Punching Process Research Articles

Structure optimization design of forging hydraulic press

In order to improve the centring and production efficiency of punching, we can add a centring structure to improve the centring of forgings in the punching process, which is mainly used to ensure the correct position of forgings during upsetting and punching, that is, to ensure the center of forgings and the center of hydraulic press to coincide. At the same time, a swing punch structure is added to clamp the replaceable punch, which is mainly used to ensure that the center of the hydraulic press coincides with the center of the punch, and there is no need for manual or auxiliary machine in the working process of the swing punch structure, which can greatly improve the production efficiency.

Structural Design and Property Evaluations of Foam-based Composite Materials: Effect of Perforation Depth and Foam Density on the Mechanical, Sound Absorption, and Thermal Properties

Nonwoven fabrics and rigid polyurethane foam(PUF) are commonly used materials as building materials, but there are few studies on combining both materials and reporting characteristic evaluations for the application. In this study, N/L/Fr nonwoven fabrics are combined with PUF to produce N/PUF composites, and then a needle punching machine is used for perforation, thereby produces perforated N/PUF composites. With PUF densities being 70 kg/m3 and 80 kg/m3, a perforation depth of 100 % results in significantly decreasing mechanical properties. Based on the results of thermal conductivity coefficient, the employment of needle punch process results in a decrease in the thermal insulation of N/PUF composite; however, the descending level is comparatively smaller when PUF is made of a greater density. In the thermogravimetric analysis (TGA), the char residue is 4.86 % for PUF and 11.68 % for N/PUF composites, indicating that N/L/Fr nonwoven fabrics improve the thermal stability of PUF. As per limiting oxygen index (LOI), the part of proposed N/PUF composites that first contacts the flame is N/L/Fr nonwoven fabrics, which causes an LOI of 33 when in practical application and resembles the LOI (33) of N/L/Fr nonwoven fabrics. Based on the test results, the optimal perforated N/PUF composites are made of a PUF density of 80 kg/m3 and a perforation depth of 75 %, and the optimal compression strength is 375.29 kPa, which increases by 10.96 %. In addition, the proposed products have the same impact absorption capacity (5.88 J) as that of N/PUF composites, which absorb a total of 98.16 % impact energy. The sound absorption is improved in the frequency band of 800–2500 Hz, which broadens the sound absorption bandwidth and benefits the application as being sound absorbent materials.

Stress Modeling Study on Package Crack Due to Debris

Very thin semiconductor package is very prone to package crack. This paper discusses the stress modeling study conducted to understand the package crack problem in a specific smart card package. Finite element analysis (FEA) was used to analyze the maximum package stress level and corresponding location to find out if the presence of debris during the package assembly punching process could cause such problem and how it would happen. Based on the stress results, it was confirmed that even with a 60μm-thick piece of debris under the package, crack at the top is possible due to package bending and mold stress exceeding the flexural strength of the package mold material. The stress increases as the debris location is moved closer to the area where force is applied during the punching process. The study shows that the presence of debris should not be taken for granted though how small the debris may seem because significantly high bending stress could still be induced especially for very thin packages. Eliminating any source of debris in the package assembly process.is very important to prevent package crack.

Finite Element Analysis of the Magneto-Mechanical Coupling Due to Punching Process in Electrical Steel Sheet

In this article, a finite element (FE) modeling of the punching effect on the magnetic properties of electrical steel sheet is carried out. For that, the modified anhysteretic Sablik model is applied together with the plastic strain distribution obtained from a punching process simulation performed using the software ABAQUS. First, a synchronous electrical machine is simulated including the effect of the punching process, and it shows the degradation of the magnetic flux density at the lamination edges and an increase of the iron losses. Then, results obtained from the magneto-mechanical simulation are investigated in terms of the method used to implement the plastic strain distribution in the FE computation. Two examples have been investigated: a square steel sheet and a tooth of an electrical machine.

Clearance effect on the sheared edge characteristics of key chain cranioplasty plate in the punching process

Punching process is a process to cut sheet metal by pressing the workpiece until it exceeds the elastic limit of the material. In this study, the researcher used the finite element method as a solution to a problem during the manufacturing process. This research simulated the punching process, particularly hole-making, in keychain cranioplasty product to obtain smoothest sheared edge characteristics by optimising the clearance amount variations. The product had 1.53 mm diameter and 0.6 mm thickness of titanium alloy plate. The analysis was performed using the finite element method with the support of ANSYS Explicit Dynamic software. During the punching process, the punching speed was 2600 mm/min. The results showed that reductions in clearance, below 2.5% clearance, produced rougher sheared edge. The higher clearance produce rougher sheared edge. The 2.5% clearance was the standard for a right sheared edge to make a hole in the keychain cranioplasty plate with 0.6 mm thickness.

