The aeronautics and aerospace industries often require special-shaped parts made from lightweight materials with a constant resistance, such as filament winding composite elbows and tees. Filament winding patterns can be realized using numerically controlled filament winding machines. Herein, a 3-axis computer controlled filament winding machine is proposed to solve existing problems with winding of composite elbows such as inconsistent quality, low productivity, and high costs. In this study, a geodesic winding equation for the torus and non-geodesic winding equation for the cylindrical sections of the elbow are provided and the winding angle α’ is optimized. Furthermore, the correspondence relationship between the cylindrical and torus section motion is derived. The winding pattern is optimized and tested using the proposed 3-axis filament-winding machine. The results show that the optimal winding pattern design can be easily calculated with a programmable multi-axis controller using a simple control program, and a consistent winding pattern can be achieved. This paper provides a low-cost manufacturing method for the filament winding of composite elbows with cylindrical ends of unequal lengths.
Composite materials are increasingly used for aircraft construction in the aviation industry due to their high performance-to-weight ratios, low thermal conductivity, good corrosion resistance, good chemical/physical stability, vibration reduction and anti-magnetic characteristics, as well many other excellent properties [
Several companies offer commercial filament winding computer-aided design (CAD) software including FiberGrafiX™ (ENTEC Composite Machines, USA), CADFIL™ (Crescent Consultants, UK), CADWIND™ (MATERIAL SA, Belgium), and ComposicaD™. According to ENTEC, its FiberGrafiX™ software is used in more filament winding machines around the world than any other similar application. Fiber paths can be created in the software and used to wind parts for machines with two to six axes of motion. Crescent Consultants offers CADFIL as both a standard or customized software package for use with any numerically controlled winding machine. CADFIL-Lite has many of the same features as the more powerful CADFIL-Axsym package but with quick and simple parametric programming for common filament winding geometries. The CADWIND software from MATERIAL SA can calculate winding patterns for any mandrel geometry and automatically generate a program to produce the part on any winding machine [
Although the four commercial software mentioned above can be used to design and produce asymmetric winding components such as elbows and tees, a computer numerical control (CNC) winding machine with a minimum of four axesis required for combined-elbow winding and the software is expensive. Han et al. [
The commercial software and investigations mentioned above are suitable for winding of elbows when the length
The composite elbow is an asymmetric rotating body with a relatively complex structure that can be divided into three parts, as shown in
A schematic diagram of the composite elbow winding machine is presented in
Traditional composite elbow winding mandrels usually have cylindrical sections (AB and CD) of equal length on both ends. The length of the cylindrical sections should not be too long, so that the elbow mandrel can rotate about its centerline at both ends, controlled by either a 4-or 5-axis computer-controlled winding machine. However, the 3-axis composite elbow winding machine does not have any cylindrical length requirements on either end of the elbow mandrel and the winding process can be completed by a 3-axis CNC winding machine, which reduces the cost and is more efficient. In this kind of winding machine, when swing radius R of the torus changes, the distance between the carriage assembly and the bed can be adjusted by the screw adjustment mechanism to ensure the geometric center O’ of the composite elbow coincides with the rotation center of the carriage assembly. The elbow mandrel is arranged vertically to ensure the carriage assembly rotates on the horizontal plane. This makes it easy to place the winding fiber tows and deal with problems in the winding process, however, it is also easy to collect excess resin during the winding process. Therefore, a counterweight weight must be added to counteract the weight of the elbow mandrel, which presents a disadvantage.
