The necessary pressure to move the swage was signi. Swage autofrettage process is used for internal forming and sizing of gun barrels designed to withstand high internal pressures. Parametric analysis of the mandrel geometrical data in a. Swaging is used in the metalworking field, known as metallurgy, to serve a variety of purposes. Optimization of mechanical swage autofrettage process h i g h l i g h t s optimum mandrelinner diameter interference ratio from which maximum benefit was obtained from swage autofrettage process was determined. In thermal autofrettage, the beneficial compressive residual stresses at the inner wall are produced by means of thermal gradient across the wall thickness. This process produces favorable compressive residual hoop stresses at the bore of the gun barrel, and results in an increas e in the life of the component. Us8408033b2 autofrettage process and autofrettage apparatus.
Jun 30, 2016 thermal autofrettage is a potential process to generate beneficial compressive residual stresses at and around the inner wall of a thickwalled cylinder for increasing its pressure carrying capacity. The idea of thermal autofrettage has been conceived recently, and due to its simplicity, it has the potential to be competitive with the existing hydraulic and swage autofrettage processes. Residual stress analysis of swage autofrettaged gun barrel. Pdf swage autofrettage process is used for internal forming and sizing of thick walled tubes designed to withstand high internal pressures. As a standard during autofrettage the pressure and strain on tube are recorded. The corresponding axisymmetric finite element model has been developed. Poelzl bohler hochdrucktechnik gmbh kapfenberg, austria abstract the autofrettage is an important procedure for components which are exposed to high and ultra high pressures. Swage autofrettage process is a low cost and simple way of sizing and profiling of internal surface of thickwalled tubes. The results show that the combined swage can not only meet the requirements of autofrettage, but. Jul 11, 2015 residual stress analysis of swage autofrettaged gun barrel is performed in this study via finite element fe method. In order to compare the two autofrettage processes, the code is applied to two hypothetic 120 mm gun barrels simulating both swage and hydraulic autofrettage.
The interior space 5 of the workpiece 2 is filled with a fluid and closed so as to be pressuretight. In this process, a mandrel with a diameter slightly larger than that of the tube is pressed inside the tube and in so doing, creates the internal profile. Swage autofrettage is one of the methods used for increasing life time of tubes and thick wall cylinders under the dynamic loading condition. Theoretical and finiteelement modeling of autofrettage process in strainhardening thickwalled cylinders. Computer modeling of internal pressure autofrettage. Jan 01, 2007 swage autofrettage process is used for internal forming and sizing of thickwalled tubes designed to withstand high internal pressures. An alternative to hydraulic autofrettage is swage autofrettage in which a relatively short mandrel is forced along the inside of the tube. High pressures close to failure in the range of to 2000 mpa were necessary. Contact pressure and hoop stress at the interface as functions of 9 interference for a section in zone 2.
Oct 26, 2010 an alternative to hydraulic autofrettage is swage autofrettage in which a relatively short mandrel is forced along the inside of the tube. What is swaging process working of swaging machine what is swaging operation. The volume available to the fluid in the interior space 5 of the workpiece 2 is reduced by a displacement piston 19 which is moved into the. The design of tungsten carbide swage with a center hole is proposed, the interference between the cylindrical mandrel and the inner hole of the tungsten carbide swage is performed by thermal expansion and contraction to form a combined swage. Experimental assessment of residual stresses induced by. Aug 20, 2009 the autofrettage process is a method that produces tensile plastic deformation during the overloading of a pressure vessel which reverses and becomes compressive during unloading. Optimization of mechanical swage autofrettage process. In this paper, a twopass swage autofrettage process of a thickwalled cylinder was. Autofrettage is a metal fabrication technique in which a pressure vessel is subjected to enormous pressure, causing internal portions. In this work, a comparative study of the thermal autofrettage and the.
It is commonly used with solder terminals and printed circuit board pins for low to medium volume applications. The deformation and stress distribution during autofrettage are. A similar process in its effect is a swage process 3 or shotpeening one 4. The swage mandrel and the cylinder are made of tungsten carbide and steel, respectively. In this process, a swage with a diametrical interference with the barrel is forced to pass through bore, generating compressive residual stresses. Ha always produces compressive nearbore axial stress nbas but sa can produce dominant and highly tensile nbas. It highlights how the theory of plasticity and finite element modeling are applied in the modeling of autofrettage processes. Computer modeling of internal pressure autofrettage process. The object may be, for example, a pressure vessel or gun barrel.
Services a broad spectrum of cold forming services felss. The process is modeled as an iso numerical study on the swage autofrettage process. The detailed numerical comparison between the two different autofrettage processes points to the fact that the swage autofrettage process is superior to the hydraulic autofrettage process. The swaging technique captures the board between the.
