Prepreg Pultrusion Process and Application

 

 

Pultrusion Process of Resin-Based Fiber-Reinforced Composite Materials Traditional Pultrusion Process

 

The dry fiber is impregnated with resin and then heated and solidified in a mold.

 

The production process is automated, suitable for the production of various slender rods, and products with a length almost limited by the hand guard can be pulled out.

 

The axial fibers along the pultrusion direction are mainly used, and the typical products are various rods.

 

The complex thin-walled profiles increase the cross-section crack resistance by adding surface felt between the fibers, and the typical products are various types of profiles

 

 

 

 

Prepreg (Advanced Pulltrusion) Pultrusion Process

• Using unidirectional prepreg, the layers are laid out according to the mechanical design, and a series of deformation, heating, and curing are used to form aviation-grade profiles.
• Short mold molding can produce slender components with almost unlimited length.
• Tankless and short mold production saves a lot of equipment costs.
• The mold is directly heated, with high heating efficiency and energy saving.
• Currently, only fixed-section components can be produced, but variable thickness components can be produced by adding sacrificial layers.

 

 

 

 

 

 

Characteristics of Prepreg Pultrusion Manufacturing Technology Characteristics of Prepreg Pultrusion Manufacturing Technology:

 

Prepreg pultrusion can be understood as a step-by-step continuous molding. For unidirectional thermosetting prepreg, as the temperature increases during the heating process, the resin viscosity decreases, and the fiber will slip under the pressure, which is prone to fiber deformation and collapse.

 

The pressurization at this stage requires extreme caution, both to ensure that the resin flows fully and the bubbles during the prepreg laying are fully overflowed, and to control the fiber to stay in place as much as possible. Generally speaking, the 0° fiber along the traction direction is not a serious problem due to the existence of traction tension, but the 90° and ±45° fibers are very likely to have the above-mentioned situation at this stage

 

 

▶There should be at least one layer of prepreg in the 0° direction in the layer design.

▶For components with larger cross-sectional thickness and size, there are certain requirements for prepreg exhaust.

 

Prepreg Pultrusion Molding Process and application Application of prepreg (advanced) pultrusion technology in typical structural parts

 

 

Laying Realization: Strip-shaped special tape laying + continuous stacking into blanks

 

 

How the Tape Laying Machine Lays

 

 

Preform Continuous Deformation Analysis: Configuration of Preform Die

 

 

The prepreg is deformed from a flat plate into a target shape. During the deformation process, the length of the horizontal line is required to remain unchanged, and the contour gradually changes along the longitudinal direction. The rate of change needs to match the slip rate between the prepreg layers to prevent wrinkles. By making the mold base too high, the mold presents a turtleback shape to make the prepreg fit.

 

 

The prepreg is deformed from a flat plate into a target shape. When no constraints are applied, large deviations will occur in the lateral and longitudinal directions, causing stacking and wrinkling defects in the prepreg. At the same time, the presence of tension will cause the prepreg to be suspended.

 

Preform Continuous Deformation Analysis: Reconstruction of Preform Mold

 

 

 

Hat-Shaped Advanced Pultrusion Hot Pressing System:

 

 

 

 

 

 

 

 

 

C-Beam Pre-Deformation Analysis

 

 

 

 

Assembly and Pultrusion Curing of I-Beams:

 

 

 

 

 

 

Aerospace Pod Rod Pultrusion Technology

 

 

 

 

Preliminary Study on Thermoplastic Prepreg Pultrusion Technology

 

Technical Difficulties

• Unlike thermosetting prepreg pultrusion, thermoplastic prepreg is in a softened state during the molding process. Therefore, choosing the appropriate pressurization temperature is the key to affecting the molding quality.
• During the pulsating traction process, the prepreg should be in a hardened state, so the molded part should be cooled before traction, so the mold should have fast heating and cooling functions.
• Repeated alternation of hot and cold will cause high internal stress in the part, so the heating and cooling scheme needs to consider the deformation and stress of the part.

 

 

 

Thermoplastic Prepreg is Ultrasonically Welded into a Preform

The preforming module shapes the preform to facilitate entry into the hot press curing module

The prepreg layers are fused through temperature and pressure

The cooling module passes cooling water into the mold to shape the prepreg

The traction module is responsible for providing traction for pulsating pultrusion

The deviation correction module corrects the lateral displacement of the prepreg

 

 

 

Summary and Outlook

Prepreg pultrusion technology has a high processing advantage for structural parts such as slender trusses. The use of short mold technology has technical characteristics such as low equipment investment and energy saving. It is one of the low-cost manufacturing methods for composite components.

 

Prepreg pultrusion technology can easily control the thermal experience of the blank, interrupt heating immediately, and form intermediate products with different curing degrees, such as the “C-beam” in this report.

 

The non-autoclave curing process can continuously heat the prepreg molded workpiece through the self-heating mold to complete the curing, which can save a lot of energy and reduce production costs.

 

General and Professional Manufacturing Equipment:

The composite manufacturing process has evolved from manual laying in the early stage of development to the introduction of more and more automated equipment, forming a more automated production process. In the early stage of development, equipment used general equipment (such as general tape laying and wire laying equipment) when the target product was uncertain or the product scale was small and the processing target was uncertain. However, with the clarification of product goals and the expansion of production demand, equipment that is targeted at specific product processes as much as possible will bring higher manufacturing efficiency and lower manufacturing costs.

 

Accurately Implement the Process Through Equipment:

Professionals engaged in process technology research analyze and test the process and obtain accurate process control parameters, and propose process control goals from the product side. Equipment manufacturers analyze from the equipment implementation side, determine the implementation path, and reach a more reliable and accurate implementation of the process through systematic analysis with process personnel. Putting the process into the equipment has always been one of the signs of the development of the manufacturing industry.

 

Manufacturing Process Automation:

Use automatic machines as much as possible to replace manual methods. In modern manufacturing, the operating level, skills and emotions of on-site personnel are factors that affect product quality, especially simple and repetitive production links, which require on-site process personnel and production management personnel to discover and raise problems. Demand is the top priority.