Fine Blanking Process Research Articles

Investigation of a novel modified die design for fine-blanking process to reduce the die-roll size

Abstract Fine-blanking is known as an effective sheet metal forming process to obtain precisely blanked parts with smooth cutting surface. However, the die-roll occurred in the sharp area is an inevitable problem which decreases the working performance and service life of the part. In order to reduce the die-roll size, a modified die design for fine-blanking process was proposed. The cutting edge of the die is set on an indenter arranged along the sharp area, while in the conventional die design, cutting edge is set on the die directly according to the part outline. The finite element method was used to optimize the die structure. The material flow was studied to explain the mechanism of the modified die design compared to the conventional die. The results of the FE-simulation were applied in the production of the automobile synchronizer. This part has four sharp areas where big die-roll occurs easily and yet it requires small die-roll sizes strictly. The experiment results proved that this novel die design was quite effective to reduce the die-roll size, which showed a promising application in future real practice.

An investigation on the microstructure of the fine-blanked sprocket

A sprocket is a profiled wheel with teeth that meshes with a chain, track, or other perforated or indented material. Instead of conventional machining methods, the fine-blanking process has been increasingly adopted to manufacture sprockets recently. On the basis of advantages of the fine blanking, the quality and the dimensional precision of the sprocket can surely be improved, especially those of the cut surface. In this paper, an investigation has been made on the microstructure of the sprocket tooth surface, since the microstructure is a significant factor affecting the performance of the part. Examinations by optical microscopy and SEM revealed microstructures at different locations of a sprocket tooth. In addition, numerical simulations of the fine-blanking process have been conducted by using a coupled thermo-mechanical finite element model. Based on results of the simulations, the distributions of temperature, strain, and metal flow velocity have been obtained to explain the microscopic phenomena. Moreover, the formation of the flown line and the die-roll, as well as the initiation and the propagation of the crack, has also been discussed in this work. Both of the numerical and experimental results were in good agreement with the mechanism of fine blanking.

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.

Application of mold trough design to blanking technology

In this study, a blanking technique applicable to various metals and metal thicknesses was developed. The V-ring mold design used in the conventional fine blanking process was modified by incorporating an annular trough adjacent to the cutting edge of the mold. The proposed technique imparted sufficient strength to the target section to withstand high hydrostatic pressures and fractures. To determine the optimum trough width for obtaining a high-quality shear surface, blanking experiments were conducted on three metal materials with different trough widths and blank holder pressures. The annular trough of the mold reduced fracture defects and improved the quality of the shear zone. In addition, the developed approach is applicable to sheet stocks and thick plates. Experimental results demonstrate that the proposed technique outperforms conventional fine blanking.

Experimental and numerical analysis of micromechanical damage for DP600 steel in fine-blanking process

In fine-blanking process, metallographic inspection shows that highly elongated and densely packed grains extend along the shear direction within a narrow large deformation region, meanwhile micro-cracks initiate and grow up. By taking the effect of shear loading into account, the recent modified GTN model proposed in 2014 is implemented and validated. The shear damage model combines the damage mechanics concept with the porous plasticity model and is applied to simulate fine-blanking process to verify its accuracy in predicting material damage and tearing fracture. The formation and propagation of shear band in fine-blanking process are studied. Both numerical results and experimental observations reveals that the effect of shear damage plays a significant role in inducing tearing, which eventually leads to fracture failure in the fine-blanking process.

A Study Of The Die Roll Height Of SHP-1 And SCP-1 Materials In The Fine Blanking Process

Abstract The height of the die roll, the distance of the V-ring, and the shear rate were varied with the aim of investigating the effects of the applied changes on the fine blanking line in a cold-rolled and a pickled steel sheet, referred to as SCP-1 and SHP-1, respectively. Both materials consisted primarily of a ferrite phase with small amounts of impurities including F, Mn, and Cr. The distance was found to be a very important factor in controlling the shear of the V-ring in the fine blanking process. When the position of the V-ring was set at distances of 1.5 mm and 2 mm, the die roll height increased with increasing shear speeds from 6.4 m/min to 10 and 16 m/min. Analysis of the influence of the shear rate revealed that low rates resulted in the lowest die roll heights since the flow of material was effectively inhibited.

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.

