Cold Backward Extrusion of Titanium Billet with Pulsating Lubricant Supply on Servo Press

2012 ◽  
Vol 504-506 ◽  
pp. 381-386 ◽  
Author(s):  
Ryo Matsumoto ◽  
Shinkichi Sawa ◽  
Hiroshi Utsunomiya
Keyword(s):  
Pure Titanium ◽  
Forming Limit ◽  
Structural Components ◽  
Liquid Lubricant ◽  
Backward Extrusion ◽  
Surface Observation ◽  
Internal Channel ◽  
Servo Press ◽  
Extrusion Method

To prevent seizure in backward extrusion of holes for lightweight structural components, an extrusion method utilizing a punch having an internal channel for supplying liquid lubricant to the punch nose was applied to forming of pure titanium billet using a servo press. On the servo press, the punch was pushed into the billet in a manner combining pulsed and stepwise modes. The sufficient amount of the liquid lubricant was pulsating supplied to the cavity formed at the bottom of the hole. Appropriate punch ram motion and forming limit for preventing seizure are determined from the surface observation of the formed hole and the punch.

Punch Wear in the Forming of Deep Holes with Pulse Ram Motion on a Servo Press

2014 ◽  
Vol 611-612 ◽  
pp. 127-133 ◽  
Author(s):  
Ryo Matsumoto ◽  
Hiroshi Utsunomiya
Keyword(s):  
Cold Extrusion ◽  
Low Friction ◽  
Element Analysis ◽  
Liquid Lubricant ◽  
Backward Extrusion ◽  
Servo Press ◽  
The Finite Element Analysis ◽  
The Relationship ◽  
Punch Wear ◽  
Extrusion Method

For the fabrication of lightweight components such as hollow components, we proposed a cold extrusion method for forming of deep holes that utilizes a punch with an internal channel for the supply of liquid lubricant using a servo press. The relationship between the punch ram motion and the punch wear in the proposed forming method is investigated by the finite element analysis in this study. The punch wear is determined by using the Archard’s equation. Although low friction at specimen–punch interface realizes in the forming with pulse punch ram motion (proposed forming method), the punch wear in the backward extrusion with pulse punch ram motion is 1.1–2.4 times larger than that with no pulse punch ram motion (conventional forming method). The influence of punch ram motion and friction on the punch wear is discussed.

scholarly journals Forming Limit Stress Diagram Prediction of Pure Titanium Sheet Based on GTN Model

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1783 ◽  
Author(s):  
Tao Huang ◽  
Mei Zhan ◽  
Kun Wang ◽  
Fuxiao Chen ◽  
Junqing Guo ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Pure Titanium ◽  
Void Volume Fraction ◽  
Void Volume ◽  
Forming Limit ◽  
Stress And Strain ◽  
Gtn Model ◽  
Stress Diagram ◽  
Limit Stress ◽  
Hemispherical Punch

In this paper, the initial values of damage parameters in the Gurson–Tvergaard–Needleman (GTN) model are determined by a microscopic test combined with empirical formulas, and the final accurate values are determined by finite element reverse calibration. The original void volume fraction (f0), the volume fraction of potential nucleated voids (fN), the critical void volume fraction (fc), the void volume fraction at the final failure (fF) of material are assigned as 0.006, 0.001, 0.03, 0.06 according to the simulation results, respectively. The hemispherical punch stretching test of commercially pure titanium (TA1) sheet is simulated by a plastic constitutive formula derived from the GTN model. The stress and strain are obtained at the last loading step before crack. The forming limit diagram (FLD) and the forming limit stress diagram (FLSD) of the TA1 sheet under plastic forming conditions are plotted, which are in good agreement with the FLD obtained by the hemispherical punch stretching test and the FLSD obtained by the conversion between stress and strain during the sheet forming process. The results show that the GTN model determined by the finite element reverse calibration method can be used to predict the forming limit of the TA1 sheet metal.

scholarly journals Piercing and Surface-Crack Defects in Cold Combined Forward-Backward Extrusion

2021 ◽  
Vol 11 (9) ◽  
pp. 3900
Author(s):  
Heng-Sheng Lin ◽  
Chien-Yu Lee ◽  
Wen-Shun Li
Keyword(s):  
Surface Crack ◽  
Metal Flow ◽  
Forming Limit Diagram ◽  
Extrusion Ratio ◽  
Forming Limit ◽  
Element Analysis ◽  
Backward Extrusion ◽  
The Finite Element Analysis ◽  
Fracture Damage ◽  
Fracturing Mechanism