A study on the tool geometry effects in the swage autofrettage process swage autofrettage is one of the methods used for increasing life time of tubes and thick wall cylinders under the dynamic loading condition. It is our recommendation that the checking of the after swage dimension of the swaged fitting is the most accurate indicator of a properly swaged termination. The autofrettage process is widely used in various industries. Pdf is there an ultimate autofrettage process researchgate. Residual stress analysis of swage autofrettaged gun barrel is performed in this study via finite element fe method. Residual stress calculation of swage autofrettage gun barrel. It is can sometimes be done as a hot working process and is considered forging. Introduction to swage assembly swage assembly is a method of mechanically fastening pin terminals to a circuit board, similar in style to riveting. Contact pressure and hoop stress at the interface as functions of 10 interference for a section in zone 3. A comparative study of thermal and hydraulic autofrettage. Autofrettage fundamentals, industrial applications and.
Swage autofrettage analysis current status and future. In this paper swage autofrettage process of thick walled tubes are simulated using abaqus commercial code and effect of tool design on the residual stress distribution are investigated. Afterward, the adopted abstract autofrettage is a procedure performed to improve the durability of high the effect of autofrettage on the valve house of the cutting head assembly of a water jet cutting machine. In this paper, the swage autofrettage process of a thickwalled cylinder has been numerically investigated. Computer modeling and optimization of swage autofrettage process of a thickwalled cylinder incorporating bauschinger effect. A general autofrettage model of a thickwalled cylinder based on tensilecompressive stressstrain curve of a material. Afterward, the adopted abstract autofrettage is a procedure performed to improve the durability of high the effect of autofrettage on the valve house of the cutting head. This paper presents an experimental and numerical study of this process.
Analysis of swage autofrettage in metal tube international. A numerical study of swage autofrettage of thickwalled. The autofrettage process is a method that produces tensile plastic deformation during the overloading of a pressure vessel which reverses and becomes compressive during unloading. The english origin of swaging dates back to the 19th century. The optimal design of gun barrels has two major goals. An oversized moving mandrel is forced inside the gun barrel, which deforms the material through physical interference.
Swage autofrettage is a more economical method to form beneficial residual stresses in the thick walled cylinders when it is compared with the hydraulic autofrettage method. The process is modeled axisymmetric using finite element analysis, and the effects of various friction coefficient are studied. Optimum autofrettage pressure of hydrogen valve using finite. Swage autofrettage process is a localized and dynamic deformation process. Swaging is usually a cold working process, but also may be hot worked.
A simple analysis of the swage autofrettage process dtic. Jan 10, 2020 the autofrettage process is widely used in various industries for increasing operating pressures for advanced industrial, automotive, aerospace and defense. Autofrettage procedure is based on the establishment. The autofrettage cold forming process for thickwalled cylinders has its origin in artillery. In addition to mechanical engineering, the development of processes and innovative solutions for industry 4. At the end of the autofrettage process, the permanent bore enlargement and residual stresses are calculated. The thermal process, because due to the relatively small. In this paper swage autofrettage process of thick walled tubes are simulated using abaqus commercial code and effect of tool. The effect of autofrettage on pressure bearing capacity of the barrel was investigated.
The process is carried out by pressing a plain or a profiled tool mandrel inside a thickwalled tube to create an internal profile andor size its internal diameter. A swage is the shaped tool used to transform an objects shape into the desired form by bending or shaping. All swage nipples are either manufactured from seamless pipe or bar material and have an available working pressure equivavlent to straight. Autofrettage causes steep stress gradients away from. Both goals can be simultaneously achieved by introducing a favorable residual stress field, through the barrels wall, commonly by the autofrettage process. Autofrettage fundamentals, industrial applications and benefits. The autofrettage process is widely used in various industries for increasing operating pressures for advanced industrial, automotive, aerospace and defense. Swaging is the actionoriented process for shaping a swage. A residual stress solution for the case of swage autofrettage assuming ideal elasticperfectly plastic behavior without bauschinger effect, is. Gun barrels showed a significant development in range, power and reliability because of the application of an innovative manufacturing process. The swage autofrettage technique is one of the modernized prestressing methods to enhance the load bearing capacity and fatigue life of all gun barrels.
Depending on the input data, the optimum autofrettage pressure, which is between 600 and 1,000 mpa, causes a permanent deformation of 20% to 35% of the cylinder wall. In the autofrettage process, a thickwalled workpiece 2 to undergo autofrettage is positioned in an autofrettage apparatus 1. Pdf download for design of twopass swage autofrettage processes of. The process is achieved by increasing elastic strength of a cylinder with various methods such as hydraulic pressurization, mechanical swaging, or by utilizing the pressure of a powder gas. The second and third steps may be repeated one or more times. In this process, a mandrel with a diameter slightly larger than that of the tube is pressed inside the cylinder. Swage autofrettage sa is far more complex than hydraulic autofrettage ha. The process is carried out by pressing a plain or a profiled tool mandrel inside a thickwalled tube to create an. Felss offers a broad spectrum of services for the cold forming of pipes and solid material. Multiple autofrettage the united states of america as. Optimum autofrettage pressure of hydrogen valve using. This paper analyzes thermal autofrettage for exploring the feasibility of its industrial exploitation.
