An Investigation into Conventional Spinning Process Using Ball Shaped Rollers as Forming Tool

The noncircular spinning is one of the recent breakthroughs of the traditional spinning processes. The spinning force is one of the important parameters for designing the spinning equipment and one of the main factors influencing the forming quality of spun parts. The variation of spinning force during noncircular spinning is considerably different from that of the conventional spinning due to the high-speed reciprocating movement of the roller induced by the variable spun workpiece profile. This paper presents an experimental investigation of spinning force characteristics of a hollow part with triangular cross sections using an octagon ring transducer based on electrical measuring method. A series of experiments using profiling driving spinning method was carried out to study the effects of the main process parameters, such as the roller feed rate, blank thickness–diameter ratio, and mandrel rotational speed, on the spinning force characteristics. The important characteristics of the force components of noncircular spinning were discussed based on the electrical measuring results. Furthermore, the variations of force components were compared with those obtained in the cases of conventional spinning and 3D non-axisymmetrical spinning. The results show that different from the conventional spinning and similar to the 3D non-axisymmetrical spinning, the three components of spinning force along the axial, radial, and tangential direction of roller vary periodically with the mandrel rotational angle. Different from the conventional and the 3D non-axisymmetrical spinning, the maximum spinning force is related to the mandrel rotational speed, even if the feed rate of roller remains constant, and increases with the increase of the mandrel rotational speed.

Bacterial poly-3-hydroxybutyrate is a thermoplastic biopolyester that is considered a potential alternative to traditional fossil-based plastics due to its rapid biodegradation performance in both soil and marine environments and its compostability. Due to problems in thermal and crystallization behaviors of the bacterial poly-3-hydroxybutyrate polymer, an improvement has been made in the cooling channel of the conventional fiber spinning process. Using an enhanced quench channel, named as a half tube on a conventional melt spinning line, melt spinning of the bacterial poly-3-hydroxybutyrate multifilament fibers is successfully carried out. The maximum crystallization temperature of polymers was taken into account while adjusting the quenching process. The study examined the impact of varying drawing ratios and the designed quenching apparatus on the thermal (differential scanning calorimetry), mechanical (tensile and drawing force tests), morphological, and crystal structure characteristics of fibers. The quenching apparatus has visibly created a homogeneous melt flow under the spinnerets. While it has a negative impact on fiber cross-sectional formation, raising the draw ratio greatly enhances mechanical properties.

Extensive studies concerning the spinning and drawing of polypropylene resulted in a method for production of high modulus fibers under industrially feasible conditions. The fibers were produced in a conventional melt spinning and drawing process that was optimized in order to increase the elastic modulus of fibers. By such optimization of the process, a tensile strength of around 8 cN/dtex, an elastic modulus up to 14.7 GPa, and a dynamic modulus up to 19 GPa were attained. In this study the mechanical properties of polypropylene fibers were investigated, which were spun from fiber grade controlled rheology (CR) polymers and from the blends of a fiber grade CR polymer with a molding grade polymer in the composition range of 10–50 wt %. The addition of the molding grade polymer to the fiber grade CR polymer resulted in lower tensile strength and moduli, with one exception. By blending a CR polymer with 10% of the molding grade polymer, maximization of the elastic and dynamic modulus was achieved. The predicted modulus of a two‐phase blend, calculated from several representative equations, was compared with the elastic modulus of drawn fibers, determined from the specific stress versus strain curve, and the dynamic modulus, obtained from the sound velocity measurements. The best fit was achieved with the Kleiner simplex equation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1–8, 2005

Finite Element Simulation of Thermomechanical Spinning Process

Circumferential cracking of conventional metal spinning process is investigated by means of finite element simulation using the Generalized Incremental Stress State dependent damage model (GISSMO). This model provides a damage scalar as an indicator to remove elements on where a crack appears. Result show that simulation predictions are in very good agreement with experiment cracking locations. A region around the cracking area deforms in the opposite direction of a roller’s stroke during cracking. This phenomenon is considered as a reason for circumferential cracking at the interaction between a plate and a tailstock. This paper shows a successful damage model to predict circumferential crack and new insights into this defect.

It is demonstrated that continuous filaments of rapidly crystallizing polymers, such as polyethylene and polypropylene, can be spun from the melt using an electric field as the only driving force. The molten polymer is fed into a metallic capillary forming a hemispherical drop at the end of the orifice. An electrical field is applied between the capillary and a conducting plate held perpendicular to the axis of the orifice. Above a critical field intensity a fine continuous jet of molten polymer is drawn; rapid crystallization ensues and a continuous fiber is formed. For fibers spun in an uncontrolled thermal environment, corresponding to ambient air temperature, and at electric field intensities of 6 and 7 kV cm−1, the properties are typically those of unoriented or slightly oriented polyolefin fibers, such as would be obtained in a conventional fiber spinning process.

