Piercing Process Research Articles

Simulation of vibration piercing of pipe blank at press

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

Three-Dimensional Finite Element Numerical Simulation and Analysis of Solid-State Processing of Metal Material

Solid-state processing of metal material is a very complex physical and chemical process, which is coupled by a series of variations including heat transfer, momentum transfer, mass transfer, and phase change. Applying three-dimensional (3D) finite element numerical method to the simulation of solid-state processing can perform analysis of metal material’s forging processes before production trial production, can obtain their relevant information such as material flow law, temperature field, and strain field under the minimum physical test conditions, thereby predicting metal material’s forming defects and improving their forging quality. On the basis of summarizing and analyzing previous research works, this paper expounded the current status and significance of solid-state processing of metal materials, elaborated the development background, current status, and future challenges of 3D finite element numerical simulation, introduced the discrimination method and free surface solution method of numerical simulation calculation, conducted finite element model’s geometric assumptions, material selection, element division, model establishment, parameter selection, and initial and boundary condition determination, and simulated and analyzed rheological casting, remelting heating, thixoforming, and rotary piercing processes of metal materials. The results show that the 3D finite element numerical method can not only simulate various processes of flow field, temperature field, stress field, and microstructure in solid-state processing but also can provide a reliable basis for effectively obtaining a reasonable description and finding a more optimized design plan for metal material processing in a short time, which plays an important role in understanding and analyzing solid metal forming process, controlling and optimizing process parameters, guiding and mastering rheological casting, and secondary heating and rotary piercing of metal materials.

The Influence of the Initial Billet on the Mechanical Properties of Pipes

The article researched the influence on the pipes mechanical properties initial billet obtained by the traditional method and the proposed method, in which the piercing process is excluded. The proposed method involves casting the initial billet for the production of seamless pipes with a cavity obtained on a continuous casting machine. The production of hot-rolled seamless pipes from a hollow billet is an urgent issue today, since central porosity and axial segregation after casting are excluded, affecting the quality of the pipes obtained in the subsequent stages of production: rolling on a mandrel mill and reducing. The result is a minimal deviation of the mechanical properties of steel samples obtained by double deformation of a hollow continuously cast billet from samples obtained according to the traditional scheme, including the piercing process.

Analytical method of determining the movement resistance of a tip for forming rectangular technological hole in the lower structure tracks

The aim of this work is to theoretically determine the total resistance to soil pricking with a wedge-shaped tip to create a rectangular cavity and to determine the influence of the size of the working equipment and soil environment in the repair of earthenware or areas where trench technology can-not be used. To determine the forces of the recess of the replaceable pilot, the law of change of soil pressure on the working surfaces of the working equipment was first determined, which is based on the idea of the change of the soil elastic state at its compaction was determined, which is determined by the compression module of deformation of the soil. The processes occurring during the formation of wells and new approaches to the improvement of calculations have been described. On the basis of the pro-posed model of the piercing process, the laws of change of the normal pressure of soil resistance on the surface of the wedge working equipment are established. Based on its value, the results of theoretical studies have received a rational form and parameters of the tip of the work equipment.

Comprehensive evaluation of process parameters optimization for sheet piercing assisted by magnetic medium based on grey relational analysis

With the promotion of advanced manufacturing concepts such as green, high efficiency and intelligence, the shortboard and development bottleneck of traditional forming technology are increasingly prominent. The traditional forming technology is difficult to meet the actual needs of modern production. Special forming methods have emerged. The piercing process of sheet assisted by magnetic medium is an innovative attempt. However, there are many factors that affect the process, and the multi-field coupling further improves the process complexity, so it is very important to design the experimental scheme scientifically and reasonably. In this paper, through the design of orthogonal experiment, the piercing experiments are carried out under the condition of various process parameters, and then with the help of the grey correlation theory analysis, the relative rollover and the width of the relative bright zone are taken as the evaluation indexes. Through the analysis of range and analysis of variance, to find the key factors affecting the quality of piercing, determine the best combination of process parameters, and verify the accuracy of the results by confirming the test. The results show that: the best process combination scheme is A2B3C2D3. The experiments were carried out according to the recommended optimization scheme, the relative rollover reduced to 1.19%, and the proportion of the width of relative bright area reaches 64.06%. This paper provides scientific guidance for the research and quality improvement of piercing technology assisted by magnetic medium.

