A New Methodology to Manufacture Component by Closed Die Forging

Transcription

1 A New Methodology to Manufacture Component by Closed Die Forging Neeraj Deshpande 1, Ashutosh Sonawane 2, Tejas Deshpande 3, Aditya Deshmukh 4, Tukaram Sargar 5 1 UG Student, Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, neerajdeshpande89@gmail.com 2 UG Student, Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, ashutoshsonawane9@gmail.com 3 UG Student, Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, tdesh1991@gmail.com 4 UG Student, Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, adi.deshmukh1995@gmail.com 5 Assistant Professor, Department of Mechanical Engineering, Smt. Kashibai Navale College of Engineering, sargartukaram@gmail.com ABSTRACT Open die forging also known as free forging is mostly used for manufacturing simple parts whereas complex parts are manufactured through impression die forging. A complex geometry can be produced through open forging but it would be time consuming and expensive. The size of the component plays a significant role in the selection of type of forging method to be used. The heavy and massive components are traditionally manufactured by open forging as quantity of parts required is too small to justify the cost of dies. The parts produced through the open forging route require additional machining to fulfill the required surface finish specifications. During machining the grain flow lines get cut which results in a significant decrease in the strength of component. Another drawback of this process is that a highly skilled operator is required to give more accurate shape. In the present work a new method of manufacturing the component is demonstrated with primary objective of achieving near to shape of the component. The new method involves theoretically designing a closed die, analyzing the stresses developed in the die using analysis software. The next step is checking the feasibility of the process by using simulation software and providing the actual forging parameters. This completes the validation of the manufacturing process. The components manufactured by this process have shape close to the desired shape. Therefore minimum machining is required resulting in the reduction of machining cost and size of ingot required. Hence the presented method is more economical than open forging approach. This concept can be implemented for other similar geometry components. Keywords: Closed die, Forging, Net to shape, preform, simulation etc INTRODUCTION In this paper, a suggestion has been made to improve the existing forging process of a specific component by designing a split die for manufacturing the same component. The component for which the suggestions are made is a part used in the oil and gas sectors to control and maintain the flow from wellbore. The component is currently being manufactured by open forging. The hot ingot is held by the manipulator and press is used to give the desired shape to the component. The main drawback in this process is that the geometry of the component obtained is rough or net to shape is not achieved. Also a large amount of machining is required after forging to get the desired shape which cuts the grain flow of the material and reduces the strength of the component. The new process of manufacturing includes designing a closed die to make an I-shape preform in the next stage. The stress analysis of the dies is to be done in the ANSYS software. Lastly, computer simulation of the manufacturing process is done putting actual forging parameters. 920

2 1.1 Literature Review Forging process typically consists of two main types i.e. open-die forging and impression-die or closed-die forging. Open die forging is suitable for simple geometry components unlike complex discs, rings, crankshafts, axles etc. A significant machining is required after open die forging to achieve desired tolerances. Also the size of the job is a considerable factor for deciding the type of forging process. Open die forging also gives an advantage that the material grain flow is more continuous with increased fatigue resistance and strength of the component. The preform geometry of complex parts has a great impact on forging loads and material wastes. [1] presented a new algorithm involving the selection of primary preform geometry and secondly, improvements in the preform design. By eliminating the time consuming remeshing process, the ability of material flow simulation is increased. The trials performed on the two dies showed that the material waste can be reduced to 5.1% to 7.3% with decreasing forging force required [1]. [2] Proposed a new method of manufacturing curved workpieces by open-die forging in which the material flow is controlled by the manipulator displacements. The integrated forging and bending process combined with different steps of forming performed with the manipulator displacements, the influence of various process parameters on the workpiece curvature and geometry is discussed [2]. [3] Suggested that the material wasted in flash accounts for about 20-40% of original workpiece. The forged product cost can be reduced if the forging is performed in a closed die with minimum raw material required. The forging of complex parts is introduced with a new tooling concept. The new process has been checked by doing process simulations performing number of iterations, thereby eliminating the need to manufacture the expensive tooling [3]. 1.2 Objectives and Scope 1] Studying the component geometry and application. 2] Analysing the forging process to manufacture the component viz. Open-die forging. 3] Suggesting a new method of manufacturing the component i.e. in split-die. 4] Theoretical design of I-shaped preform and die and 3D model preparation 5] Stress and deformation analysis of I-shape die in ANSYS 14.5 putting the maximum forging force. 6] Checking feasibility of process by doing process simulation in DEFORM 3D. 2. THEORETICAL DIE DESIGN The following is the given component which is to be manufactured: Fig-1: Component Drawing 921

