Forming of Dome and Inlet Parts of a High Pressure CNG Vessel by the Hot Spinning Process

2016 ◽  
Vol 40 (10) ◽  
pp. 887-894
Author(s):  
Kwang O Lee ◽  
Gun Young Park ◽  
Hyo Seo Kwak ◽  
Chul Kim
Keyword(s):  
High Pressure ◽  
Spinning Process ◽  
Hot Spinning Process

Numerical and Experimental Analysis of Attaching-Mandrel Process Under Multi-Pass Cold Spinning Process on Superalloy GH3030

2019 ◽  
Author(s):  
Li Zixuan ◽  
Shu Xuedao ◽  
Cen Zewei ◽  
Zhang Song
Keyword(s):  
Production Efficiency ◽  
Thickness Distribution ◽  
Grain Structure ◽  
Combination Method ◽  
Nickel Base Superalloy ◽  
Forming Quality ◽  
Spinning Process ◽  
Conventional Spinning ◽  
Hot Spinning Process ◽  
Nickel Base

Abstract The superalloy products formed by multi-pass conventional spinning are widely used in rotary forming parts with complex shapes. As the connection of each forming pass, the attaching-mandrel process has an important influence on forming quality and production efficiency. The hot spinning process is usually adopted in superalloy forming because its poor plasticity in normal temperature, meanwhile, it brings the poor surface quality of the parts and huge energy consumption. For this reason, the cold spinning and the attaching-mandrel process of nickel-base superalloy GH3030 are studied. The combination method of experiment and simulation is used to study the attaching-mandrel process based on one-forward-pass spinning process. The effects of pass pitch and the attaching-mandrel velocity on the tool forces, parts stress field, strain field and wall thickness distribution are analyzed. The microstructure of the part is divided into three layers: outer, middle and inner layer. The grain size of each layer is compared. Then the effect of different pass pitch on the grain structure is clarified. The results show that the reasonable pass pitch and the attaching-mandrel velocity can improve the forming quality and production efficiency. The multi-pass cold spinning process on superalloy GH3030 is feasible. The excessive pass pitch can cause seriously grain elongation, the grain boundaries are blurred, and even cracking.

scholarly journals Study on optimization of thermal spinning process of accumulator shell

2020 ◽  
Vol 21 (4) ◽  
pp. 402
Author(s):  
Bin Li ◽  
Yunan Li ◽  
Peihao Zhu ◽  
Wenpeng Ma ◽  
Yinhong Xiao ◽  
...  
Keyword(s):  
Response Surface Model ◽  
Spindle Speed ◽  
Surface Model ◽  
Multi Objective Optimization ◽  
Process Technology ◽  
Element Simulation ◽  
Maximum Wall Thickness ◽  
Spinning Process ◽  
Hot Spinning Process ◽  
Central Composite

In view of the shortcomings of the existing hot spinning process technology of the accumulator shell, a method for optimizing the multi-spinning process parameters is proposed. The Johnson-Cook constitutive model of the accumulator shell material – 34CrMo4 alloy steel − was established with its parameters obtained experimentally. The finite element simulation was carried out for the hot spinning and closing process. Based on which, three parameters with the greatest influence on the spinning formation were studied: spinning temperature, spindle speed and friction coefficient. Combined with the central composite test, the response surface model and the mapping relationship between the three parameters and the maximum mises stress as well as the maximum wall thickness increment of the shell were established. The Pareto optimized solution set was obtained through multi-objective optimization. Under the condition of not affecting product quality, the optimized solution with low spinning temperature and high spindle speed is selected to reduce energy loss and improve work efficiency. The results indicate that the optimized process is experimentally verified to reduce the process temperature by nearly 30 °C, and the efficiency is increased by 25%.

scholarly journals Research on Multipass Hot Spinning Process Technology of AZ80 Magnesium Alloy Shell

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Wei Liang ◽  
Lin Guan ◽  
Qiongying Lv ◽  
Zhigang Xing
Keyword(s):  
Magnesium Alloy ◽  
Process Parameters ◽  
Simulation Analysis ◽  
Preliminary Test ◽  
Process Technology ◽  
Az80 Magnesium Alloy ◽  
Spinning Process ◽  
Temperature Parameter ◽  
Technical Specifications ◽  
Hot Spinning Process

Combined with finite element numerical simulation analysis, the hot-spin forming technology of cylindrical AZ80 magnesium alloy parts was studied in the paper. The multipass hot-spin forming of magnesium alloy shell parts was simulated by the ABAQUS software to analyze the stress and strain distribution and change during spinning for the preliminary test process parameters in the magnesium alloy spinning test. Then, the process parameters were optimized during the hot spinning test, especially the matching relationship between temperature parameter and thinning rate parameter, and the hot spinning magnesium alloy shell parts with the expected technical specifications were finished.

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Prolonged Fixation Studies For Spaceflight

1973 ◽  
Vol 31 ◽  
pp. 332-333
Author(s):  
Robert Corbett ◽  
Delbert E. Philpott ◽  
Sam Black
Keyword(s):  
High Pressure ◽  
Living Systems ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Early Signs ◽  
Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

Cryosectioning plant roots prepared by high-pressure freezing

1987 ◽  
Vol 45 ◽  
pp. 662-663
Author(s):  
R.E. Crang ◽  
M. Mueller ◽  
K. Zierold
Keyword(s):  
High Pressure ◽  
Cell Walls ◽  
Plant Tissues ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Vitreous State ◽  
Radial Depth ◽  
Irregular Topography ◽  
Considerable Depth ◽  
Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

High-pressure freezing and freeze substitution of plant tissue

1992 ◽  
Vol 50 (1) ◽  
pp. 748-749
Author(s):  
William P. Sharp ◽  
Robert W. Roberson
Keyword(s):  
High Pressure ◽  
Cell Structure ◽  
Leaf Tissue ◽  
Freeze Substitution ◽  
Crystal Formation ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Components ◽  
Cold Metal ◽  
Brome Grass

The aim of ultrastructural investigation is to analyze cell architecture and relate a functional role(s) to cell components. It is known that aqueous chemical fixation requires seconds to minutes to penetrate and stabilize cell structure which may result in structural artifacts. The use of ultralow temperatures to fix and prepare specimens, however, leads to a much improved preservation of the cell’s living state. A critical limitation of conventional cryofixation methods (i.e., propane-jet freezing, cold-metal slamming, plunge-freezing) is that only a 10 to 40 μm thick surface layer of cells can be frozen without distorting ice crystal formation. This problem can be allayed by freezing samples under about 2100 bar of hydrostatic pressure which suppresses the formation of ice nuclei and their rate of growth. Thus, 0.6 mm thick samples with a total volume of 1 mm3 can be frozen without ice crystal damage. The purpose of this study is to describe the cellular details and identify potential artifacts in root tissue of barley (Hordeum vulgari L.) and leaf tissue of brome grass (Bromus mollis L.) fixed and prepared by high-pressure freezing (HPF) and freeze substitution (FS) techniques.

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