The design of a semi-additive manufacturing shape using metal 3D printing for a partially strengthened mold based on a high-alloy tool steel powder

In this paper, describe the fabrication of high strength punch molds that can be applied to ultra-high strength sheet materials after processing. A method for improving the strength of the punching die by additive manufacturing (AM) of a high strength powder material using a metal 3D printer was proposed. Furthermore, a semi-additive technique was proposed to increase the punch strength through partial AM of specific parts of the punch that require high strength. A preprocessing process for predicting the semi-additive shape for the punch function portion is proposed for application of the AM technology of a metal 3D printer to this semi-additive technique. The preprocessing for determining the semi-additive shape consists of the predicting step of the punch strength based on the shear process of the sheet material, analyzing step the stress distribution of the punch, defining step the semi-additive range, designing step the semi-additive shape, and verifying step the additive interface strength. Based on this simulation, the range of shapes for the semi-additive was 1.21 mm and 2.62 mm for sheet material CP1180 and 1.3 mm and 3.2 mm for sheet material 22MnB5. The shape and range determined in the simulation process defines a semi-additive area (volume) for the 3D printing AM technique using a high-strength powder material, and a semi-additive punch was manufactured according to the defined area. The semi-additive punch (HWS powder material) fabricated in this study was performed a durability test for validity verification in the piercing process of high-strength sheet material (CR980). This validation test compared the state of the punch after 1000 piercing processes with a typical cold piercing punch (SKD11 solid material). From this test, the feasibility of the semi-additive punch was confirmed by showing a similar state of scratches and abrasion from the two punches. The simulation analysis processor for the additive shape and the additive range prediction for the semi-additive punch manufacturing presented in this paper can be useful for the additive manufacture of cutting and trimming punch mold.

Investigation of the characteristics of a fiber-optic gas-liquid two-phase flow sensor.

A laboratory-prepared wedge-shaped fiber probe using step-index multimode plastic optical fiber was described and tested in a lab-scale gas-liquid flow generator. A three-dimensional model was established in order to fully simulate the process of bubble piercing by the optical fiber probe. A theoretical analysis of the luminous intensity distribution of the light transmission in the process of bubble piercing was undertaken under conditions of different relative positions between the fiber probe and the bubble axis. Using this analytical method, it was possible to accurately define the range of the central region of the bubble where the presignal appeared.

A Useful Manufacturing Guide for Rotary Piercing Seamless Pipe by ALE Method

The development of numerical simulations is potentially useful in predicting the most suitable manufacturing processes and ultimately improving product quality. Seamless pipes are manufactured by a rotary piercing process in which round billets (workpiece) are fed between two rolls and pierced by a stationary plug. During this process, the material undergoes severe deformation which renders it impractical to be modelled and analysed with conventional finite element methods. In this paper, three-dimensional numerical simulations of the piercing process are performed with an arbitrary Lagrangian–Eulerian (ALE) formulation in LS-DYNA software. Details about the material model as well as the elements’ formulations are elaborated here, and mesh sensitivity analysis was performed. The results of the numerical simulations are in good agreement with experimental data found in the literature and the validity of the analysis method is confirmed. The effects of varying workpiece velocity, process temperature, and wall thickness on the maximum stress levels of the product material/pipes are investigated by performing simulations of sixty scenarios. Three-dimensional surface plots are generated which can be utilized to predict the maximum stress value at any given combination of the three parameters.

Application of an Incremental Constitutive Model for the FE Analysis of Material Dynamic Restoration in the Rotary Tube Piercing Process.