3 2.1 Forging Model/ Forging Drawing Forging model is prepared after adding allowances to the proof machine drawing i.e. component drawing. The two types of allowances added are: 1] Machining Allowance: It is around 20 mm added along the diameter of the component at various sections. 2] Shrinkage Allowance: For Steel, the shrinkage allowance is 1.3% of the dimensions of the component. The dimensions of as forged component are calculated as follows: Section Machined Component Dimensions As Forged Component Dimensions mm mm mm mm mm 706 mm Table No-1: Dimensions of as Forged Component Allowance over height = 25 mm. Therefore, As forged component height = = 721 mm 2.2 Calculation of Weights: (Note: Proof Machine weight, Net weight are calculated from Creo Paramteric Software) 1] Proof machine weight = Kg 2] Net Weight = Kg 3] Cut Weight = Net Weight + Scale Loss 4] Scale Loss = 7% of Net Wt. = Kg. Therefore Cut Weight = = 1534 Kg 5] Gross Weight = Cut Wt./0.88 = 1743 Kg The Net weight calculated by 3D models in Creo Parametric: Fig-2: As Forged Component 2.3 Dimensions of Ingot The ingot selected is the standard ingot available: Standard Ingot Diameter = 515 mm Standard ingot length = 921 mm 2.4 Dimensions of Die As internal profile of die is replica of outside profile of component. Therefore dimensions are calculated as above: Section Final Die Dimensions mm mm mm Table No-2: Dimensions of Die 922

4 2.5 Wall Thickness of Die The material selected for die is die steel having ultimate tensile strength of 1300 N/mm 2 σallowable = Sut / FOS = 1300 / 4 = 325 N/ mm 2 By using formula for Hoop Stress, σ Allowable = (P*d)/2*t, where, σallowable = Allowable Hoop Stress (N/mm^2) P = Internal pressure inside the die (N/mm^2) = N/mm^2 d = Internal diameter of die (mm) = 706 mm t = thickness of die (mm) d Thickness of die (t) = 2 σallowable Thickness of die (t) = mm 3. STRESS AND DEFORMATION ANALYSIS IN ANSYS 14.5 The stress analysis in ANSYS 14.5 has been done by putting the maximum forging force exerted inside the die cavity. Maximum force = 4000 Tons. The following table compares the analytical and numerical results: Stress Analytical Value FEA Axi-symmetric Value Allowable Hoop Stress Equivalent (von-mises) Stress (MPa) Hoop Stress (MPa) Formula: 2 2 σ = p (D +d ), D = Outer Dia. ( 2 2 ) = 325 MPa = MPa Table No.3- Comparison of Theoretical and FEA stresses As we can see that the actual stress by ANSYS is less than the theoretical design stress or allowable stress, the die design is safe. The maximum stress analysed by ANSYS i.e. Equivalent (von-mises) Stress is shown in the following figure: Fig-3: Equivalent (von-mises) Stress The deformation occurred in the die obtained by ANSYS results = mm 923

5 Fig-4: Total Deformation 4. PROCESS SIMULATION IN DEFORM 3D The actual process has been simulated using DEFORM 3D software to check feasibility of manufacturing: Fig-5: Process Simulation (Step-1) 924

6 Fig-6: Process Simulation (Step-9) CONCLUSION 1] The new method suggested for manufacturing the component is more economical compared to current process. 2] The method is more feasible and suitable to manufacture the component of same geometries. 3] The die design can be improved in future for similar part geometries. REFERENCES [1] M. Sedighi, S. Tokmechi, A New Approach to Preform Design in Forging Process of Complex Parts, journal of materials processing technology, Volume 197, Issues 1 3, 1 February [2] Martin Wolfgarten, Gerhard Hirt, New method for the manufacturing of curved workpieces by open-die forging, Manufacturing Technology, Volume 65, Issue 1, [3] Victor Vazquez, Taylan Altan, Die design for Flashless forging of complex parts, Journal of Materials Processing Technology, Volume 98, Issue 1, 15 January [4] P. Hartley a, I. Pillinger, Numerical simulation of the forging process, Computer Methods in Applied Mechanics and Engineering, Volume 195, Issues 48 49, 1 October