V-ring Indenter Research Articles

Comparative study of v-ring indenter configurations in fineblanking in order to derive tool design guidelines

The v-ring indenters and their configurations play a major role in the fineblanking process, directly influencing component quality and characteristics. While past studies regarding residual stresses of blanked components focused mainly on the use of a pair of v-rings, so far no efforts were undertaken to compare different v-ring setups, deducing tool design guidelines and enabling possible cost savings. Therefore, a comparative study of different v-ring indenter setups and their influence on cut surface parameters, surface hardness and induced residual stresses of the produced components was performed. The obtained results indicate a minor influence of blank holder-sided v-rings on the observed component characteristics in comparison to indenters situated on the die leading to recommendations with regard to cost-efficient tool design.

Application of Finite Element Method to Analyze the Influences of Process Parameters on the Cut Surface in Fine Blanking Processes by Using Clearance-Dependent Critical Fracture Criteria

The correct choice of process parameters is important in predicting the cut surface and obtaining a fully-fine sheared surface in the fine blanking process. The researchers used the value of the critical fracture criterion obtained by long duration experiments to predict the conditions of cut surfaces in the fine blanking process. In this study, the clearance-dependent critical ductile fracture criteria obtained by the Cockcroft-Latham and Oyane criteria were used to reduce the time and cost of experiments to obtain the value of the critical fracture criterion. The Finite Element Method (FEM) was applied to fine blanking processes to study the influences of process parameters such as the initial compression, the punch and die corner radii and the shape and size of the V-ring indenter on the length of the sheared surface. The effects of stress triaxiality and punch diameters on the cut surface produced by the fine blanking process are also discussed. The verified process parameters and tool geometry for obtaining a fully-fine sheared SPCC surface are described. The results showed that the accurate and stable prediction of ductile fracture initiation can be achieved using the Oyane criterion.

Parameters Design of Discontinuous Dot Indenter in Fine Blanking Process with Different Thickness Workpiece

This paper proposes a new blankholder to fine blanking process. V-ring indenter has been widely applied in fine blanking to produce clean cut parts, however, it is difficult to be manufactured, the machining accuracy of which is hard to ensure and the cost is very high. In this approach, the fine blanking process combined with discontinuous dot indenter was put forward and the parameters design for workpiece with different thickness was studied with the finite element simulation and the orthogonal experiment methods. The larger burnished surface zone can be obtained by optimizing discontinuous dot indenter parameters. In addition, the relationship between the discontinuous dot indenter parameters and the workpiece thickness was got from data processing. Finally, applying this relationship to fine blank workpiece with different thickness, nearly full clean cut surface part was obtained.

Numerical and experimental investigation of the discontinuous dot indenter in the fine-blanking process

The fine-blanking process has been widely applied in industries to produce clean-cut surface parts. The V-ring indenter blank holder, which is an essential part of the fine-blanking tool, is notably important in increasing the cutting surface quality of blanked parts. Because the V-ring indenter is difficult to manufacture, it is difficult to ensure the machining accuracy, and the cost is notably high. In this study, a new discontinuous dot indenter blank holder is presented. The discontinuous dot indenter blank holder can improve the quality of the fine-blanked surface, which is identical to that of the V-ring indenter, but the manufacture process is notably easy, and the cost is notably low. The hydrostatic stress, material flow and quality of the fine-blanked surface in the fine-blanking process were analyzed to reveal the discontinuous dot indenter mechanism. To obtain a larger burnished zone, the finite-element (FE) simulation and ANOVA technique were applied to optimize the discontinuous dot indenter parameters, i.e., dot diameters, fillet radius, distributions, positions and heights. Next, these optimal parameters were applied to fine-blank a spur gear, and the experiment results have a good agreement with the FE simulation results. Moreover, the results also indicate that the discontinuous dot indenter can be used in the fine-blanking process to obtain almost full clean-cut surface parts.

Force parameters and experimental characterisation in fine-blanking process

It is important that before any experimental study in fine-blanking process a raw estimation is obtained of any forces which applied to the blank. Thus, this paper aims to present the development of force parameters and experimental characterisation in fine-blanking process. For this reason the effects of blank thickness and tensile strength on fine-blanking force have been examined by experimental approach and theoretical formulation. Also, the effects of counterforce and V-ring length on workpiece flatness and total force have been illustrated experimentally. The results show that the mechanism of the V-ring indenter could be experimentally clarified on the basis of material flow analysis. Also, the flatness of workpiece increases with an increase in counterforce in fine-blanking process. Furthermore, forming force increases with an increase in the blank thickness and tensile strength.

A novel fine-blanking approach

This paper proposes a novel approach to fine blanking. The V-ring indenter used in conventional fine blanking is no longer required; a trough on the die is used instead. In this approach, the cutting process combined with high hydrostatic stresses produced from the trough on the die cutting edge can substantially decrease the fracture in the shear zone. A series of experimental tests with experimental specimens of various thicknesses was conducted. The burnished surface obtained from this approach can nearly achieve the complete thickness of the blank in one operation, suggesting that the fracture zone can be nearly eliminated. In addition, the surface roughness of the burnished surface range was measured between 0.03 and 0.08 μm, and the tolerance band for the diameter was between IT2 and IT4. These results indicate an improvement in the values obtained using conventional fine blanking.