Numerical Study on the Comparison of Deformation Characteristics during the Fine Blanking Process of Spur Gears and Helical Gear

As important transmission components, helical gears have been widely applied to mechanical and automotive fields. The traditional manufacturing process for helical gears is machining, which is time-consuming and result in the high cost of gears. In order to improve the production efficiency and product quality of helical gears, a novel forming process principle for the fine blanking of helical gears was developed. In this study, reliable three-dimensional (3D) rigid-plastic finite element (FE) models of single tooth and complete gears were set up and investigated using the software Deform-3D, the deformation characteristics of fine blanking of spur gears and helical gears were compared. Based on the valid numerical models, variation tendency of different field variables such as damage material flow velocity, and mean stress were obtained, as well as the feature of the tooth section, which provides a better understanding of the deformation mechanism of rotational fine blanking process.

Finite Element Analysis of the Fine Blanking Process for Seat Recliner Plate Holder of Recreation Vehicle

In this paper, the finite element analysis (FEA) of the fine blanking process was conducted for the seat recliner plate holder of recreation vehicle. Because the plate holder was a complex part with the various dimple shapes, it was formed and blanked with a three-station progressive fine blanking tool. The fine blanking tool was optimally designed, manufactured and performed the fine blanking experiments. The shear surface of the outer contour, the stress and strain of the part, and the loads of the tool elements were estimated by the results of the fine blanking simulation. Because the plate holder samples from fine blanking experiments had the good accuracy of the dimples’ position and dimension, it would be noticed the fine blanking simulation was conducted without error.

Piezoelectric-based non-destructive monitoring of contact pressures in fine-blanking process

A piezoelectric polyvinylidene fluoride film stress sensor was developed to measure the contact pressure on the sheet near the cutting edge in the fine-blanking process. Two cases with and without cracks in the fine-blanking surface were studied. The relationship between the contact pressure and crack width was investigated using the Kriging methodology at different punching speeds. The maximum contact pressure appeared at the beginning of sheet punching, but not at the end of V-ring indention. For the case with and without cracks in the fine-blanking surface, one and two fluctuations of contact pressure are observed, respectively. Using the Kriging model, a fine-blanked surface with a reduced crack width can be obtained using the optimal values of contact pressure and punching speed.

Finite Element Simulation of Effect of Part Shape on Forming Quality in Fine-blanking Process

Fine-blanking as an effective and economical sheet metal cutting process has been widely used in the precision machines, automobiles, electronics and aircraft areas. This process can produce smooth-sheared edges over the full workpiece thickness in one single operation with the optimized process parameters. However, the crack phenomenon always occurred in the fine-blanking process when the part shape is complicated. The forming quality of the part with concave and convex shape has been investigated with finite element simulation and experiment methods. In order to reveal the effect of part shape on the fine-blanking process comprehensively, a simple finite element model in which the part has convex and concave shape were created. The effects of the angle between the neighbouring edges and height of the convex and concave on the surface quality have been investigated. Furthermore, the way to design the parameters for parts with complicated shape has been discussed in this paper.

Development of Closed Extruding Fine Blanking Technology

The closed-extruding fine blanking was developed to form thick plate and low plasticity materials. In this paper, the principle and process of the closed-extruding fine blanking were elaborated. The material flow and the influence of the process parameters on the forming quality were analyzed. At the same time, by means of metallographic observation and analysis of microhardness as well as surface residual stress, the characteristics of the material in the closed-extruding fine-blanking process were investigated.

A Study on the Clearance Design of Fine Blanking Tool for Al Special Parts with Various Inner Corner Shapes

Fine blanking is a press-working process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Recently, many studies on the weight reduction of automobile for fuel saving were underway. Especially, there are many examples in which light metal like Al were applied for automotive parts. The clearance between the punch and die of a fine blanking tool is an important design factor that affects the sheared surface of a product. In a fine blanking process, the clearance is typically assigned a 0.5% material thickness. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. In this study, a setting for optimum clearance was proposed for inner corner shapes by checking shear characteristics and bulging effects according to various clearances. After designing a special part with various corner shapes possessing Al5052 (thickness: 4 mm), a fine blanking tool was constructed and fine blanking experiments were conducted. The result could be usefully applied in fine blanking processes for Al automobile parts with corner shapes in the future.