Generally, the elbow can be regarded as a part of the torus. In elbow section BC, shown in
where
Considering a microelement on the torus of the elbow section, as shown in
where
According to differential geometry [
When
From
Then, integrating
If we set the ratio of bending radius and elbow radius as
From
For special curved surfaces, like the torus, not all geodesic winding can cover the entire surface. To avoid bridging and slippage, the initial winding angle
Substituting
From
n | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
---|---|---|---|---|---|---|---|---|---|
45.0 | 35.3 | 30.0 | 26.6 | 24.1 | 22.2 | 20.7 | 19.5 | 18.4 |
According to
In the composite elbow winding machine shown in
In the winding process of the torus section, the geometric relationship between the rotation angle
As shown in
where Δ
From
For the elbow shown in
From the differential terms
The optimized winding angle
The optimized winding angle
The helical section lengths of cylindrical sections AB and CD, denoted
From
The rotation angles of the winding eye in the helical sections of cylindrical sections AB and CD are denoted
The total rotation angle
For asymmetric complex parts such as composite elbows, use of the multiple tangent point method for filament winding will lead to fiber bridging on both dome ends. Therefore, the single tangent winding method is usually adopted. If the initial winding angle
The composite elbow is an asymmetric component and the winding angle is a function of the rotation angle of the winding eye. Among the latitude lines corresponding to the surface of the torus,
The projection of a fiber band of width
To obtain a fiber band offset, the rotation angle increment
With continuous advances in materials science, computer technology, modern control technology, artificial intelligence, and other related technologies, the traditional manufacturing industry is constantly evolving towards intelligent manufacturing. In recent years, due to continuous progress and improvements in motion control technology, motion control systems have become a mature technology and occupy an important position in the automation industry as independent industrial automation control products. Applications include decision-making in production processes, integrated manufacturing, friendly human-machine, and energy-saving and environmentally friendly processing. Indeed, intelligent manufacturing has become an important trend in factory automation, in which motion control technology also plays a major role, and will beat the core of advanced intelligent manufacturing in the future [
The filament winding machine proposed in this paper is a low-cost system with only three motion control axes, including swing motion of the elbow mandrel, linear motion of the elbow mandrel, and rotation of the mandrel. Three Panasonic servo motors of the A5 series ere used to produce the swing and linear movements of the elbow mandrel and rotation of the winding eye. To control the 3-axis motion of the machinein space, a PMAC-PC104 motion control card (fifth-generation, Delta Tau, USA) was selected. The motion control card uses advanced digital signal processing (DSP) technology, including Motorola 56K series, which is the most powerful motion controller in the world and an outstanding representation of current open CNC system controllers. The fast and accurate calculation ability is transformed into high-precision and fast motion trajectory calculation and control, which can be transformed into precise multi-axis motion trajectories via simple motion programs. The high performance, flexibility, ease of use, and low cost of the controller provide a complete technical solution for realizing the winding patterns of elbows. Once the 3-axis coordinate information is defined, the absolute coordinate mode or relative coordinate mode can be selected. In this study, the relative coordinate mode was used. To cover the surface of the composite elbow,
No. | Elbow mandrel (increment) | Winding eye (increment) |
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1 | 0 | |
2 | ||
3 | ||
4 | ||
5 | ||
6 | ||
7 | ||
8 | ||
9 | ||
10 | − |
|
11 | ||
12 |
Based on the previous winding motion trajectory analysis, Advantech’s industrial control computer, PMAC motion control card and VC++ language were used to design a CAM system for composite elbow filament winding. The control system only requires knowing the length of cylindrical sections AB and CD, ratio
Take the winding process of the composite elbow as an example, the length of cylindrical sections AB and CD were 400 mm and 150 mm, respectively, the ratio
Fiber winding trajectory equations for the cylindrical sections and torus section of the elbow based on non-geodesic and geodesic winding, respectively, were introduced. In addition, boundary conditions of the initial winding angle without bridging or slippage were proposed. The optimal winding angle The motion program was written onto a PMAC-PC104 motion control card and tested on a 3-axis computer-controlled filament winding machine. The results show that the winding pattern is uniform and the motion control process is stable. This not only verifies the correctness of the theory presented in this paper but also shows that the 3-axis computer controlled winding machine can be used for winding of composite elbows. Moreover, the method can be used for winding composite elbows with cylindrical ends of unequal lengths and provides a low-cost approach to composite elbow winding.
The authors gratefully acknowledge financial support from the Basic Scientific Research Project (2572020DF01) of Northeast Forestry University and the Fundamental Research Funds for Higher Education Institutions of Heilongjiang Province (grant numbers 135309513 and 135309109).