Development of PLC based Sequential Pneumatic Punching System

Programmable logic sequential pneumatic system is developed for mechanical applications, like sealing, name punching, plate designing, etc. punching machine is considered as inevitable in almost all the industries like mechanical, electronic, food industries and automobile, etc. To print the hallmarks, logos as a brand. In respect to reducing the processing time by upgrading the conventional system to automation by integrating with Programmable logic control (PLC) as the system works with the interfacing of hardware (punching machine) and solenoids to control the actuation sequence. A sequential pneumatic PLC-based automatic punching machine is designed to have great control over the process of punching the hallmarks and logos with an automating feeding system followed by the punching process, which leads to a high production rate and reduces the process lead time, and increases the safety of workers.

Improvement of the slotless tubular permanent magnet linear motor with lighter mover mass for punching applications

The slotless tubular permanent magnet linear motor (STPMLM) offers obvious advantages when it is applied to the punching system, such as space saving and controllable impact strength. Herein, the mechanical and electromagnetic coupled differential equations were established to present a comprehensive analysis of the relationship between mover mass and motor performance in the punching system. The travel time of the punching movement was expressed analytically under the condition of the mover obtaining the same impact kinetic energy, and the relationship between the mover mass and the resistive energy consumption in one punching process was also deduced under the same condition. Then the analytical results were validated by a numerical model. The studies show that a lighter mover mass can contribute to less resistive energy consumption and faster dynamic response in the punching applications. Based on that, a STPMLM with special-shaped yoke was designed for lighter mover mass. Moreover, prototype experiments including static thrust characteristic and dynamic performance were conducted. The experimental results proved that the proposed permanent magnet linear motor with special-shaped yoke can improve the dynamic performance and reduce resistive energy consumption while ensuring that the electromagnetic performance is not affected.

Verification of electric steel punching simulation results using microhardness

One of the most dominant manufacturing methods in the production of electromechanical devices from sheet metal is punching. In punching, the material undergoes plastic deformation and finally fracture. Punching of an electrical steel sheet causes plastic deformation on the edges of the part, which affects the magnetic properties of the material, i.e., increases iron losses in the material, which in turn has a negative effect on the performance of the electromagnetic devices in the final product. Therefore, punching-induced iron losses decrease the energy efficiency of the device. FEM simulations of punching have shown significantly increased plastic deformation on the workpiece edges with increasing tool wear. In order to identify the critical tool wear, after which the iron losses have increased beyond acceptable limits, the simulation results must be verified with experimental methods. The acceptable limits are pushed further in the standards by the International Electrotechnical Commission (IEC). The new standard (IEC TS 60034-30-2:2016) has much stricter limits regarding the energy efficiency of electromechanical machines, with an IE5 class efficiency that exceeds the previous IE4 class (IEC 60034-30-1:2014) requirements by 30%. The simulations are done using Scientific Forming Technologies Corporation Deform, a finite element software for material processing simulations. The electrical steel used is M400-50A, and the tool material is Vanadis 23, a powder-based high-speed steel. Vanadis 23 is a high alloyed powder metallurgical high-speed steel with a high abrasive wear resistance and a high compressive strength. It is suitable for cold work processing like punching. In the existing literature, FEM simulations and experimental methods have been incorporated for investigating the edge deformation properties of sheared surfaces, but there is a research gap in verifying the simulation results with the experimental methods. In this paper, FEM simulation of the punching process is verified using an electrical steel sheet from real production environment and measuring the deformation of the edges using microhardness measurements. The simulations show high plastic deformation 50 μm into the workpiece edge, a result that is shown to be in good agreement with the experimental results.

Investigation of punching process using steel and aluminum alloys

Investigation of punching process using steel and aluminum alloys

Performance and optimization of parameters on rubber punching process

The present problem in rubber industries are punching and processing of rubbers. The improper dimensional accuracy is obtained from other machines. The electric operated punching machine is used to resolve the problems. In this paper, the rubber material which made by polyisoprene is pressed under hydraulic punching machine. The rate of quality and its processing time also better than other methods. The cutting of rubber is made through die unit and its control the process parameters. The experimental objectives are to support the development of a model to predict the shape of the rubber. The model is used to investigate the effect of potential factors influencing the punching process and their interactions. The punching process parameters are optimized through taguchi optimization method and their parametric contribution has been studied through variance analysis.