The composite fibers with conductive and magnetic properties were prepared from the spinning solution consisting of poly(vinyl alcohol), poly(3,4-ethylenedioxythiophene)-poly(sodium-p-styrenesulfonate), and Co-doped Fe3O4 magnetic particles (Co-Fe3O4) via a conventional wet spinning process. The morphology, microstructure, elemental composition, crystallinity, thermal stability, mechanical properties, conductivity, and magnetic properties of the composite fibers were studied. The scanning electron microscopy images showed that the diameters of the composite fibers were in the range of 30–50 μm with a rough surface and reniform cross-section. The energy-dispersive spectra results indicated that the poly(3,4-ethylenedioxythiophene)-poly(sodium-p-styrenesulfonate) particles were mostly distributed on the surface of the composite fiber, while the Co-Fe3O4 magnetic particles mainly existed inside the fiber. The composite fibers were amorphous, but contained a certain crystalline phase, and with the increase of the poly(3,4-ethylenedioxythiophene)-poly(sodium-p-styrenesulfonate) content, the crystallinity of the composite fiber decreased. The conductivity and saturation magnetization of the composite fiber with a Co-Fe3O4 content of 2.68 wt% and poly(3,4-ethylenedioxythiophene)-poly(sodium-p-styrenesulfonate) of 8.6 wt% reached 0.2 S/cm and 1.9 A m2/kg, respectively. Besides, the composite fibers displayed improved thermal stability and good mechanical properties, which are applicable in electromagnetic protection fields.

Evolution of microstructures at a wide range of solidification cooling rate in a Ni-based superalloy

Cellular automaton modeling of dynamic recrystallization in Al-Mg alloy coating fabricated using the friction surfacing process

Wood-plastic composites have attracted extensive attention throughout the world because of their advantages. However, the manufacturing mechanism of the wood-plastic composites, i.e., high-speed milling technology, is not perfect and needs further study. The effects of the cutting parameters, i.e., the spindle speed, feed rate, axial milling depth, and radial milling depth, on the surface roughness and chip morphology were studied; the surface roughness values, Ra and Rz of high-speed milling wood-plastic composites samples were measured via high precision surface roughness measuring instrument, and their regression equations were calculated. The chips produced via a high-speed milling process were collected and studied. The results showed that the surface roughness of the wood-plastic composites increases with an increase in the axial depth, feed rate, or radial depth, but decreases with an increase in the spindle speed. In addition, the axial milling depth, feed rate, and spindle speed had a significant effect on the morphology of the chips. However, the effect of the radial milling depth on the morphology of the chips was not obvious. The results can provide a scientific basis for the optimization of high-speed milling processing of wood-plastic composites.

The simulation of the multi-pass and die-less spinning process

In the multi-pass conventional spinning process, roller paths have a significant influence on the forming quality of formed parts. The variations of the cone angle of the curvilinear generatrix part make roller path planning difficult. Current researches mainly focus on the design of the roller path profiles and its influence on the wall thickness uniformity of the parts in the one-pass spinning process. It is still difficult to realize the quantitative design of the roller path for the multi-pass spinning process. In this paper, a parametric roller path design method, which can set the mode of starting point allocation, number of passes, roller path profile, backward pass strategy, and gap between the roller and mandrel flexibly, is put forward. The influences of each factor on the forming quality of the curvilinear generatrix parts are further studied based on spinning experiments and finite simulation analysis. The results show that the parametric roller path design method proposed in this paper is an effective way to realize spinning of the curvilinear generatrix parts. Moreover, the backward pass strategy and gap between the roller and mandrel tend to cause lower reductions of wall thickness and better fittability, which can improve the forming precision of the curvilinear generatrix parts significantly.

Friction-spinning – Interesting Approach to Manufacture of Complex Sheet Metal Parts and Tubes

Inclusion compounds formed between cyclodextrins and nylon 6

Extracellular matrices are arranged with a specific geometry based on tissue type and mechanical stimulus. For blood vessels in the body, preferential alignment of fibers is in the direction of repetitive force. Electrospinning is a controllable process which can result in fiber alignment and randomization depending on the parameters utilized. In this study, arterial grafts composed of polycaprolactone (PCL), polydioxanone (PDO) and silk fibroin in blends of 100:0 and 50:50 for both PCL:silk and PDO:silk were investigated to determine if fibers could be controllably aligned using a mandrel rotational speed ranging from 500 to 8000 revolutions per minute (RPM). Results revealed that large- and small-diameter mandrels produced different degrees of fiber alignment based on a fast Fourier transform of scanning electron microscope images. Uniaxial tensile testing further demonstrated scaffold anisotropy through changes in peak stress, modulus and strain at break at mandrel rotational speeds of 500 and 8000 RPM, causing peak stress and modulus for PCL to increase 5- and 4.5-fold, respectively, as rotational speed increased. Additional mechanical testing was performed on grafts using dynamic compliance, burst strength and longitudinal strength displaying that grafts electrospun at higher rotational rates produced stiffer conduits which had lower compliance and higher burst strength compared to the lower mandrel rotational rate. Scaffold properties were found to depend on several parameters in the electrospinning process: mandrel rotational rate, polymer type, and mandrel size. Vascular scaffold design under anisotropic conditions provided interesting insights and warrants further investigation.