Metal flow tends to be complex and difficult to predict in the combined forward-backward extrusion (CFBE) process. Piercing and surface-crack defects are phenomenal in forming fasteners featuring a forward extruded pin and a backward extruded cup. In this work, a series of the CFBE tests with various combinations of the forward extrusion ratio (FER) and the backward extrusion ratio (BER) were conducted. A forming limit diagram, detailed with the piercing and surface-crack defects on the forward extruded pin or the backward extruded cup, was developed to provide a conception in choosing appropriate extrusion ratios in forming fasteners with such pin-and-cup features. With the aid of the forming load-stroke curves and the finite element analysis of fracture damage, the fracturing mechanism for the CFBE process was provided.

scholarly journals Effect of Edge Conditions on the Formability of Commercially Pure Titanium Sheet (Grade 2) at Room Temperature

2020 ◽  
Vol 321 ◽  
pp. 04027
Author(s):  
J.S. Kwame ◽  
E. Yakushina ◽  
P. Blackwell
Keyword(s):  
Room Temperature ◽  
Pure Titanium ◽  
Forming Limit ◽  
Crystallographic Structure ◽  
Commercially Pure Titanium ◽  
Edge Conditions ◽  
Edge Surface ◽  
Awj Cutting ◽  
Very High ◽  
Hemispherical Punch

Titanium and its alloys are difficult to form, particularly at room temperature, due to their crystallographic structure and limited availability of slip systems. Such limited formability could be exacerbated by virtue of the technique used to cut the sheet. Forming limit diagrams will not necessarily recognize such effects, which can lead to failures during forming trials. An example of a situation where this could be demonstrated is in sheet with pre-fabricated holes. This work used a hemispherical punch to stretch in-plane a 20mm diameter hole prepared with laser, EDM and AWJ cutting techniques in order to quantify the edge formability of the material. It was identified that, the edge surface conditions have a major impact on the edge formability of the material. The edges of the material prepared with EDM showed very high formability tendencies compared with AWJ and laser cutting. The work proposed an alternative characterization method that could be adopted for edge formability assessment.

Evaluation of Press Formability of Pure Titanium Sheets

2016 ◽  
Vol 716 ◽  
pp. 87-98 ◽  
Author(s):  
Quoc Tuan Pham ◽  
Young Suk Kim
Keyword(s):  
Strain Hardening ◽  
Pure Titanium ◽  
Yield Function ◽  
Forming Limit ◽  
Commercially Pure Titanium ◽  
Specific Strength ◽  
Force Criterion ◽  
Stress Strain Relation ◽  
Cp Ti ◽  
Press Formability

Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However compared with automotive steels and aluminum alloys, only limited research has been conducted on the plastic deformation characteristics and press formability of CP Ti sheets. In this study, the mechanical properties, including the anisotropic property and the stress-strain relation, of the CP Ti sheet are clarified in relation to press formability. A new proposed strain hardening model, Kim-Tuan equation, is successful in perfectly describing the stress evaluation for strain increment of this material during strain path. The forming limit curve (FLC) of the CP Ti sheet as a criterion for press formability was experimentally evaluated by punch stretching testing and analytically predicted via Hora’s modified maximum force criterion. The predicted FLC based on the Kim-Tuan strain hardening equation and the appropriate yield function correlates well with the experimental results of the punch stretching test.

Process capabilities of commercially pure titanium grade 2 formed through warm incremental sheet forming

2021 ◽  
pp. 095440542199566
Author(s):  
Pavan Kumar ◽  
Puneet Tandon
Keyword(s):  
Room Temperature ◽  
Fe Simulation ◽  
Pure Titanium ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Forming Limit ◽  
Commercially Pure Titanium ◽  
Wall Angle ◽  
Commercially Pure ◽  
Cp Ti

Commercially pure titanium (CP-Ti) Grade-2 has many applications due to its good weldability, strength, ductility, formability, and superior corrosion resistance. Although, CP-Ti Grade-2 can be formed at room temperature, however, it has lower ductility at room temperature. Therefore, heat treatment or thermal activation is required to increase its ductility and formability. In this paper, the process capabilities of CP-Ti Grade-2 to form the components through warm incremental sheet forming (ISF) has been investigated. To identify the optimal temperature at which CP-Ti Grade-2 sheets can be incrementally formed, straight groove tests were performed experimentally at various temperatures. Two geometries, namely, varying wall angle truncated cone, and constant wall angle truncated cone were used as test cases to evaluate the formability of CP-Ti Grade-2, in terms of limiting wall angle. The formability was also assessed through forming limit diagram obtained by Finite Element (FE) simulation. With forming limit damage criterion, fracture in the formed component was predicted with FE simulation using Abaqus Explicit software. To assess the process capabilities of CP-Ti Grade-2 sheet formed through warm ISF, thickness distribution, forming forces, geometrical accuracy, and surface roughness were analyzed through both FE simulation and experimental work.

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