Effect of Die Clearance on Peak Punching Force During Cryogenic Micropunching of Polycaprolactone

Abstract Microscale holes were punched at cryogenic conditions in polycaprolactone (PCL) membranes to create synthetic three-dimensional (3D) tissue scaffolds through multilayer stacking of two-dimensional (2D) porous membranes. Punching forces were experimentally measured, and finite element modeling of the punching process was validated by comparing punching force results. Holes of nominal diameter of 200 μm were punched in PCL films of two different thicknesses: 40 μm and 70 μm. Die clearances used for holes in 40 μm thick films were 15.0%, 30.0%, and 45.0%. Die clearances used for holes in 70 μm films were 8.6%, 17.1%, and 25.7%. All holes were punched while the PCL film was in thermal equilibrium with a bath of boiling liquid nitrogen. Punching forces were analyzed to study the effect of die clearance and film thickness. A 3D finite element simulation of the punching process was done using deform 3d software. Cryogenic material properties of PCL used in the simulation were determined experimentally. It was concluded that finite element simulation for the cryogenic micropunching process can be used to predict peak punching forces with reasonable accuracy, which is a key factor to be considered while designing the punching dies. The finite element simulations did not predict an optimal die clearance to minimize peak punching force. However, the measured peak punching forces for 70 μm thick film seem to favor the smallest die clearance to minimize peak punching force.

Tensile, compressive, and fatigue strength of a quasi-isotropic carbon fiber reinforced plastic laminate with a punched hole

The mechanical properties of a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate with a punched hole were investigated. During the punching process, pressure was applied to the laminate through the upper and lower blank holders of a punching machine; the clearance between the punch and blank holders was set to be small to suppress damage in the CFRP laminates. Due to the dragging of plies encountered during punching, the surface of the punched hole was relatively uneven as compared to that of the drilled hole. However, the effect of the uneven surface created during the punching process was not as significant on the tensile and compressive strength of the open hole as compared to the manufacturing damages generated by drilling processes. The stress–number of cycles to failure curves for the open-hole tension–tension fatigue tests also showed comparable results between the punched- and drilled-hole specimens. These results indicate that there were no significant differences in the mechanical properties of CFRP laminates with a punched hole, and thus present the possibility of a highly productive hole-making process using the punching method.

Evaluation of Preosteoblast MC3T3-E1 Cells Cultured on a Microporous Titanium Membrane Fabricated Using a Precise Mechanical Punching Process.

The surface topography of Titanium (Ti) combined toughness and biocompatibility affects the attachment and migration of cells. Limited information of morphological characteristics, formed by precise machining in micron order, is currently available on the Ti that could promote osteoconduction. In the present study, a pure Ti membrane was pierced with precise 25 μm square holes at 75 μm intervals and appear burrs at the edge of aperture. We defined the surface without burrs as the “Head side” and that with burrs as the “Tail side”. The effects of the machining microtopography on the proliferation and differentiation of the preosteoblasts (MC3T3-E1 cells) were investigated. The cells were more likely to migrate to, and accumulate in, the aperture of holes on the head side, but grew uniformly regardless of holes on the tail side. The topography on the both surfaces increased osteopontin gene expression levels. Osteocalcin expression levels were higher on the head side than one on the blank scaffold and tail side (p < 0.05). The osteocalcin protein expression levels were higher on the tail side than on the head side after 21 days of cultivation, and were comparable to the proportion of the calcified area (p < 0.05). These results demonstrate the capacity of a novel microporous Ti membrane fabricated using a precise mechanical punching process to promote cell proliferation and activity.

On the failure of punching process

Punching is recognized to be useful in sheet cold forming. To the best of our knowledge, researchers have been interested just in thin ones. That is why the interest of this paper is in premature AISI D2 punch damage in case of thick S500 MC plettac. Several techniques such as optical microscopy, Energy dispersive spectroscopy (EDS), Vickers hardness and scanning electron microscopy (SEM) were used in order to extract failure causes. The obtained results showed that back-up plate, corrosion, wear and fatigue as well as head punch cracking, scaling, mating and inflation lead to a short-life service. Microstructures characterizations exhibit fractured chromium carbides and lamellar pearlite bending during head tool and back-up plate contact.

Finite element analysis of self-piercing riveting of aluminum alloy and carbon fiber reinforced polymer composites

Self-piercing riveting (SPR) is a high-speed fastening process that can join similar and dissimilar sheet materials without the need for pre-processing such as drilling or punching. During SPR processes, two overlapping sheets are joined by a rivet. The upper sheet is punched first by the rivet and then the lower sheet is deformed between the rivet and the die, creating a mechanical interlock. In this study, self-piercing riveting of aluminum alloy and carbon fiber reinforced polymer composites (CFRP) sheets was analysed using finite element simulations. For the finite element simulation of SPR processes, the orthogonal elasticity, the fracture model, and the cohesive zone model were used for describing the behaviour of CFRP. For validation of the composite material model, the punching process of CFRP was performed and the results were compared with FE predictions. The SPR process of the aluminum alloy and CFRP was simulated numerically and the performance of the joint was evaluated.