In the numerical simulation of hot forming processes, the correct description of material flow stress is very important for the accuracy of the results. For complex manufacturing processes, such as the rotary tube piercing (RTP), constitutive laws based on both power and exponential mathematical expressions are commonly used due to its inherent simplicity, despite the limitations that this approach involves, namely, the use of accumulated strain as a state parameter. In this paper, a constitutive model of the P91 steel derived from the evolution of dislocation density with strain, which takes into account the mechanisms of dynamic recovery (DRV) and dynamic recrystallization (DRX), is proposed for the finite element (FE) analysis of the RTP process. The material model is developed in an incremental manner to allow its implementation in the FE code FORGE®. The success of this implementation is confirmed by the good correlation between results of the simulation and experimental measurements of the manufactured tube (elongation, twist angle, mean wall thickness and eccentricity). In addition, this incremental model allows addressing how the restoring mechanisms of DRV and DRV occur during the RTP process. The analysis puts into evidence that DRV and DRX prevail over each other cyclically, following an alternating sequence during the material processing, due mainly to the effect of the strain rate on the material.

On One Controllability of the Schrödinger Equation as Coupled with the Atomic-Level Mannesmann Effect

In this paper we outline a certain way of understanding of macroscopically uncontrollable emergence of the so called Mannesmann effect by means of its induced controllable quantum-mechanical background. In other words, we factually present a modus operandi of how to avoid macroscopic models of specific atomic-level cavity origin based consequently on a classical fracture mechanics theory. Under such circumstances, the target solution of the controllable microscopic model cannot be determined, since it can obviously arise only as a macroscopic state of the structurally disturbed rolled metal semi-product during the Mannesmann process. We obtain this irrelevance of the target solution, using a very special kind of control of the famous Schrödinger equation employed as a fundamental model equation here. We show contextually that such control follows from some very elementary aspects of the group theory conditioning a physical meaning of the Schrödinger equation written in a controllable form. We specially emerge primary cyclic groups of symmetry of special solutions to the Schrödinger equation. Their imaginary part is given by a control satisfying the Klein-Gordon equation which can be driven (through a specific avoidance of the cyclic group Z4) into a connection with the characteristic series of primary cyclic groups and/or torsion groups respectively. We obtain a physically controllable special results representing a strange correspondence between a certain LET (Linear Energy Transfer) and “quantum-like” tunnelling interpreted for some “everyday” objects, particularly for the considered Mannesmann piercing process with a torsion known from metallurgy. The process violations are shown and further reflected via a standard finite element method (FEM) simulation.

Analysis of Wall Thickness Eccentricity in the Rotary Tube Piercing Process Using a Strain Correlated FE Model

The wall thickness eccentricity is one of the most important weaknesses that appears in seamless tubes production, since this imperfection is subsequently transferred downstream through the manufacturing stages until the final product. For this reason, in this article a finite element model of the rotary tube piercing (RTP) process is developed aimed at analysing the wall thickness eccentricity imperfection. Experimental data extracted from the industrial process is used for the validation of the model, including operational process variables like power consumption and process velocity, and deformation variables as elongation and longitudinal torsion, originated by axial and shear strain respectively. The cause of longitudinal torsion is also analysed. The two most important conclusions derived from this study are: (I) the longitudinal torsion of the tube is a crucial parameter for the correct model validation, and (II) the combined effect between the uneven temperature distribution of the billet and the plug bending deformation is identified as the major cause of the wall thickness eccentricity flaw.

Laser Drilling of Microholes in Glass

The results of the successful laser drilling of 30 – 200 μm in diameter microholes in glass ranging in thickness from 0.1 to 0.8 mm are reported. High-quality holes together with high process performance are achieved by using in the hole piercing process an immersion cooling liquid in contact with the bottom surface of the glass.

Simultaneous Nano-Texturing onto a CVD-Diamond Coated Piercing Punch with Femtosecond Laser Trimming

In this study, a CVD (Chemical Vapor Deposition)-diamond coated tungsten carbide cobalt (WC (Co)) punch was trimmed to adjust its surface roughness and to significantly reduce its edge curvature for fine piercing by femtosecond laser processing. Through this laser trimming, the surface quality of the diamond coating and the punch edge profile were improved to less than 0.5 μm at the maximum roughness and 2 μm in the edge width, respectively. In parallel with this improvement of surface quality, the side surface of the diamond coating was modified to include nano-textures via the LIPSS (Laser Induced Periodic Surface Structuring) process. Through the fine piercing process, this nanotexture was transcribed onto the pierced hole surface together with fine shearing of the hole by piercing. WLI (White-Light Interferometry) and SEM (Scanning Electron Microscopy) were utilized to describe this transcription of nanotextures during the piercing process. These semiregular nanotextures with an LIPSS period of 300 nm on the pierced hole surface induced a blue colored surface plasmon.