After swage inspection procedures the crosby group. Forging is used in manufacturing and is a way of shaping metal with c. Investigate and quantify the hydrostatic pressure effect on strain gages used to measure the residual stresses induced during autofrettage. The goal of autofrettage is to increase the durability of the final product. In this paper swage autofrettage process of thick walled tubes are simulated using abaqus commercial code and effect of tool design. A twodimensional planestrain analysis is used to determine the contact pressure at different locations of the cylinder as a function of interference. Any overall correlation between sa and ha residual stresses is coincidental. The autofrettage coldforming process for thickwalled cylinders has its origin in artillery technology of the 19th century. Whilst hydraulic autofrettage is axisymmetric with engineering plane strain behavior, swage autofrettage involves a short axial cylindrical indentation created by a mandrel with appropriate slopes on either side of the flat section, which is forced along the length of the tube, fig. The elastoplastic material model with hardening and nonlinear strainkinematic hardening the bauschinger effect was adopted. What is swaging process working of swaging machine.
A numerical study of swage autofrettage of thickwalled tubes. Materials free fulltext parametric analysis of the. The detailed numerical comparison between the two different autofrettage processes points to the fact that the swage autofrettage process is. In the current study, swage autofrettage process, applied on to two thick walled cylinders. Thermal autofrettage is a potential process to generate beneficial compressive residual stresses at and around the inner wall of a thickwalled cylinder for increasing its pressure carrying capacity. An oversized moving mandrel is forced inside the gun barrel, which deforms the material through. Design of twopass swage autofrettage processes of thickwalled. Excellent earlier developmental work for hydraulic and mechanical swage autofrettage manufacturing processes were reported refs 1,2. Inthis paper, the internally pressure overloading autofrettage process will be numericallyinvestigated. The hydraulic autofrettage process was slow, expensive, and dangerous. Pdf in this paper, the swage autofrettage process of a thickwalled cylinder has been numerically investigated. A r t i c l e i n f o a b s t r a c t article history. Swage nipples msssp95 prochem manufactures, stocks and supplies a range of plain, bevelled and threaded concentric and eccentric swage nipples, from 8 1. This process produces favorable compressive residual hoop stresses at the bore of the pressure vessel, and results in an increase in the life of the component.
A manufacturing method includes a first step of performing swage autofrettage on an object. Swage assembly is a method of mechanically fastening pin terminals to a circuit board, similar in style to riveting. In this paper, the swage autofrettage process of a thickwalled cylinder has been numerically. A study on the tool geometry effects in the swage autofrettage.
This research work deals with the swage or mechanical autofrettage of metal tubes. Abstract the autofrettage pr ocess is a method that produces tensile plastic deformation in a gun barrel which reverses and becomes compressive during unloading. For increasing operating pressures for advanced industrial, automotive, aerospace and defence systems, the application of autofrettage process is required to improve component fatigue life. The cut wire process consists of cutting off cylinders of steel wire, rounding them by swaging and grinding them to final shape between two flat rotating disks, followed by annealing and polishing.
The hassle factor goes up exponentially when you have to swage primer pockets and keep that brass separate. Pdf a numerical study of swage autofrettage of thickwalled tubes. Autofrettage is a metal cold forming technique in which a pressure vessel is subjected to enormous pressure, causing internal portions of the part to yield plastically, resulting in internal compressive residual stresses once the pressure is released. Technology and modeling deals with the technology and modeling of autofrettage processes, explaining the subject in a lucid manner. The autofrettage process is a wellknown method to improve the working strength and fatigue life of thickwalled cylinders. Jun 24, 2019 the autofrettage process is widely used in various industries for increasing operating pressures for advanced industrial, automotive, aerospace and defense. This can be achieved through an energyefficient and safe twopass swage autofrettage process by generating a favorable compressive residual hoop stress field in the inner layer of the cylinder. Nov 01, 2015 autofrettage is a metal fabrication technique in which a pressure vessel is subjected to enormous pressure, causing internal portions of the part to yield plastically, resulting in internal.
The initial design of the benchmark pressure vessels was based on fea and material models currently used to simulate the autofrettage process to. Swage autofrettage process is used for internal forming and sizing of thickwalled tubes designed to withstand high internal pressures. Computer modeling and optimization of swage autofrettage. Design and analysis of the swage for swage autofrettage. Due to its simplicity and inexpensive arrangement, it can compete with the conventional hydraulic autofrettage process. A method of an estimation of an autofrettage pressure is developed in the presented work.