Experimental investigations of electromagnetic punching process in CFRP laminate

ABSTRACT Electromagnetic punching is an efficient hole-machining process in order to satisfy structural or functional requirements. In this paper, the electromagnetic punching experiments were carried out to investigate hole-punching quality of carbon fiber reinforced plastic laminates with various punches. The quality evaluation such as macroscopic measurement, microstructure observation and delamination analysis was implemented. As a comparison, drilling experiments and corresponding quality tests were also accomplished. The results showed that the cutting tools had significant effects on the quality of the formed holes. For electromagnetic punched holes, the edged punch was superior to flat punch and hollow punch in term of the machining accuracy, microscopic morphology and delamination defect. Comparing with drilling process, the delamination factors of edged punched holes were lower than that of drilled holes on the basic of ultrasonic C-scan technology, implying that delamination of drilled hole was severer than edged punched holes.

Effect of Process Parameters on Tensile Strength of Sansevieria and Areca Husk Fiber Needle-Punched Nonwoven Fabrics

Abstract The present study intends to determine the optimum process conditions for needle punching the nonwoven fabrics produced from blends of sansevieria and areca husk fibers. The Box–Behnken experimental design is used for the optimization of the fabric weight (200–400 g/m2), punch density (150–250 punches/cm2), and blend ratio (30:70–70:30) with respect to the tensile strength of the nonwoven fabrics and to evaluate the effects and interactions of the needle punching process conditions. The optimum process conditions were obtained at a fabric weight of 400 g/m2, 250 punches/cm2, and 70:30 blend ratio. Nonwoven fabric with a highest breaking force of 17.58 N in the machine direction and 36.51 N in the transverse direction was obtained at the optimum process conditions. The nonwoven fabric developed from this study can be used as a floor covering material in the construction field.

Evaluation of the belt punching process efficiency based on the resistance force of the compressed material

Vacuum conveyor belt punching process by using the piercing punch which cooperates with the die has potential to be modified in aspects of lowering the perforation force, extending the tool life, and improving the hole quality in the perforated belts. All these parameters have an influence on the efficiency of the process and strictly depends on the punch geometry. This indicates that based on these criteria the optimization of the tool constructional features may be performed. In the presented research, authors have shown the linear correlation between the resistance force of the compressed material of the multilayer polymer composite belt in punching and the efficiency of the process. It was also proved that using the effective geometry of the piercing punch with spherical bowl can reduce the perforation force by 69%. Based on the obtained model, the simplified optimization as well as the evaluation of the punches with defined geometry can be performed, since all characteristics of the material compressive force obtained for the effective punches were almost consistent. For proper analysis, it is necessary to use the combination of the analytical and numerical modelling, computer simulations with using the finite element method (FEM) and the experimental tests. However, by performing simple compression tests for various tool geometry on the strength testing machine, it is possible to perform the comparison analysis of different piercing punches based on the derived models. This approach can be used to evaluate the properties of selected tools for the groups of materials with wide divergence of the mechanical properties without performing the complex research.

Thermal conductivities of a needle-punched carbon/carbon composite with unbalanced structures

The XYZ 3-dimensional thermal conductivities of the C/C up to 2000 °C were measured by a laser flash method. Carbon fiber-reinforced carbon composites (C/C) were generally developed for aerospace missions due to their excellent thermal resistivity at ultrahigh temperature. C/C must endure harsh environments such as thousands of degrees Celsius without degradation of its mechanical properties. To solve this problem, among the passive thermal protection system, we suggest a method of conducting more heat through the mono-axial direction, which resulted in ease of the thermal rise in the heat receiving part. For example, the X-43A flight applied unbalanced C/C (UCC) with different carbon fiber orientation ratios according to the XY direction in the leading edge part. To investigate the difference in thermal conductivity between unbalanced C/C (UCC) and balanced C/C (BCC), unbalanced and balanced preforms were prepared by a needle punching process, and then they were densified by pitch infiltration and a carbonization process. We compared and analyzed the effects of unbalanced C/C(UCC) and balanced C/C (BCC) structures on the thermal conductivity. We also designed the “rule of mixtures” equation for calculating thermal conductivities of each C/C using reported data of carbon fiber and graphite matrix. Our calculations of thermal conductivity ratio match the ratio of real data.

P‐115: Research on Waviness Improvement for Foldable Display and Relevant Ultra‐Thin Metal Plate Modeling Process

Since the creep was an inherent characteristic of polymer materials, the all‐polymer Organic Light‐Emitting Diode (OLED) display module exhibited a permanent deformation that could not be recovered by itself. We hoped to use ultra‐thin metal plate as a support to reduce the irreversible module waviness. However, there would be a risk of crack failure causing by the stress concentration at the metal edges of the folding area. After researching among three conventional metal cutting methods (punch, etch and laser‐cut), we compared the morphologies of the cutting edges and found that the punch process was optimal for ultra‐thin metal plate cutting.