Effects of Parameters on Fine Blanking of Steel Synchronizer Ring Teeth

The influences of parameters on fine blanking of steel synchronizer ring teeth have been studied in this paper. Based on the finite element (FE) analysis software DEFORM-3D, a three-dimensional FE model of fine blanking of steel synchronizer ring teeth was established. By analyzing the distribution of hydrostatic stress, the length of smooth cut surface and the height of die-roll, the influence of parameters (i.e., counterforce, blanking clearance and V-ring indenter form) on the cut surface of synchronizer ring teeth were discussed. The quantitative relationships between parameters and the cut surfaces were established. The results show that: Increasing counterforce, decreasing blanking clearance and V-ring indenter located on die are conducive to increase the length of smooth cut surface and to decrease the height of die-roll. These results have a certain guiding significance on the production process of fine blanking of steel synchronizer ring.

Effects of parameters on rotational fine blanking of helical gears

The application of fine blanking to the manufacturing of helical gears directly from a strip has been restricted due to the traditional linear cutting stroke of the punch and die. In this work, rotational fine blanking which combined the linear and rotational motion of punch and counterpunch was applied for the forming of helical gears. A three-dimensional (3D) rigid-plastic finite element model was developed on the DEFORM-3D platform. By finite element simulation and analysis, the influences of key parameters on the punch load and cut surface were investigated. It is shown that: 1) with increasing the counterforce or helical angle, the punch load and the depth of die roll increase; 2) with increasing blank holder force, the punch load increases while the depth of die roll decreases; 3) V-ring indenter facilitates an improvement in the quality. The results of this research reveal the deformation mechanism of rotational fine blanking of helical gears, and provide valuable guidelines for further experimental studies.

Investigation of the shear-zone length in fine hydromechanical blanking

A new process called fine hydromechanical blanking is proposed in this paper. In contrast to conventional fine blanking, in fine hydromechanical blanking, the V-ring indenter on the guide plate is replaced by a V-ring cavity formed in a workpiece and pressurized by hydraulic pressure. In addition, the counterforce from the blanking ejector is replaced by the hydraulic pressure acting on the ejector chamber. An experimental algorithm for optimization based on the Taguchi method, in which a genetic algorithm is used for searching, is proposed to determine the largest shear-zone length. From the experimental results, it is concluded that the proposed method can achieve the same effects as conventional fine blanking. In addition, an investigation of the effect of the hydraulic pressure in the V-ring cavity and ejector chamber on the shear-zone length was conducted through a series of experiments. The results show that the experiments were greatly affected by the height of the burnished surface and indicate the significance of the hydraulic pressure in the V-ring cavity and ejector chamber.

Modelling of Fine Blanking Process of the Aluminium Sheets

The required technological quality of the blanked products can be achieved through operations of fine blanking. This allows for obtaining products with improved dimensional accuracy and good quality cut-surface. In order to cut products from soft materials, including aluminium and its alloys, the methods of fine blanking with upsetting and fine blanking with reduced clearance are typically employed. The study presents the results of numerical modelling of the fine blanking process for a disk made of 1-millimetre sheet aluminium EN AW-1070A. The goal of the numerical simulations was to evaluate the effect of clearance between blanking die and the punch, and the impact of V-ring indenter on stress and strain distribution in the shearing zone.

Application of Taguchi technique to investigation of geometry and position of V-ring indenter in fine-blanking process

One of the special features of the fine-blanking process is the use of the V-ring indenter. The V-ring geometry, namely its angle and height, in addition to its position, affects features of the fine-blanked surface. In this study, the finite element (FE) simulation, the Taguchi technique, and the analysis of variance (ANOVA) techniques were carried out to investigate the degree of importance of V-ring indenter parameters. The results indicated that the height and position of the V-ring indenter have a major influence on the fine-blanking process, followed by the V-ring indenter angle. The combination of the FE-simulation, the Taguchi method, and the ANOVA technique was an effective tool to predict the degree of importance of the V-ring indenter parameters in the fine-blanking process, in addition to facilitating an improvement in the quality of the fine-blanked parts by optimization of these V-ring indenter parameters.

Investigation Mechanism of V-Ring Indenter Geometry in Fine-Blanking Process

The V-ring indenter geometry (angle, height and position) was investigated by using the finite element method (FEM) to theoretically clarify the mechanism and its action in the fine-blanking process. The FEM simulation results indicate that very small or very large V-ring indenter angles, heights, and positions cause difficulty in the rotation of the material-flow and that the hydrostatic pressure is generated with great difficulty in the blanked material; therefore, crack formation occurs easily. The application of a suitable V-ring indenter angle, height, and position significantly suppresses the formation of rotating flow, which results in increased hydrostatic pressure, and crack formation is consequently prevented.

Finite-element analysis of V-ring indenter mechanism in fine-blanking process

In fine-blanking process, V-ring indenter is very important in increasing the edge quality of the blanked part. Previous research in this field was mainly experiment-based; therefore, the theoretical mechanism was not clarified. In this study, the V-ring indenter mechanism was investigated using the finite element method. The mechanism and effects of the V-ring indenter could be theoretically clarified on the basis of material flow analysis and stress distribution. The application of the V-ring indenter increased compressive stress before the cutting phase, and significantly suppressed the increased rotation of material flow during the cutting phase. This, in turn, caused increased hydrostatic compressive stress, resulting in a larger smooth cut surface.

The effect of V-ring indenter on the sheared surface in the fine-blanking process of pawl

Finite element analysis has been performed to investigate the effect of V-ring indenter on the sheared surface in the fine blanking of pawl, which is a part of the automotive safety belt and is made of AISI1045 sheet. The Cockcroft and Latham’s fracture criterion and the element kill method are used in order to simulate the blanking operation successfully. Simulation results are obtained for various positions and heights of the V-ring indenter, and the experimental results are compared with theoretical results. It is shown that the FEM simulation results can be useful for predicting the optimal condition for fine blanking products.