A Study on the Clearance Decision of Fine Blanking Tool for Eco-Al Special Parts with Various Inner Corner Shapes

Fine blanking is a press-working process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Recently, many studies on the weight reduction of automobile for fuel saving were underway. Especially, there are many examples in which light metal like Al were applied for automotive parts. Eco-Al is the new material which is replaced Mg of aluminum alloy with Mg+Al2Ca, therefore Eco-Al material has improved mechanical properties and formability. The clearance between the punch and die of a fine blanking tool is an important design factor that affects the sheared surface of a product. In a fine blanking process, the clearance is typically assigned a 0.5% material thickness. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. In this study, a setting for optimum clearance was proposed for inner corner shapes by checking shear characteristics and bulging effects according to various clearances. After designing a special part with various corner shapes possessing Eco-Al5052 (thickness: 4 mm), a fine blanking tool was constructed and fine blanking experiments were conducted. The result could be usefully applied in fine blanking processes for Eco-Al automobile parts with corner shapes in the future.

A Study on the Shear Characteristics of Fine Blanking for Al 5052 and Eco-Al 5052 Sheet

Fine blanking is a press-working process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Recently, many studies on the weight reduction of automobile for fuel saving were underway. Especially, there are many examples which new materials were applied for automotive parts. Eco-Al is the new material which is replaced Mg of aluminum alloy with Mg+Al2Ca, therefore Eco-Al material has improved mechanical properties and formability. In this paper, the shear characteristics of Eco-Al 5052 and Al 5052 parts which had been blanked by fine blanking process were analyzed and compared. As a result, even though Eco-Al and Al sheets were not treated for fine blanking, the cutting surface of Eco-Al and Al parts had the shear surface of more than 85% and dimensional accuracy of more than ISO accuracy grade 9.

The FEM Simulation of the Pressure and Fine-Blanking Quality

A numerical model research of fine-blanking has been built up. The fine-blanking process of parts with pressure is 0KN20 KN40 KN60 KN respectively , thickness of plate 2.9mm and diameter 16mm,of steel 45, has been simulated. Through simulation, the study gets the material distribution situation of mean-stress fields in the progress of fine-blanking, and analyzes the relation between mean-stress fields and the crack of shearing zone. And get the pressure optimization value.

An Experimental Study on the Clearance Design of Fine Blanking Tool for High-Strength Steel Special Parts with Various Inner Corner Shapes

The clearance between the punch and die of a fine blanking tool is an important design factor that affects the sheared surface of a product. In a fine blanking process, the clearance is typically assigned a 0.5% material thickness. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur.In this study, a setting for optimum clearance was proposed for inner corner shapes by checking shear characteristics and bulging effects according to various clearances. After designing a special part with various corner shapes possessing SPFH590 (thickness: 4 mm), a high-strength steel material, a fine blanking tool was constructed and fine blanking experiments were conducted. The result could be usefully applied in fine blanking processes for high-strength steel automobile parts with corner shapes in the future.

Process design of cold forging with thick plate for seat recliner parts

A seat recliner is a device that connects the seat back with the seat frame. It can be used to adjust the lean angle. An important component of a seat recliner is the sector tooth, which has thus far been manufactured by the fine blanking process. In this study, we propose the use of the cold-forging process as an alternative in order to achieve improved mechanical stiffness and reduced weight. To apply the cold-forging process, the entire forming process is divided into two stages in order to improve the dimensional accuracy of the tooth part of the sector tooth. Uniform plastic deformation is induced by the design of the preform on the contacting area in the sector tooth by simultaneously using a bending and a forging mechanism. By the proposed process design for the two-step cold forging process, the mechanical stiffness and surface roughness of the test product can be improved. Furthermore, the weight can be reduced by 10% by applying a 3.6-mm-thick plate instead of a 4.0-mm-thick one. Finally, the number of forming stages can be reduced without sacrificing the dimensional accuracy of the sector tooth and increasing the punch load.

An Innovative Experimental Setup for Laboratory Tests of Fine Blanking Process

Fine blanking process can produce parts with accurate cutting edge quality. Studying the effects of process parameters on accuracy and quality of fine banking products are usually expensive. In this paper, an innovative idea has been introduced for a set of fine blanking test rig which is not as complicate and expensive as standard fine blanking dies but it could be used alternatively for limited laboratory works. The main concept of the rig is based on manual adjustment of counter punch force and blank holder force by means of rubber spring and torque meters respectively. As a case study, the effect of counter punch force of fine blanking process in a 2mm thickness steel AISI-1006 sheet was studied by this test rig. The results show that increasing the counter punch force makes burr dimension on cutting edge to get smaller which means better quality of the product.