pressure vessels. It is the first in China to apply the resin-free dry fiber winding process to the molding of composite gas cylinders and new rubber composite products, solving the problems of poor impact resistance, difficult recycling and low production efficiency of traditional composite materials. (1) Develop and promote the use of dry fiber wound LPG gas cylinders to promote my country's traditional products such as gas tanks and fire extinguishers from metal-based materials to the era of lightweight, long-life and high-safety composite materials. (2) Develop and promote the application of high-performance upgraded rubber products such as dry fiber continuous winding reinforced rubber airbags, dredging pipes, high-speed rail and automobile gas springs, and military rubber lifters.

Dry fiber wound LPG cylinders

Dry Filament Winding Jacks

Dry fiber wound rubber tube and airbag

2. Research on Key Technologies for Manufacturing Bamboo-Based Multi-Dimensional

Special-Shaped Composite Materials

This research is a pioneering effort internationally to develop molding processes and

equipment for bamboo fiber-reinforced special-shaped composites, establishing

specifications, methods, and standards for the production, testing, performance

characterization, and application evaluation of green and environmentally friendly

bio-based composite materials. This research will promote the restructuring and

transformation and upgrading of the bamboo fiber composites industry, enabling

the expanded application of bamboo fiber composites in water conservancy pipelines,

automotive interior linings, and construction engineering. Furthermore, the research

and development of innovative fiber-reinforced green composite products will be

pursued, leading to their industrialization and application.

Plant fiber-based composite square tubes and round tubes

Hemp fiber wrapped elbows and tees

Hemp fiber wound hose

3. Robotic-Based Filament Winding Process and Equipment

This robotic-based filament winding process and equipment addresses a range of core

engineering challenges in wound composite products, from molding theory and process

design optimization to the development of efficient molding equipment.

Based on flexible industrial robots, modular end-of-line winding mechanisms, precision

tension control, and efficient molds, this system encompasses the entire composite

winding, curing, and post-processing process. This modularized, fully automated

production line is achieved through the use of robotic molding workstations.

Network-based Robotic Winding Workstation Solution

4. Composite Material Rapid Molding Process and Fully Automated Production Line

The composite lithium battery case cover and tray developed in this project are 20%

lighter than aluminum alloys, while maintaining comparable cost. This enables the rapid

production of composite battery cases, with a cycle time of less than 10 minutes and an

annual output of over 20,000 units.

5. Composite Material Processing Technology and Machining Equipment Development

To overcome the bottleneck in efficient and low-loss processing of fiber-reinforced composites,

we developed specialized composite machining tools. We analyzed the impact of composite

structure on machining, considered the influence of tools and machining techniques on the

processing of composite products, improved and optimized existing machining processes, and established technical specifications for automated composite manufacturing. We leveraged specialized composite machining tools and processes to achieve breakthroughs in key CNC machining technologies for composite materials.

Composite material internal cutting drill bit

Composite material milling and drilling robots

6. Special winding process and products

(1) A winding strategy with cross-rotation axis transformation was used to solve the problem

of uneven ball winding thickness, and a carbon fiber winding reinforced ceramic ball was

developed.

(2) In collaboration with Hefei University of Technology, a carbon fiber composite annular

fuel tank and a carbon fiber high-tension winding flywheel were developed.

(3) A carbon fiber lattice shell structure antenna cover sample was developed and the

mechanical properties analysis in the service environment was carried out.

Carbon fiber wound reinforced ceramic balls

Composite annular gas cylinder

Carbon fiber radome

Carbon fiber high tension winding flywheel

Carbon fiber drive shaft

7. High-pressure pipe winding machine and production line

(1) The high-pressure pipe winding control system developed by us has a domestic market

share of 80% and is used in more than 30 large composite material manufacturing companies,

including state-owned enterprises and listed companies.

(2) We promoted the listing of Daqing Hanwei Changyuan High-pressure FRP Pipeline Co.,

Ltd. and Suzhou Jiumei FRP Co., Ltd. in Canada and on the National Equities Exchange

and Quotations (NEEQ).

(3) The produced pipelines are used in major projects such as the West-East Gas Pipeline,

the 982 offshore oil platform, and polar icebreakers.

Typical users of winding machines and production lines

(4) Developed the world's first fully automatic FRP pipe production line integrating winding,

curing, demoulding, grinding, cutting and conveying processes for Future Pipe Industries

of the Netherlands (the world's second largest composite pipe manufacturer with an annual

output value of over US$1 billion).

(5) The fully automatic high-pressure FRP pipe production line developed was exported to

the United States, Russia and other countries, realizing the export of domestic high-pressure

FRP pipe manufacturing equipment.

Fully automatic high-pressure FRP pipe production line

8. Electromagnetic Heating Superconducting Molds and Robotic Winding Workstations

(1) Innovatively combining electromagnetic induction heating and heat pipe superconducting

heat transfer technology. Developed the first set of electromagnetic heating superconducting

molds with a length of up to 7 meters, which are used for curing and molding products such

as pipes, drive shafts, and insulators.

(2) Developed the first domestic fiber winding workstation based on a six-degree-of-freedom

robot, suitable for wet, dry, tape winding, and dry fiber winding processes, a modular winding

head, and a high-precision fiber tension control system.

9. Other composite material forming equipment and production lines

(1) Developed a four-degree-of-freedom bending special winding machine based on a fixed

bending mold and a rotating wire guide head for winding.

(2) Developed a robot-based composite material cutting, grinding, and polishing workstation.

(3) Developed a carbon fiber heating mural gluing and bonding production line to achieve fully

automatic production of laying base cloth → laying reflective film → laying heating plate →

laying mural → cutting → finished product.

(4) Developed a carbon fiber geothermal module production line to achieve automatic production

and automated handling of carbon fiber geothermal modules: loading → wrapping reflective film

→ pasting aluminum film → turning rock wool board → laying heating plate → pasting aluminum film

→ unloading.