The Effects of Cryogenic Process on the AISI M2 Punch Materials and on the Hole Edge Geometry of the DIN EN 10111‐98 Sheet Metal Control Arm Parts

In this study, not only the effects of cryogenic processing on the wear of AISI M2 punches but also the effects of punch wear on the hole edge geometry of DIN EN 10111‐98 sheet metal control arm parts were investigated. The hole geometry changes are generally associated with punch wear and process parameters. Piercing operations were performed using eccentric press on 2.5‐mm‐thick sheet metal control arm parts with circular and slot AISI M2 tool steel punches. The punches were traditionally heat treated. The others were cryogenically treated at −145°C in addition to the conventional heat treatment. Weight losses were measured for punch wear assessments; furthermore, SEM and OM images were analyzed. The hole edge geometries of the selected parts were measured with a contour measuring machine in the specified number of blanks. So, no damage was done to the products for measurements. The cryogenic process resulted in a significantly low amount of retained austenite and caused uniformly distributed thin carbide precipitates. Reduction of retained austenite and formation of fine carbide particles led to increase in hardness values. It was found that untreated circular punch wear weight losses were approximately 40% higher than those of cryogenically treated samples. The untreated slot punch change rate was about 106% higher than that of the cryogenically treated samples. The wear process during the punching was faster and greater for the untreated punches. Fatigue microcracks were more common at the cutting edge of the untreated punches. However, abrasive wear was generally observed in cryogenically treated punches. The edge geometry values in the circular holes were at least two times higher than those in the slot holes of untreated samples. At the end of the industrial piercing process, it was determined that the M2 tool steel punch wear rates were decreased by cryogenic treatment, and the size changes of the hole geometry of the punches of the DIN EN 10111‐98 control arm parts were more economic and with a better quality.

Experimental and numerical analysis of rotary tube piercing process for producing thick-walled tubes of nickel-base superalloy

Abstract In order to overcome the problems of existing methods for preparing thick-walled tubes of nickel-base superalloy (TWNS), the rotary tube piercing (RTP) process was proposed. For this purpose, an improved piercing mill was designed, and the influences of process parameters on strain, temperature, biting condition, lose stability of mandrel, defects control and microstructure distribution were studied by the combination of finite element model (FEM) and experiments. Based on the control variable method, the ranges of process parameters corresponding to the second biting condition and the critical condition of mandrel instability were determined by the simulation results. The experiment results indicate that the external separation layer defect (ESLD) is significantly affected by roll speed and reduction rate. The internal separation layer defect (ISLD) is mainly controlled by reduction rate. The preferred process parameters are determined as temperature 1040℃, reduction rate 13 %, roll speed 35 rpm, feed angle 8°, cross angle 15°, and plug advance against gorge 12 mm. The equiaxed grains with average grain size of 25 μm are obtained due to the complete dynamic recrystallization (DRX) process.

Design and Fabrication of Automatic Fuse Insertion Machine

Fireworks are a class of low explosive pyrotechnic devices used for aesthetic and entertainment purposes. In our project, we automate the fuse insertion process of the Chinese cracker (Bhijili). In India, the fuse insertion is done by handmade process. Due to handmade process, it creates serious health problems to the labours and it requires more labour, consumes more time. So, we planned to implement this process in a “PLC based automatic machine”. In which we combined Piercing, Dipping and Fuse Insertion. In reference of cracker manufacturing in China, they already had automatic fuse insertion, but they have a different procedure (chemical filling is done after the fuse insertion) compared to our country’s procedure, fuse is inserted after chemical filling. In our automation, we sequence the process of piercing and fuse insertion in an automatic manner. Advantage of our project are, increases productivity, reduced lead time, elimination of setup time, reduce the cost, fewer accident. For an emergency safety to the human and the surroundings, we use the fireball (mono ammonium phosphate) for the occasional fire accident which reduces the concentration of the blast in a few seconds.

