Multi stages toolpath optimisation of single point incremental forming process

Single point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. Mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two have significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy had successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively

Part accuracy improvement in two point incremental forming with a partial die using a model predictive control algorithm

As a flexible forming technology, Incremental Sheet Forming (ISF) is a promising alternative to traditional sheet forming processes in small-batch or customised production but suffers from low part accuracy in terms of its application in the industry. The ISF toolpath has direct influences on the geometric accuracy of the formed part since the part is formed by a simple tool following the toolpath. Based on the basic structure of a simple Model Predictive Control (MPC) algorithm designed for Single Point Incremental Forming (SPIF) in our previous work Lu et al. (2015) [1] that only dealt with the toolpath correction in the vertical direction, an enhanced MPC algorithm has been developed specially for Two Point Incremental Forming (TPIF) with a partial die in this work. The enhanced control algorithm is able to correct the toolpath in both the vertical and horizontal directions. In the newly-added horizontal control module, intensive profile points in the evenly distributed radial directions of the horizontal section were used to estimate the horizontal error distribution along the horizontal sectional profile during the forming process. The toolpath correction was performed through properly adjusting the toolpath in two directions based on the optimised toolpath parameters at each step. A case study for forming a non-axisymmetric shape was conducted to experimentally validate the developed toolpath correction strategy. Experiment results indicate that the two-directional toolpath correction approach contributes to part accuracy improvement in TPIF compared with the typical TPIF process that is without toolpath correction

Tool path generation for single point incremental forming using intelligent sequencing and multi-step mesh morphing techniques

A new methodology of generating optimized tool paths for incremental sheet forming is proposed in this work. The objective is to make parts with improved accuracy. To enable this, a systematic, automated technique of creating intermediate shapes using a morph mapping strategy is developed. This strategy is based on starting with a shape different from the final shape, available as a triangulated STL model, and using step-wise incremental deformation to the original mesh to arrive at the final part shape. Further, optimized tool path generation requires intelligent sequencing of partial tool paths that may be applied specifically to certain features on the part. The sequencing procedure is discussed next and case studies showing the application of the integrated technique are illustrated. The accuracy of the formed parts significantly improves using this integrated technique. The maximum deviations are brought down to less than 1 mm, while average absolute deviations of less than 0.5 mm are recorded

Процес отримання напівсферичного виробу інкрементним формуванням

Метою роботи є дослідження та моделювання процесу інкремннтного штампування напівсферичної деталі за допомогою методу скінчених елементів (МСЕ), дослідження енергосилових параметрів процесу та напружено-деформованого стану матеріалу, а також проведення моделювання інкрементного штампування напівсферичної деталі в Abaqus. В дисертаційній роботі проведено аналіз сучасного стану досліджень по технології виготовлення деталей інкрементним формуванням, наведено їх переваги та недоліки, на основі чого сформульовані задачі досліджень. За допомогою методу скінченних елементів проведено моделювання штампування напівсферичної деталі класичним способом витягування в програмі DEFORM. Визначено силові режими деформування. Встановлений напружено-деформований стан викову в кінці деформування. Показано розподіл температур по об’єму здеформованих деталей та розподіл критерію руйнування. За допомогою методу скінченних елементів проведено моделювання отримання напівсферичної деталі методом інкрементного штампування в програмі Abaqus. Розроблене штампове оснащення для отримання напівсферичної деталі.The purpose of the work is research and modeling of the process of incremental stamping of a hemispherical part using the finite element method (FEM), research of energy parameters of the process and the stress-strain state of the material, as well as modeling of incremental stamping of a hemispherical part in Abaqus. In the dissertation, an analysis of the current state of research on the technology of manufacturing parts by incremental forming is carried out, their advantages and disadvantages are given, on the basis of which research tasks are formulated. With the help of the finite element method, the simulation of the stamping of a hemispherical part by the classical method of extraction in the DEFORM program was carried out. Force modes of deformation are determined. The stress-strained state of the forging at the end of the deformation is established. The distribution of temperatures over the volume of deformed parts and the distribution of the failure criterion are shown. With the help of the finite element method, the simulation of obtaining a emispherical part by the method of incremental stamping was carried out in the Abaqus program. Developed stamping equipment for obtaining a hemispherical part

Single point incremental forming: An assessment of the progress and technology trends from 2005 to 2015

The last decade has seen considerable interest in flexible forming processes. Among the upcoming flexible forming techniques, one that has captured a lot of interest is single point incremental forming (SPIF), where a flat sheet is incrementally deformed into a desired shape by the action of a tool that follows a defined toolpath conforming to the final part geometry. Research on SPIF in the last ten years has focused on defining the limits of this process, understanding the deformation mechanics and material behaviour and extending the process limits using various strategies. This paper captures the developments that have taken place over the last decade in academia and industry to highlight the current state of the art in this field. The use of different hardware platforms, forming mechanics, failure mechanism, estimation of forces, use of toolpath and tooling strategies, development of process planning tools, simulation of the process, aspects of sustainable manufacture and current and future applications are individually tracked to outline the current state of this process and provide a roadmap for future work on this process

Incremental Forming of Polymers at Room Temperature

Single Point Incremental Forming (SPIF) is a forming process in which a fully clamped sheet is formed by a hemispherical ended tool that moves along a predefined 3D toolpath. The sheet is formed in a series of local deformations to reach its desired shape. Double Sided Incremental Forming (DSIF) includes one tool on each side of the sheet so that the second tool can take the role of the local die or the forming tool to improve the part shape geometry and forming parts with higher geometric complexity. Significant advantages of incremental forming process include, (i) low tooling cost due to easy fabrication and geometry independence of the tools, (ii) absence of the heating energy cost due to room temperature nature of the process, and (iii) its capability of forming complex parts which make it suitable for low volume forming of the polymer sheets as well as prototype fabrication. This work investigates the effects of SPIF process parameters on formability and failure mode in polymer, metal-polymer laminates, mechanical and microstructural properties, and chain orientation of the formed polymers. Capability of DSIF process in forming polymers is also shown and discussed. Investigation on the effect of SPIF process parameters on formability and mode of failure shows that increasing incremental depth increases formability; however, this advantage is limited to the occurrence of wrinkling. The results show that the mode of failure depends on incremental depth and shape of the part being formed. Additionally, tool rotation speed reduces forming forces. Investigation of the influence of SPIF on mechanical properties and chain orientation of the formed polymers shows that SPIF increases the strain at fracture and Ultimate Tensile Strength (UTS). Yield stress and Young’s modulus in the formed polymers are reduced as compared to the unformed polymers. The effect of process parameters on formability and failure mode in SPIF of Metal-Polymer laminates is also examined and it is shown that polymer thickness has a significant effect on formability. Additionally, the feasibility of forming polymers with DSIF process is presented. Preliminary results show that DSIF increases the formability and geometric definition as compared to SPIF