The effects of shear affected zone on edge crack sensitivity in dual-phase steels

Dual phase steels offer good combination of mechanical properties which is attractive for automotive industry. However, some challenges still remain and suppress using them widely. One of these challenges is the formation of premature cracks at shear-cut edges during the subsequent forming processes, which cannot be predicted by the conventional finite element methods. Therefore, the present study aims to propose a numerical tool to predict edge cracks in DP steel components. In this regard, the hole expansion method was applied as an edge crack detection technique on DP1000 steel sheets. To elaborate the study, parallel finite element simulations were performed as well. The simulation method considered the whole hole piercing process and the following hole expansion test as a one-stroke two-step strategy. The hole piercing process was applied in the first step on the sheet and a hole was cut. The results reveal that this process forms some surface irregularities and applies a special amount of damage at the cut edge, which both could have effects on the edge crack sensitivity. To study these effects, the subsequent hole expansion test was simulated on the manufactured hole. Thus, the effects of both surface irregularities and residual damage from hole piercing process were investigated in different case studies with all possible combinations of these effects. This strategy provides possibilities to numerically separate effects of surface quality and residual damage. The contribution shows on the one hand the experimental investigations and on the other hand deals with the numerical influence analyses.

Research on piercing of aluminum sheet assisted with magnetic medium

At present, flexible die medium represented by fluid is mainly used in tube hydropiercing, but it is relatively rare in sheet forming field because of the high requirement of sealing. For this reason, magnetorheological fluid, one of the representatives of intelligent materials, is used as a force transfer medium to provide backpressure for the piercing process of sheet for the first time in this paper, so as to reduce the collapse and improve the quality of fracture surface. The results show that with the increase of internal pressure, the collapse of the area near the cutting edge of punch decreases, the length of burnish zone increases, the aperture is closer to the nominal diameter, and the quality of the hole is significantly improved. The theoretical mechanics model of a single straight chain is established through theoretical analysis, and the magnitude and loading mode of the force exerted on the sheet by magnetic medium are deduced. Through the balanced relationship between punching force and backpressure in the deformed area of sheet, the key parameters affecting the collapse of piercing of sheet are obtained, which has important guiding significance for improving the quality of sheet metal piercing products with magnetic medium.

Influence of Process Parameters in Laser Piercing

This work addresses the analysis of the influence of process parameters in laser piercing for mild steel, stainless steel, and aluminum thick sheets, carried out by the monitorization of the signal with a photodiode installed coaxially in the cutting head. The sensor captures the infrared or visible signal emitted during the piercing. The relationship between the intensity of the signal and the parameter values was analyzed, distinguishing between soft and fast piercings. The results permit the optimization of the piercing strategy with a reduction of 25% in time and the possibility of establishing a threshold to control the piercing process. This study reveals the importance of knowing parameter dependencies with the process results and highlights the potential of monitorization systems in laser cutting to improve the piercing duration and avoid wasting time during production.

Microstructure evolution of nickel-based superalloy with periodic thermal parameters during rotary tube piercing process

Due to the interaction of compression and torsion deformation, the grain refinement mechanism of rotary tube piercing (RTP) process is still ambiguous. Therefore, the microstructure evolution of a nickel-based superalloy was investigated by combining numerical simulations with experiments. By establishing a thermo-mechanical coupling finite element model (FEM), the evolution of temperature, strain, and strain rate for RTP process was studied quantitatively. The corresponding experiments were conducted on the independent-developed piercing mill, and the influences of reduction rate and roll speed on microstructure were discussed by the control variable method. The results reveal that the periodic shear strain components play a dominant role in the grain refinement process. Under single pass RTP process, the average grain size is refined from 130 to 25 μm. The microstructure is divided into three typical states: the coarse grains before entering the deformation region, the mixed grains in the preparation region, and the fine equiaxed grains in the uniform wall thickness region and rounding region. The reduction rate has significant effects on the dynamic recrystallization (DRX) process, and the uniformity of microstructure is determined by the roll speed.